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=ham 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 A1BF9C433DB for ; Wed, 30 Dec 2020 08:47:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74620207A9 for ; Wed, 30 Dec 2020 08:47:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726529AbgL3Irj (ORCPT ); Wed, 30 Dec 2020 03:47:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726348AbgL3Iri (ORCPT ); Wed, 30 Dec 2020 03:47:38 -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 5993DC061799; Wed, 30 Dec 2020 00:46:58 -0800 (PST) Received: by mail-pf1-x433.google.com with SMTP id f9so9361922pfc.11; Wed, 30 Dec 2020 00:46:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id; bh=4hCJ1uMJpAFhFUoq0+DB5gxgdyiGzPgLXZHVoajEEEA=; b=PHm5ofpjbWbsoLGYwa9L10tOUovyRO/uI6H5ddbo36wgCesQ7mcCy2z3oBMiUEaf3/ 5Mc0kNcQk8jyewpciwrxPxJ5bgppu2LydQFqLUieJPndZtHr/bgH4raxv0RX+7sdlxcp 38BDnO6xoVzWIMbVYYfKNNUw0KSMSMraT0jur/NJB+YPnqXsvcXZMQB7wc3p+DXjkf0B sg44yNm4lr6KHxZ/Cy+1db3DgaR3CNCnOETlOnJgPgwD3XAlN86C/9iO17DVM8XwRq4o nZFvz/KntWpSba/IddB2VFM9A3Fjklaem/GsXSV03N+GgkLCWEBVyTYTcu5YFK+hWfqJ dpJA== 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; bh=4hCJ1uMJpAFhFUoq0+DB5gxgdyiGzPgLXZHVoajEEEA=; b=NvML41CRfy7AohAAnzgeu9f/p6sUmLp/r86HU7/YnhiXJ85XdVVkHQJBUPPihuQ1Uh nJ7NhdLCpmDi4q6H+v6X4Aa7K7phg0sVpklBDMItugDn06rds8cCY8D2IdJL+KLtceVJ UpEBx+27dBVGlsFo+pGwZ8CwdKw874NfbkqC/l91BLniPZ4xQXlbaoW/x43i97RD2yvm OsCvjtVGLfBvlKSz+VgQJkSgpcseO4D3GMLkJPr6Osi+ZcYkrPxtD61kE686pUP4gyee to34sqR8i28OpXywNGZuRJ4tGx/809wj0U0Ox2piDEf/SaUod+dSoeCdiYH+BQ5QUTbL +1MA== X-Gm-Message-State: AOAM531bc4WTg1l8ewXIJDKWrDAHAZsg73N6cNUyHz/G5nFYkIXfaOdC 3oChq0mDgFQo5Qj3aVUbJgfjXIgbJw== X-Google-Smtp-Source: ABdhPJwcsakYdfFcFOfWAxfpjWtQAy1hsG9kYylK6U1z+W9dz0HstcNWGR26ZyKh7ZHxUq2BPHRlyw== X-Received: by 2002:a63:8f4c:: with SMTP id r12mr51411688pgn.311.1609318017913; Wed, 30 Dec 2020 00:46:57 -0800 (PST) Received: from localhost.localdomain ([216.52.21.4]) by smtp.gmail.com with ESMTPSA id 22sm41936113pfn.190.2020.12.30.00.46.56 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Dec 2020 00:46:57 -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] Allow user to set metric on default route learned via Router Advertisement. Date: Wed, 30 Dec 2020 00:46:43 -0800 Message-Id: <1609318004-12709-1-git-send-email-pchaudhary@linkedin.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allow user to set metric on default route learned via Router Advertisement. Not: 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 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 default route is learned via routing protocol too. ---------------------------------------------------------------- ``` # show ip 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::be16:65ff:feb3:ce8e dev eth0 proto ra metric 1996489705 pref high ``` Kernel IPv6 routing table ---------------------------------------------------------------- ``` Destination Next Hop Flag Met Ref Use If ::/0 fe80::be16:65ff:feb3:ce8e UGDAe 1996489705 0 0 eth0 ``` FRR Routing Table, if default route is learned via routing protocol. ---------------------------------------------------------------- # show ipv6 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::be16:65ff:feb3:ce8e, eth0, 6d07h43m ---------------------------------------------------------------- Praveen Chaudhary (1): Allow user to set metric on default route learned via Router Advertisement. Documentation/networking/ip-sysctl.rst | 8 ++++++++ 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 | 15 +++++++++++---- net/ipv6/route.c | 8 +++++--- 8 files changed, 39 insertions(+), 8 deletions(-) -- 2.7.4