// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 */
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf-cgroup.h>
#include <linux/rcupdate.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/topology.h>
#include <linux/ktime.h>
#include <linux/sched.h>
#include <linux/uidgid.h>
#include <linux/filter.h>
#include <linux/ctype.h>
#include <linux/jiffies.h>
#include <linux/pid_namespace.h>
#include <linux/proc_ns.h>
#include <linux/security.h>
#include <linux/btf_ids.h>

#include "../../lib/kstrtox.h"

/* If kernel subsystem is allowing eBPF programs to call this function,
 * inside its own verifier_ops->get_func_proto() callback it should return
 * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
 *
 * Different map implementations will rely on rcu in map methods
 * lookup/update/delete, therefore eBPF programs must run under rcu lock
 * if program is allowed to access maps, so check rcu_read_lock_held in
 * all three functions.
 */
BPF_CALL_2(bpf_map_lookup_elem, struct bpf_map *, map, void *, key)
{
        WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
        return (unsigned long) map->ops->map_lookup_elem(map, key);
}

const struct bpf_func_proto bpf_map_lookup_elem_proto = {
        .func           = bpf_map_lookup_elem,
        .gpl_only       = false,
        .pkt_access     = true,
        .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_MAP_KEY,
};

BPF_CALL_4(bpf_map_update_elem, struct bpf_map *, map, void *, key,
           void *, value, u64, flags)
{
        WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
        return map->ops->map_update_elem(map, key, value, flags);
}

const struct bpf_func_proto bpf_map_update_elem_proto = {
        .func           = bpf_map_update_elem,
        .gpl_only       = false,
        .pkt_access     = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_MAP_KEY,
        .arg3_type      = ARG_PTR_TO_MAP_VALUE,
        .arg4_type      = ARG_ANYTHING,
};

BPF_CALL_2(bpf_map_delete_elem, struct bpf_map *, map, void *, key)
{
        WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
        return map->ops->map_delete_elem(map, key);
}

const struct bpf_func_proto bpf_map_delete_elem_proto = {
        .func           = bpf_map_delete_elem,
        .gpl_only       = false,
        .pkt_access     = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_MAP_KEY,
};

BPF_CALL_3(bpf_map_push_elem, struct bpf_map *, map, void *, value, u64, flags)
{
        return map->ops->map_push_elem(map, value, flags);
}

const struct bpf_func_proto bpf_map_push_elem_proto = {
        .func           = bpf_map_push_elem,
        .gpl_only       = false,
        .pkt_access     = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_MAP_VALUE,
        .arg3_type      = ARG_ANYTHING,
};

BPF_CALL_2(bpf_map_pop_elem, struct bpf_map *, map, void *, value)
{
        return map->ops->map_pop_elem(map, value);
}

const struct bpf_func_proto bpf_map_pop_elem_proto = {
        .func           = bpf_map_pop_elem,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_UNINIT_MAP_VALUE,
};

BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value)
{
        return map->ops->map_peek_elem(map, value);
}

const struct bpf_func_proto bpf_map_peek_elem_proto = {
        .func           = bpf_map_peek_elem,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_PTR_TO_UNINIT_MAP_VALUE,
};

const struct bpf_func_proto bpf_get_prandom_u32_proto = {
        .func           = bpf_user_rnd_u32,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_get_smp_processor_id)
{
        return smp_processor_id();
}

const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
        .func           = bpf_get_smp_processor_id,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_get_numa_node_id)
{
        return numa_node_id();
}

const struct bpf_func_proto bpf_get_numa_node_id_proto = {
        .func           = bpf_get_numa_node_id,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_ktime_get_ns)
{
        /* NMI safe access to clock monotonic */
        return ktime_get_mono_fast_ns();
}

const struct bpf_func_proto bpf_ktime_get_ns_proto = {
        .func           = bpf_ktime_get_ns,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_ktime_get_boot_ns)
{
        /* NMI safe access to clock boottime */
        return ktime_get_boot_fast_ns();
}

const struct bpf_func_proto bpf_ktime_get_boot_ns_proto = {
        .func           = bpf_ktime_get_boot_ns,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_ktime_get_coarse_ns)
{
        return ktime_get_coarse_ns();
}

const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto = {
        .func           = bpf_ktime_get_coarse_ns,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_get_current_pid_tgid)
{
        struct task_struct *task = current;

        if (unlikely(!task))
                return -EINVAL;

        return (u64) task->tgid << 32 | task->pid;
}

const struct bpf_func_proto bpf_get_current_pid_tgid_proto = {
        .func           = bpf_get_current_pid_tgid,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_0(bpf_get_current_uid_gid)
{
        struct task_struct *task = current;
        kuid_t uid;
        kgid_t gid;

        if (unlikely(!task))
                return -EINVAL;

        current_uid_gid(&uid, &gid);
        return (u64) from_kgid(&init_user_ns, gid) << 32 |
                     from_kuid(&init_user_ns, uid);
}

const struct bpf_func_proto bpf_get_current_uid_gid_proto = {
        .func           = bpf_get_current_uid_gid,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
{
        struct task_struct *task = current;

        if (unlikely(!task))
                goto err_clear;

        /* Verifier guarantees that size > 0 */
        strscpy(buf, task->comm, size);
        return 0;
err_clear:
        memset(buf, 0, size);
        return -EINVAL;
}

const struct bpf_func_proto bpf_get_current_comm_proto = {
        .func           = bpf_get_current_comm,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg2_type      = ARG_CONST_SIZE,
};

#if defined(CONFIG_QUEUED_SPINLOCKS) || defined(CONFIG_BPF_ARCH_SPINLOCK)

static inline void __bpf_spin_lock(struct bpf_spin_lock *lock)
{
        arch_spinlock_t *l = (void *)lock;
        union {
                __u32 val;
                arch_spinlock_t lock;
        } u = { .lock = __ARCH_SPIN_LOCK_UNLOCKED };

        compiletime_assert(u.val == 0, "__ARCH_SPIN_LOCK_UNLOCKED not 0");
        BUILD_BUG_ON(sizeof(*l) != sizeof(__u32));
        BUILD_BUG_ON(sizeof(*lock) != sizeof(__u32));
        arch_spin_lock(l);
}

static inline void __bpf_spin_unlock(struct bpf_spin_lock *lock)
{
        arch_spinlock_t *l = (void *)lock;

        arch_spin_unlock(l);
}

#else

static inline void __bpf_spin_lock(struct bpf_spin_lock *lock)
{
        atomic_t *l = (void *)lock;

        BUILD_BUG_ON(sizeof(*l) != sizeof(*lock));
        do {
                atomic_cond_read_relaxed(l, !VAL);
        } while (atomic_xchg(l, 1));
}

static inline void __bpf_spin_unlock(struct bpf_spin_lock *lock)
{
        atomic_t *l = (void *)lock;

        atomic_set_release(l, 0);
}

#endif

static DEFINE_PER_CPU(unsigned long, irqsave_flags);

static inline void __bpf_spin_lock_irqsave(struct bpf_spin_lock *lock)
{
        unsigned long flags;

        local_irq_save(flags);
        __bpf_spin_lock(lock);
        __this_cpu_write(irqsave_flags, flags);
}

notrace BPF_CALL_1(bpf_spin_lock, struct bpf_spin_lock *, lock)
{
        __bpf_spin_lock_irqsave(lock);
        return 0;
}

const struct bpf_func_proto bpf_spin_lock_proto = {
        .func           = bpf_spin_lock,
        .gpl_only       = false,
        .ret_type       = RET_VOID,
        .arg1_type      = ARG_PTR_TO_SPIN_LOCK,
};

static inline void __bpf_spin_unlock_irqrestore(struct bpf_spin_lock *lock)
{
        unsigned long flags;

        flags = __this_cpu_read(irqsave_flags);
        __bpf_spin_unlock(lock);
        local_irq_restore(flags);
}

notrace BPF_CALL_1(bpf_spin_unlock, struct bpf_spin_lock *, lock)
{
        __bpf_spin_unlock_irqrestore(lock);
        return 0;
}

const struct bpf_func_proto bpf_spin_unlock_proto = {
        .func           = bpf_spin_unlock,
        .gpl_only       = false,
        .ret_type       = RET_VOID,
        .arg1_type      = ARG_PTR_TO_SPIN_LOCK,
};

void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
                           bool lock_src)
{
        struct bpf_spin_lock *lock;

        if (lock_src)
                lock = src + map->spin_lock_off;
        else
                lock = dst + map->spin_lock_off;
        preempt_disable();
        __bpf_spin_lock_irqsave(lock);
        copy_map_value(map, dst, src);
        __bpf_spin_unlock_irqrestore(lock);
        preempt_enable();
}

BPF_CALL_0(bpf_jiffies64)
{
        return get_jiffies_64();
}

const struct bpf_func_proto bpf_jiffies64_proto = {
        .func           = bpf_jiffies64,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
        struct cgroup *cgrp;
        u64 cgrp_id;

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        cgrp_id = cgroup_id(cgrp);
        rcu_read_unlock();

        return cgrp_id;
}

const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {
        .func           = bpf_get_current_cgroup_id,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_1(bpf_get_current_ancestor_cgroup_id, int, ancestor_level)
{
        struct cgroup *cgrp;
        struct cgroup *ancestor;
        u64 cgrp_id;

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        ancestor = cgroup_ancestor(cgrp, ancestor_level);
        cgrp_id = ancestor ? cgroup_id(ancestor) : 0;
        rcu_read_unlock();

        return cgrp_id;
}

const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto = {
        .func           = bpf_get_current_ancestor_cgroup_id,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_ANYTHING,
};

#ifdef CONFIG_CGROUP_BPF

BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
{
        /* flags argument is not used now,
         * but provides an ability to extend the API.
         * verifier checks that its value is correct.
         */
        enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
        struct bpf_cgroup_storage *storage;
        struct bpf_cg_run_ctx *ctx;
        void *ptr;

        /* get current cgroup storage from BPF run context */
        ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);
        storage = ctx->prog_item->cgroup_storage[stype];

        if (stype == BPF_CGROUP_STORAGE_SHARED)
                ptr = &READ_ONCE(storage->buf)->data[0];
        else
                ptr = this_cpu_ptr(storage->percpu_buf);

        return (unsigned long)ptr;
}

const struct bpf_func_proto bpf_get_local_storage_proto = {
        .func           = bpf_get_local_storage,
        .gpl_only       = false,
        .ret_type       = RET_PTR_TO_MAP_VALUE,
        .arg1_type      = ARG_CONST_MAP_PTR,
        .arg2_type      = ARG_ANYTHING,
};
#endif

#define BPF_STRTOX_BASE_MASK 0x1F

static int __bpf_strtoull(const char *buf, size_t buf_len, u64 flags,
                          unsigned long long *res, bool *is_negative)
{
        unsigned int base = flags & BPF_STRTOX_BASE_MASK;
        const char *cur_buf = buf;
        size_t cur_len = buf_len;
        unsigned int consumed;
        size_t val_len;
        char str[64];

        if (!buf || !buf_len || !res || !is_negative)
                return -EINVAL;

        if (base != 0 && base != 8 && base != 10 && base != 16)
                return -EINVAL;

        if (flags & ~BPF_STRTOX_BASE_MASK)
                return -EINVAL;

        while (cur_buf < buf + buf_len && isspace(*cur_buf))
                ++cur_buf;

