Re: [PATCH v3 1/6] OvmfPkg/TPM: Import PeiDxeTpmPlatformHierarchyLib.c from edk2-platforms

["Marc-André Lureau" <mlureau@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 9980 bytes --]

Hi

On Tue, Aug 10, 2021 at 9:22 PM Stefan Berger <stefanb@linux.vnet.ibm.com>
wrote:

> Import PeiDxeTpmPlatformHierarchyLib.c from edk2-platforms. Modify it so
> that ConfigureTpmPlatformHierarchy() is the only public function provided
> by this file.
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> ---
>  .../Include/Library/TpmPlatformHierarchyLib.h |  27 +++
>  .../PeiDxeTpmPlatformHierarchyLib.c           | 210 ++++++++++++++++++
>  .../PeiDxeTpmPlatformHierarchyLib.inf         |  40 ++++
>  3 files changed, 277 insertions(+)
>  create mode 100644 OvmfPkg/Include/Library/TpmPlatformHierarchyLib.h
>  create mode 100644
> OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.c
>  create mode 100644
> OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.inf
>
> diff --git a/OvmfPkg/Include/Library/TpmPlatformHierarchyLib.h
> b/OvmfPkg/Include/Library/TpmPlatformHierarchyLib.h
> new file mode 100644
> index 0000000000..a872fa09dc
> --- /dev/null
> +++ b/OvmfPkg/Include/Library/TpmPlatformHierarchyLib.h
> @@ -0,0 +1,27 @@
> +/** @file
> +    TPM Platform Hierarchy configuration library.
> +
> +    This library provides functions for customizing the TPM's Platform
> Hierarchy
> +    Authorization Value (platformAuth) and Platform Hierarchy
> Authorization
> +    Policy (platformPolicy) can be defined through this function.
> +
> +Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) Microsoft Corporation.<BR>
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef _TPM_PLATFORM_HIERARCHY_LIB_H_
> +#define _TPM_PLATFORM_HIERARCHY_LIB_H_
> +
> +/**
> +   This service will perform the TPM Platform Hierarchy configuration at
> the SmmReadyToLock event.
> +
> +**/
> +VOID
> +EFIAPI
> +ConfigureTpmPlatformHierarchy (
> +  VOID
> +  );
> +
> +#endif
> diff --git
> a/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.c
> b/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.c
> new file mode 100644
> index 0000000000..ba2d99bb53
> --- /dev/null
> +++
> b/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.c
> @@ -0,0 +1,210 @@
> +/** @file
> +    TPM Platform Hierarchy configuration library.
> +
> +    This library provides functions for customizing the TPM's Platform
> Hierarchy
> +    Authorization Value (platformAuth) and Platform Hierarchy
> Authorization
> +    Policy (platformPolicy) can be defined through this function.
> +
> +    Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> +    Copyright (c) Microsoft Corporation.<BR>
> +    SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +    @par Specification Reference:
> +
> https://trustedcomputinggroup.org/resource/tcg-tpm-v2-0-provisioning-guidance/
> +**/
> +
> +#include <Uefi.h>
> +
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/MemoryAllocationLib.h>
> +#include <Library/RngLib.h>
> +#include <Library/Tpm2CommandLib.h>
> +#include <Library/Tpm2DeviceLib.h>
> +
> +//
> +// The authorization value may be no larger than the digest produced by
> the hash
> +//   algorithm used for context integrity.
> +//
> +#define      MAX_NEW_AUTHORIZATION_SIZE SHA512_DIGEST_SIZE
> +
> +UINT16       mAuthSize;
> +
> +/**
> +  Generate high-quality entropy source through RDRAND.
> +
> +  @param[in]   Length        Size of the buffer, in bytes, to fill with.
> +  @param[out]  Entropy       Pointer to the buffer to store the entropy
> data.
> +
> +  @retval EFI_SUCCESS        Entropy generation succeeded.
> +  @retval EFI_NOT_READY      Failed to request random data.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +RdRandGenerateEntropy (
> +  IN UINTN         Length,
> +  OUT UINT8        *Entropy
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINTN       BlockCount;
> +  UINT64      Seed[2];
> +  UINT8       *Ptr;
> +
> +  Status = EFI_NOT_READY;
> +  BlockCount = Length / 64;
> +  Ptr = (UINT8 *)Entropy;
> +
> +  //
> +  // Generate high-quality seed for DRBG Entropy
> +  //
> +  while (BlockCount > 0) {
> +    Status = GetRandomNumber128 (Seed);
> +    if (EFI_ERROR (Status)) {
> +      return Status;
> +    }
> +    CopyMem (Ptr, Seed, 64);
>

