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.ndr import ndr_unpack
  23 from samba.dcerpc import misc, dnsp
  24 from samba.dcerpc.dnsp import DNS_TYPE_NS, DNS_TYPE_A, DNS_TYPE_AAAA, \
  25     DNS_TYPE_CNAME, DNS_TYPE_SRV, DNS_TYPE_PTR
  26
  27 class DemoteException(Exception):
  28     """Base element for demote errors"""
  29
  30     def __init__(self, value):
  31         self.value = value
  32
  33     def __str__(self):
  34         return "DemoteException: " + self.value
  35
  36
  37 def remove_sysvol_references(samdb, logger, dc_name):
  38     # DNs under the Configuration DN:
  39     realm = samdb.domain_dns_name()
  40     for s in ("CN=Enterprise,CN=Microsoft System Volumes,CN=System",
  41               "CN=%s,CN=Microsoft System Volumes,CN=System" % realm):
  42         dn = ldb.Dn(samdb, s)
  43
  44         # This is verbose, but it is the safe, escape-proof way
  45         # to add a base and add an arbitrary RDN.
  46         if dn.add_base(samdb.get_config_basedn()) == False:
  47             raise DemoteException("Failed constructing DN %s by adding base %s" \
  48                                   % (dn, samdb.get_config_basedn()))
  49         if dn.add_child("CN=X") == False:
  50             raise DemoteException("Failed constructing DN %s by adding child CN=X"\
  51                                       % (dn))
  52         dn.set_component(0, "CN", dc_name)
  53         try:
  54             logger.info("Removing Sysvol reference: %s" % dn)
  55             samdb.delete(dn)
  56         except ldb.LdbError as (enum, estr):
  57             if enum == ldb.ERR_NO_SUCH_OBJECT:
  58                 pass
  59             else:
  60                 raise
  61
  62     # DNs under the Domain DN:
  63     for s in ("CN=Domain System Volumes (SYSVOL share),CN=File Replication Service,CN=System",
  64               "CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System"):
  65         # This is verbose, but it is the safe, escape-proof way
  66         # to add a base and add an arbitrary RDN.
  67         dn = ldb.Dn(samdb, s)
  68         if dn.add_base(samdb.get_default_basedn()) == False:
  69             raise DemoteException("Failed constructing DN %s by adding base" % \
  70                                   (dn, samdb.get_default_basedn()))
  71         if dn.add_child("CN=X") == False:
  72             raise DemoteException("Failed constructing DN %s by adding child %s"\
  73                                   % (dn, rdn))
  74         dn.set_component(0, "CN", dc_name)
  75
  76         try:
  77             logger.info("Removing Sysvol reference: %s" % dn)
  78             samdb.delete(dn)
  79         except ldb.LdbError as (enum, estr):
  80             if enum == ldb.ERR_NO_SUCH_OBJECT:
  81                 pass
  82             else:
  83                 raise
  84
  85
  86 def remove_dns_references(samdb, logger, dnsHostName):
  87
  88     # Check we are using in-database DNS
  89     zones = samdb.search(base="", scope=ldb.SCOPE_SUBTREE,
  90                          expression="(&(objectClass=dnsZone)(!(dc=RootDNSServers)))",
  91                          attrs=[],
  92                          controls=["search_options:0:2"])
  93     if len(zones) == 0:
  94         return
  95
  96     dnsHostNameUpper = dnsHostName.upper()
  97
  98     try:
  99         primary_recs = samdb.dns_lookup(dnsHostName)
 100     except RuntimeError as (enum, estr):
 101         if enum == 0x000025F2: #WERR_DNS_ERROR_NAME_DOES_NOT_EXIST
 102               return
 103         raise DemoteException("lookup of %s failed: %s" % (dnsHostName, estr))
 104     samdb.dns_replace(dnsHostName, [])
 105
 106     res = samdb.search("",
 107                        scope=ldb.SCOPE_BASE, attrs=["namingContexts"])
 108     assert len(res) == 1
 109     ncs = res[0]["namingContexts"]
 110
 111     # Work out the set of names we will likely have an A record on by
 112     # default.  This is by default all the partitions of type
 113     # domainDNS.  By finding the canocial name of all the partitions,
 114     # we find the likely candidates.  We only remove the record if it
 115     # maches the IP that was used by the dnsHostName.  This avoids us
 116     # needing to look a the dns_update_list file from in the demote
 117     # script.
