diff options
| -rw-r--r-- | synapse/api/errors.py | 11 | ||||
| -rw-r--r-- | synapse/handlers/e2e_room_keys.py | 88 | ||||
| -rw-r--r-- | synapse/rest/client/v2_alpha/room_keys.py | 2 | ||||
| -rw-r--r-- | synapse/storage/e2e_room_keys.py | 69 | ||||
| -rw-r--r-- | synapse/storage/schema/delta/46/e2e_room_keys.sql | 8 |
5 files changed, 99 insertions, 79 deletions
diff --git a/synapse/api/errors.py b/synapse/api/errors.py index 8c97e91ba1..d37bcb4082 100644 --- a/synapse/api/errors.py +++ b/synapse/api/errors.py @@ -289,9 +289,14 @@ class LimitExceededError(SynapseError): class RoomKeysVersionError(SynapseError): """A client has tried to upload to a non-current version of the room_keys store """ - def __init__(self, code=403, msg="Wrong room_keys version", current_version=None, - errcode=Codes.WRONG_ROOM_KEYS_VERSION): - super(RoomKeysVersionError, self).__init__(code, msg, errcode) + def __init__(self, current_version): + """ + Args: + current_version (str): the current version of the store they should have used + """ + super(RoomKeysVersionError, self).__init__( + 403, "Wrong room_keys version", Codes.WRONG_ROOM_KEYS_VERSION + ) self.current_version = current_version def error_dict(self): diff --git a/synapse/handlers/e2e_room_keys.py b/synapse/handlers/e2e_room_keys.py index bd58be6558..dda31fdd24 100644 --- a/synapse/handlers/e2e_room_keys.py +++ b/synapse/handlers/e2e_room_keys.py @@ -24,8 +24,21 @@ logger = logging.getLogger(__name__) class E2eRoomKeysHandler(object): + """ + Implements an optional realtime backup mechanism for encrypted E2E megolm room keys. + This gives a way for users to store and recover their megolm keys if they lose all + their clients. It should also extend easily to future room key mechanisms. + The actual payload of the encrypted keys is completely opaque to the handler. + """ + def __init__(self, hs): self.store = hs.get_datastore() + + # Used to lock whenever a client is uploading key data. This prevents collisions + # between clients trying to upload the details of a new session, given all + # clients belonging to a user will receive and try to upload a new session at + # roughly the same time. Also used to lock out uploads when the key is being + # changed. self._upload_linearizer = Linearizer("upload_room_keys_lock") @defer.inlineCallbacks @@ -40,33 +53,34 @@ class E2eRoomKeysHandler(object): @defer.inlineCallbacks def delete_room_keys(self, user_id, version, room_id, session_id): - yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id) + # lock for consistency with uploading + with (yield self._upload_linearizer.queue(user_id)): + yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id) @defer.inlineCallbacks def upload_room_keys(self, user_id, version, room_keys): # TODO: Validate the JSON to make sure it has the right keys. - # Check that the version we're trying to upload is the current version - - try: - version_info = yield self.get_version_info(user_id, version) - except StoreError as e: - if e.code == 404: - raise SynapseError(404, "Version '%s' not found" % (version,)) - else: - raise e - - if version_info['version'] != version: - raise RoomKeysVersionError(current_version=version_info.version) - # XXX: perhaps we should use a finer grained lock here? with (yield self._upload_linearizer.queue(user_id)): - - # go through the room_keys - for room_id in room_keys['rooms']: - for session_id in room_keys['rooms'][room_id]['sessions']: - room_key = room_keys['rooms'][room_id]['sessions'][session_id] + # Check that the version we're trying to upload is the current version + try: + version_info = yield self.get_version_info(user_id, version) + except StoreError as e: + if e.code == 404: + raise SynapseError(404, "Version '%s' not found" % (version,)) + else: + raise e + + if version_info['version'] != version: + raise RoomKeysVersionError(current_version=version_info.version) + + # go through the room_keys. + # XXX: this should/could be done concurrently, given we're in a lock. + for room_id, room in room_keys['rooms'].iteritems(): + for session_id, session in room['sessions'].iteritems(): + room_key = session[session_id] yield self._upload_room_key( user_id, version, room_id, session_id, room_key @@ -86,10 +100,29 @@ class E2eRoomKeysHandler(object): else: raise e - # check whether we merge or not. spelling it out with if/elifs rather - # than lots of booleans for legibility. - upsert = True + if _should_replace_room_key(current_room_key, room_key): + yield self.store.set_e2e_room_key( + user_id, version, room_id, session_id, room_key + ) + + def _should_replace_room_key(current_room_key, room_key): + """ + Determine whether to replace the current_room_key in our backup for this + session (if any) with a new room_key that has been uploaded. + + Args: + current_room_key (dict): Optional, the current room_key dict if any + room_key (dict): The new room_key dict which may or may not be fit to + replace the current_room_key + + Returns: + True if current_room_key should be replaced by room_key in the backup + """ + if current_room_key: + # spelt out with if/elifs rather than nested boolean expressions + # purely for legibility. + if room_key['is_verified'] and not current_room_key['is_verified']: pass elif ( @@ -97,16 +130,11 @@ class E2eRoomKeysHandler(object): current_room_key['first_message_index'] ): pass - elif room_key['forwarded_count'] < room_key['forwarded_count']: + elif room_key['forwarded_count'] < current_room_key['forwarded_count']: pass else: - upsert = False - - # if so, we set the new room_key - if upsert: - yield self.store.set_e2e_room_key( - user_id, version, room_id, session_id, room_key - ) + return False + return True @defer.inlineCallbacks def create_version(self, user_id, version_info): diff --git a/synapse/rest/client/v2_alpha/room_keys.py b/synapse/rest/client/v2_alpha/room_keys.py index 128b732fb1..70b7b4573f 100644 --- a/synapse/rest/client/v2_alpha/room_keys.py +++ b/synapse/rest/client/v2_alpha/room_keys.py @@ -68,6 +68,8 @@ class RoomKeysServlet(RestServlet): * lower forwarded_count always wins over higher forwarded_count We trust the clients not to lie and corrupt their own backups. + It also means that if your access_token is stolen, the attacker could + delete your backup. POST /room_keys/keys/!abc:matrix.org/c0ff33?version=1 HTTP/1.1 Content-Type: application/json diff --git a/synapse/storage/e2e_room_keys.py b/synapse/storage/e2e_room_keys.py index 8efca11a8c..c11417c415 100644 --- a/synapse/storage/e2e_room_keys.py +++ b/synapse/storage/e2e_room_keys.py @@ -44,30 +44,21 @@ class EndToEndRoomKeyStore(SQLBaseStore): def set_e2e_room_key(self, user_id, version, room_id, session_id, room_key): - def _set_e2e_room_key_txn(txn): - - self._simple_upsert_txn( - txn, - table="e2e_room_keys", - keyvalues={ - "user_id": user_id, - "room_id": room_id, - "session_id": session_id, - }, - values={ - "version": version, - "first_message_index": room_key['first_message_index'], - "forwarded_count": room_key['forwarded_count'], - "is_verified": room_key['is_verified'], - "session_data": room_key['session_data'], - }, - lock=False, - ) - - return True - - return self.runInteraction( - "set_e2e_room_key", _set_e2e_room_key_txn + yield self._simple_upsert( + table="e2e_room_keys", + keyvalues={ + "user_id": user_id, + "room_id": room_id, + "session_id": session_id, + }, + values={ + "version": version, + "first_message_index": room_key['first_message_index'], + "forwarded_count": room_key['forwarded_count'], + "is_verified": room_key['is_verified'], + "session_data": room_key['session_data'], + }, + lock=False, ) # XXX: this isn't currently used and isn't tested anywhere @@ -107,7 +98,9 @@ class EndToEndRoomKeyStore(SQLBaseStore): ) @defer.inlineCallbacks - def get_e2e_room_keys(self, user_id, version, room_id, session_id): + def get_e2e_room_keys( + self, user_id, version, room_id=room_id, session_id=session_id + ): keyvalues = { "user_id": user_id, @@ -115,8 +108,8 @@ class EndToEndRoomKeyStore(SQLBaseStore): } if room_id: keyvalues['room_id'] = room_id - if session_id: - keyvalues['session_id'] = session_id + if session_id: + keyvalues['session_id'] = session_id rows = yield self._simple_select_list( table="e2e_room_keys", @@ -133,18 +126,10 @@ class EndToEndRoomKeyStore(SQLBaseStore): desc="get_e2e_room_keys", ) - # perlesque autovivification from https://stackoverflow.com/a/19829714/6764493 - class AutoVivification(dict): - def __getitem__(self, item): - try: - return dict.__getitem__(self, item) - except KeyError: - value = self[item] = type(self)() - return value - - sessions = AutoVivification() + sessions = {} for row in rows: - sessions['rooms'][row['room_id']]['sessions'][row['session_id']] = { + room_entry = sessions['rooms'].setdefault(row['room_id'], {"sessions": {}}) + room_entry['sessions'][row['session_id']] = { "first_message_index": row["first_message_index"], "forwarded_count": row["forwarded_count"], "is_verified": row["is_verified"], @@ -154,7 +139,9 @@ class EndToEndRoomKeyStore(SQLBaseStore): defer.returnValue(sessions) @defer.inlineCallbacks - def delete_e2e_room_keys(self, user_id, version, room_id, session_id): + def delete_e2e_room_keys( + self, user_id, version, room_id=room_id, session_id=session_id + ): keyvalues = { "user_id": user_id, @@ -162,8 +149,8 @@ class EndToEndRoomKeyStore(SQLBaseStore): } if room_id: keyvalues['room_id'] = room_id - if session_id: - keyvalues['session_id'] = session_id + if session_id: + keyvalues['session_id'] = session_id yield self._simple_delete( table="e2e_room_keys", diff --git a/synapse/storage/schema/delta/46/e2e_room_keys.sql b/synapse/storage/schema/delta/46/e2e_room_keys.sql index 0d2a85fbe6..16499ac34c 100644 --- a/synapse/storage/schema/delta/46/e2e_room_keys.sql +++ b/synapse/storage/schema/delta/46/e2e_room_keys.sql @@ -25,16 +25,14 @@ CREATE TABLE e2e_room_keys ( session_data TEXT NOT NULL ); -CREATE UNIQUE INDEX e2e_room_keys_user_idx ON e2e_room_keys(user_id); -CREATE UNIQUE INDEX e2e_room_keys_room_idx ON e2e_room_keys(room_id); -CREATE UNIQUE INDEX e2e_room_keys_session_idx ON e2e_room_keys(session_id); +CREATE UNIQUE INDEX e2e_room_keys_idx ON e2e_room_keys(user_id, room_id, session_id); -- the metadata for each generation of encrypted e2e session backups -CREATE TABLE e2e_room_key_versions ( +CREATE TABLE e2e_room_keys_versions ( user_id TEXT NOT NULL, version TEXT NOT NULL, algorithm TEXT NOT NULL, auth_data TEXT NOT NULL ); -CREATE UNIQUE INDEX e2e_room_key_user_idx ON e2e_room_keys(user_id); +CREATE UNIQUE INDEX e2e_room_keys_versions_user_idx ON e2e_room_keys_versions(user_id); |