This looks like it's copying past the Seed buffer, which is 2 * sizeof(u64)
= 16.

+
> +    BlockCount--;
> +    Ptr = Ptr + 64;
> +  }
> +
> +  //
> +  // Populate the remained data as request.
> +  //
> +  Status = GetRandomNumber128 (Seed);
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +  CopyMem (Ptr, Seed, (Length % 64));
>

And then again.

Isn't there a better way to fill a buffer with random data in edk2?

+
> +  return Status;
> +}
> +
> +/**
> +  This function returns the maximum size of TPM2B_AUTH; this structure is
> used for an authorization value
> +  and limits an authValue to being no larger than the largest digest
> produced by a TPM.
> +
> +  @param[out] AuthSize                 Tpm2 Auth size
> +
> +  @retval EFI_SUCCESS                  Auth size returned.
> +  @retval EFI_DEVICE_ERROR             Can not return platform auth due
> to device error.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +GetAuthSize (
> +  OUT UINT16            *AuthSize
> +  )
> +{
> +  EFI_STATUS            Status;
> +  TPML_PCR_SELECTION    Pcrs;
> +  UINTN                 Index;
> +  UINT16                DigestSize;
> +
> +  Status = EFI_SUCCESS;
> +
> +  while (mAuthSize == 0) {
>

This is a bit odd, but ok.

+
> +    mAuthSize = SHA1_DIGEST_SIZE;
> +    ZeroMem (&Pcrs, sizeof (TPML_PCR_SELECTION));
> +    Status = Tpm2GetCapabilityPcrs (&Pcrs);
> +
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((DEBUG_ERROR, "Tpm2GetCapabilityPcrs fail!\n"));
> +      break;
> +    }
> +
> +    DEBUG ((DEBUG_ERROR, "Tpm2GetCapabilityPcrs - %08x\n", Pcrs.count));
> +
> +    for (Index = 0; Index < Pcrs.count; Index++) {
> +      DEBUG ((DEBUG_ERROR, "alg - %x\n", Pcrs.pcrSelections[Index].hash));
> +
> +      switch (Pcrs.pcrSelections[Index].hash) {
> +      case TPM_ALG_SHA1:
> +        DigestSize = SHA1_DIGEST_SIZE;
> +        break;
> +      case TPM_ALG_SHA256:
> +        DigestSize = SHA256_DIGEST_SIZE;
> +        break;
> +      case TPM_ALG_SHA384:
> +        DigestSize = SHA384_DIGEST_SIZE;
> +        break;
> +      case TPM_ALG_SHA512:
> +        DigestSize = SHA512_DIGEST_SIZE;
> +        break;
> +      case TPM_ALG_SM3_256:
> +        DigestSize = SM3_256_DIGEST_SIZE;
> +        break;
> +      default:
> +        DigestSize = SHA1_DIGEST_SIZE;
> +        break;
> +      }
> +
> +      if (DigestSize > mAuthSize) {
> +        mAuthSize = DigestSize;
> +      }
> +    }
> +    break;
> +  }
> +
> +  *AuthSize = mAuthSize;
> +  return Status;
> +}
> +
> +/**
> +  Set PlatformAuth to random value.
> +**/
> +VOID
> +RandomizePlatformAuth (
> +  VOID
> +  )
> +{
> +  EFI_STATUS                        Status;
> +  UINT16                            AuthSize;
> +  UINT8                             *Rand;
> +  UINTN                             RandSize;
> +  TPM2B_AUTH                        NewPlatformAuth;
> +
> +  //
> +  // Send Tpm2HierarchyChange Auth with random value to avoid
> PlatformAuth being null
> +  //
> +
> +  GetAuthSize (&AuthSize);
> +
> +  ZeroMem (NewPlatformAuth.buffer, AuthSize);
> +  NewPlatformAuth.size = AuthSize;
> +
> +  //
> +  // Allocate one buffer to store random data.
> +  //
> +  RandSize = MAX_NEW_AUTHORIZATION_SIZE;
> +  Rand = AllocatePool (RandSize);
> +
> +  RdRandGenerateEntropy (RandSize, Rand);
> +  CopyMem (NewPlatformAuth.buffer, Rand, AuthSize);
>