        *is_negative = (cur_buf < buf + buf_len && *cur_buf == '-');
        if (*is_negative)
                ++cur_buf;

        consumed = cur_buf - buf;
        cur_len -= consumed;
        if (!cur_len)
                return -EINVAL;

        cur_len = min(cur_len, sizeof(str) - 1);
        memcpy(str, cur_buf, cur_len);
        str[cur_len] = '\0';
        cur_buf = str;

        cur_buf = _parse_integer_fixup_radix(cur_buf, &base);
        val_len = _parse_integer(cur_buf, base, res);

        if (val_len & KSTRTOX_OVERFLOW)
                return -ERANGE;

        if (val_len == 0)
                return -EINVAL;

        cur_buf += val_len;
        consumed += cur_buf - str;

        return consumed;
}

static int __bpf_strtoll(const char *buf, size_t buf_len, u64 flags,
                         long long *res)
{
        unsigned long long _res;
        bool is_negative;
        int err;

        err = __bpf_strtoull(buf, buf_len, flags, &_res, &is_negative);
        if (err < 0)
                return err;
        if (is_negative) {
                if ((long long)-_res > 0)
                        return -ERANGE;
                *res = -_res;
        } else {
                if ((long long)_res < 0)
                        return -ERANGE;
                *res = _res;
        }
        return err;
}

BPF_CALL_4(bpf_strtol, const char *, buf, size_t, buf_len, u64, flags,
           long *, res)
{
        long long _res;
        int err;

        err = __bpf_strtoll(buf, buf_len, flags, &_res);
        if (err < 0)
                return err;
        if (_res != (long)_res)
                return -ERANGE;
        *res = _res;
        return err;
}

const struct bpf_func_proto bpf_strtol_proto = {
        .func           = bpf_strtol,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
        .arg2_type      = ARG_CONST_SIZE,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_LONG,
};

BPF_CALL_4(bpf_strtoul, const char *, buf, size_t, buf_len, u64, flags,
           unsigned long *, res)
{
        unsigned long long _res;
        bool is_negative;
        int err;

        err = __bpf_strtoull(buf, buf_len, flags, &_res, &is_negative);
        if (err < 0)
                return err;
        if (is_negative)
                return -EINVAL;
        if (_res != (unsigned long)_res)
                return -ERANGE;
        *res = _res;
        return err;
}

const struct bpf_func_proto bpf_strtoul_proto = {
        .func           = bpf_strtoul,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
        .arg2_type      = ARG_CONST_SIZE,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_LONG,
};
#endif

BPF_CALL_3(bpf_strncmp, const char *, s1, u32, s1_sz, const char *, s2)
{
        return strncmp(s1, s2, s1_sz);
}

const struct bpf_func_proto bpf_strncmp_proto = {
        .func           = bpf_strncmp,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_MEM,
        .arg2_type      = ARG_CONST_SIZE,
        .arg3_type      = ARG_PTR_TO_CONST_STR,
};

BPF_CALL_4(bpf_get_ns_current_pid_tgid, u64, dev, u64, ino,
           struct bpf_pidns_info *, nsdata, u32, size)
{
        struct task_struct *task = current;
        struct pid_namespace *pidns;
        int err = -EINVAL;

        if (unlikely(size != sizeof(struct bpf_pidns_info)))
                goto clear;

        if (unlikely((u64)(dev_t)dev != dev))
                goto clear;

        if (unlikely(!task))
                goto clear;

        pidns = task_active_pid_ns(task);
        if (unlikely(!pidns)) {
                err = -ENOENT;
                goto clear;
        }

        if (!ns_match(&pidns->ns, (dev_t)dev, ino))
                goto clear;

        nsdata->pid = task_pid_nr_ns(task, pidns);
        nsdata->tgid = task_tgid_nr_ns(task, pidns);
        return 0;
clear:
        memset((void *)nsdata, 0, (size_t) size);
        return err;
}

const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto = {
        .func           = bpf_get_ns_current_pid_tgid,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_ANYTHING,
        .arg2_type      = ARG_ANYTHING,
        .arg3_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg4_type      = ARG_CONST_SIZE,
};

static const struct bpf_func_proto bpf_get_raw_smp_processor_id_proto = {
        .func           = bpf_get_raw_cpu_id,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
};

BPF_CALL_5(bpf_event_output_data, void *, ctx, struct bpf_map *, map,
           u64, flags, void *, data, u64, size)
{
        if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
                return -EINVAL;

        return bpf_event_output(map, flags, data, size, NULL, 0, NULL);
}

const struct bpf_func_proto bpf_event_output_data_proto =  {
        .func           = bpf_event_output_data,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
        .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
};

BPF_CALL_3(bpf_copy_from_user, void *, dst, u32, size,
           const void __user *, user_ptr)
{
        int ret = copy_from_user(dst, user_ptr, size);

        if (unlikely(ret)) {
                memset(dst, 0, size);
                ret = -EFAULT;
        }

        return ret;
}

const struct bpf_func_proto bpf_copy_from_user_proto = {
        .func           = bpf_copy_from_user,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
        .arg3_type      = ARG_ANYTHING,
};

BPF_CALL_5(bpf_copy_from_user_task, void *, dst, u32, size,
           const void __user *, user_ptr, struct task_struct *, tsk, u64, flags)
{
        int ret;

