From patchwork Wed Apr 1 16:17:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 228405 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, 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 F39A2C2D0F3 for ; Wed, 1 Apr 2020 16:43:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DADE20658 for ; Wed, 1 Apr 2020 16:43:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585759426; bh=VqqyroAfWhyQOvnteSX/FAKaG6w+Qak3m5q11T6oLKM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UxaKCW6szBsTxMn5s0Od1yHckZPJ5ux2VTRcChZbIomfhfZpdJ0Vx/sAzEW4IkTsN nu16qF2tdWkKKwieSbFnA2hOxaCaW7T77QQ2++rAEyW/mtKWUs7h0//jEEiTafkZJi S/tL1gay7Gw83DLd+JJ1Ut/J+slXNDJztR6+uBpc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389651AbgDAQnm (ORCPT ); Wed, 1 Apr 2020 12:43:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:44562 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389650AbgDAQnl (ORCPT ); Wed, 1 Apr 2020 12:43:41 -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 E81D62063A; Wed, 1 Apr 2020 16:43:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585759421; bh=VqqyroAfWhyQOvnteSX/FAKaG6w+Qak3m5q11T6oLKM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fIfJYyBegzHN6gozLHT6GJPpg5IY/Gohq4OEXBjiSwPgUxV0TcBzC3a761FaNKrvi dejak29f/cyzG/VjJJLw9bkUbYVwnqe5AesEHiNfx95ceWBJSQqg4yCF7oNYOgV4X1 4Rzi+/xbrG1g9h9VCk91Pge7KZFR6hmSO9MMMngo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sabrina Dubroca , Stefano Brivio , "David S. Miller" , Sasha Levin Subject: [PATCH 4.14 073/148] net: ipv4: dont let PMTU updates increase route MTU Date: Wed, 1 Apr 2020 18:17:45 +0200 Message-Id: <20200401161600.427535721@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200401161552.245876366@linuxfoundation.org> References: <20200401161552.245876366@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: Sabrina Dubroca [ Upstream commit 28d35bcdd3925e7293408cdb8aa5f2aac5f0d6e3 ] When an MTU update with PMTU smaller than net.ipv4.route.min_pmtu is received, we must clamp its value. However, we can receive a PMTU exception with PMTU < old_mtu < ip_rt_min_pmtu, which would lead to an increase in PMTU. To fix this, take the smallest of the old MTU and ip_rt_min_pmtu. Before this patch, in case of an update, the exception's MTU would always change. Now, an exception can have only its lock flag updated, but not the MTU, so we need to add a check on locking to the following "is this exception getting updated, or close to expiring?" test. Fixes: d52e5a7e7ca4 ("ipv4: lock mtu in fnhe when received PMTU < net.ipv4.route.min_pmtu") Signed-off-by: Sabrina Dubroca Reviewed-by: Stefano Brivio Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/route.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8b855d3eec9e7..05fe1d0075444 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1014,21 +1014,22 @@ out: kfree_skb(skb); static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) { struct dst_entry *dst = &rt->dst; + u32 old_mtu = ipv4_mtu(dst); struct fib_result res; bool lock = false; if (ip_mtu_locked(dst)) return; - if (ipv4_mtu(dst) < mtu) + if (old_mtu < mtu) return; if (mtu < ip_rt_min_pmtu) { lock = true; - mtu = ip_rt_min_pmtu; + mtu = min(old_mtu, ip_rt_min_pmtu); } - if (rt->rt_pmtu == mtu && + if (rt->rt_pmtu == mtu && !lock && time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2)) return;