summary refs log tree commit diff
path: root/synapse/api/auth.py
blob: 2178e623da8ec146d3ee0ca3bd86d71919d74097 (plain) (blame)
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
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from typing import Optional

import pymacaroons
from netaddr import IPAddress

from twisted.internet import defer
from twisted.web.server import Request

import synapse.types
from synapse import event_auth
from synapse.api.auth_blocking import AuthBlocking
from synapse.api.constants import EventTypes, Membership
from synapse.api.errors import (
    AuthError,
    Codes,
    InvalidClientTokenError,
    MissingClientTokenError,
)
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
from synapse.events import EventBase
from synapse.logging import opentracing as opentracing
from synapse.types import StateMap, UserID
from synapse.util.caches import register_cache
from synapse.util.caches.lrucache import LruCache
from synapse.util.metrics import Measure

logger = logging.getLogger(__name__)


AuthEventTypes = (
    EventTypes.Create,
    EventTypes.Member,
    EventTypes.PowerLevels,
    EventTypes.JoinRules,
    EventTypes.RoomHistoryVisibility,
    EventTypes.ThirdPartyInvite,
)

# guests always get this device id.
GUEST_DEVICE_ID = "guest_device"


class _InvalidMacaroonException(Exception):
    pass


class Auth(object):
    """
    FIXME: This class contains a mix of functions for authenticating users
    of our client-server API and authenticating events added to room graphs.
    """

    def __init__(self, hs):
        self.hs = hs
        self.clock = hs.get_clock()
        self.store = hs.get_datastore()
        self.state = hs.get_state_handler()

        self.token_cache = LruCache(10000)
        register_cache("cache", "token_cache", self.token_cache)

        self._auth_blocking = AuthBlocking(self.hs)

        self._account_validity = hs.config.account_validity
        self._track_appservice_user_ips = hs.config.track_appservice_user_ips
        self._macaroon_secret_key = hs.config.macaroon_secret_key

    @defer.inlineCallbacks
    def check_from_context(self, room_version: str, event, context, do_sig_check=True):
        prev_state_ids = yield defer.ensureDeferred(context.get_prev_state_ids())
        auth_events_ids = yield self.compute_auth_events(
            event, prev_state_ids, for_verification=True
        )
        auth_events = yield self.store.get_events(auth_events_ids)
        auth_events = {(e.type, e.state_key): e for e in auth_events.values()}

        room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
        event_auth.check(
            room_version_obj, event, auth_events=auth_events, do_sig_check=do_sig_check
        )

    @defer.inlineCallbacks
    def check_user_in_room(
        self,
        room_id: str,
        user_id: str,
        current_state: Optional[StateMap[EventBase]] = None,
        allow_departed_users: bool = False,
    ):
        """Check if the user is in the room, or was at some point.
        Args:
            room_id: The room to check.

            user_id: The user to check.

            current_state: Optional map of the current state of the room.
                If provided then that map is used to check whether they are a
                member of the room. Otherwise the current membership is
                loaded from the database.

            allow_departed_users: if True, accept users that were previously
                members but have now departed.

        Raises:
            AuthError if the user is/was not in the room.
        Returns:
            Deferred[Optional[EventBase]]:
                Membership event for the user if the user was in the
                room. This will be the join event if they are currently joined to
                the room. This will be the leave event if they have left the room.
        """
        if current_state:
            member = current_state.get((EventTypes.Member, user_id), None)
        else:
            member = yield defer.ensureDeferred(
                self.state.get_current_state(
                    room_id=room_id, event_type=EventTypes.Member, state_key=user_id
                )
            )
        membership = member.membership if member else None

        if membership == Membership.JOIN:
            return member

        # XXX this looks totally bogus. Why do we not allow users who have been banned,
        # or those who were members previously and have been re-invited?
        if allow_departed_users and membership == Membership.LEAVE:
            forgot = yield self.store.did_forget(user_id, room_id)
            if not forgot:
                return member

        raise AuthError(403, "User %s not in room %s" % (user_id, room_id))

    @defer.inlineCallbacks
    def check_host_in_room(self, room_id, host):
        with Measure(self.clock, "check_host_in_room"):
            latest_event_ids = yield self.store.is_host_joined(room_id, host)
            return latest_event_ids

    def can_federate(self, event, auth_events):
        creation_event = auth_events.get((EventTypes.Create, ""))

        return creation_event.content.get("m.federate", True) is True

    def get_public_keys(self, invite_event):
        return event_auth.get_public_keys(invite_event)

    @defer.inlineCallbacks
    def get_user_by_req(
        self,
        request: Request,
        allow_guest: bool = False,
        rights: str = "access",
        allow_expired: bool = False,
    ):
        """ Get a registered user's ID.