        /* flags is not used yet */
        if (unlikely(flags))
                return -EINVAL;

        if (unlikely(!size))
                return 0;

        ret = access_process_vm(tsk, (unsigned long)user_ptr, dst, size, 0);
        if (ret == size)
                return 0;

        memset(dst, 0, size);
        /* Return -EFAULT for partial read */
        return ret < 0 ? ret : -EFAULT;
}

const struct bpf_func_proto bpf_copy_from_user_task_proto = {
        .func           = bpf_copy_from_user_task,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_PTR_TO_BTF_ID,
        .arg4_btf_id    = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
        .arg5_type      = ARG_ANYTHING
};

BPF_CALL_2(bpf_per_cpu_ptr, const void *, ptr, u32, cpu)
{
        if (cpu >= nr_cpu_ids)
                return (unsigned long)NULL;

        return (unsigned long)per_cpu_ptr((const void __percpu *)ptr, cpu);
}

const struct bpf_func_proto bpf_per_cpu_ptr_proto = {
        .func           = bpf_per_cpu_ptr,
        .gpl_only       = false,
        .ret_type       = RET_PTR_TO_MEM_OR_BTF_ID | PTR_MAYBE_NULL | MEM_RDONLY,
        .arg1_type      = ARG_PTR_TO_PERCPU_BTF_ID,
        .arg2_type      = ARG_ANYTHING,
};

BPF_CALL_1(bpf_this_cpu_ptr, const void *, percpu_ptr)
{
        return (unsigned long)this_cpu_ptr((const void __percpu *)percpu_ptr);
}

const struct bpf_func_proto bpf_this_cpu_ptr_proto = {
        .func           = bpf_this_cpu_ptr,
        .gpl_only       = false,
        .ret_type       = RET_PTR_TO_MEM_OR_BTF_ID | MEM_RDONLY,
        .arg1_type      = ARG_PTR_TO_PERCPU_BTF_ID,
};

static int bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
                size_t bufsz)
{
        void __user *user_ptr = (__force void __user *)unsafe_ptr;

        buf[0] = 0;

        switch (fmt_ptype) {
        case 's':
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
                if ((unsigned long)unsafe_ptr < TASK_SIZE)
                        return strncpy_from_user_nofault(buf, user_ptr, bufsz);
                fallthrough;
#endif
        case 'k':
                return strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
        case 'u':
                return strncpy_from_user_nofault(buf, user_ptr, bufsz);
        }

        return -EINVAL;
}

/* Per-cpu temp buffers used by printf-like helpers to store the bprintf binary
 * arguments representation.
 */
#define MAX_BPRINTF_BUF_LEN     512

/* Support executing three nested bprintf helper calls on a given CPU */
#define MAX_BPRINTF_NEST_LEVEL  3
struct bpf_bprintf_buffers {
        char tmp_bufs[MAX_BPRINTF_NEST_LEVEL][MAX_BPRINTF_BUF_LEN];
};
static DEFINE_PER_CPU(struct bpf_bprintf_buffers, bpf_bprintf_bufs);
static DEFINE_PER_CPU(int, bpf_bprintf_nest_level);

static int try_get_fmt_tmp_buf(char **tmp_buf)
{
        struct bpf_bprintf_buffers *bufs;
        int nest_level;

        preempt_disable();
        nest_level = this_cpu_inc_return(bpf_bprintf_nest_level);
        if (WARN_ON_ONCE(nest_level > MAX_BPRINTF_NEST_LEVEL)) {
                this_cpu_dec(bpf_bprintf_nest_level);
                preempt_enable();
                return -EBUSY;
        }
        bufs = this_cpu_ptr(&bpf_bprintf_bufs);
        *tmp_buf = bufs->tmp_bufs[nest_level - 1];

        return 0;
}

void bpf_bprintf_cleanup(void)
{
        if (this_cpu_read(bpf_bprintf_nest_level)) {
                this_cpu_dec(bpf_bprintf_nest_level);
                preempt_enable();
        }
}

/*
 * bpf_bprintf_prepare - Generic pass on format strings for bprintf-like helpers
 *
 * Returns a negative value if fmt is an invalid format string or 0 otherwise.
 *
 * This can be used in two ways:
 * - Format string verification only: when bin_args is NULL
 * - Arguments preparation: in addition to the above verification, it writes in
 *   bin_args a binary representation of arguments usable by bstr_printf where
 *   pointers from BPF have been sanitized.
 *
 * In argument preparation mode, if 0 is returned, safe temporary buffers are
 * allocated and bpf_bprintf_cleanup should be called to free them after use.
 */
int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
                        u32 **bin_args, u32 num_args)
{
        char *unsafe_ptr = NULL, *tmp_buf = NULL, *tmp_buf_end, *fmt_end;
        size_t sizeof_cur_arg, sizeof_cur_ip;
        int err, i, num_spec = 0;
        u64 cur_arg;
        char fmt_ptype, cur_ip[16], ip_spec[] = "%pXX";

        fmt_end = strnchr(fmt, fmt_size, 0);
        if (!fmt_end)
                return -EINVAL;
        fmt_size = fmt_end - fmt;

        if (bin_args) {
                if (num_args && try_get_fmt_tmp_buf(&tmp_buf))
                        return -EBUSY;

                tmp_buf_end = tmp_buf + MAX_BPRINTF_BUF_LEN;
                *bin_args = (u32 *)tmp_buf;
        }

        for (i = 0; i < fmt_size; i++) {
                if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) {
                        err = -EINVAL;
                        goto out;
                }

                if (fmt[i] != '%')
                        continue;

                if (fmt[i + 1] == '%') {
                        i++;
                        continue;
                }

                if (num_spec >= num_args) {
                        err = -EINVAL;
                        goto out;
                }

