diff options
Diffstat (limited to 'synapse/crypto')
| -rw-r--r-- | synapse/crypto/keyring.py | 899 |
1 files changed, 517 insertions, 382 deletions
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py index d8ba870cca..0fd15287e7 100644 --- a/synapse/crypto/keyring.py +++ b/synapse/crypto/keyring.py @@ -15,12 +15,13 @@ # limitations under the License. import logging -from collections import namedtuple +from collections import defaultdict +import six from six import raise_from from six.moves import urllib -import nacl.signing +import attr from signedjson.key import ( decode_verify_key_bytes, encode_verify_key_base64, @@ -43,7 +44,9 @@ from synapse.api.errors import ( RequestSendFailed, SynapseError, ) +from synapse.storage.keys import FetchKeyResult from synapse.util import logcontext, unwrapFirstError +from synapse.util.async_helpers import yieldable_gather_results from synapse.util.logcontext import ( LoggingContext, PreserveLoggingContext, @@ -56,22 +59,36 @@ from synapse.util.retryutils import NotRetryingDestination logger = logging.getLogger(__name__) -VerifyKeyRequest = namedtuple("VerifyRequest", ( - "server_name", "key_ids", "json_object", "deferred" -)) -""" -A request for a verify key to verify a JSON object. +@attr.s(slots=True, cmp=False) +class VerifyKeyRequest(object): + """ + A request for a verify key to verify a JSON object. + + Attributes: + server_name(str): The name of the server to verify against. + + key_ids(set[str]): The set of key_ids to that could be used to verify the + JSON object -Attributes: - server_name(str): The name of the server to verify against. - key_ids(set(str)): The set of key_ids to that could be used to verify the - JSON object - json_object(dict): The JSON object to verify. - deferred(Deferred[str, str, nacl.signing.VerifyKey]): - A deferred (server_name, key_id, verify_key) tuple that resolves when - a verify key has been fetched. The deferreds' callbacks are run with no - logcontext. -""" + json_object(dict): The JSON object to verify. + + minimum_valid_until_ts (int): time at which we require the signing key to + be valid. (0 implies we don't care) + + deferred(Deferred[str, str, nacl.signing.VerifyKey]): + A deferred (server_name, key_id, verify_key) tuple that resolves when + a verify key has been fetched. The deferreds' callbacks are run with no + logcontext. + + If we are unable to find a key which satisfies the request, the deferred + errbacks with an M_UNAUTHORIZED SynapseError. + """ + + server_name = attr.ib() + key_ids = attr.ib() + json_object = attr.ib() + minimum_valid_until_ts = attr.ib() + deferred = attr.ib(default=attr.Factory(defer.Deferred)) class KeyLookupError(ValueError): @@ -79,13 +96,16 @@ class KeyLookupError(ValueError): class Keyring(object): - def __init__(self, hs): - self.store = hs.get_datastore() + def __init__(self, hs, key_fetchers=None): self.clock = hs.get_clock() - self.client = hs.get_http_client() - self.config = hs.get_config() - self.perspective_servers = self.config.perspectives - self.hs = hs + + if key_fetchers is None: + key_fetchers = ( + StoreKeyFetcher(hs), + PerspectivesKeyFetcher(hs), + ServerKeyFetcher(hs), + ) + self._key_fetchers = key_fetchers # map from server name to Deferred. Has an entry for each server with # an ongoing key download; the Deferred completes once the download @@ -94,11 +114,25 @@ class Keyring(object): # These are regular, logcontext-agnostic Deferreds. self.key_downloads = {} - def verify_json_for_server(self, server_name, json_object): + def verify_json_for_server(self, server_name, json_object, validity_time): + """Verify that a JSON object has been signed by a given server + + Args: + server_name (str): name of the server which must have signed this object + + json_object (dict): object to be checked + + validity_time (int): timestamp at which we require the signing key to + be valid. (0 implies we don't care) + + Returns: + Deferred[None]: completes if the the object was correctly signed, otherwise + errbacks with an error + """ + req = server_name, json_object, validity_time + return logcontext.make_deferred_yieldable( - self.verify_json_objects_for_server( - [(server_name, json_object)] - )[0] + self.verify_json_objects_for_server((req,))[0] ) def verify_json_objects_for_server(self, server_and_json): @@ -106,10 +140,12 @@ class Keyring(object): necessary. Args: - server_and_json (list): List of pairs of (server_name, json_object) + server_and_json (iterable[Tuple[str, dict, int]): + Iterable of triplets