/mandos/trunk : revision 42

6

# This program is partly derived from an example program for an Avahi

7

# service publisher, downloaded from

8

# <http://avahi.org/wiki/PythonPublishExample>. This includes the

9

# methods "add" and "remove" in the "AvahiService" class, the

10

# "server_state_changed" and "entry_group_state_changed" functions,

11

# and some lines in "main".

9

# following functions: "AvahiService.add", "AvahiService.remove",

10

# "server_state_changed", "entry_group_state_changed", and some lines

11

# in "main".

12

#

13

# Everything else is

14

61

from dbus.mainloop.glib import DBusGMainLoop

62

import ctypes

63

64

version = "1.0"

64

# Brief description of the operation of this program:

65

#

66

# This server announces itself as a Zeroconf service. Connecting

67

# clients use the TLS protocol, with the unusual quirk that this

68

# server program acts as a TLS "client" while a connecting client acts

69

# as a TLS "server". The client (acting as a TLS "server") must

70

# supply an OpenPGP certificate, and the fingerprint of this

71

# certificate is used by this server to look up (in a list read from a

72

# file at start time) which binary blob to give the client. No other

73

# authentication or authorization is done by this server.

74

65

75

66

76

logger = logging.Logger('mandos')

67

77

syslogger = logging.handlers.SysLogHandler\

68

(facility = logging.handlers.SysLogHandler.LOG_DAEMON,

69

address = "/dev/log")

78

(facility = logging.handlers.SysLogHandler.LOG_DAEMON)

70

79

syslogger.setFormatter(logging.Formatter\

71

('Mandos: %(levelname)s: %(message)s'))

80

('%(levelname)s: %(message)s'))

72

81

logger.addHandler(syslogger)

82

del syslogger

73

83

74

console = logging.StreamHandler()

75

console.setFormatter(logging.Formatter('%(name)s: %(levelname)s:'

76

' %(message)s'))

77

logger.addHandler(console)

78

84

79

85

class AvahiError(Exception):

80

86

def __init__(self, value):

90

96

91

97

92

98

class AvahiService(object):

93

"""An Avahi (Zeroconf) service.

94

Attributes:

99

"""

95

100

interface: integer; avahi.IF_UNSPEC or an interface index.

96

101

Used to optionally bind to the specified interface.

97

name: string; Example: 'Mandos'

98

type: string; Example: '_mandos._tcp'.

99

See <http://www.dns-sd.org/ServiceTypes.html>

100

port: integer; what port to announce

101

TXT: list of strings; TXT record for the service

102

domain: string; Domain to publish on, default to .local if empty.

103

host: string; Host to publish records for, default is localhost

104

max_renames: integer; maximum number of renames

105

rename_count: integer; counter so we only rename after collisions

106

a sensible number of times

102

name = string; Example: "Mandos"

103

type = string; Example: "_mandos._tcp".

104

See <http://www.dns-sd.org/ServiceTypes.html>

105

port = integer; what port to announce

106

TXT = list of strings; TXT record for the service

107

domain = string; Domain to publish on, default to .local if empty.

108

host = string; Host to publish records for, default to localhost

109

if empty.

110

max_renames = integer; maximum number of renames

111

rename_count = integer; counter so we only rename after collisions

112

a sensible number of times

107

113

"""

108

114

def __init__(self, interface = avahi.IF_UNSPEC, name = None,

109

115

type = None, port = None, TXT = None, domain = "",

110

host = "", max_renames = 32768):

116

host = "", max_renames = 12):

117

"""An Avahi (Zeroconf) service. """

111

118

self.interface = interface

112

119

self.name = name

113

120

self.type = type

126

133

u" retries, exiting.", rename_count)

127

134

raise AvahiServiceError("Too many renames")

128

135

name = server.GetAlternativeServiceName(name)

129

logger.error(u"Changing name to %r ...", name)

130

syslogger.setFormatter(logging.Formatter\

131

('Mandos (%s): %%(levelname)s:'

132

' %%(message)s' % name))

136

logger.notice(u"Changing name to %r ...", name)

133

137

self.remove()

134

138

self.add()

135

139

self.rename_count += 1

171

175

fingerprint: string (40 or 32 hexadecimal digits); used to

172

176

uniquely identify the client

173

177

secret: bytestring; sent verbatim (over TLS) to client

174

host: string; available for use by the checker command

178

fqdn: string (FQDN); available for use by the checker command

175

179

created: datetime.datetime(); object creation, not client host

176

180

last_checked_ok: datetime.datetime() or None if not yet checked OK

177

181

timeout: datetime.timedelta(); How long from last_checked_ok

217

221

interval = property(lambda self: self._interval,

218

222

_set_interval)

219

223

del _set_interval

220

def __init__(self, name = None, stop_hook=None, config={}):

221

"""Note: the 'checker' key in 'config' sets the

222

'checker_command' attribute and *not* the 'checker'

223

attribute."""