                /* The string is zero-terminated so if fmt[i] != 0, we can
                 * always access fmt[i + 1], in the worst case it will be a 0
                 */
                i++;

                /* skip optional "[0 +-][num]" width formatting field */
                while (fmt[i] == '0' || fmt[i] == '+'  || fmt[i] == '-' ||
                       fmt[i] == ' ')
                        i++;
                if (fmt[i] >= '1' && fmt[i] <= '9') {
                        i++;
                        while (fmt[i] >= '0' && fmt[i] <= '9')
                                i++;
                }

                if (fmt[i] == 'p') {
                        sizeof_cur_arg = sizeof(long);

                        if ((fmt[i + 1] == 'k' || fmt[i + 1] == 'u') &&
                            fmt[i + 2] == 's') {
                                fmt_ptype = fmt[i + 1];
                                i += 2;
                                goto fmt_str;
                        }

                        if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) ||
                            ispunct(fmt[i + 1]) || fmt[i + 1] == 'K' ||
                            fmt[i + 1] == 'x' || fmt[i + 1] == 's' ||
                            fmt[i + 1] == 'S') {
                                /* just kernel pointers */
                                if (tmp_buf)
                                        cur_arg = raw_args[num_spec];
                                i++;
                                goto nocopy_fmt;
                        }

                        if (fmt[i + 1] == 'B') {
                                if (tmp_buf)  {
                                        err = snprintf(tmp_buf,
                                                       (tmp_buf_end - tmp_buf),
                                                       "%pB",
                                                       (void *)(long)raw_args[num_spec]);
                                        tmp_buf += (err + 1);
                                }

                                i++;
                                num_spec++;
                                continue;
                        }

                        /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */
                        if ((fmt[i + 1] != 'i' && fmt[i + 1] != 'I') ||
                            (fmt[i + 2] != '4' && fmt[i + 2] != '6')) {
                                err = -EINVAL;
                                goto out;
                        }

                        i += 2;
                        if (!tmp_buf)
                                goto nocopy_fmt;

                        sizeof_cur_ip = (fmt[i] == '4') ? 4 : 16;
                        if (tmp_buf_end - tmp_buf < sizeof_cur_ip) {
                                err = -ENOSPC;
                                goto out;
                        }

                        unsafe_ptr = (char *)(long)raw_args[num_spec];
                        err = copy_from_kernel_nofault(cur_ip, unsafe_ptr,
                                                       sizeof_cur_ip);
                        if (err < 0)
                                memset(cur_ip, 0, sizeof_cur_ip);

                        /* hack: bstr_printf expects IP addresses to be
                         * pre-formatted as strings, ironically, the easiest way
                         * to do that is to call snprintf.
                         */
                        ip_spec[2] = fmt[i - 1];
                        ip_spec[3] = fmt[i];
                        err = snprintf(tmp_buf, tmp_buf_end - tmp_buf,
                                       ip_spec, &cur_ip);

                        tmp_buf += err + 1;
                        num_spec++;

                        continue;
                } else if (fmt[i] == 's') {
                        fmt_ptype = fmt[i];
fmt_str:
                        if (fmt[i + 1] != 0 &&
                            !isspace(fmt[i + 1]) &&
                            !ispunct(fmt[i + 1])) {
                                err = -EINVAL;
                                goto out;
                        }

                        if (!tmp_buf)
                                goto nocopy_fmt;

                        if (tmp_buf_end == tmp_buf) {
                                err = -ENOSPC;
                                goto out;
                        }

                        unsafe_ptr = (char *)(long)raw_args[num_spec];
                        err = bpf_trace_copy_string(tmp_buf, unsafe_ptr,
                                                    fmt_ptype,
                                                    tmp_buf_end - tmp_buf);
                        if (err < 0) {
                                tmp_buf[0] = '\0';
                                err = 1;
                        }

                        tmp_buf += err;
                        num_spec++;

                        continue;
                } else if (fmt[i] == 'c') {
                        if (!tmp_buf)
                                goto nocopy_fmt;

                        if (tmp_buf_end == tmp_buf) {
                                err = -ENOSPC;
                                goto out;
                        }

                        *tmp_buf = raw_args[num_spec];
                        tmp_buf++;
                        num_spec++;

                        continue;
                }

                sizeof_cur_arg = sizeof(int);

                if (fmt[i] == 'l') {
                        sizeof_cur_arg = sizeof(long);
                        i++;
                }
                if (fmt[i] == 'l') {
                        sizeof_cur_arg = sizeof(long long);
                        i++;
                }

                if (fmt[i] != 'i' && fmt[i] != 'd' && fmt[i] != 'u' &&
                    fmt[i] != 'x' && fmt[i] != 'X') {
                        err = -EINVAL;
                        goto out;
                }

                if (tmp_buf)
                        cur_arg = raw_args[num_spec];

nocopy_fmt:
                if (tmp_buf) {
                        tmp_buf = PTR_ALIGN(tmp_buf, sizeof(u32));
                        if (tmp_buf_end - tmp_buf < sizeof_cur_arg) {
                                err = -ENOSPC;
                                goto out;
                        }

                        if (sizeof_cur_arg == 8) {
                                *(u32 *)tmp_buf = *(u32 *)&cur_arg;
                                *(u32 *)(tmp_buf + 4) = *((u32 *)&cur_arg + 1);
                        } else {
                                *(u32 *)tmp_buf = (u32)(long)cur_arg;
                        }
                        tmp_buf += sizeof_cur_arg;
                }
                num_spec++;
        }

        err = 0;
out:
        if (err)
                bpf_bprintf_cleanup();
        return err;
}

BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt,
           const void *, data, u32, data_len)
{
        int err, num_args;
        u32 *bin_args;

        if (data_len % 8 || data_len > MAX_BPRINTF_VARARGS * 8 ||
            (data_len && !data))
                return -EINVAL;
        num_args = data_len / 8;

        /* ARG_PTR_TO_CONST_STR guarantees that fmt is zero-terminated so we
         * can safely give an unbounded size.
         */
        err = bpf_bprintf_prepare(fmt, UINT_MAX, data, &bin_args, num_args);
        if (err < 0)
                return err;

        err = bstr_printf(str, str_size, fmt, bin_args);

        bpf_bprintf_cleanup();

        return err + 1;
}

const struct bpf_func_proto bpf_snprintf_proto = {
        .func           = bpf_snprintf,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_MEM_OR_NULL,
        .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
        .arg3_type      = ARG_PTR_TO_CONST_STR,
        .arg4_type      = ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
        .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
};

/* BPF map elements can contain 'struct bpf_timer'.
 * Such map owns all of its BPF timers.
 * 'struct bpf_timer' is allocated as part of map element allocation
 * and it's zero initialized.
 * That space is used to keep 'struct bpf_timer_kern'.
 * bpf_timer_init() allocates 'struct bpf_hrtimer', inits hrtimer, and
 * remembers 'struct bpf_map *' pointer it's part of.
 * bpf_timer_set_callback() increments prog refcnt and assign bpf callback_fn.
 * bpf_timer_start() arms the timer.
 * If user space reference to a map goes to zero at this point
 * ops->map_release_uref callback is responsible for cancelling the timers,
 * freeing their memory, and decrementing prog's refcnts.
 * bpf_timer_cancel() cancels the timer and decrements prog's refcnt.
 * Inner maps can contain bpf timers as well. ops->map_release_uref is
 * freeing the timers when inner map is replaced or deleted by user space.
 */
struct bpf_hrtimer {
        struct hrtimer timer;
        struct bpf_map *map;
        struct bpf_prog *prog;
        void __rcu *callback_fn;
        void *value;
};

/* the actual struct hidden inside uapi struct bpf_timer */
struct bpf_timer_kern {
        struct bpf_hrtimer *timer;
        /* bpf_spin_lock is used here instead of spinlock_t to make
         * sure that it always fits into space reserved by struct bpf_timer
         * regardless of LOCKDEP and spinlock debug flags.
         */
        struct bpf_spin_lock lock;
} __attribute__((aligned(8)));

static DEFINE_PER_CPU(struct bpf_hrtimer *, hrtimer_running);

static enum hrtimer_restart bpf_timer_cb(struct hrtimer *hrtimer)
{
        struct bpf_hrtimer *t = container_of(hrtimer, struct bpf_hrtimer, timer);
        struct bpf_map *map = t->map;
        void *value = t->value;
        bpf_callback_t callback_fn;
        void *key;
        u32 idx;

        BTF_TYPE_EMIT(struct bpf_timer);
        callback_fn = rcu_dereference_check(t->callback_fn, rcu_read_lock_bh_held());
        if (!callback_fn)
                goto out;

        /* bpf_timer_cb() runs in hrtimer_run_softirq. It doesn't migrate and
         * cannot be preempted by another bpf_timer_cb() on the same cpu.
         * Remember the timer this callback is servicing to prevent
         * deadlock if callback_fn() calls bpf_timer_cancel() or
         * bpf_map_delete_elem() on the same timer.
         */
        this_cpu_write(hrtimer_running, t);
        if (map->map_type == BPF_MAP_TYPE_ARRAY) {
                struct bpf_array *array = container_of(map, struct bpf_array, map);

                /* compute the key */
                idx = ((char *)value - array->value) / array->elem_size;
                key = &idx;
        } else { /* hash or lru */
                key = value - round_up(map->key_size, 8);
        }

        callback_fn((u64)(long)map, (u64)(long)key, (u64)(long)value, 0, 0);
        /* The verifier checked that return value is zero. */

        this_cpu_write(hrtimer_running, NULL);
out:
        return HRTIMER_NORESTART;
}

BPF_CALL_3(bpf_timer_init, struct bpf_timer_kern *, timer, struct bpf_map *, map,
           u64, flags)
{
        clockid_t clockid = flags & (MAX_CLOCKS - 1);
        struct bpf_hrtimer *t;
        int ret = 0;

        BUILD_BUG_ON(MAX_CLOCKS != 16);
        BUILD_BUG_ON(sizeof(struct bpf_timer_kern) > sizeof(struct bpf_timer));
        BUILD_BUG_ON(__alignof__(struct bpf_timer_kern) != __alignof__(struct bpf_timer));

        if (in_nmi())
                return -EOPNOTSUPP;

        if (flags >= MAX_CLOCKS ||
            /* similar to timerfd except _ALARM variants are not supported */
            (clockid != CLOCK_MONOTONIC &&
             clockid != CLOCK_REALTIME &&
             clockid != CLOCK_BOOTTIME))
                return -EINVAL;
        __bpf_spin_lock_irqsave(&timer->lock);
        t = timer->timer;
        if (t) {
                ret = -EBUSY;
                goto out;
        }
        if (!atomic64_read(&map->usercnt)) {
                /* maps with timers must be either held by user space
                 * or pinned in bpffs.
                 */
                ret = -EPERM;
                goto out;
        }
        /* allocate hrtimer via map_kmalloc to use memcg accounting */
        t = bpf_map_kmalloc_node(map, sizeof(*t), GFP_ATOMIC, map->numa_node);
        if (!t) {
                ret = -ENOMEM;
                goto out;
        }
        t->value = (void *)timer - map->timer_off;
        t->map = map;
        t->prog = NULL;
        rcu_assign_pointer(t->callback_fn, NULL);
        hrtimer_init(&t->timer, clockid, HRTIMER_MODE_REL_SOFT);
        t->timer.function = bpf_timer_cb;
        timer->timer = t;
out:
        __bpf_spin_unlock_irqrestore(&timer->lock);
        return ret;
}

static const struct bpf_func_proto bpf_timer_init_proto = {
        .func           = bpf_timer_init,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_TIMER,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
};

