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From: Daniel Mack <daniel@zonque•org>
To: Florian Westphal <fw@strlen•de>
Cc: Daniel Borkmann <dborkman@redhat•com>,
	Alexey Perevalov <a.perevalov@samsung•com>,
	Pablo Neira Ayuso <pablo@netfilter•org>,
	netdev <netdev@vger•kernel.org>
Subject: Re: cgroup matches in INPUT chain
Date: Fri, 20 Mar 2015 14:57:39 +0100	[thread overview]
Message-ID: <550C2753.9020608@zonque.org> (raw)
In-Reply-To: <20150319185807.GA3845@breakpoint.cc>

Hi,

On 03/19/2015 07:58 PM, Florian Westphal wrote:
> Daniel Mack <daniel@zonque•org> wrote:
>> In my tests, however, NF_INET_LOCAL_IN is iterated before early_demux()
>> is called,
> 
> Early demux occurs after PRE_ROUTING but before LOCAL_IN.

Hmm, you're right, except it isn't in my case. I'm not familiar with
that code, so please bear with me :)

In my simple test setup, when skbs are dequeued by process_backlog(),
they have skb->_skb_refdst set, and hence ip_rcv_finish() does not call
into early_demux() prior to iterating the INPUT chain:

ip_rcv_finish()
    if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL)
        ...
        ipprot->early_demux(skb);
        ...

Therefore, cgroup_mt() in xt_cgroup.c will be called with skb->sk ==
NULL, which makes the match callback ineffective. From looking at the
code, I assume xt_owner has the same problem.

However, when the skb is processed directly from the NIC's interrupt
handler, early_demux() is called as expected, and the match succeeds.

Any pointers how this can be solved would be greatly appreciated.


Thanks,
Daniel

next prev parent reply	other threads:[~2015-03-20 13:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-19 18:41 cgroup matches in INPUT chain Daniel Mack
2015-03-19 18:58 ` Florian Westphal
2015-03-20 13:57   ` Daniel Mack [this message]
2015-03-20 16:11     ` Florian Westphal
2015-03-20 16:21       ` Daniel Mack
2015-03-20 20:18         ` Daniel Borkmann
2015-03-20 20:55         ` Cong Wang
2015-03-20 22:07           ` Daniel Mack

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