From: David Barmann <david.barmann@stackpath.com>
Date: Thu, 8 Nov 2018 14:13:35 +0000 (-0600)
Subject: sock: Reset dst when changing sk_mark via setsockopt
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=50254256f382;p=linux.git

sock: Reset dst when changing sk_mark via setsockopt

When setting the SO_MARK socket option, if the mark changes, the dst
needs to be reset so that a new route lookup is performed.

This fixes the case where an application wants to change routing by
setting a new sk_mark.  If this is done after some packets have already
been sent, the dst is cached and has no effect.

Signed-off-by: David Barmann <david.barmann@stackpath.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/core/sock.c b/net/core/sock.c
index 7b304e454a385..6d7e189e3cd9f 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -952,10 +952,12 @@ set_rcvbuf:
 			clear_bit(SOCK_PASSSEC, &sock->flags);
 		break;
 	case SO_MARK:
-		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {
 			ret = -EPERM;
-		else
+		} else if (val != sk->sk_mark) {
 			sk->sk_mark = val;
+			sk_dst_reset(sk);
+		}
 		break;
 
 	case SO_RXQ_OVFL: