TcgMorLock.c

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#include <PiDxe.h>
#include <Guid/MemoryOverwriteControl.h>
#include <IndustryStandard/MemoryOverwriteRequestControlLock.h>
#include <Library/DebugLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include "TcgMorLock.h"
 
typedef struct {
  CHAR16      *VariableName;
  EFI_GUID    *VendorGuid;
} VARIABLE_TYPE;
 
VARIABLE_TYPE  mMorVariableType[] = {
  { MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,     &gEfiMemoryOverwriteControlDataGuid        },
  { MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME, &gEfiMemoryOverwriteRequestControlLockGuid },
};
 
BOOLEAN
IsAnyMorVariable (
  IN CHAR16    *VariableName,
  IN EFI_GUID  *VendorGuid
  )
{
  UINTN  Index;
 
  for (Index = 0; Index < sizeof (mMorVariableType)/sizeof (mMorVariableType[0]); Index++) {
    if ((StrCmp (VariableName, mMorVariableType[Index].VariableName) == 0) &&
        (CompareGuid (VendorGuid, mMorVariableType[Index].VendorGuid)))
    {
      return TRUE;
    }
  }
 
  return FALSE;
}
 
BOOLEAN
IsMorLockVariable (
  IN CHAR16    *VariableName,
  IN EFI_GUID  *VendorGuid
  )
{
  if ((StrCmp (VariableName, MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME) == 0) &&
      (CompareGuid (VendorGuid, &gEfiMemoryOverwriteRequestControlLockGuid)))
  {
    return TRUE;
  }
 
  return FALSE;
}
 
EFI_STATUS
EFIAPI
SetVariableCheckHandlerMor (
  IN CHAR16    *VariableName,
  IN EFI_GUID  *VendorGuid,
  IN UINT32    Attributes,
  IN UINTN     DataSize,
  IN VOID      *Data
  )
{
  UINTN       MorLockDataSize;
  BOOLEAN     MorLock;
  EFI_STATUS  Status;
 
  //
  // do not handle non-MOR variable
  //
  if (!IsAnyMorVariable (VariableName, VendorGuid)) {
    return EFI_SUCCESS;
  }
 
  MorLockDataSize = sizeof (MorLock);
  Status          = InternalGetVariable (
                      MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
                      &gEfiMemoryOverwriteRequestControlLockGuid,
                      NULL,
                      &MorLockDataSize,
                      &MorLock
                      );
  if (!EFI_ERROR (Status) && MorLock) {
    //
    // If lock, deny access
    //
    return EFI_INVALID_PARAMETER;
  }
 
  //
  // Delete not OK
  //
  if ((DataSize != sizeof (UINT8)) || (Data == NULL) || (Attributes == 0)) {
    return EFI_INVALID_PARAMETER;
  }
 
  //
  // check format
  //
  if (IsMorLockVariable (VariableName, VendorGuid)) {
    //
    // set to any other value not OK
    //
    if ((*(UINT8 *)Data != 1) && (*(UINT8 *)Data != 0)) {
      return EFI_INVALID_PARAMETER;
    }
  }
 
  //
  // Or grant access
  //
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
MorLockDriverInit (
  VOID
  )
{
  EFI_STATUS  Status;
  UINT8       Data;
 
  Data   = 0;
  Status = InternalSetVariable (
             MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
             &gEfiMemoryOverwriteRequestControlLockGuid,
             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
             1,
             &Data
             );
  return Status;
}