rand_pool.c

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#include "crypto/rand.h"
#include <openssl/aes.h>
 
#include <Uefi.h>
#include <Library/RngLib.h>
 
STATIC
BOOLEAN
EFIAPI
RandGetBytes (
  IN UINTN   Length,
  OUT UINT8  *RandBuffer
  )
{
  BOOLEAN  Ret;
  UINT64   TempRand;
 
  Ret = FALSE;
 
  if (RandBuffer == NULL) {
    DEBUG ((DEBUG_ERROR, "[OPENSSL_RAND_POOL] NULL RandBuffer. No random numbers are generated and your system is not secure\n"));
    ASSERT (RandBuffer != NULL); // Since we can't generate random numbers, we should assert. Otherwise we will just blow up later.
    return Ret;
  }
 
  while (Length > 0) {
    // Use RngLib to get random number
    Ret = GetRandomNumber64 (&TempRand);
 
    if (!Ret) {
      return Ret;
    }
 
    if (Length >= sizeof (TempRand)) {
      *((UINT64 *)RandBuffer) = TempRand;
      RandBuffer             += sizeof (UINT64);
      Length                 -= sizeof (TempRand);
    } else {
      CopyMem (RandBuffer, &TempRand, Length);
      Length = 0;
    }
  }
 
  return Ret;
}
 
/*
 * Add random bytes to the pool to acquire requested amount of entropy
 *
 * This function is platform specific and tries to acquire the requested
 * amount of entropy by polling platform specific entropy sources.
 *
 * This is OpenSSL required interface.
 */
size_t
ossl_pool_acquire_entropy (
  RAND_POOL  *pool
  )
{
  BOOLEAN        Ret;
  size_t         Bytes_needed;
  unsigned char  *Buffer;
 
  Bytes_needed = ossl_rand_pool_bytes_needed (pool, 1 /*entropy_factor*/);
  if (Bytes_needed > 0) {
    Buffer = ossl_rand_pool_add_begin (pool, Bytes_needed);
 
    if (Buffer != NULL) {
      Ret = RandGetBytes (Bytes_needed, Buffer);
      if (FALSE == Ret) {
        ossl_rand_pool_add_end (pool, 0, 0);
      } else {
        ossl_rand_pool_add_end (pool, Bytes_needed, 8 * Bytes_needed);
      }
    }
  }
 
  return ossl_rand_pool_entropy_available (pool);
}
 
/*
 * Implementation for UEFI
 *
 * This is OpenSSL required interface.
 */
int
ossl_pool_add_nonce_data (
  RAND_POOL  *pool
  )
{
  UINT8  data[16];
 
  RandGetBytes (sizeof (data), data);
 
  return ossl_rand_pool_add (pool, (unsigned char *)&data, sizeof (data), 0);
}
 
/*
 * Implementation for UEFI
 *
 * This is OpenSSL required interface.
 */
int
rand_pool_add_additional_data (
  RAND_POOL  *pool
  )
{
  UINT8  data[16];
 
  RandGetBytes (sizeof (data), data);
 
  return ossl_rand_pool_add (pool, (unsigned char *)&data, sizeof (data), 0);
}
 
/*
 * Dummy Implementation for UEFI
 *
 * This is OpenSSL required interface.
 */
int
ossl_rand_pool_init (
  VOID
  )
{
  return 1;
}
 
/*
 * Dummy Implementation for UEFI
 *
 * This is OpenSSL required interface.
 */
VOID
ossl_rand_pool_cleanup (
  VOID
  )
{
}
 
/*
 * Dummy Implementation for UEFI
 *
 * This is OpenSSL required interface.
 */
VOID
ossl_rand_pool_keep_random_devices_open (
  int  keep
  )
{
}