// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
 */
#include <uapi/linux/btf.h>
#include <linux/bpf-cgroup.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/stringify.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/perf_event.h>
#include <linux/ctype.h>
#include <linux/error-injection.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>
#include <linux/poison.h>
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/bpf_mem_alloc.h>
#include <net/xdp.h>
#include <linux/trace_events.h>
#include <linux/kallsyms.h>

#include "disasm.h"

static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        [_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};

enum bpf_features {
        BPF_FEAT_RDONLY_CAST_TO_VOID = 0,
        BPF_FEAT_STREAMS             = 1,
        __MAX_BPF_FEAT,
};

struct bpf_mem_alloc bpf_global_percpu_ma;
static bool bpf_global_percpu_ma_set;

/* bpf_check() is a static code analyzer that walks eBPF program
 * instruction by instruction and updates register/stack state.
 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
 *
 * The first pass is depth-first-search to check that the program is a DAG.
 * It rejects the following programs:
 * - larger than BPF_MAXINSNS insns
 * - if loop is present (detected via back-edge)
 * - unreachable insns exist (shouldn't be a forest. program = one function)
 * - out of bounds or malformed jumps
 * The second pass is all possible path descent from the 1st insn.
 * Since it's analyzing all paths through the program, the length of the
 * analysis is limited to 64k insn, which may be hit even if total number of
 * insn is less then 4K, but there are too many branches that change stack/regs.
 * Number of 'branches to be analyzed' is limited to 1k
 *
 * On entry to each instruction, each register has a type, and the instruction
 * changes the types of the registers depending on instruction semantics.
 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
 * copied to R1.
 *
 * All registers are 64-bit.
 * R0 - return register
 * R1-R5 argument passing registers
 * R6-R9 callee saved registers
 * R10 - frame pointer read-only
 *
 * At the start of BPF program the register R1 contains a pointer to bpf_context
 * and has type PTR_TO_CTX.
 *
 * Verifier tracks arithmetic operations on pointers in case:
 *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
 * 1st insn copies R10 (which has FRAME_PTR) type into R1
 * and 2nd arithmetic instruction is pattern matched to recognize
 * that it wants to construct a pointer to some element within stack.
 * So after 2nd insn, the register R1 has type PTR_TO_STACK
 * (and -20 constant is saved for further stack bounds checking).
 * Meaning that this reg is a pointer to stack plus known immediate constant.
 *
 * Most of the time the registers have SCALAR_VALUE type, which
 * means the register has some value, but it's not a valid pointer.
 * (like pointer plus pointer becomes SCALAR_VALUE type)
 *
 * When verifier sees load or store instructions the type of base register
 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
 * four pointer types recognized by check_mem_access() function.
 *
 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
 * and the range of [ptr, ptr + map's value_size) is accessible.
 *
 * registers used to pass values to function calls are checked against
 * function argument constraints.
 *
 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
 * It means that the register type passed to this function must be
 * PTR_TO_STACK and it will be used inside the function as
 * 'pointer to map element key'
 *
 * For example the argument constraints for bpf_map_lookup_elem():
 *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
 *   .arg1_type = ARG_CONST_MAP_PTR,
 *   .arg2_type = ARG_PTR_TO_MAP_KEY,
 *
 * ret_type says that this function returns 'pointer to map elem value or null'
 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
 * 2nd argument should be a pointer to stack, which will be used inside
 * the helper function as a pointer to map element key.
 *
 * On the kernel side the helper function looks like:
 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 * {
 *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 *    void *key = (void *) (unsigned long) r2;
 *    void *value;
 *
 *    here kernel can access 'key' and 'map' pointers safely, knowing that
 *    [key, key + map->key_size) bytes are valid and were initialized on
 *    the stack of eBPF program.
 * }
 *
 * Corresponding eBPF program may look like:
 *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
 *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
 *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 * here verifier looks at prototype of map_lookup_elem() and sees:
 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
 *
 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
 * and were initialized prior to this call.
 * If it's ok, then verifier allows this BPF_CALL insn and looks at
 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
 * returns either pointer to map value or NULL.
 *
 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
 * insn, the register holding that pointer in the true branch changes state to
 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
 * branch. See check_cond_jmp_op().
 *
 * After the call R0 is set to return type of the function and registers R1-R5
 * are set to NOT_INIT to indicate that they are no longer readable.
 *
 * The following reference types represent a potential reference to a kernel
 * resource which, after first being allocated, must be checked and freed by
 * the BPF program:
 * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
 *
 * When the verifier sees a helper call return a reference type, it allocates a
 * pointer id for the reference and stores it in the current function state.
 * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
 * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
 * passes through a NULL-check conditional. For the branch wherein the state is
 * changed to CONST_IMM, the verifier releases the reference.
 *
 * For each helper function that allocates a reference, such as
 * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
 * bpf_sk_release(). When a reference type passes into the release function,
 * the verifier also releases the reference. If any unchecked or unreleased
 * reference remains at the end of the program, the verifier rejects it.
 */

/* verifier_state + insn_idx are pushed to stack when branch is encountered */
struct bpf_verifier_stack_elem {
        /* verifier state is 'st'
         * before processing instruction 'insn_idx'
         * and after processing instruction 'prev_insn_idx'
         */
        struct bpf_verifier_state st;
        int insn_idx;
        int prev_insn_idx;
        struct bpf_verifier_stack_elem *next;
        /* length of verifier log at the time this state was pushed on stack */
        u32 log_pos;
};

#define BPF_COMPLEXITY_LIMIT_JMP_SEQ    8192
#define BPF_COMPLEXITY_LIMIT_STATES     64

#define BPF_GLOBAL_PERCPU_MA_MAX_SIZE  512

#define BPF_PRIV_STACK_MIN_SIZE         64

static int acquire_reference(struct bpf_verifier_env *env, int insn_idx);
static int release_reference_nomark(struct bpf_verifier_state *state, int ref_obj_id);
static int release_reference(struct bpf_verifier_env *env, int ref_obj_id);
static void invalidate_non_owning_refs(struct bpf_verifier_env *env);
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env);
static int ref_set_non_owning(struct bpf_verifier_env *env,
                              struct bpf_reg_state *reg);
static bool is_trusted_reg(const struct bpf_reg_state *reg);
static inline bool in_sleepable_context(struct bpf_verifier_env *env);
static const char *non_sleepable_context_description(struct bpf_verifier_env *env);
static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg);
static void scalar_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg);

static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
                              struct bpf_map *map,
                              bool unpriv, bool poison)
{
        unpriv |= bpf_map_ptr_unpriv(aux);
        aux->map_ptr_state.unpriv = unpriv;
        aux->map_ptr_state.poison = poison;
        aux->map_ptr_state.map_ptr = map;
}

static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
{
        bool poisoned = bpf_map_key_poisoned(aux);

        aux->map_key_state = state | BPF_MAP_KEY_SEEN |
                             (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
}

struct bpf_call_arg_meta {
        struct bpf_map_desc map;
        bool raw_mode;
        bool pkt_access;
        u8 release_regno;
        int regno;
        int access_size;
        int mem_size;
        u64 msize_max_value;
        int ref_obj_id;
        int dynptr_id;
        int func_id;
        struct btf *btf;
        u32 btf_id;
        struct btf *ret_btf;
        u32 ret_btf_id;
        u32 subprogno;
        struct btf_field *kptr_field;
        s64 const_map_key;
};

struct bpf_kfunc_meta {
        struct btf *btf;
        const struct btf_type *proto;
        const char *name;
        const u32 *flags;
        s32 id;
};

struct btf *btf_vmlinux;

static const char *btf_type_name(const struct btf *btf, u32 id)
{
        return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
}

static DEFINE_MUTEX(bpf_verifier_lock);
static DEFINE_MUTEX(bpf_percpu_ma_lock);

__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
        struct bpf_verifier_env *env = private_data;
        va_list args;

        if (!bpf_verifier_log_needed(&env->log))
                return;

        va_start(args, fmt);
        bpf_verifier_vlog(&env->log, fmt, args);
        va_end(args);
}

static void verbose_invalid_scalar(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg,
                                   struct bpf_retval_range range, const char *ctx,
                                   const char *reg_name)
{
        bool unknown = true;

        verbose(env, "%s the register %s has", ctx, reg_name);
        if (reg->smin_value > S64_MIN) {
                verbose(env, " smin=%lld", reg->smin_value);
                unknown = false;
        }
        if (reg->smax_value < S64_MAX) {
                verbose(env, " smax=%lld", reg->smax_value);
                unknown = false;
        }
        if (unknown)
                verbose(env, " unknown scalar value");
        verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval);
}

static bool reg_not_null(const struct bpf_reg_state *reg)
{
        enum bpf_reg_type type;

        type = reg->type;
        if (type_may_be_null(type))
                return false;

        type = base_type(type);
        return type == PTR_TO_SOCKET ||
                type == PTR_TO_TCP_SOCK ||
                type == PTR_TO_MAP_VALUE ||
                type == PTR_TO_MAP_KEY ||
                type == PTR_TO_SOCK_COMMON ||
                (type == PTR_TO_BTF_ID && is_trusted_reg(reg)) ||
                (type == PTR_TO_MEM && !(reg->type & PTR_UNTRUSTED)) ||
                type == CONST_PTR_TO_MAP;
}

static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg)
{
        struct btf_record *rec = NULL;
        struct btf_struct_meta *meta;

        if (reg->type == PTR_TO_MAP_VALUE) {
                rec = reg->map_ptr->record;
        } else if (type_is_ptr_alloc_obj(reg->type)) {
                meta = btf_find_struct_meta(reg->btf, reg->btf_id);
                if (meta)
                        rec = meta->record;
        }
        return rec;
}

bool bpf_subprog_is_global(const struct bpf_verifier_env *env, int subprog)
{
        struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux;

        return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL;
}

static bool subprog_returns_void(struct bpf_verifier_env *env, int subprog)
{
        const struct btf_type *type, *func, *func_proto;
        const struct btf *btf = env->prog->aux->btf;
        u32 btf_id;

        btf_id = env->prog->aux->func_info[subprog].type_id;

        func = btf_type_by_id(btf, btf_id);
        if (verifier_bug_if(!func, env, "btf_id %u not found", btf_id))
                return false;

        func_proto = btf_type_by_id(btf, func->type);
        if (!func_proto)
                return false;

        type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
        if (!type)
                return false;

        return btf_type_is_void(type);
}

static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
{
        struct bpf_func_info *info;

        if (!env->prog->aux->func_info)
                return "";

        info = &env->prog->aux->func_info[subprog];
        return btf_type_name(env->prog->aux->btf, info->type_id);
}

void bpf_mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog)
{
        struct bpf_subprog_info *info = subprog_info(env, subprog);

        info->is_cb = true;
        info->is_async_cb = true;
        info->is_exception_cb = true;
}

static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog)
{
        return subprog_info(env, subprog)->is_exception_cb;
}

static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
{
        return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK | BPF_RES_SPIN_LOCK);
}

static bool type_is_rdonly_mem(u32 type)
{
        return type & MEM_RDONLY;
}

static bool is_acquire_function(enum bpf_func_id func_id,
                                const struct bpf_map *map)
{
        enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;

        if (func_id == BPF_FUNC_sk_lookup_tcp ||
            func_id == BPF_FUNC_sk_lookup_udp ||
            func_id == BPF_FUNC_skc_lookup_tcp ||
            func_id == BPF_FUNC_ringbuf_reserve ||
            func_id == BPF_FUNC_kptr_xchg)
                return true;

        if (func_id == BPF_FUNC_map_lookup_elem &&
            (map_type == BPF_MAP_TYPE_SOCKMAP ||
             map_type == BPF_MAP_TYPE_SOCKHASH))
                return true;

        return false;
}

static bool is_ptr_cast_function(enum bpf_func_id func_id)
{
        return func_id == BPF_FUNC_tcp_sock ||
                func_id == BPF_FUNC_sk_fullsock ||
                func_id == BPF_FUNC_skc_to_tcp_sock ||
                func_id == BPF_FUNC_skc_to_tcp6_sock ||
                func_id == BPF_FUNC_skc_to_udp6_sock ||
                func_id == BPF_FUNC_skc_to_mptcp_sock ||
                func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
                func_id == BPF_FUNC_skc_to_tcp_request_sock;
}

static bool is_dynptr_ref_function(enum bpf_func_id func_id)
{
        return func_id == BPF_FUNC_dynptr_data;
}

static bool is_sync_callback_calling_kfunc(u32 btf_id);
static bool is_async_callback_calling_kfunc(u32 btf_id);
static bool is_callback_calling_kfunc(u32 btf_id);
static bool is_bpf_throw_kfunc(struct bpf_insn *insn);

static bool is_bpf_wq_set_callback_kfunc(u32 btf_id);
static bool is_task_work_add_kfunc(u32 func_id);

static bool is_sync_callback_calling_function(enum bpf_func_id func_id)
{
        return func_id == BPF_FUNC_for_each_map_elem ||
               func_id == BPF_FUNC_find_vma ||
               func_id == BPF_FUNC_loop ||
               func_id == BPF_FUNC_user_ringbuf_drain;
}

static bool is_async_callback_calling_function(enum bpf_func_id func_id)
{
        return func_id == BPF_FUNC_timer_set_callback;
}

static bool is_callback_calling_function(enum bpf_func_id func_id)
{
        return is_sync_callback_calling_function(func_id) ||
               is_async_callback_calling_function(func_id);
}

bool bpf_is_sync_callback_calling_insn(struct bpf_insn *insn)
{
        return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) ||
               (bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm));
}

bool bpf_is_async_callback_calling_insn(struct bpf_insn *insn)
{
        return (bpf_helper_call(insn) && is_async_callback_calling_function(insn->imm)) ||
               (bpf_pseudo_kfunc_call(insn) && is_async_callback_calling_kfunc(insn->imm));
}

static bool is_async_cb_sleepable(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        /* bpf_timer callbacks are never sleepable. */
        if (bpf_helper_call(insn) && insn->imm == BPF_FUNC_timer_set_callback)
                return false;

        /* bpf_wq and bpf_task_work callbacks are always sleepable. */
        if (bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
            (is_bpf_wq_set_callback_kfunc(insn->imm) || is_task_work_add_kfunc(insn->imm)))
                return true;

        verifier_bug(env, "unhandled async callback in is_async_cb_sleepable");
        return false;
}

bool bpf_is_may_goto_insn(struct bpf_insn *insn)
{
        return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_MAY_GOTO;
}

static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id,
                                        const struct bpf_map *map)
{
        int ref_obj_uses = 0;

        if (is_ptr_cast_function(func_id))
                ref_obj_uses++;
        if (is_acquire_function(func_id, map))
                ref_obj_uses++;
        if (is_dynptr_ref_function(func_id))
                ref_obj_uses++;

        return ref_obj_uses > 1;
}


static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots)
{
       int allocated_slots = state->allocated_stack / BPF_REG_SIZE;

       /* We need to check that slots between [spi - nr_slots + 1, spi] are
        * within [0, allocated_stack).
        *
        * Please note that the spi grows downwards. For example, a dynptr
        * takes the size of two stack slots; the first slot will be at
        * spi and the second slot will be at spi - 1.
        */
       return spi - nr_slots + 1 >= 0 && spi < allocated_slots;
}

static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                  const char *obj_kind, int nr_slots)
{
        int off, spi;

        if (!tnum_is_const(reg->var_off)) {
                verbose(env, "%s has to be at a constant offset\n", obj_kind);
                return -EINVAL;
        }

        off = reg->var_off.value;
        if (off % BPF_REG_SIZE) {
                verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
                return -EINVAL;
        }

        spi = bpf_get_spi(off);
        if (spi + 1 < nr_slots) {
                verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
                return -EINVAL;
        }

        if (!is_spi_bounds_valid(bpf_func(env, reg), spi, nr_slots))
                return -ERANGE;
        return spi;
}

static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS);
}

static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots)
{
        return stack_slot_obj_get_spi(env, reg, "iter", nr_slots);
}

static int irq_flag_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        return stack_slot_obj_get_spi(env, reg, "irq_flag", 1);
}

static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
{
        switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
        case DYNPTR_TYPE_LOCAL:
                return BPF_DYNPTR_TYPE_LOCAL;
        case DYNPTR_TYPE_RINGBUF:
                return BPF_DYNPTR_TYPE_RINGBUF;
        case DYNPTR_TYPE_SKB:
                return BPF_DYNPTR_TYPE_SKB;
        case DYNPTR_TYPE_XDP:
                return BPF_DYNPTR_TYPE_XDP;
        case DYNPTR_TYPE_SKB_META:
                return BPF_DYNPTR_TYPE_SKB_META;
        case DYNPTR_TYPE_FILE:
                return BPF_DYNPTR_TYPE_FILE;
        default:
                return BPF_DYNPTR_TYPE_INVALID;
        }
}

static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type)
{
        switch (type) {
        case BPF_DYNPTR_TYPE_LOCAL:
                return DYNPTR_TYPE_LOCAL;
        case BPF_DYNPTR_TYPE_RINGBUF:
                return DYNPTR_TYPE_RINGBUF;
        case BPF_DYNPTR_TYPE_SKB:
                return DYNPTR_TYPE_SKB;
        case BPF_DYNPTR_TYPE_XDP:
                return DYNPTR_TYPE_XDP;
        case BPF_DYNPTR_TYPE_SKB_META:
                return DYNPTR_TYPE_SKB_META;
        case BPF_DYNPTR_TYPE_FILE:
                return DYNPTR_TYPE_FILE;
        default:
                return 0;
        }
}

static bool dynptr_type_refcounted(enum bpf_dynptr_type type)
{
        return type == BPF_DYNPTR_TYPE_RINGBUF || type == BPF_DYNPTR_TYPE_FILE;
}

static void __mark_dynptr_reg(struct bpf_reg_state *reg,
                              enum bpf_dynptr_type type,
                              bool first_slot, int dynptr_id);


static void mark_dynptr_stack_regs(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *sreg1,
                                   struct bpf_reg_state *sreg2,
                                   enum bpf_dynptr_type type)
{
        int id = ++env->id_gen;

        __mark_dynptr_reg(sreg1, type, true, id);
        __mark_dynptr_reg(sreg2, type, false, id);
}

static void mark_dynptr_cb_reg(struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg,
                               enum bpf_dynptr_type type)
{
        __mark_dynptr_reg(reg, type, true, ++env->id_gen);
}

static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
                                        struct bpf_func_state *state, int spi);

static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                   enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        enum bpf_dynptr_type type;
        int spi, i, err;

        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return spi;

        /* We cannot assume both spi and spi - 1 belong to the same dynptr,
         * hence we need to call destroy_if_dynptr_stack_slot twice for both,
         * to ensure that for the following example:
         *      [d1][d1][d2][d2]
         * spi    3   2   1   0
         * So marking spi = 2 should lead to destruction of both d1 and d2. In
         * case they do belong to same dynptr, second call won't see slot_type
         * as STACK_DYNPTR and will simply skip destruction.
         */
        err = destroy_if_dynptr_stack_slot(env, state, spi);
        if (err)
                return err;
        err = destroy_if_dynptr_stack_slot(env, state, spi - 1);
        if (err)
                return err;

        for (i = 0; i < BPF_REG_SIZE; i++) {
                state->stack[spi].slot_type[i] = STACK_DYNPTR;
                state->stack[spi - 1].slot_type[i] = STACK_DYNPTR;
        }

        type = arg_to_dynptr_type(arg_type);
        if (type == BPF_DYNPTR_TYPE_INVALID)
                return -EINVAL;

        mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr,
                               &state->stack[spi - 1].spilled_ptr, type);

        if (dynptr_type_refcounted(type)) {
                /* The id is used to track proper releasing */
                int id;

                if (clone_ref_obj_id)
                        id = clone_ref_obj_id;
                else
                        id = acquire_reference(env, insn_idx);

                if (id < 0)
                        return id;

                state->stack[spi].spilled_ptr.ref_obj_id = id;
                state->stack[spi - 1].spilled_ptr.ref_obj_id = id;
        }

        return 0;
}

static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi)
{
        int i;

        for (i = 0; i < BPF_REG_SIZE; i++) {
                state->stack[spi].slot_type[i] = STACK_INVALID;
                state->stack[spi - 1].slot_type[i] = STACK_INVALID;
        }

        bpf_mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
        bpf_mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);
}

static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi, ref_obj_id, i;

        /*
         * This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot
         * be released by any dynptr helper. Hence, unmark_stack_slots_dynptr
         * is safe to do directly.
         */
        if (reg->type == CONST_PTR_TO_DYNPTR) {
                verifier_bug(env, "CONST_PTR_TO_DYNPTR cannot be released");
                return -EFAULT;
        }
        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return spi;

        if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
                invalidate_dynptr(env, state, spi);
                return 0;
        }

        ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id;

        /* If the dynptr has a ref_obj_id, then we need to invalidate
         * two things:
         *
         * 1) Any dynptrs with a matching ref_obj_id (clones)
         * 2) Any slices derived from this dynptr.
         */

        /* Invalidate any slices associated with this dynptr */
        WARN_ON_ONCE(release_reference(env, ref_obj_id));

        /* Invalidate any dynptr clones */
        for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) {
                if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id)
                        continue;

                /* it should always be the case that if the ref obj id
                 * matches then the stack slot also belongs to a
                 * dynptr
                 */
                if (state->stack[i].slot_type[0] != STACK_DYNPTR) {
                        verifier_bug(env, "misconfigured ref_obj_id");
                        return -EFAULT;
                }
                if (state->stack[i].spilled_ptr.dynptr.first_slot)
                        invalidate_dynptr(env, state, i);
        }

        return 0;
}

static void __mark_reg_unknown(const struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg);

static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        if (!env->allow_ptr_leaks)
                bpf_mark_reg_not_init(env, reg);
        else
                __mark_reg_unknown(env, reg);
}

static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
                                        struct bpf_func_state *state, int spi)
{
        struct bpf_func_state *fstate;
        struct bpf_reg_state *dreg;
        int i, dynptr_id;

        /* We always ensure that STACK_DYNPTR is never set partially,
         * hence just checking for slot_type[0] is enough. This is
         * different for STACK_SPILL, where it may be only set for
         * 1 byte, so code has to use is_spilled_reg.
         */
        if (state->stack[spi].slot_type[0] != STACK_DYNPTR)
                return 0;

        /* Reposition spi to first slot */
        if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
                spi = spi + 1;

        if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
                int ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id;
                int ref_cnt = 0;

                /*
                 * A referenced dynptr can be overwritten only if there is at
                 * least one other dynptr sharing the same ref_obj_id,
                 * ensuring the reference can still be properly released.
                 */
                for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
                        if (state->stack[i].slot_type[0] != STACK_DYNPTR)
                                continue;
                        if (!state->stack[i].spilled_ptr.dynptr.first_slot)
                                continue;
                        if (state->stack[i].spilled_ptr.ref_obj_id == ref_obj_id)
                                ref_cnt++;
                }

                if (ref_cnt <= 1) {
                        verbose(env, "cannot overwrite referenced dynptr\n");
                        return -EINVAL;
                }
        }

        mark_stack_slot_scratched(env, spi);
        mark_stack_slot_scratched(env, spi - 1);

        /* Writing partially to one dynptr stack slot destroys both. */
        for (i = 0; i < BPF_REG_SIZE; i++) {
                state->stack[spi].slot_type[i] = STACK_INVALID;
                state->stack[spi - 1].slot_type[i] = STACK_INVALID;
        }

        dynptr_id = state->stack[spi].spilled_ptr.id;
        /* Invalidate any slices associated with this dynptr */
        bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({
                /* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */
                if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM)
                        continue;
                if (dreg->dynptr_id == dynptr_id)
                        mark_reg_invalid(env, dreg);
        }));

        /* Do not release reference state, we are destroying dynptr on stack,
         * not using some helper to release it. Just reset register.
         */
        bpf_mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
        bpf_mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);

        return 0;
}

static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        int spi;

        if (reg->type == CONST_PTR_TO_DYNPTR)
                return false;

        spi = dynptr_get_spi(env, reg);

        /* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an
         * error because this just means the stack state hasn't been updated yet.
         * We will do check_mem_access to check and update stack bounds later.
         */
        if (spi < 0 && spi != -ERANGE)
                return false;

        /* We don't need to check if the stack slots are marked by previous
         * dynptr initializations because we allow overwriting existing unreferenced
         * STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls
         * destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are
         * touching are completely destructed before we reinitialize them for a new
         * one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early
         * instead of delaying it until the end where the user will get "Unreleased
         * reference" error.
         */
        return true;
}

static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int i, spi;

        /* This already represents first slot of initialized bpf_dynptr.
         *
         * CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to
         * check_func_arg_reg_off's logic, so we don't need to check its
         * offset and alignment.
         */
        if (reg->type == CONST_PTR_TO_DYNPTR)
                return true;

        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return false;
        if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
                return false;

        for (i = 0; i < BPF_REG_SIZE; i++) {
                if (state->stack[spi].slot_type[i] != STACK_DYNPTR ||
                    state->stack[spi - 1].slot_type[i] != STACK_DYNPTR)
                        return false;
        }

        return true;
}

static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                    enum bpf_arg_type arg_type)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        enum bpf_dynptr_type dynptr_type;
        int spi;

        /* ARG_PTR_TO_DYNPTR takes any type of dynptr */
        if (arg_type == ARG_PTR_TO_DYNPTR)
                return true;

        dynptr_type = arg_to_dynptr_type(arg_type);
        if (reg->type == CONST_PTR_TO_DYNPTR) {
                return reg->dynptr.type == dynptr_type;
        } else {
                spi = dynptr_get_spi(env, reg);
                if (spi < 0)
                        return false;
                return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
        }
}

static void __mark_reg_known_zero(struct bpf_reg_state *reg);

static bool in_rcu_cs(struct bpf_verifier_env *env);

static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta);

static int mark_stack_slots_iter(struct bpf_verifier_env *env,
                                 struct bpf_kfunc_call_arg_meta *meta,
                                 struct bpf_reg_state *reg, int insn_idx,
                                 struct btf *btf, u32 btf_id, int nr_slots)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi, i, j, id;

        spi = iter_get_spi(env, reg, nr_slots);
        if (spi < 0)
                return spi;

        id = acquire_reference(env, insn_idx);
        if (id < 0)
                return id;

        for (i = 0; i < nr_slots; i++) {
                struct bpf_stack_state *slot = &state->stack[spi - i];
                struct bpf_reg_state *st = &slot->spilled_ptr;

                __mark_reg_known_zero(st);
                st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
                if (is_kfunc_rcu_protected(meta)) {
                        if (in_rcu_cs(env))
                                st->type |= MEM_RCU;
                        else
                                st->type |= PTR_UNTRUSTED;
                }
                st->ref_obj_id = i == 0 ? id : 0;
                st->iter.btf = btf;
                st->iter.btf_id = btf_id;
                st->iter.state = BPF_ITER_STATE_ACTIVE;
                st->iter.depth = 0;

                for (j = 0; j < BPF_REG_SIZE; j++)
                        slot->slot_type[j] = STACK_ITER;

                mark_stack_slot_scratched(env, spi - i);
        }

        return 0;
}

static int unmark_stack_slots_iter(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg, int nr_slots)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi, i, j;

        spi = iter_get_spi(env, reg, nr_slots);
        if (spi < 0)
                return spi;

        for (i = 0; i < nr_slots; i++) {
                struct bpf_stack_state *slot = &state->stack[spi - i];
                struct bpf_reg_state *st = &slot->spilled_ptr;

                if (i == 0)
                        WARN_ON_ONCE(release_reference(env, st->ref_obj_id));

                bpf_mark_reg_not_init(env, st);

                for (j = 0; j < BPF_REG_SIZE; j++)
                        slot->slot_type[j] = STACK_INVALID;

                mark_stack_slot_scratched(env, spi - i);
        }

        return 0;
}

static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env,
                                     struct bpf_reg_state *reg, int nr_slots)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi, i, j;

        /* For -ERANGE (i.e. spi not falling into allocated stack slots), we
         * will do check_mem_access to check and update stack bounds later, so
         * return true for that case.
         */
        spi = iter_get_spi(env, reg, nr_slots);
        if (spi == -ERANGE)
                return true;
        if (spi < 0)
                return false;

        for (i = 0; i < nr_slots; i++) {
                struct bpf_stack_state *slot = &state->stack[spi - i];

                for (j = 0; j < BPF_REG_SIZE; j++)
                        if (slot->slot_type[j] == STACK_ITER)
                                return false;
        }

        return true;
}

static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                   struct btf *btf, u32 btf_id, int nr_slots)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi, i, j;

        spi = iter_get_spi(env, reg, nr_slots);
        if (spi < 0)
                return -EINVAL;

        for (i = 0; i < nr_slots; i++) {
                struct bpf_stack_state *slot = &state->stack[spi - i];
                struct bpf_reg_state *st = &slot->spilled_ptr;

                if (st->type & PTR_UNTRUSTED)
                        return -EPROTO;
                /* only main (first) slot has ref_obj_id set */
                if (i == 0 && !st->ref_obj_id)
                        return -EINVAL;
                if (i != 0 && st->ref_obj_id)
                        return -EINVAL;
                if (st->iter.btf != btf || st->iter.btf_id != btf_id)
                        return -EINVAL;

                for (j = 0; j < BPF_REG_SIZE; j++)
                        if (slot->slot_type[j] != STACK_ITER)
                                return -EINVAL;
        }

        return 0;
}

static int acquire_irq_state(struct bpf_verifier_env *env, int insn_idx);
static int release_irq_state(struct bpf_verifier_state *state, int id);

static int mark_stack_slot_irq_flag(struct bpf_verifier_env *env,
                                     struct bpf_kfunc_call_arg_meta *meta,
                                     struct bpf_reg_state *reg, int insn_idx,
                                     int kfunc_class)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        struct bpf_stack_state *slot;
        struct bpf_reg_state *st;
        int spi, i, id;

        spi = irq_flag_get_spi(env, reg);
        if (spi < 0)
                return spi;

        id = acquire_irq_state(env, insn_idx);
        if (id < 0)
                return id;

        slot = &state->stack[spi];
        st = &slot->spilled_ptr;

        __mark_reg_known_zero(st);
        st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
        st->ref_obj_id = id;
        st->irq.kfunc_class = kfunc_class;

        for (i = 0; i < BPF_REG_SIZE; i++)
                slot->slot_type[i] = STACK_IRQ_FLAG;

        mark_stack_slot_scratched(env, spi);
        return 0;
}

static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                      int kfunc_class)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        struct bpf_stack_state *slot;
        struct bpf_reg_state *st;
        int spi, i, err;

        spi = irq_flag_get_spi(env, reg);
        if (spi < 0)
                return spi;

        slot = &state->stack[spi];
        st = &slot->spilled_ptr;

        if (st->irq.kfunc_class != kfunc_class) {
                const char *flag_kfunc = st->irq.kfunc_class == IRQ_NATIVE_KFUNC ? "native" : "lock";
                const char *used_kfunc = kfunc_class == IRQ_NATIVE_KFUNC ? "native" : "lock";

                verbose(env, "irq flag acquired by %s kfuncs cannot be restored with %s kfuncs\n",
                        flag_kfunc, used_kfunc);
                return -EINVAL;
        }

        err = release_irq_state(env->cur_state, st->ref_obj_id);
        WARN_ON_ONCE(err && err != -EACCES);
        if (err) {
                int insn_idx = 0;

                for (int i = 0; i < env->cur_state->acquired_refs; i++) {
                        if (env->cur_state->refs[i].id == env->cur_state->active_irq_id) {
                                insn_idx = env->cur_state->refs[i].insn_idx;
                                break;
                        }
                }

                verbose(env, "cannot restore irq state out of order, expected id=%d acquired at insn_idx=%d\n",
                        env->cur_state->active_irq_id, insn_idx);
                return err;
        }

        bpf_mark_reg_not_init(env, st);

        for (i = 0; i < BPF_REG_SIZE; i++)
                slot->slot_type[i] = STACK_INVALID;

        mark_stack_slot_scratched(env, spi);
        return 0;
}

static bool is_irq_flag_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        struct bpf_stack_state *slot;
        int spi, i;

        /* For -ERANGE (i.e. spi not falling into allocated stack slots), we
         * will do check_mem_access to check and update stack bounds later, so
         * return true for that case.
         */
        spi = irq_flag_get_spi(env, reg);
        if (spi == -ERANGE)
                return true;
        if (spi < 0)
                return false;

        slot = &state->stack[spi];

        for (i = 0; i < BPF_REG_SIZE; i++)
                if (slot->slot_type[i] == STACK_IRQ_FLAG)
                        return false;
        return true;
}

static int is_irq_flag_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        struct bpf_stack_state *slot;
        struct bpf_reg_state *st;
        int spi, i;

        spi = irq_flag_get_spi(env, reg);
        if (spi < 0)
                return -EINVAL;

        slot = &state->stack[spi];
        st = &slot->spilled_ptr;

        if (!st->ref_obj_id)
                return -EINVAL;

        for (i = 0; i < BPF_REG_SIZE; i++)
                if (slot->slot_type[i] != STACK_IRQ_FLAG)
                        return -EINVAL;
        return 0;
}

/* Check if given stack slot is "special":
 *   - spilled register state (STACK_SPILL);
 *   - dynptr state (STACK_DYNPTR);
 *   - iter state (STACK_ITER).
 *   - irq flag state (STACK_IRQ_FLAG)
 */
static bool is_stack_slot_special(const struct bpf_stack_state *stack)
{
        enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1];

        switch (type) {
        case STACK_SPILL:
        case STACK_DYNPTR:
        case STACK_ITER:
        case STACK_IRQ_FLAG:
                return true;
        case STACK_INVALID:
        case STACK_POISON:
        case STACK_MISC:
        case STACK_ZERO:
                return false;
        default:
                WARN_ONCE(1, "unknown stack slot type %d\n", type);
                return true;
        }
}

/* The reg state of a pointer or a bounded scalar was saved when
 * it was spilled to the stack.
 */

/*
 * Mark stack slot as STACK_MISC, unless it is already:
 * - STACK_INVALID, in which case they are equivalent.
 * - STACK_ZERO, in which case we preserve more precise STACK_ZERO.
 * - STACK_POISON, which truly forbids access to the slot.
 * Regardless of allow_ptr_leaks setting (i.e., privileged or unprivileged
 * mode), we won't promote STACK_INVALID to STACK_MISC. In privileged case it is
 * unnecessary as both are considered equivalent when loading data and pruning,
 * in case of unprivileged mode it will be incorrect to allow reads of invalid
 * slots.
 */
static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype)
{
        if (*stype == STACK_ZERO)
                return;
        if (*stype == STACK_INVALID || *stype == STACK_POISON)
                return;
        *stype = STACK_MISC;
}

static void scrub_spilled_slot(u8 *stype)
{
        if (*stype != STACK_INVALID && *stype != STACK_POISON)
                *stype = STACK_MISC;
}

/* copy array src of length n * size bytes to dst. dst is reallocated if it's too
 * small to hold src. This is different from krealloc since we don't want to preserve
 * the contents of dst.
 *
 * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could
 * not be allocated.
 */
static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
{
        size_t alloc_bytes;
        void *orig = dst;
        size_t bytes;

        if (ZERO_OR_NULL_PTR(src))
                goto out;

        if (unlikely(check_mul_overflow(n, size, &bytes)))
                return NULL;

        alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes));
        dst = krealloc(orig, alloc_bytes, flags);
        if (!dst) {
                kfree(orig);
                return NULL;
        }

        memcpy(dst, src, bytes);
out:
        return dst ? dst : ZERO_SIZE_PTR;
}

/* resize an array from old_n items to new_n items. the array is reallocated if it's too
 * small to hold new_n items. new items are zeroed out if the array grows.
 *
 * Contrary to krealloc_array, does not free arr if new_n is zero.
 */
static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
{
        size_t alloc_size;
        void *new_arr;

        if (!new_n || old_n == new_n)
                goto out;

        alloc_size = kmalloc_size_roundup(size_mul(new_n, size));
        new_arr = krealloc(arr, alloc_size, GFP_KERNEL_ACCOUNT);
        if (!new_arr) {
                kfree(arr);
                return NULL;
        }
        arr = new_arr;

        if (new_n > old_n)
                memset(arr + old_n * size, 0, (new_n - old_n) * size);

out:
        return arr ? arr : ZERO_SIZE_PTR;
}

static int copy_reference_state(struct bpf_verifier_state *dst, const struct bpf_verifier_state *src)
{
        dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs,
                               sizeof(struct bpf_reference_state), GFP_KERNEL_ACCOUNT);
        if (!dst->refs)
                return -ENOMEM;

        dst->acquired_refs = src->acquired_refs;
        dst->active_locks = src->active_locks;
        dst->active_preempt_locks = src->active_preempt_locks;
        dst->active_rcu_locks = src->active_rcu_locks;
        dst->active_irq_id = src->active_irq_id;
        dst->active_lock_id = src->active_lock_id;
        dst->active_lock_ptr = src->active_lock_ptr;
        return 0;
}

static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
        size_t n = src->allocated_stack / BPF_REG_SIZE;

        dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state),
                                GFP_KERNEL_ACCOUNT);
        if (!dst->stack)
                return -ENOMEM;

        dst->allocated_stack = src->allocated_stack;
        return 0;
}

static int resize_reference_state(struct bpf_verifier_state *state, size_t n)
{
        state->refs = realloc_array(state->refs, state->acquired_refs, n,
                                    sizeof(struct bpf_reference_state));
        if (!state->refs)
                return -ENOMEM;

        state->acquired_refs = n;
        return 0;
}

/* Possibly update state->allocated_stack to be at least size bytes. Also
 * possibly update the function's high-water mark in its bpf_subprog_info.
 */
static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size)
{
        size_t old_n = state->allocated_stack / BPF_REG_SIZE, n;

        /* The stack size is always a multiple of BPF_REG_SIZE. */
        size = round_up(size, BPF_REG_SIZE);
        n = size / BPF_REG_SIZE;

        if (old_n >= n)
                return 0;

        state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state));
        if (!state->stack)
                return -ENOMEM;

        state->allocated_stack = size;

        /* update known max for given subprogram */
        if (env->subprog_info[state->subprogno].stack_depth < size)
                env->subprog_info[state->subprogno].stack_depth = size;

        return 0;
}

/* Acquire a pointer id from the env and update the state->refs to include
 * this new pointer reference.
 * On success, returns a valid pointer id to associate with the register
 * On failure, returns a negative errno.
 */
static struct bpf_reference_state *acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
{
        struct bpf_verifier_state *state = env->cur_state;
        int new_ofs = state->acquired_refs;
        int err;

        err = resize_reference_state(state, state->acquired_refs + 1);
        if (err)
                return NULL;
        state->refs[new_ofs].insn_idx = insn_idx;

        return &state->refs[new_ofs];
}

static int acquire_reference(struct bpf_verifier_env *env, int insn_idx)
{
        struct bpf_reference_state *s;

        s = acquire_reference_state(env, insn_idx);
        if (!s)
                return -ENOMEM;
        s->type = REF_TYPE_PTR;
        s->id = ++env->id_gen;
        return s->id;
}

static int acquire_lock_state(struct bpf_verifier_env *env, int insn_idx, enum ref_state_type type,
                              int id, void *ptr)
{
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_reference_state *s;

        s = acquire_reference_state(env, insn_idx);
        if (!s)
                return -ENOMEM;
        s->type = type;
        s->id = id;
        s->ptr = ptr;

        state->active_locks++;
        state->active_lock_id = id;
        state->active_lock_ptr = ptr;
        return 0;
}

static int acquire_irq_state(struct bpf_verifier_env *env, int insn_idx)
{
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_reference_state *s;

        s = acquire_reference_state(env, insn_idx);
        if (!s)
                return -ENOMEM;
        s->type = REF_TYPE_IRQ;
        s->id = ++env->id_gen;

        state->active_irq_id = s->id;
        return s->id;
}

static void release_reference_state(struct bpf_verifier_state *state, int idx)
{
        int last_idx;
        size_t rem;

        /* IRQ state requires the relative ordering of elements remaining the
         * same, since it relies on the refs array to behave as a stack, so that
         * it can detect out-of-order IRQ restore. Hence use memmove to shift
         * the array instead of swapping the final element into the deleted idx.
         */
        last_idx = state->acquired_refs - 1;
        rem = state->acquired_refs - idx - 1;
        if (last_idx && idx != last_idx)
                memmove(&state->refs[idx], &state->refs[idx + 1], sizeof(*state->refs) * rem);
        memset(&state->refs[last_idx], 0, sizeof(*state->refs));
        state->acquired_refs--;
        return;
}

static bool find_reference_state(struct bpf_verifier_state *state, int ptr_id)
{
        int i;

        for (i = 0; i < state->acquired_refs; i++)
                if (state->refs[i].id == ptr_id)
                        return true;

        return false;
}

static int release_lock_state(struct bpf_verifier_state *state, int type, int id, void *ptr)
{
        void *prev_ptr = NULL;
        u32 prev_id = 0;
        int i;

        for (i = 0; i < state->acquired_refs; i++) {
                if (state->refs[i].type == type && state->refs[i].id == id &&
                    state->refs[i].ptr == ptr) {
                        release_reference_state(state, i);
                        state->active_locks--;
                        /* Reassign active lock (id, ptr). */
                        state->active_lock_id = prev_id;
                        state->active_lock_ptr = prev_ptr;
                        return 0;
                }
                if (state->refs[i].type & REF_TYPE_LOCK_MASK) {
                        prev_id = state->refs[i].id;
                        prev_ptr = state->refs[i].ptr;
                }
        }
        return -EINVAL;
}

static int release_irq_state(struct bpf_verifier_state *state, int id)
{
        u32 prev_id = 0;
        int i;

        if (id != state->active_irq_id)
                return -EACCES;

        for (i = 0; i < state->acquired_refs; i++) {
                if (state->refs[i].type != REF_TYPE_IRQ)
                        continue;
                if (state->refs[i].id == id) {
                        release_reference_state(state, i);
                        state->active_irq_id = prev_id;
                        return 0;
                } else {
                        prev_id = state->refs[i].id;
                }
        }
        return -EINVAL;
}

static struct bpf_reference_state *find_lock_state(struct bpf_verifier_state *state, enum ref_state_type type,
                                                   int id, void *ptr)
{
        int i;

        for (i = 0; i < state->acquired_refs; i++) {
                struct bpf_reference_state *s = &state->refs[i];

                if (!(s->type & type))
                        continue;

                if (s->id == id && s->ptr == ptr)
                        return s;
        }
        return NULL;
}

static void free_func_state(struct bpf_func_state *state)
{
        if (!state)
                return;
        kfree(state->stack);
        kfree(state);
}

void bpf_clear_jmp_history(struct bpf_verifier_state *state)
{
        kfree(state->jmp_history);
        state->jmp_history = NULL;
        state->jmp_history_cnt = 0;
}

void bpf_free_verifier_state(struct bpf_verifier_state *state,
                            bool free_self)
{
        int i;

        for (i = 0; i <= state->curframe; i++) {
                free_func_state(state->frame[i]);
                state->frame[i] = NULL;
        }
        kfree(state->refs);
        bpf_clear_jmp_history(state);
        if (free_self)
                kfree(state);
}

/* copy verifier state from src to dst growing dst stack space
 * when necessary to accommodate larger src stack
 */
static int copy_func_state(struct bpf_func_state *dst,
                           const struct bpf_func_state *src)
{
        memcpy(dst, src, offsetof(struct bpf_func_state, stack));
        return copy_stack_state(dst, src);
}

int bpf_copy_verifier_state(struct bpf_verifier_state *dst_state,
                           const struct bpf_verifier_state *src)
{
        struct bpf_func_state *dst;
        int i, err;

        dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
                                          src->jmp_history_cnt, sizeof(*dst_state->jmp_history),
                                          GFP_KERNEL_ACCOUNT);
        if (!dst_state->jmp_history)
                return -ENOMEM;
        dst_state->jmp_history_cnt = src->jmp_history_cnt;

        /* if dst has more stack frames then src frame, free them, this is also
         * necessary in case of exceptional exits using bpf_throw.
         */
        for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
                free_func_state(dst_state->frame[i]);
                dst_state->frame[i] = NULL;
        }
        err = copy_reference_state(dst_state, src);
        if (err)
                return err;
        dst_state->speculative = src->speculative;
        dst_state->in_sleepable = src->in_sleepable;
        dst_state->curframe = src->curframe;
        dst_state->branches = src->branches;
        dst_state->parent = src->parent;
        dst_state->first_insn_idx = src->first_insn_idx;
        dst_state->last_insn_idx = src->last_insn_idx;
        dst_state->dfs_depth = src->dfs_depth;
        dst_state->callback_unroll_depth = src->callback_unroll_depth;
        dst_state->may_goto_depth = src->may_goto_depth;
        dst_state->equal_state = src->equal_state;
        for (i = 0; i <= src->curframe; i++) {
                dst = dst_state->frame[i];
                if (!dst) {
                        dst = kzalloc_obj(*dst, GFP_KERNEL_ACCOUNT);
                        if (!dst)
                                return -ENOMEM;
                        dst_state->frame[i] = dst;
                }
                err = copy_func_state(dst, src->frame[i]);
                if (err)
                        return err;
        }
        return 0;
}

static u32 state_htab_size(struct bpf_verifier_env *env)
{
        return env->prog->len;
}

struct list_head *bpf_explored_state(struct bpf_verifier_env *env, int idx)
{
        struct bpf_verifier_state *cur = env->cur_state;
        struct bpf_func_state *state = cur->frame[cur->curframe];

        return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
}

static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b)
{
        int fr;

        if (a->curframe != b->curframe)
                return false;

        for (fr = a->curframe; fr >= 0; fr--)
                if (a->frame[fr]->callsite != b->frame[fr]->callsite)
                        return false;

        return true;
}


void bpf_free_backedges(struct bpf_scc_visit *visit)
{
        struct bpf_scc_backedge *backedge, *next;

        for (backedge = visit->backedges; backedge; backedge = next) {
                bpf_free_verifier_state(&backedge->state, false);
                next = backedge->next;
                kfree(backedge);
        }
        visit->backedges = NULL;
}

static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
                     int *insn_idx, bool pop_log)
{
        struct bpf_verifier_state *cur = env->cur_state;
        struct bpf_verifier_stack_elem *elem, *head = env->head;
        int err;

        if (env->head == NULL)
                return -ENOENT;

        if (cur) {
                err = bpf_copy_verifier_state(cur, &head->st);
                if (err)
                        return err;
        }
        if (pop_log)
                bpf_vlog_reset(&env->log, head->log_pos);
        if (insn_idx)
                *insn_idx = head->insn_idx;
        if (prev_insn_idx)
                *prev_insn_idx = head->prev_insn_idx;
        elem = head->next;
        bpf_free_verifier_state(&head->st, false);
        kfree(head);
        env->head = elem;
        env->stack_size--;
        return 0;
}

static bool error_recoverable_with_nospec(int err)
{
        /* Should only return true for non-fatal errors that are allowed to
         * occur during speculative verification. For these we can insert a
         * nospec and the program might still be accepted. Do not include
         * something like ENOMEM because it is likely to re-occur for the next
         * architectural path once it has been recovered-from in all speculative
         * paths.
         */
        return err == -EPERM || err == -EACCES || err == -EINVAL;
}

static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
                                             int insn_idx, int prev_insn_idx,
                                             bool speculative)
{
        struct bpf_verifier_state *cur = env->cur_state;
        struct bpf_verifier_stack_elem *elem;
        int err;

        elem = kzalloc_obj(struct bpf_verifier_stack_elem, GFP_KERNEL_ACCOUNT);
        if (!elem)
                return ERR_PTR(-ENOMEM);

        elem->insn_idx = insn_idx;
        elem->prev_insn_idx = prev_insn_idx;
        elem->next = env->head;
        elem->log_pos = env->log.end_pos;
        env->head = elem;
        env->stack_size++;
        err = bpf_copy_verifier_state(&elem->st, cur);
        if (err)
                return ERR_PTR(-ENOMEM);
        elem->st.speculative |= speculative;
        if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
                verbose(env, "The sequence of %d jumps is too complex.\n",
                        env->stack_size);
                return ERR_PTR(-E2BIG);
        }
        if (elem->st.parent) {
                ++elem->st.parent->branches;
                /* WARN_ON(branches > 2) technically makes sense here,
                 * but
                 * 1. speculative states will bump 'branches' for non-branch
                 * instructions
                 * 2. is_state_visited() heuristics may decide not to create
                 * a new state for a sequence of branches and all such current
                 * and cloned states will be pointing to a single parent state
                 * which might have large 'branches' count.
                 */
        }
        return &elem->st;
}

static const int caller_saved[CALLER_SAVED_REGS] = {
        BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
};

/* This helper doesn't clear reg->id */
static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
        reg->var_off = tnum_const(imm);
        reg->smin_value = (s64)imm;
        reg->smax_value = (s64)imm;
        reg->umin_value = imm;
        reg->umax_value = imm;

        reg->s32_min_value = (s32)imm;
        reg->s32_max_value = (s32)imm;
        reg->u32_min_value = (u32)imm;
        reg->u32_max_value = (u32)imm;
}

/* Mark the unknown part of a register (variable offset or scalar value) as
 * known to have the value @imm.
 */
static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
        /* Clear off and union(map_ptr, range) */
        memset(((u8 *)reg) + sizeof(reg->type), 0,
               offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
        reg->id = 0;
        reg->ref_obj_id = 0;
        ___mark_reg_known(reg, imm);
}

static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
{
        reg->var_off = tnum_const_subreg(reg->var_off, imm);
        reg->s32_min_value = (s32)imm;
        reg->s32_max_value = (s32)imm;
        reg->u32_min_value = (u32)imm;
        reg->u32_max_value = (u32)imm;
}

/* Mark the 'variable offset' part of a register as zero.  This should be
 * used only on registers holding a pointer type.
 */
static void __mark_reg_known_zero(struct bpf_reg_state *reg)
{
        __mark_reg_known(reg, 0);
}

static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        __mark_reg_known(reg, 0);
        reg->type = SCALAR_VALUE;
        /* all scalars are assumed imprecise initially (unless unprivileged,
         * in which case everything is forced to be precise)
         */
        reg->precise = !env->bpf_capable;
}

static void mark_reg_known_zero(struct bpf_verifier_env *env,
                                struct bpf_reg_state *regs, u32 regno)
{
        __mark_reg_known_zero(regs + regno);
}

static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type,
                              bool first_slot, int dynptr_id)
{
        /* reg->type has no meaning for STACK_DYNPTR, but when we set reg for
         * callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply
         * set it unconditionally as it is ignored for STACK_DYNPTR anyway.
         */
        __mark_reg_known_zero(reg);
        reg->type = CONST_PTR_TO_DYNPTR;
        /* Give each dynptr a unique id to uniquely associate slices to it. */
        reg->id = dynptr_id;
        reg->dynptr.type = type;
        reg->dynptr.first_slot = first_slot;
}

static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
{
        if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
                const struct bpf_map *map = reg->map_ptr;

                if (map->inner_map_meta) {
                        reg->type = CONST_PTR_TO_MAP;
                        reg->map_ptr = map->inner_map_meta;
                        /* transfer reg's id which is unique for every map_lookup_elem
                         * as UID of the inner map.
                         */
                        if (btf_record_has_field(map->inner_map_meta->record,
                                                 BPF_TIMER | BPF_WORKQUEUE | BPF_TASK_WORK)) {
                                reg->map_uid = reg->id;
                        }
                } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
                        reg->type = PTR_TO_XDP_SOCK;
                } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
                           map->map_type == BPF_MAP_TYPE_SOCKHASH) {
                        reg->type = PTR_TO_SOCKET;
                } else {
                        reg->type = PTR_TO_MAP_VALUE;
                }
                return;
        }

        reg->type &= ~PTR_MAYBE_NULL;
}

static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno,
                                struct btf_field_graph_root *ds_head)
{
        __mark_reg_known(&regs[regno], ds_head->node_offset);
        regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC;
        regs[regno].btf = ds_head->btf;
        regs[regno].btf_id = ds_head->value_btf_id;
}

static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
{
        return type_is_pkt_pointer(reg->type);
}

static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
{
        return reg_is_pkt_pointer(reg) ||
               reg->type == PTR_TO_PACKET_END;
}

static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg)
{
        return base_type(reg->type) == PTR_TO_MEM &&
               (reg->type &
                (DYNPTR_TYPE_SKB | DYNPTR_TYPE_XDP | DYNPTR_TYPE_SKB_META));
}

/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
                                    enum bpf_reg_type which)
{
        /* The register can already have a range from prior markings.
         * This is fine as long as it hasn't been advanced from its
         * origin.
         */
        return reg->type == which &&
               reg->id == 0 &&
               tnum_equals_const(reg->var_off, 0);
}

/* Reset the min/max bounds of a register */
static void __mark_reg_unbounded(struct bpf_reg_state *reg)
{
        reg->smin_value = S64_MIN;
        reg->smax_value = S64_MAX;
        reg->umin_value = 0;
        reg->umax_value = U64_MAX;

        reg->s32_min_value = S32_MIN;
        reg->s32_max_value = S32_MAX;
        reg->u32_min_value = 0;
        reg->u32_max_value = U32_MAX;
}

static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
{
        reg->smin_value = S64_MIN;
        reg->smax_value = S64_MAX;
        reg->umin_value = 0;
        reg->umax_value = U64_MAX;
}

static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
{
        reg->s32_min_value = S32_MIN;
        reg->s32_max_value = S32_MAX;
        reg->u32_min_value = 0;
        reg->u32_max_value = U32_MAX;
}

static void reset_reg64_and_tnum(struct bpf_reg_state *reg)
{
        __mark_reg64_unbounded(reg);
        reg->var_off = tnum_unknown;
}

static void reset_reg32_and_tnum(struct bpf_reg_state *reg)
{
        __mark_reg32_unbounded(reg);
        reg->var_off = tnum_unknown;
}

static void __update_reg32_bounds(struct bpf_reg_state *reg)
{
        struct tnum var32_off = tnum_subreg(reg->var_off);

        /* min signed is max(sign bit) | min(other bits) */
        reg->s32_min_value = max_t(s32, reg->s32_min_value,
                        var32_off.value | (var32_off.mask & S32_MIN));
        /* max signed is min(sign bit) | max(other bits) */
        reg->s32_max_value = min_t(s32, reg->s32_max_value,
                        var32_off.value | (var32_off.mask & S32_MAX));
        reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
        reg->u32_max_value = min(reg->u32_max_value,
                                 (u32)(var32_off.value | var32_off.mask));
}

static void __update_reg64_bounds(struct bpf_reg_state *reg)
{
        u64 tnum_next, tmax;
        bool umin_in_tnum;

        /* min signed is max(sign bit) | min(other bits) */
        reg->smin_value = max_t(s64, reg->smin_value,
                                reg->var_off.value | (reg->var_off.mask & S64_MIN));
        /* max signed is min(sign bit) | max(other bits) */
        reg->smax_value = min_t(s64, reg->smax_value,
                                reg->var_off.value | (reg->var_off.mask & S64_MAX));
        reg->umin_value = max(reg->umin_value, reg->var_off.value);
        reg->umax_value = min(reg->umax_value,
                              reg->var_off.value | reg->var_off.mask);

        /* Check if u64 and tnum overlap in a single value */
        tnum_next = tnum_step(reg->var_off, reg->umin_value);
        umin_in_tnum = (reg->umin_value & ~reg->var_off.mask) == reg->var_off.value;
        tmax = reg->var_off.value | reg->var_off.mask;
        if (umin_in_tnum && tnum_next > reg->umax_value) {
                /* The u64 range and the tnum only overlap in umin.
                 * u64:  ---[xxxxxx]-----
                 * tnum: --xx----------x-
                 */
                ___mark_reg_known(reg, reg->umin_value);
        } else if (!umin_in_tnum && tnum_next == tmax) {
                /* The u64 range and the tnum only overlap in the maximum value
                 * represented by the tnum, called tmax.
                 * u64:  ---[xxxxxx]-----
                 * tnum: xx-----x--------
                 */
                ___mark_reg_known(reg, tmax);
        } else if (!umin_in_tnum && tnum_next <= reg->umax_value &&
                   tnum_step(reg->var_off, tnum_next) > reg->umax_value) {
                /* The u64 range and the tnum only overlap in between umin
                 * (excluded) and umax.
                 * u64:  ---[xxxxxx]-----
                 * tnum: xx----x-------x-
                 */
                ___mark_reg_known(reg, tnum_next);
        }
}

static void __update_reg_bounds(struct bpf_reg_state *reg)
{
        __update_reg32_bounds(reg);
        __update_reg64_bounds(reg);
}

/* Uses signed min/max values to inform unsigned, and vice-versa */
static void deduce_bounds_32_from_64(struct bpf_reg_state *reg)
{
        /* If upper 32 bits of u64/s64 range don't change, we can use lower 32
         * bits to improve our u32/s32 boundaries.
         *
         * E.g., the case where we have upper 32 bits as zero ([10, 20] in
         * u64) is pretty trivial, it's obvious that in u32 we'll also have
         * [10, 20] range. But this property holds for any 64-bit range as
         * long as upper 32 bits in that entire range of values stay the same.
         *
         * E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311]
         * in decimal) has the same upper 32 bits throughout all the values in
         * that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15])
         * range.
         *
         * Note also, that [0xA, 0xF] is a valid range both in u32 and in s32,
         * following the rules outlined below about u64/s64 correspondence
         * (which equally applies to u32 vs s32 correspondence). In general it
         * depends on actual hexadecimal values of 32-bit range. They can form
         * only valid u32, or only valid s32 ranges in some cases.
         *
         * So we use all these insights to derive bounds for subregisters here.
         */
        if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) {
                /* u64 to u32 casting preserves validity of low 32 bits as
                 * a range, if upper 32 bits are the same
                 */
                reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value);
                reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value);

                if ((s32)reg->umin_value <= (s32)reg->umax_value) {
                        reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
                        reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
                }
        }
        if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) {
                /* low 32 bits should form a proper u32 range */
                if ((u32)reg->smin_value <= (u32)reg->smax_value) {
                        reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value);
                        reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value);
                }
                /* low 32 bits should form a proper s32 range */
                if ((s32)reg->smin_value <= (s32)reg->smax_value) {
                        reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
                        reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
                }
        }
        /* Special case where upper bits form a small sequence of two
         * sequential numbers (in 32-bit unsigned space, so 0xffffffff to
         * 0x00000000 is also valid), while lower bits form a proper s32 range
         * going from negative numbers to positive numbers. E.g., let's say we
         * have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]).
         * Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff,
         * 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits,
         * we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]).
         * Note that it doesn't have to be 0xffffffff going to 0x00000000 in
         * upper 32 bits. As a random example, s64 range
         * [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range
         * [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister.
         */
        if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) &&
            (s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) {
                reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
                reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
        }
        if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) &&
            (s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) {
                reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
                reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
        }
}

static void deduce_bounds_32_from_32(struct bpf_reg_state *reg)
{
        /* if u32 range forms a valid s32 range (due to matching sign bit),
         * try to learn from that
         */
        if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
                reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
                reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
        }
        /* If we cannot cross the sign boundary, then signed and unsigned bounds
         * are the same, so combine.  This works even in the negative case, e.g.
         * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
         */
        if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
                reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
                reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
        } else {
                if (reg->u32_max_value < (u32)reg->s32_min_value) {
                        /* See __reg64_deduce_bounds() for detailed explanation.
                         * Refine ranges in the following situation:
                         *
                         * 0                                                   U32_MAX
                         * |  [xxxxxxxxxxxxxx u32 range xxxxxxxxxxxxxx]              |
                         * |----------------------------|----------------------------|
                         * |xxxxx s32 range xxxxxxxxx]                       [xxxxxxx|
                         * 0                     S32_MAX S32_MIN                    -1
                         */
                        reg->s32_min_value = (s32)reg->u32_min_value;
                        reg->u32_max_value = min_t(u32, reg->u32_max_value, reg->s32_max_value);
                } else if ((u32)reg->s32_max_value < reg->u32_min_value) {
                        /*
                         * 0                                                   U32_MAX
                         * |              [xxxxxxxxxxxxxx u32 range xxxxxxxxxxxxxx]  |
                         * |----------------------------|----------------------------|
                         * |xxxxxxxxx]                       [xxxxxxxxxxxx s32 range |
                         * 0                     S32_MAX S32_MIN                    -1
                         */
                        reg->s32_max_value = (s32)reg->u32_max_value;
                        reg->u32_min_value = max_t(u32, reg->u32_min_value, reg->s32_min_value);
                }
        }
}

static void deduce_bounds_64_from_64(struct bpf_reg_state *reg)
{
        /* If u64 range forms a valid s64 range (due to matching sign bit),
         * try to learn from that. Let's do a bit of ASCII art to see when
         * this is happening. Let's take u64 range first:
         *
         * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
         * |-------------------------------|--------------------------------|
         *
         * Valid u64 range is formed when umin and umax are anywhere in the
         * range [0, U64_MAX], and umin <= umax. u64 case is simple and
         * straightforward. Let's see how s64 range maps onto the same range
         * of values, annotated below the line for comparison:
         *
         * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
         * |-------------------------------|--------------------------------|
         * 0                        S64_MAX S64_MIN                        -1
         *
         * So s64 values basically start in the middle and they are logically
         * contiguous to the right of it, wrapping around from -1 to 0, and
         * then finishing as S64_MAX (0x7fffffffffffffff) right before
         * S64_MIN. We can try drawing the continuity of u64 vs s64 values
         * more visually as mapped to sign-agnostic range of hex values.
         *
         *  u64 start                                               u64 end
         *  _______________________________________________________________
         * /                                                               \
         * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
         * |-------------------------------|--------------------------------|
         * 0                        S64_MAX S64_MIN                        -1
         *                                / \
         * >------------------------------   ------------------------------->
         * s64 continues...        s64 end   s64 start          s64 "midpoint"
         *
         * What this means is that, in general, we can't always derive
         * something new about u64 from any random s64 range, and vice versa.
         *
         * But we can do that in two particular cases. One is when entire
         * u64/s64 range is *entirely* contained within left half of the above
         * diagram or when it is *entirely* contained in the right half. I.e.:
         *
         * |-------------------------------|--------------------------------|
         *     ^                   ^            ^                 ^
         *     A                   B            C                 D
         *
         * [A, B] and [C, D] are contained entirely in their respective halves
         * and form valid contiguous ranges as both u64 and s64 values. [A, B]
         * will be non-negative both as u64 and s64 (and in fact it will be
         * identical ranges no matter the signedness). [C, D] treated as s64
         * will be a range of negative values, while in u64 it will be
         * non-negative range of values larger than 0x8000000000000000.
         *
         * Now, any other range here can't be represented in both u64 and s64
         * simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid
         * contiguous u64 ranges, but they are discontinuous in s64. [B, C]
         * in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX],
         * for example. Similarly, valid s64 range [D, A] (going from negative
         * to positive values), would be two separate [D, U64_MAX] and [0, A]
         * ranges as u64. Currently reg_state can't represent two segments per
         * numeric domain, so in such situations we can only derive maximal
         * possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64).
         *
         * So we use these facts to derive umin/umax from smin/smax and vice
         * versa only if they stay within the same "half". This is equivalent
         * to checking sign bit: lower half will have sign bit as zero, upper
         * half have sign bit 1. Below in code we simplify this by just
         * casting umin/umax as smin/smax and checking if they form valid
         * range, and vice versa. Those are equivalent checks.
         */
        if ((s64)reg->umin_value <= (s64)reg->umax_value) {
                reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value);
                reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value);
        }
        /* If we cannot cross the sign boundary, then signed and unsigned bounds
         * are the same, so combine.  This works even in the negative case, e.g.
         * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
         */
        if ((u64)reg->smin_value <= (u64)reg->smax_value) {
                reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
                reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
        } else {
                /* If the s64 range crosses the sign boundary, then it's split
                 * between the beginning and end of the U64 domain. In that
                 * case, we can derive new bounds if the u64 range overlaps
                 * with only one end of the s64 range.
                 *
                 * In the following example, the u64 range overlaps only with
                 * positive portion of the s64 range.
                 *
                 * 0                                                   U64_MAX
                 * |  [xxxxxxxxxxxxxx u64 range xxxxxxxxxxxxxx]              |
                 * |----------------------------|----------------------------|
                 * |xxxxx s64 range xxxxxxxxx]                       [xxxxxxx|
                 * 0                     S64_MAX S64_MIN                    -1
                 *
                 * We can thus derive the following new s64 and u64 ranges.
                 *
                 * 0                                                   U64_MAX
                 * |  [xxxxxx u64 range xxxxx]                               |
                 * |----------------------------|----------------------------|
                 * |  [xxxxxx s64 range xxxxx]                               |
                 * 0                     S64_MAX S64_MIN                    -1
                 *
                 * If they overlap in two places, we can't derive anything
                 * because reg_state can't represent two ranges per numeric
                 * domain.
                 *
                 * 0                                                   U64_MAX
                 * |  [xxxxxxxxxxxxxxxxx u64 range xxxxxxxxxxxxxxxxx]        |
                 * |----------------------------|----------------------------|
                 * |xxxxx s64 range xxxxxxxxx]                    [xxxxxxxxxx|
                 * 0                     S64_MAX S64_MIN                    -1
                 *
                 * The first condition below corresponds to the first diagram
                 * above.
                 */
                if (reg->umax_value < (u64)reg->smin_value) {
                        reg->smin_value = (s64)reg->umin_value;
                        reg->umax_value = min_t(u64, reg->umax_value, reg->smax_value);
                } else if ((u64)reg->smax_value < reg->umin_value) {
                        /* This second condition considers the case where the u64 range
                         * overlaps with the negative portion of the s64 range:
                         *
                         * 0                                                   U64_MAX
                         * |              [xxxxxxxxxxxxxx u64 range xxxxxxxxxxxxxx]  |
                         * |----------------------------|----------------------------|
                         * |xxxxxxxxx]                       [xxxxxxxxxxxx s64 range |
                         * 0                     S64_MAX S64_MIN                    -1
                         */
                        reg->smax_value = (s64)reg->umax_value;
                        reg->umin_value = max_t(u64, reg->umin_value, reg->smin_value);
                }
        }
}

static void deduce_bounds_64_from_32(struct bpf_reg_state *reg)
{
        /* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit
         * values on both sides of 64-bit range in hope to have tighter range.
         * E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from
         * 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff].
         * With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound
         * (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of
         * _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a
         * better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff].
         * We just need to make sure that derived bounds we are intersecting
         * with are well-formed ranges in respective s64 or u64 domain, just
         * like we do with similar kinds of 32-to-64 or 64-to-32 adjustments.
         */
        __u64 new_umin, new_umax;
        __s64 new_smin, new_smax;

        /* u32 -> u64 tightening, it's always well-formed */
        new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value;
        new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value;
        reg->umin_value = max_t(u64, reg->umin_value, new_umin);
        reg->umax_value = min_t(u64, reg->umax_value, new_umax);
        /* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */
        new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value;
        new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value;
        reg->smin_value = max_t(s64, reg->smin_value, new_smin);
        reg->smax_value = min_t(s64, reg->smax_value, new_smax);

        /* Here we would like to handle a special case after sign extending load,
         * when upper bits for a 64-bit range are all 1s or all 0s.
         *
         * Upper bits are all 1s when register is in a range:
         *   [0xffff_ffff_0000_0000, 0xffff_ffff_ffff_ffff]
         * Upper bits are all 0s when register is in a range:
         *   [0x0000_0000_0000_0000, 0x0000_0000_ffff_ffff]
         * Together this forms are continuous range:
         *   [0xffff_ffff_0000_0000, 0x0000_0000_ffff_ffff]
         *
         * Now, suppose that register range is in fact tighter:
         *   [0xffff_ffff_8000_0000, 0x0000_0000_ffff_ffff] (R)
         * Also suppose that it's 32-bit range is positive,
         * meaning that lower 32-bits of the full 64-bit register
         * are in the range:
         *   [0x0000_0000, 0x7fff_ffff] (W)
         *
         * If this happens, then any value in a range:
         *   [0xffff_ffff_0000_0000, 0xffff_ffff_7fff_ffff]
         * is smaller than a lowest bound of the range (R):
         *   0xffff_ffff_8000_0000
         * which means that upper bits of the full 64-bit register
         * can't be all 1s, when lower bits are in range (W).
         *
         * Note that:
         *  - 0xffff_ffff_8000_0000 == (s64)S32_MIN
         *  - 0x0000_0000_7fff_ffff == (s64)S32_MAX
         * These relations are used in the conditions below.
         */
        if (reg->s32_min_value >= 0 && reg->smin_value >= S32_MIN && reg->smax_value <= S32_MAX) {
                reg->smin_value = reg->s32_min_value;
                reg->smax_value = reg->s32_max_value;
                reg->umin_value = reg->s32_min_value;
                reg->umax_value = reg->s32_max_value;
                reg->var_off = tnum_intersect(reg->var_off,
                                              tnum_range(reg->smin_value, reg->smax_value));
        }
}

static void __reg_deduce_bounds(struct bpf_reg_state *reg)
{
        deduce_bounds_64_from_64(reg);
        deduce_bounds_32_from_64(reg);
        deduce_bounds_32_from_32(reg);
        deduce_bounds_64_from_32(reg);
}

/* Attempts to improve var_off based on unsigned min/max information */
static void __reg_bound_offset(struct bpf_reg_state *reg)
{
        struct tnum var64_off = tnum_intersect(reg->var_off,
                                               tnum_range(reg->umin_value,
                                                          reg->umax_value));
        struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off),
                                               tnum_range(reg->u32_min_value,
                                                          reg->u32_max_value));

        reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
}

static bool range_bounds_violation(struct bpf_reg_state *reg);

static void reg_bounds_sync(struct bpf_reg_state *reg)
{
        /* If the input reg_state is invalid, we can exit early */
        if (range_bounds_violation(reg))
                return;
        /* We might have learned new bounds from the var_off. */
        __update_reg_bounds(reg);
        /* We might have learned something about the sign bit. */
        __reg_deduce_bounds(reg);
        __reg_deduce_bounds(reg);
        /* We might have learned some bits from the bounds. */
        __reg_bound_offset(reg);
        /* Intersecting with the old var_off might have improved our bounds
         * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
         * then new var_off is (0; 0x7f...fc) which improves our umax.
         */
        __update_reg_bounds(reg);
}

static bool range_bounds_violation(struct bpf_reg_state *reg)
{
        return (reg->umin_value > reg->umax_value || reg->smin_value > reg->smax_value ||
                reg->u32_min_value > reg->u32_max_value ||
                reg->s32_min_value > reg->s32_max_value);
}

static bool const_tnum_range_mismatch(struct bpf_reg_state *reg)
{
        u64 uval = reg->var_off.value;
        s64 sval = (s64)uval;

        if (!tnum_is_const(reg->var_off))
                return false;

        return reg->umin_value != uval || reg->umax_value != uval ||
               reg->smin_value != sval || reg->smax_value != sval;
}

static bool const_tnum_range_mismatch_32(struct bpf_reg_state *reg)
{
        u32 uval32 = tnum_subreg(reg->var_off).value;
        s32 sval32 = (s32)uval32;

        if (!tnum_subreg_is_const(reg->var_off))
                return false;

        return reg->u32_min_value != uval32 || reg->u32_max_value != uval32 ||
               reg->s32_min_value != sval32 || reg->s32_max_value != sval32;
}

static int reg_bounds_sanity_check(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg, const char *ctx)
{
        const char *msg;

        if (range_bounds_violation(reg)) {
                msg = "range bounds violation";
                goto out;
        }

        if (const_tnum_range_mismatch(reg)) {
                msg = "const tnum out of sync with range bounds";
                goto out;
        }

        if (const_tnum_range_mismatch_32(reg)) {
                msg = "const subreg tnum out of sync with range bounds";
                goto out;
        }

        return 0;
out:
        verifier_bug(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] "
                     "s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)",
                     ctx, msg, reg->umin_value, reg->umax_value,
                     reg->smin_value, reg->smax_value,
                     reg->u32_min_value, reg->u32_max_value,
                     reg->s32_min_value, reg->s32_max_value,
                     reg->var_off.value, reg->var_off.mask);
        if (env->test_reg_invariants)
                return -EFAULT;
        __mark_reg_unbounded(reg);
        return 0;
}

static bool __reg32_bound_s64(s32 a)
{
        return a >= 0 && a <= S32_MAX;
}

static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
{
        reg->umin_value = reg->u32_min_value;
        reg->umax_value = reg->u32_max_value;

        /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
         * be positive otherwise set to worse case bounds and refine later
         * from tnum.
         */
        if (__reg32_bound_s64(reg->s32_min_value) &&
            __reg32_bound_s64(reg->s32_max_value)) {
                reg->smin_value = reg->s32_min_value;
                reg->smax_value = reg->s32_max_value;
        } else {
                reg->smin_value = 0;
                reg->smax_value = U32_MAX;
        }
}

/* Mark a register as having a completely unknown (scalar) value. */
void bpf_mark_reg_unknown_imprecise(struct bpf_reg_state *reg)
{
        /*
         * Clear type, off, and union(map_ptr, range) and
         * padding between 'type' and union
         */
        memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
        reg->type = SCALAR_VALUE;
        reg->id = 0;
        reg->ref_obj_id = 0;
        reg->var_off = tnum_unknown;
        reg->frameno = 0;
        reg->precise = false;
        __mark_reg_unbounded(reg);
}

/* Mark a register as having a completely unknown (scalar) value,
 * initialize .precise as true when not bpf capable.
 */
static void __mark_reg_unknown(const struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg)
{
        bpf_mark_reg_unknown_imprecise(reg);
        reg->precise = !env->bpf_capable;
}

static void mark_reg_unknown(struct bpf_verifier_env *env,
                             struct bpf_reg_state *regs, u32 regno)
{
        __mark_reg_unknown(env, regs + regno);
}

static int __mark_reg_s32_range(struct bpf_verifier_env *env,
                                struct bpf_reg_state *regs,
                                u32 regno,
                                s32 s32_min,
                                s32 s32_max)
{
        struct bpf_reg_state *reg = regs + regno;

        reg->s32_min_value = max_t(s32, reg->s32_min_value, s32_min);
        reg->s32_max_value = min_t(s32, reg->s32_max_value, s32_max);

        reg->smin_value = max_t(s64, reg->smin_value, s32_min);
        reg->smax_value = min_t(s64, reg->smax_value, s32_max);

        reg_bounds_sync(reg);

        return reg_bounds_sanity_check(env, reg, "s32_range");
}

void bpf_mark_reg_not_init(const struct bpf_verifier_env *env,
                           struct bpf_reg_state *reg)
{
        __mark_reg_unknown(env, reg);
        reg->type = NOT_INIT;
}

static int mark_btf_ld_reg(struct bpf_verifier_env *env,
                           struct bpf_reg_state *regs, u32 regno,
                           enum bpf_reg_type reg_type,
                           struct btf *btf, u32 btf_id,
                           enum bpf_type_flag flag)
{
        switch (reg_type) {
        case SCALAR_VALUE:
                mark_reg_unknown(env, regs, regno);
                return 0;
        case PTR_TO_BTF_ID:
                mark_reg_known_zero(env, regs, regno);
                regs[regno].type = PTR_TO_BTF_ID | flag;
                regs[regno].btf = btf;
                regs[regno].btf_id = btf_id;
                if (type_may_be_null(flag))
                        regs[regno].id = ++env->id_gen;
                return 0;
        case PTR_TO_MEM:
                mark_reg_known_zero(env, regs, regno);
                regs[regno].type = PTR_TO_MEM | flag;
                regs[regno].mem_size = 0;
                return 0;
        default:
                verifier_bug(env, "unexpected reg_type %d in %s\n", reg_type, __func__);
                return -EFAULT;
        }
}

#define DEF_NOT_SUBREG  (0)
static void init_reg_state(struct bpf_verifier_env *env,
                           struct bpf_func_state *state)
{
        struct bpf_reg_state *regs = state->regs;
        int i;

        for (i = 0; i < MAX_BPF_REG; i++) {
                bpf_mark_reg_not_init(env, &regs[i]);
                regs[i].subreg_def = DEF_NOT_SUBREG;
        }

        /* frame pointer */
        regs[BPF_REG_FP].type = PTR_TO_STACK;
        mark_reg_known_zero(env, regs, BPF_REG_FP);
        regs[BPF_REG_FP].frameno = state->frameno;
}

static struct bpf_retval_range retval_range(s32 minval, s32 maxval)
{
        /*
         * return_32bit is set to false by default and set explicitly
         * by the caller when necessary.
         */
        return (struct bpf_retval_range){ minval, maxval, false };
}

static void init_func_state(struct bpf_verifier_env *env,
                            struct bpf_func_state *state,
                            int callsite, int frameno, int subprogno)
{
        state->callsite = callsite;
        state->frameno = frameno;
        state->subprogno = subprogno;
        state->callback_ret_range = retval_range(0, 0);
        init_reg_state(env, state);
        mark_verifier_state_scratched(env);
}

/* Similar to push_stack(), but for async callbacks */
static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
                                                int insn_idx, int prev_insn_idx,
                                                int subprog, bool is_sleepable)
{
        struct bpf_verifier_stack_elem *elem;
        struct bpf_func_state *frame;

        elem = kzalloc_obj(struct bpf_verifier_stack_elem, GFP_KERNEL_ACCOUNT);
        if (!elem)
                return ERR_PTR(-ENOMEM);

        elem->insn_idx = insn_idx;
        elem->prev_insn_idx = prev_insn_idx;
        elem->next = env->head;
        elem->log_pos = env->log.end_pos;
        env->head = elem;
        env->stack_size++;
        if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
                verbose(env,
                        "The sequence of %d jumps is too complex for async cb.\n",
                        env->stack_size);
                return ERR_PTR(-E2BIG);
        }
        /* Unlike push_stack() do not bpf_copy_verifier_state().
         * The caller state doesn't matter.
         * This is async callback. It starts in a fresh stack.
         * Initialize it similar to do_check_common().
         */
        elem->st.branches = 1;
        elem->st.in_sleepable = is_sleepable;
        frame = kzalloc_obj(*frame, GFP_KERNEL_ACCOUNT);
        if (!frame)
                return ERR_PTR(-ENOMEM);
        init_func_state(env, frame,
                        BPF_MAIN_FUNC /* callsite */,
                        0 /* frameno within this callchain */,
                        subprog /* subprog number within this prog */);
        elem->st.frame[0] = frame;
        return &elem->st;
}


static int cmp_subprogs(const void *a, const void *b)
{
        return ((struct bpf_subprog_info *)a)->start -
               ((struct bpf_subprog_info *)b)->start;
}

