onion-grater 29.4 KB
Newer Older
1
#!/usr/bin/python3 -u
2

3
# This filter proxy allows fine-grained access whitelists of commands
4 5
# (and their argunents) and events on a per-application basis, stored
# in:
6
#
7
#     /etc/onion-grater.d/
8
#
9 10
# that are pretty self-explanatory as long as you understand the Tor
# ControlPort language. The format is expressed in YAML where the
anonym's avatar
anonym committed
11 12
# top-level is supposed to be a list, where each element is a
# dictionary looking something like this:
13
#
14
#     - name: blabla
15 16 17 18
#       apparmor-profiles:
#         - path_to_executable_if_that_is_the_name_of_the_apparmor_profile
#         # or
#         - explicit_apparmor_profile_name
19
#         ...
20
#       users:
anonym's avatar
anonym committed
21 22
#         - user
#         ...
23
#       hosts:
anonym's avatar
anonym committed
24
#         - host
25 26
#         ...
#       commands:
anonym's avatar
anonym committed
27
#         command:
28
#           - command_arg_rule
29 30
#           ...
#         ...
31 32 33
#       confs:
#         conf:
#           - conf_arg_rule
34
#           ...
35
#         ...
36
#       events:
anonym's avatar
anonym committed
37 38 39
#         event:
#           event_option: event_option_value
#           ...
40 41
#         ...
#
42 43 44 45 46 47
# `name` (optional) is a string which gives an internal name, useful
# for debugging. When not given, filters will default to the name of
# the file (excluding extension) they were read from (so there can be
# duplicates!). It is advisable to define one filter per file, and
# give helpful filenames instead of using this field.
#
48
# A filter is matched if for each of the relevant qualifiers at
anonym's avatar
anonym committed
49
# least one of the elements match the client. For local (loopback)
50
# clients the following qualifiers are relevant:
anonym's avatar
anonym committed
51
#
52 53 54 55
# * `apparmor-profiles`: a list of strings, each being the name
#   of the AppArmor profile applied to the binary or script of the client,
#   with `*` matching anything. While this matcher always works for binaries,
#   it only works for scripts with an enabled AppArmor profile (not
anonym's avatar
anonym committed
56 57
#   necessarily enforced, complain mode is good enough).
#
58
# * `users`: a list of strings, each describing the user of the
anonym's avatar
anonym committed
59 60
#   client with `*` matching anything.
#
61 62
# For remote (non-local) clients, the following qualifiers are
# relevant:
anonym's avatar
anonym committed
63
#
64
# * hosts: a list of strings, each describing the IPv4 address
anonym's avatar
anonym committed
65 66
#   of the client with `*` matching anything.
#
67 68
# A filter can serve both local and remote clients by having
# qualifiers of both types.
anonym's avatar
anonym committed
69 70 71 72 73 74
#
# `commands` (optional) is a list where each item is a dictionary with
# the obligatory `pattern` key, which is a regular expression that is
# matched against the full argument part of the command. The default
# behavior is to just proxy the line through if matched, but it can be
# altered with these keys:
anonym's avatar
anonym committed
75 76 77
#
# * `replacement`: this rewrites the arguments. The value is a Python
#   format string (str.format()) which will be given the match groups
anonym's avatar
anonym committed
78
#   from the match of `pattern`. The rewritten command is then proxied
79 80 81 82 83 84 85
#   without the need to match any rule. There are also some special
#   patterns that will be replaced as follows:
#
#   - {client-address}: the client's IP address
#   - {client-port}: the client's port
#   - {server-address}: the server's IP address
#   - {server-port}: the server's (listening) port
anonym's avatar
anonym committed
86
#
87 88 89 90 91 92
# * `response`: a list of dictionaries, where the `pattern` and
#   `replacement` keys work exactly as for commands arguments, but now
#   for the response. Note that this means that the response is left
#   intact if `pattern` doesn't match it, and if many `pattern`:s
#   match, only the first one (in the order listed) will trigger a
#   replacement.
anonym's avatar
anonym committed
93 94 95
#
# If a simple regex (as string) is given, it is assumed to be the
# `pattern` which allows a short-hand for this common type of rule.
anonym's avatar
anonym committed
96
#
anonym's avatar
anonym committed
97 98 99
# Note that to allow a command to be run without arguments, the empty
# string must be explicitly given as a `pattern`. Hence, an empty
# argument list does not allow any use of the command.
100
#
101 102 103
# `confs` (optional) is a dictionary, and it's just syntactic sugar to
# generate GETCONF/SETCONF rules. If a key exists, GETCONF of the
# keyname is allowed, and if it has a non-empty list as value, those
104
# values are allowed to be set. The empty string means that resetting
105 106 107
# it is allowed. This is very useful for applications that like to
# SETCONF on multiple configurations at the same time.
#
anonym's avatar
anonym committed
108
# `events` (optional) is a dictionary where the key represents the
109
# event. If a key exists the event is allowed. The value is another
anonym's avatar
anonym committed
110 111 112 113 114 115
# dictionary of options:
#
# * `suppress`: a boolean determining whether we should just fool the
#   client that it has subscribed to the event (i.e. the client
#   request is not filtered) while we suppress them.
#
116 117 118 119
# * `response`: a dictionary, where the `pattern` and `replacement`
#   keys work exactly as for `response` for commands, but now for the
#   events.
#
anonym's avatar
anonym committed
120 121 122
# `restrict-stream-events` (optional) is a boolean, and if set any
# STREAM events sent to the client (after it has subscribed to them)
# will be restricted to those belonging to the client itself. This
123 124
# option only works for local clients and will be unset for remote
# clients.
125

