source4/scripting/bin/samba_dnsupdate

   1 #!/usr/bin/env python
   2 # vim: expandtab
   3 #
   4 # update our DNS names using TSIG-GSS
   5 #
   6 # Copyright (C) Andrew Tridgell 2010
   7 #
   8 # This program is free software; you can redistribute it and/or modify
   9 # it under the terms of the GNU General Public License as published by
  10 # the Free Software Foundation; either version 3 of the License, or
  11 # (at your option) any later version.
  12 #
  13 # This program is distributed in the hope that it will be useful,
  14 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 # GNU General Public License for more details.
  17 #
  18 # You should have received a copy of the GNU General Public License
  19 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21
  22 import os
  23 import fcntl
  24 import sys
  25 import tempfile
  26 import subprocess
  27
  28 # ensure we get messages out immediately, so they get in the samba logs,
  29 # and don't get swallowed by a timeout
  30 os.environ['PYTHONUNBUFFERED'] = '1'
  31
  32 # forcing GMT avoids a problem in some timezones with kerberos. Both MIT
  33 # heimdal can get mutual authentication errors due to the 24 second difference
  34 # between UTC and GMT when using some zone files (eg. the PDT zone from
  35 # the US)
  36 os.environ["TZ"] = "GMT"
  37
  38 # Find right directory when running from source tree
  39 sys.path.insert(0, "bin/python")
  40
  41 import samba
  42 import optparse
  43 from samba import getopt as options
  44 from ldb import SCOPE_BASE
  45 from samba.auth import system_session
  46 from samba.samdb import SamDB
  47 from samba.dcerpc import netlogon, winbind
  48
  49 samba.ensure_external_module("dns", "dnspython")
  50 import dns.resolver
  51 import dns.exception
  52
  53 default_ttl = 900
  54 am_rodc = False
  55 error_count = 0
  56
  57 parser = optparse.OptionParser("samba_dnsupdate")
  58 sambaopts = options.SambaOptions(parser)
  59 parser.add_option_group(sambaopts)
  60 parser.add_option_group(options.VersionOptions(parser))
  61 parser.add_option("--verbose", action="store_true")
  62 parser.add_option("--all-names", action="store_true")
  63 parser.add_option("--all-interfaces", action="store_true")
  64 parser.add_option("--use-file", type="string", help="Use a file, rather than real DNS calls")
  65 parser.add_option("--update-list", type="string", help="Add DNS names from the given file")
  66 parser.add_option("--update-cache", type="string", help="Cache database of already registered records")
  67 parser.add_option("--fail-immediately", action='store_true', help="Exit on first failure")
  68 parser.add_option("--no-credentials", dest='nocreds', action='store_true', help="don't try and get credentials")
  69 parser.add_option("--no-substiutions", dest='nosubs', action='store_true', help="don't try and expands variables in file specified by --update-list")
  70
  71 creds = None
  72 ccachename = None
  73
  74 opts, args = parser.parse_args()
  75
  76 if len(args) != 0:
  77     parser.print_usage()
  78     sys.exit(1)
  79
  80 lp = sambaopts.get_loadparm()
  81
  82 domain = lp.get("realm")
  83 host = lp.get("netbios name")
  84 if opts.all_interfaces:
  85     all_interfaces = True
  86 else:
  87     all_interfaces = False
  88
  89 IPs = samba.interface_ips(lp, all_interfaces)
  90 nsupdate_cmd = lp.get('nsupdate command')
  91
  92 if len(IPs) == 0:
  93     print "No IP interfaces - skipping DNS updates"
  94     sys.exit(0)
  95
  96 IP6s = []
  97 IP4s = []
  98 for i in IPs:
  99     if i.find(':') != -1:
 100         IP6s.append(i)
 101     else:
 102         IP4s.append(i)
 103
 104
 105 if opts.verbose:
 106     print "IPs: %s" % IPs
 107
 108
 109 def get_credentials(lp):
 110     """# get credentials if we haven't got them already."""