BPF_CALL_3(bpf_timer_set_callback, struct bpf_timer_kern *, timer, void *, callback_fn,
           struct bpf_prog_aux *, aux)
{
        struct bpf_prog *prev, *prog = aux->prog;
        struct bpf_hrtimer *t;
        int ret = 0;

        if (in_nmi())
                return -EOPNOTSUPP;
        __bpf_spin_lock_irqsave(&timer->lock);
        t = timer->timer;
        if (!t) {
                ret = -EINVAL;
                goto out;
        }
        if (!atomic64_read(&t->map->usercnt)) {
                /* maps with timers must be either held by user space
                 * or pinned in bpffs. Otherwise timer might still be
                 * running even when bpf prog is detached and user space
                 * is gone, since map_release_uref won't ever be called.
                 */
                ret = -EPERM;
                goto out;
        }
        prev = t->prog;
        if (prev != prog) {
                /* Bump prog refcnt once. Every bpf_timer_set_callback()
                 * can pick different callback_fn-s within the same prog.
                 */
                prog = bpf_prog_inc_not_zero(prog);
                if (IS_ERR(prog)) {
                        ret = PTR_ERR(prog);
                        goto out;
                }
                if (prev)
                        /* Drop prev prog refcnt when swapping with new prog */
                        bpf_prog_put(prev);
                t->prog = prog;
        }
        rcu_assign_pointer(t->callback_fn, callback_fn);
out:
        __bpf_spin_unlock_irqrestore(&timer->lock);
        return ret;
}

static const struct bpf_func_proto bpf_timer_set_callback_proto = {
        .func           = bpf_timer_set_callback,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_TIMER,
        .arg2_type      = ARG_PTR_TO_FUNC,
};

BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, flags)
{
        struct bpf_hrtimer *t;
        int ret = 0;

        if (in_nmi())
                return -EOPNOTSUPP;
        if (flags)
                return -EINVAL;
        __bpf_spin_lock_irqsave(&timer->lock);
        t = timer->timer;
        if (!t || !t->prog) {
                ret = -EINVAL;
                goto out;
        }
        hrtimer_start(&t->timer, ns_to_ktime(nsecs), HRTIMER_MODE_REL_SOFT);
out:
        __bpf_spin_unlock_irqrestore(&timer->lock);
        return ret;
}

static const struct bpf_func_proto bpf_timer_start_proto = {
        .func           = bpf_timer_start,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_TIMER,
        .arg2_type      = ARG_ANYTHING,
        .arg3_type      = ARG_ANYTHING,
};

static void drop_prog_refcnt(struct bpf_hrtimer *t)
{
        struct bpf_prog *prog = t->prog;

        if (prog) {
                bpf_prog_put(prog);
                t->prog = NULL;
                rcu_assign_pointer(t->callback_fn, NULL);
        }
}

BPF_CALL_1(bpf_timer_cancel, struct bpf_timer_kern *, timer)
{
        struct bpf_hrtimer *t;
        int ret = 0;

        if (in_nmi())
                return -EOPNOTSUPP;
        __bpf_spin_lock_irqsave(&timer->lock);
        t = timer->timer;
        if (!t) {
                ret = -EINVAL;
                goto out;
        }
        if (this_cpu_read(hrtimer_running) == t) {
                /* If bpf callback_fn is trying to bpf_timer_cancel()
                 * its own timer the hrtimer_cancel() will deadlock
                 * since it waits for callback_fn to finish
                 */
                ret = -EDEADLK;
                goto out;
        }
        drop_prog_refcnt(t);
out:
        __bpf_spin_unlock_irqrestore(&timer->lock);
        /* Cancel the timer and wait for associated callback to finish
         * if it was running.
         */
        ret = ret ?: hrtimer_cancel(&t->timer);
        return ret;
}

static const struct bpf_func_proto bpf_timer_cancel_proto = {
        .func           = bpf_timer_cancel,
        .gpl_only       = true,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_TIMER,
};

/* This function is called by map_delete/update_elem for individual element and
 * by ops->map_release_uref when the user space reference to a map reaches zero.
 */
void bpf_timer_cancel_and_free(void *val)
{
        struct bpf_timer_kern *timer = val;
        struct bpf_hrtimer *t;

        /* Performance optimization: read timer->timer without lock first. */
        if (!READ_ONCE(timer->timer))
                return;

