344 lines
8.4 KiB
C
344 lines
8.4 KiB
C
|
// SPDX-License-Identifier: GPL-2.0
|
||
|
|
/*
|
||
|
|
* Copyright (c) 2020 Facebook
|
||
|
|
* Copyright 2020 Google LLC.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/pid.h>
|
||
|
|
#include <linux/sched.h>
|
||
|
|
#include <linux/rculist.h>
|
||
|
|
#include <linux/list.h>
|
||
|
|
#include <linux/hash.h>
|
||
|
|
#include <linux/types.h>
|
||
|
|
#include <linux/spinlock.h>
|
||
|
|
#include <linux/bpf.h>
|
||
|
|
#include <linux/bpf_local_storage.h>
|
||
|
|
#include <linux/filter.h>
|
||
|
|
#include <uapi/linux/btf.h>
|
||
|
|
#include <linux/btf_ids.h>
|
||
|
|
#include <linux/fdtable.h>
|
||
|
|
#include <linux/rcupdate_trace.h>
|
||
|
|
|
||
|
|
DEFINE_BPF_STORAGE_CACHE(task_cache);
|
||
|
|
|
||
|
|
static DEFINE_PER_CPU(int, bpf_task_storage_busy);
|
||
|
|
|
||
|
|
static void bpf_task_storage_lock(void)
|
||
|
|
{
|
||
|
|
migrate_disable();
|
||
|
|
this_cpu_inc(bpf_task_storage_busy);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void bpf_task_storage_unlock(void)
|
||
|
|
{
|
||
|
|
this_cpu_dec(bpf_task_storage_busy);
|
||
|
|
migrate_enable();
|
||
|
|
}
|
||
|
|
|
||
|
|
static bool bpf_task_storage_trylock(void)
|
||
|
|
{
|
||
|
|
migrate_disable();
|
||
|
|
if (unlikely(this_cpu_inc_return(bpf_task_storage_busy) != 1)) {
|
||
|
|
this_cpu_dec(bpf_task_storage_busy);
|
||
|
|
migrate_enable();
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct bpf_local_storage __rcu **task_storage_ptr(void *owner)
|
||
|
|
{
|
||
|
|
struct task_struct *task = owner;
|
||
|
|
|
||
|
|
return &task->bpf_storage;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct bpf_local_storage_data *
|
||
|
|
task_storage_lookup(struct task_struct *task, struct bpf_map *map,
|
||
|
|
bool cacheit_lockit)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage *task_storage;
|
||
|
|
struct bpf_local_storage_map *smap;
|
||
|
|
|
||
|
|
task_storage =
|
||
|
|
rcu_dereference_check(task->bpf_storage, bpf_rcu_lock_held());
|
||
|
|
if (!task_storage)
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
smap = (struct bpf_local_storage_map *)map;
|
||
|
|
return bpf_local_storage_lookup(task_storage, smap, cacheit_lockit);
|
||
|
|
}
|
||
|
|
|
||
|
|
void bpf_task_storage_free(struct task_struct *task)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_elem *selem;
|
||
|
|
struct bpf_local_storage *local_storage;
|
||
|
|
bool free_task_storage = false;
|
||
|
|
struct hlist_node *n;
|
||
|
|
unsigned long flags;
|
||
|
|
|
||
|
|
rcu_read_lock();
|
||
|
|
|
||
|
|
local_storage = rcu_dereference(task->bpf_storage);
|
||
|
|
if (!local_storage) {
|
||
|
|
rcu_read_unlock();
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Neither the bpf_prog nor the bpf-map's syscall
|
||
|
|
* could be modifying the local_storage->list now.
|
||
|
|
* Thus, no elem can be added-to or deleted-from the
|
||
|
|
* local_storage->list by the bpf_prog or by the bpf-map's syscall.
|
||
|
|
*
|
||
|
|
* It is racing with bpf_local_storage_map_free() alone
|
||
|
|
* when unlinking elem from the local_storage->list and
|
||
|
|
* the map's bucket->list.
|
||
|
|
*/
|
||
|
|
bpf_task_storage_lock();
|
||
|
|
raw_spin_lock_irqsave(&local_storage->lock, flags);
|
||
|
|
hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
|
||
|
|
/* Always unlink from map before unlinking from
|
||
|
|
* local_storage.
|
||
|
|
*/
|
||
|
|
bpf_selem_unlink_map(selem);
|
||
|
|
free_task_storage = bpf_selem_unlink_storage_nolock(
|
||
|
|
local_storage, selem, false, false);
|
||
|
|
}
|
||
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
rcu_read_unlock();
|
||
|
|
|
||
|
|
/* free_task_storage should always be true as long as
|
||
|
|
* local_storage->list was non-empty.
