SecurityPkg/RngDxe: Add AArch64 RawAlgorithm support through ArmTrngLib

Bugzilla: 3668 (https://bugzilla.tianocore.org/show_bug.cgi?id=3668)

RawAlgorithm is used to provide access to entropy that is suitable
for cryptographic applications. Therefore, add RawAlgorithm support
that provides access to entropy using the ArmTrngLib.

Also remove unused UefiBootServicesTableLib library inclusion
and Status variable.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>

3 files changed, 100 insertions, 4 deletions

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c
index 09a5924a69..ceddc8f08a 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c
@@ -1,11 +1,13 @@
 /** @file

   RNG Driver to produce the UEFI Random Number Generator protocol.

 

-  The driver will use the RNDR instruction to produce random numbers.

+  The driver can use RNDR instruction (through the RngLib and if FEAT_RNG is

+  present) to produce random numbers. It also uses the Arm FW-TRNG interface

+  to implement EFI_RNG_ALGORITHM_RAW.

 

   RNG Algorithms defined in UEFI 2.4:

    - EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID

-   - EFI_RNG_ALGORITHM_RAW                    - Unsupported

+   - EFI_RNG_ALGORITHM_RAW

    - EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID

    - EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID

    - EFI_RNG_ALGORITHM_X9_31_3DES_GUID        - Unsupported

@@ -26,12 +28,14 @@
 #include <Library/MemoryAllocationLib.h>

 #include <Library/UefiBootServicesTableLib.h>

 #include <Library/RngLib.h>

+#include <Library/DebugLib.h>

+#include <Library/ArmTrngLib.h>

 #include <Protocol/Rng.h>

 

 #include "RngDxeInternals.h"

 

 // Maximum number of Rng algorithms.

-#define RNG_AVAILABLE_ALGO_MAX  1

+#define RNG_AVAILABLE_ALGO_MAX  2

 

 /** Allocate and initialize mAvailableAlgoArray with the available

     Rng algorithms. Also update mAvailableAlgoArrayCount.

@@ -46,8 +50,9 @@ GetAvailableAlgorithms (
   )

 {

   UINT64  DummyRand;

+  UINT16  MajorRevision;

+  UINT16  MinorRevision;

 

-  // Allocate RNG_AVAILABLE_ALGO_MAX entries to avoid evaluating

   // Rng algorithms 2 times, one for the allocation, one to populate.

   mAvailableAlgoArray = AllocateZeroPool (RNG_AVAILABLE_ALGO_MAX);

   if (mAvailableAlgoArray == NULL) {

@@ -64,6 +69,16 @@ GetAvailableAlgorithms (
     mAvailableAlgoArrayCount++;

   }

 

+  // Raw algorithm (Trng)

+  if (!EFI_ERROR (GetArmTrngVersion (&MajorRevision, &MinorRevision))) {

+    CopyMem (

+      &mAvailableAlgoArray[mAvailableAlgoArrayCount],

+      &gEfiRngAlgorithmRaw,

+      sizeof (EFI_RNG_ALGORITHM)

+      );

+    mAvailableAlgoArrayCount++;

+  }

+

   return EFI_SUCCESS;

 }

 

@@ -141,6 +156,11 @@ FoundAlgo:
     return Status;

   }

 

+  // Raw algorithm (Trng)

+  if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {

+    return GenerateEntropy (RNGValueLength, RNGValue);

+  }

+

   //

   // Other algorithms are unsupported by this driver.

   //

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/ArmTrng.c b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmTrng.c
new file mode 100644
index 0000000000..ffe557b692
--- /dev/null
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/ArmTrng.c
@@ -0,0 +1,71 @@
+/** @file

+  RNG Driver to produce the UEFI Random Number Generator protocol.

+

+  The driver implements the EFI_RNG_ALGORITHM_RAW using the FW-TRNG

+  interface to provide entropy.

+

+  Copyright (c) 2021 - 2022, Arm Limited. All rights reserved.<BR>

+

+  SPDX-License-Identifier: BSD-2-Clause-Patent

+

+**/

+

+#include <Library/BaseLib.h>

+#include <Library/BaseMemoryLib.h>

+#include <Library/DebugLib.h>

+#include <Library/ArmTrngLib.h>

+#include <Protocol/Rng.h>

+

+#include "RngDxeInternals.h"

+

+/**

+  Generate high-quality entropy source using a TRNG or through RDRAND.

+

+  @param[in]   Length        Size of the buffer, in bytes, to fill with.

+  @param[out]  Entropy       Pointer to the buffer to store the entropy data.

+

+  @retval  RETURN_SUCCESS            The function completed successfully.

+  @retval  RETURN_INVALID_PARAMETER  Invalid parameter.

+  @retval  RETURN_UNSUPPORTED        Function not implemented.

+  @retval  RETURN_BAD_BUFFER_SIZE    Buffer size is too small.

+  @retval  RETURN_NOT_READY          No Entropy available.

+**/

+EFI_STATUS

+EFIAPI

+GenerateEntropy (

+  IN  UINTN  Length,

+  OUT UINT8  *Entropy

+  )

+{

+  EFI_STATUS  Status;

+  UINTN       CollectedEntropyBits;

+  UINTN       RequiredEntropyBits;

+  UINTN       EntropyBits;

+  UINTN       Index;

+  UINTN       MaxBits;

+

+  ZeroMem (Entropy, Length);

+

+  RequiredEntropyBits  = (Length << 3);

+  Index                = 0;

+  CollectedEntropyBits = 0;

+  MaxBits              = GetArmTrngMaxSupportedEntropyBits ();

+  while (CollectedEntropyBits < RequiredEntropyBits) {

+    EntropyBits = MIN ((RequiredEntropyBits - CollectedEntropyBits), MaxBits);

+    Status      = GetArmTrngEntropy (

+                    EntropyBits,

+                    (Length - Index),

+                    &Entropy[Index]

+                    );

+    if (EFI_ERROR (Status)) {

+      // Discard the collected bits.

+      ZeroMem (Entropy, Length);

+      return Status;

+    }

+

+    CollectedEntropyBits += EntropyBits;

+    Index                += (EntropyBits >> 3);

+  } // while

+

+  return Status;

+}

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
index 1985dfbb46..e0e767cbf3 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
@@ -43,8 +43,10 @@
 

 [Sources.AARCH64]

   AArch64/RngDxe.c

+  ArmTrng.c

 

 [Packages]

+  MdeModulePkg/MdeModulePkg.dec

   MdePkg/MdePkg.dec

   SecurityPkg/SecurityPkg.dec

 

@@ -57,6 +59,9 @@
   TimerLib

   RngLib

 

+[LibraryClasses.AARCH64]

+  ArmTrngLib

+

 [Guids]

   gEfiRngAlgorithmSp80090Hash256Guid  ## SOMETIMES_PRODUCES    ## GUID        # Unique ID of the algorithm for RNG

   gEfiRngAlgorithmSp80090Hmac256Guid  ## SOMETIMES_PRODUCES    ## GUID        # Unique ID of the algorithm for RNG