diff options
Diffstat (limited to 'synapse')
| -rw-r--r-- | synapse/handlers/oidc_handler.py | 89 | ||||
| -rw-r--r-- | synapse/util/caches/cached_call.py | 129 |
2 files changed, 182 insertions, 36 deletions
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py index 3adc75fa4a..5f3e8a77f5 100644 --- a/synapse/handlers/oidc_handler.py +++ b/synapse/handlers/oidc_handler.py @@ -41,6 +41,7 @@ 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.caches.cached_call import RetryOnExceptionCachedCall if TYPE_CHECKING: from synapse.server import HomeServer @@ -245,6 +246,7 @@ class OidcProvider: self._token_generator = token_generator + self._config = provider self._callback_url = hs.config.oidc_callback_url # type: str self._scopes = provider.scopes @@ -253,14 +255,16 @@ class OidcProvider: provider.client_id, provider.client_secret, provider.client_auth_method, ) # type: ClientAuth self._client_auth_method = provider.client_auth_method - self._provider_metadata = OpenIDProviderMetadata( - issuer=provider.issuer, - authorization_endpoint=provider.authorization_endpoint, - token_endpoint=provider.token_endpoint, - userinfo_endpoint=provider.userinfo_endpoint, - jwks_uri=provider.jwks_uri, - ) # type: OpenIDProviderMetadata - self._provider_needs_discovery = provider.discover + + # cache of metadata for the identity provider (endpoint uris, mostly). This is + # loaded on-demand from the discovery endpoint (if discovery is enabled), with + # possible overrides from the config. Access via `load_metadata`. + self._provider_metadata = RetryOnExceptionCachedCall(self._load_metadata) + + # cache of JWKs used by the identity provider to sign tokens. Loaded on demand + # from the IdP's jwks_uri, if required. + self._jwks = RetryOnExceptionCachedCall(self._load_jwks) + self._user_mapping_provider = provider.user_mapping_provider_class( provider.user_mapping_provider_config ) @@ -286,7 +290,7 @@ class OidcProvider: self._sso_handler.register_identity_provider(self) - def _validate_metadata(self): + def _validate_metadata(self, m: OpenIDProviderMetadata) -> None: """Verifies the provider metadata. This checks the validity of the currently loaded provider. Not @@ -305,7 +309,6 @@ class OidcProvider: if self._skip_verification is True: return - m = self._provider_metadata m.validate_issuer() m.validate_authorization_endpoint() m.validate_token_endpoint() @@ -340,11 +343,7 @@ class OidcProvider: ) else: # If we're not using userinfo, we need a valid jwks to validate the ID token - if m.get("jwks") is None: - if m.get("jwks_uri") is not None: - m.validate_jwks_uri() - else: - raise ValueError('"jwks_uri" must be set') + m.validate_jwks_uri() @property def _uses_userinfo(self) -> bool: @@ -361,11 +360,15 @@ class OidcProvider: or self._user_profile_method == "userinfo_endpoint" ) - async def load_metadata(self) -> OpenIDProviderMetadata: - """Load and validate the provider metadata. + async def load_metadata(self, force: bool = False) -> OpenIDProviderMetadata: + """Return the provider metadata. + + If this is the first call, the metadata is built from the config and from the + metadata discovery endpoint (if enabled), and then validated. If the metadata + is successfully validated, it is then cached for future use. - The values metadatas are discovered if ``oidc_config.discovery`` is - ``True`` and then cached. + Args: + force: If true, any cached metadata is discarded to force a reload. Raises: ValueError: if something in the provider is not valid @@ -373,18 +376,32 @@ class OidcProvider: Returns: The provider's metadata. """ - # If we are using the OpenID Discovery documents, it needs to be loaded once - # FIXME: should there be a lock here? - if self._provider_needs_discovery: - url = get_well_known_url(self._provider_metadata["issuer"], external=True) + if force: + # reset the cached call to ensure we get a new result + self._provider_metadata = RetryOnExceptionCachedCall(self._load_metadata) + + return await self._provider_metadata.get() + + async def _load_metadata(self) -> OpenIDProviderMetadata: + # init the metadata from our config + metadata = OpenIDProviderMetadata( + issuer=self._config.issuer, + authorization_endpoint=self._config.authorization_endpoint, + token_endpoint=self._config.token_endpoint, + userinfo_endpoint=self._config.userinfo_endpoint, + jwks_uri=self._config.jwks_uri, + ) + + # load any data from the discovery endpoint, if enabled + if self._config.discover: + url = get_well_known_url(self._config.issuer, external=True) metadata_response = await self._http_client.get_json(url) # TODO: maybe update the other way around to let user override some values? - self._provider_metadata.update(metadata_response) - self._provider_needs_discovery = False + metadata.update(metadata_response) - self._validate_metadata() + self._validate_metadata(metadata) - return self._provider_metadata + return metadata async def load_jwks(self, force: bool = False) -> JWKS: """Load the JSON Web Key Set used to sign ID tokens. @@ -414,27 +431,27 @@ class OidcProvider: ] } """ + if force: + # reset the cached call to ensure we get a new result + self._jwks = RetryOnExceptionCachedCall(self._load_jwks) + return await self._jwks.get() + + async def _load_jwks(self) -> JWKS: if self._uses_userinfo: # We're not using jwt