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/** @file
RNG Driver to produce the UEFI Random Number Generator protocol.
The driver can use RNDR instruction (through the RngLib and if FEAT_RNG is
present) to produce random numbers. It also uses the Arm FW-TRNG interface
to implement EFI_RNG_ALGORITHM_RAW.
RNG Algorithms defined in UEFI 2.4:
- EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID
- EFI_RNG_ALGORITHM_RAW
- EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID
- EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID
- EFI_RNG_ALGORITHM_X9_31_3DES_GUID - Unsupported
- EFI_RNG_ALGORITHM_X9_31_AES_GUID - Unsupported
Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
Copyright (c) 2021 - 2022, Arm Limited. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/RngLib.h>
#include <Library/DebugLib.h>
#include <Library/ArmTrngLib.h>
#include <Protocol/Rng.h>
#include "RngDxeInternals.h"
// Maximum number of Rng algorithms.
#define RNG_AVAILABLE_ALGO_MAX 2
/** Allocate and initialize mAvailableAlgoArray with the available
Rng algorithms. Also update mAvailableAlgoArrayCount.
@retval EFI_SUCCESS The function completed successfully.
@retval EFI_OUT_OF_RESOURCES Could not allocate memory.
**/
EFI_STATUS
EFIAPI
GetAvailableAlgorithms (
VOID
)
{
UINT64 DummyRand;
UINT16 MajorRevision;
UINT16 MinorRevision;
// Rng algorithms 2 times, one for the allocation, one to populate.
mAvailableAlgoArray = AllocateZeroPool (RNG_AVAILABLE_ALGO_MAX);
if (mAvailableAlgoArray == NULL) {
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))) {
DEBUG ((
DEBUG_WARN,
"PcdCpuRngSupportedAlgorithm should be a non-zero GUID\n"
));
}
DEBUG_CODE_END ();
}
// Raw algorithm (Trng)
if (!EFI_ERROR (GetArmTrngVersion (&MajorRevision, &MinorRevision))) {
CopyMem (
&mAvailableAlgoArray[mAvailableAlgoArrayCount],
&gEfiRngAlgorithmRaw,
sizeof (EFI_RNG_ALGORITHM)
);
mAvailableAlgoArrayCount++;
}
return EFI_SUCCESS;
}
/** Free mAvailableAlgoArray.
**/
VOID
EFIAPI
FreeAvailableAlgorithms (
VOID
)
{
FreePool (mAvailableAlgoArray);
return;
}
/**
Produces and returns an RNG value using either the default or specified RNG algorithm.
@param[in] This A pointer to the EFI_RNG_PROTOCOL instance.
@param[in] RNGAlgorithm A pointer to the EFI_RNG_ALGORITHM that identifies the RNG
algorithm to use. May be NULL in which case the function will
use its default RNG algorithm.
@param[in] RNGValueLength The length in bytes of the memory buffer pointed to by
RNGValue. The driver shall return exactly this numbers of bytes.
@param[out] RNGValue A caller-allocated memory buffer filled by the driver with the
resulting RNG value.
@retval EFI_SUCCESS The RNG value was returned successfully.
@retval EFI_UNSUPPORTED The algorithm specified by RNGAlgorithm is not supported by
this driver.
@retval EFI_DEVICE_ERROR An RNG value could not be retrieved due to a hardware or
firmware error.
@retval EFI_NOT_READY There is not enough random data available to satisfy the length
requested by RNGValueLength.
@retval EFI_INVALID_PARAMETER RNGValue is NULL or RNGValueLength is zero.
**/
EFI_STATUS
EFIAPI
RngGetRNG (
IN EFI_RNG_PROTOCOL *This,
IN EFI_RNG_ALGORITHM *RNGAlgorithm OPTIONAL,
IN UINTN RNGValueLength,
OUT UINT8 *RNGValue
)
{
EFI_STATUS Status;
UINTN Index;
if ((This == NULL) || (RNGValueLength == 0) || (RNGValue == NULL)) {
return EFI_INVALID_PARAMETER;
}
if (RNGAlgorithm == NULL) {
//
// Use the default RNG algorithm if RNGAlgorithm is NULL.
//
for (Index = 0; Index < mAvailableAlgoArrayCount; Index++) {
if (!IsZeroGuid (&mAvailableAlgoArray[Index])) {
RNGAlgorithm = &mAvailableAlgoArray[Index];
goto FoundAlgo;
}
}
if (Index == mAvailableAlgoArrayCount) {
// No algorithm available.
ASSERT (Index != mAvailableAlgoArrayCount);
return EFI_DEVICE_ERROR;
}
}
FoundAlgo:
if (CompareGuid (RNGAlgorithm, PcdGetPtr (PcdCpuRngSupportedAlgorithm))) {
Status = RngGetBytes (RNGValueLength, RNGValue);
return Status;
}
// Raw algorithm (Trng)
if (CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
return GenerateEntropy (RNGValueLength, RNGValue);
}
//
// Other algorithms are unsupported by this driver.
//
return EFI_UNSUPPORTED;
}
/**
Returns information about the random number generation implementation.
@param[in] This A pointer to the EFI_RNG_PROTOCOL instance.
@param[in,out] RNGAlgorithmListSize On input, the size in bytes of RNGAlgorithmList.
On output with a return code of EFI_SUCCESS, the size
in bytes of the data returned in RNGAlgorithmList. On output
with a return code of EFI_BUFFER_TOO_SMALL,
the size of RNGAlgorithmList required to obtain the list.
@param[out] RNGAlgorithmList A caller-allocated memory buffer filled by the driver
with one EFI_RNG_ALGORITHM element for each supported
RNG algorithm. The list must not change across multiple
calls to the same driver. The first algorithm in the list
is the default algorithm for the driver.
@retval EFI_SUCCESS The RNG algorithm list was returned successfully.
@retval EFI_UNSUPPORTED The services is not supported by this driver.
@retval EFI_DEVICE_ERROR The list of algorithms could not be retrieved due to a
hardware or firmware error.
@retval EFI_INVALID_PARAMETER One or more of the parameters are incorrect.
@retval EFI_BUFFER_TOO_SMALL The buffer RNGAlgorithmList is too small to hold the result.
**/
EFI_STATUS
EFIAPI
RngGetInfo (
IN EFI_RNG_PROTOCOL *This,
IN OUT UINTN *RNGAlgorithmListSize,
OUT EFI_RNG_ALGORITHM *RNGAlgorithmList
)
{
UINTN RequiredSize;
if ((This == NULL) || (RNGAlgorithmListSize == NULL)) {
return EFI_INVALID_PARAMETER;
}
RequiredSize = mAvailableAlgoArrayCount * sizeof (EFI_RNG_ALGORITHM);
if (RequiredSize == 0) {
// No supported algorithms found.
return EFI_UNSUPPORTED;
}
if (*RNGAlgorithmListSize < RequiredSize) {
*RNGAlgorithmListSize = RequiredSize;
return EFI_BUFFER_TOO_SMALL;
}
if (RNGAlgorithmList == NULL) {
return EFI_INVALID_PARAMETER;
}
// There is no gap in the array, so copy the block.
CopyMem (RNGAlgorithmList, mAvailableAlgoArray, RequiredSize);
*RNGAlgorithmListSize = RequiredSize;
return EFI_SUCCESS;
}
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