of (server_name, json_object, validity_time) + validity_time is a timestamp at which the signing key must be valid. Returns: - List<Deferred>: for each input pair, a deferred indicating success + List<Deferred[None]>: for each input triplet, a deferred indicating success or failure to verify each json object's signature for the given server_name. The deferreds run their callbacks in the sentinel logcontext. @@ -118,30 +154,32 @@ class Keyring(object): verify_requests = [] handle = preserve_fn(_handle_key_deferred) - def process(server_name, json_object): + def process(server_name, json_object, validity_time): """Process an entry in the request list - Given a (server_name, json_object) pair from the request list, - adds a key request to verify_requests, and returns a deferred which will - complete or fail (in the sentinel context) when verification completes. + Given a (server_name, json_object, validity_time) triplet from the request + list, adds a key request to verify_requests, and returns a deferred which + will complete or fail (in the sentinel context) when verification completes. """ key_ids = signature_ids(json_object, server_name) if not key_ids: return defer.fail( SynapseError( - 400, - "Not signed by %s" % (server_name,), - Codes.UNAUTHORIZED, + 400, "Not signed by %s" % (server_name,), Codes.UNAUTHORIZED ) ) - logger.debug("Verifying for %s with key_ids %s", - server_name, key_ids) + logger.debug( + "Verifying for %s with key_ids %s, min_validity %i", + server_name, + key_ids, + validity_time, + ) # add the key request to the queue, but don't start it off yet. verify_request = VerifyKeyRequest( - server_name, key_ids, json_object, defer.Deferred(), + server_name, key_ids, json_object, validity_time ) verify_requests.append(verify_request) @@ -153,8 +191,8 @@ class Keyring(object): return handle(verify_request) results = [ - process(server_name, json_object) - for server_name, json_object in server_and_json + process(server_name, json_object, validity_time) + for server_name, json_object, validity_time in server_and_json ] if verify_requests: @@ -179,16 +217,12 @@ class Keyring(object): # any other lookups until we have finished. # The deferreds are called with no logcontext. server_to_deferred = { - rq.server_name: defer.Deferred() - for rq in verify_requests + rq.server_name: defer.Deferred() for rq in verify_requests } # We want to wait for any previous lookups to complete before # proceeding. - yield self.wait_for_previous_lookups( - [rq.server_name for rq in verify_requests], - server_to_deferred, - ) + yield self.wait_for_previous_lookups(server_to_deferred) # Actually start fetching keys. self._get_server_verify_keys(verify_requests) @@ -216,19 +250,16 @@ class Keyring(object): return res for verify_request in verify_requests: - verify_request.deferred.addBoth( - remove_deferreds, verify_request, - ) + verify_request.deferred.addBoth(remove_deferreds, verify_request) except Exception: logger.exception("Error starting key lookups") @defer.inlineCallbacks - def wait_for_previous_lookups(self, server_names, server_to_deferred): + def wait_for_previous_lookups(self, server_to_deferred): """Waits for any previous key lookups for the given servers to finish. Args: - server_names (list): list of server_names we want to lookup - server_to_deferred (dict): server_name to deferred which gets + server_to_deferred (dict[str, Deferred]): server_name to deferred which gets resolved once we've finished looking up keys for that server. The Deferreds should be regular twisted ones which call their callbacks with no logcontext. @@ -241,14 +272,15 @@ class Keyring(object): while True: wait_on = [ (server_name, self.key_downloads[server_name]) - for server_name in server_names + for server_name in server_to_deferred.keys() if server_name in self.key_downloads ] if not wait_on: break logger.info( "Waiting for existing lookups for %s to complete [loop %i]", - [w[0] for w in wait_on], loop_count, + [w[0] for w in wait_on], + loop_count, ) with PreserveLoggingContext(): yield defer.DeferredList((w[1] for w in wait_on)) @@ -279,129 +311,290 @@ class Keyring(object): verify_requests (list[VerifyKeyRequest]): list of verify requests """ - # These are functions that produce keys given a list of key ids - key_fetch_fns = ( - self.get_keys_from_store, # First try the local store - self.get_keys_from_perspectives, # Then try via perspectives - self.get_keys_from_server, # Then try directly + remaining_requests = set( + (rq for rq in