signing, return an empty jwk set return {"keys": []} - # First check if the JWKS are loaded in the provider metadata. - # It can happen either if the provider gives its JWKS in the discovery - # document directly or if it was already loaded once. metadata = await self.load_metadata() - jwk_set = metadata.get("jwks") - if jwk_set is not None and not force: - return jwk_set - # Loading the JWKS using the `jwks_uri` metadata + # Load the JWKS using the `jwks_uri` metadata. uri = metadata.get("jwks_uri") if not uri: + # this should be unreachable: load_metadata validates that + # there is a jwks_uri in the metadata if _uses_userinfo is unset raise RuntimeError('Missing "jwks_uri" in metadata') jwk_set = await self._http_client.get_json(uri) - # Caching the JWKS in the provider's metadata - self._provider_metadata["jwks"] = jwk_set return jwk_set async def _exchange_code(self, code: str) -> Token: diff --git a/synapse/util/caches/cached_call.py b/synapse/util/caches/cached_call.py new file mode 100644 index 0000000000..3ee0f2317a --- /dev/null +++ b/synapse/util/caches/cached_call.py @@ -0,0 +1,129 @@ +# -*- coding: utf-8 -*- +# 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. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from typing import Awaitable, Callable, Generic, Optional, TypeVar, Union + +from twisted.internet.defer import Deferred +from twisted.python.failure import Failure + +from synapse.logging.context import make_deferred_yieldable, run_in_background + +TV = TypeVar("TV") + + +class CachedCall(Generic[TV]): + """A wrapper for asynchronous calls whose results should be shared + + This is useful for wrapping asynchronous functions, where there might be multiple + callers, but we only want to call the underlying function once (and have the result + returned to all callers). + + Similar results can be achieved via a lock of some form, but that typically requires + more boilerplate (and ends up being less efficient). + + Correctly handles Synapse logcontexts (logs and resource usage for the underlying + function are logged against the logcontext which is active when get() is first + called). + + Example usage: + + _cached_val = CachedCall(_load_prop) + + async def handle_request() -> X: + # We can call this multiple times, but it will result in a single call to + # _load_prop(). + return await _cached_val.get() + + async def _load_prop() -> X: + await difficult_operation() + + + The implementation is deliberately single-shot (ie, once the call is initiated, + there is no way to ask for it to be run). This keeps the implementation and + semantics simple. If you want to make a new call, simply replace the whole + CachedCall object. + """ + + __slots__ = ["_callable", "_deferred", "_result"] + + def __init__(self, f: Callable[[], Awaitable[TV]]): + """ + Args: + f: The underlying function. Only one call to this function will be alive + at once (per instance of CachedCall) + """ + self._callable = f # type: Optional[Callable[[], Awaitable[TV]]] + self._deferred = None # type: Optional[Deferred] + self._result = None # type: Union[None, Failure, TV] + + async def get(self) -> TV: + """Kick off the call if necessary, and return the result""" + + # Fire off the callable now if this is our first time + if not self._deferred: + self._deferred = run_in_background(self._callable) + + # we will never need the callable again, so make sure it can be GCed + self._callable = None + + # once the deferred completes, store the result. We cannot simply leave the + # result in the deferred, since if it's a Failure, GCing the deferred + # would then log a critical error about unhandled Failures. + def got_result(r): + self._result = r + + self._deferred.addBoth(got_result) + + # TODO: consider cancellation semantics. Currently, if the call to get() + # is cancelled, the underlying call will continue (and any future calls + # will get the result/exception), which I think is *probably* ok, modulo + # the fact the underlying call may be logged to a cancelled logcontext, + # and any eventual exception may not be reported. + + # we can now await the deferred, and once it completes, return the result. + await make_deferred_yieldable(self._deferred) + + # I *think* this is the easiest way to correctly raise a Failure without having + # to gut-wrench into the implementation of Deferred. + d = Deferred() + d.callback(self._result) + return await d + + +class RetryOnExceptionCachedCall(Generic[TV]): + """A wrapper around CachedCall which will retry the call if an exception is thrown + + This is used in much the same way as CachedCall, but adds some extra functionality + so that if the underlying function throws an exception, then the next call to get() + will initiate another call to the underlying function. (Any calls to get() which + are already pending will raise the exception.) + """ + + slots = ["_cachedcall"] + + def __init__(self, f: Callable[[], Awaitable[TV]]): + async def _wrapper() -> TV: + try: + return await f() + except Exception: + # the call raised an exception: replace the underlying CachedCall to + # trigger another call next time get() is called + self._cachedcall = CachedCall(_wrapper) + raise + + self._cachedcall = CachedCall(_wrapper) + + async def get(self) -> TV: + return await self._cachedcall.get() |