From patchwork Fri Feb 14 01:00:29 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Xing X-Patchwork-Id: 13974253 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) (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 F1D37CA64; Fri, 14 Feb 2025 01:01:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739494866; cv=none; b=PVIShaR3yMIiq3ZnihfMKZJc+vEfZq62KhE6SY8pAfwVZWj8iMpPL0/VwthrqsY4jfXmhAKwrb50qfhz14dyWB8sdLhqjgq4VQv2T0dseXLBPtz/zeO/ghe0ZgZCMIU7EQEDK3ZdrPhRXowJkipktNGP7EdKJ3nijsnOXekIEJA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739494866; c=relaxed/simple; bh=bKrm1hiTC/nINgvY+o1Fo1gLAQbsMuznKHX0Uw3gAzY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JdV/+LQ6It9vb2FFuxbV7ayWSXV57waw7sFXaX5FR3aZ3Mt3BCxQRWiDw8K2F1Irf/pdb/3gEuC0aoL7MKkcXXbAq6f8eTnE7DGL3x608ckcdOeeptsQaXREjhA51rWbAnlblDV2sDPExxF6p3gYL8fZDwzpmpc6oJk9x5ETiQc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JyC26Fko; arc=none smtp.client-ip=209.85.214.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JyC26Fko" Received: by mail-pl1-f173.google.com with SMTP id d9443c01a7336-220e83d65e5so13857475ad.1; Thu, 13 Feb 2025 17:01:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1739494864; x=1740099664; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7Alr0Cy5SCB+CgKRZoduXfthZLgwnrJQ/3rmN5eLpq4=; b=JyC26FkodYCdv3HUuWo1ZKXqqeaoF28UI2KFdQoAFVxA0BL42jwl9LTZxwhBy9mO0G x1jlfWNaKrVRL/1G0EXrHp7BSkAnCB2iRcuVUcJk4LJ5DyOOaOHgekPYs2lPX0k/6GMz pZKCRdj9CBvQXaDIk0ERitPG+WmvXiOrjhEjOMLYnYtzwZwkyoA2mfPniRjyJaN+U6Kw cJv5ULcxf6ajh3xV+qlfd9h84A4rjcxjaE0Pb2yc+/JXGVbO6faSfAkzdFIylxk6xptw USXn//hpGPPOy/PAGKC38YPliOdzd/xXqC/JPGlXvh+gZxiM+htj1k/remHXLrtriwD4 ucHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739494864; x=1740099664; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7Alr0Cy5SCB+CgKRZoduXfthZLgwnrJQ/3rmN5eLpq4=; b=k2i21Vpgzg8CqQ0Y3fAWlG0zpfpqNAjyBWo/cBe9u2ohafA5PZAQb8v8BeesQ2cVWq EXe463D8yFZGbeb7hy1xyy2S/FK90XBp4ty/A0hAt1UWWubF0Z86b3lexrujTirLq8cD YWBIg5smAQ+CLhjyG2N6yi1hdsFu6nMKOiEacRJpNLK6DQAS2/ZvBsdJsweeQOkjvv0Y RxhV8sccUX9usVRdhoQBNJhQIrVZpx1ePFJWEBr+P064Rd3MVN7igDqHbokyoyNewZpP v7+RjDimI2hDLusUR5dnfZnzDk82tq+iavAGzKYc+yTHLi7rzNfj9i9GgM12sgn+3BU5 CKXA== X-Forwarded-Encrypted: i=1; AJvYcCUI8NnBI58VIk8tOH71G+rpcNnHEYbXJjMrpt55xAT7PKjIn8DA3Va82u1mNEv4b9IlDFqg2B4=@vger.kernel.org X-Gm-Message-State: AOJu0YwEBAUNbHscYjBgn4LinKUs60dt2drI0qLMfWGIWuUJacFStGWC YEldCBY9Q5vzO6anVIsownCUPbBDoRlbZdORYUa0qJtEmo8bpFjs X-Gm-Gg: ASbGncs67V8cy6/R+IzZl26nrJtUdmrW9H2c9MlNS/ULi7p7eQ2NCHDUebK3yajMjk2 LvC0QekgoFyH9odaifEtXn7wAM+0npG26hwP4pT6vPI+enE/ExOQKZvRUvx7ewnhJITI0p/yY3I phdgsZcK2rgnSDlsDMCEJYUzgR0ZQegrSgvgIjsMMzNQOVbE2o6zCPncxnE95LudlXr+QqGFzcx Mu7wP/8gcUFJDty1PXQ/ztmqg+XFrZTUA6q0iCOWRxyPoU4rXfIs0/LDzzkK+wsFvHXC4i17zEA yEnwTqrD+U5MoOKw3qWWANf4Q79n4yiISDTels02ZMc0cz68vY0IKA== X-Google-Smtp-Source: AGHT+IHWxFAE42zfVksUmAwqklSodiqbmsiv5SWUoCRrl3vqWza/iZQq7H6+SoJgcp/MOSyPgd/8Qg== X-Received: by 2002:a17:902:dac6:b0:220:da88:2009 with SMTP id d9443c01a7336-220da8820d6mr59346725ad.45.1739494863937; Thu, 13 Feb 2025 17:01:03 -0800 (PST) Received: from KERNELXING-MC1.tencent.com ([111.201.25.167]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-220d534db68sm18629565ad.39.2025.02.13.17.00.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Feb 2025 17:01:03 -0800 (PST) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, willemdebruijn.kernel@gmail.com, willemb@google.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, horms@kernel.org Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: [PATCH bpf-next v11 03/12] bpf: prevent unsafe access to the sock fields in the BPF timestamping callback Date: Fri, 14 Feb 2025 09:00:29 +0800 Message-Id: <20250214010038.54131-4-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20250214010038.54131-1-kerneljasonxing@gmail.com> References: <20250214010038.54131-1-kerneljasonxing@gmail.com> 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 The subsequent patch will implement BPF TX timestamping. It will call the sockops BPF program without holding the sock lock. This breaks the current assumption that all sock ops programs will hold the sock lock. The sock's fields of the uapi's bpf_sock_ops requires this assumption. To address this, a new "u8 is_locked_tcp_sock;" field is added. This patch sets it in the current