SecurityPkg/RandomNumberGenerator/RngDxe/ArmRngDxe.c

   1 /** @file
   2   RNG Driver to produce the UEFI Random Number Generator protocol.
   3
   4   The driver can use RNDR instruction (through the RngLib and if FEAT_RNG is
   5   present) to produce random numbers. It also uses the Arm FW-TRNG interface
   6   to implement EFI_RNG_ALGORITHM_RAW.
   7
   8   RNG Algorithms defined in UEFI 2.4:
   9    - EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID
  10    - EFI_RNG_ALGORITHM_RAW
  11    - EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID
  12    - EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID
  13    - EFI_RNG_ALGORITHM_X9_31_3DES_GUID        - Unsupported
  14    - EFI_RNG_ALGORITHM_X9_31_AES_GUID         - Unsupported
  15
  16   Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
  17   Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
  18   (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
  19   Copyright (c) 2021 - 2022, Arm Limited. All rights reserved.<BR>
  20
  21   SPDX-License-Identifier: BSD-2-Clause-Patent
  22
  23 **/
  24
  25 #include <Library/BaseLib.h>
  26 #include <Library/BaseMemoryLib.h>
  27 #include <Library/DebugLib.h>
  28 #include <Library/MemoryAllocationLib.h>
  29 #include <Library/UefiBootServicesTableLib.h>
  30 #include <Library/RngLib.h>
  31 #include <Protocol/Rng.h>
  32
  33 #include "RngDxeInternals.h"
  34
  35 /** Free mAvailableAlgoArray.
  36 **/
  37 VOID
  38 EFIAPI
  39 FreeAvailableAlgorithms (
  40   VOID
  41   )
  42 {
  43   FreePool (mAvailableAlgoArray);
  44   return;
  45 }
  46
  47 /**
  48   Produces and returns an RNG value using either the default or specified RNG algorithm.
  49
  50   @param[in]  This                    A pointer to the EFI_RNG_PROTOCOL instance.
  51   @param[in]  RNGAlgorithm            A pointer to the EFI_RNG_ALGORITHM that identifies the RNG
  52                                       algorithm to use. May be NULL in which case the function will
  53                                       use its default RNG algorithm.
  54   @param[in]  RNGValueLength          The length in bytes of the memory buffer pointed to by
  55                                       RNGValue. The driver shall return exactly this numbers of bytes.
  56   @param[out] RNGValue                A caller-allocated memory buffer filled by the driver with the
  57                                       resulting RNG value.
  58
  59   @retval EFI_SUCCESS                 The RNG value was returned successfully.
  60   @retval EFI_UNSUPPORTED             The algorithm specified by RNGAlgorithm is not supported by
  61                                       this driver.
  62   @retval EFI_DEVICE_ERROR            An RNG value could not be retrieved due to a hardware or
  63                                       firmware error.
  64   @retval EFI_NOT_READY               There is not enough random data available to satisfy the length
  65                                       requested by RNGValueLength.
  66   @retval EFI_INVALID_PARAMETER       RNGValue is NULL or RNGValueLength is zero.
  67
  68 **/
  69 EFI_STATUS
  70 EFIAPI
  71 RngGetRNG (
  72   IN EFI_RNG_PROTOCOL   *This,
  73   IN EFI_RNG_ALGORITHM  *RNGAlgorithm  OPTIONAL,
  74   IN UINTN              RNGValueLength,
  75   OUT UINT8             *RNGValue
  76   )
  77 {
  78   EFI_STATUS  Status;
  79   UINTN       Index;
  80
  81   if ((This == NULL) || (RNGValueLength == 0) || (RNGValue == NULL)) {
  82     return EFI_INVALID_PARAMETER;
  83   }
  84
  85   if (RNGAlgorithm == NULL) {
  86     //
  87     // Use the default RNG algorithm if RNGAlgorithm is NULL.
