// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_tracing_net.h"
#include "bpf_misc.h"

/* clang considers 'sum += 1' as usage but 'sum++' as non-usage.  GCC
 * is more consistent and considers both 'sum += 1' and 'sum++' as
 * non-usage.  This triggers warnings in the functions below.
 *
 * Starting with GCC 16 -Wunused-but-set-variable=2 can be used to
 * mimic clang's behavior.  */
#if !defined(__clang__) && __GNUC__ > 15
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
#endif

char _license[] SEC("license") = "GPL";

struct {
        __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
        __uint(map_flags, BPF_F_NO_PREALLOC);
        __type(key, int);
        __type(value, long);
} map_a SEC(".maps");

__u32 user_data, target_pid;
__s32 key_serial;
__u64 flags, task_storage_val, cgroup_id;

struct bpf_key *bpf_lookup_user_key(__s32 serial, __u64 flags) __ksym;
void bpf_key_put(struct bpf_key *key) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int get_cgroup_id(void *ctx)
{
        struct task_struct *task;
        struct css_set *cgroups;

        task = bpf_get_current_task_btf();
        if (task->pid != target_pid)
                return 0;

        /* simulate bpf_get_current_cgroup_id() helper */
        bpf_rcu_read_lock();
        cgroups = task->cgroups;
        if (!cgroups)
                goto unlock;
        cgroup_id = cgroups->dfl_cgrp->kn->id;
unlock:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_succ(void *ctx)
{
        struct task_struct *task, *real_parent;
        long init_val = 2;
        long *ptr;

        task = bpf_get_current_task_btf();
        if (task->pid != target_pid)
                return 0;

        bpf_rcu_read_lock();
        /* region including helper using rcu ptr real_parent */
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
                                   BPF_LOCAL_STORAGE_GET_F_CREATE);
        if (!ptr)
                goto out;
        ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
        if (!ptr)
                goto out;
        task_storage_val = *ptr;
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int no_lock(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* old style ptr_to_btf_id is not allowed in sleepable */
        task = bpf_get_current_task_btf();
        real_parent = task->real_parent;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int two_regions(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* two regions */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        bpf_rcu_read_unlock();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_1(void *ctx)
{
        struct task_struct *task, *real_parent;

        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_2(void *ctx)
{
        struct task_struct *task, *real_parent;

        bpf_rcu_read_lock();
        task = bpf_get_current_task_btf();
        bpf_rcu_read_unlock();

        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int task_acquire(void *ctx)
{
        struct task_struct *task, *real_parent, *gparent;

        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;

        /* rcu_ptr->rcu_field */
        gparent = real_parent->real_parent;
        if (!gparent)
                goto out;

        /* acquire a reference which can be used outside rcu read lock region */
        gparent = bpf_task_acquire(gparent);
        if (!gparent)
                goto out;

        (void)bpf_task_storage_get(&map_a, gparent, 0, 0);
        bpf_task_release(gparent);
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_lock(void *ctx)
{
        struct task_struct *task;

        /* missing bpf_rcu_read_lock() */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        (void)bpf_task_storage_get(&map_a, task, 0, 0);
        bpf_rcu_read_unlock();
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_unlock(void *ctx)
{
        struct task_struct *task;

        /* missing bpf_rcu_read_unlock() */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        (void)bpf_task_storage_get(&map_a, task, 0, 0);
        return 0;
}

SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_rcu_mismatch(void *ctx)
{
        struct task_struct *task, *real_parent;

        task = bpf_get_current_task_btf();
        /* non-sleepable: missing bpf_rcu_read_unlock() in one path */
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
        if (real_parent)
                bpf_rcu_read_unlock();
out:
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int inproper_sleepable_helper(void *ctx)
{
        struct task_struct *task, *real_parent;
        struct pt_regs *regs;
        __u32 value = 0;
        void *ptr;

        task = bpf_get_current_task_btf();
        /* sleepable helper in rcu read lock region */
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
        if (!regs)
                goto out;

        ptr = (void *)PT_REGS_IP(regs);
        (void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
        user_data = value;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?lsm.s/bpf")
int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size,
             bool kernel)
{
        struct bpf_key *bkey;

