From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH nf] netfilter: ipv6: Orphan skbs in nf_ct_frag6_gather() Date: Thu, 14 Apr 2016 10:40:15 +0200 Message-ID: <20160414084015.GA3192@breakpoint.cc> References: <1460570974-44050-1-git-send-email-joe@ovn.org> <063D6719AE5E284EB5DD2968C1650D6D5F4A226C@AcuExch.aculab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: 'Joe Stringer' , "netfilter-devel@vger.kernel.org" , "fw@strlen.de" , "diproiettod@vmware.com" , "netdev@vger.kernel.org" To: David Laight Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:41216 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752498AbcDNIkZ (ORCPT ); Thu, 14 Apr 2016 04:40:25 -0400 Content-Disposition: inline In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D5F4A226C@AcuExch.aculab.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: David Laight wrote: > From: Joe Stringer > > Sent: 13 April 2016 19:10 > > This is the IPv6 equivalent of commit 8282f27449bf ("inet: frag: Always > > orphan skbs inside ip_defrag()"). > > > > Prior to commit 029f7f3b8701 ("netfilter: ipv6: nf_defrag: avoid/free > > clone operations"), ipv6 fragments sent to nf_ct_frag6_gather() would be > > cloned (implicitly orphaning) prior to queueing for reassembly. As such, > > when the IPv6 message is eventually reassembled, the skb->sk for all > > fragments would be NULL. After that commit was introduced, rather than > > cloning, the original skbs were queued directly without orphaning. The > > end result is that all frags except for the first and last may have a > > socket attached. > > I'd have thought that the queued fragments would still want to be > resource-counted against the socket (I think that is what skb->sk is for). No, ipv4/ipv6 reasm has its own accouting. > Although I can't imagine why IPv6 reassembly is happening on skb > associated with a socket. Right, thats a much more interesting question -- both ipv4 and ipv6 orphan skbs before NF_HOOK prerouting trip. (That being said, I don't mind the patch, I'm just be curious how this can happen).