MdePkg/DxeRngLib: Refactor Rng algorithm selection

Add a library constructor which:
- locate the RNG prototocol and keep a reference to it in order to avoid
  locating it multiple times (for each random number generation)
- check which secure algorithm is available on the platform.
  This avoids to try each secure algorithm until finding one
  available for each random number generation call.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
This commit is contained in:
Pierre Gondois 2024-09-03 18:04:39 +02:00 committed by mergify[bot]
parent bc02b255a8
commit c04c4534c4
2 changed files with 157 additions and 30 deletions

View File

@ -1,17 +1,129 @@
/** @file
Provides an implementation of the library class RngLib that uses the Rng protocol.
Copyright (c) 2023, Arm Limited. All rights reserved.
Copyright (c) 2023 - 2024, Arm Limited. All rights reserved.
Copyright (c) Microsoft Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Uefi.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/RngLib.h>
#include <Protocol/Rng.h>
STATIC EFI_RNG_PROTOCOL *mRngProtocol;
STATIC UINTN mFirstAlgo = MAX_UINTN;
typedef struct {
/// Guid of the secure algorithm.
EFI_GUID *Guid;
/// Algorithm name.
CONST CHAR8 *Name;
/// The algorithm is available for use.
BOOLEAN Available;
} SECURE_RNG_ALGO_ARRAY;
//
// These represent UEFI SPEC defined algorithms that should be supported by
// the RNG protocol and are generally considered secure.
//
GLOBAL_REMOVE_IF_UNREFERENCED SECURE_RNG_ALGO_ARRAY mSecureHashAlgorithms[] = {
{
&gEfiRngAlgorithmSp80090Ctr256Guid, // SP800-90A DRBG CTR using AES-256
"DRBG-CTR",
FALSE,
},
{
&gEfiRngAlgorithmSp80090Hmac256Guid, // SP800-90A DRBG HMAC using SHA-256
"DRBG-HMAC",
FALSE,
},
{
&gEfiRngAlgorithmSp80090Hash256Guid, // SP800-90A DRBG Hash using SHA-256
"DRBG-Hash",
FALSE,
},
{
&gEfiRngAlgorithmRaw, // Raw data from NRBG (or TRNG)
"TRNG",
FALSE,
},
};
/**
Constructor routine to probe the available secure Rng algorithms.
@param ImageHandle The firmware allocated handle for the EFI image.
@param SystemTable A pointer to the EFI System Table.
@retval EFI_SUCCESS Success.
@retval EFI_NOT_FOUND Not found.
@retval EFI_INVALID_PARAMETER Invalid parameter.
**/
EFI_STATUS
EFIAPI
DxeRngLibConstructor (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
UINTN RngArraySize;
UINTN RngArrayCnt;
UINT32 Index;
UINT32 Index1;
EFI_RNG_ALGORITHM *RngArray;
Status = gBS->LocateProtocol (&gEfiRngProtocolGuid, NULL, (VOID **)&mRngProtocol);
if (EFI_ERROR (Status) || (mRngProtocol == NULL)) {
DEBUG ((DEBUG_ERROR, "%a: Could not locate RNG protocol, Status = %r\n", __func__, Status));
return Status;
}
RngArraySize = 0;
Status = mRngProtocol->GetInfo (mRngProtocol, &RngArraySize, NULL);
if (EFI_ERROR (Status) && (Status != EFI_BUFFER_TOO_SMALL)) {
return Status;
} else if (RngArraySize == 0) {
return EFI_NOT_FOUND;
}
RngArrayCnt = RngArraySize / sizeof (*RngArray);
RngArray = AllocateZeroPool (RngArraySize);
if (RngArray == NULL) {
return EFI_OUT_OF_RESOURCES;
}
Status = mRngProtocol->GetInfo (mRngProtocol, &RngArraySize, RngArray);
if (EFI_ERROR (Status)) {
goto ExitHandler;
}
for (Index = 0; Index < RngArrayCnt; Index++) {
for (Index1 = 0; Index1 < ARRAY_SIZE (mSecureHashAlgorithms); Index1++) {
if (CompareGuid (&RngArray[Index], mSecureHashAlgorithms[Index1].Guid)) {
