[PATCH 5.4 302/320] gre: Dont accidentally set RTO_ONLINK in gre_fill_metadata_dst()

Greg Kroah-Hartman
2022-01-24T19:51:09Z

From: Guillaume Nault <gnault@redhat.com>

commit f7716b318568b22fbf0e3be99279a979e217cf71 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/ip_gre.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -577,8 +577,9 @@ static int gre_fill_metadata_dst(struct

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);