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[2604:1380:1:3600::1]) by mx.google.com with ESMTPS id 16si9608454qka.757.2022.02.02.17.03.58 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Feb 2022 17:03:58 -0800 (PST) Received-SPF: pass (google.com: domain of mptcp+bounces-3414-wpasupplicant.patchew=gmail.com@lists.linux.dev designates 2604:1380:1:3600::1 as permitted sender) client-ip=2604:1380:1:3600::1; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=F1hwAjsI; spf=pass (google.com: domain of mptcp+bounces-3414-wpasupplicant.patchew=gmail.com@lists.linux.dev designates 2604:1380:1:3600::1 as permitted sender) smtp.mailfrom="mptcp+bounces-3414-wpasupplicant.patchew=gmail.com@lists.linux.dev"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ewr.edge.kernel.org (Postfix) with ESMTPS id 609AC1C0DD5 for ; Thu, 3 Feb 2022 01:03:58 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 319EF2F43; Thu, 3 Feb 2022 01:03:55 +0000 (UTC) X-Original-To: mptcp@lists.linux.dev Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA1852F27 for ; Thu, 3 Feb 2022 01:03:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643850232; x=1675386232; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Lx38d9fhYiCL1gyKi+5TqLDwjarXqB2FJolRnno2uwY=; b=F1hwAjsIJ8huaKGwpbc8i09QewFL96AXS7nBdt1lWeS1BNHKe7n3F7fx 5vPXs+mYNOTMdPGQS52DnTWrvvmjdcjxZo2bZuFKnj+/SdBHRQfF7iByR a5NIXXWkh+2igh3v+KQBcmcS3ETZyPNyYb6xyjl2pAm0nVPVAAzJEqlr6 BmxUk8twJPKFN78xlq9JtEZVBNFmiOtt8hxfqA5vzJTld8h0XJrTBpR9K IrKtS7vNkrAdBYJs5zm3i/EBRxCYhwRbpAK0S9Opk15is63dQYgHqXUiR F7eCxSDWeudFAQx70DYK0nDdRGVLYyT4gz4UW5r46U4jT362AKlswNn3T w==; X-IronPort-AV: E=McAfee;i="6200,9189,10246"; a="228023384" X-IronPort-AV: E=Sophos;i="5.88,338,1635231600"; d="scan'208";a="228023384" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2022 17:03:49 -0800 X-IronPort-AV: E=Sophos;i="5.88,338,1635231600"; d="scan'208";a="483070830" Received: from mjmartin-desk2.amr.corp.intel.com (HELO mjmartin-desk2.intel.com) ([10.251.1.6]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2022 17:03:48 -0800 From: Mat Martineau To: netdev@vger.kernel.org Cc: Matthieu Baerts , davem@davemloft.net, kuba@kernel.org, mptcp@lists.linux.dev, Mat Martineau Subject: [PATCH net-next 3/7] mptcp: clarify when options can be used Date: Wed, 2 Feb 2022 17:03:39 -0800 Message-Id: <20220203010343.113421-4-mathew.j.martineau@linux.intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220203010343.113421-1-mathew.j.martineau@linux.intel.com> References: <20220203010343.113421-1-mathew.j.martineau@linux.intel.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Matthieu Baerts RFC8684 doesn't seem to clearly specify which MPTCP options can be used together. Some options are mutually exclusive -- e.g. MP_CAPABLE and MP_JOIN --, some can be used together -- e.g. DSS + MP_PRIO --, some can but we prefer not to -- e.g. DSS + ADD_ADDR -- and some have to be used together at some points -- e.g. MP_FAIL and DSS. We need to clarify this as a base before allowing other modifications. For example, does it make sense to send a RM_ADDR with an MPC or MPJ? This remains open for possible future discussions. Signed-off-by: Matthieu Baerts Signed-off-by: Mat Martineau --- net/mptcp/options.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index ab054c389a5f..7345f28f3de1 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -1267,8 +1267,27 @@ void mptcp_write_options(__be32 *ptr, const struct t= cp_sock *tp, const struct sock *ssk =3D (const struct sock *)tp; struct mptcp_subflow_context *subflow; =20 - /* DSS, MPC, MPJ, ADD_ADDR, FASTCLOSE and RST are mutually exclusive, - * see mptcp_established_options*() + /* Which options can be used together? + * + * X: mutually exclusive + * O: often used together + * C: can be used together in some cases + * P: could be used together but we prefer not to (optimisations) + * + * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | + * ------|------|------|------|------|------|------|------|------| + * MPC |------|------|------|------|------|------|------|------| + * MPJ | X |------|------|------|------|------|------|------| + * DSS | X | X |------|------|------|------|------|------| + * ADD | X | X | P |------|------|------|------|------| + * RM | C | C | C | P |------|------|------|------| + * PRIO | X | C | C | C | C |------|------|------| + * FAIL | X | X | C | X | X | X |------|------| + * FC | X | X | X | X | X | X | X |------| + * RST | X | X | X | X | X | X | O | O | + * ------|------|------|------|------|------|------|------|------| + * + * The same applies in mptcp_established_options() function. */ if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { struct mptcp_ext *mpext =3D &opts->ext_copy; --=20 2.35.1