From 5443c2dc310d2c8eb15fb8eefd5057342e78cd0d Mon Sep 17 00:00:00 2001
From: Pierre Gondois <pierre.gondois@arm.com>
Date: Fri, 11 Aug 2023 16:33:08 +0200
Subject: 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>
---
 .../BaseRngLibTimerLib/BaseRngLibTimerLib.inf      |  4 ++++
 .../Library/BaseRngLibTimerLib/RngLibTimer.c       | 28 ++++++++++++++++++++++
 2 files changed, 32 insertions(+)

(limited to 'MdeModulePkg/Library')

diff --git a/MdeModulePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf b/MdeModulePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
index f729001060..8461260cc8 100644
--- a/MdeModulePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
+++ b/MdeModulePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
@@ -29,6 +29,10 @@
 
 [Packages]
   MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+
+[Guids]
+  gEdkiiRngAlgorithmUnSafe
 
 [LibraryClasses]
   BaseLib
diff --git a/MdeModulePkg/Library/BaseRngLibTimerLib/RngLibTimer.c b/MdeModulePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
index 980854d67b..28ff46c71f 100644
--- a/MdeModulePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
+++ b/MdeModulePkg/Library/BaseRngLibTimerLib/RngLibTimer.c
@@ -2,14 +2,18 @@
   BaseRng Library that uses the TimerLib to provide reasonably random numbers.
   Do not use this on a production system.
 
+  Copyright (c) 2023, Arm Limited. All rights reserved.
   Copyright (c) Microsoft Corporation.
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
 #include <Base.h>
+#include <Uefi.h>
 #include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/TimerLib.h>
+#include <Guid/RngAlgorithm.h>
 
 #define DEFAULT_DELAY_TIME_IN_MICROSECONDS  10
 
@@ -190,3 +194,27 @@ 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.
+**/
+EFI_STATUS
+EFIAPI
+GetRngGuid (
+  GUID  *RngGuid
+  )
+{
+  if (RngGuid == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  CopyMem (RngGuid, &gEdkiiRngAlgorithmUnSafe, sizeof (*RngGuid));
+  return EFI_SUCCESS;
+}
-- 
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