/mandos/trunk

To get this branch, use:
bzr branch http://bzr.recompile.se/loggerhead/mandos/trunk
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
#!/usr/bin/python

from __future__ import division

import SocketServer
import socket
import select
from optparse import OptionParser
import datetime
import errno
import gnutls.crypto
import gnutls.connection
import gnutls.errors
import gnutls.library.functions
import gnutls.library.constants
import gnutls.library.types
import ConfigParser
import sys
import re
import os
import signal
from sets import Set
import subprocess

import dbus
import gobject
import avahi
from dbus.mainloop.glib import DBusGMainLoop
import ctypes

import logging
import logging.handlers

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

logger = logging.Logger('mandos')
logger.addHandler(logging.handlers.SysLogHandler(facility = logging.handlers.SysLogHandler.LOG_DAEMON))

# This variable is used to optionally bind to a specified interface.
# It is a global variable to fit in with the other variables from the
# Avahi server example code.
serviceInterface = avahi.IF_UNSPEC
# From the Avahi server example code:
serviceName = "Mandos"
serviceType = "_mandos._tcp" # http://www.dns-sd.org/ServiceTypes.html
servicePort = None                      # Not known at startup
serviceTXT = []                         # TXT record for the service
domain = ""                  # Domain to publish on, default to .local
host = ""          # Host to publish records for, default to localhost
group = None #our entry group
rename_count = 12       # Counter so we only rename after collisions a
                        # sensible number of times
# End of Avahi example code


