Commit fd8db077 authored by Florian Lehner's avatar Florian Lehner Committed by Daniel Borkmann
Browse files

bpf, devmap: Add .map_alloc_check 



Use the .map_allock_check callback to perform allocation checks before
allocating memory for the devmap.

Signed-off-by: default avatarFlorian Lehner <dev@der-flo.net>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240615101158.57889-1-dev@der-flo.net
parent 69716e44

kernel/bpf/devmap.c

+17 −10
Original line number Diff line number Diff line
@@ -107,7 +107,7 @@ static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab, 
	return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];

}



static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)

static int dev_map_alloc_check(union bpf_attr *attr)

{

	u32 valsize = attr->value_size;
@@ -121,23 +121,28 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) 
	    attr->map_flags & ~DEV_CREATE_FLAG_MASK)

		return -EINVAL;



	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {

		/* Hash table size must be power of 2; roundup_pow_of_two()

		 * can overflow into UB on 32-bit arches

		 */

		if (attr->max_entries > 1UL << 31)

			return -EINVAL;

	}



	return 0;

}



static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)

{

	/* Lookup returns a pointer straight to dev->ifindex, so make sure the

	 * verifier prevents writes from the BPF side

	 */

	attr->map_flags |= BPF_F_RDONLY_PROG;





	bpf_map_init_from_attr(&dtab->map, attr);



	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {

		/* hash table size must be power of 2; roundup_pow_of_two() can

		 * overflow into UB on 32-bit arches, so check that first

		 */

		if (dtab->map.max_entries > 1UL << 31)

			return -EINVAL;



		/* Hash table size must be power of 2 */

		dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);



		dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,

							   dtab->map.numa_node);

		if (!dtab->dev_index_head)
@@ -1040,6 +1045,7 @@ static u64 dev_map_mem_usage(const struct bpf_map *map) 
BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)

const struct bpf_map_ops dev_map_ops = {

	.map_meta_equal = bpf_map_meta_equal,

	.map_alloc_check = dev_map_alloc_check,

	.map_alloc = dev_map_alloc,

	.map_free = dev_map_free,

	.map_get_next_key = dev_map_get_next_key,
@@ -1054,6 +1060,7 @@ const struct bpf_map_ops dev_map_ops = { 


const struct bpf_map_ops dev_map_hash_ops = {

	.map_meta_equal = bpf_map_meta_equal,

	.map_alloc_check = dev_map_alloc_check,

	.map_alloc = dev_map_alloc,

	.map_free = dev_map_free,

	.map_get_next_key = dev_map_hash_get_next_key,