diff --git a/synapse/api/auth/oauth_delegated.py b/synapse/api/auth/oauth_delegated.py
new file mode 100644
index 0000000000..b3b5c29a94
--- /dev/null
+++ b/synapse/api/auth/oauth_delegated.py
@@ -0,0 +1,227 @@
+# Copyright 2023 The Matrix.org Foundation.
+#
+# 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.
+import logging
+from typing import TYPE_CHECKING, Any, Dict, List, Optional
+from urllib.parse import urlencode
+
+from authlib.oauth2 import ClientAuth
+from authlib.oauth2.auth import encode_client_secret_basic, encode_client_secret_post
+from authlib.oauth2.rfc7523 import ClientSecretJWT, PrivateKeyJWT, private_key_jwt_sign
+from authlib.oauth2.rfc7662 import IntrospectionToken
+from authlib.oidc.discovery import OpenIDProviderMetadata, get_well_known_url
+
+from twisted.web.client import readBody
+from twisted.web.http_headers import Headers
+
+from synapse.api.auth.base import BaseAuth
+from synapse.api.errors import AuthError, StoreError
+from synapse.http.site import SynapseRequest
+from synapse.logging.context import make_deferred_yieldable
+from synapse.types import Requester, UserID, create_requester
+from synapse.util import json_decoder
+from synapse.util.caches.cached_call import RetryOnExceptionCachedCall
+
+if TYPE_CHECKING:
+ from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+def scope_to_list(scope: str) -> List[str]:
+ """Convert a scope string to a list of scope tokens"""
+ return scope.strip().split(" ")
+
+
+class PrivateKeyJWTWithKid(PrivateKeyJWT):
+ """An implementation of the private_key_jwt client auth method that includes a kid header.
+
+ This is needed because some providers (Keycloak) require the kid header to figure
+ out which key to use to verify the signature.
+ """
+
+ def sign(self, auth: Any, token_endpoint: str) -> bytes:
+ return private_key_jwt_sign(
+ auth.client_secret,
+ client_id=auth.client_id,
+ token_endpoint=token_endpoint,
+ claims=self.claims,
+ header={"kid": auth.client_secret["kid"]},
+ )
+
+
+class OAuthDelegatedAuth(BaseAuth):
+ AUTH_METHODS = {
+ "client_secret_post": encode_client_secret_post,
+ "client_secret_basic": encode_client_secret_basic,
+ "client_secret_jwt": ClientSecretJWT(),
+ "private_key_jwt": PrivateKeyJWTWithKid(),
+ }
+
+ def __init__(self, hs: "HomeServer"):
+ super().__init__(hs)
+
+ self._config = hs.config.auth
+ assert self._config.oauth_delegation_enabled, "OAuth delegation is not enabled"
+ assert self._config.oauth_delegation_issuer, "No issuer provided"
+ assert self._config.oauth_delegation_client_id, "No client_id provided"
+ assert self._config.oauth_delegation_client_secret, "No client_secret provided"
+ assert (
+ self._config.oauth_delegation_client_auth_method
+ in OAuthDelegatedAuth.AUTH_METHODS
+ ), "Invalid client_auth_method"
+
+ self._http_client = hs.get_proxied_http_client()
+ self._hostname = hs.hostname
+
+ self._issuer_metadata = RetryOnExceptionCachedCall(self._load_metadata)
+ secret = self._config.oauth_delegation_client_secret
+ self._client_auth = ClientAuth(
+ self._config.oauth_delegation_client_id,
+ secret,
+ OAuthDelegatedAuth.AUTH_METHODS[
+ self._config.oauth_delegation_client_auth_method
+ ],
+ )
+
+ async def _load_metadata(self) -> OpenIDProviderMetadata:
+ if self._config.oauth_delegation_issuer_metadata is not None:
+ return OpenIDProviderMetadata(
+ **self._config.oauth_delegation_issuer_metadata
+ )
+ url = get_well_known_url(self._config.oauth_delegation_issuer, external=True)
+ response = await self._http_client.get_json(url)
+ metadata = OpenIDProviderMetadata(**response)
+ # metadata.validate_introspection_endpoint()
+ return metadata
+
+ async def _introspect_token(self, token: str) -> IntrospectionToken:
+ metadata = await self._issuer_metadata.get()
+ introspection_endpoint = metadata.get("introspection_endpoint")
+ raw_headers: Dict[str, str] = {
+ "Content-Type": "application/x-www-form-urlencoded",
+ "User-Agent": str(self._http_client.user_agent, "utf-8"),
+ "Accept": "application/json",
+ }
+
+ args = {"token": token, "token_type_hint": "access_token"}
+ body = urlencode(args, True)
+
+ # Fill the body/headers with credentials
+ uri, raw_headers, body = self._client_auth.prepare(
+ method="POST", uri=introspection_endpoint, headers=raw_headers, body=body
+ )
+ headers = Headers({k: [v] for (k, v) in raw_headers.items()})
+
+ # Do the actual request
+ # We're not using the SimpleHttpClient util methods as we don't want to
+ # check the HTTP status code and we do the body encoding ourself.
