linux-kernel - Re: [PATCH net-next v2] tcp: Add mark for TIMEWAIT sockets

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Message-Id: <20180510.174520.128087783939744310.davem@davemloft.net>
Date:   Thu, 10 May 2018 17:45:20 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     jmaxwell37@...il.com
Cc:     kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        jmaxwell@...hat.com
Subject: Re: [PATCH net-next v2] tcp: Add mark for TIMEWAIT sockets

From: Jon Maxwell <jmaxwell37@...il.com>
Date: Thu, 10 May 2018 16:53:51 +1000

> This version has some suggestions by Eric Dumazet:
> 
> - Use a local variable for the mark in IPv6 instead of ctl_sk to avoid SMP 
> races. 
> - Use the more elegant "IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark"
> statement. 
> - Factorize code as sk_fullsock() check is not necessary.
> 
> Aidan McGurn from Openwave Mobility systems reported the following bug:
> 
> "Marked routing is broken on customer deployment. Its effects are large 
> increase in Uplink retransmissions caused by the client never receiving 
> the final ACK to their FINACK - this ACK misses the mark and routes out 
> of the incorrect route."
> 
> Currently marks are added to sk_buffs for replies when the "fwmark_reflect" 
> sysctl is enabled. But not for TW sockets that had sk->sk_mark set via 
> setsockopt(SO_MARK..).  
> 
> Fix this in IPv4/v6 by adding tw->tw_mark for TIME_WAIT sockets. Copy the the 
> original sk->sk_mark in __inet_twsk_hashdance() to the new tw->tw_mark location. 
> Then progate this so that the skb gets sent with the correct mark. Do the same 
> for resets. Give the "fwmark_reflect" sysctl precedence over sk->sk_mark so that
> netfilter rules are still honored.
> 
> Signed-off-by: Jon Maxwell <jmaxwell37@...il.com>

I'm surprised the lack of a mark in timewait sockets wasn't noticed earlier.

Applied, thank you.