/mandos/trunk : revision 1

1

#!/usr/bin/python

2

3

from __future__ import division

4

5

import SocketServer

6

import socket

7

import select

8

from optparse import OptionParser

9

import datetime

10

import errno

11

import gnutls.crypto

12

import gnutls.connection

13

import gnutls.errors

14

import gnutls.library.functions

15

import gnutls.library.constants

16

import gnutls.library.types

17

import ConfigParser

18

import sys

19

import re

20

import os

21

import signal

22

from sets import Set

23

import subprocess

24

25

import dbus

26

import gobject

27

import avahi

28

from dbus.mainloop.glib import DBusGMainLoop

29

import ctypes

30

31

import logging

32

import logging.handlers

33

34

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

35

36

logger = logging.Logger('mandos')

37

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

38

39

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

40

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

41

# Avahi server example code.

42

serviceInterface = avahi.IF_UNSPEC

43

# From the Avahi server example code:

44

serviceName = "Mandos"

45

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

46

servicePort = None # Not known at startup

47

serviceTXT = [] # TXT record for the service

48

domain = "" # Domain to publish on, default to .local

49

host = "" # Host to publish records for, default to localhost

50

group = None #our entry group

51

rename_count = 12 # Counter so we only rename after collisions a

52

# sensible number of times

53

# End of Avahi example code

54

55

56

class Client(object):

57

"""A representation of a client host served by this server.

58

Attributes:

59

name: string; from the config file, used in log messages

60

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

61

uniquely identify the client

62

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

63

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

64

created: datetime.datetime()

65

last_seen: datetime.datetime() or None if not yet seen

66

timeout: datetime.timedelta(); How long from last_seen until

67

this client is invalid

68

interval: datetime.timedelta(); How often to start a new checker

69

stop_hook: If set, called by stop() as stop_hook(self)

70

checker: subprocess.Popen(); a running checker process used

71

to see if the client lives.

72

Is None if no process is running.

73

checker_initiator_tag: a gobject event source tag, or None

74

stop_initiator_tag: - '' -

75

checker_callback_tag: - '' -

76

checker_command: string; External command which is run to check if

77

client lives. %()s expansions are done at

78

runtime with vars(self) as dict, so that for

79

instance %(name)s can be used in the command.

80

Private attibutes:

81

_timeout: Real variable for 'timeout'

82

_interval: Real variable for 'interval'

83

_timeout_milliseconds: Used by gobject.timeout_add()

84

_interval_milliseconds: - '' -

85

"""

86

def _set_timeout(self, timeout):

87

"Setter function for 'timeout' attribute"

88

self._timeout = timeout

89

self._timeout_milliseconds = ((self.timeout.days

90

* 24 * 60 * 60 * 1000)

91

+ (self.timeout.seconds * 1000)

92

+ (self.timeout.microseconds

93

// 1000))

94

timeout = property(lambda self: self._timeout,

95

_set_timeout)

96

del _set_timeout

97

def _set_interval(self, interval):

98

"Setter function for 'interval' attribute"

99

self._interval = interval

100

self._interval_milliseconds = ((self.interval.days

101

* 24 * 60 * 60 * 1000)

102

+ (self.interval.seconds

103

* 1000)

104

+ (self.interval.microseconds

105

// 1000))

106

interval = property(lambda self: self._interval,

107

_set_interval)

108

del _set_interval

109

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):

112

self.name = name

113

# Uppercase and remove spaces from fingerprint

114

# for later comparison purposes with return value of

115

# the fingerprint() function

116

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

117

if secret:

118

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

119

elif secfile:

120

sf = open(secfile)

121

self.secret = sf.read()

122

sf.close()

123

else:

124

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

125

% self.name)

126

self.fqdn = fqdn # string

127

self.created = datetime.datetime.now()

128

self.last_seen = None

129

if timeout is None:

130

timeout = options.timeout

131

self.timeout = timeout

132

if interval == -1:

133

interval = options.interval

134

else:

135

interval = string_to_delta(interval)

136

self.interval = interval

137

self.stop_hook = stop_hook

138

self.checker = None

139

self.checker_initiator_tag = None

140

self.stop_initiator_tag = None

141

self.checker_callback_tag = None

142

self.check_command = checker

143

def start(self):

144

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

145

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

146

# and every interval from then on.

147

self.checker_initiator_tag = gobject.timeout_add\

148

(self._interval_milliseconds,

149

self.start_checker)

150

# Also start a new checker *right now*.

151

self.start_checker()

152

# Schedule a stop() when 'timeout' has passed

153

self.stop_initiator_tag = gobject.timeout_add\

154

(self._timeout_milliseconds,

155

self.stop)

156

def stop(self):

157

"""Stop this client.