class Client(object):
    """A representation of a client host served by this server.
    Attributes:
    name:      string; from the config file, used in log messages
    fingerprint: string (40 or 32 hexadecimal digits); used to
                 uniquely identify the client
    secret:    bytestring; sent verbatim (over TLS) to client
    fqdn:      string (FQDN); available for use by the checker command
    created:   datetime.datetime()
    last_seen: datetime.datetime() or None if not yet seen
    timeout:   datetime.timedelta(); How long from last_seen until
                                     this client is invalid
    interval:  datetime.timedelta(); How often to start a new checker
    stop_hook: If set, called by stop() as stop_hook(self)
    checker:   subprocess.Popen(); a running checker process used
                                   to see if the client lives.
                                   Is None if no process is running.
    checker_initiator_tag: a gobject event source tag, or None
    stop_initiator_tag:    - '' -
    checker_callback_tag:  - '' -
    checker_command: string; External command which is run to check if
                     client lives.  %()s expansions are done at
                     runtime with vars(self) as dict, so that for
                     instance %(name)s can be used in the command.
    Private attibutes:
    _timeout: Real variable for 'timeout'
    _interval: Real variable for 'interval'
    _timeout_milliseconds: Used by gobject.timeout_add()
    _interval_milliseconds: - '' -
    """
    def _set_timeout(self, timeout):
        "Setter function for 'timeout' attribute"
        self._timeout = timeout
        self._timeout_milliseconds = ((self.timeout.days
                                       * 24 * 60 * 60 * 1000)
                                      + (self.timeout.seconds * 1000)
                                      + (self.timeout.microseconds
                                         // 1000))
    timeout = property(lambda self: self._timeout,
                       _set_timeout)
    del _set_timeout
    def _set_interval(self, interval):
        "Setter function for 'interval' attribute"
        self._interval = interval
        self._interval_milliseconds = ((self.interval.days
                                        * 24 * 60 * 60 * 1000)
                                       + (self.interval.seconds
                                          * 1000)
                                       + (self.interval.microseconds
                                          // 1000))
    interval = property(lambda self: self._interval,
                        _set_interval)
    del _set_interval
    def __init__(self, name=None, options=None, stop_hook=None,
                 fingerprint=None, secret=None, secfile=None, fqdn=None,
                 timeout=None, interval=-1, checker=None):
        self.name = name
        # Uppercase and remove spaces from fingerprint
        # for later comparison purposes with return value of
        # the fingerprint() function
        self.fingerprint = fingerprint.upper().replace(u" ", u"")
        if secret:
            self.secret = secret.decode(u"base64")
        elif secfile:
            sf = open(secfile)
            self.secret = sf.read()
            sf.close()
        else:
            raise RuntimeError(u"No secret or secfile for client %s"
                               % self.name)
        self.fqdn = fqdn                # string
        self.created = datetime.datetime.now()
        self.last_seen = None
        if timeout is None:
            timeout = options.timeout
        self.timeout = timeout
        if interval == -1:
            interval = options.interval
        else:
            interval = string_to_delta(interval)
        self.interval = interval
        self.stop_hook = stop_hook
        self.checker = None
        self.checker_initiator_tag = None
        self.stop_initiator_tag = None
        self.checker_callback_tag = None
        self.check_command = checker
    def start(self):
        """Start this clients checker and timeout hooks"""
        # Schedule a new checker to be started an 'interval' from now,
        # and every interval from then on.
        self.checker_initiator_tag = gobject.timeout_add\
                                     (self._interval_milliseconds,
                                      self.start_checker)
        # Also start a new checker *right now*.
        self.start_checker()
        # Schedule a stop() when 'timeout' has passed
        self.stop_initiator_tag = gobject.timeout_add\
                                  (self._timeout_milliseconds,
                                   self.stop)
    def stop(self):
        """Stop this client.
        The possibility that this client might be restarted is left
        open, but not currently used."""
        logger.debug(u"Stopping client %s", self.name)
        self.secret = None
        if self.stop_initiator_tag:
            gobject.source_remove(self.stop_initiator_tag)
            self.stop_initiator_tag = None
        if self.checker_initiator_tag:
            gobject.source_remove(self.checker_initiator_tag)
            self.checker_initiator_tag = None
        self.stop_checker()
        if self.stop_hook:
            self.stop_hook(self)
        # Do not run this again if called by a gobject.timeout_add
        return False
    def __del__(self):
        # Some code duplication here and in stop()
        if hasattr(self, "stop_initiator_tag") \
               and self.stop_initiator_tag:
            gobject.source_remove(self.stop_initiator_tag)
            self.stop_initiator_tag = None
        if hasattr(self, "checker_initiator_tag") \
               and self.checker_initiator_tag:
            gobject.source_remove(self.checker_initiator_tag)
            self.checker_initiator_tag = None
        self.stop_checker()
    def checker_callback(self, pid, condition):
        """The checker has completed, so take appropriate actions."""
        now = datetime.datetime.now()
        if os.WIFEXITED(condition) \
               and (os.WEXITSTATUS(condition) == 0):
            logger.debug(u"Checker for %(name)s succeeded",
                         vars(self))
            self.last_seen = now
            gobject.source_remove(self.stop_initiator_tag)
            self.stop_initiator_tag = gobject.timeout_add\
                                      (self._timeout_milliseconds,
                                       self.stop)
        if not os.WIFEXITED(condition):
            logger.warning(u"Checker for %(name)s crashed?",
                           vars(self))
        else:
            logger.debug(u"Checker for %(name)s failed",
                         vars(self))
            self.checker = None
        self.checker_callback_tag = None
    def start_checker(self):
        """Start a new checker subprocess if one is not running.
        If a checker already exists, leave it running and do
        nothing."""
        if self.checker is None:
            logger.debug(u"Starting checker for %s",
                         self.name)
            try:
                command = self.check_command % self.fqdn
            except TypeError:
                escaped_attrs = dict((key, re.escape(str(val)))
                                     for key, val in
                                     vars(self).iteritems())
                try:
                    command = self.check_command % escaped_attrs
                except TypeError, error:
                    logger.critical(u'Could not format string "%s": %s',
                                    self.check_command, error)
                    return True # Try again later
            try:
                self.checker = subprocess.\
                               Popen(command,
                                     stdout=subprocess.PIPE,
                                     close_fds=True, shell=True,
                                     cwd="/")
                self.checker_callback_tag = gobject.\
                                            child_watch_add(self.checker.pid,
                                                            self.\
                                                            checker_callback)
            except subprocess.OSError, error:
                logger.error(u"Failed to start subprocess: %s",
                             error)
        # Re-run this periodically if run by gobject.timeout_add
        return True
    def stop_checker(self):
        """Force the checker process, if any, to stop."""
        if not hasattr(self, "checker") or self.checker is None:
            return
        gobject.source_remove(self.checker_callback_tag)
        self.checker_callback_tag = None
        os.kill(self.checker.pid, signal.SIGTERM)
        if self.checker.poll() is None:
            os.kill(self.checker.pid, signal.SIGKILL)
        self.checker = None
    def still_valid(self, now=None):
        """Has the timeout not yet passed for this client?"""
        if now is None:
            now = datetime.datetime.now()
        if self.last_seen is None:
            return now < (self.created + self.timeout)
        else:
            return now < (self.last_seen + self.timeout)