 111     from samba import credentials
 112     global ccachename, creds
 113     if creds is not None:
 114         return
 115     creds = credentials.Credentials()
 116     creds.guess(lp)
 117     creds.set_machine_account(lp)
 118     creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
 119     (tmp_fd, ccachename) = tempfile.mkstemp()
 120     try:
 121         creds.get_named_ccache(lp, ccachename)
 122     except RuntimeError as e:
 123         os.unlink(ccachename)
 124         raise e
 125
 126
 127 class dnsobj(object):
 128     """an object to hold a parsed DNS line"""
 129
 130     def __init__(self, string_form):
 131         list = string_form.split()
 132         if len(list) < 3:
 133             raise Exception("Invalid DNS entry %r" % string_form)
 134         self.dest = None
 135         self.port = None
 136         self.ip = None
 137         self.existing_port = None
 138         self.existing_weight = None
 139         self.type = list[0]
 140         self.name = list[1]
 141         if self.type == 'SRV':
 142             if len(list) < 4:
 143                 raise Exception("Invalid DNS entry %r" % string_form)
 144             self.dest = list[2]
 145             self.port = list[3]
 146         elif self.type in ['A', 'AAAA']:
 147             self.ip   = list[2] # usually $IP, which gets replaced
 148         elif self.type == 'CNAME':
 149             self.dest = list[2]
 150         elif self.type == 'NS':
 151             self.dest = list[2]
 152         else:
 153             raise Exception("Received unexpected DNS reply of type %s: %s" % (self.type, string_form))
 154
 155     def __str__(self):
 156         if self.type == "A":
 157             return "%s %s %s" % (self.type, self.name, self.ip)
 158         if self.type == "AAAA":
 159             return "%s %s %s" % (self.type, self.name, self.ip)
 160         if self.type == "SRV":
 161             return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
 162         if self.type == "CNAME":
 163             return "%s %s %s" % (self.type, self.name, self.dest)
 164         if self.type == "NS":
 165             return "%s %s %s" % (self.type, self.name, self.dest)
 166
 167
 168 def parse_dns_line(line, sub_vars):
 169     """parse a DNS line from."""
 170     if line.startswith("SRV _ldap._tcp.pdc._msdcs.") and not samdb.am_pdc():
 171         if opts.verbose:
 172             print "Skipping PDC entry (%s) as we are not a PDC" % line
 173         return None
 174     subline = samba.substitute_var(line, sub_vars)
 175     return dnsobj(subline)
 176
 177
 178 def hostname_match(h1, h2):
 179     """see if two hostnames match."""
 180     h1 = str(h1)
 181     h2 = str(h2)
 182     return h1.lower().rstrip('.') == h2.lower().rstrip('.')
 183
 184
 185 def check_dns_name(d):
 186     """check that a DNS entry exists."""
 187     normalised_name = d.name.rstrip('.') + '.'
 188     if opts.verbose:
 189         print "Looking for DNS entry %s as %s" % (d, normalised_name)
 190
 191     if opts.use_file is not None:
 192         try:
 193             dns_file = open(opts.use_file, "r")
 194         except IOError:
 195             return False
 196
 197         for line in dns_file:
 198             line = line.strip()
 199             if line == '' or line[0] == "#":
 200                 continue
 201             if line.lower() == str(d).lower():
 202                 return True
 203         return False
 204
 205     resolver = dns.resolver.Resolver()
 206     if d.type == "NS":
 207         # we need to lookup the nameserver for the parent domain,
 208         # and use that to check the NS record
 209         parent_domain = '.'.join(normalised_name.split('.')[1:])
 210         try:
 211             ans = resolver.query(parent_domain, 'NS')
 212         except dns.exception.DNSException:
 213             if opts.verbose:
 214                 print "Failed to find parent NS for %s" % d
 215             return False
 216         nameservers = set()
 217         for i in range(len(ans)):
 218             try:
 219                 ns = resolver.query(str(ans[i]), 'A')
 220             except dns.exception.DNSException:
 221                 continue
 222             for j in range(len(ns)):
 223                 nameservers.add(str(ns[j]))
 224         d.nameservers = list(nameservers)
 225
 226     try:
 227         if getattr(d, 'nameservers', None):
 228             resolver.nameservers = list(d.nameservers)
 229         ans = resolver.query(normalised_name, d.type)
 230     except dns.exception.DNSException:
 231         if opts.verbose:
 232             print "Failed to find DNS entry %s" % d
 233         return False
 234     if d.type in ['A', 'AAAA']:
 235         # we need to be sure that our IP is there
 236         for rdata in ans:
 237             if str(rdata) == str(d.ip):
 238                 return True
 239     elif d.type == 'CNAME':
 240         for i in range(len(ans)):
 241             if hostname_match(ans[i].target, d.dest):
 242                 return True
 243     elif d.type == 'NS':
 244         for i in range(len(ans)):
 245             if hostname_match(ans[i].target, d.dest):
 246                 return True
 247     elif d.type == 'SRV':
 248         for rdata in ans:
 249             if opts.verbose:
 250                 print "Checking %s against %s" % (rdata, d)
 251             if hostname_match(rdata.target, d.dest):
 252                 if str(rdata.port) == str(d.port):
 253                     return True
 254                 else:
 255                     d.existing_port     = str(rdata.port)
 256                     d.existing_weight = str(rdata.weight)
 257
 258     if opts.verbose:
 259         print "Failed to find matching DNS entry %s" % d
 260
 261     return False
 262
 263
 264 def get_subst_vars(samdb):
 265     """get the list of substitution vars."""