anonym's avatar
anonym committed
126
import argparse
127
import fcntl
128
import glob
129
import ipaddress
130
import os.path
anonym's avatar
anonym committed
131 132
import psutil
import re
133
import socket
anonym's avatar
anonym committed
134
import socketserver
135 136
import stem
import stem.control
137
import stem.connection
138
import struct
139
import sys
140
import textwrap
anonym's avatar
anonym committed
141
import yaml
142

143
DEFAULT_LISTEN_ADDRESS = 'localhost'
144
DEFAULT_LISTEN_PORT = 9051
145 146
DEFAULT_COOKIE_PATH = '/run/tor/control.authcookie'
DEFAULT_CONTROL_SOCKET_PATH = '/run/tor/control'
anonym's avatar
anonym committed
147

148

149
class NoRewriteMatch(RuntimeError):
150 151 152
    """
    Error when no matching rewrite rule was found but one was expected.
    """
153 154
    pass

155

156 157 158 159 160
def log(msg):
    print(msg, file=sys.stderr)
    sys.stderr.flush()


161 162
def pid_of_laddr(address):
    try:
163
        return next(conn for conn in psutil.net_connections()
164 165 166 167 168
                    if conn.laddr == address).pid
    except StopIteration:
        return None


169
def apparmor_profile_of_pid(pid):
170 171 172 173 174
    # Here we leverage AppArmor's in-kernel solution for determining
    # the exact executable invoked. Looking at /proc/pid/exe when an
    # interpreted script is running will just point to the
    # interpreter's binary, which is not fine-grained enough, but
    # AppArmor will be aware of which script is running for processes
175 176 177
    # using one of its profiles. However, we fallback to /proc/pid/exe
    # in case there is no AppArmor profile, so the only unsupported
    # mode here is unconfined scripts.
178
    enabled_aa_profile_re = r'^(.+) \((?:complain|enforce)\)$'
179 180
    with open('/proc/{}/attr/current'.format(str(pid)), "rb") as fh:
        aa_profile_status = str(fh.read().strip(), 'UTF-8')
181 182 183
        apparmor_profile_match = re.match(enabled_aa_profile_re, aa_profile_status)
        if apparmor_profile_match:
            return apparmor_profile_match.group(1)
184 185
        else:
            return psutil.Process(pid).exe()
186 187


188 189 190 191 192 193 194 195 196
def get_ip_address(ifname):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    return socket.inet_ntoa(fcntl.ioctl(
        s.fileno(),
        0x8915,  # SIOCGIFADDR
        struct.pack('256s', bytes(ifname[:15], 'utf-8'))
    )[20:24])


197
class FilteredControlPortProxySession:
198 199 200 201 202 203 204
    """
    Class used to deal with a single session, delegated from the handler
    (FilteredControlPortProxyHandler). Its main job is proxying the traffic
    between the client and the real control port, blocking or rewriting
    it as dictated by the filter rule set.
    """

