RngDxe.c

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#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/RngLib.h>
#include <Protocol/Rng.h>
 
#include "RngDxeInternals.h"
 
//
// Array containing the validated Rng algorithm.
// The entry with the lowest index will be the default algorithm.
//
UINTN              mAvailableAlgoArrayCount;
EFI_RNG_ALGORITHM  *mAvailableAlgoArray;
 
//
// The Random Number Generator (RNG) protocol
//
EFI_RNG_PROTOCOL  mRngRdRand = {
  RngGetInfo,
  RngGetRNG
};
 
EFI_STATUS
EFIAPI
RngDriverEntry (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS  Status;
  EFI_HANDLE  Handle;
 
  //
  // Get the list of available algorithm.
  //
  Status = GetAvailableAlgorithms ();
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  if (mAvailableAlgoArrayCount == 0) {
    return EFI_REQUEST_UNLOAD_IMAGE;
  }
 
  //
  // Install UEFI RNG (Random Number Generator) Protocol
  //
  Handle = NULL;
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Handle,
                  &gEfiRngProtocolGuid,
                  &mRngRdRand,
                  NULL
                  );
  if (EFI_ERROR (Status)) {
    FreeAvailableAlgorithms ();
  }
 
  return Status;
}
 
EFI_STATUS
EFIAPI
RngDriverUnLoad (
  IN EFI_HANDLE  ImageHandle
  )
{
  //
  // Free the list of available algorithm.
  //
  FreeAvailableAlgorithms ();
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
RngGetBytes (
  IN UINTN   Length,
  OUT UINT8  *RandBuffer
  )
{
  BOOLEAN  IsRandom;
  UINT64   TempRand[2];
 
  while (Length > 0) {
    IsRandom = GetRandomNumber128 (TempRand);
    if (!IsRandom) {
      return EFI_NOT_READY;
    }
 
    if (Length >= sizeof (TempRand)) {
      WriteUnaligned64 ((UINT64 *)RandBuffer, TempRand[0]);
      RandBuffer += sizeof (UINT64);
      WriteUnaligned64 ((UINT64 *)RandBuffer, TempRand[1]);
      RandBuffer += sizeof (UINT64);
      Length     -= sizeof (TempRand);
    } else {
      CopyMem (RandBuffer, TempRand, Length);
      Length = 0;
    }
  }
 
  return EFI_SUCCESS;
}