/mandos/trunk : revision 22

1

#!/usr/bin/python

2

# -*- mode: python; coding: utf-8 -*-

3

#

4

# Mandos server - give out binary blobs to connecting clients.

5

#

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

# following functions: "add_service", "remove_service",

10

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

11

# in "main".

12

#

13

14

# Påhlsson.

15

#

16

# This program is free software: you can redistribute it and/or modify

17

# it under the terms of the GNU General Public License as published by

18

# the Free Software Foundation, either version 3 of the License, or

19

# (at your option) any later version.

20

#

21

# This program is distributed in the hope that it will be useful,

22

# but WITHOUT ANY WARRANTY; without even the implied warranty of

23

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

24

# GNU General Public License for more details.

25

#

26

# You should have received a copy of the GNU General Public License

27

# along with this program. If not, see <http://www.gnu.org/licenses/>.

28

#

29

# Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and

30

# <https://www.fukt.bsnet.se/~teddy/>.

31

#

2

32

3

33

from __future__ import division

4

34

21

51

import signal

22

52

from sets import Set

23

53

import subprocess

54

import atexit

55

import stat

56

import logging

57

import logging.handlers

24

58

25

59

import dbus

26

60

import gobject

28

62

from dbus.mainloop.glib import DBusGMainLoop

29

63

import ctypes

30

64

31

import logging

32

import logging.handlers

65

# Brief description of the operation of this program:

66

#

67

# This server announces itself as a Zeroconf service. Connecting

68

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

69

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

70

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

71

# supply an OpenPGP certificate, and the fingerprint of this

72

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

73

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

74

# authentication or authorization is done by this server.

33

75

34

# logghandler.setFormatter(logging.Formatter('%(levelname)s %(message)s')

35

76

36

77

logger = logging.Logger('mandos')

37

logger.addHandler(logging.handlers.SysLogHandler(facility = logging.handlers.SysLogHandler.LOG_DAEMON))

78

syslogger = logging.handlers.SysLogHandler\

79

(facility = logging.handlers.SysLogHandler.LOG_DAEMON)

80

syslogger.setFormatter(logging.Formatter\

81

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

82

logger.addHandler(syslogger)

83

del syslogger

38

84

39

85

# This variable is used to optionally bind to a specified interface.

40

86

# It is a global variable to fit in with the other variables from the

41

# Avahi server example code.

87

# Avahi example code.

42

88

serviceInterface = avahi.IF_UNSPEC

43

# From the Avahi server example code:

89

# From the Avahi example code:

44

90

serviceName = "Mandos"

45

91

serviceType = "_mandos._tcp" # http://www.dns-sd.org/ServiceTypes.html

46

92

servicePort = None # Not known at startup

107

153

_set_interval)

108

154

del _set_interval

109

155

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

110

fingerprint=None, secret=None, secfile=None, fqdn=None,

111

timeout=None, interval=-1, checker=None):

156

fingerprint=None, secret=None, secfile=None,

157

fqdn=None, timeout=None, interval=-1, checker=None):

158

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

159

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

112

160

self.name = name

113

161

# Uppercase and remove spaces from fingerprint

114

162

# for later comparison purposes with return value of

127

175

self.created = datetime.datetime.now()

128

176

self.last_seen = None

129

177

if timeout is None:

130

timeout = options.timeout

131

self.timeout = timeout

178

self.timeout = options.timeout

179

else:

180

self.timeout = string_to_delta(timeout)

132

181

if interval == -1:

133

interval = options.interval

182

self.interval = options.interval

134

183

else:

135

interval = string_to_delta(interval)

136

self.interval = interval

184

self.interval = string_to_delta(interval)

137

185

self.stop_hook = stop_hook

138

186

self.checker = None

139

187

self.checker_initiator_tag = None

141

189

self.checker_callback_tag = None

142

190

self.check_command = checker

143

191

def start(self):

144

"""Start this clients checker and timeout hooks"""

192

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

145

193

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

146

194

# and every interval from then on.

147

195

self.checker_initiator_tag = gobject.timeout_add\

157

205

"""Stop this client.

158

206

The possibility that this client might be restarted is left

159

207

open, but not currently used."""

