Query missing cross-signing keys on local sig upload (#7289)
Andrew Morgan
GitHub
parent
556566f0b8
commit
f89ad3b6df
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@ -0,0 +1 @@
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Fix a bug with cross-signing devices belonging to remote users who did not share a room with any user on the local homeserver.
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@ -399,20 +399,30 @@ class TransportLayerClient(object):
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{
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"device_keys": {
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"<user_id>": ["<device_id>"]
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} }
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}
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}
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Response:
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{
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"device_keys": {
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"<user_id>": {
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"<device_id>": {...}
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} } }
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}
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},
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"master_key": {
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"<user_id>": {...}
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}
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},
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"self_signing_key": {
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"<user_id>": {...}
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}
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}
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Args:
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destination(str): The server to query.
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query_content(dict): The user ids to query.
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Returns:
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A dict containg the device keys.
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A dict containing device and cross-signing keys.
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"""
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path = _create_v1_path("/user/keys/query")
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@ -429,14 +439,30 @@ class TransportLayerClient(object):
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Response:
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{
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"stream_id": "...",
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"devices": [ { ... } ]
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"devices": [ { ... } ],
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"master_key": {
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"user_id": "<user_id>",
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"usage": [...],
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"keys": {...},
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"signatures": {
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"<user_id>": {...}
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}
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},
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"self_signing_key": {
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"user_id": "<user_id>",
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"usage": [...],
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"keys": {...},
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"signatures": {
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"<user_id>": {...}
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}
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}
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}
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Args:
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destination(str): The server to query.
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query_content(dict): The user ids to query.
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Returns:
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A dict containg the device keys.
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A dict containing device and cross-signing keys.
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"""
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path = _create_v1_path("/user/devices/%s", user_id)
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@ -454,8 +480,10 @@ class TransportLayerClient(object):
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{
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"one_time_keys": {
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"<user_id>": {
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"<device_id>": "<algorithm>"
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} } }
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"<device_id>": "<algorithm>"
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}
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}
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}
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Response:
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{
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@ -463,13 +491,16 @@ class TransportLayerClient(object):
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"<user_id>": {
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"<device_id>": {
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"<algorithm>:<key_id>": "<key_base64>"
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} } } }
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}
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}
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}
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}
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Args:
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destination(str): The server to query.
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query_content(dict): The user ids to query.
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Returns:
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A dict containg the one-time keys.
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A dict containing the one-time keys.
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"""
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path = _create_v1_path("/user/keys/claim")
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@ -174,8 +174,8 @@ class E2eKeysHandler(object):
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"""This is called when we are querying the device list of a user on
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a remote homeserver and their device list is not in the device list
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cache. If we share a room with this user and we're not querying for
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specific user we will update the cache
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with their device list."""
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specific user we will update the cache with their device list.
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"""
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destination_query = remote_queries_not_in_cache[destination]
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@ -961,13 +961,19 @@ class E2eKeysHandler(object):
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return signature_list, failures
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@defer.inlineCallbacks
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def _get_e2e_cross_signing_verify_key(self, user_id, key_type, from_user_id=None):
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"""Fetch the cross-signing public key from storage and interpret it.
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def _get_e2e_cross_signing_verify_key(
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self, user_id: str, key_type: str, from_user_id: str = None
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):
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"""Fetch locally or remotely query for a cross-signing public key.
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First, attempt to fetch the cross-signing public key from storage.
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If that fails, query the keys from the homeserver they belong to
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and update our local copy.
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Args:
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user_id (str): the user whose key should be fetched
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key_type (str): the type of key to fetch
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from_user_id (str): the user that we are fetching the keys for.
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user_id: the user whose key should be fetched
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key_type: the type of key to fetch
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from_user_id: the user that we are fetching the keys for.
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This affects what signatures are fetched.
