python: Add SMB credentials cache test

Test that we can use a credentials cache with a user's service ticket
obtained with our Python code to connect to a service through SMB.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

python/samba/tests/krb5/test_smb.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+# Unix SMB/CIFS implementation.
+# Copyright (C) Stefan Metzmacher 2020
+# Copyright (C) 2021 Catalyst.Net Ltd
+#
+# 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
+
+from ldb import SCOPE_SUBTREE
+from samba.dcerpc import security
+from samba.ndr import ndr_unpack
+from samba.samba3 import libsmb_samba_internal as libsmb
+from samba.samba3 import param as s3param
+
+from samba.tests.krb5.kdc_base_test import KDCBaseTest
+
+sys.path.insert(0, "bin/python")
+os.environ["PYTHONUNBUFFERED"] = "1"
+
+global_asn1_print = False
+global_hexdump = False
+
+
+class SmbTests(KDCBaseTest):
+    """Test for SMB authentication using Kerberos credentials stored in a
+       credentials cache file.
+    """
+
+    def test_smb(self):
+        # Create a user account and a machine account, along with a Kerberos
+        # credentials cache file where the service ticket authenticating the
+        # user are stored.
+
+        user_name = "smbusr"
+        mach_name = self.dns_host_name
+        service = "cifs"
+        share = "tmp"
+
+        # Create the user account.
+        (user_credentials, _) = self.create_account(user_name)
+
+        # Talk to the KDC to obtain the service ticket, which gets placed into
+        # the cache. The machine account name has to match the name in the
+        # ticket, to ensure that the krbtgt ticket doesn't also need to be
+        # stored.
+        (creds, cachefile) = self.create_ccache_with_user(user_credentials,
+                                                          mach_name,
+                                                          service)
+
+        # Set the Kerberos 5 credentials cache environment variable. This is
+        # required because the codepath that gets run (gse_krb5) looks for it
+        # in here and not in the credentials object.
+        krb5_ccname = os.environ.get("KRB5CCNAME", "")
+        self.addCleanup(os.environ.__setitem__, "KRB5CCNAME", krb5_ccname)
+        os.environ["KRB5CCNAME"] = "FILE:" + cachefile.name
+
+        # Authenticate in-process to the machine account using the user's
+        # cached credentials.
+
+        # Retrieve the user account's SID.
+        ldb_res = self.ldb.search(scope=SCOPE_SUBTREE,
+                                  expression="(sAMAccountName=%s)" % user_name,
+                                  attrs=["objectSid"])
+        self.assertEqual(1, len(ldb_res))
+        sid = ndr_unpack(security.dom_sid, ldb_res[0]["objectSid"][0])
+
+        # Connect to a share and retrieve the user SID.
+        s3_lp = s3param.get_context()
+        s3_lp.load(self.lp.configfile)
+
+        min_protocol = s3_lp.get("client min protocol")
+        self.addCleanup(s3_lp.set, "client min protocol", min_protocol)
+        s3_lp.set("client min protocol", "NT1")
+
+        max_protocol = s3_lp.get("client max protocol")
+        self.addCleanup(s3_lp.set, "client max protocol", max_protocol)
+        s3_lp.set("client max protocol", "NT1")
+
+        conn = libsmb.Conn(mach_name, share, lp=s3_lp, creds=creds)
+
+        (uid, gid, gids, sids, guest) = conn.posix_whoami()
+
+        # Ensure that they match.
+        self.assertEqual(sid, sids[0])
+
+        # Remove the cached credentials file.
+        os.remove(cachefile.name)
+
+
+if __name__ == "__main__":
+    global_asn1_print = True
+    global_hexdump = True
+    import unittest
+    unittest.main()

python/samba/tests/usage.py

@@ -99,6 +99,7 @@ EXCLUDE_USAGE = {
     'python/samba/tests/krb5/test_ccache.py',
     'python/samba/tests/krb5/test_ldap.py',
     'python/samba/tests/krb5/test_rpc.py',
+    'python/samba/tests/krb5/test_smb.py',
     'python/samba/tests/krb5/ms_kile_client_principal_lookup_tests.py',
 }
 

source4/selftest/tests.py

@@ -838,6 +838,7 @@ planoldpythontestsuite("fl2008r2dc:local", "samba.tests.krb5.xrealm_tests")
 planoldpythontestsuite("ad_dc_default", "samba.tests.krb5.test_ccache")
 planoldpythontestsuite("ad_dc_default", "samba.tests.krb5.test_ldap")
 planoldpythontestsuite("ad_dc_default", "samba.tests.krb5.test_rpc")
+planoldpythontestsuite("ad_dc_smb1", "samba.tests.krb5.test_smb")
 
 for env in ["ad_dc", smbv1_disabled_testenv]:
     planoldpythontestsuite(env, "samba.tests.smb", extra_args=['-U"$USERNAME%$PASSWORD"'])