224

def __init__(self, name=None, stop_hook=None, fingerprint=None,

225

secret=None, secfile=None, fqdn=None, timeout=None,

226

interval=-1, checker=None):

227

"""Note: the 'checker' argument sets the 'checker_command'

228

attribute and not the 'checker' attribute.."""

224

229

self.name = name

225

230

logger.debug(u"Creating client %r", self.name)

226

# Uppercase and remove spaces from fingerprint for later

227

# comparison purposes with return value from the fingerprint()

228

# function

229

self.fingerprint = config["fingerprint"].upper()\

230

.replace(u" ", u"")

231

# Uppercase and remove spaces from fingerprint

232

# for later comparison purposes with return value of

233

# the fingerprint() function

234

self.fingerprint = fingerprint.upper().replace(u" ", u"")

231

235

logger.debug(u" Fingerprint: %s", self.fingerprint)

232

if "secret" in config:

233

self.secret = config["secret"].decode(u"base64")

234

elif "secfile" in config:

235

sf = open(config["secfile"])

236

if secret:

237

self.secret = secret.decode(u"base64")

238

elif secfile:

239

sf = open(secfile)

236

240

self.secret = sf.read()

237

241

sf.close()

238

242

else:

239

243

raise TypeError(u"No secret or secfile for client %s"

240

244

% self.name)

241

self.host = config.get("host", "")

245

self.fqdn = fqdn

242

246

self.created = datetime.datetime.now()

243

247

self.last_checked_ok = None

244

self.timeout = string_to_delta(config["timeout"])

245

self.interval = string_to_delta(config["interval"])

248

self.timeout = string_to_delta(timeout)

249

self.interval = string_to_delta(interval)

246

250

self.stop_hook = stop_hook

247

251

self.checker = None

248

252

self.checker_initiator_tag = None

249

253

self.stop_initiator_tag = None

250

254

self.checker_callback_tag = None

251

self.check_command = config["checker"]

255

self.check_command = checker

252

256

def start(self):

253

257

"""Start this client's checker and timeout hooks"""

254

258

# Schedule a new checker to be started an 'interval' from now,

267

271

The possibility that a client might be restarted is left open,

268

272

but not currently used."""

269

273

# If this client doesn't have a secret, it is already stopped.

270

if hasattr(self, "secret") and self.secret:

271

logger.info(u"Stopping client %s", self.name)

274

if self.secret:

275

logger.debug(u"Stopping client %s", self.name)

272

276

self.secret = None

273

277

else:

274

278

return False

293

297

self.checker = None

294

298

if os.WIFEXITED(condition) \

295

299

and (os.WEXITSTATUS(condition) == 0):

296

logger.info(u"Checker for %(name)s succeeded",

297

vars(self))

300

logger.debug(u"Checker for %(name)s succeeded",

301

vars(self))

298

302

self.last_checked_ok = now

299

303

gobject.source_remove(self.stop_initiator_tag)

300

304

self.stop_initiator_tag = gobject.timeout_add\

304

308

logger.warning(u"Checker for %(name)s crashed?",

305

309

vars(self))

306

310

else:

307

logger.info(u"Checker for %(name)s failed",

308

vars(self))

311

logger.debug(u"Checker for %(name)s failed",

312

vars(self))

309

313

def start_checker(self):

310

314

"""Start a new checker subprocess if one is not running.

311

315

If a checker already exists, leave it running and do

321

325

if self.checker is None:

322

326

try:

323

327

# In case check_command has exactly one % operator

324

command = self.check_command % self.host

328

command = self.check_command % self.fqdn

325

329

except TypeError:

326

330

# Escape attributes for the shell

327

331

escaped_attrs = dict((key, re.escape(str(val)))

334

338

u' %s', self.check_command, error)

335

339

return True # Try again later

336

340

try:

337

logger.info(u"Starting checker %r for %s",

338

command, self.name)

341

logger.debug(u"Starting checker %r for %s",

342

command, self.name)

339

343

self.checker = subprocess.Popen(command,

340

344

close_fds=True,

341

345

shell=True, cwd="/")

354

358

self.checker_callback_tag = None

355

359

if getattr(self, "checker", None) is None:

356

360

return

357

logger.debug(u"Stopping checker for %(name)s", vars(self))

361

logger.debug("Stopping checker for %(name)s", vars(self))

358

362

try:

359

363

os.kill(self.checker.pid, signal.SIGTERM)

360

364

#os.sleep(0.5)

392

396

393

397

def fingerprint(openpgp):

