diff options
Diffstat (limited to 'synapse/handlers/sso.py')
| -rw-r--r-- | synapse/handlers/sso.py | 254 |
1 files changed, 246 insertions, 8 deletions
diff --git a/synapse/handlers/sso.py b/synapse/handlers/sso.py index f054b66a53..548b02211b 100644 --- a/synapse/handlers/sso.py +++ b/synapse/handlers/sso.py @@ -13,17 +13,19 @@ # See the License for the specific language governing permissions and # limitations under the License. import logging -from typing import TYPE_CHECKING, Awaitable, Callable, List, Optional +from typing import TYPE_CHECKING, Awaitable, Callable, Dict, List, Optional import attr +from typing_extensions import NoReturn from twisted.web.http import Request -from synapse.api.errors import RedirectException +from synapse.api.errors import RedirectException, SynapseError from synapse.http.server import respond_with_html from synapse.http.site import SynapseRequest from synapse.types import JsonDict, UserID, contains_invalid_mxid_characters from synapse.util.async_helpers import Linearizer +from synapse.util.stringutils import random_string if TYPE_CHECKING: from synapse.server import HomeServer @@ -40,16 +42,52 @@ class MappingException(Exception): @attr.s class UserAttributes: - localpart = attr.ib(type=str) + # the localpart of the mxid that the mapper has assigned to the user. + # if `None`, the mapper has not picked a userid, and the user should be prompted to + # enter one. + localpart = attr.ib(type=Optional[str]) display_name = attr.ib(type=Optional[str], default=None) emails = attr.ib(type=List[str], default=attr.Factory(list)) +@attr.s(slots=True) +class UsernameMappingSession: + """Data we track about SSO sessions""" + + # A unique identifier for this SSO provider, e.g. "oidc" or "saml". + auth_provider_id = attr.ib(type=str) + + # user ID on the IdP server + remote_user_id = attr.ib(type=str) + + # attributes returned by the ID mapper + display_name = attr.ib(type=Optional[str]) + emails = attr.ib(type=List[str]) + + # An optional dictionary of extra attributes to be provided to the client in the + # login response. + extra_login_attributes = attr.ib(type=Optional[JsonDict]) + + # where to redirect the client back to + client_redirect_url = attr.ib(type=str) + + # expiry time for the session, in milliseconds + expiry_time_ms = attr.ib(type=int) + + +# the HTTP cookie used to track the mapping session id +USERNAME_MAPPING_SESSION_COOKIE_NAME = b"username_mapping_session" + + class SsoHandler: # The number of attempts to ask the mapping provider for when generating an MXID. _MAP_USERNAME_RETRIES = 1000 + # the time a UsernameMappingSession remains valid for + _MAPPING_SESSION_VALIDITY_PERIOD_MS = 15 * 60 * 1000 + def __init__(self, hs: "HomeServer"): + self._clock = hs.get_clock() self._store = hs.get_datastore() self._server_name = hs.hostname self._registration_handler = hs.get_registration_handler() @@ -59,6 +97,9 @@ class SsoHandler: # a lock on the mappings self._mapping_lock = Linearizer(name="sso_user_mapping", clock=hs.get_clock()) + # a map from session id to session data + self._username_mapping_sessions = {} # type: Dict[str, UsernameMappingSession] + def render_error( self, request, error: str, error_description: Optional[str] = None ) -> None: @@ -206,6 +247,18 @@ class SsoHandler: # Otherwise, generate a new user. if not user_id: attributes = await self._call_attribute_mapper(sso_to_matrix_id_mapper) + + if attributes.localpart is None: + # the mapper doesn't return a username. bail out with a redirect to + # the username picker. + await self._redirect_to_username_picker( + auth_provider_id, + remote_user_id, + attributes, + client_redirect_url, + extra_login_attributes, + ) + user_id = await self._register_mapped_user( attributes, auth_provider_id, @@ -243,10 +296,8 @@ class SsoHandler: ) if not attributes.localpart: - raise MappingException( - "Error parsing SSO response: SSO mapping provider plugin " - "did not return a localpart value" - ) + # the mapper has not picked a localpart + return attributes # Check if this mxid already exists user_id = UserID(attributes.localpart, self._server_name).to_string() @@ -261,6 +312,59 @@ class SsoHandler: ) return attributes + async def _redirect_to_username_picker( + self, + auth_provider_id: str, + remote_user_id: str, + attributes: UserAttributes, + client_redirect_url: str, + extra_login_attributes: Optional[JsonDict], + ) -> NoReturn: + """Creates a UsernameMappingSession and redirects the browser + + Called if the user mapping provider doesn't return a localpart for a new user. + Raises a RedirectException which redirects the browser to the username picker. + + Args: + auth_provider_id: A unique identifier for this SSO provider, e.g. + "oidc" or "saml". + + remote_user_id: The unique identifier from the SSO provider. + + attributes: the user attributes returned by the user mapping provider. + + client_redirect_url: The redirect URL passed in by the client, which we + will eventually redirect back to. + + extra_login_attributes: An optional dictionary of extra + attributes to be provided to the client in the login response. + + Raises: + RedirectException + """ + session_id = random_string(16) + now = self._clock.time_msec() + session = UsernameMappingSession( + auth_provider_id=auth_provider_id, + remote_user_id=remote_user_id, + display_name=attributes.display_name, + emails=attributes.emails, + client_redirect_url=client_redirect_url, + expiry_time_ms=now + self._MAPPING_SESSION_VALIDITY_PERIOD_MS, + extra_login_attributes=extra_login_attributes, + ) + + self._username_mapping_sessions[session_id] = session + logger.info("Recorded registration session id %s", session_id) + + # Set the cookie and redirect to the username picker + e = RedirectException(b"/_synapse/client/pick_username") + e.cookies.append( + b"%s=%s; path=/" + % (USERNAME_MAPPING_SESSION_COOKIE_NAME, session_id.encode("ascii")) + ) + raise e + async def _register_mapped_user( self, attributes: UserAttributes, @@ -269,9 +373,38 @@ class SsoHandler: user_agent: str, ip_address: str, ) -> str: + """Register a new SSO user. + + This is called once we have successfully mapped the remote user id onto a local + user id, one way or another. + + Args: + attributes: user attributes returned by the user mapping provider, + including a non-empty localpart. + + auth_provider_id: A unique identifier for this SSO provider, e.g. + "oidc" or "saml". + + remote_user_id: The unique identifier from the SSO provider. + + user_agent: The user-agent in the HTTP request (used for potential + shadow-banning.) + + ip_address: The IP address of the requester (used for potential + shadow-banning.) + + Raises: + a MappingException if the localpart is invalid. + + a SynapseError with code 400 and errcode Codes.USER_IN_USE if the localpart + is already taken. + """ + # Since the localpart is provided via a potentially untrusted module, # ensure the MXID is valid before registering. - if contains_invalid_mxid_characters(attributes.localpart): + if not attributes.localpart or contains_invalid_mxid_characters( + attributes.localpart + ): raise MappingException("localpart is invalid: %s" % (attributes.localpart,)) logger.debug("Mapped SSO user to local part %s", attributes.localpart) @@ -326,3 +459,108 @@ class SsoHandler: await self._auth_handler.complete_sso_ui_auth( user_id, ui_auth_session_id, request ) + + async def check_username_availability( + self, localpart: str, session_id: str, + ) -> bool: + """Handle an "is username available" callback check + + Args: + localpart: desired localpart + session_id: the session id for the username picker + Returns: + True if the username is available + Raises: + SynapseError if the localpart is invalid or the session is unknown + """ + + # make sure that there is a valid mapping session, to stop people dictionary- + # scanning for accounts + + self._expire_old_sessions() + session = self._username_mapping_sessions.get(session_id) + if not session: + logger.info("Couldn't find session id %s", session_id) + raise SynapseError(400, "unknown session") + + logger.info( + "[session %s] Checking for availability of username %s", + session_id, + localpart, + ) + + if contains_invalid_mxid_characters(localpart): + raise SynapseError(400, "localpart is invalid: %s" % (localpart,)) + user_id = UserID(localpart, self._server_name).to_string() + user_infos = await self._store.get_users_by_id_case_insensitive(user_id) + + logger.info("[session %s] users: %s", session_id, user_infos) + return not user_infos + + async def handle_submit_username_request( + self, request: SynapseRequest, localpart: str, session_id: str + ) -> None: + """Handle a request to the username-picker 'submit' endpoint + + Will serve an HTTP response to the request. + + Args: + request: HTTP request + localpart: localpart requested by the user + session_id: ID of the username mapping session, extracted from a cookie + """ + self._expire_old_sessions() + session = self._username_mapping_sessions.get(session_id) + if not session: + logger.info("Couldn't find session id %s", session_id) + raise SynapseError(400, "unknown session") + + logger.info("[session %s] Registering localpart %s", session_id, localpart) + + attributes = UserAttributes( + localpart=localpart, + display_name=session.display_name, + emails=session.emails, + ) + + # the following will raise a 400 error if the username has been taken in the + # meantime. + user_id = await self._register_mapped_user( + attributes, + session.auth_provider_id, + session.remote_user_id, + request.get_user_agent(""), + request.getClientIP(), + ) + + logger.info("[session %s] Registered userid %s", session_id, user_id) + + # delete the mapping session and the cookie + del self._username_mapping_sessions[session_id] + + # delete the cookie + request.addCookie( + USERNAME_MAPPING_SESSION_COOKIE_NAME, + b"", + expires=b"Thu, 01 Jan 1970 00:00:00 GMT", + path=b"/", + ) + + await self._auth_handler.complete_sso_login( + user_id, + request, + session.client_redirect_url, + session.extra_login_attributes, + ) + + def _expire_old_sessions(self): + to_expire = [] + now = int(self._clock.time_msec()) + + for session_id, session in self._username_mapping_sessions.items(): + if session.expiry_time_ms <= now: + to_expire.append(session_id) + + for session_id in to_expire: + logger.info("Expiring mapping session %s", session_id) + del self._username_mapping_sessions[session_id] |