#define HTAB_CREATE_FLAG_MASK \
(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \
- BPF_F_RDONLY | BPF_F_WRONLY)
+ BPF_F_RDONLY | BPF_F_WRONLY | BPF_F_ZERO_SEED)
struct bucket {
struct hlist_nulls_head head;
*/
bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
+ bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
int numa_node = bpf_map_attr_numa_node(attr);
BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
*/
return -EPERM;
+ if (zero_seed && !capable(CAP_SYS_ADMIN))
+ /* Guard against local DoS, and discourage production use. */
+ return -EPERM;
+
if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK)
/* reserved bits should not be used */
return -EINVAL;
if (!htab->buckets)
goto free_htab;
- htab->hashrnd = get_random_int();
+ if (htab->map.map_flags & BPF_F_ZERO_SEED)
+ htab->hashrnd = 0;
+ else
+ htab->hashrnd = get_random_int();
+
for (i = 0; i < htab->n_buckets; i++) {
INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
raw_spin_lock_init(&htab->buckets[i].lock);