// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2019 Netronome Systems, Inc. */

#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/utsname.h>

#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/kernel.h>
#include <linux/version.h>

#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"

/* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release,
 * but Ubuntu provides /proc/version_signature file, as described at
 * https://ubuntu.com/kernel, with an example contents below, which we
 * can use to get a proper LINUX_VERSION_CODE.
 *
 *   Ubuntu 5.4.0-12.15-generic 5.4.8
 *
 * In the above, 5.4.8 is what kernel is actually expecting, while
 * uname() call will return 5.4.0 in info.release.
 */
static __u32 get_ubuntu_kernel_version(void)
{
        const char *ubuntu_kver_file = "/proc/version_signature";
        __u32 major, minor, patch;
        int ret;
        FILE *f;

        if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) != 0)
                return 0;

        f = fopen(ubuntu_kver_file, "re");
        if (!f)
                return 0;

        ret = fscanf(f, "%*s %*s %u.%u.%u\n", &major, &minor, &patch);
        fclose(f);
        if (ret != 3)
                return 0;

        return KERNEL_VERSION(major, minor, patch);
}

/* On Debian LINUX_VERSION_CODE doesn't correspond to info.release.
 * Instead, it is provided in info.version. An example content of
 * Debian 10 looks like the below.
 *
 *   utsname::release   4.19.0-22-amd64
 *   utsname::version   #1 SMP Debian 4.19.260-1 (2022-09-29)
 *
 * In the above, 4.19.260 is what kernel is actually expecting, while
 * uname() call will return 4.19.0 in info.release.
 */
static __u32 get_debian_kernel_version(struct utsname *info)
{
        __u32 major, minor, patch;
        char *p;

        p = strstr(info->version, "Debian ");
        if (!p) {
                /* This is not a Debian kernel. */
                return 0;
        }

        if (sscanf(p, "Debian %u.%u.%u", &major, &minor, &patch) != 3)
                return 0;

        return KERNEL_VERSION(major, minor, patch);
}

__u32 get_kernel_version(void)
{
        __u32 major, minor, patch, version;
        struct utsname info;

        /* Check if this is an Ubuntu kernel. */
        version = get_ubuntu_kernel_version();
        if (version != 0)
                return version;

        uname(&info);

        /* Check if this is a Debian kernel. */
        version = get_debian_kernel_version(&info);
        if (version != 0)
                return version;

        if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
                return 0;

        return KERNEL_VERSION(major, minor, patch);
}

static int probe_prog_load(enum bpf_prog_type prog_type,
                           const struct bpf_insn *insns, size_t insns_cnt,
                           char *log_buf, size_t log_buf_sz)
{
        LIBBPF_OPTS(bpf_prog_load_opts, opts,
                .log_buf = log_buf,
                .log_size = log_buf_sz,
                .log_level = log_buf ? 1 : 0,
        );
        int fd, err, exp_err = 0;
        const char *exp_msg = NULL;
        char buf[4096];

        switch (prog_type) {
        case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
                opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
                break;
        case BPF_PROG_TYPE_CGROUP_SOCKOPT:
                opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
                break;
        case BPF_PROG_TYPE_SK_LOOKUP:
                opts.expected_attach_type = BPF_SK_LOOKUP;
                break;
        case BPF_PROG_TYPE_KPROBE:
                opts.kern_version = get_kernel_version();
                break;
        case BPF_PROG_TYPE_LIRC_MODE2:
                opts.expected_attach_type = BPF_LIRC_MODE2;
                break;
        case BPF_PROG_TYPE_TRACING:
        case BPF_PROG_TYPE_LSM:
                opts.log_buf = buf;
                opts.log_size = sizeof(buf);
                opts.log_level = 1;
                if (prog_type == BPF_PROG_TYPE_TRACING)
                        opts.expected_attach_type = BPF_TRACE_FENTRY;
                else
                        opts.expected_attach_type = BPF_MODIFY_RETURN;
                opts.attach_btf_id = 1;

                exp_err = -EINVAL;
                exp_msg = "attach_btf_id 1 is not a function";
                break;
        case BPF_PROG_TYPE_EXT:
                opts.log_buf = buf;
                opts.log_size = sizeof(buf);
                opts.log_level = 1;
                opts.attach_btf_id = 1;