160

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

161

self.secret = None

162

if self.stop_initiator_tag:

208

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

209

if self.secret:

210

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

211

self.secret = None

212

else:

213

return False

214

if hasattr(self, "stop_initiator_tag") \

215

and self.stop_initiator_tag:

163

216

gobject.source_remove(self.stop_initiator_tag)

164

217

self.stop_initiator_tag = None

165

if self.checker_initiator_tag:

218

if hasattr(self, "checker_initiator_tag") \

219

and self.checker_initiator_tag:

166

220

gobject.source_remove(self.checker_initiator_tag)

167

221

self.checker_initiator_tag = None

168

222

self.stop_checker()

171

225

# Do not run this again if called by a gobject.timeout_add

172

226

return False

173

227

def __del__(self):

174

# Some code duplication here and in stop()

175

if hasattr(self, "stop_initiator_tag") \

176

and self.stop_initiator_tag:

177

gobject.source_remove(self.stop_initiator_tag)

178

self.stop_initiator_tag = None

179

if hasattr(self, "checker_initiator_tag") \

180

and self.checker_initiator_tag:

181

gobject.source_remove(self.checker_initiator_tag)

182

self.checker_initiator_tag = None

183

self.stop_checker()

228

self.stop_hook = None

229

self.stop()

184

230

def checker_callback(self, pid, condition):

185

231

"""The checker has completed, so take appropriate actions."""

186

232

now = datetime.datetime.now()

233

self.checker_callback_tag = None

234

self.checker = None

187

235

if os.WIFEXITED(condition) \

188

236

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

189

237

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

193

241

self.stop_initiator_tag = gobject.timeout_add\

194

242

(self._timeout_milliseconds,

195

243

self.stop)

196

if not os.WIFEXITED(condition):

244

elif not os.WIFEXITED(condition):

197

245

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

198

246

vars(self))

199

247

else:

200

248

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

201

249

vars(self))

202

self.checker = None

203

self.checker_callback_tag = None

204

250

def start_checker(self):

205

251

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

206

252

If a checker already exists, leave it running and do

207

253

nothing."""

254

# The reason for not killing a running checker is that if we

255

# did that, then if a checker (for some reason) started

256

# running slowly and taking more than 'interval' time, the

257

# client would inevitably timeout, since no checker would get

258

# a chance to run to completion. If we instead leave running

259

# checkers alone, the checker would have to take more time

260

# than 'timeout' for the client to be declared invalid, which

261

# is as it should be.

208

262

if self.checker is None:

209

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

210

self.name)

211

263

try:

212

264

command = self.check_command % self.fqdn

213

265

except TypeError:

217

269

try:

218

270

command = self.check_command % escaped_attrs

219

271

except TypeError, error:

220

logger.critical(u'Could not format string "%s": %s',

221

self.check_command, error)

272

logger.critical(u'Could not format string "%s":'

273

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

222

274

return True # Try again later

223

275

try:

276

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

277

command, self.name)

224

278

self.checker = subprocess.\

225

279

Popen(command,

226

stdout=subprocess.PIPE,

227

280

close_fds=True, shell=True,

228

281

cwd="/")

229

self.checker_callback_tag = gobject.\

230

child_watch_add(self.checker.pid,

231

self.\

232

checker_callback)

282

self.checker_callback_tag = gobject.child_watch_add\

283

(self.checker.pid,

284

self.checker_callback)

233

285

except subprocess.OSError, error:

234

286

logger.error(u"Failed to start subprocess: %s",

235

287

error)

237

289

return True

238

290

def stop_checker(self):

239

291

"""Force the checker process, if any, to stop."""

292

if self.checker_callback_tag:

293

gobject.source_remove(self.checker_callback_tag)

294

self.checker_callback_tag = None

240

295

if not hasattr(self, "checker") or self.checker is None:

241

296

return

242

gobject.source_remove(self.checker_callback_tag)

243

self.checker_callback_tag = None

244

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

245

if self.checker.poll() is None:

246

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

297

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

298

try:

299

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

300

#os.sleep(0.5)

301

#if self.checker.poll() is None:

302

# os.kill(self.checker.pid, signal.SIGKILL)

303

except OSError, error:

304

if error.errno != errno.ESRCH:

305

raise

247

306

self.checker = None

248

307

def still_valid(self, now=None):

249

308

"""Has the timeout not yet passed for this client?"""

