bpf: sockmap, map_release does not hold refcnt for pinned maps

Relying on map_release hook to decrement the reference counts when a
map is removed only works if the map is not being pinned. In the
pinned case the ref is decremented immediately and the BPF programs
released. After this BPF programs may not be in-use which is not
what the user would expect.

This patch moves the release logic into bpf_map_put_uref() and brings
sockmap in-line with how a similar case is handled in prog array maps.

Fixes: 3d9e952697de ("bpf: sockmap, fix leaking maps with attached but not detached progs")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 14750e7c5ee4..027107f4be53 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -476,7 +476,7 @@ static u32 prog_fd_array_sys_lookup_elem(void *ptr)
 }
 
 /* decrement refcnt of all bpf_progs that are stored in this map */
-void bpf_fd_array_map_clear(struct bpf_map *map)
+static void bpf_fd_array_map_clear(struct bpf_map *map)
 {
         struct bpf_array *array = container_of(map, struct bpf_array, map);
         int i;
@@ -495,6 +495,7 @@ const struct bpf_map_ops prog_array_map_ops = {
         .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,
+        .map_release_uref = bpf_fd_array_map_clear,
 };
 
 static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,