 266     global lp, am_rodc
 267     vars = {}
 268
 269     vars['DNSDOMAIN'] = samdb.domain_dns_name()
 270     vars['DNSFOREST'] = samdb.forest_dns_name()
 271     vars['HOSTNAME']  = samdb.host_dns_name()
 272     vars['NTDSGUID']  = samdb.get_ntds_GUID()
 273     vars['SITE']      = samdb.server_site_name()
 274     res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
 275     guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
 276     vars['DOMAINGUID'] = guid
 277     am_rodc = samdb.am_rodc()
 278
 279     return vars
 280
 281
 282 def call_nsupdate(d, op="add"):
 283     """call nsupdate for an entry."""
 284     global ccachename, nsupdate_cmd, krb5conf
 285
 286     assert(op in ["add", "delete"])
 287
 288     if opts.verbose:
 289         print "Calling nsupdate for %s (%s)" % (d, op)
 290
 291     if opts.use_file is not None:
 292         try:
 293             rfile = open(opts.use_file, 'r+')
 294         except IOError:
 295             # Perhaps create it
 296             rfile = open(opts.use_file, 'w+')
 297             # Open it for reading again, in case someone else got to it first
 298             rfile = open(opts.use_file, 'r+')
 299         fcntl.lockf(rfile, fcntl.LOCK_EX)
 300         (file_dir, file_name) = os.path.split(opts.use_file)
 301         (tmp_fd, tmpfile) = tempfile.mkstemp(dir=file_dir, prefix=file_name, suffix="XXXXXX")
 302         wfile = os.fdopen(tmp_fd, 'a')
 303         rfile.seek(0)
 304         for line in rfile:
 305             if op == "delete":
 306                 l = parse_dns_line(line, {})
 307                 if str(l).lower() == str(d).lower():
 308                     continue
 309             wfile.write(line)
 310         if op == "add":
 311             wfile.write(str(d)+"\n")
 312         os.rename(tmpfile, opts.use_file)
 313         fcntl.lockf(rfile, fcntl.LOCK_UN)
 314         return
 315
 316     normalised_name = d.name.rstrip('.') + '.'
 317
 318     (tmp_fd, tmpfile) = tempfile.mkstemp()
 319     f = os.fdopen(tmp_fd, 'w')
 320     if getattr(d, 'nameservers', None):
 321         f.write('server %s\n' % d.nameservers[0])
 322     if d.type == "A":
 323         f.write("update %s %s %u A %s\n" % (op, normalised_name, default_ttl, d.ip))
 324     if d.type == "AAAA":
 325         f.write("update %s %s %u AAAA %s\n" % (op, normalised_name, default_ttl, d.ip))
 326     if d.type == "SRV":
 327         if op == "add" and d.existing_port is not None:
 328             f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
 329                                                            d.existing_port, d.dest))
 330         f.write("update %s %s %u SRV 0 100 %s %s\n" % (op, normalised_name, default_ttl, d.port, d.dest))
 331     if d.type == "CNAME":
 332         f.write("update %s %s %u CNAME %s\n" % (op, normalised_name, default_ttl, d.dest))
 333     if d.type == "NS":
 334         f.write("update %s %s %u NS %s\n" % (op, normalised_name, default_ttl, d.dest))
 335     if opts.verbose:
 336         f.write("show\n")
 337     f.write("send\n")
 338     f.close()
 339
 340     global error_count
 341     if ccachename:
 342         os.environ["KRB5CCNAME"] = ccachename
 343     try:
 344         cmd = nsupdate_cmd[:]
 345         cmd.append(tmpfile)
 346         env = {}
 347         if krb5conf:
 348             env["KRB5_CONFIG"] = krb5conf
 349         if ccachename:
 350             env["KRB5CCNAME"] = ccachename
 351         ret = subprocess.call(cmd, shell=False, env=env)
 352         if ret != 0:
 353             if opts.fail_immediately:
 354                 if opts.verbose:
 355                     print("Failed update with %s" % tmpfile)
 356                 sys.exit(1)
 357             error_count = error_count + 1
 358             if opts.verbose:
 359                 print("Failed nsupdate: %d" % ret)
 360     except Exception, estr:
 361         if opts.fail_immediately:
 362             sys.exit(1)
 363         error_count = error_count + 1
 364         if opts.verbose:
 365             print("Failed nsupdate: %s : %s" % (str(d), estr))
 366     os.unlink(tmpfile)
 367
 368
 369
 370 def rodc_dns_update(d, t, op):
