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         if len(list) < 3:
 129             raise Exception("Invalid DNS entry %r" % string_form)
 130         self.dest = None
 131         self.port = None
 132         self.ip = None
 133         self.existing_port = None
 134         self.existing_weight = None
 135         self.type = list[0]
 136         self.name = list[1].lower()
 137         if self.type == 'SRV':
 138             if len(list) < 4:
 139                 raise Exception("Invalid DNS entry %r" % string_form)
 140             self.dest = list[2].lower()
 141             self.port = list[3]
 142         elif self.type in ['A', 'AAAA']:
 143             self.ip   = list[2] # usually $IP, which gets replaced
 144         elif self.type == 'CNAME':
 145             self.dest = list[2].lower()
 146         elif self.type == 'NS':
 147             self.dest = list[2].lower()
 148         else:
 149             raise Exception("Received unexpected DNS reply of type %s" % self.type)
 150
 151     def __str__(self):
 152         if d.type == "A":     return "%s %s %s" % (self.type, self.name, self.ip)
 153         if d.type == "AAAA":  return "%s %s %s" % (self.type, self.name, self.ip)
 154         if d.type == "SRV":   return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
 155         if d.type == "CNAME": return "%s %s %s" % (self.type, self.name, self.dest)
 156         if d.type == "NS":    return "%s %s %s" % (self.type, self.name, self.dest)
 157
 158
 159 def parse_dns_line(line, sub_vars):
 160     """parse a DNS line from."""
 161     if line.startswith("SRV _ldap._tcp.pdc._msdcs.") and not samdb.am_pdc():
 162         if opts.verbose:
 163             print "Skipping PDC entry (%s) as we are not a PDC" % line
 164         return None
 165     subline = samba.substitute_var(line, sub_vars)
 166     return dnsobj(subline)
 167
 168
 169 def hostname_match(h1, h2):
 170     """see if two hostnames match."""
 171     h1 = str(h1)
 172     h2 = str(h2)
 173     return h1.lower().rstrip('.') == h2.lower().rstrip('.')
 174
 175
 176 def check_dns_name(d):
 177     """check that a DNS entry exists."""
 178     normalised_name = d.name.rstrip('.') + '.'
 179     if opts.verbose:
 180         print "Looking for DNS entry %s as %s" % (d, normalised_name)
 181
 182     if opts.use_file is not None:
 183         try:
 184             dns_file = open(opts.use_file, "r")
 185         except IOError:
 186             return False
 187
 188         for line in dns_file:
 189             line = line.strip()
 190             if line == '' or line[0] == "#":
 191                 continue
 192             if line.lower() == str(d).lower():
 193                 return True
 194         return False
 195
 196     resolver = dns.resolver.Resolver()
 197     if d.type == "NS":
 198         # we need to lookup the nameserver for the parent domain,
 199         # and use that to check the NS record
 200         parent_domain = '.'.join(normalised_name.split('.')[1:])
 201         try:
 202             ans = resolver.query(parent_domain, 'NS')
 203         except dns.exception.DNSException:
 204             if opts.verbose:
 205                 print "Failed to find parent NS for %s" % d
 206             return False
 207         nameservers = set()
 208         for i in range(len(ans)):
 209             try:
 210                 ns = resolver.query(str(ans[i]), 'A')
 211             except dns.exception.DNSException:
 212                 continue
 213             for j in range(len(ns)):
 214                 nameservers.add(str(ns[j]))
 215         d.nameservers = list(nameservers)
 216
 217     try:
 218         if getattr(d, 'nameservers', None):
 219             resolver.nameservers = list(d.nameservers)
 220         ans = resolver.query(normalised_name, d.type)
 221     except dns.exception.DNSException:
 222         if opts.verbose:
 223             print "Failed to find DNS entry %s" % d
 224         return False
 225     if d.type in ['A', 'AAAA']:
 226         # we need to be sure that our IP is there
 227         for rdata in ans:
 228             if str(rdata) == str(d.ip):
 229                 return True
 230     elif d.type == 'CNAME':
 231         for i in range(len(ans)):
 232             if hostname_match(ans[i].target, d.dest):
 233                 return True
 234     elif d.type == 'NS':
 235         for i in range(len(ans)):
 236             if hostname_match(ans[i].target, d.dest):
 237                 return True
 238     elif d.type == 'SRV':
 239         for rdata in ans:
 240             if opts.verbose:
 241                 print "Checking %s against %s" % (rdata, d)
 242             if hostname_match(rdata.target, d.dest):
 243                 if str(rdata.port) == str(d.port):
 244                     return True
 245                 else:
 246                     d.existing_port     = str(rdata.port)
 247                     d.existing_weight = str(rdata.weight)
 248
 249     if opts.verbose:
 250         print "Failed to find matching DNS entry %s" % d
 251
 252     return False
 253
 254
 255 def get_subst_vars(samdb):
 256     """get the list of substitution vars."""
