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 parser.add_option("--no-substiutions", dest='nosubs', action='store_true', help="don't try and expands variables in file specified by --update-list")
  69
  70 creds = None
  71 ccachename = None
  72
  73 opts, args = parser.parse_args()
  74
  75 if len(args) != 0:
  76     parser.print_usage()
  77     sys.exit(1)
  78
  79 lp = sambaopts.get_loadparm()
  80
  81 domain = lp.get("realm")
  82 host = lp.get("netbios name")
  83 if opts.all_interfaces:
  84     all_interfaces = True
  85 else:
  86     all_interfaces = False
  87
  88 IPs = samba.interface_ips(lp, all_interfaces)
  89 nsupdate_cmd = lp.get('nsupdate command')
  90
  91 if len(IPs) == 0:
  92     print "No IP interfaces - skipping DNS updates"
  93     sys.exit(0)
  94
  95 IP6s = []
  96 IP4s = []
  97 for i in IPs:
  98     if i.find(':') != -1:
  99         IP6s.append(i)
 100     else:
 101         IP4s.append(i)
 102
 103
 104 if opts.verbose:
 105     print "IPs: %s" % IPs
 106
 107
 108 def get_credentials(lp):
 109     """# get credentials if we haven't got them already."""
 110     from samba import credentials
 111     global ccachename, creds
 112     if creds is not None:
 113         return
 114     creds = credentials.Credentials()
 115     creds.guess(lp)
 116     creds.set_machine_account(lp)
 117     creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
 118     (tmp_fd, ccachename) = tempfile.mkstemp()
 119     creds.get_named_ccache(lp, ccachename)
 120
 121
 122 class dnsobj(object):
 123     """an object to hold a parsed DNS line"""
 124
 125     def __init__(self, string_form):
 126         list = string_form.split()
 127         if len(list) < 3:
 128             raise Exception("Invalid DNS entry %r" % string_form)
 129         self.dest = None
 130         self.port = None
 131         self.ip = None
 132         self.existing_port = None
 133         self.existing_weight = None
 134         self.type = list[0]
 135         self.name = list[1].lower()
 136         if self.type == 'SRV':
 137             if len(list) < 4:
 138                 raise Exception("Invalid DNS entry %r" % string_form)
 139             self.dest = list[2].lower()
 140             self.port = list[3]
 141         elif self.type in ['A', 'AAAA']:
 142             self.ip   = list[2] # usually $IP, which gets replaced
 143         elif self.type == 'CNAME':
 144             self.dest = list[2].lower()
 145         elif self.type == 'NS':
 146             self.dest = list[2].lower()
 147         else:
 148             raise Exception("Received unexpected DNS reply of type %s" % self.type)
 149
 150     def __str__(self):
 151         if d.type == "A":
 152             return "%s %s %s" % (self.type, self.name, self.ip)
 153         if d.type == "AAAA":
 154             return "%s %s %s" % (self.type, self.name, self.ip)
 155         if d.type == "SRV":
 156             return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
 157         if d.type == "CNAME":
 158             return "%s %s %s" % (self.type, self.name, self.dest)
 159         if d.type == "NS":
 160             return "%s %s %s" % (self.type, self.name, self.dest)
 161
 162
 163 def parse_dns_line(line, sub_vars):
 164     """parse a DNS line from."""
 165     if line.startswith("SRV _ldap._tcp.pdc._msdcs.") and not samdb.am_pdc():
 166         if opts.verbose:
 167             print "Skipping PDC entry (%s) as we are not a PDC" % line
 168         return None
 169     subline = samba.substitute_var(line, sub_vars)
 170     return dnsobj(subline)
 171
 172
 173 def hostname_match(h1, h2):
 174     """see if two hostnames match."""
 175     h1 = str(h1)
 176     h2 = str(h2)
 177     return h1.lower().rstrip('.') == h2.lower().rstrip('.')
 178
 179
 180 def check_dns_name(d):
 181     """check that a DNS entry exists."""
 182     normalised_name = d.name.rstrip('.') + '.'
