From patchwork Mon May 2 21:12:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mat Martineau X-Patchwork-Id: 12834739 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEA8BC4332F for ; Mon, 2 May 2022 21:12:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1387588AbiEBVQN (ORCPT ); Mon, 2 May 2022 17:16:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245719AbiEBVQL (ORCPT ); Mon, 2 May 2022 17:16:11 -0400 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C2D726E7; Mon, 2 May 2022 14:12:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651525961; x=1683061961; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DlnszPk3X2RPEnjbzh3vP3TQq5DteMJxTVw6ps/Fp2w=; b=dYJ9AorlUTegnySMYv5uV1s0f1QONlPJIMNq533hLVRDtyzjHdaqn59C xSf5LWf3d44G44L/vHyyLCMQeQ/k/VOka0R2dTJxAOtSxXTX302hCM4ro kvvYnDtW0jdpLqpa1IXKLZLImF0PewRRuNqfXq4UKiBzuHOdRk+qO4QsQ 99SvnS78iOflyoU3V328o3oDZ+OEiRy3LizApN8wpr2zqfdD8eLkdqU1X UjdFXONA87YMTvR/dSS39q+hQ3qDt4YVaCTBk5LRojOrjv9pAG8Ezdnrk XcJsV58OoPllcdP1z2t4TIgQT9jC9U5vItLNq4Nm6vRBvtQi8Of8tcAun A==; X-IronPort-AV: E=McAfee;i="6400,9594,10335"; a="247878459" X-IronPort-AV: E=Sophos;i="5.91,193,1647327600"; d="scan'208";a="247878459" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 May 2022 14:12:40 -0700 X-IronPort-AV: E=Sophos;i="5.91,193,1647327600"; d="scan'208";a="810393787" Received: from mjmartin-desk2.amr.corp.intel.com (HELO mjmartin-desk2.intel.com) ([10.212.141.55]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 May 2022 14:12:40 -0700 From: Mat Martineau To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: Nicolas Rybowski , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, mptcp@lists.linux.dev, Matthieu Baerts , Mat Martineau Subject: [PATCH bpf-next v3 1/8] bpf: expose is_mptcp flag to bpf_tcp_sock Date: Mon, 2 May 2022 14:12:27 -0700 Message-Id: <20220502211235.142250-2-mathew.j.martineau@linux.intel.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220502211235.142250-1-mathew.j.martineau@linux.intel.com> References: <20220502211235.142250-1-mathew.j.martineau@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Nicolas Rybowski is_mptcp is a field from struct tcp_sock used to indicate that the current tcp_sock is part of the MPTCP protocol. In this protocol, a first socket (mptcp_sock) is created with sk_protocol set to IPPROTO_MPTCP (=262) for control purpose but it isn't directly on the wire. This is the role of the subflow (kernel) sockets which are classical tcp_sock with sk_protocol set to IPPROTO_TCP. The only way to differentiate such sockets from plain TCP sockets is the is_mptcp field from tcp_sock. Such an exposure in BPF is thus required to be able to differentiate plain TCP sockets from MPTCP subflow sockets in BPF_PROG_TYPE_SOCK_OPS programs. The choice has been made to silently pass the case when CONFIG_MPTCP is unset by defaulting is_mptcp to 0 in order to make BPF independent of the MPTCP configuration. Another solution is to make the verifier fail in 'bpf_tcp_sock_is_valid_ctx_access' but this will add an additional '#ifdef CONFIG_MPTCP' in the BPF code and a same injected BPF program will not run if MPTCP is not set. An example use-case is provided in https://github.com/multipath-tcp/mptcp_net-next/tree/scripts/bpf/examples Suggested-by: Matthieu Baerts Acked-by: Matthieu Baerts Signed-off-by: Nicolas Rybowski Signed-off-by: Mat Martineau --- include/uapi/linux/bpf.h | 1 + net/core/filter.c | 9 ++++++++- tools/include/uapi/linux/bpf.h | 1 + 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 444fe6f1cf35..7043f3641534 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5706,6 +5706,7 @@ struct bpf_tcp_sock { __u32 delivered; /* Total data packets delivered incl. rexmits */ __u32 delivered_ce; /* Like the above but only ECE marked packets */ __u32 icsk_retransmits; /* Number of unrecovered [RTO] timeouts */ + __u32 is_mptcp; /* Is MPTCP subflow? */ }; struct bpf_sock_tuple { diff --git a/net/core/filter.c b/net/core/filter.c index b741b9f7e6a9..b474e5bd1458 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6754,7 +6754,7 @@ bool bpf_tcp_sock_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { if (off < 0 || off >= offsetofend(struct bpf_tcp_sock, - icsk_retransmits)) + is_mptcp)) return false; if (off % size != 0) @@ -6888,6 +6888,13 @@ u32 bpf_tcp_sock_convert_ctx_access(enum bpf_access_type type, case offsetof(struct bpf_tcp_sock, icsk_retransmits): BPF_INET_SOCK_GET_COMMON(icsk_retransmits); break; + case offsetof(struct bpf_tcp_sock, is_mptcp): +#ifdef CONFIG_MPTCP + BPF_TCP_SOCK_GET_COMMON(is_mptcp); +#else + *insn++ = BPF_MOV32_IMM(si->dst_reg, 0); +#endif + break; } return insn - insn_buf; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 444fe6f1cf35..7043f3641534 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5706,6 +5706,7 @@ struct bpf_tcp_sock { __u32 delivered; /* Total data packets delivered incl. rexmits */ __u32 delivered_ce; /* Like the above but only ECE marked packets */ __u32 icsk_retransmits; /* Number of unrecovered [RTO] timeouts */ + __u32 is_mptcp; /* Is MPTCP subflow? */ }; struct bpf_sock_tuple {