 118
 119     def dns_name_from_dn(dn):
 120         # The canonical string of DC=example,DC=com is
 121         # example.com/
 122         #
 123         # The canonical string of CN=Configuration,DC=example,DC=com
 124         # is example.com/Configuration
 125         return ldb.Dn(samdb, dn).canonical_str().split('/', 1)[0]
 126
 127     # By using a set here, duplicates via (eg) example.com/Configuration
 128     # do not matter, they become just example.com
 129     a_names_to_remove_from \
 130         = set(dns_name_from_dn(dn) for dn in ncs)
 131
 132     def a_rec_to_remove(dnsRecord):
 133         if dnsRecord.wType == DNS_TYPE_A or dnsRecord.wType == DNS_TYPE_AAAA:
 134             for rec in primary_recs:
 135                 if rec.wType == dnsRecord.wType and rec.data == dnsRecord.data:
 136                     return True
 137         return False
 138
 139     for a_name in a_names_to_remove_from:
 140         try:
 141             logger.debug("checking for DNS records to remove on %s" % a_name)
 142             a_recs = samdb.dns_lookup(a_name)
 143         except RuntimeError as (enum, estr):
 144             if enum == 0x000025F2: #WERR_DNS_ERROR_NAME_DOES_NOT_EXIST
 145                 return
 146             raise DemoteException("lookup of %s failed: %s" % (a_name, estr))
 147
 148         orig_num_recs = len(a_recs)
 149         a_recs = [ r for r in a_recs if not a_rec_to_remove(r) ]
 150
 151         if len(a_recs) != orig_num_recs:
 152             logger.info("updating %s keeping %d values, removing %s values" % \
 153                 (a_name, len(a_recs), orig_num_recs - len(a_recs)))
 154             samdb.dns_replace(a_name, a_recs)
 155
 156     # Find all the CNAME, NS, PTR and SRV records that point at the
 157     # name we are removing
 158
 159     def to_remove(value):
 160         dnsRecord = ndr_unpack(dnsp.DnssrvRpcRecord, value)
 161         if dnsRecord.wType == DNS_TYPE_NS \
 162            or dnsRecord.wType == DNS_TYPE_CNAME \
 163            or dnsRecord.wType == DNS_TYPE_PTR:
 164             if dnsRecord.data.upper() == dnsHostNameUpper:
 165                 return True
 166         elif dnsRecord.wType == DNS_TYPE_SRV:
 167             if dnsRecord.data.nameTarget.upper() == dnsHostNameUpper:
 168                 return True
 169         return False
 170
 171     for zone in zones:
 172         logger.debug("checking %s" % zone.dn)
 173         records = samdb.search(base=zone.dn, scope=ldb.SCOPE_SUBTREE,
 174                                expression="(&(objectClass=dnsNode)"
 175                                "(!(dNSTombstoned=TRUE)))",
 176                                attrs=["dnsRecord"])
 177         for record in records:
 178             try:
 179                 orig_values = record["dnsRecord"]
 180             except KeyError:
 181                 continue
 182
 183             # Remove references to dnsHostName in A, AAAA, NS, CNAME and SRV
 184             values = [ ndr_unpack(dnsp.DnssrvRpcRecord, v)
 185                        for v in orig_values if not to_remove(v) ]
 186
 187             if len(values) != len(orig_values):
 188                 logger.info("updating %s keeping %d values, removing %s values" \
 189                             % (record.dn, len(values),
 190                                len(orig_values) - len(values)))
 191
 192                 # This requires the values to be unpacked, so this
 193                 # has been done in the list comprehension above
 194                 samdb.dns_replace_by_dn(record.dn, values)
 195
 196 def offline_remove_server(samdb, logger,
 197                           server_dn,
 198                           remove_computer_obj=False,
 199                           remove_server_obj=False,
 200                           remove_sysvol_obj=False,
 201                           remove_dns_names=False,
 202                           remove_dns_account=False):
 203     res = samdb.search("",
 204                        scope=ldb.SCOPE_BASE, attrs=["dsServiceName"])
 205     assert len(res) == 1
 206     my_serviceName = res[0]["dsServiceName"][0]
 207
 208     # Confirm this is really a server object
 209     msgs = samdb.search(base=server_dn,
 210                         attrs=["serverReference", "cn",
 211                                "dnsHostName"],
 212                         scope=ldb.SCOPE_BASE,
 213                         expression="(objectClass=server)")
