[edk2-devel] [PATCH v3 1/6] OvmfPkg/TPM: Import PeiDxeTpmPlatformHierarchyLib.c from edk2-platforms
Stefan Berger
stefanb at linux.ibm.com
Thu Aug 12 15:30:24 UTC 2021
On 8/12/21 9:48 AM, Marc-André Lureau wrote:
> Hi On Tue, Aug 10, 2021 at 9:22 PM Stefan Berger
> <stefanb at linux.vnet.ibm.com> wrote: Import
> PeiDxeTpmPlatformHierarchyLib.c from edk2-platforms. Modify it so that
> ConfigureTpmPlatformHierarchy() is the only public function provided
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> Hi
>
> On Tue, Aug 10, 2021 at 9:22 PM Stefan Berger
> <stefanb at linux.vnet.ibm.com <mailto:stefanb at 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 at linux.ibm.com
> <mailto:stefanb at 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/
> <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.
Ha! Thanks for looking at this. Those seem to be the pitfalls of blindly
importing code from edk2-platforms. Now the question is whether to leave
it broken in edk2-platforms or fix it there first before trying to
import it to edk2. In the interest of time I'd rather fix it here.
Obviously the BlockCount is also wrong.
>
> +
> + 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?
I don't know. On ARM it *looks like* the path goes down to an assembly
instruction getting 64bit random number from the hardware:
MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
On x86 it will end up calling GenerateRandomNumberViaNist800Algorithm:
MdePkg/Library/DxeRngLib/DxeRngLib.c
CryptoPkg/Drvier/Crypto.c has this here:
BOOLEAN
EFIAPI
CryptoServiceRandomSeed (
IN CONST UINT8 *Seed OPTIONAL,
IN UINTN SeedSize
)
{
return CALL_BASECRYPTLIB (Random.Services.Seed, RandomSeed, (Seed,
SeedSize)
}
and this one:
BOOLEAN
EFIAPI
CryptoServiceRandomBytes (
OUT UINT8 *Output,
IN UINTN Size
)
{
return CALL_BASECRYPTLIB (Random.Services.Bytes, RandomBytes,
(Output, Size)
}
Those are pseudorandom numbers. I don't know about others.
>
> +
> + 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?
Indeed!
>
> +}
> +
> +/**
> + 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
>
>
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