                exp_err = -EINVAL;
                exp_msg = "Cannot replace kernel functions";
                break;
        case BPF_PROG_TYPE_SYSCALL:
                opts.prog_flags = BPF_F_SLEEPABLE;
                break;
        case BPF_PROG_TYPE_STRUCT_OPS:
                exp_err = -524; /* -ENOTSUPP */
                break;
        case BPF_PROG_TYPE_UNSPEC:
        case BPF_PROG_TYPE_SOCKET_FILTER:
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
        case BPF_PROG_TYPE_TRACEPOINT:
        case BPF_PROG_TYPE_XDP:
        case BPF_PROG_TYPE_PERF_EVENT:
        case BPF_PROG_TYPE_CGROUP_SKB:
        case BPF_PROG_TYPE_CGROUP_SOCK:
        case BPF_PROG_TYPE_LWT_IN:
        case BPF_PROG_TYPE_LWT_OUT:
        case BPF_PROG_TYPE_LWT_XMIT:
        case BPF_PROG_TYPE_SOCK_OPS:
        case BPF_PROG_TYPE_SK_SKB:
        case BPF_PROG_TYPE_CGROUP_DEVICE:
        case BPF_PROG_TYPE_SK_MSG:
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
        case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
        case BPF_PROG_TYPE_LWT_SEG6LOCAL:
        case BPF_PROG_TYPE_SK_REUSEPORT:
        case BPF_PROG_TYPE_FLOW_DISSECTOR:
        case BPF_PROG_TYPE_CGROUP_SYSCTL:
                break;
        case BPF_PROG_TYPE_NETFILTER:
                opts.expected_attach_type = BPF_NETFILTER;
                break;
        default:
                return -EOPNOTSUPP;
        }

        fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
        err = -errno;
        if (fd >= 0)
                close(fd);
        if (exp_err) {
                if (fd >= 0 || err != exp_err)
                        return 0;
                if (exp_msg && !strstr(buf, exp_msg))
                        return 0;
                return 1;
        }
        return fd >= 0 ? 1 : 0;
}

int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
{
        struct bpf_insn insns[] = {
                BPF_MOV64_IMM(BPF_REG_0, 0),
                BPF_EXIT_INSN()
        };
        const size_t insn_cnt = ARRAY_SIZE(insns);
        int ret;

        if (opts)
                return libbpf_err(-EINVAL);

        ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
        return libbpf_err(ret);
}

int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
                         const char *str_sec, size_t str_len,
                         int token_fd)
{
        struct btf_header hdr = {
                .magic = BTF_MAGIC,
                .version = BTF_VERSION,
                .hdr_len = sizeof(struct btf_header),
                .type_len = types_len,
                .str_off = types_len,
                .str_len = str_len,
        };
        LIBBPF_OPTS(bpf_btf_load_opts, opts,
                .token_fd = token_fd,
                .btf_flags = token_fd ? BPF_F_TOKEN_FD : 0,
        );
        int btf_fd, btf_len;
        __u8 *raw_btf;

        btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
        raw_btf = malloc(btf_len);
        if (!raw_btf)
                return -ENOMEM;

        memcpy(raw_btf, &hdr, sizeof(hdr));
        memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
        memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);

        btf_fd = bpf_btf_load(raw_btf, btf_len, &opts);

        free(raw_btf);
        return btf_fd;
}

static int load_local_storage_btf(void)
{
        const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
        /* struct bpf_spin_lock {
         *   int val;
         * };
         * struct val {
         *   int cnt;
         *   struct bpf_spin_lock l;
         * };
         */
        __u32 types[] = {
                /* int */
                BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
                /* struct bpf_spin_lock */                      /* [2] */
                BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
                BTF_MEMBER_ENC(15, 1, 0), /* int val; */
                /* struct val */                                /* [3] */
                BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
                BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
                BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
        };

        return libbpf__load_raw_btf((char *)types, sizeof(types),
                                     strs, sizeof(strs), 0);
}

static int probe_map_create(enum bpf_map_type map_type)
{
        LIBBPF_OPTS(bpf_map_create_opts, opts);
        int key_size, value_size, max_entries;
        __u32 btf_key_type_id = 0, btf_value_type_id = 0;
        int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;

        key_size        = sizeof(__u32);
        value_size      = sizeof(__u32);
        max_entries     = 1;

