From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [RFC PATCH net-next 0/5] netns: allow to identify peer netns Date: Wed, 02 Jul 2014 23:47:10 +0200 Message-ID: <53B47DDE.7@6wind.com> References: <537327F1.4060603@6wind.com> <1404302346-4507-1-git-send-email-nicolas.dichtel@6wind.com> <87simj7ca1.fsf@x220.int.ebiederm.org> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, davem@davemloft.net, stephen@networkplumber.org To: "Eric W. Biederman" Return-path: Received: from mail-wi0-f182.google.com ([209.85.212.182]:44893 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754182AbaGBVrO (ORCPT ); Wed, 2 Jul 2014 17:47:14 -0400 Received: by mail-wi0-f182.google.com with SMTP id bs8so1230479wib.3 for ; Wed, 02 Jul 2014 14:47:13 -0700 (PDT) In-Reply-To: <87simj7ca1.fsf@x220.int.ebiederm.org> Sender: netdev-owner@vger.kernel.org List-ID: Le 02/07/2014 22:09, Eric W. Biederman a =C3=A9crit : > Nicolas Dichtel writes: > >> The goal of this serie is to be able to multicast netlink messages w= ith an >> attribute that identify a peer netns. >> This is needed by the userland to interpret some informations contai= ned in >> netlink messages (like IFLA_LINK value, but also some other attribut= es in case >> of x-netns netdevice (see also >> http://thread.gmane.org/gmane.linux.network/315933/focus=3D316064)). >> >> Each network namespaces allocates its own ids for other netns (inclu= ding >> itself). The user can retrieve these ids via a new netlink messages,= but only >> if he has a FD which points to this netns. Dump is not implemented s= o that a >> user cannot get the whole netns list. >> >> The goal of this RFC is mainly to validate the principle, ie patch 1= /5 and 2/5. >> Patch 3/5 and 4/5 shows an example of how to use these ids in rtnetl= ink >> messages. And patch 5/5 shows that the netlink messages can be symet= ric between >> a GET and a SET. > > This approach fundamentally breaks process migration, and calls for a > namespace of namespaces. Why does it call for a namespace of namespaces? Ids are different in ea= ch netns, because each netns has its own list id. Can you elaborate why it breaks the process migration? Do you think that identifying a netns from another netns is fundamental= ly wrong? Nicolas