 183     if opts.verbose:
 184         print "Looking for DNS entry %s as %s" % (d, normalised_name)
 185
 186     if opts.use_file is not None:
 187         try:
 188             dns_file = open(opts.use_file, "r")
 189         except IOError:
 190             return False
 191
 192         for line in dns_file:
 193             line = line.strip()
 194             if line == '' or line[0] == "#":
 195                 continue
 196             if line.lower() == str(d).lower():
 197                 return True
 198         return False
 199
 200     resolver = dns.resolver.Resolver()
 201     if d.type == "NS":
 202         # we need to lookup the nameserver for the parent domain,
 203         # and use that to check the NS record
 204         parent_domain = '.'.join(normalised_name.split('.')[1:])
 205         try:
 206             ans = resolver.query(parent_domain, 'NS')
 207         except dns.exception.DNSException:
 208             if opts.verbose:
 209                 print "Failed to find parent NS for %s" % d
 210             return False
 211         nameservers = set()
 212         for i in range(len(ans)):
 213             try:
 214                 ns = resolver.query(str(ans[i]), 'A')
 215             except dns.exception.DNSException:
 216                 continue
 217             for j in range(len(ns)):
 218                 nameservers.add(str(ns[j]))
 219         d.nameservers = list(nameservers)
 220
 221     try:
 222         if getattr(d, 'nameservers', None):
 223             resolver.nameservers = list(d.nameservers)
 224         ans = resolver.query(normalised_name, d.type)
 225     except dns.exception.DNSException:
 226         if opts.verbose:
 227             print "Failed to find DNS entry %s" % d
 228         return False
 229     if d.type in ['A', 'AAAA']:
 230         # we need to be sure that our IP is there
 231         for rdata in ans:
 232             if str(rdata) == str(d.ip):
 233                 return True
 234     elif d.type == 'CNAME':
 235         for i in range(len(ans)):
 236             if hostname_match(ans[i].target, d.dest):
 237                 return True
 238     elif d.type == 'NS':
 239         for i in range(len(ans)):
 240             if hostname_match(ans[i].target, d.dest):
 241                 return True
 242     elif d.type == 'SRV':
 243         for rdata in ans:
 244             if opts.verbose:
 245                 print "Checking %s against %s" % (rdata, d)
 246             if hostname_match(rdata.target, d.dest):
 247                 if str(rdata.port) == str(d.port):
 248                     return True
 249                 else:
 250                     d.existing_port     = str(rdata.port)
 251                     d.existing_weight = str(rdata.weight)
 252
 253     if opts.verbose:
 254         print "Failed to find matching DNS entry %s" % d
 255
 256     return False
 257
 258
 259 def get_subst_vars(samdb):
 260     """get the list of substitution vars."""
 261     global lp, am_rodc
 262     vars = {}
 263
 264     vars['DNSDOMAIN'] = samdb.domain_dns_name()
 265     vars['DNSFOREST'] = samdb.forest_dns_name()
 266     vars['HOSTNAME']  = samdb.host_dns_name()
 267     vars['NTDSGUID']  = samdb.get_ntds_GUID()
 268     vars['SITE']      = samdb.server_site_name()
 269     res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
 270     guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
 271     vars['DOMAINGUID'] = guid
 272     am_rodc = samdb.am_rodc()
 273
 274     return vars
 275
 276
 277 def call_nsupdate(d):
 278     """call nsupdate for an entry."""
 279     global ccachename, nsupdate_cmd, krb5conf
 280
 281     if opts.verbose:
 282         print "Calling nsupdate for %s" % d
 283
 284     if opts.use_file is not None:
 285         try:
 286             rfile = open(opts.use_file, 'r+')
 287         except IOError:
 288             # Perhaps create it
 289             rfile = open(opts.use_file, 'w+')
 290             # Open it for reading again, in case someone else got to it first
 291             rfile = open(opts.use_file, 'r+')
 292         fcntl.lockf(rfile, fcntl.LOCK_EX)
 293         (file_dir, file_name) = os.path.split(opts.use_file)
 294         (tmp_fd, tmpfile) = tempfile.mkstemp(dir=file_dir, prefix=file_name, suffix="XXXXXX")
 295         wfile = os.fdopen(tmp_fd, 'a')
 296         rfile.seek(0)
 297         for line in rfile:
 298             wfile.write(line)
 299         wfile.write(str(d)+"\n")
 300         os.rename(tmpfile, opts.use_file)
 301         fcntl.lockf(rfile, fcntl.LOCK_UN)
 302         return
 303
 304     normalised_name = d.name.rstrip('.') + '.'
