selftest: add python S4U2Self tests including unkeyed checksums

To test the CRC32 I reverted the unkeyed-checksum fix (43958af1)
and the weak-crypto fix (389d1b97). Note that the unkeyed-md5
still worked even with weak-crypto disabled, and that the
unkeyed-sha1 never worked but I left it anyway.

Signed-off-by: Isaac Boukris <iboukris@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri May 15 12:25:40 UTC 2020 on sn-devel-184

6 files changed, 327 insertions, 1 deletions

diff --git a/python/samba/tests/krb5/kcrypto.py b/python/samba/tests/krb5/kcrypto.py
index ed3c84fa186..2572fa5bab3 100755
--- a/python/samba/tests/krb5/kcrypto.py
+++ b/python/samba/tests/krb5/kcrypto.py
@@ -51,6 +51,7 @@ os.environ["PYTHONUNBUFFERED"] = "1"
 from math import gcd
 from functools import reduce
 from struct import pack, unpack
+from binascii import crc32
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives import hmac
 from cryptography.hazmat.primitives.ciphers import algorithms as ciphers
@@ -533,6 +534,21 @@ class _MD5(_ChecksumProfile):
         return SIMPLE_HASH(text, hashes.MD5)
 
 
+class _SHA1(_ChecksumProfile):
+    @classmethod
+    def checksum(cls, key, keyusage, text):
+        # This is unkeyed!
+        return SIMPLE_HASH(text, hashes.SHA1)
+
+
+class _CRC32(_ChecksumProfile):
+    @classmethod
+    def checksum(cls, key, keyusage, text):
+        # This is unkeyed!
+        cksum = (~crc32(text, 0xffffffff)) & 0xffffffff
+        return pack('<I', cksum)
+
+
 _enctype_table = {
     Enctype.DES3: _DES3CBC,
     Enctype.AES128: _AES128CTS,
@@ -547,6 +563,8 @@ _checksum_table = {
     Cksumtype.SHA1_AES256: _SHA1AES256,
     Cksumtype.HMAC_MD5: _HMACMD5,
     Cksumtype.MD5: _MD5,
+    Cksumtype.SHA1: _SHA1,
+    Cksumtype.CRC32: _CRC32,
 }
 
 
@@ -835,6 +853,73 @@ class KcrytoTest(TestCase):
     def test_md5_unkeyed_checksum_aes256_usage_50(self):
         return self._test_md5_unkeyed_checksum(Enctype.AES256, 50)
 
