// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf-cgroup.h>
#include <linux/bpf.h>
#include <linux/bpf_local_storage.h>
#include <linux/btf.h>
#include <linux/bug.h>
#include <linux/filter.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <uapi/linux/btf.h>
#include <linux/btf_ids.h>
#ifdef CONFIG_CGROUP_BPF
#include "../cgroup/cgroup-internal.h"
#define LOCAL_STORAGE_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
struct bpf_cgroup_storage_map {
struct bpf_map map;
spinlock_t lock;
struct rb_root root;
struct list_head list;
};
static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
{
return container_of(map, struct bpf_cgroup_storage_map, map);
}
static bool attach_type_isolated(const struct bpf_map *map)
{
return map->key_size == sizeof(struct bpf_cgroup_storage_key);
}
static int bpf_cgroup_storage_key_cmp(const struct bpf_cgroup_storage_map *map,
const void *_key1, const void *_key2)
{
if (attach_type_isolated(&map->map)) {
const struct bpf_cgroup_storage_key *key1 = _key1;
const struct bpf_cgroup_storage_key *key2 = _key2;
if (key1->cgroup_inode_id < key2->cgroup_inode_id)
return -1;
else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
return 1;
else if (key1->attach_type < key2->attach_type)
return -1;
else if (key1->attach_type > key2->attach_type)
return 1;
} else {
const __u64 *cgroup_inode_id1 = _key1;
const __u64 *cgroup_inode_id2 = _key2;
if (*cgroup_inode_id1 < *cgroup_inode_id2)
return -1;
else if (*cgroup_inode_id1 > *cgroup_inode_id2)
return 1;
}
return 0;
}
struct bpf_cgroup_storage *
cgroup_storage_lookup(struct bpf_cgroup_storage_map *map,
void *key, bool locked)
{
struct rb_root *root = &map->root;
struct rb_node *node;
if (!locked)
spin_lock_bh(&map->lock);
node = root->rb_node;
while (node) {
struct bpf_cgroup_storage *storage;
storage = container_of(node, struct bpf_cgroup_storage, node);
switch (bpf_cgroup_storage_key_cmp(map, key, &storage->key)) {
case -1:
node = node->rb_left;
break;
case 1:
node = node->rb_right;
break;
default:
if (!locked)
spin_unlock_bh(&map->lock);
return storage;
}
}
if (!locked)
spin_unlock_bh(&map->lock);
return NULL;
}
static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
struct bpf_cgroup_storage *storage)
{
struct rb_root *root = &map->root;
struct rb_node **new = &(root->rb_node), *parent = NULL;
while (*new) {
struct bpf_cgroup_storage *this;
this = container_of(*new, struct bpf_cgroup_storage, node);
parent = *new;
switch (bpf_cgroup_storage_key_cmp(map, &storage->key, &this->key)) {
case -1:
new = &((*new)->rb_left);
break;
case 1:
new = &((*new)->rb_right);
break;
default:
return -EEXIST;
}
}
rb_link_node(&storage->node, parent, new);
rb_insert_color(&storage->node, root);
return 0;
}
static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *key)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct bpf_cgroup_storage *storage;
storage = cgroup_storage_lookup(map, key, false);
if (!storage)
return NULL;
return &READ_ONCE(storage->buf)->data[0];
}
static long cgroup_storage_update_elem(struct bpf_map *map, void *key,
void *value, u64 flags)
{
struct bpf_cgroup_storage *storage;
struct bpf_storage_buffer *new;
if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST)))
return -EINVAL;
if (unlikely((flags & BPF_F_LOCK) &&
!btf_record_has_field(map->record, BPF_SPIN_LOCK)))
return -EINVAL;
storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
key, false);
if (!storage)
return -ENOENT;
if (flags & BPF_F_LOCK) {
copy_map_value_locked(map, storage->buf->data, value, false);
return 0;
}
new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
__GFP_ZERO | GFP_NOWAIT | __GFP_NOWARN,
map->numa_node);
if (!new)
return -ENOMEM;
memcpy(&new->data[0], value, map->value_size);
check_and_init_map_value(map, new->data);
new = xchg(&storage->buf, new);
kfree_rcu(new, rcu);
return 0;
}
int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
void *value)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct bpf_cgroup_storage *storage;
int cpu, off = 0;
u32 size;
rcu_read_lock();
storage = cgroup_storage_lookup(map, key, false);
if (!storage) {
rcu_read_unlock();
return -ENOENT;
}
/* per_cpu areas are zero-filled and bpf programs can only
* access 'value_size' of them, so copying rounded areas
* will not leak any kernel data
*/
size = round_up(_map->value_size, 8);
for_each_possible_cpu(cpu) {
bpf_long_memcpy(value + off,
per_cpu_ptr(storage->percpu_buf, cpu), size);
off += size;
}
rcu_read_unlock();
return 0;
}
int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
void *value, u64 map_flags)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct bpf_cgroup_storage *storage;
int cpu, off = 0;
u32 size;
if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
return -EINVAL;
rcu_read_lock();
storage = cgroup_storage_lookup(map, key, false);
if (!storage) {
rcu_read_unlock();
return -ENOENT;
}
/* the user space will provide round_up(value_size, 8) bytes that
* will be copied into per-cpu area. bpf programs can only access
* value_size of it. During lookup the same extra bytes will be
* returned or zeros which were zero-filled by percpu_alloc,
* so no kernel data leaks possible
*/
size = round_up(_map->value_size, 8);
for_each_possible_cpu(cpu) {
bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
value + off, size);
off += size;
}
rcu_read_unlock();
return 0;
}
static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
void *_next_key)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct bpf_cgroup_storage *storage;
spin_lock_bh(&map->lock);
if (list_empty(&map->list))
goto enoent;
if (key) {
storage = cgroup_storage_lookup(map, key, true);
if (!storage)
goto enoent;
storage = list_next_entry(storage, list_map);
if (!storage)
goto enoent;
} else {
storage = list_first_entry(&map->list,
struct bpf_cgroup_storage, list_map);
}
spin_unlock_bh(&map->lock);
if (attach_type_isolated(&map->map)) {
struct bpf_cgroup_storage_key *next = _next_key;
*next = storage->key;
} else {
__u64 *next = _next_key;
*next = storage->key.cgroup_inode_id;
}
return 0;
enoent:
spin_unlock_bh(&map->lock);
return -ENOENT;
}
static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
{
__u32 max_value_size = BPF_LOCAL_STORAGE_MAX_VALUE_SIZE;
int numa_node = bpf_map_attr_numa_node(attr);
struct bpf_cgroup_storage_map *map;
/* percpu is bound by PCPU_MIN_UNIT_SIZE, non-percu
* is the same as other local storages.
*/
if (attr->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
max_value_size = min_t(__u32, max_value_size,
PCPU_MIN_UNIT_SIZE);
if (attr->key_size != sizeof(struct bpf_cgroup_storage_key) &&
attr->key_size != sizeof(__u64))
return ERR_PTR(-EINVAL);
if (attr->value_size == 0)
return ERR_PTR(-EINVAL);
if (attr->value_size > max_value_size)
return ERR_PTR(-E2BIG);
if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
!bpf_map_flags_access_ok(attr->map_flags))
return ERR_PTR(-EINVAL);
if (attr->max_entries)
/* max_entries is not used and enforced to be 0 */
return ERR_PTR(-EINVAL);
map = bpf_map_area_alloc(sizeof(struct bpf_cgroup_storage_map), numa_node);
if (!map)
return ERR_PTR(-ENOMEM);
/* copy mandatory map attributes */
bpf_map_init_from_attr(&map->map, attr);
spin_lock_init(&map->lock);
map->root = RB_ROOT;
INIT_LIST_HEAD(&map->list);
return &map->map;
}
static void cgroup_storage_map_free(struct bpf_map *_map)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct list_head *storages = &map->list;
struct bpf_cgroup_storage *storage, *stmp;
cgroup_lock();
list_for_each_entry_safe(storage, stmp, storages, list_map) {
bpf_cgroup_storage_unlink(storage);
bpf_cgroup_storage_free(storage);
}
cgroup_unlock();
WARN_ON(!RB_EMPTY_ROOT(&map->root));
WARN_ON(!list_empty(&map->list));
bpf_map_area_free(map);
}
static long cgroup_storage_delete_elem(struct bpf_map *map, void *key)
{
return -EINVAL;
}
static int cgroup_storage_check_btf(const struct bpf_map *map,
const struct btf *btf,
const struct btf_type *key_type,
const struct btf_type *value_type)
{
if (attach_type_isolated(map)) {
struct btf_member *m;
u32 offset, size;
/* Key is expected to be of struct bpf_cgroup_storage_key type,
* which is:
* struct bpf_cgroup_storage_key {
* __u64 cgroup_inode_id;
* __u32 attach_type;
* };
*/
/*
* Key_type must be a structure with two fields.
*/
if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
BTF_INFO_VLEN(key_type->info) != 2)
return -EINVAL;
/*
* The first field must be a 64 bit integer at 0 offset.
*/
m = (struct btf_member *)(key_type + 1);
size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
return -EINVAL;
/*
* The second field must be a 32 bit integer at 64 bit offset.