/* Find subprogram that contains instruction at 'off' */
struct bpf_subprog_info *bpf_find_containing_subprog(struct bpf_verifier_env *env, int off)
{
        struct bpf_subprog_info *vals = env->subprog_info;
        int l, r, m;

        if (off >= env->prog->len || off < 0 || env->subprog_cnt == 0)
                return NULL;

        l = 0;
        r = env->subprog_cnt - 1;
        while (l < r) {
                m = l + (r - l + 1) / 2;
                if (vals[m].start <= off)
                        l = m;
                else
                        r = m - 1;
        }
        return &vals[l];
}

/* Find subprogram that starts exactly at 'off' */
int bpf_find_subprog(struct bpf_verifier_env *env, int off)
{
        struct bpf_subprog_info *p;

        p = bpf_find_containing_subprog(env, off);
        if (!p || p->start != off)
                return -ENOENT;
        return p - env->subprog_info;
}

static int add_subprog(struct bpf_verifier_env *env, int off)
{
        int insn_cnt = env->prog->len;
        int ret;

        if (off >= insn_cnt || off < 0) {
                verbose(env, "call to invalid destination\n");
                return -EINVAL;
        }
        ret = bpf_find_subprog(env, off);
        if (ret >= 0)
                return ret;
        if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
                verbose(env, "too many subprograms\n");
                return -E2BIG;
        }
        /* determine subprog starts. The end is one before the next starts */
        env->subprog_info[env->subprog_cnt++].start = off;
        sort(env->subprog_info, env->subprog_cnt,
             sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
        return env->subprog_cnt - 1;
}

static int bpf_find_exception_callback_insn_off(struct bpf_verifier_env *env)
{
        struct bpf_prog_aux *aux = env->prog->aux;
        struct btf *btf = aux->btf;
        const struct btf_type *t;
        u32 main_btf_id, id;
        const char *name;
        int ret, i;

        /* Non-zero func_info_cnt implies valid btf */
        if (!aux->func_info_cnt)
                return 0;
        main_btf_id = aux->func_info[0].type_id;

        t = btf_type_by_id(btf, main_btf_id);
        if (!t) {
                verbose(env, "invalid btf id for main subprog in func_info\n");
                return -EINVAL;
        }

        name = btf_find_decl_tag_value(btf, t, -1, "exception_callback:");
        if (IS_ERR(name)) {
                ret = PTR_ERR(name);
                /* If there is no tag present, there is no exception callback */
                if (ret == -ENOENT)
                        ret = 0;
                else if (ret == -EEXIST)
                        verbose(env, "multiple exception callback tags for main subprog\n");
                return ret;
        }

        ret = btf_find_by_name_kind(btf, name, BTF_KIND_FUNC);
        if (ret < 0) {
                verbose(env, "exception callback '%s' could not be found in BTF\n", name);
                return ret;
        }
        id = ret;
        t = btf_type_by_id(btf, id);
        if (btf_func_linkage(t) != BTF_FUNC_GLOBAL) {
                verbose(env, "exception callback '%s' must have global linkage\n", name);
                return -EINVAL;
        }
        ret = 0;
        for (i = 0; i < aux->func_info_cnt; i++) {
                if (aux->func_info[i].type_id != id)
                        continue;
                ret = aux->func_info[i].insn_off;
                /* Further func_info and subprog checks will also happen
                 * later, so assume this is the right insn_off for now.
                 */
                if (!ret) {
                        verbose(env, "invalid exception callback insn_off in func_info: 0\n");
                        ret = -EINVAL;
                }
        }
        if (!ret) {
                verbose(env, "exception callback type id not found in func_info\n");
                ret = -EINVAL;
        }
        return ret;
}

#define MAX_KFUNC_BTFS  256

struct bpf_kfunc_btf {
        struct btf *btf;
        struct module *module;
        u16 offset;
};

struct bpf_kfunc_btf_tab {
        struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS];
        u32 nr_descs;
};

static int kfunc_desc_cmp_by_id_off(const void *a, const void *b)
{
        const struct bpf_kfunc_desc *d0 = a;
        const struct bpf_kfunc_desc *d1 = b;

        /* func_id is not greater than BTF_MAX_TYPE */
        return d0->func_id - d1->func_id ?: d0->offset - d1->offset;
}

static int kfunc_btf_cmp_by_off(const void *a, const void *b)
{
        const struct bpf_kfunc_btf *d0 = a;
        const struct bpf_kfunc_btf *d1 = b;

        return d0->offset - d1->offset;
}

static struct bpf_kfunc_desc *
find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
{
        struct bpf_kfunc_desc desc = {
                .func_id = func_id,
                .offset = offset,
        };
        struct bpf_kfunc_desc_tab *tab;

        tab = prog->aux->kfunc_tab;
        return bsearch(&desc, tab->descs, tab->nr_descs,
                       sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
}

int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id,
                       u16 btf_fd_idx, u8 **func_addr)
{
        const struct bpf_kfunc_desc *desc;

        desc = find_kfunc_desc(prog, func_id, btf_fd_idx);
        if (!desc)
                return -EFAULT;

        *func_addr = (u8 *)desc->addr;
        return 0;
}

static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
                                         s16 offset)
{
        struct bpf_kfunc_btf kf_btf = { .offset = offset };
        struct bpf_kfunc_btf_tab *tab;
        struct bpf_kfunc_btf *b;
        struct module *mod;
        struct btf *btf;
        int btf_fd;

        tab = env->prog->aux->kfunc_btf_tab;
        b = bsearch(&kf_btf, tab->descs, tab->nr_descs,
                    sizeof(tab->descs[0]), kfunc_btf_cmp_by_off);
        if (!b) {
                if (tab->nr_descs == MAX_KFUNC_BTFS) {
                        verbose(env, "too many different module BTFs\n");
                        return ERR_PTR(-E2BIG);
                }

                if (bpfptr_is_null(env->fd_array)) {
                        verbose(env, "kfunc offset > 0 without fd_array is invalid\n");
                        return ERR_PTR(-EPROTO);
                }

                if (copy_from_bpfptr_offset(&btf_fd, env->fd_array,
                                            offset * sizeof(btf_fd),
                                            sizeof(btf_fd)))
                        return ERR_PTR(-EFAULT);

                btf = btf_get_by_fd(btf_fd);
                if (IS_ERR(btf)) {
                        verbose(env, "invalid module BTF fd specified\n");
                        return btf;
                }

                if (!btf_is_module(btf)) {
                        verbose(env, "BTF fd for kfunc is not a module BTF\n");
                        btf_put(btf);
                        return ERR_PTR(-EINVAL);
                }

                mod = btf_try_get_module(btf);
                if (!mod) {
                        btf_put(btf);
                        return ERR_PTR(-ENXIO);
                }

                b = &tab->descs[tab->nr_descs++];
                b->btf = btf;
                b->module = mod;
                b->offset = offset;

                /* sort() reorders entries by value, so b may no longer point
                 * to the right entry after this
                 */
                sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
                     kfunc_btf_cmp_by_off, NULL);
        } else {
                btf = b->btf;
        }

        return btf;
}

void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
{
        if (!tab)
                return;

        while (tab->nr_descs--) {
                module_put(tab->descs[tab->nr_descs].module);
                btf_put(tab->descs[tab->nr_descs].btf);
        }
        kfree(tab);
}

static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset)
{
        if (offset) {
                if (offset < 0) {
                        /* In the future, this can be allowed to increase limit
                         * of fd index into fd_array, interpreted as u16.
                         */
                        verbose(env, "negative offset disallowed for kernel module function call\n");
                        return ERR_PTR(-EINVAL);
                }

                return __find_kfunc_desc_btf(env, offset);
        }
        return btf_vmlinux ?: ERR_PTR(-ENOENT);
}

#define KF_IMPL_SUFFIX "_impl"

static const struct btf_type *find_kfunc_impl_proto(struct bpf_verifier_env *env,
                                                    struct btf *btf,
                                                    const char *func_name)
{
        char *buf = env->tmp_str_buf;
        const struct btf_type *func;
        s32 impl_id;
        int len;

        len = snprintf(buf, TMP_STR_BUF_LEN, "%s%s", func_name, KF_IMPL_SUFFIX);
        if (len < 0 || len >= TMP_STR_BUF_LEN) {
                verbose(env, "function name %s%s is too long\n", func_name, KF_IMPL_SUFFIX);
                return NULL;
        }

        impl_id = btf_find_by_name_kind(btf, buf, BTF_KIND_FUNC);
        if (impl_id <= 0) {
                verbose(env, "cannot find function %s in BTF\n", buf);
                return NULL;
        }

        func = btf_type_by_id(btf, impl_id);

        return btf_type_by_id(btf, func->type);
}

static int fetch_kfunc_meta(struct bpf_verifier_env *env,
                            s32 func_id,
                            s16 offset,
                            struct bpf_kfunc_meta *kfunc)
{
        const struct btf_type *func, *func_proto;
        const char *func_name;
        u32 *kfunc_flags;
        struct btf *btf;

        if (func_id <= 0) {
                verbose(env, "invalid kernel function btf_id %d\n", func_id);
                return -EINVAL;
        }

        btf = find_kfunc_desc_btf(env, offset);
        if (IS_ERR(btf)) {
                verbose(env, "failed to find BTF for kernel function\n");
                return PTR_ERR(btf);
        }

        /*
         * Note that kfunc_flags may be NULL at this point, which
         * means that we couldn't find func_id in any relevant
         * kfunc_id_set. This most likely indicates an invalid kfunc
         * call.  However we don't fail with an error here,
         * and let the caller decide what to do with NULL kfunc->flags.
         */
        kfunc_flags = btf_kfunc_flags(btf, func_id, env->prog);

        func = btf_type_by_id(btf, func_id);
        if (!func || !btf_type_is_func(func)) {
                verbose(env, "kernel btf_id %d is not a function\n", func_id);
                return -EINVAL;
        }

        func_name = btf_name_by_offset(btf, func->name_off);

        /*
         * An actual prototype of a kfunc with KF_IMPLICIT_ARGS flag
         * can be found through the counterpart _impl kfunc.
         */
        if (kfunc_flags && (*kfunc_flags & KF_IMPLICIT_ARGS))
                func_proto = find_kfunc_impl_proto(env, btf, func_name);
        else
                func_proto = btf_type_by_id(btf, func->type);

        if (!func_proto || !btf_type_is_func_proto(func_proto)) {
                verbose(env, "kernel function btf_id %d does not have a valid func_proto\n",
                        func_id);
                return -EINVAL;
        }

        memset(kfunc, 0, sizeof(*kfunc));
        kfunc->btf = btf;
        kfunc->id = func_id;
        kfunc->name = func_name;
        kfunc->proto = func_proto;
        kfunc->flags = kfunc_flags;

        return 0;
}

int bpf_add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, u16 offset)
{
        struct bpf_kfunc_btf_tab *btf_tab;
        struct btf_func_model func_model;
        struct bpf_kfunc_desc_tab *tab;
        struct bpf_prog_aux *prog_aux;
        struct bpf_kfunc_meta kfunc;
        struct bpf_kfunc_desc *desc;
        unsigned long addr;
        int err;

        prog_aux = env->prog->aux;
        tab = prog_aux->kfunc_tab;
        btf_tab = prog_aux->kfunc_btf_tab;
        if (!tab) {
                if (!btf_vmlinux) {
                        verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n");
                        return -ENOTSUPP;
                }

                if (!env->prog->jit_requested) {
                        verbose(env, "JIT is required for calling kernel function\n");
                        return -ENOTSUPP;
                }

                if (!bpf_jit_supports_kfunc_call()) {
                        verbose(env, "JIT does not support calling kernel function\n");
                        return -ENOTSUPP;
                }

                if (!env->prog->gpl_compatible) {
                        verbose(env, "cannot call kernel function from non-GPL compatible program\n");
                        return -EINVAL;
                }

                tab = kzalloc_obj(*tab, GFP_KERNEL_ACCOUNT);
                if (!tab)
                        return -ENOMEM;
                prog_aux->kfunc_tab = tab;
        }

        /* func_id == 0 is always invalid, but instead of returning an error, be
         * conservative and wait until the code elimination pass before returning
         * error, so that invalid calls that get pruned out can be in BPF programs
         * loaded from userspace.  It is also required that offset be untouched
         * for such calls.
         */
        if (!func_id && !offset)
                return 0;

        if (!btf_tab && offset) {
                btf_tab = kzalloc_obj(*btf_tab, GFP_KERNEL_ACCOUNT);
                if (!btf_tab)
                        return -ENOMEM;
                prog_aux->kfunc_btf_tab = btf_tab;
        }

        if (find_kfunc_desc(env->prog, func_id, offset))
                return 0;

        if (tab->nr_descs == MAX_KFUNC_DESCS) {
                verbose(env, "too many different kernel function calls\n");
                return -E2BIG;
        }

        err = fetch_kfunc_meta(env, func_id, offset, &kfunc);
        if (err)
                return err;

        addr = kallsyms_lookup_name(kfunc.name);
        if (!addr) {
                verbose(env, "cannot find address for kernel function %s\n", kfunc.name);
                return -EINVAL;
        }

        if (bpf_dev_bound_kfunc_id(func_id)) {
                err = bpf_dev_bound_kfunc_check(&env->log, prog_aux);
                if (err)
                        return err;
        }

        err = btf_distill_func_proto(&env->log, kfunc.btf, kfunc.proto, kfunc.name, &func_model);
        if (err)
                return err;

        desc = &tab->descs[tab->nr_descs++];
        desc->func_id = func_id;
        desc->offset = offset;
        desc->addr = addr;
        desc->func_model = func_model;
        sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
             kfunc_desc_cmp_by_id_off, NULL);
        return 0;
}

bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog)
{
        return !!prog->aux->kfunc_tab;
}

static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
{
        struct bpf_subprog_info *subprog = env->subprog_info;
        int i, ret, insn_cnt = env->prog->len, ex_cb_insn;
        struct bpf_insn *insn = env->prog->insnsi;

        /* Add entry function. */
        ret = add_subprog(env, 0);
        if (ret)
                return ret;

        for (i = 0; i < insn_cnt; i++, insn++) {
                if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) &&
                    !bpf_pseudo_kfunc_call(insn))
                        continue;

                if (!env->bpf_capable) {
                        verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
                        return -EPERM;
                }

                if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn))
                        ret = add_subprog(env, i + insn->imm + 1);
                else
                        ret = bpf_add_kfunc_call(env, insn->imm, insn->off);

                if (ret < 0)
                        return ret;
        }

        ret = bpf_find_exception_callback_insn_off(env);
        if (ret < 0)
                return ret;
        ex_cb_insn = ret;

        /* If ex_cb_insn > 0, this means that the main program has a subprog
         * marked using BTF decl tag to serve as the exception callback.
         */
        if (ex_cb_insn) {
                ret = add_subprog(env, ex_cb_insn);
                if (ret < 0)
                        return ret;
                for (i = 1; i < env->subprog_cnt; i++) {
                        if (env->subprog_info[i].start != ex_cb_insn)
                                continue;
                        env->exception_callback_subprog = i;
                        bpf_mark_subprog_exc_cb(env, i);
                        break;
                }
        }

        /* Add a fake 'exit' subprog which could simplify subprog iteration
         * logic. 'subprog_cnt' should not be increased.
         */
        subprog[env->subprog_cnt].start = insn_cnt;

        if (env->log.level & BPF_LOG_LEVEL2)
                for (i = 0; i < env->subprog_cnt; i++)
                        verbose(env, "func#%d @%d\n", i, subprog[i].start);

        return 0;
}

static int check_subprogs(struct bpf_verifier_env *env)
{
        int i, subprog_start, subprog_end, off, cur_subprog = 0;
        struct bpf_subprog_info *subprog = env->subprog_info;
        struct bpf_insn *insn = env->prog->insnsi;
        int insn_cnt = env->prog->len;

        /* now check that all jumps are within the same subprog */
        subprog_start = subprog[cur_subprog].start;
        subprog_end = subprog[cur_subprog + 1].start;
        for (i = 0; i < insn_cnt; i++) {
                u8 code = insn[i].code;

                if (code == (BPF_JMP | BPF_CALL) &&
                    insn[i].src_reg == 0 &&
                    insn[i].imm == BPF_FUNC_tail_call) {
                        subprog[cur_subprog].has_tail_call = true;
                        subprog[cur_subprog].tail_call_reachable = true;
                }
                if (BPF_CLASS(code) == BPF_LD &&
                    (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
                        subprog[cur_subprog].has_ld_abs = true;
                if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
                        goto next;
                if (BPF_OP(code) == BPF_CALL)
                        goto next;
                if (BPF_OP(code) == BPF_EXIT) {
                        subprog[cur_subprog].exit_idx = i;
                        goto next;
                }
                off = i + bpf_jmp_offset(&insn[i]) + 1;
                if (off < subprog_start || off >= subprog_end) {
                        verbose(env, "jump out of range from insn %d to %d\n", i, off);
                        return -EINVAL;
                }
next:
                if (i == subprog_end - 1) {
                        /* to avoid fall-through from one subprog into another
                         * the last insn of the subprog should be either exit
                         * or unconditional jump back or bpf_throw call
                         */
                        if (code != (BPF_JMP | BPF_EXIT) &&
                            code != (BPF_JMP32 | BPF_JA) &&
                            code != (BPF_JMP | BPF_JA)) {
                                verbose(env, "last insn is not an exit or jmp\n");
                                return -EINVAL;
                        }
                        subprog_start = subprog_end;
                        cur_subprog++;
                        if (cur_subprog < env->subprog_cnt)
                                subprog_end = subprog[cur_subprog + 1].start;
                }
        }
        return 0;
}

/*
 * Sort subprogs in topological order so that leaf subprogs come first and
 * their callers come later. This is a DFS post-order traversal of the call
 * graph. Scan only reachable instructions (those in the computed postorder) of
 * the current subprog to discover callees (direct subprogs and sync
 * callbacks).
 */
static int sort_subprogs_topo(struct bpf_verifier_env *env)
{
        struct bpf_subprog_info *si = env->subprog_info;
        int *insn_postorder = env->cfg.insn_postorder;
        struct bpf_insn *insn = env->prog->insnsi;
        int cnt = env->subprog_cnt;
        int *dfs_stack = NULL;
        int top = 0, order = 0;
        int i, ret = 0;
        u8 *color = NULL;

        color = kvzalloc_objs(*color, cnt, GFP_KERNEL_ACCOUNT);
        dfs_stack = kvmalloc_objs(*dfs_stack, cnt, GFP_KERNEL_ACCOUNT);
        if (!color || !dfs_stack) {
                ret = -ENOMEM;
                goto out;
        }

        /*
         * DFS post-order traversal.
         * Color values: 0 = unvisited, 1 = on stack, 2 = done.
         */
        for (i = 0; i < cnt; i++) {
                if (color[i])
                        continue;
                color[i] = 1;
                dfs_stack[top++] = i;

                while (top > 0) {
                        int cur = dfs_stack[top - 1];
                        int po_start = si[cur].postorder_start;
                        int po_end = si[cur + 1].postorder_start;
                        bool pushed = false;
                        int j;

                        for (j = po_start; j < po_end; j++) {
                                int idx = insn_postorder[j];
                                int callee;

                                if (!bpf_pseudo_call(&insn[idx]) && !bpf_pseudo_func(&insn[idx]))
                                        continue;
                                callee = bpf_find_subprog(env, idx + insn[idx].imm + 1);
                                if (callee < 0) {
                                        ret = -EFAULT;
                                        goto out;
                                }
                                if (color[callee] == 2)
                                        continue;
                                if (color[callee] == 1) {
                                        if (bpf_pseudo_func(&insn[idx]))
                                                continue;
                                        verbose(env, "recursive call from %s() to %s()\n",
                                                subprog_name(env, cur),
                                                subprog_name(env, callee));
                                        ret = -EINVAL;
                                        goto out;
                                }
                                color[callee] = 1;
                                dfs_stack[top++] = callee;
                                pushed = true;
                                break;
                        }

                        if (!pushed) {
                                color[cur] = 2;
                                env->subprog_topo_order[order++] = cur;
                                top--;
                        }
                }
        }

        if (env->log.level & BPF_LOG_LEVEL2)
                for (i = 0; i < cnt; i++)
                        verbose(env, "topo_order[%d] = %s\n",
                                i, subprog_name(env, env->subprog_topo_order[i]));
out:
        kvfree(dfs_stack);
        kvfree(color);
        return ret;
}

static int mark_stack_slot_obj_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                    int spi, int nr_slots)
{
        int i;

        for (i = 0; i < nr_slots; i++)
                mark_stack_slot_scratched(env, spi - i);
        return 0;
}

static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        int spi;

        /* For CONST_PTR_TO_DYNPTR, it must have already been done by
         * check_reg_arg in check_helper_call and mark_btf_func_reg_size in
         * check_kfunc_call.
         */
        if (reg->type == CONST_PTR_TO_DYNPTR)
                return 0;
        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return spi;
        /* Caller ensures dynptr is valid and initialized, which means spi is in
         * bounds and spi is the first dynptr slot. Simply mark stack slot as
         * read.
         */
        return mark_stack_slot_obj_read(env, reg, spi, BPF_DYNPTR_NR_SLOTS);
}

static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                          int spi, int nr_slots)
{
        return mark_stack_slot_obj_read(env, reg, spi, nr_slots);
}

static int mark_irq_flag_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        int spi;

        spi = irq_flag_get_spi(env, reg);
        if (spi < 0)
                return spi;
        return mark_stack_slot_obj_read(env, reg, spi, 1);
}

/* This function is supposed to be used by the following 32-bit optimization
 * code only. It returns TRUE if the source or destination register operates
 * on 64-bit, otherwise return FALSE.
 */
bool bpf_is_reg64(struct bpf_insn *insn,
              u32 regno, struct bpf_reg_state *reg, enum bpf_reg_arg_type t)
{
        u8 code, class, op;

        code = insn->code;
        class = BPF_CLASS(code);
        op = BPF_OP(code);
        if (class == BPF_JMP) {
                /* BPF_EXIT for "main" will reach here. Return TRUE
                 * conservatively.
                 */
                if (op == BPF_EXIT)
                        return true;
                if (op == BPF_CALL) {
                        /* BPF to BPF call will reach here because of marking
                         * caller saved clobber with DST_OP_NO_MARK for which we
                         * don't care the register def because they are anyway
                         * marked as NOT_INIT already.
                         */
                        if (insn->src_reg == BPF_PSEUDO_CALL)
                                return false;
                        /* Helper call will reach here because of arg type
                         * check, conservatively return TRUE.
                         */
                        if (t == SRC_OP)
                                return true;

                        return false;
                }
        }

        if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32))
                return false;

        if (class == BPF_ALU64 || class == BPF_JMP ||
            (class == BPF_ALU && op == BPF_END && insn->imm == 64))
                return true;

        if (class == BPF_ALU || class == BPF_JMP32)
                return false;

        if (class == BPF_LDX) {
                if (t != SRC_OP)
                        return BPF_SIZE(code) == BPF_DW || BPF_MODE(code) == BPF_MEMSX;
                /* LDX source must be ptr. */
                return true;
        }

        if (class == BPF_STX) {
                /* BPF_STX (including atomic variants) has one or more source
                 * operands, one of which is a ptr. Check whether the caller is
                 * asking about it.
                 */
                if (t == SRC_OP && reg->type != SCALAR_VALUE)
                        return true;
                return BPF_SIZE(code) == BPF_DW;
        }

        if (class == BPF_LD) {
                u8 mode = BPF_MODE(code);

                /* LD_IMM64 */
                if (mode == BPF_IMM)
                        return true;

                /* Both LD_IND and LD_ABS return 32-bit data. */
                if (t != SRC_OP)
                        return  false;

                /* Implicit ctx ptr. */
                if (regno == BPF_REG_6)
                        return true;

                /* Explicit source could be any width. */
                return true;
        }

        if (class == BPF_ST)
                /* The only source register for BPF_ST is a ptr. */
                return true;

        /* Conservatively return true at default. */
        return true;
}

static void mark_insn_zext(struct bpf_verifier_env *env,
                           struct bpf_reg_state *reg)
{
        s32 def_idx = reg->subreg_def;

        if (def_idx == DEF_NOT_SUBREG)
                return;

        env->insn_aux_data[def_idx - 1].zext_dst = true;
        /* The dst will be zero extended, so won't be sub-register anymore. */
        reg->subreg_def = DEF_NOT_SUBREG;
}

static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
                           enum bpf_reg_arg_type t)
{
        struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
        struct bpf_reg_state *reg;
        bool rw64;

        mark_reg_scratched(env, regno);

        reg = &regs[regno];
        rw64 = bpf_is_reg64(insn, regno, reg, t);
        if (t == SRC_OP) {
                /* check whether register used as source operand can be read */
                if (reg->type == NOT_INIT) {
                        verbose(env, "R%d !read_ok\n", regno);
                        return -EACCES;
                }
                /* We don't need to worry about FP liveness because it's read-only */
                if (regno == BPF_REG_FP)
                        return 0;

                if (rw64)
                        mark_insn_zext(env, reg);

                return 0;
        } else {
                /* check whether register used as dest operand can be written to */
                if (regno == BPF_REG_FP) {
                        verbose(env, "frame pointer is read only\n");
                        return -EACCES;
                }
                reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
                if (t == DST_OP)
                        mark_reg_unknown(env, regs, regno);
        }
        return 0;
}

static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
                         enum bpf_reg_arg_type t)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];

        return __check_reg_arg(env, state->regs, regno, t);
}

static int insn_stack_access_flags(int frameno, int spi)
{
        return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno;
}

static void mark_indirect_target(struct bpf_verifier_env *env, int idx)
{
        env->insn_aux_data[idx].indirect_target = true;
}

#define LR_FRAMENO_BITS 3
#define LR_SPI_BITS     6
#define LR_ENTRY_BITS   (LR_SPI_BITS + LR_FRAMENO_BITS + 1)
#define LR_SIZE_BITS    4
#define LR_FRAMENO_MASK ((1ull << LR_FRAMENO_BITS) - 1)
#define LR_SPI_MASK     ((1ull << LR_SPI_BITS)     - 1)
#define LR_SIZE_MASK    ((1ull << LR_SIZE_BITS)    - 1)
#define LR_SPI_OFF      LR_FRAMENO_BITS
#define LR_IS_REG_OFF   (LR_SPI_BITS + LR_FRAMENO_BITS)
#define LINKED_REGS_MAX 6

struct linked_reg {
        u8 frameno;
        union {
                u8 spi;
                u8 regno;
        };
        bool is_reg;
};

struct linked_regs {
        int cnt;
        struct linked_reg entries[LINKED_REGS_MAX];
};

static struct linked_reg *linked_regs_push(struct linked_regs *s)
{
        if (s->cnt < LINKED_REGS_MAX)
                return &s->entries[s->cnt++];

        return NULL;
}

/* Use u64 as a vector of 6 10-bit values, use first 4-bits to track
 * number of elements currently in stack.
 * Pack one history entry for linked registers as 10 bits in the following format:
 * - 3-bits frameno
 * - 6-bits spi_or_reg
 * - 1-bit  is_reg
 */
static u64 linked_regs_pack(struct linked_regs *s)
{
        u64 val = 0;
        int i;

        for (i = 0; i < s->cnt; ++i) {
                struct linked_reg *e = &s->entries[i];
                u64 tmp = 0;

                tmp |= e->frameno;
                tmp |= e->spi << LR_SPI_OFF;
                tmp |= (e->is_reg ? 1 : 0) << LR_IS_REG_OFF;

                val <<= LR_ENTRY_BITS;
                val |= tmp;
        }
        val <<= LR_SIZE_BITS;
        val |= s->cnt;
        return val;
}

static void linked_regs_unpack(u64 val, struct linked_regs *s)
{
        int i;

        s->cnt = val & LR_SIZE_MASK;
        val >>= LR_SIZE_BITS;

        for (i = 0; i < s->cnt; ++i) {
                struct linked_reg *e = &s->entries[i];

                e->frameno =  val & LR_FRAMENO_MASK;
                e->spi     = (val >> LR_SPI_OFF) & LR_SPI_MASK;
                e->is_reg  = (val >> LR_IS_REG_OFF) & 0x1;
                val >>= LR_ENTRY_BITS;
        }
}

static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
{
        const struct btf_type *func;
        struct btf *desc_btf;

        if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
                return NULL;

        desc_btf = find_kfunc_desc_btf(data, insn->off);
        if (IS_ERR(desc_btf))
                return "<error>";

        func = btf_type_by_id(desc_btf, insn->imm);
        return btf_name_by_offset(desc_btf, func->name_off);
}

void bpf_verbose_insn(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        const struct bpf_insn_cbs cbs = {
                .cb_call        = disasm_kfunc_name,
                .cb_print       = verbose,
                .private_data   = env,
        };

        print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
}

/* If any register R in hist->linked_regs is marked as precise in bt,
 * do bt_set_frame_{reg,slot}(bt, R) for all registers in hist->linked_regs.
 */
void bpf_bt_sync_linked_regs(struct backtrack_state *bt, struct bpf_jmp_history_entry *hist)
{
        struct linked_regs linked_regs;
        bool some_precise = false;
        int i;

        if (!hist || hist->linked_regs == 0)
                return;

        linked_regs_unpack(hist->linked_regs, &linked_regs);
        for (i = 0; i < linked_regs.cnt; ++i) {
                struct linked_reg *e = &linked_regs.entries[i];

                if ((e->is_reg && bt_is_frame_reg_set(bt, e->frameno, e->regno)) ||
                    (!e->is_reg && bt_is_frame_slot_set(bt, e->frameno, e->spi))) {
                        some_precise = true;
                        break;
                }
        }

        if (!some_precise)
                return;

        for (i = 0; i < linked_regs.cnt; ++i) {
                struct linked_reg *e = &linked_regs.entries[i];

                if (e->is_reg)
                        bpf_bt_set_frame_reg(bt, e->frameno, e->regno);
                else
                        bpf_bt_set_frame_slot(bt, e->frameno, e->spi);
        }
}

int mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
        return bpf_mark_chain_precision(env, env->cur_state, regno, NULL);
}

/* mark_chain_precision_batch() assumes that env->bt is set in the caller to
 * desired reg and stack masks across all relevant frames
 */
static int mark_chain_precision_batch(struct bpf_verifier_env *env,
                                      struct bpf_verifier_state *starting_state)
{
        return bpf_mark_chain_precision(env, starting_state, -1, NULL);
}

static bool is_spillable_regtype(enum bpf_reg_type type)
{
        switch (base_type(type)) {
        case PTR_TO_MAP_VALUE:
        case PTR_TO_STACK:
        case PTR_TO_CTX:
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET_END:
        case PTR_TO_FLOW_KEYS:
        case CONST_PTR_TO_MAP:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
        case PTR_TO_BTF_ID:
        case PTR_TO_BUF:
        case PTR_TO_MEM:
        case PTR_TO_FUNC:
        case PTR_TO_MAP_KEY:
        case PTR_TO_ARENA:
                return true;
        default:
                return false;
        }
}


/* check if register is a constant scalar value */
static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
{
        return reg->type == SCALAR_VALUE &&
               tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
}

/* assuming is_reg_const() is true, return constant value of a register */
static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
{
        return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
}

static bool __is_pointer_value(bool allow_ptr_leaks,
                               const struct bpf_reg_state *reg)
{
        if (allow_ptr_leaks)
                return false;

        return reg->type != SCALAR_VALUE;
}

static void clear_scalar_id(struct bpf_reg_state *reg)
{
        reg->id = 0;
        reg->delta = 0;
}

static void assign_scalar_id_before_mov(struct bpf_verifier_env *env,
                                        struct bpf_reg_state *src_reg)
{
        if (src_reg->type != SCALAR_VALUE)
                return;
        /*
         * The verifier is processing rX = rY insn and
         * rY->id has special linked register already.
         * Cleared it, since multiple rX += const are not supported.
         */
        if (src_reg->id & BPF_ADD_CONST)
                clear_scalar_id(src_reg);
        /*
         * Ensure that src_reg has a valid ID that will be copied to
         * dst_reg and then will be used by sync_linked_regs() to
         * propagate min/max range.
         */
        if (!src_reg->id && !tnum_is_const(src_reg->var_off))
                src_reg->id = ++env->id_gen;
}

/* Copy src state preserving dst->parent and dst->live fields */
static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src)
{
        *dst = *src;
}

static void save_register_state(struct bpf_verifier_env *env,
                                struct bpf_func_state *state,
                                int spi, struct bpf_reg_state *reg,
                                int size)
{
        int i;

        copy_register_state(&state->stack[spi].spilled_ptr, reg);

        for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
                state->stack[spi].slot_type[i - 1] = STACK_SPILL;

        /* size < 8 bytes spill */
        for (; i; i--)
                mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]);
}

static bool is_bpf_st_mem(struct bpf_insn *insn)
{
        return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
}

static int get_reg_width(struct bpf_reg_state *reg)
{
        return fls64(reg->umax_value);
}

/* See comment for mark_fastcall_pattern_for_call() */
static void check_fastcall_stack_contract(struct bpf_verifier_env *env,
                                          struct bpf_func_state *state, int insn_idx, int off)
{
        struct bpf_subprog_info *subprog = &env->subprog_info[state->subprogno];
        struct bpf_insn_aux_data *aux = env->insn_aux_data;
        int i;

        if (subprog->fastcall_stack_off <= off || aux[insn_idx].fastcall_pattern)
                return;
        /* access to the region [max_stack_depth .. fastcall_stack_off)
         * from something that is not a part of the fastcall pattern,
         * disable fastcall rewrites for current subprogram by setting
         * fastcall_stack_off to a value smaller than any possible offset.
         */
        subprog->fastcall_stack_off = S16_MIN;
        /* reset fastcall aux flags within subprogram,
         * happens at most once per subprogram
         */
        for (i = subprog->start; i < (subprog + 1)->start; ++i) {
                aux[i].fastcall_spills_num = 0;
                aux[i].fastcall_pattern = 0;
        }
}

static void scrub_special_slot(struct bpf_func_state *state, int spi)
{
        int i;

        /* regular write of data into stack destroys any spilled ptr */
        state->stack[spi].spilled_ptr.type = NOT_INIT;
        /* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */
        if (is_stack_slot_special(&state->stack[spi]))
                for (i = 0; i < BPF_REG_SIZE; i++)
                        scrub_spilled_slot(&state->stack[spi].slot_type[i]);
}

/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
 * stack boundary and alignment are checked in check_mem_access()
 */
static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
                                       /* stack frame we're writing to */
                                       struct bpf_func_state *state,
                                       int off, int size, int value_regno,
                                       int insn_idx)
{
        struct bpf_func_state *cur; /* state of the current function */
        int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
        struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
        struct bpf_reg_state *reg = NULL;
        int insn_flags = insn_stack_access_flags(state->frameno, spi);

        /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
         * so it's aligned access and [off, off + size) are within stack limits
         */
        if (!env->allow_ptr_leaks &&
            bpf_is_spilled_reg(&state->stack[spi]) &&
            !bpf_is_spilled_scalar_reg(&state->stack[spi]) &&
            size != BPF_REG_SIZE) {
                verbose(env, "attempt to corrupt spilled pointer on stack\n");
                return -EACCES;
        }

        cur = env->cur_state->frame[env->cur_state->curframe];
        if (value_regno >= 0)
                reg = &cur->regs[value_regno];
        if (!env->bypass_spec_v4) {
                bool sanitize = reg && is_spillable_regtype(reg->type);

                for (i = 0; i < size; i++) {
                        u8 type = state->stack[spi].slot_type[i];

                        if (type != STACK_MISC && type != STACK_ZERO) {
                                sanitize = true;
                                break;
                        }
                }

                if (sanitize)
                        env->insn_aux_data[insn_idx].nospec_result = true;
        }

        err = destroy_if_dynptr_stack_slot(env, state, spi);
        if (err)
                return err;

        check_fastcall_stack_contract(env, state, insn_idx, off);
        mark_stack_slot_scratched(env, spi);
        if (reg && !(off % BPF_REG_SIZE) && reg->type == SCALAR_VALUE && env->bpf_capable) {
                bool reg_value_fits;

                reg_value_fits = get_reg_width(reg) <= BITS_PER_BYTE * size;
                /* Make sure that reg had an ID to build a relation on spill. */
                if (reg_value_fits)
                        assign_scalar_id_before_mov(env, reg);
                save_register_state(env, state, spi, reg, size);
                /* Break the relation on a narrowing spill. */
                if (!reg_value_fits)
                        state->stack[spi].spilled_ptr.id = 0;
        } else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
                   env->bpf_capable) {
                struct bpf_reg_state *tmp_reg = &env->fake_reg[0];

                memset(tmp_reg, 0, sizeof(*tmp_reg));
                __mark_reg_known(tmp_reg, insn->imm);
                tmp_reg->type = SCALAR_VALUE;
                save_register_state(env, state, spi, tmp_reg, size);
        } else if (reg && is_spillable_regtype(reg->type)) {
                /* register containing pointer is being spilled into stack */
                if (size != BPF_REG_SIZE) {
                        verbose_linfo(env, insn_idx, "; ");
                        verbose(env, "invalid size of register spill\n");
                        return -EACCES;
                }
                if (state != cur && reg->type == PTR_TO_STACK) {
                        verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
                        return -EINVAL;
                }
                save_register_state(env, state, spi, reg, size);
        } else {
                u8 type = STACK_MISC;

                scrub_special_slot(state, spi);

                /* when we zero initialize stack slots mark them as such */
                if ((reg && bpf_register_is_null(reg)) ||
                    (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) {
                        /* STACK_ZERO case happened because register spill
                         * wasn't properly aligned at the stack slot boundary,
                         * so it's not a register spill anymore; force
                         * originating register to be precise to make
                         * STACK_ZERO correct for subsequent states
                         */
                        err = mark_chain_precision(env, value_regno);
                        if (err)
                                return err;
                        type = STACK_ZERO;
                }

                /* Mark slots affected by this stack write. */
                for (i = 0; i < size; i++)
                        state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type;
                insn_flags = 0; /* not a register spill */
        }

        if (insn_flags)
                return bpf_push_jmp_history(env, env->cur_state, insn_flags, 0);
        return 0;
}

/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
 * known to contain a variable offset.
 * This function checks whether the write is permitted and conservatively
 * tracks the effects of the write, considering that each stack slot in the
 * dynamic range is potentially written to.
 *
 * 'value_regno' can be -1, meaning that an unknown value is being written to
 * the stack.
 *
 * Spilled pointers in range are not marked as written because we don't know
 * what's going to be actually written. This means that read propagation for
 * future reads cannot be terminated by this write.
 *
 * For privileged programs, uninitialized stack slots are considered
 * initialized by this write (even though we don't know exactly what offsets
 * are going to be written to). The idea is that we don't want the verifier to
 * reject future reads that access slots written to through variable offsets.
 */
static int check_stack_write_var_off(struct bpf_verifier_env *env,
                                     /* func where register points to */
                                     struct bpf_func_state *state,
                                     int ptr_regno, int off, int size,
                                     int value_regno, int insn_idx)
{
        struct bpf_func_state *cur; /* state of the current function */
        int min_off, max_off;
        int i, err;
        struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
        struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
        bool writing_zero = false;
        /* set if the fact that we're writing a zero is used to let any
         * stack slots remain STACK_ZERO
         */
        bool zero_used = false;

        cur = env->cur_state->frame[env->cur_state->curframe];
        ptr_reg = &cur->regs[ptr_regno];
        min_off = ptr_reg->smin_value + off;
        max_off = ptr_reg->smax_value + off + size;
        if (value_regno >= 0)
                value_reg = &cur->regs[value_regno];
        if ((value_reg && bpf_register_is_null(value_reg)) ||
            (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0))
                writing_zero = true;

        for (i = min_off; i < max_off; i++) {
                int spi;

                spi = bpf_get_spi(i);
                err = destroy_if_dynptr_stack_slot(env, state, spi);
                if (err)
                        return err;
        }

        check_fastcall_stack_contract(env, state, insn_idx, min_off);
        /* Variable offset writes destroy any spilled pointers in range. */
        for (i = min_off; i < max_off; i++) {
                u8 new_type, *stype;
                int slot, spi;

                slot = -i - 1;
                spi = slot / BPF_REG_SIZE;
                stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
                mark_stack_slot_scratched(env, spi);

                if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) {
                        /* Reject the write if range we may write to has not
                         * been initialized beforehand. If we didn't reject
                         * here, the ptr status would be erased below (even
                         * though not all slots are actually overwritten),
                         * possibly opening the door to leaks.
                         *
                         * We do however catch STACK_INVALID case below, and
                         * only allow reading possibly uninitialized memory
                         * later for CAP_PERFMON, as the write may not happen to
                         * that slot.
                         */
                        verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
                                insn_idx, i);
                        return -EINVAL;
                }

                /* If writing_zero and the spi slot contains a spill of value 0,
                 * maintain the spill type.
                 */
                if (writing_zero && *stype == STACK_SPILL &&
                    bpf_is_spilled_scalar_reg(&state->stack[spi])) {
                        struct bpf_reg_state *spill_reg = &state->stack[spi].spilled_ptr;

                        if (tnum_is_const(spill_reg->var_off) && spill_reg->var_off.value == 0) {
                                zero_used = true;
                                continue;
                        }
                }

                /*
                 * Scrub slots if variable-offset stack write goes over spilled pointers.
                 * Otherwise bpf_is_spilled_reg() may == true && spilled_ptr.type == NOT_INIT
                 * and valid program is rejected by check_stack_read_fixed_off()
                 * with obscure "invalid size of register fill" message.
                 */
                scrub_special_slot(state, spi);

                /* Update the slot type. */
                new_type = STACK_MISC;
                if (writing_zero && *stype == STACK_ZERO) {
                        new_type = STACK_ZERO;
                        zero_used = true;
                }
                /* If the slot is STACK_INVALID, we check whether it's OK to
                 * pretend that it will be initialized by this write. The slot
                 * might not actually be written to, and so if we mark it as
                 * initialized future reads might leak uninitialized memory.
                 * For privileged programs, we will accept such reads to slots
                 * that may or may not be written because, if we're reject
                 * them, the error would be too confusing.
                 * Conservatively, treat STACK_POISON in a similar way.
                 */
                if ((*stype == STACK_INVALID || *stype == STACK_POISON) &&
                    !env->allow_uninit_stack) {
                        verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
                                        insn_idx, i);
                        return -EINVAL;
                }
                *stype = new_type;
        }
        if (zero_used) {
                /* backtracking doesn't work for STACK_ZERO yet. */
                err = mark_chain_precision(env, value_regno);
                if (err)
                        return err;
        }
        return 0;
}

/* When register 'dst_regno' is assigned some values from stack[min_off,
 * max_off), we set the register's type according to the types of the
 * respective stack slots. If all the stack values are known to be zeros, then
 * so is the destination reg. Otherwise, the register is considered to be
 * SCALAR. This function does not deal with register filling; the caller must
 * ensure that all spilled registers in the stack range have been marked as
 * read.
 */
static void mark_reg_stack_read(struct bpf_verifier_env *env,
                                /* func where src register points to */
                                struct bpf_func_state *ptr_state,
                                int min_off, int max_off, int dst_regno)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        int i, slot, spi;
        u8 *stype;
        int zeros = 0;

        for (i = min_off; i < max_off; i++) {
                slot = -i - 1;
                spi = slot / BPF_REG_SIZE;
                mark_stack_slot_scratched(env, spi);
                stype = ptr_state->stack[spi].slot_type;
                if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
                        break;
                zeros++;
        }
        if (zeros == max_off - min_off) {
                /* Any access_size read into register is zero extended,
                 * so the whole register == const_zero.
                 */
                __mark_reg_const_zero(env, &state->regs[dst_regno]);
        } else {
                /* have read misc data from the stack */
                mark_reg_unknown(env, state->regs, dst_regno);
        }
}

/* Read the stack at 'off' and put the results into the register indicated by
 * 'dst_regno'. It handles reg filling if the addressed stack slot is a
 * spilled reg.
 *
 * 'dst_regno' can be -1, meaning that the read value is not going to a
 * register.
 *
 * The access is assumed to be within the current stack bounds.
 */
static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
                                      /* func where src register points to */
                                      struct bpf_func_state *reg_state,
                                      int off, int size, int dst_regno)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
        struct bpf_reg_state *reg;
        u8 *stype, type;
        int insn_flags = insn_stack_access_flags(reg_state->frameno, spi);

        stype = reg_state->stack[spi].slot_type;
        reg = &reg_state->stack[spi].spilled_ptr;

        mark_stack_slot_scratched(env, spi);
        check_fastcall_stack_contract(env, state, env->insn_idx, off);

        if (bpf_is_spilled_reg(&reg_state->stack[spi])) {
                u8 spill_size = 1;

                for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--)
                        spill_size++;

                if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) {
                        if (reg->type != SCALAR_VALUE) {
                                verbose_linfo(env, env->insn_idx, "; ");
                                verbose(env, "invalid size of register fill\n");
                                return -EACCES;
                        }

                        if (dst_regno < 0)
                                return 0;

                        if (size <= spill_size &&
                            bpf_stack_narrow_access_ok(off, size, spill_size)) {
                                /* The earlier check_reg_arg() has decided the
                                 * subreg_def for this insn.  Save it first.
                                 */
                                s32 subreg_def = state->regs[dst_regno].subreg_def;

                                if (env->bpf_capable && size == 4 && spill_size == 4 &&
                                    get_reg_width(reg) <= 32)
                                        /* Ensure stack slot has an ID to build a relation
                                         * with the destination register on fill.
                                         */
                                        assign_scalar_id_before_mov(env, reg);
                                copy_register_state(&state->regs[dst_regno], reg);
                                state->regs[dst_regno].subreg_def = subreg_def;

                                /* Break the relation on a narrowing fill.
                                 * coerce_reg_to_size will adjust the boundaries.
                                 */
                                if (get_reg_width(reg) > size * BITS_PER_BYTE)
                                        clear_scalar_id(&state->regs[dst_regno]);
                        } else {
                                int spill_cnt = 0, zero_cnt = 0;

                                for (i = 0; i < size; i++) {
                                        type = stype[(slot - i) % BPF_REG_SIZE];
                                        if (type == STACK_SPILL) {
                                                spill_cnt++;
                                                continue;
                                        }
                                        if (type == STACK_MISC)
                                                continue;
                                        if (type == STACK_ZERO) {
                                                zero_cnt++;
                                                continue;
                                        }
                                        if (type == STACK_INVALID && env->allow_uninit_stack)
                                                continue;
                                        if (type == STACK_POISON) {
                                                verbose(env, "reading from stack off %d+%d size %d, slot poisoned by dead code elimination\n",
                                                        off, i, size);
                                        } else {
                                                verbose(env, "invalid read from stack off %d+%d size %d\n",
                                                        off, i, size);
                                        }
                                        return -EACCES;
                                }

                                if (spill_cnt == size &&
                                    tnum_is_const(reg->var_off) && reg->var_off.value == 0) {
                                        __mark_reg_const_zero(env, &state->regs[dst_regno]);
                                        /* this IS register fill, so keep insn_flags */
                                } else if (zero_cnt == size) {
                                        /* similarly to mark_reg_stack_read(), preserve zeroes */
                                        __mark_reg_const_zero(env, &state->regs[dst_regno]);
                                        insn_flags = 0; /* not restoring original register state */
                                } else {
                                        mark_reg_unknown(env, state->regs, dst_regno);
                                        insn_flags = 0; /* not restoring original register state */
                                }
                        }
                } else if (dst_regno >= 0) {
                        /* restore register state from stack */
                        if (env->bpf_capable)
                                /* Ensure stack slot has an ID to build a relation
                                 * with the destination register on fill.
                                 */
                                assign_scalar_id_before_mov(env, reg);
                        copy_register_state(&state->regs[dst_regno], reg);
                        /* mark reg as written since spilled pointer state likely
                         * has its liveness marks cleared by is_state_visited()
                         * which resets stack/reg liveness for state transitions
                         */
                } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
                        /* If dst_regno==-1, the caller is asking us whether
                         * it is acceptable to use this value as a SCALAR_VALUE
                         * (e.g. for XADD).
                         * We must not allow unprivileged callers to do that
                         * with spilled pointers.
                         */
                        verbose(env, "leaking pointer from stack off %d\n",
                                off);
                        return -EACCES;
                }
        } else {
                for (i = 0; i < size; i++) {
                        type = stype[(slot - i) % BPF_REG_SIZE];
                        if (type == STACK_MISC)
                                continue;
                        if (type == STACK_ZERO)
                                continue;
                        if (type == STACK_INVALID && env->allow_uninit_stack)
                                continue;
                        if (type == STACK_POISON) {
                                verbose(env, "reading from stack off %d+%d size %d, slot poisoned by dead code elimination\n",
                                        off, i, size);
                        } else {
                                verbose(env, "invalid read from stack off %d+%d size %d\n",
                                        off, i, size);
                        }
                        return -EACCES;
                }
                if (dst_regno >= 0)
                        mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
                insn_flags = 0; /* we are not restoring spilled register */
        }
        if (insn_flags)
                return bpf_push_jmp_history(env, env->cur_state, insn_flags, 0);
        return 0;
}

enum bpf_access_src {
        ACCESS_DIRECT = 1,  /* the access is performed by an instruction */
        ACCESS_HELPER = 2,  /* the access is performed by a helper */
};

static int check_stack_range_initialized(struct bpf_verifier_env *env,
                                         int regno, int off, int access_size,
                                         bool zero_size_allowed,
                                         enum bpf_access_type type,
                                         struct bpf_call_arg_meta *meta);

static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
{
        return cur_regs(env) + regno;
}

/* Read the stack at 'ptr_regno + off' and put the result into the register
 * 'dst_regno'.
 * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
 * but not its variable offset.
 * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
 *
 * As opposed to check_stack_read_fixed_off, this function doesn't deal with
 * filling registers (i.e. reads of spilled register cannot be detected when
 * the offset is not fixed). We conservatively mark 'dst_regno' as containing
 * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
 * offset; for a fixed offset check_stack_read_fixed_off should be used
 * instead.
 */
static int check_stack_read_var_off(struct bpf_verifier_env *env,
                                    int ptr_regno, int off, int size, int dst_regno)
{
        /* The state of the source register. */
        struct bpf_reg_state *reg = reg_state(env, ptr_regno);
        struct bpf_func_state *ptr_state = bpf_func(env, reg);
        int err;
        int min_off, max_off;

        /* Note that we pass a NULL meta, so raw access will not be permitted.
         */
        err = check_stack_range_initialized(env, ptr_regno, off, size,
                                            false, BPF_READ, NULL);
        if (err)
                return err;

        min_off = reg->smin_value + off;
        max_off = reg->smax_value + off;
        mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
        check_fastcall_stack_contract(env, ptr_state, env->insn_idx, min_off);
        return 0;
}

/* check_stack_read dispatches to check_stack_read_fixed_off or
 * check_stack_read_var_off.
 *
 * The caller must ensure that the offset falls within the allocated stack
 * bounds.
 *
 * 'dst_regno' is a register which will receive the value from the stack. It
 * can be -1, meaning that the read value is not going to a register.
 */
static int check_stack_read(struct bpf_verifier_env *env,
                            int ptr_regno, int off, int size,
                            int dst_regno)
{
        struct bpf_reg_state *reg = reg_state(env, ptr_regno);
        struct bpf_func_state *state = bpf_func(env, reg);
        int err;
        /* Some accesses are only permitted with a static offset. */
        bool var_off = !tnum_is_const(reg->var_off);

        /* The offset is required to be static when reads don't go to a
         * register, in order to not leak pointers (see
         * check_stack_read_fixed_off).
         */
        if (dst_regno < 0 && var_off) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
                        tn_buf, off, size);
                return -EACCES;
        }
        /* Variable offset is prohibited for unprivileged mode for simplicity
         * since it requires corresponding support in Spectre masking for stack
         * ALU. See also retrieve_ptr_limit(). The check in
         * check_stack_access_for_ptr_arithmetic() called by
         * adjust_ptr_min_max_vals() prevents users from creating stack pointers
         * with variable offsets, therefore no check is required here. Further,
         * just checking it here would be insufficient as speculative stack
         * writes could still lead to unsafe speculative behaviour.
         */
        if (!var_off) {
                off += reg->var_off.value;
                err = check_stack_read_fixed_off(env, state, off, size,
                                                 dst_regno);
        } else {
                /* Variable offset stack reads need more conservative handling
                 * than fixed offset ones. Note that dst_regno >= 0 on this
                 * branch.
                 */
                err = check_stack_read_var_off(env, ptr_regno, off, size,
                                               dst_regno);
        }
        return err;
}


/* check_stack_write dispatches to check_stack_write_fixed_off or
 * check_stack_write_var_off.
 *
 * 'ptr_regno' is the register used as a pointer into the stack.
 * 'value_regno' is the register whose value we're writing to the stack. It can
 * be -1, meaning that we're not writing from a register.
 *
 * The caller must ensure that the offset falls within the maximum stack size.
 */
static int check_stack_write(struct bpf_verifier_env *env,
                             int ptr_regno, int off, int size,
                             int value_regno, int insn_idx)
{
        struct bpf_reg_state *reg = reg_state(env, ptr_regno);
        struct bpf_func_state *state = bpf_func(env, reg);
        int err;

        if (tnum_is_const(reg->var_off)) {
                off += reg->var_off.value;
                err = check_stack_write_fixed_off(env, state, off, size,
                                                  value_regno, insn_idx);
        } else {
                /* Variable offset stack reads need more conservative handling
                 * than fixed offset ones.
                 */
                err = check_stack_write_var_off(env, state,
                                                ptr_regno, off, size,
                                                value_regno, insn_idx);
        }
        return err;
}

static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
                                 int off, int size, enum bpf_access_type type)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_map *map = reg->map_ptr;
        u32 cap = bpf_map_flags_to_cap(map);

        if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
                verbose(env, "write into map forbidden, value_size=%d off=%lld size=%d\n",
                        map->value_size, reg->smin_value + off, size);
                return -EACCES;
        }

        if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
                verbose(env, "read from map forbidden, value_size=%d off=%lld size=%d\n",
                        map->value_size, reg->smin_value + off, size);
                return -EACCES;
        }

        return 0;
}

/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
static int __check_mem_access(struct bpf_verifier_env *env, int regno,
                              int off, int size, u32 mem_size,
                              bool zero_size_allowed)
{
        bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
        struct bpf_reg_state *reg;

        if (off >= 0 && size_ok && (u64)off + size <= mem_size)
                return 0;

        reg = &cur_regs(env)[regno];
        switch (reg->type) {
        case PTR_TO_MAP_KEY:
                verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n",
                        mem_size, off, size);
                break;
        case PTR_TO_MAP_VALUE:
                verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
                        mem_size, off, size);
                break;
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET_END:
                verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
                        off, size, regno, reg->id, off, mem_size);
                break;
        case PTR_TO_CTX:
                verbose(env, "invalid access to context, ctx_size=%d off=%d size=%d\n",
                        mem_size, off, size);
                break;
        case PTR_TO_MEM:
        default:
                verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
                        mem_size, off, size);
        }

        return -EACCES;
}

/* check read/write into a memory region with possible variable offset */
static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
                                   int off, int size, u32 mem_size,
                                   bool zero_size_allowed)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *reg = &state->regs[regno];
        int err;

        /* We may have adjusted the register pointing to memory region, so we
         * need to try adding each of min_value and max_value to off
         * to make sure our theoretical access will be safe.
         *
         * The minimum value is only important with signed
         * comparisons where we can't assume the floor of a
         * value is 0.  If we are using signed variables for our
         * index'es we need to make sure that whatever we use
         * will have a set floor within our range.
         */
        if (reg->smin_value < 0 &&
            (reg->smin_value == S64_MIN ||
             (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
              reg->smin_value + off < 0)) {
                verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
                        regno);
                return -EACCES;
        }
        err = __check_mem_access(env, regno, reg->smin_value + off, size,
                                 mem_size, zero_size_allowed);
        if (err) {
                verbose(env, "R%d min value is outside of the allowed memory range\n",
                        regno);
                return err;
        }

        /* If we haven't set a max value then we need to bail since we can't be
         * sure we won't do bad things.
         * If reg->umax_value + off could overflow, treat that as unbounded too.
         */
        if (reg->umax_value >= BPF_MAX_VAR_OFF) {
                verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
                        regno);
                return -EACCES;
        }
        err = __check_mem_access(env, regno, reg->umax_value + off, size,
                                 mem_size, zero_size_allowed);
        if (err) {
                verbose(env, "R%d max value is outside of the allowed memory range\n",
                        regno);
                return err;
        }

        return 0;
}

static int __check_ptr_off_reg(struct bpf_verifier_env *env,
                               const struct bpf_reg_state *reg, int regno,
                               bool fixed_off_ok)
{
        /* Access to this pointer-typed register or passing it to a helper
         * is only allowed in its original, unmodified form.
         */

        if (!tnum_is_const(reg->var_off)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env, "variable %s access var_off=%s disallowed\n",
                        reg_type_str(env, reg->type), tn_buf);
                return -EACCES;
        }

        if (reg->smin_value < 0) {
                verbose(env, "negative offset %s ptr R%d off=%lld disallowed\n",
                        reg_type_str(env, reg->type), regno, reg->var_off.value);
                return -EACCES;
        }

        if (!fixed_off_ok && reg->var_off.value != 0) {
                verbose(env, "dereference of modified %s ptr R%d off=%lld disallowed\n",
                        reg_type_str(env, reg->type), regno, reg->var_off.value);
                return -EACCES;
        }

        return 0;
}

static int check_ptr_off_reg(struct bpf_verifier_env *env,
                             const struct bpf_reg_state *reg, int regno)
{
        return __check_ptr_off_reg(env, reg, regno, false);
}

static int map_kptr_match_type(struct bpf_verifier_env *env,
                               struct btf_field *kptr_field,
                               struct bpf_reg_state *reg, u32 regno)
{
        const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id);
        int perm_flags;
        const char *reg_name = "";

        if (base_type(reg->type) != PTR_TO_BTF_ID)
                goto bad_type;

        if (btf_is_kernel(reg->btf)) {
                perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU;

                /* Only unreferenced case accepts untrusted pointers */
                if (kptr_field->type == BPF_KPTR_UNREF)
                        perm_flags |= PTR_UNTRUSTED;
        } else {
                perm_flags = PTR_MAYBE_NULL | MEM_ALLOC;
                if (kptr_field->type == BPF_KPTR_PERCPU)
                        perm_flags |= MEM_PERCPU;
        }

        if (type_flag(reg->type) & ~perm_flags)
                goto bad_type;

        /* We need to verify reg->type and reg->btf, before accessing reg->btf */
        reg_name = btf_type_name(reg->btf, reg->btf_id);

        /* For ref_ptr case, release function check should ensure we get one
         * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the
         * normal store of unreferenced kptr, we must ensure var_off is zero.
         * Since ref_ptr cannot be accessed directly by BPF insns, check for
         * reg->ref_obj_id is not needed here.
         */
        if (__check_ptr_off_reg(env, reg, regno, true))
                return -EACCES;

        /* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and
         * we also need to take into account the reg->var_off.
         *
         * We want to support cases like:
         *
         * struct foo {
         *         struct bar br;
         *         struct baz bz;
         * };
         *
         * struct foo *v;
         * v = func();        // PTR_TO_BTF_ID
         * val->foo = v;      // reg->var_off is zero, btf and btf_id match type
         * val->bar = &v->br; // reg->var_off is still zero, but we need to retry with
         *                    // first member type of struct after comparison fails
         * val->baz = &v->bz; // reg->var_off is non-zero, so struct needs to be walked
         *                    // to match type
         *
         * In the kptr_ref case, check_func_arg_reg_off already ensures reg->var_off
         * is zero. We must also ensure that btf_struct_ids_match does not walk
         * the struct to match type against first member of struct, i.e. reject
         * second case from above. Hence, when type is BPF_KPTR_REF, we set
         * strict mode to true for type match.
         */
        if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->var_off.value,
                                  kptr_field->kptr.btf, kptr_field->kptr.btf_id,
                                  kptr_field->type != BPF_KPTR_UNREF))
                goto bad_type;
        return 0;
bad_type:
        verbose(env, "invalid kptr access, R%d type=%s%s ", regno,
                reg_type_str(env, reg->type), reg_name);
        verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name);
        if (kptr_field->type == BPF_KPTR_UNREF)
                verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED),
                        targ_name);
        else
                verbose(env, "\n");
        return -EINVAL;
}

static bool in_sleepable(struct bpf_verifier_env *env)
{
        return env->cur_state->in_sleepable;
}

/* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock()
 * can dereference RCU protected pointers and result is PTR_TRUSTED.
 */
static bool in_rcu_cs(struct bpf_verifier_env *env)
{
        return env->cur_state->active_rcu_locks ||
               env->cur_state->active_locks ||
               !in_sleepable(env);
}

/* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */
BTF_SET_START(rcu_protected_types)
#ifdef CONFIG_NET
BTF_ID(struct, prog_test_ref_kfunc)
#endif
#ifdef CONFIG_CGROUPS
BTF_ID(struct, cgroup)
#endif
#ifdef CONFIG_BPF_JIT
BTF_ID(struct, bpf_cpumask)
#endif
BTF_ID(struct, task_struct)
#ifdef CONFIG_CRYPTO
BTF_ID(struct, bpf_crypto_ctx)
#endif
BTF_SET_END(rcu_protected_types)

static bool rcu_protected_object(const struct btf *btf, u32 btf_id)
{
        if (!btf_is_kernel(btf))
                return true;
        return btf_id_set_contains(&rcu_protected_types, btf_id);
}

static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field)
{
        struct btf_struct_meta *meta;

        if (btf_is_kernel(kptr_field->kptr.btf))
                return NULL;

        meta = btf_find_struct_meta(kptr_field->kptr.btf,
                                    kptr_field->kptr.btf_id);

        return meta ? meta->record : NULL;
}

static bool rcu_safe_kptr(const struct btf_field *field)
{
        const struct btf_field_kptr *kptr = &field->kptr;

        return field->type == BPF_KPTR_PERCPU ||
               (field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id));
}

static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field)
{
        struct btf_record *rec;
        u32 ret;

        ret = PTR_MAYBE_NULL;
        if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) {
                ret |= MEM_RCU;
                if (kptr_field->type == BPF_KPTR_PERCPU)
                        ret |= MEM_PERCPU;
                else if (!btf_is_kernel(kptr_field->kptr.btf))
                        ret |= MEM_ALLOC;

                rec = kptr_pointee_btf_record(kptr_field);
                if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE))
                        ret |= NON_OWN_REF;
        } else {
                ret |= PTR_UNTRUSTED;
        }

        return ret;
}

static int mark_uptr_ld_reg(struct bpf_verifier_env *env, u32 regno,
                            struct btf_field *field)
{
        struct bpf_reg_state *reg;
        const struct btf_type *t;

        t = btf_type_by_id(field->kptr.btf, field->kptr.btf_id);
        mark_reg_known_zero(env, cur_regs(env), regno);
        reg = reg_state(env, regno);
        reg->type = PTR_TO_MEM | PTR_MAYBE_NULL;
        reg->mem_size = t->size;
        reg->id = ++env->id_gen;

        return 0;
}

static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno,
                                 int value_regno, int insn_idx,
                                 struct btf_field *kptr_field)
{
        struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
        int class = BPF_CLASS(insn->code);
        struct bpf_reg_state *val_reg;
        int ret;

        /* Things we already checked for in check_map_access and caller:
         *  - Reject cases where variable offset may touch kptr
         *  - size of access (must be BPF_DW)
         *  - tnum_is_const(reg->var_off)
         *  - kptr_field->offset == off + reg->var_off.value
         */
        /* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */
        if (BPF_MODE(insn->code) != BPF_MEM) {
                verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n");
                return -EACCES;
        }

        /* We only allow loading referenced kptr, since it will be marked as
         * untrusted, similar to unreferenced kptr.
         */
        if (class != BPF_LDX &&
            (kptr_field->type == BPF_KPTR_REF || kptr_field->type == BPF_KPTR_PERCPU)) {
                verbose(env, "store to referenced kptr disallowed\n");
                return -EACCES;
        }
        if (class != BPF_LDX && kptr_field->type == BPF_UPTR) {
                verbose(env, "store to uptr disallowed\n");
                return -EACCES;
        }

        if (class == BPF_LDX) {
                if (kptr_field->type == BPF_UPTR)
                        return mark_uptr_ld_reg(env, value_regno, kptr_field);

                /* We can simply mark the value_regno receiving the pointer
                 * value from map as PTR_TO_BTF_ID, with the correct type.
                 */
                ret = mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID,
                                      kptr_field->kptr.btf, kptr_field->kptr.btf_id,
                                      btf_ld_kptr_type(env, kptr_field));
                if (ret < 0)
                        return ret;
        } else if (class == BPF_STX) {
                val_reg = reg_state(env, value_regno);
                if (!bpf_register_is_null(val_reg) &&
                    map_kptr_match_type(env, kptr_field, val_reg, value_regno))
                        return -EACCES;
        } else if (class == BPF_ST) {
                if (insn->imm) {
                        verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n",
                                kptr_field->offset);
                        return -EACCES;
                }
        } else {
                verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n");
                return -EACCES;
        }
        return 0;
}

/*
 * Return the size of the memory region accessible from a pointer to map value.
 * For INSN_ARRAY maps whole bpf_insn_array->ips array is accessible.
 */
static u32 map_mem_size(const struct bpf_map *map)
{
        if (map->map_type == BPF_MAP_TYPE_INSN_ARRAY)
                return map->max_entries * sizeof(long);

        return map->value_size;
}

/* check read/write into a map element with possible variable offset */
static int check_map_access(struct bpf_verifier_env *env, u32 regno,
                            int off, int size, bool zero_size_allowed,
                            enum bpf_access_src src)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *reg = &state->regs[regno];
        struct bpf_map *map = reg->map_ptr;
        u32 mem_size = map_mem_size(map);
        struct btf_record *rec;
        int err, i;

        err = check_mem_region_access(env, regno, off, size, mem_size, zero_size_allowed);
        if (err)
                return err;

        if (IS_ERR_OR_NULL(map->record))
                return 0;
        rec = map->record;
        for (i = 0; i < rec->cnt; i++) {
                struct btf_field *field = &rec->fields[i];
                u32 p = field->offset;

                /* If any part of a field  can be touched by load/store, reject
                 * this program. To check that [x1, x2) overlaps with [y1, y2),
                 * it is sufficient to check x1 < y2 && y1 < x2.
                 */
                if (reg->smin_value + off < p + field->size &&
                    p < reg->umax_value + off + size) {
                        switch (field->type) {
                        case BPF_KPTR_UNREF:
                        case BPF_KPTR_REF:
                        case BPF_KPTR_PERCPU:
                        case BPF_UPTR:
                                if (src != ACCESS_DIRECT) {
                                        verbose(env, "%s cannot be accessed indirectly by helper\n",
                                                btf_field_type_name(field->type));
                                        return -EACCES;
                                }
                                if (!tnum_is_const(reg->var_off)) {
                                        verbose(env, "%s access cannot have variable offset\n",
                                                btf_field_type_name(field->type));
                                        return -EACCES;
                                }
                                if (p != off + reg->var_off.value) {
                                        verbose(env, "%s access misaligned expected=%u off=%llu\n",
                                                btf_field_type_name(field->type),
                                                p, off + reg->var_off.value);
                                        return -EACCES;
                                }
                                if (size != bpf_size_to_bytes(BPF_DW)) {
                                        verbose(env, "%s access size must be BPF_DW\n",
                                                btf_field_type_name(field->type));
                                        return -EACCES;
                                }
                                break;
                        default:
                                verbose(env, "%s cannot be accessed directly by load/store\n",
                                        btf_field_type_name(field->type));
                                return -EACCES;
                        }
                }
        }
        return 0;
}

static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
                               const struct bpf_call_arg_meta *meta,
                               enum bpf_access_type t)
{
        enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

        switch (prog_type) {
        /* Program types only with direct read access go here! */
        case BPF_PROG_TYPE_LWT_IN:
        case BPF_PROG_TYPE_LWT_OUT:
        case BPF_PROG_TYPE_LWT_SEG6LOCAL:
        case BPF_PROG_TYPE_SK_REUSEPORT:
        case BPF_PROG_TYPE_FLOW_DISSECTOR:
        case BPF_PROG_TYPE_CGROUP_SKB:
                if (t == BPF_WRITE)
                        return false;
                fallthrough;

        /* Program types with direct read + write access go here! */
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
        case BPF_PROG_TYPE_XDP:
        case BPF_PROG_TYPE_LWT_XMIT:
        case BPF_PROG_TYPE_SK_SKB:
        case BPF_PROG_TYPE_SK_MSG:
                if (meta)
                        return meta->pkt_access;

                env->seen_direct_write = true;
                return true;

        case BPF_PROG_TYPE_CGROUP_SOCKOPT:
                if (t == BPF_WRITE)
                        env->seen_direct_write = true;

                return true;

        default:
                return false;
        }
}

static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
                               int size, bool zero_size_allowed)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        int err;

        if (reg->range < 0) {
                verbose(env, "R%d offset is outside of the packet\n", regno);
                return -EINVAL;
        }

        err = check_mem_region_access(env, regno, off, size, reg->range, zero_size_allowed);
        if (err)
                return err;

        /* __check_mem_access has made sure "off + size - 1" is within u16.
         * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
         * otherwise find_good_pkt_pointers would have refused to set range info
         * that __check_mem_access would have rejected this pkt access.
         * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
         */
        env->prog->aux->max_pkt_offset =
                max_t(u32, env->prog->aux->max_pkt_offset,
                      off + reg->umax_value + size - 1);

        return 0;
}

static bool is_var_ctx_off_allowed(struct bpf_prog *prog)
{
        return resolve_prog_type(prog) == BPF_PROG_TYPE_SYSCALL;
}

/* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
static int __check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
                              enum bpf_access_type t, struct bpf_insn_access_aux *info)
{
        if (env->ops->is_valid_access &&
            env->ops->is_valid_access(off, size, t, env->prog, info)) {
                /* A non zero info.ctx_field_size indicates that this field is a
                 * candidate for later verifier transformation to load the whole
                 * field and then apply a mask when accessed with a narrower
                 * access than actual ctx access size. A zero info.ctx_field_size
                 * will only allow for whole field access and rejects any other
                 * type of narrower access.
                 */
                if (base_type(info->reg_type) == PTR_TO_BTF_ID) {
                        if (info->ref_obj_id &&
                            !find_reference_state(env->cur_state, info->ref_obj_id)) {
                                verbose(env, "invalid bpf_context access off=%d. Reference may already be released\n",
                                        off);
                                return -EACCES;
                        }
                } else {
                        env->insn_aux_data[insn_idx].ctx_field_size = info->ctx_field_size;
                }
                /* remember the offset of last byte accessed in ctx */
                if (env->prog->aux->max_ctx_offset < off + size)
                        env->prog->aux->max_ctx_offset = off + size;
                return 0;
        }

        verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
        return -EACCES;
}

static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
                            int off, int access_size, enum bpf_access_type t,
                            struct bpf_insn_access_aux *info)
{
        /*
         * Program types that don't rewrite ctx accesses can safely
         * dereference ctx pointers with fixed offsets.
         */
        bool var_off_ok = is_var_ctx_off_allowed(env->prog);
        bool fixed_off_ok = !env->ops->convert_ctx_access;
        struct bpf_reg_state *regs = cur_regs(env);
        struct bpf_reg_state *reg = regs + regno;
        int err;

        if (var_off_ok)
                err = check_mem_region_access(env, regno, off, access_size, U16_MAX, false);
        else
                err = __check_ptr_off_reg(env, reg, regno, fixed_off_ok);
        if (err)
                return err;
        off += reg->umax_value;

        err = __check_ctx_access(env, insn_idx, off, access_size, t, info);
        if (err)
                verbose_linfo(env, insn_idx, "; ");
        return err;
}

static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
                                  int size)
{
        if (size < 0 || off < 0 ||
            (u64)off + size > sizeof(struct bpf_flow_keys)) {
                verbose(env, "invalid access to flow keys off=%d size=%d\n",
                        off, size);
                return -EACCES;
        }
        return 0;
}

static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
                             u32 regno, int off, int size,
                             enum bpf_access_type t)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_insn_access_aux info = {};
        bool valid;

        if (reg->smin_value < 0) {
                verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
                        regno);
                return -EACCES;
        }

        switch (reg->type) {
        case PTR_TO_SOCK_COMMON:
                valid = bpf_sock_common_is_valid_access(off, size, t, &info);
                break;
        case PTR_TO_SOCKET:
                valid = bpf_sock_is_valid_access(off, size, t, &info);
                break;
        case PTR_TO_TCP_SOCK:
                valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
                break;
        case PTR_TO_XDP_SOCK:
                valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
                break;
        default:
                valid = false;
        }


        if (valid) {
                env->insn_aux_data[insn_idx].ctx_field_size =
                        info.ctx_field_size;
                return 0;
        }

        verbose(env, "R%d invalid %s access off=%d size=%d\n",
                regno, reg_type_str(env, reg->type), off, size);

        return -EACCES;
}

static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
{
        return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
}

static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
{
        const struct bpf_reg_state *reg = reg_state(env, regno);

        return reg->type == PTR_TO_CTX;
}

static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
{
        const struct bpf_reg_state *reg = reg_state(env, regno);

        return type_is_sk_pointer(reg->type);
}

static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
{
        const struct bpf_reg_state *reg = reg_state(env, regno);

        return type_is_pkt_pointer(reg->type);
}

static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
{
        const struct bpf_reg_state *reg = reg_state(env, regno);

        /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
        return reg->type == PTR_TO_FLOW_KEYS;
}

static bool is_arena_reg(struct bpf_verifier_env *env, int regno)
{
        const struct bpf_reg_state *reg = reg_state(env, regno);

        return reg->type == PTR_TO_ARENA;
}

/* Return false if @regno contains a pointer whose type isn't supported for
 * atomic instruction @insn.
 */
static bool atomic_ptr_type_ok(struct bpf_verifier_env *env, int regno,
                               struct bpf_insn *insn)
{
        if (is_ctx_reg(env, regno))
                return false;
        if (is_pkt_reg(env, regno))
                return false;
        if (is_flow_key_reg(env, regno))
                return false;
        if (is_sk_reg(env, regno))
                return false;
        if (is_arena_reg(env, regno))
                return bpf_jit_supports_insn(insn, true);

        return true;
}

static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
#ifdef CONFIG_NET
        [PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
        [PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
        [PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
#endif
        [CONST_PTR_TO_MAP] = btf_bpf_map_id,
};

static bool is_trusted_reg(const struct bpf_reg_state *reg)
{
        /* A referenced register is always trusted. */
        if (reg->ref_obj_id)
                return true;

        /* Types listed in the reg2btf_ids are always trusted */
        if (reg2btf_ids[base_type(reg->type)] &&
            !bpf_type_has_unsafe_modifiers(reg->type))
                return true;

        /* If a register is not referenced, it is trusted if it has the
         * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the
         * other type modifiers may be safe, but we elect to take an opt-in
         * approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are
         * not.
         *
         * Eventually, we should make PTR_TRUSTED the single source of truth
         * for whether a register is trusted.
         */
        return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS &&
               !bpf_type_has_unsafe_modifiers(reg->type);
}

static bool is_rcu_reg(const struct bpf_reg_state *reg)
{
        return reg->type & MEM_RCU;
}

static void clear_trusted_flags(enum bpf_type_flag *flag)
{
        *flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU);
}

static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
                                   const struct bpf_reg_state *reg,
                                   int off, int size, bool strict)
{
        struct tnum reg_off;
        int ip_align;

        /* Byte size accesses are always allowed. */
        if (!strict || size == 1)
                return 0;

        /* For platforms that do not have a Kconfig enabling
         * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
         * NET_IP_ALIGN is universally set to '2'.  And on platforms
         * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
         * to this code only in strict mode where we want to emulate
         * the NET_IP_ALIGN==2 checking.  Therefore use an
         * unconditional IP align value of '2'.
         */
        ip_align = 2;

        reg_off = tnum_add(reg->var_off, tnum_const(ip_align + off));
        if (!tnum_is_aligned(reg_off, size)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env,
                        "misaligned packet access off %d+%s+%d size %d\n",
                        ip_align, tn_buf, off, size);
                return -EACCES;
        }

        return 0;
}

static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
                                       const struct bpf_reg_state *reg,
                                       const char *pointer_desc,
                                       int off, int size, bool strict)
{
        struct tnum reg_off;

        /* Byte size accesses are always allowed. */
        if (!strict || size == 1)
                return 0;

        reg_off = tnum_add(reg->var_off, tnum_const(off));
        if (!tnum_is_aligned(reg_off, size)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env, "misaligned %saccess off %s+%d size %d\n",
                        pointer_desc, tn_buf, off, size);
                return -EACCES;
        }

        return 0;
}

static int check_ptr_alignment(struct bpf_verifier_env *env,
                               const struct bpf_reg_state *reg, int off,
                               int size, bool strict_alignment_once)
{
        bool strict = env->strict_alignment || strict_alignment_once;
        const char *pointer_desc = "";

        switch (reg->type) {
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
                /* Special case, because of NET_IP_ALIGN. Given metadata sits
                 * right in front, treat it the very same way.
                 */
                return check_pkt_ptr_alignment(env, reg, off, size, strict);
        case PTR_TO_FLOW_KEYS:
                pointer_desc = "flow keys ";
                break;
        case PTR_TO_MAP_KEY:
                pointer_desc = "key ";
                break;
        case PTR_TO_MAP_VALUE:
                pointer_desc = "value ";
                if (reg->map_ptr->map_type == BPF_MAP_TYPE_INSN_ARRAY)
                        strict = true;
                break;
        case PTR_TO_CTX:
                pointer_desc = "context ";
                break;
        case PTR_TO_STACK:
                pointer_desc = "stack ";
                /* The stack spill tracking logic in check_stack_write_fixed_off()
                 * and check_stack_read_fixed_off() relies on stack accesses being
                 * aligned.
                 */
                strict = true;
                break;
        case PTR_TO_SOCKET:
                pointer_desc = "sock ";
                break;
        case PTR_TO_SOCK_COMMON:
                pointer_desc = "sock_common ";
                break;
        case PTR_TO_TCP_SOCK:
                pointer_desc = "tcp_sock ";
                break;
        case PTR_TO_XDP_SOCK:
                pointer_desc = "xdp_sock ";
                break;
        case PTR_TO_ARENA:
                return 0;
        default:
                break;
        }
        return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
                                           strict);
}

static enum priv_stack_mode bpf_enable_priv_stack(struct bpf_prog *prog)
{
        if (!bpf_jit_supports_private_stack())
                return NO_PRIV_STACK;