+    def _test_sha1_unkeyed_checksum(self, etype, usage):
+        # SHA1 unkeyed checksum
+        pw = b'password'
+        salt = b'salt'
+        key = string_to_key(etype, pw, salt)
+        plain = b'twenty nineteen eighteen seventeen'
+        cksum = h('381c870d8875d1913555de19af5c885fd27b7da9')
+        verify_checksum(Cksumtype.SHA1, key, usage, plain, cksum)
+
+    def test_sha1_unkeyed_checksum_des3_usage_40(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.DES3, 40)
+
+    def test_sha1_unkeyed_checksum_des3_usage_50(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.DES3, 50)
+
+    def test_sha1_unkeyed_checksum_rc4_usage_40(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.RC4, 40)
+
+    def test_sha1_unkeyed_checksum_rc4_usage_50(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.RC4, 50)
+
+    def test_sha1_unkeyed_checksum_aes128_usage_40(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.AES128, 40)
+
+    def test_sha1_unkeyed_checksum_aes128_usage_50(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.AES128, 50)
+
+    def test_sha1_unkeyed_checksum_aes256_usage_40(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.AES256, 40)
+
+    def test_sha1_unkeyed_checksum_aes256_usage_50(self):
+        return self._test_sha1_unkeyed_checksum(Enctype.AES256, 50)
+
+    def _test_crc32_unkeyed_checksum(self, etype, usage):
+        # CRC32 unkeyed checksum
+        pw = b'password'
+        salt = b'salt'
+        key = string_to_key(etype, pw, salt)
+        plain = b'africa america asia australia europe'
+        cksum = h('ce595a53')
+        verify_checksum(Cksumtype.CRC32, key, usage, plain, cksum)
+
+    def test_crc32_unkeyed_checksum_des3_usage_40(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.DES3, 40)
+
+    def test_crc32_unkeyed_checksum_des3_usage_50(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.DES3, 50)
+
+    def test_crc32_unkeyed_checksum_rc4_usage_40(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.RC4, 40)
+
+    def test_crc32_unkeyed_checksum_rc4_usage_50(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.RC4, 50)
+
+    def test_crc32_unkeyed_checksum_aes128_usage_40(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.AES128, 40)
+
+    def test_crc32_unkeyed_checksum_aes128_usage_50(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.AES128, 50)
+
+    def test_crc32_unkeyed_checksum_aes256_usage_40(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.AES256, 40)
+
+    def test_crc32_unkeyed_checksum_aes256_usage_50(self):
+        return self._test_crc32_unkeyed_checksum(Enctype.AES256, 50)
+
+
 if __name__ == "__main__":
     import unittest
     unittest.main()
diff --git a/python/samba/tests/krb5/raw_testcase.py b/python/samba/tests/krb5/raw_testcase.py
index 6c7bcd418a0..f43ce9cbc3c 100644
--- a/python/samba/tests/krb5/raw_testcase.py
+++ b/python/samba/tests/krb5/raw_testcase.py
@@ -867,3 +867,26 @@ class RawKerberosTest(TestCase):
         if native_decoded_only:
             return decoded
         return decoded, obj
+
+    def PA_S4U2Self_create(self, name, realm, tgt_session_key, ctype=None):
+        # PA-S4U2Self     ::= SEQUENCE {
+        #        name            [0] PrincipalName,
+        #        realm           [1] Realm,
+        #        cksum           [2] Checksum,
+        #        auth            [3] GeneralString
+        # }
+        cksum_data = name['name-type'].to_bytes(4, byteorder='little')
+        for n in name['name-string']:
+            cksum_data += n.encode()
+        cksum_data += realm.encode()
+        cksum_data += "Kerberos".encode()
+        cksum = self.Checksum_create(tgt_session_key, 17, cksum_data, ctype)
+
+        PA_S4U2Self_obj = {
+            'name': name,
+            'realm': realm,
+            'cksum': cksum,
+            'auth': "Kerberos",
+        }
+        pa_s4u2self = self.der_encode(PA_S4U2Self_obj, asn1Spec=krb5_asn1.PA_S4U2Self())
+        return self.PA_DATA_create(129, pa_s4u2self)
diff --git a/python/samba/tests/krb5/rfc4120.asn1 b/python/samba/tests/krb5/rfc4120.asn1
index 05b43106034..98ba887729d 100644
--- a/python/samba/tests/krb5/rfc4120.asn1
+++ b/python/samba/tests/krb5/rfc4120.asn1
@@ -415,6 +415,14 @@ AD-AND-OR               ::= SEQUENCE {
 
 AD-MANDATORY-FOR-KDC    ::= AuthorizationData
 
+-- S4U
+
+PA-S4U2Self ::= SEQUENCE {
+        name            [0] PrincipalName,
+        realm           [1] Realm,
+        cksum           [2] Checksum,
+        auth            [3] KerberosString
+}
 
 
 
diff --git a/python/samba/tests/krb5/rfc4120_pyasn1.py b/python/samba/tests/krb5/rfc4120_pyasn1.py
index b2627aa3dcb..05304a8a099 100644
--- a/python/samba/tests/krb5/rfc4120_pyasn1.py
+++ b/python/samba/tests/krb5/rfc4120_pyasn1.py
@@ -1,5 +1,5 @@
 # Auto-generated by asn1ate v.0.6.1.dev0 from rfc4120.asn1
-# (last modified on 2020-03-26 10:28:24.346775)
+# (last modified on 2020-05-06 17:51:00.323318)
 
 # KerberosV5Spec2
 from pyasn1.type import univ, char, namedtype, namedval, tag, constraint, useful
@@ -780,6 +780,18 @@ PA_ENC_TS_ENC.componentType = namedtype.NamedTypes(
 )
 
