/mandos/trunk : revision 24.1.13

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

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

28

# <http://www.gnu.org/licenses/>.

27

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

29

28

#

30

29

# Contact the authors at <mandos@fukt.bsnet.se>.

31

30

#

62

61

from dbus.mainloop.glib import DBusGMainLoop

63

62

import ctypes

64

63

65

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

66

75

67

76

logger = logging.Logger('mandos')

68

77

syslogger = logging.handlers.SysLogHandler\

69

(facility = logging.handlers.SysLogHandler.LOG_DAEMON,

70

address = "/dev/log")

78

(facility = logging.handlers.SysLogHandler.LOG_DAEMON)

71

79

syslogger.setFormatter(logging.Formatter\

72

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

80

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

73

81

logger.addHandler(syslogger)

82

del syslogger

74

83

75

console = logging.StreamHandler()

76

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

77

' %(message)s'))

78

logger.addHandler(console)

79

84

80

85

class AvahiError(Exception):

81

86

def __init__(self, value):

91

96

92

97

93

98

class AvahiService(object):

94

"""An Avahi (Zeroconf) service.

95

Attributes:

99

"""

96

100

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

97

101

Used to optionally bind to the specified interface.

98

name: string; Example: 'Mandos'

99

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

100

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

101

port: integer; what port to announce

102

TXT: list of strings; TXT record for the service

103

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

104

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

105

max_renames: integer; maximum number of renames

106

rename_count: integer; counter so we only rename after collisions

107

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

108

113

"""

109

114

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

110

115

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

111

host = "", max_renames = 32768):

116

host = "", max_renames = 12):

117

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

112

118

self.interface = interface

113

119

self.name = name

114

120

self.type = type

120

126

self.domain = domain

121

127

self.host = host

122

128

self.rename_count = 0

123

self.max_renames = max_renames

124

129

def rename(self):

125

130

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

126

131

if self.rename_count >= self.max_renames:

127

logger.critical(u"No suitable Zeroconf service name found"

128

u" after %i retries, exiting.",

129

rename_count)

132

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

133

u" retries, exiting.", rename_count)

130

134

raise AvahiServiceError("Too many renames")

131

self.name = server.GetAlternativeServiceName(self.name)

132

logger.info(u"Changing Zeroconf service name to %r ...",

133

str(self.name))

134

syslogger.setFormatter(logging.Formatter\

135

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

136

' %%(message)s' % self.name))

135

name = server.GetAlternativeServiceName(name)

136

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

137

self.remove()

138

self.add()

139

self.rename_count += 1

151

avahi.DBUS_INTERFACE_ENTRY_GROUP)

152

group.connect_to_signal('StateChanged',

153

entry_group_state_changed)

154

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

154

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

155

service.name, service.type)

156

group.AddService(

157

self.interface, # interface

175

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

176

uniquely identify the client

177

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

178

host: string; available for use by the checker command

178

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

179

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

180

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

181

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

221

interval = property(lambda self: self._interval,

222

_set_interval)

223

del _set_interval

224

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

225

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

226

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

227

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.."""

228

229

self.name = name

229

230

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

230

# Uppercase and remove spaces from fingerprint for later

231

# comparison purposes with return value from the fingerprint()

232

# function

233

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

234

.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"")

235

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

236

if "secret" in config:

237

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

238

elif "secfile" in config:

239

sf = open(config["secfile"])

236

if secret:

237

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

238

elif secfile:

239

sf = open(secfile)

240

self.secret = sf.read()

241

sf.close()

242

else:

243

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

244

% self.name)

245

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

245

self.fqdn = fqdn

246

self.created = datetime.datetime.now()

247

self.last_checked_ok = None

248

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

249

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

248

self.timeout = string_to_delta(timeout)

249

self.interval = string_to_delta(interval)

250

self.stop_hook = stop_hook

251

self.checker = None

252

self.checker_initiator_tag = None

253

self.stop_initiator_tag = None

254

self.checker_callback_tag = None

255

self.check_command = config["checker"]

255

self.check_command = checker

256

def start(self):

257

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

258

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

271

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

272

but not currently used."""

