cb54cd2463
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194 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. 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. This commit will focus on the SMI handler(s) registered within the FaultTolerantWriteDxe driver and insert AsmLfence API to mitigate the bounds check bypass issue. For SMI handler SmmFaultTolerantWriteHandler(): Under "case FTW_FUNCTION_WRITE:", 'SmmFtwWriteHeader->Length' can be a potential cross boundary access of the 'CommBuffer' (controlled external inputs) during speculative execution. This cross boundary access is later passed as parameter 'Length' into function FtwWrite(). Within function FtwWrite(), the value of 'Length' can be inferred by code: "CopyMem (MyBuffer + Offset, Buffer, Length);". One can observe which part of the content within 'Buffer' was brought into cache to possibly reveal the value of 'Length'. Hence, this commit adds a AsmLfence() after the boundary/range checks of 'CommBuffer' to prevent the speculative execution. 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-firmware-speculative-execution-side-channel-mitigation And the document at: https://software.intel.com/security-software-guidance/api-app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass-vulnerabilities.pdf Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Hao Wu <hao.a.wu@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com> Acked-by: Laszlo Ersek <lersek@redhat.com> Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
100 lines
3.4 KiB
INI
100 lines
3.4 KiB
INI
## @file
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# Fault Tolerant Write Smm Driver.
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#
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# This driver installs SMM Fault Tolerant Write (FTW) protocol, which provides fault
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# tolerant write capability in SMM environment for block devices. Its implementation
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# depends on the full functionality SMM FVB protocol that support read, write/erase
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# flash access.
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#
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# Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
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#
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# This program and the accompanying materials
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# are licensed and made available under the terms and conditions of the BSD License
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# which accompanies this distribution. The full text of the license may be found at
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# http://opensource.org/licenses/bsd-license.php
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# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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#
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##
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[Defines]
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INF_VERSION = 0x00010005
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BASE_NAME = SmmFaultTolerantWriteDxe
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MODULE_UNI_FILE = SmmFaultTolerantWriteDxe.uni
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FILE_GUID = 470CB248-E8AC-473c-BB4F-81069A1FE6FD
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MODULE_TYPE = DXE_SMM_DRIVER
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VERSION_STRING = 1.0
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PI_SPECIFICATION_VERSION = 0x0001000A
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ENTRY_POINT = SmmFaultTolerantWriteInitialize
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#
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# The following information is for reference only and not required by the build tools.
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#
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# VALID_ARCHITECTURES = IA32 X64
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#
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[Sources]
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FtwMisc.c
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UpdateWorkingBlock.c
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FaultTolerantWrite.c
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FaultTolerantWriteSmm.c
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FaultTolerantWrite.h
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FaultTolerantWriteSmmCommon.h
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[Packages]
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MdePkg/MdePkg.dec
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MdeModulePkg/MdeModulePkg.dec
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[LibraryClasses]
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SmmServicesTableLib
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MemoryAllocationLib
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BaseMemoryLib
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UefiDriverEntryPoint
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DebugLib
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UefiLib
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PcdLib
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ReportStatusCodeLib
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SmmMemLib
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BaseLib
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[Guids]
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#
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# Signature in EFI_FAULT_TOLERANT_WORKING_BLOCK_HEADER
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#
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## CONSUMES ## GUID
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## PRODUCES ## GUID
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gEdkiiWorkingBlockSignatureGuid
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[Protocols]
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gEfiSmmSwapAddressRangeProtocolGuid | gEfiMdeModulePkgTokenSpaceGuid.PcdFullFtwServiceEnable ## SOMETIMES_CONSUMES
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## NOTIFY
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## CONSUMES
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gEfiSmmFirmwareVolumeBlockProtocolGuid
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## PRODUCES
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## UNDEFINED # SmiHandlerRegister
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gEfiSmmFaultTolerantWriteProtocolGuid
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gEfiSmmEndOfDxeProtocolGuid ## CONSUMES
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[FeaturePcd]
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gEfiMdeModulePkgTokenSpaceGuid.PcdFullFtwServiceEnable ## CONSUMES
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[Pcd]
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase ## SOMETIMES_CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase64 ## CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingSize ## CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase ## SOMETIMES_CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase64 ## CONSUMES
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareSize ## CONSUMES
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#
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# gBS->CalculateCrc32() is consumed in EntryPoint.
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# PI spec said: When the DXE Foundation is notified that the EFI_RUNTIME_ARCH_PROTOCOL
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# has been installed, then the Boot Service CalculateCrc32() is available.
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# So add gEfiRuntimeArchProtocolGuid Depex here.
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#
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[Depex]
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gEfiSmmFirmwareVolumeBlockProtocolGuid AND gEfiRuntimeArchProtocolGuid
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[UserExtensions.TianoCore."ExtraFiles"]
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SmmFaultTolerantWriteDxeExtra.uni
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