MdePkg/Rng: Add GetRngGuid() to RngLib

The EFI_RNG_PROTOCOL can use the RngLib. The RngLib has multiple
implementations, some of them are unsafe (e.g. BaseRngLibTimerLib).
To allow the RngDxe to detect when such implementation is used,
add a GetRngGuid() function to the RngLib.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Kun Qin <kun.qin@microsoft.com>

6 files changed, 151 insertions, 0 deletions

diff --git a/MdePkg/Library/BaseRngLib/AArch64/Rndr.c b/MdePkg/Library/BaseRngLib/AArch64/Rndr.c
index 20811bf..d39db62 100644
--- a/MdePkg/Library/BaseRngLib/AArch64/Rndr.c
+++ b/MdePkg/Library/BaseRngLib/AArch64/Rndr.c
@@ -2,6 +2,7 @@
   Random number generator service that uses the RNDR instruction

   to provide pseudorandom numbers.

 

+  Copyright (c) 2023, Arm Limited. All rights reserved.<BR>

   Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>

   Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>

 

@@ -11,6 +12,7 @@
 

 #include <Uefi.h>

 #include <Library/BaseLib.h>

+#include <Library/BaseMemoryLib.h>

 #include <Library/DebugLib.h>

 #include <Library/RngLib.h>

 

@@ -138,3 +140,43 @@ ArchIsRngSupported (
 {

   return mRndrSupported;

 }

+

+/**

+  Get a GUID identifying the RNG algorithm implementation.

+

+  @param [out] RngGuid  If success, contains the GUID identifying

+                        the RNG algorithm implementation.

+

+  @retval EFI_SUCCESS             Success.

+  @retval EFI_UNSUPPORTED         Not supported.

+  @retval EFI_INVALID_PARAMETER   Invalid parameter.

+**/

+EFI_STATUS

+EFIAPI

+GetRngGuid (

+  GUID  *RngGuid

+  )

+{

+  GUID  *RngLibGuid;

+

+  if (RngGuid == NULL) {

+    return EFI_INVALID_PARAMETER;

+  }

+

+  if (!mRndrSupported) {

+    return EFI_UNSUPPORTED;

+  }

+

+  //

+  // If the platform advertises the algorithm behind RNDR instruction,

+  // use it. Otherwise use gEfiRngAlgorithmArmRndr.

+  //

+  RngLibGuid = PcdGetPtr (PcdCpuRngSupportedAlgorithm);

+  if (!IsZeroGuid (RngLibGuid)) {

+    CopyMem (RngGuid, RngLibGuid, sizeof (*RngGuid));

+  } else {

+    CopyMem (RngGuid, &gEfiRngAlgorithmArmRndr, sizeof (*RngGuid));

+  }

+

+  return EFI_SUCCESS;

+}

diff --git a/MdePkg/Library/BaseRngLib/BaseRngLib.inf b/MdePkg/Library/BaseRngLib/BaseRngLib.inf
index 1fcceb9..49503b1 100644
--- a/MdePkg/Library/BaseRngLib/BaseRngLib.inf
+++ b/MdePkg/Library/BaseRngLib/BaseRngLib.inf
@@ -4,6 +4,7 @@
 #  BaseRng Library that uses CPU RNG instructions (e.g. RdRand) to

 #  provide random numbers.

 #

+#  Copyright (c) 2023, Arm Limited. All rights reserved.<BR>

 #  Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>

 #  Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>

 #

@@ -43,9 +44,18 @@
   AArch64/ArmReadIdIsar0.asm | MSFT

   AArch64/ArmRng.asm         | MSFT

 

+[Guids.AARCH64]

+  gEfiRngAlgorithmArmRndr

+

+[Guids.Ia32, Guids.X64]

+  gEfiRngAlgorithmSp80090Ctr256Guid

+

 [Packages]

   MdePkg/MdePkg.dec

 

+[Pcd.AARCH64]

+  gEfiMdePkgTokenSpaceGuid.PcdCpuRngSupportedAlgorithm

+

 [LibraryClasses]

   BaseLib

   DebugLib

diff --git a/MdePkg/Library/BaseRngLib/Rand/RdRand.c b/MdePkg/Library/BaseRngLib/Rand/RdRand.c
index 070d41e..9bd6835 100644
--- a/MdePkg/Library/BaseRngLib/Rand/RdRand.c
+++ b/MdePkg/Library/BaseRngLib/Rand/RdRand.c
@@ -2,6 +2,7 @@
   Random number generator services that uses RdRand instruction access

   to provide high-quality random numbers.

 

+Copyright (c) 2023, Arm Limited. All rights reserved.<BR>

 Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>

 Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>

 

@@ -11,6 +12,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 

 #include <Uefi.h>

 #include <Library/BaseLib.h>

+#include <Library/BaseMemoryLib.h>

 #include <Library/DebugLib.h>

 

 #include "BaseRngLibInternals.h"

@@ -128,3 +130,27 @@ ArchIsRngSupported (
   */

   return TRUE;

 }

+

+/**

+  Get a GUID identifying the RNG algorithm implementation.

