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Message-ID: <alpine.LSU.2.01.1004011557270.5368@obet.zrqbmnf.qr>
Date: Thu, 1 Apr 2010 15:59:49 +0200 (CEST)
From: Jan Engelhardt <jengelh@...ozas.de>
To: Patrick McHardy <kaber@...sh.net>
cc: netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 5/5] netfilter: xt_TEE: have cloned packet travel through
Xtables too
On Thursday 2010-04-01 15:48, Patrick McHardy wrote:
>Jan Engelhardt wrote:
>> On Thursday 2010-04-01 15:22, Patrick McHardy wrote:
>>>>>> Conntrack loops are prevented by using a dummy conntrack, just as
>>>>>> NOTRACK does.
>>>>> [...]
>>>>>> - When the cloned packets gets XFRMed or tunneled, its status switches
>>>>>> from "special" to "plain". Doing policy routing on them does not seem
>>>>>> so far-fetched.
>>>>> My question was about the case without conntrack.
>>>> Hm. Do you have any suggestion in countering a case whereby a user
>>>> does -I OUTPUT -j TEE without conntrack?
>>>>
>>>> Perhaps making nesting a feature that requires conntrack, such that the
>>>> non-CT case can't loop?
>>> If we drop the reentrancy thing, what should work is to prevent
>>> using loopback as output device and using something similar to
>>> the recursion counters tunnel devices used to have.
>>
>> Nah. I'm going to pick a bit from struct skbuff to indicate the
>> packet was teed so as to avoid that loop.
>
>That's a bad idea, we shouldn't be adding new skb members for something
>as peripheral as this module.
I would have done this, which does not add a member:
IP6CB(skb)->flags |= IPSKB_CLONED;
>What's wrong with adding a reentrancy counter?
Sounds like a plan.
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