netdev - Re: [PATCH 5/5] netfilter: xt_TEE: have cloned packet travel through Xtables too

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Message-ID: <alpine.LSU.2.01.1004011511180.1174@obet.zrqbmnf.qr>
Date:	Thu, 1 Apr 2010 15:15:38 +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 13:09, 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?

>> I can think of a handful of applications:
>>  - CLASSIFY
>
>Good point, you should probably reset a couple of skb members
>after the skb_copy().

I take it you mean

 nf_reset(skb)
 skb->mark = 0;
 skb_init_secmark(nskb);

Or should we be using skb_alloc and copying the data portion over, like 
ipt_REJECT does since v2.6.24-2931-g9ba99b0?

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