netcmd: Avoid database corruption by opting not to create database files during an...

If backup dirs contain hardlinks, the backup process could previously
attempt to open an LMDB database already opened during the backup,
causing it to be recreated as a new TDB database. This commit ensures
that new database files are not created during this operation, and that
the main SamDB database is not modified.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14027

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
(cherry picked from commit 4cf773591d49166b8c7ef8d637d7edfe755d48aa)

diff --git a/python/samba/netcmd/domain_backup.py b/python/samba/netcmd/domain_backup.py
index c5749a5c8e28abdfeb97b86e478d182defd3862a..c5a7083f536512d78f03512171ccf80ac2411ec4 100644 (file)
--- a/python/samba/netcmd/domain_backup.py
+++ b/python/samba/netcmd/domain_backup.py
@@ -305,7 +305,8 @@ class cmd_domain_backup_online(samba.netcmd.Command):
             shutil.rmtree(paths.sysvol)
 
             # Edit the downloaded sam.ldb to mark it as a backup
-            samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp)
+            samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp,
+                          flags=ldb.FLG_DONT_CREATE_DB)
             time_str = get_timestamp()
             add_backup_marker(samdb, "backupDate", time_str)
             add_backup_marker(samdb, "sidForRestore", new_sid)
@@ -529,7 +530,8 @@ class cmd_domain_backup_restore(cmd_fsmo_seize):
         # open a DB connection to the restored DB
         private_dir = os.path.join(targetdir, 'private')
         samdb_path = os.path.join(private_dir, 'sam.ldb')
-        samdb = SamDB(url=samdb_path, session_info=system_session(), lp=lp)
+        samdb = SamDB(url=samdb_path, session_info=system_session(), lp=lp,
+                      flags=ldb.FLG_DONT_CREATE_DB)
         backup_type = self.get_backup_type(samdb)
 
         if site is None:
@@ -637,7 +639,8 @@ class cmd_domain_backup_restore(cmd_fsmo_seize):
                                    host_ip, host_ip6, site)
 
         secrets_path = os.path.join(private_dir, 'secrets.ldb')
-        secrets_ldb = Ldb(secrets_path, session_info=system_session(), lp=lp)
+        secrets_ldb = Ldb(secrets_path, session_info=system_session(), lp=lp,
+                          flags=ldb.FLG_DONT_CREATE_DB)
         secretsdb_self_join(secrets_ldb, domain=ctx.domain_name,
                             realm=ctx.realm, dnsdomain=ctx.dnsdomain,
                             netbiosname=ctx.myname, domainsid=ctx.domsid,
@@ -929,7 +932,8 @@ class cmd_domain_backup_rename(samba.netcmd.Command):
 
         # connect to the local DB (making sure we use the new/renamed config)
         lp.load(paths.smbconf)
-        samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp)
+        samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp,
+                      flags=ldb.FLG_DONT_CREATE_DB)
 
         # Edit the cloned sam.ldb to mark it as a backup
         time_str = get_timestamp()
@@ -1017,7 +1021,8 @@ class cmd_domain_backup_offline(samba.netcmd.Command):
     # on the secrets.ldb file before backing up that file and secrets.tdb
     def backup_secrets(self, private_dir, lp, logger):
         secrets_path = os.path.join(private_dir, 'secrets')
-        secrets_obj = Ldb(secrets_path + '.ldb', lp=lp)
+        secrets_obj = Ldb(secrets_path + '.ldb', lp=lp,
+                          flags=ldb.FLG_DONT_CREATE_DB)
         logger.info('Starting transaction on ' + secrets_path)
         secrets_obj.transaction_start()
         self.offline_tdb_copy(secrets_path + '.ldb')
@@ -1042,7 +1047,7 @@ class cmd_domain_backup_offline(samba.netcmd.Command):
         else:
             logger.info('Starting transaction on ' + sam_ldb_path)
             copy_function = self.offline_tdb_copy
-            sam_obj = Ldb(sam_ldb_path, lp=lp)
+            sam_obj = Ldb(sam_ldb_path, lp=lp, flags=ldb.FLG_DONT_CREATE_DB)
             sam_obj.transaction_start()
 
         logger.info('   backing up ' + sam_ldb_path)
@@ -1094,7 +1099,8 @@ class cmd_domain_backup_offline(samba.netcmd.Command):
 
         check_targetdir(logger, targetdir)
 
-        samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp)
+        samdb = SamDB(url=paths.samdb, session_info=system_session(), lp=lp,
+                      flags=ldb.FLG_RDONLY)
         sid = get_sid_for_restore(samdb, logger)
 
         # Iterating over the directories in this specific order ensures that
@@ -1149,7 +1155,8 @@ class cmd_domain_backup_offline(samba.netcmd.Command):
         #          Writing to a .bak file only works because the DN being
         #          written to happens to be top level.
         samdb = SamDB(url=paths.samdb + self.backup_ext,
-                      session_info=system_session(), lp=lp)
+                      session_info=system_session(), lp=lp,
+                      flags=ldb.FLG_DONT_CREATE_DB)
         time_str = get_timestamp()
         add_backup_marker(samdb, "backupDate", time_str)
         add_backup_marker(samdb, "sidForRestore", sid)
@@ -1161,7 +1168,7 @@ class cmd_domain_backup_offline(samba.netcmd.Command):
             if not os.path.exists(path + self.backup_ext):
                 if path.endswith('.ldb'):
                     logger.info('Starting transaction on solo db: ' + path)
-                    ldb_obj = Ldb(path, lp=lp)
+                    ldb_obj = Ldb(path, lp=lp, flags=ldb.FLG_DONT_CREATE_DB)
                     ldb_obj.transaction_start()
                     logger.info('   running tdbbackup on the same file')
                     self.offline_tdb_copy(path)