gre: Don't accidentally set RTO_ONLINK in gre_fill_metadata_dst()

Mask the ECN bits before initialising ->flowi4_tos. The tunnel key may
have the last ECN bit set, which will interfere with the route lookup
process as ip_route_output_key_hash() interpretes this bit specially
(to restrict the route scope).

Found by code inspection, compile tested only.

Fixes: 962924fa2b7a ("ip_gre: Refactor collect metatdata mode tunnel xmit to ip_md_tunnel_xmit")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 2ac2b95..99db2e4 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -604,8 +604,9 @@ static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 
        key = &info->key;
        ip_tunnel_init_flow(&fl4, IPPROTO_GRE, key->u.ipv4.dst, key->u.ipv4.src,
-                           tunnel_id_to_key32(key->tun_id), key->tos, 0,
-                           skb->mark, skb_get_hash(skb));
+                           tunnel_id_to_key32(key->tun_id),
+                           key->tos & ~INET_ECN_MASK, 0, skb->mark,
+                           skb_get_hash(skb));
        rt = ip_route_output_key(dev_net(dev), &fl4);
        if (IS_ERR(rt))
                return PTR_ERR(rt);