python/samba/remove_dc.py

   1 # Unix SMB/CIFS implementation.
   2 # Copyright Matthieu Patou <mat@matws.net> 2011
   3 # Copyright Andrew Bartlett <abartlet@samba.org> 2008-2015
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 3 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 #
  18
  19 import uuid
  20 import ldb
  21 from ldb import LdbError
  22 from samba import werror
  23 from samba.ndr import ndr_unpack
  24 from samba.dcerpc import misc, dnsp
  25 from samba.dcerpc.dnsp import DNS_TYPE_NS, DNS_TYPE_A, DNS_TYPE_AAAA, \
  26     DNS_TYPE_CNAME, DNS_TYPE_SRV, DNS_TYPE_PTR
  27
  28
  29 class DemoteException(Exception):
  30     """Base element for demote errors"""
  31
  32     def __init__(self, value):
  33         self.value = value
  34
  35     def __str__(self):
  36         return "DemoteException: " + self.value
  37
  38
  39 def remove_sysvol_references(samdb, logger, dc_name):
  40     # DNs under the Configuration DN:
  41     realm = samdb.domain_dns_name()
  42     for s in ("CN=Enterprise,CN=Microsoft System Volumes,CN=System",
  43               "CN=%s,CN=Microsoft System Volumes,CN=System" % realm):
  44         dn = ldb.Dn(samdb, s)
  45
  46         # This is verbose, but it is the safe, escape-proof way
  47         # to add a base and add an arbitrary RDN.
  48         if dn.add_base(samdb.get_config_basedn()) == False:
  49             raise DemoteException("Failed constructing DN %s by adding base %s"
  50                                   % (dn, samdb.get_config_basedn()))
  51         if dn.add_child("CN=X") == False:
  52             raise DemoteException("Failed constructing DN %s by adding child CN=X"
  53                                   % (dn))
  54         dn.set_component(0, "CN", dc_name)
  55         try:
  56             logger.info("Removing Sysvol reference: %s" % dn)
  57             samdb.delete(dn)
  58         except ldb.LdbError as e:
  59             (enum, estr) = e.args
  60             if enum == ldb.ERR_NO_SUCH_OBJECT:
  61                 pass
  62             else:
  63                 raise
  64
  65     # DNs under the Domain DN:
  66     for s in ("CN=Domain System Volumes (SYSVOL share),CN=File Replication Service,CN=System",
  67               "CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System"):
  68         # This is verbose, but it is the safe, escape-proof way
  69         # to add a base and add an arbitrary RDN.
  70         dn = ldb.Dn(samdb, s)
  71         if dn.add_base(samdb.get_default_basedn()) == False:
  72             raise DemoteException("Failed constructing DN %s by adding base" %
  73                                   (dn, samdb.get_default_basedn()))
  74         if dn.add_child("CN=X") == False:
  75             raise DemoteException("Failed constructing DN %s by adding child "
  76                                   "CN=X (soon to be CN=%s)" % (dn, dc_name))
  77         dn.set_component(0, "CN", dc_name)
  78
  79         try:
  80             logger.info("Removing Sysvol reference: %s" % dn)
  81             samdb.delete(dn)
  82         except ldb.LdbError as e1:
  83             (enum, estr) = e1.args
  84             if enum == ldb.ERR_NO_SUCH_OBJECT:
  85                 pass
  86             else:
  87                 raise
  88
  89
  90 def remove_dns_references(samdb, logger, dnsHostName, ignore_no_name=False):
  91
  92     # Check we are using in-database DNS
  93     zones = samdb.search(base="", scope=ldb.SCOPE_SUBTREE,
  94                          expression="(&(objectClass=dnsZone)(!(dc=RootDNSServers)))",
  95                          attrs=[],
  96                          controls=["search_options:0:2"])
  97     if len(zones) == 0:
  98         return
  99
 100     dnsHostNameUpper = dnsHostName.upper()
 101
 102     try:
 103         (dn, primary_recs) = samdb.dns_lookup(dnsHostName)
 104     except RuntimeError as e4:
 105         (enum, estr) = e4.args
 106         if (enum == werror.WERR_DNS_ERROR_NAME_DOES_NOT_EXIST or
 107             enum == werror.WERR_DNS_ERROR_RCODE_NAME_ERROR):
 108             if ignore_no_name:
 109                 remove_hanging_dns_references(samdb, logger,
 110                                               dnsHostNameUpper,
 111                                               zones)
 112             return
 113         raise DemoteException("lookup of %s failed: %s" % (dnsHostName, estr))
 114     samdb.dns_replace(dnsHostName, [])
 115
 116     res = samdb.search("",
 117                        scope=ldb.SCOPE_BASE, attrs=["namingContexts"])
 118     assert len(res) == 1
 119     ncs = res[0]["namingContexts"]
 120
 121     # Work out the set of names we will likely have an A record on by
 122     # default.  This is by default all the partitions of type
 123     # domainDNS.  By finding the canocial name of all the partitions,
 124     # we find the likely candidates.  We only remove the record if it
 125     # maches the IP that was used by the dnsHostName.  This avoids us
 126     # needing to look a the dns_update_list file from in the demote
 127     # script.