205 206
    # Limit the length of a line, to prevent DoS attacks trying to
    # crash this filter proxy by sending infinitely long lines.
207
    MAX_LINESIZE = 10*1024
208 209 210 211

    def __init__(self, handler):
        self.allowed_commands = handler.allowed_commands
        self.allowed_events = handler.allowed_events
212
        self.client_address = handler.client_address
213 214 215 216 217 218 219 220 221 222
        self.client_pid = handler.client_pid
        self.controller = handler.controller
        self.debug_log = handler.debug_log
        self.filter_name = handler.filter_name
        self.restrict_stream_events = handler.restrict_stream_events
        self.rfile = handler.rfile
        self.server_address = handler.server_address
        self.wfile = handler.wfile
        self.client_streams = set()
        self.subscribed_event_listeners = []
223

224
    def debug_log_send(self, line):
225
        if global_args.print_responses:
226
            self.debug_log(line, format_multiline=True, sep=': <- ')
227

228
    def debug_log_recv(self, line):
229
        if global_args.print_requests:
230
            self.debug_log(line, format_multiline=True, sep=': -> ')
231

232
    def debug_log_rewrite(self, kind, old, new):
233 234
        if kind not in ['command', 'received event', 'response'] or \
           (kind == 'command' and not global_args.print_responses) or \
235 236
           (kind in ['received event', 'response']
            and not global_args.print_requests):
237 238 239 240
            return
        if new != old:
            old = textwrap.indent(old.strip(), ' '*4)
            new = textwrap.indent(new.strip(), ' '*4)
241 242
            self.debug_log("rewrote {}:\n{}\nto:\n{}".format(kind, old, new),
                           format_multiline=False)
243

244
    def respond(self, line, raw=False):
245 246
        if line.isspace():
            return
247 248
        self.debug_log_send(line)
        self.wfile.write(bytes(line, 'ascii'))
249 250
        if not raw:
            self.wfile.write(bytes("\r\n", 'ascii'))
251
        self.wfile.flush()
252

253 254
    def get_rule(self, cmd, arg_str):
        allowed_args = self.allowed_commands.get(cmd, [])
255
        return next((rule for rule in allowed_args
256
                     if re.match(rule['pattern'] + "$", arg_str)), None)
257

258
    def proxy_line(self, line, args_rewriter=None, response_rewriter=None):
259 260
        if args_rewriter:
            new_line = args_rewriter(line)
261
            self.debug_log_rewrite('command', line, new_line)
262
            line = new_line
263
        response = self.controller.msg(line.strip()).raw_content()
264
        if response_rewriter:
265
            new_response = response_rewriter(response)
266
            self.debug_log_rewrite('response', response, new_response)
267
            response = new_response
268
        self.respond(response, raw=True)
269

270 271 272 273
    def filter_line(self, line):
        self.debug_log("command filtered: {}".format(line))
        self.respond("510 Command filtered")

274
    def rewrite_line(self, replacers, line):
275
        builtin_replacers = {
276 277 278 279
            'client-address': self.client_address[0],
            'client-port':    str(self.client_address[1]),
            'server-address': self.server_address[0],
            'server-port':    str(self.server_address[1]),
280
        }
281 282 283 284
        terminator = ''
        if line[-2:] == "\r\n":
            terminator = "\r\n"
            line = line[:-2]
285 286 287
        for r in replacers:
            match = re.match(r['pattern'] + "$", line)
            if match:
288 289 290
                return r['replacement'].format(
                    *match.groups(), **builtin_replacers
                ) + terminator
291
        raise NoRewriteMatch()
292

293
    def rewrite_matched_line(self, replacers, line):
294
        try:
295
            return self.rewrite_line(replacers, line)
296
        except NoRewriteMatch:
297 298
            return line

299
    def rewrite_matched_lines(self, replacers, lines):
300
        split_lines = lines.strip().split("\r\n")
301
        return "\r\n".join([self.rewrite_matched_line(replacers, line)
302
                            for line in split_lines]) + "\r\n"
303