 257     global lp, am_rodc
 258     vars = {}
 259
 260     vars['DNSDOMAIN'] = samdb.domain_dns_name()
 261     vars['DNSFOREST'] = samdb.forest_dns_name()
 262     vars['HOSTNAME']  = samdb.host_dns_name()
 263     vars['NTDSGUID']  = samdb.get_ntds_GUID()
 264     vars['SITE']      = samdb.server_site_name()
 265     res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
 266     guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
 267     vars['DOMAINGUID'] = guid
 268     am_rodc = samdb.am_rodc()
 269
 270     return vars
 271
 272
 273 def call_nsupdate(d):
 274     """call nsupdate for an entry."""
 275     global ccachename, nsupdate_cmd
 276
 277     if opts.verbose:
 278         print "Calling nsupdate for %s" % d
 279
 280     if opts.use_file is not None:
 281         wfile = open(opts.use_file, 'a')
 282         fcntl.lockf(wfile, fcntl.LOCK_EX)
 283         wfile.write(str(d)+"\n")
 284         fcntl.lockf(wfile, fcntl.LOCK_UN)
 285         return
 286
 287     normalised_name = d.name.rstrip('.') + '.'
 288
 289     (tmp_fd, tmpfile) = tempfile.mkstemp()
 290     f = os.fdopen(tmp_fd, 'w')
 291     if getattr(d, 'nameservers', None):
 292         f.write('server %s\n' % d.nameservers[0])
 293     if d.type == "A":
 294         f.write("update add %s %u A %s\n" % (normalised_name, default_ttl, d.ip))
 295     if d.type == "AAAA":
 296         f.write("update add %s %u AAAA %s\n" % (normalised_name, default_ttl, d.ip))
 297     if d.type == "SRV":
 298         if d.existing_port is not None:
 299             f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
 300                                                            d.existing_port, d.dest))
 301         f.write("update add %s %u SRV 0 100 %s %s\n" % (normalised_name, default_ttl, d.port, d.dest))
 302     if d.type == "CNAME":
 303         f.write("update add %s %u CNAME %s\n" % (normalised_name, default_ttl, d.dest))
 304     if d.type == "NS":
 305         f.write("update add %s %u NS %s\n" % (normalised_name, default_ttl, d.dest))
 306     if opts.verbose:
 307         f.write("show\n")
 308     f.write("send\n")
 309     f.close()
 310
 311     global error_count
 312     if ccachename:
 313         os.environ["KRB5CCNAME"] = ccachename
 314     try:
 315         cmd = nsupdate_cmd[:]
 316         cmd.append(tmpfile)
 317         if ccachename:
 318             env = {"KRB5CCNAME": ccachename}
 319         else:
 320             env = {}
 321         ret = subprocess.call(cmd, shell=False, env=env)
 322         if ret != 0:
 323             if opts.fail_immediately:
 324                 if opts.verbose:
 325                     print("Failed update with %s" % tmpfile)
 326                 sys.exit(1)
 327             error_count = error_count + 1
 328             if opts.verbose:
 329                 print("Failed nsupdate: %d" % ret)
 330     except Exception, estr:
 331         if opts.fail_immediately:
 332             sys.exit(1)
 333         error_count = error_count + 1
 334         if opts.verbose:
 335             print("Failed nsupdate: %s : %s" % (str(d), estr))
 336     os.unlink(tmpfile)
 337
 338
 339
 340 def rodc_dns_update(d, t):
 341     '''a single DNS update via the RODC netlogon call'''
 342     global sub_vars
 343
 344     if opts.verbose:
 345         print "Calling netlogon RODC update for %s" % d
 346
 347     typemap = {
 348         netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
 349         netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
 350         netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
 351         netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
 352         netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
 353         netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
 354         netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
 355         }
 356
 357     w = winbind.winbind("irpc:winbind_server", lp)
 358     dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
 359     dns_names.count = 1
 360     name = netlogon.NL_DNS_NAME_INFO()
 361     name.type = t
 362     name.dns_domain_info_type = typemap[t]
 363     name.priority = 0
 364     name.weight   = 0
 365     if d.port is not None:
 366         name.port = int(d.port)
 367     name.dns_register = True
 368     dns_names.names = [ name ]
 369     site_name = sub_vars['SITE'].decode('utf-8')
 370
 371     global error_count
 372
 373     try:
 374         ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
