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authorMartin KaFai Lau <kafai@fb.com>2017-06-27 23:08:34 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-29 13:13:25 -0400
commit14dc6f04f49dc12614d7e90928b495b8d73cd471 (patch)
tree159ebddef04be2ae417c503ab46593be570c680f /kernel/bpf/hashtab.c
parent77b0d3617738e532bae683bf9d88ea35fff223e5 (diff)
bpf: Add syscall lookup support for fd array and htab
This patch allows userspace to do BPF_MAP_LOOKUP_ELEM on BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_ARRAY_OF_MAPS and BPF_MAP_TYPE_HASH_OF_MAPS. The lookup returns a prog-id or map-id to the userspace. The userspace can then use the BPF_PROG_GET_FD_BY_ID or BPF_MAP_GET_FD_BY_ID to get a fd. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/hashtab.c')
-rw-r--r--kernel/bpf/hashtab.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 004334ea13ba..4fb463172aa8 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1244,6 +1244,26 @@ static void fd_htab_map_free(struct bpf_map *map)
}
/* only called from syscall */
+int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
+{
+ void **ptr;
+ int ret = 0;
+
+ if (!map->ops->map_fd_sys_lookup_elem)
+ return -ENOTSUPP;
+
+ rcu_read_lock();
+ ptr = htab_map_lookup_elem(map, key);
+ if (ptr)
+ *value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
+ else
+ ret = -ENOENT;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+/* only called from syscall */
int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
void *key, void *value, u64 map_flags)
{
@@ -1305,4 +1325,5 @@ const struct bpf_map_ops htab_of_maps_map_ops = {
.map_delete_elem = htab_map_delete_elem,
.map_fd_get_ptr = bpf_map_fd_get_ptr,
.map_fd_put_ptr = bpf_map_fd_put_ptr,
+ .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
};