net/ipv4: Set oif in fib_compute_spec_dst

Xin reported that icmp replies may not use the address on the device the
echo request is received if the destination address is broadcast. Instead
a route lookup is done without considering VRF context. Fix by setting
oif in flow struct to the master device if it is enslaved. That directs
the lookup to the VRF table. If the device is not enslaved, oif is still
0 so no affect.

Fixes: cd2fbe1b6b51 ("net: Use VRF device index for lookups on RX")
Reported-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index b21833651394233bbdb143d765e4408333b13b72..e46cdd310e5f86ef6985993e4226db614a2a8732 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -300,6 +300,7 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb)
        if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {
                struct flowi4 fl4 = {
                        .flowi4_iif = LOOPBACK_IFINDEX,
+                       .flowi4_oif = l3mdev_master_ifindex_rcu(dev),
                        .daddr = ip_hdr(skb)->saddr,
                        .flowi4_tos = RT_TOS(ip_hdr(skb)->tos),
                        .flowi4_scope = scope,