RngDxe.c

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#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/RngLib.h>
 
#include "RngDxeInternals.h"
 
//
// Count of Rng algorithms.
//
#define RNG_ALGORITHM_COUNT  2
 
EFI_STATUS
EFIAPI
GetAvailableAlgorithms (
  VOID
  )
{
  UINT64  RngTest;
 
  if (GetRandomNumber64 (&RngTest)) {
    mAvailableAlgoArrayCount = RNG_ALGORITHM_COUNT;
  }
 
  return EFI_SUCCESS;
}
 
VOID
EFIAPI
FreeAvailableAlgorithms (
  VOID
  )
{
  mAvailableAlgoArrayCount = 0;
  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;
 
  if ((This == NULL) || (RNGValueLength == 0) || (RNGValue == NULL)) {
    return EFI_INVALID_PARAMETER;
  }
 
  Status = EFI_UNSUPPORTED;
  if (RNGAlgorithm == NULL) {
    //
    // Use the default RNG algorithm if RNGAlgorithm is NULL.
    //
    RNGAlgorithm = &gEfiRngAlgorithmSp80090Ctr256Guid;
  }
 
  //
  // NIST SP800-90-AES-CTR-256 supported by RDRAND
  //
  if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmSp80090Ctr256Guid)) {
    Status = RngGetBytes (RNGValueLength, RNGValue);
    return Status;
  }
 
  //
  // The "raw" algorithm is intended to provide entropy directly
  //
  if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
    Status = GenerateEntropy (RNGValueLength, RNGValue);
    return Status;
  }
 
  //
  // Other algorithms were unsupported by this driver.
  //
  return Status;
}
 
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 = RNG_ALGORITHM_COUNT * sizeof (EFI_RNG_ALGORITHM);
 
  if (*RNGAlgorithmListSize < RequiredSize) {
    *RNGAlgorithmListSize = RequiredSize;
    return EFI_BUFFER_TOO_SMALL;
  }
 
  if (RNGAlgorithmList == NULL) {
    return EFI_INVALID_PARAMETER;
  }
 
  CopyMem (&RNGAlgorithmList[0], &gEfiRngAlgorithmSp80090Ctr256Guid, sizeof (EFI_RNG_ALGORITHM));
 
  // x86 platforms also support EFI_RNG_ALGORITHM_RAW via RDSEED
  CopyMem (&RNGAlgorithmList[1], &gEfiRngAlgorithmRaw, sizeof (EFI_RNG_ALGORITHM));
 
  *RNGAlgorithmListSize = RequiredSize;
  return EFI_SUCCESS;
}