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125 lines
4.0 KiB
C
125 lines
4.0 KiB
C
/** @file
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TCG MOR (Memory Overwrite Request) Lock Control support (DXE version).
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This module clears MemoryOverwriteRequestControlLock variable to indicate
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MOR lock control unsupported.
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Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <PiDxe.h>
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#include <Guid/MemoryOverwriteControl.h>
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#include <IndustryStandard/MemoryOverwriteRequestControlLock.h>
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#include <Library/DebugLib.h>
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#include <Library/BaseLib.h>
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#include <Library/BaseMemoryLib.h>
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#include "Variable.h"
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extern EDKII_VARIABLE_LOCK_PROTOCOL mVariableLock;
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/**
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This service is an MOR/MorLock checker handler for the SetVariable().
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@param[in] VariableName the name of the vendor's variable, as a
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Null-Terminated Unicode String
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@param[in] VendorGuid Unify identifier for vendor.
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@param[in] Attributes Attributes bitmask to set for the variable.
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@param[in] DataSize The size in bytes of Data-Buffer.
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@param[in] Data Point to the content of the variable.
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@retval EFI_SUCCESS The MOR/MorLock check pass, and Variable
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driver can store the variable data.
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@retval EFI_INVALID_PARAMETER The MOR/MorLock data or data size or
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attributes is not allowed for MOR variable.
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@retval EFI_ACCESS_DENIED The MOR/MorLock is locked.
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@retval EFI_ALREADY_STARTED The MorLock variable is handled inside this
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function. Variable driver can just return
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EFI_SUCCESS.
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**/
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EFI_STATUS
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SetVariableCheckHandlerMor (
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IN CHAR16 *VariableName,
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IN EFI_GUID *VendorGuid,
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IN UINT32 Attributes,
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IN UINTN DataSize,
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IN VOID *Data
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)
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{
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//
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// Just let it pass. No need provide protection for DXE version.
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//
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return EFI_SUCCESS;
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}
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/**
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Initialization for MOR Control Lock.
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@retval EFI_SUCCESS MorLock initialization success.
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@return Others Some error occurs.
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**/
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EFI_STATUS
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MorLockInit (
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VOID
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)
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{
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//
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// Always clear variable to report unsupported to OS.
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// The reason is that the DXE version is not proper to provide *protection*.
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// BIOS should use SMM version variable driver to provide such capability.
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//
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VariableServiceSetVariable (
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MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
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&gEfiMemoryOverwriteRequestControlLockGuid,
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0, // Attributes
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0, // DataSize
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NULL // Data
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);
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//
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// Need set this variable to be read-only to prevent other module set it.
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//
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VariableLockRequestToLock (&mVariableLock, MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME, &gEfiMemoryOverwriteRequestControlLockGuid);
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//
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// The MOR variable can effectively improve platform security only when the
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// MorLock variable protects the MOR variable. In turn MorLock cannot be made
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// secure without SMM support in the platform firmware (see above).
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//
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// Thus, delete the MOR variable, should it exist for any reason (some OSes
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// are known to create MOR unintentionally, in an attempt to set it), then
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// also lock the MOR variable, in order to prevent other modules from
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// creating it.
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//
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VariableServiceSetVariable (
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MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
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&gEfiMemoryOverwriteControlDataGuid,
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0, // Attributes
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0, // DataSize
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NULL // Data
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);
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VariableLockRequestToLock (
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&mVariableLock,
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MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
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&gEfiMemoryOverwriteControlDataGuid
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);
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return EFI_SUCCESS;
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}
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/**
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Delayed initialization for MOR Control Lock at EndOfDxe.
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This function performs any operations queued by MorLockInit().
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**/
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VOID
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MorLockInitAtEndOfDxe (
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VOID
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)
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{
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//
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// Do nothing.
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//
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}
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