From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F314DC433DB for ; Tue, 26 Jan 2021 19:38:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C210F22B2C for ; Tue, 26 Jan 2021 19:38:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388197AbhAZFjf (ORCPT ); Tue, 26 Jan 2021 00:39:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732115AbhAZDfj (ORCPT ); Mon, 25 Jan 2021 22:35:39 -0500 Received: from mail-oi1-x230.google.com (mail-oi1-x230.google.com [IPv6:2607:f8b0:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB531C06174A; Mon, 25 Jan 2021 19:34:58 -0800 (PST) Received: by mail-oi1-x230.google.com with SMTP id x71so17133741oia.9; Mon, 25 Jan 2021 19:34:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=loohkZAKsZDbkdCoMUXlVDMNQHJ6H2P6HeBaC1bU6Ik=; b=FvjOcmkQnig6wqaFE0vVvA4SfhS35ilbcU9GvrL1i8uwn9pMAsv57VDLh2gAsiTe0B 7IB+xV7vcbb/77nkBmYVDYqC35uxGzcXumd+hvCkYbRuKtPfEnxDrN0yai1u/SLuhEee Vscrfz7JG/HSsPu5a8FbrKzae7nlzgE+Ss23NXIaknsWUQEHZsfhscKfKQx0Vm9FIsMd rOxT1LLjNQH42D7TBo1F+MQfDh9ieOHBxpl3JVhXPiNJRa2UTGs4LB6Q8DYOd8MRbqPP WjpelirF64C8rx7S8Lig7RRG8WO8/cMjgK7TKdd70SxrUFjLZKsWrpeOHFBzH2baO4TX jwjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=loohkZAKsZDbkdCoMUXlVDMNQHJ6H2P6HeBaC1bU6Ik=; b=BykWLPpejThdIX3xG0uv4qhSR9AGVGrPKDU415CY5ZGwSr1lbbLY0GOk8OCXBYcx3S rSeBd6WnrPc/vB6XY9GJtvfL+P9xvTsjsLzrIWaHSZSyWg1XLuL6xI9yhMSX6qN9gQYp 2PEfq45SnTeyqFkxzrpBKXKnPEDnxPN0qxcxrx1DmEmsIG3b4ZSZ5WVm+1aiCwbzzmq5 6X7wqtUO6S90We/0BuWRxxP8bUufwLmYLG7PDDu+Jp8vpYYaIscU/XF2YXjPYfQWoBk/ IWRzAPn1HY6zd+a0BXbQNaW1jZdYLgAsOlA3pmIvgQ+akvrUvp80XdAOssAU/Ox8Va4K 3v4Q== X-Gm-Message-State: AOAM531Ifa6zkm2Rv6q6fLDaWgR8dcO3NvZecpi0QofCf68gdwPQt+H/ BVJ01lecSzDOlpiq61qBMCE= X-Google-Smtp-Source: ABdhPJxkre9Bvv2KxaUHEbRKlOwTJUMYFF6OgPmIFYpdWP36nVjKV/0ZUHQ/Z7V6OH5GHYBLVH6k8Q== X-Received: by 2002:aca:f382:: with SMTP id r124mr1978802oih.175.1611632098343; Mon, 25 Jan 2021 19:34:58 -0800 (PST) Received: from Davids-MacBook-Pro.local ([2601:282:800:dc80:f5f4:6dbf:d358:29ee]) by smtp.googlemail.com with ESMTPSA id v2sm2129201ooq.25.2021.01.25.19.34.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Jan 2021 19:34:57 -0800 (PST) Subject: Re: [PATCH v4 net-next 1/1] Allow user to set metric on default route learned via Router Advertisement. To: Praveen Chaudhary , davem@davemloft.net, kuba@kernel.org, corbet@lwn.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zhenggen Xu , David Ahern References: <20210125214430.24079-1-pchaudhary@linkedin.com> From: David Ahern Message-ID: <21884a37-ee26-3c8c-690e-9ea29d77d8b9@gmail.com> Date: Mon, 25 Jan 2021 20:34:56 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210125214430.24079-1-pchaudhary@linkedin.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 1/25/21 2:44 PM, Praveen Chaudhary wrote: > For IPv4, default route is learned via DHCPv4 and user is allowed to change > metric using config etc/network/interfaces. But for IPv6, default route can > be learned via RA, for which, currently a fixed metric value 1024 is used. > > Ideally, user should be able to configure metric on default route for IPv6 > similar to IPv4. This fix adds sysctl for the same. > > Signed-off-by: Praveen Chaudhary > Signed-off-by: Zhenggen Xu > > Reviewed-by: David Ahern > > Changes in v1. > 1.) Correct the call to rt6_add_dflt_router. > > Changes in v2. > 1.) Replace accept_ra_defrtr_metric to ra_defrtr_metric. > 2.) Change Type to __u32 