ip6_tunnel: disable caching when the traffic class is inherited

[ Upstream commit b5c2d49544e5930c96e2632a7eece3f4325a1888 ]

If an ip6 tunnel is configured to inherit the traffic class from
the inner header, the dst_cache must be disabled or it will foul
the policy routing.

The issue is apprently there since at leat Linux-2.6.12-rc2.

Reported-by: Liam McBirnie <liam.mcbirnie@boeing.com>
Cc: Liam McBirnie <liam.mcbirnie@boeing.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 741917c..195b083 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -894,13 +894,22 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
        struct ipv6_tel_txoption opt;
        struct dst_entry *dst = NULL, *ndst = NULL;
        struct net_device *tdev;
        struct ipv6_tel_txoption opt;
        struct dst_entry *dst = NULL, *ndst = NULL;
        struct net_device *tdev;

+       bool use_cache = false;

        int mtu;
        unsigned int max_headroom = sizeof(struct ipv6hdr);
        u8 proto;
        int err = -1;
        int pkt_len;
 
        int mtu;
        unsigned int max_headroom = sizeof(struct ipv6hdr);
        u8 proto;
        int err = -1;
        int pkt_len;
 

-       if (!fl6->flowi6_mark)
+       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
+                */
+               use_cache = true;
+       }
+
+       if (use_cache)

                dst = ip6_tnl_dst_check(t);
        if (!dst) {
                ndst = ip6_route_output(net, NULL, fl6);
                dst = ip6_tnl_dst_check(t);
        if (!dst) {
                ndst = ip6_route_output(net, NULL, fl6);


@@ -959,7 +968,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
                skb = new_skb;
        }
        skb_dst_drop(skb);
                skb = new_skb;
        }
        skb_dst_drop(skb);

-       if (fl6->flowi6_mark) {
+       if (!use_cache) {

                skb_dst_set(skb, dst);
                ndst = NULL;
        } else {
                skb_dst_set(skb, dst);
                ndst = NULL;
        } else {