verify_requests if not rq.deferred.called) ) @defer.inlineCallbacks def do_iterations(): with Measure(self.clock, "get_server_verify_keys"): - # dict[str, set(str)]: keys to fetch for each server - missing_keys = {} - for verify_request in verify_requests: - missing_keys.setdefault(verify_request.server_name, set()).update( - verify_request.key_ids - ) - - for fn in key_fetch_fns: - results = yield fn(missing_keys.items()) - - # We now need to figure out which verify requests we have keys - # for and which we don't - missing_keys = {} - requests_missing_keys = [] - for verify_request in verify_requests: - if verify_request.deferred.called: - # We've already called this deferred, which probably - # means that we've already found a key for it. - continue - - server_name = verify_request.server_name - - # see if any of the keys we got this time are sufficient to - # complete this VerifyKeyRequest. - result_keys = results.get(server_name, {}) - for key_id in verify_request.key_ids: - key = result_keys.get(key_id) - if key: - with PreserveLoggingContext(): - verify_request.deferred.callback( - (server_name, key_id, key) - ) - break - else: - # The else block is only reached if the loop above - # doesn't break. - missing_keys.setdefault(server_name, set()).update( - verify_request.key_ids - ) - requests_missing_keys.append(verify_request) - - if not missing_keys: - break + for f in self._key_fetchers: + if not remaining_requests: + return + yield self._attempt_key_fetches_with_fetcher(f, remaining_requests) + # look for any requests which weren't satisfied with PreserveLoggingContext(): - for verify_request in requests_missing_keys: - verify_request.deferred.errback(SynapseError( - 401, - "No key for %s with id %s" % ( - verify_request.server_name, verify_request.key_ids, - ), - Codes.UNAUTHORIZED, - )) + for verify_request in remaining_requests: + verify_request.deferred.errback( + SynapseError( + 401, + "No key for %s with ids in %s (min_validity %i)" + % ( + verify_request.server_name, + verify_request.key_ids, + verify_request.minimum_valid_until_ts, + ), + Codes.UNAUTHORIZED, + ) + ) def on_err(err): + # we don't really expect to get here, because any errors should already + # have been caught and logged. But if we do, let's log the error and make + # sure that all of the deferreds are resolved. + logger.error("Unexpected error in _get_server_verify_keys: %s", err) with PreserveLoggingContext(): - for verify_request in verify_requests: + for verify_request in remaining_requests: if not verify_request.deferred.called: verify_request.deferred.errback(err) run_in_background(do_iterations).addErrback(on_err) @defer.inlineCallbacks - def get_keys_from_store(self, server_name_and_key_ids): + def _attempt_key_fetches_with_fetcher(self, fetcher, remaining_requests): + """Use a key fetcher to attempt to satisfy some key requests + + Args: + fetcher (KeyFetcher): fetcher to use to fetch the keys + remaining_requests (set[VerifyKeyRequest]): outstanding key requests. + Any successfully-completed requests will be removed from the list. + """ + # dict[str, dict[str, int]]: keys to fetch. + # server_name -> key_id -> min_valid_ts + missing_keys = defaultdict(dict) + + for verify_request in remaining_requests: + # any completed requests should already have been removed + assert not verify_request.deferred.called + keys_for_server = missing_keys[verify_request.server_name] + + for key_id in verify_request.key_ids: + # If we have several requests for the same key, then we only need to + # request that key once, but we should do so with the greatest + # min_valid_until_ts of the requests, so that we can satisfy all of + # the requests. + keys_for_server[key_id] = max( + keys_for_server.get(key_id, -1), + verify_request.minimum_valid_until_ts + ) + + results = yield fetcher.get_keys(missing_keys) + + completed = list() + for verify_request in remaining_requests: + server_name = verify_request.server_name + + # see if any of the keys we got this time are sufficient to + # complete this VerifyKeyRequest. + result_keys = results.get(server_name, {}) + for key_id in verify_request.key_ids: + fetch_key_result = result_keys.get(key_id) + if not fetch_key_result: + # we didn't get a result for this key + continue + + if ( + fetch_key_result.valid_until_ts + < verify_request.minimum_valid_until_ts + ): + # key was not valid at this point + continue + + with PreserveLoggingContext(): + verify_request.deferred.callback( + (server_name, key_id, fetch_key_result.verify_key) + ) + completed.append(verify_request) + break + + remaining_requests.difference_update(completed) + + +class KeyFetcher(object): + def get_keys(self, keys_to_fetch): """ Args: - server_name_and_key_ids (iterable(Tuple[str, iterable[str]]): - list of (server_name, iterable[key_id]) tuples to fetch keys for + keys_to_fetch (dict[str, dict[str, int]]): + the keys to be fetched. server_name -> key_id -> min_valid_ts Returns: - Deferred: resolves to dict[str, dict[str, VerifyKey|None]]: map from - server_name -> key_id -> VerifyKey + Deferred[dict[str, dict[str, synapse.storage.keys.FetchKeyResult|None]]]: + map from server_name -> key_id -> FetchKeyResult """ + raise NotImplementedError + + +class StoreKeyFetcher(KeyFetcher): + """KeyFetcher impl which fetches keys from our data store""" + + def __init__(self, hs): + self.store = hs.get_datastore() + + @defer.inlineCallbacks + def get_keys(self, keys_to_fetch): + """see KeyFetcher.get_keys""" + keys_to_fetch = ( (server_name, key_id) - for server_name, key_ids in server_name_and_key_ids - for key_id in key_ids + for server_name, keys_for_server in keys_to_fetch.items() + for key_id in keys_for_server.keys() ) + res = yield self.store.get_server_verify_keys(keys_to_fetch) keys = {} for (server_name, key_id), key in res.items(): keys.setdefault(server_name, {})[key_id] = key defer.returnValue(keys) + +class BaseV2KeyFetcher(object): + def __init__(self, hs): + self.store = hs.get_datastore() + self.config = hs.get_config() + + @defer.inlineCallbacks + def process_v2_response( + self, from_server, response_json, time_added_ms + ): + """Parse a 'Server Keys' structure from the result of a /key request + + This is used to parse either the entirety of the response from + GET /_matrix/key/v2/server, or a single entry from the list returned by + POST /_matrix/key/v2/query. + + Checks that each signature in the response that claims to come from the origin + server is valid, and that there is at least one such signature. + + Stores the json in server_keys_json so that it can be used for future responses + to /_matrix/key/v2/query. + + Args: + from_server (str): the name of the server producing this result: either + the origin server for a /_matrix/key/v2/server request, or the notary + for a /_matrix/key/v2/query. + + response_json (dict): the json-decoded Server Keys response object + + time_added_ms (int): the timestamp to record in server_keys_json + + Returns: + Deferred[dict[str, FetchKeyResult]]: map from key_id to result object + """ + ts_valid_until_ms = response_json[u"valid_until_ts"] + + # start by extracting the keys from the response, since they may be required + # to validate the signature on the response. + verify_keys = {} + for key_id, key_data in response_json["verify_keys"].items(): + if is_signing_algorithm_supported(key_id): + key_base64 = key_data["key"] + key_bytes = decode_base64(key_base64) + verify_key = decode_verify_key_bytes(key_id, key_bytes) + verify_keys[key_id] = FetchKeyResult( + verify_key=verify_key, valid_until_ts=ts_valid_until_ms + ) + + server_name = response_json["server_name"] + verified = False + for key_id in response_json["signatures"].get(server_name, {}): + # each of the keys used for the signature must be present in the response + # json. + key = verify_keys.get(key_id) + if not key: + raise KeyLookupError( + "Key response is signed by key id %s:%s but that key is not " + "present in the response" % (server_name, key_id) + ) + + verify_signed_json(response_json, server_name, key.verify_key) + verified = True + + if not verified: + raise KeyLookupError( + "Key response for %s is not signed by the origin server" + % (server_name,) + ) + + for key_id, key_data in response_json["old_verify_keys"].items(): + if is_signing_algorithm_supported(key_id): + key_base64 = key_data["key"] + key_bytes = decode_base64(key_base64) + verify_key = decode_verify_key_bytes(key_id, key_bytes) + verify_keys[key_id] = FetchKeyResult( + verify_key=verify_key, valid_until_ts=key_data["expired_ts"] + ) + + # re-sign the json with our own key, so that it is ready if we are asked to + # give it out as a notary server + signed_key_json = sign_json( + response_json, self.config.server_name, self.config.signing_key[0] + ) + + signed_key_json_bytes = encode_canonical_json(signed_key_json) + + yield logcontext.make_deferred_yieldable( + defer.gatherResults( + [ + run_in_background( + self.store.store_server_keys_json, + server_name=server_name, + key_id=key_id, + from_server=from_server, + ts_now_ms=time_added_ms, + ts_expires_ms=ts_valid_until_ms, + key_json_bytes=signed_key_json_bytes, + ) + for key_id in verify_keys + ], + consumeErrors=True, + ).addErrback(unwrapFirstError) + ) + + defer.returnValue(verify_keys) + + +class PerspectivesKeyFetcher(BaseV2KeyFetcher): + """KeyFetcher impl which fetches keys from the "perspectives" servers""" + + def __init__(self, hs): + super(PerspectivesKeyFetcher, self).