From patchwork Wed Jul 28 22:51:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 12407021 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=-19.7 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,URIBL_BLOCKED,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 4E317C4338F for ; Wed, 28 Jul 2021 22:51:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 319846103E for ; Wed, 28 Jul 2021 22:51:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232452AbhG1Wvx (ORCPT ); Wed, 28 Jul 2021 18:51:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:36970 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232073AbhG1Wvv (ORCPT ); Wed, 28 Jul 2021 18:51:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2CCB66103C; Wed, 28 Jul 2021 22:51:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627512709; bh=oBJuZNTcYSVTfhtRKT7AVcyVXW3ahX3jWEHrGsp4I90=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bIZpFoxwmIqFOd/3YF5dNLp73ApkdZ8lm7+HvOrEp6p+cv+GTYlz7ID252JiPTbGR LnGI7uxEMhuBU2gjOlp0qSOIy2GOFMyl6iKyaK7OX+mqmXLVZdMg6cliDhmh+RP37H BRFRaPSem74qaHQq2+KTJ9jsqxuIMEj84v69IZBUmUlO6onWq6rbedxUBFHS5qBIpA UAEy0uQGQQvaMtJpr6OYaFN9Xwf4tY07Gmxi3DYDFo/OWUHE3jqKroaq+9rXopvc1X qktDQnaw1lE0wEwoEt7d5F3sk8IioUPnrPdduNjIGZ8rvFSNTHamUD597xu8VZjcoL qw9UwpP5SmOYw== From: Jarkko Sakkinen To: Shuah Khan Cc: linux-kselftest@vger.kernel.org, linux-sgx@vger.kernel.org, Reinette Chatre , Borislav Petkov , Tianjia Zhang , Dave Hansen , Jarkko Sakkinen , Borislav Petkov , Jethro Beekman , linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] selftests/sgx: Fix calculations for sub-maximum field sizes Date: Thu, 29 Jul 2021 01:51:38 +0300 Message-Id: <20210728225140.248408-3-jarkko@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210728225140.248408-1-jarkko@kernel.org> References: <20210728225140.248408-1-jarkko@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@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. The original patch did a bad job explaining the code change but it turned out making sense. I wrote a new description. Fixes: 2adcba79e69d ("selftests/x86: Add a selftest for SGX") Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/ Reviewed-by: Dave Hansen Signed-off-by: Tianjia Zhang Signed-off-by: Jarkko Sakkinen --- v4: - Updated the short summary according to: https://lore.kernel.org/linux-sgx/4303b822-5861-ba2c-f620-0e752e499329@intel.com/ 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);