CVE-2023-0225 pytest/acl: test deleting dNSHostName as unprivileged user

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15276

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

[abartlet@samba.org The self.set_heuristic(samba.dsdb.DS_HR_ATTR_AUTHZ_ON_LDAP_ADD, b'11')
 in the test setUp() is unused in this test but is included as a
 clean backport, so the fact that the server does not implement this
 is unimportant]

3 files changed, 239 insertions, 0 deletions

diff --git a/selftest/knownfail.d/dns-host-name-deletion b/selftest/knownfail.d/dns-host-name-deletion
new file mode 100644
index 00000000000..ac11619ffc3
--- /dev/null
+++ b/selftest/knownfail.d/dns-host-name-deletion
@@ -0,0 +1,2 @@
+^samba4.ldap.acl_modify.python\(.*\).__main__.AclModifyTests.test_modify_delete_dns_host_name_ldif_unspecified\(.*\)
+^samba4.ldap.acl_modify.python\(.*\).__main__.AclModifyTests.test_modify_delete_dns_host_name_unspecified\(.*\)
diff --git a/source4/dsdb/tests/python/acl_modify.py b/source4/dsdb/tests/python/acl_modify.py
new file mode 100755
index 00000000000..c85748a764f
--- /dev/null
+++ b/source4/dsdb/tests/python/acl_modify.py
@@ -0,0 +1,236 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+
+import optparse
+import sys
+sys.path.insert(0, "bin/python")
+import samba
+
+from samba.tests.subunitrun import SubunitOptions, TestProgram
+
+import samba.getopt as options
+
+from ldb import ERR_INSUFFICIENT_ACCESS_RIGHTS
+from ldb import Message, MessageElement, Dn
+from ldb import FLAG_MOD_REPLACE, FLAG_MOD_DELETE
+from samba.dcerpc import security
+
+from samba.auth import system_session
+from samba import gensec, sd_utils
+from samba.samdb import SamDB
+from samba.credentials import Credentials, DONT_USE_KERBEROS
+import samba.tests
+import samba.dsdb
+
+
+parser = optparse.OptionParser("acl.py [options] <host>")
+sambaopts = options.SambaOptions(parser)
+parser.add_option_group(sambaopts)
+parser.add_option_group(options.VersionOptions(parser))
+
+# use command line creds if available
+credopts = options.CredentialsOptions(parser)
+parser.add_option_group(credopts)
+subunitopts = SubunitOptions(parser)
+parser.add_option_group(subunitopts)
+
+opts, args = parser.parse_args()
+
+if len(args) < 1:
+    parser.print_usage()
+    sys.exit(1)
+
+host = args[0]
+if "://" not in host:
+    ldaphost = "ldap://%s" % host
+else:
+    ldaphost = host
+    start = host.rindex("://")
+    host = host.lstrip(start + 3)
+
+lp = sambaopts.get_loadparm()
+creds = credopts.get_credentials(lp)
+creds.set_gensec_features(creds.get_gensec_features() | gensec.FEATURE_SEAL)
+
+#
+# Tests start here
+#
+
+
+class AclTests(samba.tests.TestCase):
+
+    def setUp(self):
+        super(AclTests, self).setUp()
+
+        strict_checking = samba.tests.env_get_var_value('STRICT_CHECKING', allow_missing=True)
+        if strict_checking is None:
+            strict_checking = '1'
+        self.strict_checking = bool(int(strict_checking))
+
+        self.ldb_admin = SamDB(ldaphost, credentials=creds, session_info=system_session(lp), lp=lp)
+        self.base_dn = self.ldb_admin.domain_dn()
+        self.domain_sid = security.dom_sid(self.ldb_admin.get_domain_sid())
+        self.user_pass = "samba123@"
+        self.configuration_dn = self.ldb_admin.get_config_basedn().get_linearized()
+        self.sd_utils = sd_utils.SDUtils(self.ldb_admin)
+        self.addCleanup(self.delete_admin_connection)
+        # used for anonymous login
+        self.creds_tmp = Credentials()
+        self.creds_tmp.set_username("")
+        self.creds_tmp.set_password("")
+        self.creds_tmp.set_domain(creds.get_domain())
+        self.creds_tmp.set_realm(creds.get_realm())
+        self.creds_tmp.set_workstation(creds.get_workstation())
+        print("baseDN: %s" % self.base_dn)
+
+        # set AttributeAuthorizationOnLDAPAdd and BlockOwnerImplicitRights
+        self.set_heuristic(samba.dsdb.DS_HR_ATTR_AUTHZ_ON_LDAP_ADD, b'11')
+
+    def set_heuristic(self, index, values):
+        self.assertGreater(index, 0)
+        self.assertLess(index, 30)
+        self.assertIsInstance(values, bytes)
+
+        # Get the old "dSHeuristics" if it was set
+        dsheuristics = self.ldb_admin.get_dsheuristics()
+        # Reset the "dSHeuristics" as they were before
+        self.addCleanup(self.ldb_admin.set_dsheuristics, dsheuristics)
+        # Set the "dSHeuristics" to activate the correct behaviour
+        default_heuristics = b"000000000100000000020000000003"
+        if dsheuristics is None:
+            dsheuristics = b""
+        dsheuristics += default_heuristics[len(dsheuristics):]
+        dsheuristics = (dsheuristics[:index - 1] +
+                        values +
+                        dsheuristics[index - 1 + len(values):])
+        self.ldb_admin.set_dsheuristics(dsheuristics)
+
+    def get_user_dn(self, name):
+        return "CN=%s,CN=Users,%s" % (name, self.base_dn)
+
+    def get_ldb_connection(self, target_username, target_password):
+        creds_tmp = Credentials()
+        creds_tmp.set_username(target_username)
+        creds_tmp.set_password(target_password)
+        creds_tmp.set_domain(creds.get_domain())
+        creds_tmp.set_realm(creds.get_realm())
+        creds_tmp.set_workstation(creds.get_workstation())
+        creds_tmp.set_gensec_features(creds_tmp.get_gensec_features()
+                                      | gensec.FEATURE_SEAL)
+        creds_tmp.set_kerberos_state(DONT_USE_KERBEROS)  # kinit is too expensive to use in a tight loop
+        ldb_target = SamDB(url=ldaphost, credentials=creds_tmp, lp=lp)
+        return ldb_target
+
+    # Test if we have any additional groups for users than default ones
+    def assert_user_no_group_member(self, username):
+        res = self.ldb_admin.search(self.base_dn, expression="(distinguishedName=%s)" % self.get_user_dn(username))
+        try:
+            self.assertEqual(res[0]["memberOf"][0], "")
+        except KeyError:
+            pass
+        else:
+            self.fail()
+
+    def delete_admin_connection(self):
+        del self.sd_utils
+        del self.ldb_admin
+
+
+class AclModifyTests(AclTests):
+
+    def setup_computer_with_hostname(self, account_name):
+        ou_dn = f'OU={account_name},{self.base_dn}'
+        dn = f'CN={account_name},{ou_dn}'
+
+        user, password = "mouse", "mus musculus 123!"
+        self.addCleanup(self.ldb_admin.deleteuser, user)
+
+        self.ldb_admin.newuser(user, password)
+        self.ldb_user = self.get_ldb_connection(user, password)
+
+        self.addCleanup(self.ldb_admin.delete, ou_dn,
+                        controls=["tree_delete:0"])
+        self.ldb_admin.create_ou(ou_dn)
+
+        self.ldb_admin.add({
+            'dn': dn,
+            'objectClass': 'computer',
+            'sAMAccountName': account_name + '$',
+        })
+
+        host_name = f'{account_name}.{self.ldb_user.domain_dns_name()}'
+
+        m = Message(Dn(self.ldb_admin, dn))
+        m['dNSHostName'] = MessageElement(host_name,
+                                          FLAG_MOD_REPLACE,
+                                          'dNSHostName')
+
+        self.ldb_admin.modify(m)
+        return host_name, dn
+
+    def test_modify_delete_dns_host_name_specified(self):
+        '''Test deleting dNSHostName'''
+        account_name = self.id().rsplit(".", 1)[1][:63]
+        host_name, dn = self.setup_computer_with_hostname(account_name)
+
+        m = Message(Dn(self.ldb_user, dn))
+        m['dNSHostName'] = MessageElement(host_name,
+                                          FLAG_MOD_DELETE,
+                                          'dNSHostName')
+
+        self.assertRaisesLdbError(
+            ERR_INSUFFICIENT_ACCESS_RIGHTS,
+            "User able to delete dNSHostName (with specified name)",
+            self.ldb_user.modify, m)
+
+    def test_modify_delete_dns_host_name_unspecified(self):
+        '''Test deleting dNSHostName'''
+        account_name = self.id().rsplit(".", 1)[1][:63]
+        host_name, dn = self.setup_computer_with_hostname(account_name)
+
+        m = Message(Dn(self.ldb_user, dn))
+        m['dNSHostName'] = MessageElement([],
+                                          FLAG_MOD_DELETE,
+                                          'dNSHostName')
+
+        self.assertRaisesLdbError(
+            ERR_INSUFFICIENT_ACCESS_RIGHTS,
+            "User able to delete dNSHostName (without specified name)",
+            self.ldb_user.modify, m)
+
+    def test_modify_delete_dns_host_name_ldif_specified(self):
+        '''Test deleting dNSHostName'''
+        account_name = self.id().rsplit(".", 1)[1][:63]
+        host_name, dn = self.setup_computer_with_hostname(account_name)
+
+        ldif = f"""
+dn: {dn}
+changetype: modify
+delete: dNSHostName
+dNSHostName: {host_name}
+"""
+        self.assertRaisesLdbError(
+            ERR_INSUFFICIENT_ACCESS_RIGHTS,
+            "User able to delete dNSHostName (with specified name)",
+            self.ldb_user.modify_ldif, ldif)
+
+    def test_modify_delete_dns_host_name_ldif_unspecified(self):
+        '''Test deleting dNSHostName'''
+        account_name = self.id().rsplit(".", 1)[1][:63]
+        host_name, dn = self.setup_computer_with_hostname(account_name)
+
+        ldif = f"""
+dn: {dn}
+changetype: modify
+delete: dNSHostName
+"""
+        self.assertRaisesLdbError(
+            ERR_INSUFFICIENT_ACCESS_RIGHTS,
+            "User able to delete dNSHostName (without specific name)",
+            self.ldb_user.modify_ldif, ldif)
+
+
+ldb = SamDB(ldaphost, credentials=creds, session_info=system_session(lp), lp=lp)
+
+TestProgram(module=__name__, opts=subunitopts)
diff --git a/source4/selftest/tests.py b/source4/selftest/tests.py
index a09945f40da..29801bc190b 100755
--- a/source4/selftest/tests.py
+++ b/source4/selftest/tests.py
@@ -1418,6 +1418,7 @@ for env in all_fl_envs + ["schema_dc"]:
     plantestsuite("samba4.ldap.possibleInferiors.python(%s)" % env, env, [python, os.path.join(samba4srcdir, "dsdb/samdb/ldb_modules/tests/possibleinferiors.py"), "ldap://$SERVER", '-U"$USERNAME%$PASSWORD"', "-W$DOMAIN"])
     plantestsuite_loadlist("samba4.ldap.secdesc.python(%s)" % env, env, [python, os.path.join(DSDB_PYTEST_DIR, "sec_descriptor.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '$LOADLIST', '$LISTOPT'])
     plantestsuite_loadlist("samba4.ldap.acl.python(%s)" % env, env, ["STRICT_CHECKING=0", python, os.path.join(DSDB_PYTEST_DIR, "acl.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '$LOADLIST', '$LISTOPT'])
+    plantestsuite_loadlist("samba4.ldap.acl_modify.python(%s)" % env, env, ["STRICT_CHECKING=0", python, os.path.join(DSDB_PYTEST_DIR, "acl_modify.py"), '$SERVER', '-U"$USERNAME%$PASSWORD"', '--workgroup=$DOMAIN', '$LOADLIST', '$LISTOPT'])
 
 for env in all_fl_envs + ["schema_dc", "ad_dc_no_ntlm"]:
     if env != "fl2000dc":