CVE-2022-37967 Add new PAC checksum

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15231

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

1 files changed, 73 insertions, 5 deletions

diff --git a/python/samba/tests/krb5/raw_testcase.py b/python/samba/tests/krb5/raw_testcase.py
index 4f683a9631b..4fb2b7bf181 100644
--- a/python/samba/tests/krb5/raw_testcase.py
+++ b/python/samba/tests/krb5/raw_testcase.py
@@ -557,7 +557,8 @@ class RawKerberosTest(TestCaseInTempDir):
 
     pac_checksum_types = {krb5pac.PAC_TYPE_SRV_CHECKSUM,
                           krb5pac.PAC_TYPE_KDC_CHECKSUM,
-                          krb5pac.PAC_TYPE_TICKET_CHECKSUM}
+                          krb5pac.PAC_TYPE_TICKET_CHECKSUM,
+                          krb5pac.PAC_TYPE_FULL_CHECKSUM}
 
     etypes_to_test = (
         {"value": -1111, "name": "dummy", },
@@ -651,6 +652,12 @@ class RawKerberosTest(TestCaseInTempDir):
             tkt_sig_support = '0'
         cls.tkt_sig_support = bool(int(tkt_sig_support))
 
+        full_sig_support = samba.tests.env_get_var_value('FULL_SIG_SUPPORT',
+                                                         allow_missing=True)
+        if full_sig_support is None:
+            full_sig_support = '0'
+        cls.full_sig_support = bool(int(full_sig_support))
+
         gnutls_pbkdf2_support = samba.tests.env_get_var_value(
             'GNUTLS_PBKDF2_SUPPORT',
             allow_missing=True)
@@ -2434,6 +2441,7 @@ class RawKerberosTest(TestCaseInTempDir):
                          unexpected_flags=None,
                          ticket_decryption_key=None,
                          expect_ticket_checksum=None,
+                         expect_full_checksum=None,
                          generate_fast_fn=None,
                          generate_fast_armor_fn=None,
                          generate_fast_padata_fn=None,
@@ -2503,6 +2511,7 @@ class RawKerberosTest(TestCaseInTempDir):
             'unexpected_flags': unexpected_flags,
             'ticket_decryption_key': ticket_decryption_key,
             'expect_ticket_checksum': expect_ticket_checksum,
+            'expect_full_checksum': expect_full_checksum,
             'generate_fast_fn': generate_fast_fn,
             'generate_fast_armor_fn': generate_fast_armor_fn,
             'generate_fast_padata_fn': generate_fast_padata_fn,
@@ -2568,6 +2577,7 @@ class RawKerberosTest(TestCaseInTempDir):
                           unexpected_flags=None,
                           ticket_decryption_key=None,
                           expect_ticket_checksum=None,
+                          expect_full_checksum=None,
                           generate_fast_fn=None,
                           generate_fast_armor_fn=None,
                           generate_fast_padata_fn=None,
@@ -2638,6 +2648,7 @@ class RawKerberosTest(TestCaseInTempDir):
             'unexpected_flags': unexpected_flags,
             'ticket_decryption_key': ticket_decryption_key,
             'expect_ticket_checksum': expect_ticket_checksum,
+            'expect_full_checksum': expect_full_checksum,
             'generate_fast_fn': generate_fast_fn,
             'generate_fast_armor_fn': generate_fast_armor_fn,
             'generate_fast_padata_fn': generate_fast_padata_fn,
@@ -3120,7 +3131,8 @@ class RawKerberosTest(TestCaseInTempDir):
                 self.check_pac_buffers(pac_data, kdc_exchange_dict)
 
         expect_ticket_checksum = kdc_exchange_dict['expect_ticket_checksum']
-        if expect_ticket_checksum:
+        expect_full_checksum = kdc_exchange_dict['expect_full_checksum']
+        if expect_ticket_checksum or expect_full_checksum:
             self.assertIsNotNone(ticket_decryption_key)
 
         if ticket_decryption_key is not None:
@@ -3130,7 +3142,9 @@ class RawKerberosTest(TestCaseInTempDir):
                                service_ticket=service_ticket,
                                expect_pac=expect_pac,
                                expect_ticket_checksum=expect_ticket_checksum
-                               or self.tkt_sig_support)
+                               or self.tkt_sig_support,
+                               expect_full_checksum=expect_full_checksum
+                               or self.full_sig_support)
 
         kdc_exchange_dict['rep_ticket_creds'] = ticket_creds
 
@@ -3267,6 +3281,8 @@ class RawKerberosTest(TestCaseInTempDir):
         unchecked = set()
         if not self.tkt_sig_support:
             require_strict.add(krb5pac.PAC_TYPE_TICKET_CHECKSUM)
+        if not self.full_sig_support:
+            require_strict.add(krb5pac.PAC_TYPE_FULL_CHECKSUM)
 
         expected_client_claims = kdc_exchange_dict['expected_client_claims']
         unexpected_client_claims = kdc_exchange_dict[
@@ -3323,6 +3339,7 @@ class RawKerberosTest(TestCaseInTempDir):
         if rep_msg_type == KRB_TGS_REP:
             if not self.is_tgs_principal(expected_sname):
                 expected_types.append(krb5pac.PAC_TYPE_TICKET_CHECKSUM)
+                expected_types.append(krb5pac.PAC_TYPE_FULL_CHECKSUM)
 
         expect_extra_pac_buffers = self.is_tgs(expected_sname)
 
