199 lines
6.4 KiB
Python
199 lines
6.4 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from synapse.api.errors import SynapseError
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from synapse.crypto.event_signing import check_event_content_hash
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from synapse.events import FrozenEvent
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from synapse.events.utils import prune_event
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from synapse.http.servlet import assert_params_in_request
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from synapse.util import unwrapFirstError, logcontext
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from twisted.internet import defer
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logger = logging.getLogger(__name__)
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class FederationBase(object):
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def __init__(self, hs):
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self.spam_checker = hs.get_spam_checker()
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@defer.inlineCallbacks
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def _check_sigs_and_hash_and_fetch(self, origin, pdus, outlier=False,
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include_none=False):
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"""Takes a list of PDUs and checks the signatures and hashs of each
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one. If a PDU fails its signature check then we check if we have it in
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the database and if not then request if from the originating server of
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that PDU.
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If a PDU fails its content hash check then it is redacted.
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The given list of PDUs are not modified, instead the function returns
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a new list.
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Args:
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pdu (list)
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outlier (bool)
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Returns:
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Deferred : A list of PDUs that have valid signatures and hashes.
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"""
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deferreds = self._check_sigs_and_hashes(pdus)
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@defer.inlineCallbacks
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def handle_check_result(pdu, deferred):
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try:
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res = yield logcontext.make_deferred_yieldable(deferred)
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except SynapseError:
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res = None
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if not res:
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# Check local db.
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res = yield self.store.get_event(
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pdu.event_id,
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allow_rejected=True,
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allow_none=True,
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)
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if not res and pdu.origin != origin:
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try:
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res = yield self.get_pdu(
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destinations=[pdu.origin],
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event_id=pdu.event_id,
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outlier=outlier,
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timeout=10000,
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)
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except SynapseError:
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pass
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if not res:
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logger.warn(
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"Failed to find copy of %s with valid signature",
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pdu.event_id,
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)
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defer.returnValue(res)
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handle = logcontext.preserve_fn(handle_check_result)
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deferreds2 = [
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handle(pdu, deferred)
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for pdu, deferred in zip(pdus, deferreds)
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]
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valid_pdus = yield logcontext.make_deferred_yieldable(
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defer.gatherResults(
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deferreds2,
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consumeErrors=True,
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)
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).addErrback(unwrapFirstError)
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if include_none:
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defer.returnValue(valid_pdus)
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else:
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defer.returnValue([p for p in valid_pdus if p])
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def _check_sigs_and_hash(self, pdu):
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return logcontext.make_deferred_yieldable(
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self._check_sigs_and_hashes([pdu])[0],
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)
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def _check_sigs_and_hashes(self, pdus):
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"""Checks that each of the received events is correctly signed by the
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sending server.
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Args:
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pdus (list[FrozenEvent]): the events to be checked
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Returns:
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list[Deferred]: for each input event, a deferred which:
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* returns the original event if the checks pass
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* returns a redacted version of the event (if the signature
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matched but the hash did not)
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* throws a SynapseError if the signature check failed.
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The deferreds run their callbacks in the sentinel logcontext.
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"""
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redacted_pdus = [
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prune_event(pdu)
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for pdu in pdus
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]
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deferreds = self.keyring.verify_json_objects_for_server([
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(p.origin, p.get_pdu_json())
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for p in redacted_pdus
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])
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ctx = logcontext.LoggingContext.current_context()
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def callback(_, pdu, redacted):
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with logcontext.PreserveLoggingContext(ctx):
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if not check_event_content_hash(pdu):
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logger.warn(
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"Event content has been tampered, redacting %s: %s",
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pdu.event_id, pdu.get_pdu_json()
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)
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return redacted
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if self.spam_checker.check_event_for_spam(pdu):
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logger.warn(
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"Event contains spam, redacting %s: %s",
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pdu.event_id, pdu.get_pdu_json()
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)
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return redacted
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return pdu
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def errback(failure, pdu):
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failure.trap(SynapseError)
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with logcontext.PreserveLoggingContext(ctx):
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logger.warn(
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"Signature check failed for %s",
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pdu.event_id,
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)
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return failure
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for deferred, pdu, redacted in zip(deferreds, pdus, redacted_pdus):
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deferred.addCallbacks(
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callback, errback,
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callbackArgs=[pdu, redacted],
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errbackArgs=[pdu],
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)
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return deferreds
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def event_from_pdu_json(pdu_json, outlier=False):
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"""Construct a FrozenEvent from an event json received over federation
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Args:
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pdu_json (object): pdu as received over federation
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outlier (bool): True to mark this event as an outlier
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Returns:
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FrozenEvent
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Raises:
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SynapseError: if the pdu is missing required fields
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"""
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# we could probably enforce a bunch of other fields here (room_id, sender,
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# origin, etc etc)
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assert_params_in_request(pdu_json, ('event_id', 'type'))
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event = FrozenEvent(
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pdu_json
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)
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event.internal_metadata.outlier = outlier
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return event
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