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