@@ -4194,7 +4211,8 @@ class RawKerberosTest(TestCaseInTempDir):
 
     def verify_ticket(self, ticket, krbtgt_keys, service_ticket,
                       expect_pac=True,
-                      expect_ticket_checksum=True):
+                      expect_ticket_checksum=True,
+                      expect_full_checksum=None):
         # Decrypt the ticket.
 
         key = ticket.decryption_key
@@ -4239,6 +4257,8 @@ class RawKerberosTest(TestCaseInTempDir):
 
         checksums = {}
 
+        full_checksum_buffer = None
+
         for pac_buffer, raw_pac_buffer in zip(pac.buffers, raw_pac.buffers):
             buffer_type = pac_buffer.type
             if buffer_type in self.pac_checksum_types:
@@ -4253,7 +4273,9 @@ class RawKerberosTest(TestCaseInTempDir):
 
                 checksums[buffer_type] = checksum, ctype
 
-                if buffer_type != krb5pac.PAC_TYPE_TICKET_CHECKSUM:
+                if buffer_type == krb5pac.PAC_TYPE_FULL_CHECKSUM:
+                    full_checksum_buffer = raw_pac_buffer
+                elif buffer_type != krb5pac.PAC_TYPE_TICKET_CHECKSUM:
                     # Zero the checksum field so that we can later verify the
                     # checksums. The ticket checksum field is not zeroed.
 
@@ -4267,6 +4289,17 @@ class RawKerberosTest(TestCaseInTempDir):
         # Re-encode the PAC.
         pac_data = ndr_pack(raw_pac)
 
+        if full_checksum_buffer is not None:
+            signature = ndr_unpack(
+                krb5pac.PAC_SIGNATURE_DATA,
+                full_checksum_buffer.info.remaining)
+            signature.signature = bytes(len(checksum))
+            full_checksum_buffer.info.remaining = ndr_pack(
+                signature)
+
+            # Re-encode the PAC.
+            full_pac_data = ndr_pack(raw_pac)
+
         # Verify the signatures.
 
         server_checksum, server_ctype = checksums[
@@ -4295,6 +4328,7 @@ class RawKerberosTest(TestCaseInTempDir):
 
         if not service_ticket:
             self.assertNotIn(krb5pac.PAC_TYPE_TICKET_CHECKSUM, checksums)
+            self.assertNotIn(krb5pac.PAC_TYPE_FULL_CHECKSUM, checksums)
         else:
             ticket_checksum, ticket_ctype = checksums.get(
                 krb5pac.PAC_TYPE_TICKET_CHECKSUM,
@@ -4313,6 +4347,19 @@ class RawKerberosTest(TestCaseInTempDir):
                                                 ticket_ctype,
                                                 ticket_checksum)
 
+            full_checksum, full_ctype = checksums.get(
+                krb5pac.PAC_TYPE_FULL_CHECKSUM,
+                (None, None))
+            if expect_full_checksum:
+                self.assertIsNotNone(full_checksum)
+            elif expect_full_checksum is False:
+                self.assertIsNone(full_checksum)
+            if full_checksum is not None:
+                krbtgt_key.verify_rodc_checksum(KU_NON_KERB_CKSUM_SALT,
+                                                full_pac_data,
+                                                full_ctype,
+                                                full_checksum)
+
     def modified_ticket(self,
                         ticket, *,
                         new_ticket_key=None,
@@ -4370,6 +4417,14 @@ class RawKerberosTest(TestCaseInTempDir):
                 checksum_keys[krb5pac.PAC_TYPE_TICKET_CHECKSUM] = (
                     kdc_checksum_key)
 
+        if krb5pac.PAC_TYPE_FULL_CHECKSUM not in checksum_keys:
+            # If the full signature key is not present, fall back to the key
+            # used for the KDC signature.
+            kdc_checksum_key = checksum_keys.get(krb5pac.PAC_TYPE_KDC_CHECKSUM)
+            if kdc_checksum_key is not None:
+                checksum_keys[krb5pac.PAC_TYPE_FULL_CHECKSUM] = (
+                    kdc_checksum_key)
+
         # Decrypt the ticket.
 
         enc_part = ticket.ticket['enc-part']
@@ -4522,6 +4577,19 @@ class RawKerberosTest(TestCaseInTempDir):
         # Add the new checksum buffers to the PAC.
         pac.buffers = pac_buffers
 
+        # Calculate the full checksum and insert it into the PAC.
+        full_checksum_buffer = checksum_buffers.get(
+            krb5pac.PAC_TYPE_FULL_CHECKSUM)
+        if full_checksum_buffer is not None:
+            full_checksum_key = checksum_keys[krb5pac.PAC_TYPE_FULL_CHECKSUM]
+
+            pac_data = ndr_pack(pac)
+            full_checksum = full_checksum_key.make_checksum(
+                KU_NON_KERB_CKSUM_SALT,
+                pac_data)
+
+            full_checksum_buffer.info.signature = full_checksum
+
         # Calculate the server and KDC checksums and insert them into the PAC.
 
         server_checksum_buffer = checksum_buffers.get(