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=-10.0 required=3.0 tests=BAYES_00,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 BF3E6C433E7 for ; Mon, 20 Jul 2020 15:42:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AF342065E for ; Mon, 20 Jul 2020 15:42:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259757; bh=rFoy4+bilLHmpMG120DrVDDOAD844hgaxHpfK202y14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zR0OuhLKHv1gGM5yFGwoPKoLDAPZ+KEL0MfZnOs9bTOUmBpia8uPqsvVch92qypAA qFGuFDPd4q1GYyUrOgoUh7H9UM+aRu0EjiqRzOviTCOK+C9kPzipf+sMJHeWp9joUC TokXSAJd053MPX8ZAFfEnh5b1A7qkFrTyXS2qbVU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730106AbgGTPmg (ORCPT ); Mon, 20 Jul 2020 11:42:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:35530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729399AbgGTPme (ORCPT ); Mon, 20 Jul 2020 11:42:34 -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 F104F2065E; Mon, 20 Jul 2020 15:42:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259753; bh=rFoy4+bilLHmpMG120DrVDDOAD844hgaxHpfK202y14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1STfUrMpHbfJ+XyXGT9U/njHXZUBrnzx+OBh1KliEpLpfeswl+FIvqtFOVREDfo2w AQpBr3ivDZIWZa4Ow6ZtvT1TMAQALZjfDFKyOP7l25k+yjxdY3hO8ZTvDYL2aEhCXB o9ZEF553GA9wMJCERQD+6uxO/aRTFd8HERpwKUfE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Mathieu Desnoyers , "David S. Miller" Subject: [PATCH 4.9 37/86] tcp: md5: allow changing MD5 keys in all socket states Date: Mon, 20 Jul 2020 17:36:33 +0200 Message-Id: <20200720152755.030511978@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152753.138974850@linuxfoundation.org> References: <20200720152753.138974850@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 1ca0fafd73c5268e8fc4b997094b8bb2bfe8deea ] This essentially reverts commit 721230326891 ("tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets") Mathieu reported that many vendors BGP implementations can actually switch TCP MD5 on established flows. Quoting Mathieu : Here is a list of a few network vendors along with their behavior with respect to TCP MD5: - Cisco: Allows for password to be changed, but within the hold-down timer (~180 seconds). - Juniper: When password is initially set on active connection it will reset, but after that any subsequent password changes no network resets. - Nokia: No notes on if they flap the tcp connection or not. - Ericsson/RedBack: Allows for 2 password (old/new) to co-exist until both sides are ok with new passwords. - Meta-Switch: Expects the password to be set before a connection is attempted, but no further info on whether they reset the TCP connection on a change. - Avaya: Disable the neighbor, then set password, then re-enable. - Zebos: Would normally allow the change when socket connected. We can revert my prior change because commit 9424e2e7ad93 ("tcp: md5: fix potential overestimation of TCP option space") removed the leak of 4 kernel bytes to the wire that was the main reason for my patch. While doing my investigations, I found a bug when a MD5 key is changed, leading to these commits that stable teams want to consider before backporting this revert : Commit 6a2febec338d ("tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key()") Commit e6ced831ef11 ("tcp: md5: refine tcp_md5_do_add()/tcp_md5_hash_key() barriers") Fixes: 721230326891 "tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets" Signed-off-by: Eric Dumazet Reported-by: Mathieu Desnoyers Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2672,10 +2672,7 @@ static int do_tcp_setsockopt(struct sock #ifdef CONFIG_TCP_MD5SIG case TCP_MD5SIG: - if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) - err = tp->af_specific->md5_parse(sk, optval, optlen); - else - err = -EINVAL; + err = tp->af_specific->md5_parse(sk, optval, optlen); break; #endif case TCP_USER_TIMEOUT: