udp_tunnel: Pass UDP socket down through udp_tunnel{, 6}_xmit_skb().

That was we can make sure the output path of ipv4/ipv6 operate on
the UDP socket rather than whatever random thing happens to be in
skb->sk.

Based upon a patch by Jiri Pirko.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index ef3d7aa..66deebc 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -176,7 +176,8 @@
 			goto tx_error;
 		}
 		ttl = ip4_dst_hoplimit(&rt->dst);
-		err = udp_tunnel_xmit_skb(rt, clone, src->ipv4.s_addr,
+		err = udp_tunnel_xmit_skb(rt, ub->ubsock->sk, clone,
+					  src->ipv4.s_addr,
 					  dst->ipv4.s_addr, 0, ttl, 0,
 					  src->udp_port, dst->udp_port,
 					  false, true);
@@ -197,7 +198,8 @@
 		if (err)
 			goto tx_error;
 		ttl = ip6_dst_hoplimit(ndst);
-		err = udp_tunnel6_xmit_skb(ndst, clone, ndst->dev, &src->ipv6,
+		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, clone,
+					   ndst->dev, &src->ipv6,
 					   &dst->ipv6, 0, ttl, src->udp_port,
 					   dst->udp_port, false);
 #endif