*/
m++;
offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
return -EINVAL;
} else {
u32 int_data;
/*
* Key is expected to be u64, which stores the cgroup_inode_id
*/
if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
return -EINVAL;
int_data = *(u32 *)(key_type + 1);
if (BTF_INT_BITS(int_data) != 64 || BTF_INT_OFFSET(int_data))
return -EINVAL;
}
return 0;
}
static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *key,
struct seq_file *m)
{
enum bpf_cgroup_storage_type stype;
struct bpf_cgroup_storage *storage;
int cpu;
rcu_read_lock();
storage = cgroup_storage_lookup(map_to_storage(map), key, false);
if (!storage) {
rcu_read_unlock();
return;
}
btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
stype = cgroup_storage_type(map);
if (stype == BPF_CGROUP_STORAGE_SHARED) {
seq_puts(m, ": ");
btf_type_seq_show(map->btf, map->btf_value_type_id,
&READ_ONCE(storage->buf)->data[0], m);
seq_putc(m, '\n');
} else {
seq_puts(m, ": {\n");
for_each_possible_cpu(cpu) {
seq_printf(m, "\tcpu%d: ", cpu);
btf_type_seq_show(map->btf, map->btf_value_type_id,
per_cpu_ptr(storage->percpu_buf, cpu),
m);
seq_putc(m, '\n');
}
seq_puts(m, "}\n");
}
rcu_read_unlock();
}
static u64 cgroup_storage_map_usage(const struct bpf_map *map)
{
/* Currently the dynamically allocated elements are not counted. */
return sizeof(struct bpf_cgroup_storage_map);
}
BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct,
bpf_cgroup_storage_map)
const struct bpf_map_ops cgroup_storage_map_ops = {
.map_alloc = cgroup_storage_map_alloc,
.map_free = cgroup_storage_map_free,
.map_get_next_key = cgroup_storage_get_next_key,
.map_lookup_elem = cgroup_storage_lookup_elem,
.map_update_elem = cgroup_storage_update_elem,
.map_delete_elem = cgroup_storage_delete_elem,
.map_check_btf = cgroup_storage_check_btf,
.map_seq_show_elem = cgroup_storage_seq_show_elem,
.map_mem_usage = cgroup_storage_map_usage,
.map_btf_id = &cgroup_storage_map_btf_ids[0],
};
int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
{
enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
if (aux->cgroup_storage[stype] &&
aux->cgroup_storage[stype] != _map)
return -EBUSY;
aux->cgroup_storage[stype] = _map;
return 0;
}
static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
{
size_t size;
if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
size = sizeof(struct bpf_storage_buffer) + map->value_size;
*pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
PAGE_SIZE) >> PAGE_SHIFT;
} else {
size = map->value_size;
*pages = round_up(round_up(size, 8) * num_possible_cpus(),
PAGE_SIZE) >> PAGE_SHIFT;
}
return size;
}
struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
enum bpf_cgroup_storage_type stype)
{
const gfp_t gfp = __GFP_ZERO | GFP_USER;
struct bpf_cgroup_storage *storage;
struct bpf_map *map;
size_t size;
u32 pages;
map = prog->aux->cgroup_storage[stype];
if (!map)
return NULL;
size = bpf_cgroup_storage_calculate_size(map, &pages);
storage = bpf_map_kmalloc_node(map, sizeof(struct bpf_cgroup_storage),
gfp, map->numa_node);
if (!storage)
goto enomem;
if (stype == BPF_CGROUP_STORAGE_SHARED) {
storage->buf = bpf_map_kmalloc_node(map, size, gfp,
map->numa_node);
if (!storage->buf)
goto enomem;
check_and_init_map_value(map, storage->buf->data);
} else {
storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
if (!storage->percpu_buf)
goto enomem;
}
storage->map = (struct bpf_cgroup_storage_map *)map;
return storage;
enomem:
kfree(storage);
return ERR_PTR(-ENOMEM);
}
static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
{
struct bpf_cgroup_storage *storage =
container_of(rcu, struct bpf_cgroup_storage, rcu);
kfree(storage->buf);
kfree(storage);
}
static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
{
struct bpf_cgroup_storage *storage =
container_of(rcu, struct bpf_cgroup_storage, rcu);
free_percpu(storage->percpu_buf);
kfree(storage);
}
void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
{
enum bpf_cgroup_storage_type stype;
struct bpf_map *map;
if (!storage)
return;
map = &storage->map->map;
stype = cgroup_storage_type(map);
if (stype == BPF_CGROUP_STORAGE_SHARED)
call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
else
call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
}
void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
struct cgroup *cgroup,
enum bpf_attach_type type)
{
struct bpf_cgroup_storage_map *map;
if (!storage)
return;
storage->key.attach_type = type;
storage->key.cgroup_inode_id = cgroup_id(cgroup);
map = storage->map;
spin_lock_bh(&map->lock);
WARN_ON(cgroup_storage_insert(map, storage));
list_add(&storage->list_map, &map->list);
list_add(&storage->list_cg, &cgroup->bpf.storages);
spin_unlock_bh(&map->lock);
}
void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
{
struct bpf_cgroup_storage_map *map;
struct rb_root *root;
if (!storage)
return;
map = storage->map;
spin_lock_bh(&map->lock);
root = &map->root;
rb_erase(&storage->node, root);
list_del(&storage->list_map);
list_del(&storage->list_cg);
spin_unlock_bh(&map->lock);
}
#endif
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