From 4b36b482e0cc1a63db27534c4ea5d9608cdb6a79 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com> Date: Mon, 6 Jan 2020 12:33:56 +0000 Subject: [PATCH] Fix exception when fetching notary server's old keys (#6625) Lift the restriction that *all* the keys used for signing v2 key responses be present in verify_keys. Fixes #6596. --- changelog.d/6625.bugfix | 1 + synapse/crypto/keyring.py | 13 ++-- tests/crypto/test_keyring.py | 147 +++++++++++++++++++++++------------ 3 files changed, 107 insertions(+), 54 deletions(-) create mode 100644 changelog.d/6625.bugfix diff --git a/changelog.d/6625.bugfix b/changelog.d/6625.bugfix new file mode 100644 index 000000000..a8dc5587d --- /dev/null +++ b/changelog.d/6625.bugfix @@ -0,0 +1 @@ +Fix exception when fetching the `matrix.org:ed25519:auto` key. diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py index 7cfad192e..6fe5a6a26 100644 --- a/synapse/crypto/keyring.py +++ b/synapse/crypto/keyring.py @@ -511,17 +511,18 @@ class BaseV2KeyFetcher(object): 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) - ) + # the key may not be present in verify_keys if: + # * we got the key from the notary server, and: + # * the key belongs to the notary server, and: + # * the notary server is using a different key to sign notary + # responses. + continue verify_signed_json(response_json, server_name, key.verify_key) verified = True + break if not verified: raise KeyLookupError( diff --git a/tests/crypto/test_keyring.py b/tests/crypto/test_keyring.py index 8efd39c7f..34d5895f1 100644 --- a/tests/crypto/test_keyring.py +++ b/tests/crypto/test_keyring.py @@ -19,6 +19,7 @@ from mock import Mock import canonicaljson import signedjson.key import signedjson.sign +from nacl.signing import SigningKey from signedjson.key import encode_verify_key_base64, get_verify_key from twisted.internet import defer @@ -412,6 +413,49 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase): handlers=None, http_client=self.http_client, config=config ) + def build_perspectives_response( + self, server_name: str, signing_key: SigningKey, valid_until_ts: int, + ) -> dict: + """ + Build a valid perspectives server response to a request for the given key + """ + verify_key = signedjson.key.get_verify_key(signing_key) + verifykey_id = "%s:%s" % (verify_key.alg, verify_key.version) + + response = { + "server_name": server_name, + "old_verify_keys": {}, + "valid_until_ts": valid_until_ts, + "verify_keys": { + verifykey_id: { + "key": signedjson.key.encode_verify_key_base64(verify_key) + } + }, + } + # the response must be signed by both the origin server and the perspectives + # server. + signedjson.sign.sign_json(response, server_name, signing_key) + self.mock_perspective_server.sign_response(response) + return response + + def expect_outgoing_key_query( + self, expected_server_name: str, expected_key_id: str, response: dict + ) -> None: + """ + Tell the mock http client to expect a perspectives-server key query + """ + + def post_json(destination, path, data, **kwargs): + self.assertEqual(destination, self.mock_perspective_server.server_name) + self.assertEqual(path, "/_matrix/key/v2/query") + + # check that the request is for the expected key + q = data["server_keys"] + self.assertEqual(list(q[expected_server_name].keys()), [expected_key_id]) + return {"server_keys": [response]} + + self.http_client.post_json.side_effect = post_json + def test_get_keys_from_perspectives(self): # arbitrarily advance the clock a bit self.reactor.advance(100) @@ -424,33 +468,61 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase): testverifykey_id = "ed25519:ver1" VALID_UNTIL_TS = 200 * 1000 - # valid response - response = { - "server_name": SERVER_NAME, - "old_verify_keys": {}, - "valid_until_ts": VALID_UNTIL_TS, - "verify_keys": { - testverifykey_id: { - "key": signedjson.key.encode_verify_key_base64(testverifykey) - } - }, - } + response = self.build_perspectives_response( + SERVER_NAME, testkey, VALID_UNTIL_TS, + ) - # the response must be signed by both the origin server and the perspectives - # server. - signedjson.sign.sign_json(response, SERVER_NAME, testkey) - self.mock_perspective_server.sign_response(response) + self.expect_outgoing_key_query(SERVER_NAME, "key1", response) - def post_json(destination, path, data, **kwargs): - self.assertEqual(destination, self.mock_perspective_server.server_name) - self.assertEqual(path, "/_matrix/key/v2/query") + keys_to_fetch = {SERVER_NAME: {"key1": 0}} + keys = self.get_success(fetcher.get_keys(keys_to_fetch)) + self.assertIn(SERVER_NAME, keys) + k = keys[SERVER_NAME][testverifykey_id] + self.assertEqual(k.valid_until_ts, VALID_UNTIL_TS) + self.assertEqual(k.verify_key, testverifykey) + self.assertEqual(k.verify_key.alg, "ed25519") + self.assertEqual(k.verify_key.version, "ver1") - # check that the request is for the expected key - q = data["server_keys"] - self.assertEqual(list(q[SERVER_NAME].keys()), ["key1"]) - return {"server_keys": [response]} + # check that the perspectives store is correctly updated + lookup_triplet = (SERVER_NAME, testverifykey_id, None) + key_json = self.get_success( + self.hs.get_datastore().get_server_keys_json([lookup_triplet]) + ) + res = key_json[lookup_triplet] + self.assertEqual(len(res), 1) + res = res[0] + self.assertEqual(res["key_id"], testverifykey_id) + self.assertEqual(res["from_server"], self.mock_perspective_server.server_name) + self.assertEqual(res["ts_added_ms"], self.reactor.seconds() * 1000) + self.assertEqual(res["ts_valid_until_ms"], VALID_UNTIL_TS) - self.http_client.post_json.side_effect = post_json + self.assertEqual( + bytes(res["key_json"]), canonicaljson.encode_canonical_json(response) + ) + + def test_get_perspectives_own_key(self): + """Check that we can get the perspectives server's own keys + + This is slightly complicated by the fact that the perspectives server may + use different keys for signing notary responses. + """ + + # arbitrarily advance the clock a bit + self.reactor.advance(100) + + fetcher = PerspectivesKeyFetcher(self.hs) + + SERVER_NAME = self.mock_perspective_server.server_name + testkey = signedjson.key.generate_signing_key("ver1") + testverifykey = signedjson.key.get_verify_key(testkey) + testverifykey_id = "ed25519:ver1" + VALID_UNTIL_TS = 200 * 1000 + + response = self.build_perspectives_response( + SERVER_NAME, testkey, VALID_UNTIL_TS + ) + + self.expect_outgoing_key_query(SERVER_NAME, "key1", response) keys_to_fetch = {SERVER_NAME: {"key1": 0}} keys = self.get_success(fetcher.get_keys(keys_to_fetch)) @@ -490,35 +562,14 @@ class PerspectivesKeyFetcherTestCase(unittest.HomeserverTestCase): VALID_UNTIL_TS = 200 * 1000 def build_response(): - # valid response - response = { - "server_name": SERVER_NAME, - "old_verify_keys": {}, - "valid_until_ts": VALID_UNTIL_TS, - "verify_keys": { - testverifykey_id: { - "key": signedjson.key.encode_verify_key_base64(testverifykey) - } - }, - } - - # the response must be signed by both the origin server and the perspectives - # server. - signedjson.sign.sign_json(response, SERVER_NAME, testkey) - self.mock_perspective_server.sign_response(response) - return response + return self.build_perspectives_response( + SERVER_NAME, testkey, VALID_UNTIL_TS + ) def get_key_from_perspectives(response): fetcher = PerspectivesKeyFetcher(self.hs) keys_to_fetch = {SERVER_NAME: {"key1": 0}} - - def post_json(destination, path, data, **kwargs): - self.assertEqual(destination, self.mock_perspective_server.server_name) - self.assertEqual(path, "/_matrix/key/v2/query") - return {"server_keys": [response]} - - self.http_client.post_json.side_effect = post_json - + self.expect_outgoing_key_query(SERVER_NAME, "key1", response) return self.get_success(fetcher.get_keys(keys_to_fetch)) # start with a valid response so we can check we are testing the right thing