From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=192.55.52.120; helo=mga04.intel.com; envelope-from=hao.a.wu@intel.com; receiver=edk2-devel@lists.01.org Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) (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 1B92A21A00AE6 for ; Sat, 29 Sep 2018 22:33:42 -0700 (PDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Sep 2018 22:33:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,322,1534834800"; d="scan'208";a="95131132" Received: from fmsmsx105.amr.corp.intel.com ([10.18.124.203]) by orsmga001.jf.intel.com with ESMTP; 29 Sep 2018 22:33:30 -0700 Received: from fmsmsx125.amr.corp.intel.com (10.18.125.40) by FMSMSX105.amr.corp.intel.com (10.18.124.203) with Microsoft SMTP Server (TLS) id 14.3.319.2; Sat, 29 Sep 2018 22:33:29 -0700 Received: from shsmsx152.ccr.corp.intel.com (10.239.6.52) by FMSMSX125.amr.corp.intel.com (10.18.125.40) with Microsoft SMTP Server (TLS) id 14.3.319.2; Sat, 29 Sep 2018 22:33:29 -0700 Received: from shsmsx104.ccr.corp.intel.com ([169.254.5.183]) by SHSMSX152.ccr.corp.intel.com ([169.254.6.37]) with mapi id 14.03.0319.002; Sun, 30 Sep 2018 13:33:27 +0800 From: "Wu, Hao A" To: "Wu, Hao A" , "edk2-devel@lists.01.org" CC: "Yao, Jiewen" Thread-Topic: [edk2] [PATCH v1] MinPlatformPkg/Test: [CVE-2017-5753] Fix bounds check bypass Thread-Index: AQHUWH4TRDdtsrAOfUeXG6VSxjcyHaUITHqg Date: Sun, 30 Sep 2018 05:33:27 +0000 Message-ID: References: <20180930052545.8628-1-hao.a.wu@intel.com> In-Reply-To: <20180930052545.8628-1-hao.a.wu@intel.com> Accept-Language: zh-CN, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] MIME-Version: 1.0 Subject: Re: [PATCH v1] MinPlatformPkg/Test: [CVE-2017-5753] Fix bounds check bypass X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Sep 2018 05:33:42 -0000 Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Please ignore this one. Some more information need to be added in the subject line. Another patch mail has been sent out to address this. Best Regards, Hao Wu > -----Original Message----- > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ha= o > Wu > Sent: Sunday, September 30, 2018 1:26 PM > To: edk2-devel@lists.01.org > Cc: Wu, Hao A; Yao, Jiewen > Subject: [edk2] [PATCH v1] MinPlatformPkg/Test: [CVE-2017-5753] Fix bound= s > check bypass >=20 > Speculative execution is used by processor to avoid having to wait for > data to arrive from memory, or for previous operations to finish, the > processor may speculate as to what will be executed. >=20 > If the speculation is incorrect, the speculatively executed instructions > might leave hints such as which memory locations have been brought into > cache. Malicious actors can use the bounds check bypass method (code > gadgets with controlled external inputs) to infer data values that have > been used in speculative operations to reveal secrets which should not > otherwise be accessed. >=20 > This commit will focus on the SMI handler(s) registered within > TestPointCheckLib & TestPointLib and insert AsmLfence API to mitigate the > bounds check bypass issue. >=20 > A. For SMI handler TestPointSmmHandler() within TestPointCheckLib: >=20 > Under "case > TEST_POINT_SMM_COMMUNICATION_FUNC_ID_UEFI_GCD_MAP_INFO:", > 'CommBuffer' (controlled external inputs) is passed into function > TestPointSmmReadyToBootSmmPageProtectionHandler(). >=20 > Within function TestPointSmmReadyToBootSmmPageProtectionHandler(), the > contents in 'CommBuffer' will be copied into 'CommData'. But if the size > and sanity checks for the communication buffer is speculatively bypassed, > '(UINTN)CommData + CommData->UefiMemoryMapOffset)' can potentially > point > to cross boundary area of 'CommData'. This pointer is then passed into > function TestPointCheckSmmCommunicationBuffer() as 'UefiMemoryMap'. >=20 > Within function TestPointCheckSmmCommunicationBuffer(), > 'MemoryMap->PhysicalStart' can be a potential cross boundary access. And > its value can be inferred by function calls sequence: >=20 > TestPointCheckPageTable() via 'BaseAddress' > GetPageTableEntry() via 