 305
 306     (tmp_fd, tmpfile) = tempfile.mkstemp()
 307     f = os.fdopen(tmp_fd, 'w')
 308     if getattr(d, 'nameservers', None):
 309         f.write('server %s\n' % d.nameservers[0])
 310     if d.type == "A":
 311         f.write("update add %s %u A %s\n" % (normalised_name, default_ttl, d.ip))
 312     if d.type == "AAAA":
 313         f.write("update add %s %u AAAA %s\n" % (normalised_name, default_ttl, d.ip))
 314     if d.type == "SRV":
 315         if d.existing_port is not None:
 316             f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
 317                                                            d.existing_port, d.dest))
 318         f.write("update add %s %u SRV 0 100 %s %s\n" % (normalised_name, default_ttl, d.port, d.dest))
 319     if d.type == "CNAME":
 320         f.write("update add %s %u CNAME %s\n" % (normalised_name, default_ttl, d.dest))
 321     if d.type == "NS":
 322         f.write("update add %s %u NS %s\n" % (normalised_name, default_ttl, d.dest))
 323     if opts.verbose:
 324         f.write("show\n")
 325     f.write("send\n")
 326     f.close()
 327
 328     global error_count
 329     if ccachename:
 330         os.environ["KRB5CCNAME"] = ccachename
 331     try:
 332         cmd = nsupdate_cmd[:]
 333         cmd.append(tmpfile)
 334         env = {}
 335         if krb5conf:
 336             env["KRB5_CONFIG"] = krb5conf
 337         if ccachename:
 338             env["KRB5CCNAME"] = ccachename
 339         ret = subprocess.call(cmd, shell=False, env=env)
 340         if ret != 0:
 341             if opts.fail_immediately:
 342                 if opts.verbose:
 343                     print("Failed update with %s" % tmpfile)
 344                 sys.exit(1)
 345             error_count = error_count + 1
 346             if opts.verbose:
 347                 print("Failed nsupdate: %d" % ret)
 348     except Exception, estr:
 349         if opts.fail_immediately:
 350             sys.exit(1)
 351         error_count = error_count + 1
 352         if opts.verbose:
 353             print("Failed nsupdate: %s : %s" % (str(d), estr))
 354     os.unlink(tmpfile)
 355
 356
 357
 358 def rodc_dns_update(d, t):
 359     '''a single DNS update via the RODC netlogon call'''
 360     global sub_vars
 361
 362     if opts.verbose:
 363         print "Calling netlogon RODC update for %s" % d
 364
 365     typemap = {
 366         netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
 367         netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
 368         netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
 369         netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
 370         netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
 371         netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
 372         netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
 373         }
 374
 375     w = winbind.winbind("irpc:winbind_server", lp)
 376     dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
 377     dns_names.count = 1
 378     name = netlogon.NL_DNS_NAME_INFO()
 379     name.type = t
 380     name.dns_domain_info_type = typemap[t]
 381     name.priority = 0
 382     name.weight   = 0
 383     if d.port is not None:
 384         name.port = int(d.port)
 385     name.dns_register = True
 386     dns_names.names = [ name ]
 387     site_name = sub_vars['SITE'].decode('utf-8')
 388
 389     global error_count
 390
 391     try:
 392         ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
 393         if ret_names.names[0].status != 0:
 394             print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
 395             error_count = error_count + 1
 396     except RuntimeError, reason:
 397         print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
 398         error_count = error_count + 1
 399
 400     if error_count != 0 and opts.fail_immediately:
 401         sys.exit(1)
 402
 403
 404 def call_rodc_update(d):
 405     '''RODCs need to use the netlogon API for nsupdate'''
