linux-kernel - Re: [PATCH net v2] ipv6: Prevent ipv6_find_hdr() from returning ENOENT for valid non-first fragments

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Message-ID: <20150109113145.GA4426@salvia>
Date:	Fri, 9 Jan 2015 12:31:45 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Rahul Sharma <rsharma@...sta.com>, netdev@...r.kernel.org
Cc:	YOSHIFUJI Hideaki <hideaki.yoshifuji@...aclelinux.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH net v2] ipv6: Prevent ipv6_find_hdr() from returning
 ENOENT for valid non-first fragments

On Fri, Jan 09, 2015 at 06:53:06PM +0900, YOSHIFUJI Hideaki wrote:
> Hi,
> 
> Rahul Sharma wrote:
> >ipv6_find_hdr() currently assumes that the next-header field in the
> >fragment header of the non-first fragment is the "protocol number of
> >the last header" (here last header excludes any extension header
> >protocol numbers ) which is incorrect as per RFC2460. The next-header
> >value is the first header of the fragmentable part of the original
> >packet (which can be extension header as well).
> >This can create reassembly problems. For example: Fragmented
> >authenticated OSPFv3 packets (where AH header is inserted before the
> >protocol header). For the second fragment, the next header value in
> >the fragment header will be NEXTHDR_AUTH which is correct but
> >ipv6_find_hdr will return ENOENT since AH is an extension header
> >resulting in second fragment getting dropped. This check for the
> >presence of non-extension header needs to be removed.
> >
> >Signed-off-by: Rahul Sharma <rsharma@...sta.com>
> 
> Acked-by: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>

I already mentioned this patch will break ip6tables.

And it doesn't make sense to me that you still hit the problem with
nf_defrag_ipv6.

Could you please hold on with this patch until we clarify what the
real undelying problem is? Could you send me a pcap trace?
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