        /* bpf_prog_check_recur() checks all prog types that use bpf trampoline
         * while kprobe/tp/perf_event/raw_tp don't use trampoline hence checked
         * explicitly.
         */
        switch (prog->type) {
        case BPF_PROG_TYPE_KPROBE:
        case BPF_PROG_TYPE_TRACEPOINT:
        case BPF_PROG_TYPE_PERF_EVENT:
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
                return PRIV_STACK_ADAPTIVE;
        case BPF_PROG_TYPE_TRACING:
        case BPF_PROG_TYPE_LSM:
        case BPF_PROG_TYPE_STRUCT_OPS:
                if (prog->aux->priv_stack_requested || bpf_prog_check_recur(prog))
                        return PRIV_STACK_ADAPTIVE;
                fallthrough;
        default:
                break;
        }

        return NO_PRIV_STACK;
}

static int round_up_stack_depth(struct bpf_verifier_env *env, int stack_depth)
{
        if (env->prog->jit_requested)
                return round_up(stack_depth, 16);

        /* round up to 32-bytes, since this is granularity
         * of interpreter stack size
         */
        return round_up(max_t(u32, stack_depth, 1), 32);
}

/* temporary state used for call frame depth calculation */
struct bpf_subprog_call_depth_info {
        int ret_insn; /* caller instruction where we return to. */
        int caller; /* caller subprogram idx */
        int frame; /* # of consecutive static call stack frames on top of stack */
};

/* starting from main bpf function walk all instructions of the function
 * and recursively walk all callees that given function can call.
 * Ignore jump and exit insns.
 */
static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
                                         struct bpf_subprog_call_depth_info *dinfo,
                                         bool priv_stack_supported)
{
        struct bpf_subprog_info *subprog = env->subprog_info;
        struct bpf_insn *insn = env->prog->insnsi;
        int depth = 0, frame = 0, i, subprog_end, subprog_depth;
        bool tail_call_reachable = false;
        int total;
        int tmp;

        /* no caller idx */
        dinfo[idx].caller = -1;

        i = subprog[idx].start;
        if (!priv_stack_supported)
                subprog[idx].priv_stack_mode = NO_PRIV_STACK;
process_func:
        /* protect against potential stack overflow that might happen when
         * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
         * depth for such case down to 256 so that the worst case scenario
         * would result in 8k stack size (32 which is tailcall limit * 256 =
         * 8k).
         *
         * To get the idea what might happen, see an example:
         * func1 -> sub rsp, 128
         *  subfunc1 -> sub rsp, 256
         *  tailcall1 -> add rsp, 256
         *   func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
         *   subfunc2 -> sub rsp, 64
         *   subfunc22 -> sub rsp, 128
         *   tailcall2 -> add rsp, 128
         *    func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
         *
         * tailcall will unwind the current stack frame but it will not get rid
         * of caller's stack as shown on the example above.
         */
        if (idx && subprog[idx].has_tail_call && depth >= 256) {
                verbose(env,
                        "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
                        depth);
                return -EACCES;
        }

        subprog_depth = round_up_stack_depth(env, subprog[idx].stack_depth);
        if (priv_stack_supported) {
                /* Request private stack support only if the subprog stack
                 * depth is no less than BPF_PRIV_STACK_MIN_SIZE. This is to
                 * avoid jit penalty if the stack usage is small.
                 */
                if (subprog[idx].priv_stack_mode == PRIV_STACK_UNKNOWN &&
                    subprog_depth >= BPF_PRIV_STACK_MIN_SIZE)
                        subprog[idx].priv_stack_mode = PRIV_STACK_ADAPTIVE;
        }

        if (subprog[idx].priv_stack_mode == PRIV_STACK_ADAPTIVE) {
                if (subprog_depth > MAX_BPF_STACK) {
                        verbose(env, "stack size of subprog %d is %d. Too large\n",
                                idx, subprog_depth);
                        return -EACCES;
                }
        } else {
                depth += subprog_depth;
                if (depth > MAX_BPF_STACK) {
                        total = 0;
                        for (tmp = idx; tmp >= 0; tmp = dinfo[tmp].caller)
                                total++;

                        verbose(env, "combined stack size of %d calls is %d. Too large\n",
                                total, depth);
                        return -EACCES;
                }
        }
continue_func:
        subprog_end = subprog[idx + 1].start;
        for (; i < subprog_end; i++) {
                int next_insn, sidx;

                if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) {
                        bool err = false;

                        if (!is_bpf_throw_kfunc(insn + i))
                                continue;
                        for (tmp = idx; tmp >= 0 && !err; tmp = dinfo[tmp].caller) {
                                if (subprog[tmp].is_cb) {
                                        err = true;
                                        break;
                                }
                        }
                        if (!err)
                                continue;
                        verbose(env,
                                "bpf_throw kfunc (insn %d) cannot be called from callback subprog %d\n",
                                i, idx);
                        return -EINVAL;
                }

                if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
                        continue;
                /* remember insn and function to return to */

                /* find the callee */
                next_insn = i + insn[i].imm + 1;
                sidx = bpf_find_subprog(env, next_insn);
                if (verifier_bug_if(sidx < 0, env, "callee not found at insn %d", next_insn))
                        return -EFAULT;
                if (subprog[sidx].is_async_cb) {
                        if (subprog[sidx].has_tail_call) {
                                verifier_bug(env, "subprog has tail_call and async cb");
                                return -EFAULT;
                        }
                        /* async callbacks don't increase bpf prog stack size unless called directly */
                        if (!bpf_pseudo_call(insn + i))
                                continue;
                        if (subprog[sidx].is_exception_cb) {
                                verbose(env, "insn %d cannot call exception cb directly", i);
                                return -EINVAL;
                        }
                }

                /* store caller info for after we return from callee */
                dinfo[idx].frame = frame;
                dinfo[idx].ret_insn = i + 1;

                /* push caller idx into callee's dinfo */
                dinfo[sidx].caller = idx;

                i = next_insn;

                idx = sidx;
                if (!priv_stack_supported)
                        subprog[idx].priv_stack_mode = NO_PRIV_STACK;

                if (subprog[idx].has_tail_call)
                        tail_call_reachable = true;

                frame = bpf_subprog_is_global(env, idx) ? 0 : frame + 1;
                if (frame >= MAX_CALL_FRAMES) {
                        verbose(env, "the call stack of %d frames is too deep !\n",
                                frame);
                        return -E2BIG;
                }
                goto process_func;
        }
        /* if tail call got detected across bpf2bpf calls then mark each of the
         * currently present subprog frames as tail call reachable subprogs;
         * this info will be utilized by JIT so that we will be preserving the
         * tail call counter throughout bpf2bpf calls combined with tailcalls
         */
        if (tail_call_reachable)
                for (tmp = idx; tmp >= 0; tmp = dinfo[tmp].caller) {
                        if (subprog[tmp].is_exception_cb) {
                                verbose(env, "cannot tail call within exception cb\n");
                                return -EINVAL;
                        }
                        subprog[tmp].tail_call_reachable = true;
                }
        if (subprog[0].tail_call_reachable)
                env->prog->aux->tail_call_reachable = true;

        /* end of for() loop means the last insn of the 'subprog'
         * was reached. Doesn't matter whether it was JA or EXIT
         */
        if (frame == 0 && dinfo[idx].caller < 0)
                return 0;
        if (subprog[idx].priv_stack_mode != PRIV_STACK_ADAPTIVE)
                depth -= round_up_stack_depth(env, subprog[idx].stack_depth);

        /* pop caller idx from callee */
        idx = dinfo[idx].caller;

        /* retrieve caller state from its frame */
        frame = dinfo[idx].frame;
        i = dinfo[idx].ret_insn;

        goto continue_func;
}

static int check_max_stack_depth(struct bpf_verifier_env *env)
{
        enum priv_stack_mode priv_stack_mode = PRIV_STACK_UNKNOWN;
        struct bpf_subprog_call_depth_info *dinfo;
        struct bpf_subprog_info *si = env->subprog_info;
        bool priv_stack_supported;
        int ret;

        dinfo = kvcalloc(env->subprog_cnt, sizeof(*dinfo), GFP_KERNEL_ACCOUNT);
        if (!dinfo)
                return -ENOMEM;

        for (int i = 0; i < env->subprog_cnt; i++) {
                if (si[i].has_tail_call) {
                        priv_stack_mode = NO_PRIV_STACK;
                        break;
                }
        }

        if (priv_stack_mode == PRIV_STACK_UNKNOWN)
                priv_stack_mode = bpf_enable_priv_stack(env->prog);

        /* All async_cb subprogs use normal kernel stack. If a particular
         * subprog appears in both main prog and async_cb subtree, that
         * subprog will use normal kernel stack to avoid potential nesting.
         * The reverse subprog traversal ensures when main prog subtree is
         * checked, the subprogs appearing in async_cb subtrees are already
         * marked as using normal kernel stack, so stack size checking can
         * be done properly.
         */
        for (int i = env->subprog_cnt - 1; i >= 0; i--) {
                if (!i || si[i].is_async_cb) {
                        priv_stack_supported = !i && priv_stack_mode == PRIV_STACK_ADAPTIVE;
                        ret = check_max_stack_depth_subprog(env, i, dinfo,
                                        priv_stack_supported);
                        if (ret < 0) {
                                kvfree(dinfo);
                                return ret;
                        }
                }
        }

        for (int i = 0; i < env->subprog_cnt; i++) {
                if (si[i].priv_stack_mode == PRIV_STACK_ADAPTIVE) {
                        env->prog->aux->jits_use_priv_stack = true;
                        break;
                }
        }

        kvfree(dinfo);

        return 0;
}

static int __check_buffer_access(struct bpf_verifier_env *env,
                                 const char *buf_info,
                                 const struct bpf_reg_state *reg,
                                 int regno, int off, int size)
{
        if (off < 0) {
                verbose(env,
                        "R%d invalid %s buffer access: off=%d, size=%d\n",
                        regno, buf_info, off, size);
                return -EACCES;
        }
        if (!tnum_is_const(reg->var_off)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env,
                        "R%d invalid variable buffer offset: off=%d, var_off=%s\n",
                        regno, off, tn_buf);
                return -EACCES;
        }

        return 0;
}

static int check_tp_buffer_access(struct bpf_verifier_env *env,
                                  const struct bpf_reg_state *reg,
                                  int regno, int off, int size)
{
        int err;

        err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
        if (err)
                return err;

        env->prog->aux->max_tp_access = max(reg->var_off.value + off + size,
                                            env->prog->aux->max_tp_access);

        return 0;
}

static int check_buffer_access(struct bpf_verifier_env *env,
                               const struct bpf_reg_state *reg,
                               int regno, int off, int size,
                               bool zero_size_allowed,
                               u32 *max_access)
{
        const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
        int err;

        err = __check_buffer_access(env, buf_info, reg, regno, off, size);
        if (err)
                return err;

        *max_access = max(reg->var_off.value + off + size, *max_access);

        return 0;
}

/* BPF architecture zero extends alu32 ops into 64-bit registesr */
static void zext_32_to_64(struct bpf_reg_state *reg)
{
        reg->var_off = tnum_subreg(reg->var_off);
        __reg_assign_32_into_64(reg);
}

/* truncate register to smaller size (in bytes)
 * must be called with size < BPF_REG_SIZE
 */
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
{
        u64 mask;

        /* clear high bits in bit representation */
        reg->var_off = tnum_cast(reg->var_off, size);

        /* fix arithmetic bounds */
        mask = ((u64)1 << (size * 8)) - 1;
        if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
                reg->umin_value &= mask;
                reg->umax_value &= mask;
        } else {
                reg->umin_value = 0;
                reg->umax_value = mask;
        }
        reg->smin_value = reg->umin_value;
        reg->smax_value = reg->umax_value;

        /* If size is smaller than 32bit register the 32bit register
         * values are also truncated so we push 64-bit bounds into
         * 32-bit bounds. Above were truncated < 32-bits already.
         */
        if (size < 4)
                __mark_reg32_unbounded(reg);

        reg_bounds_sync(reg);
}

static void set_sext64_default_val(struct bpf_reg_state *reg, int size)
{
        if (size == 1) {
                reg->smin_value = reg->s32_min_value = S8_MIN;
                reg->smax_value = reg->s32_max_value = S8_MAX;
        } else if (size == 2) {
                reg->smin_value = reg->s32_min_value = S16_MIN;
                reg->smax_value = reg->s32_max_value = S16_MAX;
        } else {
                /* size == 4 */
                reg->smin_value = reg->s32_min_value = S32_MIN;
                reg->smax_value = reg->s32_max_value = S32_MAX;
        }
        reg->umin_value = reg->u32_min_value = 0;
        reg->umax_value = U64_MAX;
        reg->u32_max_value = U32_MAX;
        reg->var_off = tnum_unknown;
}

static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size)
{
        s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval;
        u64 top_smax_value, top_smin_value;
        u64 num_bits = size * 8;

        if (tnum_is_const(reg->var_off)) {
                u64_cval = reg->var_off.value;
                if (size == 1)
                        reg->var_off = tnum_const((s8)u64_cval);
                else if (size == 2)
                        reg->var_off = tnum_const((s16)u64_cval);
                else
                        /* size == 4 */
                        reg->var_off = tnum_const((s32)u64_cval);

                u64_cval = reg->var_off.value;
                reg->smax_value = reg->smin_value = u64_cval;
                reg->umax_value = reg->umin_value = u64_cval;
                reg->s32_max_value = reg->s32_min_value = u64_cval;
                reg->u32_max_value = reg->u32_min_value = u64_cval;
                return;
        }

        top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits;
        top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits;

        if (top_smax_value != top_smin_value)
                goto out;

        /* find the s64_min and s64_min after sign extension */
        if (size == 1) {
                init_s64_max = (s8)reg->smax_value;
                init_s64_min = (s8)reg->smin_value;
        } else if (size == 2) {
                init_s64_max = (s16)reg->smax_value;
                init_s64_min = (s16)reg->smin_value;
        } else {
                init_s64_max = (s32)reg->smax_value;
                init_s64_min = (s32)reg->smin_value;
        }

        s64_max = max(init_s64_max, init_s64_min);
        s64_min = min(init_s64_max, init_s64_min);

        /* both of s64_max/s64_min positive or negative */
        if ((s64_max >= 0) == (s64_min >= 0)) {
                reg->s32_min_value = reg->smin_value = s64_min;
                reg->s32_max_value = reg->smax_value = s64_max;
                reg->u32_min_value = reg->umin_value = s64_min;
                reg->u32_max_value = reg->umax_value = s64_max;
                reg->var_off = tnum_range(s64_min, s64_max);
                return;
        }

out:
        set_sext64_default_val(reg, size);
}

static void set_sext32_default_val(struct bpf_reg_state *reg, int size)
{
        if (size == 1) {
                reg->s32_min_value = S8_MIN;
                reg->s32_max_value = S8_MAX;
        } else {
                /* size == 2 */
                reg->s32_min_value = S16_MIN;
                reg->s32_max_value = S16_MAX;
        }
        reg->u32_min_value = 0;
        reg->u32_max_value = U32_MAX;
        reg->var_off = tnum_subreg(tnum_unknown);
}

static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size)
{
        s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val;
        u32 top_smax_value, top_smin_value;
        u32 num_bits = size * 8;

        if (tnum_is_const(reg->var_off)) {
                u32_val = reg->var_off.value;
                if (size == 1)
                        reg->var_off = tnum_const((s8)u32_val);
                else
                        reg->var_off = tnum_const((s16)u32_val);

                u32_val = reg->var_off.value;
                reg->s32_min_value = reg->s32_max_value = u32_val;
                reg->u32_min_value = reg->u32_max_value = u32_val;
                return;
        }

        top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits;
        top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits;

        if (top_smax_value != top_smin_value)
                goto out;

        /* find the s32_min and s32_min after sign extension */
        if (size == 1) {
                init_s32_max = (s8)reg->s32_max_value;
                init_s32_min = (s8)reg->s32_min_value;
        } else {
                /* size == 2 */
                init_s32_max = (s16)reg->s32_max_value;
                init_s32_min = (s16)reg->s32_min_value;
        }
        s32_max = max(init_s32_max, init_s32_min);
        s32_min = min(init_s32_max, init_s32_min);

        if ((s32_min >= 0) == (s32_max >= 0)) {
                reg->s32_min_value = s32_min;
                reg->s32_max_value = s32_max;
                reg->u32_min_value = (u32)s32_min;
                reg->u32_max_value = (u32)s32_max;
                reg->var_off = tnum_subreg(tnum_range(s32_min, s32_max));
                return;
        }

out:
        set_sext32_default_val(reg, size);
}

bool bpf_map_is_rdonly(const struct bpf_map *map)
{
        /* A map is considered read-only if the following condition are true:
         *
         * 1) BPF program side cannot change any of the map content. The
         *    BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
         *    and was set at map creation time.
         * 2) The map value(s) have been initialized from user space by a
         *    loader and then "frozen", such that no new map update/delete
         *    operations from syscall side are possible for the rest of
         *    the map's lifetime from that point onwards.
         * 3) Any parallel/pending map update/delete operations from syscall
         *    side have been completed. Only after that point, it's safe to
         *    assume that map value(s) are immutable.
         */
        return (map->map_flags & BPF_F_RDONLY_PROG) &&
               READ_ONCE(map->frozen) &&
               !bpf_map_write_active(map);
}

int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val,
                        bool is_ldsx)
{
        void *ptr;
        u64 addr;
        int err;

        err = map->ops->map_direct_value_addr(map, &addr, off);
        if (err)
                return err;
        ptr = (void *)(long)addr + off;

        switch (size) {
        case sizeof(u8):
                *val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr;
                break;
        case sizeof(u16):
                *val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr;
                break;
        case sizeof(u32):
                *val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr;
                break;
        case sizeof(u64):
                *val = *(u64 *)ptr;
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

#define BTF_TYPE_SAFE_RCU(__type)  __PASTE(__type, __safe_rcu)
#define BTF_TYPE_SAFE_RCU_OR_NULL(__type)  __PASTE(__type, __safe_rcu_or_null)
#define BTF_TYPE_SAFE_TRUSTED(__type)  __PASTE(__type, __safe_trusted)
#define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type)  __PASTE(__type, __safe_trusted_or_null)

/*
 * Allow list few fields as RCU trusted or full trusted.
 * This logic doesn't allow mix tagging and will be removed once GCC supports
 * btf_type_tag.
 */

/* RCU trusted: these fields are trusted in RCU CS and never NULL */
BTF_TYPE_SAFE_RCU(struct task_struct) {
        const cpumask_t *cpus_ptr;
        struct css_set __rcu *cgroups;
        struct task_struct __rcu *real_parent;
        struct task_struct *group_leader;
};

BTF_TYPE_SAFE_RCU(struct cgroup) {
        /* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */
        struct kernfs_node *kn;
};

BTF_TYPE_SAFE_RCU(struct css_set) {
        struct cgroup *dfl_cgrp;
};

BTF_TYPE_SAFE_RCU(struct cgroup_subsys_state) {
        struct cgroup *cgroup;
};

/* RCU trusted: these fields are trusted in RCU CS and can be NULL */
BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {
        struct file __rcu *exe_file;
#ifdef CONFIG_MEMCG
        struct task_struct __rcu *owner;
#endif
};

/* skb->sk, req->sk are not RCU protected, but we mark them as such
 * because bpf prog accessible sockets are SOCK_RCU_FREE.
 */
BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) {
        struct sock *sk;
};

BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) {
        struct sock *sk;
};

/* full trusted: these fields are trusted even outside of RCU CS and never NULL */
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) {
        struct seq_file *seq;
};

BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) {
        struct bpf_iter_meta *meta;
        struct task_struct *task;
};

BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) {
        struct file *file;
};

BTF_TYPE_SAFE_TRUSTED(struct file) {
        struct inode *f_inode;
};

BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) {
        struct inode *d_inode;
};

BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) {
        struct sock *sk;
};

BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct) {
        struct mm_struct *vm_mm;
        struct file *vm_file;
};

static bool type_is_rcu(struct bpf_verifier_env *env,
                        struct bpf_reg_state *reg,
                        const char *field_name, u32 btf_id)
{
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup_subsys_state));

        return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu");
}

static bool type_is_rcu_or_null(struct bpf_verifier_env *env,
                                struct bpf_reg_state *reg,
                                const char *field_name, u32 btf_id)
{
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock));

        return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null");
}

static bool type_is_trusted(struct bpf_verifier_env *env,
                            struct bpf_reg_state *reg,
                            const char *field_name, u32 btf_id)
{
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));

        return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
}

static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *reg,
                                    const char *field_name, u32 btf_id)
{
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry));
        BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct));

        return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
                                          "__safe_trusted_or_null");
}

static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *regs,
                                   int regno, int off, int size,
                                   enum bpf_access_type atype,
                                   int value_regno)
{
        struct bpf_reg_state *reg = regs + regno;
        const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id);
        const char *tname = btf_name_by_offset(reg->btf, t->name_off);
        const char *field_name = NULL;
        enum bpf_type_flag flag = 0;
        u32 btf_id = 0;
        int ret;

        if (!env->allow_ptr_leaks) {
                verbose(env,
                        "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
                        tname);
                return -EPERM;
        }
        if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) {
                verbose(env,
                        "Cannot access kernel 'struct %s' from non-GPL compatible program\n",
                        tname);
                return -EINVAL;
        }

        if (!tnum_is_const(reg->var_off)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env,
                        "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
                        regno, tname, off, tn_buf);
                return -EACCES;
        }

        off += reg->var_off.value;

        if (off < 0) {
                verbose(env,
                        "R%d is ptr_%s invalid negative access: off=%d\n",
                        regno, tname, off);
                return -EACCES;
        }

        if (reg->type & MEM_USER) {
                verbose(env,
                        "R%d is ptr_%s access user memory: off=%d\n",
                        regno, tname, off);
                return -EACCES;
        }

        if (reg->type & MEM_PERCPU) {
                verbose(env,
                        "R%d is ptr_%s access percpu memory: off=%d\n",
                        regno, tname, off);
                return -EACCES;
        }

        if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) {
                if (!btf_is_kernel(reg->btf)) {
                        verifier_bug(env, "reg->btf must be kernel btf");
                        return -EFAULT;
                }
                ret = env->ops->btf_struct_access(&env->log, reg, off, size);
        } else {
                /* Writes are permitted with default btf_struct_access for
                 * program allocated objects (which always have ref_obj_id > 0),
                 * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC.
                 */
                if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) {
                        verbose(env, "only read is supported\n");
                        return -EACCES;
                }

                if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) &&
                    !(reg->type & MEM_RCU) && !reg->ref_obj_id) {
                        verifier_bug(env, "ref_obj_id for allocated object must be non-zero");
                        return -EFAULT;
                }

                ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name);
        }

        if (ret < 0)
                return ret;

        if (ret != PTR_TO_BTF_ID) {
                /* just mark; */

        } else if (type_flag(reg->type) & PTR_UNTRUSTED) {
                /* If this is an untrusted pointer, all pointers formed by walking it
                 * also inherit the untrusted flag.
                 */
                flag = PTR_UNTRUSTED;

        } else if (is_trusted_reg(reg) || is_rcu_reg(reg)) {
                /* By default any pointer obtained from walking a trusted pointer is no
                 * longer trusted, unless the field being accessed has explicitly been
                 * marked as inheriting its parent's state of trust (either full or RCU).
                 * For example:
                 * 'cgroups' pointer is untrusted if task->cgroups dereference
                 * happened in a sleepable program outside of bpf_rcu_read_lock()
                 * section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU).
                 * Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED.
                 *
                 * A regular RCU-protected pointer with __rcu tag can also be deemed
                 * trusted if we are in an RCU CS. Such pointer can be NULL.
                 */
                if (type_is_trusted(env, reg, field_name, btf_id)) {
                        flag |= PTR_TRUSTED;
                } else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) {
                        flag |= PTR_TRUSTED | PTR_MAYBE_NULL;
                } else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) {
                        if (type_is_rcu(env, reg, field_name, btf_id)) {
                                /* ignore __rcu tag and mark it MEM_RCU */
                                flag |= MEM_RCU;
                        } else if (flag & MEM_RCU ||
                                   type_is_rcu_or_null(env, reg, field_name, btf_id)) {
                                /* __rcu tagged pointers can be NULL */
                                flag |= MEM_RCU | PTR_MAYBE_NULL;

                                /* We always trust them */
                                if (type_is_rcu_or_null(env, reg, field_name, btf_id) &&
                                    flag & PTR_UNTRUSTED)
                                        flag &= ~PTR_UNTRUSTED;
                        } else if (flag & (MEM_PERCPU | MEM_USER)) {
                                /* keep as-is */
                        } else {
                                /* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */
                                clear_trusted_flags(&flag);
                        }
                } else {
                        /*
                         * If not in RCU CS or MEM_RCU pointer can be NULL then
                         * aggressively mark as untrusted otherwise such
                         * pointers will be plain PTR_TO_BTF_ID without flags
                         * and will be allowed to be passed into helpers for
                         * compat reasons.
                         */
                        flag = PTR_UNTRUSTED;
                }
        } else {
                /* Old compat. Deprecated */
                clear_trusted_flags(&flag);
        }

        if (atype == BPF_READ && value_regno >= 0) {
                ret = mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static int check_ptr_to_map_access(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *regs,
                                   int regno, int off, int size,
                                   enum bpf_access_type atype,
                                   int value_regno)
{
        struct bpf_reg_state *reg = regs + regno;
        struct bpf_map *map = reg->map_ptr;
        struct bpf_reg_state map_reg;
        enum bpf_type_flag flag = 0;
        const struct btf_type *t;
        const char *tname;
        u32 btf_id;
        int ret;

        if (!btf_vmlinux) {
                verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
                return -ENOTSUPP;
        }

        if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
                verbose(env, "map_ptr access not supported for map type %d\n",
                        map->map_type);
                return -ENOTSUPP;
        }

        t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
        tname = btf_name_by_offset(btf_vmlinux, t->name_off);

        if (!env->allow_ptr_leaks) {
                verbose(env,
                        "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
                        tname);
                return -EPERM;
        }

        if (off < 0) {
                verbose(env, "R%d is %s invalid negative access: off=%d\n",
                        regno, tname, off);
                return -EACCES;
        }

        if (atype != BPF_READ) {
                verbose(env, "only read from %s is supported\n", tname);
                return -EACCES;
        }

        /* Simulate access to a PTR_TO_BTF_ID */
        memset(&map_reg, 0, sizeof(map_reg));
        ret = mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID,
                              btf_vmlinux, *map->ops->map_btf_id, 0);
        if (ret < 0)
                return ret;
        ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL);
        if (ret < 0)
                return ret;

        if (value_regno >= 0) {
                ret = mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/* Check that the stack access at the given offset is within bounds. The
 * maximum valid offset is -1.
 *
 * The minimum valid offset is -MAX_BPF_STACK for writes, and
 * -state->allocated_stack for reads.
 */
static int check_stack_slot_within_bounds(struct bpf_verifier_env *env,
                                          s64 off,
                                          struct bpf_func_state *state,
                                          enum bpf_access_type t)
{
        int min_valid_off;

        if (t == BPF_WRITE || env->allow_uninit_stack)
                min_valid_off = -MAX_BPF_STACK;
        else
                min_valid_off = -state->allocated_stack;

        if (off < min_valid_off || off > -1)
                return -EACCES;
        return 0;
}

/* Check that the stack access at 'regno + off' falls within the maximum stack
 * bounds.
 *
 * 'off' includes `regno->offset`, but not its dynamic part (if any).
 */
static int check_stack_access_within_bounds(
                struct bpf_verifier_env *env,
                int regno, int off, int access_size,
                enum bpf_access_type type)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_func_state *state = bpf_func(env, reg);
        s64 min_off, max_off;
        int err;
        char *err_extra;

        if (type == BPF_READ)
                err_extra = " read from";
        else
                err_extra = " write to";

        if (tnum_is_const(reg->var_off)) {
                min_off = (s64)reg->var_off.value + off;
                max_off = min_off + access_size;
        } else {
                if (reg->smax_value >= BPF_MAX_VAR_OFF ||
                    reg->smin_value <= -BPF_MAX_VAR_OFF) {
                        verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
                                err_extra, regno);
                        return -EACCES;
                }
                min_off = reg->smin_value + off;
                max_off = reg->smax_value + off + access_size;
        }

        err = check_stack_slot_within_bounds(env, min_off, state, type);
        if (!err && max_off > 0)
                err = -EINVAL; /* out of stack access into non-negative offsets */
        if (!err && access_size < 0)
                /* access_size should not be negative (or overflow an int); others checks
                 * along the way should have prevented such an access.
                 */
                err = -EFAULT; /* invalid negative access size; integer overflow? */

        if (err) {
                if (tnum_is_const(reg->var_off)) {
                        verbose(env, "invalid%s stack R%d off=%lld size=%d\n",
                                err_extra, regno, min_off, access_size);
                } else {
                        char tn_buf[48];

                        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                        verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n",
                                err_extra, regno, tn_buf, off, access_size);
                }
                return err;
        }

        /* Note that there is no stack access with offset zero, so the needed stack
         * size is -min_off, not -min_off+1.
         */
        return grow_stack_state(env, state, -min_off /* size */);
}

static bool get_func_retval_range(struct bpf_prog *prog,
                                  struct bpf_retval_range *range)
{
        if (prog->type == BPF_PROG_TYPE_LSM &&
                prog->expected_attach_type == BPF_LSM_MAC &&
                !bpf_lsm_get_retval_range(prog, range)) {
                return true;
        }
        return false;
}

static void add_scalar_to_reg(struct bpf_reg_state *dst_reg, s64 val)
{
        struct bpf_reg_state fake_reg;

        if (!val)
                return;

        fake_reg.type = SCALAR_VALUE;
        __mark_reg_known(&fake_reg, val);

        scalar32_min_max_add(dst_reg, &fake_reg);
        scalar_min_max_add(dst_reg, &fake_reg);
        dst_reg->var_off = tnum_add(dst_reg->var_off, fake_reg.var_off);

        reg_bounds_sync(dst_reg);
}

/* check whether memory at (regno + off) is accessible for t = (read | write)
 * if t==write, value_regno is a register which value is stored into memory
 * if t==read, value_regno is a register which will receive the value from memory
 * if t==write && value_regno==-1, some unknown value is stored into memory
 * if t==read && value_regno==-1, don't care what we read from memory
 */
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
                            int off, int bpf_size, enum bpf_access_type t,
                            int value_regno, bool strict_alignment_once, bool is_ldsx)
{
        struct bpf_reg_state *regs = cur_regs(env);
        struct bpf_reg_state *reg = regs + regno;
        int size, err = 0;

        size = bpf_size_to_bytes(bpf_size);
        if (size < 0)
                return size;

        err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
        if (err)
                return err;

        if (reg->type == PTR_TO_MAP_KEY) {
                if (t == BPF_WRITE) {
                        verbose(env, "write to change key R%d not allowed\n", regno);
                        return -EACCES;
                }

                err = check_mem_region_access(env, regno, off, size,
                                              reg->map_ptr->key_size, false);
                if (err)
                        return err;
                if (value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else if (reg->type == PTR_TO_MAP_VALUE) {
                struct btf_field *kptr_field = NULL;

                if (t == BPF_WRITE && value_regno >= 0 &&
                    is_pointer_value(env, value_regno)) {
                        verbose(env, "R%d leaks addr into map\n", value_regno);
                        return -EACCES;
                }
                err = check_map_access_type(env, regno, off, size, t);
                if (err)
                        return err;
                err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT);
                if (err)
                        return err;
                if (tnum_is_const(reg->var_off))
                        kptr_field = btf_record_find(reg->map_ptr->record,
                                                     off + reg->var_off.value, BPF_KPTR | BPF_UPTR);
                if (kptr_field) {
                        err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field);
                } else if (t == BPF_READ && value_regno >= 0) {
                        struct bpf_map *map = reg->map_ptr;

                        /*
                         * If map is read-only, track its contents as scalars,
                         * unless it is an insn array (see the special case below)
                         */
                        if (tnum_is_const(reg->var_off) &&
                            bpf_map_is_rdonly(map) &&
                            map->ops->map_direct_value_addr &&
                            map->map_type != BPF_MAP_TYPE_INSN_ARRAY) {
                                int map_off = off + reg->var_off.value;
                                u64 val = 0;

                                err = bpf_map_direct_read(map, map_off, size,
                                                          &val, is_ldsx);
                                if (err)
                                        return err;

                                regs[value_regno].type = SCALAR_VALUE;
                                __mark_reg_known(&regs[value_regno], val);
                        } else if (map->map_type == BPF_MAP_TYPE_INSN_ARRAY) {
                                if (bpf_size != BPF_DW) {
                                        verbose(env, "Invalid read of %d bytes from insn_array\n",
                                                     size);
                                        return -EACCES;
                                }
                                copy_register_state(&regs[value_regno], reg);
                                add_scalar_to_reg(&regs[value_regno], off);
                                regs[value_regno].type = PTR_TO_INSN;
                        } else {
                                mark_reg_unknown(env, regs, value_regno);
                        }
                }
        } else if (base_type(reg->type) == PTR_TO_MEM) {
                bool rdonly_mem = type_is_rdonly_mem(reg->type);
                bool rdonly_untrusted = rdonly_mem && (reg->type & PTR_UNTRUSTED);

                if (type_may_be_null(reg->type)) {
                        verbose(env, "R%d invalid mem access '%s'\n", regno,
                                reg_type_str(env, reg->type));
                        return -EACCES;
                }

                if (t == BPF_WRITE && rdonly_mem) {
                        verbose(env, "R%d cannot write into %s\n",
                                regno, reg_type_str(env, reg->type));
                        return -EACCES;
                }

                if (t == BPF_WRITE && value_regno >= 0 &&
                    is_pointer_value(env, value_regno)) {
                        verbose(env, "R%d leaks addr into mem\n", value_regno);
                        return -EACCES;
                }

                /*
                 * Accesses to untrusted PTR_TO_MEM are done through probe
                 * instructions, hence no need to check bounds in that case.
                 */
                if (!rdonly_untrusted)
                        err = check_mem_region_access(env, regno, off, size,
                                                      reg->mem_size, false);
                if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
                        mark_reg_unknown(env, regs, value_regno);
        } else if (reg->type == PTR_TO_CTX) {
                struct bpf_insn_access_aux info = {
                        .reg_type = SCALAR_VALUE,
                        .is_ldsx = is_ldsx,
                        .log = &env->log,
                };
                struct bpf_retval_range range;

                if (t == BPF_WRITE && value_regno >= 0 &&
                    is_pointer_value(env, value_regno)) {
                        verbose(env, "R%d leaks addr into ctx\n", value_regno);
                        return -EACCES;
                }

                err = check_ctx_access(env, insn_idx, regno, off, size, t, &info);
                if (!err && t == BPF_READ && value_regno >= 0) {
                        /* ctx access returns either a scalar, or a
                         * PTR_TO_PACKET[_META,_END]. In the latter
                         * case, we know the offset is zero.
                         */
                        if (info.reg_type == SCALAR_VALUE) {
                                if (info.is_retval && get_func_retval_range(env->prog, &range)) {
                                        err = __mark_reg_s32_range(env, regs, value_regno,
                                                                   range.minval, range.maxval);
                                        if (err)
                                                return err;
                                } else {
                                        mark_reg_unknown(env, regs, value_regno);
                                }
                        } else {
                                mark_reg_known_zero(env, regs,
                                                    value_regno);
                                if (type_may_be_null(info.reg_type))
                                        regs[value_regno].id = ++env->id_gen;
                                /* A load of ctx field could have different
                                 * actual load size with the one encoded in the
                                 * insn. When the dst is PTR, it is for sure not
                                 * a sub-register.
                                 */
                                regs[value_regno].subreg_def = DEF_NOT_SUBREG;
                                if (base_type(info.reg_type) == PTR_TO_BTF_ID) {
                                        regs[value_regno].btf = info.btf;
                                        regs[value_regno].btf_id = info.btf_id;
                                        regs[value_regno].ref_obj_id = info.ref_obj_id;
                                }
                        }
                        regs[value_regno].type = info.reg_type;
                }

        } else if (reg->type == PTR_TO_STACK) {
                /* Basic bounds checks. */
                err = check_stack_access_within_bounds(env, regno, off, size, t);
                if (err)
                        return err;

                if (t == BPF_READ)
                        err = check_stack_read(env, regno, off, size,
                                               value_regno);
                else
                        err = check_stack_write(env, regno, off, size,
                                                value_regno, insn_idx);
        } else if (reg_is_pkt_pointer(reg)) {
                if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
                        verbose(env, "cannot write into packet\n");
                        return -EACCES;
                }
                if (t == BPF_WRITE && value_regno >= 0 &&
                    is_pointer_value(env, value_regno)) {
                        verbose(env, "R%d leaks addr into packet\n",
                                value_regno);
                        return -EACCES;
                }
                err = check_packet_access(env, regno, off, size, false);
                if (!err && t == BPF_READ && value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else if (reg->type == PTR_TO_FLOW_KEYS) {
                if (t == BPF_WRITE && value_regno >= 0 &&
                    is_pointer_value(env, value_regno)) {
                        verbose(env, "R%d leaks addr into flow keys\n",
                                value_regno);
                        return -EACCES;
                }

                err = check_flow_keys_access(env, off, size);
                if (!err && t == BPF_READ && value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else if (type_is_sk_pointer(reg->type)) {
                if (t == BPF_WRITE) {
                        verbose(env, "R%d cannot write into %s\n",
                                regno, reg_type_str(env, reg->type));
                        return -EACCES;
                }
                err = check_sock_access(env, insn_idx, regno, off, size, t);
                if (!err && value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else if (reg->type == PTR_TO_TP_BUFFER) {
                err = check_tp_buffer_access(env, reg, regno, off, size);
                if (!err && t == BPF_READ && value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else if (base_type(reg->type) == PTR_TO_BTF_ID &&
                   !type_may_be_null(reg->type)) {
                err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
                                              value_regno);
        } else if (reg->type == CONST_PTR_TO_MAP) {
                err = check_ptr_to_map_access(env, regs, regno, off, size, t,
                                              value_regno);
        } else if (base_type(reg->type) == PTR_TO_BUF &&
                   !type_may_be_null(reg->type)) {
                bool rdonly_mem = type_is_rdonly_mem(reg->type);
                u32 *max_access;

                if (rdonly_mem) {
                        if (t == BPF_WRITE) {
                                verbose(env, "R%d cannot write into %s\n",
                                        regno, reg_type_str(env, reg->type));
                                return -EACCES;
                        }
                        max_access = &env->prog->aux->max_rdonly_access;
                } else {
                        max_access = &env->prog->aux->max_rdwr_access;
                }

                err = check_buffer_access(env, reg, regno, off, size, false,
                                          max_access);

                if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
                        mark_reg_unknown(env, regs, value_regno);
        } else if (reg->type == PTR_TO_ARENA) {
                if (t == BPF_READ && value_regno >= 0)
                        mark_reg_unknown(env, regs, value_regno);
        } else {
                verbose(env, "R%d invalid mem access '%s'\n", regno,
                        reg_type_str(env, reg->type));
                return -EACCES;
        }

        if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
            regs[value_regno].type == SCALAR_VALUE) {
                if (!is_ldsx)
                        /* b/h/w load zero-extends, mark upper bits as known 0 */
                        coerce_reg_to_size(&regs[value_regno], size);
                else
                        coerce_reg_to_size_sx(&regs[value_regno], size);
        }
        return err;
}

static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
                             bool allow_trust_mismatch);

static int check_load_mem(struct bpf_verifier_env *env, struct bpf_insn *insn,
                          bool strict_alignment_once, bool is_ldsx,
                          bool allow_trust_mismatch, const char *ctx)
{
        struct bpf_reg_state *regs = cur_regs(env);
        enum bpf_reg_type src_reg_type;
        int err;

        /* check src operand */
        err = check_reg_arg(env, insn->src_reg, SRC_OP);
        if (err)
                return err;

        /* check dst operand */
        err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
        if (err)
                return err;

        src_reg_type = regs[insn->src_reg].type;

        /* Check if (src_reg + off) is readable. The state of dst_reg will be
         * updated by this call.
         */
        err = check_mem_access(env, env->insn_idx, insn->src_reg, insn->off,
                               BPF_SIZE(insn->code), BPF_READ, insn->dst_reg,
                               strict_alignment_once, is_ldsx);
        err = err ?: save_aux_ptr_type(env, src_reg_type,
                                       allow_trust_mismatch);
        err = err ?: reg_bounds_sanity_check(env, &regs[insn->dst_reg], ctx);

        return err;
}

static int check_store_reg(struct bpf_verifier_env *env, struct bpf_insn *insn,
                           bool strict_alignment_once)
{
        struct bpf_reg_state *regs = cur_regs(env);
        enum bpf_reg_type dst_reg_type;
        int err;

        /* check src1 operand */
        err = check_reg_arg(env, insn->src_reg, SRC_OP);
        if (err)
                return err;

        /* check src2 operand */
        err = check_reg_arg(env, insn->dst_reg, SRC_OP);
        if (err)
                return err;

        dst_reg_type = regs[insn->dst_reg].type;

        /* Check if (dst_reg + off) is writeable. */
        err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off,
                               BPF_SIZE(insn->code), BPF_WRITE, insn->src_reg,
                               strict_alignment_once, false);
        err = err ?: save_aux_ptr_type(env, dst_reg_type, false);

        return err;
}

static int check_atomic_rmw(struct bpf_verifier_env *env,
                            struct bpf_insn *insn)
{
        int load_reg;
        int err;

        if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) {
                verbose(env, "invalid atomic operand size\n");
                return -EINVAL;
        }

        /* check src1 operand */
        err = check_reg_arg(env, insn->src_reg, SRC_OP);
        if (err)
                return err;

        /* check src2 operand */
        err = check_reg_arg(env, insn->dst_reg, SRC_OP);
        if (err)
                return err;

        if (insn->imm == BPF_CMPXCHG) {
                /* Check comparison of R0 with memory location */
                const u32 aux_reg = BPF_REG_0;

                err = check_reg_arg(env, aux_reg, SRC_OP);
                if (err)
                        return err;

                if (is_pointer_value(env, aux_reg)) {
                        verbose(env, "R%d leaks addr into mem\n", aux_reg);
                        return -EACCES;
                }
        }

        if (is_pointer_value(env, insn->src_reg)) {
                verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
                return -EACCES;
        }

        if (!atomic_ptr_type_ok(env, insn->dst_reg, insn)) {
                verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
                        insn->dst_reg,
                        reg_type_str(env, reg_state(env, insn->dst_reg)->type));
                return -EACCES;
        }

        if (insn->imm & BPF_FETCH) {
                if (insn->imm == BPF_CMPXCHG)
                        load_reg = BPF_REG_0;
                else
                        load_reg = insn->src_reg;

                /* check and record load of old value */
                err = check_reg_arg(env, load_reg, DST_OP);
                if (err)
                        return err;
        } else {
                /* This instruction accesses a memory location but doesn't
                 * actually load it into a register.
                 */
                load_reg = -1;
        }

        /* Check whether we can read the memory, with second call for fetch
         * case to simulate the register fill.
         */
        err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off,
                               BPF_SIZE(insn->code), BPF_READ, -1, true, false);
        if (!err && load_reg >= 0)
                err = check_mem_access(env, env->insn_idx, insn->dst_reg,
                                       insn->off, BPF_SIZE(insn->code),
                                       BPF_READ, load_reg, true, false);
        if (err)
                return err;

        if (is_arena_reg(env, insn->dst_reg)) {
                err = save_aux_ptr_type(env, PTR_TO_ARENA, false);
                if (err)
                        return err;
        }
        /* Check whether we can write into the same memory. */
        err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off,
                               BPF_SIZE(insn->code), BPF_WRITE, -1, true, false);
        if (err)
                return err;
        return 0;
}

static int check_atomic_load(struct bpf_verifier_env *env,
                             struct bpf_insn *insn)
{
        int err;

        err = check_load_mem(env, insn, true, false, false, "atomic_load");
        if (err)
                return err;

        if (!atomic_ptr_type_ok(env, insn->src_reg, insn)) {
                verbose(env, "BPF_ATOMIC loads from R%d %s is not allowed\n",
                        insn->src_reg,
                        reg_type_str(env, reg_state(env, insn->src_reg)->type));
                return -EACCES;
        }

        return 0;
}

static int check_atomic_store(struct bpf_verifier_env *env,
                              struct bpf_insn *insn)
{
        int err;

        err = check_store_reg(env, insn, true);
        if (err)
                return err;

        if (!atomic_ptr_type_ok(env, insn->dst_reg, insn)) {
                verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
                        insn->dst_reg,
                        reg_type_str(env, reg_state(env, insn->dst_reg)->type));
                return -EACCES;
        }

        return 0;
}

static int check_atomic(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        switch (insn->imm) {
        case BPF_ADD:
        case BPF_ADD | BPF_FETCH:
        case BPF_AND:
        case BPF_AND | BPF_FETCH:
        case BPF_OR:
        case BPF_OR | BPF_FETCH:
        case BPF_XOR:
        case BPF_XOR | BPF_FETCH:
        case BPF_XCHG:
        case BPF_CMPXCHG:
                return check_atomic_rmw(env, insn);
        case BPF_LOAD_ACQ:
                if (BPF_SIZE(insn->code) == BPF_DW && BITS_PER_LONG != 64) {
                        verbose(env,
                                "64-bit load-acquires are only supported on 64-bit arches\n");
                        return -EOPNOTSUPP;
                }
                return check_atomic_load(env, insn);
        case BPF_STORE_REL:
                if (BPF_SIZE(insn->code) == BPF_DW && BITS_PER_LONG != 64) {
                        verbose(env,
                                "64-bit store-releases are only supported on 64-bit arches\n");
                        return -EOPNOTSUPP;
                }
                return check_atomic_store(env, insn);
        default:
                verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n",
                        insn->imm);
                return -EINVAL;
        }
}

/* When register 'regno' is used to read the stack (either directly or through
 * a helper function) make sure that it's within stack boundary and, depending
 * on the access type and privileges, that all elements of the stack are
 * initialized.
 *
 * All registers that have been spilled on the stack in the slots within the
 * read offsets are marked as read.
 */
static int check_stack_range_initialized(
                struct bpf_verifier_env *env, int regno, int off,
                int access_size, bool zero_size_allowed,
                enum bpf_access_type type, struct bpf_call_arg_meta *meta)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_func_state *state = bpf_func(env, reg);
        int err, min_off, max_off, i, j, slot, spi;
        /* Some accesses can write anything into the stack, others are
         * read-only.
         */
        bool clobber = type == BPF_WRITE;
        /*
         * Negative access_size signals global subprog/kfunc arg check where
         * STACK_POISON slots are acceptable. static stack liveness
         * might have determined that subprog doesn't read them,
         * but BTF based global subprog validation isn't accurate enough.
         */
        bool allow_poison = access_size < 0 || clobber;

        access_size = abs(access_size);

        if (access_size == 0 && !zero_size_allowed) {
                verbose(env, "invalid zero-sized read\n");
                return -EACCES;
        }

        err = check_stack_access_within_bounds(env, regno, off, access_size, type);
        if (err)
                return err;


        if (tnum_is_const(reg->var_off)) {
                min_off = max_off = reg->var_off.value + off;
        } else {
                /* Variable offset is prohibited for unprivileged mode for
                 * simplicity since it requires corresponding support in
                 * Spectre masking for stack ALU.
                 * See also retrieve_ptr_limit().
                 */
                if (!env->bypass_spec_v1) {
                        char tn_buf[48];

                        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                        verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n",
                                regno, tn_buf);
                        return -EACCES;
                }
                /* Only initialized buffer on stack is allowed to be accessed
                 * with variable offset. With uninitialized buffer it's hard to
                 * guarantee that whole memory is marked as initialized on
                 * helper return since specific bounds are unknown what may
                 * cause uninitialized stack leaking.
                 */
                if (meta && meta->raw_mode)
                        meta = NULL;

                min_off = reg->smin_value + off;
                max_off = reg->smax_value + off;
        }

        if (meta && meta->raw_mode) {
                /* Ensure we won't be overwriting dynptrs when simulating byte
                 * by byte access in check_helper_call using meta.access_size.
                 * This would be a problem if we have a helper in the future
                 * which takes:
                 *
                 *      helper(uninit_mem, len, dynptr)
                 *
                 * Now, uninint_mem may overlap with dynptr pointer. Hence, it
                 * may end up writing to dynptr itself when touching memory from
                 * arg 1. This can be relaxed on a case by case basis for known
                 * safe cases, but reject due to the possibilitiy of aliasing by
                 * default.
                 */
                for (i = min_off; i < max_off + access_size; i++) {
                        int stack_off = -i - 1;

                        spi = bpf_get_spi(i);
                        /* raw_mode may write past allocated_stack */
                        if (state->allocated_stack <= stack_off)
                                continue;
                        if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) {
                                verbose(env, "potential write to dynptr at off=%d disallowed\n", i);
                                return -EACCES;
                        }
                }
                meta->access_size = access_size;
                meta->regno = regno;
                return 0;
        }

        for (i = min_off; i < max_off + access_size; i++) {
                u8 *stype;

                slot = -i - 1;
                spi = slot / BPF_REG_SIZE;
                if (state->allocated_stack <= slot) {
                        verbose(env, "allocated_stack too small\n");
                        return -EFAULT;
                }

                stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
                if (*stype == STACK_MISC)
                        goto mark;
                if ((*stype == STACK_ZERO) ||
                    (*stype == STACK_INVALID && env->allow_uninit_stack)) {
                        if (clobber) {
                                /* helper can write anything into the stack */
                                *stype = STACK_MISC;
                        }
                        goto mark;
                }

                if (bpf_is_spilled_reg(&state->stack[spi]) &&
                    (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
                     env->allow_ptr_leaks)) {
                        if (clobber) {
                                __mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
                                for (j = 0; j < BPF_REG_SIZE; j++)
                                        scrub_spilled_slot(&state->stack[spi].slot_type[j]);
                        }
                        goto mark;
                }

                if (*stype == STACK_POISON) {
                        if (allow_poison)
                                goto mark;
                        verbose(env, "reading from stack R%d off %d+%d size %d, slot poisoned by dead code elimination\n",
                                regno, min_off, i - min_off, access_size);
                } else if (tnum_is_const(reg->var_off)) {
                        verbose(env, "invalid read from stack R%d off %d+%d size %d\n",
                                regno, min_off, i - min_off, access_size);
                } else {
                        char tn_buf[48];

                        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                        verbose(env, "invalid read from stack R%d var_off %s+%d size %d\n",
                                regno, tn_buf, i - min_off, access_size);
                }
                return -EACCES;
mark:
                ;
        }
        return 0;
}

static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
                                   int access_size, enum bpf_access_type access_type,
                                   bool zero_size_allowed,
                                   struct bpf_call_arg_meta *meta)
{
        struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
        u32 *max_access;

        switch (base_type(reg->type)) {
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
                return check_packet_access(env, regno, 0, access_size,
                                           zero_size_allowed);
        case PTR_TO_MAP_KEY:
                if (access_type == BPF_WRITE) {
                        verbose(env, "R%d cannot write into %s\n", regno,
                                reg_type_str(env, reg->type));
                        return -EACCES;
                }
                return check_mem_region_access(env, regno, 0, access_size,
                                               reg->map_ptr->key_size, false);
        case PTR_TO_MAP_VALUE:
                if (check_map_access_type(env, regno, 0, access_size, access_type))
                        return -EACCES;
                return check_map_access(env, regno, 0, access_size,
                                        zero_size_allowed, ACCESS_HELPER);
        case PTR_TO_MEM:
                if (type_is_rdonly_mem(reg->type)) {
                        if (access_type == BPF_WRITE) {
                                verbose(env, "R%d cannot write into %s\n", regno,
                                        reg_type_str(env, reg->type));
                                return -EACCES;
                        }
                }
                return check_mem_region_access(env, regno, 0,
                                               access_size, reg->mem_size,
                                               zero_size_allowed);
        case PTR_TO_BUF:
                if (type_is_rdonly_mem(reg->type)) {
                        if (access_type == BPF_WRITE) {
                                verbose(env, "R%d cannot write into %s\n", regno,
                                        reg_type_str(env, reg->type));
                                return -EACCES;
                        }

                        max_access = &env->prog->aux->max_rdonly_access;
                } else {
                        max_access = &env->prog->aux->max_rdwr_access;
                }
                return check_buffer_access(env, reg, regno, 0,
                                           access_size, zero_size_allowed,
                                           max_access);
        case PTR_TO_STACK:
                return check_stack_range_initialized(
                                env,
                                regno, 0, access_size,
                                zero_size_allowed, access_type, meta);
        case PTR_TO_BTF_ID:
                return check_ptr_to_btf_access(env, regs, regno, 0,
                                               access_size, BPF_READ, -1);
        case PTR_TO_CTX:
                /* Only permit reading or writing syscall context using helper calls. */
                if (is_var_ctx_off_allowed(env->prog)) {
                        int err = check_mem_region_access(env, regno, 0, access_size, U16_MAX,
                                                          zero_size_allowed);
                        if (err)
                                return err;
                        if (env->prog->aux->max_ctx_offset < reg->umax_value + access_size)
                                env->prog->aux->max_ctx_offset = reg->umax_value + access_size;
                        return 0;
                }
                fallthrough;
        default: /* scalar_value or invalid ptr */
                /* Allow zero-byte read from NULL, regardless of pointer type */
                if (zero_size_allowed && access_size == 0 &&
                    bpf_register_is_null(reg))
                        return 0;

                verbose(env, "R%d type=%s ", regno,
                        reg_type_str(env, reg->type));
                verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
                return -EACCES;
        }
}

/* verify arguments to helpers or kfuncs consisting of a pointer and an access
 * size.
 *
 * @regno is the register containing the access size. regno-1 is the register
 * containing the pointer.
 */
static int check_mem_size_reg(struct bpf_verifier_env *env,
                              struct bpf_reg_state *reg, u32 regno,
                              enum bpf_access_type access_type,
                              bool zero_size_allowed,
                              struct bpf_call_arg_meta *meta)
{
        int err;

        /* This is used to refine r0 return value bounds for helpers
         * that enforce this value as an upper bound on return values.
         * See do_refine_retval_range() for helpers that can refine
         * the return value. C type of helper is u32 so we pull register
         * bound from umax_value however, if negative verifier errors
         * out. Only upper bounds can be learned because retval is an
         * int type and negative retvals are allowed.
         */
        meta->msize_max_value = reg->umax_value;

        /* The register is SCALAR_VALUE; the access check happens using
         * its boundaries. For unprivileged variable accesses, disable
         * raw mode so that the program is required to initialize all
         * the memory that the helper could just partially fill up.
         */
        if (!tnum_is_const(reg->var_off))
                meta = NULL;

        if (reg->smin_value < 0) {
                verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
                        regno);
                return -EACCES;
        }

        if (reg->umin_value == 0 && !zero_size_allowed) {
                verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n",
                        regno, reg->umin_value, reg->umax_value);
                return -EACCES;
        }

        if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
                verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
                        regno);
                return -EACCES;
        }
        err = check_helper_mem_access(env, regno - 1, reg->umax_value,
                                      access_type, zero_size_allowed, meta);
        if (!err)
                err = mark_chain_precision(env, regno);
        return err;
}

static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                         u32 regno, u32 mem_size)
{
        bool may_be_null = type_may_be_null(reg->type);
        struct bpf_reg_state saved_reg;
        int err;

        if (bpf_register_is_null(reg))
                return 0;

        /* Assuming that the register contains a value check if the memory
         * access is safe. Temporarily save and restore the register's state as
         * the conversion shouldn't be visible to a caller.
         */
        if (may_be_null) {
                saved_reg = *reg;
                mark_ptr_not_null_reg(reg);
        }

        int size = base_type(reg->type) == PTR_TO_STACK ? -(int)mem_size : mem_size;

        err = check_helper_mem_access(env, regno, size, BPF_READ, true, NULL);
        err = err ?: check_helper_mem_access(env, regno, size, BPF_WRITE, true, NULL);

        if (may_be_null)
                *reg = saved_reg;

        return err;
}

static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                    u32 regno)
{
        struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1];
        bool may_be_null = type_may_be_null(mem_reg->type);
        struct bpf_reg_state saved_reg;
        struct bpf_call_arg_meta meta;
        int err;

        WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5);

        memset(&meta, 0, sizeof(meta));

        if (may_be_null) {
                saved_reg = *mem_reg;
                mark_ptr_not_null_reg(mem_reg);
        }

        err = check_mem_size_reg(env, reg, regno, BPF_READ, true, &meta);
        err = err ?: check_mem_size_reg(env, reg, regno, BPF_WRITE, true, &meta);

        if (may_be_null)
                *mem_reg = saved_reg;

        return err;
}

enum {
        PROCESS_SPIN_LOCK = (1 << 0),
        PROCESS_RES_LOCK  = (1 << 1),
        PROCESS_LOCK_IRQ  = (1 << 2),
};

/* Implementation details:
 * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL.
 * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL.
 * Two bpf_map_lookups (even with the same key) will have different reg->id.
 * Two separate bpf_obj_new will also have different reg->id.
 * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier
 * clears reg->id after value_or_null->value transition, since the verifier only
 * cares about the range of access to valid map value pointer and doesn't care
 * about actual address of the map element.
 * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
 * reg->id > 0 after value_or_null->value transition. By doing so
 * two bpf_map_lookups will be considered two different pointers that
 * point to different bpf_spin_locks. Likewise for pointers to allocated objects
 * returned from bpf_obj_new.
 * The verifier allows taking only one bpf_spin_lock at a time to avoid
 * dead-locks.
 * Since only one bpf_spin_lock is allowed the checks are simpler than
 * reg_is_refcounted() logic. The verifier needs to remember only
 * one spin_lock instead of array of acquired_refs.
 * env->cur_state->active_locks remembers which map value element or allocated
 * object got locked and clears it after bpf_spin_unlock.
 */
static int process_spin_lock(struct bpf_verifier_env *env, int regno, int flags)
{
        bool is_lock = flags & PROCESS_SPIN_LOCK, is_res_lock = flags & PROCESS_RES_LOCK;
        const char *lock_str = is_res_lock ? "bpf_res_spin" : "bpf_spin";
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_verifier_state *cur = env->cur_state;
        bool is_const = tnum_is_const(reg->var_off);
        bool is_irq = flags & PROCESS_LOCK_IRQ;
        u64 val = reg->var_off.value;
        struct bpf_map *map = NULL;
        struct btf *btf = NULL;
        struct btf_record *rec;
        u32 spin_lock_off;
        int err;

        if (!is_const) {
                verbose(env,
                        "R%d doesn't have constant offset. %s_lock has to be at the constant offset\n",
                        regno, lock_str);
                return -EINVAL;
        }
        if (reg->type == PTR_TO_MAP_VALUE) {
                map = reg->map_ptr;
                if (!map->btf) {
                        verbose(env,
                                "map '%s' has to have BTF in order to use %s_lock\n",
                                map->name, lock_str);
                        return -EINVAL;
                }
        } else {
                btf = reg->btf;
        }

        rec = reg_btf_record(reg);
        if (!btf_record_has_field(rec, is_res_lock ? BPF_RES_SPIN_LOCK : BPF_SPIN_LOCK)) {
                verbose(env, "%s '%s' has no valid %s_lock\n", map ? "map" : "local",
                        map ? map->name : "kptr", lock_str);
                return -EINVAL;
        }
        spin_lock_off = is_res_lock ? rec->res_spin_lock_off : rec->spin_lock_off;
        if (spin_lock_off != val) {
                verbose(env, "off %lld doesn't point to 'struct %s_lock' that is at %d\n",
                        val, lock_str, spin_lock_off);
                return -EINVAL;
        }
        if (is_lock) {
                void *ptr;
                int type;

                if (map)
                        ptr = map;
                else
                        ptr = btf;

                if (!is_res_lock && cur->active_locks) {
                        if (find_lock_state(env->cur_state, REF_TYPE_LOCK, 0, NULL)) {
                                verbose(env,
                                        "Locking two bpf_spin_locks are not allowed\n");
                                return -EINVAL;
                        }
                } else if (is_res_lock && cur->active_locks) {
                        if (find_lock_state(env->cur_state, REF_TYPE_RES_LOCK | REF_TYPE_RES_LOCK_IRQ, reg->id, ptr)) {
                                verbose(env, "Acquiring the same lock again, AA deadlock detected\n");
                                return -EINVAL;
                        }
                }

                if (is_res_lock && is_irq)
                        type = REF_TYPE_RES_LOCK_IRQ;
                else if (is_res_lock)
                        type = REF_TYPE_RES_LOCK;
                else
                        type = REF_TYPE_LOCK;
                err = acquire_lock_state(env, env->insn_idx, type, reg->id, ptr);
                if (err < 0) {
                        verbose(env, "Failed to acquire lock state\n");
                        return err;
                }
        } else {
                void *ptr;
                int type;

                if (map)
                        ptr = map;
                else
                        ptr = btf;

                if (!cur->active_locks) {
                        verbose(env, "%s_unlock without taking a lock\n", lock_str);
                        return -EINVAL;
                }

                if (is_res_lock && is_irq)
                        type = REF_TYPE_RES_LOCK_IRQ;
                else if (is_res_lock)
                        type = REF_TYPE_RES_LOCK;
                else
                        type = REF_TYPE_LOCK;
                if (!find_lock_state(cur, type, reg->id, ptr)) {
                        verbose(env, "%s_unlock of different lock\n", lock_str);
                        return -EINVAL;
                }
                if (reg->id != cur->active_lock_id || ptr != cur->active_lock_ptr) {
                        verbose(env, "%s_unlock cannot be out of order\n", lock_str);
                        return -EINVAL;
                }
                if (release_lock_state(cur, type, reg->id, ptr)) {
                        verbose(env, "%s_unlock of different lock\n", lock_str);
                        return -EINVAL;
                }

                invalidate_non_owning_refs(env);
        }
        return 0;
}

/* Check if @regno is a pointer to a specific field in a map value */
static int check_map_field_pointer(struct bpf_verifier_env *env, u32 regno,
                                   enum btf_field_type field_type,
                                   struct bpf_map_desc *map_desc)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        bool is_const = tnum_is_const(reg->var_off);
        struct bpf_map *map = reg->map_ptr;
        u64 val = reg->var_off.value;
        const char *struct_name = btf_field_type_name(field_type);
        int field_off = -1;

        if (!is_const) {
                verbose(env,
                        "R%d doesn't have constant offset. %s has to be at the constant offset\n",
                        regno, struct_name);
                return -EINVAL;
        }
        if (!map->btf) {
                verbose(env, "map '%s' has to have BTF in order to use %s\n", map->name,
                        struct_name);
                return -EINVAL;
        }
        if (!btf_record_has_field(map->record, field_type)) {
                verbose(env, "map '%s' has no valid %s\n", map->name, struct_name);
                return -EINVAL;
        }
        switch (field_type) {
        case BPF_TIMER:
                field_off = map->record->timer_off;
                break;
        case BPF_TASK_WORK:
                field_off = map->record->task_work_off;
                break;
        case BPF_WORKQUEUE:
                field_off = map->record->wq_off;
                break;
        default:
                verifier_bug(env, "unsupported BTF field type: %s\n", struct_name);
                return -EINVAL;
        }
        if (field_off != val) {
                verbose(env, "off %lld doesn't point to 'struct %s' that is at %d\n",
                        val, struct_name, field_off);
                return -EINVAL;
        }
        if (map_desc->ptr) {
                verifier_bug(env, "Two map pointers in a %s helper", struct_name);
                return -EFAULT;
        }
        map_desc->uid = reg->map_uid;
        map_desc->ptr = map;
        return 0;
}

static int process_timer_func(struct bpf_verifier_env *env, int regno,
                              struct bpf_map_desc *map)
{
        if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
                verbose(env, "bpf_timer cannot be used for PREEMPT_RT.\n");
                return -EOPNOTSUPP;
        }
        return check_map_field_pointer(env, regno, BPF_TIMER, map);
}

static int process_timer_helper(struct bpf_verifier_env *env, int regno,
                                struct bpf_call_arg_meta *meta)
{
        return process_timer_func(env, regno, &meta->map);
}

static int process_timer_kfunc(struct bpf_verifier_env *env, int regno,
                               struct bpf_kfunc_call_arg_meta *meta)
{
        return process_timer_func(env, regno, &meta->map);
}

static int process_kptr_func(struct bpf_verifier_env *env, int regno,
                             struct bpf_call_arg_meta *meta)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct btf_field *kptr_field;
        struct bpf_map *map_ptr;
        struct btf_record *rec;
        u32 kptr_off;

        if (type_is_ptr_alloc_obj(reg->type)) {
                rec = reg_btf_record(reg);
        } else { /* PTR_TO_MAP_VALUE */
                map_ptr = reg->map_ptr;
                if (!map_ptr->btf) {
                        verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n",
                                map_ptr->name);
                        return -EINVAL;
                }
                rec = map_ptr->record;
                meta->map.ptr = map_ptr;
        }

        if (!tnum_is_const(reg->var_off)) {
                verbose(env,
                        "R%d doesn't have constant offset. kptr has to be at the constant offset\n",
                        regno);
                return -EINVAL;
        }

        if (!btf_record_has_field(rec, BPF_KPTR)) {
                verbose(env, "R%d has no valid kptr\n", regno);
                return -EINVAL;
        }

        kptr_off = reg->var_off.value;
        kptr_field = btf_record_find(rec, kptr_off, BPF_KPTR);
        if (!kptr_field) {
                verbose(env, "off=%d doesn't point to kptr\n", kptr_off);
                return -EACCES;
        }
        if (kptr_field->type != BPF_KPTR_REF && kptr_field->type != BPF_KPTR_PERCPU) {
                verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off);
                return -EACCES;
        }
        meta->kptr_field = kptr_field;
        return 0;
}

/* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK
 * which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR.
 *
 * In both cases we deal with the first 8 bytes, but need to mark the next 8
 * bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of
 * CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object.
 *
 * Mutability of bpf_dynptr is at two levels, one is at the level of struct
 * bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct
 * bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can
 * mutate the view of the dynptr and also possibly destroy it. In the latter
 * case, it cannot mutate the bpf_dynptr itself but it can still mutate the
 * memory that dynptr points to.
 *
 * The verifier will keep track both levels of mutation (bpf_dynptr's in
 * reg->type and the memory's in reg->dynptr.type), but there is no support for
 * readonly dynptr view yet, hence only the first case is tracked and checked.
 *
 * This is consistent with how C applies the const modifier to a struct object,
 * where the pointer itself inside bpf_dynptr becomes const but not what it
 * points to.
 *
 * Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument
 * type, and declare it as 'const struct bpf_dynptr *' in their prototype.
 */
static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
                               enum bpf_arg_type arg_type, int clone_ref_obj_id)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        int err;

        if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
                verbose(env,
                        "arg#%d expected pointer to stack or const struct bpf_dynptr\n",
                        regno - 1);
                return -EINVAL;
        }

        /* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an
         * ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*):
         */
        if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) {
                verifier_bug(env, "misconfigured dynptr helper type flags");
                return -EFAULT;
        }

        /*  MEM_UNINIT - Points to memory that is an appropriate candidate for
         *               constructing a mutable bpf_dynptr object.
         *
         *               Currently, this is only possible with PTR_TO_STACK
         *               pointing to a region of at least 16 bytes which doesn't
         *               contain an existing bpf_dynptr.
         *
         *  MEM_RDONLY - Points to a initialized bpf_dynptr that will not be
         *               mutated or destroyed. However, the memory it points to
         *               may be mutated.
         *
         *  None       - Points to a initialized dynptr that can be mutated and
         *               destroyed, including mutation of the memory it points
         *               to.
         */
        if (arg_type & MEM_UNINIT) {
                int i;

                if (!is_dynptr_reg_valid_uninit(env, reg)) {
                        verbose(env, "Dynptr has to be an uninitialized dynptr\n");
                        return -EINVAL;
                }

                /* we write BPF_DW bits (8 bytes) at a time */
                for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) {
                        err = check_mem_access(env, insn_idx, regno,
                                               i, BPF_DW, BPF_WRITE, -1, false, false);
                        if (err)
                                return err;
                }

                err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id);
        } else /* MEM_RDONLY and None case from above */ {
                /* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */
                if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) {
                        verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n");
                        return -EINVAL;
                }

                if (!is_dynptr_reg_valid_init(env, reg)) {
                        verbose(env,
                                "Expected an initialized dynptr as arg #%d\n",
                                regno - 1);
                        return -EINVAL;
                }

                /* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */
                if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) {
                        verbose(env,
                                "Expected a dynptr of type %s as arg #%d\n",
                                dynptr_type_str(arg_to_dynptr_type(arg_type)), regno - 1);
                        return -EINVAL;
                }

                err = mark_dynptr_read(env, reg);
        }
        return err;
}

static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi)
{
        struct bpf_func_state *state = bpf_func(env, reg);

        return state->stack[spi].spilled_ptr.ref_obj_id;
}

static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
}

static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_ITER_NEW;
}


static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_ITER_DESTROY;
}

static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx,
                              const struct btf_param *arg)
{
        /* btf_check_iter_kfuncs() guarantees that first argument of any iter
         * kfunc is iter state pointer
         */
        if (is_iter_kfunc(meta))
                return arg_idx == 0;

        /* iter passed as an argument to a generic kfunc */
        return btf_param_match_suffix(meta->btf, arg, "__iter");
}

static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx,
                            struct bpf_kfunc_call_arg_meta *meta)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        const struct btf_type *t;
        int spi, err, i, nr_slots, btf_id;

        if (reg->type != PTR_TO_STACK) {
                verbose(env, "arg#%d expected pointer to an iterator on stack\n", regno - 1);
                return -EINVAL;
        }

        /* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs()
         * ensures struct convention, so we wouldn't need to do any BTF
         * validation here. But given iter state can be passed as a parameter
         * to any kfunc, if arg has "__iter" suffix, we need to be a bit more
         * conservative here.
         */
        btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1);
        if (btf_id < 0) {
                verbose(env, "expected valid iter pointer as arg #%d\n", regno - 1);
                return -EINVAL;
        }
        t = btf_type_by_id(meta->btf, btf_id);
        nr_slots = t->size / BPF_REG_SIZE;

        if (is_iter_new_kfunc(meta)) {
                /* bpf_iter_<type>_new() expects pointer to uninit iter state */
                if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) {
                        verbose(env, "expected uninitialized iter_%s as arg #%d\n",
                                iter_type_str(meta->btf, btf_id), regno - 1);
                        return -EINVAL;
                }

                for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) {
                        err = check_mem_access(env, insn_idx, regno,
                                               i, BPF_DW, BPF_WRITE, -1, false, false);
                        if (err)
                                return err;
                }

                err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots);
                if (err)
                        return err;
        } else {
                /* iter_next() or iter_destroy(), as well as any kfunc
                 * accepting iter argument, expect initialized iter state
                 */
                err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
                switch (err) {
                case 0:
                        break;
                case -EINVAL:
                        verbose(env, "expected an initialized iter_%s as arg #%d\n",
                                iter_type_str(meta->btf, btf_id), regno - 1);
                        return err;
                case -EPROTO:
                        verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
                        return err;
                default:
                        return err;
                }

                spi = iter_get_spi(env, reg, nr_slots);
                if (spi < 0)
                        return spi;

                err = mark_iter_read(env, reg, spi, nr_slots);
                if (err)
                        return err;

                /* remember meta->iter info for process_iter_next_call() */
                meta->iter.spi = spi;
                meta->iter.frameno = reg->frameno;
                meta->ref_obj_id = iter_ref_obj_id(env, reg, spi);

                if (is_iter_destroy_kfunc(meta)) {
                        err = unmark_stack_slots_iter(env, reg, nr_slots);
                        if (err)
                                return err;
                }
        }

        return 0;
}

/* Look for a previous loop entry at insn_idx: nearest parent state
 * stopped at insn_idx with callsites matching those in cur->frame.
 */
static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env,
                                                  struct bpf_verifier_state *cur,
                                                  int insn_idx)
{
        struct bpf_verifier_state_list *sl;
        struct bpf_verifier_state *st;
        struct list_head *pos, *head;

        /* Explored states are pushed in stack order, most recent states come first */
        head = bpf_explored_state(env, insn_idx);
        list_for_each(pos, head) {
                sl = container_of(pos, struct bpf_verifier_state_list, node);
                /* If st->branches != 0 state is a part of current DFS verification path,
                 * hence cur & st for a loop.
                 */
                st = &sl->state;
                if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) &&
                    st->dfs_depth < cur->dfs_depth)
                        return st;
        }

        return NULL;
}

/*
 * Check if scalar registers are exact for the purpose of not widening.
 * More lenient than regs_exact()
 */
static bool scalars_exact_for_widen(const struct bpf_reg_state *rold,
                                    const struct bpf_reg_state *rcur)
{
        return !memcmp(rold, rcur, offsetof(struct bpf_reg_state, id));
}

static void maybe_widen_reg(struct bpf_verifier_env *env,
                            struct bpf_reg_state *rold, struct bpf_reg_state *rcur)
{
        if (rold->type != SCALAR_VALUE)
                return;
        if (rold->type != rcur->type)
                return;
        if (rold->precise || rcur->precise || scalars_exact_for_widen(rold, rcur))
                return;
        __mark_reg_unknown(env, rcur);
}

static int widen_imprecise_scalars(struct bpf_verifier_env *env,
                                   struct bpf_verifier_state *old,
                                   struct bpf_verifier_state *cur)
{
        struct bpf_func_state *fold, *fcur;
        int i, fr, num_slots;

        for (fr = old->curframe; fr >= 0; fr--) {
                fold = old->frame[fr];
                fcur = cur->frame[fr];

                for (i = 0; i < MAX_BPF_REG; i++)
                        maybe_widen_reg(env,
                                        &fold->regs[i],
                                        &fcur->regs[i]);

                num_slots = min(fold->allocated_stack / BPF_REG_SIZE,
                                fcur->allocated_stack / BPF_REG_SIZE);
                for (i = 0; i < num_slots; i++) {
                        if (!bpf_is_spilled_reg(&fold->stack[i]) ||
                            !bpf_is_spilled_reg(&fcur->stack[i]))
                                continue;

                        maybe_widen_reg(env,
                                        &fold->stack[i].spilled_ptr,
                                        &fcur->stack[i].spilled_ptr);
                }
        }
        return 0;
}

static struct bpf_reg_state *get_iter_from_state(struct bpf_verifier_state *cur_st,
                                                 struct bpf_kfunc_call_arg_meta *meta)
{
        int iter_frameno = meta->iter.frameno;
        int iter_spi = meta->iter.spi;

        return &cur_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr;
}

/* process_iter_next_call() is called when verifier gets to iterator's next
 * "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer
 * to it as just "iter_next()" in comments below.
 *
 * BPF verifier relies on a crucial contract for any iter_next()
 * implementation: it should *eventually* return NULL, and once that happens
 * it should keep returning NULL. That is, once iterator exhausts elements to
 * iterate, it should never reset or spuriously return new elements.
 *
 * With the assumption of such contract, process_iter_next_call() simulates
 * a fork in the verifier state to validate loop logic correctness and safety
 * without having to simulate infinite amount of iterations.
 *
 * In current state, we first assume that iter_next() returned NULL and
 * iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such
 * conditions we should not form an infinite loop and should eventually reach
 * exit.
 *
 * Besides that, we also fork current state and enqueue it for later
 * verification. In a forked state we keep iterator state as ACTIVE
 * (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We
 * also bump iteration depth to prevent erroneous infinite loop detection
 * later on (see iter_active_depths_differ() comment for details). In this
 * state we assume that we'll eventually loop back to another iter_next()
 * calls (it could be in exactly same location or in some other instruction,
 * it doesn't matter, we don't make any unnecessary assumptions about this,
 * everything revolves around iterator state in a stack slot, not which
 * instruction is calling iter_next()). When that happens, we either will come
 * to iter_next() with equivalent state and can conclude that next iteration
 * will proceed in exactly the same way as we just verified, so it's safe to
 * assume that loop converges. If not, we'll go on another iteration
 * simulation with a different input state, until all possible starting states
 * are validated or we reach maximum number of instructions limit.
 *
 * This way, we will either exhaustively discover all possible input states
 * that iterator loop can start with and eventually will converge, or we'll
 * effectively regress into bounded loop simulation logic and either reach
 * maximum number of instructions if loop is not provably convergent, or there
 * is some statically known limit on number of iterations (e.g., if there is
 * an explicit `if n > 100 then break;` statement somewhere in the loop).
 *
 * Iteration convergence logic in is_state_visited() relies on exact
 * states comparison, which ignores read and precision marks.
 * This is necessary because read and precision marks are not finalized
 * while in the loop. Exact comparison might preclude convergence for
 * simple programs like below:
 *
 *     i = 0;
 *     while(iter_next(&it))
 *       i++;
 *
 * At each iteration step i++ would produce a new distinct state and
 * eventually instruction processing limit would be reached.
 *
 * To avoid such behavior speculatively forget (widen) range for
 * imprecise scalar registers, if those registers were not precise at the
 * end of the previous iteration and do not match exactly.
 *
 * This is a conservative heuristic that allows to verify wide range of programs,
 * however it precludes verification of programs that conjure an
 * imprecise value on the first loop iteration and use it as precise on a second.
 * For example, the following safe program would fail to verify:
 *
 *     struct bpf_num_iter it;
 *     int arr[10];
 *     int i = 0, a = 0;
 *     bpf_iter_num_new(&it, 0, 10);
 *     while (bpf_iter_num_next(&it)) {
 *       if (a == 0) {
 *         a = 1;
 *         i = 7; // Because i changed verifier would forget
 *                // it's range on second loop entry.
 *       } else {
 *         arr[i] = 42; // This would fail to verify.
 *       }
 *     }
 *     bpf_iter_num_destroy(&it);
 */
static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx,
                                  struct bpf_kfunc_call_arg_meta *meta)
{
        struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
        struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr;
        struct bpf_reg_state *cur_iter, *queued_iter;

        BTF_TYPE_EMIT(struct bpf_iter);

        cur_iter = get_iter_from_state(cur_st, meta);

        if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE &&
            cur_iter->iter.state != BPF_ITER_STATE_DRAINED) {
                verifier_bug(env, "unexpected iterator state %d (%s)",
                             cur_iter->iter.state, iter_state_str(cur_iter->iter.state));
                return -EFAULT;
        }

        if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) {
                /* Because iter_next() call is a checkpoint is_state_visitied()
                 * should guarantee parent state with same call sites and insn_idx.
                 */
                if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx ||
                    !same_callsites(cur_st->parent, cur_st)) {
                        verifier_bug(env, "bad parent state for iter next call");
                        return -EFAULT;
                }
                /* Note cur_st->parent in the call below, it is necessary to skip
                 * checkpoint created for cur_st by is_state_visited()
                 * right at this instruction.
                 */
                prev_st = find_prev_entry(env, cur_st->parent, insn_idx);
                /* branch out active iter state */
                queued_st = push_stack(env, insn_idx + 1, insn_idx, false);
                if (IS_ERR(queued_st))
                        return PTR_ERR(queued_st);

                queued_iter = get_iter_from_state(queued_st, meta);
                queued_iter->iter.state = BPF_ITER_STATE_ACTIVE;
                queued_iter->iter.depth++;
                if (prev_st)
                        widen_imprecise_scalars(env, prev_st, queued_st);

                queued_fr = queued_st->frame[queued_st->curframe];
                mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]);
        }

        /* switch to DRAINED state, but keep the depth unchanged */
        /* mark current iter state as drained and assume returned NULL */
        cur_iter->iter.state = BPF_ITER_STATE_DRAINED;
        __mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]);

        return 0;
}

static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
        return type == ARG_CONST_SIZE ||
               type == ARG_CONST_SIZE_OR_ZERO;
}

static bool arg_type_is_raw_mem(enum bpf_arg_type type)
{
        return base_type(type) == ARG_PTR_TO_MEM &&
               type & MEM_UNINIT;
}

static bool arg_type_is_release(enum bpf_arg_type type)
{
        return type & OBJ_RELEASE;
}

static bool arg_type_is_dynptr(enum bpf_arg_type type)
{
        return base_type(type) == ARG_PTR_TO_DYNPTR;
}

static int resolve_map_arg_type(struct bpf_verifier_env *env,
                                 const struct bpf_call_arg_meta *meta,
                                 enum bpf_arg_type *arg_type)
{
        if (!meta->map.ptr) {
                /* kernel subsystem misconfigured verifier */
                verifier_bug(env, "invalid map_ptr to access map->type");
                return -EFAULT;
        }

        switch (meta->map.ptr->map_type) {
        case BPF_MAP_TYPE_SOCKMAP:
        case BPF_MAP_TYPE_SOCKHASH:
                if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
                        *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
                } else {
                        verbose(env, "invalid arg_type for sockmap/sockhash\n");
                        return -EINVAL;
                }
                break;
        case BPF_MAP_TYPE_BLOOM_FILTER:
                if (meta->func_id == BPF_FUNC_map_peek_elem)
                        *arg_type = ARG_PTR_TO_MAP_VALUE;
                break;
        default:
                break;
        }
        return 0;
}

struct bpf_reg_types {
        const enum bpf_reg_type types[10];
        u32 *btf_id;
};

static const struct bpf_reg_types sock_types = {
        .types = {
                PTR_TO_SOCK_COMMON,
                PTR_TO_SOCKET,
                PTR_TO_TCP_SOCK,
                PTR_TO_XDP_SOCK,
        },
};

#ifdef CONFIG_NET
static const struct bpf_reg_types btf_id_sock_common_types = {
        .types = {
                PTR_TO_SOCK_COMMON,
                PTR_TO_SOCKET,
                PTR_TO_TCP_SOCK,
                PTR_TO_XDP_SOCK,
                PTR_TO_BTF_ID,
                PTR_TO_BTF_ID | PTR_TRUSTED,
        },
        .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
};
#endif

static const struct bpf_reg_types mem_types = {
        .types = {
                PTR_TO_STACK,
                PTR_TO_PACKET,
                PTR_TO_PACKET_META,
                PTR_TO_MAP_KEY,
                PTR_TO_MAP_VALUE,
                PTR_TO_MEM,
                PTR_TO_MEM | MEM_RINGBUF,
                PTR_TO_BUF,
                PTR_TO_BTF_ID | PTR_TRUSTED,
                PTR_TO_CTX,
        },
};

static const struct bpf_reg_types spin_lock_types = {
        .types = {
                PTR_TO_MAP_VALUE,
                PTR_TO_BTF_ID | MEM_ALLOC,
        }
};

static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } };
static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
static const struct bpf_reg_types btf_ptr_types = {
        .types = {
                PTR_TO_BTF_ID,
                PTR_TO_BTF_ID | PTR_TRUSTED,
                PTR_TO_BTF_ID | MEM_RCU,
        },
};
static const struct bpf_reg_types percpu_btf_ptr_types = {
        .types = {
                PTR_TO_BTF_ID | MEM_PERCPU,
                PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU,
                PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED,
        }
};
static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types kptr_xchg_dest_types = {
        .types = {
                PTR_TO_MAP_VALUE,
                PTR_TO_BTF_ID | MEM_ALLOC,
                PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF,
                PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU,
        }
};
static const struct bpf_reg_types dynptr_types = {
        .types = {
                PTR_TO_STACK,
                CONST_PTR_TO_DYNPTR,
        }
};

static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
        [ARG_PTR_TO_MAP_KEY]            = &mem_types,
        [ARG_PTR_TO_MAP_VALUE]          = &mem_types,
        [ARG_CONST_SIZE]                = &scalar_types,
        [ARG_CONST_SIZE_OR_ZERO]        = &scalar_types,
        [ARG_CONST_ALLOC_SIZE_OR_ZERO]  = &scalar_types,
        [ARG_CONST_MAP_PTR]             = &const_map_ptr_types,
        [ARG_PTR_TO_CTX]                = &context_types,
        [ARG_PTR_TO_SOCK_COMMON]        = &sock_types,
#ifdef CONFIG_NET
        [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types,
#endif
        [ARG_PTR_TO_SOCKET]             = &fullsock_types,
        [ARG_PTR_TO_BTF_ID]             = &btf_ptr_types,
        [ARG_PTR_TO_SPIN_LOCK]          = &spin_lock_types,
        [ARG_PTR_TO_MEM]                = &mem_types,
        [ARG_PTR_TO_RINGBUF_MEM]        = &ringbuf_mem_types,
        [ARG_PTR_TO_PERCPU_BTF_ID]      = &percpu_btf_ptr_types,
        [ARG_PTR_TO_FUNC]               = &func_ptr_types,
        [ARG_PTR_TO_STACK]              = &stack_ptr_types,
        [ARG_PTR_TO_CONST_STR]          = &const_str_ptr_types,
        [ARG_PTR_TO_TIMER]              = &timer_types,
        [ARG_KPTR_XCHG_DEST]            = &kptr_xchg_dest_types,
        [ARG_PTR_TO_DYNPTR]             = &dynptr_types,
};

static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
                          enum bpf_arg_type arg_type,
                          const u32 *arg_btf_id,
                          struct bpf_call_arg_meta *meta)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        enum bpf_reg_type expected, type = reg->type;
        const struct bpf_reg_types *compatible;
        int i, j, err;

        compatible = compatible_reg_types[base_type(arg_type)];
        if (!compatible) {
                verifier_bug(env, "unsupported arg type %d", arg_type);
                return -EFAULT;
        }

        /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
         * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
         *
         * Same for MAYBE_NULL:
         *
         * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
         * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
         *
         * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type.
         *
         * Therefore we fold these flags depending on the arg_type before comparison.
         */
        if (arg_type & MEM_RDONLY)
                type &= ~MEM_RDONLY;
        if (arg_type & PTR_MAYBE_NULL)
                type &= ~PTR_MAYBE_NULL;
        if (base_type(arg_type) == ARG_PTR_TO_MEM)
                type &= ~DYNPTR_TYPE_FLAG_MASK;

        /* Local kptr types are allowed as the source argument of bpf_kptr_xchg */
        if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type) && regno == BPF_REG_2) {
                type &= ~MEM_ALLOC;
                type &= ~MEM_PERCPU;
        }

        for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
                expected = compatible->types[i];
                if (expected == NOT_INIT)
                        break;

                if (type == expected)
                        goto found;
        }

        verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
        for (j = 0; j + 1 < i; j++)
                verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
        verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
        return -EACCES;

found:
        if (base_type(reg->type) != PTR_TO_BTF_ID)
                return 0;

        if (compatible == &mem_types) {
                if (!(arg_type & MEM_RDONLY)) {
                        verbose(env,
                                "%s() may write into memory pointed by R%d type=%s\n",
                                func_id_name(meta->func_id),
                                regno, reg_type_str(env, reg->type));
                        return -EACCES;
                }
                return 0;
        }

        switch ((int)reg->type) {
        case PTR_TO_BTF_ID:
        case PTR_TO_BTF_ID | PTR_TRUSTED:
        case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL:
        case PTR_TO_BTF_ID | MEM_RCU:
        case PTR_TO_BTF_ID | PTR_MAYBE_NULL:
        case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU:
        {
                /* For bpf_sk_release, it needs to match against first member
                 * 'struct sock_common', hence make an exception for it. This
                 * allows bpf_sk_release to work for multiple socket types.
                 */
                bool strict_type_match = arg_type_is_release(arg_type) &&
                                         meta->func_id != BPF_FUNC_sk_release;

                if (type_may_be_null(reg->type) &&
                    (!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) {
                        verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno);
                        return -EACCES;
                }

                if (!arg_btf_id) {
                        if (!compatible->btf_id) {
                                verifier_bug(env, "missing arg compatible BTF ID");
                                return -EFAULT;
                        }
                        arg_btf_id = compatible->btf_id;
                }

                if (meta->func_id == BPF_FUNC_kptr_xchg) {
                        if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
                                return -EACCES;
                } else {
                        if (arg_btf_id == BPF_PTR_POISON) {
                                verbose(env, "verifier internal error:");
                                verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n",
                                        regno);
                                return -EACCES;
                        }

                        err = __check_ptr_off_reg(env, reg, regno, true);
                        if (err)
                                return err;

                        if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id,
                                                  reg->var_off.value, btf_vmlinux, *arg_btf_id,
                                                  strict_type_match)) {
                                verbose(env, "R%d is of type %s but %s is expected\n",
                                        regno, btf_type_name(reg->btf, reg->btf_id),
                                        btf_type_name(btf_vmlinux, *arg_btf_id));
                                return -EACCES;
                        }
                }
                break;
        }
        case PTR_TO_BTF_ID | MEM_ALLOC:
        case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
        case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
        case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
                if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
                    meta->func_id != BPF_FUNC_kptr_xchg) {
                        verifier_bug(env, "unimplemented handling of MEM_ALLOC");
                        return -EFAULT;
                }
                /* Check if local kptr in src arg matches kptr in dst arg */
                if (meta->func_id == BPF_FUNC_kptr_xchg && regno == BPF_REG_2) {
                        if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
                                return -EACCES;
                }
                break;
        case PTR_TO_BTF_ID | MEM_PERCPU:
        case PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU:
        case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED:
                /* Handled by helper specific checks */
                break;
        default:
                verifier_bug(env, "invalid PTR_TO_BTF_ID register for type match");
                return -EFAULT;
        }
        return 0;
}

static struct btf_field *
reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields)
{
        struct btf_field *field;
        struct btf_record *rec;

        rec = reg_btf_record(reg);
        if (!rec)
                return NULL;

        field = btf_record_find(rec, off, fields);
        if (!field)
                return NULL;

        return field;
}

static int check_func_arg_reg_off(struct bpf_verifier_env *env,
                                  const struct bpf_reg_state *reg, int regno,
                                  enum bpf_arg_type arg_type)
{
        u32 type = reg->type;

        /* When referenced register is passed to release function, its fixed
         * offset must be 0.
         *
         * We will check arg_type_is_release reg has ref_obj_id when storing
         * meta->release_regno.
         */
        if (arg_type_is_release(arg_type)) {
                /* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it
                 * may not directly point to the object being released, but to
                 * dynptr pointing to such object, which might be at some offset
                 * on the stack. In that case, we simply to fallback to the
                 * default handling.
                 */
                if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK)
                        return 0;

                /* Doing check_ptr_off_reg check for the offset will catch this
                 * because fixed_off_ok is false, but checking here allows us
                 * to give the user a better error message.
                 */
                if (!tnum_is_const(reg->var_off) || reg->var_off.value != 0) {
                        verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n",
                                regno);
                        return -EINVAL;
                }
        }

        switch (type) {
        /* Pointer types where both fixed and variable offset is explicitly allowed: */
        case PTR_TO_STACK:
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_MAP_KEY:
        case PTR_TO_MAP_VALUE:
        case PTR_TO_MEM:
        case PTR_TO_MEM | MEM_RDONLY:
        case PTR_TO_MEM | MEM_RINGBUF:
        case PTR_TO_BUF:
        case PTR_TO_BUF | MEM_RDONLY:
        case PTR_TO_ARENA:
        case SCALAR_VALUE:
                return 0;
        /* All the rest must be rejected, except PTR_TO_BTF_ID which allows
         * fixed offset.
         */
        case PTR_TO_BTF_ID:
        case PTR_TO_BTF_ID | MEM_ALLOC:
        case PTR_TO_BTF_ID | PTR_TRUSTED:
        case PTR_TO_BTF_ID | MEM_RCU:
        case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
        case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
                /* When referenced PTR_TO_BTF_ID is passed to release function,
                 * its fixed offset must be 0. In the other cases, fixed offset
                 * can be non-zero. This was already checked above. So pass
                 * fixed_off_ok as true to allow fixed offset for all other
                 * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we
                 * still need to do checks instead of returning.
                 */
                return __check_ptr_off_reg(env, reg, regno, true);
        case PTR_TO_CTX:
                /*
                 * Allow fixed and variable offsets for syscall context, but
                 * only when the argument is passed as memory, not ctx,
                 * otherwise we may get modified ctx in tail called programs and
                 * global subprogs (that may act as extension prog hooks).
                 */
                if (arg_type != ARG_PTR_TO_CTX && is_var_ctx_off_allowed(env->prog))
                        return 0;
                fallthrough;
        default:
                return __check_ptr_off_reg(env, reg, regno, false);
        }
}

static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
                                                const struct bpf_func_proto *fn,
                                                struct bpf_reg_state *regs)
{
        struct bpf_reg_state *state = NULL;
        int i;

        for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
                if (arg_type_is_dynptr(fn->arg_type[i])) {
                        if (state) {
                                verbose(env, "verifier internal error: multiple dynptr args\n");
                                return NULL;
                        }
                        state = &regs[BPF_REG_1 + i];
                }

        if (!state)
                verbose(env, "verifier internal error: no dynptr arg found\n");

        return state;
}

static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi;

        if (reg->type == CONST_PTR_TO_DYNPTR)
                return reg->id;
        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return spi;
        return state->stack[spi].spilled_ptr.id;
}

static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi;

        if (reg->type == CONST_PTR_TO_DYNPTR)
                return reg->ref_obj_id;
        spi = dynptr_get_spi(env, reg);
        if (spi < 0)
                return spi;
        return state->stack[spi].spilled_ptr.ref_obj_id;
}

static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
                                            struct bpf_reg_state *reg)
{
        struct bpf_func_state *state = bpf_func(env, reg);
        int spi;

        if (reg->type == CONST_PTR_TO_DYNPTR)
                return reg->dynptr.type;

        spi = bpf_get_spi(reg->var_off.value);
        if (spi < 0) {
                verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
                return BPF_DYNPTR_TYPE_INVALID;
        }

        return state->stack[spi].spilled_ptr.dynptr.type;
}

static int check_reg_const_str(struct bpf_verifier_env *env,
                               struct bpf_reg_state *reg, u32 regno)
{
        struct bpf_map *map = reg->map_ptr;
        int err;
        int map_off;
        u64 map_addr;
        char *str_ptr;

        if (reg->type != PTR_TO_MAP_VALUE)
                return -EINVAL;

        if (map->map_type == BPF_MAP_TYPE_INSN_ARRAY) {
                verbose(env, "R%d points to insn_array map which cannot be used as const string\n", regno);
                return -EACCES;
        }

        if (!bpf_map_is_rdonly(map)) {
                verbose(env, "R%d does not point to a readonly map'\n", regno);
                return -EACCES;
        }

        if (!tnum_is_const(reg->var_off)) {
                verbose(env, "R%d is not a constant address'\n", regno);
                return -EACCES;
        }

        if (!map->ops->map_direct_value_addr) {
                verbose(env, "no direct value access support for this map type\n");
                return -EACCES;
        }

        err = check_map_access(env, regno, 0,
                               map->value_size - reg->var_off.value, false,
                               ACCESS_HELPER);
        if (err)
                return err;

        map_off = reg->var_off.value;
        err = map->ops->map_direct_value_addr(map, &map_addr, map_off);
        if (err) {
                verbose(env, "direct value access on string failed\n");
                return err;
        }

        str_ptr = (char *)(long)(map_addr);
        if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
                verbose(env, "string is not zero-terminated\n");
                return -EINVAL;
        }
        return 0;
}

/* Returns constant key value in `value` if possible, else negative error */
static int get_constant_map_key(struct bpf_verifier_env *env,
                                struct bpf_reg_state *key,
                                u32 key_size,
                                s64 *value)
{
        struct bpf_func_state *state = bpf_func(env, key);
        struct bpf_reg_state *reg;
        int slot, spi, off;
        int spill_size = 0;
        int zero_size = 0;
        int stack_off;
        int i, err;
        u8 *stype;

        if (!env->bpf_capable)
                return -EOPNOTSUPP;
        if (key->type != PTR_TO_STACK)
                return -EOPNOTSUPP;
        if (!tnum_is_const(key->var_off))
                return -EOPNOTSUPP;

        stack_off = key->var_off.value;
        slot = -stack_off - 1;
        spi = slot / BPF_REG_SIZE;
        off = slot % BPF_REG_SIZE;
        stype = state->stack[spi].slot_type;

        /* First handle precisely tracked STACK_ZERO */
        for (i = off; i >= 0 && stype[i] == STACK_ZERO; i--)
                zero_size++;
        if (zero_size >= key_size) {
                *value = 0;
                return 0;
        }

        /* Check that stack contains a scalar spill of expected size */
        if (!bpf_is_spilled_scalar_reg(&state->stack[spi]))
                return -EOPNOTSUPP;
        for (i = off; i >= 0 && stype[i] == STACK_SPILL; i--)
                spill_size++;
        if (spill_size != key_size)
                return -EOPNOTSUPP;

        reg = &state->stack[spi].spilled_ptr;
        if (!tnum_is_const(reg->var_off))
                /* Stack value not statically known */
                return -EOPNOTSUPP;

        /* We are relying on a constant value. So mark as precise
         * to prevent pruning on it.
         */
        bpf_bt_set_frame_slot(&env->bt, key->frameno, spi);
        err = mark_chain_precision_batch(env, env->cur_state);
        if (err < 0)
                return err;

        *value = reg->var_off.value;
        return 0;
}

static bool can_elide_value_nullness(enum bpf_map_type type);

static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
                          struct bpf_call_arg_meta *meta,
                          const struct bpf_func_proto *fn,
                          int insn_idx)
{
        u32 regno = BPF_REG_1 + arg;
        struct bpf_reg_state *reg = reg_state(env, regno);
        enum bpf_arg_type arg_type = fn->arg_type[arg];
        enum bpf_reg_type type = reg->type;
        u32 *arg_btf_id = NULL;
        u32 key_size;
        int err = 0;

        if (arg_type == ARG_DONTCARE)
                return 0;

        err = check_reg_arg(env, regno, SRC_OP);
        if (err)
                return err;

        if (arg_type == ARG_ANYTHING) {
                if (is_pointer_value(env, regno)) {
                        verbose(env, "R%d leaks addr into helper function\n",
                                regno);
                        return -EACCES;
                }
                return 0;
        }

        if (type_is_pkt_pointer(type) &&
            !may_access_direct_pkt_data(env, meta, BPF_READ)) {
                verbose(env, "helper access to the packet is not allowed\n");
                return -EACCES;
        }

        if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) {
                err = resolve_map_arg_type(env, meta, &arg_type);
                if (err)
                        return err;
        }

        if (bpf_register_is_null(reg) && type_may_be_null(arg_type))
                /* A NULL register has a SCALAR_VALUE type, so skip
                 * type checking.
                 */
                goto skip_type_check;

        /* arg_btf_id and arg_size are in a union. */
        if (base_type(arg_type) == ARG_PTR_TO_BTF_ID ||
            base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK)
                arg_btf_id = fn->arg_btf_id[arg];

        err = check_reg_type(env, regno, arg_type, arg_btf_id, meta);
        if (err)
                return err;

        err = check_func_arg_reg_off(env, reg, regno, arg_type);
        if (err)
                return err;

skip_type_check:
        if (arg_type_is_release(arg_type)) {
                if (arg_type_is_dynptr(arg_type)) {
                        struct bpf_func_state *state = bpf_func(env, reg);
                        int spi;

                        /* Only dynptr created on stack can be released, thus
                         * the get_spi and stack state checks for spilled_ptr
                         * should only be done before process_dynptr_func for
                         * PTR_TO_STACK.
                         */
                        if (reg->type == PTR_TO_STACK) {
                                spi = dynptr_get_spi(env, reg);
                                if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) {
                                        verbose(env, "arg %d is an unacquired reference\n", regno);
                                        return -EINVAL;
                                }
                        } else {
                                verbose(env, "cannot release unowned const bpf_dynptr\n");
                                return -EINVAL;
                        }
                } else if (!reg->ref_obj_id && !bpf_register_is_null(reg)) {
                        verbose(env, "R%d must be referenced when passed to release function\n",
                                regno);
                        return -EINVAL;
                }
                if (meta->release_regno) {
                        verifier_bug(env, "more than one release argument");
                        return -EFAULT;
                }
                meta->release_regno = regno;
        }

        if (reg->ref_obj_id && base_type(arg_type) != ARG_KPTR_XCHG_DEST) {
                if (meta->ref_obj_id) {
                        verbose(env, "more than one arg with ref_obj_id R%d %u %u",
                                regno, reg->ref_obj_id,
                                meta->ref_obj_id);
                        return -EACCES;
                }
                meta->ref_obj_id = reg->ref_obj_id;
        }

        switch (base_type(arg_type)) {
        case ARG_CONST_MAP_PTR:
                /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
                if (meta->map.ptr) {
                        /* Use map_uid (which is unique id of inner map) to reject:
                         * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
                         * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
                         * if (inner_map1 && inner_map2) {
                         *     timer = bpf_map_lookup_elem(inner_map1);
                         *     if (timer)
                         *         // mismatch would have been allowed
                         *         bpf_timer_init(timer, inner_map2);
                         * }
                         *
                         * Comparing map_ptr is enough to distinguish normal and outer maps.
                         */
                        if (meta->map.ptr != reg->map_ptr ||
                            meta->map.uid != reg->map_uid) {
                                verbose(env,
                                        "timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
                                        meta->map.uid, reg->map_uid);
                                return -EINVAL;
                        }
                }
                meta->map.ptr = reg->map_ptr;
                meta->map.uid = reg->map_uid;
                break;
        case ARG_PTR_TO_MAP_KEY:
                /* bpf_map_xxx(..., map_ptr, ..., key) call:
                 * check that [key, key + map->key_size) are within
                 * stack limits and initialized
                 */
                if (!meta->map.ptr) {
                        /* in function declaration map_ptr must come before
                         * map_key, so that it's verified and known before
                         * we have to check map_key here. Otherwise it means
                         * that kernel subsystem misconfigured verifier
                         */
                        verifier_bug(env, "invalid map_ptr to access map->key");
                        return -EFAULT;
                }
                key_size = meta->map.ptr->key_size;
                err = check_helper_mem_access(env, regno, key_size, BPF_READ, false, NULL);
                if (err)
                        return err;
                if (can_elide_value_nullness(meta->map.ptr->map_type)) {
                        err = get_constant_map_key(env, reg, key_size, &meta->const_map_key);
                        if (err < 0) {
                                meta->const_map_key = -1;
                                if (err == -EOPNOTSUPP)
                                        err = 0;
                                else
                                        return err;
                        }
                }
                break;
        case ARG_PTR_TO_MAP_VALUE:
                if (type_may_be_null(arg_type) && bpf_register_is_null(reg))
                        return 0;

                /* bpf_map_xxx(..., map_ptr, ..., value) call:
                 * check [value, value + map->value_size) validity
                 */
                if (!meta->map.ptr) {
                        /* kernel subsystem misconfigured verifier */
                        verifier_bug(env, "invalid map_ptr to access map->value");
                        return -EFAULT;
                }
                meta->raw_mode = arg_type & MEM_UNINIT;
                err = check_helper_mem_access(env, regno, meta->map.ptr->value_size,
                                              arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ,
                                              false, meta);
                break;
        case ARG_PTR_TO_PERCPU_BTF_ID:
                if (!reg->btf_id) {
                        verbose(env, "Helper has invalid btf_id in R%d\n", regno);
                        return -EACCES;
                }
                meta->ret_btf = reg->btf;
                meta->ret_btf_id = reg->btf_id;
                break;
        case ARG_PTR_TO_SPIN_LOCK:
                if (in_rbtree_lock_required_cb(env)) {
                        verbose(env, "can't spin_{lock,unlock} in rbtree cb\n");
                        return -EACCES;
                }
                if (meta->func_id == BPF_FUNC_spin_lock) {
                        err = process_spin_lock(env, regno, PROCESS_SPIN_LOCK);
                        if (err)
                                return err;
                } else if (meta->func_id == BPF_FUNC_spin_unlock) {
                        err = process_spin_lock(env, regno, 0);
                        if (err)
                                return err;
                } else {
                        verifier_bug(env, "spin lock arg on unexpected helper");
                        return -EFAULT;
                }
                break;
        case ARG_PTR_TO_TIMER:
                err = process_timer_helper(env, regno, meta);
                if (err)
                        return err;
                break;
        case ARG_PTR_TO_FUNC:
                meta->subprogno = reg->subprogno;
                break;
        case ARG_PTR_TO_MEM:
                /* The access to this pointer is only checked when we hit the
                 * next is_mem_size argument below.
                 */
                meta->raw_mode = arg_type & MEM_UNINIT;
                if (arg_type & MEM_FIXED_SIZE) {
                        err = check_helper_mem_access(env, regno, fn->arg_size[arg],
                                                      arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ,
                                                      false, meta);
                        if (err)
                                return err;
                        if (arg_type & MEM_ALIGNED)
                                err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true);
                }
                break;
        case ARG_CONST_SIZE:
                err = check_mem_size_reg(env, reg, regno,
                                         fn->arg_type[arg - 1] & MEM_WRITE ?
                                         BPF_WRITE : BPF_READ,
                                         false, meta);
                break;
        case ARG_CONST_SIZE_OR_ZERO:
                err = check_mem_size_reg(env, reg, regno,
                                         fn->arg_type[arg - 1] & MEM_WRITE ?
                                         BPF_WRITE : BPF_READ,
                                         true, meta);
                break;
        case ARG_PTR_TO_DYNPTR:
                err = process_dynptr_func(env, regno, insn_idx, arg_type, 0);
                if (err)
                        return err;
                break;
        case ARG_CONST_ALLOC_SIZE_OR_ZERO:
                if (!tnum_is_const(reg->var_off)) {
                        verbose(env, "R%d is not a known constant'\n",
                                regno);
                        return -EACCES;
                }
                meta->mem_size = reg->var_off.value;
                err = mark_chain_precision(env, regno);
                if (err)
                        return err;
                break;
        case ARG_PTR_TO_CONST_STR:
        {
                err = check_reg_const_str(env, reg, regno);
                if (err)
                        return err;
                break;
        }
        case ARG_KPTR_XCHG_DEST:
                err = process_kptr_func(env, regno, meta);
                if (err)
                        return err;
                break;
        }

        return err;
}

static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
{
        enum bpf_attach_type eatype = env->prog->expected_attach_type;
        enum bpf_prog_type type = resolve_prog_type(env->prog);

        if (func_id != BPF_FUNC_map_update_elem &&
            func_id != BPF_FUNC_map_delete_elem)
                return false;

        /* It's not possible to get access to a locked struct sock in these
         * contexts, so updating is safe.
         */
        switch (type) {
        case BPF_PROG_TYPE_TRACING:
                if (eatype == BPF_TRACE_ITER)
                        return true;
                break;
        case BPF_PROG_TYPE_SOCK_OPS:
                /* map_update allowed only via dedicated helpers with event type checks */
                if (func_id == BPF_FUNC_map_delete_elem)
                        return true;
                break;
        case BPF_PROG_TYPE_SOCKET_FILTER:
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
        case BPF_PROG_TYPE_XDP:
        case BPF_PROG_TYPE_SK_REUSEPORT:
        case BPF_PROG_TYPE_FLOW_DISSECTOR:
        case BPF_PROG_TYPE_SK_LOOKUP:
                return true;
        default:
                break;
        }

        verbose(env, "cannot update sockmap in this context\n");
        return false;
}

bool bpf_allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
        return env->prog->jit_requested &&
               bpf_jit_supports_subprog_tailcalls();
}

static int check_map_func_compatibility(struct bpf_verifier_env *env,
                                        struct bpf_map *map, int func_id)
{
        if (!map)
                return 0;

        /* We need a two way check, first is from map perspective ... */
        switch (map->map_type) {
        case BPF_MAP_TYPE_PROG_ARRAY:
                if (func_id != BPF_FUNC_tail_call)
                        goto error;
                break;
        case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
                if (func_id != BPF_FUNC_perf_event_read &&
                    func_id != BPF_FUNC_perf_event_output &&
                    func_id != BPF_FUNC_skb_output &&
                    func_id != BPF_FUNC_perf_event_read_value &&
                    func_id != BPF_FUNC_xdp_output)
                        goto error;
                break;
        case BPF_MAP_TYPE_RINGBUF:
                if (func_id != BPF_FUNC_ringbuf_output &&
                    func_id != BPF_FUNC_ringbuf_reserve &&
                    func_id != BPF_FUNC_ringbuf_query &&
                    func_id != BPF_FUNC_ringbuf_reserve_dynptr &&
                    func_id != BPF_FUNC_ringbuf_submit_dynptr &&
                    func_id != BPF_FUNC_ringbuf_discard_dynptr)
                        goto error;
                break;
        case BPF_MAP_TYPE_USER_RINGBUF:
                if (func_id != BPF_FUNC_user_ringbuf_drain)
                        goto error;
                break;
        case BPF_MAP_TYPE_STACK_TRACE:
                if (func_id != BPF_FUNC_get_stackid)
                        goto error;
                break;
        case BPF_MAP_TYPE_CGROUP_ARRAY:
                if (func_id != BPF_FUNC_skb_under_cgroup &&
                    func_id != BPF_FUNC_current_task_under_cgroup)
                        goto error;
                break;
        case BPF_MAP_TYPE_CGROUP_STORAGE:
        case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
                if (func_id != BPF_FUNC_get_local_storage)
                        goto error;
                break;
        case BPF_MAP_TYPE_DEVMAP:
        case BPF_MAP_TYPE_DEVMAP_HASH:
                if (func_id != BPF_FUNC_redirect_map &&
                    func_id != BPF_FUNC_map_lookup_elem)
                        goto error;
                break;
        /* Restrict bpf side of cpumap and xskmap, open when use-cases
         * appear.
         */
        case BPF_MAP_TYPE_CPUMAP:
                if (func_id != BPF_FUNC_redirect_map)
                        goto error;
                break;
        case BPF_MAP_TYPE_XSKMAP:
                if (func_id != BPF_FUNC_redirect_map &&
                    func_id != BPF_FUNC_map_lookup_elem)
                        goto error;
                break;
        case BPF_MAP_TYPE_ARRAY_OF_MAPS:
        case BPF_MAP_TYPE_HASH_OF_MAPS:
                if (func_id != BPF_FUNC_map_lookup_elem)
                        goto error;
                break;
        case BPF_MAP_TYPE_SOCKMAP:
                if (func_id != BPF_FUNC_sk_redirect_map &&
                    func_id != BPF_FUNC_sock_map_update &&
                    func_id != BPF_FUNC_msg_redirect_map &&
                    func_id != BPF_FUNC_sk_select_reuseport &&
                    func_id != BPF_FUNC_map_lookup_elem &&
                    !may_update_sockmap(env, func_id))
                        goto error;
                break;
        case BPF_MAP_TYPE_SOCKHASH:
                if (func_id != BPF_FUNC_sk_redirect_hash &&
                    func_id != BPF_FUNC_sock_hash_update &&
                    func_id != BPF_FUNC_msg_redirect_hash &&
                    func_id != BPF_FUNC_sk_select_reuseport &&
                    func_id != BPF_FUNC_map_lookup_elem &&
                    !may_update_sockmap(env, func_id))
                        goto error;
                break;
        case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
                if (func_id != BPF_FUNC_sk_select_reuseport)
                        goto error;
                break;
        case BPF_MAP_TYPE_QUEUE:
        case BPF_MAP_TYPE_STACK:
                if (func_id != BPF_FUNC_map_peek_elem &&
                    func_id != BPF_FUNC_map_pop_elem &&
                    func_id != BPF_FUNC_map_push_elem)
                        goto error;
                break;
        case BPF_MAP_TYPE_SK_STORAGE:
                if (func_id != BPF_FUNC_sk_storage_get &&
                    func_id != BPF_FUNC_sk_storage_delete &&
                    func_id != BPF_FUNC_kptr_xchg)
                        goto error;
                break;
        case BPF_MAP_TYPE_INODE_STORAGE:
                if (func_id != BPF_FUNC_inode_storage_get &&
                    func_id != BPF_FUNC_inode_storage_delete &&
                    func_id != BPF_FUNC_kptr_xchg)
                        goto error;
                break;
        case BPF_MAP_TYPE_TASK_STORAGE:
                if (func_id != BPF_FUNC_task_storage_get &&
                    func_id != BPF_FUNC_task_storage_delete &&
                    func_id != BPF_FUNC_kptr_xchg)
                        goto error;
                break;
        case BPF_MAP_TYPE_CGRP_STORAGE:
                if (func_id != BPF_FUNC_cgrp_storage_get &&
                    func_id != BPF_FUNC_cgrp_storage_delete &&
                    func_id != BPF_FUNC_kptr_xchg)
                        goto error;
                break;
        case BPF_MAP_TYPE_BLOOM_FILTER:
                if (func_id != BPF_FUNC_map_peek_elem &&
                    func_id != BPF_FUNC_map_push_elem)
                        goto error;
                break;
        case BPF_MAP_TYPE_INSN_ARRAY:
                goto error;
        default:
                break;
        }

        /* ... and second from the function itself. */
        switch (func_id) {
        case BPF_FUNC_tail_call:
                if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
                        goto error;
                if (env->subprog_cnt > 1 && !bpf_allow_tail_call_in_subprogs(env)) {
                        verbose(env, "mixing of tail_calls and bpf-to-bpf calls is not supported\n");
                        return -EINVAL;
                }
                break;
        case BPF_FUNC_perf_event_read:
        case BPF_FUNC_perf_event_output:
        case BPF_FUNC_perf_event_read_value:
        case BPF_FUNC_skb_output:
        case BPF_FUNC_xdp_output:
                if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
                        goto error;
                break;
        case BPF_FUNC_ringbuf_output:
        case BPF_FUNC_ringbuf_reserve:
        case BPF_FUNC_ringbuf_query:
        case BPF_FUNC_ringbuf_reserve_dynptr:
        case BPF_FUNC_ringbuf_submit_dynptr:
        case BPF_FUNC_ringbuf_discard_dynptr:
                if (map->map_type != BPF_MAP_TYPE_RINGBUF)
                        goto error;
                break;
        case BPF_FUNC_user_ringbuf_drain:
                if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF)
                        goto error;
                break;
        case BPF_FUNC_get_stackid:
                if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
                        goto error;
                break;
        case BPF_FUNC_current_task_under_cgroup:
        case BPF_FUNC_skb_under_cgroup:
                if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
                        goto error;
                break;
        case BPF_FUNC_redirect_map:
                if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
                    map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
                    map->map_type != BPF_MAP_TYPE_CPUMAP &&
                    map->map_type != BPF_MAP_TYPE_XSKMAP)
                        goto error;
                break;
        case BPF_FUNC_sk_redirect_map:
        case BPF_FUNC_msg_redirect_map:
        case BPF_FUNC_sock_map_update:
                if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
                        goto error;
                break;
        case BPF_FUNC_sk_redirect_hash:
        case BPF_FUNC_msg_redirect_hash:
        case BPF_FUNC_sock_hash_update:
                if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
                        goto error;
                break;
        case BPF_FUNC_get_local_storage:
                if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
                    map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
                        goto error;
                break;
        case BPF_FUNC_sk_select_reuseport:
                if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
                    map->map_type != BPF_MAP_TYPE_SOCKMAP &&
                    map->map_type != BPF_MAP_TYPE_SOCKHASH)
                        goto error;
                break;
        case BPF_FUNC_map_pop_elem:
                if (map->map_type != BPF_MAP_TYPE_QUEUE &&
                    map->map_type != BPF_MAP_TYPE_STACK)
                        goto error;
                break;
        case BPF_FUNC_map_peek_elem:
        case BPF_FUNC_map_push_elem:
                if (map->map_type != BPF_MAP_TYPE_QUEUE &&
                    map->map_type != BPF_MAP_TYPE_STACK &&
                    map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
                        goto error;
                break;
        case BPF_FUNC_map_lookup_percpu_elem:
                if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
                    map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
                    map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
                        goto error;
                break;
        case BPF_FUNC_sk_storage_get:
        case BPF_FUNC_sk_storage_delete:
                if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
                        goto error;
                break;
        case BPF_FUNC_inode_storage_get:
        case BPF_FUNC_inode_storage_delete:
                if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
                        goto error;
                break;
        case BPF_FUNC_task_storage_get:
        case BPF_FUNC_task_storage_delete:
                if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
                        goto error;
                break;
        case BPF_FUNC_cgrp_storage_get:
        case BPF_FUNC_cgrp_storage_delete:
                if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
                        goto error;
                break;
        default:
                break;
        }

        return 0;
error:
        verbose(env, "cannot pass map_type %d into func %s#%d\n",
                map->map_type, func_id_name(func_id), func_id);
        return -EINVAL;
}

static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
        int count = 0;

        if (arg_type_is_raw_mem(fn->arg1_type))
                count++;
        if (arg_type_is_raw_mem(fn->arg2_type))
                count++;
        if (arg_type_is_raw_mem(fn->arg3_type))
                count++;
        if (arg_type_is_raw_mem(fn->arg4_type))
                count++;
        if (arg_type_is_raw_mem(fn->arg5_type))
                count++;

        /* We only support one arg being in raw mode at the moment,
         * which is sufficient for the helper functions we have
         * right now.
         */
        return count <= 1;
}

static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg)
{
        bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE;
        bool has_size = fn->arg_size[arg] != 0;
        bool is_next_size = false;

        if (arg + 1 < ARRAY_SIZE(fn->arg_type))
                is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]);

        if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM)
                return is_next_size;

        return has_size == is_next_size || is_next_size == is_fixed;
}

static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
{
        /* bpf_xxx(..., buf, len) call will access 'len'
         * bytes from memory 'buf'. Both arg types need
         * to be paired, so make sure there's no buggy
         * helper function specification.
         */
        if (arg_type_is_mem_size(fn->arg1_type) ||
            check_args_pair_invalid(fn, 0) ||
            check_args_pair_invalid(fn, 1) ||
            check_args_pair_invalid(fn, 2) ||
            check_args_pair_invalid(fn, 3) ||
            check_args_pair_invalid(fn, 4))
                return false;

        return true;
}

static bool check_btf_id_ok(const struct bpf_func_proto *fn)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
                if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID)
                        return !!fn->arg_btf_id[i];
                if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK)
                        return fn->arg_btf_id[i] == BPF_PTR_POISON;
                if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] &&
                    /* arg_btf_id and arg_size are in a union. */
                    (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM ||
                     !(fn->arg_type[i] & MEM_FIXED_SIZE)))
                        return false;
        }

        return true;
}

static bool check_mem_arg_rw_flag_ok(const struct bpf_func_proto *fn)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
                enum bpf_arg_type arg_type = fn->arg_type[i];

                if (base_type(arg_type) != ARG_PTR_TO_MEM)
                        continue;
                if (!(arg_type & (MEM_WRITE | MEM_RDONLY)))
                        return false;
        }

        return true;
}

static int check_func_proto(const struct bpf_func_proto *fn)
{
        return check_raw_mode_ok(fn) &&
               check_arg_pair_ok(fn) &&
               check_mem_arg_rw_flag_ok(fn) &&
               check_btf_id_ok(fn) ? 0 : -EINVAL;
}

/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
 * are now invalid, so turn them into unknown SCALAR_VALUE.
 *
 * This also applies to dynptr slices belonging to skb and xdp dynptrs,
 * since these slices point to packet data.
 */
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
        struct bpf_func_state *state;
        struct bpf_reg_state *reg;

        bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
                if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
                        mark_reg_invalid(env, reg);
        }));
}

enum {
        AT_PKT_END = -1,
        BEYOND_PKT_END = -2,
};

static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
{
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *reg = &state->regs[regn];

        if (reg->type != PTR_TO_PACKET)
                /* PTR_TO_PACKET_META is not supported yet */
                return;

        /* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
         * How far beyond pkt_end it goes is unknown.
         * if (!range_open) it's the case of pkt >= pkt_end
         * if (range_open) it's the case of pkt > pkt_end
         * hence this pointer is at least 1 byte bigger than pkt_end
         */
        if (range_open)
                reg->range = BEYOND_PKT_END;
        else
                reg->range = AT_PKT_END;
}

static int release_reference_nomark(struct bpf_verifier_state *state, int ref_obj_id)
{
        int i;

        for (i = 0; i < state->acquired_refs; i++) {
                if (state->refs[i].type != REF_TYPE_PTR)
                        continue;
                if (state->refs[i].id == ref_obj_id) {
                        release_reference_state(state, i);
                        return 0;
                }
        }
        return -EINVAL;
}

/* The pointer with the specified id has released its reference to kernel
 * resources. Identify all copies of the same pointer and clear the reference.
 *
 * This is the release function corresponding to acquire_reference(). Idempotent.
 */
static int release_reference(struct bpf_verifier_env *env, int ref_obj_id)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state;
        struct bpf_reg_state *reg;
        int err;

        err = release_reference_nomark(vstate, ref_obj_id);
        if (err)
                return err;

        bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                if (reg->ref_obj_id == ref_obj_id)
                        mark_reg_invalid(env, reg);
        }));

        return 0;
}

static void invalidate_non_owning_refs(struct bpf_verifier_env *env)
{
        struct bpf_func_state *unused;
        struct bpf_reg_state *reg;

        bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
                if (type_is_non_owning_ref(reg->type))
                        mark_reg_invalid(env, reg);
        }));
}

static void clear_caller_saved_regs(struct bpf_verifier_env *env,
                                    struct bpf_reg_state *regs)
{
        int i;

        /* after the call registers r0 - r5 were scratched */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                bpf_mark_reg_not_init(env, &regs[caller_saved[i]]);
                __check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK);
        }
}

typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
                                   struct bpf_func_state *caller,
                                   struct bpf_func_state *callee,
                                   int insn_idx);

static int set_callee_state(struct bpf_verifier_env *env,
                            struct bpf_func_state *caller,
                            struct bpf_func_state *callee, int insn_idx);

static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite,
                            set_callee_state_fn set_callee_state_cb,
                            struct bpf_verifier_state *state)
{
        struct bpf_func_state *caller, *callee;
        int err;

        if (state->curframe + 1 >= MAX_CALL_FRAMES) {
                verbose(env, "the call stack of %d frames is too deep\n",
                        state->curframe + 2);
                return -E2BIG;
        }

        if (state->frame[state->curframe + 1]) {
                verifier_bug(env, "Frame %d already allocated", state->curframe + 1);
                return -EFAULT;
        }

        caller = state->frame[state->curframe];
        callee = kzalloc_obj(*callee, GFP_KERNEL_ACCOUNT);
        if (!callee)
                return -ENOMEM;
        state->frame[state->curframe + 1] = callee;

        /* callee cannot access r0, r6 - r9 for reading and has to write
         * into its own stack before reading from it.
         * callee can read/write into caller's stack
         */
        init_func_state(env, callee,
                        /* remember the callsite, it will be used by bpf_exit */
                        callsite,
                        state->curframe + 1 /* frameno within this callchain */,
                        subprog /* subprog number within this prog */);
        err = set_callee_state_cb(env, caller, callee, callsite);
        if (err)
                goto err_out;

        /* only increment it after check_reg_arg() finished */
        state->curframe++;

        return 0;

err_out:
        free_func_state(callee);
        state->frame[state->curframe + 1] = NULL;
        return err;
}

static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
                                    const struct btf *btf,
                                    struct bpf_reg_state *regs)
{
        struct bpf_subprog_info *sub = subprog_info(env, subprog);
        struct bpf_verifier_log *log = &env->log;
        u32 i;
        int ret;

        ret = btf_prepare_func_args(env, subprog);
        if (ret)
                return ret;

        /* check that BTF function arguments match actual types that the
         * verifier sees.
         */
        for (i = 0; i < sub->arg_cnt; i++) {
                u32 regno = i + 1;
                struct bpf_reg_state *reg = &regs[regno];
                struct bpf_subprog_arg_info *arg = &sub->args[i];

                if (arg->arg_type == ARG_ANYTHING) {
                        if (reg->type != SCALAR_VALUE) {
                                bpf_log(log, "R%d is not a scalar\n", regno);
                                return -EINVAL;
                        }
                } else if (arg->arg_type & PTR_UNTRUSTED) {
                        /*
                         * Anything is allowed for untrusted arguments, as these are
                         * read-only and probe read instructions would protect against
                         * invalid memory access.
                         */
                } else if (arg->arg_type == ARG_PTR_TO_CTX) {
                        ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_CTX);
                        if (ret < 0)
                                return ret;
                        /* If function expects ctx type in BTF check that caller
                         * is passing PTR_TO_CTX.
                         */
                        if (reg->type != PTR_TO_CTX) {
                                bpf_log(log, "arg#%d expects pointer to ctx\n", i);
                                return -EINVAL;
                        }
                } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
                        ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
                        if (ret < 0)
                                return ret;
                        if (check_mem_reg(env, reg, regno, arg->mem_size))
                                return -EINVAL;
                        if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) {
                                bpf_log(log, "arg#%d is expected to be non-NULL\n", i);
                                return -EINVAL;
                        }
                } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
                        /*
                         * Can pass any value and the kernel won't crash, but
                         * only PTR_TO_ARENA or SCALAR make sense. Everything
                         * else is a bug in the bpf program. Point it out to
                         * the user at the verification time instead of
                         * run-time debug nightmare.
                         */
                        if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) {
                                bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno);
                                return -EINVAL;
                        }
                } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
                        ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_DYNPTR);
                        if (ret)
                                return ret;

                        ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0);
                        if (ret)
                                return ret;
                } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
                        struct bpf_call_arg_meta meta;
                        int err;

                        if (bpf_register_is_null(reg) && type_may_be_null(arg->arg_type))
                                continue;

                        memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */
                        err = check_reg_type(env, regno, arg->arg_type, &arg->btf_id, &meta);
                        err = err ?: check_func_arg_reg_off(env, reg, regno, arg->arg_type);
                        if (err)
                                return err;
                } else {
                        verifier_bug(env, "unrecognized arg#%d type %d", i, arg->arg_type);
                        return -EFAULT;
                }
        }

        return 0;
}

/* Compare BTF of a function call with given bpf_reg_state.
 * Returns:
 * EFAULT - there is a verifier bug. Abort verification.
 * EINVAL - there is a type mismatch or BTF is not available.
 * 0 - BTF matches with what bpf_reg_state expects.
 * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
 */
static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
                                  struct bpf_reg_state *regs)
{
        struct bpf_prog *prog = env->prog;
        struct btf *btf = prog->aux->btf;
        u32 btf_id;
        int err;

        if (!prog->aux->func_info)
                return -EINVAL;

        btf_id = prog->aux->func_info[subprog].type_id;
        if (!btf_id)
                return -EFAULT;

        if (prog->aux->func_info_aux[subprog].unreliable)
                return -EINVAL;

        err = btf_check_func_arg_match(env, subprog, btf, regs);
        /* Compiler optimizations can remove arguments from static functions
         * or mismatched type can be passed into a global function.
         * In such cases mark the function as unreliable from BTF point of view.
         */
        if (err)
                prog->aux->func_info_aux[subprog].unreliable = true;
        return err;
}

static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                              int insn_idx, int subprog,
                              set_callee_state_fn set_callee_state_cb)
{
        struct bpf_verifier_state *state = env->cur_state, *callback_state;
        struct bpf_func_state *caller, *callee;
        int err;

        caller = state->frame[state->curframe];
        err = btf_check_subprog_call(env, subprog, caller->regs);
        if (err == -EFAULT)
                return err;

        /* set_callee_state is used for direct subprog calls, but we are
         * interested in validating only BPF helpers that can call subprogs as
         * callbacks
         */
        env->subprog_info[subprog].is_cb = true;
        if (bpf_pseudo_kfunc_call(insn) &&
            !is_callback_calling_kfunc(insn->imm)) {
                verifier_bug(env, "kfunc %s#%d not marked as callback-calling",
                             func_id_name(insn->imm), insn->imm);
                return -EFAULT;
        } else if (!bpf_pseudo_kfunc_call(insn) &&
                   !is_callback_calling_function(insn->imm)) { /* helper */
                verifier_bug(env, "helper %s#%d not marked as callback-calling",
                             func_id_name(insn->imm), insn->imm);
                return -EFAULT;
        }

        if (bpf_is_async_callback_calling_insn(insn)) {
                struct bpf_verifier_state *async_cb;

                /* there is no real recursion here. timer and workqueue callbacks are async */
                env->subprog_info[subprog].is_async_cb = true;
                async_cb = push_async_cb(env, env->subprog_info[subprog].start,
                                         insn_idx, subprog,
                                         is_async_cb_sleepable(env, insn));
                if (IS_ERR(async_cb))
                        return PTR_ERR(async_cb);
                callee = async_cb->frame[0];
                callee->async_entry_cnt = caller->async_entry_cnt + 1;

                /* Convert bpf_timer_set_callback() args into timer callback args */
                err = set_callee_state_cb(env, caller, callee, insn_idx);
                if (err)
                        return err;

                return 0;
        }

        /* for callback functions enqueue entry to callback and
         * proceed with next instruction within current frame.
         */
        callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false);
        if (IS_ERR(callback_state))
                return PTR_ERR(callback_state);

        err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb,
                               callback_state);
        if (err)
                return err;

        callback_state->callback_unroll_depth++;
        callback_state->frame[callback_state->curframe - 1]->callback_depth++;
        caller->callback_depth = 0;
        return 0;
}

static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                           int *insn_idx)
{
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_func_state *caller;
        int err, subprog, target_insn;

        target_insn = *insn_idx + insn->imm + 1;
        subprog = bpf_find_subprog(env, target_insn);
        if (verifier_bug_if(subprog < 0, env, "target of func call at insn %d is not a program",
                            target_insn))
                return -EFAULT;

        caller = state->frame[state->curframe];
        err = btf_check_subprog_call(env, subprog, caller->regs);
        if (err == -EFAULT)
                return err;
        if (bpf_subprog_is_global(env, subprog)) {
                const char *sub_name = subprog_name(env, subprog);

                if (env->cur_state->active_locks) {
                        verbose(env, "global function calls are not allowed while holding a lock,\n"
                                     "use static function instead\n");
                        return -EINVAL;
                }

                if (env->subprog_info[subprog].might_sleep && !in_sleepable_context(env)) {
                        verbose(env, "sleepable global function %s() called in %s\n",
                                sub_name, non_sleepable_context_description(env));
                        return -EINVAL;
                }

                if (err) {
                        verbose(env, "Caller passes invalid args into func#%d ('%s')\n",
                                subprog, sub_name);
                        return err;
                }

                if (env->log.level & BPF_LOG_LEVEL)
                        verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
                                subprog, sub_name);
                if (env->subprog_info[subprog].changes_pkt_data)
                        clear_all_pkt_pointers(env);
                /* mark global subprog for verifying after main prog */
                subprog_aux(env, subprog)->called = true;
                clear_caller_saved_regs(env, caller->regs);

                /* All non-void global functions return a 64-bit SCALAR_VALUE. */
                if (!subprog_returns_void(env, subprog)) {
                        mark_reg_unknown(env, caller->regs, BPF_REG_0);
                        caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
                }

                /* continue with next insn after call */
                return 0;
        }

        /* for regular function entry setup new frame and continue
         * from that frame.
         */
        err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state);
        if (err)
                return err;

        clear_caller_saved_regs(env, caller->regs);

        /* and go analyze first insn of the callee */
        *insn_idx = env->subprog_info[subprog].start - 1;

        if (env->log.level & BPF_LOG_LEVEL) {
                verbose(env, "caller:\n");
                print_verifier_state(env, state, caller->frameno, true);
                verbose(env, "callee:\n");
                print_verifier_state(env, state, state->curframe, true);
        }

        return 0;
}

int map_set_for_each_callback_args(struct bpf_verifier_env *env,
                                   struct bpf_func_state *caller,
                                   struct bpf_func_state *callee)
{
        /* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn,
         *      void *callback_ctx, u64 flags);
         * callback_fn(struct bpf_map *map, void *key, void *value,
         *      void *callback_ctx);
         */
        callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];

        callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
        __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
        callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr;

        callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
        __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
        callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr;

        /* pointer to stack or null */
        callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
        return 0;
}

static int set_callee_state(struct bpf_verifier_env *env,
                            struct bpf_func_state *caller,
                            struct bpf_func_state *callee, int insn_idx)
{
        int i;

        /* copy r1 - r5 args that callee can access.  The copy includes parent
         * pointers, which connects us up to the liveness chain
         */
        for (i = BPF_REG_1; i <= BPF_REG_5; i++)
                callee->regs[i] = caller->regs[i];
        return 0;
}

static int set_map_elem_callback_state(struct bpf_verifier_env *env,
                                       struct bpf_func_state *caller,
                                       struct bpf_func_state *callee,
                                       int insn_idx)
{
        struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
        struct bpf_map *map;
        int err;

        /* valid map_ptr and poison value does not matter */
        map = insn_aux->map_ptr_state.map_ptr;
        if (!map->ops->map_set_for_each_callback_args ||
            !map->ops->map_for_each_callback) {
                verbose(env, "callback function not allowed for map\n");
                return -ENOTSUPP;
        }

        err = map->ops->map_set_for_each_callback_args(env, caller, callee);
        if (err)
                return err;

        callee->in_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 1);
        return 0;
}

static int set_loop_callback_state(struct bpf_verifier_env *env,
                                   struct bpf_func_state *caller,
                                   struct bpf_func_state *callee,
                                   int insn_idx)
{
        /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
         *          u64 flags);
         * callback_fn(u64 index, void *callback_ctx);
         */
        callee->regs[BPF_REG_1].type = SCALAR_VALUE;
        callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);

        callee->in_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 1);
        return 0;
}

static int set_timer_callback_state(struct bpf_verifier_env *env,
                                    struct bpf_func_state *caller,
                                    struct bpf_func_state *callee,
                                    int insn_idx)
{
        struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr;

        /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
         * callback_fn(struct bpf_map *map, void *key, void *value);
         */
        callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
        __mark_reg_known_zero(&callee->regs[BPF_REG_1]);
        callee->regs[BPF_REG_1].map_ptr = map_ptr;

        callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
        __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
        callee->regs[BPF_REG_2].map_ptr = map_ptr;

        callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
        __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
        callee->regs[BPF_REG_3].map_ptr = map_ptr;

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
        callee->in_async_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 0);
        return 0;
}

static int set_find_vma_callback_state(struct bpf_verifier_env *env,
                                       struct bpf_func_state *caller,
                                       struct bpf_func_state *callee,
                                       int insn_idx)
{
        /* bpf_find_vma(struct task_struct *task, u64 addr,
         *               void *callback_fn, void *callback_ctx, u64 flags)
         * (callback_fn)(struct task_struct *task,
         *               struct vm_area_struct *vma, void *callback_ctx);
         */
        callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];

        callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
        __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
        callee->regs[BPF_REG_2].btf =  btf_vmlinux;
        callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];

        /* pointer to stack or null */
        callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
        callee->in_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 1);
        return 0;
}

static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env,
                                           struct bpf_func_state *caller,
                                           struct bpf_func_state *callee,
                                           int insn_idx)
{
        /* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void
         *                        callback_ctx, u64 flags);
         * callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx);
         */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_0]);
        mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL);
        callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);

        callee->in_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 1);
        return 0;
}

static int set_rbtree_add_callback_state(struct bpf_verifier_env *env,
                                         struct bpf_func_state *caller,
                                         struct bpf_func_state *callee,
                                         int insn_idx)
{
        /* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node,
         *                     bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b));
         *
         * 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset
         * that 'less' callback args will be receiving. However, 'node' arg was release_reference'd
         * by this point, so look at 'root'
         */
        struct btf_field *field;

        field = reg_find_field_offset(&caller->regs[BPF_REG_1],
                                      caller->regs[BPF_REG_1].var_off.value,
                                      BPF_RB_ROOT);
        if (!field || !field->graph_root.value_btf_id)
                return -EFAULT;

        mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root);
        ref_set_non_owning(env, &callee->regs[BPF_REG_1]);
        mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root);
        ref_set_non_owning(env, &callee->regs[BPF_REG_2]);

        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
        callee->in_callback_fn = true;
        callee->callback_ret_range = retval_range(0, 1);
        return 0;
}

static int set_task_work_schedule_callback_state(struct bpf_verifier_env *env,
                                                 struct bpf_func_state *caller,
                                                 struct bpf_func_state *callee,
                                                 int insn_idx)
{
        struct bpf_map *map_ptr = caller->regs[BPF_REG_3].map_ptr;

        /*
         * callback_fn(struct bpf_map *map, void *key, void *value);
         */
        callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
        __mark_reg_known_zero(&callee->regs[BPF_REG_1]);
        callee->regs[BPF_REG_1].map_ptr = map_ptr;

        callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
        __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
        callee->regs[BPF_REG_2].map_ptr = map_ptr;

        callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
        __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
        callee->regs[BPF_REG_3].map_ptr = map_ptr;

        /* unused */
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
        bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
        callee->in_async_callback_fn = true;
        callee->callback_ret_range = retval_range(S32_MIN, S32_MAX);
        return 0;
}

static bool is_rbtree_lock_required_kfunc(u32 btf_id);

/* Are we currently verifying the callback for a rbtree helper that must
 * be called with lock held? If so, no need to complain about unreleased
 * lock
 */
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env)
{
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_insn *insn = env->prog->insnsi;
        struct bpf_func_state *callee;
        int kfunc_btf_id;

        if (!state->curframe)
                return false;

        callee = state->frame[state->curframe];

        if (!callee->in_callback_fn)
                return false;

        kfunc_btf_id = insn[callee->callsite].imm;
        return is_rbtree_lock_required_kfunc(kfunc_btf_id);
}

static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg)
{
        if (range.return_32bit)
                return range.minval <= reg->s32_min_value && reg->s32_max_value <= range.maxval;
        else
                return range.minval <= reg->smin_value && reg->smax_value <= range.maxval;
}

static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
        struct bpf_verifier_state *state = env->cur_state, *prev_st;
        struct bpf_func_state *caller, *callee;
        struct bpf_reg_state *r0;
        bool in_callback_fn;
        int err;

        callee = state->frame[state->curframe];
        r0 = &callee->regs[BPF_REG_0];
        if (r0->type == PTR_TO_STACK) {
                /* technically it's ok to return caller's stack pointer
                 * (or caller's caller's pointer) back to the caller,
                 * since these pointers are valid. Only current stack
                 * pointer will be invalid as soon as function exits,
                 * but let's be conservative
                 */
                verbose(env, "cannot return stack pointer to the caller\n");
                return -EINVAL;
        }

        caller = state->frame[state->curframe - 1];
        if (callee->in_callback_fn) {
                if (r0->type != SCALAR_VALUE) {
                        verbose(env, "R0 not a scalar value\n");
                        return -EACCES;
                }

                /* we are going to rely on register's precise value */
                err = mark_chain_precision(env, BPF_REG_0);
                if (err)
                        return err;

                /* enforce R0 return value range, and bpf_callback_t returns 64bit */
                if (!retval_range_within(callee->callback_ret_range, r0)) {
                        verbose_invalid_scalar(env, r0, callee->callback_ret_range,
                                               "At callback return", "R0");
                        return -EINVAL;
                }
                if (!bpf_calls_callback(env, callee->callsite)) {
                        verifier_bug(env, "in callback at %d, callsite %d !calls_callback",
                                     *insn_idx, callee->callsite);
                        return -EFAULT;
                }
        } else {
                /* return to the caller whatever r0 had in the callee */
                caller->regs[BPF_REG_0] = *r0;
        }

        /* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite,
         * there function call logic would reschedule callback visit. If iteration
         * converges is_state_visited() would prune that visit eventually.
         */
        in_callback_fn = callee->in_callback_fn;
        if (in_callback_fn)
                *insn_idx = callee->callsite;
        else
                *insn_idx = callee->callsite + 1;

        if (env->log.level & BPF_LOG_LEVEL) {
                verbose(env, "returning from callee:\n");
                print_verifier_state(env, state, callee->frameno, true);
                verbose(env, "to caller at %d:\n", *insn_idx);
                print_verifier_state(env, state, caller->frameno, true);
        }
        /* clear everything in the callee. In case of exceptional exits using
         * bpf_throw, this will be done by copy_verifier_state for extra frames. */
        free_func_state(callee);
        state->frame[state->curframe--] = NULL;

        /* for callbacks widen imprecise scalars to make programs like below verify:
         *
         *   struct ctx { int i; }
         *   void cb(int idx, struct ctx *ctx) { ctx->i++; ... }
         *   ...
         *   struct ctx = { .i = 0; }
         *   bpf_loop(100, cb, &ctx, 0);
         *
         * This is similar to what is done in process_iter_next_call() for open
         * coded iterators.
         */
        prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL;
        if (prev_st) {
                err = widen_imprecise_scalars(env, prev_st, state);
                if (err)
                        return err;
        }
        return 0;
}

static int do_refine_retval_range(struct bpf_verifier_env *env,
                                  struct bpf_reg_state *regs, int ret_type,
                                  int func_id,
                                  struct bpf_call_arg_meta *meta)
{
        struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];

        if (ret_type != RET_INTEGER)
                return 0;

        switch (func_id) {
        case BPF_FUNC_get_stack:
        case BPF_FUNC_get_task_stack:
        case BPF_FUNC_probe_read_str:
        case BPF_FUNC_probe_read_kernel_str:
        case BPF_FUNC_probe_read_user_str:
                ret_reg->smax_value = meta->msize_max_value;
                ret_reg->s32_max_value = meta->msize_max_value;
                ret_reg->smin_value = -MAX_ERRNO;
                ret_reg->s32_min_value = -MAX_ERRNO;
                reg_bounds_sync(ret_reg);
                break;
        case BPF_FUNC_get_smp_processor_id:
                ret_reg->umax_value = nr_cpu_ids - 1;
                ret_reg->u32_max_value = nr_cpu_ids - 1;
                ret_reg->smax_value = nr_cpu_ids - 1;
                ret_reg->s32_max_value = nr_cpu_ids - 1;
                ret_reg->umin_value = 0;
                ret_reg->u32_min_value = 0;
                ret_reg->smin_value = 0;
                ret_reg->s32_min_value = 0;
                reg_bounds_sync(ret_reg);
                break;
        }

        return reg_bounds_sanity_check(env, ret_reg, "retval");
}

static int
record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
                int func_id, int insn_idx)
{
        struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
        struct bpf_map *map = meta->map.ptr;

        if (func_id != BPF_FUNC_tail_call &&
            func_id != BPF_FUNC_map_lookup_elem &&
            func_id != BPF_FUNC_map_update_elem &&
            func_id != BPF_FUNC_map_delete_elem &&
            func_id != BPF_FUNC_map_push_elem &&
            func_id != BPF_FUNC_map_pop_elem &&
            func_id != BPF_FUNC_map_peek_elem &&
            func_id != BPF_FUNC_for_each_map_elem &&
            func_id != BPF_FUNC_redirect_map &&
            func_id != BPF_FUNC_map_lookup_percpu_elem)
                return 0;

        if (map == NULL) {
                verifier_bug(env, "expected map for helper call");
                return -EFAULT;
        }

        /* In case of read-only, some additional restrictions
         * need to be applied in order to prevent altering the
         * state of the map from program side.
         */
        if ((map->map_flags & BPF_F_RDONLY_PROG) &&
            (func_id == BPF_FUNC_map_delete_elem ||
             func_id == BPF_FUNC_map_update_elem ||
             func_id == BPF_FUNC_map_push_elem ||
             func_id == BPF_FUNC_map_pop_elem)) {
                verbose(env, "write into map forbidden\n");
                return -EACCES;
        }

        if (!aux->map_ptr_state.map_ptr)
                bpf_map_ptr_store(aux, meta->map.ptr,
                                  !meta->map.ptr->bypass_spec_v1, false);
        else if (aux->map_ptr_state.map_ptr != meta->map.ptr)
                bpf_map_ptr_store(aux, meta->map.ptr,
                                  !meta->map.ptr->bypass_spec_v1, true);
        return 0;
}

static int
record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
                int func_id, int insn_idx)
{
        struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
        struct bpf_reg_state *reg;
        struct bpf_map *map = meta->map.ptr;
        u64 val, max;
        int err;

        if (func_id != BPF_FUNC_tail_call)
                return 0;
        if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
                verbose(env, "expected prog array map for tail call");
                return -EINVAL;
        }

        reg = reg_state(env, BPF_REG_3);
        val = reg->var_off.value;
        max = map->max_entries;

        if (!(is_reg_const(reg, false) && val < max)) {
                bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
                return 0;
        }

        err = mark_chain_precision(env, BPF_REG_3);
        if (err)
                return err;
        if (bpf_map_key_unseen(aux))
                bpf_map_key_store(aux, val);
        else if (!bpf_map_key_poisoned(aux) &&
                  bpf_map_key_immediate(aux) != val)
                bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
        return 0;
}

static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit)
{
        struct bpf_verifier_state *state = env->cur_state;
        enum bpf_prog_type type = resolve_prog_type(env->prog);
        struct bpf_reg_state *reg = reg_state(env, BPF_REG_0);
        bool refs_lingering = false;
        int i;

        if (!exception_exit && cur_func(env)->frameno)
                return 0;

        for (i = 0; i < state->acquired_refs; i++) {
                if (state->refs[i].type != REF_TYPE_PTR)
                        continue;
                /* Allow struct_ops programs to return a referenced kptr back to
                 * kernel. Type checks are performed later in check_return_code.
                 */
                if (type == BPF_PROG_TYPE_STRUCT_OPS && !exception_exit &&
                    reg->ref_obj_id == state->refs[i].id)
                        continue;
                verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
                        state->refs[i].id, state->refs[i].insn_idx);
                refs_lingering = true;
        }
        return refs_lingering ? -EINVAL : 0;
}

static int check_resource_leak(struct bpf_verifier_env *env, bool exception_exit, bool check_lock, const char *prefix)
{
        int err;

        if (check_lock && env->cur_state->active_locks) {
                verbose(env, "%s cannot be used inside bpf_spin_lock-ed region\n", prefix);
                return -EINVAL;
        }

        err = check_reference_leak(env, exception_exit);
        if (err) {
                verbose(env, "%s would lead to reference leak\n", prefix);
                return err;
        }

        if (check_lock && env->cur_state->active_irq_id) {
                verbose(env, "%s cannot be used inside bpf_local_irq_save-ed region\n", prefix);
                return -EINVAL;
        }

        if (check_lock && env->cur_state->active_rcu_locks) {
                verbose(env, "%s cannot be used inside bpf_rcu_read_lock-ed region\n", prefix);
                return -EINVAL;
        }

        if (check_lock && env->cur_state->active_preempt_locks) {
                verbose(env, "%s cannot be used inside bpf_preempt_disable-ed region\n", prefix);
                return -EINVAL;
        }

        return 0;
}

static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *regs)
{
        struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
        struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
        struct bpf_map *fmt_map = fmt_reg->map_ptr;
        struct bpf_bprintf_data data = {};
        int err, fmt_map_off, num_args;
        u64 fmt_addr;
        char *fmt;

        /* data must be an array of u64 */
        if (data_len_reg->var_off.value % 8)
                return -EINVAL;
        num_args = data_len_reg->var_off.value / 8;

        /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
         * and map_direct_value_addr is set.
         */
        fmt_map_off = fmt_reg->var_off.value;
        err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
                                                  fmt_map_off);
        if (err) {
                verbose(env, "failed to retrieve map value address\n");
                return -EFAULT;
        }
        fmt = (char *)(long)fmt_addr + fmt_map_off;

        /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
         * can focus on validating the format specifiers.
         */
        err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data);
        if (err < 0)
                verbose(env, "Invalid format string\n");

        return err;
}

static int check_get_func_ip(struct bpf_verifier_env *env)
{
        enum bpf_prog_type type = resolve_prog_type(env->prog);
        int func_id = BPF_FUNC_get_func_ip;

        if (type == BPF_PROG_TYPE_TRACING) {
                if (!bpf_prog_has_trampoline(env->prog)) {
                        verbose(env, "func %s#%d supported only for fentry/fexit/fsession/fmod_ret programs\n",
                                func_id_name(func_id), func_id);
                        return -ENOTSUPP;
                }
                return 0;
        } else if (type == BPF_PROG_TYPE_KPROBE) {
                return 0;
        }

        verbose(env, "func %s#%d not supported for program type %d\n",
                func_id_name(func_id), func_id, type);
        return -ENOTSUPP;
}

static struct bpf_insn_aux_data *cur_aux(const struct bpf_verifier_env *env)
{
        return &env->insn_aux_data[env->insn_idx];
}

static bool loop_flag_is_zero(struct bpf_verifier_env *env)
{
        struct bpf_reg_state *reg = reg_state(env, BPF_REG_4);
        bool reg_is_null = bpf_register_is_null(reg);

        if (reg_is_null)
                mark_chain_precision(env, BPF_REG_4);

        return reg_is_null;
}

static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno)
{
        struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state;

        if (!state->initialized) {
                state->initialized = 1;
                state->fit_for_inline = loop_flag_is_zero(env);
                state->callback_subprogno = subprogno;
                return;
        }

        if (!state->fit_for_inline)
                return;

        state->fit_for_inline = (loop_flag_is_zero(env) &&
                                 state->callback_subprogno == subprogno);
}

/* Returns whether or not the given map type can potentially elide
 * lookup return value nullness check. This is possible if the key
 * is statically known.
 */
static bool can_elide_value_nullness(enum bpf_map_type type)
{
        switch (type) {
        case BPF_MAP_TYPE_ARRAY:
        case BPF_MAP_TYPE_PERCPU_ARRAY:
                return true;
        default:
                return false;
        }
}

int bpf_get_helper_proto(struct bpf_verifier_env *env, int func_id,
                         const struct bpf_func_proto **ptr)
{
        if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID)
                return -ERANGE;

        if (!env->ops->get_func_proto)
                return -EINVAL;

        *ptr = env->ops->get_func_proto(func_id, env->prog);
        return *ptr && (*ptr)->func ? 0 : -EINVAL;
}

/* Check if we're in a sleepable context. */
static inline bool in_sleepable_context(struct bpf_verifier_env *env)
{
        return !env->cur_state->active_rcu_locks &&
               !env->cur_state->active_preempt_locks &&
               !env->cur_state->active_locks &&
               !env->cur_state->active_irq_id &&
               in_sleepable(env);
}

static const char *non_sleepable_context_description(struct bpf_verifier_env *env)
{
        if (env->cur_state->active_rcu_locks)
                return "rcu_read_lock region";
        if (env->cur_state->active_preempt_locks)
                return "non-preemptible region";
        if (env->cur_state->active_irq_id)
                return "IRQ-disabled region";
        if (env->cur_state->active_locks)
                return "lock region";
        return "non-sleepable prog";
}

static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                             int *insn_idx_p)
{
        enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
        bool returns_cpu_specific_alloc_ptr = false;
        const struct bpf_func_proto *fn = NULL;
        enum bpf_return_type ret_type;
        enum bpf_type_flag ret_flag;
        struct bpf_reg_state *regs;
        struct bpf_call_arg_meta meta;
        int insn_idx = *insn_idx_p;
        bool changes_data;
        int i, err, func_id;

        /* find function prototype */
        func_id = insn->imm;
        err = bpf_get_helper_proto(env, insn->imm, &fn);
        if (err == -ERANGE) {
                verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id);
                return -EINVAL;
        }

        if (err) {
                verbose(env, "program of this type cannot use helper %s#%d\n",
                        func_id_name(func_id), func_id);
                return err;
        }

        /* eBPF programs must be GPL compatible to use GPL-ed functions */
        if (!env->prog->gpl_compatible && fn->gpl_only) {
                verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
                return -EINVAL;
        }

        if (fn->allowed && !fn->allowed(env->prog)) {
                verbose(env, "helper call is not allowed in probe\n");
                return -EINVAL;
        }

        /* With LD_ABS/IND some JITs save/restore skb from r1. */
        changes_data = bpf_helper_changes_pkt_data(func_id);
        if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
                verifier_bug(env, "func %s#%d: r1 != ctx", func_id_name(func_id), func_id);
                return -EFAULT;
        }

        memset(&meta, 0, sizeof(meta));
        meta.pkt_access = fn->pkt_access;

        err = check_func_proto(fn);
        if (err) {
                verifier_bug(env, "incorrect func proto %s#%d", func_id_name(func_id), func_id);
                return err;
        }

        if (fn->might_sleep && !in_sleepable_context(env)) {
                verbose(env, "sleepable helper %s#%d in %s\n", func_id_name(func_id), func_id,
                        non_sleepable_context_description(env));
                return -EINVAL;
        }

        /* Track non-sleepable context for helpers. */
        if (!in_sleepable_context(env))
                env->insn_aux_data[insn_idx].non_sleepable = true;

        meta.func_id = func_id;
        /* check args */
        for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
                err = check_func_arg(env, i, &meta, fn, insn_idx);
                if (err)
                        return err;
        }

        err = record_func_map(env, &meta, func_id, insn_idx);
        if (err)
                return err;

        err = record_func_key(env, &meta, func_id, insn_idx);
        if (err)
                return err;

        /* Mark slots with STACK_MISC in case of raw mode, stack offset
         * is inferred from register state.
         */
        for (i = 0; i < meta.access_size; i++) {
                err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
                                       BPF_WRITE, -1, false, false);
                if (err)
                        return err;
        }

        regs = cur_regs(env);

        if (meta.release_regno) {
                err = -EINVAL;
                if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) {
                        err = unmark_stack_slots_dynptr(env, &regs[meta.release_regno]);
                } else if (func_id == BPF_FUNC_kptr_xchg && meta.ref_obj_id) {
                        u32 ref_obj_id = meta.ref_obj_id;
                        bool in_rcu = in_rcu_cs(env);
                        struct bpf_func_state *state;
                        struct bpf_reg_state *reg;

                        err = release_reference_nomark(env->cur_state, ref_obj_id);
                        if (!err) {
                                bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
                                        if (reg->ref_obj_id == ref_obj_id) {
                                                if (in_rcu && (reg->type & MEM_ALLOC) && (reg->type & MEM_PERCPU)) {
                                                        reg->ref_obj_id = 0;
                                                        reg->type &= ~MEM_ALLOC;
                                                        reg->type |= MEM_RCU;
                                                } else {
                                                        mark_reg_invalid(env, reg);
                                                }
                                        }
                                }));
                        }
                } else if (meta.ref_obj_id) {
                        err = release_reference(env, meta.ref_obj_id);
                } else if (bpf_register_is_null(&regs[meta.release_regno])) {
                        /* meta.ref_obj_id can only be 0 if register that is meant to be
                         * released is NULL, which must be > R0.
                         */
                        err = 0;
                }
                if (err) {
                        verbose(env, "func %s#%d reference has not been acquired before\n",
                                func_id_name(func_id), func_id);
                        return err;
                }
        }

        switch (func_id) {
        case BPF_FUNC_tail_call:
                err = check_resource_leak(env, false, true, "tail_call");
                if (err)
                        return err;
                break;
        case BPF_FUNC_get_local_storage:
                /* check that flags argument in get_local_storage(map, flags) is 0,
                 * this is required because get_local_storage() can't return an error.
                 */
                if (!bpf_register_is_null(&regs[BPF_REG_2])) {
                        verbose(env, "get_local_storage() doesn't support non-zero flags\n");
                        return -EINVAL;
                }
                break;
        case BPF_FUNC_for_each_map_elem:
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_map_elem_callback_state);
                break;
        case BPF_FUNC_timer_set_callback:
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_timer_callback_state);
                break;
        case BPF_FUNC_find_vma:
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_find_vma_callback_state);
                break;
        case BPF_FUNC_snprintf:
                err = check_bpf_snprintf_call(env, regs);
                break;
        case BPF_FUNC_loop:
                update_loop_inline_state(env, meta.subprogno);
                /* Verifier relies on R1 value to determine if bpf_loop() iteration
                 * is finished, thus mark it precise.
                 */
                err = mark_chain_precision(env, BPF_REG_1);
                if (err)
                        return err;
                if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) {
                        err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                                 set_loop_callback_state);
                } else {
                        cur_func(env)->callback_depth = 0;
                        if (env->log.level & BPF_LOG_LEVEL2)
                                verbose(env, "frame%d bpf_loop iteration limit reached\n",
                                        env->cur_state->curframe);
                }
                break;
        case BPF_FUNC_dynptr_from_mem:
                if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) {
                        verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n",
                                reg_type_str(env, regs[BPF_REG_1].type));
                        return -EACCES;
                }
                break;
        case BPF_FUNC_set_retval:
                if (prog_type == BPF_PROG_TYPE_LSM &&
                    env->prog->expected_attach_type == BPF_LSM_CGROUP) {
                        if (!env->prog->aux->attach_func_proto->type) {
                                /* Make sure programs that attach to void
                                 * hooks don't try to modify return value.
                                 */
                                verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
                                return -EINVAL;
                        }
                }
                break;
        case BPF_FUNC_dynptr_data:
        {
                struct bpf_reg_state *reg;
                int id, ref_obj_id;

                reg = get_dynptr_arg_reg(env, fn, regs);
                if (!reg)
                        return -EFAULT;


                if (meta.dynptr_id) {
                        verifier_bug(env, "meta.dynptr_id already set");
                        return -EFAULT;
                }
                if (meta.ref_obj_id) {
                        verifier_bug(env, "meta.ref_obj_id already set");
                        return -EFAULT;
                }

                id = dynptr_id(env, reg);
                if (id < 0) {
                        verifier_bug(env, "failed to obtain dynptr id");
                        return id;
                }

                ref_obj_id = dynptr_ref_obj_id(env, reg);
                if (ref_obj_id < 0) {
                        verifier_bug(env, "failed to obtain dynptr ref_obj_id");
                        return ref_obj_id;
                }

                meta.dynptr_id = id;
                meta.ref_obj_id = ref_obj_id;

                break;
        }
        case BPF_FUNC_dynptr_write:
        {
                enum bpf_dynptr_type dynptr_type;
                struct bpf_reg_state *reg;

                reg = get_dynptr_arg_reg(env, fn, regs);
                if (!reg)
                        return -EFAULT;

                dynptr_type = dynptr_get_type(env, reg);
                if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
                        return -EFAULT;

                if (dynptr_type == BPF_DYNPTR_TYPE_SKB ||
                    dynptr_type == BPF_DYNPTR_TYPE_SKB_META)
                        /* this will trigger clear_all_pkt_pointers(), which will
                         * invalidate all dynptr slices associated with the skb
                         */
                        changes_data = true;

                break;
        }
        case BPF_FUNC_per_cpu_ptr:
        case BPF_FUNC_this_cpu_ptr:
        {
                struct bpf_reg_state *reg = &regs[BPF_REG_1];
                const struct btf_type *type;

                if (reg->type & MEM_RCU) {
                        type = btf_type_by_id(reg->btf, reg->btf_id);
                        if (!type || !btf_type_is_struct(type)) {
                                verbose(env, "Helper has invalid btf/btf_id in R1\n");
                                return -EFAULT;
                        }
                        returns_cpu_specific_alloc_ptr = true;
                        env->insn_aux_data[insn_idx].call_with_percpu_alloc_ptr = true;
                }
                break;
        }
        case BPF_FUNC_user_ringbuf_drain:
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_user_ringbuf_callback_state);
                break;
        }

        if (err)
                return err;