 371     '''a single DNS update via the RODC netlogon call'''
 372     global sub_vars
 373
 374     assert(op in ["add", "delete"])
 375
 376     if opts.verbose:
 377         print "Calling netlogon RODC update for %s" % d
 378
 379     typemap = {
 380         netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
 381         netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
 382         netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
 383         netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
 384         netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
 385         netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
 386         netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
 387         }
 388
 389     w = winbind.winbind("irpc:winbind_server", lp)
 390     dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
 391     dns_names.count = 1
 392     name = netlogon.NL_DNS_NAME_INFO()
 393     name.type = t
 394     name.dns_domain_info_type = typemap[t]
 395     name.priority = 0
 396     name.weight   = 0
 397     if d.port is not None:
 398         name.port = int(d.port)
 399     if op == "add":
 400         name.dns_register = True
 401     else:
 402         name.dns_register = False
 403     dns_names.names = [ name ]
 404     site_name = sub_vars['SITE'].decode('utf-8')
 405
 406     global error_count
 407
 408     try:
 409         ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
 410         if ret_names.names[0].status != 0:
 411             print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
 412             error_count = error_count + 1
 413     except RuntimeError, reason:
 414         print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
 415         error_count = error_count + 1
 416
 417     if error_count != 0 and opts.fail_immediately:
 418         sys.exit(1)
 419
 420
 421 def call_rodc_update(d, op="add"):
 422     '''RODCs need to use the netlogon API for nsupdate'''
 423     global lp, sub_vars
 424
 425     assert(op in ["add", "delete"])
 426
 427     # we expect failure for 3268 if we aren't a GC
 428     if d.port is not None and int(d.port) == 3268:
 429         return
 430
 431     # map the DNS request to a netlogon update type
 432     map = {
 433         netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
 434         netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
 435         netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
 436         netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 437         netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 438         netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
 439         netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
 440         }
 441
 442     for t in map:
 443         subname = samba.substitute_var(map[t], sub_vars)
 444         if subname.lower() == d.name.lower():
 445             # found a match - do the update
 446             rodc_dns_update(d, t, op)
 447             return
 448     if opts.verbose:
 449         print("Unable to map to netlogon DNS update: %s" % d)
 450
 451
 452 # get the list of DNS entries we should have
 453 if opts.update_list:
 454     dns_update_list = opts.update_list
 455 else:
 456     dns_update_list = lp.private_path('dns_update_list')
 457
 458 if opts.update_cache:
 459     dns_update_cache = opts.update_cache
 460 else:
 461     dns_update_cache = lp.private_path('dns_update_cache')
 462
 463 # use our private krb5.conf to avoid problems with the wrong domain
 464 # bind9 nsupdate wants the default domain set
 465 krb5conf = lp.private_path('krb5.conf')
 466 os.environ['KRB5_CONFIG'] = krb5conf
 467
 468 file = open(dns_update_list, "r")
 469
 470 if opts.nosubs:
 471     sub_vars = {}
 472 else:
 473     samdb = SamDB(url=lp.samdb_url(), session_info=system_session(), lp=lp)
 474
 475     # get the substitution dictionary
 476     sub_vars = get_subst_vars(samdb)
 477
 478 # build up a list of update commands to pass to nsupdate
 479 update_list = []
 480 dns_list = []
 481 cache_list = []
 482 delete_list = []
 483
 484 dup_set = set()
 485 cache_set = set()
 486
 487 rebuild_cache = False
