From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [RFC PATCH net-next 2/2] udp: add sk opt to allow sending pkt with src 0.0.0.0 Date: Thu, 14 Nov 2013 15:31:54 +0100 Message-ID: <20131114143154.GD26901@order.stressinduktion.org> References: <20131105205744.GK8832@order.stressinduktion.org> <1383958474-6255-1-git-send-email-nicolas.dichtel@6wind.com> <1383958474-6255-2-git-send-email-nicolas.dichtel@6wind.com> <20131111.001803.110603937316567461.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: nicolas.dichtel@6wind.com, netdev@vger.kernel.org, David.Laight@ACULAB.COM, jiri@resnulli.us, vyasevich@gmail.com, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, thaller@redhat.com, stephen@networkplumber.org To: David Miller Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:42882 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753503Ab3KNObz (ORCPT ); Thu, 14 Nov 2013 09:31:55 -0500 Content-Disposition: inline In-Reply-To: <20131111.001803.110603937316567461.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Nov 11, 2013 at 12:18:03AM -0500, David Miller wrote: > From: Nicolas Dichtel > Date: Sat, 9 Nov 2013 01:54:34 +0100 > > > This feature allows to a send packets with address source set to 0.0.0.0 even if > > an ip address is available on another interface. > > > > It's useful for DHCP client, to allow them to use UDP sockets and be compliant > > with the RFC2131, Section 4.1: > > > > 4.1 Constructing and sending DHCP messages > > ... > > DHCP messages broadcast by a client prior to that client obtaining > > its IP address must have the source address field in the IP header > > set to 0. > > > > Based on a previous work from > > Guillaume Gaudonville . > > > > Signed-off-by: Nicolas Dichtel > > This requirement of the RFC is inconsistent with a host based > addressing model, that which Linux employs, it assumes an interface > based one. > > The wording here is also very ambiguous. > > This RFC fails to even remotely consider what the right behavior > should be in a host based addressing environment at all, and anyone > reading this RFC should just accept that. > > Furthermore, the fact that you're implementing _addressing_ policy in > the UDP code makes this change even more unreasonable. I agree on this and will check how other operating systems which only use sockets do deal with that. Do you have an idea how to deal with the rp_filter issue if no ip address is set? Should we relax it in such cases? Greetings, Hannes