 128
 129     def dns_name_from_dn(dn):
 130         # The canonical string of DC=example,DC=com is
 131         # example.com/
 132         #
 133         # The canonical string of CN=Configuration,DC=example,DC=com
 134         # is example.com/Configuration
 135         return ldb.Dn(samdb, dn).canonical_str().split('/', 1)[0]
 136
 137     # By using a set here, duplicates via (eg) example.com/Configuration
 138     # do not matter, they become just example.com
 139     a_names_to_remove_from \
 140         = set(dns_name_from_dn(str(dn)) for dn in ncs)
 141
 142     def a_rec_to_remove(dnsRecord):
 143         if dnsRecord.wType == DNS_TYPE_A or dnsRecord.wType == DNS_TYPE_AAAA:
 144             for rec in primary_recs:
 145                 if rec.wType == dnsRecord.wType and rec.data == dnsRecord.data:
 146                     return True
 147         return False
 148
 149     for a_name in a_names_to_remove_from:
 150         try:
 151             logger.debug("checking for DNS records to remove on %s" % a_name)
 152             (a_rec_dn, a_recs) = samdb.dns_lookup(a_name)
 153         except RuntimeError as e2:
 154             (enum, estr) = e2.args
 155             if enum == werror.WERR_DNS_ERROR_NAME_DOES_NOT_EXIST:
 156                 return
 157             raise DemoteException("lookup of %s failed: %s" % (a_name, estr))
 158
 159         orig_num_recs = len(a_recs)
 160         a_recs = [r for r in a_recs if not a_rec_to_remove(r)]
 161
 162         if len(a_recs) != orig_num_recs:
 163             logger.info("updating %s keeping %d values, removing %s values" %
 164                         (a_name, len(a_recs), orig_num_recs - len(a_recs)))
 165             samdb.dns_replace(a_name, a_recs)
 166
 167     remove_hanging_dns_references(samdb, logger, dnsHostNameUpper, zones)
 168
 169
 170 def remove_hanging_dns_references(samdb, logger, dnsHostNameUpper, zones):
 171
 172     # Find all the CNAME, NS, PTR and SRV records that point at the
 173     # name we are removing
 174
 175     def to_remove(value):
 176         dnsRecord = ndr_unpack(dnsp.DnssrvRpcRecord, value)
 177         if dnsRecord.wType == DNS_TYPE_NS \
 178            or dnsRecord.wType == DNS_TYPE_CNAME \
 179            or dnsRecord.wType == DNS_TYPE_PTR:
 180             if dnsRecord.data.upper() == dnsHostNameUpper:
 181                 return True
 182         elif dnsRecord.wType == DNS_TYPE_SRV:
 183             if dnsRecord.data.nameTarget.upper() == dnsHostNameUpper:
 184                 return True
 185         return False
 186
 187     for zone in zones:
 188         logger.debug("checking %s" % zone.dn)
 189         records = samdb.search(base=zone.dn, scope=ldb.SCOPE_SUBTREE,
 190                                expression="(&(objectClass=dnsNode)"
 191                                "(!(dNSTombstoned=TRUE)))",
 192                                attrs=["dnsRecord"])
 193         for record in records:
 194             try:
 195                 orig_values = record["dnsRecord"]
 196             except KeyError:
 197                 continue
 198
 199             # Remove references to dnsHostName in A, AAAA, NS, CNAME and SRV
 200             values = [ndr_unpack(dnsp.DnssrvRpcRecord, v)
 201                        for v in orig_values if not to_remove(v)]
 202
 203             if len(values) != len(orig_values):
 204                 logger.info("updating %s keeping %d values, removing %s values"
 205                             % (record.dn, len(values),
 206                                len(orig_values) - len(values)))
 207
 208                 # This requires the values to be unpacked, so this
 209                 # has been done in the list comprehension above
 210                 samdb.dns_replace_by_dn(record.dn, values)
