ArmRngDxe.c

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#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/RngLib.h>
#include <Protocol/Rng.h>
 
#include "RngDxeInternals.h"
 
VOID
EFIAPI
FreeAvailableAlgorithms (
  VOID
  )
{
  mAvailableAlgoArrayCount = 0;
  FreePool (mAvailableAlgoArray);
  return;
}
 
EFI_STATUS
EFIAPI
RngGetRNG (
  IN EFI_RNG_PROTOCOL   *This,
  IN EFI_RNG_ALGORITHM  *RNGAlgorithm  OPTIONAL,
  IN UINTN              RNGValueLength,
  OUT UINT8             *RNGValue
  )
{
  EFI_STATUS  Status;
  GUID        RngGuid;
 
  if ((This == NULL) || (RNGValueLength == 0) || (RNGValue == NULL)) {
    return EFI_INVALID_PARAMETER;
  }
 
  if (RNGAlgorithm == NULL) {
    //
    // Use the default RNG algorithm if RNGAlgorithm is NULL.
    //
    if (mAvailableAlgoArrayCount != 0) {
      RNGAlgorithm = &mAvailableAlgoArray[0];
    } else {
      return EFI_UNSUPPORTED;
    }
  }
 
  Status = GetRngGuid (&RngGuid);
  if (!EFI_ERROR (Status) &&
      CompareGuid (RNGAlgorithm, &RngGuid))
  {
    Status = RngGetBytes (RNGValueLength, RNGValue);
    return Status;
  }
 
  // Raw algorithm (Trng)
  if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
    return GenerateEntropy (RNGValueLength, RNGValue);
  }
 
  //
  // Other algorithms are unsupported by this driver.
  //
  return EFI_UNSUPPORTED;
}
 
EFI_STATUS
EFIAPI
RngGetInfo (
  IN EFI_RNG_PROTOCOL    *This,
  IN OUT UINTN           *RNGAlgorithmListSize,
  OUT EFI_RNG_ALGORITHM  *RNGAlgorithmList
  )
{
  UINTN  RequiredSize;
 
  if ((This == NULL) || (RNGAlgorithmListSize == NULL)) {
    return EFI_INVALID_PARAMETER;
  }
 
  RequiredSize = mAvailableAlgoArrayCount * sizeof (EFI_RNG_ALGORITHM);
 
  if (RequiredSize == 0) {
    // No supported algorithms found.
    return EFI_UNSUPPORTED;
  }
 
  if (*RNGAlgorithmListSize < RequiredSize) {
    *RNGAlgorithmListSize = RequiredSize;
    return EFI_BUFFER_TOO_SMALL;
  }
 
  if (RNGAlgorithmList == NULL) {
    return EFI_INVALID_PARAMETER;
  }
 
  // There is no gap in the array, so copy the block.
  CopyMem (RNGAlgorithmList, mAvailableAlgoArray, RequiredSize);
  *RNGAlgorithmListSize = RequiredSize;
  return EFI_SUCCESS;
}