[edk2-devel] [PATCH v3 07/20] SecurityPkg: RngDxe: Remove incorrect limitation on GetRng

["Doug Flick via groups.io" <dougflick=microsoft.com@groups.io>]

Removed from gEfiRngAlgorithmRaw an incorrect assumption that
Raw cannot return less than 256 bits. The DRNG Algorithms
should always use a 256 bit seed as per nist standards
however a caller is free to request less than 256 bits.
>
>     //
>    // When a DRBG is used on the output of a entropy source,
>    // its security level must be at least 256 bits according to UEFI
Spec.
>    //
>    if (RNGValueLength < 32) {
>      return EFI_INVALID_PARAMETER;
>    }
>

AARCH64 platforms do not have this limitation and this brings both
implementations into alignment with each other and the spec.

Cc: Jiewen Yao <jiewen.yao@intel.com>

Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
---
 SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
index 7e06e16e4b..5723ed6957 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c
@@ -116,14 +116,6 @@ RngGetRNG (
   // The "raw" algorithm is intended to provide entropy directly
   //
   if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
-    //
-    // When a DRBG is used on the output of a entropy source,
-    // its security level must be at least 256 bits according to UEFI Spec.
-    //
-    if (RNGValueLength < 32) {
-      return EFI_INVALID_PARAMETER;
-    }
-
     Status = GenerateEntropy (RNGValueLength, RNGValue);
     return Status;
   }
-- 
2.34.1



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