mSecureHashAlgorithms[Index1].Available = TRUE;
if (mFirstAlgo == MAX_UINTN) {
mFirstAlgo = Index1;
}
break;
}
}
}
ExitHandler:
FreePool (RngArray);
return Status;
}
/**
Routine Description:
@ -32,55 +144,68 @@ GenerateRandomNumberViaNist800Algorithm (
IN UINTN BufferSize
)
{
EFI_STATUS Status;
EFI_RNG_PROTOCOL *RngProtocol;
RngProtocol = NULL;
EFI_STATUS Status;
UINTN Index;
SECURE_RNG_ALGO_ARRAY *Algo;
if (Buffer == NULL) {
DEBUG ((DEBUG_ERROR, "%a: Buffer == NULL.\n", __func__));
return EFI_INVALID_PARAMETER;
}
Status = gBS->LocateProtocol (&gEfiRngProtocolGuid, NULL, (VOID **)&RngProtocol);
if (EFI_ERROR (Status) || (RngProtocol == NULL)) {
DEBUG ((DEBUG_ERROR, "%a: Could not locate RNG prototocol, Status = %r\n", __func__, Status));
return Status;
if (mRngProtocol == NULL) {
return EFI_NOT_FOUND;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Ctr256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm CTR-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
// Try the first available algorithm.
if (mFirstAlgo != MAX_UINTN) {
Algo = &mSecureHashAlgorithms[mFirstAlgo];
Status = mRngProtocol->GetRNG (mRngProtocol, Algo->Guid, BufferSize, Buffer);
DEBUG ((
DEBUG_INFO,
"%a: GetRNG algorithm %a - Status = %r\n",
__func__,
Algo->Name,
Status
));
if (!EFI_ERROR (Status)) {
return Status;
}
Index = mFirstAlgo + 1;
} else {
Index = 0;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Hmac256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm HMAC-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
// Iterate over other available algorithms.
for ( ; Index < ARRAY_SIZE (mSecureHashAlgorithms); Index++) {
Algo = &mSecureHashAlgorithms[Index];
if (!Algo->Available) {
continue;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmSp80090Hash256Guid, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm Hash-256 - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
Status = RngProtocol->GetRNG (RngProtocol, &gEfiRngAlgorithmRaw, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm Raw - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
Status = mRngProtocol->GetRNG (mRngProtocol, Algo->Guid, BufferSize, Buffer);
DEBUG ((
DEBUG_INFO,
"%a: GetRNG algorithm %a - Status = %r\n",
__func__,
Algo->Name,
Status
));
if (!EFI_ERROR (Status)) {
return Status;
}
}
// If all the other methods have failed, use the default method from the RngProtocol
Status = RngProtocol->GetRNG (RngProtocol, NULL, BufferSize, Buffer);
Status = mRngProtocol->GetRNG (mRngProtocol, NULL, BufferSize, Buffer);
DEBUG ((DEBUG_INFO, "%a: GetRNG algorithm default - Status = %r\n", __func__, Status));
if (!EFI_ERROR (Status)) {
return Status;
}
// If we get to this point, we have failed
DEBUG ((DEBUG_ERROR, "%a: GetRNG() failed, staus = %r\n", __func__, Status));
DEBUG ((DEBUG_ERROR, "%a: GetRNG() failed, Status = %r\n", __func__, Status));
return Status;
}// GenerateRandomNumberViaNist800Algorithm()

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@ -15,6 +15,7 @@
MODULE_TYPE = DXE_DRIVER
VERSION_STRING = 1.0
LIBRARY_CLASS = RngLib|DXE_DRIVER DXE_RUNTIME_DRIVER UEFI_APPLICATION UEFI_DRIVER
CONSTRUCTOR = DxeRngLibConstructor
[Packages]
MdePkg/MdePkg.dec
@ -24,6 +25,7 @@
[LibraryClasses]
DebugLib
MemoryAllocationLib
UefiBootServicesTableLib
[Protocols]