From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH net-next] net: ipv6: put host and anycast routes on device with address Date: Thu, 17 Aug 2017 10:56:54 -0600 Message-ID: <3b4eb556-a25b-75a8-9d29-1974607044cf@gmail.com> References: <1502923076-12292-1-git-send-email-dsahern@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: yoshfuji@linux-ipv6.org, hannes@stressinduktion.org To: netdev@vger.kernel.org, David Miller Return-path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:34761 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751943AbdHQQ5B (ORCPT ); Thu, 17 Aug 2017 12:57:01 -0400 Received: by mail-pg0-f67.google.com with SMTP id y192so10756084pgd.1 for ; Thu, 17 Aug 2017 09:57:01 -0700 (PDT) In-Reply-To: <1502923076-12292-1-git-send-email-dsahern@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On 8/16/17 4:37 PM, David Ahern wrote: > One nagging difference between ipv4 and ipv6 is host routes for ipv6 > addresses are installed using the loopback device or VRF / L3 Master > device. e.g., > > 2001:db8:1::/120 dev veth0 proto kernel metric 256 pref medium > local 2001:db8:1::1 dev lo table local proto kernel metric 0 pref medium > > Using the loopback device is convenient -- necessary for local tx, but > has some nasty side effects, most notably setting the 'lo' device down > causes all host routes for all local IPv6 address to be removed from the > FIB and completely breaks IPv6 networking across all interfaces. > > This patch puts FIB entries for IPv6 routes against the device. This > simplifies the routes in the FIB, for example by making dst->dev and > rt6i_idev->dev the same (a future patch can look at removing the device > reference taken for rt6i_idev for FIB entries). For example: > > $ ip -6 r ls table all | grep veth1 > 2001:db8:99::/120 dev veth1 proto kernel metric 256 pref medium > anycast 2001:db8:99:: dev veth1 table local proto kernel metric 0 pref medium > local 2001:db8:99::1 dev veth1 table local proto kernel metric 0 pref medium > > When copies are made on FIB lookups, the cloned route has dst->dev > set to loopback (or the L3 master device). This is needed for the > local Tx of packets to local addresses. > > With fib entries allocated against the real network device, the addrconf > code that reinserts host routes on admin up of 'lo' is no longer needed. > > Signed-off-by: David Ahern > --- > net/ipv6/addrconf.c | 42 ------------------------------------------ > net/ipv6/route.c | 46 ++++++++++++++++++++++++++++++++++------------ > 2 files changed, 34 insertions(+), 54 deletions(-) > DaveM: please drop this one. I found a use case that is failing: UDP packets to a local linklocal address with no server are not getting the ICMP unreachable. Will send a v2 when tests complete.