From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757003AbbAIADL (ORCPT ); Thu, 8 Jan 2015 19:03:11 -0500 Received: from mail.us.es ([193.147.175.20]:41750 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752785AbbAIADI (ORCPT ); Thu, 8 Jan 2015 19:03:08 -0500 X-Qmail-Scanner-Diagnostics: from 127.0.0.1 by antivirus2 (envelope-from , uid 501) with qmail-scanner-2.10 (clamdscan: 0.98.5/19898. spamassassin: 3.4.0. Clear:RC:1(127.0.0.1):SA:0(-104.0/7.5):. Processed in 2.651723 secs); 09 Jan 2015 00:03:04 -0000 X-Spam-ASN: AS12715 87.216.0.0/16 X-Envelope-From: pneira@us.es Date: Fri, 9 Jan 2015 01:05:46 +0100 From: Pablo Neira Ayuso To: Hannes Frederic Sowa Cc: Rahul Sharma , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org Subject: Re: [PATCH net] ipv6: Prevent ipv6_find_hdr() from returning ENOENT for valid non-first fragments Message-ID: <20150109000546.GA3488@salvia> References: <20150106224706.GA7416@salvia> <1420627396.26870.36.camel@stressinduktion.org> <20150108205328.GA3361@salvia> <1420756756.1755002.211556745.0418D128@webmail.messagingengine.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1420756756.1755002.211556745.0418D128@webmail.messagingengine.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 08, 2015 at 11:39:16PM +0100, Hannes Frederic Sowa wrote: > Hi Pablo, > > On Thu, Jan 8, 2015, at 21:53, Pablo Neira Ayuso wrote: > > I'm afraid we cannot just get rid of that !ipv6_ext_hdr() check. The > > ipv6_find_hdr() function is designed to return the transport protocol. > > After the proposed change, it will return extension header numbers. > > This will break existing ip6tables rulesets since the `-p' option > > relies on this function to match the transport protocol. > > > > Note that the AH header is skipped (see code a bit below this > > problematic fragmentation handling) so the follow up header after the > > AH header is returned as the transport header. > > > > We can probably return the AH protocol number for non-1st fragments. > > However, that would be something new to ip6tables since nobody has > > ever seen packet matching `-p ah' rules. Thus, we restore control to > > the user to allow this, but we would accept all kind of fragmented AH > > traffic through the firewall since we cannot know what transport > > protocol contains from non-1st fragments (unless I'm missing anything, > > I need to have a closer look at this again tomorrow with fresher > > mind). > > The code in question is guarded by (_frag_off != 0), so we are > definitely processing a non-1st fragment currently. The -p match would > happen at the time when the packet is reassembled and thus ipv6_find_hdr > will find the real transport (final) header at this point (I hope I > followed the code correctly here). Then, Rahul should get things working by modprobing nf_defrag_ipv6.