        Args:
            request: An HTTP request with an access_token query parameter.
            allow_guest: If False, will raise an AuthError if the user making the
                request is a guest.
            rights: The operation being performed; the access token must allow this
            allow_expired: If True, allow the request through even if the account
                is expired, or session token lifetime has ended. Note that
                /login will deliver access tokens regardless of expiration.

        Returns:
            defer.Deferred: resolves to a `synapse.types.Requester` object
        Raises:
            InvalidClientCredentialsError if no user by that token exists or the token
                is invalid.
            AuthError if access is denied for the user in the access token
        """
        try:
            ip_addr = self.hs.get_ip_from_request(request)
            user_agent = request.requestHeaders.getRawHeaders(
                b"User-Agent", default=[b""]
            )[0].decode("ascii", "surrogateescape")

            access_token = self.get_access_token_from_request(request)

            user_id, app_service = yield self._get_appservice_user_id(request)
            if user_id:
                request.authenticated_entity = user_id
                opentracing.set_tag("authenticated_entity", user_id)
                opentracing.set_tag("appservice_id", app_service.id)

                if ip_addr and self._track_appservice_user_ips:
                    yield self.store.insert_client_ip(
                        user_id=user_id,
                        access_token=access_token,
                        ip=ip_addr,
                        user_agent=user_agent,
                        device_id="dummy-device",  # stubbed
                    )

                return synapse.types.create_requester(user_id, app_service=app_service)

            user_info = yield self.get_user_by_access_token(
                access_token, rights, allow_expired=allow_expired
            )
            user = user_info["user"]
            token_id = user_info["token_id"]
            is_guest = user_info["is_guest"]

            # Deny the request if the user account has expired.
            if self._account_validity.enabled and not allow_expired:
                user_id = user.to_string()
                expiration_ts = yield self.store.get_expiration_ts_for_user(user_id)
                if (
                    expiration_ts is not None
                    and self.clock.time_msec() >= expiration_ts
                ):
                    raise AuthError(
                        403, "User account has expired", errcode=Codes.EXPIRED_ACCOUNT
                    )

            # device_id may not be present if get_user_by_access_token has been
            # stubbed out.
            device_id = user_info.get("device_id")

            if user and access_token and ip_addr:
                yield self.store.insert_client_ip(
                    user_id=user.to_string(),
                    access_token=access_token,
                    ip=ip_addr,
                    user_agent=user_agent,
                    device_id=device_id,
                )

            if is_guest and not allow_guest:
                raise AuthError(
                    403,
                    "Guest access not allowed",
                    errcode=Codes.GUEST_ACCESS_FORBIDDEN,
                )

            request.authenticated_entity = user.to_string()
            opentracing.set_tag("authenticated_entity", user.to_string())
            if device_id:
                opentracing.set_tag("device_id", device_id)

            return synapse.types.create_requester(
                user, token_id, is_guest, device_id, app_service=app_service
            )
        except KeyError:
            raise MissingClientTokenError()

    @defer.inlineCallbacks
    def _get_appservice_user_id(self, request):
        app_service = self.store.get_app_service_by_token(
            self.get_access_token_from_request(request)
        )
        if app_service is None:
            return None, None

        if app_service.ip_range_whitelist:
            ip_address = IPAddress(self.hs.get_ip_from_request(request))
            if ip_address not in app_service.ip_range_whitelist:
                return None, None

        if b"user_id" not in request.args:
            return app_service.sender, app_service

        user_id = request.args[b"user_id"][0].decode("utf8")
        if app_service.sender == user_id:
            return app_service.sender, app_service

        if not app_service.is_interested_in_user(user_id):
            raise AuthError(403, "Application service cannot masquerade as this user.")
        if not (yield self.store.get_user_by_id(user_id)):
            raise AuthError(403, "Application service has not registered this user")
        return user_id, app_service