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Returns:
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@ -976,16 +982,140 @@ class E2eKeysHandler(object):
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Raises:
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NotFoundError: if the key is not found
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SynapseError: if `user_id` is invalid
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"""
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user = UserID.from_string(user_id)
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key = yield self.store.get_e2e_cross_signing_key(
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user_id, key_type, from_user_id
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)
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if key is None:
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logger.debug("no %s key found for %s", key_type, user_id)
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if key:
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# We found a copy of this key in our database. Decode and return it
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key_id, verify_key = get_verify_key_from_cross_signing_key(key)
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return key, key_id, verify_key
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# If we couldn't find the key locally, and we're looking for keys of
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# another user then attempt to fetch the missing key from the remote
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# user's server.
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#
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# We may run into this in possible edge cases where a user tries to
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# cross-sign a remote user, but does not share any rooms with them yet.
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# Thus, we would not have their key list yet. We instead fetch the key,
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# store it and notify clients of new, associated device IDs.
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if self.is_mine(user) or key_type not in ["master", "self_signing"]:
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# Note that master and self_signing keys are the only cross-signing keys we
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# can request over federation
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raise NotFoundError("No %s key found for %s" % (key_type, user_id))
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key_id, verify_key = get_verify_key_from_cross_signing_key(key)
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(
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key,
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key_id,
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verify_key,
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) = yield self._retrieve_cross_signing_keys_for_remote_user(user, key_type)
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if key is None:
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raise NotFoundError("No %s key found for %s" % (key_type, user_id))
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return key, key_id, verify_key
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@defer.inlineCallbacks
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def _retrieve_cross_signing_keys_for_remote_user(
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self, user: UserID, desired_key_type: str,
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):
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"""Queries cross-signing keys for a remote user and saves them to the database
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Only the key specified by `key_type` will be returned, while all retrieved keys
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will be saved regardless
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Args:
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user: The user to query remote keys for
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desired_key_type: The type of key to receive. One of "master", "self_signing"
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Returns:
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Deferred[Tuple[Optional[Dict], Optional[str], Optional[VerifyKey]]]: A tuple
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of the retrieved key content, the key's ID and the matching VerifyKey.
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If the key cannot be retrieved, all values in the tuple will instead be None.
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"""
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try:
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remote_result = yield self.federation.query_user_devices(
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user.domain, user.to_string()
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)
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except Exception as e:
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logger.warning(
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"Unable to query %s for cross-signing keys of user %s: %s %s",
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user.domain,
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user.to_string(),
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type(e),
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e,
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)
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return None, None, None
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# Process each of the retrieved cross-signing keys
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desired_key = None
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desired_key_id = None
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desired_verify_key = None
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retrieved_device_ids = []
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for key_type in ["master", "self_signing"]:
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key_content = remote_result.get(key_type + "_key")
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if not key_content:
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continue
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# Ensure these keys belong to the correct user
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if "user_id" not in key_content:
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logger.warning(
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"Invalid %s key retrieved, missing user_id field: %s",
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key_type,
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key_content,
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)
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continue
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if user.to_string() != key_content["user_id"]:
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logger.warning(
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"Found %s key of user %s when querying for keys of user %s",
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key_type,
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key_content["user_id"],
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user.to_string(),
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)
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continue
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# Validate the key contents
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try:
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# verify_key is a VerifyKey from signedjson, which uses
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# .version to denote the portion of the key ID after the
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# algorithm and colon, which is the device ID
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key_id, verify_key = get_verify_key_from_cross_signing_key(key_content)
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except ValueError as e:
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logger.warning(
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"Invalid %s key retrieved: %s - %s %s",
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key_type,
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key_content,
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type(e),
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e,
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)
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continue
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# Note down the device ID attached to this key
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retrieved_device_ids.append(verify_key.version)
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# If this is the desired key type, save it and its ID/VerifyKey
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if key_type == desired_key_type:
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desired_key = key_content
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desired_verify_key = verify_key
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desired_key_id = key_id
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# At the same time, store this key in the db for subsequent queries
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yield self.store.set_e2e_cross_signing_key(
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user.to_string(), key_type, key_content
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)
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# Notify clients that new devices for this user have been discovered
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if retrieved_device_ids:
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# XXX is this necessary?
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yield self.device_handler.notify_device_update(
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user.to_string(), retrieved_device_ids
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)
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return desired_key, desired_key_id, desired_verify_key
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def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
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"""Check a cross-signing key uploaded by a user. Performs some basic sanity
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