def peer_certificate(session):
    # If not an OpenPGP certificate...
    if gnutls.library.functions.gnutls_certificate_type_get\
            (session._c_object) \
           != gnutls.library.constants.GNUTLS_CRT_OPENPGP:
        # ...do the normal thing
        return session.peer_certificate
    list_size = ctypes.c_uint()
    cert_list = gnutls.library.functions.gnutls_certificate_get_peers\
        (session._c_object, ctypes.byref(list_size))
    if list_size.value == 0:
        return None
    cert = cert_list[0]
    return ctypes.string_at(cert.data, cert.size)


def fingerprint(openpgp):
    # New empty GnuTLS certificate
    crt = gnutls.library.types.gnutls_openpgp_crt_t()
    gnutls.library.functions.gnutls_openpgp_crt_init\
        (ctypes.byref(crt))
    # New GnuTLS "datum" with the OpenPGP public key
    datum = gnutls.library.types.gnutls_datum_t\
        (ctypes.cast(ctypes.c_char_p(openpgp),
                     ctypes.POINTER(ctypes.c_ubyte)),
         ctypes.c_uint(len(openpgp)))
    # Import the OpenPGP public key into the certificate
    ret = gnutls.library.functions.gnutls_openpgp_crt_import\
        (crt,
         ctypes.byref(datum),
         gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)
    # New buffer for the fingerprint
    buffer = ctypes.create_string_buffer(20)
    buffer_length = ctypes.c_size_t()
    # Get the fingerprint from the certificate into the buffer
    gnutls.library.functions.gnutls_openpgp_crt_get_fingerprint\
        (crt, ctypes.byref(buffer), ctypes.byref(buffer_length))
    # Deinit the certificate
    gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)
    # Convert the buffer to a Python bytestring
    fpr = ctypes.string_at(buffer, buffer_length.value)
    # Convert the bytestring to hexadecimal notation
    hex_fpr = u''.join(u"%02X" % ord(char) for char in fpr)
    return hex_fpr


class tcp_handler(SocketServer.BaseRequestHandler, object):
    """A TCP request handler class.
    Instantiated by IPv6_TCPServer for each request to handle it.
    Note: This will run in its own forked process."""
    
    def handle(self):
        logger.debug(u"TCP connection from: %s",
                     unicode(self.client_address))
        session = gnutls.connection.ClientSession(self.request,
                                                  gnutls.connection.\
                                                  X509Credentials())
        
        #priority = ':'.join(("NONE", "+VERS-TLS1.1", "+AES-256-CBC",
        #                "+SHA1", "+COMP-NULL", "+CTYPE-OPENPGP",
        #                "+DHE-DSS"))
        priority = "SECURE256"
        
        gnutls.library.functions.gnutls_priority_set_direct\
            (session._c_object, priority, None);
        
        try:
            session.handshake()
        except gnutls.errors.GNUTLSError, error:
            logger.debug(u"Handshake failed: %s", error)
            # Do not run session.bye() here: the session is not
            # established.  Just abandon the request.
            return
        try:
            fpr = fingerprint(peer_certificate(session))
        except (TypeError, gnutls.errors.GNUTLSError), error:
            logger.debug(u"Bad certificate: %s", error)
            session.bye()
            return
        logger.debug(u"Fingerprint: %s", fpr)
        client = None
        for c in clients:
            if c.fingerprint == fpr:
                client = c
                break
        # Have to check if client.still_valid(), since it is possible
        # that the client timed out while establishing the GnuTLS
        # session.
        if (not client) or (not client.still_valid()):
            if client:
                logger.debug(u"Client %(name)s is invalid",
                             vars(client))
            else:
                logger.debug(u"Client not found for fingerprint: %s",
                             fpr)
            session.bye()
            return
        sent_size = 0
        while sent_size < len(client.secret):
            sent = session.send(client.secret[sent_size:])
            logger.debug(u"Sent: %d, remaining: %d",
                         sent, len(client.secret)
                         - (sent_size + sent))
            sent_size += sent
        session.bye()