    @defer.inlineCallbacks
    def get_user_by_access_token(
        self, token: str, rights: str = "access", allow_expired: bool = False,
    ):
        """ Validate access token and get user_id from it

        Args:
            token: The access token to get the user by
            rights: The operation being performed; the access token must
                allow this
            allow_expired: If False, raises an InvalidClientTokenError
                if the token is expired
        Returns:
            Deferred[dict]: dict that includes:
               `user` (UserID)
               `is_guest` (bool)
               `token_id` (int|None): access token id. May be None if guest
               `device_id` (str|None): device corresponding to access token
        Raises:
            InvalidClientTokenError if a user by that token exists, but the token is
                expired
            InvalidClientCredentialsError if no user by that token exists or the token
                is invalid
        """

        if rights == "access":
            # first look in the database
            r = yield self._look_up_user_by_access_token(token)
            if r:
                valid_until_ms = r["valid_until_ms"]
                if (
                    not allow_expired
                    and valid_until_ms is not None
                    and valid_until_ms < self.clock.time_msec()
                ):
                    # there was a valid access token, but it has expired.
                    # soft-logout the user.
                    raise InvalidClientTokenError(
                        msg="Access token has expired", soft_logout=True
                    )

                return r

        # otherwise it needs to be a valid macaroon
        try:
            user_id, guest = self._parse_and_validate_macaroon(token, rights)
            user = UserID.from_string(user_id)

            if rights == "access":
                if not guest:
                    # non-guest access tokens must be in the database
                    logger.warning("Unrecognised access token - not in store.")
                    raise InvalidClientTokenError()

                # Guest access tokens are not stored in the database (there can
                # only be one access token per guest, anyway).
                #
                # In order to prevent guest access tokens being used as regular
                # user access tokens (and hence getting around the invalidation
                # process), we look up the user id and check that it is indeed
                # a guest user.
                #
                # It would of course be much easier to store guest access
                # tokens in the database as well, but that would break existing
                # guest tokens.
                stored_user = yield self.store.get_user_by_id(user_id)
                if not stored_user:
                    raise InvalidClientTokenError("Unknown user_id %s" % user_id)
                if not stored_user["is_guest"]:
                    raise InvalidClientTokenError(
                        "Guest access token used for regular user"
                    )
                ret = {
                    "user": user,
                    "is_guest": True,
                    "token_id": None,
                    # all guests get the same device id
                    "device_id": GUEST_DEVICE_ID,
                }
            elif rights == "delete_pusher":
                # We don't store these tokens in the database
                ret = {
                    "user": user,
                    "is_guest": False,
                    "token_id": None,
                    "device_id": None,
                }
            else:
                raise RuntimeError("Unknown rights setting %s", rights)
            return ret
        except (
            _InvalidMacaroonException,
            pymacaroons.exceptions.MacaroonException,
            TypeError,
            ValueError,
        ) as e:
            logger.warning("Invalid macaroon in auth: %s %s", type(e), e)
            raise InvalidClientTokenError("Invalid macaroon passed.")

    def _parse_and_validate_macaroon(self, token, rights="access"):
        """Takes a macaroon and tries to parse and validate it. This is cached
        if and only if rights == access and there isn't an expiry.

        On invalid macaroon raises _InvalidMacaroonException

        Returns:
            (user_id, is_guest)
        """
        if rights == "access":
            cached = self.token_cache.get(token, None)
            if cached:
                return cached

        try:
            macaroon = pymacaroons.Macaroon.deserialize(token)
        except Exception:  # deserialize can throw more-or-less anything
            # doesn't look like a macaroon: treat it as an opaque token which
            # must be in the database.
            # TODO: it would be nice to get rid of this, but apparently some
            # people use access tokens which aren't macaroons
            raise _InvalidMacaroonException()

        try:
            user_id = self.get_user_id_from_macaroon(macaroon)

            guest = False
            for caveat in macaroon.caveats:
                if caveat.caveat_id == "guest = true":
                    guest = True

            self.validate_macaroon(macaroon, rights, user_id=user_id)
        except (pymacaroons.exceptions.MacaroonException, TypeError, ValueError):
            raise InvalidClientTokenError("Invalid macaroon passed.")

        if rights == "access":
            self.token_cache[token] = (user_id, guest)

        return user_id, guest

    def get_user_id_from_macaroon(self, macaroon):
        """Retrieve the user_id given by the caveats on the macaroon.

