From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next] ipv6: perform inetpeer binding at dst creation, with readonly option Date: Tue, 06 Mar 2012 16:05:28 -0500 (EST) Message-ID: <20120306.160528.1272258218296495399.davem@davemloft.net> References: <4F56320B.60400@network-box.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: nick.jones@network-box.com Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:39650 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031130Ab2CFVFx (ORCPT ); Tue, 6 Mar 2012 16:05:53 -0500 In-Reply-To: <4F56320B.60400@network-box.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Nick Jones Date: Tue, 06 Mar 2012 23:49:31 +0800 > A neighbour advertises itself as obsolete and at a later time, the host > sends solicitations to the neighbours direct address. The NS icmp6 > packets have hoplimit explicitly set to 255. > > The neighbour re-advertises itself. All subsequent packets sent to the > neighbour address will now have hoplimit stuck at 255 because the setup > of the NS packet wrote 255 to the cached metrics of the inetpeer that > the neighbour address' ip6_dst was bound to. If the neighbour was a > router, a RA that attempts to update the hoplimit for the route will > have no effect because of the way ip6_dst_hoplimit works. > > This patch adds an rt6_init_metrics method that is called shortly after > a call to ip6_dst_alloc, it performs the inetpeer binding at that time. > > It allows the caller to indicate whether they want the new ip6_dst > metrics, and thus the inetpeer metrics, to be writable. icmp6_dst_alloc > will now no longer permanently alter the peer metrics. > > Signed-off-by: Nick Jones So we essentially have two views of the same inetpeer. I would say that the real fix for this is to just use kmalloc'd metrics for these special icmp6 dsts and leave the rest of the code alone.