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/** @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.
//
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 / sizeof(Seed);
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, sizeof(Seed));
BlockCount--;
Ptr = Ptr + sizeof(Seed);
}
//
// Populate the remained data as request.
//
Status = GetRandomNumber128 (Seed);
if (EFI_ERROR (Status)) {
return Status;
}
CopyMem (Ptr, Seed, (Length % sizeof(Seed)));
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) {
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;
TPM2B_AUTH NewPlatformAuth;
//
// Send Tpm2HierarchyChange Auth with random value to avoid PlatformAuth being null
//
GetAuthSize (&AuthSize);
NewPlatformAuth.size = AuthSize;
//
// Create the random bytes in the destination buffer
//
RdRandGenerateEntropy (NewPlatformAuth.size, NewPlatformAuth.buffer);
//
// 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);
}
/**
Disable the TPM platform hierarchy.
@retval EFI_SUCCESS The TPM was disabled successfully.
@retval Others An error occurred attempting to disable the TPM platform hierarchy.
**/
EFI_STATUS
DisableTpmPlatformHierarchy (
VOID
)
{
EFI_STATUS Status;
// Make sure that we have use of the TPM.
Status = Tpm2RequestUseTpm ();
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a:%a() - Tpm2RequestUseTpm Failed! %r\n", gEfiCallerBaseName, __FUNCTION__, Status));
ASSERT_EFI_ERROR (Status);
return Status;
}
// Let's do what we can to shut down the hierarchies.
// Disable the PH NV.
// IMPORTANT NOTE: We *should* be able to disable the PH NV here, but TPM parts have
// been known to store the EK cert in the PH NV. If we disable it, the
// EK cert will be unreadable.
// Disable the PH.
Status = Tpm2HierarchyControl (
TPM_RH_PLATFORM, // AuthHandle
NULL, // AuthSession
TPM_RH_PLATFORM, // Hierarchy
NO // State
);
DEBUG ((DEBUG_VERBOSE, "%a:%a() - Disable PH = %r\n", gEfiCallerBaseName, __FUNCTION__, Status));
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a:%a() - Disable PH Failed! %r\n", gEfiCallerBaseName, __FUNCTION__, Status));
ASSERT_EFI_ERROR (Status);
}
return Status;
}
/**
This service defines the configuration of the Platform Hierarchy Authorization Value (platformAuth)
and Platform Hierarchy Authorization Policy (platformPolicy).
**/
VOID
EFIAPI
ConfigureTpmPlatformHierarchy (
)
{
if (PcdGetBool (PcdRandomizePlatformHierarchy)) {
//
// Send Tpm2HierarchyChange Auth with random value to avoid PlatformAuth being null
//
RandomizePlatformAuth ();
} else {
//
// Disable the hierarchy entirely (do not randomize it)
//
DisableTpmPlatformHierarchy ();
}
}
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