        Does *not* validate the macaroon.

        Args:
            macaroon (pymacaroons.Macaroon): The macaroon to validate

        Returns:
            (str) user id

        Raises:
            InvalidClientCredentialsError if there is no user_id caveat in the
                macaroon
        """
        user_prefix = "user_id = "
        for caveat in macaroon.caveats:
            if caveat.caveat_id.startswith(user_prefix):
                return caveat.caveat_id[len(user_prefix) :]
        raise InvalidClientTokenError("No user caveat in macaroon")

    def validate_macaroon(self, macaroon, type_string, user_id):
        """
        validate that a Macaroon is understood by and was signed by this server.

        Args:
            macaroon(pymacaroons.Macaroon): The macaroon to validate
            type_string(str): The kind of token required (e.g. "access",
                              "delete_pusher")
            user_id (str): The user_id required
        """
        v = pymacaroons.Verifier()

        # the verifier runs a test for every caveat on the macaroon, to check
        # that it is met for the current request. Each caveat must match at
        # least one of the predicates specified by satisfy_exact or
        # specify_general.
        v.satisfy_exact("gen = 1")
        v.satisfy_exact("type = " + type_string)
        v.satisfy_exact("user_id = %s" % user_id)
        v.satisfy_exact("guest = true")
        v.satisfy_general(self._verify_expiry)

        # access_tokens include a nonce for uniqueness: any value is acceptable
        v.satisfy_general(lambda c: c.startswith("nonce = "))

        v.verify(macaroon, self._macaroon_secret_key)

    def _verify_expiry(self, caveat):
        prefix = "time < "
        if not caveat.startswith(prefix):
            return False
        expiry = int(caveat[len(prefix) :])
        now = self.hs.get_clock().time_msec()
        return now < expiry

    @defer.inlineCallbacks
    def _look_up_user_by_access_token(self, token):
        ret = yield self.store.get_user_by_access_token(token)
        if not ret:
            return None

        # we use ret.get() below because *lots* of unit tests stub out
        # get_user_by_access_token in a way where it only returns a couple of
        # the fields.
        user_info = {
            "user": UserID.from_string(ret.get("name")),
            "token_id": ret.get("token_id", None),
            "is_guest": False,
            "device_id": ret.get("device_id"),
            "valid_until_ms": ret.get("valid_until_ms"),
        }
        return user_info

    def get_appservice_by_req(self, request):
        token = self.get_access_token_from_request(request)
        service = self.store.get_app_service_by_token(token)
        if not service:
            logger.warning("Unrecognised appservice access token.")
            raise InvalidClientTokenError()
        request.authenticated_entity = service.sender
        return defer.succeed(service)

    async def is_server_admin(self, user: UserID) -> bool:
        """ Check if the given user is a local server admin.

        Args:
            user: user to check

        Returns:
            True if the user is an admin
        """
        return await self.store.is_server_admin(user)

    def compute_auth_events(
        self, event, current_state_ids: StateMap[str], for_verification: bool = False,
    ):
        """Given an event and current state return the list of event IDs used
        to auth an event.

        If `for_verification` is False then only return auth events that
        should be added to the event's `auth_events`.

