From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH net-next] ipv6: addrconf: fix mcast route for GRE devices Date: Wed, 30 Jul 2014 18:09:27 +0200 Message-ID: <1406736567.6757.14.camel@localhost> References: <1406681743-104844-1-git-send-email-equinox@diac24.net> <1406733282.5122.12.camel@localhost> <20140730153503.GJ801478@jupiter.n2.diac24.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , netdev@vger.kernel.org, Stephen Hemminger To: David Lamparter Return-path: Received: from out2-smtp.messagingengine.com ([66.111.4.26]:60304 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753705AbaG3QJa (ORCPT ); Wed, 30 Jul 2014 12:09:30 -0400 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by gateway1.nyi.internal (Postfix) with ESMTP id 55DCC2341C for ; Wed, 30 Jul 2014 12:09:29 -0400 (EDT) In-Reply-To: <20140730153503.GJ801478@jupiter.n2.diac24.net> Sender: netdev-owner@vger.kernel.org List-ID: Hi, On Mi, 2014-07-30 at 17:35 +0200, David Lamparter wrote: > (New patch following in separate mail - I haven't touched > addrconf_sit_config since I have no clue about ISATAP & the likes.) isatap shouldn't use multicast and afaik output path does block multicast tx. sit in non-ptp mainly depends on 2002:: or 6rd prefix and drops others packets. sit-ptp can use multicast. > > On Wed, Jul 30, 2014 at 05:14:42PM +0200, Hannes Frederic Sowa wrote: > > On Mi, 2014-07-30 at 02:55 +0200, David Lamparter wrote: > > > GRE devices, for some reason, were coming up with an autoconfigured > > > address, but no ff00::/8 route in the local table. This breaks any kind > > > of multicast, in particular OSPFv3, mDNS, - and ND. In fact, IPv6 only > > > works at all because there is little need for ND on PtP devices. > > > > > > Adding any other IPv6 address on the device would rectify this issue > > > through inet6_addr_add()/addrconf_add_dev() - and would leave the route > > > around even if the address was later removed. (This is probably why > > > this issue was not discovered earlier. AFAICS it has been there from > > > the beginning, e.g. aee80b5 "generate link local address for GRE > > > tunnel") > > > > Yep, this is poor, but changing this will break user space... > > How exactly will this break user space? Because the multicast routes will always be restored after e.g. a route flush or manual route deletion. Scripts might depend on this. > > > (Note: multicast is supported on GRE devices of all kinds, including PtP > > > GRE, P-t-Mcast GRE and NBMA-GRE.) > > > > > > Fixes: aee80b54b235 (ipv6: generate link local address for GRE tunnel) > > > Signed-off-by: David Lamparter > > > Cc: Stephen Hemminger > > > > We should install routes before joining LL, I would go with > > > > idev = addrconf_add_dev(dev); > > if (IS_ERR(idev)) > > return; > > > > in addrconf_gre_config etc. > > Well, yeah, to be honest I have no clue why these functions are > separated as they are. Once fixed up, the only difference between > addrconf_gre_config and addrconf_dev_config is the true/false value on > prefix_route for addrconf_addr_gen... and what the rationale for that > is, I can only consult an oracle for. Basically this is a slalom run to keep exisisting behaviour and clean up the code a little bit. > How about pushing the switch(dev->type) down from addrconf_notify into > addrconf_dev_config()? > > > Looks like we don't correctly configure ARPHRD_IP6GRE gre tunnels... > > IP6GRE doesn't currently auto-generate a link-local address at all, is > that what you meant? (Yeah we could/should add that too...) Exactly. Thanks, Hannes