From e2446eaab5585555a38ea0df4e01ff313dbb4ac9 Mon Sep 17 00:00:00 2001 From: Shawn Lu Date: Sat, 4 Feb 2012 12:38:09 +0000 Subject: [PATCH] tcp_v4_send_reset: binding oif to iif in no sock case Binding RST packet outgoing interface to incoming interface for tcp v4 when there is no socket associate with it. when sk is not NULL, using sk->sk_bound_dev_if instead. (suggested by Eric Dumazet). This has few benefits: 1. tcp_v6_send_reset already did that. 2. This helps tcp connect with SO_BINDTODEVICE set. When connection is lost, we still able to sending out RST using same interface. 3. we are sending reply, it is most likely to be succeed if iif is used Signed-off-by: Shawn Lu Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 337ba4c..94d683a 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -651,6 +651,11 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) arg.iov[0].iov_len, IPPROTO_TCP, 0); arg.csumoffset = offsetof(struct tcphdr, check) / 2; arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0; + /* When socket is gone, all binding information is lost. + * routing might fail in this case. using iif for oif to + * make sure we can deliver it + */ + arg.bound_dev_if = sk ? sk->sk_bound_dev_if : inet_iif(skb); net = dev_net(skb_dst(skb)->dev); arg.tos = ip_hdr(skb)->tos; -- 2.7.4