        Returns:
            defer.Deferred(list[str]): List of event IDs.
        """

        if event.type == EventTypes.Create:
            return defer.succeed([])

        # Currently we ignore the `for_verification` flag even though there are
        # some situations where we can drop particular auth events when adding
        # to the event's `auth_events` (e.g. joins pointing to previous joins
        # when room is publicly joinable). Dropping event IDs has the
        # advantage that the auth chain for the room grows slower, but we use
        # the auth chain in state resolution v2 to order events, which means
        # care must be taken if dropping events to ensure that it doesn't
        # introduce undesirable "state reset" behaviour.
        #
        # All of which sounds a bit tricky so we don't bother for now.

        auth_ids = []
        for etype, state_key in event_auth.auth_types_for_event(event):
            auth_ev_id = current_state_ids.get((etype, state_key))
            if auth_ev_id:
                auth_ids.append(auth_ev_id)

        return defer.succeed(auth_ids)

    async def check_can_change_room_list(self, room_id: str, user: UserID):
        """Determine whether the user is allowed to edit the room's entry in the
        published room list.

        Args:
            room_id
            user
        """

        is_admin = await self.is_server_admin(user)
        if is_admin:
            return True

        user_id = user.to_string()
        await self.check_user_in_room(room_id, user_id)

        # We currently require the user is a "moderator" in the room. We do this
        # by checking if they would (theoretically) be able to change the
        # m.room.canonical_alias events
        power_level_event = await self.state.get_current_state(
            room_id, EventTypes.PowerLevels, ""
        )

        auth_events = {}
        if power_level_event:
            auth_events[(EventTypes.PowerLevels, "")] = power_level_event

        send_level = event_auth.get_send_level(
            EventTypes.CanonicalAlias, "", power_level_event
        )
        user_level = event_auth.get_user_power_level(user_id, auth_events)

        return user_level >= send_level

    @staticmethod
    def has_access_token(request: Request):
        """Checks if the request has an access_token.

        Returns:
            bool: False if no access_token was given, True otherwise.
        """
        query_params = request.args.get(b"access_token")
        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
        return bool(query_params) or bool(auth_headers)

    @staticmethod
    def get_access_token_from_request(request: Request):
        """Extracts the access_token from the request.

        Args:
            request: The http request.
        Returns:
            unicode: The access_token
        Raises:
            MissingClientTokenError: If there isn't a single access_token in the
                request
        """

        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
        query_params = request.args.get(b"access_token")
        if auth_headers:
            # Try the get the access_token from a "Authorization: Bearer"
            # header
            if query_params is not None:
                raise MissingClientTokenError(
                    "Mixing Authorization headers and access_token query parameters."
                )
            if len(auth_headers) > 1:
                raise MissingClientTokenError("Too many Authorization headers.")
            parts = auth_headers[0].split(b" ")
            if parts[0] == b"Bearer" and len(parts) == 2:
                return parts[1].decode("ascii")
            else:
                raise MissingClientTokenError("Invalid Authorization header.")
        else:
            # Try to get the access_token from the query params.
            if not query_params:
                raise MissingClientTokenError()

            return query_params[0].decode("ascii")

    @defer.inlineCallbacks
    def check_user_in_room_or_world_readable(
        self, room_id: str, user_id: str, allow_departed_users: bool = False
    ):
        """Checks that the user is or was in the room or the room is world
        readable. If it isn't then an exception is raised.

        Args:
            room_id: room to check
            user_id: user to check
            allow_departed_users: if True, accept users that were previously
                members but have now departed

        Returns:
            Deferred[tuple[str, str|None]]: Resolves to the current membership of
                the user in the room and the membership event ID of the user. If
                the user is not in the room and never has been, then
                `(Membership.JOIN, None)` is returned.
        """

        try:
            # check_user_in_room will return the most recent membership
            # event for the user if:
            #  * The user is a non-guest user, and was ever in the room
            #  * The user is a guest user, and has joined the room
            # else it will throw.
            member_event = yield self.check_user_in_room(
                room_id, user_id, allow_departed_users=allow_departed_users
            )
            return member_event.membership, member_event.event_id
        except AuthError:
            visibility = yield defer.ensureDeferred(
                self.state.get_current_state(
                    room_id, EventTypes.RoomHistoryVisibility, ""
                )
            )
            if (
                visibility
                and visibility.content["history_visibility"] == "world_readable"
            ):
                return Membership.JOIN, None
            raise AuthError(
                403,
                "User %s not in room %s, and room previews are disabled"
                % (user_id, room_id),
            )

    def check_auth_blocking(self, *args, **kwargs):
        return self._auth_blocking.check_auth_blocking(*args, **kwargs)