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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 792E9C433E0 for ; Wed, 13 Jan 2021 01:52:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 399072310A for ; Wed, 13 Jan 2021 01:52:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726929AbhAMBvX (ORCPT ); Tue, 12 Jan 2021 20:51:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbhAMBvW (ORCPT ); Tue, 12 Jan 2021 20:51:22 -0500 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE3E8C0617A5; Tue, 12 Jan 2021 17:50:41 -0800 (PST) Received: by mail-pf1-x433.google.com with SMTP id m6so266093pfk.1; Tue, 12 Jan 2021 17:50:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=lVMcs8UX05yYXnv8U8ZRWy0QX2Aplqzdx81ZhiBh7Rg=; b=YSrS63qemmiLiixU+9VJW7ig6DvBllC70+EwxvUTHxHvABJQI7xoO5KhU//Ft86i+T gR1wNiUxIxadrz6NaT3D2Yq8yNjByMD47EJkrhi8jBLt/UboGUhqCsPz0brvudDVv3oG w3rm5kAtE/aOb1AqlMZRfc1vEYIwGNvgKDkHB622O3j3L59LqaDHxV16QhbO6Rfx5Tah 7iDbrnNZHyjoEIk0VyAk8O3vWp3+KHR6HD4YLJ3N/OCeRpfoFDok4w7vXxKnbxBXFfLQ 2rxCKxW0PW23LeIzenJCyhKeGGFrtiLvQIjY/JKH3WtnlEyR1tbuI62k3RCTgr9p7te6 QI4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=lVMcs8UX05yYXnv8U8ZRWy0QX2Aplqzdx81ZhiBh7Rg=; b=eg89Z1yKzmSC3mXBXny/UzecSnFhNYJyye5gMKOIOJA2dg5aaPZ7AbH1aqAryNBdUE uqtGRuyqj+rZofEhvm+uCesDgfohD9m1rY5w2yO3ZiULBiVvunAQBvkBUxZ2S8wypZlC /saqX8JbATN1Mx337CLS5OX+HjLy94B3RH/n0HzRb6hThnqfACxWTYr5p/P1ZdtO6245 uZoOou1OHvtcgLj/23+bw3ey2I5i7Z/mpdCEaS9gYgbWAegdXY+0oZGpPuQ+frwN81h9 5Y7HUIxnQuSQNaA3mziUsPuvKeKFWpRaAh8ToLGNK4BGzIewSFXeGnNrUesS8FZAezai jctg== X-Gm-Message-State: AOAM530LqpY4o7AX/Kd1em9jeSdZOpVcFQakcVQeRT835jcR3yGOPtuR R/Jta9c+g6egvYD56PjtZp8y6/Dio+V4 X-Google-Smtp-Source: ABdhPJwTz97VyacaNkUBhukAr/6SlYHlN8opCDa4IIoJbI8KKVvtHMQfGKBcVgLgxtjeH5FoFS4GOg== X-Received: by 2002:a65:50c8:: with SMTP id s8mr2028437pgp.68.1610502641398; Tue, 12 Jan 2021 17:50:41 -0800 (PST) Received: from localhost.localdomain ([216.52.21.4]) by smtp.gmail.com with ESMTPSA id a18sm388345pfg.107.2021.01.12.17.50.40 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Jan 2021 17:50:40 -0800 (PST) From: Praveen Chaudhary X-Google-Original-From: Praveen Chaudhary To: 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 Subject: [PATCH v1 net-next 0/1] Allow user to set metric on default route learned via Router Advertisement. Date: Tue, 12 Jan 2021 17:50:35 -0800 Message-Id: <20210113015036.17674-1-pchaudhary@linkedin.com> X-Mailer: git-send-email 2.29.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allow user to set metric on default route learned via Router Advertisement. Note: RFC 4191 does not say anything for metric for IPv6 default route. Fix: For IPv4, default route is learned via DHCPv4 and user is allowed to change metric using config in 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. Logs: ---------------------------------------------------------------- For IPv4: ---------------------------------------------------------------- Config in etc/network/interfaces ---------------------------------------------------------------- ``` auto eth0 iface eth0 inet dhcp metric 4261413864 ``` IPv4 Kernel Route Table: ---------------------------------------------------------------- ``` $ sudo route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.11.44.1 0.0.0.0 UG -33553432 0 0 eth0 ``` 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, 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.accept_ra_defrtr_metric=0x770003e9 ``` IP monitor: ---------------------------------------------------------------- ``` default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705 pref high ``` Kernel IPv6 routing table ---------------------------------------------------------------- ``` Destination Next Hop Flag Met Ref Use If ::/0 fe80::xx16:xxxx:feb3:ce8e UGDAe 1996489705 0 0 eth0 ``` 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 IPv6 RA is received, because the default route must be fully controlled by RA msg. ``` admin@lnos-x1-a-asw03:~$ sudo sysctl -w net.ipv6.conf.eth0.accept_ra_defrtr_metric=0x770003e8 net.ipv6.conf.eth0.accept_ra_defrtr_metric = 0x770003e8 ``` IP monitor: when metric is changed after learning Default Route from previous IPv6 RA msg: ``` 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 ``` Praveen Chaudhary (1): Allow user to set metric on default route learned via Router Advertisement. Documentation/networking/ip-sysctl.rst | 18 ++++++++++++++++++ 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 | 10 ++++++++++ net/ipv6/ndisc.c | 14 ++++++++++---- net/ipv6/route.c | 5 +++-- 8 files changed, 46 insertions(+), 7 deletions(-) base-commit: 139711f033f636cc78b6aaf7363252241b9698ef -- 2.29.0