Re: [PATCH] Reallocate TPM Active PCRs based on platform support.

["Rodrigo Gonzalez del Cueto" <rodrigo.gonzalez.del.cueto@intel.com>]

[-- Attachment #1: Type: text/plain, Size: 8674 bytes --]

Hi Jiewen,

Indeed, this bug has existed for a long time in this code. What recently changed are the TPM configurations we are testing and exposed the issue; this can be reproduced when the BIOS supported algorithms are a strict subset of the PCRs currently active in the TPM.

Now that we are using TPM configurations with support for additional PCR banks (ex. SHA384 and SM3) the bug has been exposed when compiling a BIOS without support for these PCR banks which are active by default in the some of the TPMs.

Regards,
-Rodrigo

________________________________
From: Yao, Jiewen <jiewen.yao@intel.com>
Sent: Sunday, August 8, 2021 6:13 PM
To: Gonzalez Del Cueto, Rodrigo <rodrigo.gonzalez.del.cueto@intel.com>; devel@edk2.groups.io <devel@edk2.groups.io>
Cc: Wang, Jian J <jian.j.wang@intel.com>
Subject: RE: [PATCH] Reallocate TPM Active PCRs based on platform support.

Hi Rodrigo
I don’t understand the problem statement.

This code has been there for long time. What is changed recently ?

