Re: [PATCH v2 1/3] selftests: tpm2: Probe for available PCR bank

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On 11/24/21 18:54, Jarkko Sakkinen wrote:
On Wed, Nov 24, 2021 at 09:13:12AM -0500, Stefan Berger wrote:
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 in the TPM2 commands. Assert on the probing function to not
return None.
What is *the bank* that can be used?

The bank can be either SHA-1 or SHA-256 at this point.


In addition, I don't understand the last sentence.


If the probing function returns None the test fails due to an assertIsNotNone().

   stefan


/Jarkko


Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
  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




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