From patchwork Mon May 18 17:35:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 225695 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 48DB5C433E4 for ; Mon, 18 May 2020 18:12:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B23820715 for ; Mon, 18 May 2020 18:12:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589825566; bh=p+ja2vRe2GOEd4ER0sNd2TiM8cbguWj1RwJgbtZ5bCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2EjzV4OUE6bIgCyR6A06Jnzn63wOB7P+CvYAQdjw/p5C/nCTasKYJXHE3OI6vFD+9 JmPPYY+ZBufjLvQO6k5j8UFBtgfZYJktgYuy71lOuN3FRuk/JBzsZmCLIETsriTP6z utmmLpI0X78GzilmG3LaIzCq98UM5Iuw4wzBw+4Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732620AbgERSDM (ORCPT ); Mon, 18 May 2020 14:03:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:48288 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731507AbgERSDL (ORCPT ); Mon, 18 May 2020 14:03:11 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4FD34207F5; Mon, 18 May 2020 18:03:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824990; bh=p+ja2vRe2GOEd4ER0sNd2TiM8cbguWj1RwJgbtZ5bCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ThrXOwfqZF7e35t4JcBDEcZRloPebNQuAmzFxOtFjLbkrC7XJ06WFu3xN+dik3qSc doYyOUfXej0TnKPjXms9JqAVnZ47QyAsDYe/whNoeSChWoWP0yLNpy1E4cXpynrLtP QoCLNgHQd6z2Kgxhq7Yl4BTga6+HADKLN9ss/29E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Willem de Bruijn , Xin Long , Hannes Frederic Sowa , =?utf-8?q?Maciej_=C5=BBenczykowski?= , "David S. Miller" Subject: [PATCH 5.6 037/194] Revert "ipv6: add mtu lock check in __ip6_rt_update_pmtu" Date: Mon, 18 May 2020 19:35:27 +0200 Message-Id: <20200518173534.803818704@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173531.455604187@linuxfoundation.org> References: <20200518173531.455604187@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Maciej Żenczykowski" [ Upstream commit 09454fd0a4ce23cb3d8af65066c91a1bf27120dd ] This reverts commit 19bda36c4299ce3d7e5bce10bebe01764a655a6d: | ipv6: add mtu lock check in __ip6_rt_update_pmtu | | Prior to this patch, ipv6 didn't do mtu lock check in ip6_update_pmtu. | It leaded to that mtu lock doesn't really work when receiving the pkt | of ICMPV6_PKT_TOOBIG. | | This patch is to add mtu lock check in __ip6_rt_update_pmtu just as ipv4 | did in __ip_rt_update_pmtu. The above reasoning is incorrect. IPv6 *requires* icmp based pmtu to work. There's already a comment to this effect elsewhere in the kernel: $ git grep -p -B1 -A3 'RTAX_MTU lock' net/ipv6/route.c=4813= static int rt6_mtu_change_route(struct fib6_info *f6i, void *p_arg) ... /* In IPv6 pmtu discovery is not optional, so that RTAX_MTU lock cannot disable it. We still use this lock to block changes caused by addrconf/ndisc. */ This reverts to the pre-4.9 behaviour. Cc: Eric Dumazet Cc: Willem de Bruijn Cc: Xin Long Cc: Hannes Frederic Sowa Signed-off-by: Maciej Żenczykowski Fixes: 19bda36c4299 ("ipv6: add mtu lock check in __ip6_rt_update_pmtu") Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/route.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2725,8 +2725,10 @@ static void __ip6_rt_update_pmtu(struct const struct in6_addr *daddr, *saddr; struct rt6_info *rt6 = (struct rt6_info *)dst; - if (dst_metric_locked(dst, RTAX_MTU)) - return; + /* Note: do *NOT* check dst_metric_locked(dst, RTAX_MTU) + * IPv6 pmtu discovery isn't optional, so 'mtu lock' cannot disable it. + * [see also comment in rt6_mtu_change_route()] + */ if (iph) { daddr = &iph->daddr;