Thank you
Yao Jiewen


> -----Original Message-----
> From: Gonzalez Del Cueto, Rodrigo <rodrigo.gonzalez.del.cueto@intel.com>
> Sent: Thursday, August 5, 2021 7:28 AM
> To: devel@edk2.groups.io
> Cc: Gonzalez Del Cueto, Rodrigo <rodrigo.gonzalez.del.cueto@intel.com>;
> Wang, Jian J <jian.j.wang@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> Subject: [PATCH] Reallocate TPM Active PCRs based on platform support.
>
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3515
>
> In V2: Add case to RegisterHashInterfaceLib logic
>
> RegisterHashInterfaceLib needs to correctly handle registering the HashLib
> instance supported algorithm bitmap when PcdTpm2HashMask is set to zero.
>
> The current implementation of SyncPcrAllocationsAndPcrMask() triggers
> PCR bank reallocation only based on the intersection between
> TpmActivePcrBanks and PcdTpm2HashMask.
>
> When the software HashLibBaseCryptoRouter solution is used, no PCR bank
> reallocation is occurring based on the supported hashing algorithms
> registered by the HashLib instances.
>
> Need to have an additional check for the intersection between the
> TpmActivePcrBanks and the PcdTcg2HashAlgorithmBitmap populated by the
> HashLib instances present on the platform's BIOS.
>
> Signed-off-by: Rodrigo Gonzalez del Cueto
> <rodrigo.gonzalez.del.cueto@intel.com>
>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> ---
>  SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterDxe.c
> |  6 +++++-
>  SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterPei.c |
> 6 +++++-
>  SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c                                        | 18
> +++++++++++++++++-
>  SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf                                      |  1 +
>  4 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git
> a/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterDxe.
> c
> b/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterDxe.
> c
> index 7a0f61efbb..0821159120 100644
> ---
> a/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterDxe.
> c
> +++
> b/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterDxe.
> c
> @@ -230,13 +230,17 @@ RegisterHashInterfaceLib (
>  {
>    UINTN              Index;
>    UINT32             HashMask;
> +  UINT32             Tpm2HashMask;
>    EFI_STATUS         Status;
>
>    //
>    // Check allow
>    //
>    HashMask = Tpm2GetHashMaskFromAlgo (&HashInterface->HashGuid);
> -  if ((HashMask & PcdGet32 (PcdTpm2HashMask)) == 0) {
> +  Tpm2HashMask = PcdGet32 (PcdTpm2HashMask);
> +
> +  if ((Tpm2HashMask != 0) &&
> +      ((HashMask & Tpm2HashMask) == 0)) {
>      return EFI_UNSUPPORTED;
>    }
>
> diff --git
> a/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterPei.c
> b/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterPei.c
> index 42cb562f67..6ae51dbce4 100644
> ---
> a/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterPei.c
> +++
> b/SecurityPkg/Library/HashLibBaseCryptoRouter/HashLibBaseCryptoRouterPei.c
> @@ -327,13 +327,17 @@ RegisterHashInterfaceLib (
>    UINTN              Index;
>    HASH_INTERFACE_HOB *HashInterfaceHob;
>    UINT32             HashMask;
> +  UINT32             Tpm2HashMask;
>    EFI_STATUS         Status;
>
>    //
>    // Check allow
>    //
>    HashMask = Tpm2GetHashMaskFromAlgo (&HashInterface->HashGuid);
> -  if ((HashMask & PcdGet32 (PcdTpm2HashMask)) == 0) {
> +  Tpm2HashMask = PcdGet32 (PcdTpm2HashMask);
> +
> +  if ((Tpm2HashMask != 0) &&
> +      ((HashMask & Tpm2HashMask) == 0)) {
>      return EFI_UNSUPPORTED;
>    }
>
> diff --git a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> index 93a8803ff6..5ad6a45cf3 100644
> --- a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> +++ b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> @@ -262,6 +262,7 @@ SyncPcrAllocationsAndPcrMask (
>  {
>    EFI_STATUS                        Status;
>    EFI_TCG2_EVENT_ALGORITHM_BITMAP   TpmHashAlgorithmBitmap;
> +  EFI_TCG2_EVENT_ALGORITHM_BITMAP   BiosHashAlgorithmBitmap;
>    UINT32                            TpmActivePcrBanks;
>    UINT32                            NewTpmActivePcrBanks;
>    UINT32                            Tpm2PcrMask;
> @@ -273,16 +274,27 @@ SyncPcrAllocationsAndPcrMask (
>    // Determine the current TPM support and the Platform PCR mask.
>    //
>    Status = Tpm2GetCapabilitySupportedAndActivePcrs
> (&TpmHashAlgorithmBitmap, &TpmActivePcrBanks);
> +
>    ASSERT_EFI_ERROR (Status);
> +
> +  DEBUG ((EFI_D_INFO, "Tpm2GetCapabilitySupportedAndActivePcrs -
> TpmHashAlgorithmBitmap: 0x%08x\n", TpmHashAlgorithmBitmap));
> +  DEBUG ((EFI_D_INFO, "Tpm2GetCapabilitySupportedAndActivePcrs -
> TpmActivePcrBanks 0x%08x\n", TpmActivePcrBanks));
>
>    Tpm2PcrMask = PcdGet32 (PcdTpm2HashMask);
>    if (Tpm2PcrMask == 0) {
>      //
>      // if PcdTPm2HashMask is zero, use ActivePcr setting
>      //
> +    DEBUG ((EFI_D_VERBOSE, "Initializing PcdTpm2HashMask to
> TpmActivePcrBanks 0x%08x\n", TpmActivePcrBanks));
>      PcdSet32S (PcdTpm2HashMask, TpmActivePcrBanks);
> +    DEBUG ((EFI_D_VERBOSE, "Initializing Tpm2PcrMask to TpmActivePcrBanks
> 0x%08x\n", Tpm2PcrMask));
>      Tpm2PcrMask = TpmActivePcrBanks;
>    }
> +
> +  BiosHashAlgorithmBitmap = PcdGet32 (PcdTcg2HashAlgorithmBitmap);
> +  DEBUG ((EFI_D_INFO, "PcdTcg2HashAlgorithmBitmap 0x%08x\n",
> BiosHashAlgorithmBitmap));
> +  DEBUG ((EFI_D_INFO, "Tpm2PcrMask 0x%08x\n", Tpm2PcrMask)); // Active
> PCR banks from TPM input
> +  DEBUG ((EFI_D_INFO, "TpmActivePcrBanks & BiosHashAlgorithmBitmap =
> 0x%08x\n", NewTpmActivePcrBanks));
>
>    //
>    // Find the intersection of Pcd support and TPM support.
> @@ -294,9 +306,12 @@ SyncPcrAllocationsAndPcrMask (
>    // If there are active PCR banks that are not supported by the Platform mask,
>    // update the TPM allocations and reboot the machine.
>    //
> -  if ((TpmActivePcrBanks & Tpm2PcrMask) != TpmActivePcrBanks) {
> +  if (((TpmActivePcrBanks & Tpm2PcrMask) != TpmActivePcrBanks) ||
> +      ((TpmActivePcrBanks & BiosHashAlgorithmBitmap) != TpmActivePcrBanks)) {
>      NewTpmActivePcrBanks = TpmActivePcrBanks & Tpm2PcrMask;
> +    NewTpmActivePcrBanks &= BiosHashAlgorithmBitmap;
>
> +    DEBUG ((EFI_D_INFO, "NewTpmActivePcrBanks 0x%08x\n",
> NewTpmActivePcrBanks));
>      DEBUG ((EFI_D_INFO, "%a - Reallocating PCR banks from 0x%X to 0x%X.\n",
> __FUNCTION__, TpmActivePcrBanks, NewTpmActivePcrBanks));
>      if (NewTpmActivePcrBanks == 0) {
>        DEBUG ((EFI_D_ERROR, "%a - No viable PCRs active! Please set a less
> restrictive value for PcdTpm2HashMask!\n", __FUNCTION__));
> @@ -331,6 +346,7 @@ SyncPcrAllocationsAndPcrMask (
>      }
>
>      Status = PcdSet32S (PcdTpm2HashMask, NewTpm2PcrMask);
> +    DEBUG ((EFI_D_INFO, "Setting PcdTpm2Hash Mask to 0x%08x\n",
> NewTpm2PcrMask));
>      ASSERT_EFI_ERROR (Status);
>    }
>  }
> diff --git a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf
> b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf
> index 06c26a2904..17ad116126 100644
> --- a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf
> +++ b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf
> @@ -86,6 +86,7 @@
>    ## SOMETIMES_CONSUMES
>    ## SOMETIMES_PRODUCES
>    gEfiSecurityPkgTokenSpaceGuid.PcdTpm2HashMask
> +  gEfiSecurityPkgTokenSpaceGuid.PcdTcg2HashAlgorithmBitmap                  ##
> CONSUMES
>
>  [Depex]
>    gEfiPeiMasterBootModePpiGuid AND
> --
> 2.31.1.windows.1


[-- Attachment #2: Type: text/html, Size: 15537 bytes --]