273

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

274

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

275

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

274

if self.secret:

275

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

276

self.secret = None

277

else:

278

return False

297

self.checker = None

298

if os.WIFEXITED(condition) \

299

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

300

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

301

vars(self))

300

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

301

vars(self))

302

self.last_checked_ok = now

303

gobject.source_remove(self.stop_initiator_tag)

304

self.stop_initiator_tag = gobject.timeout_add\

308

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

309

vars(self))

310

else:

311

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

312

vars(self))

311

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

312

vars(self))

313

def start_checker(self):

314

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

315

If a checker already exists, leave it running and do

325

if self.checker is None:

326

try:

327

# In case check_command has exactly one % operator

328

command = self.check_command % self.host

328

command = self.check_command % self.fqdn

329

except TypeError:

330

# Escape attributes for the shell

331

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

338

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

339

return True # Try again later

340

try:

341

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

342

command, self.name)

343

# We don't need to redirect stdout and stderr, since

344

# in normal mode, that is already done by daemon(),

345

# and in debug mode we don't want to. (Stdin is

346

# always replaced by /dev/null.)

341

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

342

command, self.name)

347

343

self.checker = subprocess.Popen(command,

348

344

close_fds=True,

349

345

shell=True, cwd="/")

350

346

self.checker_callback_tag = gobject.child_watch_add\

351

347

(self.checker.pid,

352

348

self.checker_callback)

353

except OSError, error:

349

except subprocess.OSError, error:

354

350

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

355

351

error)

356

352

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

362

358

self.checker_callback_tag = None

363

359

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

364

360

return

365

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

361

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

366

362

try:

367

363

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

368

364

#os.sleep(0.5)

400

396

401

397

def fingerprint(openpgp):

402

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))

403

# New GnuTLS "datum" with the OpenPGP public key

404

datum = gnutls.library.types.gnutls_datum_t\

405

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

406

ctypes.POINTER(ctypes.c_ubyte)),

407

ctypes.c_uint(len(openpgp)))

408

# New empty GnuTLS certificate

409

crt = gnutls.library.types.gnutls_openpgp_crt_t()

410

gnutls.library.functions.gnutls_openpgp_crt_init\

411

(ctypes.byref(crt))

412

408

# Import the OpenPGP public key into the certificate

413

gnutls.library.functions.gnutls_openpgp_crt_import\

414

(crt, ctypes.byref(datum),

415

gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

416

# Verify the self signature in the key

417

crtverify = ctypes.c_uint();

418

gnutls.library.functions.gnutls_openpgp_crt_verify_self\

419

(crt, 0, ctypes.byref(crtverify))

420

if crtverify.value != 0:

421

gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)

422

raise gnutls.errors.CertificateSecurityError("Verify failed")

409

ret = gnutls.library.functions.gnutls_openpgp_crt_import\

410

(crt,

411

ctypes.byref(datum),

412

gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

423

413

# New buffer for the fingerprint

424

414

buffer = ctypes.create_string_buffer(20)

425

415

buffer_length = ctypes.c_size_t()

441

431

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

442

432

443

433

def handle(self):

444

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

434

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

445

435

unicode(self.client_address))

446

session = gnutls.connection.ClientSession\

447

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

448

436

449

437

line = self.request.makefile().readline()

450

438

logger.debug(u"Protocol version: %r", line)

451

439

try:

455

443

logger.error(u"Unknown protocol version: %s", error)

456

444

return

457

445

446

session = gnutls.connection.ClientSession\

447

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

458

448

# Note: gnutls.connection.X509Credentials is really a generic

459

449

# GnuTLS certificate credentials object so long as no X.509

460

450

# keys are added to it. Therefore, we can use it here despite

473

463

try:

474

464

session.handshake()

475

465

except gnutls.errors.GNUTLSError, error:

476

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

466

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

477

467

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

478

468

# established. Just abandon the request.

479

469

return

480

470

try:

