Validate signatures on incoming events
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44a24605ad
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@ -19,6 +19,7 @@ from synapse.api.events.utils import prune_event
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from syutil.jsonutil import encode_canonical_json
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from syutil.base64util import encode_base64, decode_base64
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from syutil.crypto.jsonsign import sign_json
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from synapse.api.errors import SynapseError, Codes
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import hashlib
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import logging
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@ -29,15 +30,24 @@ logger = logging.getLogger(__name__)
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def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
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"""Check whether the hash for this PDU matches the contents"""
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computed_hash = _compute_content_hash(event, hash_algorithm)
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logging.debug("Expecting hash: %s", encode_base64(computed_hash.digest()))
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if computed_hash.name not in event.hashes:
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raise Exception("Algorithm %s not in hashes %s" % (
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computed_hash.name, list(event.hashes)
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))
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raise SynapseError(
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400,
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"Algorithm %s not in hashes %s" % (
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computed_hash.name, list(event.hashes),
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),
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Codes.UNAUTHORIZED,
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)
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message_hash_base64 = event.hashes[computed_hash.name]
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try:
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message_hash_bytes = decode_base64(message_hash_base64)
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except:
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raise Exception("Invalid base64: %s" % (message_hash_base64,))
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raise SynapseError(
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400,
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"Invalid base64: %s" % (message_hash_base64,),
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Codes.UNAUTHORIZED,
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)
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return message_hash_bytes == computed_hash.digest()
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@ -17,13 +17,17 @@
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from ._base import BaseHandler
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from synapse.api.errors import AuthError, FederationError
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from synapse.api.events.utils import prune_event
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from synapse.api.errors import AuthError, FederationError, SynapseError
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from synapse.api.events.room import RoomMemberEvent
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from synapse.api.constants import Membership
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from synapse.util.logutils import log_function
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from synapse.federation.pdu_codec import PduCodec
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from synapse.util.async import run_on_reactor
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from synapse.crypto.event_signing import compute_event_signature
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from synapse.crypto.event_signing import (
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compute_event_signature, check_event_content_hash
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)
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from syutil.jsonutil import encode_canonical_json
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from twisted.internet import defer
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@ -59,6 +63,7 @@ class FederationHandler(BaseHandler):
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self.state_handler = hs.get_state_handler()
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# self.auth_handler = gs.get_auth_handler()
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self.server_name = hs.hostname
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self.keyring = hs.get_keyring()
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self.lock_manager = hs.get_room_lock_manager()
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@ -112,6 +117,34 @@ class FederationHandler(BaseHandler):
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logger.debug("Processing event: %s", event.event_id)
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redacted_event = prune_event(event)
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redacted_event.origin = pdu.origin
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redacted_event.origin_server_ts = pdu.origin_server_ts
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redacted_pdu = self.pdu_codec.pdu_from_event(redacted_event)
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redacted_pdu_json = redacted_pdu.get_dict()
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try:
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yield self.keyring.verify_json_for_server(
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event.origin, redacted_pdu_json
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)
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except SynapseError as e:
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logger.warn("Signature check failed for %s redacted to %s",
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encode_canonical_json(pdu.get_dict()),
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encode_canonical_json(redacted_pdu_json),
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)
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raise FederationError(
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"ERROR",
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e.code,
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e.msg,
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affected=event.event_id,
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)
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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", event.event_id
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)
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event = redacted_event
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if state:
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state = [self.pdu_codec.event_from_pdu(p) for p in state]
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@ -23,7 +23,7 @@ from synapse.handlers.federation import FederationHandler
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from synapse.server import HomeServer
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from synapse.federation.units import Pdu
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from mock import NonCallableMock, ANY
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from mock import NonCallableMock, ANY, Mock
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from ..utils import MockKey
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@ -62,6 +62,7 @@ class FederationTestCase(unittest.TestCase):
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config=self.mock_config,
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auth=self.auth,
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state_handler=self.state_handler,
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keyring=Mock(),
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)
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self.datastore = hs.get_datastore()
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@ -80,6 +81,7 @@ class FederationTestCase(unittest.TestCase):
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origin_server_ts=0,
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event_id="$a:b",
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origin="b",
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hashes={"sha256":"PvbCLWrTBxnBsSO7/cJ76072ySTCgI/XGadESRAe02M"},
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)
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self.datastore.persist_event.return_value = defer.succeed(None)
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