  88     //
  89     for (Index = 0; Index < mAvailableAlgoArrayCount; Index++) {
  90       if (!IsZeroGuid (&mAvailableAlgoArray[Index])) {
  91         RNGAlgorithm = &mAvailableAlgoArray[Index];
  92         goto FoundAlgo;
  93       }
  94     }
  95
  96     if (Index == mAvailableAlgoArrayCount) {
  97       // No algorithm available.
  98       ASSERT (Index != mAvailableAlgoArrayCount);
  99       return EFI_DEVICE_ERROR;
 100     }
 101   }
 102
 103 FoundAlgo:
 104   if (CompareGuid (RNGAlgorithm, PcdGetPtr (PcdCpuRngSupportedAlgorithm))) {
 105     Status = RngGetBytes (RNGValueLength, RNGValue);
 106     return Status;
 107   }
 108
 109   // Raw algorithm (Trng)
 110   if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
 111     return GenerateEntropy (RNGValueLength, RNGValue);
 112   }
 113
 114   //
 115   // Other algorithms are unsupported by this driver.
 116   //
 117   return EFI_UNSUPPORTED;
 118 }
 119
 120 /**
 121   Returns information about the random number generation implementation.
 122
 123   @param[in]     This                 A pointer to the EFI_RNG_PROTOCOL instance.
 124   @param[in,out] RNGAlgorithmListSize On input, the size in bytes of RNGAlgorithmList.
 125                                       On output with a return code of EFI_SUCCESS, the size
 126                                       in bytes of the data returned in RNGAlgorithmList. On output
 127                                       with a return code of EFI_BUFFER_TOO_SMALL,
 128                                       the size of RNGAlgorithmList required to obtain the list.
 129   @param[out] RNGAlgorithmList        A caller-allocated memory buffer filled by the driver
 130                                       with one EFI_RNG_ALGORITHM element for each supported
 131                                       RNG algorithm. The list must not change across multiple
 132                                       calls to the same driver. The first algorithm in the list
 133                                       is the default algorithm for the driver.
 134
 135   @retval EFI_SUCCESS                 The RNG algorithm list was returned successfully.
 136   @retval EFI_UNSUPPORTED             The services is not supported by this driver.
 137   @retval EFI_DEVICE_ERROR            The list of algorithms could not be retrieved due to a
 138                                       hardware or firmware error.
 139   @retval EFI_INVALID_PARAMETER       One or more of the parameters are incorrect.
 140   @retval EFI_BUFFER_TOO_SMALL        The buffer RNGAlgorithmList is too small to hold the result.
 141
 142 **/
 143 EFI_STATUS
 144 EFIAPI
 145 RngGetInfo (
 146   IN EFI_RNG_PROTOCOL    *This,
 147   IN OUT UINTN           *RNGAlgorithmListSize,
 148   OUT EFI_RNG_ALGORITHM  *RNGAlgorithmList
 149   )
 150 {
 151   UINTN  RequiredSize;
 152
 153   if ((This == NULL) || (RNGAlgorithmListSize == NULL)) {
 154     return EFI_INVALID_PARAMETER;
 155   }
 156
 157   RequiredSize = mAvailableAlgoArrayCount * sizeof (EFI_RNG_ALGORITHM);
 158
 159   if (RequiredSize == 0) {
 160     // No supported algorithms found.
 161     return EFI_UNSUPPORTED;
 162   }
 163
 164   if (*RNGAlgorithmListSize < RequiredSize) {
 165     *RNGAlgorithmListSize = RequiredSize;
 166     return EFI_BUFFER_TOO_SMALL;
 167   }
 168
 169   if (RNGAlgorithmList == NULL) {
 170     return EFI_INVALID_PARAMETER;
 171   }
 172
 173   // There is no gap in the array, so copy the block.
 174   CopyMem (RNGAlgorithmList, mAvailableAlgoArray, RequiredSize);
 175   *RNGAlgorithmListSize = RequiredSize;
 176   return EFI_SUCCESS;
 177 }