 211
 212
 213 def offline_remove_server(samdb, logger,
 214                           server_dn,
 215                           remove_computer_obj=False,
 216                           remove_server_obj=False,
 217                           remove_sysvol_obj=False,
 218                           remove_dns_names=False,
 219                           remove_dns_account=False):
 220     res = samdb.search("",
 221                        scope=ldb.SCOPE_BASE, attrs=["dsServiceName"])
 222     assert len(res) == 1
 223     my_serviceName = res[0]["dsServiceName"][0]
 224
 225     # Confirm this is really a server object
 226     msgs = samdb.search(base=server_dn,
 227                         attrs=["serverReference", "cn",
 228                                "dnsHostName"],
 229                         scope=ldb.SCOPE_BASE,
 230                         expression="(objectClass=server)")
 231     msg = msgs[0]
 232     dc_name = str(msgs[0]["cn"][0])
 233
 234     try:
 235         computer_dn = ldb.Dn(samdb, msgs[0]["serverReference"][0].decode('utf8'))
 236     except KeyError:
 237         computer_dn = None
 238
 239     try:
 240         dnsHostName = msgs[0]["dnsHostName"][0]
 241     except KeyError:
 242         dnsHostName = None
 243
 244     if remove_server_obj:
 245         # Remove the server DN (do a tree-delete as it could still have a
 246         # 'DNS Settings' child object if it's a Windows DC)
 247         samdb.delete(server_dn, ["tree_delete:0"])
 248
 249     if computer_dn is not None:
 250         computer_msgs = samdb.search(base=computer_dn,
 251                                      expression="objectclass=computer",
 252                                      attrs=["msDS-KrbTgtLink",
 253                                             "rIDSetReferences",
 254                                             "cn"],
 255                                      scope=ldb.SCOPE_BASE)
 256         if "rIDSetReferences" in computer_msgs[0]:
 257             rid_set_dn = str(computer_msgs[0]["rIDSetReferences"][0])
 258             logger.info("Removing RID Set: %s" % rid_set_dn)
 259             samdb.delete(rid_set_dn)
 260         if "msDS-KrbTgtLink" in computer_msgs[0]:
 261             krbtgt_link_dn = str(computer_msgs[0]["msDS-KrbTgtLink"][0])
 262             logger.info("Removing RODC KDC account: %s" % krbtgt_link_dn)
 263             samdb.delete(krbtgt_link_dn)
 264
 265         if remove_computer_obj:
 266             # Delete the computer tree
 267             logger.info("Removing computer account: %s (and any child objects)" % computer_dn)
 268             samdb.delete(computer_dn, ["tree_delete:0"])
 269
 270         if "dnsHostName" in msgs[0]:
 271             dnsHostName = msgs[0]["dnsHostName"][0]
 272
 273     if remove_dns_account:
 274         res = samdb.search(expression="(&(objectclass=user)(cn=dns-%s)(servicePrincipalName=DNS/%s))" %
 275                            (ldb.binary_encode(dc_name), dnsHostName),
 276                            attrs=[], scope=ldb.SCOPE_SUBTREE,
 277                            base=samdb.get_default_basedn())
 278         if len(res) == 1:
 279             logger.info("Removing Samba-specific DNS service account: %s" % res[0].dn)
 280             samdb.delete(res[0].dn)
 281
 282     if dnsHostName is not None and remove_dns_names:
 283         remove_dns_references(samdb, logger, dnsHostName)
 284
 285     if remove_sysvol_obj:
 286         remove_sysvol_references(samdb, logger, dc_name)
 287
 288
 289 def offline_remove_ntds_dc(samdb,
 290                            logger,
 291                            ntds_dn,
 292                            remove_computer_obj=False,
 293                            remove_server_obj=False,
