From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1738C07E99 for ; Mon, 5 Jul 2021 14:37:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB9546195A for ; Mon, 5 Jul 2021 14:37:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231520AbhGEOjk (ORCPT ); Mon, 5 Jul 2021 10:39:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:43860 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231511AbhGEOjj (ORCPT ); Mon, 5 Jul 2021 10:39:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E817C61955; Mon, 5 Jul 2021 14:37:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625495822; bh=cRp9ny7eyKyuD0MO2TdfPzp9DciYKWy2hpAippP5l1M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MOvW33LflC0rIYgHmOKdap42/n3ieZr2zx1FGV6tPK4wS1ToslmmoOSRAeAiLYTqj s61uoiZIoM6fV7JOOZqWp86ArFS5j4cjh/07Pc8qMPlZIWlk0JRiLOde8vAs9b7Ykn T1I/NHvENc89Kh7lrIcJ2T8DffQrWo29D5VLelHWR/Q2+O0J/9ZM1NTScectOaPmjr i2mXZ7kx2l/EtFJ2e+vkI0getpG5qGH+M7ah4g4cGooaD/JvPwjxZXvkVmXafA0MyH 5aculBgEFThJM+h/eow70W1cALwszuKJHSFjnN2+sUKtRu8aMqX9QE3k04PZESQfUd 6Tu3vtkn+J8sw== From: Jarkko Sakkinen To: Shuah Khan Cc: linux-kselftest@vger.kernel.org, linux-sgx@vger.kernel.org, Reinette Chatre , Borislav Petkov , Tianjia Zhang , Jarkko Sakkinen , Dave Hansen , Jethro Beekman , Borislav Petkov , linux-kernel@vger.kernel.org Subject: [PATCH 2/4] selftests/sgx: Fix Q1 and Q2 calculation in sigstruct.c Date: Mon, 5 Jul 2021 17:36:50 +0300 Message-Id: <20210705143652.116125-3-jarkko@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210705143652.116125-1-jarkko@kernel.org> References: <20210705143652.116125-1-jarkko@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Tianjia Zhang Q1 and Q2 are numbers with *maximum* length of 384 bytes. If the calculated length of Q1 and Q2 is less than 384 bytes, things will go wrong. E.g. if Q2 is 383 bytes, then 1. The bytes of q2 are copied to sigstruct->q2 in calc_q1q2(). 2. The entire sigstruct->q2 is reversed, which results it being 256 * Q2, given that the last byte of sigstruct->q2 is added to before the bytes given by calc_q1q2(). Either change in key or measurement can trigger the bug. E.g. an unmeasured heap could cause a devastating change in Q1 or Q2. Reverse exactly the bytes of Q1 and Q2 in calc_q1q2() before returning to the caller. Fixes: 2adcba79e69d ("selftests/x86: Add a selftest for SGX") Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/ Signed-off-by: Tianjia Zhang Signed-off-by: Jarkko Sakkinen --- The original patch did a bad job explaining the code change but it turned out making sense. I wrote a new description. v3: - Adjusted the fixes tag to refer to the correct commit v2: - Added a fixes tag. tools/testing/selftests/sgx/sigstruct.c | 41 +++++++++++++------------ 1 file changed, 21 insertions(+), 20 deletions(-) diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c index dee7a3d6c5a5..92bbc5a15c39 100644 --- a/tools/testing/selftests/sgx/sigstruct.c +++ b/tools/testing/selftests/sgx/sigstruct.c @@ -55,10 +55,27 @@ static bool alloc_q1q2_ctx(const uint8_t *s, const uint8_t *m, return true; } +static void reverse_bytes(void *data, int length) +{ + int i = 0; + int j = length - 1; + uint8_t temp; + uint8_t *ptr = data; + + while (i < j) { + temp = ptr[i]; + ptr[i] = ptr[j]; + ptr[j] = temp; + i++; + j--; + } +} + static bool calc_q1q2(const uint8_t *s, const uint8_t *m, uint8_t *q1, uint8_t *q2) { struct q1q2_ctx ctx; + int len; if (!alloc_q1q2_ctx(s, m, &ctx)) { fprintf(stderr, "Not enough memory for Q1Q2 calculation\n"); @@ -89,8 +106,10 @@ static bool calc_q1q2(const uint8_t *s, const uint8_t *m, uint8_t *q1, goto out; } - BN_bn2bin(ctx.q1, q1); - BN_bn2bin(ctx.q2, q2); + len = BN_bn2bin(ctx.q1, q1); + reverse_bytes(q1, len); + len = BN_bn2bin(ctx.q2, q2); + reverse_bytes(q2, len); free_q1q2_ctx(&ctx); return true; @@ -152,22 +171,6 @@ static RSA *gen_sign_key(void) return key; } -static void reverse_bytes(void *data, int length) -{ - int i = 0; - int j = length - 1; - uint8_t temp; - uint8_t *ptr = data; - - while (i < j) { - temp = ptr[i]; - ptr[i] = ptr[j]; - ptr[j] = temp; - i++; - j--; - } -} - enum mrtags { MRECREATE = 0x0045544145524345, MREADD = 0x0000000044444145, @@ -367,8 +370,6 @@ bool encl_measure(struct encl *encl) /* BE -> LE */ reverse_bytes(sigstruct->signature, SGX_MODULUS_SIZE); reverse_bytes(sigstruct->modulus, SGX_MODULUS_SIZE); - reverse_bytes(sigstruct->q1, SGX_MODULUS_SIZE); - reverse_bytes(sigstruct->q2, SGX_MODULUS_SIZE); EVP_MD_CTX_destroy(ctx); RSA_free(key); -- 2.32.0