Hi Sami,
Your suggestion in https://edk2.groups.io/g/devel/message/106511 works
properly during my test.
But I think we still need to keep the `+ &RngGuid, ` change below
as a bug fix?
Thanks,
Kun
On 6/29/2023 3:28 AM, Sami Mujawar wrote:
Hi Pierre,
I think this patch would not be required if my suggestions for patch
6/8 are adopted.
Regards,
Sami Mujawar
On 09/05/2023 08:40 am, pierre.gond...@arm.com wrote:
From: Pierre Gondois <pierre.gond...@arm.com>
The first element of mAvailableAlgoArray should be the default
algorithm to avoid going through a selection process at each
RngGetRNG() call.
Once all the available Rng algorithms have been probed, place
a safe Rng algorithm at the first position of mAvailableAlgoArray.
Signed-off-by: Pierre Gondois <pierre.gond...@arm.com>
---
.../RngDxe/AArch64/AArch64Algo.c | 48 ++++++++++++++++++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git
a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
index a1ff7bd58fda..ed236b2e8141 100644
--- a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
+++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/AArch64Algo.c
@@ -17,6 +17,50 @@
// Maximum number of Rng algorithms.
#define RNG_AVAILABLE_ALGO_MAX 2
+/** mAvailableAlgoArray[0] should contain the default Rng algorithm.
+ The Rng algorithm at the first index might be unsafe.
+ If a safe algorithm is available, choose it as the default one.
+**/
+VOID
+EFIAPI
+RngFindDefaultAlgo (
+ VOID
+ )
+{
+ EFI_RNG_ALGORITHM *CurAlgo;
+ EFI_RNG_ALGORITHM TmpGuid;
+ UINTN Index;
+
+ CurAlgo = &mAvailableAlgoArray[0];
+
+ if (IsZeroGuid (CurAlgo) ||
+ !CompareGuid (CurAlgo, &gEfiRngAlgorithmUnSafe))
+ {
+ // mAvailableAlgoArray[0] is a valid Rng algorithm.
+ return;
+ }
+
+ for (Index = 1; Index < mAvailableAlgoArrayCount; Index++) {
+ CurAlgo = &mAvailableAlgoArray[Index];
+ if (!IsZeroGuid (CurAlgo) ||
+ CompareGuid (CurAlgo, &gEfiRngAlgorithmUnSafe))
+ {
+ break;
+ }
+ }
+
+ if (Index == mAvailableAlgoArrayCount) {
+ // No valid Rng algorithm available.
+ return;
+ }
+
+ CopyMem (&TmpGuid, CurAlgo, sizeof (EFI_RNG_ALGORITHM));
+ CopyMem (CurAlgo, &mAvailableAlgoArray[0], sizeof
(EFI_RNG_ALGORITHM));
+ CopyMem (&mAvailableAlgoArray[0], &TmpGuid, sizeof
(EFI_RNG_ALGORITHM));
+
+ return;
+}
+
/** Allocate and initialize mAvailableAlgoArray with the available
Rng algorithms. Also update mAvailableAlgoArrayCount.
@@ -45,7 +89,7 @@ GetAvailableAlgorithms (
if (!EFI_ERROR (Status)) {
CopyMem (
&mAvailableAlgoArray[mAvailableAlgoArrayCount],
- RngGuid,
+ &RngGuid,
sizeof (RngGuid)
);
mAvailableAlgoArrayCount++;
@@ -68,5 +112,7 @@ GetAvailableAlgorithms (
mAvailableAlgoArrayCount++;
}
+ RngFindDefaultAlgo ();
+
return EFI_SUCCESS;
}
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