xfrm: Clear low order bits of ->flowi4_tos in decode_session4().

Commit 23e7b1bfed61 ("xfrm: Don't accidentally set RTO_ONLINK in
decode_session4()") fixed a problem where decode_session4() could
erroneously set the RTO_ONLINK flag for IPv4 route lookups. This
problem was reintroduced when decode_session4() was modified to
use the flow dissector.

Fix this by clearing again the two low order bits of ->flowi4_tos.
Found by code inspection, compile tested only.

Fixes: 7a0207094f1b ("xfrm: policy: replace session decode with flow dissector")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 1b7e75159727791ef5ed03299729711ed775a16e..7351f32052dc0b21d37a144bbb03a630ef9bee5a 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3416,7 +3416,7 @@ decode_session4(const struct xfrm_flow_keys *flkeys, struct flowi *fl, bool reve
        }
 
        fl4->flowi4_proto = flkeys->basic.ip_proto;
-       fl4->flowi4_tos = flkeys->ip.tos;
+       fl4->flowi4_tos = flkeys->ip.tos & ~INET_ECN_MASK;
 }
 
 #if IS_ENABLED(CONFIG_IPV6)