        __bpf_spin_lock_irqsave(&timer->lock);
        /* re-read it under lock */
        t = timer->timer;
        if (!t)
                goto out;
        drop_prog_refcnt(t);
        /* The subsequent bpf_timer_start/cancel() helpers won't be able to use
         * this timer, since it won't be initialized.
         */
        timer->timer = NULL;
out:
        __bpf_spin_unlock_irqrestore(&timer->lock);
        if (!t)
                return;
        /* Cancel the timer and wait for callback to complete if it was running.
         * If hrtimer_cancel() can be safely called it's safe to call kfree(t)
         * right after for both preallocated and non-preallocated maps.
         * The timer->timer = NULL was already done and no code path can
         * see address 't' anymore.
         *
         * Check that bpf_map_delete/update_elem() wasn't called from timer
         * callback_fn. In such case don't call hrtimer_cancel() (since it will
         * deadlock) and don't call hrtimer_try_to_cancel() (since it will just
         * return -1). Though callback_fn is still running on this cpu it's
         * safe to do kfree(t) because bpf_timer_cb() read everything it needed
         * from 't'. The bpf subprog callback_fn won't be able to access 't',
         * since timer->timer = NULL was already done. The timer will be
         * effectively cancelled because bpf_timer_cb() will return
         * HRTIMER_NORESTART.
         */
        if (this_cpu_read(hrtimer_running) != t)
                hrtimer_cancel(&t->timer);
        kfree(t);
}

const struct bpf_func_proto bpf_get_current_task_proto __weak;
const struct bpf_func_proto bpf_get_current_task_btf_proto __weak;
const struct bpf_func_proto bpf_probe_read_user_proto __weak;
const struct bpf_func_proto bpf_probe_read_user_str_proto __weak;
const struct bpf_func_proto bpf_probe_read_kernel_proto __weak;
const struct bpf_func_proto bpf_probe_read_kernel_str_proto __weak;
const struct bpf_func_proto bpf_task_pt_regs_proto __weak;

const struct bpf_func_proto *
bpf_base_func_proto(enum bpf_func_id func_id)
{
        switch (func_id) {
        case BPF_FUNC_map_lookup_elem:
                return &bpf_map_lookup_elem_proto;
        case BPF_FUNC_map_update_elem:
                return &bpf_map_update_elem_proto;
        case BPF_FUNC_map_delete_elem:
                return &bpf_map_delete_elem_proto;
        case BPF_FUNC_map_push_elem:
                return &bpf_map_push_elem_proto;
        case BPF_FUNC_map_pop_elem:
                return &bpf_map_pop_elem_proto;
        case BPF_FUNC_map_peek_elem:
                return &bpf_map_peek_elem_proto;
        case BPF_FUNC_get_prandom_u32:
                return &bpf_get_prandom_u32_proto;
        case BPF_FUNC_get_smp_processor_id:
                return &bpf_get_raw_smp_processor_id_proto;
        case BPF_FUNC_get_numa_node_id:
                return &bpf_get_numa_node_id_proto;
        case BPF_FUNC_tail_call:
                return &bpf_tail_call_proto;
        case BPF_FUNC_ktime_get_ns:
                return &bpf_ktime_get_ns_proto;
        case BPF_FUNC_ktime_get_boot_ns:
                return &bpf_ktime_get_boot_ns_proto;
        case BPF_FUNC_ringbuf_output:
                return &bpf_ringbuf_output_proto;
        case BPF_FUNC_ringbuf_reserve:
                return &bpf_ringbuf_reserve_proto;
        case BPF_FUNC_ringbuf_submit:
                return &bpf_ringbuf_submit_proto;
        case BPF_FUNC_ringbuf_discard:
                return &bpf_ringbuf_discard_proto;
        case BPF_FUNC_ringbuf_query:
                return &bpf_ringbuf_query_proto;
        case BPF_FUNC_for_each_map_elem:
                return &bpf_for_each_map_elem_proto;
        case BPF_FUNC_loop:
                return &bpf_loop_proto;
        case BPF_FUNC_strncmp:
                return &bpf_strncmp_proto;
        default:
                break;
        }

        if (!bpf_capable())
                return NULL;

        switch (func_id) {
        case BPF_FUNC_spin_lock:
                return &bpf_spin_lock_proto;
        case BPF_FUNC_spin_unlock:
                return &bpf_spin_unlock_proto;
        case BPF_FUNC_jiffies64:
                return &bpf_jiffies64_proto;
        case BPF_FUNC_per_cpu_ptr:
                return &bpf_per_cpu_ptr_proto;
        case BPF_FUNC_this_cpu_ptr:
                return &bpf_this_cpu_ptr_proto;
        case BPF_FUNC_timer_init:
                return &bpf_timer_init_proto;
        case BPF_FUNC_timer_set_callback:
                return &bpf_timer_set_callback_proto;
        case BPF_FUNC_timer_start:
                return &bpf_timer_start_proto;
        case BPF_FUNC_timer_cancel:
                return &bpf_timer_cancel_proto;
        default:
                break;
        }

        if (!perfmon_capable())
                return NULL;

        switch (func_id) {
        case BPF_FUNC_trace_printk:
                return bpf_get_trace_printk_proto();
        case BPF_FUNC_get_current_task:
                return &bpf_get_current_task_proto;
        case BPF_FUNC_get_current_task_btf:
                return &bpf_get_current_task_btf_proto;
        case BPF_FUNC_probe_read_user:
                return &bpf_probe_read_user_proto;
        case BPF_FUNC_probe_read_kernel:
                return security_locked_down(LOCKDOWN_BPF_READ_KERNEL) < 0 ?
                       NULL : &bpf_probe_read_kernel_proto;
        case BPF_FUNC_probe_read_user_str:
                return &bpf_probe_read_user_str_proto;
        case BPF_FUNC_probe_read_kernel_str:
                return security_locked_down(LOCKDOWN_BPF_READ_KERNEL) < 0 ?
                       NULL : &bpf_probe_read_kernel_str_proto;
        case BPF_FUNC_snprintf_btf:
                return &bpf_snprintf_btf_proto;
        case BPF_FUNC_snprintf:
                return &bpf_snprintf_proto;
        case BPF_FUNC_task_pt_regs:
                return &bpf_task_pt_regs_proto;
        case BPF_FUNC_trace_vprintk:
                return bpf_get_trace_vprintk_proto();
        default:
                return NULL;
        }
}