304
    def event_cb(self, event, event_rewriter=None):
305
        if self.restrict_stream_events and \
306
           isinstance(event, stem.response.events.StreamEvent) and \
307
           not global_args.disable_filtering:
308
            if event.id not in self.client_streams:
309 310
                if event.status in [stem.StreamStatus.NEW,
                                    stem.StreamStatus.NEWRESOLVE] and \
311 312 313
                   self.client_pid == pid_of_laddr((event.source_address,
                                                    event.source_port)):
                    self.client_streams.add(event.id)
314 315 316 317
                else:
                    return
            elif event.status in [stem.StreamStatus.FAILED,
                                  stem.StreamStatus.CLOSED]:
318
                self.client_streams.remove(event.id)
319 320
        raw_event_content = event.raw_content()
        if event_rewriter:
321
            new_raw_event_content = event_rewriter(raw_event_content)
322
            self.debug_log_rewrite(
323 324 325
                'received event', raw_event_content, new_raw_event_content
            )
            raw_event_content = new_raw_event_content
326 327
            if raw_event_content.strip() == '':
                return
328
        self.respond(raw_event_content, raw=True)
329

330 331
    def update_event_subscriptions(self, events):
        for listener, event in self.subscribed_event_listeners:
332
            if event not in events:
333 334
                self.controller.remove_event_listener(listener)
                self.subscribed_event_listeners.remove((listener, event))
335
                if global_args.print_responses:
336
                    self.debug_log("unsubscribed from event '{}'".format(event))
anonym's avatar
anonym committed
337
        for event in events:
338
            if any(event == event_ for _, event_ in self.subscribed_event_listeners):
339
                if global_args.print_responses:
340 341
                    self.debug_log("already subscribed to event '{}'"
                                   .format(event))
342
                continue
343
            rule = self.allowed_events.get(event, {}) or {}
anonym's avatar
anonym committed
344 345 346 347
            if not rule.get('suppress', False) or \
               global_args.disable_filtering:
                event_rewriter = None
                if 'response' in rule:
348
                    replacers = rule['response']
anonym's avatar
anonym committed
349
                    def _event_rewriter(line):
350
                        return self.rewrite_matched_line(replacers, line)
anonym's avatar
anonym committed
351 352
                    event_rewriter = _event_rewriter
                def _event_cb(event):
353 354
                    self.event_cb(event, event_rewriter=event_rewriter)
                self.controller.add_event_listener(
anonym's avatar
anonym committed
355 356
                    _event_cb, getattr(stem.control.EventType, event)
                )
357
                self.subscribed_event_listeners.append((_event_cb, event))
358
                if global_args.print_responses:
359
                    self.debug_log("subscribed to event '{}'".format(event))
360 361
            else:
                if global_args.print_responses:
362
                    self.debug_log("suppressed subscription to event '{}'"
363
                                   .format(event))
364
        self.respond("250 OK")
365

366 367 368 369 370 371 372 373
    def handle(self):
        while True:
            binary_line = self.rfile.readline(self.MAX_LINESIZE)
            if binary_line == b'':
                # Deal with clients that close the socket without a QUIT.
                break
            line = str(binary_line, 'ascii')
            if line.isspace():
374 375
                self.debug_log('ignoring received empty (or whitespace-only) '
                               + 'line')
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
                continue
            match = re.match(
                r'(?P<cmd>\S+)(?P<cmd_arg_sep>\s*)(?P<arg_str>[^\r\n]*)\r?\n$',
                line
            )
            if not match:
                self.debug_log("received bad line (escapes made explicit): " +
                               repr(line))
                # Hopefully the next line is ok...
                continue
            self.debug_log_recv(line)
            cmd         = match.group('cmd')
            cmd_arg_sep = match.group('cmd_arg_sep')
            arg_str     = match.group('arg_str')
            args = arg_str.split()
            cmd = cmd.upper()

            if cmd == "PROTOCOLINFO":
                # Stem calls PROTOCOLINFO before authenticating. Tell the
                # client that there is no authentication.
                self.respond("250-PROTOCOLINFO 1")
                self.respond("250-AUTH METHODS=NULL")
                self.respond("250-VERSION Tor=\"{}\""
                             .format(self.controller.get_version()))
                self.respond("250 OK")

            elif cmd == "AUTHENTICATE":
                # We have already authenticated, and the filtered port is
                # access-restricted according to our filter instead.
                self.respond("250 OK")

            elif cmd == "QUIT":
                self.respond("250 closing connection")
                break

            elif cmd == "SETEVENTS":
                # The control language doesn't care about case for
                # the event type.
                events = [event.upper() for event in args]
415 416 417 418 419
                if not global_args.disable_filtering and \
                   any(event not in self.allowed_events for event in events):
                    self.filter_line(line)
                else:
                    self.update_event_subscriptions(events)
420

