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

From: Eric Dumazet
Date: Thu May 10 2018 - 09:27:10 EST




On 05/09/2018 11:53 PM, Jon Maxwell wrote:
> 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@xxxxxxxxx>

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>

Thanks Jon.