 375         if ret_names.names[0].status != 0:
 376             print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
 377             error_count = error_count + 1
 378     except RuntimeError, reason:
 379         print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
 380         error_count = error_count + 1
 381
 382     if error_count != 0 and opts.fail_immediately:
 383         sys.exit(1)
 384
 385
 386 def call_rodc_update(d):
 387     '''RODCs need to use the netlogon API for nsupdate'''
 388     global lp, sub_vars
 389
 390     # we expect failure for 3268 if we aren't a GC
 391     if d.port is not None and int(d.port) == 3268:
 392         return
 393
 394     # map the DNS request to a netlogon update type
 395     map = {
 396         netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
 397         netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
 398         netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
 399         netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 400         netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 401         netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
 402         netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
 403         }
 404
 405     for t in map:
 406         subname = samba.substitute_var(map[t], sub_vars)
 407         if subname.lower() == d.name.lower():
 408             # found a match - do the update
 409             rodc_dns_update(d, t)
 410             return
 411     if opts.verbose:
 412         print("Unable to map to netlogon DNS update: %s" % d)
 413
 414
 415 # get the list of DNS entries we should have
 416 if opts.update_list:
 417     dns_update_list = opts.update_list
 418 else:
 419     dns_update_list = lp.private_path('dns_update_list')
 420
 421 # use our private krb5.conf to avoid problems with the wrong domain
 422 # bind9 nsupdate wants the default domain set
 423 krb5conf = lp.private_path('krb5.conf')
 424 os.environ['KRB5_CONFIG'] = krb5conf
 425
 426 file = open(dns_update_list, "r")
 427
 428 samdb = SamDB(url=lp.samdb_url(), session_info=system_session(), lp=lp)
 429
 430 # get the substitution dictionary
 431 sub_vars = get_subst_vars(samdb)
 432
 433 # build up a list of update commands to pass to nsupdate
 434 update_list = []
 435 dns_list = []
 436
 437 dup_set = set()
 438
 439 # read each line, and check that the DNS name exists
 440 for line in file:
 441     line = line.strip()
 442     if line == '' or line[0] == "#":
 443         continue
 444     d = parse_dns_line(line, sub_vars)
 445     if d is None:
 446         continue
 447     if d.type == 'A' and len(IP4s) == 0:
 448         continue
 449     if d.type == 'AAAA' and len(IP6s) == 0:
 450         continue
 451     if str(d) not in dup_set:
 452         dns_list.append(d)
 453         dup_set.add(str(d))
 454
 455 # now expand the entries, if any are A record with ip set to $IP
 456 # then replace with multiple entries, one for each interface IP
 457 for d in dns_list:
 458     if d.ip != "$IP":
 459         continue
 460     if d.type == 'A':
 461         d.ip = IP4s[0]
 462         for i in range(len(IP4s)-1):
 463             d2 = dnsobj(str(d))
 464             d2.ip = IP4s[i+1]
 465             dns_list.append(d2)
 466     if d.type == 'AAAA':
 467         d.ip = IP6s[0]
 468         for i in range(len(IP6s)-1):
 469             d2 = dnsobj(str(d))
 470             d2.ip = IP6s[i+1]
 471             dns_list.append(d2)
 472
 473 # now check if the entries already exist on the DNS server
 474 for d in dns_list:
 475     if opts.all_names or not check_dns_name(d):
 476         update_list.append(d)
 477
 478 if len(update_list) == 0:
 479     if opts.verbose:
 480         print "No DNS updates needed"
 481     sys.exit(0)
 482
 483 # get our krb5 creds
 484 if not opts.nocreds:
 485     get_credentials(lp)
 486
 487 # ask nsupdate to add entries as needed
 488 for d in update_list:
 489     if am_rodc:
 490         if d.name.lower() == domain.lower():
 491             continue
 492         if not d.type in [ 'A', 'AAAA' ]:
 493             call_rodc_update(d)
 494         else:
 495             call_nsupdate(d)
 496     else:
 497         call_nsupdate(d)
 498
 499 # delete the ccache if we created it
 500 if ccachename is not None:
 501     os.unlink(ccachename)
 502
 503 if error_count != 0:
 504     print("Failed update of %u entries" % error_count)
 505 sys.exit(error_count)