From 9328e0d1bc09e96bd7dc85374f5c2a1e0e04e539 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 11 Jan 2018 20:29:05 -0800 Subject: [PATCH] bpf: hashtab: move checks out of alloc function Use the new callback to perform allocation checks for hash maps. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Daniel Borkmann --- kernel/bpf/hashtab.c | 123 +++++++++++++++++++++++++------------------ 1 file changed, 73 insertions(+), 50 deletions(-) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index b80f42adf068..7fd6519444d3 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -227,6 +227,70 @@ static int alloc_extra_elems(struct bpf_htab *htab) } /* Called from syscall */ +static int htab_map_alloc_check(union bpf_attr *attr) +{ + bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || + attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); + bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH || + attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); + /* percpu_lru means each cpu has its own LRU list. + * it is different from BPF_MAP_TYPE_PERCPU_HASH where + * the map's value itself is percpu. percpu_lru has + * nothing to do with the map's value. + */ + bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); + bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); + int numa_node = bpf_map_attr_numa_node(attr); + + BUILD_BUG_ON(offsetof(struct htab_elem, htab) != + offsetof(struct htab_elem, hash_node.pprev)); + BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) != + offsetof(struct htab_elem, hash_node.pprev)); + + if (lru && !capable(CAP_SYS_ADMIN)) + /* LRU implementation is much complicated than other + * maps. Hence, limit to CAP_SYS_ADMIN for now. + */ + return -EPERM; + + if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK) + /* reserved bits should not be used */ + return -EINVAL; + + if (!lru && percpu_lru) + return -EINVAL; + + if (lru && !prealloc) + return -ENOTSUPP; + + if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru)) + return -EINVAL; + + /* check sanity of attributes. + * value_size == 0 may be allowed in the future to use map as a set + */ + if (attr->max_entries == 0 || attr->key_size == 0 || + attr->value_size == 0) + return -EINVAL; + + if (attr->key_size > MAX_BPF_STACK) + /* eBPF programs initialize keys on stack, so they cannot be + * larger than max stack size + */ + return -E2BIG; + + if (attr->value_size >= KMALLOC_MAX_SIZE - + MAX_BPF_STACK - sizeof(struct htab_elem)) + /* if value_size is bigger, the user space won't be able to + * access the elements via bpf syscall. This check also makes + * sure that the elem_size doesn't overflow and it's + * kmalloc-able later in htab_map_update_elem() + */ + return -E2BIG; + + return 0; +} + static struct bpf_map *htab_map_alloc(union bpf_attr *attr) { bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || @@ -245,52 +309,6 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) int err, i; u64 cost; - BUILD_BUG_ON(offsetof(struct htab_elem, htab) != - offsetof(struct htab_elem, hash_node.pprev)); - BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) != - offsetof(struct htab_elem, hash_node.pprev)); - - if (lru && !capable(CAP_SYS_ADMIN)) - /* LRU implementation is much complicated than other - * maps. Hence, limit to CAP_SYS_ADMIN for now. - */ - return ERR_PTR(-EPERM); - - if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK) - /* reserved bits should not be used */ - return ERR_PTR(-EINVAL); - - if (!lru && percpu_lru) - return ERR_PTR(-EINVAL); - - if (lru && !prealloc) - return ERR_PTR(-ENOTSUPP); - - if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru)) - return ERR_PTR(-EINVAL); - - /* check sanity of attributes. - * value_size == 0 may be allowed in the future to use map as a set - */ - if (attr->max_entries == 0 || attr->key_size == 0 || - attr->value_size == 0) - return ERR_PTR(-EINVAL); - - if (attr->key_size > MAX_BPF_STACK) - /* eBPF programs initialize keys on stack, so they cannot be - * larger than max stack size - */ - return ERR_PTR(-E2BIG); - - if (attr->value_size >= KMALLOC_MAX_SIZE - - MAX_BPF_STACK - sizeof(struct htab_elem)) - /* if value_size is bigger, the user space won't be able to - * access the elements via bpf syscall. This check also makes - * sure that the elem_size doesn't overflow and it's - * kmalloc-able later in htab_map_update_elem() - */ - return ERR_PTR(-E2BIG); - htab = kzalloc(sizeof(*htab), GFP_USER); if (!htab) return ERR_PTR(-ENOMEM); @@ -1142,6 +1160,7 @@ static void htab_map_free(struct bpf_map *map) } const struct bpf_map_ops htab_map_ops = { + .map_alloc_check = htab_map_alloc_check, .map_alloc = htab_map_alloc, .map_free = htab_map_free, .map_get_next_key = htab_map_get_next_key, @@ -1152,6 +1171,7 @@ const struct bpf_map_ops htab_map_ops = { }; const struct bpf_map_ops htab_lru_map_ops = { + .map_alloc_check = htab_map_alloc_check, .map_alloc = htab_map_alloc, .map_free = htab_map_free, .map_get_next_key = htab_map_get_next_key, @@ -1235,6 +1255,7 @@ int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value, } const struct bpf_map_ops htab_percpu_map_ops = { + .map_alloc_check = htab_map_alloc_check, .map_alloc = htab_map_alloc, .map_free = htab_map_free, .map_get_next_key = htab_map_get_next_key, @@ -1244,6 +1265,7 @@ const struct bpf_map_ops htab_percpu_map_ops = { }; const struct bpf_map_ops htab_lru_percpu_map_ops = { + .map_alloc_check = htab_map_alloc_check, .map_alloc = htab_map_alloc, .map_free = htab_map_free, .map_get_next_key = htab_map_get_next_key, @@ -1252,11 +1274,11 @@ const struct bpf_map_ops htab_lru_percpu_map_ops = { .map_delete_elem = htab_lru_map_delete_elem, }; -static struct bpf_map *fd_htab_map_alloc(union bpf_attr *attr) +static int fd_htab_map_alloc_check(union bpf_attr *attr) { if (attr->value_size != sizeof(u32)) - return ERR_PTR(-EINVAL); - return htab_map_alloc(attr); + return -EINVAL; + return htab_map_alloc_check(attr); } static void fd_htab_map_free(struct bpf_map *map) @@ -1327,7 +1349,7 @@ static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr) if (IS_ERR(inner_map_meta)) return inner_map_meta; - map = fd_htab_map_alloc(attr); + map = htab_map_alloc(attr); if (IS_ERR(map)) { bpf_map_meta_free(inner_map_meta); return map; @@ -1371,6 +1393,7 @@ static void htab_of_map_free(struct bpf_map *map) } const struct bpf_map_ops htab_of_maps_map_ops = { + .map_alloc_check = fd_htab_map_alloc_check, .map_alloc = htab_of_map_alloc, .map_free = htab_of_map_free, .map_get_next_key = htab_map_get_next_key,