instead of __s32. > 3.) Change description in Documentation/networking/ip-sysctl.rst. > 4.) Use proc_douintvec instead of proc_dointvec. > 5.) Code style in ndisc_router_discovery(). > 6.) Change Type to u32 instead of unsigned int. > > Changes in v3: > 1.) Removed '---' and '```' from description. > 2.) Remove stray ' after accept_ra_defrtr. > 3.) Fix tab in net/ipv6/addrconf.c. > > Changes in v4: > 1.) Remove special case of 0 and use IP6_RT_PRIO_USER as default. > 2.) Do not allow 0. > 3.) Change Documentation accordingly. > 4.) Remove extra brackets and compare with zero in ndisc_router_discovery(). > 5.) Remove compare with zero in rt6_add_dflt_router(). > > Logs: > > For IPv4: > > Config in etc/network/interfaces: > auto eth0 > iface eth0 inet dhcp > metric 4261413864 > > IPv4 Kernel Route Table: > $ ip route list > default via 172.21.47.1 dev eth0 metric 4261413864 > > FRR Table, if a static route is configured: > [In real scenario, it is useful to prefer BGP learned default route over DHCPv4 default route.] > Codes: K - kernel route, C - connected, S - static, R - RIP, > O - OSPF, I - IS-IS, B - BGP, P - PIM, E - EIGRP, N - NHRP, > T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP, > > - selected route, * - FIB route > > S>* 0.0.0.0/0 [20/0] is directly connected, eth0, 00:00:03 > K 0.0.0.0/0 [254/1000] via 172.21.47.1, eth0, 6d08h51m > > i.e. User can prefer Default Router learned via Routing Protocol in IPv4. > Similar behavior is not possible for IPv6, without this fix. > > After fix [for IPv6]: > sudo sysctl -w net.ipv6.conf.eth0.net.ipv6.conf.eth0.ra_defrtr_metric=1996489705 > > IP monitor: [When IPv6 RA is received] > default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705 pref high > > Kernel IPv6 routing table > $ ip -6 route list > default via fe80::be16:65ff:feb3:ce8e dev eth0 proto ra metric 1996489705 expires 21sec hoplimit 64 pref high > > FRR Table, if a static route is configured: > [In real scenario, it is useful to prefer BGP learned default route over IPv6 RA default route.] > Codes: K - kernel route, C - connected, S - static, R - RIPng, > O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table, > v - VNC, V - VNC-Direct, A - Babel, D - SHARP, > > - selected route, * - FIB route > > S>* ::/0 [20/0] is directly connected, eth0, 00:00:06 > K ::/0 [119/1001] via fe80::xx16:xxxx:feb3:ce8e, eth0, 6d07h43m > > If the metric is changed later, the effect will be seen only when next IPv6 > RA is received, because the default route must be fully controlled by RA msg. > Below metric is changed from 1996489705 to 1996489704. > > $ sudo sysctl -w net.ipv6.conf.eth0.ra_defrtr_metric=1996489704 > net.ipv6.conf.eth0.ra_defrtr_metric = 1996489704 > > IP monitor: > [On next IPv6 RA msg, Kernel deletes prev route and installs new route with updated metric] > > Deleted default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705  expires 3sec hoplimit 64 pref high > default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489704  pref high > --- > Documentation/networking/ip-sysctl.rst | 10 ++++++++++ > include/linux/ipv6.h | 1 + > include/net/ip6_route.h | 3 ++- > include/uapi/linux/ipv6.h | 1 + > include/uapi/linux/sysctl.h | 1 + > net/ipv6/addrconf.c | 11 +++++++++++ > net/ipv6/ndisc.c | 12 ++++++++---- > net/ipv6/route.c | 5 +++-- > 8 files changed, 37 insertions(+), 7 deletions(-) > Reviewed-by: David Ahern