+

+  @param [out] RngGuid  If success, contains the GUID identifying

+                        the RNG algorithm implementation.

+

+  @retval EFI_SUCCESS             Success.

+  @retval EFI_UNSUPPORTED         Not supported.

+  @retval EFI_INVALID_PARAMETER   Invalid parameter.

+**/

+EFI_STATUS

+EFIAPI

+GetRngGuid (

+  GUID  *RngGuid

+  )

+{

+  if (RngGuid == NULL) {

+    return EFI_INVALID_PARAMETER;

+  }

+

+  CopyMem (RngGuid, &gEfiRngAlgorithmSp80090Ctr256Guid, sizeof (*RngGuid));

+  return EFI_SUCCESS;

+}

diff --git a/MdePkg/Library/BaseRngLibNull/BaseRngLibNull.c b/MdePkg/Library/BaseRngLibNull/BaseRngLibNull.c
index efba5c8..af5e8eb 100644
--- a/MdePkg/Library/BaseRngLibNull/BaseRngLibNull.c
+++ b/MdePkg/Library/BaseRngLibNull/BaseRngLibNull.c
@@ -1,13 +1,16 @@
 /** @file

   Null version of Random number generator services.

 

+Copyright (c) 2023, Arm Limited. All rights reserved.<BR>

 Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>

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

 

 **/

 

+#include <Uefi.h>

 #include <Library/DebugLib.h>

 #include <Library/RngLib.h>

+#include <Protocol/Rng.h>

 

 /**

   Generates a 16-bit random number.

@@ -92,3 +95,22 @@ GetRandomNumber128 (
   ASSERT (FALSE);

   return FALSE;

 }

+

+/**

+  Get a GUID identifying the RNG algorithm implementation.

+

+  @param [out] RngGuid  If success, contains the GUID identifying

+                        the RNG algorithm implementation.

+

+  @retval EFI_SUCCESS             Success.

+  @retval EFI_UNSUPPORTED         Not supported.

+  @retval EFI_INVALID_PARAMETER   Invalid parameter.

+**/

+EFI_STATUS

+EFIAPI

+GetRngGuid (

+  GUID  *RngGuid

+  )

+{

+  return EFI_UNSUPPORTED;

+}

diff --git a/MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c b/MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
index c4fdd1d..4a7cae7 100644
--- a/MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
+++ b/MdePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
@@ -212,3 +212,26 @@ GetRandomNumber128 (
   // Read second 64 bits

   return GetRandomNumber64 (++Rand);

 }

+

+/**

+  Get a GUID identifying the RNG algorithm implementation.

+

+  @param [out] RngGuid  If success, contains the GUID identifying

+                        the RNG algorithm implementation.

+

+  @retval EFI_SUCCESS             Success.

+  @retval EFI_UNSUPPORTED         Not supported.

+  @retval EFI_INVALID_PARAMETER   Invalid parameter.

+**/

+RETURN_STATUS

+EFIAPI

+GetRngGuid (

+  GUID  *RngGuid

+  )

+{

+  /* This implementation is to be replaced by its MdeModulePkg copy.

+   * The cause being that some GUIDs (gEdkiiRngAlgorithmUnSafe) cannot

+   * be defined in the MdePkg.

+   */

+  return RETURN_UNSUPPORTED;

+}

diff --git a/MdePkg/Library/DxeRngLib/DxeRngLib.c b/MdePkg/Library/DxeRngLib/DxeRngLib.c
index a01b66a..05c7957 100644
--- a/MdePkg/Library/DxeRngLib/DxeRngLib.c
+++ b/MdePkg/Library/DxeRngLib/DxeRngLib.c
@@ -1,6 +1,7 @@
 /** @file

  Provides an implementation of the library class RngLib that uses the Rng protocol.

 

+ Copyright (c) 2023, Arm Limited. All rights reserved.

  Copyright (c) Microsoft Corporation. All rights reserved.

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

 

@@ -207,3 +208,30 @@ GetRandomNumber128 (
 

   return TRUE;

 }

+

+/**

+  Get a GUID identifying the RNG algorithm implementation.

+

+  @param [out] RngGuid  If success, contains the GUID identifying

+                        the RNG algorithm implementation.

+

+  @retval EFI_SUCCESS             Success.

+  @retval EFI_UNSUPPORTED         Not supported.

+  @retval EFI_INVALID_PARAMETER   Invalid parameter.

+**/

+EFI_STATUS

+EFIAPI

+GetRngGuid (

+  GUID  *RngGuid

+  )

+{

+  /* It is not possible to know beforehand which Rng algorithm will

+   * be used by this library.

+   * This API is mainly used by RngDxe. RngDxe relies on the RngLib.

+   * The RngLib|DxeRngLib.inf implementation locates and uses an installed

+   * EFI_RNG_PROTOCOL.

+   * It is thus not possible to have both RngDxe and RngLib|DxeRngLib.inf.

+   * and it is ok not to support this API.

+   */

+  return EFI_UNSUPPORTED;

+}