From nobody Wed Dec 25 12:58:50 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=none (zoho.com: 198.145.21.10 is neither permitted nor denied by domain of lists.01.org) smtp.mailfrom=edk2-devel-bounces@lists.01.org Return-Path: Received: from ml01.01.org (ml01.01.org [198.145.21.10]) by mx.zohomail.com with SMTPS id 150777111781491.05764790719718; Wed, 11 Oct 2017 18:18:37 -0700 (PDT) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 6CB4721F3C18C; Wed, 11 Oct 2017 18:15:06 -0700 (PDT) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 1D0DE21F7D515 for ; Wed, 11 Oct 2017 18:15:04 -0700 (PDT) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Oct 2017 18:18:34 -0700 Received: from shwdepsi940.ccr.corp.intel.com ([10.239.9.118]) by fmsmga005.fm.intel.com with ESMTP; 11 Oct 2017 18:18:33 -0700 X-Original-To: edk2-devel@lists.01.org Received-SPF: none (zoho.com: 198.145.21.10 is neither permitted nor denied by domain of lists.01.org) client-ip=198.145.21.10; envelope-from=edk2-devel-bounces@lists.01.org; helo=ml01.01.org; Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=192.55.52.93; helo=mga11.intel.com; envelope-from=qin.long@intel.com; receiver=edk2-devel@lists.01.org X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,363,1503385200"; d="scan'208";a="161684999" From: Long Qin To: chao.b.zhang@intel.com, James.Bottomley@HansenPartnership.com Date: Thu, 12 Oct 2017 09:18:11 +0800 Message-Id: <20171012011811.2140-1-qin.long@intel.com> X-Mailer: git-send-email 2.14.1.windows.1 Subject: [edk2] [PATCH] SecurityPkg/Pkcs7Verify: Add the comments to address security problem X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: edk2-devel@lists.01.org, Qin Long MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Errors-To: edk2-devel-bounces@lists.01.org Sender: "edk2-devel" X-ZohoMail: RSF_4 Z_629925259 SPT_0 Content-Type: text/plain; charset="utf-8" Add the comments to address security problems in the Pkcs7Verify Protocol per UEFI 2.7 updates. The Pkcs7Verifier function VerifySignature() has problematic use cases where it might be used to unwittingly bypass security checks. The specific problem is that if the supplied hash is a different algorithm from the blacklist hash, the hash will be approved even if it should have been denied. The added comments place a strong warning about the problem. It is possible to use the protocol reliably, either by agreeing a hash to use for all time (like sha256) or by looping over all supported hashes when using the protocol. Cc: Chao Zhang Cc: James Bottomley Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Qin Long --- MdePkg/Include/Protocol/Pkcs7Verify.h | 10 +++++++++- SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c | 8 ++++++++ 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/MdePkg/Include/Protocol/Pkcs7Verify.h b/MdePkg/Include/Protoco= l/Pkcs7Verify.h index ca5ec75910..eaeda48300 100644 --- a/MdePkg/Include/Protocol/Pkcs7Verify.h +++ b/MdePkg/Include/Protocol/Pkcs7Verify.h @@ -6,7 +6,7 @@ PKCS#7 is a general-purpose cryptographic standard (defined by RFC2315, available at http://tools.ietf.org/html/rfc2315). =20 -Copyright (c) 2015, Intel Corporation. All rights reserved.
+Copyright (c) 2015 - 2017, Intel Corporation. All rights reserved.
This program and the accompanying materials are licensed and made availabl= e under the terms and conditions of the BSD License that accompanies this distribu= tion. The full text of the license may be found at @@ -140,6 +140,14 @@ EFI_STATUS verifies the signature of the content is valid and signing certificate w= as not revoked and is contained within a list of trusted signers. =20 + Note: because this function uses hashes and the specification contains a= variety of + hash choices, you should be aware that the check against the Revok= edDb list + will improperly succeed if the signature is revoked using a differ= ent hash + algorithm. For this reason, you should either cycle through all U= EFI supported + hashes to see if one is forbidden, or rely on a single hash choice= only if the + UEFI signature authority only signs and revokes with a single hash= (at time + of writing, this hash choice is SHA256). + @param[in] This Pointer to EFI_PKCS7_VERIFY_PROTOCOL= instance. @param[in] Signature Points to buffer containing ASN.1 DE= R-encoded PKCS detached signature. diff --git a/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c b/Secu= rityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c index 0da549a6bd..ac83e6d5c2 100644 --- a/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c +++ b/SecurityPkg/Pkcs7Verify/Pkcs7VerifyDxe/Pkcs7VerifyDxe.c @@ -1321,6 +1321,14 @@ _Exit: verifies the signature of the content is valid and signing certificate w= as not revoked and is contained within a list of trusted signers. =20 + Note: because this function uses hashes and the specification contains a= variety of + hash choices, you should be aware that the check against the Revok= edDb list + will improperly succeed if the signature is revoked using a differ= ent hash + algorithm. For this reason, you should either cycle through all U= EFI supported + hashes to see if one is forbidden, or rely on a single hash choice= only if the + UEFI signature authority only signs and revokes with a single hash= (at time + of writing, this hash choice is SHA256). + @param[in] This Pointer to EFI_PKCS7_VERIFY_PROTOCOL= instance. @param[in] Signature Points to buffer containing ASN.1 DE= R-encoded PKCS detached signature. --=20 2.14.1.windows.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel