diff options
Diffstat (limited to '')
-rw-r--r-- | kernel/bpf/local_storage.c | 622 |
1 files changed, 622 insertions, 0 deletions
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c new file mode 100644 index 000000000..b139247d2 --- /dev/null +++ b/kernel/bpf/local_storage.c @@ -0,0 +1,622 @@ +//SPDX-License-Identifier: GPL-2.0 +#include <linux/bpf-cgroup.h> +#include <linux/bpf.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> + +#ifdef CONFIG_CGROUP_BPF + +DEFINE_PER_CPU(struct bpf_cgroup_storage_info, + bpf_cgroup_storage_info[BPF_CGROUP_STORAGE_NEST_MAX]); + +#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 int 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) && + !map_value_has_spin_lock(map))) + 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 = kmalloc_node(sizeof(struct bpf_storage_buffer) + + map->value_size, + __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN, + map->numa_node); + if (!new) + return -ENOMEM; + + memcpy(&new->data[0], value, map->value_size); + check_and_init_map_lock(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) +{ + int numa_node = bpf_map_attr_numa_node(attr); + struct bpf_cgroup_storage_map *map; + struct bpf_map_memory mem; + int ret; + + 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 > PAGE_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); + + ret = bpf_map_charge_init(&mem, sizeof(struct bpf_cgroup_storage_map)); + if (ret < 0) + return ERR_PTR(ret); + + map = kmalloc_node(sizeof(struct bpf_cgroup_storage_map), + __GFP_ZERO | GFP_USER, numa_node); + if (!map) { + bpf_map_charge_finish(&mem); + return ERR_PTR(-ENOMEM); + } + + bpf_map_charge_move(&map->map.memory, &mem); + + /* 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; + + mutex_lock(&cgroup_mutex); + + list_for_each_entry_safe(storage, stmp, storages, list_map) { + bpf_cgroup_storage_unlink(storage); + bpf_cgroup_storage_free(storage); + } + + mutex_unlock(&cgroup_mutex); + + 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; +} + +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 = cgroup_storage_type(map); + 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_puts(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_puts(m, "\n"); + } + seq_puts(m, "}\n"); + } + rcu_read_unlock(); +} + +static int cgroup_storage_map_btf_id; +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_btf_name = "bpf_cgroup_storage_map", + .map_btf_id = &cgroup_storage_map_btf_id, +}; + +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) +{ + struct bpf_cgroup_storage *storage; + struct bpf_map *map; + gfp_t flags; + size_t size; + u32 pages; + + map = prog->aux->cgroup_storage[stype]; + if (!map) + return NULL; + + size = bpf_cgroup_storage_calculate_size(map, &pages); + + 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) + goto enomem; + + flags = __GFP_ZERO | GFP_USER; + + if (stype == BPF_CGROUP_STORAGE_SHARED) { + storage->buf = kmalloc_node(size, flags, map->numa_node); + if (!storage->buf) + goto enomem; + check_and_init_map_lock(map, storage->buf->data); + } else { + storage->percpu_buf = __alloc_percpu_gfp(size, 8, flags); + if (!storage->percpu_buf) + goto enomem; + } + + storage->map = (struct bpf_cgroup_storage_map *)map; + + return storage; + +enomem: + bpf_map_uncharge_memlock(map, pages); + 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; + u32 pages; + + if (!storage) + return; + + map = &storage->map->map; + + bpf_cgroup_storage_calculate_size(map, &pages); + bpf_map_uncharge_memlock(map, pages); + + 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 |