'BaseAddress'. Then one can observe which part of > the content within arrays 'L4PageTable', 'L3PageTable', 'L2PageTable' or > 'L1PageTable', was brought into cache to possibly reveal the value. >=20 > B. For SMI handler SmmTestPointSmiHandler() within TestPointLib: >=20 > Under "case > SMI_HANDLER_TEST_POINT_COMMAND_GET_DATA_BY_OFFSET:", > 'CommBuffer' (controlled external inputs) is passed into function > SmmTestPointSmiHandlerGetDataByOffset(). >=20 > Within function SmmTestPointSmiHandlerGetDataByOffset(), the contents in > 'CommBuffer' will be copied into 'SmiHandlerTestPointGetDataByOffset'. Bu= t > if the size and sanity checks for the communication buffer is > speculatively bypassed, 'SmiHandlerTestPointGetDataByOffset.DataSize' can > be a potential cross boundary access. >=20 > Then in function SmiHandlerTestPointCopyData(), this value can be inferre= d > by code: > CopyMem( > DataBuffer, > (UINT8 *)InputData + *DataOffset, > (UINTN)*DataSize > ); > One can observe which part of the content within 'DataBuffer' was brought > into cache to possibly reveal the cross bounary access value. >=20 > Hence, this commit adds AsmLfence() calls after the boundary/range checks > of the communication buffer to prevent the speculative execution. >=20 > A more detailed explanation of the purpose of commit is under the > 'Bounds check bypass mitigation' section of the below link: > https://software.intel.com/security-software-guidance/insights/host-firmw= are- > speculative-execution-side-channel-mitigation >=20 > And the document at: > https://software.intel.com/security-software-guidance/api- > app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass- > vulnerabilities.pdf >=20 > Cc: Jiewen Yao > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Hao Wu > --- >=20 > Platform/Intel/MinPlatformPkg/Test/Library/TestPointCheckLib/SmmTestPoint > CheckLib.c | 7 +++++++ >=20 > Platform/Intel/MinPlatformPkg/Test/Library/TestPointLib/SmmTestPointComm > unication.c | 8 +++++++- > 2 files changed, 14 insertions(+), 1 deletion(-) >=20 > diff --git > a/Platform/Intel/MinPlatformPkg/Test/Library/TestPointCheckLib/SmmTestPoi > ntCheckLib.c > b/Platform/Intel/MinPlatformPkg/Test/Library/TestPointCheckLib/SmmTestPoi > ntCheckLib.c > index b40469b278..dc40dae6d5 100644 > --- > a/Platform/Intel/MinPlatformPkg/Test/Library/TestPointCheckLib/SmmTestPoi > ntCheckLib.c > +++ > b/Platform/Intel/MinPlatformPkg/Test/Library/TestPointCheckLib/SmmTestPoi > ntCheckLib.c > @@ -14,6 +14,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY > KIND, EITHER EXPRESS OR IMPLIED. > #include > #include > #include > +#include > #include > #include > #include > @@ -374,6 +375,12 @@ > TestPointSmmReadyToBootSmmPageProtectionHandler ( > } >=20 > if (CommData->UefiMemoryMapSize !=3D 0) { > + // > + // The AsmLfence() call here is to ensure the previous range/content= checks > + // for the CommBuffer (copied in to CommData) have been completed > before > + // calling into TestPointCheckSmmCommunicationBuffer(). > + // > + AsmLfence (); > Result =3D TRUE; >=20 > Status =3D TestPointCheckSmmCommunicationBuffer ( > diff --git > a/Platform/Intel/MinPlatformPkg/Test/Library/TestPointLib/SmmTestPointCom > munication.c > b/Platform/Intel/MinPlatformPkg/Test/Library/TestPointLib/SmmTestPointCom > munication.c > index cce0538832..b4757da046 100644 > --- > a/Platform/Intel/MinPlatformPkg/Test/Library/TestPointLib/SmmTestPointCom > munication.c > +++ > b/Platform/Intel/MinPlatformPkg/Test/Library/TestPointLib/SmmTestPointCom > munication.c > @@ -251,7 +251,13 @@ SmmTestPointSmiHandlerGetDataByOffset ( > SmiHandlerTestPointParameterGetDataByOffset->Header.ReturnStatus =3D > (UINT64)(INT64)(INTN)Status; > goto Done; > } > - > + > + // > + // The AsmLfence() call here is to ensure the previous range/content c= hecks > + // for the CommBuffer have been completed before calling into > + // SmiHandlerTestPointCopyData(). > + // > + AsmLfence (); > SmiHandlerTestPointCopyData ( > Data, > DataSize, > -- > 2.12.0.windows.1 >=20 > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel