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linux/kernel/bpf/helpers.c
Alexei Starovoitov 07be4c4a3e bpf: Add bpf_copy_from_user() helper.
Sleepable BPF programs can now use copy_from_user() to access user memory.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-4-alexei.starovoitov@gmail.com
2020-08-28 21:20:33 +02:00

710 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
*/
#include <linux/bpf.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 "../../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());
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());
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());
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_pop_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_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;
strncpy(buf, task->comm, size);
/* Verifier guarantees that size > 0. For task->comm exceeding
* size, guarantee that buf is %NUL-terminated. Unconditionally
* done here to save the size test.
*/
buf[size - 1] = 0;
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);
notrace BPF_CALL_1(bpf_spin_lock, struct bpf_spin_lock *, lock)
{
unsigned long flags;
local_irq_save(flags);
__bpf_spin_lock(lock);
__this_cpu_write(irqsave_flags, flags);
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,
};
notrace BPF_CALL_1(bpf_spin_unlock, struct bpf_spin_lock *, lock)
{
unsigned long flags;
flags = __this_cpu_read(irqsave_flags);
__bpf_spin_unlock(lock);
local_irq_restore(flags);
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(lock);
copy_map_value(map, dst, src);
____bpf_spin_unlock(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 = task_dfl_cgroup(current);
return cgroup_id(cgrp);
}
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 = task_dfl_cgroup(current);
struct cgroup *ancestor;
ancestor = cgroup_ancestor(cgrp, ancestor_level);
if (!ancestor)
return 0;
return cgroup_id(ancestor);
}
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
DECLARE_PER_CPU(struct bpf_cgroup_storage*,
bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
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;
void *ptr;
storage = this_cpu_read(bpf_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,
.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,
.arg2_type = ARG_CONST_SIZE,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_LONG,
};
#endif
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,
.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,
};
const struct bpf_func_proto bpf_get_current_task_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_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;
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_trace_printk:
if (!perfmon_capable())
return NULL;
return bpf_get_trace_printk_proto();
case BPF_FUNC_jiffies64:
return &bpf_jiffies64_proto;
default:
break;
}
if (!perfmon_capable())
return NULL;
switch (func_id) {
case BPF_FUNC_get_current_task:
return &bpf_get_current_task_proto;
case BPF_FUNC_probe_read_user:
return &bpf_probe_read_user_proto;
case BPF_FUNC_probe_read_kernel:
return &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 &bpf_probe_read_kernel_str_proto;
default:
return NULL;
}
}