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 <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 4be5ff08..85f184e 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2196,7 +2196,8 @@
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.