From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [RFC PATCH net] Revert "ipv6: ndisc: inherit metadata dst when creating ndisc requests" Date: Tue, 1 Dec 2015 14:20:35 +0100 Message-ID: <565D9EA3.3040105@6wind.com> References: <1448644625-29345-1-git-send-email-nicolas.dichtel@6wind.com> <20151130122038.26c5de6b@griffin> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: davem@davemloft.net, netdev@vger.kernel.org, Thomas Graf , Hannes Frederic Sowa To: Jiri Benc Return-path: Received: from mail-wm0-f50.google.com ([74.125.82.50]:33583 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753877AbbLANUy (ORCPT ); Tue, 1 Dec 2015 08:20:54 -0500 Received: by wmec201 with SMTP id c201so204945261wme.0 for ; Tue, 01 Dec 2015 05:20:53 -0800 (PST) In-Reply-To: <20151130122038.26c5de6b@griffin> Sender: netdev-owner@vger.kernel.org List-ID: Le 30/11/2015 12:20, Jiri Benc a =E9crit : > On Fri, 27 Nov 2015 18:17:05 +0100, Nicolas Dichtel wrote: >> This reverts commit ab450605b35caa768ca33e86db9403229bf42be4. >> >> In IPv6, we cannot inherit the dst of the original dst. ndisc packet= s >> are IPv6 packets and may take another route than the original packet= =2E >> >> This patch breaks the following scenario: a packet comes from eth0 a= nd >> is forwarded through vxlan1. The encapsulated packet triggers an NS >> which cannot be sent because of the wrong route. >> >> CC: Jiri Benc >> CC: Thomas Graf >> Signed-off-by: Nicolas Dichtel >> --- >> >> I know that this is not the right fix, it's why I've put RFC ;-) > > I'm actually okay with applying the revert for now. The revert is not > the right fix but at least it is less wrong than the current state. Ok for me. > > The problem is deeper. I fixed the IPv4 part in commit 63d008a4e9ee > ("ipv4: send arp replies to the correct tunnel") but for IPv6, I don'= t > know how to fix it. We already have dst set for IPv6, thus we cannot > use it to carry lwtunnel metadata for ndisc replies. I will also think a bit more to this. > > I tried to consult this with a couple of people, haven't met with muc= h > interest. > >> Should the right fix only do a copy of dst metadata in the new dst? > > Copy of the dst (I'm afraid we cannot just set the ->lwtstate field, > the same dst_entry may be shared between different tunnels) is pretty > much the only thing I could think of. Yes, you're right. Thank you, Nicolas