394

398

"Convert an OpenPGP bytestring to a hexdigit fingerprint string"

399

# New empty GnuTLS certificate

400

crt = gnutls.library.types.gnutls_openpgp_crt_t()

401

gnutls.library.functions.gnutls_openpgp_crt_init\

402

(ctypes.byref(crt))

395

403

# New GnuTLS "datum" with the OpenPGP public key

396

404

datum = gnutls.library.types.gnutls_datum_t\

397

405

(ctypes.cast(ctypes.c_char_p(openpgp),

398

406

ctypes.POINTER(ctypes.c_ubyte)),

399

407

ctypes.c_uint(len(openpgp)))

400

# New empty GnuTLS certificate

401

crt = gnutls.library.types.gnutls_openpgp_crt_t()

402

gnutls.library.functions.gnutls_openpgp_crt_init\

403

(ctypes.byref(crt))

404

408

# Import the OpenPGP public key into the certificate

405

gnutls.library.functions.gnutls_openpgp_crt_import\

406

(crt, ctypes.byref(datum),

407

gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

409

ret = gnutls.library.functions.gnutls_openpgp_crt_import\

410

(crt,

411

ctypes.byref(datum),

412

gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

408

413

# New buffer for the fingerprint

409

414

buffer = ctypes.create_string_buffer(20)

410

415

buffer_length = ctypes.c_size_t()

426

431

Note: This will run in its own forked process."""

427

432

428

433

def handle(self):

429

logger.info(u"TCP connection from: %s",

434

logger.debug(u"TCP connection from: %s",

430

435

unicode(self.client_address))

431

436

session = gnutls.connection.ClientSession\

432

437

(self.request, gnutls.connection.X509Credentials())

458

463

try:

459

464

session.handshake()

460

465

except gnutls.errors.GNUTLSError, error:

461

logger.warning(u"Handshake failed: %s", error)

466

logger.debug(u"Handshake failed: %s", error)

462

467

# Do not run session.bye() here: the session is not

463

468

# established. Just abandon the request.

464

469

return

465

470

try:

466

471

fpr = fingerprint(peer_certificate(session))

467

472

except (TypeError, gnutls.errors.GNUTLSError), error:

468

logger.warning(u"Bad certificate: %s", error)

473

logger.debug(u"Bad certificate: %s", error)

469

474

session.bye()

470

475

return

471

476

logger.debug(u"Fingerprint: %s", fpr)

475

480

client = c

476

481

break

477

482

if not client:

478

logger.warning(u"Client not found for fingerprint: %s",

479

fpr)

483

logger.debug(u"Client not found for fingerprint: %s", fpr)

480

484

session.bye()

481

485

return

482

486

# Have to check if client.still_valid(), since it is possible

483

487

# that the client timed out while establishing the GnuTLS

484

488

# session.

485

489

if not client.still_valid():

486

logger.warning(u"Client %(name)s is invalid",

487

vars(client))

490

logger.debug(u"Client %(name)s is invalid", vars(client))

488

491

session.bye()

489

492

return

490

493

sent_size = 0

525

528

self.settings["interface"])

526

529

except socket.error, error:

527

530

if error[0] == errno.EPERM:

528

logger.error(u"No permission to"

529

u" bind to interface %s",

530

self.settings["interface"])

531

logger.warning(u"No permission to"

532

u" bind to interface %s",

533

self.settings["interface"])

531

534

else:

532

535

raise error

533

536

# Only bind(2) the socket if we really need to.

536

539

in6addr_any = "::"

537

540

self.server_address = (in6addr_any,

538

541

self.server_address[1])

539

elif not self.server_address[1]:

542

elif self.server_address[1] is None:

540

543

self.server_address = (self.server_address[0],

541

544

0)

542

# if self.settings["interface"]:

543

# self.server_address = (self.server_address[0],

544

# 0, # port

545

# 0, # flowinfo

546

# if_nametoindex

547

# (self.settings

548

# ["interface"]))

549

545

return super(type(self), self).server_bind()

550

546

551

547

586

582

def server_state_changed(state):

587

583

"""Derived from the Avahi example code"""

588

584

if state == avahi.SERVER_COLLISION:

589

logger.error(u"Server name collision")

585

logger.warning(u"Server name collision")

590

586

service.remove()

591

587

elif state == avahi.SERVER_RUNNING:

592

588

service.add()

631

627

return if_nametoindex(interface)

632

628

633

629

634

def daemon(nochdir = False, noclose = False):

630

def daemon(nochdir, noclose):

635

631

"""See daemon(3). Standard BSD Unix function.

636

632

This should really exist as os.daemon, but it doesn't (yet)."""

