From: "Gerd v. Egidy" <lists@egidy.de>
To: jamal <hadi@cyberus.ca>
Cc: netdev@vger.kernel.org, dev@lists.strongswan.org
Subject: xfrm by MARK: tcp problems when mark for in and out differ
Date: Wed, 13 Oct 2010 15:57:06 +0200 [thread overview]
Message-ID: <201010131557.06588.lists@egidy.de> (raw)
Hi,
I use current strongswan git to set up ipsec connections with the xfrm by MARK
feature. When I configure xfrm policies with different marks for incoming and
outgoing packets, incoming tcp connections can't be established anymore. The
SYN-ACK packet is never sent through the tunnel.
An example policy looks like this:
src 192.168.5.0/24 dst 192.168.1.0/24
dir out priority 1760
mark 5/0xffffffff
tmpl src 172.16.1.131 dst 172.16.1.130
proto esp reqid 16384 mode tunnel
src 192.168.1.0/24 dst 192.168.5.0/24
dir fwd priority 1760
tmpl src 172.16.1.130 dst 172.16.1.131
proto esp reqid 16384 mode tunnel
src 192.168.1.0/24 dst 192.168.5.0/24
dir in priority 1760
tmpl src 172.16.1.130 dst 172.16.1.131
proto esp reqid 16384 mode tunnel
-> incoming packets are without mark, outgoing packets are marked with 5
I traced the packet in the xfrm code and found out that the problem is in the
flow data. When the SYN-ACK hits __xfrm_lookup, the value in fl->mark is 0
(more precisely: the mark value used in the incoming packet). This means that
xfrm_policy_match will not match on the correct policy because the mark values
differ.
I'm not too familiar with the kernel networking code. But I guess that the
flow for the SYN-ACK is set up based on the data used for the SYN and is not
updated when my iptables rule changes the mark of the packet:
iptables -t raw -A OUTPUT -s 192.168.5.0/255.255.255.0 -d
192.168.1.0/255.255.255.0 -j MARK --set-mark 5
I guess that the flow data should be updated somewhere. But I don't know what
the correct place for that code would be.
Can somebody more familiar with the network stack help me with this please?
Thank you very much.
Kind regards,
Gerd
--
Address (better: trap) for people I really don't want to get mail from:
jonas@cactusamerica.com
next reply other threads:[~2010-10-13 13:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-13 13:57 Gerd v. Egidy [this message]
2010-10-14 12:02 ` xfrm by MARK: tcp problems when mark for in and out differ jamal
2010-10-14 13:01 ` Gerd v. Egidy
2010-10-14 13:14 ` jamal
2010-10-14 14:14 ` -j MARK in raw vs. mangle (was Re: xfrm by MARK: tcp problems when mark for in and out differ) Gerd v. Egidy
2010-10-14 12:05 ` xfrm by MARK: tcp problems when mark for in and out differ jamal
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