From patchwork Tue Aug 27 00:14:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zijian Zhang X-Patchwork-Id: 13778672 Received: from mail-qv1-f53.google.com (mail-qv1-f53.google.com [209.85.219.53]) (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 299B21FA4 for ; Tue, 27 Aug 2024 00:16:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.53 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724717790; cv=none; b=o7TeQeF58jE88iIReQKhTjO6Q3AX2xJEXuv3m2qqYMrofqvlJsn98Nk+N+Te7EN+0Q72k+NCSMerNo2RG9OpC59UYAXiHx7Y1HieP1MvO7dF8AReVkBH/XsA0MRlIe+w8vhZOMSB0eLF665q65ZqDAh+BL2ixr/2woV0PT5/T/M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724717790; c=relaxed/simple; bh=MNX9a16kkQeFn5DqUjfgOX3cRGCxUfjm0QpaWgyc7Zk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=TTBzqQ6ClkuRJbxJpvtuT1Mp61Shbi/3BcSRxyVw+EI+y259Djl67LAiJToHULxeMF9Hrh82KIUak/frQONddZ5uRbXtXpQqaC9LO8Ttt9+oIDFpGozS+38SLXBEIft/32nVTvx4vVRdxrJn8q1Zk5DS92hFegNREe5z17BdZN0= 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=iMkB9JA8; arc=none smtp.client-ip=209.85.219.53 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="iMkB9JA8" Received: by mail-qv1-f53.google.com with SMTP id 6a1803df08f44-6bf9db9740aso22131696d6.2 for ; Mon, 26 Aug 2024 17:16:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1724717786; x=1725322586; 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=KxqlCIIVPOy80RPgVgWmzEjQn5sLiFmvjQd7bMYBDjE=; b=iMkB9JA8BPpM9AqV2tFEyWluXh8moLbqZtKJ9pZ8FI26yzizTTmZrqoWQk4+MaKjNd 8vsUd0CLdO4z27n+d/nyC0PlV9oABz6RMmSAXhOziZt2GxmElRCK1TmCHfUaEVUwhrUR UWDQWL9s7+pliP8H5tthdgA3pFxj8goFCSxIM7NIkDquw1r+VI9tUVanxEhkEtEyW+4d KP45T7pzXZwaN4bvE/z/itLTCsLbXrl5+u6watdSt0JyvXS1+9herPzLjg7Fe/lXkpeG wJy+UpUaNXW0hJHotkRQUh3zDi/lSZsb/kew5TWqWvq0C1LkImqRPaTkBJfL0Iv3Y+r3 4sCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724717786; x=1725322586; 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=KxqlCIIVPOy80RPgVgWmzEjQn5sLiFmvjQd7bMYBDjE=; b=u8BCbe/gBDGsDjrkOB6+pUTuXHn4ZETSjqEwkQQ/VteWu6DMFQXiaaWPyHmtCA1bad MZEsECRdQr5pBjWeq273ifytxKky73XjnfqDWaGo58KO2FmLygvy2yw7koSREA1lNZ+2 Rebkmb7BtfdGw6OZN9Tb0d62rYuJJnlx14LA9u4SACBvztd5gm5IObtKPkq1SsYcb65f N7KAn9cjxBB7hn1BI7mE87L9DKOPcJf/Wmvw9CcTULu98dzP9ksWuGs4DbR3gwTkjaRZ OxFoooo43oUQEsdyEXW6M1rKowKqibL5haaoAaC+7iasKwLP46mBGqye19uy7n+VSgze feqA== X-Gm-Message-State: AOJu0YzAsEpM24N17dCgLufqNXsQyxdq5KCJhFfu9kD+/ChI4SpUzTiz FqFzeeoPQ4zAmCduiW5Db0na20J2WoXzI9Jyy0BtL4QkB7CkvOefVa8cmAgkAJ1Nl12PVbmXUSK W X-Google-Smtp-Source: AGHT+IFPG6Y1jf7+5BPEFiEK9LFPqtPQh5Q/Dkl6TBuKSEqW4VLlroF06ndzuDQogttxJWwjvVUxhQ== X-Received: by 2002:a05:6214:4806:b0:6bf:7fba:c829 with SMTP id 6a1803df08f44-6c32b809629mr13308046d6.42.1724717786406; Mon, 26 Aug 2024 17:16:26 -0700 (PDT) Received: from n191-036-066.byted.org ([130.44.212.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6c162dcda66sm51387136d6.122.2024.08.26.17.16.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Aug 2024 17:16:25 -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 v1 0/2] prevent bpf_reserve_hdr_opt() from growing skb larger than MTU Date: Tue, 27 Aug 2024 00:14:05 +0000 Message-Id: <20240827001407.2476854-1-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. 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 +++++++++++++++++++ 4 files changed, 70 insertions(+), 10 deletions(-)