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("--fail-immediately", action='store_true', help="Exit on first failure")
  67 parser.add_option("--no-credentials", dest='nocreds', action='store_true', help="don't try and get credentials")
  68
  69 creds = None
  70 ccachename = None
  71
  72 opts, args = parser.parse_args()
  73
  74 if len(args) != 0:
  75     parser.print_usage()
  76     sys.exit(1)
  77
  78 lp = sambaopts.get_loadparm()
  79
  80 domain = lp.get("realm")
  81 host = lp.get("netbios name")
  82 if opts.all_interfaces:
  83     all_interfaces = True
  84 else:
  85     all_interfaces = False
  86
  87 IPs = samba.interface_ips(lp, all_interfaces)
  88 nsupdate_cmd = lp.get('nsupdate command')
  89
  90 if len(IPs) == 0:
  91     print "No IP interfaces - skipping DNS updates"
  92     sys.exit(0)
  93
  94 IP6s = []
  95 IP4s = []
  96 for i in IPs:
  97     if i.find(':') != -1:
  98         if i.find('%') == -1:
  99             # we don't want link local addresses for DNS updates
 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     creds.get_named_ccache(lp, ccachename)
 121
 122
 123 class dnsobj(object):
 124     """an object to hold a parsed DNS line"""
 125
 126     def __init__(self, string_form):
 127         list = string_form.split()
 128         self.dest = None
 129         self.port = None
 130         self.ip = None
 131         self.existing_port = None
 132         self.existing_weight = None
 133         self.type = list[0]
 134         self.name = list[1].lower()
 135         if self.type == 'SRV':
 136             self.dest = list[2].lower()
 137             self.port = list[3]
 138         elif self.type in ['A', 'AAAA']:
 139             self.ip   = list[2] # usually $IP, which gets replaced
 140         elif self.type == 'CNAME':
 141             self.dest = list[2].lower()
 142         elif self.type == 'NS':
 143             self.dest = list[2].lower()
 144         else:
 145             print "Received unexpected DNS reply of type %s" % self.type
 146             raise
 147
 148     def __str__(self):
 149         if d.type == "A":     return "%s %s %s" % (self.type, self.name, self.ip)
 150         if d.type == "AAAA":  return "%s %s %s" % (self.type, self.name, self.ip)
 151         if d.type == "SRV":   return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
 152         if d.type == "CNAME": return "%s %s %s" % (self.type, self.name, self.dest)
 153         if d.type == "NS":    return "%s %s %s" % (self.type, self.name, self.dest)
 154
 155
 156 def parse_dns_line(line, sub_vars):
 157     """parse a DNS line from."""
 158     if line.startswith("SRV _ldap._tcp.pdc._msdcs.") and not samdb.am_pdc():
 159         if opts.verbose:
 160             print "Skipping PDC entry (%s) as we are not a PDC" % line
 161         return None
 162     subline = samba.substitute_var(line, sub_vars)
 163     d = dnsobj(subline)
 164     return d
 165
 166
 167 def hostname_match(h1, h2):
 168     """see if two hostnames match."""
 169     h1 = str(h1)
 170     h2 = str(h2)
 171     return h1.lower().rstrip('.') == h2.lower().rstrip('.')
 172
 173
 174 def check_dns_name(d):
 175     """check that a DNS entry exists."""
 176     normalised_name = d.name.rstrip('.') + '.'
 177     if opts.verbose:
 178         print "Looking for DNS entry %s as %s" % (d, normalised_name)
 179
 180     if opts.use_file is not None:
 181         try:
 182             dns_file = open(opts.use_file, "r")
 183         except IOError:
 184             return False
 185
 186         for line in dns_file:
 187             line = line.strip()
 188             if line == '' or line[0] == "#":
 189                 continue
 190             if line.lower() == str(d).lower():
 191                 return True
 192         return False
 193
 194     resolver = dns.resolver.Resolver()
 195     if d.type == "NS":
 196         # we need to lookup the nameserver for the parent domain,
 197         # and use that to check the NS record
 198         parent_domain = '.'.join(normalised_name.split('.')[1:])
 199         try:
 200             ans = resolver.query(parent_domain, 'NS')
 201         except dns.exception.DNSException:
 202             if opts.verbose:
 203                 print "Failed to find parent NS for %s" % d
 204             return False
 205         nameservers = set()
 206         for i in range(len(ans)):
 207             try:
 208                 ns = resolver.query(str(ans[i]), 'A')
 209             except dns.exception.DNSException:
 210                 continue
 211             for j in range(len(ns)):
 212                 nameservers.add(str(ns[j]))
 213         d.nameservers = list(nameservers)
 214
 215     try:
 216         if getattr(d, 'nameservers', None):
 217             resolver.nameservers = list(d.nameservers)
 218         ans = resolver.query(normalised_name, d.type)
 219     except dns.exception.DNSException:
 220         if opts.verbose:
 221             print "Failed to find DNS entry %s" % d
 222         return False
 223     if d.type in ['A', 'AAAA']:
 224         # we need to be sure that our IP is there
 225         for rdata in ans:
 226             if str(rdata) == str(d.ip):
 227                 return True
 228     elif d.type == 'CNAME':
 229         for i in range(len(ans)):
 230             if hostname_match(ans[i].target, d.dest):
 231                 return True
 232     elif d.type == 'NS':
 233         for i in range(len(ans)):
 234             if hostname_match(ans[i].target, d.dest):
 235                 return True
 236     elif d.type == 'SRV':
 237         for rdata in ans:
 238             if opts.verbose:
 239                 print "Checking %s against %s" % (rdata, d)
 240             if hostname_match(rdata.target, d.dest):
 241                 if str(rdata.port) == str(d.port):
 242                     return True
 243                 else:
 244                     d.existing_port     = str(rdata.port)
 245                     d.existing_weight = str(rdata.weight)
 246
 247     if opts.verbose:
 248         print "Failed to find matching DNS entry %s" % d
 249
 250     return False
 251
 252
 253 def get_subst_vars(samdb):
 254     """get the list of substitution vars."""
