Re: [PATCH 3/3] SecurityPkg: Add support for RngDxe on AARCH64

["Ard Biesheuvel" <ardb@kernel.org>]

On Wed, 28 Apr 2021 at 22:44, Rebecca Cran <rebecca@nuviainc.com> wrote:
>
> AARCH64 support has been added to BaseRngLib via the optional
> ARMv8.5 FEAT_RNG.
>
> Refactor RngDxe to support AARCH64, note support for it in the
> VALID_ARCHITECTURES line of RngDxe.inf and enable it in SecurityPkg.dsc.
>
> Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
> ---
>  SecurityPkg/SecurityPkg.dsc                                   |  11 +-
>  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf           |  19 +++-
>  SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.h       |  37 ++++++
>  SecurityPkg/RandomNumberGenerator/RngDxe/{ => Rand}/AesCore.h |   0
>  SecurityPkg/RandomNumberGenerator/RngDxe/{ => Rand}/RdRand.h  |   0
>  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxeInternals.h    |  88 ++++++++++++++
>  SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.c       |  54 +++++++++
>  SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c     | 108 ++++++++++++++++++
>  SecurityPkg/RandomNumberGenerator/RngDxe/{ => Rand}/AesCore.c |   0
>  SecurityPkg/RandomNumberGenerator/RngDxe/{ => Rand}/RdRand.c  |   0
>  SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RngDxe.c        | 120 ++++++++++++++++++++
>  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.c             | 117 ++++---------------
>  12 files changed, 450 insertions(+), 104 deletions(-)
>
> diff --git a/SecurityPkg/SecurityPkg.dsc b/SecurityPkg/SecurityPkg.dsc
> index 12ccd1634941..bd4b810bce61 100644
> --- a/SecurityPkg/SecurityPkg.dsc
> +++ b/SecurityPkg/SecurityPkg.dsc
> @@ -259,6 +259,12 @@ [Components]
>  [Components.IA32, Components.X64, Components.ARM, Components.AARCH64]
>    SecurityPkg/Library/AuthVariableLib/AuthVariableLib.inf
>
> +[Components.IA32, Components.X64, Components.AARCH64]
> +  #
> +  # Random Number Generator
> +  #
> +  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
> +
>  [Components.IA32, Components.X64]
>    SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf
>
> @@ -334,11 +340,6 @@ [Components.IA32, Components.X64]
>    SecurityPkg/Library/SmmTcg2PhysicalPresenceLib/SmmTcg2PhysicalPresenceLib.inf
>    SecurityPkg/Library/SmmTcg2PhysicalPresenceLib/StandaloneMmTcg2PhysicalPresenceLib.inf
>
> -  #
> -  # Random Number Generator
> -  #
> -  SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
> -
>    #
>    # Opal Password solution
>    #
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
> index 99d6f6b35fc2..c188b6076c00 100644
> --- a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxe.inf
> @@ -26,15 +26,24 @@ [Defines]
>  #
>  # The following information is for reference only and not required by the build tools.
>  #
> -#  VALID_ARCHITECTURES           = IA32 X64
> +#  VALID_ARCHITECTURES           = IA32 X64 AARCH64
>  #
>
>  [Sources.common]
>    RngDxe.c
> -  RdRand.c
> -  RdRand.h
> -  AesCore.c
> -  AesCore.h
> +  RngDxeInternals.h
> +
> +[Sources.IA32, Sources.X64]
> +  Rand/RngDxe.c
> +  Rand/RdRand.c
> +  Rand/RdRand.h
> +  Rand/AesCore.c
> +  Rand/AesCore.h
> +
> +[Sources.AARCH64]
> +  AArch64/RngDxe.c
> +  AArch64/Rndr.c
> +  AArch64/Rndr.h
>
>  [Packages]
>    MdePkg/MdePkg.dec
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.h b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.h
> new file mode 100644
> index 000000000000..458faa834a3d
> --- /dev/null
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.h
> @@ -0,0 +1,37 @@
> +/** @file
> +  Header for the RNDR APIs used by RNG DXE driver.
> +
> +  Support API definitions for RNDR instruction access.
> +
> +
> +  Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
> +  (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef RNDR_H_
> +#define RNDR_H_
> +
> +#include <Library/BaseLib.h>
> +#include <Protocol/Rng.h>
> +
> +/**
> +  Calls RNDR to fill a buffer of arbitrary size with random bytes.
> +
> +  @param[in]   Length        Size of the buffer, in bytes, to fill with.
> +  @param[out]  RandBuffer    Pointer to the buffer to store the random result.
> +
> +  @retval EFI_SUCCESS        Random bytes generation succeeded.
> +  @retval EFI_NOT_READY      Failed to request random bytes.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +RndrGetBytes (
> +  IN UINTN         Length,
> +  OUT UINT8        *RandBuffer
> +  );
> +
> +#endif  // RNDR_H_
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AesCore.h b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/AesCore.h