 214     msg = msgs[0]
 215     dc_name = str(msgs[0]["cn"][0])
 216
 217     try:
 218         computer_dn = ldb.Dn(samdb, msgs[0]["serverReference"][0])
 219     except KeyError:
 220         computer_dn = None
 221
 222     try:
 223         dnsHostName = msgs[0]["dnsHostName"][0]
 224     except KeyError:
 225         dnsHostName = None
 226
 227     if remove_server_obj:
 228         # Remove the server DN
 229         samdb.delete(server_dn)
 230
 231     if computer_dn is not None:
 232         computer_msgs = samdb.search(base=computer_dn,
 233                                      expression="objectclass=computer",
 234                                      attrs=["msDS-KrbTgtLink",
 235                                             "rIDSetReferences",
 236                                             "cn"],
 237                                      scope=ldb.SCOPE_BASE)
 238         if "rIDSetReferences" in computer_msgs[0]:
 239             rid_set_dn = str(computer_msgs[0]["rIDSetReferences"][0])
 240             logger.info("Removing RID Set: %s" % rid_set_dn)
 241             samdb.delete(rid_set_dn)
 242         if "msDS-KrbTgtLink" in computer_msgs[0]:
 243             krbtgt_link_dn = str(computer_msgs[0]["msDS-KrbTgtLink"][0])
 244             logger.info("Removing RODC KDC account: %s" % krbtgt_link_dn)
 245             samdb.delete(krbtgt_link_dn)
 246
 247         if remove_computer_obj:
 248             # Delete the computer tree
 249             logger.info("Removing computer account: %s (and any child objects)" % computer_dn)
 250             samdb.delete(computer_dn, ["tree_delete:0"])
 251
 252         if "dnsHostName" in msgs[0]:
 253             dnsHostName = msgs[0]["dnsHostName"][0]
 254
 255     if remove_dns_account:
 256         res = samdb.search(expression="(&(objectclass=user)(cn=dns-%s)(servicePrincipalName=DNS/%s))" %
 257                            (ldb.binary_encode(dc_name), dnsHostName),
 258                            attrs=[], scope=ldb.SCOPE_SUBTREE,
 259                            base=samdb.get_default_basedn())
 260         if len(res) == 1:
 261             logger.info("Removing Samba-specific DNS service account: %s" % res[0].dn)
 262             samdb.delete(res[0].dn)
 263
 264     if dnsHostName is not None and remove_dns_names:
 265         remove_dns_references(samdb, logger, dnsHostName)
 266
 267     if remove_sysvol_obj:
 268         remove_sysvol_references(samdb, logger, dc_name)
 269
 270 def offline_remove_ntds_dc(samdb,
 271                            logger,
 272                            ntds_dn,
 273                            remove_computer_obj=False,
 274                            remove_server_obj=False,
 275                            remove_connection_obj=False,
 276                            seize_stale_fsmo=False,
 277                            remove_sysvol_obj=False,
 278                            remove_dns_names=False,
 279                            remove_dns_account=False):
 280     res = samdb.search("",
 281                        scope=ldb.SCOPE_BASE, attrs=["dsServiceName"])
 282     assert len(res) == 1
 283     my_serviceName = ldb.Dn(samdb, res[0]["dsServiceName"][0])
 284     server_dn = ntds_dn.parent()
 285
 286     if my_serviceName == ntds_dn:
 287         raise DemoteException("Refusing to demote our own DSA: %s " % my_serviceName)
 288
 289     try:
 290         msgs = samdb.search(base=ntds_dn, expression="objectClass=ntdsDSA",
 291                         attrs=["objectGUID"], scope=ldb.SCOPE_BASE)
 292     except LdbError as (enum, estr):
 293         if enum == ldb.ERR_NO_SUCH_OBJECT:
 294               raise DemoteException("Given DN %s doesn't exist" % ntds_dn)
 295         else:
 296             raise
 297     if (len(msgs) == 0):
 298         raise DemoteException("%s is not an ntdsda in %s"
 299                               % (ntds_dn, samdb.domain_dns_name()))
 300
 301     msg = msgs[0]
 302     if (msg.dn.get_rdn_name() != "CN" or
 303         msg.dn.get_rdn_value() != "NTDS Settings"):
 304         raise DemoteException("Given DN (%s) wasn't the NTDS Settings DN" %
 305                               ntds_dn)
 306
 307     ntds_guid = ndr_unpack(misc.GUID, msg["objectGUID"][0])
 308
 309     if remove_connection_obj:
 310         # Find any nTDSConnection objects with that DC as the fromServer.
 311         # We use the GUID to avoid issues with any () chars in a server
 312         # name.