 255     global lp, am_rodc
 256     vars = {}
 257
 258     vars['DNSDOMAIN'] = samdb.domain_dns_name()
 259     vars['DNSFOREST'] = samdb.forest_dns_name()
 260     vars['HOSTNAME']  = samdb.host_dns_name()
 261     vars['NTDSGUID']  = samdb.get_ntds_GUID()
 262     vars['SITE']      = samdb.server_site_name()
 263     res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
 264     guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
 265     vars['DOMAINGUID'] = guid
 266     am_rodc = samdb.am_rodc()
 267
 268     return vars
 269
 270
 271 def call_nsupdate(d):
 272     """call nsupdate for an entry."""
 273     global ccachename, nsupdate_cmd
 274
 275     if opts.verbose:
 276         print "Calling nsupdate for %s" % d
 277
 278     if opts.use_file is not None:
 279         wfile = open(opts.use_file, 'a')
 280         fcntl.lockf(wfile, fcntl.LOCK_EX)
 281         wfile.write(str(d)+"\n")
 282         fcntl.lockf(wfile, fcntl.LOCK_UN)
 283         return
 284
 285     normalised_name = d.name.rstrip('.') + '.'
 286
 287     (tmp_fd, tmpfile) = tempfile.mkstemp()
 288     f = os.fdopen(tmp_fd, 'w')
 289     if getattr(d, 'nameservers', None):
 290         f.write('server %s\n' % d.nameservers[0])
 291     if d.type == "A":
 292         f.write("update add %s %u A %s\n" % (normalised_name, default_ttl, d.ip))
 293     if d.type == "AAAA":
 294         f.write("update add %s %u AAAA %s\n" % (normalised_name, default_ttl, d.ip))
 295     if d.type == "SRV":
 296         if d.existing_port is not None:
 297             f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
 298                                                            d.existing_port, d.dest))
 299         f.write("update add %s %u SRV 0 100 %s %s\n" % (normalised_name, default_ttl, d.port, d.dest))
 300     if d.type == "CNAME":
 301         f.write("update add %s %u CNAME %s\n" % (normalised_name, default_ttl, d.dest))
 302     if d.type == "NS":
 303         f.write("update add %s %u NS %s\n" % (normalised_name, default_ttl, d.dest))
 304     if opts.verbose:
 305         f.write("show\n")
 306     f.write("send\n")
 307     f.close()
 308
 309     global error_count
 310     if ccachename:
 311         os.environ["KRB5CCNAME"] = ccachename
 312     try:
 313         cmd = nsupdate_cmd[:]
 314         cmd.append(tmpfile)
 315         if ccachename:
 316             env = {"KRB5CCNAME": ccachename}
 317         else:
 318             env = {}
 319         ret = subprocess.call(cmd, shell=False, env=env)
 320         if ret != 0:
 321             if opts.fail_immediately:
 322                 if opts.verbose:
 323                     print("Failed update with %s" % tmpfile)
 324                 sys.exit(1)
 325             error_count = error_count + 1
 326             if opts.verbose:
 327                 print("Failed nsupdate: %d" % ret)
 328     except Exception, estr:
 329         if opts.fail_immediately:
 330             sys.exit(1)
 331         error_count = error_count + 1
 332         if opts.verbose:
 333             print("Failed nsupdate: %s : %s" % (str(d), estr))
 334     os.unlink(tmpfile)
 335
 336
 337
 338 def rodc_dns_update(d, t):
 339     '''a single DNS update via the RODC netlogon call'''
 340     global sub_vars
 341
 342     if opts.verbose:
 343         print "Calling netlogon RODC update for %s" % d
 344
 345     typemap = {
 346         netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
 347         netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
 348         netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
 349         netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
 350         netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
 351         netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
 352         netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
 353         }
 354
 355     w = winbind.winbind("irpc:winbind_server", lp)
 356     dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
 357     dns_names.count = 1
 358     name = netlogon.NL_DNS_NAME_INFO()
 359     name.type = t
 360     name.dns_domain_info_type = typemap[t]
 361     name.priority = 0
 362     name.weight   = 0
 363     if d.port is not None:
 364         name.port = int(d.port)
 365     name.dns_register = True
 366     dns_names.names = [ name ]
 367     site_name = sub_vars['SITE'].decode('utf-8')
 368
 369     global error_count
 370
 371     try:
 372         ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