 488 try:
 489     cfile = open(dns_update_cache, 'r+')
 490 except IOError:
 491     # Perhaps create it
 492     cfile = open(dns_update_cache, 'w+')
 493     # Open it for reading again, in case someone else got to it first
 494     cfile = open(dns_update_cache, 'r+')
 495 fcntl.lockf(cfile, fcntl.LOCK_EX)
 496 for line in cfile:
 497     line = line.strip()
 498     if line == '' or line[0] == "#":
 499         continue
 500     c = parse_dns_line(line, {})
 501     if c is None:
 502         continue
 503     if str(c) not in cache_set:
 504         cache_list.append(c)
 505         cache_set.add(str(c))
 506
 507 # read each line, and check that the DNS name exists
 508 for line in file:
 509     line = line.strip()
 510     if line == '' or line[0] == "#":
 511         continue
 512     d = parse_dns_line(line, sub_vars)
 513     if d is None:
 514         continue
 515     if d.type == 'A' and len(IP4s) == 0:
 516         continue
 517     if d.type == 'AAAA' and len(IP6s) == 0:
 518         continue
 519     if str(d) not in dup_set:
 520         dns_list.append(d)
 521         dup_set.add(str(d))
 522
 523 # now expand the entries, if any are A record with ip set to $IP
 524 # then replace with multiple entries, one for each interface IP
 525 for d in dns_list:
 526     if d.ip != "$IP":
 527         continue
 528     if d.type == 'A':
 529         d.ip = IP4s[0]
 530         for i in range(len(IP4s)-1):
 531             d2 = dnsobj(str(d))
 532             d2.ip = IP4s[i+1]
 533             dns_list.append(d2)
 534     if d.type == 'AAAA':
 535         d.ip = IP6s[0]
 536         for i in range(len(IP6s)-1):
 537             d2 = dnsobj(str(d))
 538             d2.ip = IP6s[i+1]
 539             dns_list.append(d2)
 540
 541 # now check if the entries already exist on the DNS server
 542 for d in dns_list:
 543     found = False
 544     for c in cache_list:
 545         if str(c).lower() == str(d).lower():
 546             found = True
 547             break
 548     if not found:
 549         rebuild_cache = True
 550     if opts.all_names or not check_dns_name(d):
 551         update_list.append(d)
 552
 553 for c in cache_list:
 554     found = False
 555     for d in dns_list:
 556         if str(c).lower() == str(d).lower():
 557             found = True
 558             break
 559     if found:
 560         continue
 561     rebuild_cache = True
 562     if not opts.all_names and not check_dns_name(c):
 563         continue
 564     delete_list.append(c)
 565
 566 if len(delete_list) == 0 and len(update_list) == 0 and not rebuild_cache:
 567     if opts.verbose:
 568         print "No DNS updates needed"
 569     sys.exit(0)
 570
 571 # get our krb5 creds
 572 if len(delete_list) != 0 or len(update_list) != 0:
 573     if not opts.nocreds:
 574         get_credentials(lp)
 575
 576 # ask nsupdate to delete entries as needed
 577 for d in delete_list:
 578     if am_rodc:
 579         if d.name.lower() == domain.lower():
 580             continue
 581         if not d.type in [ 'A', 'AAAA' ]:
 582             call_rodc_update(d, op="delete")
 583         else:
 584             call_nsupdate(d, op="delete")
 585     else:
 586         call_nsupdate(d, op="delete")
 587
 588 # ask nsupdate to add entries as needed
 589 for d in update_list:
 590     if am_rodc:
 591         if d.name.lower() == domain.lower():
 592             continue
 593         if not d.type in [ 'A', 'AAAA' ]:
 594             call_rodc_update(d)
 595         else:
 596             call_nsupdate(d)
 597     else:
 598         call_nsupdate(d)
 599
 600 if rebuild_cache:
 601     (file_dir, file_name) = os.path.split(dns_update_cache)
 602     (tmp_fd, tmpfile) = tempfile.mkstemp(dir=file_dir, prefix=file_name, suffix="XXXXXX")
 603     wfile = os.fdopen(tmp_fd, 'a')
 604     for d in dns_list:
 605         wfile.write(str(d)+"\n")
 606     os.rename(tmpfile, dns_update_cache)
 607 fcntl.lockf(cfile, fcntl.LOCK_UN)
 608
 609 # delete the ccache if we created it
 610 if ccachename is not None:
 611     os.unlink(ccachename)
 612
 613 if error_count != 0:
 614     print("Failed update of %u entries" % error_count)
 615 sys.exit(error_count)