 294                            remove_connection_obj=False,
 295                            seize_stale_fsmo=False,
 296                            remove_sysvol_obj=False,
 297                            remove_dns_names=False,
 298                            remove_dns_account=False):
 299     res = samdb.search("",
 300                        scope=ldb.SCOPE_BASE, attrs=["dsServiceName"])
 301     assert len(res) == 1
 302     my_serviceName = ldb.Dn(samdb, res[0]["dsServiceName"][0].decode('utf8'))
 303     server_dn = ntds_dn.parent()
 304
 305     if my_serviceName == ntds_dn:
 306         raise DemoteException("Refusing to demote our own DSA: %s " % my_serviceName)
 307
 308     try:
 309         msgs = samdb.search(base=ntds_dn, expression="objectClass=ntdsDSA",
 310                             attrs=["objectGUID"], scope=ldb.SCOPE_BASE)
 311     except LdbError as e5:
 312         (enum, estr) = e5.args
 313         if enum == ldb.ERR_NO_SUCH_OBJECT:
 314             raise DemoteException("Given DN %s doesn't exist" % ntds_dn)
 315         else:
 316             raise
 317     if (len(msgs) == 0):
 318         raise DemoteException("%s is not an ntdsda in %s"
 319                               % (ntds_dn, samdb.domain_dns_name()))
 320
 321     msg = msgs[0]
 322     if (msg.dn.get_rdn_name() != "CN" or
 323         msg.dn.get_rdn_value() != "NTDS Settings"):
 324         raise DemoteException("Given DN (%s) wasn't the NTDS Settings DN" %
 325                               ntds_dn)
 326
 327     ntds_guid = ndr_unpack(misc.GUID, msg["objectGUID"][0])
 328
 329     if remove_connection_obj:
 330         # Find any nTDSConnection objects with that DC as the fromServer.
 331         # We use the GUID to avoid issues with any () chars in a server
 332         # name.
 333         stale_connections = samdb.search(base=samdb.get_config_basedn(),
 334                                          expression="(&(objectclass=nTDSConnection)"
 335                                          "(fromServer=<GUID=%s>))" % ntds_guid)
 336         for conn in stale_connections:
 337             logger.info("Removing nTDSConnection: %s" % conn.dn)
 338             samdb.delete(conn.dn)
 339
 340     if seize_stale_fsmo:
 341         stale_fsmo_roles = samdb.search(base="", scope=ldb.SCOPE_SUBTREE,
 342                                         expression="(fsmoRoleOwner=<GUID=%s>))"
 343                                         % ntds_guid,
 344                                         controls=["search_options:0:2"])
 345         # Find any FSMO roles they have, give them to this server
 346
 347         for role in stale_fsmo_roles:
 348             val = str(my_serviceName)
 349             m = ldb.Message()
 350             m.dn = role.dn
 351             m['value'] = ldb.MessageElement(val, ldb.FLAG_MOD_REPLACE,
 352                                             'fsmoRoleOwner')
 353             logger.warning("Seizing FSMO role on: %s (now owned by %s)"
 354                            % (role.dn, my_serviceName))
 355             samdb.modify(m)
 356
 357     # Remove the NTDS setting tree
 358     try:
 359         logger.info("Removing nTDSDSA: %s (and any children)" % ntds_dn)
 360         samdb.delete(ntds_dn, ["tree_delete:0"])
 361     except LdbError as e6:
 362         (enum, estr) = e6.args
 363         raise DemoteException("Failed to remove the DCs NTDS DSA object: %s"
 364                               % estr)
 365
 366     offline_remove_server(samdb, logger, server_dn,
 367                           remove_computer_obj=remove_computer_obj,
 368                           remove_server_obj=remove_server_obj,
 369                           remove_sysvol_obj=remove_sysvol_obj,
 370                           remove_dns_names=remove_dns_names,