421
            else:
422
                rule = self.get_rule(cmd, arg_str)
423
                if rule is None and global_args.disable_filtering:
424
                    rule = {}
425
                if rule is not None:
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
                    args_rewriter = None
                    response_rewriter = None

                    if 'response' in rule:
                        def _response_rewriter(lines):
                            return self.rewrite_matched_lines(rule['response'],
                                                              lines)
                        response_rewriter = _response_rewriter

                    if 'replacement' in rule:
                        def _args_rewriter(line):
                            # We also want to match the command in `line`
                            # and add it back to the replacement string.
                            # We make sure to keep the exact white spaces
                            # separating the command and arguments, to not
                            # rewrite the line unnecessarily.
                            prefix = cmd + cmd_arg_sep
                            replacer = {
                                'pattern':     prefix + rule['pattern'],
                                'replacement': prefix + rule['replacement']
                            }
                            return self.rewrite_line([replacer], line)
                        args_rewriter = _args_rewriter

                    self.proxy_line(line, args_rewriter=args_rewriter,
                                    response_rewriter=response_rewriter)
                else:
453
                    self.filter_line(line)
454 455


456
class FilteredControlPortProxyHandler(socketserver.StreamRequestHandler):
457 458 459 460 461 462 463
    """
    Class handing each control port connection and collecting information
    about the origin and using it to find a matching filter rule set. It
    then delegates the session handling (the actual filtering) to a
    FilteredControlPortProxySession object.
    """

464
    def debug_log(self, line, format_multiline=False, sep=': '):
465 466 467 468 469 470
        line = line.strip()
        if format_multiline and "\n" in line:
            sep += "(multi-line)\n"
            line = textwrap.indent(line, ' '*4)
        log(self.client_desc + sep + line)

471 472
    def setup(self):
        super(type(self), self).setup()
473 474 475 476 477 478 479
        self.allowed_commands = {}
        self.allowed_events = {}
        self.client_desc = None
        self.client_pid = None
        self.client_streams = set()
        self.controller = None
        self.filter_name = None
480
        self.filters = []
481 482 483
        self.restrict_stream_events = False
        self.server_address = self.server.server_address
        self.subscribed_event_listeners = []
484
        for filter_file in glob.glob('/etc/onion-grater.d/*.yml'):
485 486
            try:
                with open(filter_file, "rb") as fh:
487
                    filters = yaml.safe_load(fh.read())
488 489 490 491 492
                    name = re.sub(r'\.yml$', '', os.path.basename(filter_file))
                    for filter_ in filters:
                        if name not in filter_:
                            filter_['name'] = name
                    self.filters += filters
493 494 495
            except (yaml.parser.ParserError, yaml.scanner.ScannerError) as err:
                log("filter '{}' has bad YAML and was not loaded: {}"
                    .format(filter_file, str(err)))
496

497
    def add_allowed_commands(self, commands):
498 499 500 501 502
        for cmd in commands:
            allowed_args = commands[cmd]
            # An empty argument list allows nothing, but will
            # make some code below easier than if it can be
            # None as well.
503
            if allowed_args is None:
504 505 506 507
                allowed_args = []
            for i in range(len(allowed_args)):
                if isinstance(allowed_args[i], str):
                    allowed_args[i] = {'pattern': allowed_args[i]}
508
            self.allowed_commands[cmd.upper()] = allowed_args
509

510
    def add_allowed_confs_commands(self, confs):
511 512 513
        combined_getconf_rule = {'pattern': "(" + "|".join([
            key for key in confs]) + ")"}
        setconf_reset_part = "\s*|\s*".join([
514 515
            key for key in confs
            if isinstance(confs[key], list) and '' in confs[key]]
516 517 518 519
        )
        setconf_assignment_part = "\s*|\s*".join([
            "{}=({})".format(
                key, "|".join(confs[key])
520 521 522
            )
            for key in confs
            if isinstance(confs[key], list) and len(confs[key]) > 0])
523 524 525 526 527 528 529 530 531 532
        setconf_parts = []
        for part in [setconf_reset_part, setconf_assignment_part]:
            if part and part != '':
                setconf_parts.append(part)
        combined_setconf_rule = {
            'pattern': "({})+".format("\s*|\s*".join(setconf_parts))
        }
        for cmd, rule in [('GETCONF', combined_getconf_rule),
                          ('SETCONF', combined_setconf_rule)]:
            if rule['pattern'] != "()+":
533 534 535
                if cmd not in self.allowed_commands:
                    self.allowed_commands[cmd] = []
                self.allowed_commands[cmd].append(rule)
536