        /* sleepable kfunc in rcu read lock region */
        bpf_rcu_read_lock();
        bkey = bpf_lookup_user_key(key_serial, flags);
        bpf_rcu_read_unlock();
        if (!bkey)
                return -1;
        bpf_key_put(bkey);

        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int nested_rcu_region(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* nested rcu read lock regions */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int nested_rcu_region_unbalanced_1(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* nested rcu read lock regions */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        bpf_rcu_read_unlock();
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int nested_rcu_region_unbalanced_2(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* nested rcu read lock regions */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        bpf_rcu_read_lock();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        if (!real_parent)
                goto out;
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
        bpf_rcu_read_unlock();
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_trusted_non_rcuptr(void *ctx)
{
        struct task_struct *task, *group_leader;

        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        /* the pointer group_leader is explicitly marked as trusted */
        group_leader = task->real_parent->group_leader;
        (void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_untrusted_rcuptr(void *ctx)
{
        struct task_struct *task, *real_parent;

        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        bpf_rcu_read_unlock();
        /* helper use of rcu ptr outside the rcu read lock region */
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int cross_rcu_region(void *ctx)
{
        struct task_struct *task, *real_parent;

        /* rcu ptr define/use in different regions */
        task = bpf_get_current_task_btf();
        bpf_rcu_read_lock();
        real_parent = task->real_parent;
        bpf_rcu_read_unlock();
        bpf_rcu_read_lock();
        (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
        bpf_rcu_read_unlock();
        return 0;
}

__noinline
static int static_subprog(void *ctx)
{
        volatile int ret = 0;

        if (bpf_get_prandom_u32())
                return ret + 42;
        return ret + bpf_get_prandom_u32();
}

__noinline
int global_subprog(u64 a)
{
        volatile int ret = a;

        return ret + static_subprog(NULL);
}

__noinline
static int static_subprog_lock(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        if (bpf_get_prandom_u32())
                return ret + 42;
        return ret + bpf_get_prandom_u32();
}

__noinline
int global_subprog_lock(u64 a)
{
        volatile int ret = a;

        return ret + static_subprog_lock(NULL);
}

__noinline
static int static_subprog_unlock(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_unlock();
        if (bpf_get_prandom_u32())
                return ret + 42;
        return ret + bpf_get_prandom_u32();
}

__noinline
int global_subprog_unlock(u64 a)
{
        volatile int ret = a;

        return ret + static_subprog_unlock(NULL);
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        if (bpf_get_prandom_u32())
                ret += static_subprog(ctx);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        if (bpf_get_prandom_u32())
                ret += global_subprog(ret);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog_lock(void *ctx)
{
        volatile int ret = 0;

        ret += static_subprog_lock(ctx);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog_lock(void *ctx)
{
        volatile int ret = 0;

        ret += global_subprog_lock(ret);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_subprog_unlock(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        ret += static_subprog_unlock(ctx);
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_global_subprog_unlock(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        ret += global_subprog_unlock(ret);
        return 0;
}

int __noinline
global_sleepable_helper_subprog(int i)
{
        if (i)
                bpf_copy_from_user(&i, sizeof(i), NULL);
        return i;
}

int __noinline
global_sleepable_kfunc_subprog(int i)
{
        if (i)
                bpf_copy_from_user_str(&i, sizeof(i), NULL, 0);
        global_subprog(i);
        return i;
}

int __noinline
global_subprog_calling_sleepable_global(int i)
{
        if (!i)
                global_sleepable_kfunc_subprog(i);
        return i;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_sleepable_helper_global_subprog(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        ret += global_sleepable_helper_subprog(ret);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_sleepable_kfunc_global_subprog(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        ret += global_sleepable_kfunc_subprog(ret);
        bpf_rcu_read_unlock();
        return 0;
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int rcu_read_lock_sleepable_global_subprog_indirect(void *ctx)
{
        volatile int ret = 0;

        bpf_rcu_read_lock();
        ret += global_subprog_calling_sleepable_global(ret);
        bpf_rcu_read_unlock();
        return 0;
}