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