 
+class PA_S4U2Self(univ.Sequence):
+    pass
+
+
+PA_S4U2Self.componentType = namedtype.NamedTypes(
+    namedtype.NamedType('name', PrincipalName().subtype(explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 0))),
+    namedtype.NamedType('realm', Realm().subtype(explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 1))),
+    namedtype.NamedType('cksum', Checksum().subtype(explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 2))),
+    namedtype.NamedType('auth', KerberosString().subtype(explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatSimple, 3)))
+)
+
+
 class PADataTypeValues(univ.Integer):
     pass
 
diff --git a/python/samba/tests/krb5/s4u_tests.py b/python/samba/tests/krb5/s4u_tests.py
new file mode 100755
index 00000000000..ae38635c53b
--- /dev/null
+++ b/python/samba/tests/krb5/s4u_tests.py
@@ -0,0 +1,197 @@
+#!/usr/bin/env python3
+# Unix SMB/CIFS implementation.
+# Copyright (C) Stefan Metzmacher 2020
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import sys
+import os
+
+sys.path.insert(0, "bin/python")
+os.environ["PYTHONUNBUFFERED"] = "1"
+
+from samba.tests import env_get_var_value
+from samba.tests.krb5.kcrypto import Cksumtype
+from samba.tests.krb5.raw_testcase import RawKerberosTest
+import samba.tests.krb5.rfc4120_pyasn1 as krb5_asn1
+
+global_asn1_print = False
+global_hexdump = False
+
+class S4UKerberosTests(RawKerberosTest):
+
+    def setUp(self):
+        super(S4UKerberosTests, self).setUp()
+        self.do_asn1_print = global_asn1_print
+        self.do_hexdump = global_hexdump
+
+    def _test_s4u2self(self, pa_s4u2self_ctype=None):
+        service_creds = self.get_service_creds()
+        service = service_creds.get_username()
+        realm = service_creds.get_realm()
+
+        cname = self.PrincipalName_create(name_type=1, names=[service])
+        sname = self.PrincipalName_create(name_type=2, names=["krbtgt", realm])
+
+        till = self.get_KerberosTime(offset=36000)
+
+        kdc_options = krb5_asn1.KDCOptions('forwardable')
+        padata = None
+
+        etypes=(18,17,23)
+
+        req = self.AS_REQ_create(padata=padata,
+                                 kdc_options=str(kdc_options),
+                                 cname=cname,
+                                 realm=realm,
+                                 sname=sname,
+                                 from_time=None,
+                                 till_time=till,
+                                 renew_time=None,
+                                 nonce=0x7fffffff,
+                                 etypes=etypes,
+                                 addresses=None,
+                                 EncAuthorizationData=None,
+                                 EncAuthorizationData_key=None,
+                                 additional_tickets=None)
+        rep = self.send_recv_transaction(req)
+        self.assertIsNotNone(rep)
+
+        self.assertEqual(rep['msg-type'], 30)
+        self.assertEqual(rep['error-code'], 25)
+        rep_padata = self.der_decode(rep['e-data'], asn1Spec=krb5_asn1.METHOD_DATA())
+
+        for pa in rep_padata:
+            if pa['padata-type'] == 19:
+                etype_info2 = pa['padata-value']
+                break
+
+        etype_info2 = self.der_decode(etype_info2, asn1Spec=krb5_asn1.ETYPE_INFO2())
+
+        key = self.PasswordKey_from_etype_info2(service_creds, etype_info2[0])
+
+        (patime, pausec) = self.get_KerberosTimeWithUsec()
+        pa_ts = self.PA_ENC_TS_ENC_create(patime, pausec)
+        pa_ts = self.der_encode(pa_ts, asn1Spec=krb5_asn1.PA_ENC_TS_ENC())
+
+        enc_pa_ts_usage = 1
+        pa_ts = self.EncryptedData_create(key, enc_pa_ts_usage, pa_ts)
+        pa_ts = self.der_encode(pa_ts, asn1Spec=krb5_asn1.EncryptedData())
+
+        pa_ts = self.PA_DATA_create(2, pa_ts)
+
+        kdc_options = krb5_asn1.KDCOptions('forwardable')
+        padata = [pa_ts]
+
+        req = self.AS_REQ_create(padata=padata,
+                                 kdc_options=str(kdc_options),
+                                 cname=cname,
+                                 realm=realm,
+                                 sname=sname,
+                                 from_time=None,
+                                 till_time=till,
+                                 renew_time=None,
+                                 nonce=0x7fffffff,
+                                 etypes=etypes,
+                                 addresses=None,
+                                 EncAuthorizationData=None,
+                                 EncAuthorizationData_key=None,
+                                 additional_tickets=None)
+        rep = self.send_recv_transaction(req)
+        self.assertIsNotNone(rep)
+
+        msg_type = rep['msg-type']
+        self.assertEqual(msg_type, 11)
+
+        usage = 3
+        enc_part2 = key.decrypt(usage, rep['enc-part']['cipher'])
+        enc_part2 = self.der_decode(enc_part2, asn1Spec=krb5_asn1.EncASRepPart())
+
+        # S4U2Self Request
+        sname = cname
+
+        for_user_name = env_get_var_value('FOR_USER')
+        uname = self.PrincipalName_create(name_type=1, names=[for_user_name])
+
+        kdc_options = krb5_asn1.KDCOptions('forwardable')
+        till = self.get_KerberosTime(offset=36000)
+        ticket = rep['ticket']
+        ticket_session_key = self.EncryptionKey_import(enc_part2['key'])
+        pa_s4u = self.PA_S4U2Self_create(name=uname, realm=realm,
+                                         tgt_session_key=ticket_session_key,
+                                         ctype=pa_s4u2self_ctype)
+        padata = [pa_s4u]
+
+        subkey = self.RandomKey(ticket_session_key.etype)
+        subkey_usage = 9
+
+        (ctime, cusec) = self.get_KerberosTimeWithUsec()
+
+        req = self.TGS_REQ_create(padata=padata,
+                                  cusec=cusec,
+                                  ctime=ctime,
+                                  ticket=ticket,
+                                  kdc_options=str(kdc_options),
+                                  cname=cname,
+                                  realm=realm,
+                                  sname=sname,
+                                  from_time=None,
+                                  till_time=till,
+                                  renew_time=None,
+                                  nonce=0x7ffffffe,
+                                  etypes=etypes,
+                                  addresses=None,
+                                  EncAuthorizationData=None,
+                                  EncAuthorizationData_key=None,
+                                  additional_tickets=None,
+                                  ticket_session_key=ticket_session_key,
+                                  authenticator_subkey=subkey)
+        rep = self.send_recv_transaction(req)
+        self.assertIsNotNone(rep)
+
+        msg_type = rep['msg-type']
+        if msg_type == 13:
+            enc_part2 = subkey.decrypt(subkey_usage, rep['enc-part']['cipher'])
+            enc_part2 = self.der_decode(enc_part2, asn1Spec=krb5_asn1.EncTGSRepPart())
+
+        return msg_type
+
+    # Using the checksum type from the tgt_session_key happens to work everywhere
+    def test_s4u2self(self):
+        msg_type = self._test_s4u2self()
+        self.assertEqual(msg_type, 13)
+
+    # Per spec, the checksum of PA-FOR-USER is HMAC_MD5, see [MS-SFU] 2.2.1
+    def test_s4u2self_hmac_md5_checksum(self):
+        msg_type = self._test_s4u2self(pa_s4u2self_ctype=Cksumtype.HMAC_MD5)
+        self.assertEqual(msg_type, 13)
+
+    def test_s4u2self_md5_unkeyed_checksum(self):
+        msg_type = self._test_s4u2self(pa_s4u2self_ctype=Cksumtype.MD5)
+        self.assertEqual(msg_type, 30)
+
+    def test_s4u2self_sha1_unkeyed_checksum(self):
+        msg_type = self._test_s4u2self(pa_s4u2self_ctype=Cksumtype.SHA1)
+        self.assertEqual(msg_type, 30)
+
+    def test_s4u2self_crc32_unkeyed_checksum(self):
+        msg_type = self._test_s4u2self(pa_s4u2self_ctype=Cksumtype.CRC32)
+        self.assertEqual(msg_type, 30)
+
+if __name__ == "__main__":
+    global_asn1_print = True
+    global_hexdump = True
+    import unittest
+    unittest.main()
diff --git a/python/samba/tests/usage.py b/python/samba/tests/usage.py
index 18e9fad232f..58053474e03 100644
--- a/python/samba/tests/usage.py
+++ b/python/samba/tests/usage.py
@@ -87,6 +87,7 @@ EXCLUDE_USAGE = {
     'python/samba/tests/dcerpc/raw_protocol.py',
     'python/samba/tests/krb5/kcrypto.py',
     'python/samba/tests/krb5/simple_tests.py',
+    'python/samba/tests/krb5/s4u_tests.py',
 }
 
 EXCLUDE_HELP = {