481

471

fpr = fingerprint(peer_certificate(session))

482

472

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

483

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

473

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

484

474

session.bye()

485

475

return

486

476

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

490

480

client = c

491

481

break

492

482

if not client:

493

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

494

fpr)

483

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

495

484

session.bye()

496

485

return

497

486

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

498

487

# that the client timed out while establishing the GnuTLS

499

488

# session.

500

489

if not client.still_valid():

501

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

502

vars(client))

490

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

503

491

session.bye()

504

492

return

505

493

sent_size = 0

540

528

self.settings["interface"])

541

529

except socket.error, error:

542

530

if error[0] == errno.EPERM:

543

logger.error(u"No permission to"

544

u" bind to interface %s",

545

self.settings["interface"])

531

logger.warning(u"No permission to"

532

u" bind to interface %s",

533

self.settings["interface"])

546

534

else:

547

535

raise error

548

536

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

551

539

in6addr_any = "::"

552

540

self.server_address = (in6addr_any,

553

541

self.server_address[1])

554

elif not self.server_address[1]:

542

elif self.server_address[1] is None:

555

543

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

556

544

0)

557

# if self.settings["interface"]:

558

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

559

# 0, # port

560

# 0, # flowinfo

561

# if_nametoindex

562

# (self.settings

563

# ["interface"]))

564

545

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

565

546

566

547

577

558

datetime.timedelta(1)

578

559

>>> string_to_delta(u'1w')

579

560

datetime.timedelta(7)

580

>>> string_to_delta('5m 30s')

581

datetime.timedelta(0, 330)

582

561

"""

583

timevalue = datetime.timedelta(0)

584

for s in interval.split():

585

try:

586

suffix=unicode(s[-1])

587

value=int(s[:-1])

588

if suffix == u"d":

589

delta = datetime.timedelta(value)

590

elif suffix == u"s":

591

delta = datetime.timedelta(0, value)

592

elif suffix == u"m":

593

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

594

elif suffix == u"h":

595

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

596

elif suffix == u"w":

597

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

598

else:

599

raise ValueError

600

except (ValueError, IndexError):

562

try:

563

suffix=unicode(interval[-1])

564

value=int(interval[:-1])

565

if suffix == u"d":

566

delta = datetime.timedelta(value)

567

elif suffix == u"s":

568

delta = datetime.timedelta(0, value)

569

elif suffix == u"m":

570

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

571

elif suffix == u"h":

572

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

573

elif suffix == u"w":

574

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

575

else:

601

576

raise ValueError

602

timevalue += delta

603

return timevalue

577

except (ValueError, IndexError):

578

raise ValueError

579

return delta

604

580

605

581

606

582

def server_state_changed(state):

607

583

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

608

584

if state == avahi.SERVER_COLLISION:

609

logger.error(u"Zeroconf server name collision")

585

logger.warning(u"Server name collision")

610

586

service.remove()

611

587

elif state == avahi.SERVER_RUNNING:

612

588

service.add()

614

590

615

591

def entry_group_state_changed(state, error):

616

592

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

617

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

593

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

618

594

619

595

if state == avahi.ENTRY_GROUP_ESTABLISHED:

620

logger.debug(u"Zeroconf service established.")

596

logger.debug(u"Service established.")

621

597

elif state == avahi.ENTRY_GROUP_COLLISION:

622

logger.warning(u"Zeroconf service name collision.")

598

logger.warning(u"Service name collision.")

