From patchwork Fri Feb 16 23:55:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 202452 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:693c:2685:b0:108:e6aa:91d0 with SMTP id mn5csp61546dyc; Fri, 16 Feb 2024 16:01:10 -0800 (PST) X-Forwarded-Encrypted: i=2; AJvYcCUinS6lLREuVnkQZBwLTBmrlKS6E5b3MfRlbuE1r8CAlJuPU+eYx/LF9unxHcAYMRO0Pwt1aMuYI4NNQLVrX/yRr0Ovdg== X-Google-Smtp-Source: AGHT+IHkXK4vykAKcEoCUWyj1RvmqKgsHeUi2T/lfnzN5/YrmPGvJmA4c5QpoMyPHRL4MPMTzAUi X-Received: by 2002:a05:6a00:124b:b0:6e1:18d2:db15 with SMTP id u11-20020a056a00124b00b006e118d2db15mr8515629pfi.2.1708128070214; Fri, 16 Feb 2024 16:01:10 -0800 (PST) Received: from sv.mirrors.kernel.org (sv.mirrors.kernel.org. [2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id y18-20020aa79e12000000b006e03381d1ddsi636931pfq.343.2024.02.16.16.01.10 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Feb 2024 16:01:10 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-69517-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@chromium.org header.s=google header.b="VQCtYCr/"; arc=fail (body hash mismatch); spf=pass (google.com: domain of linux-kernel+bounces-69517-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-69517-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 162F32897CC for ; Sat, 17 Feb 2024 00:00:44 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A8AAC154450; Fri, 16 Feb 2024 23:55:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="VQCtYCr/" Received: from mail-pf1-f180.google.com (mail-pf1-f180.google.com [209.85.210.180]) (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 1282A14C59A for ; Fri, 16 Feb 2024 23:55:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708127747; cv=none; b=hJKqKswMLBBuQWrvXNiTR/CMW0J2OpfpTTGbeBI1pSDds7swn2mTowf2Z+4hJlIiPcoSj4c6yXAlwfJhUUFOOsFBQxG8EeTNy8k9UerFfCURoM33bWFkYs4z1gy91fFDUTr/s0wUrFbld29PXa0Mk0aTAkaXSvz5neRDCoGOPOM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708127747; c=relaxed/simple; bh=4OucJmNe1/pNjupONQadff5J4lun4ayJWUXyyzw61w8=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=krjPliP3jPkbddWytiWTci3ryX0rEtkl2nx1UOocgdyj92LPL7Tyq4PS/ica6xVk8wG6tYH3HGpVcFOz1dTvvp98Nc9zleaYU5kRFOOthpT+b37IIEjEp7o/xgKzyT7Zzx+OBGsvFph6/LOT9iVjM8vz4Ype4KYXKm/2uvz1n6Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=VQCtYCr/; arc=none smtp.client-ip=209.85.210.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Received: by mail-pf1-f180.google.com with SMTP id d2e1a72fcca58-6e10e50179bso1940276b3a.1 for ; Fri, 16 Feb 2024 15:55:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1708127743; x=1708732543; 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=rUDkEiOEm4wZFWkz9cLvzAsbKQOJPsyUHuSB+y80Mkk=; b=VQCtYCr/+ts5IGN30TRG5SvBOqUyUZrUebrY5VZC5UYDCsfaMgpa/3qM9YoBXxTx3U Gc9AUYF5vVlvdREE3lVmWZ3yJpbArbyk4bmvb+kSQnSQlaQJV5DIvlubT0QquujUA0Br fQFB+0fUe3oegyOpeZvpJiJ4HbgTWjzHAYYzk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708127743; x=1708732543; 