 406     global lp, sub_vars
 407
 408     # we expect failure for 3268 if we aren't a GC
 409     if d.port is not None and int(d.port) == 3268:
 410         return
 411
 412     # map the DNS request to a netlogon update type
 413     map = {
 414         netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
 415         netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
 416         netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
 417         netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 418         netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 419         netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
 420         netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
 421         }
 422
 423     for t in map:
 424         subname = samba.substitute_var(map[t], sub_vars)
 425         if subname.lower() == d.name.lower():
 426             # found a match - do the update
 427             rodc_dns_update(d, t)
 428             return
 429     if opts.verbose:
 430         print("Unable to map to netlogon DNS update: %s" % d)
 431
 432
 433 # get the list of DNS entries we should have
 434 if opts.update_list:
 435     dns_update_list = opts.update_list
 436 else:
 437     dns_update_list = lp.private_path('dns_update_list')
 438
 439 # use our private krb5.conf to avoid problems with the wrong domain
 440 # bind9 nsupdate wants the default domain set
 441 krb5conf = lp.private_path('krb5.conf')
 442 os.environ['KRB5_CONFIG'] = krb5conf
 443
 444 file = open(dns_update_list, "r")
 445
 446 if opts.nosubs:
 447     sub_vars = {}
 448 else:
 449     samdb = SamDB(url=lp.samdb_url(), session_info=system_session(), lp=lp)
 450
 451     # get the substitution dictionary
 452     sub_vars = get_subst_vars(samdb)
 453
 454 # build up a list of update commands to pass to nsupdate
 455 update_list = []
 456 dns_list = []
 457
 458 dup_set = set()
 459
 460 # read each line, and check that the DNS name exists
 461 for line in file:
 462     line = line.strip()
 463     if line == '' or line[0] == "#":
 464         continue
 465     d = parse_dns_line(line, sub_vars)
 466     if d is None:
 467         continue
 468     if d.type == 'A' and len(IP4s) == 0:
 469         continue
 470     if d.type == 'AAAA' and len(IP6s) == 0:
 471         continue
 472     if str(d) not in dup_set:
 473         dns_list.append(d)
 474         dup_set.add(str(d))
 475
 476 # now expand the entries, if any are A record with ip set to $IP
 477 # then replace with multiple entries, one for each interface IP
 478 for d in dns_list:
 479     if d.ip != "$IP":
 480         continue
 481     if d.type == 'A':
 482         d.ip = IP4s[0]
 483         for i in range(len(IP4s)-1):
 484             d2 = dnsobj(str(d))
 485             d2.ip = IP4s[i+1]
 486             dns_list.append(d2)
 487     if d.type == 'AAAA':
 488         d.ip = IP6s[0]
 489         for i in range(len(IP6s)-1):
 490             d2 = dnsobj(str(d))
 491             d2.ip = IP6s[i+1]
 492             dns_list.append(d2)
 493
 494 # now check if the entries already exist on the DNS server
 495 for d in dns_list:
 496     if opts.all_names or not check_dns_name(d):
 497         update_list.append(d)
 498
 499 if len(update_list) == 0:
 500     if opts.verbose:
 501         print "No DNS updates needed"
 502     sys.exit(0)
 503
 504 # get our krb5 creds
 505 if not opts.nocreds:
 506     get_credentials(lp)
 507
 508 # ask nsupdate to add entries as needed
 509 for d in update_list:
 510     if am_rodc:
 511         if d.name.lower() == domain.lower():
 512             continue
 513         if not d.type in [ 'A', 'AAAA' ]:
 514             call_rodc_update(d)
 515         else:
 516             call_nsupdate(d)
 517     else:
 518         call_nsupdate(d)
 519
 520 # delete the ccache if we created it
 521 if ccachename is not None:
 522     os.unlink(ccachename)
 523
 524 if error_count != 0:
 525     print("Failed update of %u entries" % error_count)
 526 sys.exit(error_count)