selftest/drs: Demonstrate ERROR(ldb): uncaught exception - Deleted target CN=NTDS Settings... in join

"samba-tool domain join" uses the replication API in a strange way, perhaps no longer
required, except that we often still have folks upgrading from very old Samba versions.

By deferring the writing out to the DB of link replication to the very end, we have a
better chance that all the objects required are present, however the situation may
have changed during the cycle, and a link could still be sent, pointing to a deleted
object.

We currently fail in this situation.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15329

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
(cherry picked from commit 2d41bcce83a976b85636c92d6fc38c63fdde5431)

4 files changed, 140 insertions, 0 deletions

diff --git a/selftest/knownfail.d/replicate_against_deleted b/selftest/knownfail.d/replicate_against_deleted
new file mode 100644
index 00000000000..9caa5346a45
--- /dev/null
+++ b/selftest/knownfail.d/replicate_against_deleted
@@ -0,0 +1 @@
+samba4.drs.ridalloc_exop.python\(.*\).ridalloc_exop.DrsReplicaSyncTestCase.test_replicate_against_deleted_objects_transaction
diff --git a/source4/dsdb/pydsdb.c b/source4/dsdb/pydsdb.c
index 804007e9e86..fd7cda21a43 100644
--- a/source4/dsdb/pydsdb.c
+++ b/source4/dsdb/pydsdb.c
@@ -1768,5 +1768,7 @@ MODULE_INIT_FUNC(dsdb)
 	ADD_DSDB_STRING(DS_GUID_SCHEMA_CLASS_MANAGED_SERVICE_ACCOUNT);
 	ADD_DSDB_STRING(DS_GUID_SCHEMA_CLASS_USER);
 
+	ADD_DSDB_STRING(DSDB_FULL_JOIN_REPLICATION_COMPLETED_OPAQUE_NAME);
+
 	return m;
 }
diff --git a/source4/dsdb/samdb/samdb.h b/source4/dsdb/samdb/samdb.h
index 46e80810384..d054244b20d 100644
--- a/source4/dsdb/samdb/samdb.h
+++ b/source4/dsdb/samdb/samdb.h
@@ -372,6 +372,8 @@ struct dsdb_extended_dn_store_format {
 
 #define DSDB_OPAQUE_PARTITION_MODULE_MSG_OPAQUE_NAME "DSDB_OPAQUE_PARTITION_MODULE_MSG"
 
+#define DSDB_FULL_JOIN_REPLICATION_COMPLETED_OPAQUE_NAME "DSDB_FULL_JOIN_REPLICATION_COMPLETED"
+
 #define DSDB_ACL_CHECKS_DIRSYNC_FLAG 0x1
 #define DSDB_SAMDB_MINIMUM_ALLOWED_RID   1000
 
diff --git a/source4/torture/drs/python/ridalloc_exop.py b/source4/torture/drs/python/ridalloc_exop.py
index 7869967cf1d..8ce4098bc06 100644
--- a/source4/torture/drs/python/ridalloc_exop.py
+++ b/source4/torture/drs/python/ridalloc_exop.py
@@ -43,6 +43,7 @@ from samba.auth import system_session, admin_session
 from samba.dbchecker import dbcheck
 from samba.ndr import ndr_pack
 from samba.dcerpc import security
+from samba import drs_utils, dsdb
 
