netdev - [PATCH net] net/ipv4: Set oif in fib_compute_spec

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Date:   Sat,  7 Jul 2018 16:15:26 -0700
From:   dsahern@...nel.org
To:     netdev@...r.kernel.org
Cc:     lucien.xin@...il.com, David Ahern <dsahern@...il.com>
Subject: [PATCH net] net/ipv4: Set oif in fib_compute_spec_dst

From: David Ahern <dsahern@...il.com>

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@...il.com>
Signed-off-by: David Ahern <dsahern@...il.com>
---
 net/ipv4/fib_frontend.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index b21833651394..e46cdd310e5f 100644
--- 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,
-- 
2.11.0