158

The possibility that this client might be restarted is left

159

open, but not currently used."""

160

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

161

self.secret = None

162

if self.stop_initiator_tag:

163

gobject.source_remove(self.stop_initiator_tag)

164

self.stop_initiator_tag = None

165

if self.checker_initiator_tag:

166

gobject.source_remove(self.checker_initiator_tag)

167

self.checker_initiator_tag = None

168

self.stop_checker()

169

if self.stop_hook:

170

self.stop_hook(self)

171

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

172

return False

173

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()

184

def checker_callback(self, pid, condition):

185

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

186

now = datetime.datetime.now()

187

if os.WIFEXITED(condition) \

188

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

189

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

190

vars(self))

191

self.last_seen = now

192

gobject.source_remove(self.stop_initiator_tag)

193

self.stop_initiator_tag = gobject.timeout_add\

194

(self._timeout_milliseconds,

195

self.stop)

196

if not os.WIFEXITED(condition):

197

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

198

vars(self))

199

else:

200

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

201

vars(self))

202

self.checker = None

203

self.checker_callback_tag = None

204

def start_checker(self):

205

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

206

If a checker already exists, leave it running and do

207

nothing."""

208

if self.checker is None:

209

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

210

self.name)

211

try:

212

command = self.check_command % self.fqdn

213

except TypeError:

214

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

215

for key, val in

216

vars(self).iteritems())

217

try:

218

command = self.check_command % escaped_attrs

219

except TypeError, error:

220

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

221

self.check_command, error)

222

return True # Try again later

223

try:

224

self.checker = subprocess.\

225

Popen(command,

226

stdout=subprocess.PIPE,

227

close_fds=True, shell=True,

228

cwd="/")

229

self.checker_callback_tag = gobject.\

230

child_watch_add(self.checker.pid,

231

self.\

232

checker_callback)

233

except subprocess.OSError, error:

234

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

235

error)

236

# Re-run this periodically if run by gobject.timeout_add

237

return True

238

def stop_checker(self):

239

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

240

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

241

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)

247

self.checker = None

248

def still_valid(self, now=None):

249

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

250

if now is None:

251

now = datetime.datetime.now()

252

if self.last_seen is None:

253

return now < (self.created + self.timeout)

254

else:

255

return now < (self.last_seen + self.timeout)

256

257

258

def peer_certificate(session):

259

# If not an OpenPGP certificate...

260

if gnutls.library.functions.gnutls_certificate_type_get\

261

(session._c_object) \

262

!= gnutls.library.constants.GNUTLS_CRT_OPENPGP:

263

# ...do the normal thing

264

return session.peer_certificate

265

list_size = ctypes.c_uint()

266

cert_list = gnutls.library.functions.gnutls_certificate_get_peers\

267

(session._c_object, ctypes.byref(list_size))

268

if list_size.value == 0:

269

return None

270

cert = cert_list[0]

271

return ctypes.string_at(cert.data, cert.size)

272

273

274

def fingerprint(openpgp):

275

# New empty GnuTLS certificate

276

crt = gnutls.library.types.gnutls_openpgp_crt_t()

277

gnutls.library.functions.gnutls_openpgp_crt_init\

278

(ctypes.byref(crt))

279

# New GnuTLS "datum" with the OpenPGP public key

280

datum = gnutls.library.types.gnutls_datum_t\

281

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

282

ctypes.POINTER(ctypes.c_ubyte)),

283

ctypes.c_uint(len(openpgp)))

284

# Import the OpenPGP public key into the certificate

285

ret = gnutls.library.functions.gnutls_openpgp_crt_import\

286

(crt,

287

ctypes.byref(datum),

288

gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

289

# New buffer for the fingerprint

290

buffer = ctypes.create_string_buffer(20)

291

buffer_length = ctypes.c_size_t()

292

# Get the fingerprint from the certificate into the buffer

293

gnutls.library.functions.gnutls_openpgp_crt_get_fingerprint\

294

(crt, ctypes.byref(buffer), ctypes.byref(buffer_length))

295

# Deinit the certificate

296

gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)

297

# Convert the buffer to a Python bytestring

298

fpr = ctypes.string_at(buffer, buffer_length.value)

299

# Convert the bytestring to hexadecimal notation

300

hex_fpr = u''.join(u"%02X" % ord(char) for char in fpr)

301

return hex_fpr

302

303

304

class tcp_handler(SocketServer.BaseRequestHandler, object):

305

"""A TCP request handler class.

306

Instantiated by IPv6_TCPServer for each request to handle it.

