From patchwork Mon Dec 17 07:23:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10732803 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C0B3C746 for ; Mon, 17 Dec 2018 07:24:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A87C7297CC for ; Mon, 17 Dec 2018 07:24:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9C7F2297E2; Mon, 17 Dec 2018 07:24:50 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 18CA4297CC for ; Mon, 17 Dec 2018 07:24:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726395AbeLQHYt (ORCPT ); Mon, 17 Dec 2018 02:24:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:49794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726417AbeLQHYt (ORCPT ); Mon, 17 Dec 2018 02:24:49 -0500 Received: from sol.localdomain (c-24-23-142-8.hsd1.ca.comcast.net [24.23.142.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9032B217FA; Mon, 17 Dec 2018 07:24:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545031487; bh=pVKTUkgZskLzXJSHlLP2daHgO3bztP+bDJy2vka2L2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OKRIIFLc5TkxWcsDc9q4i8wMSPnuLqDYua1N4ph+JAg1bT1QWjdoaZcgZ+IqOc5Hd 53u+8dO1OFd8NOHLpfocF+HwLMVysOjlS+z1dRP7KYmJzqBHhxWTIAGZHKKazVT328 fwWLkT5eedxPlEXs18x+lx7Rk05G/SBpxxZTcbNI= From: Eric Biggers To: linux-crypto@vger.kernel.org, Herbert Xu Cc: Rob Rice , Raveendra Padasalagi , Gilad Ben-Yossef , Yael Chemla Subject: [PATCH 1/3] crypto: authenc - fix parsing key with misaligned rta_len Date: Sun, 16 Dec 2018 23:23:22 -0800 Message-Id: <20181217072324.16844-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181217072324.16844-1-ebiggers@kernel.org> References: <20181217072324.16844-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Keys for "authenc" AEADs are formatted as an rtattr containing a 4-byte 'enckeylen', followed by an authentication key and an encryption key. crypto_authenc_extractkeys() parses the key to find the inner keys. However, it fails to consider the case where the rtattr's payload is longer than 4 bytes but not 4-byte aligned, and where the key ends before the next 4-byte aligned boundary. In this case, 'keylen -= RTA_ALIGN(rta->rta_len);' underflows to a value near UINT_MAX. This causes a buffer overread and crash during crypto_ahash_setkey(). Fix it by restricting the rtattr payload to the expected size. Reproducer using AF_ALG: #include #include #include int main() { int fd; struct sockaddr_alg addr = { .salg_type = "aead", .salg_name = "authenc(hmac(sha256),cbc(aes))", }; struct { struct rtattr attr; __be32 enckeylen; char keys[1]; } __attribute__((packed)) key = { .attr.rta_len = sizeof(key), .attr.rta_type = 1 /* CRYPTO_AUTHENC_KEYA_PARAM */, }; fd = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(fd, (void *)&addr, sizeof(addr)); setsockopt(fd, SOL_ALG, ALG_SET_KEY, &key, sizeof(key)); } It caused: BUG: unable to handle kernel paging request at ffff88007ffdc000 PGD 2e01067 P4D 2e01067 PUD 2e04067 PMD 2e05067 PTE 0 Oops: 0000 [#1] SMP CPU: 0 PID: 883 Comm: authenc Not tainted 4.20.0-rc1-00108-g00c9fe37a7f27 #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014 RIP: 0010:sha256_ni_transform+0xb3/0x330 arch/x86/crypto/sha256_ni_asm.S:155 [...] Call Trace: sha256_ni_finup+0x10/0x20 arch/x86/crypto/sha256_ssse3_glue.c:321 crypto_shash_finup+0x1a/0x30 crypto/shash.c:178 shash_digest_unaligned+0x45/0x60 crypto/shash.c:186 crypto_shash_digest+0x24/0x40 crypto/shash.c:202 hmac_setkey+0x135/0x1e0 crypto/hmac.c:66 crypto_shash_setkey+0x2b/0xb0 crypto/shash.c:66 shash_async_setkey+0x10/0x20 crypto/shash.c:223 crypto_ahash_setkey+0x2d/0xa0 crypto/ahash.c:202 crypto_authenc_setkey+0x68/0x100 crypto/authenc.c:96 crypto_aead_setkey+0x2a/0xc0 crypto/aead.c:62 aead_setkey+0xc/0x10 crypto/algif_aead.c:526 alg_setkey crypto/af_alg.c:223 [inline] alg_setsockopt+0xfe/0x130 crypto/af_alg.c:256 __sys_setsockopt+0x6d/0xd0 net/socket.c:1902 __do_sys_setsockopt net/socket.c:1913 [inline] __se_sys_setsockopt net/socket.c:1910 [inline] __x64_sys_setsockopt+0x1f/0x30 net/socket.c:1910 do_syscall_64+0x4a/0x180 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: e236d4a89a2f ("[CRYPTO] authenc: Move enckeylen into key itself") Cc: # v2.6.25+ Signed-off-by: Eric Biggers --- crypto/authenc.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/crypto/authenc.c b/crypto/authenc.c index 37f54d1b2f669..4be293a4b5f0f 100644 --- a/crypto/authenc.c +++ b/crypto/authenc.c @@ -58,14 +58,22 @@ int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key, return -EINVAL; if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM) return -EINVAL; - if (RTA_PAYLOAD(rta) < sizeof(*param)) + + /* + * RTA_OK() didn't align the rtattr's payload when validating that it + * fits in the buffer. Yet, the keys should start on the next 4-byte + * aligned boundary. To avoid confusion, require that the rtattr + * payload be exactly the param struct, which has a 4-byte aligned size. + */ + if (RTA_PAYLOAD(rta) != sizeof(*param)) return -EINVAL; + BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO); param = RTA_DATA(rta); keys->enckeylen = be32_to_cpu(param->enckeylen); - key += RTA_ALIGN(rta->rta_len); - keylen -= RTA_ALIGN(rta->rta_len); + key += rta->rta_len; + keylen -= rta->rta_len; if (keylen < keys->enckeylen) return -EINVAL;