linux/kernel/bpf/local_storage.c
Daniel Borkmann e8d2bec045 bpf: decouple btf from seq bpf fs dump and enable more maps
Commit a26ca7c982 ("bpf: btf: Add pretty print support to
the basic arraymap") and 699c86d6ec ("bpf: btf: add pretty
print for hash/lru_hash maps") enabled support for BTF and
dumping via BPF fs for array and hash/lru map. However, both
can be decoupled from each other such that regular BPF maps
can be supported for attaching BTF key/value information,
while not all maps necessarily need to dump via map_seq_show_elem()
callback.

The basic sanity check which is a prerequisite for all maps
is that key/value size has to match in any case, and some maps
can have extra checks via map_check_btf() callback, e.g.
probing certain types or indicating no support in general. With
that we can also enable retrieving BTF info for per-cpu map
types and lpm.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
2018-08-13 00:52:45 +02:00

380 lines
8.5 KiB
C

//SPDX-License-Identifier: GPL-2.0
#include <linux/bpf-cgroup.h>
#include <linux/bpf.h>
#include <linux/bug.h>
#include <linux/filter.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
DEFINE_PER_CPU(void*, bpf_cgroup_storage);
#ifdef CONFIG_CGROUP_BPF
#define LOCAL_STORAGE_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
struct bpf_cgroup_storage_map {
struct bpf_map map;
spinlock_t lock;
struct bpf_prog *prog;
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 int bpf_cgroup_storage_key_cmp(
const struct bpf_cgroup_storage_key *key1,
const struct bpf_cgroup_storage_key *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;
return 0;
}
static struct bpf_cgroup_storage *cgroup_storage_lookup(
struct bpf_cgroup_storage_map *map, struct bpf_cgroup_storage_key *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(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(&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_key *key = _key;
struct bpf_cgroup_storage *storage;
storage = cgroup_storage_lookup(map, key, false);
if (!storage)
return NULL;
return &READ_ONCE(storage->buf)->data[0];
}
static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
void *value, u64 flags)
{
struct bpf_cgroup_storage_key *key = _key;
struct bpf_cgroup_storage *storage;
struct bpf_storage_buffer *new;
if (flags & BPF_NOEXIST)
return -EINVAL;
storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
key, false);
if (!storage)
return -ENOENT;
new = kmalloc_node(sizeof(struct bpf_storage_buffer) +
map->value_size, __GFP_ZERO | GFP_USER,
map->numa_node);
if (!new)
return -ENOMEM;
memcpy(&new->data[0], value, map->value_size);
new = xchg(&storage->buf, new);
kfree_rcu(new, rcu);
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_key *key = _key;
struct bpf_cgroup_storage_key *next = _next_key;
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);
if (!storage)
goto enoent;
} else {
storage = list_first_entry(&map->list,
struct bpf_cgroup_storage, list);
}
spin_unlock_bh(&map->lock);
next->attach_type = storage->key.attach_type;
next->cgroup_inode_id = 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)
{
int numa_node = bpf_map_attr_numa_node(attr);
struct bpf_cgroup_storage_map *map;
if (attr->key_size != sizeof(struct bpf_cgroup_storage_key))
return ERR_PTR(-EINVAL);
if (attr->value_size > PAGE_SIZE)
return ERR_PTR(-E2BIG);
if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK)
/* reserved bits should not be used */
return ERR_PTR(-EINVAL);
if (attr->max_entries)
/* max_entries is not used and enforced to be 0 */
return ERR_PTR(-EINVAL);
map = kmalloc_node(sizeof(struct bpf_cgroup_storage_map),
__GFP_ZERO | GFP_USER, numa_node);
if (!map)
return ERR_PTR(-ENOMEM);
map->map.pages = round_up(sizeof(struct bpf_cgroup_storage_map),
PAGE_SIZE) >> PAGE_SHIFT;
/* 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);
WARN_ON(!RB_EMPTY_ROOT(&map->root));
WARN_ON(!list_empty(&map->list));
kfree(map);
}
static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
{
return -EINVAL;
}
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 = map_check_no_btf,
};
int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
int ret = -EBUSY;
spin_lock_bh(&map->lock);
if (map->prog && map->prog != prog)
goto unlock;
if (prog->aux->cgroup_storage && prog->aux->cgroup_storage != _map)
goto unlock;
map->prog = prog;
prog->aux->cgroup_storage = _map;
ret = 0;
unlock:
spin_unlock_bh(&map->lock);
return ret;
}
void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *_map)
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
spin_lock_bh(&map->lock);
if (map->prog == prog) {
WARN_ON(prog->aux->cgroup_storage != _map);
map->prog = NULL;
prog->aux->cgroup_storage = NULL;
}
spin_unlock_bh(&map->lock);
}
struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog)
{
struct bpf_cgroup_storage *storage;
struct bpf_map *map;
u32 pages;
map = prog->aux->cgroup_storage;
if (!map)
return NULL;
pages = round_up(sizeof(struct bpf_cgroup_storage) +
sizeof(struct bpf_storage_buffer) +
map->value_size, PAGE_SIZE) >> PAGE_SHIFT;
if (bpf_map_charge_memlock(map, pages))
return ERR_PTR(-EPERM);
storage = kmalloc_node(sizeof(struct bpf_cgroup_storage),
__GFP_ZERO | GFP_USER, map->numa_node);
if (!storage) {
bpf_map_uncharge_memlock(map, pages);
return ERR_PTR(-ENOMEM);
}
storage->buf = kmalloc_node(sizeof(struct bpf_storage_buffer) +
map->value_size, __GFP_ZERO | GFP_USER,
map->numa_node);
if (!storage->buf) {
bpf_map_uncharge_memlock(map, pages);
kfree(storage);
return ERR_PTR(-ENOMEM);
}
storage->map = (struct bpf_cgroup_storage_map *)map;
return storage;
}
void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
{
u32 pages;
struct bpf_map *map;
if (!storage)
return;
map = &storage->map->map;
pages = round_up(sizeof(struct bpf_cgroup_storage) +
sizeof(struct bpf_storage_buffer) +
map->value_size, PAGE_SIZE) >> PAGE_SHIFT;
bpf_map_uncharge_memlock(map, pages);
kfree_rcu(storage->buf, rcu);
kfree_rcu(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->kn->id.id;
map = storage->map;
spin_lock_bh(&map->lock);
WARN_ON(cgroup_storage_insert(map, storage));
list_add(&storage->list, &map->list);
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);
spin_unlock_bh(&map->lock);
}
#endif