From 28335a7445202a3d118145a07d9138e9881ebe18 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 7 Oct 2015 08:40:13 -0700 Subject: [PATCH] net: Do not drop to make_route if oif is l3mdev Commit deaa0a6a930 ("net: Lookup actual route when oif is VRF device") exposed a bug in __ip_route_output_key_hash for VRF devices: on FIB lookup failure if the oif is specified the current logic drops to make_route on the assumption that the route tables are wrong. For VRF/L3 master devices this leads to wrong dst entries and route lookups. For example: $ ip route ls table vrf-red unreachable default broadcast 10.2.1.0 dev eth1 proto kernel scope link src 10.2.1.2 10.2.1.0/24 dev eth1 proto kernel scope link src 10.2.1.2 local 10.2.1.2 dev eth1 proto kernel scope host src 10.2.1.2 broadcast 10.2.1.255 dev eth1 proto kernel scope link src 10.2.1.2 $ ip route get oif vrf-red 1.1.1.1 1.1.1.1 dev vrf-red src 10.0.0.2 cache With this patch: $ ip route get oif vrf-red 1.1.1.1 RTNETLINK answers: No route to host which is the correct response based on the default route Signed-off-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/route.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 4be5ff08f98d..85f184e429c6 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2196,7 +2196,8 @@ struct rtable *__ip_route_output_key_hash(struct net *net, struct flowi4 *fl4, if (err) { res.fi = NULL; res.table = NULL; - if (fl4->flowi4_oif) { + if (fl4->flowi4_oif && + !netif_index_is_l3_master(net, fl4->flowi4_oif)) { /* Apparently, routing tables are wrong. Assume, that the destination is on link. -- 2.20.1