SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c

   1 /** @file
   2   RNG Driver to produce the UEFI Random Number Generator protocol.
   3
   4   The driver will use the new RDRAND instruction to produce high-quality, high-performance
   5   entropy and random number.
   6
   7   RNG Algorithms defined in UEFI 2.4:
   8    - EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID  - Supported
   9      (RDRAND implements a hardware NIST SP800-90 AES-CTR-256 based DRBG)
  10    - EFI_RNG_ALGORITHM_RAW                    - Supported
  11      (Structuring RDRAND invocation can be guaranteed as high-quality entropy source)
  12    - EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID - Unsupported
  13    - EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID - Unsupported
  14    - EFI_RNG_ALGORITHM_X9_31_3DES_GUID        - Unsupported
  15    - EFI_RNG_ALGORITHM_X9_31_AES_GUID         - Unsupported
  16
  17   Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
  18   (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
  19   SPDX-License-Identifier: BSD-2-Clause-Patent
  20
  21 **/
  22
  23 #include "RdRand.h"
  24 #include "RngDxeInternals.h"
  25
  26 /**
  27   Produces and returns an RNG value using either the default or specified RNG algorithm.
  28
  29   @param[in]  This                    A pointer to the EFI_RNG_PROTOCOL instance.
  30   @param[in]  RNGAlgorithm            A pointer to the EFI_RNG_ALGORITHM that identifies the RNG
  31                                       algorithm to use. May be NULL in which case the function will
  32                                       use its default RNG algorithm.
  33   @param[in]  RNGValueLength          The length in bytes of the memory buffer pointed to by
  34                                       RNGValue. The driver shall return exactly this numbers of bytes.
  35   @param[out] RNGValue                A caller-allocated memory buffer filled by the driver with the
  36                                       resulting RNG value.
  37
  38   @retval EFI_SUCCESS                 The RNG value was returned successfully.
  39   @retval EFI_UNSUPPORTED             The algorithm specified by RNGAlgorithm is not supported by
  40                                       this driver.
  41   @retval EFI_DEVICE_ERROR            An RNG value could not be retrieved due to a hardware or
  42                                       firmware error.
  43   @retval EFI_NOT_READY               There is not enough random data available to satisfy the length
  44                                       requested by RNGValueLength.
  45   @retval EFI_INVALID_PARAMETER       RNGValue is NULL or RNGValueLength is zero.
  46
  47 **/
  48 EFI_STATUS
  49 EFIAPI
  50 RngGetRNG (
  51   IN EFI_RNG_PROTOCOL            *This,
  52   IN EFI_RNG_ALGORITHM           *RNGAlgorithm  OPTIONAL,
  53   IN UINTN                       RNGValueLength,
  54   OUT UINT8                      *RNGValue
  55   )
  56 {
  57   EFI_STATUS    Status;
  58
  59   if ((RNGValueLength == 0) || (RNGValue == NULL)) {
  60     return EFI_INVALID_PARAMETER;
  61   }
  62
  63   Status = EFI_UNSUPPORTED;
  64   if (RNGAlgorithm == NULL) {
  65     //
  66     // Use the default RNG algorithm if RNGAlgorithm is NULL.
  67     //
  68     RNGAlgorithm = &gEfiRngAlgorithmSp80090Ctr256Guid;
  69   }
  70
  71   //
  72   // NIST SP800-90-AES-CTR-256 supported by RDRAND
  73   //
  74   if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmSp80090Ctr256Guid)) {
  75     Status = RngGetBytes (RNGValueLength, RNGValue);
  76     return Status;
  77   }
  78
  79   //
  80   // The "raw" algorithm is intended to provide entropy directly
  81   //
  82   if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
  83     //
  84     // When a DRBG is used on the output of a entropy source,
  85     // its security level must be at least 256 bits according to UEFI Spec.
  86     //
  87     if (RNGValueLength < 32) {
  88       return EFI_INVALID_PARAMETER;
  89     }
  90
  91     Status = RdRandGenerateEntropy (RNGValueLength, RNGValue);
  92     return Status;
  93   }
  94
  95   //
  96   // Other algorithms were unsupported by this driver.
  97   //
  98   return Status;
  99 }
 100
 101 /**
 102   Returns information about the random number generation implementation.
 103
 104   @param[in,out] RNGAlgorithmListSize On input, the size in bytes of RNGAlgorithmList.
 105                                       On output with a return code of EFI_SUCCESS, the size
 106                                       in bytes of the data returned in RNGAlgorithmList. On output
 107                                       with a return code of EFI_BUFFER_TOO_SMALL,
 108                                       the size of RNGAlgorithmList required to obtain the list.
 109   @param[out] RNGAlgorithmList        A caller-allocated memory buffer filled by the driver
 110                                       with one EFI_RNG_ALGORITHM element for each supported
 111                                       RNG algorithm. The list must not change across multiple
 112                                       calls to the same driver. The first algorithm in the list
 113                                       is the default algorithm for the driver.
 114
 115   @retval EFI_SUCCESS                 The RNG algorithm list was returned successfully.
 116   @retval EFI_BUFFER_TOO_SMALL        The buffer RNGAlgorithmList is too small to hold the result.
 117
 118 **/
 119 UINTN
 120 EFIAPI
 121 ArchGetSupportedRngAlgorithms (
 122   IN OUT UINTN                     *RNGAlgorithmListSize,
 123   OUT    EFI_RNG_ALGORITHM         *RNGAlgorithmList
 124   )
 125 {
 126   UINTN RequiredSize;
 127   EFI_RNG_ALGORITHM *CpuRngSupportedAlgorithm;
 128
 129   RequiredSize = 2 * sizeof (EFI_RNG_ALGORITHM);
 130
 131   if (*RNGAlgorithmListSize < RequiredSize) {
 132     *RNGAlgorithmListSize = RequiredSize;
 133     return EFI_BUFFER_TOO_SMALL;
 134   }
 135
 136   CpuRngSupportedAlgorithm = PcdGetPtr (PcdCpuRngSupportedAlgorithm);
 137
 138   CopyMem(&RNGAlgorithmList[0], CpuRngSupportedAlgorithm, sizeof (EFI_RNG_ALGORITHM));
 139
 140   // x86 platforms also support EFI_RNG_ALGORITHM_RAW via RDSEED
 141   CopyMem(&RNGAlgorithmList[1], &gEfiRngAlgorithmRaw, sizeof (EFI_RNG_ALGORITHM));
 142
 143   *RNGAlgorithmListSize = RequiredSize;
 144   return EFI_SUCCESS;
 145 }