diff options
Diffstat (limited to 'synapse/handlers/oidc_handler.py')
| -rw-r--r-- | synapse/handlers/oidc_handler.py | 101 |
1 files changed, 96 insertions, 5 deletions
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py index b4a74390cc..825fadb76f 100644 --- a/synapse/handlers/oidc_handler.py +++ b/synapse/handlers/oidc_handler.py @@ -1,5 +1,6 @@ # -*- coding: utf-8 -*- # Copyright 2020 Quentin Gliech +# Copyright 2021 The Matrix.org Foundation C.I.C. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -14,13 +15,13 @@ # limitations under the License. import inspect import logging -from typing import TYPE_CHECKING, Dict, Generic, List, Optional, TypeVar +from typing import TYPE_CHECKING, Dict, Generic, List, Optional, TypeVar, Union from urllib.parse import urlencode import attr import pymacaroons from authlib.common.security import generate_token -from authlib.jose import JsonWebToken +from authlib.jose import JsonWebToken, jwt from authlib.oauth2.auth import ClientAuth from authlib.oauth2.rfc6749.parameters import prepare_grant_uri from authlib.oidc.core import CodeIDToken, ImplicitIDToken, UserInfo @@ -35,12 +36,15 @@ from typing_extensions import TypedDict from twisted.web.client import readBody from synapse.config import ConfigError -from synapse.config.oidc_config import OidcProviderConfig +from synapse.config.oidc_config import ( + OidcProviderClientSecretJwtKey, + OidcProviderConfig, +) from synapse.handlers.sso import MappingException, UserAttributes from synapse.http.site import SynapseRequest from synapse.logging.context import make_deferred_yieldable from synapse.types import JsonDict, UserID, map_username_to_mxid_localpart -from synapse.util import json_decoder +from synapse.util import Clock, json_decoder from synapse.util.caches.cached_call import RetryOnExceptionCachedCall from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry @@ -276,9 +280,21 @@ class OidcProvider: self._scopes = provider.scopes self._user_profile_method = provider.user_profile_method + + client_secret = None # type: Union[None, str, JwtClientSecret] + if provider.client_secret: + client_secret = provider.client_secret + elif provider.client_secret_jwt_key: + client_secret = JwtClientSecret( + provider.client_secret_jwt_key, + provider.client_id, + provider.issuer, + hs.get_clock(), + ) + self._client_auth = ClientAuth( provider.client_id, - provider.client_secret, + client_secret, provider.client_auth_method, ) # type: ClientAuth self._client_auth_method = provider.client_auth_method @@ -977,6 +993,81 @@ class OidcProvider: return str(remote_user_id) +# number of seconds a newly-generated client secret should be valid for +CLIENT_SECRET_VALIDITY_SECONDS = 3600 + +# minimum remaining validity on a client secret before we should generate a new one +CLIENT_SECRET_MIN_VALIDITY_SECONDS = 600 + + +class JwtClientSecret: + """A class which generates a new client secret on demand, based on a JWK + + This implementation is designed to comply with the requirements for Apple Sign in: + https://developer.apple.com/documentation/sign_in_with_apple/generate_and_validate_tokens#3262048 + + It looks like those requirements are based on https://tools.ietf.org/html/rfc7523, + but it's worth noting that we still put the generated secret in the "client_secret" + field (or rather, whereever client_auth_method puts it) rather than in a + client_assertion field in the body as that RFC seems to require. + """ + + def __init__( + self, + key: OidcProviderClientSecretJwtKey, + oauth_client_id: str, + oauth_issuer: str, + clock: Clock, + ): + self._key = key + self._oauth_client_id = oauth_client_id + self._oauth_issuer = oauth_issuer + self._clock = clock + self._cached_secret = b"" + self._cached_secret_replacement_time = 0 + + def __str__(self): + # if client_auth_method is client_secret_basic, then ClientAuth.prepare calls + # encode_client_secret_basic, which calls "{}".format(secret), which ends up + # here. + return self._get_secret().decode("ascii") + + def __bytes__(self): + # if client_auth_method is client_secret_post, then ClientAuth.prepare calls + # encode_client_secret_post, which ends up here. + return self._get_secret() + + def _get_secret(self) -> bytes: + now = self._clock.time() + + # if we have enough validity on our existing secret, use it + if now < self._cached_secret_replacement_time: + return self._cached_secret + + issued_at = int(now) + expires_at = issued_at + CLIENT_SECRET_VALIDITY_SECONDS + + # we copy the configured header because jwt.encode modifies it. + header = dict(self._key.jwt_header) + + # see https://tools.ietf.org/html/rfc7523#section-3 + payload = { + "sub": self._oauth_client_id, + "aud": self._oauth_issuer, + "iat": issued_at, + "exp": expires_at, + **self._key.jwt_payload, + } + logger.info( + "Generating new JWT for %s: %s %s", self._oauth_issuer, header, payload + ) + self._cached_secret = jwt.encode(header, payload, self._key.key) + self._cached_secret_replacement_time = ( + expires_at - CLIENT_SECRET_MIN_VALIDITY_SECONDS + ) + return self._cached_secret + + class OidcSessionTokenGenerator: """Methods for generating and checking OIDC Session cookies.""" |