From: Eli Cooper <elicooper@gmx.com>
Date: Mon, 25 Dec 2017 10:43:49 +0800
Subject: ip6_tunnel: disable dst caching if tunnel is dual-stack
Git-commit: 23263ec86a5f44312d2899323872468752324107
Patch-mainline: v4.15-rc8
References: networking-stable-18_01_12

When an ip6_tunnel is in mode 'any', where the transport layer
protocol can be either 4 or 41, dst_cache must be disabled.

This is because xfrm policies might apply to only one of the two
protocols. Caching dst would cause xfrm policies for one protocol
incorrectly used for the other.

Signed-off-by: Eli Cooper <elicooper@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/ipv6/ip6_tunnel.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1081,10 +1081,11 @@ int ip6_tnl_xmit(struct sk_buff *skb, st
 			memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
 			neigh_release(neigh);
 		}
-	} else if (!(t->parms.flags &
-		     (IP6_TNL_F_USE_ORIG_TCLASS | IP6_TNL_F_USE_ORIG_FWMARK))) {
-		/* enable the cache only only if the routing decision does
-		 * not depend on the current inner header value
+	} else if (t->parms.proto != 0 && !(t->parms.flags &
+					    (IP6_TNL_F_USE_ORIG_TCLASS |
+					     IP6_TNL_F_USE_ORIG_FWMARK))) {
+		/* enable the cache only if neither the outer protocol nor the
+		 * routing decision depends on the current inner header value
 		 */
 		use_cache = true;
 	}