[TCP]: Honour sk_bound_dev_if in tcp_v4_send_ack

A time_wait socket inherits sk_bound_dev_if from the original socket,
but it is not used when sending ACK packets using ip_send_reply.

Fix by passing the oif to ip_send_reply in struct ip_reply_arg and
use it for output routing.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 47c61055eb60..97e294e82679 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -705,6 +705,8 @@ static void tcp_v4_send_ack(struct tcp_timewait_sock *twsk,
                                       ip_hdr(skb)->saddr, /* XXX */
                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+        if (twsk)
+                arg.bound_dev_if = twsk->tw_sk.tw_bound_dev_if;
 
         ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);