> similarity index 100%
> rename from SecurityPkg/RandomNumberGenerator/RngDxe/AesCore.h
> rename to SecurityPkg/RandomNumberGenerator/RngDxe/Rand/AesCore.h
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RdRand.h b/SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RdRand.h
> similarity index 100%
> rename from SecurityPkg/RandomNumberGenerator/RngDxe/RdRand.h
> rename to SecurityPkg/RandomNumberGenerator/RngDxe/Rand/RdRand.h
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxeInternals.h b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxeInternals.h
> new file mode 100644
> index 000000000000..7e38fc2564f6
> --- /dev/null
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/RngDxeInternals.h
> @@ -0,0 +1,88 @@
> +/** @file
> +  Function prototypes for UEFI Random Number Generator protocol support.
> +
> +  Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef RNGDXE_INTERNALS_H_
> +#define RNGDXE_INTERNALS_H_
> +
> +extern EFI_RNG_ALGORITHM *mSUpportedRngAlgorithms;
> +
> +/**
> +  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
> +  );
> +
> +/**
> +  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
> +  );
> +
> +/**
> +  Returns the size of the RNG algorithms structure.
> +
> +  @return Size of the EFI_RNG_ALGORITHM list.
> +**/
> +UINTN
> +EFIAPI
> +ArchGetSupportedRngAlgorithmsSize (
> +  VOID
> +  );
> +
> +#endif  // RNGDXE_INTERNALS_H_
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.c b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.c
> new file mode 100644
> index 000000000000..36166a9cbc13
> --- /dev/null
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/Rndr.c
> @@ -0,0 +1,54 @@
> +/** @file
> +  Support routines for RNDR instruction access.
> +
> +  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>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/RngLib.h>
> +
> +#include "Rndr.h"
> +
> +/**
> +  Calls RNDR to fill a buffer of arbitrary size with random bytes.
> +
> +  @param[in]   Length        Size of the buffer, in bytes, to fill with.
> +  @param[out]  RandBuffer    Pointer to the buffer to store the random result.
> +
> +  @retval EFI_SUCCESS        Random bytes generation succeeded.
> +  @retval EFI_NOT_READY      Failed to request random bytes.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +RndrGetBytes (
> +  IN UINTN         Length,
> +  OUT UINT8        *RandBuffer
> +  )
> +{
> +  BOOLEAN     IsRandom;
> +  UINT64      TempRand;
> +
> +  while (Length > 0) {
> +    IsRandom = GetRandomNumber64 (&TempRand);
> +    if (!IsRandom) {
> +      return EFI_NOT_READY;
> +    }
> +    if (Length >= sizeof (TempRand)) {
> +      WriteUnaligned64 ((UINT64*)RandBuffer, TempRand);
> +      RandBuffer += sizeof (UINT64);
> +      Length -= sizeof (TempRand);
> +    } else {
> +      CopyMem (RandBuffer, &TempRand, Length);
> +      Length = 0;
> +    }
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> diff --git a/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c
> new file mode 100644
> index 000000000000..18cca825e72d
> --- /dev/null
> +++ b/SecurityPkg/RandomNumberGenerator/RngDxe/AArch64/RngDxe.c
> @@ -0,0 +1,108 @@
> +/** @file
> +  RNG Driver to produce the UEFI Random Number Generator protocol.
> +
> +  The driver will use the new RNDR instruction to produce high-quality, high-performance
> +  entropy and random number.
> +
> +  RNG Algorithms defined in UEFI 2.4:
> +   - EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID  - Unsupported
> +   - EFI_RNG_ALGORITHM_RAW                    - Supported
> +   - EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID - Unsupported
> +   - EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID - Unsupported
> +   - 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>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include <Library/BaseLib.h>
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Library/TimerLib.h>
> +#include <Protocol/Rng.h>
> +
> +#include "Rndr.h"
> +
> +//
> +// Supported RNG Algorithms list by this driver.
> +//
> +EFI_RNG_ALGORITHM mSupportedRngAlgorithms[] = {
> +  EFI_RNG_ALGORITHM_RAW


This is incorrect. Both flavors of RNDR return the output of a DRBG,
the only difference is how often they are reseeded.

We might need a PCD here to define which exact DRBG implementation is
used in the hardware, and set this accordingly. We could use a VOID*
PTR PCD type to carry the GUID itself, in which case we could reuse
the same code for x86 as well, if I am not mistaken.

-- 
Ard.