class IPv6_TCPServer(SocketServer.ForkingTCPServer, object):
    """IPv6 TCP server.  Accepts 'None' as address and/or port.
    Attributes:
        options:        Command line options
        clients:        Set() of Client objects
    """
    address_family = socket.AF_INET6
    def __init__(self, *args, **kwargs):
        if "options" in kwargs:
            self.options = kwargs["options"]
            del kwargs["options"]
        if "clients" in kwargs:
            self.clients = kwargs["clients"]
            del kwargs["clients"]
        return super(type(self), self).__init__(*args, **kwargs)
    def server_bind(self):
        """This overrides the normal server_bind() function
        to bind to an interface if one was specified, and also NOT to
        bind to an address or port if they were not specified."""
        if self.options.interface:
            if not hasattr(socket, "SO_BINDTODEVICE"):
                # From /usr/include/asm-i486/socket.h
                socket.SO_BINDTODEVICE = 25
            try:
                self.socket.setsockopt(socket.SOL_SOCKET,
                                       socket.SO_BINDTODEVICE,
                                       self.options.interface)
            except socket.error, error:
                if error[0] == errno.EPERM:
                    logger.warning(u"No permission to"
                                   u" bind to interface %s",
                                   self.options.interface)
                else:
                    raise error
        # Only bind(2) the socket if we really need to.
        if self.server_address[0] or self.server_address[1]:
            if not self.server_address[0]:
                in6addr_any = "::"
                self.server_address = (in6addr_any,
                                       self.server_address[1])
            elif self.server_address[1] is None:
                self.server_address = (self.server_address[0],
                                       0)
            return super(type(self), self).server_bind()


def string_to_delta(interval):
    """Parse a string and return a datetime.timedelta

    >>> string_to_delta('7d')
    datetime.timedelta(7)
    >>> string_to_delta('60s')
    datetime.timedelta(0, 60)
    >>> string_to_delta('60m')
    datetime.timedelta(0, 3600)
    >>> string_to_delta('24h')
    datetime.timedelta(1)
    >>> string_to_delta(u'1w')
    datetime.timedelta(7)
    """
    try:
        suffix=unicode(interval[-1])
        value=int(interval[:-1])
        if suffix == u"d":
            delta = datetime.timedelta(value)
        elif suffix == u"s":
            delta = datetime.timedelta(0, value)
        elif suffix == u"m":
            delta = datetime.timedelta(0, 0, 0, 0, value)
        elif suffix == u"h":
            delta = datetime.timedelta(0, 0, 0, 0, 0, value)
        elif suffix == u"w":
            delta = datetime.timedelta(0, 0, 0, 0, 0, 0, value)
        else:
            raise ValueError
    except (ValueError, IndexError):
        raise ValueError
    return delta


def add_service():
    """From the Avahi server example code"""
    global group, serviceName, serviceType, servicePort, serviceTXT, \
           domain, host
    if group is None:
        group = dbus.Interface(
                bus.get_object( avahi.DBUS_NAME,
                                server.EntryGroupNew()),
                avahi.DBUS_INTERFACE_ENTRY_GROUP)
        group.connect_to_signal('StateChanged',
                                entry_group_state_changed)
    logger.debug(u"Adding service '%s' of type '%s' ...",
                 serviceName, serviceType)
    
    group.AddService(
            serviceInterface,           # interface
            avahi.PROTO_INET6,          # protocol
            dbus.UInt32(0),             # flags
            serviceName, serviceType,
            domain, host,
            dbus.UInt16(servicePort),
            avahi.string_array_to_txt_array(serviceTXT))
    group.Commit()


def remove_service():
    """From the Avahi server example code"""
    global group
    
    if not group is None:
        group.Reset()


def server_state_changed(state):
    """From the Avahi server example code"""
    if state == avahi.SERVER_COLLISION:
        logger.warning(u"Server name collision")
        remove_service()
    elif state == avahi.SERVER_RUNNING:
        add_service()


def entry_group_state_changed(state, error):
    """From the Avahi server example code"""
    global serviceName, server, rename_count
    
    logger.debug(u"state change: %i", state)
    
    if state == avahi.ENTRY_GROUP_ESTABLISHED:
        logger.debug(u"Service established.")
    elif state == avahi.ENTRY_GROUP_COLLISION:
        
        rename_count = rename_count - 1
        if rename_count > 0:
            name = server.GetAlternativeServiceName(name)
            logger.warning(u"Service name collision, "
                           u"changing name to '%s' ...", name)
            remove_service()
            add_service()
            
        else:
            logger.error(u"No suitable service name found "
                         u"after %i retries, exiting.",
                         n_rename)
            main_loop.quit()
    elif state == avahi.ENTRY_GROUP_FAILURE:
        logger.error(u"Error in group state changed %s",
                     unicode(error))
        main_loop.quit()
        return


