From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH iproute2] ip route: broken logic when using default word and family not specified Date: Sat, 16 Dec 2017 13:21:15 -0800 Message-ID: <20171216132115.7d924d8d@xeon-e3> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Alexander Zubkov Return-path: Received: from mail-pg0-f54.google.com ([74.125.83.54]:43757 "EHLO mail-pg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756877AbdLPVVS (ORCPT ); Sat, 16 Dec 2017 16:21:18 -0500 Received: by mail-pg0-f54.google.com with SMTP id b18so7663942pgv.10 for ; Sat, 16 Dec 2017 13:21:18 -0800 (PST) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Sat, 18 Nov 2017 14:12:48 +0100 Alexander Zubkov wrote: > Hello, > > I have found odd behaviour when using "ip route list" (and other bound > commands) with prefix "default". > > When family not specified, its value is completely ignored and "ip > route list default" shows all inet4 prefixes. Same do "ip route list > exact default" and "ip route list match default". Examples are at the > end of the message. > > When family is specified, the behaviour changes and default works as > expected (=0.0.0.0/0 for inet4 and =::/0 for inet6). The above > commands all shows only default prefix in the output and only "root > default" shows all prefixes. > > I tried to dig into the code and found that when default is using with > unspecified family - the resulting structures filter.[mr]dst will > actually become all-zeroes as in the case when nothing is specified. > > I propose to change this in such a way (see attached patch). When > default prefix is parsed, the flag PREFIXLEN_SPECIFIED is attached to > it too, like for prefixes with "/". It seems logical to me, > because "/0" is really implied by "default" and even directly set up > in the code: > > dst->bitlen = 0; > > Then during filtering there is additional logic for unspecified family > and specified prefix. > > With this patch ip route list commands shown above are working as > expected. And it also works with unspecified table when routes are > printed from different families. > > Examples after applying the patch: > > # ./ip route list > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > 192.168.1.0/24 via 192.168.0.3 dev eth0 > # ./ip -6 route list > fe80::/64 dev eth0 proto kernel metric 256 pref medium > fe80:1::/64 via fe80::3 dev eth0 metric 1024 pref medium > default via fe80::2 dev eth0 metric 1024 pref medium > # ./ip route list default > default via 192.168.0.2 dev eth0 > # ./ip route list exact default > default via 192.168.0.2 dev eth0 > # ./ip route list match default > default via 192.168.0.2 dev eth0 > # ./ip route list root default > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > 192.168.1.0/24 via 192.168.0.3 dev eth0 > # ./ip route list default table all > default via 192.168.0.2 dev eth0 > unreachable default dev lo proto kernel metric 4294967295 error -101 pref medium > default via fe80::2 dev eth0 metric 1024 pref medium > unreachable default dev lo proto kernel metric 4294967295 error -101 pref medium > unreachable default dev lo proto kernel metric 4294967295 error -101 pref medium > # ./ip route list root default table all > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > ... > ff00::/8 dev eth0 table local metric 256 pref medium > unreachable default dev lo proto kernel metric 4294967295 error -101 pref medium > > And before patch: > > # ip route list default > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > 192.168.1.0/24 via 192.168.0.3 dev eth0 > # ip route list match default > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > 192.168.1.0/24 via 192.168.0.3 dev eth0 > # ip route list exact default > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > 192.168.1.0/24 via 192.168.0.3 dev eth0 > # ip -4 route list exact default > default via 192.168.0.2 dev eth0 > # ip -6 route list exact default > default via fe80::2 dev eth0 metric 1024 > # ip route list exact default table all > default via 192.168.0.2 dev eth0 > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.1 > ... > local fe80::3c09:19ff:feee:9866 dev lo table local proto none metric 0 > ff00::/8 dev eth0 table local metric 256 > unreachable default dev lo table unspec proto kernel metric > 4294967295 error -101 I think this is fine, and see no problem. The patch is missing 'Signed-off-by' line which is required for iproute2; the overall rules for iproute2 are (mostly) the same as the kernel. Please resubmit with Signed-off-by