From: Peter Oskolkov <posk@google.com>
Date: Wed, 16 Jan 2019 08:47:54 -0800
Subject: bpf: bpf_setsockopt: reset sock dst on SO_MARK changes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.0-rc3
Git-commit: f4924f24da8c7ef64195096817f3cde324091d97
References: bsc#1109837

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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/filter.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3772,7 +3772,10 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_so
 			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;