sock_ops callbacks. The "is_fullsock" test is then replaced by the "is_locked_tcp_sock" test during sock_ops_convert_ctx_access(). The new TX timestamping callbacks added in the subsequent patch will not have this set. This will prevent unsafe access from the new timestamping callbacks. Potentially, we could allow read-only access. However, this would require identifying which callback is read-safe-only and also requires additional BPF instruction rewrites in the covert_ctx. Since the BPF program can always read everything from a socket (e.g., by using bpf_core_cast), this patch keeps it simple and disables all read and write access to any socket fields through the bpf_sock_ops UAPI from the new TX timestamping callback. Moreover, note that some of the fields in bpf_sock_ops are specific to tcp_sock, and sock_ops currently only supports tcp_sock. In the future, UDP timestamping will be added, which will also break this assumption. The same idea used in this patch will be reused. Considering that the current sock_ops only supports tcp_sock, the variable is named is_locked_"tcp"_sock. Signed-off-by: Jason Xing --- include/linux/filter.h | 1 + include/net/tcp.h | 1 + net/core/filter.c | 8 ++++---- net/ipv4/tcp_input.c | 2 ++ net/ipv4/tcp_output.c | 2 ++ 5 files changed, 10 insertions(+), 4 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index a3ea46281595..d36d5d5180b1 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1508,6 +1508,7 @@ struct bpf_sock_ops_kern { void *skb_data_end; u8 op; u8 is_fullsock; + u8 is_locked_tcp_sock; u8 remaining_opt_len; u64 temp; /* temp and everything after is not * initialized to 0 before calling diff --git a/include/net/tcp.h b/include/net/tcp.h index 5b2b04835688..4c4dca59352b 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2649,6 +2649,7 @@ static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); if (sk_fullsock(sk)) { sock_ops.is_fullsock = 1; + sock_ops.is_locked_tcp_sock = 1; sock_owned_by_me(sk); } diff --git a/net/core/filter.c b/net/core/filter.c index 1c6c07507a78..8631036f6b64 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -10381,10 +10381,10 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, } \ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF( \ struct bpf_sock_ops_kern, \ - is_fullsock), \ + is_locked_tcp_sock), \ fullsock_reg, si->src_reg, \ offsetof(struct bpf_sock_ops_kern, \ - is_fullsock)); \ + is_locked_tcp_sock)); \ *insn++ = BPF_JMP_IMM(BPF_JEQ, fullsock_reg, 0, jmp); \ if (si->dst_reg == si->src_reg) \ *insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg, \ @@ -10469,10 +10469,10 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, temp)); \ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF( \ struct bpf_sock_ops_kern, \ - is_fullsock), \ + is_locked_tcp_sock), \ reg, si->dst_reg, \ offsetof(struct bpf_sock_ops_kern, \ - is_fullsock)); \ + is_locked_tcp_sock)); \ *insn++ = BPF_JMP_IMM(BPF_JEQ, reg, 0, 2); \ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF( \ struct bpf_sock_ops_kern, sk),\ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eb82e01da911..95733dcdfb4b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -169,6 +169,7 @@ static void bpf_skops_parse_hdr(struct sock *sk, struct sk_buff *skb) memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); sock_ops.op = BPF_SOCK_OPS_PARSE_HDR_OPT_CB; sock_ops.is_fullsock = 1; + sock_ops.is_locked_tcp_sock = 1; sock_ops.sk = sk; bpf_skops_init_skb(&sock_ops, skb, tcp_hdrlen(skb)); @@ -185,6 +186,7 @@ static void bpf_skops_established(struct sock *sk, int bpf_op, memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); sock_ops.op = bpf_op; sock_ops.is_fullsock = 1; + sock_ops.is_locked_tcp_sock = 1; sock_ops.sk = sk; /* sk with TCP_REPAIR_ON does not have skb in tcp_finish_connect */ if (skb) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index bc95d2a5924f..a0e779bdbc6b 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -525,6 +525,7 @@ static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, sock_owned_by_me(sk); sock_ops.is_fullsock = 1; + sock_ops.is_locked_tcp_sock = 1; sock_ops.sk = sk; } @@ -570,6 +571,7 @@ static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, sock_owned_by_me(sk); sock_ops.is_fullsock = 1; + sock_ops.is_locked_tcp_sock = 1; sock_ops.sk = sk; }