623

599

service.rename()

624

600

elif state == avahi.ENTRY_GROUP_FAILURE:

625

logger.critical(u"Avahi: Error in group state changed %s",

601

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

626

602

unicode(error))

627

603

raise AvahiGroupError("State changed: %s", str(error))

628

604

651

627

return if_nametoindex(interface)

652

628

653

629

654

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

630

def daemon(nochdir, noclose):

655

631

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

656

632

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

657

633

if os.fork():

659

635

os.setsid()

660

636

if not nochdir:

661

637

os.chdir("/")

662

if os.fork():

663

sys.exit()

664

638

if not noclose:

665

639

# Close all standard open file descriptors

666

640

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

678

652

global main_loop_started

679

653

main_loop_started = False

680

654

681

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

655

parser = OptionParser()

682

656

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

683

657

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

684

658

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

687

661

help="Port number to receive requests on")

688

662

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

689

663

help="Run self-test")

690

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

664

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

691

665

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

692

666

" terminal")

693

667

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

718

692

# Parse config file for server-global settings

719

693

server_config = ConfigParser.SafeConfigParser(server_defaults)

720

694

del server_defaults

721

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

695

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

696

server_section = "server"

722

697

# Convert the SafeConfigParser object to a dict

723

server_settings = server_config.defaults()

698

server_settings = dict(server_config.items(server_section))

724

699

# Use getboolean on the boolean config option

725

700

server_settings["debug"] = server_config.getboolean\

726

("DEFAULT", "debug")

701

(server_section, "debug")

727

702

del server_config

728

703

729

704

# Override the settings from the config file with command line

736

711

del options

737

712

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

738

713

739

debug = server_settings["debug"]

740

741

if not debug:

742

syslogger.setLevel(logging.WARNING)

743

console.setLevel(logging.WARNING)

744

745

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

746

syslogger.setFormatter(logging.Formatter\

747

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

748

' %%(message)s'

749

% server_settings["servicename"]))

750

751

714

# Parse config file with clients

752

715

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

753

716

"interval": "5m",

754

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

755

"host": "",

717

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

756

718

}

757

719

client_config = ConfigParser.SafeConfigParser(client_defaults)

758

720

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

762

724

service = AvahiService(name = server_settings["servicename"],

763

725

type = "_mandos._tcp", );

764

726

if server_settings["interface"]:

765

service.interface = if_nametoindex\

766

(server_settings["interface"])

727

service.interface = if_nametoindex(server_settings["interface"])

767

728

768

729

global main_loop

769

730

global bus

772

733

DBusGMainLoop(set_as_default=True )

773

734

main_loop = gobject.MainLoop()

774

735

bus = dbus.SystemBus()

775

server = dbus.Interface(bus.get_object(avahi.DBUS_NAME,

776

avahi.DBUS_PATH_SERVER),

777

avahi.DBUS_INTERFACE_SERVER)

736

server = dbus.Interface(

737

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

738

avahi.DBUS_INTERFACE_SERVER )

778

739

# End of Avahi example code

779

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

780

751

clients = Set()

781

752

def remove_from_clients(client):

782

753

clients.remove(client)

783

754

if not clients:

784

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

755

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

785

756

sys.exit()

786

757

787

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

758

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

788

759

stop_hook = remove_from_clients,

789

config

790

= dict(client_config.items(section)))

760

**(dict(client_config\

761

.items(section))))

791

762

for section in client_config.sections()))

792

if not clients:

793

logger.critical(u"No clients defined")

794

sys.exit(1)

795

796

if debug:

797

# Redirect stdin so all checkers get /dev/null

798

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

799

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

800

if null > 2:

801

os.close(null)

802

else:

803

# No console logging

804

logger.removeHandler(console)

805

# Close all input and output, do double fork, etc.

806

daemon()

807

808

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

809

pid = os.getpid()

810

try:

811

pidfile = open(pidfilename, "w")

812

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

813

pidfile.close()

814

del pidfile

815

except IOError, err:

816

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

817

pidfilename, os.getpid())

763

764

if not debug:

765

daemon(False, False)

818

766

819

767

def cleanup():

820

768

"Cleanup function; run on exit"

847

795

clients=clients)

848

796

# Find out what port we got

849

797

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

850

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

851

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())

852

800

853

801

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

854

802

867

815

tcp_server.handle_request\

868

816

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

869

817

870

logger.debug(u"Starting main loop")

818

logger.debug("Starting main loop")

871

819

main_loop_started = True

872

820

main_loop.run()

873

821

except AvahiError, error: