Remove signature check on v1 identity server lookups (#8001)

We've [decided](https://github.com/matrix-org/synapse/issues/5253#issuecomment-665976308) to remove the signature check for v1 lookups.

The signature check has been removed in v2 lookups. v1 lookups are currently deprecated. As mentioned in the above linked issue, this verification was causing deployments for the vector.im and matrix.org IS deployments, and this change is the simplest solution, without being unjustified.

Implementations are encouraged to use the v2 lookup API as it has [increased privacy benefits](https://github.com/matrix-org/matrix-doc/pull/2134).
This commit is contained in:
Andrew Morgan 2020-08-03 13:56:43 -07:00 committed by GitHub
parent 5d92a1428c
commit 481f76c7aa
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 4 additions and 31 deletions

1
changelog.d/8001.misc Normal file
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@ -0,0 +1 @@
Remove redundant and unreliable signature check for v1 Identity Service lookup responses.

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@ -22,14 +22,10 @@ import urllib.parse
from typing import Awaitable, Callable, Dict, List, Optional, Tuple
from canonicaljson import json
from signedjson.key import decode_verify_key_bytes
from signedjson.sign import verify_signed_json
from unpaddedbase64 import decode_base64
from twisted.internet.error import TimeoutError
from synapse.api.errors import (
AuthError,
CodeMessageException,
Codes,
HttpResponseException,
@ -628,9 +624,9 @@ class IdentityHandler(BaseHandler):
)
if "mxid" in data:
if "signatures" not in data:
raise AuthError(401, "No signatures on 3pid binding")
await self._verify_any_signature(data, id_server)
# note: we used to verify the identity server's signature here, but no longer
# require or validate it. See the following for context:
# https://github.com/matrix-org/synapse/issues/5253#issuecomment-666246950
return data["mxid"]
except TimeoutError:
raise SynapseError(500, "Timed out contacting identity server")
@ -751,30 +747,6 @@ class IdentityHandler(BaseHandler):
mxid = lookup_results["mappings"].get(lookup_value)
return mxid
async def _verify_any_signature(self, data, server_hostname):
if server_hostname not in data["signatures"]:
raise AuthError(401, "No signature from server %s" % (server_hostname,))
for key_name, signature in data["signatures"][server_hostname].items():
try:
key_data = await self.blacklisting_http_client.get_json(
"%s%s/_matrix/identity/api/v1/pubkey/%s"
% (id_server_scheme, server_hostname, key_name)
)
except TimeoutError:
raise SynapseError(500, "Timed out contacting identity server")
if "public_key" not in key_data:
raise AuthError(
401, "No public key named %s from %s" % (key_name, server_hostname)
)
verify_signed_json(
data,
server_hostname,
decode_verify_key_bytes(
key_name, decode_base64(key_data["public_key"])
),
)
return
async def ask_id_server_for_third_party_invite(
self,
requester: Requester,