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=rUDkEiOEm4wZFWkz9cLvzAsbKQOJPsyUHuSB+y80Mkk=; b=F/hLdFE3qAznQK0DRPPvcbF/6Z+iclDzNPh/kBQ5EJvLKWfGbkNDLnqAFKMogTGQwE dVddvKZjU+K3rnLWCzYZjd2CP2V8e94hBzzEpZ1X7pIkcLV11MxTLfq54GqLUAkUZ5AP SxWe+ddd6B4u4uYGC5i1MaqhYGAOOJZOFx25Qr4kXYGuaN20+KmdtuyEFFGWZlC7KGKI Z4UqWGzCQjWcVok893vebTERDJXXuxLL3yJ1Pe+RKyZze8N9NOQ9op9KYdygS/JE9+FE xTSFe1EAaDXJaEy+JPiy1BOU8rSvhUTN0FOrl4jmCCGiM/APTVS5H2rrNk8zV1dIWEOu Z0qA== X-Forwarded-Encrypted: i=1; AJvYcCWJKJBipVqLH5EGBYK1aIvaWf5lvNt6Y0mlkA9vXhr6mQpOm6nPw0v5cEs2u439Hzs8nSbvci4SAQ+vT+bu+w2liMjwpcRpC0Bmxfia X-Gm-Message-State: AOJu0YzRWtI9unbuTvPpsqg7RZ8woXDOssPdYd0QKLQoI43UlcNj74I0 Z2rj/K8Q4rvM7MvUfreW63gP9tEelOImm69UdFSRgL32jZwEOekFQWUJ9Z2akQ== X-Received: by 2002:a05:6a00:2d20:b0:6e1:4854:a971 with SMTP id fa32-20020a056a002d2000b006e14854a971mr1937441pfb.29.1708127743221; Fri, 16 Feb 2024 15:55:43 -0800 (PST) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id ca27-20020a056a02069b00b005dc4fc80b21sm368295pgb.70.2024.02.16.15.55.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Feb 2024 15:55:42 -0800 (PST) From: Kees Cook To: Alexei Starovoitov Cc: Kees Cook , Mark Rutland , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Mykola Lysenko , Shuah Khan , Haowen Bai , bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, Yonghong Song , Anton Protopopov , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2] bpf: Replace bpf_lpm_trie_key 0-length array with flexible array Date: Fri, 16 Feb 2024 15:55:40 -0800 Message-Id: <20240216235536.it.234-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4343; i=keescook@chromium.org; h=from:subject:message-id; bh=4OucJmNe1/pNjupONQadff5J4lun4ayJWUXyyzw61w8=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlz/X8UPCdAKeZwgS/GrEX/APRKLSR78iobTw4y dXxUgXbWaKJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZc/1/AAKCRCJcvTf3G3A Ju39D/9tO6fK6reOxpstX11hwZ2bgrVjYujyRm7uaqbmD+TCRcbVOzoQd0p7gjziow3lwrEyLa+ 4YP7D8O3gXP0SZVLS4qwYCBDTT09wuVBZzXp9rm3z8IxDmN+WpJOCaMh5j6jd84QsNNO8INr2Tf Opb2E+xfhF9+rW3QEIksdQj1gOOS5o/R/jF0x+KJCS+fB5lNtJa0x545ihPNPAC76/WUdogGftD SdhjFednoLYJFL/AOIiCa9GWmd8Gj7USAKFHFSs3ZkMwLqzAngxC8oPvGuK9stI/cBkAqzDj9Mg ldvYlxhlCeAjn2yP0LKEEiCCGHz/KioHHO3r1J7ywT1ccobLkatybedYEk8zGMQWpfVKyWR4udr ZLw4uXlAmfPdoZBZ0r8RcFpqhg6X+uTR6le6/I3JiOXHLPb2T4xaghtvCxXwWcjaG9DXXyK3wRz CuLQ1arkLEbVTyyHNjBnG65P+BVRB5mJqSm1t3uA0nuMp+d2i4qgce2Z801e3gLPVI6TKVdrZHo 5HqzhpSZXfrN7LaXubTTX7EVx+5jVV54lRpxKOdiOy23UrA9pI+olBpYjQHM+uztAtb6hVoHmTW vRp8RuUUrhKE8U2QE65ZTTFIl1P86FFUqDgH96cB9vp3OQNZNGwBnRFR3+KxEGzvH0RQ4fKIoQn q51rjQ9 nGYFw61w== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1791102099773502309 X-GMAIL-MSGID: 1791102099773502309 Replace deprecated 0-length array in struct bpf_lpm_trie_key with flexible array. Found with GCC 13: ./kernel/bpf/lpm_trie.c:207:51: warning: array subscript i is outside array bounds of 'const __u8[0]' {aka 'const unsigned char[]'} [-Warray-bounds=] 207 | *(__be16 *)&key->data[i]); | ^~~~~~~~~~~~~ ./include/uapi/linux/swab.h:102:54: note: in definition of macro '__swab16' 