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


Rodrigo Gonzalez del Cueto
 

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3515

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.

Change-Id: I1cdabe14a4fb5adfc289a2dd60f1b467c64282ac
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/Tcg/Tcg2Pei/Tcg2Pei.c | 18 +++++++++++++++++-
SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf | 1 +
2 files changed, 18 insertions(+), 1 deletion(-)

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

Join devel@edk2.groups.io to automatically receive all group messages.