537
    def add_allowed_events(self, events):
538 539 540 541
        for event in events:
            opts = events[event]
            # Same as for the `commands` argument list, let's
            # add an empty dict to simplify later code.
542
            if opts is None:
543
                opts = {}
544 545 546
            self.allowed_events[event.upper()] = opts

    def match_and_parse_filter(self, matchers):
547 548 549
        matched_filters = [filter_ for filter_ in self.filters
                           if all(any(val == expected_val or val == '*'
                                      for val in filter_.get(key, []))
550 551
                                  for key, expected_val in matchers)]
        if len(matched_filters) == 0:
552
            return
553 554 555 556
        elif len(matched_filters) > 1:
            raise RuntimeError('multiple filters matched: ' +
                               ', '.join(matched_filters))
        matched_filter = matched_filters[0]
557
        self.filter_name = matched_filter['name']
558
        commands = matched_filter.get('commands', {}) or {}
559
        self.add_allowed_commands(commands)
560
        confs = matched_filter.get('confs', {}) or {}
561
        self.add_allowed_confs_commands(confs)
562
        events = matched_filter.get('events', {}) or {}
563 564
        self.add_allowed_events(events)
        self.restrict_stream_events = bool(matched_filter.get(
565 566 567
            'restrict-stream-events', False
        ))

568
    def connect_to_real_control_port(self):
569 570 571
        controller = None
        while not controller:
            controller = stem.connection.connect(control_socket=global_args.control_socket_path)
572
        stem.connection.authenticate_cookie(controller, cookie_path=global_args.control_cookie_path)
anonym's avatar
anonym committed
573
        return controller
574

575
    def handle(self):
576 577 578
        client_host = self.client_address[0]
        local_connection = ipaddress.ip_address(client_host).is_loopback
        if local_connection:
579
            self.client_pid = pid_of_laddr(self.client_address)
580 581
            # Deal with the race between looking up the PID, and the
            # client being killed before we find the PID.
582 583
            if not self.client_pid:
                return
584
            client_apparmor_profile = apparmor_profile_of_pid(self.client_pid)
585
            client_user = psutil.Process(self.client_pid).username()
anonym's avatar
anonym committed
586
            matchers = [
587 588
                ('apparmor-profiles', client_apparmor_profile),
                ('users',             client_user),
anonym's avatar
anonym committed
589
            ]
590
        else:
591
            self.client_pid = None
anonym's avatar
anonym committed
592
            matchers = [
593
                ('hosts', client_host),
anonym's avatar
anonym committed
594
            ]
595
        self.match_and_parse_filter(matchers)
596
        if local_connection:
597
            self.client_desc = '{aa_profile} (pid: {pid}, user: {user}, ' \
598
                               'port: {port}, filter: {filter_name})'.format(
599
                                   aa_profile=client_apparmor_profile,
600 601 602 603
                                   pid=self.client_pid,
                                   user=client_user,
                                   port=self.client_address[1],
                                   filter_name=self.filter_name
604
                               )
605
        else:
606 607
            self.client_desc = '{1}:{2} (filter: {0})'.format(
                self.filter_name, *self.client_address
608
            )
609 610
        if self.restrict_stream_events and not local_connection:
            self.debug_log(
611
                "filter '{}' has `restrict-stream-events` set "
anonym's avatar
anonym committed
612
                "and we are remote so the option was disabled"
613
                .format(self.filter_name)
anonym's avatar
anonym committed
614
            )
615 616 617 618 619 620 621
            self.restrict_stream_events = False

