From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [patch iproute2 v2 0/2] add support for IFA_F_MANAGETEMPADDR Date: Mon, 6 Jan 2014 17:01:39 +0100 Message-ID: <20140106160139.GB10204@order.stressinduktion.org> References: <1388676879-2603-1-git-send-email-jiri@resnulli.us> <20140102172949.GF22494@order.stressinduktion.org> <20140104104331.GB9295@minipsycho.orion> <20140104105515.GA25828@order.stressinduktion.org> <20140104110557.GD9295@minipsycho.orion> <20140104111546.GB25828@order.stressinduktion.org> <1388834511.7407.5.camel@weing> <20140104113543.GC25828@order.stressinduktion.org> <1389022909.23397.4.camel@weing> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Jiri Pirko , netdev@vger.kernel.org, stephen@networkplumber.org, dcbw@redhat.com To: Thomas Haller Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:42487 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753292AbaAFQBl (ORCPT ); Mon, 6 Jan 2014 11:01:41 -0500 Content-Disposition: inline In-Reply-To: <1389022909.23397.4.camel@weing> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Jan 06, 2014 at 04:41:49PM +0100, Thomas Haller wrote: > On Sat, 2014-01-04 at 12:35 +0100, Hannes Frederic Sowa wrote: > > On Sat, Jan 04, 2014 at 12:21:51PM +0100, Thomas Haller wrote: > > > > > >Also, I saw that NetworkManager switched to install autoconf addresses > > > > > >as /128, doesn't this break with IFA_F_MANAGETEMPADDR, as you expect a /64 > > > > > >prefixlen? > > > > > > > > > > /64 is required > > > > > > > > Ok, currently NM seems to "violate" that as it installs autoconf addresses > > > > with 128 prefixlen, so IFA_F_MANAGETEMPADDR should not work on them. > > > > (currently observed on Fedora 20). > > > > > > True, I noticed that too. I think that is a bug in NM to add the > > > addresses as /128. Probably, we will fix that soon. > > > > The change could be valid. Otherwise currently NM could not correctly handle > > prefix information in RAs in some cases: > > > > It is possible to let the client generate an autonomously address in a > > prefix which is actually not on-link (L=0). Kernel would automatically > > create prefix route by mistake, if NM tries to install such an address > > with /64 prefix. This does not happen if the prefix address uses 128 > > prefixlen. > > > > Would be great to have feedback on this, as this could be easily solved by an > > additional ifa_flag. > > > > Greetings, > > > > Hannes > > > > > Hi Hannes, > > > good point. I think, the user-space application (NetworkManager) should > add the autoconf addresses as /64. But the kernel should not generate > any routes in that case. It's up to the application to add them > (depending on the on-link flag). > > > What do you think about something like: I would introduce a new flag for that and also make it accessible via iproute, maybe later. Otherwise IFA_F_MANAGETEMPADDR is overloaded and doesn't do justice to its name. And since Jiri made new room in ifa_flags, it shoud be no problem. ;) Btw. while just reviewing anycast changes, I noticed a funny thing: Kernel does allocate an anycast address which is the same as the autoconf address, if NM installs /128 address and you have ipv6 forwarding enabled (fedora 20 install + ipv6 forwarding because of libvirt). You can see the addresses pop up in /proc/net/anycast6. I currenlty don't know if that is problematic. Everything seems to work here for me. ;) In the end, I don't think we should install anycast for /128, but I am not sure, yet. Greetings, Hannes