|
||
|
|
*/
|
||
|
|
if (free_task_storage)
|
||
|
|
kfree_rcu(local_storage, rcu);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_data *sdata;
|
||
|
|
struct task_struct *task;
|
||
|
|
unsigned int f_flags;
|
||
|
|
struct pid *pid;
|
||
|
|
int fd, err;
|
||
|
|
|
||
|
|
fd = *(int *)key;
|
||
|
|
pid = pidfd_get_pid(fd, &f_flags);
|
||
|
|
if (IS_ERR(pid))
|
||
|
|
return ERR_CAST(pid);
|
||
|
|
|
||
|
|
/* We should be in an RCU read side critical section, it should be safe
|
||
|
|
* to call pid_task.
|
||
|
|
*/
|
||
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
||
|
|
task = pid_task(pid, PIDTYPE_PID);
|
||
|
|
if (!task) {
|
||
|
|
err = -ENOENT;
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
bpf_task_storage_lock();
|
||
|
|
sdata = task_storage_lookup(task, map, true);
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
put_pid(pid);
|
||
|
|
return sdata ? sdata->data : NULL;
|
||
|
|
out:
|
||
|
|
put_pid(pid);
|
||
|
|
return ERR_PTR(err);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key,
|
||
|
|
void *value, u64 map_flags)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_data *sdata;
|
||
|
|
struct task_struct *task;
|
||
|
|
unsigned int f_flags;
|
||
|
|
struct pid *pid;
|
||
|
|
int fd, err;
|
||
|
|
|
||
|
|
fd = *(int *)key;
|
||
|
|
pid = pidfd_get_pid(fd, &f_flags);
|
||
|
|
if (IS_ERR(pid))
|
||
|
|
return PTR_ERR(pid);
|
||
|
|
|
||
|
|
/* We should be in an RCU read side critical section, it should be safe
|
||
|
|
* to call pid_task.
|
||
|
|
*/
|
||
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
||
|
|
task = pid_task(pid, PIDTYPE_PID);
|
||
|
|
if (!task) {
|
||
|
|
err = -ENOENT;
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
bpf_task_storage_lock();
|
||
|
|
sdata = bpf_local_storage_update(
|
||
|
|
task, (struct bpf_local_storage_map *)map, value, map_flags,
|
||
|
|
GFP_ATOMIC);
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
|
||
|
|
err = PTR_ERR_OR_ZERO(sdata);
|
||
|
|
out:
|
||
|
|
put_pid(pid);
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int task_storage_delete(struct task_struct *task, struct bpf_map *map)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_data *sdata;
|
||
|
|
|
||
|
|
sdata = task_storage_lookup(task, map, false);
|
||
|
|
if (!sdata)
|
||
|
|
return -ENOENT;
|
||
|
|
|
||
|
|
bpf_selem_unlink(SELEM(sdata), true);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key)
|
||
|
|
{
|
||
|
|
struct task_struct *task;
|
||
|
|
unsigned int f_flags;
|
||
|
|
struct pid *pid;
|
||
|
|
int fd, err;
|
||
|
|
|
||
|
|
fd = *(int *)key;
|
||
|
|
pid = pidfd_get_pid(fd, &f_flags);
|
||
|
|
if (IS_ERR(pid))
|
||
|
|
return PTR_ERR(pid);
|
||
|
|
|
||
|
|
/* We should be in an RCU read side critical section, it should be safe
|
||
|
|
* to call pid_task.
