linux-kernel - [PATCH v3 1/3] selftests: tpm2: Probe for available PCR bank

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Date:   Wed, 24 Nov 2021 19:38:25 -0500
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     jarkko@...nel.org, linux-integrity@...r.kernel.org
Cc:     peterhuewe@....de, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, skhan@...uxfoundation.org,
        Stefan Berger <stefanb@...ux.ibm.com>
Subject: [PATCH v3 1/3] selftests: tpm2: Probe for available PCR bank

From: Stefan Berger <stefanb@...ux.ibm.com>

Probe for an available PCR bank to accommodate devices that do not have a
SHA-1 PCR bank or whose SHA-1 bank is deactivated. Use the bank that can
be used for the TPM2 commands, such as the SHA-256 bank.

Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
---
 tools/testing/selftests/tpm2/tpm2_tests.py | 35 +++++++++++++++++-----
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/tpm2/tpm2_tests.py b/tools/testing/selftests/tpm2/tpm2_tests.py
index 9d764306887b..6b88ff0e47b9 100644
--- a/tools/testing/selftests/tpm2/tpm2_tests.py
+++ b/tools/testing/selftests/tpm2/tpm2_tests.py
@@ -27,7 +27,23 @@ class SmokeTest(unittest.TestCase):
         result = self.client.unseal(self.root_key, blob, auth, None)
         self.assertEqual(data, result)
 
+    def determine_bank_alg(self):
+        # Probe for available PCR bank
+        for bank_alg in [tpm2.TPM2_ALG_SHA1, tpm2.TPM2_ALG_SHA256]:
+            try:
+                handle = self.client.start_auth_session(tpm2.TPM2_SE_TRIAL)
+                self.client.policy_pcr(handle, [17], bank_alg=bank_alg)
+                return bank_alg
+            except tpm2.UnknownPCRBankError:
+                pass
+            finally:
+                self.client.flush_context(handle)
+        return None
+
     def test_seal_with_policy(self):
+        bank_alg = self.determine_bank_alg()
+        self.assertIsNotNone(bank_alg)
+
         handle = self.client.start_auth_session(tpm2.TPM2_SE_TRIAL)
 
         data = ('X' * 64).encode()
@@ -35,7 +51,7 @@ class SmokeTest(unittest.TestCase):
         pcrs = [16]
 
         try:
-            self.client.policy_pcr(handle, pcrs)
+            self.client.policy_pcr(handle, pcrs, bank_alg=bank_alg)
             self.client.policy_password(handle)
 
             policy_dig = self.client.get_policy_digest(handle)
@@ -47,7 +63,7 @@ class SmokeTest(unittest.TestCase):
         handle = self.client.start_auth_session(tpm2.TPM2_SE_POLICY)
 
         try:
-            self.client.policy_pcr(handle, pcrs)
+            self.client.policy_pcr(handle, pcrs, bank_alg=bank_alg)
             self.client.policy_password(handle)
 
             result = self.client.unseal(self.root_key, blob, auth, handle)
@@ -72,6 +88,9 @@ class SmokeTest(unittest.TestCase):
         self.assertEqual(rc, tpm2.TPM2_RC_AUTH_FAIL)
 
     def test_unseal_with_wrong_policy(self):
+        bank_alg = self.determine_bank_alg()
+        self.assertIsNotNone(bank_alg)
+
         handle = self.client.start_auth_session(tpm2.TPM2_SE_TRIAL)
 
         data = ('X' * 64).encode()
@@ -79,7 +98,7 @@ class SmokeTest(unittest.TestCase):
         pcrs = [16]
 
         try:
-            self.client.policy_pcr(handle, pcrs)
+            self.client.policy_pcr(handle, pcrs, bank_alg=bank_alg)
             self.client.policy_password(handle)
 
             policy_dig = self.client.get_policy_digest(handle)
@@ -91,13 +110,13 @@ class SmokeTest(unittest.TestCase):
         # Extend first a PCR that is not part of the policy and try to unseal.
         # This should succeed.
 
-        ds = tpm2.get_digest_size(tpm2.TPM2_ALG_SHA1)
-        self.client.extend_pcr(1, ('X' * ds).encode())
+        ds = tpm2.get_digest_size(bank_alg)
+        self.client.extend_pcr(1, ('X' * ds).encode(), bank_alg=bank_alg)
 
         handle = self.client.start_auth_session(tpm2.TPM2_SE_POLICY)
 
         try:
-            self.client.policy_pcr(handle, pcrs)
+            self.client.policy_pcr(handle, pcrs, bank_alg=bank_alg)
             self.client.policy_password(handle)
 
             result = self.client.unseal(self.root_key, blob, auth, handle)
@@ -109,14 +128,14 @@ class SmokeTest(unittest.TestCase):
 
         # Then, extend a PCR that is part of the policy and try to unseal.
         # This should fail.
-        self.client.extend_pcr(16, ('X' * ds).encode())
+        self.client.extend_pcr(16, ('X' * ds).encode(), bank_alg=bank_alg)
 
         handle = self.client.start_auth_session(tpm2.TPM2_SE_POLICY)
 
         rc = 0
 
         try:
-            self.client.policy_pcr(handle, pcrs)
+            self.client.policy_pcr(handle, pcrs, bank_alg=bank_alg)
             self.client.policy_password(handle)
 
             result = self.client.unseal(self.root_key, blob, auth, handle)
-- 
2.31.1