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