From patchwork Tue Aug 27 01:37:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zijian Zhang X-Patchwork-Id: 13778684 Received: from mail-oo1-f43.google.com (mail-oo1-f43.google.com [209.85.161.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6827BE5D for ; Tue, 27 Aug 2024 01:39:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724722753; cv=none; b=j8gPofg24tmld1SWzefV5NBl/de9nosp4Psn+o08bG9NTbF50cahecqdSD5zTkFxOCDT/SbotnvwtZkefwOulauK99BdEdc5qArT7VmCXQWllvP5dUJ/5/j8FhTqohdRs6s0rZo2k/zqj3aFt8fSVNQTGTyXRFaH+bMKV+WC/zI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724722753; c=relaxed/simple; bh=v3fq1KW4aEZUuFi/YTksAUajn0gmDL0v4Km51mhcyR0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=lBhh/lLO5miJMgERZjzHZr78uFIWSj5+8f6E5MvfohkslBhnEqXpf+7J2T+ct81DPpbCSBSOt0WTkr/d2lmI3YD8Fb+YzCVa40HmSFwBJ7qXgbLQP/lCaPtloPloMe8kkgHntBTN/ZGmOlEdxGO5rU5w1Cx0ke06rdsoQ2nKxbQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com; spf=pass smtp.mailfrom=bytedance.com; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b=XGzyspfO; arc=none smtp.client-ip=209.85.161.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=bytedance.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bytedance.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b="XGzyspfO" Received: by mail-oo1-f43.google.com with SMTP id 006d021491bc7-5daa93677e1so3830213eaf.3 for ; Mon, 26 Aug 2024 18:39:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1724722750; x=1725327550; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=+KCk/g2sbZA8Uv+3d3NhCpjCZnAuMknzU3OmgDY2yvs=; b=XGzyspfODawRUVYbEIXpW3x1P5nyEgd5KbzdHwRV23IrIwr+UXnA2hUsOtpjbWqvLk T9Vw7Z8/xgvYdWhSWftia68MHXpQyx+AWbWc1nrwwepLMvR4EoOFcj342PT2uLoA+jfz fI32v93MkuTrePr26CeIiUinLI6mtT7xf02CmaZUardxUKynxHjOaj7PhqY+rC2wKok6 8QI5zVnfg9JSZclAq+oy6ER15hOlqdJbGkIxV+km2pDFvkJjkKY5+yt10c3UZQgVZZ02 Plr4CwMmj1YrKk6lTAtWQGPGlsTbSCWvZ7wIQALfjedqRRUdjB2GzquqU1MXbrrrzIBg iOOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724722750; x=1725327550; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+KCk/g2sbZA8Uv+3d3NhCpjCZnAuMknzU3OmgDY2yvs=; b=mTMstJTynJeD8plDhT5NQsV3foBDpbWBqdHPCmiIDtcojDl9j5wZnhtLSIXTcyfqQ0 mQSg8nOv3FfrfCB+Jk6OmaDf4hv8dOYiCTTyiopl4oAQEuEBSvwL4Hp5a0V6q3lbm41U 7h8OBJckk5NGeBiVzuzXDRENrAWbh2JDPKb/1FOx7qFJXzHW6q0yVXKYg50W9NmOakUo 3gdL56BVUc9D6ugTzMvbZK6mPKJi4Ar9ZEV5F2cuXp0neFv5D1/oyaf4ZytaFUj9rHN5 bL3QA22YXFJcNabCPo8D43T6IqfIgTGK4CYzBH3mhn2TWX8gvNhgeIDUxLvY95RrYGfB YLOg== X-Gm-Message-State: AOJu0YyAr5o5q5+wGPtrr+ABTODJJYZeTPnxr4m1CrMzSzE6XkTc7l9T 0kXrpURoAUf/v/G45kYei1APtLdRtgsnGT6gEmh3CAYepk9che8uGH43LFy1MPaCskenVMClnrB j X-Google-Smtp-Source: AGHT+IFzj5Egmx82UlqLtS8702oDW5B8Irx0HmVgprRpj1oJQaQZl9jXZPR44czyMdc7d4+JYt2MPQ== X-Received: by 2002:a05:6358:3116:b0:1ac:f144:2b16 with SMTP id e5c5f4694b2df-1b5ec0e1f2fmr225096355d.26.1724722750417; Mon, 26 Aug 2024 18:39:10 -0700 (PDT) Received: from n191-036-066.byted.org ([147.160.184.150]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-454fe1c5711sm48263401cf.82.2024.08.26.18.39.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Aug 2024 18:39:09 -0700 (PDT) From: zijianzhang@bytedance.com To: bpf@vger.kernel.org Cc: edumazet@google.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com, shuah@kernel.org, xiyou.wangcong@gmail.com, wangdongdong.6@bytedance.com, zhoufeng.zf@bytedance.com, Amery Hung Subject: [PATCH bpf-next v2 0/2] prevent bpf_reserve_hdr_opt() from growing skb larger than MTU Date: Tue, 27 Aug 2024 01:37:34 +0000 Message-Id: <20240827013736.2845596-1-zijianzhang@bytedance.com> X-Mailer: git-send-email 2.20.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Amery Hung This series prevents sockops users from accidentally causing packet drops. This can happen when a BPF_SOCK_OPS_HDR_OPT_LEN_CB program reserves different option lengths in tcp_sendmsg(). Initially, sockops BPF_SOCK_OPS_HDR_OPT_LEN_CB program will be called to reserve a space in tcp_send_mss(), which will return the MSS for TSO. Then, BPF_SOCK_OPS_HDR_OPT_LEN_CB will be called in __tcp_transmit_skb() again to calculate the actual tcp_option_size and skb_push() the total header size. skb->gso_size is restored from TCP_SKB_CB(skb)->tcp_gso_size, which is derived from tcp_send_mss() where we first call HDR_OPT_LEN. If the reserved opt size is smaller than the actual header size, the len of the skb can exceed the MTU. As a result, ip(6)_fragment will drop the packet if skb->ignore_df is not set. To prevent this accidental packet drop, we need to make sure the second call to the BPF_SOCK_OPS_HDR_OPT_LEN_CB program reserves space not more than the first time. Since this cannot be done during verification time, we add a runtime sanity check to have bpf_reserve_hdr_opt return an error instead of causing packet drops later. We also add a selftests to verify the sanity check. If users accidentally reserve a small size, bpf_reserve_hdr_opt() should return an appropriate error value and no packet should be dropped. Changelog: v1 -> v2: - I accidentally missed the eBPF prog file in the previous patch submission, sorry for the convenience. Amery Hung (1): bpf: tcp: prevent bpf_reserve_hdr_opt() from growing skb larger than MTU Zijian Zhang (1): bpf: selftests: reserve smaller tcp header options than the actual size include/net/tcp.h | 8 +++ net/ipv4/tcp_input.c | 8 --- net/ipv4/tcp_output.c | 13 +++- .../bpf/prog_tests/tcp_hdr_options.c | 51 +++++++++++++ .../bpf/progs/test_reserve_tcp_hdr_options.c | 71 +++++++++++++++++++ 5 files changed, 141 insertions(+), 10 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/test_reserve_tcp_hdr_options.c