256

315

257

316

258

317

def peer_certificate(session):

318

"Return the peer's OpenPGP certificate as a bytestring"

259

319

# If not an OpenPGP certificate...

260

320

if gnutls.library.functions.gnutls_certificate_type_get\

261

321

(session._c_object) \

272

332

273

333

274

334

def fingerprint(openpgp):

335

"Convert an OpenPGP bytestring to a hexdigit fingerprint string"

275

336

# New empty GnuTLS certificate

276

337

crt = gnutls.library.types.gnutls_openpgp_crt_t()

277

338

gnutls.library.functions.gnutls_openpgp_crt_init\

336

397

return

337

398

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

338

399

client = None

339

for c in clients:

400

for c in self.server.clients:

340

401

if c.fingerprint == fpr:

341

402

client = c

342

403

break

443

504

444

505

445

506

def add_service():

446

"""From the Avahi server example code"""

507

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

447

508

global group, serviceName, serviceType, servicePort, serviceTXT, \

448

509

domain, host

449

510

if group is None:

468

529

469

530

470

531

def remove_service():

471

"""From the Avahi server example code"""

532

"""From the Avahi example code"""

472

533

global group

473

534

474

535

if not group is None:

476

537

477

538

478

539

def server_state_changed(state):

479

"""From the Avahi server example code"""

540

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

480

541

if state == avahi.SERVER_COLLISION:

481

542

logger.warning(u"Server name collision")

482

543

remove_service()

485

546

486

547

487

548

def entry_group_state_changed(state, error):

488

"""From the Avahi server example code"""

549

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

489

550

global serviceName, server, rename_count

490

551

491

552

logger.debug(u"state change: %i", state)

503

564

add_service()

504

565

505

566

else:

506

logger.error(u"No suitable service name found "

507

u"after %i retries, exiting.",

508

n_rename)

509

main_loop.quit()

567

logger.error(u"No suitable service name found after %i"

568

u" retries, exiting.", n_rename)

569

killme(1)

510

570

elif state == avahi.ENTRY_GROUP_FAILURE:

511

571

logger.error(u"Error in group state changed %s",

512

572

unicode(error))

513

main_loop.quit()

514

return

573

killme(1)

515

574

516

575

517

576

def if_nametoindex(interface):

533

592

return interface_index

534

593

535

594

536

if __name__ == '__main__':

595

def daemon(nochdir, noclose):

596

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

597

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

598

if os.fork():

599

sys.exit()

600

os.setsid()

601

if not nochdir:

602

os.chdir("/")

603

if not noclose:

604

# Close all standard open file descriptors

605

null = os.open("/dev/null", os.O_NOCTTY | os.O_RDWR)

606

if not stat.S_ISCHR(os.fstat(null).st_mode):

607

raise OSError(errno.ENODEV,

608

"/dev/null not a character device")

609

os.dup2(null, sys.stdin.fileno())

610

os.dup2(null, sys.stdout.fileno())

611

os.dup2(null, sys.stderr.fileno())

612

if null > 2:

613

os.close(null)

614

615

616

def killme(status = 0):

617

logger.debug("Stopping server with exit status %d", status)

618

exitstatus = status

619

if main_loop_started:

620

main_loop.quit()

621

else:

622

sys.exit(status)

623

624

625

def main():

626

global exitstatus

627

exitstatus = 0

628

global main_loop_started

629

main_loop_started = False

630

537

631

parser = OptionParser()

538

632

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

539

633

default=None, metavar="IF",

540

634

help="Bind to interface IF")

541

parser.add_option("--cert", type="string", default="cert.pem",

542

metavar="FILE",

543

help="Public key certificate PEM file to use")

544

parser.add_option("--key", type="string", default="key.pem",

545

metavar="FILE",

546

help="Private key PEM file to use")

547

parser.add_option("--ca", type="string", default="ca.pem",

548

metavar="FILE",

549

help="Certificate Authority certificate PEM file to use")

