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Validate signatures on incoming events

This commit is contained in:
Mark Haines 2014-11-14 16:45:39 +00:00
parent 44a24605ad
commit de1ec90133
3 changed files with 52 additions and 7 deletions

View file

@ -19,6 +19,7 @@ from synapse.api.events.utils import prune_event
from syutil.jsonutil import encode_canonical_json
from syutil.base64util import encode_base64, decode_base64
from syutil.crypto.jsonsign import sign_json
from synapse.api.errors import SynapseError, Codes
import hashlib
import logging
@ -29,15 +30,24 @@ logger = logging.getLogger(__name__)
def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
"""Check whether the hash for this PDU matches the contents"""
computed_hash = _compute_content_hash(event, hash_algorithm)
logging.debug("Expecting hash: %s", encode_base64(computed_hash.digest()))
if computed_hash.name not in event.hashes:
raise Exception("Algorithm %s not in hashes %s" % (
computed_hash.name, list(event.hashes)
))
raise SynapseError(
400,
"Algorithm %s not in hashes %s" % (
computed_hash.name, list(event.hashes),
),
Codes.UNAUTHORIZED,
)
message_hash_base64 = event.hashes[computed_hash.name]
try:
message_hash_bytes = decode_base64(message_hash_base64)
except:
raise Exception("Invalid base64: %s" % (message_hash_base64,))
raise SynapseError(
400,
"Invalid base64: %s" % (message_hash_base64,),
Codes.UNAUTHORIZED,
)
return message_hash_bytes == computed_hash.digest()

View file

@ -17,13 +17,17 @@
from ._base import BaseHandler
from synapse.api.errors import AuthError, FederationError
from synapse.api.events.utils import prune_event
from synapse.api.errors import AuthError, FederationError, SynapseError
from synapse.api.events.room import RoomMemberEvent
from synapse.api.constants import Membership
from synapse.util.logutils import log_function
from synapse.federation.pdu_codec import PduCodec
from synapse.util.async import run_on_reactor
from synapse.crypto.event_signing import compute_event_signature
from synapse.crypto.event_signing import (
compute_event_signature, check_event_content_hash
)
from syutil.jsonutil import encode_canonical_json
from twisted.internet import defer
@ -59,6 +63,7 @@ class FederationHandler(BaseHandler):
self.state_handler = hs.get_state_handler()
# self.auth_handler = gs.get_auth_handler()
self.server_name = hs.hostname
self.keyring = hs.get_keyring()
self.lock_manager = hs.get_room_lock_manager()
@ -112,6 +117,34 @@ class FederationHandler(BaseHandler):
logger.debug("Processing event: %s", event.event_id)
redacted_event = prune_event(event)
redacted_event.origin = pdu.origin
redacted_event.origin_server_ts = pdu.origin_server_ts
redacted_pdu = self.pdu_codec.pdu_from_event(redacted_event)
redacted_pdu_json = redacted_pdu.get_dict()
try:
yield self.keyring.verify_json_for_server(
event.origin, redacted_pdu_json
)
except SynapseError as e:
logger.warn("Signature check failed for %s redacted to %s",
encode_canonical_json(pdu.get_dict()),
encode_canonical_json(redacted_pdu_json),
)
raise FederationError(
"ERROR",
e.code,
e.msg,
affected=event.event_id,
)
if not check_event_content_hash(pdu):
logger.warn(
"Event content has been tampered, redacting %s", event.event_id
)
event = redacted_event
if state:
state = [self.pdu_codec.event_from_pdu(p) for p in state]

View file

@ -23,7 +23,7 @@ from synapse.handlers.federation import FederationHandler
from synapse.server import HomeServer
from synapse.federation.units import Pdu
from mock import NonCallableMock, ANY
from mock import NonCallableMock, ANY, Mock
from ..utils import MockKey
@ -62,6 +62,7 @@ class FederationTestCase(unittest.TestCase):
config=self.mock_config,
auth=self.auth,
state_handler=self.state_handler,
keyring=Mock(),
)
self.datastore = hs.get_datastore()
@ -80,6 +81,7 @@ class FederationTestCase(unittest.TestCase):
origin_server_ts=0,
event_id="$a:b",
origin="b",
hashes={"sha256":"PvbCLWrTBxnBsSO7/cJ76072ySTCgI/XGadESRAe02M"},
)
self.datastore.persist_event.return_value = defer.succeed(None)