netdev - Re: [PATCH] tcp_v4_send_reset: binding oif to iif in no sock case

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Date:	Sat, 04 Feb 2012 22:49:16 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Shawn Lu <shawn.lu@...csson.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org, xiaoclu@...il.com
Subject: Re: [PATCH] tcp_v4_send_reset: binding oif to iif in no sock case

Le samedi 04 février 2012 à 13:44 -0800, Shawn Lu a écrit :
> Binding RST packet outgoing interface to incoming interface
> for tcp v4 when there is no socket associate with it.
> 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 <shawn.lu@...csson.com>
> ---
> V3: reformat comments as suggested
>  net/ipv4/tcp_ipv4.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 90e4793..4d6f81c 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -676,6 +676,11 @@ 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;

Acked-by: Eric Dumazet <eric.dumazet@...il.com>



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