550

parser.add_option("--crl", type="string", default="crl.pem",

551

metavar="FILE",

552

help="Certificate Revokation List PEM file to use")

635

parser.add_option("-a", "--address", type="string", default=None,

636

help="Address to listen for requests on")

553

637

parser.add_option("-p", "--port", type="int", default=None,

554

638

help="Port number to receive requests on")

555

639

parser.add_option("--timeout", type="string", # Parsed later

580

664

parser.error("option --interval: Unparseable time")

581

665

582

666

# Parse config file

583

defaults = { "checker": "sleep 1; fping -q -- %%(fqdn)s" }

667

defaults = { "checker": "fping -q -- %%(fqdn)s" }

584

668

client_config = ConfigParser.SafeConfigParser(defaults)

585

#client_config.readfp(open("secrets.conf"), "secrets.conf")

669

#client_config.readfp(open("global.conf"), "global.conf")

586

670

client_config.read("mandos-clients.conf")

587

671

588

# From the Avahi server example code

672

global main_loop

673

global bus

674

global server

675

# From the Avahi example code

589

676

DBusGMainLoop(set_as_default=True )

590

677

main_loop = gobject.MainLoop()

591

678

bus = dbus.SystemBus()

596

683

597

684

debug = options.debug

598

685

686

if debug:

687

console = logging.StreamHandler()

688

# console.setLevel(logging.DEBUG)

689

console.setFormatter(logging.Formatter\

690

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

691

logger.addHandler(console)

692

del console

693

599

694

clients = Set()

600

695

def remove_from_clients(client):

601

696

clients.remove(client)

602

697

if not clients:

603

698

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

604

main_loop.quit()

699

killme()

605

700

606

701

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

607

702

stop_hook = remove_from_clients,

608

703

**(dict(client_config\

609

704

.items(section))))

610

705

for section in client_config.sections()))

706

707

if not debug:

708

daemon(False, False)

709

710

def cleanup():

711

"Cleanup function; run on exit"

712

global group

713

# From the Avahi example code

714

if not group is None:

715

group.Free()

716

group = None

717

# End of Avahi example code

718

719

while clients:

720

client = clients.pop()

721

client.stop_hook = None

722

client.stop()

723

724

atexit.register(cleanup)

725

726

if not debug:

727

signal.signal(signal.SIGINT, signal.SIG_IGN)

728

signal.signal(signal.SIGHUP, lambda signum, frame: killme())

729

signal.signal(signal.SIGTERM, lambda signum, frame: killme())

730

611

731

for client in clients:

612

732

client.start()

613

733

614

tcp_server = IPv6_TCPServer((None, options.port),

734

tcp_server = IPv6_TCPServer((options.address, options.port),

615

735

tcp_handler,

616

736

options=options,

617

737

clients=clients)

618

738

# Find out what random port we got

739

global servicePort

619

740

servicePort = tcp_server.socket.getsockname()[1]

620

741

logger.debug(u"Now listening on port %d", servicePort)

621

742

622

743

if options.interface is not None:

744

global serviceInterface

623

745

serviceInterface = if_nametoindex(options.interface)

624

746

625

# From the Avahi server example code

747

# From the Avahi example code

626

748

server.connect_to_signal("StateChanged", server_state_changed)

627

server_state_changed(server.GetState())

749

try:

750

server_state_changed(server.GetState())

751

except dbus.exceptions.DBusException, error:

752

logger.critical(u"DBusException: %s", error)

753

killme(1)

628

754

# End of Avahi example code

629

755

630

756

gobject.io_add_watch(tcp_server.fileno(), gobject.IO_IN,

632

758

tcp_server.handle_request(*args[2:],

633

759

**kwargs) or True)

634

760

try:

761

logger.debug("Starting main loop")

762

main_loop_started = True

635

763

main_loop.run()

636

764

except KeyboardInterrupt:

637

print

765

if debug:

766

print

638

767

639

# Cleanup here

768

sys.exit(exitstatus)

640

769

641

# From the Avahi server example code

642

if not group is None:

643

group.Free()

644

# End of Avahi example code

645

646

for client in clients:

647

client.stop_hook = None

648

client.stop()

770

if __name__ == '__main__':

771

main()