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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 5D2EAC49361 for ; Tue, 8 Jun 2021 19:13:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A4A5613AC for ; Tue, 8 Jun 2021 19:13:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238474AbhFHTPF (ORCPT ); Tue, 8 Jun 2021 15:15:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:40012 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237121AbhFHTEO (ORCPT ); Tue, 8 Jun 2021 15:04:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F04D461352; Tue, 8 Jun 2021 18:45:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623177959; bh=e7tfVzAIhSE1lqXwp9d2grNhkhxH/7cdTqBQYWGu11Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qaQBvovUwPgW5E4jTI5HxkqqVTDWZqvebVwRJakkEyOLy+WQk5dza7wYCCWFsyw1J pTS/oMj1LwnvvgyGL08tBuYFIxz8yCV/4qKv0oPtrxkrA1bAXM3agtwhm9qkRLFVNt tjC1vqFbtf3AorXBZMt/XFdXpGNECwFCR6e6BnNc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthieu Baerts , Paolo Abeni , Mat Martineau , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.12 025/161] mptcp: always parse mptcp options for MPC reqsk Date: Tue, 8 Jun 2021 20:25:55 +0200 Message-Id: <20210608175946.301772230@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210608175945.476074951@linuxfoundation.org> References: <20210608175945.476074951@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Paolo Abeni [ Upstream commit 06f9a435b3aa12f4de6da91f11fdce8ce7b46205 ] In subflow_syn_recv_sock() we currently skip options parsing for OoO packet, given that such packets may not carry the relevant MPC option. If the peer generates an MPC+data TSO packet and some of the early segments are lost or get reorder, we server will ignore the peer key, causing transient, unexpected fallback to TCP. The solution is always parsing the incoming MPTCP options, and do the fallback only for in-order packets. This actually cleans the existing code a bit. Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option") Reported-by: Matthieu Baerts Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/mptcp/subflow.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 1936db3574d2..8878317b4386 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -608,21 +608,20 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, /* if the sk is MP_CAPABLE, we try to fetch the client key */ if (subflow_req->mp_capable) { - if (TCP_SKB_CB(skb)->seq != subflow_req->ssn_offset + 1) { - /* here we can receive and accept an in-window, - * out-of-order pkt, which will not carry the MP_CAPABLE - * opt even on mptcp enabled paths - */ - goto create_msk; - } - + /* we can receive and accept an in-window, out-of-order pkt, + * which may not carry the MP_CAPABLE opt even on mptcp enabled + * paths: always try to extract the peer key, and fallback + * for packets missing it. + * Even OoO DSS packets coming legitly after dropped or + * reordered MPC will cause fallback, but we don't have other + * options. + */ mptcp_get_options(skb, &mp_opt); if (!mp_opt.mp_capable) { fallback = true; goto create_child; } -create_msk: new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req); if (!new_msk) fallback = true; -- 2.30.2