From patchwork Wed Apr 20 22:24:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mat Martineau X-Patchwork-Id: 12820857 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 E5322C4332F for ; Wed, 20 Apr 2022 22:25:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355788AbiDTW2E (ORCPT ); Wed, 20 Apr 2022 18:28:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237210AbiDTW2C (ORCPT ); Wed, 20 Apr 2022 18:28:02 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22C13403E0; Wed, 20 Apr 2022 15:25:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650493515; x=1682029515; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DnWR4bk+hv6VcI7OdulN0bk+Petr2t2+O49LbWUe6JI=; b=BUYNBSE1u2zPy5wJ+X2aWdgSaxjnAtOpfj6KG0+q7GKUUTiUJKgcsY9E n9fN/RYrmjMQ94skyJlel19GZBVP66SQa+eP92I8+igB4w7ysqciltlGl yPgs7Qf9VQwTQShHhpTLyhvmLZxwfGxFycSRacCEDqiM22+eWsq/enJij U6vQakbZlrvAWrXpHnCDJuwh6U+DafxLbXnunJIbbUOUe1SREypmSiRbB oDWDDPGrKELomocTRv2vt7OkDOAmaQH+8c9ZACmxCbk7rUC+AKEviJBPd V4e4vwm+k6kI+Q4F1ooWQXVFZyeSr+FSjBByRNz/yB8ciHNvn86UMTYR1 A==; X-IronPort-AV: E=McAfee;i="6400,9594,10323"; a="289277577" X-IronPort-AV: E=Sophos;i="5.90,276,1643702400"; d="scan'208";a="289277577" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2022 15:25:14 -0700 X-IronPort-AV: E=Sophos;i="5.90,276,1643702400"; d="scan'208";a="555422582" Received: from mjmartin-desk2.amr.corp.intel.com (HELO mjmartin-desk2.intel.com) ([10.209.100.38]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Apr 2022 15:25:13 -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 1/7] bpf: expose is_mptcp flag to bpf_tcp_sock Date: Wed, 20 Apr 2022 15:24:53 -0700 Message-Id: <20220420222459.307649-2-mathew.j.martineau@linux.intel.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220420222459.307649-1-mathew.j.martineau@linux.intel.com> References: <20220420222459.307649-1-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 d14b10b85e51..9ef1f3e1c22f 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5694,6 +5694,7 @@ 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 143f442a9505..7b1867f1f422 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 d14b10b85e51..9ef1f3e1c22f 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5694,6 +5694,7 @@ 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 {