        /* reset caller saved regs */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                bpf_mark_reg_not_init(env, &regs[caller_saved[i]]);
                check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
        }

        /* helper call returns 64-bit value. */
        regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;

        /* update return register (already marked as written above) */
        ret_type = fn->ret_type;
        ret_flag = type_flag(ret_type);

        switch (base_type(ret_type)) {
        case RET_INTEGER:
                /* sets type to SCALAR_VALUE */
                mark_reg_unknown(env, regs, BPF_REG_0);
                break;
        case RET_VOID:
                regs[BPF_REG_0].type = NOT_INIT;
                break;
        case RET_PTR_TO_MAP_VALUE:
                /* There is no offset yet applied, variable or fixed */
                mark_reg_known_zero(env, regs, BPF_REG_0);
                /* remember map_ptr, so that check_map_access()
                 * can check 'value_size' boundary of memory access
                 * to map element returned from bpf_map_lookup_elem()
                 */
                if (meta.map.ptr == NULL) {
                        verifier_bug(env, "unexpected null map_ptr");
                        return -EFAULT;
                }

                if (func_id == BPF_FUNC_map_lookup_elem &&
                    can_elide_value_nullness(meta.map.ptr->map_type) &&
                    meta.const_map_key >= 0 &&
                    meta.const_map_key < meta.map.ptr->max_entries)
                        ret_flag &= ~PTR_MAYBE_NULL;

                regs[BPF_REG_0].map_ptr = meta.map.ptr;
                regs[BPF_REG_0].map_uid = meta.map.uid;
                regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
                if (!type_may_be_null(ret_flag) &&
                    btf_record_has_field(meta.map.ptr->record, BPF_SPIN_LOCK | BPF_RES_SPIN_LOCK)) {
                        regs[BPF_REG_0].id = ++env->id_gen;
                }
                break;
        case RET_PTR_TO_SOCKET:
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
                break;
        case RET_PTR_TO_SOCK_COMMON:
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
                break;
        case RET_PTR_TO_TCP_SOCK:
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
                break;
        case RET_PTR_TO_MEM:
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
                regs[BPF_REG_0].mem_size = meta.mem_size;
                break;
        case RET_PTR_TO_MEM_OR_BTF_ID:
        {
                const struct btf_type *t;

                mark_reg_known_zero(env, regs, BPF_REG_0);
                t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL);
                if (!btf_type_is_struct(t)) {
                        u32 tsize;
                        const struct btf_type *ret;
                        const char *tname;

                        /* resolve the type size of ksym. */
                        ret = btf_resolve_size(meta.ret_btf, t, &tsize);
                        if (IS_ERR(ret)) {
                                tname = btf_name_by_offset(meta.ret_btf, t->name_off);
                                verbose(env, "unable to resolve the size of type '%s': %ld\n",
                                        tname, PTR_ERR(ret));
                                return -EINVAL;
                        }
                        regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
                        regs[BPF_REG_0].mem_size = tsize;
                } else {
                        if (returns_cpu_specific_alloc_ptr) {
                                regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC | MEM_RCU;
                        } else {
                                /* MEM_RDONLY may be carried from ret_flag, but it
                                 * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
                                 * it will confuse the check of PTR_TO_BTF_ID in
                                 * check_mem_access().
                                 */
                                ret_flag &= ~MEM_RDONLY;
                                regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
                        }

                        regs[BPF_REG_0].btf = meta.ret_btf;
                        regs[BPF_REG_0].btf_id = meta.ret_btf_id;
                }
                break;
        }
        case RET_PTR_TO_BTF_ID:
        {
                struct btf *ret_btf;
                int ret_btf_id;

                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
                if (func_id == BPF_FUNC_kptr_xchg) {
                        ret_btf = meta.kptr_field->kptr.btf;
                        ret_btf_id = meta.kptr_field->kptr.btf_id;
                        if (!btf_is_kernel(ret_btf)) {
                                regs[BPF_REG_0].type |= MEM_ALLOC;
                                if (meta.kptr_field->type == BPF_KPTR_PERCPU)
                                        regs[BPF_REG_0].type |= MEM_PERCPU;
                        }
                } else {
                        if (fn->ret_btf_id == BPF_PTR_POISON) {
                                verifier_bug(env, "func %s has non-overwritten BPF_PTR_POISON return type",
                                             func_id_name(func_id));
                                return -EFAULT;
                        }
                        ret_btf = btf_vmlinux;
                        ret_btf_id = *fn->ret_btf_id;
                }
                if (ret_btf_id == 0) {
                        verbose(env, "invalid return type %u of func %s#%d\n",
                                base_type(ret_type), func_id_name(func_id),
                                func_id);
                        return -EINVAL;
                }
                regs[BPF_REG_0].btf = ret_btf;
                regs[BPF_REG_0].btf_id = ret_btf_id;
                break;
        }
        default:
                verbose(env, "unknown return type %u of func %s#%d\n",
                        base_type(ret_type), func_id_name(func_id), func_id);
                return -EINVAL;
        }

        if (type_may_be_null(regs[BPF_REG_0].type))
                regs[BPF_REG_0].id = ++env->id_gen;

        if (helper_multiple_ref_obj_use(func_id, meta.map.ptr)) {
                verifier_bug(env, "func %s#%d sets ref_obj_id more than once",
                             func_id_name(func_id), func_id);
                return -EFAULT;
        }

        if (is_dynptr_ref_function(func_id))
                regs[BPF_REG_0].dynptr_id = meta.dynptr_id;

        if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) {
                /* For release_reference() */
                regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
        } else if (is_acquire_function(func_id, meta.map.ptr)) {
                int id = acquire_reference(env, insn_idx);

                if (id < 0)
                        return id;
                /* For mark_ptr_or_null_reg() */
                regs[BPF_REG_0].id = id;
                /* For release_reference() */
                regs[BPF_REG_0].ref_obj_id = id;
        }

        err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
        if (err)
                return err;

        err = check_map_func_compatibility(env, meta.map.ptr, func_id);
        if (err)
                return err;

        if ((func_id == BPF_FUNC_get_stack ||
             func_id == BPF_FUNC_get_task_stack) &&
            !env->prog->has_callchain_buf) {
                const char *err_str;

#ifdef CONFIG_PERF_EVENTS
                err = get_callchain_buffers(sysctl_perf_event_max_stack);
                err_str = "cannot get callchain buffer for func %s#%d\n";
#else
                err = -ENOTSUPP;
                err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
#endif
                if (err) {
                        verbose(env, err_str, func_id_name(func_id), func_id);
                        return err;
                }

                env->prog->has_callchain_buf = true;
        }

        if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
                env->prog->call_get_stack = true;

        if (func_id == BPF_FUNC_get_func_ip) {
                if (check_get_func_ip(env))
                        return -ENOTSUPP;
                env->prog->call_get_func_ip = true;
        }

        if (func_id == BPF_FUNC_tail_call) {
                if (env->cur_state->curframe) {
                        struct bpf_verifier_state *branch;

                        mark_reg_scratched(env, BPF_REG_0);
                        branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
                        if (IS_ERR(branch))
                                return PTR_ERR(branch);
                        clear_all_pkt_pointers(env);
                        mark_reg_unknown(env, regs, BPF_REG_0);
                        err = prepare_func_exit(env, &env->insn_idx);
                        if (err)
                                return err;
                        env->insn_idx--;
                } else {
                        changes_data = false;
                }
        }

        if (changes_data)
                clear_all_pkt_pointers(env);
        return 0;
}

/* mark_btf_func_reg_size() is used when the reg size is determined by
 * the BTF func_proto's return value size and argument.
 */
static void __mark_btf_func_reg_size(struct bpf_verifier_env *env, struct bpf_reg_state *regs,
                                     u32 regno, size_t reg_size)
{
        struct bpf_reg_state *reg = &regs[regno];

        if (regno == BPF_REG_0) {
                /* Function return value */
                reg->subreg_def = reg_size == sizeof(u64) ?
                        DEF_NOT_SUBREG : env->insn_idx + 1;
        } else if (reg_size == sizeof(u64)) {
                /* Function argument */
                mark_insn_zext(env, reg);
        }
}

static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno,
                                   size_t reg_size)
{
        return __mark_btf_func_reg_size(env, cur_regs(env), regno, reg_size);
}

static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_ACQUIRE;
}

static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_RELEASE;
}


static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_DESTRUCTIVE;
}

static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_RCU;
}

static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->kfunc_flags & KF_RCU_PROTECTED;
}

static bool is_kfunc_arg_mem_size(const struct btf *btf,
                                  const struct btf_param *arg,
                                  const struct bpf_reg_state *reg)
{
        const struct btf_type *t;

        t = btf_type_skip_modifiers(btf, arg->type, NULL);
        if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
                return false;

        return btf_param_match_suffix(btf, arg, "__sz");
}

static bool is_kfunc_arg_const_mem_size(const struct btf *btf,
                                        const struct btf_param *arg,
                                        const struct bpf_reg_state *reg)
{
        const struct btf_type *t;

        t = btf_type_skip_modifiers(btf, arg->type, NULL);
        if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
                return false;

        return btf_param_match_suffix(btf, arg, "__szk");
}

static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__k");
}

static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__ign");
}

static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__map");
}

static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__alloc");
}

static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__uninit");
}

static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__refcounted_kptr");
}

static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__nullable");
}

static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__str");
}

static bool is_kfunc_arg_irq_flag(const struct btf *btf, const struct btf_param *arg)
{
        return btf_param_match_suffix(btf, arg, "__irq_flag");
}

static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
                                          const struct btf_param *arg,
                                          const char *name)
{
        int len, target_len = strlen(name);
        const char *param_name;

        param_name = btf_name_by_offset(btf, arg->name_off);
        if (str_is_empty(param_name))
                return false;
        len = strlen(param_name);
        if (len != target_len)
                return false;
        if (strcmp(param_name, name))
                return false;

        return true;
}

enum {
        KF_ARG_DYNPTR_ID,
        KF_ARG_LIST_HEAD_ID,
        KF_ARG_LIST_NODE_ID,
        KF_ARG_RB_ROOT_ID,
        KF_ARG_RB_NODE_ID,
        KF_ARG_WORKQUEUE_ID,
        KF_ARG_RES_SPIN_LOCK_ID,
        KF_ARG_TASK_WORK_ID,
        KF_ARG_PROG_AUX_ID,
        KF_ARG_TIMER_ID
};

BTF_ID_LIST(kf_arg_btf_ids)
BTF_ID(struct, bpf_dynptr)
BTF_ID(struct, bpf_list_head)
BTF_ID(struct, bpf_list_node)
BTF_ID(struct, bpf_rb_root)
BTF_ID(struct, bpf_rb_node)
BTF_ID(struct, bpf_wq)
BTF_ID(struct, bpf_res_spin_lock)
BTF_ID(struct, bpf_task_work)
BTF_ID(struct, bpf_prog_aux)
BTF_ID(struct, bpf_timer)

static bool __is_kfunc_ptr_arg_type(const struct btf *btf,
                                    const struct btf_param *arg, int type)
{
        const struct btf_type *t;
        u32 res_id;

        t = btf_type_skip_modifiers(btf, arg->type, NULL);
        if (!t)
                return false;
        if (!btf_type_is_ptr(t))
                return false;
        t = btf_type_skip_modifiers(btf, t->type, &res_id);
        if (!t)
                return false;
        return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]);
}

static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID);
}

static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID);
}

static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID);
}

static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID);
}

static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID);
}

static bool is_kfunc_arg_timer(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TIMER_ID);
}

static bool is_kfunc_arg_wq(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_WORKQUEUE_ID);
}

static bool is_kfunc_arg_task_work(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TASK_WORK_ID);
}

static bool is_kfunc_arg_res_spin_lock(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RES_SPIN_LOCK_ID);
}

static bool is_rbtree_node_type(const struct btf_type *t)
{
        return t == btf_type_by_id(btf_vmlinux, kf_arg_btf_ids[KF_ARG_RB_NODE_ID]);
}

static bool is_list_node_type(const struct btf_type *t)
{
        return t == btf_type_by_id(btf_vmlinux, kf_arg_btf_ids[KF_ARG_LIST_NODE_ID]);
}

static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf,
                                  const struct btf_param *arg)
{
        const struct btf_type *t;

        t = btf_type_resolve_func_ptr(btf, arg->type, NULL);
        if (!t)
                return false;

        return true;
}

static bool is_kfunc_arg_prog_aux(const struct btf *btf, const struct btf_param *arg)
{
        return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_PROG_AUX_ID);
}

/*
 * A kfunc with KF_IMPLICIT_ARGS has two prototypes in BTF:
 *   - the _impl prototype with full arg list (meta->func_proto)
 *   - the BPF API prototype w/o implicit args (func->type in BTF)
 * To determine whether an argument is implicit, we compare its position
 * against the number of arguments in the prototype w/o implicit args.
 */
static bool is_kfunc_arg_implicit(const struct bpf_kfunc_call_arg_meta *meta, u32 arg_idx)
{
        const struct btf_type *func, *func_proto;
        u32 argn;

        if (!(meta->kfunc_flags & KF_IMPLICIT_ARGS))
                return false;

        func = btf_type_by_id(meta->btf, meta->func_id);
        func_proto = btf_type_by_id(meta->btf, func->type);
        argn = btf_type_vlen(func_proto);

        return argn <= arg_idx;
}

/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env,
                                        const struct btf *btf,
                                        const struct btf_type *t, int rec)
{
        const struct btf_type *member_type;
        const struct btf_member *member;
        u32 i;

        if (!btf_type_is_struct(t))
                return false;

        for_each_member(i, t, member) {
                const struct btf_array *array;

                member_type = btf_type_skip_modifiers(btf, member->type, NULL);
                if (btf_type_is_struct(member_type)) {
                        if (rec >= 3) {
                                verbose(env, "max struct nesting depth exceeded\n");
                                return false;
                        }
                        if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1))
                                return false;
                        continue;
                }
                if (btf_type_is_array(member_type)) {
                        array = btf_array(member_type);
                        if (!array->nelems)
                                return false;
                        member_type = btf_type_skip_modifiers(btf, array->type, NULL);
                        if (!btf_type_is_scalar(member_type))
                                return false;
                        continue;
                }
                if (!btf_type_is_scalar(member_type))
                        return false;
        }
        return true;
}

enum kfunc_ptr_arg_type {
        KF_ARG_PTR_TO_CTX,
        KF_ARG_PTR_TO_ALLOC_BTF_ID,    /* Allocated object */
        KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */
        KF_ARG_PTR_TO_DYNPTR,
        KF_ARG_PTR_TO_ITER,
        KF_ARG_PTR_TO_LIST_HEAD,
        KF_ARG_PTR_TO_LIST_NODE,
        KF_ARG_PTR_TO_BTF_ID,          /* Also covers reg2btf_ids conversions */
        KF_ARG_PTR_TO_MEM,
        KF_ARG_PTR_TO_MEM_SIZE,        /* Size derived from next argument, skip it */
        KF_ARG_PTR_TO_CALLBACK,
        KF_ARG_PTR_TO_RB_ROOT,
        KF_ARG_PTR_TO_RB_NODE,
        KF_ARG_PTR_TO_NULL,
        KF_ARG_PTR_TO_CONST_STR,
        KF_ARG_PTR_TO_MAP,
        KF_ARG_PTR_TO_TIMER,
        KF_ARG_PTR_TO_WORKQUEUE,
        KF_ARG_PTR_TO_IRQ_FLAG,
        KF_ARG_PTR_TO_RES_SPIN_LOCK,
        KF_ARG_PTR_TO_TASK_WORK,
};

enum special_kfunc_type {
        KF_bpf_obj_new_impl,
        KF_bpf_obj_new,
        KF_bpf_obj_drop_impl,
        KF_bpf_obj_drop,
        KF_bpf_refcount_acquire_impl,
        KF_bpf_refcount_acquire,
        KF_bpf_list_push_front_impl,
        KF_bpf_list_push_front,
        KF_bpf_list_push_back_impl,
        KF_bpf_list_push_back,
        KF_bpf_list_pop_front,
        KF_bpf_list_pop_back,
        KF_bpf_list_front,
        KF_bpf_list_back,
        KF_bpf_cast_to_kern_ctx,
        KF_bpf_rdonly_cast,
        KF_bpf_rcu_read_lock,
        KF_bpf_rcu_read_unlock,
        KF_bpf_rbtree_remove,
        KF_bpf_rbtree_add_impl,
        KF_bpf_rbtree_add,
        KF_bpf_rbtree_first,
        KF_bpf_rbtree_root,
        KF_bpf_rbtree_left,
        KF_bpf_rbtree_right,
        KF_bpf_dynptr_from_skb,
        KF_bpf_dynptr_from_xdp,
        KF_bpf_dynptr_from_skb_meta,
        KF_bpf_xdp_pull_data,
        KF_bpf_dynptr_slice,
        KF_bpf_dynptr_slice_rdwr,
        KF_bpf_dynptr_clone,
        KF_bpf_percpu_obj_new_impl,
        KF_bpf_percpu_obj_new,
        KF_bpf_percpu_obj_drop_impl,
        KF_bpf_percpu_obj_drop,
        KF_bpf_throw,
        KF_bpf_wq_set_callback,
        KF_bpf_preempt_disable,
        KF_bpf_preempt_enable,
        KF_bpf_iter_css_task_new,
        KF_bpf_session_cookie,
        KF_bpf_get_kmem_cache,
        KF_bpf_local_irq_save,
        KF_bpf_local_irq_restore,
        KF_bpf_iter_num_new,
        KF_bpf_iter_num_next,
        KF_bpf_iter_num_destroy,
        KF_bpf_set_dentry_xattr,
        KF_bpf_remove_dentry_xattr,
        KF_bpf_res_spin_lock,
        KF_bpf_res_spin_unlock,
        KF_bpf_res_spin_lock_irqsave,
        KF_bpf_res_spin_unlock_irqrestore,
        KF_bpf_dynptr_from_file,
        KF_bpf_dynptr_file_discard,
        KF___bpf_trap,
        KF_bpf_task_work_schedule_signal,
        KF_bpf_task_work_schedule_resume,
        KF_bpf_arena_alloc_pages,
        KF_bpf_arena_free_pages,
        KF_bpf_arena_reserve_pages,
        KF_bpf_session_is_return,
        KF_bpf_stream_vprintk,
        KF_bpf_stream_print_stack,
};

BTF_ID_LIST(special_kfunc_list)
BTF_ID(func, bpf_obj_new_impl)
BTF_ID(func, bpf_obj_new)
BTF_ID(func, bpf_obj_drop_impl)
BTF_ID(func, bpf_obj_drop)
BTF_ID(func, bpf_refcount_acquire_impl)
BTF_ID(func, bpf_refcount_acquire)
BTF_ID(func, bpf_list_push_front_impl)
BTF_ID(func, bpf_list_push_front)
BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_push_back)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_list_front)
BTF_ID(func, bpf_list_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
BTF_ID(func, bpf_rcu_read_lock)
BTF_ID(func, bpf_rcu_read_unlock)
BTF_ID(func, bpf_rbtree_remove)
BTF_ID(func, bpf_rbtree_add_impl)
BTF_ID(func, bpf_rbtree_add)
BTF_ID(func, bpf_rbtree_first)
BTF_ID(func, bpf_rbtree_root)
BTF_ID(func, bpf_rbtree_left)
BTF_ID(func, bpf_rbtree_right)
#ifdef CONFIG_NET
BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_dynptr_from_xdp)
BTF_ID(func, bpf_dynptr_from_skb_meta)
BTF_ID(func, bpf_xdp_pull_data)
#else
BTF_ID_UNUSED
BTF_ID_UNUSED
BTF_ID_UNUSED
BTF_ID_UNUSED
#endif
BTF_ID(func, bpf_dynptr_slice)
BTF_ID(func, bpf_dynptr_slice_rdwr)
BTF_ID(func, bpf_dynptr_clone)
BTF_ID(func, bpf_percpu_obj_new_impl)
BTF_ID(func, bpf_percpu_obj_new)
BTF_ID(func, bpf_percpu_obj_drop_impl)
BTF_ID(func, bpf_percpu_obj_drop)
BTF_ID(func, bpf_throw)
BTF_ID(func, bpf_wq_set_callback)
BTF_ID(func, bpf_preempt_disable)
BTF_ID(func, bpf_preempt_enable)
#ifdef CONFIG_CGROUPS
BTF_ID(func, bpf_iter_css_task_new)
#else
BTF_ID_UNUSED
#endif
#ifdef CONFIG_BPF_EVENTS
BTF_ID(func, bpf_session_cookie)
#else
BTF_ID_UNUSED
#endif
BTF_ID(func, bpf_get_kmem_cache)
BTF_ID(func, bpf_local_irq_save)
BTF_ID(func, bpf_local_irq_restore)
BTF_ID(func, bpf_iter_num_new)
BTF_ID(func, bpf_iter_num_next)
BTF_ID(func, bpf_iter_num_destroy)
#ifdef CONFIG_BPF_LSM
BTF_ID(func, bpf_set_dentry_xattr)
BTF_ID(func, bpf_remove_dentry_xattr)
#else
BTF_ID_UNUSED
BTF_ID_UNUSED
#endif
BTF_ID(func, bpf_res_spin_lock)
BTF_ID(func, bpf_res_spin_unlock)
BTF_ID(func, bpf_res_spin_lock_irqsave)
BTF_ID(func, bpf_res_spin_unlock_irqrestore)
BTF_ID(func, bpf_dynptr_from_file)
BTF_ID(func, bpf_dynptr_file_discard)
BTF_ID(func, __bpf_trap)
BTF_ID(func, bpf_task_work_schedule_signal)
BTF_ID(func, bpf_task_work_schedule_resume)
BTF_ID(func, bpf_arena_alloc_pages)
BTF_ID(func, bpf_arena_free_pages)
BTF_ID(func, bpf_arena_reserve_pages)
BTF_ID(func, bpf_session_is_return)
BTF_ID(func, bpf_stream_vprintk)
BTF_ID(func, bpf_stream_print_stack)

static bool is_bpf_obj_new_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_obj_new] ||
               func_id == special_kfunc_list[KF_bpf_obj_new_impl];
}

static bool is_bpf_percpu_obj_new_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_percpu_obj_new] ||
               func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl];
}

static bool is_bpf_obj_drop_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_obj_drop] ||
               func_id == special_kfunc_list[KF_bpf_obj_drop_impl];
}

static bool is_bpf_percpu_obj_drop_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_percpu_obj_drop] ||
               func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl];
}

static bool is_bpf_refcount_acquire_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_refcount_acquire] ||
               func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl];
}

static bool is_bpf_list_push_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_list_push_front] ||
               func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
               func_id == special_kfunc_list[KF_bpf_list_push_back] ||
               func_id == special_kfunc_list[KF_bpf_list_push_back_impl];
}

static bool is_bpf_rbtree_add_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_rbtree_add] ||
               func_id == special_kfunc_list[KF_bpf_rbtree_add_impl];
}

static bool is_task_work_add_kfunc(u32 func_id)
{
        return func_id == special_kfunc_list[KF_bpf_task_work_schedule_signal] ||
               func_id == special_kfunc_list[KF_bpf_task_work_schedule_resume];
}

static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
{
        if (is_bpf_refcount_acquire_kfunc(meta->func_id) && meta->arg_owning_ref)
                return false;

        return meta->kfunc_flags & KF_RET_NULL;
}

static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock];
}

static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock];
}

static bool is_kfunc_bpf_preempt_disable(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->func_id == special_kfunc_list[KF_bpf_preempt_disable];
}

static bool is_kfunc_bpf_preempt_enable(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->func_id == special_kfunc_list[KF_bpf_preempt_enable];
}

bool bpf_is_kfunc_pkt_changing(struct bpf_kfunc_call_arg_meta *meta)
{
        return meta->func_id == special_kfunc_list[KF_bpf_xdp_pull_data];
}

static enum kfunc_ptr_arg_type
get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
                       struct bpf_kfunc_call_arg_meta *meta,
                       const struct btf_type *t, const struct btf_type *ref_t,
                       const char *ref_tname, const struct btf_param *args,
                       int argno, int nargs)
{
        u32 regno = argno + 1;
        struct bpf_reg_state *regs = cur_regs(env);
        struct bpf_reg_state *reg = &regs[regno];
        bool arg_mem_size = false;

        if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
            meta->func_id == special_kfunc_list[KF_bpf_session_is_return] ||
            meta->func_id == special_kfunc_list[KF_bpf_session_cookie])
                return KF_ARG_PTR_TO_CTX;

        if (argno + 1 < nargs &&
            (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1]) ||
             is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1])))
                arg_mem_size = true;

        /* In this function, we verify the kfunc's BTF as per the argument type,
         * leaving the rest of the verification with respect to the register
         * type to our caller. When a set of conditions hold in the BTF type of
         * arguments, we resolve it to a known kfunc_ptr_arg_type.
         */
        if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
                return KF_ARG_PTR_TO_CTX;

        if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && bpf_register_is_null(reg) &&
            !arg_mem_size)
                return KF_ARG_PTR_TO_NULL;

        if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_ALLOC_BTF_ID;

        if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_REFCOUNTED_KPTR;

        if (is_kfunc_arg_dynptr(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_DYNPTR;

        if (is_kfunc_arg_iter(meta, argno, &args[argno]))
                return KF_ARG_PTR_TO_ITER;

        if (is_kfunc_arg_list_head(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_LIST_HEAD;

        if (is_kfunc_arg_list_node(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_LIST_NODE;

        if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_RB_ROOT;

        if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_RB_NODE;

        if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_CONST_STR;

        if (is_kfunc_arg_map(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_MAP;

        if (is_kfunc_arg_wq(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_WORKQUEUE;

        if (is_kfunc_arg_timer(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_TIMER;

        if (is_kfunc_arg_task_work(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_TASK_WORK;

        if (is_kfunc_arg_irq_flag(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_IRQ_FLAG;

        if (is_kfunc_arg_res_spin_lock(meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_RES_SPIN_LOCK;

        if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
                if (!btf_type_is_struct(ref_t)) {
                        verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
                                meta->func_name, argno, btf_type_str(ref_t), ref_tname);
                        return -EINVAL;
                }
                return KF_ARG_PTR_TO_BTF_ID;
        }

        if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
                return KF_ARG_PTR_TO_CALLBACK;

        /* This is the catch all argument type of register types supported by
         * check_helper_mem_access. However, we only allow when argument type is
         * pointer to scalar, or struct composed (recursively) of scalars. When
         * arg_mem_size is true, the pointer can be void *.
         */
        if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) &&
            (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
                verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
                        argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
                return -EINVAL;
        }
        return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM;
}

static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env,
                                        struct bpf_reg_state *reg,
                                        const struct btf_type *ref_t,
                                        const char *ref_tname, u32 ref_id,
                                        struct bpf_kfunc_call_arg_meta *meta,
                                        int argno)
{
        const struct btf_type *reg_ref_t;
        bool strict_type_match = false;
        const struct btf *reg_btf;
        const char *reg_ref_tname;
        bool taking_projection;
        bool struct_same;
        u32 reg_ref_id;

        if (base_type(reg->type) == PTR_TO_BTF_ID) {
                reg_btf = reg->btf;
                reg_ref_id = reg->btf_id;
        } else {
                reg_btf = btf_vmlinux;
                reg_ref_id = *reg2btf_ids[base_type(reg->type)];
        }

        /* Enforce strict type matching for calls to kfuncs that are acquiring
         * or releasing a reference, or are no-cast aliases. We do _not_
         * enforce strict matching for kfuncs by default,
         * as we want to enable BPF programs to pass types that are bitwise
         * equivalent without forcing them to explicitly cast with something
         * like bpf_cast_to_kern_ctx().
         *
         * For example, say we had a type like the following:
         *
         * struct bpf_cpumask {
         *      cpumask_t cpumask;
         *      refcount_t usage;
         * };
         *
         * Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed
         * to a struct cpumask, so it would be safe to pass a struct
         * bpf_cpumask * to a kfunc expecting a struct cpumask *.
         *
         * The philosophy here is similar to how we allow scalars of different
         * types to be passed to kfuncs as long as the size is the same. The
         * only difference here is that we're simply allowing
         * btf_struct_ids_match() to walk the struct at the 0th offset, and
         * resolve types.
         */
        if ((is_kfunc_release(meta) && reg->ref_obj_id) ||
            btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id))
                strict_type_match = true;

        WARN_ON_ONCE(is_kfunc_release(meta) && !tnum_is_const(reg->var_off));

        reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, &reg_ref_id);
        reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off);
        struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->var_off.value,
                                           meta->btf, ref_id, strict_type_match);
        /* If kfunc is accepting a projection type (ie. __sk_buff), it cannot
         * actually use it -- it must cast to the underlying type. So we allow
         * caller to pass in the underlying type.
         */
        taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname);
        if (!taking_projection && !struct_same) {
                verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
                        meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1,
                        btf_type_str(reg_ref_t), reg_ref_tname);
                return -EINVAL;
        }
        return 0;
}

static int process_irq_flag(struct bpf_verifier_env *env, int regno,
                             struct bpf_kfunc_call_arg_meta *meta)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        int err, kfunc_class = IRQ_NATIVE_KFUNC;
        bool irq_save;

        if (meta->func_id == special_kfunc_list[KF_bpf_local_irq_save] ||
            meta->func_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave]) {
                irq_save = true;
                if (meta->func_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave])
                        kfunc_class = IRQ_LOCK_KFUNC;
        } else if (meta->func_id == special_kfunc_list[KF_bpf_local_irq_restore] ||
                   meta->func_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore]) {
                irq_save = false;
                if (meta->func_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore])
                        kfunc_class = IRQ_LOCK_KFUNC;
        } else {
                verifier_bug(env, "unknown irq flags kfunc");
                return -EFAULT;
        }

        if (irq_save) {
                if (!is_irq_flag_reg_valid_uninit(env, reg)) {
                        verbose(env, "expected uninitialized irq flag as arg#%d\n", regno - 1);
                        return -EINVAL;
                }

                err = check_mem_access(env, env->insn_idx, regno, 0, BPF_DW, BPF_WRITE, -1, false, false);
                if (err)
                        return err;

                err = mark_stack_slot_irq_flag(env, meta, reg, env->insn_idx, kfunc_class);
                if (err)
                        return err;
        } else {
                err = is_irq_flag_reg_valid_init(env, reg);
                if (err) {
                        verbose(env, "expected an initialized irq flag as arg#%d\n", regno - 1);
                        return err;
                }

                err = mark_irq_flag_read(env, reg);
                if (err)
                        return err;

                err = unmark_stack_slot_irq_flag(env, reg, kfunc_class);
                if (err)
                        return err;
        }
        return 0;
}


static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct btf_record *rec = reg_btf_record(reg);

        if (!env->cur_state->active_locks) {
                verifier_bug(env, "%s w/o active lock", __func__);
                return -EFAULT;
        }

        if (type_flag(reg->type) & NON_OWN_REF) {
                verifier_bug(env, "NON_OWN_REF already set");
                return -EFAULT;
        }

        reg->type |= NON_OWN_REF;
        if (rec->refcount_off >= 0)
                reg->type |= MEM_RCU;

        return 0;
}

static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id)
{
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_func_state *unused;
        struct bpf_reg_state *reg;
        int i;

        if (!ref_obj_id) {
                verifier_bug(env, "ref_obj_id is zero for owning -> non-owning conversion");
                return -EFAULT;
        }

        for (i = 0; i < state->acquired_refs; i++) {
                if (state->refs[i].id != ref_obj_id)
                        continue;

                /* Clear ref_obj_id here so release_reference doesn't clobber
                 * the whole reg
                 */
                bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
                        if (reg->ref_obj_id == ref_obj_id) {
                                reg->ref_obj_id = 0;
                                ref_set_non_owning(env, reg);
                        }
                }));
                return 0;
        }

        verifier_bug(env, "ref state missing for ref_obj_id");
        return -EFAULT;
}

/* Implementation details:
 *
 * Each register points to some region of memory, which we define as an
 * allocation. Each allocation may embed a bpf_spin_lock which protects any
 * special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same
 * allocation. The lock and the data it protects are colocated in the same
 * memory region.
 *
 * Hence, everytime a register holds a pointer value pointing to such
 * allocation, the verifier preserves a unique reg->id for it.
 *
 * The verifier remembers the lock 'ptr' and the lock 'id' whenever
 * bpf_spin_lock is called.
 *
 * To enable this, lock state in the verifier captures two values:
 *      active_lock.ptr = Register's type specific pointer
 *      active_lock.id  = A unique ID for each register pointer value
 *
 * Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two
 * supported register types.
 *
 * The active_lock.ptr in case of map values is the reg->map_ptr, and in case of
 * allocated objects is the reg->btf pointer.
 *
 * The active_lock.id is non-unique for maps supporting direct_value_addr, as we
 * can establish the provenance of the map value statically for each distinct
 * lookup into such maps. They always contain a single map value hence unique
 * IDs for each pseudo load pessimizes the algorithm and rejects valid programs.
 *
 * So, in case of global variables, they use array maps with max_entries = 1,
 * hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point
 * into the same map value as max_entries is 1, as described above).
 *
 * In case of inner map lookups, the inner map pointer has same map_ptr as the
 * outer map pointer (in verifier context), but each lookup into an inner map
 * assigns a fresh reg->id to the lookup, so while lookups into distinct inner
 * maps from the same outer map share the same map_ptr as active_lock.ptr, they
 * will get different reg->id assigned to each lookup, hence different
 * active_lock.id.
 *
 * In case of allocated objects, active_lock.ptr is the reg->btf, and the
 * reg->id is a unique ID preserved after the NULL pointer check on the pointer
 * returned from bpf_obj_new. Each allocation receives a new reg->id.
 */
static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
        struct bpf_reference_state *s;
        void *ptr;
        u32 id;

        switch ((int)reg->type) {
        case PTR_TO_MAP_VALUE:
                ptr = reg->map_ptr;
                break;
        case PTR_TO_BTF_ID | MEM_ALLOC:
                ptr = reg->btf;
                break;
        default:
                verifier_bug(env, "unknown reg type for lock check");
                return -EFAULT;
        }
        id = reg->id;

        if (!env->cur_state->active_locks)
                return -EINVAL;
        s = find_lock_state(env->cur_state, REF_TYPE_LOCK_MASK, id, ptr);
        if (!s) {
                verbose(env, "held lock and object are not in the same allocation\n");
                return -EINVAL;
        }
        return 0;
}

static bool is_bpf_list_api_kfunc(u32 btf_id)
{
        return is_bpf_list_push_kfunc(btf_id) ||
               btf_id == special_kfunc_list[KF_bpf_list_pop_front] ||
               btf_id == special_kfunc_list[KF_bpf_list_pop_back] ||
               btf_id == special_kfunc_list[KF_bpf_list_front] ||
               btf_id == special_kfunc_list[KF_bpf_list_back];
}

static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
{
        return is_bpf_rbtree_add_kfunc(btf_id) ||
               btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
               btf_id == special_kfunc_list[KF_bpf_rbtree_first] ||
               btf_id == special_kfunc_list[KF_bpf_rbtree_root] ||
               btf_id == special_kfunc_list[KF_bpf_rbtree_left] ||
               btf_id == special_kfunc_list[KF_bpf_rbtree_right];
}

static bool is_bpf_iter_num_api_kfunc(u32 btf_id)
{
        return btf_id == special_kfunc_list[KF_bpf_iter_num_new] ||
               btf_id == special_kfunc_list[KF_bpf_iter_num_next] ||
               btf_id == special_kfunc_list[KF_bpf_iter_num_destroy];
}

static bool is_bpf_graph_api_kfunc(u32 btf_id)
{
        return is_bpf_list_api_kfunc(btf_id) ||
               is_bpf_rbtree_api_kfunc(btf_id) ||
               is_bpf_refcount_acquire_kfunc(btf_id);
}

static bool is_bpf_res_spin_lock_kfunc(u32 btf_id)
{
        return btf_id == special_kfunc_list[KF_bpf_res_spin_lock] ||
               btf_id == special_kfunc_list[KF_bpf_res_spin_unlock] ||
               btf_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave] ||
               btf_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore];
}

static bool is_bpf_arena_kfunc(u32 btf_id)
{
        return btf_id == special_kfunc_list[KF_bpf_arena_alloc_pages] ||
               btf_id == special_kfunc_list[KF_bpf_arena_free_pages] ||
               btf_id == special_kfunc_list[KF_bpf_arena_reserve_pages];
}

static bool is_bpf_stream_kfunc(u32 btf_id)
{
        return btf_id == special_kfunc_list[KF_bpf_stream_vprintk] ||
               btf_id == special_kfunc_list[KF_bpf_stream_print_stack];
}

static bool kfunc_spin_allowed(u32 btf_id)
{
        return is_bpf_graph_api_kfunc(btf_id) || is_bpf_iter_num_api_kfunc(btf_id) ||
               is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id) ||
               is_bpf_stream_kfunc(btf_id);
}

static bool is_sync_callback_calling_kfunc(u32 btf_id)
{
        return is_bpf_rbtree_add_kfunc(btf_id);
}

static bool is_async_callback_calling_kfunc(u32 btf_id)
{
        return is_bpf_wq_set_callback_kfunc(btf_id) ||
               is_task_work_add_kfunc(btf_id);
}

static bool is_bpf_throw_kfunc(struct bpf_insn *insn)
{
        return bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
               insn->imm == special_kfunc_list[KF_bpf_throw];
}

static bool is_bpf_wq_set_callback_kfunc(u32 btf_id)
{
        return btf_id == special_kfunc_list[KF_bpf_wq_set_callback];
}

static bool is_callback_calling_kfunc(u32 btf_id)
{
        return is_sync_callback_calling_kfunc(btf_id) ||
               is_async_callback_calling_kfunc(btf_id);
}

static bool is_rbtree_lock_required_kfunc(u32 btf_id)
{
        return is_bpf_rbtree_api_kfunc(btf_id);
}

static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env,
                                          enum btf_field_type head_field_type,
                                          u32 kfunc_btf_id)
{
        bool ret;

        switch (head_field_type) {
        case BPF_LIST_HEAD:
                ret = is_bpf_list_api_kfunc(kfunc_btf_id);
                break;
        case BPF_RB_ROOT:
                ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id);
                break;
        default:
                verbose(env, "verifier internal error: unexpected graph root argument type %s\n",
                        btf_field_type_name(head_field_type));
                return false;
        }

        if (!ret)
                verbose(env, "verifier internal error: %s head arg for unknown kfunc\n",
                        btf_field_type_name(head_field_type));
        return ret;
}

static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env,
                                          enum btf_field_type node_field_type,
                                          u32 kfunc_btf_id)
{
        bool ret;

        switch (node_field_type) {
        case BPF_LIST_NODE:
                ret = is_bpf_list_push_kfunc(kfunc_btf_id);
                break;
        case BPF_RB_NODE:
                ret = (is_bpf_rbtree_add_kfunc(kfunc_btf_id) ||
                       kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
                       kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_left] ||
                       kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_right]);
                break;
        default:
                verbose(env, "verifier internal error: unexpected graph node argument type %s\n",
                        btf_field_type_name(node_field_type));
                return false;
        }

        if (!ret)
                verbose(env, "verifier internal error: %s node arg for unknown kfunc\n",
                        btf_field_type_name(node_field_type));
        return ret;
}

static int
__process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg, u32 regno,
                                   struct bpf_kfunc_call_arg_meta *meta,
                                   enum btf_field_type head_field_type,
                                   struct btf_field **head_field)
{
        const char *head_type_name;
        struct btf_field *field;
        struct btf_record *rec;
        u32 head_off;

        if (meta->btf != btf_vmlinux) {
                verifier_bug(env, "unexpected btf mismatch in kfunc call");
                return -EFAULT;
        }

        if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id))
                return -EFAULT;

        head_type_name = btf_field_type_name(head_field_type);
        if (!tnum_is_const(reg->var_off)) {
                verbose(env,
                        "R%d doesn't have constant offset. %s has to be at the constant offset\n",
                        regno, head_type_name);
                return -EINVAL;
        }

        rec = reg_btf_record(reg);
        head_off = reg->var_off.value;
        field = btf_record_find(rec, head_off, head_field_type);
        if (!field) {
                verbose(env, "%s not found at offset=%u\n", head_type_name, head_off);
                return -EINVAL;
        }

        /* All functions require bpf_list_head to be protected using a bpf_spin_lock */
        if (check_reg_allocation_locked(env, reg)) {
                verbose(env, "bpf_spin_lock at off=%d must be held for %s\n",
                        rec->spin_lock_off, head_type_name);
                return -EINVAL;
        }

        if (*head_field) {
                verifier_bug(env, "repeating %s arg", head_type_name);
                return -EFAULT;
        }
        *head_field = field;
        return 0;
}

static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env,
                                           struct bpf_reg_state *reg, u32 regno,
                                           struct bpf_kfunc_call_arg_meta *meta)
{
        return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD,
                                                          &meta->arg_list_head.field);
}

static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env,
                                             struct bpf_reg_state *reg, u32 regno,
                                             struct bpf_kfunc_call_arg_meta *meta)
{
        return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT,
                                                          &meta->arg_rbtree_root.field);
}

static int
__process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env,
                                   struct bpf_reg_state *reg, u32 regno,
                                   struct bpf_kfunc_call_arg_meta *meta,
                                   enum btf_field_type head_field_type,
                                   enum btf_field_type node_field_type,
                                   struct btf_field **node_field)
{
        const char *node_type_name;
        const struct btf_type *et, *t;
        struct btf_field *field;
        u32 node_off;

        if (meta->btf != btf_vmlinux) {
                verifier_bug(env, "unexpected btf mismatch in kfunc call");
                return -EFAULT;
        }

        if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id))
                return -EFAULT;

        node_type_name = btf_field_type_name(node_field_type);
        if (!tnum_is_const(reg->var_off)) {
                verbose(env,
                        "R%d doesn't have constant offset. %s has to be at the constant offset\n",
                        regno, node_type_name);
                return -EINVAL;
        }

        node_off = reg->var_off.value;
        field = reg_find_field_offset(reg, node_off, node_field_type);
        if (!field) {
                verbose(env, "%s not found at offset=%u\n", node_type_name, node_off);
                return -EINVAL;
        }

        field = *node_field;

        et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id);
        t = btf_type_by_id(reg->btf, reg->btf_id);
        if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf,
                                  field->graph_root.value_btf_id, true)) {
                verbose(env, "operation on %s expects arg#1 %s at offset=%d "
                        "in struct %s, but arg is at offset=%d in struct %s\n",
                        btf_field_type_name(head_field_type),
                        btf_field_type_name(node_field_type),
                        field->graph_root.node_offset,
                        btf_name_by_offset(field->graph_root.btf, et->name_off),
                        node_off, btf_name_by_offset(reg->btf, t->name_off));
                return -EINVAL;
        }
        meta->arg_btf = reg->btf;
        meta->arg_btf_id = reg->btf_id;

        if (node_off != field->graph_root.node_offset) {
                verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n",
                        node_off, btf_field_type_name(node_field_type),
                        field->graph_root.node_offset,
                        btf_name_by_offset(field->graph_root.btf, et->name_off));
                return -EINVAL;
        }

        return 0;
}

static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env,
                                           struct bpf_reg_state *reg, u32 regno,
                                           struct bpf_kfunc_call_arg_meta *meta)
{
        return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
                                                  BPF_LIST_HEAD, BPF_LIST_NODE,
                                                  &meta->arg_list_head.field);
}

static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env,
                                             struct bpf_reg_state *reg, u32 regno,
                                             struct bpf_kfunc_call_arg_meta *meta)
{
        return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
                                                  BPF_RB_ROOT, BPF_RB_NODE,
                                                  &meta->arg_rbtree_root.field);
}

/*
 * css_task iter allowlist is needed to avoid dead locking on css_set_lock.
 * LSM hooks and iters (both sleepable and non-sleepable) are safe.
 * Any sleepable progs are also safe since bpf_check_attach_target() enforce
 * them can only be attached to some specific hook points.
 */
static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
{
        enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

        switch (prog_type) {
        case BPF_PROG_TYPE_LSM:
                return true;
        case BPF_PROG_TYPE_TRACING:
                if (env->prog->expected_attach_type == BPF_TRACE_ITER)
                        return true;
                fallthrough;
        default:
                return in_sleepable(env);
        }
}

static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
                            int insn_idx)
{
        const char *func_name = meta->func_name, *ref_tname;
        const struct btf *btf = meta->btf;
        const struct btf_param *args;
        struct btf_record *rec;
        u32 i, nargs;
        int ret;

        args = (const struct btf_param *)(meta->func_proto + 1);
        nargs = btf_type_vlen(meta->func_proto);
        if (nargs > MAX_BPF_FUNC_REG_ARGS) {
                verbose(env, "Function %s has %d > %d args\n", func_name, nargs,
                        MAX_BPF_FUNC_REG_ARGS);
                return -EINVAL;
        }

        /* Check that BTF function arguments match actual types that the
         * verifier sees.
         */
        for (i = 0; i < nargs; i++) {
                struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[i + 1];
                const struct btf_type *t, *ref_t, *resolve_ret;
                enum bpf_arg_type arg_type = ARG_DONTCARE;
                u32 regno = i + 1, ref_id, type_size;
                bool is_ret_buf_sz = false;
                int kf_arg_type;

                if (is_kfunc_arg_prog_aux(btf, &args[i])) {
                        /* Reject repeated use bpf_prog_aux */
                        if (meta->arg_prog) {
                                verifier_bug(env, "Only 1 prog->aux argument supported per-kfunc");
                                return -EFAULT;
                        }
                        meta->arg_prog = true;
                        cur_aux(env)->arg_prog = regno;
                        continue;
                }

                if (is_kfunc_arg_ignore(btf, &args[i]) || is_kfunc_arg_implicit(meta, i))
                        continue;

                t = btf_type_skip_modifiers(btf, args[i].type, NULL);

                if (btf_type_is_scalar(t)) {
                        if (reg->type != SCALAR_VALUE) {
                                verbose(env, "R%d is not a scalar\n", regno);
                                return -EINVAL;
                        }

                        if (is_kfunc_arg_constant(meta->btf, &args[i])) {
                                if (meta->arg_constant.found) {
                                        verifier_bug(env, "only one constant argument permitted");
                                        return -EFAULT;
                                }
                                if (!tnum_is_const(reg->var_off)) {
                                        verbose(env, "R%d must be a known constant\n", regno);
                                        return -EINVAL;
                                }
                                ret = mark_chain_precision(env, regno);
                                if (ret < 0)
                                        return ret;
                                meta->arg_constant.found = true;
                                meta->arg_constant.value = reg->var_off.value;
                        } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) {
                                meta->r0_rdonly = true;
                                is_ret_buf_sz = true;
                        } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) {
                                is_ret_buf_sz = true;
                        }

                        if (is_ret_buf_sz) {
                                if (meta->r0_size) {
                                        verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc");
                                        return -EINVAL;
                                }

                                if (!tnum_is_const(reg->var_off)) {
                                        verbose(env, "R%d is not a const\n", regno);
                                        return -EINVAL;
                                }

                                meta->r0_size = reg->var_off.value;
                                ret = mark_chain_precision(env, regno);
                                if (ret)
                                        return ret;
                        }
                        continue;
                }

                if (!btf_type_is_ptr(t)) {
                        verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t));
                        return -EINVAL;
                }

                if ((bpf_register_is_null(reg) || type_may_be_null(reg->type)) &&
                    !is_kfunc_arg_nullable(meta->btf, &args[i])) {
                        verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i);
                        return -EACCES;
                }

                if (reg->ref_obj_id) {
                        if (is_kfunc_release(meta) && meta->ref_obj_id) {
                                verifier_bug(env, "more than one arg with ref_obj_id R%d %u %u",
                                             regno, reg->ref_obj_id,
                                             meta->ref_obj_id);
                                return -EFAULT;
                        }
                        meta->ref_obj_id = reg->ref_obj_id;
                        if (is_kfunc_release(meta))
                                meta->release_regno = regno;
                }

                ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
                ref_tname = btf_name_by_offset(btf, ref_t->name_off);

                kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs);
                if (kf_arg_type < 0)
                        return kf_arg_type;

                switch (kf_arg_type) {
                case KF_ARG_PTR_TO_NULL:
                        continue;
                case KF_ARG_PTR_TO_MAP:
                        if (!reg->map_ptr) {
                                verbose(env, "pointer in R%d isn't map pointer\n", regno);
                                return -EINVAL;
                        }
                        if (meta->map.ptr && (reg->map_ptr->record->wq_off >= 0 ||
                                              reg->map_ptr->record->task_work_off >= 0)) {
                                /* Use map_uid (which is unique id of inner map) to reject:
                                 * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
                                 * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
                                 * if (inner_map1 && inner_map2) {
                                 *     wq = bpf_map_lookup_elem(inner_map1);
                                 *     if (wq)
                                 *         // mismatch would have been allowed
                                 *         bpf_wq_init(wq, inner_map2);
                                 * }
                                 *
                                 * Comparing map_ptr is enough to distinguish normal and outer maps.
                                 */
                                if (meta->map.ptr != reg->map_ptr ||
                                    meta->map.uid != reg->map_uid) {
                                        if (reg->map_ptr->record->task_work_off >= 0) {
                                                verbose(env,
                                                        "bpf_task_work pointer in R2 map_uid=%d doesn't match map pointer in R3 map_uid=%d\n",
                                                        meta->map.uid, reg->map_uid);
                                                return -EINVAL;
                                        }
                                        verbose(env,
                                                "workqueue pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
                                                meta->map.uid, reg->map_uid);
                                        return -EINVAL;
                                }
                        }
                        meta->map.ptr = reg->map_ptr;
                        meta->map.uid = reg->map_uid;
                        fallthrough;
                case KF_ARG_PTR_TO_ALLOC_BTF_ID:
                case KF_ARG_PTR_TO_BTF_ID:
                        if (!is_trusted_reg(reg)) {
                                if (!is_kfunc_rcu(meta)) {
                                        verbose(env, "R%d must be referenced or trusted\n", regno);
                                        return -EINVAL;
                                }
                                if (!is_rcu_reg(reg)) {
                                        verbose(env, "R%d must be a rcu pointer\n", regno);
                                        return -EINVAL;
                                }
                        }
                        fallthrough;
                case KF_ARG_PTR_TO_DYNPTR:
                case KF_ARG_PTR_TO_ITER:
                case KF_ARG_PTR_TO_LIST_HEAD:
                case KF_ARG_PTR_TO_LIST_NODE:
                case KF_ARG_PTR_TO_RB_ROOT:
                case KF_ARG_PTR_TO_RB_NODE:
                case KF_ARG_PTR_TO_MEM:
                case KF_ARG_PTR_TO_MEM_SIZE:
                case KF_ARG_PTR_TO_CALLBACK:
                case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
                case KF_ARG_PTR_TO_CONST_STR:
                case KF_ARG_PTR_TO_WORKQUEUE:
                case KF_ARG_PTR_TO_TIMER:
                case KF_ARG_PTR_TO_TASK_WORK:
                case KF_ARG_PTR_TO_IRQ_FLAG:
                case KF_ARG_PTR_TO_RES_SPIN_LOCK:
                        break;
                case KF_ARG_PTR_TO_CTX:
                        arg_type = ARG_PTR_TO_CTX;
                        break;
                default:
                        verifier_bug(env, "unknown kfunc arg type %d", kf_arg_type);
                        return -EFAULT;
                }

                if (is_kfunc_release(meta) && reg->ref_obj_id)
                        arg_type |= OBJ_RELEASE;
                ret = check_func_arg_reg_off(env, reg, regno, arg_type);
                if (ret < 0)
                        return ret;

                switch (kf_arg_type) {
                case KF_ARG_PTR_TO_CTX:
                        if (reg->type != PTR_TO_CTX) {
                                verbose(env, "arg#%d expected pointer to ctx, but got %s\n",
                                        i, reg_type_str(env, reg->type));
                                return -EINVAL;
                        }

                        if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
                                ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog));
                                if (ret < 0)
                                        return -EINVAL;
                                meta->ret_btf_id  = ret;
                        }
                        break;
                case KF_ARG_PTR_TO_ALLOC_BTF_ID:
                        if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                if (!is_bpf_obj_drop_kfunc(meta->func_id)) {
                                        verbose(env, "arg#%d expected for bpf_obj_drop()\n", i);
                                        return -EINVAL;
                                }
                        } else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC | MEM_PERCPU)) {
                                if (!is_bpf_percpu_obj_drop_kfunc(meta->func_id)) {
                                        verbose(env, "arg#%d expected for bpf_percpu_obj_drop()\n", i);
                                        return -EINVAL;
                                }
                        } else {
                                verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                return -EINVAL;
                        }
                        if (!reg->ref_obj_id) {
                                verbose(env, "allocated object must be referenced\n");
                                return -EINVAL;
                        }
                        if (meta->btf == btf_vmlinux) {
                                meta->arg_btf = reg->btf;
                                meta->arg_btf_id = reg->btf_id;
                        }
                        break;
                case KF_ARG_PTR_TO_DYNPTR:
                {
                        enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR;
                        int clone_ref_obj_id = 0;

                        if (reg->type == CONST_PTR_TO_DYNPTR)
                                dynptr_arg_type |= MEM_RDONLY;

                        if (is_kfunc_arg_uninit(btf, &args[i]))
                                dynptr_arg_type |= MEM_UNINIT;

                        if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
                                dynptr_arg_type |= DYNPTR_TYPE_SKB;
                        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) {
                                dynptr_arg_type |= DYNPTR_TYPE_XDP;
                        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb_meta]) {
                                dynptr_arg_type |= DYNPTR_TYPE_SKB_META;
                        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_file]) {
                                dynptr_arg_type |= DYNPTR_TYPE_FILE;
                        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_file_discard]) {
                                dynptr_arg_type |= DYNPTR_TYPE_FILE;
                                meta->release_regno = regno;
                        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] &&
                                   (dynptr_arg_type & MEM_UNINIT)) {
                                enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type;

                                if (parent_type == BPF_DYNPTR_TYPE_INVALID) {
                                        verifier_bug(env, "no dynptr type for parent of clone");
                                        return -EFAULT;
                                }

                                dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type);
                                clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id;
                                if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) {
                                        verifier_bug(env, "missing ref obj id for parent of clone");
                                        return -EFAULT;
                                }
                        }

                        ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id);
                        if (ret < 0)
                                return ret;

                        if (!(dynptr_arg_type & MEM_UNINIT)) {
                                int id = dynptr_id(env, reg);

                                if (id < 0) {
                                        verifier_bug(env, "failed to obtain dynptr id");
                                        return id;
                                }
                                meta->initialized_dynptr.id = id;
                                meta->initialized_dynptr.type = dynptr_get_type(env, reg);
                                meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg);
                        }

                        break;
                }
                case KF_ARG_PTR_TO_ITER:
                        if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) {
                                if (!check_css_task_iter_allowlist(env)) {
                                        verbose(env, "css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs\n");
                                        return -EINVAL;
                                }
                        }
                        ret = process_iter_arg(env, regno, insn_idx, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_LIST_HEAD:
                        if (reg->type != PTR_TO_MAP_VALUE &&
                            reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
                                return -EINVAL;
                        }
                        if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
                                verbose(env, "allocated object must be referenced\n");
                                return -EINVAL;
                        }
                        ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_RB_ROOT:
                        if (reg->type != PTR_TO_MAP_VALUE &&
                            reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
                                return -EINVAL;
                        }
                        if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
                                verbose(env, "allocated object must be referenced\n");
                                return -EINVAL;
                        }
                        ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_LIST_NODE:
                        if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                return -EINVAL;
                        }
                        if (!reg->ref_obj_id) {
                                verbose(env, "allocated object must be referenced\n");
                                return -EINVAL;
                        }
                        ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_RB_NODE:
                        if (is_bpf_rbtree_add_kfunc(meta->func_id)) {
                                if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                        verbose(env, "arg#%d expected pointer to allocated object\n", i);
                                        return -EINVAL;
                                }
                                if (!reg->ref_obj_id) {
                                        verbose(env, "allocated object must be referenced\n");
                                        return -EINVAL;
                                }
                        } else {
                                if (!type_is_non_owning_ref(reg->type) && !reg->ref_obj_id) {
                                        verbose(env, "%s can only take non-owning or refcounted bpf_rb_node pointer\n", func_name);
                                        return -EINVAL;
                                }
                                if (in_rbtree_lock_required_cb(env)) {
                                        verbose(env, "%s not allowed in rbtree cb\n", func_name);
                                        return -EINVAL;
                                }
                        }

                        ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_MAP:
                        /* If argument has '__map' suffix expect 'struct bpf_map *' */
                        ref_id = *reg2btf_ids[CONST_PTR_TO_MAP];
                        ref_t = btf_type_by_id(btf_vmlinux, ref_id);
                        ref_tname = btf_name_by_offset(btf, ref_t->name_off);
                        fallthrough;
                case KF_ARG_PTR_TO_BTF_ID:
                        /* Only base_type is checked, further checks are done here */
                        if ((base_type(reg->type) != PTR_TO_BTF_ID ||
                             (bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) &&
                            !reg2btf_ids[base_type(reg->type)]) {
                                verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type));
                                verbose(env, "expected %s or socket\n",
                                        reg_type_str(env, base_type(reg->type) |
                                                          (type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS)));
                                return -EINVAL;
                        }
                        ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_MEM:
                        resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
                        if (IS_ERR(resolve_ret)) {
                                verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
                                        i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret));
                                return -EINVAL;
                        }
                        ret = check_mem_reg(env, reg, regno, type_size);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_MEM_SIZE:
                {
                        struct bpf_reg_state *buff_reg = &regs[regno];
                        const struct btf_param *buff_arg = &args[i];
                        struct bpf_reg_state *size_reg = &regs[regno + 1];
                        const struct btf_param *size_arg = &args[i + 1];

                        if (!bpf_register_is_null(buff_reg) || !is_kfunc_arg_nullable(meta->btf, buff_arg)) {
                                ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1);
                                if (ret < 0) {
                                        verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1);
                                        return ret;
                                }
                        }

                        if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) {
                                if (meta->arg_constant.found) {
                                        verifier_bug(env, "only one constant argument permitted");
                                        return -EFAULT;
                                }
                                if (!tnum_is_const(size_reg->var_off)) {
                                        verbose(env, "R%d must be a known constant\n", regno + 1);
                                        return -EINVAL;
                                }
                                meta->arg_constant.found = true;
                                meta->arg_constant.value = size_reg->var_off.value;
                        }

                        /* Skip next '__sz' or '__szk' argument */
                        i++;
                        break;
                }
                case KF_ARG_PTR_TO_CALLBACK:
                        if (reg->type != PTR_TO_FUNC) {
                                verbose(env, "arg%d expected pointer to func\n", i);
                                return -EINVAL;
                        }
                        meta->subprogno = reg->subprogno;
                        break;
                case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
                        if (!type_is_ptr_alloc_obj(reg->type)) {
                                verbose(env, "arg#%d is neither owning or non-owning ref\n", i);
                                return -EINVAL;
                        }
                        if (!type_is_non_owning_ref(reg->type))
                                meta->arg_owning_ref = true;

                        rec = reg_btf_record(reg);
                        if (!rec) {
                                verifier_bug(env, "Couldn't find btf_record");
                                return -EFAULT;
                        }

                        if (rec->refcount_off < 0) {
                                verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i);
                                return -EINVAL;
                        }

                        meta->arg_btf = reg->btf;
                        meta->arg_btf_id = reg->btf_id;
                        break;
                case KF_ARG_PTR_TO_CONST_STR:
                        if (reg->type != PTR_TO_MAP_VALUE) {
                                verbose(env, "arg#%d doesn't point to a const string\n", i);
                                return -EINVAL;
                        }
                        ret = check_reg_const_str(env, reg, regno);
                        if (ret)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_WORKQUEUE:
                        if (reg->type != PTR_TO_MAP_VALUE) {
                                verbose(env, "arg#%d doesn't point to a map value\n", i);
                                return -EINVAL;
                        }
                        ret = check_map_field_pointer(env, regno, BPF_WORKQUEUE, &meta->map);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_TIMER:
                        if (reg->type != PTR_TO_MAP_VALUE) {
                                verbose(env, "arg#%d doesn't point to a map value\n", i);
                                return -EINVAL;
                        }
                        ret = process_timer_kfunc(env, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_TASK_WORK:
                        if (reg->type != PTR_TO_MAP_VALUE) {
                                verbose(env, "arg#%d doesn't point to a map value\n", i);
                                return -EINVAL;
                        }
                        ret = check_map_field_pointer(env, regno, BPF_TASK_WORK, &meta->map);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_IRQ_FLAG:
                        if (reg->type != PTR_TO_STACK) {
                                verbose(env, "arg#%d doesn't point to an irq flag on stack\n", i);
                                return -EINVAL;
                        }
                        ret = process_irq_flag(env, regno, meta);
                        if (ret < 0)
                                return ret;
                        break;
                case KF_ARG_PTR_TO_RES_SPIN_LOCK:
                {
                        int flags = PROCESS_RES_LOCK;

                        if (reg->type != PTR_TO_MAP_VALUE && reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
                                verbose(env, "arg#%d doesn't point to map value or allocated object\n", i);
                                return -EINVAL;
                        }

                        if (!is_bpf_res_spin_lock_kfunc(meta->func_id))
                                return -EFAULT;
                        if (meta->func_id == special_kfunc_list[KF_bpf_res_spin_lock] ||
                            meta->func_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave])
                                flags |= PROCESS_SPIN_LOCK;
                        if (meta->func_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave] ||
                            meta->func_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore])
                                flags |= PROCESS_LOCK_IRQ;
                        ret = process_spin_lock(env, regno, flags);
                        if (ret < 0)
                                return ret;
                        break;
                }
                }
        }

        if (is_kfunc_release(meta) && !meta->release_regno) {
                verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
                        func_name);
                return -EINVAL;
        }

        return 0;
}

int bpf_fetch_kfunc_arg_meta(struct bpf_verifier_env *env,
                             s32 func_id,
                             s16 offset,
                             struct bpf_kfunc_call_arg_meta *meta)
{
        struct bpf_kfunc_meta kfunc;
        int err;

        err = fetch_kfunc_meta(env, func_id, offset, &kfunc);
        if (err)
                return err;

        memset(meta, 0, sizeof(*meta));
        meta->btf = kfunc.btf;
        meta->func_id = kfunc.id;
        meta->func_proto = kfunc.proto;
        meta->func_name = kfunc.name;

        if (!kfunc.flags || !btf_kfunc_is_allowed(kfunc.btf, kfunc.id, env->prog))
                return -EACCES;

        meta->kfunc_flags = *kfunc.flags;

        return 0;
}

/*
 * Determine how many bytes a helper accesses through a stack pointer at
 * argument position @arg (0-based, corresponding to R1-R5).
 *
 * Returns:
 *   > 0   known read access size in bytes
 *     0   doesn't read anything directly
 * S64_MIN unknown
 *   < 0   known write access of (-return) bytes
 */
s64 bpf_helper_stack_access_bytes(struct bpf_verifier_env *env, struct bpf_insn *insn,
                                  int arg, int insn_idx)
{
        struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
        const struct bpf_func_proto *fn;
        enum bpf_arg_type at;
        s64 size;

        if (bpf_get_helper_proto(env, insn->imm, &fn) < 0)
                return S64_MIN;

        at = fn->arg_type[arg];

        switch (base_type(at)) {
        case ARG_PTR_TO_MAP_KEY:
        case ARG_PTR_TO_MAP_VALUE: {
                bool is_key = base_type(at) == ARG_PTR_TO_MAP_KEY;
                u64 val;
                int i, map_reg;

                for (i = 0; i < arg; i++) {
                        if (base_type(fn->arg_type[i]) == ARG_CONST_MAP_PTR)
                                break;
                }
                if (i >= arg)
                        goto scan_all_maps;

                map_reg = BPF_REG_1 + i;

                if (!(aux->const_reg_map_mask & BIT(map_reg)))
                        goto scan_all_maps;

                i = aux->const_reg_vals[map_reg];
                if (i < env->used_map_cnt) {
                        size = is_key ? env->used_maps[i]->key_size
                                      : env->used_maps[i]->value_size;
                        goto out;
                }
scan_all_maps:
                /*
                 * Map pointer is not known at this call site (e.g. different
                 * maps on merged paths).  Conservatively return the largest
                 * key_size or value_size across all maps used by the program.
                 */
                val = 0;
                for (i = 0; i < env->used_map_cnt; i++) {
                        struct bpf_map *map = env->used_maps[i];
                        u32 sz = is_key ? map->key_size : map->value_size;

                        if (sz > val)
                                val = sz;
                        if (map->inner_map_meta) {
                                sz = is_key ? map->inner_map_meta->key_size
                                            : map->inner_map_meta->value_size;
                                if (sz > val)
                                        val = sz;
                        }
                }
                if (!val)
                        return S64_MIN;
                size = val;
                goto out;
        }
        case ARG_PTR_TO_MEM:
                if (at & MEM_FIXED_SIZE) {
                        size = fn->arg_size[arg];
                        goto out;
                }
                if (arg + 1 < ARRAY_SIZE(fn->arg_type) &&
                    arg_type_is_mem_size(fn->arg_type[arg + 1])) {
                        int size_reg = BPF_REG_1 + arg + 1;

                        if (aux->const_reg_mask & BIT(size_reg)) {
                                size = (s64)aux->const_reg_vals[size_reg];
                                goto out;
                        }
                        /*
                         * Size arg is const on each path but differs across merged
                         * paths. MAX_BPF_STACK is a safe upper bound for reads.
                         */
                        if (at & MEM_UNINIT)
                                return 0;
                        return MAX_BPF_STACK;
                }
                return S64_MIN;
        case ARG_PTR_TO_DYNPTR:
                size = BPF_DYNPTR_SIZE;
                break;
        case ARG_PTR_TO_STACK:
                /*
                 * Only used by bpf_calls_callback() helpers. The helper itself
                 * doesn't access stack. The callback subprog does and it's
                 * analyzed separately.
                 */
                return 0;
        default:
                return S64_MIN;
        }
out:
        /*
         * MEM_UNINIT args are write-only: the helper initializes the
         * buffer without reading it.
         */
        if (at & MEM_UNINIT)
                return -size;
        return size;
}

/*
 * Determine how many bytes a kfunc accesses through a stack pointer at
 * argument position @arg (0-based, corresponding to R1-R5).
 *
 * Returns:
 *   > 0      known read access size in bytes
 *     0      doesn't access memory through that argument (ex: not a pointer)
 *   S64_MIN  unknown
 *   < 0      known write access of (-return) bytes
 */
s64 bpf_kfunc_stack_access_bytes(struct bpf_verifier_env *env, struct bpf_insn *insn,
                                 int arg, int insn_idx)
{
        struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
        struct bpf_kfunc_call_arg_meta meta;
        const struct btf_param *args;
        const struct btf_type *t, *ref_t;
        const struct btf *btf;
        u32 nargs, type_size;
        s64 size;

        if (bpf_fetch_kfunc_arg_meta(env, insn->imm, insn->off, &meta) < 0)
                return S64_MIN;

        btf = meta.btf;
        args = btf_params(meta.func_proto);
        nargs = btf_type_vlen(meta.func_proto);
        if (arg >= nargs)
                return 0;

        t = btf_type_skip_modifiers(btf, args[arg].type, NULL);
        if (!btf_type_is_ptr(t))
                return 0;

        /* dynptr: fixed 16-byte on-stack representation */
        if (is_kfunc_arg_dynptr(btf, &args[arg])) {
                size = BPF_DYNPTR_SIZE;
                goto out;
        }

        /* ptr + __sz/__szk pair: size is in the next register */
        if (arg + 1 < nargs &&
            (btf_param_match_suffix(btf, &args[arg + 1], "__sz") ||
             btf_param_match_suffix(btf, &args[arg + 1], "__szk"))) {
                int size_reg = BPF_REG_1 + arg + 1;

                if (aux->const_reg_mask & BIT(size_reg)) {
                        size = (s64)aux->const_reg_vals[size_reg];
                        goto out;
                }
                return MAX_BPF_STACK;
        }

        /* fixed-size pointed-to type: resolve via BTF */
        ref_t = btf_type_skip_modifiers(btf, t->type, NULL);
        if (!IS_ERR(btf_resolve_size(btf, ref_t, &type_size))) {
                size = type_size;
                goto out;
        }

        return S64_MIN;
out:
        /* KF_ITER_NEW kfuncs initialize the iterator state at arg 0 */
        if (arg == 0 && meta.kfunc_flags & KF_ITER_NEW)
                return -size;
        if (is_kfunc_arg_uninit(btf, &args[arg]))
                return -size;
        return size;
}

/* check special kfuncs and return:
 *  1  - not fall-through to 'else' branch, continue verification
 *  0  - fall-through to 'else' branch
 * < 0 - not fall-through to 'else' branch, return error
 */
static int check_special_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
                               struct bpf_reg_state *regs, struct bpf_insn_aux_data *insn_aux,
                               const struct btf_type *ptr_type, struct btf *desc_btf)
{
        const struct btf_type *ret_t;
        int err = 0;

        if (meta->btf != btf_vmlinux)
                return 0;

        if (is_bpf_obj_new_kfunc(meta->func_id) || is_bpf_percpu_obj_new_kfunc(meta->func_id)) {
                struct btf_struct_meta *struct_meta;
                struct btf *ret_btf;
                u32 ret_btf_id;

                if (is_bpf_obj_new_kfunc(meta->func_id) && !bpf_global_ma_set)
                        return -ENOMEM;

                if (((u64)(u32)meta->arg_constant.value) != meta->arg_constant.value) {
                        verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
                        return -EINVAL;
                }

                ret_btf = env->prog->aux->btf;
                ret_btf_id = meta->arg_constant.value;

                /* This may be NULL due to user not supplying a BTF */
                if (!ret_btf) {
                        verbose(env, "bpf_obj_new/bpf_percpu_obj_new requires prog BTF\n");
                        return -EINVAL;
                }

                ret_t = btf_type_by_id(ret_btf, ret_btf_id);
                if (!ret_t || !__btf_type_is_struct(ret_t)) {
                        verbose(env, "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct\n");
                        return -EINVAL;
                }

                if (is_bpf_percpu_obj_new_kfunc(meta->func_id)) {
                        if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) {
                                verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n",
                                        ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE);
                                return -EINVAL;
                        }

                        if (!bpf_global_percpu_ma_set) {
                                mutex_lock(&bpf_percpu_ma_lock);
                                if (!bpf_global_percpu_ma_set) {
                                        /* Charge memory allocated with bpf_global_percpu_ma to
                                         * root memcg. The obj_cgroup for root memcg is NULL.
                                         */
                                        err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL);
                                        if (!err)
                                                bpf_global_percpu_ma_set = true;
                                }
                                mutex_unlock(&bpf_percpu_ma_lock);
                                if (err)
                                        return err;
                        }

                        mutex_lock(&bpf_percpu_ma_lock);
                        err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size);
                        mutex_unlock(&bpf_percpu_ma_lock);
                        if (err)
                                return err;
                }

                struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id);
                if (is_bpf_percpu_obj_new_kfunc(meta->func_id)) {
                        if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) {
                                verbose(env, "bpf_percpu_obj_new type ID argument must be of a struct of scalars\n");
                                return -EINVAL;
                        }

                        if (struct_meta) {
                                verbose(env, "bpf_percpu_obj_new type ID argument must not contain special fields\n");
                                return -EINVAL;
                        }
                }

                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
                regs[BPF_REG_0].btf = ret_btf;
                regs[BPF_REG_0].btf_id = ret_btf_id;
                if (is_bpf_percpu_obj_new_kfunc(meta->func_id))
                        regs[BPF_REG_0].type |= MEM_PERCPU;

                insn_aux->obj_new_size = ret_t->size;
                insn_aux->kptr_struct_meta = struct_meta;
        } else if (is_bpf_refcount_acquire_kfunc(meta->func_id)) {
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
                regs[BPF_REG_0].btf = meta->arg_btf;
                regs[BPF_REG_0].btf_id = meta->arg_btf_id;

                insn_aux->kptr_struct_meta =
                        btf_find_struct_meta(meta->arg_btf,
                                             meta->arg_btf_id);
        } else if (is_list_node_type(ptr_type)) {
                struct btf_field *field = meta->arg_list_head.field;

                mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
        } else if (is_rbtree_node_type(ptr_type)) {
                struct btf_field *field = meta->arg_rbtree_root.field;

                mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
        } else if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
                mark_reg_known_zero(env, regs, BPF_REG_0);
                regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED;
                regs[BPF_REG_0].btf = desc_btf;
                regs[BPF_REG_0].btf_id = meta->ret_btf_id;
        } else if (meta->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
                ret_t = btf_type_by_id(desc_btf, meta->arg_constant.value);
                if (!ret_t) {
                        verbose(env, "Unknown type ID %lld passed to kfunc bpf_rdonly_cast\n",
                                meta->arg_constant.value);
                        return -EINVAL;
                } else if (btf_type_is_struct(ret_t)) {
                        mark_reg_known_zero(env, regs, BPF_REG_0);
                        regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
                        regs[BPF_REG_0].btf = desc_btf;
                        regs[BPF_REG_0].btf_id = meta->arg_constant.value;
                } else if (btf_type_is_void(ret_t)) {
                        mark_reg_known_zero(env, regs, BPF_REG_0);
                        regs[BPF_REG_0].type = PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED;
                        regs[BPF_REG_0].mem_size = 0;
                } else {
                        verbose(env,
                                "kfunc bpf_rdonly_cast type ID argument must be of a struct or void\n");
                        return -EINVAL;
                }
        } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_slice] ||
                   meta->func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
                enum bpf_type_flag type_flag = get_dynptr_type_flag(meta->initialized_dynptr.type);

                mark_reg_known_zero(env, regs, BPF_REG_0);

                if (!meta->arg_constant.found) {
                        verifier_bug(env, "bpf_dynptr_slice(_rdwr) no constant size");
                        return -EFAULT;
                }

                regs[BPF_REG_0].mem_size = meta->arg_constant.value;

                /* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */
                regs[BPF_REG_0].type = PTR_TO_MEM | type_flag;

                if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_slice]) {
                        regs[BPF_REG_0].type |= MEM_RDONLY;
                } else {
                        /* this will set env->seen_direct_write to true */
                        if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) {
                                verbose(env, "the prog does not allow writes to packet data\n");
                                return -EINVAL;
                        }
                }

                if (!meta->initialized_dynptr.id) {
                        verifier_bug(env, "no dynptr id");
                        return -EFAULT;
                }
                regs[BPF_REG_0].dynptr_id = meta->initialized_dynptr.id;

                /* we don't need to set BPF_REG_0's ref obj id
                 * because packet slices are not refcounted (see
                 * dynptr_type_refcounted)
                 */
        } else {
                return 0;
        }

        return 1;
}

static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name);
static int process_bpf_exit_full(struct bpf_verifier_env *env,
                                 bool *do_print_state, bool exception_exit);

static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                            int *insn_idx_p)
{
        bool sleepable, rcu_lock, rcu_unlock, preempt_disable, preempt_enable;
        u32 i, nargs, ptr_type_id, release_ref_obj_id;
        struct bpf_reg_state *regs = cur_regs(env);
        const char *func_name, *ptr_type_name;
        const struct btf_type *t, *ptr_type;
        struct bpf_kfunc_call_arg_meta meta;
        struct bpf_insn_aux_data *insn_aux;
        int err, insn_idx = *insn_idx_p;
        const struct btf_param *args;
        struct btf *desc_btf;

