netdev - Re: [RFC PATCH net-next 0/7 v2]IPv6:netfilter: defragment

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Date:	Tue, 23 Mar 2010 21:10:22 +0100 (CET)
From:	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
To:	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
cc:	Patrick McHardy <kaber@...sh.net>,
	Shan Wei <shanwei@...fujitsu.com>,
	YOSHIFUJI Hideaki <hideaki.yoshifuji@...il.com>,
	David Miller <davem@...emloft.net>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Yasuyuki KOZAKAI <yasuyuki.kozakai@...hiba.co.jp>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	netfilter-devel@...r.kernel.org
Subject: Re: [RFC PATCH net-next 0/7 v2]IPv6:netfilter: defragment

Hi,

On Wed, 24 Mar 2010, YOSHIFUJI Hideaki wrote:

> > In this case without conntrack, IPv6 would send an ICMPv6 message,
> > so in my opinion the transparent thing to do would be to still send
> > them. Of course only if reassembly is done on an end host.
> 
> Well, no.  conntrack should just forward even uncompleted fragments
> to next process (e.g. core ipv6 code), and then the core would send
> ICMP error back.  ICMP should be sent by the core ipv6 code according
> to decision of itself, not according to netfilter.

But what state could be associated by conntrack to the uncompleted 
fragments but the INVALID state? In consequence, in any sane setup, the 
uncompleted fragments will be dropped silently by a filter table rule
and no ICMP error message will be sent back.

Therefore I think iff the destination of the fragments is the host 
itself, then conntrack should generate an ICMP error message. But that 
error message must be processed by conntrack to set its state and then 
the fate of the generated packet can be decided by a rule.

Best regards,
Jozsef
-
E-mail  : kadlec@...ckhole.kfki.hu, kadlec@...l.kfki.hu
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Address : KFKI Research Institute for Particle and Nuclear Physics
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