|
||
|
|
*/
|
||
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
||
|
|
task = pid_task(pid, PIDTYPE_PID);
|
||
|
|
if (!task) {
|
||
|
|
err = -ENOENT;
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
bpf_task_storage_lock();
|
||
|
|
err = task_storage_delete(task, map);
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
out:
|
||
|
|
put_pid(pid);
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* *gfp_flags* is a hidden argument provided by the verifier */
|
||
|
|
BPF_CALL_5(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,
|
||
|
|
task, void *, value, u64, flags, gfp_t, gfp_flags)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_data *sdata;
|
||
|
|
|
||
|
|
WARN_ON_ONCE(!bpf_rcu_lock_held());
|
||
|
|
if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
|
||
|
|
return (unsigned long)NULL;
|
||
|
|
|
||
|
|
if (!task)
|
||
|
|
return (unsigned long)NULL;
|
||
|
|
|
||
|
|
if (!bpf_task_storage_trylock())
|
||
|
|
return (unsigned long)NULL;
|
||
|
|
|
||
|
|
sdata = task_storage_lookup(task, map, true);
|
||
|
|
if (sdata)
|
||
|
|
goto unlock;
|
||
|
|
|
||
|
|
/* only allocate new storage, when the task is refcounted */
|
||
|
|
if (refcount_read(&task->usage) &&
|
||
|
|
(flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
|
||
|
|
sdata = bpf_local_storage_update(
|
||
|
|
task, (struct bpf_local_storage_map *)map, value,
|
||
|
|
BPF_NOEXIST, gfp_flags);
|
||
|
|
|
||
|
|
unlock:
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL :
|
||
|
|
(unsigned long)sdata->data;
|
||
|
|
}
|
||
|
|
|
||
|
|
BPF_CALL_2(bpf_task_storage_delete, struct bpf_map *, map, struct task_struct *,
|
||
|
|
task)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
WARN_ON_ONCE(!bpf_rcu_lock_held());
|
||
|
|
if (!task)
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
if (!bpf_task_storage_trylock())
|
||
|
|
return -EBUSY;
|
||
|
|
|
||
|
|
/* This helper must only be called from places where the lifetime of the task
|
||
|
|
* is guaranteed. Either by being refcounted or by being protected
|
||
|
|
* by an RCU read-side critical section.
|
||
|
|
*/
|
||
|
|
ret = task_storage_delete(task, map);
|
||
|
|
bpf_task_storage_unlock();
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
|
||
|
|
{
|
||
|
|
return -ENOTSUPP;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct bpf_map *task_storage_map_alloc(union bpf_attr *attr)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_map *smap;
|
||
|
|
|
||
|
|
smap = bpf_local_storage_map_alloc(attr);
|
||
|
|
if (IS_ERR(smap))
|
||
|
|
return ERR_CAST(smap);
|
||
|
|
|
||
|
|
smap->cache_idx = bpf_local_storage_cache_idx_get(&task_cache);
|
||
|
|
return &smap->map;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void task_storage_map_free(struct bpf_map *map)
|
||
|
|
{
|
||
|
|
struct bpf_local_storage_map *smap;
|
||
|
|
|
||
|
|
smap = (struct bpf_local_storage_map *)map;
|
||
|
|
bpf_local_storage_cache_idx_free(&task_cache, smap->cache_idx);
|
||
|
|
bpf_local_storage_map_free(smap, &bpf_task_storage_busy);
|
||
|
|
}
|
||
|
|
|
||
|
|
BTF_ID_LIST_SINGLE(task_storage_map_btf_ids, struct, bpf_local_storage_map)
|
||
|
|
const struct bpf_map_ops task_storage_map_ops = {
|
||
|
|
.map_meta_equal = bpf_map_meta_equal,
|
||
|
|
.map_alloc_check = bpf_local_storage_map_alloc_check,
|
||
|
|
.map_alloc = task_storage_map_alloc,
|
||
|
|
.map_free = task_storage_map_free,
|
||
|
|
.map_get_next_key = notsupp_get_next_key,
|
||
|
|
.map_lookup_elem = bpf_pid_task_storage_lookup_elem,
|
||
|
|
.map_update_elem = bpf_pid_task_storage_update_elem,
|
||
|
|
.map_delete_elem = bpf_pid_task_storage_delete_elem,
|
||
|
|
.map_check_btf = bpf_local_storage_map_check_btf,
|
||
|
|
.map_btf_id = &task_storage_map_btf_ids[0],
|
||
|
|
.map_owner_storage_ptr = task_storage_ptr,
|
||
|
|
};
|
||
|
|
|
||
|
|
const struct bpf_func_proto bpf_task_storage_get_proto = {
|
||
|
|
.func = bpf_task_storage_get,
|
||
|
|
.gpl_only = false,
|
||
|
|
.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
|
||
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
||
|
|
.arg2_type = ARG_PTR_TO_BTF_ID,
|
||
|
|
.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
|
||
|
|
.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
|
||
|
|
.arg4_type = ARG_ANYTHING,
|
||
|
|
};
|
||
|
|
|
||
|
|
const struct bpf_func_proto bpf_task_storage_delete_proto = {
|
||
|
|
.func = bpf_task_storage_delete,
|
||
|
|
.gpl_only = false,
|
||
|
|
.ret_type = RET_INTEGER,
|
||
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
||
|
|
.arg2_type = ARG_PTR_TO_BTF_ID,
|
||
|
|
.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
|
||
|
|
};
|