119 lines
3.8 KiB
Python
119 lines
3.8 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015 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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from twisted.internet import defer
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from synapse.events.utils import prune_event
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from syutil.jsonutil import encode_canonical_json
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from synapse.crypto.event_signing import check_event_content_hash
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from synapse.api.errors import SynapseError
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import logging
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logger = logging.getLogger(__name__)
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class FederationBase(object):
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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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"""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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signed_pdus = []
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for pdu in pdus:
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try:
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new_pdu = yield self._check_sigs_and_hash(pdu)
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signed_pdus.append(new_pdu)
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except SynapseError:
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# FIXME: We should handle signature failures more gracefully.
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# Check local db.
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new_pdu = yield self.store.get_event(
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pdu.event_id,
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allow_rejected=True
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)
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if new_pdu:
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signed_pdus.append(new_pdu)
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continue
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# Check pdu.origin
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if pdu.origin != origin:
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new_pdu = 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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)
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if new_pdu:
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signed_pdus.append(new_pdu)
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continue
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logger.warn("Failed to find copy of %s with valid signature")
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defer.returnValue(signed_pdus)
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@defer.inlineCallbacks
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def _check_sigs_and_hash(self, pdu):
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"""Throws a SynapseError if the PDU does not have the correct
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signatures.
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Returns:
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FrozenEvent: Either the given event or it redacted if it failed the
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content hash check.
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"""
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# Check signatures are correct.
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redacted_event = prune_event(pdu)
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redacted_pdu_json = redacted_event.get_pdu_json()
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try:
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yield self.keyring.verify_json_for_server(
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pdu.origin, redacted_pdu_json
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)
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except SynapseError:
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logger.warn(
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"Signature check failed for %s redacted to %s",
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encode_canonical_json(pdu.get_pdu_json()),
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encode_canonical_json(redacted_pdu_json),
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)
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raise
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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, encode_canonical_json(pdu.get_dict())
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)
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defer.returnValue(redacted_event)
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defer.returnValue(pdu)
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