        if len(self.filters) == 0:
            status = 'no matching filter found, using an empty one'
        else:
            status = 'loaded filter: {}'.format(self.filter_name)
        log('{} connected: {}'.format(self.client_desc, status))
622
        if global_args.debug:
623
            log('Final rules:')
624
            log(yaml.dump({
625 626 627
                'commands': self.allowed_commands,
                'events': self.allowed_events,
                'restrict-stream-events': self.restrict_stream_events,
628
            }))
629
        disconnect_reason = "client quit"
630
        try:
631 632 633
            self.controller = self.connect_to_real_control_port()
            session = FilteredControlPortProxySession(self)
            session.handle()
634
        except (ConnectionResetError, BrokenPipeError) as err:
635
            # Handle clients disconnecting abruptly
636
            disconnect_reason = str(err)
637 638 639
        except stem.SocketError:
            # Handle client closing its socket abruptly
            disconnect_reason = "Client closed its socket"
640
        except stem.SocketClosed:
anonym's avatar
anonym committed
641
            # Handle Tor closing its socket abruptly
642
            disconnect_reason = "Tor closed its socket"
643
        finally:
644 645 646 647
            if self.controller:
                self.controller.close()
            log('{} disconnected: {}'.format(self.client_desc,
                                             disconnect_reason))
648 649


650
class FilteredControlPortProxy(socketserver.ThreadingTCPServer):
651 652 653 654
    """
    Simple subclass just setting some defaults differently.
    """

anonym's avatar
anonym committed
655
    # So we can restart when the listening port if in TIME_WAIT state
656 657 658 659 660 661 662
    # after an abrupt shutdown.
    allow_reuse_address = True
    # So all server threads immediately quit when the main thread
    # quits.
    daemon_threads = True


663
def main():
anonym's avatar
anonym committed
664
    parser = argparse.ArgumentParser()
665
    parser.add_argument(
666
        "--listen-address",
667 668
        type=str, metavar='ADDR', default=DEFAULT_LISTEN_ADDRESS,
        help="specifies the address on which the server listens " +
669 670
             "(default: {})".format(DEFAULT_LISTEN_ADDRESS)
    )
anonym's avatar
anonym committed
671
    parser.add_argument(
672
        "--listen-port",
673 674
        type=int, metavar='PORT', default=DEFAULT_LISTEN_PORT,
        help="specifies the port on which the server listens " +
675 676
             "(default: {})".format(DEFAULT_LISTEN_PORT)
    )
677 678 679 680 681 682
    parser.add_argument(
        "--listen-interface",
        type=str, metavar='INTERFACE',
        help="specifies the interface on which the server listens " +
             "(default: NULL)"
    )
anonym's avatar
anonym committed
683
    parser.add_argument(
684
        "--control-cookie-path",
685 686
        type=str, metavar='PATH', default=DEFAULT_COOKIE_PATH,
        help="specifies the path to Tor's control authentication cookie " +
687 688
             "(default: {})".format(DEFAULT_COOKIE_PATH)
    )
anonym's avatar
anonym committed
689
    parser.add_argument(
690
        "--control-socket-path",
691 692
        type=str, metavar='PATH', default=DEFAULT_CONTROL_SOCKET_PATH,
        help="specifies the path to Tor's control socket " +
693 694
             "(default: {})".format(DEFAULT_CONTROL_SOCKET_PATH)
    )
695 696
    parser.add_argument(
        "--complain",
697 698
        action='store_true', default=False,
        help="disables all filtering and just prints the commands sent " +
699 700
             "by the client"
    )
701 702 703
    parser.add_argument(
        "--debug",
        action='store_true', default=False,
704 705
        help="prints all requests and responses"
    )
706 707 708
    # We put the argparse results in the global scope since it's
    # awkward to extend socketserver so additional data can be sent to
    # the request handler, where we need access to the arguments.
anonym's avatar
anonym committed
709 710
    global global_args
    global_args = parser.parse_args()
711 712 713 714 715
    # Deal with overlapping functionality between arguments
    global_args.__dict__['disable_filtering'] = global_args.complain
    global_args.__dict__['print_requests'] = global_args.complain or \
                                             global_args.debug
    global_args.__dict__['print_responses'] = global_args.debug
716 717 718 719 720 721 722 723
    if global_args.listen_interface:
        ip_address = get_ip_address(global_args.listen_interface)
        if global_args.debug:
            log("IP address for interface {} : {}".format(
                global_args.listen_interface,ip_address))
    else:
        ip_address = global_args.listen_address
    address = (ip_address, global_args.listen_port)
anonym's avatar
anonym committed
724 725
    server = FilteredControlPortProxy(address, FilteredControlPortProxyHandler)
    log("Tor control port filter started, listening on {}:{}".format(*address))
726 727 728 729
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        pass
730 731 732


if __name__ == "__main__":
733
    main()