From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Benc Subject: Re: [RFC PATCH net] Revert "ipv6: ndisc: inherit metadata dst when creating ndisc requests" Date: Mon, 30 Nov 2015 12:20:38 +0100 Message-ID: <20151130122038.26c5de6b@griffin> References: <1448644625-29345-1-git-send-email-nicolas.dichtel@6wind.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, Thomas Graf , Hannes Frederic Sowa To: Nicolas Dichtel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33524 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751116AbbK3LUm (ORCPT ); Mon, 30 Nov 2015 06:20:42 -0500 In-Reply-To: <1448644625-29345-1-git-send-email-nicolas.dichtel@6wind.com> Sender: netdev-owner@vger.kernel.org List-ID: 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 packets > are IPv6 packets and may take another route than the original packet. > > This patch breaks the following scenario: a packet comes from eth0 and > 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. 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 tried to consult this with a couple of people, haven't met with much 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. > Feedback is welcomed. Yes. Thanks, Jiri -- Jiri Benc