From patchwork Fri Oct 9 17:00:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 299182 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=-14.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 176DEC43457 for ; Fri, 9 Oct 2020 17:01:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D81F72225F for ; Fri, 9 Oct 2020 17:01:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hGGk9QV7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390036AbgJIRBz (ORCPT ); Fri, 9 Oct 2020 13:01:55 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:20082 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390015AbgJIRBq (ORCPT ); Fri, 9 Oct 2020 13:01:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602262905; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k3vedgNXsnPTRd8uDisAy0AqNRztast98ievxR3PENM=; b=hGGk9QV7LnG/DUmMZfvwQ/DDFNVA0UCtCbPyo+N3yCs17Z2YrY7g5yzKv4tk1sGvrE/mIK LLPXYx+vF6XENy9NEc4lvjRLv0EHTYtHTIh6/5yMRE0c4z/6PUrlSQC4xHelOhRodO9Yl2 CtKdT4MgM7R57t6Yf/GoY1Iz53zsB+U= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-108-z7MgUgq3NxOufN1UyLXTlQ-1; Fri, 09 Oct 2020 13:01:39 -0400 X-MC-Unique: z7MgUgq3NxOufN1UyLXTlQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 584BC1084D87; Fri, 9 Oct 2020 17:01:17 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-114-111.ams2.redhat.com [10.36.114.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2728D76642; Fri, 9 Oct 2020 17:01:15 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , mptcp@lists.01.org Subject: [PATCH net 1/2] mptcp: fix fallback for MP_JOIN subflows Date: Fri, 9 Oct 2020 19:00:00 +0200 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Additional/MP_JOIN subflows that do not pass some initial handshake tests currently causes fallback to TCP. That is an RFC violation: we should instead reset the subflow and leave the the msk untouched. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/91 Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests") Reviewed-by: Mat Martineau Signed-off-by: Paolo Abeni --- net/mptcp/options.c | 32 +++++++++++++++++++++++++------- net/mptcp/protocol.h | 1 + net/mptcp/subflow.c | 10 ++++++++-- 3 files changed, 34 insertions(+), 9 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 888bbbbb3e8a..277f12633fc9 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -626,6 +626,12 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, if (unlikely(mptcp_check_fallback(sk))) return false; + /* prevent adding of any MPTCP related options on reset packet + * until we support MP_TCPRST/MP_FASTCLOSE + */ + if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) + return false; + if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts)) ret = true; else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining, @@ -676,7 +682,7 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, return false; } -static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, +static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, struct mptcp_subflow_context *subflow, struct sk_buff *skb, struct mptcp_options_received *mp_opt) @@ -693,15 +699,20 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && subflow->mp_join && mp_opt->mp_join && READ_ONCE(msk->pm.server_side)) - tcp_send_ack(sk); + tcp_send_ack(ssk); goto fully_established; } - /* we should process OoO packets before the first subflow is fully - * established, but not expected for MP_JOIN subflows + /* we must process OoO packets before the first subflow is fully + * established. OoO packets are instead a protocol violation + * for MP_JOIN subflows as the peer must not send any data + * before receiving the forth ack - cfr. RFC 8684 section 3.2. */ - if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) + if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { + if (subflow->mp_join) + goto reset; return subflow->mp_capable; + } if (mp_opt->dss && mp_opt->use_ack) { /* subflows are fully established as soon as we get any @@ -713,9 +724,12 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, } /* If the first established packet does not contain MP_CAPABLE + data - * then fallback to TCP + * then fallback to TCP. Fallback scenarios requires a reset for + * MP_JOIN subflows. */ if (!mp_opt->mp_capable) { + if (subflow->mp_join) + goto reset; subflow->mp_capable = 0; pr_fallback(msk); __mptcp_do_fallback(msk); @@ -732,12 +746,16 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, subflow->pm_notified = 1; if (subflow->mp_join) { - clear_3rdack_retransmission(sk); + clear_3rdack_retransmission(ssk); mptcp_pm_subflow_established(msk, subflow); } else { mptcp_pm_fully_established(msk); } return true; + +reset: + mptcp_subflow_reset(ssk); + return false; } static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 20f04ac85409..0a6e5b3f6ae8 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -348,6 +348,7 @@ void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow, struct mptcp_options_received *mp_opt); bool mptcp_subflow_data_available(struct sock *sk); void __init mptcp_subflow_init(void); +void mptcp_subflow_reset(struct sock *ssk); /* called with sk socket lock held */ int __mptcp_subflow_connect(struct sock *sk, int ifindex, diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 6f035af1c9d2..b1b8028730bf 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -270,6 +270,13 @@ static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) return thmac == subflow->thmac; } +void mptcp_subflow_reset(struct sock *ssk) +{ + tcp_set_state(ssk, TCP_CLOSE); + tcp_send_active_reset(ssk, GFP_ATOMIC); + tcp_done(ssk); +} + static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) { struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); @@ -342,8 +349,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) return; do_reset: - tcp_send_active_reset(sk, GFP_ATOMIC); - tcp_done(sk); + mptcp_subflow_reset(sk); } struct request_sock_ops mptcp_subflow_request_sock_ops;