 371                           remove_dns_account=remove_dns_account)
 372
 373
 374 def remove_dc(samdb, logger, dc_name):
 375
 376     # TODO: Check if this is the last server (covered mostly by
 377     # refusing to remove our own name)
 378
 379     samdb.transaction_start()
 380
 381     server_dn = None
 382
 383     # Allow the name to be a the nTDS-DSA GUID
 384     try:
 385         ntds_guid = uuid.UUID(hex=dc_name)
 386         ntds_dn = "<GUID=%s>" % ntds_guid
 387     except ValueError:
 388         try:
 389             server_msgs = samdb.search(base=samdb.get_config_basedn(),
 390                                        attrs=[],
 391                                        expression="(&(objectClass=server)"
 392                                        "(cn=%s))"
 393                                        % ldb.binary_encode(dc_name))
 394         except LdbError as e3:
 395             (enum, estr) = e3.args
 396             raise DemoteException("Failure checking if %s is an server "
 397                                   "object in %s: "
 398                                   % (dc_name, samdb.domain_dns_name()), estr)
 399
 400         if (len(server_msgs) == 0):
 401             samdb.transaction_cancel()
 402             raise DemoteException("%s is not an AD DC in %s"
 403                                   % (dc_name, samdb.domain_dns_name()))
 404         server_dn = server_msgs[0].dn
 405
 406         ntds_dn = ldb.Dn(samdb, "CN=NTDS Settings")
 407         ntds_dn.add_base(server_dn)
 408         pass
 409
 410     # Confirm this is really an ntdsDSA object
 411     try:
 412         ntds_msgs = samdb.search(base=ntds_dn, attrs=[], scope=ldb.SCOPE_BASE,
 413                                  expression="(objectClass=ntdsdsa)")
 414     except LdbError as e7:
 415         (enum, estr) = e7.args
 416         if enum == ldb.ERR_NO_SUCH_OBJECT:
 417             ntds_msgs = []
 418             pass
 419         else:
 420             samdb.transaction_cancel()
 421             raise DemoteException("Failure checking if %s is an NTDS DSA in %s: "
 422                                   % (ntds_dn, samdb.domain_dns_name()), estr)
 423
 424     # If the NTDS Settings child DN wasn't found or wasnt an ntdsDSA
 425     # object, just remove the server object located above
 426     if (len(ntds_msgs) == 0):
 427         if server_dn is None:
 428             samdb.transaction_cancel()
 429             raise DemoteException("%s is not an AD DC in %s"
 430                                   % (dc_name, samdb.domain_dns_name()))
 431
 432         offline_remove_server(samdb, logger,
 433                               server_dn,
 434                               remove_computer_obj=True,
 435                               remove_server_obj=True,
 436                               remove_sysvol_obj=True,
 437                               remove_dns_names=True,
 438                               remove_dns_account=True)
 439     else:
 440         offline_remove_ntds_dc(samdb, logger,
 441                                ntds_msgs[0].dn,
 442                                remove_computer_obj=True,
 443                                remove_server_obj=True,
 444                                remove_connection_obj=True,
 445                                seize_stale_fsmo=True,
 446                                remove_sysvol_obj=True,
 447                                remove_dns_names=True,
 448                                remove_dns_account=True)
 449
 450     samdb.transaction_commit()
 451
 452
 453 def offline_remove_dc_RemoveDsServer(samdb, ntds_dn):
 454
 455     samdb.start_transaction()
 456
 457     offline_remove_ntds_dc(samdb, ntds_dn, None)
 458
 459     samdb.commit_transaction()