        switch (map_type) {
        case BPF_MAP_TYPE_STACK_TRACE:
                value_size      = sizeof(__u64);
                break;
        case BPF_MAP_TYPE_LPM_TRIE:
                key_size        = sizeof(__u64);
                value_size      = sizeof(__u64);
                opts.map_flags  = BPF_F_NO_PREALLOC;
                break;
        case BPF_MAP_TYPE_CGROUP_STORAGE:
        case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
                key_size        = sizeof(struct bpf_cgroup_storage_key);
                value_size      = sizeof(__u64);
                max_entries     = 0;
                break;
        case BPF_MAP_TYPE_QUEUE:
        case BPF_MAP_TYPE_STACK:
                key_size        = 0;
                break;
        case BPF_MAP_TYPE_SK_STORAGE:
        case BPF_MAP_TYPE_INODE_STORAGE:
        case BPF_MAP_TYPE_TASK_STORAGE:
        case BPF_MAP_TYPE_CGRP_STORAGE:
                btf_key_type_id = 1;
                btf_value_type_id = 3;
                value_size = 8;
                max_entries = 0;
                opts.map_flags = BPF_F_NO_PREALLOC;
                btf_fd = load_local_storage_btf();
                if (btf_fd < 0)
                        return btf_fd;
                break;
        case BPF_MAP_TYPE_RINGBUF:
        case BPF_MAP_TYPE_USER_RINGBUF:
                key_size = 0;
                value_size = 0;
                max_entries = sysconf(_SC_PAGE_SIZE);
                break;
        case BPF_MAP_TYPE_STRUCT_OPS:
                /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
                opts.btf_vmlinux_value_type_id = 1;
                opts.value_type_btf_obj_fd = -1;
                exp_err = -524; /* -ENOTSUPP */
                break;
        case BPF_MAP_TYPE_BLOOM_FILTER:
                key_size = 0;
                max_entries = 1;
                break;
        case BPF_MAP_TYPE_ARENA:
                key_size        = 0;
                value_size      = 0;
                max_entries     = 1; /* one page */
                opts.map_extra  = 0; /* can mmap() at any address */
                opts.map_flags  = BPF_F_MMAPABLE;
                break;
        case BPF_MAP_TYPE_HASH:
        case BPF_MAP_TYPE_ARRAY:
        case BPF_MAP_TYPE_PROG_ARRAY:
        case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
        case BPF_MAP_TYPE_PERCPU_HASH:
        case BPF_MAP_TYPE_PERCPU_ARRAY:
        case BPF_MAP_TYPE_CGROUP_ARRAY:
        case BPF_MAP_TYPE_LRU_HASH:
        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_DEVMAP:
        case BPF_MAP_TYPE_DEVMAP_HASH:
        case BPF_MAP_TYPE_SOCKMAP:
        case BPF_MAP_TYPE_CPUMAP:
        case BPF_MAP_TYPE_XSKMAP:
        case BPF_MAP_TYPE_SOCKHASH:
        case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
                break;
        case BPF_MAP_TYPE_INSN_ARRAY:
                key_size        = sizeof(__u32);
                value_size      = sizeof(struct bpf_insn_array_value);
                break;
        case BPF_MAP_TYPE_UNSPEC:
        default:
                return -EOPNOTSUPP;
        }

        if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
            map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
                fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
                                          sizeof(__u32), sizeof(__u32), 1, NULL);
                if (fd_inner < 0)
                        goto cleanup;

                opts.inner_map_fd = fd_inner;
        }

        if (btf_fd >= 0) {
                opts.btf_fd = btf_fd;
                opts.btf_key_type_id = btf_key_type_id;
                opts.btf_value_type_id = btf_value_type_id;
        }

        fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
        err = -errno;

cleanup:
        if (fd >= 0)
                close(fd);
        if (fd_inner >= 0)
                close(fd_inner);
        if (btf_fd >= 0)
                close(btf_fd);

        if (exp_err)
                return fd < 0 && err == exp_err ? 1 : 0;
        else
                return fd >= 0 ? 1 : 0;
}

int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
{
        int ret;

        if (opts)
                return libbpf_err(-EINVAL);

        ret = probe_map_create(map_type);
        return libbpf_err(ret);
}

int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
                            const void *opts)
{
        struct bpf_insn insns[] = {
                BPF_EMIT_CALL((__u32)helper_id),
                BPF_EXIT_INSN(),
        };
        const size_t insn_cnt = ARRAY_SIZE(insns);
        char buf[4096];
        int ret;

        if (opts)
                return libbpf_err(-EINVAL);

        /* we can't successfully load all prog types to check for BPF helper
         * support, so bail out with -EOPNOTSUPP error
         */
        switch (prog_type) {
        case BPF_PROG_TYPE_TRACING:
        case BPF_PROG_TYPE_EXT:
        case BPF_PROG_TYPE_LSM:
        case BPF_PROG_TYPE_STRUCT_OPS:
                return -EOPNOTSUPP;
        default:
                break;
        }

        buf[0] = '\0';
        ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
        if (ret < 0)
                return libbpf_err(ret);

        /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
         * at all, it will emit something like "invalid func unknown#181".
         * If BPF verifier recognizes BPF helper but it's not supported for
         * given BPF program type, it will emit "unknown func bpf_sys_bpf#166"
         * or "program of this type cannot use helper bpf_sys_bpf#166".
         * In both cases, provided combination of BPF program type and BPF
         * helper is not supported by the kernel.
         * In all other cases, probe_prog_load() above will either succeed (e.g.,
         * because BPF helper happens to accept no input arguments or it
         * accepts one input argument and initial PTR_TO_CTX is fine for
         * that), or we'll get some more specific BPF verifier error about
         * some unsatisfied conditions.
         */
        if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ") ||
                         strstr(buf, "program of this type cannot use helper ")))
                return 0;
        return 1; /* assume supported */
}