def if_nametoindex(interface):
    """Call the C function if_nametoindex()"""
    try:
        libc = ctypes.cdll.LoadLibrary("libc.so.6")
        return libc.if_nametoindex(interface)
    except (OSError, AttributeError):
        if "struct" not in sys.modules:
            import struct
        if "fcntl" not in sys.modules:
            import fcntl
        SIOCGIFINDEX = 0x8933      # From /usr/include/linux/sockios.h
        s = socket.socket()
        ifreq = fcntl.ioctl(s, SIOCGIFINDEX,
                            struct.pack("16s16x", interface))
        s.close()
        interface_index = struct.unpack("I", ifreq[16:20])[0]
        return interface_index


if __name__ == '__main__':
    parser = OptionParser()
    parser.add_option("-i", "--interface", type="string",
                      default=None, metavar="IF",
                      help="Bind to interface IF")
    parser.add_option("--cert", type="string", default="cert.pem",
                      metavar="FILE",
                      help="Public key certificate PEM file to use")
    parser.add_option("--key", type="string", default="key.pem",
                      metavar="FILE",
                      help="Private key PEM file to use")
    parser.add_option("--ca", type="string", default="ca.pem",
                      metavar="FILE",
                      help="Certificate Authority certificate PEM file to use")
    parser.add_option("--crl", type="string", default="crl.pem",
                      metavar="FILE",
                      help="Certificate Revokation List PEM file to use")
    parser.add_option("-p", "--port", type="int", default=None,
                      help="Port number to receive requests on")
    parser.add_option("--timeout", type="string", # Parsed later
                      default="1h",
                      help="Amount of downtime allowed for clients")
    parser.add_option("--interval", type="string", # Parsed later
                      default="5m",
                      help="How often to check that a client is up")
    parser.add_option("--check", action="store_true", default=False,
                      help="Run self-test")
    parser.add_option("--debug", action="store_true", default=False,
                      help="Debug mode")
    (options, args) = parser.parse_args()
    
    if options.check:
        import doctest
        doctest.testmod()
        sys.exit()
    
    # Parse the time arguments
    try:
        options.timeout = string_to_delta(options.timeout)
    except ValueError:
        parser.error("option --timeout: Unparseable time")
    try:
        options.interval = string_to_delta(options.interval)
    except ValueError:
        parser.error("option --interval: Unparseable time")
    
    # Parse config file
    defaults = { "checker": "sleep 1; fping -q -- %%(fqdn)s" }
    client_config = ConfigParser.SafeConfigParser(defaults)
    #client_config.readfp(open("secrets.conf"), "secrets.conf")
    client_config.read("mandos-clients.conf")
    
    # From the Avahi server example code
    DBusGMainLoop(set_as_default=True )
    main_loop = gobject.MainLoop()
    bus = dbus.SystemBus()
    server = dbus.Interface(
            bus.get_object( avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER ),
            avahi.DBUS_INTERFACE_SERVER )
    # End of Avahi example code
    
    debug = options.debug
    
    clients = Set()
    def remove_from_clients(client):
        clients.remove(client)
        if not clients:
            logger.debug(u"No clients left, exiting")
            main_loop.quit()
    
    clients.update(Set(Client(name=section, options=options,
                              stop_hook = remove_from_clients,
                              **(dict(client_config\
                                      .items(section))))
                       for section in client_config.sections()))
    for client in clients:
        client.start()
    
    tcp_server = IPv6_TCPServer((None, options.port),
                                tcp_handler,
                                options=options,
                                clients=clients)
    # Find out what random port we got
    servicePort = tcp_server.socket.getsockname()[1]
    logger.debug(u"Now listening on port %d", servicePort)
    
    if options.interface is not None:
        serviceInterface = if_nametoindex(options.interface)
    
    # From the Avahi server example code
    server.connect_to_signal("StateChanged", server_state_changed)
    server_state_changed(server.GetState())
    # End of Avahi example code
    
    gobject.io_add_watch(tcp_server.fileno(), gobject.IO_IN,
                         lambda *args, **kwargs:
                         tcp_server.handle_request(*args[2:],
                                                   **kwargs) or True)
    try:
        main_loop.run()
    except KeyboardInterrupt:
        print
    
    # Cleanup here

    # From the Avahi server example code
    if not group is None:
        group.Free()
    # End of Avahi example code
    
    for client in clients:
        client.stop_hook = None
        client.stop()