1 files changed, 38 insertions, 17 deletions
diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
index e8be217f8a..a270441ebb 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
@@ -10,6 +10,8 @@
 #include <Library/DebugLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/ArmTrngLib.h>
+#include <Library/RngLib.h>
+#include <Guid/RngAlgorithm.h>
 
 #include "RngDxeInternals.h"
 
@@ -28,9 +30,13 @@ GetAvailableAlgorithms (
   VOID
   )
 {
-  UINT64  DummyRand;
-  UINT16  MajorRevision;
-  UINT16  MinorRevision;
+  EFI_STATUS  Status;
+  UINT16      MajorRevision;
+  UINT16      MinorRevision;
+  GUID        RngGuid;
+  BOOLEAN     UnSafeAlgo;
+
+  UnSafeAlgo = FALSE;
 
   // Rng algorithms 2 times, one for the allocation, one to populate.
   mAvailableAlgoArray = AllocateZeroPool (RNG_AVAILABLE_ALGO_MAX);
@@ -38,24 +44,29 @@ GetAvailableAlgorithms (
     return EFI_OUT_OF_RESOURCES;
   }
 
-  // Check RngGetBytes() before advertising PcdCpuRngSupportedAlgorithm.
-  if (!EFI_ERROR (RngGetBytes (sizeof (DummyRand), (UINT8 *)&DummyRand))) {
-    CopyMem (
-      &mAvailableAlgoArray[mAvailableAlgoArrayCount],
-      PcdGetPtr (PcdCpuRngSupportedAlgorithm),
-      sizeof (EFI_RNG_ALGORITHM)
-      );
-    mAvailableAlgoArrayCount++;
-
-    DEBUG_CODE_BEGIN ();
-    if (IsZeroGuid (PcdGetPtr (PcdCpuRngSupportedAlgorithm))) {
+  // Identify RngLib algorithm.
+  Status = GetRngGuid (&RngGuid);
+  if (!EFI_ERROR (Status)) {
+    if (IsZeroGuid (&RngGuid) ||
+        CompareGuid (&RngGuid, &gEdkiiRngAlgorithmUnSafe))
+    {
+      // Treat zero GUID as an unsafe algorithm
       DEBUG ((
         DEBUG_WARN,
-        "PcdCpuRngSupportedAlgorithm should be a non-zero GUID\n"
+        "RngLib uses an Unsafe algorithm and "
+        "must not be used for production builds.\n"
         ));
+      // Set the UnSafeAlgo flag to indicate an unsafe algorithm was found
+      // so that it can be added at the end of the algorithm list.
+      UnSafeAlgo = TRUE;
+    } else {
+      CopyMem (
+        &mAvailableAlgoArray[mAvailableAlgoArrayCount],
+        &RngGuid,
+        sizeof (RngGuid)
+        );
+      mAvailableAlgoArrayCount++;
     }
-
-    DEBUG_CODE_END ();
   }
 
   // Raw algorithm (Trng)
@@ -68,5 +79,15 @@ GetAvailableAlgorithms (
     mAvailableAlgoArrayCount++;
   }
 
+  // Add unsafe algorithm at the end of the list.
+  if (UnSafeAlgo) {
+    CopyMem (
+      &mAvailableAlgoArray[mAvailableAlgoArrayCount],
+      &gEdkiiRngAlgorithmUnSafe,
+      sizeof (EFI_RNG_ALGORITHM)
+      );
+    mAvailableAlgoArrayCount++;
+  }
+
   return EFI_SUCCESS;
 }