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


Yao, Jiewen
 

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

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