bpf: bpf_setsockopt: reset sock dst on SO_MARK changes

In sock_setsockopt() (net/core/sock.h), when SO_MARK option is used
to change sk_mark, sk_dst_reset(sk) is called. The same should be
done in bpf_setsockopt().

Fixes: 8c4b4c7e9ff0 ("bpf: Add setsockopt helper function to bpf")
Reported-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Peter Oskolkov <posk@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index d9076e609fca..d9ea51b47f35 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4132,7 +4132,10 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
                         sk->sk_rcvlowat = val ? : 1;
                         break;
                 case SO_MARK:
-                        sk->sk_mark = val;
+                        if (sk->sk_mark != val) {
+                                sk->sk_mark = val;
+                                sk_dst_reset(sk);
+                        }
                         break;
                 default:
                         ret = -EINVAL;