 373         if ret_names.names[0].status != 0:
 374             print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
 375             error_count = error_count + 1
 376     except RuntimeError, reason:
 377         print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
 378         error_count = error_count + 1
 379
 380     if error_count != 0 and opts.fail_immediately:
 381         sys.exit(1)
 382
 383
 384 def call_rodc_update(d):
 385     '''RODCs need to use the netlogon API for nsupdate'''
 386     global lp, sub_vars
 387
 388     # we expect failure for 3268 if we aren't a GC
 389     if d.port is not None and int(d.port) == 3268:
 390         return
 391
 392     # map the DNS request to a netlogon update type
 393     map = {
 394         netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
 395         netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
 396         netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
 397         netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 398         netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 399         netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
 400         netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
 401         }
 402
 403     for t in map:
 404         subname = samba.substitute_var(map[t], sub_vars)
 405         if subname.lower() == d.name.lower():
 406             # found a match - do the update
 407             rodc_dns_update(d, t)
 408             return
 409     if opts.verbose:
 410         print("Unable to map to netlogon DNS update: %s" % d)
 411
 412
 413 # get the list of DNS entries we should have
 414 if opts.update_list:
 415     dns_update_list = opts.update_list
 416 else:
 417     dns_update_list = lp.private_path('dns_update_list')
 418
 419 # use our private krb5.conf to avoid problems with the wrong domain
 420 # bind9 nsupdate wants the default domain set
 421 krb5conf = lp.private_path('krb5.conf')
 422 os.environ['KRB5_CONFIG'] = krb5conf
 423
 424 file = open(dns_update_list, "r")
 425
 426 samdb = SamDB(url=lp.samdb_url(), session_info=system_session(), lp=lp)
 427
 428 # get the substitution dictionary
 429 sub_vars = get_subst_vars(samdb)
 430
 431 # build up a list of update commands to pass to nsupdate
 432 update_list = []
 433 dns_list = []
 434
 435 dup_set = set()
 436
 437 # read each line, and check that the DNS name exists
 438 for line in file:
 439     line = line.strip()
 440     if line == '' or line[0] == "#":
 441         continue
 442     d = parse_dns_line(line, sub_vars)
 443     if d is None:
 444         continue
 445     if d.type == 'A' and len(IP4s) == 0:
 446         continue
 447     if d.type == 'AAAA' and len(IP6s) == 0:
 448         continue
 449     if str(d) not in dup_set:
 450         dns_list.append(d)
 451         dup_set.add(str(d))
 452
 453 # now expand the entries, if any are A record with ip set to $IP
 454 # then replace with multiple entries, one for each interface IP
 455 for d in dns_list:
 456     if d.ip != "$IP":
 457         continue
 458     if d.type == 'A':
 459         d.ip = IP4s[0]
 460         for i in range(len(IP4s)-1):
 461             d2 = dnsobj(str(d))
 462             d2.ip = IP4s[i+1]
 463             dns_list.append(d2)
 464     if d.type == 'AAAA':
 465         d.ip = IP6s[0]
 466         for i in range(len(IP6s)-1):
 467             d2 = dnsobj(str(d))
 468             d2.ip = IP6s[i+1]
 469             dns_list.append(d2)
 470
 471 # now check if the entries already exist on the DNS server
 472 for d in dns_list:
 473     if opts.all_names or not check_dns_name(d):
 474         update_list.append(d)
 475
 476 if len(update_list) == 0:
 477     if opts.verbose:
 478         print "No DNS updates needed"
 479     sys.exit(0)
 480
 481 # get our krb5 creds
 482 if not opts.nocreds:
 483     get_credentials(lp)
 484
 485 # ask nsupdate to add entries as needed
 486 for d in update_list:
 487     if am_rodc:
 488         if d.name.lower() == domain.lower():
 489             continue
 490         if not d.type in [ 'A', 'AAAA' ]:
 491             call_rodc_update(d)
 492         else:
 493             call_nsupdate(d)
 494     else:
 495         call_nsupdate(d)
 496
 497 # delete the ccache if we created it
 498 if ccachename is not None:
 499     os.unlink(ccachename)
 500
 501 if error_count != 0:
 502     print("Failed update of %u entries" % error_count)
 503 sys.exit(error_count)