        /* skip for now, but return error when we find this in fixup_kfunc_call */
        if (!insn->imm)
                return 0;

        err = bpf_fetch_kfunc_arg_meta(env, insn->imm, insn->off, &meta);
        if (err == -EACCES && meta.func_name)
                verbose(env, "calling kernel function %s is not allowed\n", meta.func_name);
        if (err)
                return err;
        desc_btf = meta.btf;
        func_name = meta.func_name;
        insn_aux = &env->insn_aux_data[insn_idx];

        insn_aux->is_iter_next = bpf_is_iter_next_kfunc(&meta);

        if (!insn->off &&
            (insn->imm == special_kfunc_list[KF_bpf_res_spin_lock] ||
             insn->imm == special_kfunc_list[KF_bpf_res_spin_lock_irqsave])) {
                struct bpf_verifier_state *branch;
                struct bpf_reg_state *regs;

                branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
                if (IS_ERR(branch)) {
                        verbose(env, "failed to push state for failed lock acquisition\n");
                        return PTR_ERR(branch);
                }

                regs = branch->frame[branch->curframe]->regs;

                /* Clear r0-r5 registers in forked state */
                for (i = 0; i < CALLER_SAVED_REGS; i++)
                        bpf_mark_reg_not_init(env, &regs[caller_saved[i]]);

                mark_reg_unknown(env, regs, BPF_REG_0);
                err = __mark_reg_s32_range(env, regs, BPF_REG_0, -MAX_ERRNO, -1);
                if (err) {
                        verbose(env, "failed to mark s32 range for retval in forked state for lock\n");
                        return err;
                }
                __mark_btf_func_reg_size(env, regs, BPF_REG_0, sizeof(u32));
        } else if (!insn->off && insn->imm == special_kfunc_list[KF___bpf_trap]) {
                verbose(env, "unexpected __bpf_trap() due to uninitialized variable?\n");
                return -EFAULT;
        }

        if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) {
                verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n");
                return -EACCES;
        }

        sleepable = bpf_is_kfunc_sleepable(&meta);
        if (sleepable && !in_sleepable(env)) {
                verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name);
                return -EACCES;
        }

        /* Track non-sleepable context for kfuncs, same as for helpers. */
        if (!in_sleepable_context(env))
                insn_aux->non_sleepable = true;

        /* Check the arguments */
        err = check_kfunc_args(env, &meta, insn_idx);
        if (err < 0)
                return err;

        if (is_bpf_rbtree_add_kfunc(meta.func_id)) {
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_rbtree_add_callback_state);
                if (err) {
                        verbose(env, "kfunc %s#%d failed callback verification\n",
                                func_name, meta.func_id);
                        return err;
                }
        }

        if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
                meta.r0_size = sizeof(u64);
                meta.r0_rdonly = false;
        }

        if (is_bpf_wq_set_callback_kfunc(meta.func_id)) {
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_timer_callback_state);
                if (err) {
                        verbose(env, "kfunc %s#%d failed callback verification\n",
                                func_name, meta.func_id);
                        return err;
                }
        }

        if (is_task_work_add_kfunc(meta.func_id)) {
                err = push_callback_call(env, insn, insn_idx, meta.subprogno,
                                         set_task_work_schedule_callback_state);
                if (err) {
                        verbose(env, "kfunc %s#%d failed callback verification\n",
                                func_name, meta.func_id);
                        return err;
                }
        }

        rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta);
        rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta);

        preempt_disable = is_kfunc_bpf_preempt_disable(&meta);
        preempt_enable = is_kfunc_bpf_preempt_enable(&meta);

        if (rcu_lock) {
                env->cur_state->active_rcu_locks++;
        } else if (rcu_unlock) {
                struct bpf_func_state *state;
                struct bpf_reg_state *reg;
                u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER);

                if (env->cur_state->active_rcu_locks == 0) {
                        verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
                        return -EINVAL;
                }
                if (--env->cur_state->active_rcu_locks == 0) {
                        bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({
                                if (reg->type & MEM_RCU) {
                                        reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL);
                                        reg->type |= PTR_UNTRUSTED;
                                }
                        }));
                }
        } else if (preempt_disable) {
                env->cur_state->active_preempt_locks++;
        } else if (preempt_enable) {
                if (env->cur_state->active_preempt_locks == 0) {
                        verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
                        return -EINVAL;
                }
                env->cur_state->active_preempt_locks--;
        }

        if (sleepable && !in_sleepable_context(env)) {
                verbose(env, "kernel func %s is sleepable within %s\n",
                        func_name, non_sleepable_context_description(env));
                return -EACCES;
        }

        if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) {
                verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n");
                return -EACCES;
        }

        if (is_kfunc_rcu_protected(&meta) && !in_rcu_cs(env)) {
                verbose(env, "kernel func %s requires RCU critical section protection\n", func_name);
                return -EACCES;
        }

        /* In case of release function, we get register number of refcounted
         * PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now.
         */
        if (meta.release_regno) {
                struct bpf_reg_state *reg = &regs[meta.release_regno];

                if (meta.initialized_dynptr.ref_obj_id) {
                        err = unmark_stack_slots_dynptr(env, reg);
                } else {
                        err = release_reference(env, reg->ref_obj_id);
                        if (err)
                                verbose(env, "kfunc %s#%d reference has not been acquired before\n",
                                        func_name, meta.func_id);
                }
                if (err)
                        return err;
        }

        if (is_bpf_list_push_kfunc(meta.func_id) || is_bpf_rbtree_add_kfunc(meta.func_id)) {
                release_ref_obj_id = regs[BPF_REG_2].ref_obj_id;
                insn_aux->insert_off = regs[BPF_REG_2].var_off.value;
                insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id);
                err = ref_convert_owning_non_owning(env, release_ref_obj_id);
                if (err) {
                        verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n",
                                func_name, meta.func_id);
                        return err;
                }

                err = release_reference(env, release_ref_obj_id);
                if (err) {
                        verbose(env, "kfunc %s#%d reference has not been acquired before\n",
                                func_name, meta.func_id);
                        return err;
                }
        }

        if (meta.func_id == special_kfunc_list[KF_bpf_throw]) {
                if (!bpf_jit_supports_exceptions()) {
                        verbose(env, "JIT does not support calling kfunc %s#%d\n",
                                func_name, meta.func_id);
                        return -ENOTSUPP;
                }
                env->seen_exception = true;

                /* In the case of the default callback, the cookie value passed
                 * to bpf_throw becomes the return value of the program.
                 */
                if (!env->exception_callback_subprog) {
                        err = check_return_code(env, BPF_REG_1, "R1");
                        if (err < 0)
                                return err;
                }
        }

        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                u32 regno = caller_saved[i];

                bpf_mark_reg_not_init(env, &regs[regno]);
                regs[regno].subreg_def = DEF_NOT_SUBREG;
        }

        /* Check return type */
        t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL);

        if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) {
                if (meta.btf != btf_vmlinux ||
                    (!is_bpf_obj_new_kfunc(meta.func_id) &&
                     !is_bpf_percpu_obj_new_kfunc(meta.func_id) &&
                     !is_bpf_refcount_acquire_kfunc(meta.func_id))) {
                        verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n");
                        return -EINVAL;
                }
        }

        if (btf_type_is_scalar(t)) {
                mark_reg_unknown(env, regs, BPF_REG_0);
                if (meta.btf == btf_vmlinux && (meta.func_id == special_kfunc_list[KF_bpf_res_spin_lock] ||
                    meta.func_id == special_kfunc_list[KF_bpf_res_spin_lock_irqsave]))
                        __mark_reg_const_zero(env, &regs[BPF_REG_0]);
                mark_btf_func_reg_size(env, BPF_REG_0, t->size);
        } else if (btf_type_is_ptr(t)) {
                ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id);
                err = check_special_kfunc(env, &meta, regs, insn_aux, ptr_type, desc_btf);
                if (err) {
                        if (err < 0)
                                return err;
                } else if (btf_type_is_void(ptr_type)) {
                        /* kfunc returning 'void *' is equivalent to returning scalar */
                        mark_reg_unknown(env, regs, BPF_REG_0);
                } else if (!__btf_type_is_struct(ptr_type)) {
                        if (!meta.r0_size) {
                                __u32 sz;

                                if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
                                        meta.r0_size = sz;
                                        meta.r0_rdonly = true;
                                }
                        }
                        if (!meta.r0_size) {
                                ptr_type_name = btf_name_by_offset(desc_btf,
                                                                   ptr_type->name_off);
                                verbose(env,
                                        "kernel function %s returns pointer type %s %s is not supported\n",
                                        func_name,
                                        btf_type_str(ptr_type),
                                        ptr_type_name);
                                return -EINVAL;
                        }

                        mark_reg_known_zero(env, regs, BPF_REG_0);
                        regs[BPF_REG_0].type = PTR_TO_MEM;
                        regs[BPF_REG_0].mem_size = meta.r0_size;

                        if (meta.r0_rdonly)
                                regs[BPF_REG_0].type |= MEM_RDONLY;

                        /* Ensures we don't access the memory after a release_reference() */
                        if (meta.ref_obj_id)
                                regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;

                        if (is_kfunc_rcu_protected(&meta))
                                regs[BPF_REG_0].type |= MEM_RCU;
                } else {
                        enum bpf_reg_type type = PTR_TO_BTF_ID;

                        if (meta.func_id == special_kfunc_list[KF_bpf_get_kmem_cache])
                                type |= PTR_UNTRUSTED;
                        else if (is_kfunc_rcu_protected(&meta) ||
                                 (bpf_is_iter_next_kfunc(&meta) &&
                                  (get_iter_from_state(env->cur_state, &meta)
                                           ->type & MEM_RCU))) {
                                /*
                                 * If the iterator's constructor (the _new
                                 * function e.g., bpf_iter_task_new) has been
                                 * annotated with BPF kfunc flag
                                 * KF_RCU_PROTECTED and was called within a RCU
                                 * read-side critical section, also propagate
                                 * the MEM_RCU flag to the pointer returned from
                                 * the iterator's next function (e.g.,
                                 * bpf_iter_task_next).
                                 */
                                type |= MEM_RCU;
                        } else {
                                /*
                                 * Any PTR_TO_BTF_ID that is returned from a BPF
                                 * kfunc should by default be treated as
                                 * implicitly trusted.
                                 */
                                type |= PTR_TRUSTED;
                        }

                        mark_reg_known_zero(env, regs, BPF_REG_0);
                        regs[BPF_REG_0].btf = desc_btf;
                        regs[BPF_REG_0].type = type;
                        regs[BPF_REG_0].btf_id = ptr_type_id;
                }

                if (is_kfunc_ret_null(&meta)) {
                        regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
                        /* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
                        regs[BPF_REG_0].id = ++env->id_gen;
                }
                mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
                if (is_kfunc_acquire(&meta)) {
                        int id = acquire_reference(env, insn_idx);

                        if (id < 0)
                                return id;
                        if (is_kfunc_ret_null(&meta))
                                regs[BPF_REG_0].id = id;
                        regs[BPF_REG_0].ref_obj_id = id;
                } else if (is_rbtree_node_type(ptr_type) || is_list_node_type(ptr_type)) {
                        ref_set_non_owning(env, &regs[BPF_REG_0]);
                }

                if (reg_may_point_to_spin_lock(&regs[BPF_REG_0]) && !regs[BPF_REG_0].id)
                        regs[BPF_REG_0].id = ++env->id_gen;
        } else if (btf_type_is_void(t)) {
                if (meta.btf == btf_vmlinux) {
                        if (is_bpf_obj_drop_kfunc(meta.func_id) ||
                            is_bpf_percpu_obj_drop_kfunc(meta.func_id)) {
                                insn_aux->kptr_struct_meta =
                                        btf_find_struct_meta(meta.arg_btf,
                                                             meta.arg_btf_id);
                        }
                }
        }

        if (bpf_is_kfunc_pkt_changing(&meta))
                clear_all_pkt_pointers(env);

        nargs = btf_type_vlen(meta.func_proto);
        args = (const struct btf_param *)(meta.func_proto + 1);
        for (i = 0; i < nargs; i++) {
                u32 regno = i + 1;

                t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL);
                if (btf_type_is_ptr(t))
                        mark_btf_func_reg_size(env, regno, sizeof(void *));
                else
                        /* scalar. ensured by check_kfunc_args() */
                        mark_btf_func_reg_size(env, regno, t->size);
        }

        if (bpf_is_iter_next_kfunc(&meta)) {
                err = process_iter_next_call(env, insn_idx, &meta);
                if (err)
                        return err;
        }

        if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie])
                env->prog->call_session_cookie = true;

        if (is_bpf_throw_kfunc(insn))
                return process_bpf_exit_full(env, NULL, true);

        return 0;
}

static bool check_reg_sane_offset_scalar(struct bpf_verifier_env *env,
                                         const struct bpf_reg_state *reg,
                                         enum bpf_reg_type type)
{
        bool known = tnum_is_const(reg->var_off);
        s64 val = reg->var_off.value;
        s64 smin = reg->smin_value;

        if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
                verbose(env, "math between %s pointer and %lld is not allowed\n",
                        reg_type_str(env, type), val);
                return false;
        }

        if (smin == S64_MIN) {
                verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
                        reg_type_str(env, type));
                return false;
        }

        if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
                verbose(env, "value %lld makes %s pointer be out of bounds\n",
                        smin, reg_type_str(env, type));
                return false;
        }

        return true;
}

static bool check_reg_sane_offset_ptr(struct bpf_verifier_env *env,
                                      const struct bpf_reg_state *reg,
                                      enum bpf_reg_type type)
{
        bool known = tnum_is_const(reg->var_off);
        s64 val = reg->var_off.value;
        s64 smin = reg->smin_value;

        if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
                verbose(env, "%s pointer offset %lld is not allowed\n",
                        reg_type_str(env, type), val);
                return false;
        }

        if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
                verbose(env, "%s pointer offset %lld is not allowed\n",
                        reg_type_str(env, type), smin);
                return false;
        }

        return true;
}

enum {
        REASON_BOUNDS   = -1,
        REASON_TYPE     = -2,
        REASON_PATHS    = -3,
        REASON_LIMIT    = -4,
        REASON_STACK    = -5,
};

static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
                              u32 *alu_limit, bool mask_to_left)
{
        u32 max = 0, ptr_limit = 0;

        switch (ptr_reg->type) {
        case PTR_TO_STACK:
                /* Offset 0 is out-of-bounds, but acceptable start for the
                 * left direction, see BPF_REG_FP. Also, unknown scalar
                 * offset where we would need to deal with min/max bounds is
                 * currently prohibited for unprivileged.
                 */
                max = MAX_BPF_STACK + mask_to_left;
                ptr_limit = -ptr_reg->var_off.value;
                break;
        case PTR_TO_MAP_VALUE:
                max = ptr_reg->map_ptr->value_size;
                ptr_limit = mask_to_left ? ptr_reg->smin_value : ptr_reg->umax_value;
                break;
        default:
                return REASON_TYPE;
        }

        if (ptr_limit >= max)
                return REASON_LIMIT;
        *alu_limit = ptr_limit;
        return 0;
}

static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
                                    const struct bpf_insn *insn)
{
        return env->bypass_spec_v1 ||
                BPF_SRC(insn->code) == BPF_K ||
                cur_aux(env)->nospec;
}

static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
                                       u32 alu_state, u32 alu_limit)
{
        /* If we arrived here from different branches with different
         * state or limits to sanitize, then this won't work.
         */
        if (aux->alu_state &&
            (aux->alu_state != alu_state ||
             aux->alu_limit != alu_limit))
                return REASON_PATHS;

        /* Corresponding fixup done in do_misc_fixups(). */
        aux->alu_state = alu_state;
        aux->alu_limit = alu_limit;
        return 0;
}

static int sanitize_val_alu(struct bpf_verifier_env *env,
                            struct bpf_insn *insn)
{
        struct bpf_insn_aux_data *aux = cur_aux(env);

        if (can_skip_alu_sanitation(env, insn))
                return 0;

        return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}

static bool sanitize_needed(u8 opcode)
{
        return opcode == BPF_ADD || opcode == BPF_SUB;
}

struct bpf_sanitize_info {
        struct bpf_insn_aux_data aux;
        bool mask_to_left;
};

static int sanitize_speculative_path(struct bpf_verifier_env *env,
                                     const struct bpf_insn *insn,
                                     u32 next_idx, u32 curr_idx)
{
        struct bpf_verifier_state *branch;
        struct bpf_reg_state *regs;

        branch = push_stack(env, next_idx, curr_idx, true);
        if (!IS_ERR(branch) && insn) {
                regs = branch->frame[branch->curframe]->regs;
                if (BPF_SRC(insn->code) == BPF_K) {
                        mark_reg_unknown(env, regs, insn->dst_reg);
                } else if (BPF_SRC(insn->code) == BPF_X) {
                        mark_reg_unknown(env, regs, insn->dst_reg);
                        mark_reg_unknown(env, regs, insn->src_reg);
                }
        }
        return PTR_ERR_OR_ZERO(branch);
}

static int sanitize_ptr_alu(struct bpf_verifier_env *env,
                            struct bpf_insn *insn,
                            const struct bpf_reg_state *ptr_reg,
                            const struct bpf_reg_state *off_reg,
                            struct bpf_reg_state *dst_reg,
                            struct bpf_sanitize_info *info,
                            const bool commit_window)
{
        struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
        struct bpf_verifier_state *vstate = env->cur_state;
        bool off_is_imm = tnum_is_const(off_reg->var_off);
        bool off_is_neg = off_reg->smin_value < 0;
        bool ptr_is_dst_reg = ptr_reg == dst_reg;
        u8 opcode = BPF_OP(insn->code);
        u32 alu_state, alu_limit;
        struct bpf_reg_state tmp;
        int err;

        if (can_skip_alu_sanitation(env, insn))
                return 0;

        /* We already marked aux for masking from non-speculative
         * paths, thus we got here in the first place. We only care
         * to explore bad access from here.
         */
        if (vstate->speculative)
                goto do_sim;

        if (!commit_window) {
                if (!tnum_is_const(off_reg->var_off) &&
                    (off_reg->smin_value < 0) != (off_reg->smax_value < 0))
                        return REASON_BOUNDS;

                info->mask_to_left = (opcode == BPF_ADD &&  off_is_neg) ||
                                     (opcode == BPF_SUB && !off_is_neg);
        }

        err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
        if (err < 0)
                return err;

        if (commit_window) {
                /* In commit phase we narrow the masking window based on
                 * the observed pointer move after the simulated operation.
                 */
                alu_state = info->aux.alu_state;
                alu_limit = abs(info->aux.alu_limit - alu_limit);
        } else {
                alu_state  = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
                alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
                alu_state |= ptr_is_dst_reg ?
                             BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;

                /* Limit pruning on unknown scalars to enable deep search for
                 * potential masking differences from other program paths.
                 */
                if (!off_is_imm)
                        env->explore_alu_limits = true;
        }

        err = update_alu_sanitation_state(aux, alu_state, alu_limit);
        if (err < 0)
                return err;
do_sim:
        /* If we're in commit phase, we're done here given we already
         * pushed the truncated dst_reg into the speculative verification
         * stack.
         *
         * Also, when register is a known constant, we rewrite register-based
         * operation to immediate-based, and thus do not need masking (and as
         * a consequence, do not need to simulate the zero-truncation either).
         */
        if (commit_window || off_is_imm)
                return 0;

        /* Simulate and find potential out-of-bounds access under
         * speculative execution from truncation as a result of
         * masking when off was not within expected range. If off
         * sits in dst, then we temporarily need to move ptr there
         * to simulate dst (== 0) +/-= ptr. Needed, for example,
         * for cases where we use K-based arithmetic in one direction
         * and truncated reg-based in the other in order to explore
         * bad access.
         */
        if (!ptr_is_dst_reg) {
                tmp = *dst_reg;
                copy_register_state(dst_reg, ptr_reg);
        }
        err = sanitize_speculative_path(env, NULL, env->insn_idx + 1, env->insn_idx);
        if (err < 0)
                return REASON_STACK;
        if (!ptr_is_dst_reg)
                *dst_reg = tmp;
        return 0;
}

static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
{
        struct bpf_verifier_state *vstate = env->cur_state;

        /* If we simulate paths under speculation, we don't update the
         * insn as 'seen' such that when we verify unreachable paths in
         * the non-speculative domain, sanitize_dead_code() can still
         * rewrite/sanitize them.
         */
        if (!vstate->speculative)
                env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
}

static int sanitize_err(struct bpf_verifier_env *env,
                        const struct bpf_insn *insn, int reason,
                        const struct bpf_reg_state *off_reg,
                        const struct bpf_reg_state *dst_reg)
{
        static const char *err = "pointer arithmetic with it prohibited for !root";
        const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
        u32 dst = insn->dst_reg, src = insn->src_reg;

        switch (reason) {
        case REASON_BOUNDS:
                verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
                        off_reg == dst_reg ? dst : src, err);
                break;
        case REASON_TYPE:
                verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
                        off_reg == dst_reg ? src : dst, err);
                break;
        case REASON_PATHS:
                verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
                        dst, op, err);
                break;
        case REASON_LIMIT:
                verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
                        dst, op, err);
                break;
        case REASON_STACK:
                verbose(env, "R%d could not be pushed for speculative verification, %s\n",
                        dst, err);
                return -ENOMEM;
        default:
                verifier_bug(env, "unknown reason (%d)", reason);
                break;
        }

        return -EACCES;
}

/* check that stack access falls within stack limits and that 'reg' doesn't
 * have a variable offset.
 *
 * Variable offset is prohibited for unprivileged mode for simplicity since it
 * requires corresponding support in Spectre masking for stack ALU.  See also
 * retrieve_ptr_limit().
 */
static int check_stack_access_for_ptr_arithmetic(
                                struct bpf_verifier_env *env,
                                int regno,
                                const struct bpf_reg_state *reg,
                                int off)
{
        if (!tnum_is_const(reg->var_off)) {
                char tn_buf[48];

                tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
                        regno, tn_buf, off);
                return -EACCES;
        }

        if (off >= 0 || off < -MAX_BPF_STACK) {
                verbose(env, "R%d stack pointer arithmetic goes out of range, "
                        "prohibited for !root; off=%d\n", regno, off);
                return -EACCES;
        }

        return 0;
}

static int sanitize_check_bounds(struct bpf_verifier_env *env,
                                 const struct bpf_insn *insn,
                                 const struct bpf_reg_state *dst_reg)
{
        u32 dst = insn->dst_reg;

        /* For unprivileged we require that resulting offset must be in bounds
         * in order to be able to sanitize access later on.
         */
        if (env->bypass_spec_v1)
                return 0;

        switch (dst_reg->type) {
        case PTR_TO_STACK:
                if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
                                                          dst_reg->var_off.value))
                        return -EACCES;
                break;
        case PTR_TO_MAP_VALUE:
                if (check_map_access(env, dst, 0, 1, false, ACCESS_HELPER)) {
                        verbose(env, "R%d pointer arithmetic of map value goes out of range, "
                                "prohibited for !root\n", dst);
                        return -EACCES;
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
 * Caller should also handle BPF_MOV case separately.
 * If we return -EACCES, caller may want to try again treating pointer as a
 * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
 */
static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
                                   struct bpf_insn *insn,
                                   const struct bpf_reg_state *ptr_reg,
                                   const struct bpf_reg_state *off_reg)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *regs = state->regs, *dst_reg;
        bool known = tnum_is_const(off_reg->var_off);
        s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
            smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
        u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
            umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
        struct bpf_sanitize_info info = {};
        u8 opcode = BPF_OP(insn->code);
        u32 dst = insn->dst_reg;
        int ret, bounds_ret;

        dst_reg = &regs[dst];

        if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
            smin_val > smax_val || umin_val > umax_val) {
                /* Taint dst register if offset had invalid bounds derived from
                 * e.g. dead branches.
                 */
                __mark_reg_unknown(env, dst_reg);
                return 0;
        }

        if (BPF_CLASS(insn->code) != BPF_ALU64) {
                /* 32-bit ALU ops on pointers produce (meaningless) scalars */
                if (opcode == BPF_SUB && env->allow_ptr_leaks) {
                        __mark_reg_unknown(env, dst_reg);
                        return 0;
                }

                verbose(env,
                        "R%d 32-bit pointer arithmetic prohibited\n",
                        dst);
                return -EACCES;
        }

        if (ptr_reg->type & PTR_MAYBE_NULL) {
                verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
                        dst, reg_type_str(env, ptr_reg->type));
                return -EACCES;
        }

        /*
         * Accesses to untrusted PTR_TO_MEM are done through probe
         * instructions, hence no need to track offsets.
         */
        if (base_type(ptr_reg->type) == PTR_TO_MEM && (ptr_reg->type & PTR_UNTRUSTED))
                return 0;

        switch (base_type(ptr_reg->type)) {
        case PTR_TO_CTX:
        case PTR_TO_MAP_VALUE:
        case PTR_TO_MAP_KEY:
        case PTR_TO_STACK:
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET:
        case PTR_TO_TP_BUFFER:
        case PTR_TO_BTF_ID:
        case PTR_TO_MEM:
        case PTR_TO_BUF:
        case PTR_TO_FUNC:
        case CONST_PTR_TO_DYNPTR:
                break;
        case PTR_TO_FLOW_KEYS:
                if (known)
                        break;
                fallthrough;
        case CONST_PTR_TO_MAP:
                /* smin_val represents the known value */
                if (known && smin_val == 0 && opcode == BPF_ADD)
                        break;
                fallthrough;
        default:
                verbose(env, "R%d pointer arithmetic on %s prohibited\n",
                        dst, reg_type_str(env, ptr_reg->type));
                return -EACCES;
        }

        /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
         * The id may be overwritten later if we create a new variable offset.
         */
        dst_reg->type = ptr_reg->type;
        dst_reg->id = ptr_reg->id;

        if (!check_reg_sane_offset_scalar(env, off_reg, ptr_reg->type) ||
            !check_reg_sane_offset_ptr(env, ptr_reg, ptr_reg->type))
                return -EINVAL;

        /* pointer types do not carry 32-bit bounds at the moment. */
        __mark_reg32_unbounded(dst_reg);

        if (sanitize_needed(opcode)) {
                ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
                                       &info, false);
                if (ret < 0)
                        return sanitize_err(env, insn, ret, off_reg, dst_reg);
        }

        switch (opcode) {
        case BPF_ADD:
                /*
                 * dst_reg gets the pointer type and since some positive
                 * integer value was added to the pointer, give it a new 'id'
                 * if it's a PTR_TO_PACKET.
                 * this creates a new 'base' pointer, off_reg (variable) gets
                 * added into the variable offset, and we copy the fixed offset
                 * from ptr_reg.
                 */
                if (check_add_overflow(smin_ptr, smin_val, &dst_reg->smin_value) ||
                    check_add_overflow(smax_ptr, smax_val, &dst_reg->smax_value)) {
                        dst_reg->smin_value = S64_MIN;
                        dst_reg->smax_value = S64_MAX;
                }
                if (check_add_overflow(umin_ptr, umin_val, &dst_reg->umin_value) ||
                    check_add_overflow(umax_ptr, umax_val, &dst_reg->umax_value)) {
                        dst_reg->umin_value = 0;
                        dst_reg->umax_value = U64_MAX;
                }
                dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
                dst_reg->raw = ptr_reg->raw;
                if (reg_is_pkt_pointer(ptr_reg)) {
                        if (!known)
                                dst_reg->id = ++env->id_gen;
                        /*
                         * Clear range for unknown addends since we can't know
                         * where the pkt pointer ended up. Also clear AT_PKT_END /
                         * BEYOND_PKT_END from prior comparison as any pointer
                         * arithmetic invalidates them.
                         */
                        if (!known || dst_reg->range < 0)
                                memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
                }
                break;
        case BPF_SUB:
                if (dst_reg == off_reg) {
                        /* scalar -= pointer.  Creates an unknown scalar */
                        verbose(env, "R%d tried to subtract pointer from scalar\n",
                                dst);
                        return -EACCES;
                }
                /* We don't allow subtraction from FP, because (according to
                 * test_verifier.c test "invalid fp arithmetic", JITs might not
                 * be able to deal with it.
                 */
                if (ptr_reg->type == PTR_TO_STACK) {
                        verbose(env, "R%d subtraction from stack pointer prohibited\n",
                                dst);
                        return -EACCES;
                }
                /* A new variable offset is created.  If the subtrahend is known
                 * nonnegative, then any reg->range we had before is still good.
                 */
                if (check_sub_overflow(smin_ptr, smax_val, &dst_reg->smin_value) ||
                    check_sub_overflow(smax_ptr, smin_val, &dst_reg->smax_value)) {
                        /* Overflow possible, we know nothing */
                        dst_reg->smin_value = S64_MIN;
                        dst_reg->smax_value = S64_MAX;
                }
                if (umin_ptr < umax_val) {
                        /* Overflow possible, we know nothing */
                        dst_reg->umin_value = 0;
                        dst_reg->umax_value = U64_MAX;
                } else {
                        /* Cannot overflow (as long as bounds are consistent) */
                        dst_reg->umin_value = umin_ptr - umax_val;
                        dst_reg->umax_value = umax_ptr - umin_val;
                }
                dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
                dst_reg->raw = ptr_reg->raw;
                if (reg_is_pkt_pointer(ptr_reg)) {
                        if (!known)
                                dst_reg->id = ++env->id_gen;
                        /*
                         * Clear range if the subtrahend may be negative since
                         * pkt pointer could move past its bounds. A positive
                         * subtrahend moves it backwards keeping positive range
                         * intact. Also clear AT_PKT_END / BEYOND_PKT_END from
                         * prior comparison as arithmetic invalidates them.
                         */
                        if ((!known && smin_val < 0) || dst_reg->range < 0)
                                memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
                }
                break;
        case BPF_AND:
        case BPF_OR:
        case BPF_XOR:
                /* bitwise ops on pointers are troublesome, prohibit. */
                verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
                        dst, bpf_alu_string[opcode >> 4]);
                return -EACCES;
        default:
                /* other operators (e.g. MUL,LSH) produce non-pointer results */
                verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
                        dst, bpf_alu_string[opcode >> 4]);
                return -EACCES;
        }

        if (!check_reg_sane_offset_ptr(env, dst_reg, ptr_reg->type))
                return -EINVAL;
        reg_bounds_sync(dst_reg);
        bounds_ret = sanitize_check_bounds(env, insn, dst_reg);
        if (bounds_ret == -EACCES)
                return bounds_ret;
        if (sanitize_needed(opcode)) {
                ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
                                       &info, true);
                if (verifier_bug_if(!can_skip_alu_sanitation(env, insn)
                                    && !env->cur_state->speculative
                                    && bounds_ret
                                    && !ret,
                                    env, "Pointer type unsupported by sanitize_check_bounds() not rejected by retrieve_ptr_limit() as required")) {
                        return -EFAULT;
                }
                if (ret < 0)
                        return sanitize_err(env, insn, ret, off_reg, dst_reg);
        }

        return 0;
}

static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        s32 *dst_smin = &dst_reg->s32_min_value;
        s32 *dst_smax = &dst_reg->s32_max_value;
        u32 *dst_umin = &dst_reg->u32_min_value;
        u32 *dst_umax = &dst_reg->u32_max_value;
        u32 umin_val = src_reg->u32_min_value;
        u32 umax_val = src_reg->u32_max_value;
        bool min_overflow, max_overflow;

        if (check_add_overflow(*dst_smin, src_reg->s32_min_value, dst_smin) ||
            check_add_overflow(*dst_smax, src_reg->s32_max_value, dst_smax)) {
                *dst_smin = S32_MIN;
                *dst_smax = S32_MAX;
        }

        /* If either all additions overflow or no additions overflow, then
         * it is okay to set: dst_umin = dst_umin + src_umin, dst_umax =
         * dst_umax + src_umax. Otherwise (some additions overflow), set
         * the output bounds to unbounded.
         */
        min_overflow = check_add_overflow(*dst_umin, umin_val, dst_umin);
        max_overflow = check_add_overflow(*dst_umax, umax_val, dst_umax);

        if (!min_overflow && max_overflow) {
                *dst_umin = 0;
                *dst_umax = U32_MAX;
        }
}

static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        s64 *dst_smin = &dst_reg->smin_value;
        s64 *dst_smax = &dst_reg->smax_value;
        u64 *dst_umin = &dst_reg->umin_value;
        u64 *dst_umax = &dst_reg->umax_value;
        u64 umin_val = src_reg->umin_value;
        u64 umax_val = src_reg->umax_value;
        bool min_overflow, max_overflow;

        if (check_add_overflow(*dst_smin, src_reg->smin_value, dst_smin) ||
            check_add_overflow(*dst_smax, src_reg->smax_value, dst_smax)) {
                *dst_smin = S64_MIN;
                *dst_smax = S64_MAX;
        }

        /* If either all additions overflow or no additions overflow, then
         * it is okay to set: dst_umin = dst_umin + src_umin, dst_umax =
         * dst_umax + src_umax. Otherwise (some additions overflow), set
         * the output bounds to unbounded.
         */
        min_overflow = check_add_overflow(*dst_umin, umin_val, dst_umin);
        max_overflow = check_add_overflow(*dst_umax, umax_val, dst_umax);

        if (!min_overflow && max_overflow) {
                *dst_umin = 0;
                *dst_umax = U64_MAX;
        }
}

static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        s32 *dst_smin = &dst_reg->s32_min_value;
        s32 *dst_smax = &dst_reg->s32_max_value;
        u32 *dst_umin = &dst_reg->u32_min_value;
        u32 *dst_umax = &dst_reg->u32_max_value;
        u32 umin_val = src_reg->u32_min_value;
        u32 umax_val = src_reg->u32_max_value;
        bool min_underflow, max_underflow;

        if (check_sub_overflow(*dst_smin, src_reg->s32_max_value, dst_smin) ||
            check_sub_overflow(*dst_smax, src_reg->s32_min_value, dst_smax)) {
                /* Overflow possible, we know nothing */
                *dst_smin = S32_MIN;
                *dst_smax = S32_MAX;
        }

        /* If either all subtractions underflow or no subtractions
         * underflow, it is okay to set: dst_umin = dst_umin - src_umax,
         * dst_umax = dst_umax - src_umin. Otherwise (some subtractions
         * underflow), set the output bounds to unbounded.
         */
        min_underflow = check_sub_overflow(*dst_umin, umax_val, dst_umin);
        max_underflow = check_sub_overflow(*dst_umax, umin_val, dst_umax);

        if (min_underflow && !max_underflow) {
                *dst_umin = 0;
                *dst_umax = U32_MAX;
        }
}

static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        s64 *dst_smin = &dst_reg->smin_value;
        s64 *dst_smax = &dst_reg->smax_value;
        u64 *dst_umin = &dst_reg->umin_value;
        u64 *dst_umax = &dst_reg->umax_value;
        u64 umin_val = src_reg->umin_value;
        u64 umax_val = src_reg->umax_value;
        bool min_underflow, max_underflow;

        if (check_sub_overflow(*dst_smin, src_reg->smax_value, dst_smin) ||
            check_sub_overflow(*dst_smax, src_reg->smin_value, dst_smax)) {
                /* Overflow possible, we know nothing */
                *dst_smin = S64_MIN;
                *dst_smax = S64_MAX;
        }

        /* If either all subtractions underflow or no subtractions
         * underflow, it is okay to set: dst_umin = dst_umin - src_umax,
         * dst_umax = dst_umax - src_umin. Otherwise (some subtractions
         * underflow), set the output bounds to unbounded.
         */
        min_underflow = check_sub_overflow(*dst_umin, umax_val, dst_umin);
        max_underflow = check_sub_overflow(*dst_umax, umin_val, dst_umax);

        if (min_underflow && !max_underflow) {
                *dst_umin = 0;
                *dst_umax = U64_MAX;
        }
}

static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        s32 *dst_smin = &dst_reg->s32_min_value;
        s32 *dst_smax = &dst_reg->s32_max_value;
        u32 *dst_umin = &dst_reg->u32_min_value;
        u32 *dst_umax = &dst_reg->u32_max_value;
        s32 tmp_prod[4];

        if (check_mul_overflow(*dst_umax, src_reg->u32_max_value, dst_umax) ||
            check_mul_overflow(*dst_umin, src_reg->u32_min_value, dst_umin)) {
                /* Overflow possible, we know nothing */
                *dst_umin = 0;
                *dst_umax = U32_MAX;
        }
        if (check_mul_overflow(*dst_smin, src_reg->s32_min_value, &tmp_prod[0]) ||
            check_mul_overflow(*dst_smin, src_reg->s32_max_value, &tmp_prod[1]) ||
            check_mul_overflow(*dst_smax, src_reg->s32_min_value, &tmp_prod[2]) ||
            check_mul_overflow(*dst_smax, src_reg->s32_max_value, &tmp_prod[3])) {
                /* Overflow possible, we know nothing */
                *dst_smin = S32_MIN;
                *dst_smax = S32_MAX;
        } else {
                *dst_smin = min_array(tmp_prod, 4);
                *dst_smax = max_array(tmp_prod, 4);
        }
}

static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        s64 *dst_smin = &dst_reg->smin_value;
        s64 *dst_smax = &dst_reg->smax_value;
        u64 *dst_umin = &dst_reg->umin_value;
        u64 *dst_umax = &dst_reg->umax_value;
        s64 tmp_prod[4];

        if (check_mul_overflow(*dst_umax, src_reg->umax_value, dst_umax) ||
            check_mul_overflow(*dst_umin, src_reg->umin_value, dst_umin)) {
                /* Overflow possible, we know nothing */
                *dst_umin = 0;
                *dst_umax = U64_MAX;
        }
        if (check_mul_overflow(*dst_smin, src_reg->smin_value, &tmp_prod[0]) ||
            check_mul_overflow(*dst_smin, src_reg->smax_value, &tmp_prod[1]) ||
            check_mul_overflow(*dst_smax, src_reg->smin_value, &tmp_prod[2]) ||
            check_mul_overflow(*dst_smax, src_reg->smax_value, &tmp_prod[3])) {
                /* Overflow possible, we know nothing */
                *dst_smin = S64_MIN;
                *dst_smax = S64_MAX;
        } else {
                *dst_smin = min_array(tmp_prod, 4);
                *dst_smax = max_array(tmp_prod, 4);
        }
}

static void scalar32_min_max_udiv(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
{
        u32 *dst_umin = &dst_reg->u32_min_value;
        u32 *dst_umax = &dst_reg->u32_max_value;
        u32 src_val = src_reg->u32_min_value; /* non-zero, const divisor */

        *dst_umin = *dst_umin / src_val;
        *dst_umax = *dst_umax / src_val;

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
        reset_reg64_and_tnum(dst_reg);
}

static void scalar_min_max_udiv(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        u64 *dst_umin = &dst_reg->umin_value;
        u64 *dst_umax = &dst_reg->umax_value;
        u64 src_val = src_reg->umin_value; /* non-zero, const divisor */

        *dst_umin = div64_u64(*dst_umin, src_val);
        *dst_umax = div64_u64(*dst_umax, src_val);

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
        reset_reg32_and_tnum(dst_reg);
}

static void scalar32_min_max_sdiv(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
{
        s32 *dst_smin = &dst_reg->s32_min_value;
        s32 *dst_smax = &dst_reg->s32_max_value;
        s32 src_val = src_reg->s32_min_value; /* non-zero, const divisor */
        s32 res1, res2;

        /* BPF div specification: S32_MIN / -1 = S32_MIN */
        if (*dst_smin == S32_MIN && src_val == -1) {
                /*
                 * If the dividend range contains more than just S32_MIN,
                 * we cannot precisely track the result, so it becomes unbounded.
                 * e.g., [S32_MIN, S32_MIN+10]/(-1),
                 *     = {S32_MIN} U [-(S32_MIN+10), -(S32_MIN+1)]
                 *     = {S32_MIN} U [S32_MAX-9, S32_MAX] = [S32_MIN, S32_MAX]
                 * Otherwise (if dividend is exactly S32_MIN), result remains S32_MIN.
                 */
                if (*dst_smax != S32_MIN) {
                        *dst_smin = S32_MIN;
                        *dst_smax = S32_MAX;
                }
                goto reset;
        }

        res1 = *dst_smin / src_val;
        res2 = *dst_smax / src_val;
        *dst_smin = min(res1, res2);
        *dst_smax = max(res1, res2);

reset:
        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;
        reset_reg64_and_tnum(dst_reg);
}

static void scalar_min_max_sdiv(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        s64 *dst_smin = &dst_reg->smin_value;
        s64 *dst_smax = &dst_reg->smax_value;
        s64 src_val = src_reg->smin_value; /* non-zero, const divisor */
        s64 res1, res2;

        /* BPF div specification: S64_MIN / -1 = S64_MIN */
        if (*dst_smin == S64_MIN && src_val == -1) {
                /*
                 * If the dividend range contains more than just S64_MIN,
                 * we cannot precisely track the result, so it becomes unbounded.
                 * e.g., [S64_MIN, S64_MIN+10]/(-1),
                 *     = {S64_MIN} U [-(S64_MIN+10), -(S64_MIN+1)]
                 *     = {S64_MIN} U [S64_MAX-9, S64_MAX] = [S64_MIN, S64_MAX]
                 * Otherwise (if dividend is exactly S64_MIN), result remains S64_MIN.
                 */
                if (*dst_smax != S64_MIN) {
                        *dst_smin = S64_MIN;
                        *dst_smax = S64_MAX;
                }
                goto reset;
        }

        res1 = div64_s64(*dst_smin, src_val);
        res2 = div64_s64(*dst_smax, src_val);
        *dst_smin = min(res1, res2);
        *dst_smax = max(res1, res2);

reset:
        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;
        reset_reg32_and_tnum(dst_reg);
}

static void scalar32_min_max_umod(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
{
        u32 *dst_umin = &dst_reg->u32_min_value;
        u32 *dst_umax = &dst_reg->u32_max_value;
        u32 src_val = src_reg->u32_min_value; /* non-zero, const divisor */
        u32 res_max = src_val - 1;

        /*
         * If dst_umax <= res_max, the result remains unchanged.
         * e.g., [2, 5] % 10 = [2, 5].
         */
        if (*dst_umax <= res_max)
                return;

        *dst_umin = 0;
        *dst_umax = min(*dst_umax, res_max);

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
        reset_reg64_and_tnum(dst_reg);
}

static void scalar_min_max_umod(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        u64 *dst_umin = &dst_reg->umin_value;
        u64 *dst_umax = &dst_reg->umax_value;
        u64 src_val = src_reg->umin_value; /* non-zero, const divisor */
        u64 res_max = src_val - 1;

        /*
         * If dst_umax <= res_max, the result remains unchanged.
         * e.g., [2, 5] % 10 = [2, 5].
         */
        if (*dst_umax <= res_max)
                return;

        *dst_umin = 0;
        *dst_umax = min(*dst_umax, res_max);

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
        reset_reg32_and_tnum(dst_reg);
}

static void scalar32_min_max_smod(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
{
        s32 *dst_smin = &dst_reg->s32_min_value;
        s32 *dst_smax = &dst_reg->s32_max_value;
        s32 src_val = src_reg->s32_min_value; /* non-zero, const divisor */

        /*
         * Safe absolute value calculation:
         * If src_val == S32_MIN (-2147483648), src_abs becomes 2147483648.
         * Here use unsigned integer to avoid overflow.
         */
        u32 src_abs = (src_val > 0) ? (u32)src_val : -(u32)src_val;

        /*
         * Calculate the maximum possible absolute value of the result.
         * Even if src_abs is 2147483648 (S32_MIN), subtracting 1 gives
         * 2147483647 (S32_MAX), which fits perfectly in s32.
         */
        s32 res_max_abs = src_abs - 1;

        /*
         * If the dividend is already within the result range,
         * the result remains unchanged. e.g., [-2, 5] % 10 = [-2, 5].
         */
        if (*dst_smin >= -res_max_abs && *dst_smax <= res_max_abs)
                return;

        /* General case: result has the same sign as the dividend. */
        if (*dst_smin >= 0) {
                *dst_smin = 0;
                *dst_smax = min(*dst_smax, res_max_abs);
        } else if (*dst_smax <= 0) {
                *dst_smax = 0;
                *dst_smin = max(*dst_smin, -res_max_abs);
        } else {
                *dst_smin = -res_max_abs;
                *dst_smax = res_max_abs;
        }

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;
        reset_reg64_and_tnum(dst_reg);
}

static void scalar_min_max_smod(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        s64 *dst_smin = &dst_reg->smin_value;
        s64 *dst_smax = &dst_reg->smax_value;
        s64 src_val = src_reg->smin_value; /* non-zero, const divisor */

        /*
         * Safe absolute value calculation:
         * If src_val == S64_MIN (-2^63), src_abs becomes 2^63.
         * Here use unsigned integer to avoid overflow.
         */
        u64 src_abs = (src_val > 0) ? (u64)src_val : -(u64)src_val;

        /*
         * Calculate the maximum possible absolute value of the result.
         * Even if src_abs is 2^63 (S64_MIN), subtracting 1 gives
         * 2^63 - 1 (S64_MAX), which fits perfectly in s64.
         */
        s64 res_max_abs = src_abs - 1;

        /*
         * If the dividend is already within the result range,
         * the result remains unchanged. e.g., [-2, 5] % 10 = [-2, 5].
         */
        if (*dst_smin >= -res_max_abs && *dst_smax <= res_max_abs)
                return;

        /* General case: result has the same sign as the dividend. */
        if (*dst_smin >= 0) {
                *dst_smin = 0;
                *dst_smax = min(*dst_smax, res_max_abs);
        } else if (*dst_smax <= 0) {
                *dst_smax = 0;
                *dst_smin = max(*dst_smin, -res_max_abs);
        } else {
                *dst_smin = -res_max_abs;
                *dst_smax = res_max_abs;
        }

        /* Reset other ranges/tnum to unbounded/unknown. */
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;
        reset_reg32_and_tnum(dst_reg);
}

static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_subreg_is_const(src_reg->var_off);
        bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
        struct tnum var32_off = tnum_subreg(dst_reg->var_off);
        u32 umax_val = src_reg->u32_max_value;

        if (src_known && dst_known) {
                __mark_reg32_known(dst_reg, var32_off.value);
                return;
        }

        /* We get our minimum from the var_off, since that's inherently
         * bitwise.  Our maximum is the minimum of the operands' maxima.
         */
        dst_reg->u32_min_value = var32_off.value;
        dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);

        /* Safe to set s32 bounds by casting u32 result into s32 when u32
         * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
         */
        if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                dst_reg->s32_min_value = dst_reg->u32_min_value;
                dst_reg->s32_max_value = dst_reg->u32_max_value;
        } else {
                dst_reg->s32_min_value = S32_MIN;
                dst_reg->s32_max_value = S32_MAX;
        }
}

static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_is_const(src_reg->var_off);
        bool dst_known = tnum_is_const(dst_reg->var_off);
        u64 umax_val = src_reg->umax_value;

        if (src_known && dst_known) {
                __mark_reg_known(dst_reg, dst_reg->var_off.value);
                return;
        }

        /* We get our minimum from the var_off, since that's inherently
         * bitwise.  Our maximum is the minimum of the operands' maxima.
         */
        dst_reg->umin_value = dst_reg->var_off.value;
        dst_reg->umax_value = min(dst_reg->umax_value, umax_val);

        /* Safe to set s64 bounds by casting u64 result into s64 when u64
         * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
         */
        if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                dst_reg->smin_value = dst_reg->umin_value;
                dst_reg->smax_value = dst_reg->umax_value;
        } else {
                dst_reg->smin_value = S64_MIN;
                dst_reg->smax_value = S64_MAX;
        }
        /* We may learn something more from the var_off */
        __update_reg_bounds(dst_reg);
}

static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_subreg_is_const(src_reg->var_off);
        bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
        struct tnum var32_off = tnum_subreg(dst_reg->var_off);
        u32 umin_val = src_reg->u32_min_value;

        if (src_known && dst_known) {
                __mark_reg32_known(dst_reg, var32_off.value);
                return;
        }

        /* We get our maximum from the var_off, and our minimum is the
         * maximum of the operands' minima
         */
        dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
        dst_reg->u32_max_value = var32_off.value | var32_off.mask;

        /* Safe to set s32 bounds by casting u32 result into s32 when u32
         * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
         */
        if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                dst_reg->s32_min_value = dst_reg->u32_min_value;
                dst_reg->s32_max_value = dst_reg->u32_max_value;
        } else {
                dst_reg->s32_min_value = S32_MIN;
                dst_reg->s32_max_value = S32_MAX;
        }
}

static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
                              struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_is_const(src_reg->var_off);
        bool dst_known = tnum_is_const(dst_reg->var_off);
        u64 umin_val = src_reg->umin_value;

        if (src_known && dst_known) {
                __mark_reg_known(dst_reg, dst_reg->var_off.value);
                return;
        }

        /* We get our maximum from the var_off, and our minimum is the
         * maximum of the operands' minima
         */
        dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
        dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;

        /* Safe to set s64 bounds by casting u64 result into s64 when u64
         * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
         */
        if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                dst_reg->smin_value = dst_reg->umin_value;
                dst_reg->smax_value = dst_reg->umax_value;
        } else {
                dst_reg->smin_value = S64_MIN;
                dst_reg->smax_value = S64_MAX;
        }
        /* We may learn something more from the var_off */
        __update_reg_bounds(dst_reg);
}

static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_subreg_is_const(src_reg->var_off);
        bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
        struct tnum var32_off = tnum_subreg(dst_reg->var_off);

        if (src_known && dst_known) {
                __mark_reg32_known(dst_reg, var32_off.value);
                return;
        }

        /* We get both minimum and maximum from the var32_off. */
        dst_reg->u32_min_value = var32_off.value;
        dst_reg->u32_max_value = var32_off.value | var32_off.mask;

        /* Safe to set s32 bounds by casting u32 result into s32 when u32
         * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
         */
        if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
                dst_reg->s32_min_value = dst_reg->u32_min_value;
                dst_reg->s32_max_value = dst_reg->u32_max_value;
        } else {
                dst_reg->s32_min_value = S32_MIN;
                dst_reg->s32_max_value = S32_MAX;
        }
}

static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        bool src_known = tnum_is_const(src_reg->var_off);
        bool dst_known = tnum_is_const(dst_reg->var_off);

        if (src_known && dst_known) {
                /* dst_reg->var_off.value has been updated earlier */
                __mark_reg_known(dst_reg, dst_reg->var_off.value);
                return;
        }

        /* We get both minimum and maximum from the var_off. */
        dst_reg->umin_value = dst_reg->var_off.value;
        dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;

        /* Safe to set s64 bounds by casting u64 result into s64 when u64
         * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
         */
        if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
                dst_reg->smin_value = dst_reg->umin_value;
                dst_reg->smax_value = dst_reg->umax_value;
        } else {
                dst_reg->smin_value = S64_MIN;
                dst_reg->smax_value = S64_MAX;
        }

        __update_reg_bounds(dst_reg);
}

static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
                                   u64 umin_val, u64 umax_val)
{
        /* We lose all sign bit information (except what we can pick
         * up from var_off)
         */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
        /* If we might shift our top bit out, then we know nothing */
        if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
                dst_reg->u32_min_value = 0;
                dst_reg->u32_max_value = U32_MAX;
        } else {
                dst_reg->u32_min_value <<= umin_val;
                dst_reg->u32_max_value <<= umax_val;
        }
}

static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        u32 umax_val = src_reg->u32_max_value;
        u32 umin_val = src_reg->u32_min_value;
        /* u32 alu operation will zext upper bits */
        struct tnum subreg = tnum_subreg(dst_reg->var_off);

        __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
        dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
        /* Not required but being careful mark reg64 bounds as unknown so
         * that we are forced to pick them up from tnum and zext later and
         * if some path skips this step we are still safe.
         */
        __mark_reg64_unbounded(dst_reg);
        __update_reg32_bounds(dst_reg);
}

static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
                                   u64 umin_val, u64 umax_val)
{
        /* Special case <<32 because it is a common compiler pattern to sign
         * extend subreg by doing <<32 s>>32. smin/smax assignments are correct
         * because s32 bounds don't flip sign when shifting to the left by
         * 32bits.
         */
        if (umin_val == 32 && umax_val == 32) {
                dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
                dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
        } else {
                dst_reg->smax_value = S64_MAX;
                dst_reg->smin_value = S64_MIN;
        }

        /* If we might shift our top bit out, then we know nothing */
        if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
                dst_reg->umin_value = 0;
                dst_reg->umax_value = U64_MAX;
        } else {
                dst_reg->umin_value <<= umin_val;
                dst_reg->umax_value <<= umax_val;
        }
}

static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        u64 umax_val = src_reg->umax_value;
        u64 umin_val = src_reg->umin_value;

        /* scalar64 calc uses 32bit unshifted bounds so must be called first */
        __scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
        __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);

        dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
        /* We may learn something more from the var_off */
        __update_reg_bounds(dst_reg);
}

static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
                                 struct bpf_reg_state *src_reg)
{
        struct tnum subreg = tnum_subreg(dst_reg->var_off);
        u32 umax_val = src_reg->u32_max_value;
        u32 umin_val = src_reg->u32_min_value;

        /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
         * be negative, then either:
         * 1) src_reg might be zero, so the sign bit of the result is
         *    unknown, so we lose our signed bounds
         * 2) it's known negative, thus the unsigned bounds capture the
         *    signed bounds
         * 3) the signed bounds cross zero, so they tell us nothing
         *    about the result
         * If the value in dst_reg is known nonnegative, then again the
         * unsigned bounds capture the signed bounds.
         * Thus, in all cases it suffices to blow away our signed bounds
         * and rely on inferring new ones from the unsigned bounds and
         * var_off of the result.
         */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;

        dst_reg->var_off = tnum_rshift(subreg, umin_val);
        dst_reg->u32_min_value >>= umax_val;
        dst_reg->u32_max_value >>= umin_val;

        __mark_reg64_unbounded(dst_reg);
        __update_reg32_bounds(dst_reg);
}

static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
                               struct bpf_reg_state *src_reg)
{
        u64 umax_val = src_reg->umax_value;
        u64 umin_val = src_reg->umin_value;

        /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
         * be negative, then either:
         * 1) src_reg might be zero, so the sign bit of the result is
         *    unknown, so we lose our signed bounds
         * 2) it's known negative, thus the unsigned bounds capture the
         *    signed bounds
         * 3) the signed bounds cross zero, so they tell us nothing
         *    about the result
         * If the value in dst_reg is known nonnegative, then again the
         * unsigned bounds capture the signed bounds.
         * Thus, in all cases it suffices to blow away our signed bounds
         * and rely on inferring new ones from the unsigned bounds and
         * var_off of the result.
         */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
        dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
        dst_reg->umin_value >>= umax_val;
        dst_reg->umax_value >>= umin_val;

        /* Its not easy to operate on alu32 bounds here because it depends
         * on bits being shifted in. Take easy way out and mark unbounded
         * so we can recalculate later from tnum.
         */
        __mark_reg32_unbounded(dst_reg);
        __update_reg_bounds(dst_reg);
}

static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
                                  struct bpf_reg_state *src_reg)
{
        u64 umin_val = src_reg->u32_min_value;

        /* Upon reaching here, src_known is true and
         * umax_val is equal to umin_val.
         */
        dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
        dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);

        dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);

        /* blow away the dst_reg umin_value/umax_value and rely on
         * dst_reg var_off to refine the result.
         */
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;

        __mark_reg64_unbounded(dst_reg);
        __update_reg32_bounds(dst_reg);
}

static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
                                struct bpf_reg_state *src_reg)
{
        u64 umin_val = src_reg->umin_value;

        /* Upon reaching here, src_known is true and umax_val is equal
         * to umin_val.
         */
        dst_reg->smin_value >>= umin_val;
        dst_reg->smax_value >>= umin_val;

        dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);

        /* blow away the dst_reg umin_value/umax_value and rely on
         * dst_reg var_off to refine the result.
         */
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;

        /* Its not easy to operate on alu32 bounds here because it depends
         * on bits being shifted in from upper 32-bits. Take easy way out
         * and mark unbounded so we can recalculate later from tnum.
         */
        __mark_reg32_unbounded(dst_reg);
        __update_reg_bounds(dst_reg);
}

static void scalar_byte_swap(struct bpf_reg_state *dst_reg, struct bpf_insn *insn)
{
        /*
         * Byte swap operation - update var_off using tnum_bswap.
         * Three cases:
         * 1. bswap(16|32|64): opcode=0xd7 (BPF_END | BPF_ALU64 | BPF_TO_LE)
         *    unconditional swap
         * 2. to_le(16|32|64): opcode=0xd4 (BPF_END | BPF_ALU | BPF_TO_LE)
         *    swap on big-endian, truncation or no-op on little-endian
         * 3. to_be(16|32|64): opcode=0xdc (BPF_END | BPF_ALU | BPF_TO_BE)
         *    swap on little-endian, truncation or no-op on big-endian
         */

        bool alu64 = BPF_CLASS(insn->code) == BPF_ALU64;
        bool to_le = BPF_SRC(insn->code) == BPF_TO_LE;
        bool is_big_endian;
#ifdef CONFIG_CPU_BIG_ENDIAN
        is_big_endian = true;
#else
        is_big_endian = false;
#endif
        /* Apply bswap if alu64 or switch between big-endian and little-endian machines */
        bool need_bswap = alu64 || (to_le == is_big_endian);

        /*
         * If the register is mutated, manually reset its scalar ID to break
         * any existing ties and avoid incorrect bounds propagation.
         */
        if (need_bswap || insn->imm == 16 || insn->imm == 32)
                clear_scalar_id(dst_reg);

        if (need_bswap) {
                if (insn->imm == 16)
                        dst_reg->var_off = tnum_bswap16(dst_reg->var_off);
                else if (insn->imm == 32)
                        dst_reg->var_off = tnum_bswap32(dst_reg->var_off);
                else if (insn->imm == 64)
                        dst_reg->var_off = tnum_bswap64(dst_reg->var_off);
                /*
                 * Byteswap scrambles the range, so we must reset bounds.
                 * Bounds will be re-derived from the new tnum later.
                 */
                __mark_reg_unbounded(dst_reg);
        }
        /* For bswap16/32, truncate dst register to match the swapped size */
        if (insn->imm == 16 || insn->imm == 32)
                coerce_reg_to_size(dst_reg, insn->imm / 8);
}

static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
                                             const struct bpf_reg_state *src_reg)
{
        bool src_is_const = false;
        u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;

        if (insn_bitness == 32) {
                if (tnum_subreg_is_const(src_reg->var_off)
                    && src_reg->s32_min_value == src_reg->s32_max_value
                    && src_reg->u32_min_value == src_reg->u32_max_value)
                        src_is_const = true;
        } else {
                if (tnum_is_const(src_reg->var_off)
                    && src_reg->smin_value == src_reg->smax_value
                    && src_reg->umin_value == src_reg->umax_value)
                        src_is_const = true;
        }

        switch (BPF_OP(insn->code)) {
        case BPF_ADD:
        case BPF_SUB:
        case BPF_NEG:
        case BPF_AND:
        case BPF_XOR:
        case BPF_OR:
        case BPF_MUL:
        case BPF_END:
                return true;

        /*
         * Division and modulo operators range is only safe to compute when the
         * divisor is a constant.
         */
        case BPF_DIV:
        case BPF_MOD:
                return src_is_const;

        /* Shift operators range is only computable if shift dimension operand
         * is a constant. Shifts greater than 31 or 63 are undefined. This
         * includes shifts by a negative number.
         */
        case BPF_LSH:
        case BPF_RSH:
        case BPF_ARSH:
                return (src_is_const && src_reg->umax_value < insn_bitness);
        default:
                return false;
        }
}

static int maybe_fork_scalars(struct bpf_verifier_env *env, struct bpf_insn *insn,
                              struct bpf_reg_state *dst_reg)
{
        struct bpf_verifier_state *branch;
        struct bpf_reg_state *regs;
        bool alu32;

        if (dst_reg->smin_value == -1 && dst_reg->smax_value == 0)
                alu32 = false;
        else if (dst_reg->s32_min_value == -1 && dst_reg->s32_max_value == 0)
                alu32 = true;
        else
                return 0;

        branch = push_stack(env, env->insn_idx, env->insn_idx, false);
        if (IS_ERR(branch))
                return PTR_ERR(branch);

        regs = branch->frame[branch->curframe]->regs;
        if (alu32) {
                __mark_reg32_known(&regs[insn->dst_reg], 0);
                __mark_reg32_known(dst_reg, -1ull);
        } else {
                __mark_reg_known(&regs[insn->dst_reg], 0);
                __mark_reg_known(dst_reg, -1ull);
        }
        return 0;
}

/* WARNING: This function does calculations on 64-bit values, but the actual
 * execution may occur on 32-bit values. Therefore, things like bitshifts
 * need extra checks in the 32-bit case.
 */
static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
                                      struct bpf_insn *insn,
                                      struct bpf_reg_state *dst_reg,
                                      struct bpf_reg_state src_reg)
{
        u8 opcode = BPF_OP(insn->code);
        s16 off = insn->off;
        bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
        int ret;

        if (!is_safe_to_compute_dst_reg_range(insn, &src_reg)) {
                __mark_reg_unknown(env, dst_reg);
                return 0;
        }

        if (sanitize_needed(opcode)) {
                ret = sanitize_val_alu(env, insn);
                if (ret < 0)
                        return sanitize_err(env, insn, ret, NULL, NULL);
        }

        /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
         * There are two classes of instructions: The first class we track both
         * alu32 and alu64 sign/unsigned bounds independently this provides the
         * greatest amount of precision when alu operations are mixed with jmp32
         * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
         * and BPF_OR. This is possible because these ops have fairly easy to
         * understand and calculate behavior in both 32-bit and 64-bit alu ops.
         * See alu32 verifier tests for examples. The second class of
         * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
         * with regards to tracking sign/unsigned bounds because the bits may
         * cross subreg boundaries in the alu64 case. When this happens we mark
         * the reg unbounded in the subreg bound space and use the resulting
         * tnum to calculate an approximation of the sign/unsigned bounds.
         */
        switch (opcode) {
        case BPF_ADD:
                scalar32_min_max_add(dst_reg, &src_reg);
                scalar_min_max_add(dst_reg, &src_reg);
                dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
                break;
        case BPF_SUB:
                scalar32_min_max_sub(dst_reg, &src_reg);
                scalar_min_max_sub(dst_reg, &src_reg);
                dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
                break;
        case BPF_NEG:
                env->fake_reg[0] = *dst_reg;
                __mark_reg_known(dst_reg, 0);
                scalar32_min_max_sub(dst_reg, &env->fake_reg[0]);
                scalar_min_max_sub(dst_reg, &env->fake_reg[0]);
                dst_reg->var_off = tnum_neg(env->fake_reg[0].var_off);
                break;
        case BPF_MUL:
                dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
                scalar32_min_max_mul(dst_reg, &src_reg);
                scalar_min_max_mul(dst_reg, &src_reg);
                break;
        case BPF_DIV:
                /* BPF div specification: x / 0 = 0 */
                if ((alu32 && src_reg.u32_min_value == 0) || (!alu32 && src_reg.umin_value == 0)) {
                        ___mark_reg_known(dst_reg, 0);
                        break;
                }
                if (alu32)
                        if (off == 1)
                                scalar32_min_max_sdiv(dst_reg, &src_reg);
                        else
                                scalar32_min_max_udiv(dst_reg, &src_reg);
                else
                        if (off == 1)
                                scalar_min_max_sdiv(dst_reg, &src_reg);
                        else
                                scalar_min_max_udiv(dst_reg, &src_reg);
                break;
        case BPF_MOD:
                /* BPF mod specification: x % 0 = x */
                if ((alu32 && src_reg.u32_min_value == 0) || (!alu32 && src_reg.umin_value == 0))
                        break;
                if (alu32)
                        if (off == 1)
                                scalar32_min_max_smod(dst_reg, &src_reg);
                        else
                                scalar32_min_max_umod(dst_reg, &src_reg);
                else
                        if (off == 1)
                                scalar_min_max_smod(dst_reg, &src_reg);
                        else
                                scalar_min_max_umod(dst_reg, &src_reg);
                break;
        case BPF_AND:
                if (tnum_is_const(src_reg.var_off)) {
                        ret = maybe_fork_scalars(env, insn, dst_reg);
                        if (ret)
                                return ret;
                }
                dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
                scalar32_min_max_and(dst_reg, &src_reg);
                scalar_min_max_and(dst_reg, &src_reg);
                break;
        case BPF_OR:
                if (tnum_is_const(src_reg.var_off)) {
                        ret = maybe_fork_scalars(env, insn, dst_reg);
                        if (ret)
                                return ret;
                }
                dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
                scalar32_min_max_or(dst_reg, &src_reg);
                scalar_min_max_or(dst_reg, &src_reg);
                break;
        case BPF_XOR:
                dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
                scalar32_min_max_xor(dst_reg, &src_reg);
                scalar_min_max_xor(dst_reg, &src_reg);
                break;
        case BPF_LSH:
                if (alu32)
                        scalar32_min_max_lsh(dst_reg, &src_reg);
                else
                        scalar_min_max_lsh(dst_reg, &src_reg);
                break;
        case BPF_RSH:
                if (alu32)
                        scalar32_min_max_rsh(dst_reg, &src_reg);
                else
                        scalar_min_max_rsh(dst_reg, &src_reg);
                break;
        case BPF_ARSH:
                if (alu32)
                        scalar32_min_max_arsh(dst_reg, &src_reg);
                else
                        scalar_min_max_arsh(dst_reg, &src_reg);
                break;
        case BPF_END:
                scalar_byte_swap(dst_reg, insn);
                break;
        default:
                break;
        }

        /*
         * ALU32 ops are zero extended into 64bit register.
         *
         * BPF_END is already handled inside the helper (truncation),
         * so skip zext here to avoid unexpected zero extension.
         * e.g., le64: opcode=(BPF_END|BPF_ALU|BPF_TO_LE), imm=0x40
         * This is a 64bit byte swap operation with alu32==true,
         * but we should not zero extend the result.
         */
        if (alu32 && opcode != BPF_END)
                zext_32_to_64(dst_reg);
        reg_bounds_sync(dst_reg);
        return 0;
}

/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
 * and var_off.
 */
static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
                                   struct bpf_insn *insn)
{
        struct bpf_verifier_state *vstate = env->cur_state;
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
        struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
        bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
        u8 opcode = BPF_OP(insn->code);
        int err;

        dst_reg = &regs[insn->dst_reg];
        if (BPF_SRC(insn->code) == BPF_X)
                src_reg = &regs[insn->src_reg];
        else
                src_reg = NULL;

        /* Case where at least one operand is an arena. */
        if (dst_reg->type == PTR_TO_ARENA || (src_reg && src_reg->type == PTR_TO_ARENA)) {
                struct bpf_insn_aux_data *aux = cur_aux(env);

                if (dst_reg->type != PTR_TO_ARENA)
                        *dst_reg = *src_reg;

                dst_reg->subreg_def = env->insn_idx + 1;

                if (BPF_CLASS(insn->code) == BPF_ALU64)
                        /*
                         * 32-bit operations zero upper bits automatically.
                         * 64-bit operations need to be converted to 32.
                         */
                        aux->needs_zext = true;

                /* Any arithmetic operations are allowed on arena pointers */
                return 0;
        }

        if (dst_reg->type != SCALAR_VALUE)
                ptr_reg = dst_reg;

        if (BPF_SRC(insn->code) == BPF_X) {
                if (src_reg->type != SCALAR_VALUE) {
                        if (dst_reg->type != SCALAR_VALUE) {
                                /* Combining two pointers by any ALU op yields
                                 * an arbitrary scalar. Disallow all math except
                                 * pointer subtraction
                                 */
                                if (opcode == BPF_SUB && env->allow_ptr_leaks) {
                                        mark_reg_unknown(env, regs, insn->dst_reg);
                                        return 0;
                                }
                                verbose(env, "R%d pointer %s pointer prohibited\n",
                                        insn->dst_reg,
                                        bpf_alu_string[opcode >> 4]);
                                return -EACCES;
                        } else {
                                /* scalar += pointer
                                 * This is legal, but we have to reverse our
                                 * src/dest handling in computing the range
                                 */
                                err = mark_chain_precision(env, insn->dst_reg);
                                if (err)
                                        return err;
                                return adjust_ptr_min_max_vals(env, insn,
                                                               src_reg, dst_reg);
                        }
                } else if (ptr_reg) {
                        /* pointer += scalar */
                        err = mark_chain_precision(env, insn->src_reg);
                        if (err)
                                return err;
                        return adjust_ptr_min_max_vals(env, insn,
                                                       dst_reg, src_reg);
                } else if (dst_reg->precise) {
                        /* if dst_reg is precise, src_reg should be precise as well */
                        err = mark_chain_precision(env, insn->src_reg);
                        if (err)
                                return err;
                }
        } else {
                /* Pretend the src is a reg with a known value, since we only
                 * need to be able to read from this state.
                 */
                off_reg.type = SCALAR_VALUE;
                __mark_reg_known(&off_reg, insn->imm);
                src_reg = &off_reg;
                if (ptr_reg) /* pointer += K */
                        return adjust_ptr_min_max_vals(env, insn,
                                                       ptr_reg, src_reg);
        }

        /* Got here implies adding two SCALAR_VALUEs */
        if (WARN_ON_ONCE(ptr_reg)) {
                print_verifier_state(env, vstate, vstate->curframe, true);
                verbose(env, "verifier internal error: unexpected ptr_reg\n");
                return -EFAULT;
        }
        if (WARN_ON(!src_reg)) {
                print_verifier_state(env, vstate, vstate->curframe, true);
                verbose(env, "verifier internal error: no src_reg\n");
                return -EFAULT;
        }
        /*
         * For alu32 linked register tracking, we need to check dst_reg's
         * umax_value before the ALU operation. After adjust_scalar_min_max_vals(),
         * alu32 ops will have zero-extended the result, making umax_value <= U32_MAX.
         */
        u64 dst_umax = dst_reg->umax_value;

        err = adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
        if (err)
                return err;
        /*
         * Compilers can generate the code
         * r1 = r2
         * r1 += 0x1
         * if r2 < 1000 goto ...
         * use r1 in memory access
         * So remember constant delta between r2 and r1 and update r1 after
         * 'if' condition.
         */
        if (env->bpf_capable &&
            (BPF_OP(insn->code) == BPF_ADD || BPF_OP(insn->code) == BPF_SUB) &&
            dst_reg->id && is_reg_const(src_reg, alu32) &&
            !(BPF_SRC(insn->code) == BPF_X && insn->src_reg == insn->dst_reg)) {
                u64 val = reg_const_value(src_reg, alu32);
                s32 off;

                if (!alu32 && ((s64)val < S32_MIN || (s64)val > S32_MAX))
                        goto clear_id;

                if (alu32 && (dst_umax > U32_MAX))
                        goto clear_id;

                off = (s32)val;

                if (BPF_OP(insn->code) == BPF_SUB) {
                        /* Negating S32_MIN would overflow */
                        if (off == S32_MIN)
                                goto clear_id;
                        off = -off;
                }

                if (dst_reg->id & BPF_ADD_CONST) {
                        /*
                         * If the register already went through rX += val
                         * we cannot accumulate another val into rx->off.
                         */
clear_id:
                        clear_scalar_id(dst_reg);
                } else {
                        if (alu32)
                                dst_reg->id |= BPF_ADD_CONST32;
                        else
                                dst_reg->id |= BPF_ADD_CONST64;
                        dst_reg->delta = off;
                }
        } else {
                /*
                 * Make sure ID is cleared otherwise dst_reg min/max could be
                 * incorrectly propagated into other registers by sync_linked_regs()
                 */
                clear_scalar_id(dst_reg);
        }
        return 0;
}

/* check validity of 32-bit and 64-bit arithmetic operations */
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        struct bpf_reg_state *regs = cur_regs(env);
        u8 opcode = BPF_OP(insn->code);
        int err;

        if (opcode == BPF_END || opcode == BPF_NEG) {
                /* check src operand */
                err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                if (err)
                        return err;

                if (is_pointer_value(env, insn->dst_reg)) {
                        verbose(env, "R%d pointer arithmetic prohibited\n",
                                insn->dst_reg);
                        return -EACCES;
                }

                /* check dest operand */
                if (regs[insn->dst_reg].type == SCALAR_VALUE) {
                        err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                        err = err ?: adjust_scalar_min_max_vals(env, insn,
                                                         &regs[insn->dst_reg],
                                                         regs[insn->dst_reg]);
                } else {
                        err = check_reg_arg(env, insn->dst_reg, DST_OP);
                }
                if (err)
                        return err;

        } else if (opcode == BPF_MOV) {

                if (BPF_SRC(insn->code) == BPF_X) {
                        if (insn->off == BPF_ADDR_SPACE_CAST) {
                                if (!env->prog->aux->arena) {
                                        verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n");
                                        return -EINVAL;
                                }
                        }

                        /* check src operand */
                        err = check_reg_arg(env, insn->src_reg, SRC_OP);
                        if (err)
                                return err;
                }

                /* check dest operand, mark as required later */
                err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                if (err)
                        return err;

                if (BPF_SRC(insn->code) == BPF_X) {
                        struct bpf_reg_state *src_reg = regs + insn->src_reg;
                        struct bpf_reg_state *dst_reg = regs + insn->dst_reg;

                        if (BPF_CLASS(insn->code) == BPF_ALU64) {
                                if (insn->imm) {
                                        /* off == BPF_ADDR_SPACE_CAST */
                                        mark_reg_unknown(env, regs, insn->dst_reg);
                                        if (insn->imm == 1) { /* cast from as(1) to as(0) */
                                                dst_reg->type = PTR_TO_ARENA;
                                                /* PTR_TO_ARENA is 32-bit */
                                                dst_reg->subreg_def = env->insn_idx + 1;
                                        }
                                } else if (insn->off == 0) {
                                        /* case: R1 = R2
                                         * copy register state to dest reg
                                         */
                                        assign_scalar_id_before_mov(env, src_reg);
                                        copy_register_state(dst_reg, src_reg);
                                        dst_reg->subreg_def = DEF_NOT_SUBREG;
                                } else {
                                        /* case: R1 = (s8, s16 s32)R2 */
                                        if (is_pointer_value(env, insn->src_reg)) {
                                                verbose(env,
                                                        "R%d sign-extension part of pointer\n",
                                                        insn->src_reg);
                                                return -EACCES;
                                        } else if (src_reg->type == SCALAR_VALUE) {
                                                bool no_sext;

                                                no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
                                                if (no_sext)
                                                        assign_scalar_id_before_mov(env, src_reg);
                                                copy_register_state(dst_reg, src_reg);
                                                if (!no_sext)
                                                        clear_scalar_id(dst_reg);
                                                coerce_reg_to_size_sx(dst_reg, insn->off >> 3);
                                                dst_reg->subreg_def = DEF_NOT_SUBREG;
                                        } else {
                                                mark_reg_unknown(env, regs, insn->dst_reg);
                                        }
                                }
                        } else {
                                /* R1 = (u32) R2 */
                                if (is_pointer_value(env, insn->src_reg)) {
                                        verbose(env,
                                                "R%d partial copy of pointer\n",
                                                insn->src_reg);
                                        return -EACCES;
                                } else if (src_reg->type == SCALAR_VALUE) {
                                        if (insn->off == 0) {
                                                bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;

                                                if (is_src_reg_u32)
                                                        assign_scalar_id_before_mov(env, src_reg);
                                                copy_register_state(dst_reg, src_reg);
                                                /* Make sure ID is cleared if src_reg is not in u32
                                                 * range otherwise dst_reg min/max could be incorrectly
                                                 * propagated into src_reg by sync_linked_regs()
                                                 */
                                                if (!is_src_reg_u32)
                                                        clear_scalar_id(dst_reg);
                                                dst_reg->subreg_def = env->insn_idx + 1;
                                        } else {
                                                /* case: W1 = (s8, s16)W2 */
                                                bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));

                                                if (no_sext)
                                                        assign_scalar_id_before_mov(env, src_reg);
                                                copy_register_state(dst_reg, src_reg);
                                                if (!no_sext)
                                                        clear_scalar_id(dst_reg);
                                                dst_reg->subreg_def = env->insn_idx + 1;
                                                coerce_subreg_to_size_sx(dst_reg, insn->off >> 3);
                                        }
                                } else {
                                        mark_reg_unknown(env, regs,
                                                         insn->dst_reg);
                                }
                                zext_32_to_64(dst_reg);
                                reg_bounds_sync(dst_reg);
                        }
                } else {
                        /* case: R = imm
                         * remember the value we stored into this reg
                         */
                        /* clear any state __mark_reg_known doesn't set */
                        mark_reg_unknown(env, regs, insn->dst_reg);
                        regs[insn->dst_reg].type = SCALAR_VALUE;
                        if (BPF_CLASS(insn->code) == BPF_ALU64) {
                                __mark_reg_known(regs + insn->dst_reg,
                                                 insn->imm);
                        } else {
                                __mark_reg_known(regs + insn->dst_reg,
                                                 (u32)insn->imm);
                        }
                }

        } else {        /* all other ALU ops: and, sub, xor, add, ... */

                if (BPF_SRC(insn->code) == BPF_X) {
                        /* check src1 operand */
                        err = check_reg_arg(env, insn->src_reg, SRC_OP);
                        if (err)
                                return err;
                }

                /* check src2 operand */
                err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                if (err)
                        return err;

                if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
                    BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
                        verbose(env, "div by zero\n");
                        return -EINVAL;
                }

                if ((opcode == BPF_LSH || opcode == BPF_RSH ||
                     opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
                        int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;

                        if (insn->imm < 0 || insn->imm >= size) {
                                verbose(env, "invalid shift %d\n", insn->imm);
                                return -EINVAL;
                        }
                }

                /* check dest operand */
                err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
                err = err ?: adjust_reg_min_max_vals(env, insn);
                if (err)
                        return err;
        }

        return reg_bounds_sanity_check(env, &regs[insn->dst_reg], "alu");
}

static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
                                   struct bpf_reg_state *dst_reg,
                                   enum bpf_reg_type type,
                                   bool range_right_open)
{
        struct bpf_func_state *state;
        struct bpf_reg_state *reg;
        int new_range;

        if (dst_reg->umax_value == 0 && range_right_open)
                /* This doesn't give us any range */
                return;

        if (dst_reg->umax_value > MAX_PACKET_OFF)
                /* Risk of overflow.  For instance, ptr + (1<<63) may be less
                 * than pkt_end, but that's because it's also less than pkt.
                 */
                return;

        new_range = dst_reg->umax_value;
        if (range_right_open)
                new_range++;