637

633

if os.fork():

639

635

os.setsid()

640

636

if not nochdir:

641

637

os.chdir("/")

642

if os.fork():

643

sys.exit()

644

638

if not noclose:

645

639

# Close all standard open file descriptors

646

640

null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)

658

652

global main_loop_started

659

653

main_loop_started = False

660

654

661

parser = OptionParser(version = "%%prog %s" % version)

655

parser = OptionParser()

662

656

parser.add_option("-i", "--interface", type="string",

663

657

metavar="IF", help="Bind to interface IF")

664

658

parser.add_option("-a", "--address", type="string",

667

661

help="Port number to receive requests on")

668

662

parser.add_option("--check", action="store_true", default=False,

669

663

help="Run self-test")

670

parser.add_option("--debug", action="store_true",

664

parser.add_option("--debug", action="store_true", default=False,

671

665

help="Debug mode; run in foreground and log to"

672

666

" terminal")

673

667

parser.add_option("--priority", type="string", help="GnuTLS"

698

692

# Parse config file for server-global settings

699

693

server_config = ConfigParser.SafeConfigParser(server_defaults)

700

694

del server_defaults

701

server_config.read(os.path.join(options.configdir, "mandos.conf"))

695

server_config.read(os.path.join(options.configdir, "server.conf"))

702

696

server_section = "server"

703

697

# Convert the SafeConfigParser object to a dict

704

698

server_settings = dict(server_config.items(server_section))

717

711

del options

718

712

# Now we have our good server settings in "server_settings"

719

713

720

debug = server_settings["debug"]

721

722

if not debug:

723

syslogger.setLevel(logging.WARNING)

724

console.setLevel(logging.WARNING)

725

726

if server_settings["servicename"] != "Mandos":

727

syslogger.setFormatter(logging.Formatter\

728

('Mandos (%s): %%(levelname)s:'

729

' %%(message)s'

730

% server_settings["servicename"]))

731

732

714

# Parse config file with clients

733

715

client_defaults = { "timeout": "1h",

734

716

"interval": "5m",

735

"checker": "fping -q -- %%(host)s",

717

"checker": "fping -q -- %%(fqdn)s",

736

718

}

737

719

client_config = ConfigParser.SafeConfigParser(client_defaults)

738

720

client_config.read(os.path.join(server_settings["configdir"],

756

738

avahi.DBUS_INTERFACE_SERVER )

757

739

# End of Avahi example code

758

740

741

debug = server_settings["debug"]

742

743

if debug:

744

console = logging.StreamHandler()

745

# console.setLevel(logging.DEBUG)

746

console.setFormatter(logging.Formatter\

747

('%(levelname)s: %(message)s'))

748

logger.addHandler(console)

749

del console

750

759

751

clients = Set()

760

752

def remove_from_clients(client):

761

753

clients.remove(client)

762

754

if not clients:

763

logger.critical(u"No clients left, exiting")

755

logger.debug(u"No clients left, exiting")

764

756

sys.exit()

765

757

766

clients.update(Set(Client(name = section,

758

clients.update(Set(Client(name=section,

767

759

stop_hook = remove_from_clients,

768

config

769

= dict(client_config.items(section)))

760

**(dict(client_config\

761

.items(section))))

770

762

for section in client_config.sections()))

771

if not clients:

772

logger.critical(u"No clients defined")

773

sys.exit(1)

774

763

775

764

if not debug:

776

logger.removeHandler(console)

777

daemon()

778

779

pidfilename = "/var/run/mandos/mandos.pid"

780

pid = os.getpid()

781

try:

782

pidfile = open(pidfilename, "w")

783

pidfile.write(str(pid) + "\n")

784

pidfile.close()

785

del pidfile

786

except IOError, err:

787

logger.error(u"Could not write %s file with PID %d",

788

pidfilename, os.getpid())

765

daemon(False, False)

789

766

790

767

def cleanup():

791

768

"Cleanup function; run on exit"

818

795

clients=clients)

819

796

# Find out what port we got

820

797

service.port = tcp_server.socket.getsockname()[1]

821

logger.info(u"Now listening on address %r, port %d, flowinfo %d,"

822

u" scope_id %d" % tcp_server.socket.getsockname())

798

logger.debug(u"Now listening on address %r, port %d, flowinfo %d,"

799

u" scope_id %d" % tcp_server.socket.getsockname())

823

800

824

801

#service.interface = tcp_server.socket.getsockname()[3]

825

802

838

815

tcp_server.handle_request\

839

816

(*args[2:], **kwargs) or True)

840

817

841

logger.debug(u"Starting main loop")

818

logger.debug("Starting main loop")

842

819

main_loop_started = True

843

820

main_loop.run()

844

821

except AvahiError, error: