Attachment 17720 Details for Bug 15276 – test and proposed fix for master

[patch] test and proposed fix for master

bug_15276.patch (text/plain), 13.11 KB, created by Jo Sutton on 2023-01-08 23:11:49 UTC

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Creator: Jo Sutton

Created: 2023-01-08 23:11:49 UTC

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patch

obsolete

>From abfd1fe97877c235e04d4f67a672ad843361e56f Mon Sep 17 00:00:00 2001
>From: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
>Date: Wed, 4 Jan 2023 21:37:49 +1300
>Subject: [PATCH 1/2] 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>
>---
> selftest/knownfail.d/dns-host-name-deletion |   2 +
> source4/dsdb/tests/python/acl_modify.py     | 236 ++++++++++++++++++++
> source4/selftest/tests.py                   |   1 +
> 3 files changed, 239 insertions(+)
> create mode 100644 selftest/knownfail.d/dns-host-name-deletion
> create mode 100755 source4/dsdb/tests/python/acl_modify.py
>
>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 774b874edbd..826c70738e6 100755
>--- a/source4/selftest/tests.py
>+++ b/source4/selftest/tests.py
>@@ -1417,6 +1417,7 @@ 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', '$LISTOPT'])
> 
> for env in all_fl_envs + ["schema_dc", "ad_dc_no_ntlm"]:
>     if env != "fl2000dc":
>-- 
>2.35.0
>
>
>From a14012aee7ad4479b64cab93552b8c5ae803b61d Mon Sep 17 00:00:00 2001
>From: Joseph Sutton <josephsutton@catalyst.net.nz>
>Date: Mon, 9 Jan 2023 11:22:34 +1300
>Subject: [PATCH 2/2] s4-acl: Don't return early if dNSHostName element has no
> values
>
>This early return would mistakenly allow an unprivileged user to delete
>the dNSHostName attribute by making an LDAP modify request with no
>values. We should no longer allow this.
>
>Add or replace operations with no values and no privileges are
>disallowed.
>
>BUG: https://bugzilla.samba.org/show_bug.cgi?id=15276
>
>Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
>---
> selftest/knownfail.d/dns-host-name-deletion |  2 --
> source4/dsdb/samdb/ldb_modules/acl.c        | 12 +++++++-----
> 2 files changed, 7 insertions(+), 7 deletions(-)
> delete mode 100644 selftest/knownfail.d/dns-host-name-deletion
>
>diff --git a/selftest/knownfail.d/dns-host-name-deletion b/selftest/knownfail.d/dns-host-name-deletion
>deleted file mode 100644
>index ac11619ffc3..00000000000
>--- a/selftest/knownfail.d/dns-host-name-deletion
>+++ /dev/null
>@@ -1,2 +0,0 @@
>-^samba4.ldap.acl_modify.python$.*$.__main__.AclModifyTests.test_modify_delete_dns_host_name_ldif_unspecified$.*$
>-^samba4.ldap.acl_modify.python$.*$.__main__.AclModifyTests.test_modify_delete_dns_host_name_unspecified$.*$
>diff --git a/source4/dsdb/samdb/ldb_modules/acl.c b/source4/dsdb/samdb/ldb_modules/acl.c
>index dd15dddfb50..14d8b3de347 100644
>--- a/source4/dsdb/samdb/ldb_modules/acl.c
>+++ b/source4/dsdb/samdb/ldb_modules/acl.c
>@@ -946,11 +946,6 @@ static int acl_check_dns_host_name(TALLOC_CTX *mem_ctx,
> 		NULL
> 	};
> 
>-	if (el->num_values == 0) {
>-		return LDB_SUCCESS;
>-	}
>-	dnsHostName = &el->values[0];
>-
> 	tmp_ctx = talloc_new(mem_ctx);
> 	if (tmp_ctx == NULL) {
> 		return ldb_oom(ldb);
>@@ -1101,6 +1096,13 @@ static int acl_check_dns_host_name(TALLOC_CTX *mem_ctx,
> 		--account_name_len;
> 	}
> 
>+	/* Check for add or replace requests with no value. */
>+	if (el->num_values == 0) {
>+		talloc_free(tmp_ctx);
>+		return ldb_operr(ldb);
>+	}
>+	dnsHostName = &el->values[0];
>+
> 	dnsHostName_str = (const char *)dnsHostName->data;
> 	dns_host_name_len = dnsHostName->length;
> 
>-- 
>2.35.0
>

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