        /* Examples for register markings:
         *
         * pkt_data in dst register:
         *
         *   r2 = r3;
         *   r2 += 8;
         *   if (r2 > pkt_end) goto <handle exception>
         *   <access okay>
         *
         *   r2 = r3;
         *   r2 += 8;
         *   if (r2 < pkt_end) goto <access okay>
         *   <handle exception>
         *
         *   Where:
         *     r2 == dst_reg, pkt_end == src_reg
         *     r2=pkt(id=n,off=8,r=0)
         *     r3=pkt(id=n,off=0,r=0)
         *
         * pkt_data in src register:
         *
         *   r2 = r3;
         *   r2 += 8;
         *   if (pkt_end >= r2) goto <access okay>
         *   <handle exception>
         *
         *   r2 = r3;
         *   r2 += 8;
         *   if (pkt_end <= r2) goto <handle exception>
         *   <access okay>
         *
         *   Where:
         *     pkt_end == dst_reg, r2 == src_reg
         *     r2=pkt(id=n,off=8,r=0)
         *     r3=pkt(id=n,off=0,r=0)
         *
         * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
         * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
         * and [r3, r3 + 8-1) respectively is safe to access depending on
         * the check.
         */

        /* If our ids match, then we must have the same max_value.  And we
         * don't care about the other reg's fixed offset, since if it's too big
         * the range won't allow anything.
         * dst_reg->umax_value is known < MAX_PACKET_OFF, therefore it fits in a u16.
         */
        bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                if (reg->type == type && reg->id == dst_reg->id)
                        /* keep the maximum range already checked */
                        reg->range = max(reg->range, new_range);
        }));
}

static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
                                u8 opcode, bool is_jmp32);
static u8 rev_opcode(u8 opcode);

/*
 * Learn more information about live branches by simulating refinement on both branches.
 * regs_refine_cond_op() is sound, so producing ill-formed register bounds for the branch means
 * that branch is dead.
 */
static int simulate_both_branches_taken(struct bpf_verifier_env *env, u8 opcode, bool is_jmp32)
{
        /* Fallthrough (FALSE) branch */
        regs_refine_cond_op(&env->false_reg1, &env->false_reg2, rev_opcode(opcode), is_jmp32);
        reg_bounds_sync(&env->false_reg1);
        reg_bounds_sync(&env->false_reg2);
        /*
         * If there is a range bounds violation in *any* of the abstract values in either
         * reg_states in the FALSE branch (i.e. reg1, reg2), the FALSE branch must be dead. Only
         * TRUE branch will be taken.
         */
        if (range_bounds_violation(&env->false_reg1) || range_bounds_violation(&env->false_reg2))
                return 1;

        /* Jump (TRUE) branch */
        regs_refine_cond_op(&env->true_reg1, &env->true_reg2, opcode, is_jmp32);
        reg_bounds_sync(&env->true_reg1);
        reg_bounds_sync(&env->true_reg2);
        /*
         * If there is a range bounds violation in *any* of the abstract values in either
         * reg_states in the TRUE branch (i.e. true_reg1, true_reg2), the TRUE branch must be dead.
         * Only FALSE branch will be taken.
         */
        if (range_bounds_violation(&env->true_reg1) || range_bounds_violation(&env->true_reg2))
                return 0;

        /* Both branches are possible, we can't determine which one will be taken. */
        return -1;
}

/*
 * <reg1> <op> <reg2>, currently assuming reg2 is a constant
 */
static int is_scalar_branch_taken(struct bpf_verifier_env *env, struct bpf_reg_state *reg1,
                                  struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32)
{
        struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
        struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off;
        u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
        u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
        s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
        s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
        u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value;
        u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value;
        s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value;
        s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value;

        if (reg1 == reg2) {
                switch (opcode) {
                case BPF_JGE:
                case BPF_JLE:
                case BPF_JSGE:
                case BPF_JSLE:
                case BPF_JEQ:
                        return 1;
                case BPF_JGT:
                case BPF_JLT:
                case BPF_JSGT:
                case BPF_JSLT:
                case BPF_JNE:
                        return 0;
                case BPF_JSET:
                        if (tnum_is_const(t1))
                                return t1.value != 0;
                        else
                                return (smin1 <= 0 && smax1 >= 0) ? -1 : 1;
                default:
                        return -1;
                }
        }

        switch (opcode) {
        case BPF_JEQ:
                /* constants, umin/umax and smin/smax checks would be
                 * redundant in this case because they all should match
                 */
                if (tnum_is_const(t1) && tnum_is_const(t2))
                        return t1.value == t2.value;
                if (!tnum_overlap(t1, t2))
                        return 0;
                /* non-overlapping ranges */
                if (umin1 > umax2 || umax1 < umin2)
                        return 0;
                if (smin1 > smax2 || smax1 < smin2)
                        return 0;
                if (!is_jmp32) {
                        /* if 64-bit ranges are inconclusive, see if we can
                         * utilize 32-bit subrange knowledge to eliminate
                         * branches that can't be taken a priori
                         */
                        if (reg1->u32_min_value > reg2->u32_max_value ||
                            reg1->u32_max_value < reg2->u32_min_value)
                                return 0;
                        if (reg1->s32_min_value > reg2->s32_max_value ||
                            reg1->s32_max_value < reg2->s32_min_value)
                                return 0;
                }
                break;
        case BPF_JNE:
                /* constants, umin/umax and smin/smax checks would be
                 * redundant in this case because they all should match
                 */
                if (tnum_is_const(t1) && tnum_is_const(t2))
                        return t1.value != t2.value;
                if (!tnum_overlap(t1, t2))
                        return 1;
                /* non-overlapping ranges */
                if (umin1 > umax2 || umax1 < umin2)
                        return 1;
                if (smin1 > smax2 || smax1 < smin2)
                        return 1;
                if (!is_jmp32) {
                        /* if 64-bit ranges are inconclusive, see if we can
                         * utilize 32-bit subrange knowledge to eliminate
                         * branches that can't be taken a priori
                         */
                        if (reg1->u32_min_value > reg2->u32_max_value ||
                            reg1->u32_max_value < reg2->u32_min_value)
                                return 1;
                        if (reg1->s32_min_value > reg2->s32_max_value ||
                            reg1->s32_max_value < reg2->s32_min_value)
                                return 1;
                }
                break;
        case BPF_JSET:
                if (!is_reg_const(reg2, is_jmp32)) {
                        swap(reg1, reg2);
                        swap(t1, t2);
                }
                if (!is_reg_const(reg2, is_jmp32))
                        return -1;
                if ((~t1.mask & t1.value) & t2.value)
                        return 1;
                if (!((t1.mask | t1.value) & t2.value))
                        return 0;
                break;
        case BPF_JGT:
                if (umin1 > umax2)
                        return 1;
                else if (umax1 <= umin2)
                        return 0;
                break;
        case BPF_JSGT:
                if (smin1 > smax2)
                        return 1;
                else if (smax1 <= smin2)
                        return 0;
                break;
        case BPF_JLT:
                if (umax1 < umin2)
                        return 1;
                else if (umin1 >= umax2)
                        return 0;
                break;
        case BPF_JSLT:
                if (smax1 < smin2)
                        return 1;
                else if (smin1 >= smax2)
                        return 0;
                break;
        case BPF_JGE:
                if (umin1 >= umax2)
                        return 1;
                else if (umax1 < umin2)
                        return 0;
                break;
        case BPF_JSGE:
                if (smin1 >= smax2)
                        return 1;
                else if (smax1 < smin2)
                        return 0;
                break;
        case BPF_JLE:
                if (umax1 <= umin2)
                        return 1;
                else if (umin1 > umax2)
                        return 0;
                break;
        case BPF_JSLE:
                if (smax1 <= smin2)
                        return 1;
                else if (smin1 > smax2)
                        return 0;
                break;
        }

        return simulate_both_branches_taken(env, opcode, is_jmp32);
}

static int flip_opcode(u32 opcode)
{
        /* How can we transform "a <op> b" into "b <op> a"? */
        static const u8 opcode_flip[16] = {
                /* these stay the same */
                [BPF_JEQ  >> 4] = BPF_JEQ,
                [BPF_JNE  >> 4] = BPF_JNE,
                [BPF_JSET >> 4] = BPF_JSET,
                /* these swap "lesser" and "greater" (L and G in the opcodes) */
                [BPF_JGE  >> 4] = BPF_JLE,
                [BPF_JGT  >> 4] = BPF_JLT,
                [BPF_JLE  >> 4] = BPF_JGE,
                [BPF_JLT  >> 4] = BPF_JGT,
                [BPF_JSGE >> 4] = BPF_JSLE,
                [BPF_JSGT >> 4] = BPF_JSLT,
                [BPF_JSLE >> 4] = BPF_JSGE,
                [BPF_JSLT >> 4] = BPF_JSGT
        };
        return opcode_flip[opcode >> 4];
}

static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg,
                                   struct bpf_reg_state *src_reg,
                                   u8 opcode)
{
        struct bpf_reg_state *pkt;

        if (src_reg->type == PTR_TO_PACKET_END) {
                pkt = dst_reg;
        } else if (dst_reg->type == PTR_TO_PACKET_END) {
                pkt = src_reg;
                opcode = flip_opcode(opcode);
        } else {
                return -1;
        }

        if (pkt->range >= 0)
                return -1;

        switch (opcode) {
        case BPF_JLE:
                /* pkt <= pkt_end */
                fallthrough;
        case BPF_JGT:
                /* pkt > pkt_end */
                if (pkt->range == BEYOND_PKT_END)
                        /* pkt has at last one extra byte beyond pkt_end */
                        return opcode == BPF_JGT;
                break;
        case BPF_JLT:
                /* pkt < pkt_end */
                fallthrough;
        case BPF_JGE:
                /* pkt >= pkt_end */
                if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END)
                        return opcode == BPF_JGE;
                break;
        }
        return -1;
}

/* compute branch direction of the expression "if (<reg1> opcode <reg2>) goto target;"
 * and return:
 *  1 - branch will be taken and "goto target" will be executed
 *  0 - branch will not be taken and fall-through to next insn
 * -1 - unknown. Example: "if (reg1 < 5)" is unknown when register value
 *      range [0,10]
 */
static int is_branch_taken(struct bpf_verifier_env *env, struct bpf_reg_state *reg1,
                           struct bpf_reg_state *reg2, u8 opcode, bool is_jmp32)
{
        if (reg_is_pkt_pointer_any(reg1) && reg_is_pkt_pointer_any(reg2) && !is_jmp32)
                return is_pkt_ptr_branch_taken(reg1, reg2, opcode);

        if (__is_pointer_value(false, reg1) || __is_pointer_value(false, reg2)) {
                u64 val;

                /* arrange that reg2 is a scalar, and reg1 is a pointer */
                if (!is_reg_const(reg2, is_jmp32)) {
                        opcode = flip_opcode(opcode);
                        swap(reg1, reg2);
                }
                /* and ensure that reg2 is a constant */
                if (!is_reg_const(reg2, is_jmp32))
                        return -1;

                if (!reg_not_null(reg1))
                        return -1;

                /* If pointer is valid tests against zero will fail so we can
                 * use this to direct branch taken.
                 */
                val = reg_const_value(reg2, is_jmp32);
                if (val != 0)
                        return -1;

                switch (opcode) {
                case BPF_JEQ:
                        return 0;
                case BPF_JNE:
                        return 1;
                default:
                        return -1;
                }
        }

        /* now deal with two scalars, but not necessarily constants */
        return is_scalar_branch_taken(env, reg1, reg2, opcode, is_jmp32);
}

/* Opcode that corresponds to a *false* branch condition.
 * E.g., if r1 < r2, then reverse (false) condition is r1 >= r2
 */
static u8 rev_opcode(u8 opcode)
{
        switch (opcode) {
        case BPF_JEQ:           return BPF_JNE;
        case BPF_JNE:           return BPF_JEQ;
        /* JSET doesn't have it's reverse opcode in BPF, so add
         * BPF_X flag to denote the reverse of that operation
         */
        case BPF_JSET:          return BPF_JSET | BPF_X;
        case BPF_JSET | BPF_X:  return BPF_JSET;
        case BPF_JGE:           return BPF_JLT;
        case BPF_JGT:           return BPF_JLE;
        case BPF_JLE:           return BPF_JGT;
        case BPF_JLT:           return BPF_JGE;
        case BPF_JSGE:          return BPF_JSLT;
        case BPF_JSGT:          return BPF_JSLE;
        case BPF_JSLE:          return BPF_JSGT;
        case BPF_JSLT:          return BPF_JSGE;
        default:                return 0;
        }
}

/* Refine range knowledge for <reg1> <op> <reg>2 conditional operation. */
static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
                                u8 opcode, bool is_jmp32)
{
        struct tnum t;
        u64 val;

        /* In case of GE/GT/SGE/JST, reuse LE/LT/SLE/SLT logic from below */
        switch (opcode) {
        case BPF_JGE:
        case BPF_JGT:
        case BPF_JSGE:
        case BPF_JSGT:
                opcode = flip_opcode(opcode);
                swap(reg1, reg2);
                break;
        default:
                break;
        }

        switch (opcode) {
        case BPF_JEQ:
                if (is_jmp32) {
                        reg1->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
                        reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
                        reg1->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
                        reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
                        reg2->u32_min_value = reg1->u32_min_value;
                        reg2->u32_max_value = reg1->u32_max_value;
                        reg2->s32_min_value = reg1->s32_min_value;
                        reg2->s32_max_value = reg1->s32_max_value;

                        t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off));
                        reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                        reg2->var_off = tnum_with_subreg(reg2->var_off, t);
                } else {
                        reg1->umin_value = max(reg1->umin_value, reg2->umin_value);
                        reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
                        reg1->smin_value = max(reg1->smin_value, reg2->smin_value);
                        reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
                        reg2->umin_value = reg1->umin_value;
                        reg2->umax_value = reg1->umax_value;
                        reg2->smin_value = reg1->smin_value;
                        reg2->smax_value = reg1->smax_value;

                        reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off);
                        reg2->var_off = reg1->var_off;
                }
                break;
        case BPF_JNE:
                if (!is_reg_const(reg2, is_jmp32))
                        swap(reg1, reg2);
                if (!is_reg_const(reg2, is_jmp32))
                        break;

                /* try to recompute the bound of reg1 if reg2 is a const and
                 * is exactly the edge of reg1.
                 */
                val = reg_const_value(reg2, is_jmp32);
                if (is_jmp32) {
                        /* u32_min_value is not equal to 0xffffffff at this point,
                         * because otherwise u32_max_value is 0xffffffff as well,
                         * in such a case both reg1 and reg2 would be constants,
                         * jump would be predicted and regs_refine_cond_op()
                         * wouldn't be called.
                         *
                         * Same reasoning works for all {u,s}{min,max}{32,64} cases
                         * below.
                         */
                        if (reg1->u32_min_value == (u32)val)
                                reg1->u32_min_value++;
                        if (reg1->u32_max_value == (u32)val)
                                reg1->u32_max_value--;
                        if (reg1->s32_min_value == (s32)val)
                                reg1->s32_min_value++;
                        if (reg1->s32_max_value == (s32)val)
                                reg1->s32_max_value--;
                } else {
                        if (reg1->umin_value == (u64)val)
                                reg1->umin_value++;
                        if (reg1->umax_value == (u64)val)
                                reg1->umax_value--;
                        if (reg1->smin_value == (s64)val)
                                reg1->smin_value++;
                        if (reg1->smax_value == (s64)val)
                                reg1->smax_value--;
                }
                break;
        case BPF_JSET:
                if (!is_reg_const(reg2, is_jmp32))
                        swap(reg1, reg2);
                if (!is_reg_const(reg2, is_jmp32))
                        break;
                val = reg_const_value(reg2, is_jmp32);
                /* BPF_JSET (i.e., TRUE branch, *not* BPF_JSET | BPF_X)
                 * requires single bit to learn something useful. E.g., if we
                 * know that `r1 & 0x3` is true, then which bits (0, 1, or both)
                 * are actually set? We can learn something definite only if
                 * it's a single-bit value to begin with.
                 *
                 * BPF_JSET | BPF_X (i.e., negation of BPF_JSET) doesn't have
                 * this restriction. I.e., !(r1 & 0x3) means neither bit 0 nor
                 * bit 1 is set, which we can readily use in adjustments.
                 */
                if (!is_power_of_2(val))
                        break;
                if (is_jmp32) {
                        t = tnum_or(tnum_subreg(reg1->var_off), tnum_const(val));
                        reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                } else {
                        reg1->var_off = tnum_or(reg1->var_off, tnum_const(val));
                }
                break;
        case BPF_JSET | BPF_X: /* reverse of BPF_JSET, see rev_opcode() */
                if (!is_reg_const(reg2, is_jmp32))
                        swap(reg1, reg2);
                if (!is_reg_const(reg2, is_jmp32))
                        break;
                val = reg_const_value(reg2, is_jmp32);
                /* Forget the ranges before narrowing tnums, to avoid invariant
                 * violations if we're on a dead branch.
                 */
                __mark_reg_unbounded(reg1);
                if (is_jmp32) {
                        t = tnum_and(tnum_subreg(reg1->var_off), tnum_const(~val));
                        reg1->var_off = tnum_with_subreg(reg1->var_off, t);
                } else {
                        reg1->var_off = tnum_and(reg1->var_off, tnum_const(~val));
                }
                break;
        case BPF_JLE:
                if (is_jmp32) {
                        reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value);
                        reg2->u32_min_value = max(reg1->u32_min_value, reg2->u32_min_value);
                } else {
                        reg1->umax_value = min(reg1->umax_value, reg2->umax_value);
                        reg2->umin_value = max(reg1->umin_value, reg2->umin_value);
                }
                break;
        case BPF_JLT:
                if (is_jmp32) {
                        reg1->u32_max_value = min(reg1->u32_max_value, reg2->u32_max_value - 1);
                        reg2->u32_min_value = max(reg1->u32_min_value + 1, reg2->u32_min_value);
                } else {
                        reg1->umax_value = min(reg1->umax_value, reg2->umax_value - 1);
                        reg2->umin_value = max(reg1->umin_value + 1, reg2->umin_value);
                }
                break;
        case BPF_JSLE:
                if (is_jmp32) {
                        reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value);
                        reg2->s32_min_value = max(reg1->s32_min_value, reg2->s32_min_value);
                } else {
                        reg1->smax_value = min(reg1->smax_value, reg2->smax_value);
                        reg2->smin_value = max(reg1->smin_value, reg2->smin_value);
                }
                break;
        case BPF_JSLT:
                if (is_jmp32) {
                        reg1->s32_max_value = min(reg1->s32_max_value, reg2->s32_max_value - 1);
                        reg2->s32_min_value = max(reg1->s32_min_value + 1, reg2->s32_min_value);
                } else {
                        reg1->smax_value = min(reg1->smax_value, reg2->smax_value - 1);
                        reg2->smin_value = max(reg1->smin_value + 1, reg2->smin_value);
                }
                break;
        default:
                return;
        }
}

/* Check for invariant violations on the registers for both branches of a condition */
static int regs_bounds_sanity_check_branches(struct bpf_verifier_env *env)
{
        int err;

        err = reg_bounds_sanity_check(env, &env->true_reg1, "true_reg1");
        err = err ?: reg_bounds_sanity_check(env, &env->true_reg2, "true_reg2");
        err = err ?: reg_bounds_sanity_check(env, &env->false_reg1, "false_reg1");
        err = err ?: reg_bounds_sanity_check(env, &env->false_reg2, "false_reg2");
        return err;
}

static void mark_ptr_or_null_reg(struct bpf_func_state *state,
                                 struct bpf_reg_state *reg, u32 id,
                                 bool is_null)
{
        if (type_may_be_null(reg->type) && reg->id == id &&
            (is_rcu_reg(reg) || !WARN_ON_ONCE(!reg->id))) {
                /* Old offset should have been known-zero, because we don't
                 * allow pointer arithmetic on pointers that might be NULL.
                 * If we see this happening, don't convert the register.
                 *
                 * But in some cases, some helpers that return local kptrs
                 * advance offset for the returned pointer. In those cases,
                 * it is fine to expect to see reg->var_off.
                 */
                if (!(type_is_ptr_alloc_obj(reg->type) || type_is_non_owning_ref(reg->type)) &&
                    WARN_ON_ONCE(!tnum_equals_const(reg->var_off, 0)))
                        return;
                if (is_null) {
                        /* We don't need id and ref_obj_id from this point
                         * onwards anymore, thus we should better reset it,
                         * so that state pruning has chances to take effect.
                         */
                        __mark_reg_known_zero(reg);
                        reg->type = SCALAR_VALUE;

                        return;
                }

                mark_ptr_not_null_reg(reg);

                if (!reg_may_point_to_spin_lock(reg)) {
                        /* For not-NULL ptr, reg->ref_obj_id will be reset
                         * in release_reference().
                         *
                         * reg->id is still used by spin_lock ptr. Other
                         * than spin_lock ptr type, reg->id can be reset.
                         */
                        reg->id = 0;
                }
        }
}

/* The logic is similar to find_good_pkt_pointers(), both could eventually
 * be folded together at some point.
 */
static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
                                  bool is_null)
{
        struct bpf_func_state *state = vstate->frame[vstate->curframe];
        struct bpf_reg_state *regs = state->regs, *reg;
        u32 ref_obj_id = regs[regno].ref_obj_id;
        u32 id = regs[regno].id;

        if (ref_obj_id && ref_obj_id == id && is_null)
                /* regs[regno] is in the " == NULL" branch.
                 * No one could have freed the reference state before
                 * doing the NULL check.
                 */
                WARN_ON_ONCE(release_reference_nomark(vstate, id));

        bpf_for_each_reg_in_vstate(vstate, state, reg, ({
                mark_ptr_or_null_reg(state, reg, id, is_null);
        }));
}

static bool try_match_pkt_pointers(const struct bpf_insn *insn,
                                   struct bpf_reg_state *dst_reg,
                                   struct bpf_reg_state *src_reg,
                                   struct bpf_verifier_state *this_branch,
                                   struct bpf_verifier_state *other_branch)
{
        if (BPF_SRC(insn->code) != BPF_X)
                return false;

        /* Pointers are always 64-bit. */
        if (BPF_CLASS(insn->code) == BPF_JMP32)
                return false;

        switch (BPF_OP(insn->code)) {
        case BPF_JGT:
                if ((dst_reg->type == PTR_TO_PACKET &&
                     src_reg->type == PTR_TO_PACKET_END) ||
                    (dst_reg->type == PTR_TO_PACKET_META &&
                     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                        /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
                        find_good_pkt_pointers(this_branch, dst_reg,
                                               dst_reg->type, false);
                        mark_pkt_end(other_branch, insn->dst_reg, true);
                } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                            src_reg->type == PTR_TO_PACKET) ||
                           (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                            src_reg->type == PTR_TO_PACKET_META)) {
                        /* pkt_end > pkt_data', pkt_data > pkt_meta' */
                        find_good_pkt_pointers(other_branch, src_reg,
                                               src_reg->type, true);
                        mark_pkt_end(this_branch, insn->src_reg, false);
                } else {
                        return false;
                }
                break;
        case BPF_JLT:
                if ((dst_reg->type == PTR_TO_PACKET &&
                     src_reg->type == PTR_TO_PACKET_END) ||
                    (dst_reg->type == PTR_TO_PACKET_META &&
                     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                        /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
                        find_good_pkt_pointers(other_branch, dst_reg,
                                               dst_reg->type, true);
                        mark_pkt_end(this_branch, insn->dst_reg, false);
                } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                            src_reg->type == PTR_TO_PACKET) ||
                           (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                            src_reg->type == PTR_TO_PACKET_META)) {
                        /* pkt_end < pkt_data', pkt_data > pkt_meta' */
                        find_good_pkt_pointers(this_branch, src_reg,
                                               src_reg->type, false);
                        mark_pkt_end(other_branch, insn->src_reg, true);
                } else {
                        return false;
                }
                break;
        case BPF_JGE:
                if ((dst_reg->type == PTR_TO_PACKET &&
                     src_reg->type == PTR_TO_PACKET_END) ||
                    (dst_reg->type == PTR_TO_PACKET_META &&
                     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                        /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
                        find_good_pkt_pointers(this_branch, dst_reg,
                                               dst_reg->type, true);
                        mark_pkt_end(other_branch, insn->dst_reg, false);
                } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                            src_reg->type == PTR_TO_PACKET) ||
                           (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                            src_reg->type == PTR_TO_PACKET_META)) {
                        /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
                        find_good_pkt_pointers(other_branch, src_reg,
                                               src_reg->type, false);
                        mark_pkt_end(this_branch, insn->src_reg, true);
                } else {
                        return false;
                }
                break;
        case BPF_JLE:
                if ((dst_reg->type == PTR_TO_PACKET &&
                     src_reg->type == PTR_TO_PACKET_END) ||
                    (dst_reg->type == PTR_TO_PACKET_META &&
                     reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                        /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
                        find_good_pkt_pointers(other_branch, dst_reg,
                                               dst_reg->type, false);
                        mark_pkt_end(this_branch, insn->dst_reg, true);
                } else if ((dst_reg->type == PTR_TO_PACKET_END &&
                            src_reg->type == PTR_TO_PACKET) ||
                           (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
                            src_reg->type == PTR_TO_PACKET_META)) {
                        /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
                        find_good_pkt_pointers(this_branch, src_reg,
                                               src_reg->type, true);
                        mark_pkt_end(other_branch, insn->src_reg, false);
                } else {
                        return false;
                }
                break;
        default:
                return false;
        }

        return true;
}

static void __collect_linked_regs(struct linked_regs *reg_set, struct bpf_reg_state *reg,
                                  u32 id, u32 frameno, u32 spi_or_reg, bool is_reg)
{
        struct linked_reg *e;

        if (reg->type != SCALAR_VALUE || (reg->id & ~BPF_ADD_CONST) != id)
                return;

        e = linked_regs_push(reg_set);
        if (e) {
                e->frameno = frameno;
                e->is_reg = is_reg;
                e->regno = spi_or_reg;
        } else {
                clear_scalar_id(reg);
        }
}

/* For all R being scalar registers or spilled scalar registers
 * in verifier state, save R in linked_regs if R->id == id.
 * If there are too many Rs sharing same id, reset id for leftover Rs.
 */
static void collect_linked_regs(struct bpf_verifier_env *env,
                                struct bpf_verifier_state *vstate,
                                u32 id,
                                struct linked_regs *linked_regs)
{
        struct bpf_insn_aux_data *aux = env->insn_aux_data;
        struct bpf_func_state *func;
        struct bpf_reg_state *reg;
        u16 live_regs;
        int i, j;

        id = id & ~BPF_ADD_CONST;
        for (i = vstate->curframe; i >= 0; i--) {
                live_regs = aux[bpf_frame_insn_idx(vstate, i)].live_regs_before;
                func = vstate->frame[i];
                for (j = 0; j < BPF_REG_FP; j++) {
                        if (!(live_regs & BIT(j)))
                                continue;
                        reg = &func->regs[j];
                        __collect_linked_regs(linked_regs, reg, id, i, j, true);
                }
                for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
                        if (!bpf_is_spilled_reg(&func->stack[j]))
                                continue;
                        reg = &func->stack[j].spilled_ptr;
                        __collect_linked_regs(linked_regs, reg, id, i, j, false);
                }
        }
}

/* For all R in linked_regs, copy known_reg range into R
 * if R->id == known_reg->id.
 */
static void sync_linked_regs(struct bpf_verifier_env *env, struct bpf_verifier_state *vstate,
                             struct bpf_reg_state *known_reg, struct linked_regs *linked_regs)
{
        struct bpf_reg_state fake_reg;
        struct bpf_reg_state *reg;
        struct linked_reg *e;
        int i;

        for (i = 0; i < linked_regs->cnt; ++i) {
                e = &linked_regs->entries[i];
                reg = e->is_reg ? &vstate->frame[e->frameno]->regs[e->regno]
                                : &vstate->frame[e->frameno]->stack[e->spi].spilled_ptr;
                if (reg->type != SCALAR_VALUE || reg == known_reg)
                        continue;
                if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST))
                        continue;
                /*
                 * Skip mixed 32/64-bit links: the delta relationship doesn't
                 * hold across different ALU widths.
                 */
                if (((reg->id ^ known_reg->id) & BPF_ADD_CONST) == BPF_ADD_CONST)
                        continue;
                if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) ||
                    reg->delta == known_reg->delta) {
                        s32 saved_subreg_def = reg->subreg_def;

                        copy_register_state(reg, known_reg);
                        reg->subreg_def = saved_subreg_def;
                } else {
                        s32 saved_subreg_def = reg->subreg_def;
                        s32 saved_off = reg->delta;
                        u32 saved_id = reg->id;

                        fake_reg.type = SCALAR_VALUE;
                        __mark_reg_known(&fake_reg, (s64)reg->delta - (s64)known_reg->delta);

                        /* reg = known_reg; reg += delta */
                        copy_register_state(reg, known_reg);
                        /*
                         * Must preserve off, id and subreg_def flag,
                         * otherwise another sync_linked_regs() will be incorrect.
                         */
                        reg->delta = saved_off;
                        reg->id = saved_id;
                        reg->subreg_def = saved_subreg_def;

                        scalar32_min_max_add(reg, &fake_reg);
                        scalar_min_max_add(reg, &fake_reg);
                        reg->var_off = tnum_add(reg->var_off, fake_reg.var_off);
                        if ((reg->id | known_reg->id) & BPF_ADD_CONST32)
                                zext_32_to_64(reg);
                        reg_bounds_sync(reg);
                }
                if (e->is_reg)
                        mark_reg_scratched(env, e->regno);
                else
                        mark_stack_slot_scratched(env, e->spi);
        }
}

static int check_cond_jmp_op(struct bpf_verifier_env *env,
                             struct bpf_insn *insn, int *insn_idx)
{
        struct bpf_verifier_state *this_branch = env->cur_state;
        struct bpf_verifier_state *other_branch;
        struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
        struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
        struct bpf_reg_state *eq_branch_regs;
        struct linked_regs linked_regs = {};
        u8 opcode = BPF_OP(insn->code);
        int insn_flags = 0;
        bool is_jmp32;
        int pred = -1;
        int err;

        /* Only conditional jumps are expected to reach here. */
        if (opcode == BPF_JA || opcode > BPF_JCOND) {
                verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
                return -EINVAL;
        }

        if (opcode == BPF_JCOND) {
                struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
                int idx = *insn_idx;

                prev_st = find_prev_entry(env, cur_st->parent, idx);

                /* branch out 'fallthrough' insn as a new state to explore */
                queued_st = push_stack(env, idx + 1, idx, false);
                if (IS_ERR(queued_st))
                        return PTR_ERR(queued_st);

                queued_st->may_goto_depth++;
                if (prev_st)
                        widen_imprecise_scalars(env, prev_st, queued_st);
                *insn_idx += insn->off;
                return 0;
        }

        /* check src2 operand */
        err = check_reg_arg(env, insn->dst_reg, SRC_OP);
        if (err)
                return err;

        dst_reg = &regs[insn->dst_reg];
        if (BPF_SRC(insn->code) == BPF_X) {
                /* check src1 operand */
                err = check_reg_arg(env, insn->src_reg, SRC_OP);
                if (err)
                        return err;

                src_reg = &regs[insn->src_reg];
                if (!(reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg)) &&
                    is_pointer_value(env, insn->src_reg)) {
                        verbose(env, "R%d pointer comparison prohibited\n",
                                insn->src_reg);
                        return -EACCES;
                }

                if (src_reg->type == PTR_TO_STACK)
                        insn_flags |= INSN_F_SRC_REG_STACK;
                if (dst_reg->type == PTR_TO_STACK)
                        insn_flags |= INSN_F_DST_REG_STACK;
        } else {
                src_reg = &env->fake_reg[0];
                memset(src_reg, 0, sizeof(*src_reg));
                src_reg->type = SCALAR_VALUE;
                __mark_reg_known(src_reg, insn->imm);

                if (dst_reg->type == PTR_TO_STACK)
                        insn_flags |= INSN_F_DST_REG_STACK;
        }

        if (insn_flags) {
                err = bpf_push_jmp_history(env, this_branch, insn_flags, 0);
                if (err)
                        return err;
        }

        is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
        copy_register_state(&env->false_reg1, dst_reg);
        copy_register_state(&env->false_reg2, src_reg);
        copy_register_state(&env->true_reg1, dst_reg);
        copy_register_state(&env->true_reg2, src_reg);
        pred = is_branch_taken(env, dst_reg, src_reg, opcode, is_jmp32);
        if (pred >= 0) {
                /* If we get here with a dst_reg pointer type it is because
                 * above is_branch_taken() special cased the 0 comparison.
                 */
                if (!__is_pointer_value(false, dst_reg))
                        err = mark_chain_precision(env, insn->dst_reg);
                if (BPF_SRC(insn->code) == BPF_X && !err &&
                    !__is_pointer_value(false, src_reg))
                        err = mark_chain_precision(env, insn->src_reg);
                if (err)
                        return err;
        }

        if (pred == 1) {
                /* Only follow the goto, ignore fall-through. If needed, push
                 * the fall-through branch for simulation under speculative
                 * execution.
                 */
                if (!env->bypass_spec_v1) {
                        err = sanitize_speculative_path(env, insn, *insn_idx + 1, *insn_idx);
                        if (err < 0)
                                return err;
                }
                if (env->log.level & BPF_LOG_LEVEL)
                        print_insn_state(env, this_branch, this_branch->curframe);
                *insn_idx += insn->off;
                return 0;
        } else if (pred == 0) {
                /* Only follow the fall-through branch, since that's where the
                 * program will go. If needed, push the goto branch for
                 * simulation under speculative execution.
                 */
                if (!env->bypass_spec_v1) {
                        err = sanitize_speculative_path(env, insn, *insn_idx + insn->off + 1,
                                                        *insn_idx);
                        if (err < 0)
                                return err;
                }
                if (env->log.level & BPF_LOG_LEVEL)
                        print_insn_state(env, this_branch, this_branch->curframe);
                return 0;
        }

        /* Push scalar registers sharing same ID to jump history,
         * do this before creating 'other_branch', so that both
         * 'this_branch' and 'other_branch' share this history
         * if parent state is created.
         */
        if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id)
                collect_linked_regs(env, this_branch, src_reg->id, &linked_regs);
        if (dst_reg->type == SCALAR_VALUE && dst_reg->id)
                collect_linked_regs(env, this_branch, dst_reg->id, &linked_regs);
        if (linked_regs.cnt > 1) {
                err = bpf_push_jmp_history(env, this_branch, 0, linked_regs_pack(&linked_regs));
                if (err)
                        return err;
        }

        other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx, false);
        if (IS_ERR(other_branch))
                return PTR_ERR(other_branch);
        other_branch_regs = other_branch->frame[other_branch->curframe]->regs;

        err = regs_bounds_sanity_check_branches(env);
        if (err)
                return err;

        copy_register_state(dst_reg, &env->false_reg1);
        copy_register_state(src_reg, &env->false_reg2);
        copy_register_state(&other_branch_regs[insn->dst_reg], &env->true_reg1);
        if (BPF_SRC(insn->code) == BPF_X)
                copy_register_state(&other_branch_regs[insn->src_reg], &env->true_reg2);

        if (BPF_SRC(insn->code) == BPF_X &&
            src_reg->type == SCALAR_VALUE && src_reg->id &&
            !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
                sync_linked_regs(env, this_branch, src_reg, &linked_regs);
                sync_linked_regs(env, other_branch, &other_branch_regs[insn->src_reg],
                                 &linked_regs);
        }
        if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
            !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
                sync_linked_regs(env, this_branch, dst_reg, &linked_regs);
                sync_linked_regs(env, other_branch, &other_branch_regs[insn->dst_reg],
                                 &linked_regs);
        }

        /* if one pointer register is compared to another pointer
         * register check if PTR_MAYBE_NULL could be lifted.
         * E.g. register A - maybe null
         *      register B - not null
         * for JNE A, B, ... - A is not null in the false branch;
         * for JEQ A, B, ... - A is not null in the true branch.
         *
         * Since PTR_TO_BTF_ID points to a kernel struct that does
         * not need to be null checked by the BPF program, i.e.,
         * could be null even without PTR_MAYBE_NULL marking, so
         * only propagate nullness when neither reg is that type.
         */
        if (!is_jmp32 && BPF_SRC(insn->code) == BPF_X &&
            __is_pointer_value(false, src_reg) && __is_pointer_value(false, dst_reg) &&
            type_may_be_null(src_reg->type) != type_may_be_null(dst_reg->type) &&
            base_type(src_reg->type) != PTR_TO_BTF_ID &&
            base_type(dst_reg->type) != PTR_TO_BTF_ID) {
                eq_branch_regs = NULL;
                switch (opcode) {
                case BPF_JEQ:
                        eq_branch_regs = other_branch_regs;
                        break;
                case BPF_JNE:
                        eq_branch_regs = regs;
                        break;
                default:
                        /* do nothing */
                        break;
                }
                if (eq_branch_regs) {
                        if (type_may_be_null(src_reg->type))
                                mark_ptr_not_null_reg(&eq_branch_regs[insn->src_reg]);
                        else
                                mark_ptr_not_null_reg(&eq_branch_regs[insn->dst_reg]);
                }
        }

        /* detect if R == 0 where R is returned from bpf_map_lookup_elem().
         * Also does the same detection for a register whose the value is
         * known to be 0.
         * NOTE: these optimizations below are related with pointer comparison
         *       which will never be JMP32.
         */
        if (!is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
            type_may_be_null(dst_reg->type) &&
            ((BPF_SRC(insn->code) == BPF_K && insn->imm == 0) ||
             (BPF_SRC(insn->code) == BPF_X && bpf_register_is_null(src_reg)))) {
                /* Mark all identical registers in each branch as either
                 * safe or unknown depending R == 0 or R != 0 conditional.
                 */
                mark_ptr_or_null_regs(this_branch, insn->dst_reg,
                                      opcode == BPF_JNE);
                mark_ptr_or_null_regs(other_branch, insn->dst_reg,
                                      opcode == BPF_JEQ);
        } else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg],
                                           this_branch, other_branch) &&
                   is_pointer_value(env, insn->dst_reg)) {
                verbose(env, "R%d pointer comparison prohibited\n",
                        insn->dst_reg);
                return -EACCES;
        }
        if (env->log.level & BPF_LOG_LEVEL)
                print_insn_state(env, this_branch, this_branch->curframe);
        return 0;
}

/* verify BPF_LD_IMM64 instruction */
static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        struct bpf_insn_aux_data *aux = cur_aux(env);
        struct bpf_reg_state *regs = cur_regs(env);
        struct bpf_reg_state *dst_reg;
        struct bpf_map *map;
        int err;

        if (BPF_SIZE(insn->code) != BPF_DW) {
                verbose(env, "invalid BPF_LD_IMM insn\n");
                return -EINVAL;
        }

        err = check_reg_arg(env, insn->dst_reg, DST_OP);
        if (err)
                return err;

        dst_reg = &regs[insn->dst_reg];
        if (insn->src_reg == 0) {
                u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;

                dst_reg->type = SCALAR_VALUE;
                __mark_reg_known(&regs[insn->dst_reg], imm);
                return 0;
        }

        /* All special src_reg cases are listed below. From this point onwards
         * we either succeed and assign a corresponding dst_reg->type after
         * zeroing the offset, or fail and reject the program.
         */
        mark_reg_known_zero(env, regs, insn->dst_reg);

        if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
                dst_reg->type = aux->btf_var.reg_type;
                switch (base_type(dst_reg->type)) {
                case PTR_TO_MEM:
                        dst_reg->mem_size = aux->btf_var.mem_size;
                        break;
                case PTR_TO_BTF_ID:
                        dst_reg->btf = aux->btf_var.btf;
                        dst_reg->btf_id = aux->btf_var.btf_id;
                        break;
                default:
                        verifier_bug(env, "pseudo btf id: unexpected dst reg type");
                        return -EFAULT;
                }
                return 0;
        }

        if (insn->src_reg == BPF_PSEUDO_FUNC) {
                struct bpf_prog_aux *aux = env->prog->aux;
                u32 subprogno = bpf_find_subprog(env,
                                                 env->insn_idx + insn->imm + 1);

                if (!aux->func_info) {
                        verbose(env, "missing btf func_info\n");
                        return -EINVAL;
                }
                if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) {
                        verbose(env, "callback function not static\n");
                        return -EINVAL;
                }

                dst_reg->type = PTR_TO_FUNC;
                dst_reg->subprogno = subprogno;
                return 0;
        }

        map = env->used_maps[aux->map_index];

        if (insn->src_reg == BPF_PSEUDO_MAP_VALUE ||
            insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) {
                if (map->map_type == BPF_MAP_TYPE_ARENA) {
                        __mark_reg_unknown(env, dst_reg);
                        dst_reg->map_ptr = map;
                        return 0;
                }
                __mark_reg_known(dst_reg, aux->map_off);
                dst_reg->type = PTR_TO_MAP_VALUE;
                dst_reg->map_ptr = map;
                WARN_ON_ONCE(map->map_type != BPF_MAP_TYPE_INSN_ARRAY &&
                             map->max_entries != 1);
                /* We want reg->id to be same (0) as map_value is not distinct */
        } else if (insn->src_reg == BPF_PSEUDO_MAP_FD ||
                   insn->src_reg == BPF_PSEUDO_MAP_IDX) {
                dst_reg->type = CONST_PTR_TO_MAP;
                dst_reg->map_ptr = map;
        } else {
                verifier_bug(env, "unexpected src reg value for ldimm64");
                return -EFAULT;
        }

        return 0;
}

static bool may_access_skb(enum bpf_prog_type type)
{
        switch (type) {
        case BPF_PROG_TYPE_SOCKET_FILTER:
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
                return true;
        default:
                return false;
        }
}

/* verify safety of LD_ABS|LD_IND instructions:
 * - they can only appear in the programs where ctx == skb
 * - since they are wrappers of function calls, they scratch R1-R5 registers,
 *   preserve R6-R9, and store return value into R0
 *
 * Implicit input:
 *   ctx == skb == R6 == CTX
 *
 * Explicit input:
 *   SRC == any register
 *   IMM == 32-bit immediate
 *
 * Output:
 *   R0 - 8/16/32-bit skb data converted to cpu endianness
 */
static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        struct bpf_reg_state *regs = cur_regs(env);
        static const int ctx_reg = BPF_REG_6;
        u8 mode = BPF_MODE(insn->code);
        int i, err;

        if (!may_access_skb(resolve_prog_type(env->prog))) {
                verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
                return -EINVAL;
        }

        if (!env->ops->gen_ld_abs) {
                verifier_bug(env, "gen_ld_abs is null");
                return -EFAULT;
        }

        /* check whether implicit source operand (register R6) is readable */
        err = check_reg_arg(env, ctx_reg, SRC_OP);
        if (err)
                return err;

        /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
         * gen_ld_abs() may terminate the program at runtime, leading to
         * reference leak.
         */
        err = check_resource_leak(env, false, true, "BPF_LD_[ABS|IND]");
        if (err)
                return err;

        if (regs[ctx_reg].type != PTR_TO_CTX) {
                verbose(env,
                        "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
                return -EINVAL;
        }

        if (mode == BPF_IND) {
                /* check explicit source operand */
                err = check_reg_arg(env, insn->src_reg, SRC_OP);
                if (err)
                        return err;
        }

        err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
        if (err < 0)
                return err;

        /* reset caller saved regs to unreadable */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                bpf_mark_reg_not_init(env, &regs[caller_saved[i]]);
                check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
        }

        /* mark destination R0 register as readable, since it contains
         * the value fetched from the packet.
         * Already marked as written above.
         */
        mark_reg_unknown(env, regs, BPF_REG_0);
        /* ld_abs load up to 32-bit skb data. */
        regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
        /*
         * See bpf_gen_ld_abs() which emits a hidden BPF_EXIT with r0=0
         * which must be explored by the verifier when in a subprog.
         */
        if (env->cur_state->curframe) {
                struct bpf_verifier_state *branch;

                mark_reg_scratched(env, BPF_REG_0);
                branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
                if (IS_ERR(branch))
                        return PTR_ERR(branch);
                mark_reg_known_zero(env, regs, BPF_REG_0);
                err = prepare_func_exit(env, &env->insn_idx);
                if (err)
                        return err;
                env->insn_idx--;
        }
        return 0;
}


static bool return_retval_range(struct bpf_verifier_env *env, struct bpf_retval_range *range)
{
        enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

        /* Default return value range. */
        *range = retval_range(0, 1);

        switch (prog_type) {
        case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
                switch (env->prog->expected_attach_type) {
                case BPF_CGROUP_UDP4_RECVMSG:
                case BPF_CGROUP_UDP6_RECVMSG:
                case BPF_CGROUP_UNIX_RECVMSG:
                case BPF_CGROUP_INET4_GETPEERNAME:
                case BPF_CGROUP_INET6_GETPEERNAME:
                case BPF_CGROUP_UNIX_GETPEERNAME:
                case BPF_CGROUP_INET4_GETSOCKNAME:
                case BPF_CGROUP_INET6_GETSOCKNAME:
                case BPF_CGROUP_UNIX_GETSOCKNAME:
                        *range = retval_range(1, 1);
                        break;
                case BPF_CGROUP_INET4_BIND:
                case BPF_CGROUP_INET6_BIND:
                        *range = retval_range(0, 3);
                        break;
                default:
                        break;
                }
                break;
        case BPF_PROG_TYPE_CGROUP_SKB:
                if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS)
                        *range = retval_range(0, 3);
                break;
        case BPF_PROG_TYPE_CGROUP_SOCK:
        case BPF_PROG_TYPE_SOCK_OPS:
        case BPF_PROG_TYPE_CGROUP_DEVICE:
        case BPF_PROG_TYPE_CGROUP_SYSCTL:
        case BPF_PROG_TYPE_CGROUP_SOCKOPT:
                break;
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
                if (!env->prog->aux->attach_btf_id)
                        return false;
                *range = retval_range(0, 0);
                break;
        case BPF_PROG_TYPE_TRACING:
                switch (env->prog->expected_attach_type) {
                case BPF_TRACE_FENTRY:
                case BPF_TRACE_FEXIT:
                case BPF_TRACE_FSESSION:
                        *range = retval_range(0, 0);
                        break;
                case BPF_TRACE_RAW_TP:
                case BPF_MODIFY_RETURN:
                        return false;
                case BPF_TRACE_ITER:
                default:
                        break;
                }
                break;
        case BPF_PROG_TYPE_KPROBE:
                switch (env->prog->expected_attach_type) {
                case BPF_TRACE_KPROBE_SESSION:
                case BPF_TRACE_UPROBE_SESSION:
                        break;
                default:
                        return false;
                }
                break;
        case BPF_PROG_TYPE_SK_LOOKUP:
                *range = retval_range(SK_DROP, SK_PASS);
                break;

        case BPF_PROG_TYPE_LSM:
                if (env->prog->expected_attach_type != BPF_LSM_CGROUP) {
                        /* no range found, any return value is allowed */
                        if (!get_func_retval_range(env->prog, range))
                                return false;
                        /* no restricted range, any return value is allowed */
                        if (range->minval == S32_MIN && range->maxval == S32_MAX)
                                return false;
                        range->return_32bit = true;
                } else if (!env->prog->aux->attach_func_proto->type) {
                        /* Make sure programs that attach to void
                         * hooks don't try to modify return value.
                         */
                        *range = retval_range(1, 1);
                }
                break;

        case BPF_PROG_TYPE_NETFILTER:
                *range = retval_range(NF_DROP, NF_ACCEPT);
                break;
        case BPF_PROG_TYPE_STRUCT_OPS:
                *range = retval_range(0, 0);
                break;
        case BPF_PROG_TYPE_EXT:
                /* freplace program can return anything as its return value
                 * depends on the to-be-replaced kernel func or bpf program.
                 */
        default:
                return false;
        }

        /* Continue calculating. */

        return true;
}

static bool program_returns_void(struct bpf_verifier_env *env)
{
        const struct bpf_prog *prog = env->prog;
        enum bpf_prog_type prog_type = prog->type;

        switch (prog_type) {
        case BPF_PROG_TYPE_LSM:
                /* See return_retval_range, for BPF_LSM_CGROUP can be 0 or 0-1 depending on hook. */
                if (prog->expected_attach_type != BPF_LSM_CGROUP &&
                    !prog->aux->attach_func_proto->type)
                        return true;
                break;
        case BPF_PROG_TYPE_STRUCT_OPS:
                if (!prog->aux->attach_func_proto->type)
                        return true;
                break;
        case BPF_PROG_TYPE_EXT:
                /*
                 * If the actual program is an extension, let it
                 * return void - attaching will succeed only if the
                 * program being replaced also returns void, and since
                 * it has passed verification its actual type doesn't matter.
                 */
                if (subprog_returns_void(env, 0))
                        return true;
                break;
        default:
                break;
        }
        return false;
}

static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name)
{
        const char *exit_ctx = "At program exit";
        struct tnum enforce_attach_type_range = tnum_unknown;
        const struct bpf_prog *prog = env->prog;
        struct bpf_reg_state *reg = reg_state(env, regno);
        struct bpf_retval_range range = retval_range(0, 1);
        enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
        struct bpf_func_state *frame = env->cur_state->frame[0];
        const struct btf_type *reg_type, *ret_type = NULL;
        int err;

        /* LSM and struct_ops func-ptr's return type could be "void" */
        if (!frame->in_async_callback_fn && program_returns_void(env))
                return 0;

        if (prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
                /* Allow a struct_ops program to return a referenced kptr if it
                 * matches the operator's return type and is in its unmodified
                 * form. A scalar zero (i.e., a null pointer) is also allowed.
                 */
                reg_type = reg->btf ? btf_type_by_id(reg->btf, reg->btf_id) : NULL;
                ret_type = btf_type_resolve_ptr(prog->aux->attach_btf,
                                                prog->aux->attach_func_proto->type,
                                                NULL);
                if (ret_type && ret_type == reg_type && reg->ref_obj_id)
                        return __check_ptr_off_reg(env, reg, regno, false);
        }

        /* eBPF calling convention is such that R0 is used
         * to return the value from eBPF program.
         * Make sure that it's readable at this time
         * of bpf_exit, which means that program wrote
         * something into it earlier
         */
        err = check_reg_arg(env, regno, SRC_OP);
        if (err)
                return err;

        if (is_pointer_value(env, regno)) {
                verbose(env, "R%d leaks addr as return value\n", regno);
                return -EACCES;
        }

        if (frame->in_async_callback_fn) {
                exit_ctx = "At async callback return";
                range = frame->callback_ret_range;
                goto enforce_retval;
        }

        if (prog_type == BPF_PROG_TYPE_STRUCT_OPS && !ret_type)
                return 0;

        if (prog_type == BPF_PROG_TYPE_CGROUP_SKB && (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS))
                enforce_attach_type_range = tnum_range(2, 3);

        if (!return_retval_range(env, &range))
                return 0;

enforce_retval:
        if (reg->type != SCALAR_VALUE) {
                verbose(env, "%s the register R%d is not a known value (%s)\n",
                        exit_ctx, regno, reg_type_str(env, reg->type));
                return -EINVAL;
        }

        err = mark_chain_precision(env, regno);
        if (err)
                return err;

        if (!retval_range_within(range, reg)) {
                verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name);
                if (prog->expected_attach_type == BPF_LSM_CGROUP &&
                    prog_type == BPF_PROG_TYPE_LSM &&
                    !prog->aux->attach_func_proto->type)
                        verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
                return -EINVAL;
        }

        if (!tnum_is_unknown(enforce_attach_type_range) &&
            tnum_in(enforce_attach_type_range, reg->var_off))
                env->prog->enforce_expected_attach_type = 1;
        return 0;
}

static int check_global_subprog_return_code(struct bpf_verifier_env *env)
{
        struct bpf_reg_state *reg = reg_state(env, BPF_REG_0);
        struct bpf_func_state *cur_frame = cur_func(env);
        int err;

        if (subprog_returns_void(env, cur_frame->subprogno))
                return 0;

        err = check_reg_arg(env, BPF_REG_0, SRC_OP);
        if (err)
                return err;

        if (is_pointer_value(env, BPF_REG_0)) {
                verbose(env, "R%d leaks addr as return value\n", BPF_REG_0);
                return -EACCES;
        }

        if (reg->type != SCALAR_VALUE) {
                verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n",
                        reg_type_str(env, reg->type));
                return -EINVAL;
        }

        return 0;
}

/* Bitmask with 1s for all caller saved registers */
#define ALL_CALLER_SAVED_REGS ((1u << CALLER_SAVED_REGS) - 1)

/* True if do_misc_fixups() replaces calls to helper number 'imm',
 * replacement patch is presumed to follow bpf_fastcall contract
 * (see mark_fastcall_pattern_for_call() below).
 */
bool bpf_verifier_inlines_helper_call(struct bpf_verifier_env *env, s32 imm)
{
        switch (imm) {
#ifdef CONFIG_X86_64
        case BPF_FUNC_get_smp_processor_id:
#ifdef CONFIG_SMP
        case BPF_FUNC_get_current_task_btf:
        case BPF_FUNC_get_current_task:
#endif
                return env->prog->jit_requested && bpf_jit_supports_percpu_insn();
#endif
        default:
                return false;
        }
}

/* If @call is a kfunc or helper call, fills @cs and returns true,
 * otherwise returns false.
 */
bool bpf_get_call_summary(struct bpf_verifier_env *env, struct bpf_insn *call,
                          struct bpf_call_summary *cs)
{
        struct bpf_kfunc_call_arg_meta meta;
        const struct bpf_func_proto *fn;
        int i;

        if (bpf_helper_call(call)) {

                if (bpf_get_helper_proto(env, call->imm, &fn) < 0)
                        /* error would be reported later */
                        return false;
                cs->fastcall = fn->allow_fastcall &&
                               (bpf_verifier_inlines_helper_call(env, call->imm) ||
                                bpf_jit_inlines_helper_call(call->imm));
                cs->is_void = fn->ret_type == RET_VOID;
                cs->num_params = 0;
                for (i = 0; i < ARRAY_SIZE(fn->arg_type); ++i) {
                        if (fn->arg_type[i] == ARG_DONTCARE)
                                break;
                        cs->num_params++;
                }
                return true;
        }

        if (bpf_pseudo_kfunc_call(call)) {
                int err;

                err = bpf_fetch_kfunc_arg_meta(env, call->imm, call->off, &meta);
                if (err < 0)
                        /* error would be reported later */
                        return false;
                cs->num_params = btf_type_vlen(meta.func_proto);
                cs->fastcall = meta.kfunc_flags & KF_FASTCALL;
                cs->is_void = btf_type_is_void(btf_type_by_id(meta.btf, meta.func_proto->type));
                return true;
        }

        return false;
}

/* LLVM define a bpf_fastcall function attribute.
 * This attribute means that function scratches only some of
 * the caller saved registers defined by ABI.
 * For BPF the set of such registers could be defined as follows:
 * - R0 is scratched only if function is non-void;
 * - R1-R5 are scratched only if corresponding parameter type is defined
 *   in the function prototype.
 *
 * The contract between kernel and clang allows to simultaneously use
 * such functions and maintain backwards compatibility with old
 * kernels that don't understand bpf_fastcall calls:
 *
 * - for bpf_fastcall calls clang allocates registers as-if relevant r0-r5
 *   registers are not scratched by the call;
 *
 * - as a post-processing step, clang visits each bpf_fastcall call and adds
 *   spill/fill for every live r0-r5;
 *
 * - stack offsets used for the spill/fill are allocated as lowest
 *   stack offsets in whole function and are not used for any other
 *   purposes;
 *
 * - when kernel loads a program, it looks for such patterns
 *   (bpf_fastcall function surrounded by spills/fills) and checks if
 *   spill/fill stack offsets are used exclusively in fastcall patterns;
 *
 * - if so, and if verifier or current JIT inlines the call to the
 *   bpf_fastcall function (e.g. a helper call), kernel removes unnecessary
 *   spill/fill pairs;
 *
 * - when old kernel loads a program, presence of spill/fill pairs
 *   keeps BPF program valid, albeit slightly less efficient.
 *
 * For example:
 *
 *   r1 = 1;
 *   r2 = 2;
 *   *(u64 *)(r10 - 8)  = r1;            r1 = 1;
 *   *(u64 *)(r10 - 16) = r2;            r2 = 2;
 *   call %[to_be_inlined]         -->   call %[to_be_inlined]
 *   r2 = *(u64 *)(r10 - 16);            r0 = r1;
 *   r1 = *(u64 *)(r10 - 8);             r0 += r2;
 *   r0 = r1;                            exit;
 *   r0 += r2;
 *   exit;
 *
 * The purpose of mark_fastcall_pattern_for_call is to:
 * - look for such patterns;
 * - mark spill and fill instructions in env->insn_aux_data[*].fastcall_pattern;
 * - mark set env->insn_aux_data[*].fastcall_spills_num for call instruction;
 * - update env->subprog_info[*]->fastcall_stack_off to find an offset
 *   at which bpf_fastcall spill/fill stack slots start;
 * - update env->subprog_info[*]->keep_fastcall_stack.
 *
 * The .fastcall_pattern and .fastcall_stack_off are used by
 * check_fastcall_stack_contract() to check if every stack access to
 * fastcall spill/fill stack slot originates from spill/fill
 * instructions, members of fastcall patterns.
 *
 * If such condition holds true for a subprogram, fastcall patterns could
 * be rewritten by remove_fastcall_spills_fills().
 * Otherwise bpf_fastcall patterns are not changed in the subprogram
 * (code, presumably, generated by an older clang version).
 *
 * For example, it is *not* safe to remove spill/fill below:
 *
 *   r1 = 1;
 *   *(u64 *)(r10 - 8)  = r1;            r1 = 1;
 *   call %[to_be_inlined]         -->   call %[to_be_inlined]
 *   r1 = *(u64 *)(r10 - 8);             r0 = *(u64 *)(r10 - 8);  <---- wrong !!!
 *   r0 = *(u64 *)(r10 - 8);             r0 += r1;
 *   r0 += r1;                           exit;
 *   exit;
 */
static void mark_fastcall_pattern_for_call(struct bpf_verifier_env *env,
                                           struct bpf_subprog_info *subprog,
                                           int insn_idx, s16 lowest_off)
{
        struct bpf_insn *insns = env->prog->insnsi, *stx, *ldx;
        struct bpf_insn *call = &env->prog->insnsi[insn_idx];
        u32 clobbered_regs_mask;
        struct bpf_call_summary cs;
        u32 expected_regs_mask;
        s16 off;
        int i;

        if (!bpf_get_call_summary(env, call, &cs))
                return;

        /* A bitmask specifying which caller saved registers are clobbered
         * by a call to a helper/kfunc *as if* this helper/kfunc follows
         * bpf_fastcall contract:
         * - includes R0 if function is non-void;
         * - includes R1-R5 if corresponding parameter has is described
         *   in the function prototype.
         */
        clobbered_regs_mask = GENMASK(cs.num_params, cs.is_void ? 1 : 0);
        /* e.g. if helper call clobbers r{0,1}, expect r{2,3,4,5} in the pattern */
        expected_regs_mask = ~clobbered_regs_mask & ALL_CALLER_SAVED_REGS;

        /* match pairs of form:
         *
         * *(u64 *)(r10 - Y) = rX   (where Y % 8 == 0)
         * ...
         * call %[to_be_inlined]
         * ...
         * rX = *(u64 *)(r10 - Y)
         */
        for (i = 1, off = lowest_off; i <= ARRAY_SIZE(caller_saved); ++i, off += BPF_REG_SIZE) {
                if (insn_idx - i < 0 || insn_idx + i >= env->prog->len)
                        break;
                stx = &insns[insn_idx - i];
                ldx = &insns[insn_idx + i];
                /* must be a stack spill/fill pair */
                if (stx->code != (BPF_STX | BPF_MEM | BPF_DW) ||
                    ldx->code != (BPF_LDX | BPF_MEM | BPF_DW) ||
                    stx->dst_reg != BPF_REG_10 ||
                    ldx->src_reg != BPF_REG_10)
                        break;
                /* must be a spill/fill for the same reg */
                if (stx->src_reg != ldx->dst_reg)
                        break;
                /* must be one of the previously unseen registers */
                if ((BIT(stx->src_reg) & expected_regs_mask) == 0)
                        break;
                /* must be a spill/fill for the same expected offset,
                 * no need to check offset alignment, BPF_DW stack access
                 * is always 8-byte aligned.
                 */
                if (stx->off != off || ldx->off != off)
                        break;
                expected_regs_mask &= ~BIT(stx->src_reg);
                env->insn_aux_data[insn_idx - i].fastcall_pattern = 1;
                env->insn_aux_data[insn_idx + i].fastcall_pattern = 1;
        }
        if (i == 1)
                return;

        /* Conditionally set 'fastcall_spills_num' to allow forward
         * compatibility when more helper functions are marked as
         * bpf_fastcall at compile time than current kernel supports, e.g:
         *
         *   1: *(u64 *)(r10 - 8) = r1
         *   2: call A                  ;; assume A is bpf_fastcall for current kernel
         *   3: r1 = *(u64 *)(r10 - 8)
         *   4: *(u64 *)(r10 - 8) = r1
         *   5: call B                  ;; assume B is not bpf_fastcall for current kernel
         *   6: r1 = *(u64 *)(r10 - 8)
         *
         * There is no need to block bpf_fastcall rewrite for such program.
         * Set 'fastcall_pattern' for both calls to keep check_fastcall_stack_contract() happy,
         * don't set 'fastcall_spills_num' for call B so that remove_fastcall_spills_fills()
         * does not remove spill/fill pair {4,6}.
         */
        if (cs.fastcall)
                env->insn_aux_data[insn_idx].fastcall_spills_num = i - 1;
        else
                subprog->keep_fastcall_stack = 1;
        subprog->fastcall_stack_off = min(subprog->fastcall_stack_off, off);
}

static int mark_fastcall_patterns(struct bpf_verifier_env *env)
{
        struct bpf_subprog_info *subprog = env->subprog_info;
        struct bpf_insn *insn;
        s16 lowest_off;
        int s, i;

        for (s = 0; s < env->subprog_cnt; ++s, ++subprog) {
                /* find lowest stack spill offset used in this subprog */
                lowest_off = 0;
                for (i = subprog->start; i < (subprog + 1)->start; ++i) {
                        insn = env->prog->insnsi + i;
                        if (insn->code != (BPF_STX | BPF_MEM | BPF_DW) ||
                            insn->dst_reg != BPF_REG_10)
                                continue;
                        lowest_off = min(lowest_off, insn->off);
                }
                /* use this offset to find fastcall patterns */
                for (i = subprog->start; i < (subprog + 1)->start; ++i) {
                        insn = env->prog->insnsi + i;
                        if (insn->code != (BPF_JMP | BPF_CALL))
                                continue;
                        mark_fastcall_pattern_for_call(env, subprog, i, lowest_off);
                }
        }
        return 0;
}

static void adjust_btf_func(struct bpf_verifier_env *env)
{
        struct bpf_prog_aux *aux = env->prog->aux;
        int i;

        if (!aux->func_info)
                return;

        /* func_info is not available for hidden subprogs */
        for (i = 0; i < env->subprog_cnt - env->hidden_subprog_cnt; i++)
                aux->func_info[i].insn_off = env->subprog_info[i].start;
}

/* Find id in idset and increment its count, or add new entry */
static void idset_cnt_inc(struct bpf_idset *idset, u32 id)
{
        u32 i;

        for (i = 0; i < idset->num_ids; i++) {
                if (idset->entries[i].id == id) {
                        idset->entries[i].cnt++;
                        return;
                }
        }
        /* New id */
        if (idset->num_ids < BPF_ID_MAP_SIZE) {
                idset->entries[idset->num_ids].id = id;
                idset->entries[idset->num_ids].cnt = 1;
                idset->num_ids++;
        }
}

/* Find id in idset and return its count, or 0 if not found */
static u32 idset_cnt_get(struct bpf_idset *idset, u32 id)
{
        u32 i;

        for (i = 0; i < idset->num_ids; i++) {
                if (idset->entries[i].id == id)
                        return idset->entries[i].cnt;
        }
        return 0;
}

/*
 * Clear singular scalar ids in a state.
 * A register with a non-zero id is called singular if no other register shares
 * the same base id. Such registers can be treated as independent (id=0).
 */
void bpf_clear_singular_ids(struct bpf_verifier_env *env,
                            struct bpf_verifier_state *st)
{
        struct bpf_idset *idset = &env->idset_scratch;
        struct bpf_func_state *func;
        struct bpf_reg_state *reg;

        idset->num_ids = 0;

        bpf_for_each_reg_in_vstate(st, func, reg, ({
                if (reg->type != SCALAR_VALUE)
                        continue;
                if (!reg->id)
                        continue;
                idset_cnt_inc(idset, reg->id & ~BPF_ADD_CONST);
        }));

        bpf_for_each_reg_in_vstate(st, func, reg, ({
                if (reg->type != SCALAR_VALUE)
                        continue;
                if (!reg->id)
                        continue;
                if (idset_cnt_get(idset, reg->id & ~BPF_ADD_CONST) == 1)
                        clear_scalar_id(reg);
        }));
}

/* Return true if it's OK to have the same insn return a different type. */
static bool reg_type_mismatch_ok(enum bpf_reg_type type)
{
        switch (base_type(type)) {
        case PTR_TO_CTX:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
        case PTR_TO_BTF_ID:
        case PTR_TO_ARENA:
                return false;
        default:
                return true;
        }
}

/* If an instruction was previously used with particular pointer types, then we
 * need to be careful to avoid cases such as the below, where it may be ok
 * for one branch accessing the pointer, but not ok for the other branch:
 *
 * R1 = sock_ptr
 * goto X;
 * ...
 * R1 = some_other_valid_ptr;
 * goto X;
 * ...
 * R2 = *(u32 *)(R1 + 0);
 */
static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
{
        return src != prev && (!reg_type_mismatch_ok(src) ||
                               !reg_type_mismatch_ok(prev));
}

static bool is_ptr_to_mem_or_btf_id(enum bpf_reg_type type)
{
        switch (base_type(type)) {
        case PTR_TO_MEM:
        case PTR_TO_BTF_ID:
                return true;
        default:
                return false;
        }
}

static bool is_ptr_to_mem(enum bpf_reg_type type)
{
        return base_type(type) == PTR_TO_MEM;
}

static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
                             bool allow_trust_mismatch)
{
        enum bpf_reg_type *prev_type = &env->insn_aux_data[env->insn_idx].ptr_type;
        enum bpf_reg_type merged_type;

        if (*prev_type == NOT_INIT) {
                /* Saw a valid insn
                 * dst_reg = *(u32 *)(src_reg + off)
                 * save type to validate intersecting paths
                 */
                *prev_type = type;
        } else if (reg_type_mismatch(type, *prev_type)) {
                /* Abuser program is trying to use the same insn
                 * dst_reg = *(u32*) (src_reg + off)
                 * with different pointer types:
                 * src_reg == ctx in one branch and
                 * src_reg == stack|map in some other branch.
                 * Reject it.
                 */
                if (allow_trust_mismatch &&
                    is_ptr_to_mem_or_btf_id(type) &&
                    is_ptr_to_mem_or_btf_id(*prev_type)) {
                        /*
                         * Have to support a use case when one path through
                         * the program yields TRUSTED pointer while another
                         * is UNTRUSTED. Fallback to UNTRUSTED to generate
                         * BPF_PROBE_MEM/BPF_PROBE_MEMSX.
                         * Same behavior of MEM_RDONLY flag.
                         */
                        if (is_ptr_to_mem(type) || is_ptr_to_mem(*prev_type))
                                merged_type = PTR_TO_MEM;
                        else
                                merged_type = PTR_TO_BTF_ID;
                        if ((type & PTR_UNTRUSTED) || (*prev_type & PTR_UNTRUSTED))
                                merged_type |= PTR_UNTRUSTED;
                        if ((type & MEM_RDONLY) || (*prev_type & MEM_RDONLY))
                                merged_type |= MEM_RDONLY;
                        *prev_type = merged_type;
                } else {
                        verbose(env, "same insn cannot be used with different pointers\n");
                        return -EINVAL;
                }
        }

        return 0;
}

enum {
        PROCESS_BPF_EXIT = 1,
        INSN_IDX_UPDATED = 2,
};

static int process_bpf_exit_full(struct bpf_verifier_env *env,
                                 bool *do_print_state,
                                 bool exception_exit)
{
        struct bpf_func_state *cur_frame = cur_func(env);

        /* We must do check_reference_leak here before
         * prepare_func_exit to handle the case when
         * state->curframe > 0, it may be a callback function,
         * for which reference_state must match caller reference
         * state when it exits.
         */
        int err = check_resource_leak(env, exception_exit,
                                      exception_exit || !env->cur_state->curframe,
                                      exception_exit ? "bpf_throw" :
                                      "BPF_EXIT instruction in main prog");
        if (err)
                return err;

        /* The side effect of the prepare_func_exit which is
         * being skipped is that it frees bpf_func_state.
         * Typically, process_bpf_exit will only be hit with
         * outermost exit. copy_verifier_state in pop_stack will
         * handle freeing of any extra bpf_func_state left over
         * from not processing all nested function exits. We
         * also skip return code checks as they are not needed
         * for exceptional exits.
         */
        if (exception_exit)
                return PROCESS_BPF_EXIT;

        if (env->cur_state->curframe) {
                /* exit from nested function */
                err = prepare_func_exit(env, &env->insn_idx);
                if (err)
                        return err;
                *do_print_state = true;
                return INSN_IDX_UPDATED;
        }

        /*
         * Return from a regular global subprogram differs from return
         * from the main program or async/exception callback.
         * Main program exit implies return code restrictions
         * that depend on program type.
         * Exit from exception callback is equivalent to main program exit.
         * Exit from async callback implies return code restrictions
         * that depend on async scheduling mechanism.
         */
        if (cur_frame->subprogno &&
            !cur_frame->in_async_callback_fn &&
            !cur_frame->in_exception_callback_fn)
                err = check_global_subprog_return_code(env);
        else
                err = check_return_code(env, BPF_REG_0, "R0");
        if (err)
                return err;
        return PROCESS_BPF_EXIT;
}

static int indirect_jump_min_max_index(struct bpf_verifier_env *env,
                                       int regno,
                                       struct bpf_map *map,
                                       u32 *pmin_index, u32 *pmax_index)
{
        struct bpf_reg_state *reg = reg_state(env, regno);
        u64 min_index = reg->umin_value;
        u64 max_index = reg->umax_value;
        const u32 size = 8;

        if (min_index > (u64) U32_MAX * size) {
                verbose(env, "the sum of R%u umin_value %llu is too big\n", regno, reg->umin_value);
                return -ERANGE;
        }
        if (max_index > (u64) U32_MAX * size) {
                verbose(env, "the sum of R%u umax_value %llu is too big\n", regno, reg->umax_value);
                return -ERANGE;
        }

        min_index /= size;
        max_index /= size;

        if (max_index >= map->max_entries) {
                verbose(env, "R%u points to outside of jump table: [%llu,%llu] max_entries %u\n",
                             regno, min_index, max_index, map->max_entries);
                return -EINVAL;
        }

        *pmin_index = min_index;
        *pmax_index = max_index;
        return 0;
}

/* gotox *dst_reg */
static int check_indirect_jump(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        struct bpf_verifier_state *other_branch;
        struct bpf_reg_state *dst_reg;
        struct bpf_map *map;
        u32 min_index, max_index;
        int err = 0;
        int n;
        int i;

        dst_reg = reg_state(env, insn->dst_reg);
        if (dst_reg->type != PTR_TO_INSN) {
                verbose(env, "R%d has type %s, expected PTR_TO_INSN\n",
                             insn->dst_reg, reg_type_str(env, dst_reg->type));
                return -EINVAL;
        }

        map = dst_reg->map_ptr;
        if (verifier_bug_if(!map, env, "R%d has an empty map pointer", insn->dst_reg))
                return -EFAULT;

        if (verifier_bug_if(map->map_type != BPF_MAP_TYPE_INSN_ARRAY, env,
                            "R%d has incorrect map type %d", insn->dst_reg, map->map_type))
                return -EFAULT;

        err = indirect_jump_min_max_index(env, insn->dst_reg, map, &min_index, &max_index);
        if (err)
                return err;

        /* Ensure that the buffer is large enough */
        if (!env->gotox_tmp_buf || env->gotox_tmp_buf->cnt < max_index - min_index + 1) {
                env->gotox_tmp_buf = bpf_iarray_realloc(env->gotox_tmp_buf,
                                                        max_index - min_index + 1);
                if (!env->gotox_tmp_buf)
                        return -ENOMEM;
        }

        n = bpf_copy_insn_array_uniq(map, min_index, max_index, env->gotox_tmp_buf->items);
        if (n < 0)
                return n;
        if (n == 0) {
                verbose(env, "register R%d doesn't point to any offset in map id=%d\n",
                             insn->dst_reg, map->id);
                return -EINVAL;
        }

        for (i = 0; i < n - 1; i++) {
                mark_indirect_target(env, env->gotox_tmp_buf->items[i]);
                other_branch = push_stack(env, env->gotox_tmp_buf->items[i],
                                          env->insn_idx, env->cur_state->speculative);
                if (IS_ERR(other_branch))
                        return PTR_ERR(other_branch);
        }
        env->insn_idx = env->gotox_tmp_buf->items[n-1];
        mark_indirect_target(env, env->insn_idx);
        return INSN_IDX_UPDATED;
}

static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
{
        int err;
        struct bpf_insn *insn = &env->prog->insnsi[env->insn_idx];
        u8 class = BPF_CLASS(insn->code);

        switch (class) {
        case BPF_ALU:
        case BPF_ALU64:
                return check_alu_op(env, insn);

        case BPF_LDX:
                return check_load_mem(env, insn, false,
                                      BPF_MODE(insn->code) == BPF_MEMSX,
                                      true, "ldx");

        case BPF_STX:
                if (BPF_MODE(insn->code) == BPF_ATOMIC)
                        return check_atomic(env, insn);
                return check_store_reg(env, insn, false);

        case BPF_ST: {
                enum bpf_reg_type dst_reg_type;

                err = check_reg_arg(env, insn->dst_reg, SRC_OP);
                if (err)
                        return err;

                dst_reg_type = cur_regs(env)[insn->dst_reg].type;

                err = check_mem_access(env, env->insn_idx, insn->dst_reg,
                                       insn->off, BPF_SIZE(insn->code),
                                       BPF_WRITE, -1, false, false);
                if (err)
                        return err;

                return save_aux_ptr_type(env, dst_reg_type, false);
        }
        case BPF_JMP:
        case BPF_JMP32: {
                u8 opcode = BPF_OP(insn->code);

                env->jmps_processed++;
                if (opcode == BPF_CALL) {
                        if (env->cur_state->active_locks) {
                                if ((insn->src_reg == BPF_REG_0 &&
                                     insn->imm != BPF_FUNC_spin_unlock &&
                                     insn->imm != BPF_FUNC_kptr_xchg) ||
                                    (insn->src_reg == BPF_PSEUDO_KFUNC_CALL &&
                                     (insn->off != 0 || !kfunc_spin_allowed(insn->imm)))) {
                                        verbose(env,
                                                "function calls are not allowed while holding a lock\n");
                                        return -EINVAL;
                                }
                        }
                        mark_reg_scratched(env, BPF_REG_0);
                        if (insn->src_reg == BPF_PSEUDO_CALL)
                                return check_func_call(env, insn, &env->insn_idx);
                        if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL)
                                return check_kfunc_call(env, insn, &env->insn_idx);
                        return check_helper_call(env, insn, &env->insn_idx);
                } else if (opcode == BPF_JA) {
                        if (BPF_SRC(insn->code) == BPF_X)
                                return check_indirect_jump(env, insn);

                        if (class == BPF_JMP)
                                env->insn_idx += insn->off + 1;
                        else
                                env->insn_idx += insn->imm + 1;
                        return INSN_IDX_UPDATED;
                } else if (opcode == BPF_EXIT) {
                        return process_bpf_exit_full(env, do_print_state, false);
                }
                return check_cond_jmp_op(env, insn, &env->insn_idx);
        }
        case BPF_LD: {
                u8 mode = BPF_MODE(insn->code);

                if (mode == BPF_ABS || mode == BPF_IND)
                        return check_ld_abs(env, insn);

                if (mode == BPF_IMM) {
                        err = check_ld_imm(env, insn);
                        if (err)
                                return err;

                        env->insn_idx++;
                        sanitize_mark_insn_seen(env);
                }
                return 0;
        }
        }
        /* all class values are handled above. silence compiler warning */
        return -EFAULT;
}

static int do_check(struct bpf_verifier_env *env)
{
        bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
        struct bpf_verifier_state *state = env->cur_state;
        struct bpf_insn *insns = env->prog->insnsi;
        int insn_cnt = env->prog->len;
        bool do_print_state = false;
        int prev_insn_idx = -1;

        for (;;) {
                struct bpf_insn *insn;
                struct bpf_insn_aux_data *insn_aux;
                int err;

                /* reset current history entry on each new instruction */
                env->cur_hist_ent = NULL;

                env->prev_insn_idx = prev_insn_idx;
                if (env->insn_idx >= insn_cnt) {
                        verbose(env, "invalid insn idx %d insn_cnt %d\n",
                                env->insn_idx, insn_cnt);
                        return -EFAULT;
                }

                insn = &insns[env->insn_idx];
                insn_aux = &env->insn_aux_data[env->insn_idx];

                if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
                        verbose(env,
                                "BPF program is too large. Processed %d insn\n",
                                env->insn_processed);
                        return -E2BIG;
                }

                state->last_insn_idx = env->prev_insn_idx;
                state->insn_idx = env->insn_idx;

                if (bpf_is_prune_point(env, env->insn_idx)) {
                        err = bpf_is_state_visited(env, env->insn_idx);
                        if (err < 0)
                                return err;
                        if (err == 1) {
                                /* found equivalent state, can prune the search */
                                if (env->log.level & BPF_LOG_LEVEL) {
                                        if (do_print_state)
                                                verbose(env, "\nfrom %d to %d%s: safe\n",
                                                        env->prev_insn_idx, env->insn_idx,
                                                        env->cur_state->speculative ?
                                                        " (speculative execution)" : "");
                                        else
                                                verbose(env, "%d: safe\n", env->insn_idx);
                                }
                                goto process_bpf_exit;
                        }
                }

                if (bpf_is_jmp_point(env, env->insn_idx)) {
                        err = bpf_push_jmp_history(env, state, 0, 0);
                        if (err)
                                return err;
                }

                if (signal_pending(current))
                        return -EAGAIN;

                if (need_resched())
                        cond_resched();

                if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) {
                        verbose(env, "\nfrom %d to %d%s:",
                                env->prev_insn_idx, env->insn_idx,
                                env->cur_state->speculative ?
                                " (speculative execution)" : "");
                        print_verifier_state(env, state, state->curframe, true);
                        do_print_state = false;
                }

                if (env->log.level & BPF_LOG_LEVEL) {
                        if (verifier_state_scratched(env))
                                print_insn_state(env, state, state->curframe);