 313         stale_connections = samdb.search(base=samdb.get_config_basedn(),
 314                                          expression="(&(objectclass=nTDSConnection)"
 315                                          "(fromServer=<GUID=%s>))" % ntds_guid)
 316         for conn in stale_connections:
 317             logger.info("Removing nTDSConnection: %s" % conn.dn)
 318             samdb.delete(conn.dn)
 319
 320     if seize_stale_fsmo:
 321         stale_fsmo_roles = samdb.search(base="", scope=ldb.SCOPE_SUBTREE,
 322                                         expression="(fsmoRoleOwner=<GUID=%s>))"
 323                                         % ntds_guid,
 324                                         controls=["search_options:0:2"])
 325         # Find any FSMO roles they have, give them to this server
 326
 327         for role in stale_fsmo_roles:
 328             val = str(my_serviceName)
 329             m = ldb.Message()
 330             m.dn = role.dn
 331             m['value'] = ldb.MessageElement(val, ldb.FLAG_MOD_REPLACE,
 332                                             'fsmoRoleOwner')
 333             logger.warning("Seizing FSMO role on: %s (now owned by %s)"
 334                            % (role.dn, my_serviceName))
 335             samdb.modify(m)
 336
 337     # Remove the NTDS setting tree
 338     try:
 339         logger.info("Removing nTDSDSA: %s (and any children)" % ntds_dn)
 340         samdb.delete(ntds_dn, ["tree_delete:0"])
 341     except LdbError as (enum, estr):
 342         raise DemoteException("Failed to remove the DCs NTDS DSA object: %s"
 343                               % estr)
 344
 345     offline_remove_server(samdb, logger, server_dn,
 346                           remove_computer_obj=remove_computer_obj,
 347                           remove_server_obj=remove_server_obj,
 348                           remove_sysvol_obj=remove_sysvol_obj,
 349                           remove_dns_names=remove_dns_names,
 350                           remove_dns_account=remove_dns_account)
 351
 352
 353 def remove_dc(samdb, logger, dc_name):
 354
 355     # TODO: Check if this is the last server (covered mostly by
 356     # refusing to remove our own name)
 357
 358     samdb.transaction_start()
 359
 360     server_dn = None
 361
 362     # Allow the name to be a the nTDS-DSA GUID
 363     try:
 364         ntds_guid = uuid.UUID(hex=dc_name)
 365         ntds_dn = "<GUID=%s>" % ntds_guid
 366     except ValueError:
 367         try:
 368             server_msgs = samdb.search(base=samdb.get_config_basedn(),
 369                                        attrs=[],
 370                                        expression="(&(objectClass=server)"
 371                                        "(cn=%s))"
 372                                     % ldb.binary_encode(dc_name))
 373         except LdbError as (enum, estr):
 374             raise DemoteException("Failure checking if %s is an server "
 375                                   "object in %s: "
 376                                   % (dc_name, samdb.domain_dns_name()), estr)
 377
 378         if (len(server_msgs) == 0):
 379             raise DemoteException("%s is not an AD DC in %s"
 380                                   % (dc_name, samdb.domain_dns_name()))
 381         server_dn = server_msgs[0].dn
 382
 383         ntds_dn = ldb.Dn(samdb, "CN=NTDS Settings")
 384         ntds_dn.add_base(server_dn)
 385         pass
 386
 387     # Confirm this is really an ntdsDSA object
 388     try:
 389         ntds_msgs = samdb.search(base=ntds_dn, attrs=[], scope=ldb.SCOPE_BASE,
 390                                  expression="(objectClass=ntdsdsa)")
 391     except LdbError as (enum, estr):
 392         if enum == ldb.ERR_NO_SUCH_OBJECT:
 393             ntds_msgs = []
 394             pass
 395         else:
 396             raise DemoteException("Failure checking if %s is an NTDS DSA in %s: "
 397                                   % (ntds_dn, samdb.domain_dns_name()), estr)
 398
 399     # If the NTDS Settings child DN wasn't found or wasnt an ntdsDSA
 400     # object, just remove the server object located above
 401     if (len(ntds_msgs) == 0):
 402         if server_dn is None:
 403             raise DemoteException("%s is not an AD DC in %s"
 404                                   % (dc_name, samdb.domain_dns_name()))
 405
 406         offline_remove_server(samdb, logger,
 407                               server_dn,
 408                               remove_computer_obj=True,
 409                               remove_server_obj=True,
 410                               remove_sysvol_obj=True,
 411                               remove_dns_names=True,
 412                               remove_dns_account=True)
 413     else:
 414         offline_remove_ntds_dc(samdb, logger,
 415                                ntds_msgs[0].dn,
 416                                remove_computer_obj=True,
 417                                remove_server_obj=True,
 418                                remove_connection_obj=True,
 419                                seize_stale_fsmo=True,
 420                                remove_sysvol_obj=True,
 421                                remove_dns_names=True,
 422                                remove_dns_account=True)
 423
 424     samdb.transaction_commit()
 425
 426
 427
 428 def offline_remove_dc_RemoveDsServer(samdb, ntds_dn):
 429
 430     samdb.start_transaction()
 431
 432     offline_remove_ntds_dc(samdb, ntds_dn, None)
 433
 434     samdb.commit_transaction()