[PATCH 3.10 229/319] ip6_tunnel: disable caching when the traffic class is inherited

Willy Tarreau
2017-02-05T20:01:15Z

From: Paolo Abeni <pabeni@redhat.com>

commit b5c2d49544e5930c96e2632a7eece3f4325a1888 upstream.

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: Willy Tarreau <w@1wt.eu>
---
net/ipv6/ip6_tunnel.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 31bab1a..12984e6 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -950,12 +950,21 @@ 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;
+ bool use_cache = false;
int mtu;
unsigned int max_headroom = sizeof(struct ipv6hdr);
u8 proto;
int err = -1;

- 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);
@@ -1012,7 +1021,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
skb = new_skb;
}
skb_dst_drop(skb);
- if (fl6->flowi6_mark) {
+ if (!use_cache) {
skb_dst_set(skb, dst);
ndst = NULL;
} else {
--
2.8.0.rc2.1.gbe9624a