 
 class DrsReplicaSyncTestCase(drs_base.DrsBaseTestCase):
@@ -673,3 +674,137 @@ class DrsReplicaSyncTestCase(drs_base.DrsBaseTestCase):
         finally:
             self._test_force_demote(fsmo_owner['dns_name'], "RIDALLOCTEST7")
             shutil.rmtree(targetdir, ignore_errors=True)
+
+    def test_replicate_against_deleted_objects_transaction(self):
+        """Not related to RID allocation, but uses the infrastructure here.
+        Do a join, create a link between two objects remotely, but
+        remove the target locally.  Show that we need to set a magic
+        opaque if there is an outer transaction.
+
+        """
+        fsmo_dn = ldb.Dn(self.ldb_dc1, "CN=RID Manager$,CN=System," + self.ldb_dc1.domain_dn())
+        (fsmo_owner, fsmo_not_owner) = self._determine_fSMORoleOwner(fsmo_dn)
+
+        test_user4 = "ridalloctestuser4"
+        test_group = "ridalloctestgroup1"
+
+        self.ldb_dc1.newuser(test_user4, "P@ssword!")
+
+        self.addCleanup(self.ldb_dc1.deleteuser, test_user4)
+
+        self.ldb_dc1.newgroup(test_group)
+        self.addCleanup(self.ldb_dc1.deletegroup, test_group)
+
+        targetdir = self._test_join(self.dnsname_dc1, "RIDALLOCTEST8")
+        try:
+            # Connect to the database
+            ldb_url = "tdb://%s" % os.path.join(targetdir, "private/sam.ldb")
+            lp = self.get_loadparm()
+
+            new_ldb = SamDB(ldb_url,
+                            session_info=system_session(lp), lp=lp)
+
+            destination_dsa_guid = misc.GUID(new_ldb.get_ntds_GUID())
+
+            repl = drs_utils.drs_Replicate(f'ncacn_ip_tcp:{self.dnsname_dc1}[seal]',
+                                           lp,
+                                           self.get_credentials(),
+                                           new_ldb,
+                                           destination_dsa_guid)
+
+            source_dsa_invocation_id = misc.GUID(self.ldb_dc1.invocation_id)
+
+            # Add the link on the remote DC
+            self.ldb_dc1.add_remove_group_members(test_group, [test_user4])
+
+            # Starting a transaction overrides, currently the logic
+            # inside repl.replicatate to retry with GET_TGT which in
+            # turn tells the repl_meta_data module that the most up to
+            # date info is already available
+            new_ldb.transaction_start()
+            repl.replicate(self.ldb_dc1.domain_dn(),
+                           source_dsa_invocation_id,
+                           destination_dsa_guid)
+
+            # Delete the user locally, before applying the links.
+            # This simulates getting the delete in the replciation
+            # stream.
+            new_ldb.deleteuser(test_user4)
+
+            # This fails as the user has been deleted locally but a remote link is sent
+            self.assertRaises(ldb.LdbError, new_ldb.transaction_commit)
+
+            new_ldb.transaction_start()
+            repl.replicate(self.ldb_dc1.domain_dn(),
+                           source_dsa_invocation_id,
+                           destination_dsa_guid)
+
+            # Delete the user locally (the previous transaction
+            # doesn't apply), before applying the links.  This
+            # simulates getting the delete in the replciation stream.
+            new_ldb.deleteuser(test_user4)
+
+            new_ldb.set_opaque_integer(dsdb.DSDB_FULL_JOIN_REPLICATION_COMPLETED_OPAQUE_NAME,
+                                       1)
+
+            # This should now work
+            try:
+                new_ldb.transaction_commit()
+            except ldb.LdbError as e:
+                self.fail(f"Failed to replicate despite setting opaque with {e.args[1]}")
+
+        finally:
+            self._test_force_demote(self.dnsname_dc1, "RIDALLOCTEST8")
+            shutil.rmtree(targetdir, ignore_errors=True)
+
+    def test_replicate_against_deleted_objects_normal(self):
+        """Not related to RID allocation, but uses the infrastructure here.
+        Do a join, create a link between two objects remotely, but
+        remove the target locally.  .
+
+        """
+        fsmo_dn = ldb.Dn(self.ldb_dc1, "CN=RID Manager$,CN=System," + self.ldb_dc1.domain_dn())
+        (fsmo_owner, fsmo_not_owner) = self._determine_fSMORoleOwner(fsmo_dn)
+
+        test_user5 = "ridalloctestuser5"
+        test_group2 = "ridalloctestgroup2"
+
+        self.ldb_dc1.newuser(test_user5, "P@ssword!")
+        self.addCleanup(self.ldb_dc1.deleteuser, test_user5)
+
+        self.ldb_dc1.newgroup(test_group2)
+        self.addCleanup(self.ldb_dc1.deletegroup, test_group2)
+
+        targetdir = self._test_join(self.dnsname_dc1, "RIDALLOCTEST9")
+        try:
+            # Connect to the database
+            ldb_url = "tdb://%s" % os.path.join(targetdir, "private/sam.ldb")
+            lp = self.get_loadparm()
+
+            new_ldb = SamDB(ldb_url,
+                            session_info=system_session(lp), lp=lp)
+
+            destination_dsa_guid = misc.GUID(new_ldb.get_ntds_GUID())
+
+            repl = drs_utils.drs_Replicate(f'ncacn_ip_tcp:{self.dnsname_dc1}[seal]',
+                                           lp,
+                                           self.get_credentials(),
+                                           new_ldb,
+                                           destination_dsa_guid)
+
+            source_dsa_invocation_id = misc.GUID(self.ldb_dc1.invocation_id)
+
+            # Add the link on the remote DC
+            self.ldb_dc1.add_remove_group_members(test_group2, [test_user5])
+
+            # Delete the user locally
+            new_ldb.deleteuser(test_user5)
+
+            # Confirm replication copes with a link to a locally deleted user
+            repl.replicate(self.ldb_dc1.domain_dn(),
+                           source_dsa_invocation_id,
+                           destination_dsa_guid)
+
+        finally:
+            self._test_force_demote(self.dnsname_dc1, "RIDALLOCTEST9")
+            shutil.rmtree(targetdir, ignore_errors=True)