source4/scripting/bin/samba_dnsupdate

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