307

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

308

309

def handle(self):

310

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

311

unicode(self.client_address))

312

session = gnutls.connection.ClientSession(self.request,

313

gnutls.connection.\

314

X509Credentials())

315

316

#priority = ':'.join(("NONE", "+VERS-TLS1.1", "+AES-256-CBC",

317

# "+SHA1", "+COMP-NULL", "+CTYPE-OPENPGP",

318

# "+DHE-DSS"))

319

priority = "SECURE256"

320

321

gnutls.library.functions.gnutls_priority_set_direct\

322

(session._c_object, priority, None);

323

324

try:

325

session.handshake()

326

except gnutls.errors.GNUTLSError, error:

327

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

328

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

329

# established. Just abandon the request.

330

return

331

try:

332

fpr = fingerprint(peer_certificate(session))

333

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

334

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

335

session.bye()

336

return

337

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

338

client = None

339

for c in clients:

340

if c.fingerprint == fpr:

341

client = c

342

break

343

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

344

# that the client timed out while establishing the GnuTLS

345

# session.

346

if (not client) or (not client.still_valid()):

347

if client:

348

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

349

vars(client))

350

else:

351

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

352

fpr)

353

session.bye()

354

return

355

sent_size = 0

356

while sent_size < len(client.secret):

357

sent = session.send(client.secret[sent_size:])

358

logger.debug(u"Sent: %d, remaining: %d",

359

sent, len(client.secret)

360

- (sent_size + sent))

361

sent_size += sent

362

session.bye()

363

364

365

class IPv6_TCPServer(SocketServer.ForkingTCPServer, object):

366

"""IPv6 TCP server. Accepts 'None' as address and/or port.

367

Attributes:

368

options: Command line options

369

clients: Set() of Client objects

370

"""

371

address_family = socket.AF_INET6

372

def __init__(self, *args, **kwargs):

373

if "options" in kwargs:

374

self.options = kwargs["options"]

375

del kwargs["options"]

376

if "clients" in kwargs:

377

self.clients = kwargs["clients"]

378

del kwargs["clients"]

379

return super(type(self), self).__init__(*args, **kwargs)

380

def server_bind(self):

381

"""This overrides the normal server_bind() function

382

to bind to an interface if one was specified, and also NOT to

383

bind to an address or port if they were not specified."""

384

if self.options.interface:

385

if not hasattr(socket, "SO_BINDTODEVICE"):

386

# From /usr/include/asm-i486/socket.h

387

socket.SO_BINDTODEVICE = 25

388

try:

389

self.socket.setsockopt(socket.SOL_SOCKET,

390

socket.SO_BINDTODEVICE,

391

self.options.interface)

392

except socket.error, error:

393

if error[0] == errno.EPERM:

394

logger.warning(u"No permission to"

395

u" bind to interface %s",

396

self.options.interface)

397

else:

398

raise error

399

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

400

if self.server_address[0] or self.server_address[1]:

401

if not self.server_address[0]:

402

in6addr_any = "::"

403

self.server_address = (in6addr_any,

404

self.server_address[1])

405

elif self.server_address[1] is None:

406

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

407

0)

408

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

409

410

411

def string_to_delta(interval):

412

"""Parse a string and return a datetime.timedelta

413

414

>>> string_to_delta('7d')

415

datetime.timedelta(7)

416

>>> string_to_delta('60s')

417

datetime.timedelta(0, 60)

418

>>> string_to_delta('60m')

419

datetime.timedelta(0, 3600)

420

>>> string_to_delta('24h')

421

datetime.timedelta(1)

422

>>> string_to_delta(u'1w')

423

datetime.timedelta(7)

424

"""

425

try:

426

suffix=unicode(interval[-1])

427

value=int(interval[:-1])

428

if suffix == u"d":

429

delta = datetime.timedelta(value)

430

elif suffix == u"s":

431

delta = datetime.timedelta(0, value)

432

elif suffix == u"m":

433

delta = datetime.timedelta(0, 0, 0, 0, value)

434

elif suffix == u"h":

435

delta = datetime.timedelta(0, 0, 0, 0, 0, value)

436

elif suffix == u"w":

437

delta = datetime.timedelta(0, 0, 0, 0, 0, 0, value)

438

else:

439

raise ValueError

440

except (ValueError, IndexError):

441

raise ValueError

442

return delta

443

444

445

def add_service():

446

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

447

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

448

domain, host

449

if group is None:

450

group = dbus.Interface(

451

bus.get_object( avahi.DBUS_NAME,

452

server.EntryGroupNew()),

453

avahi.DBUS_INTERFACE_ENTRY_GROUP)

454

group.connect_to_signal('StateChanged',

455

entry_group_state_changed)

