From 14dc6f04f49dc12614d7e90928b495b8d73cd471 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Tue, 27 Jun 2017 23:08:34 -0700 Subject: 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 Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/arraymap.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'kernel/bpf/arraymap.c') diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index ecb43542246e..d771a3872500 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -334,6 +334,26 @@ static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key) return NULL; } +/* only called from syscall */ +int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value) +{ + void **elem, *ptr; + int ret = 0; + + if (!map->ops->map_fd_sys_lookup_elem) + return -ENOTSUPP; + + rcu_read_lock(); + elem = array_map_lookup_elem(map, key); + if (elem && (ptr = READ_ONCE(*elem))) + *value = map->ops->map_fd_sys_lookup_elem(ptr); + else + ret = -ENOENT; + rcu_read_unlock(); + + return ret; +} + /* only called from syscall */ int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file, void *key, void *value, u64 map_flags) @@ -400,6 +420,11 @@ static void prog_fd_array_put_ptr(void *ptr) bpf_prog_put(ptr); } +static u32 prog_fd_array_sys_lookup_elem(void *ptr) +{ + return ((struct bpf_prog *)ptr)->aux->id; +} + /* decrement refcnt of all bpf_progs that are stored in this map */ void bpf_fd_array_map_clear(struct bpf_map *map) { @@ -418,6 +443,7 @@ const struct bpf_map_ops prog_array_map_ops = { .map_delete_elem = fd_array_map_delete_elem, .map_fd_get_ptr = prog_fd_array_get_ptr, .map_fd_put_ptr = prog_fd_array_put_ptr, + .map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem, }; static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file, @@ -585,4 +611,5 @@ const struct bpf_map_ops array_of_maps_map_ops = { .map_delete_elem = fd_array_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, }; -- cgit v1.2.3