                        verbose_linfo(env, env->insn_idx, "; ");
                        env->prev_log_pos = env->log.end_pos;
                        verbose(env, "%d: ", env->insn_idx);
                        bpf_verbose_insn(env, insn);
                        env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos;
                        env->prev_log_pos = env->log.end_pos;
                }

                if (bpf_prog_is_offloaded(env->prog->aux)) {
                        err = bpf_prog_offload_verify_insn(env, env->insn_idx,
                                                           env->prev_insn_idx);
                        if (err)
                                return err;
                }

                sanitize_mark_insn_seen(env);
                prev_insn_idx = env->insn_idx;

                /* Sanity check: precomputed constants must match verifier state */
                if (!state->speculative && insn_aux->const_reg_mask) {
                        struct bpf_reg_state *regs = cur_regs(env);
                        u16 mask = insn_aux->const_reg_mask;

                        for (int r = 0; r < ARRAY_SIZE(insn_aux->const_reg_vals); r++) {
                                u32 cval = insn_aux->const_reg_vals[r];

                                if (!(mask & BIT(r)))
                                        continue;
                                if (regs[r].type != SCALAR_VALUE)
                                        continue;
                                if (!tnum_is_const(regs[r].var_off))
                                        continue;
                                if (verifier_bug_if((u32)regs[r].var_off.value != cval,
                                                    env, "const R%d: %u != %llu",
                                                    r, cval, regs[r].var_off.value))
                                        return -EFAULT;
                        }
                }

                /* Reduce verification complexity by stopping speculative path
                 * verification when a nospec is encountered.
                 */
                if (state->speculative && insn_aux->nospec)
                        goto process_bpf_exit;

                err = do_check_insn(env, &do_print_state);
                if (error_recoverable_with_nospec(err) && state->speculative) {
                        /* Prevent this speculative path from ever reaching the
                         * insn that would have been unsafe to execute.
                         */
                        insn_aux->nospec = true;
                        /* If it was an ADD/SUB insn, potentially remove any
                         * markings for alu sanitization.
                         */
                        insn_aux->alu_state = 0;
                        goto process_bpf_exit;
                } else if (err < 0) {
                        return err;
                } else if (err == PROCESS_BPF_EXIT) {
                        goto process_bpf_exit;
                } else if (err == INSN_IDX_UPDATED) {
                } else if (err == 0) {
                        env->insn_idx++;
                }

                if (state->speculative && insn_aux->nospec_result) {
                        /* If we are on a path that performed a jump-op, this
                         * may skip a nospec patched-in after the jump. This can
                         * currently never happen because nospec_result is only
                         * used for the write-ops
                         * `*(size*)(dst_reg+off)=src_reg|imm32` and helper
                         * calls. These must never skip the following insn
                         * (i.e., bpf_insn_successors()'s opcode_info.can_jump
                         * is false). Still, add a warning to document this in
                         * case nospec_result is used elsewhere in the future.
                         *
                         * All non-branch instructions have a single
                         * fall-through edge. For these, nospec_result should
                         * already work.
                         */
                        if (verifier_bug_if((BPF_CLASS(insn->code) == BPF_JMP ||
                                             BPF_CLASS(insn->code) == BPF_JMP32) &&
                                            BPF_OP(insn->code) != BPF_CALL, env,
                                            "speculation barrier after jump instruction may not have the desired effect"))
                                return -EFAULT;
process_bpf_exit:
                        mark_verifier_state_scratched(env);
                        err = bpf_update_branch_counts(env, env->cur_state);
                        if (err)
                                return err;
                        err = pop_stack(env, &prev_insn_idx, &env->insn_idx,
                                        pop_log);
                        if (err < 0) {
                                if (err != -ENOENT)
                                        return err;
                                break;
                        } else {
                                do_print_state = true;
                                continue;
                        }
                }
        }

        return 0;
}

static int find_btf_percpu_datasec(struct btf *btf)
{
        const struct btf_type *t;
        const char *tname;
        int i, n;

        /*
         * Both vmlinux and module each have their own ".data..percpu"
         * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF
         * types to look at only module's own BTF types.
         */
        n = btf_nr_types(btf);
        for (i = btf_named_start_id(btf, true); i < n; i++) {
                t = btf_type_by_id(btf, i);
                if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
                        continue;

                tname = btf_name_by_offset(btf, t->name_off);
                if (!strcmp(tname, ".data..percpu"))
                        return i;
        }

        return -ENOENT;
}

/*
 * Add btf to the env->used_btfs array. If needed, refcount the
 * corresponding kernel module. To simplify caller's logic
 * in case of error or if btf was added before the function
 * decreases the btf refcount.
 */
static int __add_used_btf(struct bpf_verifier_env *env, struct btf *btf)
{
        struct btf_mod_pair *btf_mod;
        int ret = 0;
        int i;

        /* check whether we recorded this BTF (and maybe module) already */
        for (i = 0; i < env->used_btf_cnt; i++)
                if (env->used_btfs[i].btf == btf)
                        goto ret_put;

        if (env->used_btf_cnt >= MAX_USED_BTFS) {
                verbose(env, "The total number of btfs per program has reached the limit of %u\n",
                        MAX_USED_BTFS);
                ret = -E2BIG;
                goto ret_put;
        }

        btf_mod = &env->used_btfs[env->used_btf_cnt];
        btf_mod->btf = btf;
        btf_mod->module = NULL;

        /* if we reference variables from kernel module, bump its refcount */
        if (btf_is_module(btf)) {
                btf_mod->module = btf_try_get_module(btf);
                if (!btf_mod->module) {
                        ret = -ENXIO;
                        goto ret_put;
                }
        }

        env->used_btf_cnt++;
        return 0;

ret_put:
        /* Either error or this BTF was already added */
        btf_put(btf);
        return ret;
}

/* replace pseudo btf_id with kernel symbol address */
static int __check_pseudo_btf_id(struct bpf_verifier_env *env,
                                 struct bpf_insn *insn,
                                 struct bpf_insn_aux_data *aux,
                                 struct btf *btf)
{
        const struct btf_var_secinfo *vsi;
        const struct btf_type *datasec;
        const struct btf_type *t;
        const char *sym_name;
        bool percpu = false;
        u32 type, id = insn->imm;
        s32 datasec_id;
        u64 addr;
        int i;

        t = btf_type_by_id(btf, id);
        if (!t) {
                verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
                return -ENOENT;
        }

        if (!btf_type_is_var(t) && !btf_type_is_func(t)) {
                verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id);
                return -EINVAL;
        }

        sym_name = btf_name_by_offset(btf, t->name_off);
        addr = kallsyms_lookup_name(sym_name);
        if (!addr) {
                verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
                        sym_name);
                return -ENOENT;
        }
        insn[0].imm = (u32)addr;
        insn[1].imm = addr >> 32;

        if (btf_type_is_func(t)) {
                aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
                aux->btf_var.mem_size = 0;
                return 0;
        }

        datasec_id = find_btf_percpu_datasec(btf);
        if (datasec_id > 0) {
                datasec = btf_type_by_id(btf, datasec_id);
                for_each_vsi(i, datasec, vsi) {
                        if (vsi->type == id) {
                                percpu = true;
                                break;
                        }
                }
        }

        type = t->type;
        t = btf_type_skip_modifiers(btf, type, NULL);
        if (percpu) {
                aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU;
                aux->btf_var.btf = btf;
                aux->btf_var.btf_id = type;
        } else if (!btf_type_is_struct(t)) {
                const struct btf_type *ret;
                const char *tname;
                u32 tsize;

                /* resolve the type size of ksym. */
                ret = btf_resolve_size(btf, t, &tsize);
                if (IS_ERR(ret)) {
                        tname = btf_name_by_offset(btf, t->name_off);
                        verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
                                tname, PTR_ERR(ret));
                        return -EINVAL;
                }
                aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
                aux->btf_var.mem_size = tsize;
        } else {
                aux->btf_var.reg_type = PTR_TO_BTF_ID;
                aux->btf_var.btf = btf;
                aux->btf_var.btf_id = type;
        }

        return 0;
}

static int check_pseudo_btf_id(struct bpf_verifier_env *env,
                               struct bpf_insn *insn,
                               struct bpf_insn_aux_data *aux)
{
        struct btf *btf;
        int btf_fd;
        int err;

        btf_fd = insn[1].imm;
        if (btf_fd) {
                btf = btf_get_by_fd(btf_fd);
                if (IS_ERR(btf)) {
                        verbose(env, "invalid module BTF object FD specified.\n");
                        return -EINVAL;
                }
        } else {
                if (!btf_vmlinux) {
                        verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
                        return -EINVAL;
                }
                btf_get(btf_vmlinux);
                btf = btf_vmlinux;
        }

        err = __check_pseudo_btf_id(env, insn, aux, btf);
        if (err) {
                btf_put(btf);
                return err;
        }

        return __add_used_btf(env, btf);
}

static bool is_tracing_prog_type(enum bpf_prog_type type)
{
        switch (type) {
        case BPF_PROG_TYPE_KPROBE:
        case BPF_PROG_TYPE_TRACEPOINT:
        case BPF_PROG_TYPE_PERF_EVENT:
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
        case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
                return true;
        default:
                return false;
        }
}

static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
{
        return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
                map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
}

static int check_map_prog_compatibility(struct bpf_verifier_env *env,
                                        struct bpf_map *map,
                                        struct bpf_prog *prog)

{
        enum bpf_prog_type prog_type = resolve_prog_type(prog);

        if (map->excl_prog_sha &&
            memcmp(map->excl_prog_sha, prog->digest, SHA256_DIGEST_SIZE)) {
                verbose(env, "program's hash doesn't match map's excl_prog_hash\n");
                return -EACCES;
        }

        if (btf_record_has_field(map->record, BPF_LIST_HEAD) ||
            btf_record_has_field(map->record, BPF_RB_ROOT)) {
                if (is_tracing_prog_type(prog_type)) {
                        verbose(env, "tracing progs cannot use bpf_{list_head,rb_root} yet\n");
                        return -EINVAL;
                }
        }

        if (btf_record_has_field(map->record, BPF_SPIN_LOCK | BPF_RES_SPIN_LOCK)) {
                if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {
                        verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n");
                        return -EINVAL;
                }

                if (is_tracing_prog_type(prog_type)) {
                        verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
                        return -EINVAL;
                }
        }

        if ((bpf_prog_is_offloaded(prog->aux) || bpf_map_is_offloaded(map)) &&
            !bpf_offload_prog_map_match(prog, map)) {
                verbose(env, "offload device mismatch between prog and map\n");
                return -EINVAL;
        }

        if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
                verbose(env, "bpf_struct_ops map cannot be used in prog\n");
                return -EINVAL;
        }

        if (prog->sleepable)
                switch (map->map_type) {
                case BPF_MAP_TYPE_HASH:
                case BPF_MAP_TYPE_LRU_HASH:
                case BPF_MAP_TYPE_ARRAY:
                case BPF_MAP_TYPE_PERCPU_HASH:
                case BPF_MAP_TYPE_PERCPU_ARRAY:
                case BPF_MAP_TYPE_LRU_PERCPU_HASH:
                case BPF_MAP_TYPE_ARRAY_OF_MAPS:
                case BPF_MAP_TYPE_HASH_OF_MAPS:
                case BPF_MAP_TYPE_RINGBUF:
                case BPF_MAP_TYPE_USER_RINGBUF:
                case BPF_MAP_TYPE_INODE_STORAGE:
                case BPF_MAP_TYPE_SK_STORAGE:
                case BPF_MAP_TYPE_TASK_STORAGE:
                case BPF_MAP_TYPE_CGRP_STORAGE:
                case BPF_MAP_TYPE_QUEUE:
                case BPF_MAP_TYPE_STACK:
                case BPF_MAP_TYPE_ARENA:
                case BPF_MAP_TYPE_INSN_ARRAY:
                case BPF_MAP_TYPE_PROG_ARRAY:
                        break;
                default:
                        verbose(env,
                                "Sleepable programs can only use array, hash, ringbuf and local storage maps\n");
                        return -EINVAL;
                }

        if (bpf_map_is_cgroup_storage(map) &&
            bpf_cgroup_storage_assign(env->prog->aux, map)) {
                verbose(env, "only one cgroup storage of each type is allowed\n");
                return -EBUSY;
        }

        if (map->map_type == BPF_MAP_TYPE_ARENA) {
                if (env->prog->aux->arena) {
                        verbose(env, "Only one arena per program\n");
                        return -EBUSY;
                }
                if (!env->allow_ptr_leaks || !env->bpf_capable) {
                        verbose(env, "CAP_BPF and CAP_PERFMON are required to use arena\n");
                        return -EPERM;
                }
                if (!env->prog->jit_requested) {
                        verbose(env, "JIT is required to use arena\n");
                        return -EOPNOTSUPP;
                }
                if (!bpf_jit_supports_arena()) {
                        verbose(env, "JIT doesn't support arena\n");
                        return -EOPNOTSUPP;
                }
                env->prog->aux->arena = (void *)map;
                if (!bpf_arena_get_user_vm_start(env->prog->aux->arena)) {
                        verbose(env, "arena's user address must be set via map_extra or mmap()\n");
                        return -EINVAL;
                }
        }

        return 0;
}

static int __add_used_map(struct bpf_verifier_env *env, struct bpf_map *map)
{
        int i, err;

        /* check whether we recorded this map already */
        for (i = 0; i < env->used_map_cnt; i++)
                if (env->used_maps[i] == map)
                        return i;

        if (env->used_map_cnt >= MAX_USED_MAPS) {
                verbose(env, "The total number of maps per program has reached the limit of %u\n",
                        MAX_USED_MAPS);
                return -E2BIG;
        }

        err = check_map_prog_compatibility(env, map, env->prog);
        if (err)
                return err;

        if (env->prog->sleepable)
                atomic64_inc(&map->sleepable_refcnt);

        /* hold the map. If the program is rejected by verifier,
         * the map will be released by release_maps() or it
         * will be used by the valid program until it's unloaded
         * and all maps are released in bpf_free_used_maps()
         */
        bpf_map_inc(map);

        env->used_maps[env->used_map_cnt++] = map;

        if (map->map_type == BPF_MAP_TYPE_INSN_ARRAY) {
                err = bpf_insn_array_init(map, env->prog);
                if (err) {
                        verbose(env, "Failed to properly initialize insn array\n");
                        return err;
                }
                env->insn_array_maps[env->insn_array_map_cnt++] = map;
        }

        return env->used_map_cnt - 1;
}

/* Add map behind fd to used maps list, if it's not already there, and return
 * its index.
 * Returns <0 on error, or >= 0 index, on success.
 */
static int add_used_map(struct bpf_verifier_env *env, int fd)
{
        struct bpf_map *map;
        CLASS(fd, f)(fd);

        map = __bpf_map_get(f);
        if (IS_ERR(map)) {
                verbose(env, "fd %d is not pointing to valid bpf_map\n", fd);
                return PTR_ERR(map);
        }

        return __add_used_map(env, map);
}

static int check_alu_fields(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        u8 class = BPF_CLASS(insn->code);
        u8 opcode = BPF_OP(insn->code);

        switch (opcode) {
        case BPF_NEG:
                if (BPF_SRC(insn->code) != BPF_K || insn->src_reg != BPF_REG_0 ||
                    insn->off != 0 || insn->imm != 0) {
                        verbose(env, "BPF_NEG uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_END:
                if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
                    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
                    (class == BPF_ALU64 && BPF_SRC(insn->code) != BPF_TO_LE)) {
                        verbose(env, "BPF_END uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_MOV:
                if (BPF_SRC(insn->code) == BPF_X) {
                        if (class == BPF_ALU) {
                                if ((insn->off != 0 && insn->off != 8 && insn->off != 16) ||
                                    insn->imm) {
                                        verbose(env, "BPF_MOV uses reserved fields\n");
                                        return -EINVAL;
                                }
                        } else if (insn->off == BPF_ADDR_SPACE_CAST) {
                                if (insn->imm != 1 && insn->imm != 1u << 16) {
                                        verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n");
                                        return -EINVAL;
                                }
                        } else if ((insn->off != 0 && insn->off != 8 &&
                                    insn->off != 16 && insn->off != 32) || insn->imm) {
                                verbose(env, "BPF_MOV uses reserved fields\n");
                                return -EINVAL;
                        }
                } else if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
                        verbose(env, "BPF_MOV uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_ADD:
        case BPF_SUB:
        case BPF_AND:
        case BPF_OR:
        case BPF_XOR:
        case BPF_LSH:
        case BPF_RSH:
        case BPF_ARSH:
        case BPF_MUL:
        case BPF_DIV:
        case BPF_MOD:
                if (BPF_SRC(insn->code) == BPF_X) {
                        if (insn->imm != 0 || (insn->off != 0 && insn->off != 1) ||
                            (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
                                verbose(env, "BPF_ALU uses reserved fields\n");
                                return -EINVAL;
                        }
                } else if (insn->src_reg != BPF_REG_0 ||
                           (insn->off != 0 && insn->off != 1) ||
                           (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
                        verbose(env, "BPF_ALU uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        default:
                verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
                return -EINVAL;
        }
}

static int check_jmp_fields(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        u8 class = BPF_CLASS(insn->code);
        u8 opcode = BPF_OP(insn->code);

        switch (opcode) {
        case BPF_CALL:
                if (BPF_SRC(insn->code) != BPF_K ||
                    (insn->src_reg != BPF_PSEUDO_KFUNC_CALL && insn->off != 0) ||
                    (insn->src_reg != BPF_REG_0 && insn->src_reg != BPF_PSEUDO_CALL &&
                     insn->src_reg != BPF_PSEUDO_KFUNC_CALL) ||
                    insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) {
                        verbose(env, "BPF_CALL uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_JA:
                if (BPF_SRC(insn->code) == BPF_X) {
                        if (insn->src_reg != BPF_REG_0 || insn->imm != 0 || insn->off != 0) {
                                verbose(env, "BPF_JA|BPF_X uses reserved fields\n");
                                return -EINVAL;
                        }
                } else if (insn->src_reg != BPF_REG_0 || insn->dst_reg != BPF_REG_0 ||
                           (class == BPF_JMP && insn->imm != 0) ||
                           (class == BPF_JMP32 && insn->off != 0)) {
                        verbose(env, "BPF_JA uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_EXIT:
                if (BPF_SRC(insn->code) != BPF_K || insn->imm != 0 ||
                    insn->src_reg != BPF_REG_0 || insn->dst_reg != BPF_REG_0 ||
                    class == BPF_JMP32) {
                        verbose(env, "BPF_EXIT uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_JCOND:
                if (insn->code != (BPF_JMP | BPF_JCOND) || insn->src_reg != BPF_MAY_GOTO ||
                    insn->dst_reg || insn->imm) {
                        verbose(env, "invalid may_goto imm %d\n", insn->imm);
                        return -EINVAL;
                }
                return 0;
        default:
                if (BPF_SRC(insn->code) == BPF_X) {
                        if (insn->imm != 0) {
                                verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
                                return -EINVAL;
                        }
                } else if (insn->src_reg != BPF_REG_0) {
                        verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        }
}

static int check_insn_fields(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
        switch (BPF_CLASS(insn->code)) {
        case BPF_ALU:
        case BPF_ALU64:
                return check_alu_fields(env, insn);
        case BPF_LDX:
                if ((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMSX) ||
                    insn->imm != 0) {
                        verbose(env, "BPF_LDX uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_STX:
                if (BPF_MODE(insn->code) == BPF_ATOMIC)
                        return 0;
                if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) {
                        verbose(env, "BPF_STX uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_ST:
                if (BPF_MODE(insn->code) != BPF_MEM || insn->src_reg != BPF_REG_0) {
                        verbose(env, "BPF_ST uses reserved fields\n");
                        return -EINVAL;
                }
                return 0;
        case BPF_JMP:
        case BPF_JMP32:
                return check_jmp_fields(env, insn);
        case BPF_LD: {
                u8 mode = BPF_MODE(insn->code);

                if (mode == BPF_ABS || mode == BPF_IND) {
                        if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
                            BPF_SIZE(insn->code) == BPF_DW ||
                            (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
                                verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
                                return -EINVAL;
                        }
                } else if (mode != BPF_IMM) {
                        verbose(env, "invalid BPF_LD mode\n");
                        return -EINVAL;
                }
                return 0;
        }
        default:
                verbose(env, "unknown insn class %d\n", BPF_CLASS(insn->code));
                return -EINVAL;
        }
}

/*
 * Check that insns are sane and rewrite pseudo imm in ld_imm64 instructions:
 *
 * 1. if it accesses map FD, replace it with actual map pointer.
 * 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
 *
 * NOTE: btf_vmlinux is required for converting pseudo btf_id.
 */
static int check_and_resolve_insns(struct bpf_verifier_env *env)
{
        struct bpf_insn *insn = env->prog->insnsi;
        int insn_cnt = env->prog->len;
        int i, err;

        err = bpf_prog_calc_tag(env->prog);
        if (err)
                return err;

        for (i = 0; i < insn_cnt; i++, insn++) {
                if (insn->dst_reg >= MAX_BPF_REG) {
                        verbose(env, "R%d is invalid\n", insn->dst_reg);
                        return -EINVAL;
                }
                if (insn->src_reg >= MAX_BPF_REG) {
                        verbose(env, "R%d is invalid\n", insn->src_reg);
                        return -EINVAL;
                }
                if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
                        struct bpf_insn_aux_data *aux;
                        struct bpf_map *map;
                        int map_idx;
                        u64 addr;
                        u32 fd;

                        if (i == insn_cnt - 1 || insn[1].code != 0 ||
                            insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
                            insn[1].off != 0) {
                                verbose(env, "invalid bpf_ld_imm64 insn\n");
                                return -EINVAL;
                        }

                        if (insn[0].off != 0) {
                                verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
                                return -EINVAL;
                        }

                        if (insn[0].src_reg == 0)
                                /* valid generic load 64-bit imm */
                                goto next_insn;

                        if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
                                aux = &env->insn_aux_data[i];
                                err = check_pseudo_btf_id(env, insn, aux);
                                if (err)
                                        return err;
                                goto next_insn;
                        }

                        if (insn[0].src_reg == BPF_PSEUDO_FUNC) {
                                aux = &env->insn_aux_data[i];
                                aux->ptr_type = PTR_TO_FUNC;
                                goto next_insn;
                        }

                        /* In final convert_pseudo_ld_imm64() step, this is
                         * converted into regular 64-bit imm load insn.
                         */
                        switch (insn[0].src_reg) {
                        case BPF_PSEUDO_MAP_VALUE:
                        case BPF_PSEUDO_MAP_IDX_VALUE:
                                break;
                        case BPF_PSEUDO_MAP_FD:
                        case BPF_PSEUDO_MAP_IDX:
                                if (insn[1].imm == 0)
                                        break;
                                fallthrough;
                        default:
                                verbose(env, "unrecognized bpf_ld_imm64 insn\n");
                                return -EINVAL;
                        }

                        switch (insn[0].src_reg) {
                        case BPF_PSEUDO_MAP_IDX_VALUE:
                        case BPF_PSEUDO_MAP_IDX:
                                if (bpfptr_is_null(env->fd_array)) {
                                        verbose(env, "fd_idx without fd_array is invalid\n");
                                        return -EPROTO;
                                }
                                if (copy_from_bpfptr_offset(&fd, env->fd_array,
                                                            insn[0].imm * sizeof(fd),
                                                            sizeof(fd)))
                                        return -EFAULT;
                                break;
                        default:
                                fd = insn[0].imm;
                                break;
                        }

                        map_idx = add_used_map(env, fd);
                        if (map_idx < 0)
                                return map_idx;
                        map = env->used_maps[map_idx];

                        aux = &env->insn_aux_data[i];
                        aux->map_index = map_idx;

                        if (insn[0].src_reg == BPF_PSEUDO_MAP_FD ||
                            insn[0].src_reg == BPF_PSEUDO_MAP_IDX) {
                                addr = (unsigned long)map;
                        } else {
                                u32 off = insn[1].imm;

                                if (!map->ops->map_direct_value_addr) {
                                        verbose(env, "no direct value access support for this map type\n");
                                        return -EINVAL;
                                }

                                err = map->ops->map_direct_value_addr(map, &addr, off);
                                if (err) {
                                        verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n",
                                                map->value_size, off);
                                        return err;
                                }

                                aux->map_off = off;
                                addr += off;
                        }

                        insn[0].imm = (u32)addr;
                        insn[1].imm = addr >> 32;

next_insn:
                        insn++;
                        i++;
                        continue;
                }

                /* Basic sanity check before we invest more work here. */
                if (!bpf_opcode_in_insntable(insn->code)) {
                        verbose(env, "unknown opcode %02x\n", insn->code);
                        return -EINVAL;
                }

                err = check_insn_fields(env, insn);
                if (err)
                        return err;
        }

        /* now all pseudo BPF_LD_IMM64 instructions load valid
         * 'struct bpf_map *' into a register instead of user map_fd.
         * These pointers will be used later by verifier to validate map access.
         */
        return 0;
}

/* drop refcnt of maps used by the rejected program */
static void release_maps(struct bpf_verifier_env *env)
{
        __bpf_free_used_maps(env->prog->aux, env->used_maps,
                             env->used_map_cnt);
}

/* drop refcnt of maps used by the rejected program */
static void release_btfs(struct bpf_verifier_env *env)
{
        __bpf_free_used_btfs(env->used_btfs, env->used_btf_cnt);
}

/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
{
        struct bpf_insn *insn = env->prog->insnsi;
        int insn_cnt = env->prog->len;
        int i;

        for (i = 0; i < insn_cnt; i++, insn++) {
                if (insn->code != (BPF_LD | BPF_IMM | BPF_DW))
                        continue;
                if (insn->src_reg == BPF_PSEUDO_FUNC)
                        continue;
                insn->src_reg = 0;
        }
}

static void release_insn_arrays(struct bpf_verifier_env *env)
{
        int i;

        for (i = 0; i < env->insn_array_map_cnt; i++)
                bpf_insn_array_release(env->insn_array_maps[i]);
}



/* The verifier does more data flow analysis than llvm and will not
 * explore branches that are dead at run time. Malicious programs can
 * have dead code too. Therefore replace all dead at-run-time code
 * with 'ja -1'.
 *
 * Just nops are not optimal, e.g. if they would sit at the end of the
 * program and through another bug we would manage to jump there, then
 * we'd execute beyond program memory otherwise. Returning exception
 * code also wouldn't work since we can have subprogs where the dead
 * code could be located.
 */
static void sanitize_dead_code(struct bpf_verifier_env *env)
{
        struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
        struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
        struct bpf_insn *insn = env->prog->insnsi;
        const int insn_cnt = env->prog->len;
        int i;

        for (i = 0; i < insn_cnt; i++) {
                if (aux_data[i].seen)
                        continue;
                memcpy(insn + i, &trap, sizeof(trap));
                aux_data[i].zext_dst = false;
        }
}



static void free_states(struct bpf_verifier_env *env)
{
        struct bpf_verifier_state_list *sl;
        struct list_head *head, *pos, *tmp;
        struct bpf_scc_info *info;
        int i, j;

        bpf_free_verifier_state(env->cur_state, true);
        env->cur_state = NULL;
        while (!pop_stack(env, NULL, NULL, false));

        list_for_each_safe(pos, tmp, &env->free_list) {
                sl = container_of(pos, struct bpf_verifier_state_list, node);
                bpf_free_verifier_state(&sl->state, false);
                kfree(sl);
        }
        INIT_LIST_HEAD(&env->free_list);

        for (i = 0; i < env->scc_cnt; ++i) {
                info = env->scc_info[i];
                if (!info)
                        continue;
                for (j = 0; j < info->num_visits; j++)
                        bpf_free_backedges(&info->visits[j]);
                kvfree(info);
                env->scc_info[i] = NULL;
        }

        if (!env->explored_states)
                return;

        for (i = 0; i < state_htab_size(env); i++) {
                head = &env->explored_states[i];

                list_for_each_safe(pos, tmp, head) {
                        sl = container_of(pos, struct bpf_verifier_state_list, node);
                        bpf_free_verifier_state(&sl->state, false);
                        kfree(sl);
                }
                INIT_LIST_HEAD(&env->explored_states[i]);
        }
}

static int do_check_common(struct bpf_verifier_env *env, int subprog)
{
        bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
        struct bpf_subprog_info *sub = subprog_info(env, subprog);
        struct bpf_prog_aux *aux = env->prog->aux;
        struct bpf_verifier_state *state;
        struct bpf_reg_state *regs;
        int ret, i;

        env->prev_linfo = NULL;
        env->pass_cnt++;

        state = kzalloc_obj(struct bpf_verifier_state, GFP_KERNEL_ACCOUNT);
        if (!state)
                return -ENOMEM;
        state->curframe = 0;
        state->speculative = false;
        state->branches = 1;
        state->in_sleepable = env->prog->sleepable;
        state->frame[0] = kzalloc_obj(struct bpf_func_state, GFP_KERNEL_ACCOUNT);
        if (!state->frame[0]) {
                kfree(state);
                return -ENOMEM;
        }
        env->cur_state = state;
        init_func_state(env, state->frame[0],
                        BPF_MAIN_FUNC /* callsite */,
                        0 /* frameno */,
                        subprog);
        state->first_insn_idx = env->subprog_info[subprog].start;
        state->last_insn_idx = -1;

        regs = state->frame[state->curframe]->regs;
        if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
                const char *sub_name = subprog_name(env, subprog);
                struct bpf_subprog_arg_info *arg;
                struct bpf_reg_state *reg;

                if (env->log.level & BPF_LOG_LEVEL)
                        verbose(env, "Validating %s() func#%d...\n", sub_name, subprog);
                ret = btf_prepare_func_args(env, subprog);
                if (ret)
                        goto out;

                if (subprog_is_exc_cb(env, subprog)) {
                        state->frame[0]->in_exception_callback_fn = true;

                        /*
                         * Global functions are scalar or void, make sure
                         * we return a scalar.
                         */
                        if (subprog_returns_void(env, subprog)) {
                                verbose(env, "exception cb cannot return void\n");
                                ret = -EINVAL;
                                goto out;
                        }

                        /* Also ensure the callback only has a single scalar argument. */
                        if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) {
                                verbose(env, "exception cb only supports single integer argument\n");
                                ret = -EINVAL;
                                goto out;
                        }
                }
                for (i = BPF_REG_1; i <= sub->arg_cnt; i++) {
                        arg = &sub->args[i - BPF_REG_1];
                        reg = &regs[i];

                        if (arg->arg_type == ARG_PTR_TO_CTX) {
                                reg->type = PTR_TO_CTX;
                                mark_reg_known_zero(env, regs, i);
                        } else if (arg->arg_type == ARG_ANYTHING) {
                                reg->type = SCALAR_VALUE;
                                mark_reg_unknown(env, regs, i);
                        } else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
                                /* assume unspecial LOCAL dynptr type */
                                __mark_dynptr_reg(reg, BPF_DYNPTR_TYPE_LOCAL, true, ++env->id_gen);
                        } else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
                                reg->type = PTR_TO_MEM;
                                reg->type |= arg->arg_type &
                                             (PTR_MAYBE_NULL | PTR_UNTRUSTED | MEM_RDONLY);
                                mark_reg_known_zero(env, regs, i);
                                reg->mem_size = arg->mem_size;
                                if (arg->arg_type & PTR_MAYBE_NULL)
                                        reg->id = ++env->id_gen;
                        } else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
                                reg->type = PTR_TO_BTF_ID;
                                if (arg->arg_type & PTR_MAYBE_NULL)
                                        reg->type |= PTR_MAYBE_NULL;
                                if (arg->arg_type & PTR_UNTRUSTED)
                                        reg->type |= PTR_UNTRUSTED;
                                if (arg->arg_type & PTR_TRUSTED)
                                        reg->type |= PTR_TRUSTED;
                                mark_reg_known_zero(env, regs, i);
                                reg->btf = bpf_get_btf_vmlinux(); /* can't fail at this point */
                                reg->btf_id = arg->btf_id;
                                reg->id = ++env->id_gen;
                        } else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
                                /* caller can pass either PTR_TO_ARENA or SCALAR */
                                mark_reg_unknown(env, regs, i);
                        } else {
                                verifier_bug(env, "unhandled arg#%d type %d",
                                             i - BPF_REG_1, arg->arg_type);
                                ret = -EFAULT;
                                goto out;
                        }
                }
        } else {
                /* if main BPF program has associated BTF info, validate that
                 * it's matching expected signature, and otherwise mark BTF
                 * info for main program as unreliable
                 */
                if (env->prog->aux->func_info_aux) {
                        ret = btf_prepare_func_args(env, 0);
                        if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX)
                                env->prog->aux->func_info_aux[0].unreliable = true;
                }

                /* 1st arg to a function */
                regs[BPF_REG_1].type = PTR_TO_CTX;
                mark_reg_known_zero(env, regs, BPF_REG_1);
        }

        /* Acquire references for struct_ops program arguments tagged with "__ref" */
        if (!subprog && env->prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
                for (i = 0; i < aux->ctx_arg_info_size; i++)
                        aux->ctx_arg_info[i].ref_obj_id = aux->ctx_arg_info[i].refcounted ?
                                                          acquire_reference(env, 0) : 0;
        }

        ret = do_check(env);
out:
        if (!ret && pop_log)
                bpf_vlog_reset(&env->log, 0);
        free_states(env);
        return ret;
}

/* Lazily verify all global functions based on their BTF, if they are called
 * from main BPF program or any of subprograms transitively.
 * BPF global subprogs called from dead code are not validated.
 * All callable global functions must pass verification.
 * Otherwise the whole program is rejected.
 * Consider:
 * int bar(int);
 * int foo(int f)
 * {
 *    return bar(f);
 * }
 * int bar(int b)
 * {
 *    ...
 * }
 * foo() will be verified first for R1=any_scalar_value. During verification it
 * will be assumed that bar() already verified successfully and call to bar()
 * from foo() will be checked for type match only. Later bar() will be verified
 * independently to check that it's safe for R1=any_scalar_value.
 */
static int do_check_subprogs(struct bpf_verifier_env *env)
{
        struct bpf_prog_aux *aux = env->prog->aux;
        struct bpf_func_info_aux *sub_aux;
        int i, ret, new_cnt;

        if (!aux->func_info)
                return 0;

        /* exception callback is presumed to be always called */
        if (env->exception_callback_subprog)
                subprog_aux(env, env->exception_callback_subprog)->called = true;

again:
        new_cnt = 0;
        for (i = 1; i < env->subprog_cnt; i++) {
                if (!bpf_subprog_is_global(env, i))
                        continue;

                sub_aux = subprog_aux(env, i);
                if (!sub_aux->called || sub_aux->verified)
                        continue;

                env->insn_idx = env->subprog_info[i].start;
                WARN_ON_ONCE(env->insn_idx == 0);
                ret = do_check_common(env, i);
                if (ret) {
                        return ret;
                } else if (env->log.level & BPF_LOG_LEVEL) {
                        verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n",
                                i, subprog_name(env, i));
                }

                /* We verified new global subprog, it might have called some
                 * more global subprogs that we haven't verified yet, so we
                 * need to do another pass over subprogs to verify those.
                 */
                sub_aux->verified = true;
                new_cnt++;
        }

        /* We can't loop forever as we verify at least one global subprog on
         * each pass.
         */
        if (new_cnt)
                goto again;

        return 0;
}

static int do_check_main(struct bpf_verifier_env *env)
{
        int ret;

        env->insn_idx = 0;
        ret = do_check_common(env, 0);
        if (!ret)
                env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
        return ret;
}


static void print_verification_stats(struct bpf_verifier_env *env)
{
        int i;

        if (env->log.level & BPF_LOG_STATS) {
                verbose(env, "verification time %lld usec\n",
                        div_u64(env->verification_time, 1000));
                verbose(env, "stack depth ");
                for (i = 0; i < env->subprog_cnt; i++) {
                        u32 depth = env->subprog_info[i].stack_depth;

                        verbose(env, "%d", depth);
                        if (i + 1 < env->subprog_cnt)
                                verbose(env, "+");
                }
                verbose(env, "\n");
        }
        verbose(env, "processed %d insns (limit %d) max_states_per_insn %d "
                "total_states %d peak_states %d mark_read %d\n",
                env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS,
                env->max_states_per_insn, env->total_states,
                env->peak_states, env->longest_mark_read_walk);
}

int bpf_prog_ctx_arg_info_init(struct bpf_prog *prog,
                               const struct bpf_ctx_arg_aux *info, u32 cnt)
{
        prog->aux->ctx_arg_info = kmemdup_array(info, cnt, sizeof(*info), GFP_KERNEL_ACCOUNT);
        prog->aux->ctx_arg_info_size = cnt;

        return prog->aux->ctx_arg_info ? 0 : -ENOMEM;
}

static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
{
        const struct btf_type *t, *func_proto;
        const struct bpf_struct_ops_desc *st_ops_desc;
        const struct bpf_struct_ops *st_ops;
        const struct btf_member *member;
        struct bpf_prog *prog = env->prog;
        bool has_refcounted_arg = false;
        u32 btf_id, member_idx, member_off;
        struct btf *btf;
        const char *mname;
        int i, err;

        if (!prog->gpl_compatible) {
                verbose(env, "struct ops programs must have a GPL compatible license\n");
                return -EINVAL;
        }

        if (!prog->aux->attach_btf_id)
                return -ENOTSUPP;

        btf = prog->aux->attach_btf;
        if (btf_is_module(btf)) {
                /* Make sure st_ops is valid through the lifetime of env */
                env->attach_btf_mod = btf_try_get_module(btf);
                if (!env->attach_btf_mod) {
                        verbose(env, "struct_ops module %s is not found\n",
                                btf_get_name(btf));
                        return -ENOTSUPP;
                }
        }

        btf_id = prog->aux->attach_btf_id;
        st_ops_desc = bpf_struct_ops_find(btf, btf_id);
        if (!st_ops_desc) {
                verbose(env, "attach_btf_id %u is not a supported struct\n",
                        btf_id);
                return -ENOTSUPP;
        }
        st_ops = st_ops_desc->st_ops;

        t = st_ops_desc->type;
        member_idx = prog->expected_attach_type;
        if (member_idx >= btf_type_vlen(t)) {
                verbose(env, "attach to invalid member idx %u of struct %s\n",
                        member_idx, st_ops->name);
                return -EINVAL;
        }

        member = &btf_type_member(t)[member_idx];
        mname = btf_name_by_offset(btf, member->name_off);
        func_proto = btf_type_resolve_func_ptr(btf, member->type,
                                               NULL);
        if (!func_proto) {
                verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n",
                        mname, member_idx, st_ops->name);
                return -EINVAL;
        }

        member_off = __btf_member_bit_offset(t, member) / 8;
        err = bpf_struct_ops_supported(st_ops, member_off);
        if (err) {
                verbose(env, "attach to unsupported member %s of struct %s\n",
                        mname, st_ops->name);
                return err;
        }

        if (st_ops->check_member) {
                err = st_ops->check_member(t, member, prog);

                if (err) {
                        verbose(env, "attach to unsupported member %s of struct %s\n",
                                mname, st_ops->name);
                        return err;
                }
        }

        if (prog->aux->priv_stack_requested && !bpf_jit_supports_private_stack()) {
                verbose(env, "Private stack not supported by jit\n");
                return -EACCES;
        }

        for (i = 0; i < st_ops_desc->arg_info[member_idx].cnt; i++) {
                if (st_ops_desc->arg_info[member_idx].info[i].refcounted) {
                        has_refcounted_arg = true;
                        break;
                }
        }

        /* Tail call is not allowed for programs with refcounted arguments since we
         * cannot guarantee that valid refcounted kptrs will be passed to the callee.
         */
        for (i = 0; i < env->subprog_cnt; i++) {
                if (has_refcounted_arg && env->subprog_info[i].has_tail_call) {
                        verbose(env, "program with __ref argument cannot tail call\n");
                        return -EINVAL;
                }
        }

        prog->aux->st_ops = st_ops;
        prog->aux->attach_st_ops_member_off = member_off;

        prog->aux->attach_func_proto = func_proto;
        prog->aux->attach_func_name = mname;
        env->ops = st_ops->verifier_ops;

        return bpf_prog_ctx_arg_info_init(prog, st_ops_desc->arg_info[member_idx].info,
                                          st_ops_desc->arg_info[member_idx].cnt);
}
#define SECURITY_PREFIX "security_"

#ifdef CONFIG_FUNCTION_ERROR_INJECTION

/* list of non-sleepable functions that are otherwise on
 * ALLOW_ERROR_INJECTION list
 */
BTF_SET_START(btf_non_sleepable_error_inject)
/* Three functions below can be called from sleepable and non-sleepable context.
 * Assume non-sleepable from bpf safety point of view.
 */
BTF_ID(func, __filemap_add_folio)
#ifdef CONFIG_FAIL_PAGE_ALLOC
BTF_ID(func, should_fail_alloc_page)
#endif
#ifdef CONFIG_FAILSLAB
BTF_ID(func, should_failslab)
#endif
BTF_SET_END(btf_non_sleepable_error_inject)

static int check_non_sleepable_error_inject(u32 btf_id)
{
        return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
}

static int check_attach_sleepable(u32 btf_id, unsigned long addr, const char *func_name)
{
        /* fentry/fexit/fmod_ret progs can be sleepable if they are
         * attached to ALLOW_ERROR_INJECTION and are not in denylist.
         */
        if (!check_non_sleepable_error_inject(btf_id) &&
            within_error_injection_list(addr))
                return 0;

        return -EINVAL;
}

static int check_attach_modify_return(unsigned long addr, const char *func_name)
{
        if (within_error_injection_list(addr) ||
            !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
                return 0;

        return -EINVAL;
}

#else

/* Unfortunately, the arch-specific prefixes are hard-coded in arch syscall code
 * so we need to hard-code them, too. Ftrace has arch_syscall_match_sym_name()
 * but that just compares two concrete function names.
 */
static bool has_arch_syscall_prefix(const char *func_name)
{
#if defined(__x86_64__)
        return !strncmp(func_name, "__x64_", 6);
#elif defined(__i386__)
        return !strncmp(func_name, "__ia32_", 7);
#elif defined(__s390x__)
        return !strncmp(func_name, "__s390x_", 8);
#elif defined(__aarch64__)
        return !strncmp(func_name, "__arm64_", 8);
#elif defined(__riscv)
        return !strncmp(func_name, "__riscv_", 8);
#elif defined(__powerpc__) || defined(__powerpc64__)
        return !strncmp(func_name, "sys_", 4);
#elif defined(__loongarch__)
        return !strncmp(func_name, "sys_", 4);
#else
        return false;
#endif
}

/* Without error injection, allow sleepable and fmod_ret progs on syscalls. */

static int check_attach_sleepable(u32 btf_id, unsigned long addr, const char *func_name)
{
        if (has_arch_syscall_prefix(func_name))
                return 0;

        return -EINVAL;
}

static int check_attach_modify_return(unsigned long addr, const char *func_name)
{
        if (has_arch_syscall_prefix(func_name) ||
            !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
                return 0;

        return -EINVAL;
}

#endif /* CONFIG_FUNCTION_ERROR_INJECTION */

int bpf_check_attach_target(struct bpf_verifier_log *log,
                            const struct bpf_prog *prog,
                            const struct bpf_prog *tgt_prog,
                            u32 btf_id,
                            struct bpf_attach_target_info *tgt_info)
{
        bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
        bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING;
        char trace_symbol[KSYM_SYMBOL_LEN];
        const char prefix[] = "btf_trace_";
        struct bpf_raw_event_map *btp;
        int ret = 0, subprog = -1, i;
        const struct btf_type *t;
        bool conservative = true;
        const char *tname, *fname;
        struct btf *btf;
        long addr = 0;
        struct module *mod = NULL;

        if (!btf_id) {
                bpf_log(log, "Tracing programs must provide btf_id\n");
                return -EINVAL;
        }
        btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf;
        if (!btf) {
                bpf_log(log,
                        "Tracing program can only be attached to another program annotated with BTF\n");
                return -EINVAL;
        }
        t = btf_type_by_id(btf, btf_id);
        if (!t) {
                bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
                return -EINVAL;
        }
        tname = btf_name_by_offset(btf, t->name_off);
        if (!tname) {
                bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
                return -EINVAL;
        }
        if (tgt_prog) {
                struct bpf_prog_aux *aux = tgt_prog->aux;
                bool tgt_changes_pkt_data;
                bool tgt_might_sleep;

                if (bpf_prog_is_dev_bound(prog->aux) &&
                    !bpf_prog_dev_bound_match(prog, tgt_prog)) {
                        bpf_log(log, "Target program bound device mismatch");
                        return -EINVAL;
                }

                for (i = 0; i < aux->func_info_cnt; i++)
                        if (aux->func_info[i].type_id == btf_id) {
                                subprog = i;
                                break;
                        }
                if (subprog == -1) {
                        bpf_log(log, "Subprog %s doesn't exist\n", tname);
                        return -EINVAL;
                }
                if (aux->func && aux->func[subprog]->aux->exception_cb) {
                        bpf_log(log,
                                "%s programs cannot attach to exception callback\n",
                                prog_extension ? "Extension" : "Tracing");
                        return -EINVAL;
                }
                conservative = aux->func_info_aux[subprog].unreliable;
                if (prog_extension) {
                        if (conservative) {
                                bpf_log(log,
                                        "Cannot replace static functions\n");
                                return -EINVAL;
                        }
                        if (!prog->jit_requested) {
                                bpf_log(log,
                                        "Extension programs should be JITed\n");
                                return -EINVAL;
                        }
                        tgt_changes_pkt_data = aux->func
                                               ? aux->func[subprog]->aux->changes_pkt_data
                                               : aux->changes_pkt_data;
                        if (prog->aux->changes_pkt_data && !tgt_changes_pkt_data) {
                                bpf_log(log,
                                        "Extension program changes packet data, while original does not\n");
                                return -EINVAL;
                        }

                        tgt_might_sleep = aux->func
                                          ? aux->func[subprog]->aux->might_sleep
                                          : aux->might_sleep;
                        if (prog->aux->might_sleep && !tgt_might_sleep) {
                                bpf_log(log,
                                        "Extension program may sleep, while original does not\n");
                                return -EINVAL;
                        }
                }
                if (!tgt_prog->jited) {
                        bpf_log(log, "Can attach to only JITed progs\n");
                        return -EINVAL;
                }
                if (prog_tracing) {
                        if (aux->attach_tracing_prog) {
                                /*
                                 * Target program is an fentry/fexit which is already attached
                                 * to another tracing program. More levels of nesting
                                 * attachment are not allowed.
                                 */
                                bpf_log(log, "Cannot nest tracing program attach more than once\n");
                                return -EINVAL;
                        }
                } else if (tgt_prog->type == prog->type) {
                        /*
                         * To avoid potential call chain cycles, prevent attaching of a
                         * program extension to another extension. It's ok to attach
                         * fentry/fexit to extension program.
                         */
                        bpf_log(log, "Cannot recursively attach\n");
                        return -EINVAL;
                }
                if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
                    prog_extension &&
                    (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
                     tgt_prog->expected_attach_type == BPF_TRACE_FEXIT ||
                     tgt_prog->expected_attach_type == BPF_TRACE_FSESSION)) {
                        /* Program extensions can extend all program types
                         * except fentry/fexit. The reason is the following.
                         * The fentry/fexit programs are used for performance
                         * analysis, stats and can be attached to any program
                         * type. When extension program is replacing XDP function
                         * it is necessary to allow performance analysis of all
                         * functions. Both original XDP program and its program
                         * extension. Hence attaching fentry/fexit to
                         * BPF_PROG_TYPE_EXT is allowed. If extending of
                         * fentry/fexit was allowed it would be possible to create
                         * long call chain fentry->extension->fentry->extension
                         * beyond reasonable stack size. Hence extending fentry
                         * is not allowed.
                         */
                        bpf_log(log, "Cannot extend fentry/fexit/fsession\n");
                        return -EINVAL;
                }
        } else {
                if (prog_extension) {
                        bpf_log(log, "Cannot replace kernel functions\n");
                        return -EINVAL;
                }
        }

        switch (prog->expected_attach_type) {
        case BPF_TRACE_RAW_TP:
                if (tgt_prog) {
                        bpf_log(log,
                                "Only FENTRY/FEXIT/FSESSION progs are attachable to another BPF prog\n");
                        return -EINVAL;
                }
                if (!btf_type_is_typedef(t)) {
                        bpf_log(log, "attach_btf_id %u is not a typedef\n",
                                btf_id);
                        return -EINVAL;
                }
                if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
                        bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
                                btf_id, tname);
                        return -EINVAL;
                }
                tname += sizeof(prefix) - 1;

                /* The func_proto of "btf_trace_##tname" is generated from typedef without argument
                 * names. Thus using bpf_raw_event_map to get argument names.
                 */
                btp = bpf_get_raw_tracepoint(tname);
                if (!btp)
                        return -EINVAL;
                fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL,
                                        trace_symbol);
                bpf_put_raw_tracepoint(btp);

                if (fname)
                        ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC);

                if (!fname || ret < 0) {
                        bpf_log(log, "Cannot find btf of tracepoint template, fall back to %s%s.\n",
                                prefix, tname);
                        t = btf_type_by_id(btf, t->type);
                        if (!btf_type_is_ptr(t))
                                /* should never happen in valid vmlinux build */
                                return -EINVAL;
                } else {
                        t = btf_type_by_id(btf, ret);
                        if (!btf_type_is_func(t))
                                /* should never happen in valid vmlinux build */
                                return -EINVAL;
                }

                t = btf_type_by_id(btf, t->type);
                if (!btf_type_is_func_proto(t))
                        /* should never happen in valid vmlinux build */
                        return -EINVAL;

                break;
        case BPF_TRACE_ITER:
                if (!btf_type_is_func(t)) {
                        bpf_log(log, "attach_btf_id %u is not a function\n",
                                btf_id);
                        return -EINVAL;
                }
                t = btf_type_by_id(btf, t->type);
                if (!btf_type_is_func_proto(t))
                        return -EINVAL;
                ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
                if (ret)
                        return ret;
                break;
        default:
                if (!prog_extension)
                        return -EINVAL;
                fallthrough;
        case BPF_MODIFY_RETURN:
        case BPF_LSM_MAC:
        case BPF_LSM_CGROUP:
        case BPF_TRACE_FENTRY:
        case BPF_TRACE_FEXIT:
        case BPF_TRACE_FSESSION:
                if (prog->expected_attach_type == BPF_TRACE_FSESSION &&
                    !bpf_jit_supports_fsession()) {
                        bpf_log(log, "JIT does not support fsession\n");
                        return -EOPNOTSUPP;
                }
                if (!btf_type_is_func(t)) {
                        bpf_log(log, "attach_btf_id %u is not a function\n",
                                btf_id);
                        return -EINVAL;
                }
                if (prog_extension &&
                    btf_check_type_match(log, prog, btf, t))
                        return -EINVAL;
                t = btf_type_by_id(btf, t->type);
                if (!btf_type_is_func_proto(t))
                        return -EINVAL;

                if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
                    (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
                     prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type))
                        return -EINVAL;

                if (tgt_prog && conservative)
                        t = NULL;

                ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
                if (ret < 0)
                        return ret;

                if (tgt_prog) {
                        if (subprog == 0)
                                addr = (long) tgt_prog->bpf_func;
                        else
                                addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
                } else {
                        if (btf_is_module(btf)) {
                                mod = btf_try_get_module(btf);
                                if (mod)
                                        addr = find_kallsyms_symbol_value(mod, tname);
                                else
                                        addr = 0;
                        } else {
                                addr = kallsyms_lookup_name(tname);
                        }
                        if (!addr) {
                                module_put(mod);
                                bpf_log(log,
                                        "The address of function %s cannot be found\n",
                                        tname);
                                return -ENOENT;
                        }
                }

                if (prog->sleepable) {
                        ret = -EINVAL;
                        switch (prog->type) {
                        case BPF_PROG_TYPE_TRACING:
                                if (!check_attach_sleepable(btf_id, addr, tname))
                                        ret = 0;
                                /* fentry/fexit/fmod_ret progs can also be sleepable if they are
                                 * in the fmodret id set with the KF_SLEEPABLE flag.
                                 */
                                else {
                                        u32 *flags = btf_kfunc_is_modify_return(btf, btf_id,
                                                                                prog);

                                        if (flags && (*flags & KF_SLEEPABLE))
                                                ret = 0;
                                }
                                break;
                        case BPF_PROG_TYPE_LSM:
                                /* LSM progs check that they are attached to bpf_lsm_*() funcs.
                                 * Only some of them are sleepable.
                                 */
                                if (bpf_lsm_is_sleepable_hook(btf_id))
                                        ret = 0;
                                break;
                        default:
                                break;
                        }
                        if (ret) {
                                module_put(mod);
                                bpf_log(log, "%s is not sleepable\n", tname);
                                return ret;
                        }
                } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
                        if (tgt_prog) {
                                module_put(mod);
                                bpf_log(log, "can't modify return codes of BPF programs\n");
                                return -EINVAL;
                        }
                        ret = -EINVAL;
                        if (btf_kfunc_is_modify_return(btf, btf_id, prog) ||
                            !check_attach_modify_return(addr, tname))
                                ret = 0;
                        if (ret) {
                                module_put(mod);
                                bpf_log(log, "%s() is not modifiable\n", tname);
                                return ret;
                        }
                }

                break;
        }
        tgt_info->tgt_addr = addr;
        tgt_info->tgt_name = tname;
        tgt_info->tgt_type = t;
        tgt_info->tgt_mod = mod;
        return 0;
}

BTF_SET_START(btf_id_deny)
BTF_ID_UNUSED
#ifdef CONFIG_SMP
BTF_ID(func, ___migrate_enable)
BTF_ID(func, migrate_disable)
BTF_ID(func, migrate_enable)
#endif
#if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU
BTF_ID(func, rcu_read_unlock_strict)
#endif
#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE)
BTF_ID(func, preempt_count_add)
BTF_ID(func, preempt_count_sub)
#endif
#ifdef CONFIG_PREEMPT_RCU
BTF_ID(func, __rcu_read_lock)
BTF_ID(func, __rcu_read_unlock)
#endif
BTF_SET_END(btf_id_deny)

/* fexit and fmod_ret can't be used to attach to __noreturn functions.
 * Currently, we must manually list all __noreturn functions here. Once a more
 * robust solution is implemented, this workaround can be removed.
 */
BTF_SET_START(noreturn_deny)
#ifdef CONFIG_IA32_EMULATION
BTF_ID(func, __ia32_sys_exit)
BTF_ID(func, __ia32_sys_exit_group)
#endif
#ifdef CONFIG_KUNIT
BTF_ID(func, __kunit_abort)
BTF_ID(func, kunit_try_catch_throw)
#endif
#ifdef CONFIG_MODULES
BTF_ID(func, __module_put_and_kthread_exit)
#endif
#ifdef CONFIG_X86_64
BTF_ID(func, __x64_sys_exit)
BTF_ID(func, __x64_sys_exit_group)
#endif
BTF_ID(func, do_exit)
BTF_ID(func, do_group_exit)
BTF_ID(func, kthread_complete_and_exit)
BTF_ID(func, make_task_dead)
BTF_SET_END(noreturn_deny)

static bool can_be_sleepable(struct bpf_prog *prog)
{
        if (prog->type == BPF_PROG_TYPE_TRACING) {
                switch (prog->expected_attach_type) {
                case BPF_TRACE_FENTRY:
                case BPF_TRACE_FEXIT:
                case BPF_MODIFY_RETURN:
                case BPF_TRACE_ITER:
                case BPF_TRACE_FSESSION:
                        return true;
                default:
                        return false;
                }
        }
        return prog->type == BPF_PROG_TYPE_LSM ||
               prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||
               prog->type == BPF_PROG_TYPE_STRUCT_OPS;
}

static int check_attach_btf_id(struct bpf_verifier_env *env)
{
        struct bpf_prog *prog = env->prog;
        struct bpf_prog *tgt_prog = prog->aux->dst_prog;
        struct bpf_attach_target_info tgt_info = {};
        u32 btf_id = prog->aux->attach_btf_id;
        struct bpf_trampoline *tr;
        int ret;
        u64 key;

        if (prog->type == BPF_PROG_TYPE_SYSCALL) {
                if (prog->sleepable)
                        /* attach_btf_id checked to be zero already */
                        return 0;
                verbose(env, "Syscall programs can only be sleepable\n");
                return -EINVAL;
        }

        if (prog->sleepable && !can_be_sleepable(prog)) {
                verbose(env, "Only fentry/fexit/fsession/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");
                return -EINVAL;
        }

        if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
                return check_struct_ops_btf_id(env);

        if (prog->type != BPF_PROG_TYPE_TRACING &&
            prog->type != BPF_PROG_TYPE_LSM &&
            prog->type != BPF_PROG_TYPE_EXT)
                return 0;

        ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
        if (ret)
                return ret;

        if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
                /* to make freplace equivalent to their targets, they need to
                 * inherit env->ops and expected_attach_type for the rest of the
                 * verification
                 */
                env->ops = bpf_verifier_ops[tgt_prog->type];
                prog->expected_attach_type = tgt_prog->expected_attach_type;
        }

        /* store info about the attachment target that will be used later */
        prog->aux->attach_func_proto = tgt_info.tgt_type;
        prog->aux->attach_func_name = tgt_info.tgt_name;
        prog->aux->mod = tgt_info.tgt_mod;

        if (tgt_prog) {
                prog->aux->saved_dst_prog_type = tgt_prog->type;
                prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
        }

        if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
                prog->aux->attach_btf_trace = true;
                return 0;
        } else if (prog->expected_attach_type == BPF_TRACE_ITER) {
                return bpf_iter_prog_supported(prog);
        }

        if (prog->type == BPF_PROG_TYPE_LSM) {
                ret = bpf_lsm_verify_prog(&env->log, prog);
                if (ret < 0)
                        return ret;
        } else if (prog->type == BPF_PROG_TYPE_TRACING &&
                   btf_id_set_contains(&btf_id_deny, btf_id)) {
                verbose(env, "Attaching tracing programs to function '%s' is rejected.\n",
                        tgt_info.tgt_name);
                return -EINVAL;
        } else if ((prog->expected_attach_type == BPF_TRACE_FEXIT ||
                   prog->expected_attach_type == BPF_TRACE_FSESSION ||
                   prog->expected_attach_type == BPF_MODIFY_RETURN) &&
                   btf_id_set_contains(&noreturn_deny, btf_id)) {
                verbose(env, "Attaching fexit/fsession/fmod_ret to __noreturn function '%s' is rejected.\n",
                        tgt_info.tgt_name);
                return -EINVAL;
        }

        key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id);
        tr = bpf_trampoline_get(key, &tgt_info);
        if (!tr)
                return -ENOMEM;

        if (tgt_prog && tgt_prog->aux->tail_call_reachable)
                tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX;

        prog->aux->dst_trampoline = tr;
        return 0;
}

struct btf *bpf_get_btf_vmlinux(void)
{
        if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
                mutex_lock(&bpf_verifier_lock);
                if (!btf_vmlinux)
                        btf_vmlinux = btf_parse_vmlinux();
                mutex_unlock(&bpf_verifier_lock);
        }
        return btf_vmlinux;
}

/*
 * The add_fd_from_fd_array() is executed only if fd_array_cnt is non-zero. In
 * this case expect that every file descriptor in the array is either a map or
 * a BTF. Everything else is considered to be trash.
 */
static int add_fd_from_fd_array(struct bpf_verifier_env *env, int fd)
{
        struct bpf_map *map;
        struct btf *btf;
        CLASS(fd, f)(fd);
        int err;

        map = __bpf_map_get(f);
        if (!IS_ERR(map)) {
                err = __add_used_map(env, map);
                if (err < 0)
                        return err;
                return 0;
        }

        btf = __btf_get_by_fd(f);
        if (!IS_ERR(btf)) {
                btf_get(btf);
                return __add_used_btf(env, btf);
        }

        verbose(env, "fd %d is not pointing to valid bpf_map or btf\n", fd);
        return PTR_ERR(map);
}

static int process_fd_array(struct bpf_verifier_env *env, union bpf_attr *attr, bpfptr_t uattr)
{
        size_t size = sizeof(int);
        int ret;
        int fd;
        u32 i;

        env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);

        /*
         * The only difference between old (no fd_array_cnt is given) and new
         * APIs is that in the latter case the fd_array is expected to be
         * continuous and is scanned for map fds right away
         */
        if (!attr->fd_array_cnt)
                return 0;

        /* Check for integer overflow */
        if (attr->fd_array_cnt >= (U32_MAX / size)) {
                verbose(env, "fd_array_cnt is too big (%u)\n", attr->fd_array_cnt);
                return -EINVAL;
        }

        for (i = 0; i < attr->fd_array_cnt; i++) {
                if (copy_from_bpfptr_offset(&fd, env->fd_array, i * size, size))
                        return -EFAULT;

                ret = add_fd_from_fd_array(env, fd);
                if (ret)
                        return ret;
        }

        return 0;
}

/* replace a generic kfunc with a specialized version if necessary */
static int specialize_kfunc(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc, int insn_idx)
{
        struct bpf_prog *prog = env->prog;
        bool seen_direct_write;
        void *xdp_kfunc;
        bool is_rdonly;
        u32 func_id = desc->func_id;
        u16 offset = desc->offset;
        unsigned long addr = desc->addr;

        if (offset) /* return if module BTF is used */
                return 0;

        if (bpf_dev_bound_kfunc_id(func_id)) {
                xdp_kfunc = bpf_dev_bound_resolve_kfunc(prog, func_id);
                if (xdp_kfunc)
                        addr = (unsigned long)xdp_kfunc;
                /* fallback to default kfunc when not supported by netdev */
        } else if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
                seen_direct_write = env->seen_direct_write;
                is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE);

                if (is_rdonly)
                        addr = (unsigned long)bpf_dynptr_from_skb_rdonly;

                /* restore env->seen_direct_write to its original value, since
                 * may_access_direct_pkt_data mutates it
                 */
                env->seen_direct_write = seen_direct_write;
        } else if (func_id == special_kfunc_list[KF_bpf_set_dentry_xattr]) {
                if (bpf_lsm_has_d_inode_locked(prog))
                        addr = (unsigned long)bpf_set_dentry_xattr_locked;
        } else if (func_id == special_kfunc_list[KF_bpf_remove_dentry_xattr]) {
                if (bpf_lsm_has_d_inode_locked(prog))
                        addr = (unsigned long)bpf_remove_dentry_xattr_locked;
        } else if (func_id == special_kfunc_list[KF_bpf_dynptr_from_file]) {
                if (!env->insn_aux_data[insn_idx].non_sleepable)
                        addr = (unsigned long)bpf_dynptr_from_file_sleepable;
        } else if (func_id == special_kfunc_list[KF_bpf_arena_alloc_pages]) {
                if (env->insn_aux_data[insn_idx].non_sleepable)
                        addr = (unsigned long)bpf_arena_alloc_pages_non_sleepable;
        } else if (func_id == special_kfunc_list[KF_bpf_arena_free_pages]) {
                if (env->insn_aux_data[insn_idx].non_sleepable)
                        addr = (unsigned long)bpf_arena_free_pages_non_sleepable;
        }
        desc->addr = addr;
        return 0;
}

static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux,
                                            u16 struct_meta_reg,
                                            u16 node_offset_reg,
                                            struct bpf_insn *insn,
                                            struct bpf_insn *insn_buf,
                                            int *cnt)
{
        struct btf_struct_meta *kptr_struct_meta = insn_aux->kptr_struct_meta;
        struct bpf_insn addr[2] = { BPF_LD_IMM64(struct_meta_reg, (long)kptr_struct_meta) };

        insn_buf[0] = addr[0];
        insn_buf[1] = addr[1];
        insn_buf[2] = BPF_MOV64_IMM(node_offset_reg, insn_aux->insert_off);
        insn_buf[3] = *insn;
        *cnt = 4;
}

int bpf_fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
                     struct bpf_insn *insn_buf, int insn_idx, int *cnt)
{
        struct bpf_kfunc_desc *desc;
        int err;

        if (!insn->imm) {
                verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
                return -EINVAL;
        }

        *cnt = 0;

        /* insn->imm has the btf func_id. Replace it with an offset relative to
         * __bpf_call_base, unless the JIT needs to call functions that are
         * further than 32 bits away (bpf_jit_supports_far_kfunc_call()).
         */
        desc = find_kfunc_desc(env->prog, insn->imm, insn->off);
        if (!desc) {
                verifier_bug(env, "kernel function descriptor not found for func_id %u",
                             insn->imm);
                return -EFAULT;
        }

        err = specialize_kfunc(env, desc, insn_idx);
        if (err)
                return err;

        if (!bpf_jit_supports_far_kfunc_call())
                insn->imm = BPF_CALL_IMM(desc->addr);

        if (is_bpf_obj_new_kfunc(desc->func_id) || is_bpf_percpu_obj_new_kfunc(desc->func_id)) {
                struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };
                u64 obj_new_size = env->insn_aux_data[insn_idx].obj_new_size;

                if (is_bpf_percpu_obj_new_kfunc(desc->func_id) && kptr_struct_meta) {
                        verifier_bug(env, "NULL kptr_struct_meta expected at insn_idx %d",
                                     insn_idx);
                        return -EFAULT;
                }

                insn_buf[0] = BPF_MOV64_IMM(BPF_REG_1, obj_new_size);
                insn_buf[1] = addr[0];
                insn_buf[2] = addr[1];
                insn_buf[3] = *insn;
                *cnt = 4;
        } else if (is_bpf_obj_drop_kfunc(desc->func_id) ||
                   is_bpf_percpu_obj_drop_kfunc(desc->func_id) ||
                   is_bpf_refcount_acquire_kfunc(desc->func_id)) {
                struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) };

                if (is_bpf_percpu_obj_drop_kfunc(desc->func_id) && kptr_struct_meta) {
                        verifier_bug(env, "NULL kptr_struct_meta expected at insn_idx %d",
                                     insn_idx);
                        return -EFAULT;
                }

                if (is_bpf_refcount_acquire_kfunc(desc->func_id) && !kptr_struct_meta) {
                        verifier_bug(env, "kptr_struct_meta expected at insn_idx %d",
                                     insn_idx);
                        return -EFAULT;
                }

                insn_buf[0] = addr[0];
                insn_buf[1] = addr[1];
                insn_buf[2] = *insn;
                *cnt = 3;
        } else if (is_bpf_list_push_kfunc(desc->func_id) ||
                   is_bpf_rbtree_add_kfunc(desc->func_id)) {
                struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta;
                int struct_meta_reg = BPF_REG_3;
                int node_offset_reg = BPF_REG_4;

                /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */
                if (is_bpf_rbtree_add_kfunc(desc->func_id)) {
                        struct_meta_reg = BPF_REG_4;
                        node_offset_reg = BPF_REG_5;
                }

                if (!kptr_struct_meta) {
                        verifier_bug(env, "kptr_struct_meta expected at insn_idx %d",
                                     insn_idx);
                        return -EFAULT;
                }

                __fixup_collection_insert_kfunc(&env->insn_aux_data[insn_idx], struct_meta_reg,
                                                node_offset_reg, insn, insn_buf, cnt);
        } else if (desc->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
                   desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
                insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
                *cnt = 1;
        } else if (desc->func_id == special_kfunc_list[KF_bpf_session_is_return] &&
                   env->prog->expected_attach_type == BPF_TRACE_FSESSION) {
                /*
                 * inline the bpf_session_is_return() for fsession:
                 *   bool bpf_session_is_return(void *ctx)
                 *   {
                 *       return (((u64 *)ctx)[-1] >> BPF_TRAMP_IS_RETURN_SHIFT) & 1;
                 *   }
                 */
                insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
                insn_buf[1] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_0, BPF_TRAMP_IS_RETURN_SHIFT);
                insn_buf[2] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 1);
                *cnt = 3;
        } else if (desc->func_id == special_kfunc_list[KF_bpf_session_cookie] &&
                   env->prog->expected_attach_type == BPF_TRACE_FSESSION) {
                /*
                 * inline bpf_session_cookie() for fsession:
                 *   __u64 *bpf_session_cookie(void *ctx)
                 *   {
                 *       u64 off = (((u64 *)ctx)[-1] >> BPF_TRAMP_COOKIE_INDEX_SHIFT) & 0xFF;
                 *       return &((u64 *)ctx)[-off];
                 *   }
                 */
                insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
                insn_buf[1] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_0, BPF_TRAMP_COOKIE_INDEX_SHIFT);
                insn_buf[2] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xFF);
                insn_buf[3] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
                insn_buf[4] = BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_1);
                insn_buf[5] = BPF_ALU64_IMM(BPF_NEG, BPF_REG_0, 0);
                *cnt = 6;
        }

        if (env->insn_aux_data[insn_idx].arg_prog) {
                u32 regno = env->insn_aux_data[insn_idx].arg_prog;
                struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(regno, (long)env->prog->aux) };
                int idx = *cnt;

                insn_buf[idx++] = ld_addrs[0];
                insn_buf[idx++] = ld_addrs[1];
                insn_buf[idx++] = *insn;
                *cnt = idx;
        }
        return 0;
}

int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size)
{
        u64 start_time = ktime_get_ns();
        struct bpf_verifier_env *env;
        int i, len, ret = -EINVAL, err;
        u32 log_true_size;
        bool is_priv;

        BTF_TYPE_EMIT(enum bpf_features);

        /* no program is valid */
        if (ARRAY_SIZE(bpf_verifier_ops) == 0)
                return -EINVAL;

        /* 'struct bpf_verifier_env' can be global, but since it's not small,
         * allocate/free it every time bpf_check() is called
         */
        env = kvzalloc_obj(struct bpf_verifier_env, GFP_KERNEL_ACCOUNT);
        if (!env)
                return -ENOMEM;

        env->bt.env = env;

        len = (*prog)->len;
        env->insn_aux_data =
                vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
        ret = -ENOMEM;
        if (!env->insn_aux_data)
                goto err_free_env;
        for (i = 0; i < len; i++)
                env->insn_aux_data[i].orig_idx = i;
        env->succ = bpf_iarray_realloc(NULL, 2);
        if (!env->succ)
                goto err_free_env;
        env->prog = *prog;
        env->ops = bpf_verifier_ops[env->prog->type];

        env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token);
        env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token);
        env->bypass_spec_v1 = bpf_bypass_spec_v1(env->prog->aux->token);
        env->bypass_spec_v4 = bpf_bypass_spec_v4(env->prog->aux->token);
        env->bpf_capable = is_priv = bpf_token_capable(env->prog->aux->token, CAP_BPF);

        bpf_get_btf_vmlinux();

        /* grab the mutex to protect few globals used by verifier */
        if (!is_priv)
                mutex_lock(&bpf_verifier_lock);

        /* user could have requested verbose verifier output
         * and supplied buffer to store the verification trace
         */
        ret = bpf_vlog_init(&env->log, attr->log_level,
                            (char __user *) (unsigned long) attr->log_buf,
                            attr->log_size);
        if (ret)
                goto err_unlock;

        ret = process_fd_array(env, attr, uattr);
        if (ret)
                goto skip_full_check;

        mark_verifier_state_clean(env);

        if (IS_ERR(btf_vmlinux)) {
                /* Either gcc or pahole or kernel are broken. */
                verbose(env, "in-kernel BTF is malformed\n");
                ret = PTR_ERR(btf_vmlinux);
                goto skip_full_check;
        }

        env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
        if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
                env->strict_alignment = true;
        if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
                env->strict_alignment = false;

        if (is_priv)
                env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
        env->test_reg_invariants = attr->prog_flags & BPF_F_TEST_REG_INVARIANTS;

        env->explored_states = kvzalloc_objs(struct list_head,
                                             state_htab_size(env),
                                             GFP_KERNEL_ACCOUNT);
        ret = -ENOMEM;
        if (!env->explored_states)
                goto skip_full_check;

        for (i = 0; i < state_htab_size(env); i++)
                INIT_LIST_HEAD(&env->explored_states[i]);
        INIT_LIST_HEAD(&env->free_list);

        ret = bpf_check_btf_info_early(env, attr, uattr);
        if (ret < 0)
                goto skip_full_check;

        ret = add_subprog_and_kfunc(env);
        if (ret < 0)
                goto skip_full_check;

        ret = check_subprogs(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_check_btf_info(env, attr, uattr);
        if (ret < 0)
                goto skip_full_check;

        ret = check_and_resolve_insns(env);
        if (ret < 0)
                goto skip_full_check;

        if (bpf_prog_is_offloaded(env->prog->aux)) {
                ret = bpf_prog_offload_verifier_prep(env->prog);
                if (ret)
                        goto skip_full_check;
        }

        ret = bpf_check_cfg(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_compute_postorder(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_stack_liveness_init(env);
        if (ret)
                goto skip_full_check;

        ret = check_attach_btf_id(env);
        if (ret)
                goto skip_full_check;

        ret = bpf_compute_const_regs(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_prune_dead_branches(env);
        if (ret < 0)
                goto skip_full_check;

        ret = sort_subprogs_topo(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_compute_scc(env);
        if (ret < 0)
                goto skip_full_check;

        ret = bpf_compute_live_registers(env);
        if (ret < 0)
                goto skip_full_check;

        ret = mark_fastcall_patterns(env);
        if (ret < 0)
                goto skip_full_check;

        ret = do_check_main(env);
        ret = ret ?: do_check_subprogs(env);

        if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux))
                ret = bpf_prog_offload_finalize(env);

skip_full_check:
        kvfree(env->explored_states);

        /* might decrease stack depth, keep it before passes that
         * allocate additional slots.
         */
        if (ret == 0)
                ret = bpf_remove_fastcall_spills_fills(env);

        if (ret == 0)
                ret = check_max_stack_depth(env);

        /* instruction rewrites happen after this point */
        if (ret == 0)
                ret = bpf_optimize_bpf_loop(env);

        if (is_priv) {
                if (ret == 0)
                        bpf_opt_hard_wire_dead_code_branches(env);
                if (ret == 0)
                        ret = bpf_opt_remove_dead_code(env);
                if (ret == 0)
                        ret = bpf_opt_remove_nops(env);
        } else {
                if (ret == 0)
                        sanitize_dead_code(env);
        }

        if (ret == 0)
                /* program is valid, convert *(u32*)(ctx + off) accesses */
                ret = bpf_convert_ctx_accesses(env);

        if (ret == 0)
                ret = bpf_do_misc_fixups(env);

        /* do 32-bit optimization after insn patching has done so those patched
         * insns could be handled correctly.
         */
        if (ret == 0 && !bpf_prog_is_offloaded(env->prog->aux)) {
                ret = bpf_opt_subreg_zext_lo32_rnd_hi32(env, attr);
                env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret
                                                                     : false;
        }

        if (ret == 0)
                ret = bpf_fixup_call_args(env);

        env->verification_time = ktime_get_ns() - start_time;
        print_verification_stats(env);
        env->prog->aux->verified_insns = env->insn_processed;

        /* preserve original error even if log finalization is successful */
        err = bpf_vlog_finalize(&env->log, &log_true_size);
        if (err)
                ret = err;

        if (uattr_size >= offsetofend(union bpf_attr, log_true_size) &&
            copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size),
                                  &log_true_size, sizeof(log_true_size))) {
                ret = -EFAULT;
                goto err_release_maps;
        }

        if (ret)
                goto err_release_maps;

        if (env->used_map_cnt) {
                /* if program passed verifier, update used_maps in bpf_prog_info */
                env->prog->aux->used_maps = kmalloc_objs(env->used_maps[0],
                                                         env->used_map_cnt,
                                                         GFP_KERNEL_ACCOUNT);

                if (!env->prog->aux->used_maps) {
                        ret = -ENOMEM;
                        goto err_release_maps;
                }

                memcpy(env->prog->aux->used_maps, env->used_maps,
                       sizeof(env->used_maps[0]) * env->used_map_cnt);
                env->prog->aux->used_map_cnt = env->used_map_cnt;
        }
        if (env->used_btf_cnt) {
                /* if program passed verifier, update used_btfs in bpf_prog_aux */
                env->prog->aux->used_btfs = kmalloc_objs(env->used_btfs[0],
                                                         env->used_btf_cnt,
                                                         GFP_KERNEL_ACCOUNT);
                if (!env->prog->aux->used_btfs) {
                        ret = -ENOMEM;
                        goto err_release_maps;
                }

                memcpy(env->prog->aux->used_btfs, env->used_btfs,
                       sizeof(env->used_btfs[0]) * env->used_btf_cnt);
                env->prog->aux->used_btf_cnt = env->used_btf_cnt;
        }
        if (env->used_map_cnt || env->used_btf_cnt) {
                /* program is valid. Convert pseudo bpf_ld_imm64 into generic
                 * bpf_ld_imm64 instructions
                 */
                convert_pseudo_ld_imm64(env);
        }

        adjust_btf_func(env);

        /* extension progs temporarily inherit the attach_type of their targets
           for verification purposes, so set it back to zero before returning
         */
        if (env->prog->type == BPF_PROG_TYPE_EXT)
                env->prog->expected_attach_type = 0;

        env->prog = __bpf_prog_select_runtime(env, env->prog, &ret);

err_release_maps:
        if (ret)
                release_insn_arrays(env);
        if (!env->prog->aux->used_maps)
                /* if we didn't copy map pointers into bpf_prog_info, release
                 * them now. Otherwise free_used_maps() will release them.
                 */
                release_maps(env);
        if (!env->prog->aux->used_btfs)
                release_btfs(env);

        *prog = env->prog;

        module_put(env->attach_btf_mod);
err_unlock:
        if (!is_priv)
                mutex_unlock(&bpf_verifier_lock);
        bpf_clear_insn_aux_data(env, 0, env->prog->len);
        vfree(env->insn_aux_data);
err_free_env:
        bpf_stack_liveness_free(env);
        kvfree(env->cfg.insn_postorder);
        kvfree(env->scc_info);
        kvfree(env->succ);
        kvfree(env->gotox_tmp_buf);
        kvfree(env);
        return ret;
}