Why generate random data for MAX_NEW_AUTHORIZATION to only copy a subset
after?

+
> +  FreePool (Rand);
> +
> +  //
> +  // Send Tpm2HierarchyChangeAuth command with the new Auth value
> +  //
> +  Status = Tpm2HierarchyChangeAuth (TPM_RH_PLATFORM, NULL,
> &NewPlatformAuth);
> +  DEBUG ((DEBUG_INFO, "Tpm2HierarchyChangeAuth Result: - %r\n", Status));
> +  ZeroMem (NewPlatformAuth.buffer, AuthSize);
> +  ZeroMem (Rand, RandSize);
>

Isn't Rand free at this point?

+}
> +
> +/**
> +   This service defines the configuration of the Platform Hierarchy
> Authorization Value (platformAuth)
> +   and Platform Hierarchy Authorization Policy (platformPolicy)
> +
> +**/
> +VOID
> +EFIAPI
> +ConfigureTpmPlatformHierarchy (
> +  )
> +{
> +  RandomizePlatformAuth ();
> +}
> diff --git
> a/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.inf
> b/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.inf
> new file mode 100644
> index 0000000000..a413e02302
> --- /dev/null
> +++
> b/OvmfPkg/Library/PeiDxeTpmPlatformHierarchyLib/PeiDxeTpmPlatformHierarchyLib.inf
> @@ -0,0 +1,40 @@
> +### @file
> +#
> +#   TPM Platform Hierarchy configuration library.
> +#
> +#   This library provides functions for customizing the TPM's Platform
> Hierarchy
> +#   Authorization Value (platformAuth) and Platform Hierarchy
> Authorization
> +#   Policy (platformPolicy) can be defined through this function.
> +#
> +# Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> +# Copyright (c) Microsoft Corporation.<BR>
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +###
> +
> +[Defines]
> +  INF_VERSION                    = 0x00010005
> +  BASE_NAME                      = PeiDxeTpmPlatformHierarchyLib
> +  FILE_GUID                      = 7794F92C-4E8E-4E57-9E4A-49A0764C7D73
> +  MODULE_TYPE                    = PEIM
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = TpmPlatformHierarchyLib|PEIM DXE_DRIVER
> +
> +[LibraryClasses]
> +  BaseLib
> +  BaseMemoryLib
> +  DebugLib
> +  MemoryAllocationLib
> +  RngLib
> +  Tpm2CommandLib
> +  Tpm2DeviceLib
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  MdeModulePkg/MdeModulePkg.dec
> +  SecurityPkg/SecurityPkg.dec
> +  CryptoPkg/CryptoPkg.dec
> +
> +[Sources]
> +  PeiDxeTpmPlatformHierarchyLib.c
> --
> 2.31.1
>
>

[-- Attachment #2: Type: text/html, Size: 12944 bytes --]