__init__(hs) + self.clock = hs.get_clock() + self.client = hs.get_http_client() + self.perspective_servers = self.config.perspectives + @defer.inlineCallbacks - def get_keys_from_perspectives(self, server_name_and_key_ids): + def get_keys(self, keys_to_fetch): + """see KeyFetcher.get_keys""" + @defer.inlineCallbacks def get_key(perspective_name, perspective_keys): try: result = yield self.get_server_verify_key_v2_indirect( - server_name_and_key_ids, perspective_name, perspective_keys + keys_to_fetch, perspective_name, perspective_keys ) defer.returnValue(result) except KeyLookupError as e: - logger.warning( - "Key lookup failed from %r: %s", perspective_name, e, - ) + logger.warning("Key lookup failed from %r: %s", perspective_name, e) except Exception as e: logger.exception( "Unable to get key from %r: %s %s", perspective_name, - type(e).__name__, str(e), + type(e).__name__, + str(e), ) defer.returnValue({}) - results = yield logcontext.make_deferred_yieldable(defer.gatherResults( - [ - run_in_background(get_key, p_name, p_keys) - for p_name, p_keys in self.perspective_servers.items() - ], - consumeErrors=True, - ).addErrback(unwrapFirstError)) + results = yield logcontext.make_deferred_yieldable( + defer.gatherResults( + [ + run_in_background(get_key, p_name, p_keys) + for p_name, p_keys in self.perspective_servers.items() + ], + consumeErrors=True, + ).addErrback(unwrapFirstError) + ) union_of_keys = {} for result in results: @@ -411,36 +604,33 @@ class Keyring(object): defer.returnValue(union_of_keys) @defer.inlineCallbacks - def get_keys_from_server(self, server_name_and_key_ids): - results = yield logcontext.make_deferred_yieldable(defer.gatherResults( - [ - run_in_background( - self.get_server_verify_key_v2_direct, - server_name, - key_ids, - ) - for server_name, key_ids in server_name_and_key_ids - ], - consumeErrors=True, - ).addErrback(unwrapFirstError)) + def get_server_verify_key_v2_indirect( + self, keys_to_fetch, perspective_name, perspective_keys + ): + """ + Args: + keys_to_fetch (dict[str, dict[str, int]]): + the keys to be fetched. server_name -> key_id -> min_valid_ts - merged = {} - for result in results: - merged.update(result) + perspective_name (str): name of the notary server to query for the keys - defer.returnValue({ - server_name: keys - for server_name, keys in merged.items() - if keys - }) + perspective_keys (dict[str, VerifyKey]): map of key_id->key for the + notary server + + Returns: + Deferred[dict[str, dict[str, synapse.storage.keys.FetchKeyResult]]]: map + from server_name -> key_id -> FetchKeyResult + + Raises: + KeyLookupError if there was an error processing the entire response from + the server + """ + logger.info( + "Requesting keys %s from notary server %s", + keys_to_fetch.items(), + perspective_name, + ) - @defer.inlineCallbacks - def get_server_verify_key_v2_indirect(self, server_names_and_key_ids, - perspective_name, - perspective_keys): - # TODO(mark): Set the minimum_valid_until_ts to that needed by - # the events being validated or the current time if validating - # an incoming request. try: query_response = yield self.client.post_json( destination=perspective_name, @@ -448,249 +638,213 @@ class Keyring(object): data={ u"server_keys": { server_name: { - key_id: { - u"minimum_valid_until_ts": 0 - } for key_id in key_ids + key_id: {u"minimum_valid_until_ts": min_valid_ts} + for key_id, min_valid_ts in server_keys.items() } - for server_name, key_ids in server_names_and_key_ids + for server_name, server_keys in keys_to_fetch.items() } }, - long_retries=True, ) except (NotRetryingDestination, RequestSendFailed) as e: - raise_from( - KeyLookupError("Failed to connect to remote server"), e, - ) + raise_from(KeyLookupError("Failed to connect to remote server"), e) except HttpResponseException as e: - raise_from( - KeyLookupError("Remote server returned an error"), e, - ) + raise_from(KeyLookupError("Remote server returned an error"), e) keys = {} + added_keys = [] - responses = query_response["server_keys"] + time_now_ms = self.clock.time_msec() - for