From mboxrd@z Thu Jan 1 00:00:00 1970 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 495981FA5 for ; Fri, 29 Apr 2022 22:02:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651269743; x=1682805743; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DlnszPk3X2RPEnjbzh3vP3TQq5DteMJxTVw6ps/Fp2w=; b=JzmsVuDWZlrZBcTleQv5Q9z3KZEnBDKvfAoZ+dnVFKydXk/KBFy3Y1FE FRHOJPWYKTxcsAlnKnW1Tux/ygzVrfCvp5zK8bstvaK1EyR8SbOFKRmoa gNAsn3b8izNSkM2DE+CwC17K6ZzIruvO+0hNT6CeT5PKlVPAfnPEXT+9G B9O9M51AAvYbmIKrXQ0A5v0oGOhausSeNibI8maIQ+wHkkakUIq5biAIm jaLRWD7B9uj84rxwH+cv5UNi72Y7gilqywpeyokNO6jyQqCbMFD80OGQg owupLTlJz4USbSgSc2pM3xPPEE9+pUtoat58FE9xNG09AmA/TE1rbGp+x w==; X-IronPort-AV: E=McAfee;i="6400,9594,10332"; a="246698322" X-IronPort-AV: E=Sophos;i="5.91,186,1647327600"; d="scan'208";a="246698322" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2022 15:02:09 -0700 X-IronPort-AV: E=Sophos;i="5.91,186,1647327600"; d="scan'208";a="582419796" Received: from mjmartin-desk2.amr.corp.intel.com (HELO mjmartin-desk2.intel.com) ([10.212.217.201]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2022 15:02:09 -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 v2 1/8] bpf: expose is_mptcp flag to bpf_tcp_sock Date: Fri, 29 Apr 2022 15:01:57 -0700 Message-Id: <20220429220204.353225-2-mathew.j.martineau@linux.intel.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220429220204.353225-1-mathew.j.martineau@linux.intel.com> References: <20220429220204.353225-1-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: 8bit 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 { -- 2.36.0