+ response = await self._http_client.request(
+ method="POST",
+ uri=uri,
+ data=body.encode("utf-8"),
+ headers=headers,
+ )
+
+ resp_body = await make_deferred_yieldable(readBody(response))
+ # TODO: Let's not worry about 5xx errors & co. for now and just try
+ # decoding that as JSON. We should also do some validation of the
+ # response
+ resp = json_decoder.decode(resp_body.decode("utf-8"))
+ return IntrospectionToken(**resp)
+
+ async def get_user_by_req(
+ self,
+ request: SynapseRequest,
+ allow_guest: bool = False,
+ allow_expired: bool = False,
+ ) -> Requester:
+ access_token = self.get_access_token_from_request(request)
+ return await self.get_user_by_access_token(access_token, allow_expired)
+
+ async def get_user_by_access_token(
+ self,
+ token: str,
+ allow_expired: bool = False,
+ ) -> Requester:
+ introspection_result = await self._introspect_token(token)
+
+ logger.info(f"Introspection result: {introspection_result!r}")
+
+ # TODO: introspection verification should be more extensive, especially:
+ # - verify the scopes
+ # - verify the audience
+ if not introspection_result.get("active"):
+ raise AuthError(
+ 403,
+ "Invalid access token",
+ )
+
+ # TODO: claim mapping should be configurable
+ username: Optional[str] = introspection_result.get("username")
+ if username is None or not isinstance(username, str):
+ raise AuthError(
+ 500,
+ "Invalid username claim in the introspection result",
+ )
+
+ # Let's look at the scope
+ scope: List[str] = scope_to_list(introspection_result.get("scope", ""))
+ device_id = None
+ # Find device_id in scope
+ for tok in scope:
+ if tok.startswith("urn:matrix:org.matrix.msc2967.client:device:"):
+ parts = tok.split(":")
+ if len(parts) == 5:
+ device_id = parts[4]
+
+ user_id = UserID(username, self._hostname)
+ user_info = await self.store.get_userinfo_by_id(user_id=user_id.to_string())
+
+ # If the user does not exist, we should create it on the fly
+ # TODO: we could use SCIM to provision users ahead of time and listen
+ # for SCIM SET events if those ever become standard:
+ # https://datatracker.ietf.org/doc/html/draft-hunt-scim-notify-00
+ if not user_info:
+ await self.store.register_user(user_id=user_id.to_string())
+ user_info = await self.store.get_userinfo_by_id(user_id=user_id.to_string())
+ if not user_info:
+ raise AuthError(
+ 500,
+ "Could not create user on the fly",
+ )
+
+ if device_id:
+ # Create the device on the fly if it does not exist
+ try:
+ await self.store.get_device(
+ user_id=user_id.to_string(), device_id=device_id
+ )
+ except StoreError:
+ await self.store.store_device(
+ user_id=user_id.to_string(),
+ device_id=device_id,
+ initial_device_display_name="OIDC-native client",
+ )
+
+ # TODO: there is a few things missing in the requester here, which still need
+ # to be figured out, like:
+ # - impersonation, with the `authenticated_entity`, which is used for
+ # rate-limiting, MAU limits, etc.
+ # - shadow-banning, with the `shadow_banned` flag
+ # - a proper solution for appservices, which still needs to be figured out in
+ # the context of MSC3861
+ return create_requester(
+ user_id=user_id,
+ device_id=device_id,
+ )
diff --git a/synapse/config/auth.py b/synapse/config/auth.py
index 35774962c0..25b5cc60dc 100644
--- a/synapse/config/auth.py
+++ b/synapse/config/auth.py
@@ -14,9 +14,11 @@
# limitations under the License.
from typing import Any
+from authlib.jose.rfc7517 import JsonWebKey
+
from synapse.types import JsonDict
-from ._base import Config
+from ._base import Config, ConfigError
class AuthConfig(Config):
@@ -53,3 +55,29 @@ class AuthConfig(Config):
self.ui_auth_session_timeout = self.parse_duration(
ui_auth.get("session_timeout", 0)
)
+
+ oauth_delegation = config.get("oauth_delegation", {})
+ self.oauth_delegation_enabled = oauth_delegation.get("enabled", False)
+ self.oauth_delegation_issuer = oauth_delegation.get("issuer", "")
+ self.oauth_delegation_issuer_metadata = oauth_delegation.get("issuer_metadata")
+ self.oauth_delegation_account = oauth_delegation.get("account", "")
+ self.oauth_delegation_client_id = oauth_delegation.get("client_id", "")
+ self.oauth_delegation_client_secret = oauth_delegation.get("client_secret", "")
+ self.oauth_delegation_client_auth_method = oauth_delegation.get(
+ "client_auth_method", "client_secret_post"
+ )
+
+ self.password_enabled = password_config.get(
+ "enabled", not self.oauth_delegation_enabled
+ )
+
+ if self.oauth_delegation_client_auth_method == "private_key_jwt":
+ self.oauth_delegation_client_secret = JsonWebKey.import_key(
+ self.oauth_delegation_client_secret
+ )
+
+ # If we are delegating via OAuth then password cannot be supported as well
+ if self.oauth_delegation_enabled and self.password_enabled:
+ raise ConfigError(
+ "Password auth cannot be enabled when OAuth delegation is enabled"
+ )
diff --git a/synapse/server.py b/synapse/server.py
index df88af12a9..1c82500f30 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -428,6 +428,10 @@ class HomeServer(metaclass=abc.ABCMeta):
@cache_in_self
def get_auth(self) -> Auth:
+ if self.config.auth.oauth_delegation_enabled:
+ from synapse.api.auth.oauth_delegated import OAuthDelegatedAuth
+
+ return OAuthDelegatedAuth(self)
return InternalAuth(self)
@cache_in_self
|