456

logger.debug(u"Adding service '%s' of type '%s' ...",

457

serviceName, serviceType)

458

459

group.AddService(

460

serviceInterface, # interface

461

avahi.PROTO_INET6, # protocol

462

dbus.UInt32(0), # flags

463

serviceName, serviceType,

464

domain, host,

465

dbus.UInt16(servicePort),

466

avahi.string_array_to_txt_array(serviceTXT))

467

group.Commit()

468

469

470

def remove_service():

471

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

472

global group

473

474

if not group is None:

475

group.Reset()

476

477

478

def server_state_changed(state):

479

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

480

if state == avahi.SERVER_COLLISION:

481

logger.warning(u"Server name collision")

482

remove_service()

483

elif state == avahi.SERVER_RUNNING:

484

add_service()

485

486

487

def entry_group_state_changed(state, error):

488

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

489

global serviceName, server, rename_count

490

491

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

492

493

if state == avahi.ENTRY_GROUP_ESTABLISHED:

494

logger.debug(u"Service established.")

495

elif state == avahi.ENTRY_GROUP_COLLISION:

496

497

rename_count = rename_count - 1

498

if rename_count > 0:

499

name = server.GetAlternativeServiceName(name)

500

logger.warning(u"Service name collision, "

501

u"changing name to '%s' ...", name)

502

remove_service()

503

add_service()

504

505

else:

506

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

507

u"after %i retries, exiting.",

508

n_rename)

509

main_loop.quit()

510

elif state == avahi.ENTRY_GROUP_FAILURE:

511

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

512

unicode(error))

513

main_loop.quit()

514

return

515

516

517

def if_nametoindex(interface):

518

"""Call the C function if_nametoindex()"""

519

try:

520

libc = ctypes.cdll.LoadLibrary("libc.so.6")

521

return libc.if_nametoindex(interface)

522

except (OSError, AttributeError):

523

if "struct" not in sys.modules:

524

import struct

525

if "fcntl" not in sys.modules:

526

import fcntl

527

SIOCGIFINDEX = 0x8933 # From /usr/include/linux/sockios.h

528

s = socket.socket()

529

ifreq = fcntl.ioctl(s, SIOCGIFINDEX,

530

struct.pack("16s16x", interface))

531

s.close()

532

interface_index = struct.unpack("I", ifreq[16:20])[0]

533

return interface_index

534

535

536

if __name__ == '__main__':

537

parser = OptionParser()

538

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

539

default=None, metavar="IF",

540

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")

553

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

554

help="Port number to receive requests on")

555

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

556

default="1h",

557

help="Amount of downtime allowed for clients")

558

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

559

default="5m",

560

help="How often to check that a client is up")

561

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

562

help="Run self-test")

563

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

564

help="Debug mode")

565

(options, args) = parser.parse_args()

566

567

if options.check:

568

import doctest

569

doctest.testmod()

570

sys.exit()

571

572

# Parse the time arguments

573

try:

574

options.timeout = string_to_delta(options.timeout)

575

except ValueError:

576

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

577

try:

578

options.interval = string_to_delta(options.interval)

579

except ValueError:

580

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

581

582

# Parse config file

583

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

584

client_config = ConfigParser.SafeConfigParser(defaults)

585

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

586

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

587

588

# From the Avahi server example code

589

DBusGMainLoop(set_as_default=True )

590

main_loop = gobject.MainLoop()

591

bus = dbus.SystemBus()

592

server = dbus.Interface(

593

bus.get_object( avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER ),

594

avahi.DBUS_INTERFACE_SERVER )

595

# End of Avahi example code

596

597

debug = options.debug

598

599

clients = Set()

600

def remove_from_clients(client):

601

clients.remove(client)

602

if not clients:

603

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

604

main_loop.quit()

605

606

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

607

stop_hook = remove_from_clients,

608

**(dict(client_config\

609

.items(section))))

610

for section in client_config.sections()))

611

for client in clients:

612

client.start()

613

614

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

615

tcp_handler,

616

options=options,

617

clients=clients)

618

# Find out what random port we got

619

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

620

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

621

622

if options.interface is not None:

623

serviceInterface = if_nametoindex(options.interface)

624

625

# From the Avahi server example code

626

server.connect_to_signal("StateChanged", server_state_changed)

627

server_state_changed(server.GetState())

628

# End of Avahi example code

629

630

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

631

lambda *args, **kwargs:

632

tcp_server.handle_request(*args[2:],

633

**kwargs) or True)

634

try:

635

main_loop.run()

636

except KeyboardInterrupt:

637

print

638

639

# Cleanup here

640

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()