net/ipv4: Set oif in fib_compute_spec_dst

[ Upstream commit e7372197e15856ec4ee66b668020a662994db103 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index ffae472e250a58e074d62f678353bb802147efb4..7bdd89354db5cc7f8b40c4831d3de23068d45dcf 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -290,6 +290,7 @@ __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,