response in responses: - if (u"signatures" not in response - or perspective_name not in response[u"signatures"]): + for response in query_response["server_keys"]: + # do this first, so that we can give useful errors thereafter + server_name = response.get("server_name") + if not isinstance(server_name, six.string_types): raise KeyLookupError( - "Key response not signed by perspective server" - " %r" % (perspective_name,) + "Malformed response from key notary server %s: invalid server_name" + % (perspective_name,) ) - verified = False - for key_id in response[u"signatures"][perspective_name]: - if key_id in perspective_keys: - verify_signed_json( - response, - perspective_name, - perspective_keys[key_id] - ) - verified = True - - if not verified: - logging.info( - "Response from perspective server %r not signed with a" - " known key, signed with: %r, known keys: %r", + try: + processed_response = yield self._process_perspectives_response( perspective_name, - list(response[u"signatures"][perspective_name]), - list(perspective_keys) + perspective_keys, + response, + time_added_ms=time_now_ms, ) - raise KeyLookupError( - "Response not signed with a known key for perspective" - " server %r" % (perspective_name,) + except KeyLookupError as e: + logger.warning( + "Error processing response from key notary server %s for origin " + "server %s: %s", + perspective_name, + server_name, + e, ) + # we continue to process the rest of the response + continue - processed_response = yield self.process_v2_response( - perspective_name, response + added_keys.extend( + (server_name, key_id, key) for key_id, key in processed_response.items() ) - server_name = response["server_name"] - keys.setdefault(server_name, {}).update(processed_response) - yield logcontext.make_deferred_yieldable(defer.gatherResults( - [ - run_in_background( - self.store_keys, - server_name=server_name, - from_server=perspective_name, - verify_keys=response_keys, - ) - for server_name, response_keys in keys.items() - ], - consumeErrors=True - ).addErrback(unwrapFirstError)) + yield self.store.store_server_verify_keys( + perspective_name, time_now_ms, added_keys + ) defer.returnValue(keys) - @defer.inlineCallbacks - def get_server_verify_key_v2_direct(self, server_name, key_ids): - keys = {} # type: dict[str, nacl.signing.VerifyKey] + def _process_perspectives_response( + self, perspective_name, perspective_keys, response, time_added_ms + ): + """Parse a 'Server Keys' structure from the result of a /key/query request - for requested_key_id in key_ids: - if requested_key_id in keys: - continue + Checks that the entry is correctly signed by the perspectives server, and then + passes over to process_v2_response - try: - response = yield self.client.get_json( - destination=server_name, - path="/_matrix/key/v2/server/" + urllib.parse.quote(requested_key_id), - ignore_backoff=True, - ) - except (NotRetryingDestination, RequestSendFailed) as e: - raise_from( - KeyLookupError("Failed to connect to remote server"), e, - ) - except HttpResponseException as e: - raise_from( - KeyLookupError("Remote server returned an error"), e, - ) + Args: + perspective_name (str): the name of the notary server that produced this + result - if (u"signatures" not in response - or server_name not in response[u"signatures"]): - raise KeyLookupError("Key response not signed by remote server") + perspective_keys (dict[str, VerifyKey]): map of key_id->key for the + notary server - if response["server_name"] != server_name: - raise KeyLookupError("Expected a response for server %r not %r" % ( - server_name, response["server_name"] - )) + response (dict): the json-decoded Server Keys response object - response_keys = yield self.process_v2_response( - from_server=server_name, - requested_ids=[requested_key_id], - response_json=response, - ) + time_added_ms (int): the timestamp to record in server_keys_json - keys.update(response_keys) + Returns: + Deferred[dict[str, FetchKeyResult]]: map from key_id to result object + """ + if ( + u"signatures" not in response + or perspective_name not in response[u"signatures"] + ): + raise KeyLookupError("Response not signed by the notary server") + + verified = False + for key_id in response[u"signatures"][perspective_name]: + if key_id in perspective_keys: + verify_signed_json(response, perspective_name, perspective_keys[key_id]) + verified = True + + if not verified: + raise KeyLookupError( + "Response not signed with a known key: signed with: %r, known keys: %r" + % ( + list(response[u"signatures"][perspective_name].keys()), + list(perspective_keys.keys()), + ) + ) - yield self.store_keys( - server_name=server_name, - from_server=server_name, - verify_keys=keys, + return self.process_v2_response( + perspective_name, response, time_added_ms=time_added_ms ) - defer.returnValue({server_name: keys}) - @defer.inlineCallbacks - def process_v2_response( - self, from_server, response_json, requested_ids=[], - ): - """Parse a 'Server Keys' structure from the result of a /key request - This is used to parse either the entirety of the response from - GET /_matrix/key/v2/server, or a single entry from the list returned by - POST /_matrix/key/v2/query. - - Checks that each signature in the response that claims to come from the origin - server is valid. (Does not check that there actually is such a signature, for - some reason.) +class ServerKeyFetcher(BaseV2KeyFetcher): + """KeyFetcher impl which fetches keys from the origin servers""" - Stores the json in server_keys_json so that it can be used for future responses - to /_matrix/key/v2/query. + def __init__(self, hs): + super(ServerKeyFetcher, self).__init__(hs) + self.clock = hs.get_clock() + self.client = hs.get_http_client() + def get_keys(self, keys_to_fetch): + """ Args: - from_server (str): the name of the server producing this result: either - the origin server for a /_matrix/key/v2/server request, or the notary - for a /_matrix/key/v2/query. - - response_json (dict): the json-decoded Server Keys response object - - requested_ids (iterable[str]): a list of the key IDs that were requested. - We will store the json for these key ids as well as any that are - actually in the response + keys_to_fetch (dict[str, iterable[str]]): + the keys to be fetched. server_name -> key_ids Returns: - Deferred[dict[str, nacl.signing.VerifyKey]]: - map from key_id to key object + Deferred[dict[str, dict[str, synapse.storage.keys.FetchKeyResult|None]]]: + map from server_name -> key_id -> FetchKeyResult """ - time_now_ms = self.clock.time_msec() - response_keys = {} - verify_keys = {} - for key_id, key_data in response_json["verify_keys"].items(): - if is_signing_algorithm_supported(key_id): - key_base64 = key_data["key"] - key_bytes = decode_base64(key_base64) - verify_key = decode_verify_key_bytes(key_id, key_bytes) - verify_key.time_added = time_now_ms - verify_keys[key_id] = verify_key - old_verify_keys = {} - for key_id, key_data in response_json["old_verify_keys"].items(): - if is_signing_algorithm_supported(key_id): - key_base64 = key_data["key"] - key_bytes = decode_base64(key_base64) - verify_key = decode_verify_key_bytes(key_id, key_bytes) - verify_key.expired = key_data["expired_ts"] - verify_key.time_added = time_now_ms - old_verify_keys[key_id] = verify_key + results = {} - server_name = response_json["server_name"] - for key_id in response_json["signatures"].get(server_name, {}): - if key_id not in response_json["verify_keys"]: - raise KeyLookupError( - "Key response must include verification keys for all" - " signatures" - ) - if key_id in verify_keys: - verify_signed_json( - response_json, - server_name, - verify_keys[key_id] + @defer.inlineCallbacks + def get_key(key_to_fetch_item): + server_name, key_ids = key_to_fetch_item + try: + keys = yield self.get_server_verify_key_v2_direct(server_name, key_ids) + results[server_name] = keys + except KeyLookupError as e: + logger.warning( + "Error looking up keys %s from %s: %s", key_ids, server_name, e ) + except Exception: + logger.exception("Error getting keys %s from %s", key_ids, server_name) - signed_key_json = sign_json( - response_json, - self.config.server_name, - self.config.signing_key[0], + return yieldable_gather_results(get_key, keys_to_fetch.items()).addCallback( + lambda _: results ) - signed_key_json_bytes = encode_canonical_json(signed_key_json) - ts_valid_until_ms = signed_key_json[u"valid_until_ts"] - - updated_key_ids = set(requested_ids) - updated_key_ids.update(verify_keys) - updated_key_ids.update(old_verify_keys) - - response_keys.update(verify_keys) - response_keys.update(old_verify_keys) - - yield logcontext.make_deferred_yieldable(defer.gatherResults( - [ - run_in_background( - self.store.store_server_keys_json, - server_name=server_name, - key_id=key_id, - from_server=from_server, - ts_now_ms=time_now_ms, - ts_expires_ms=ts_valid_until_ms, - key_json_bytes=signed_key_json_bytes, - ) - for key_id in updated_key_ids - ], - consumeErrors=True, - ).addErrback(unwrapFirstError)) - - defer.returnValue(response_keys) + @defer.inlineCallbacks + def get_server_verify_key_v2_direct(self, server_name, key_ids): + """ - def store_keys(self, server_name, from_server, verify_keys): - """Store a collection of verify keys for a given server Args: - server_name(str): The name of the server the keys are for. - from_server(str): The server the keys were downloaded from. - verify_keys(dict): A mapping of key_id to VerifyKey. + server_name (str): + key_ids (iterable[str]): + Returns: - A deferred that completes when the keys are stored. + Deferred[dict[str, FetchKeyResult]]: map from key ID to lookup result + + Raises: + KeyLookupError if there was a problem making the lookup """ - # TODO(markjh): Store whether the keys have expired. - return logcontext.make_deferred_yieldable(defer.gatherResults( - [ - run_in_background( - self.store.store_server_verify_key, - server_name, server_name, key.time_added, key + keys = {} # type: dict[str, FetchKeyResult] + + for requested_key_id in key_ids: + # we may have found this key as a side-effect of asking for another. + if requested_key_id in keys: + continue + + time_now_ms = self.clock.time_msec() + try: + response = yield self.client.get_json( + destination=server_name, + path="/_matrix/key/v2/server/" + + urllib.parse.quote(requested_key_id), + ignore_backoff=True, + + # we only give the remote server 10s to respond. It should be an + # easy request to handle, so if it doesn't reply within 10s, it's + # probably not going to. + # + # Furthermore, when we are acting as a notary server, we cannot + # wait all day for all of the origin servers, as the requesting + # server will otherwise time out before we can respond. + # + # (Note that get_json may make 4 attempts, so this can still take + # almost 45 seconds to fetch the headers, plus up to another 60s to + # read the response). + timeout=10000, ) - for key_id, key in verify_keys.items() - ], - consumeErrors=True, - ).addErrback(unwrapFirstError)) + except (NotRetryingDestination, RequestSendFailed) as e: + raise_from(KeyLookupError("Failed to connect to remote server"), e) + except HttpResponseException as e: + raise_from(KeyLookupError("Remote server returned an error"), e) + + if response["server_name"] != server_name: + raise KeyLookupError( + "Expected a response for server %r not %r" + % (server_name, response["server_name"]) + ) + + response_keys = yield self.process_v2_response( + from_server=server_name, + response_json=response, + time_added_ms=time_now_ms, + ) + yield self.store.store_server_verify_keys( + server_name, + time_now_ms, + ((server_name, key_id, key) for key_id, key in response_keys.items()), + ) + keys.update(response_keys) + + defer.returnValue(keys) @defer.inlineCallbacks @@ -707,48 +861,29 @@ def _handle_key_deferred(verify_request): SynapseError if there was a problem performing the verification """ server_name = verify_request.server_name - try: - with PreserveLoggingContext(): - _, key_id, verify_key = yield verify_request.deferred - except KeyLookupError as e: - logger.warn( - "Failed to download keys for %s: %s %s", - server_name, type(e).__name__, str(e), - ) - raise SynapseError( - 502, - "Error downloading keys for %s" % (server_name,), - Codes.UNAUTHORIZED, - ) - except Exception as e: - logger.exception( - "Got Exception when downloading keys for %s: %s %s", - server_name, type(e).__name__, str(e), - ) - raise SynapseError( - 401, - "No key for %s with id %s" % (server_name, verify_request.key_ids), - Codes.UNAUTHORIZED, - ) + with PreserveLoggingContext(): + _, key_id, verify_key = yield verify_request.deferred json_object = verify_request.json_object - logger.debug("Got key %s %s:%s for server %s, verifying" % ( - key_id, verify_key.alg, verify_key.version, server_name, - )) + logger.debug( + "Got key %s %s:%s for server %s, verifying" + % (key_id, verify_key.alg, verify_key.version, server_name) + ) try: verify_signed_json(json_object, server_name, verify_key) except SignatureVerifyException as e: logger.debug( "Error verifying signature for %s:%s:%s with key %s: %s", - server_name, verify_key.alg, verify_key.version, + server_name, + verify_key.alg, + verify_key.version, encode_verify_key_base64(verify_key), str(e), ) raise SynapseError( 401, - "Invalid signature for server %s with key %s:%s: %s" % ( - server_name, verify_key.alg, verify_key.version, str(e), - ), + "Invalid signature for server %s with key %s:%s: %s" + % (server_name, verify_key.alg, verify_key.version, str(e)), Codes.UNAUTHORIZED, ) |