102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) | ^ ./include/linux/byteorder/generic.h:97:21: note: in expansion of macro '__be16_to_cpu' 97 | #define be16_to_cpu __be16_to_cpu | ^~~~~~~~~~~~~ ./kernel/bpf/lpm_trie.c:206:28: note: in expansion of macro 'be16_to_cpu' 206 | u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] ^ | ^~~~~~~~~~~ In file included from ../include/linux/bpf.h:7: ./include/uapi/linux/bpf.h:82:17: note: while referencing 'data' 82 | __u8 data[0]; /* Arbitrary size */ | ^~~~ And found at run-time under CONFIG_FORTIFY_SOURCE: UBSAN: array-index-out-of-bounds in kernel/bpf/lpm_trie.c:218:49 index 0 is out of range for type '__u8 [*]' This includes fixing the selftest which was incorrectly using a variable length struct as a header, identified earlier[1]. Avoid this by just explicitly including the prefixlen member instead of struct bpf_lpm_trie_key. Note that it is not possible to simply remove the "data" member, as it is referenced by userspace cilium: struct egress_gw_policy_key in_key = { .lpm_key = { 32 + 24, {} }, .saddr = CLIENT_IP, .daddr = EXTERNAL_SVC_IP & 0Xffffff, }; systemd: ipv6_map_fd = bpf_map_new( BPF_MAP_TYPE_LPM_TRIE, offsetof(struct bpf_lpm_trie_key, data) + sizeof(uint32_t)*4, sizeof(uint64_t), ... The only risk to UAPI would be if sizeof() were used directly on the data member, which it does not seem to be. It is only used as a static initializer destination and to find its location via offsetof(). Link: https://lore.kernel.org/all/202206281009.4332AA33@keescook/ [1] Reported-by: Mark Rutland Closes: https://paste.debian.net/hidden/ca500597/ Signed-off-by: Kees Cook Acked-by: Gustavo A. R. Silva --- Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Andrii Nakryiko Cc: Martin KaFai Lau Cc: Song Liu Cc: Yonghong Song Cc: John Fastabend Cc: KP Singh Cc: Stanislav Fomichev Cc: Hao Luo Cc: Jiri Olsa Cc: Mykola Lysenko Cc: Shuah Khan Cc: Haowen Bai Cc: bpf@vger.kernel.org Cc: linux-kselftest@vger.kernel.org v2- clarify commit log, add more failure examples v1- https://lore.kernel.org/all/63e531e3.170a0220.3a46a.3262@mx.google.com/ --- include/uapi/linux/bpf.h | 2 +- tools/testing/selftests/bpf/progs/map_ptr_kern.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 754e68ca8744..359dd8a429c1 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -80,7 +80,7 @@ struct bpf_insn { /* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ struct bpf_lpm_trie_key { __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ - __u8 data[0]; /* Arbitrary size */ + __u8 data[]; /* Arbitrary size */ }; struct bpf_cgroup_storage_key { diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c b/tools/testing/selftests/bpf/progs/map_ptr_kern.c index 3325da17ec81..1d476c6ae284 100644 --- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c +++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c @@ -316,7 +316,7 @@ struct lpm_trie { } __attribute__((preserve_access_index)); struct lpm_key { - struct bpf_lpm_trie_key trie_key; + __u32 prefixlen; __u32 data; };