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,
get_request_user_agent(request),
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,
)
async def handle_redirect_request(
self, request: SynapseRequest, client_redirect_url: bytes
) -> None:
"""Handle an incoming request to /login/sso/redirect
It redirects the browser to the authorization endpoint with a few
parameters:
- ``client_id``: the client ID set in ``oidc_config.client_id``
- ``response_type``: ``code``
- ``redirect_uri``: the callback URL ; ``{base url}/_synapse/oidc/callback``
- ``scope``: the list of scopes set in ``oidc_config.scopes``
- ``state``: a random string
- ``nonce``: a random string
In addition to redirecting the client, we are setting a cookie with
a signed macaroon token containing the state, the nonce and the
client_redirect_url params. Those are then checked when the client
comes back from the provider.
Args:
request: the incoming request from the browser.
We'll respond to it with a redirect and a cookie.
client_redirect_url: the URL that we should redirect the client to
when everything is done
"""
state = generate_token()
nonce = generate_token()
cookie = self._generate_oidc_session_token(
state=state, nonce=nonce, client_redirect_url=client_redirect_url.decode(),
)
request.addCookie(
SESSION_COOKIE_NAME,
cookie,
path="/_synapse/oidc",
max_age="3600",
httpOnly=True,
sameSite="lax",
)
metadata = await self.load_metadata()
authorization_endpoint = metadata.get("authorization_endpoint")
uri = prepare_grant_uri(
authorization_endpoint,
client_id=self._client_auth.client_id,
response_type="code",
redirect_uri=self._callback_url,
scope=self._scopes,
state=state,
nonce=nonce,
)
request.redirect(uri)
finish_request(request)
async def handle_oidc_callback(self, request: SynapseRequest) -> None:
"""Handle an incoming request to /_synapse/oidc/callback
Since we might want to display OIDC-related errors in a user-friendly
way, we don't raise SynapseError from here. Instead, we call
``self._render_error`` which displays an HTML page for the error.
Most of the OpenID Connect logic happens here:
- first, we check if there was any error returned by the provider and
display it
- then we fetch the session cookie, decode and verify it
- the ``state`` query parameter should match with the one stored in the
session cookie
- once we known this session is legit, exchange the code with the
provider using the ``token_endpoint`` (see ``_exchange_code``)
- once we have the token, use it to either extract the UserInfo from
the ``id_token`` (``_parse_id_token``), or use the ``access_token``
to fetch UserInfo from the ``userinfo_endpoint``
(``_fetch_userinfo``)
- map those UserInfo to a Matrix user (``_map_userinfo_to_user``) and
finish the login
Args:
request: the incoming request from the browser.
"""
# The provider might redirect with an error.
# In that case, just display it as-is.
if b"error" in request.args:
# error response from the auth server. see:
# https://tools.ietf.org/html/rfc6749#section-4.1.2.1
# https://openid.net/specs/openid-connect-core-1_0.html#AuthError
error = request.args[b"error"][0].decode()
description = request.args.get(b"error_description", [b""])[0].decode()
# Most of the errors returned by the provider could be due by
# either the provider misbehaving or Synapse being misconfigured.
# The only exception of that is "access_denied", where the user
# probably cancelled the login flow. In other cases, log those errors.
if error != "access_denied":
logger.error("Error from the OIDC provider: %s %s", error, description)
self._render_error(request, error, description)
return
# otherwise, it is presumably a successful response. see:
# https://tools.ietf.org/html/rfc6749#section-4.1.2
# Fetch the session cookie
session = request.getCookie(SESSION_COOKIE_NAME) # type: Optional[bytes]
if session is None:
logger.info("No session cookie found")
self._render_error(request, "missing_session", "No session cookie found")
return
# Remove the cookie. There is a good chance that if the callback failed
# once, it will fail next time and the code will already be exchanged.
# Removing it early avoids spamming the provider with token requests.
request.addCookie(
SESSION_COOKIE_NAME,
b"",
path="/_synapse/oidc",
expires="Thu, Jan 01 1970 00:00:00 UTC",
httpOnly=True,
sameSite="lax",
)
# Check for the state query parameter
if b"state" not in request.args:
logger.info("State parameter is missing")
self._render_error(request, "invalid_request", "State parameter is missing")
return
state = request.args[b"state"][0].decode()
# Deserialize the session token and verify it.
try:
(
nonce,
client_redirect_url,
ui_auth_session_id,
) = self._verify_oidc_session_token(session, state)
except MacaroonDeserializationException as e:
logger.exception("Invalid session")
self._render_error(request, "invalid_session", str(e))
return
except MacaroonInvalidSignatureException as e:
logger.exception("Could not verify session")
self._render_error(request, "mismatching_session", str(e))
return
# Exchange the code with the provider
if b"code" not in request.args:
logger.info("Code parameter is missing")
self._render_error(request, "invalid_request", "Code parameter is missing")
return
logger.debug("Exchanging code")
code = request.args[b"code"][0].decode()
try:
token = await self._exchange_code(code)
except OidcError as e:
logger.exception("Could not exchange code")
self._render_error(request, e.error, e.error_description)
return
logger.debug("Successfully obtained OAuth2 access token")
# Now that we have a token, get the userinfo, either by decoding the
# `id_token` or by fetching the `userinfo_endpoint`.
if self._uses_userinfo:
logger.debug("Fetching userinfo")
try:
userinfo = await self._fetch_userinfo(token)
except Exception as e:
logger.exception("Could not fetch userinfo")
self._render_error(request, "fetch_error", str(e))
return
else:
logger.debug("Extracting userinfo from id_token")
try:
userinfo = await self._parse_id_token(token, nonce=nonce)
except Exception as e:
logger.exception("Invalid id_token")
self._render_error(request, "invalid_token", str(e))
return
# Call the mapper to register/login the user
try:
user_id = await self._map_userinfo_to_user(userinfo, token)
except MappingException as e:
logger.exception("Could not map user")
self._render_error(request, "mapping_error", str(e))
return
# and finally complete the login
if ui_auth_session_id:
await self._auth_handler.complete_sso_ui_auth(
user_id, ui_auth_session_id, request
)
else:
await self._auth_handler.complete_sso_login(
user_id, request, client_redirect_url
)
async def handle_redirect_request(
self,
request: SynapseRequest,
client_redirect_url: Optional[bytes],
ui_auth_session_id: Optional[str] = None,
) -> str:
"""Handle an incoming request to /login/sso/redirect
It returns a redirect to the authorization endpoint with a few
parameters:
- ``client_id``: the client ID set in ``oidc_config.client_id``
- ``response_type``: ``code``
- ``redirect_uri``: the callback URL ; ``{base url}/_synapse/client/oidc/callback``
- ``scope``: the list of scopes set in ``oidc_config.scopes``
- ``state``: a random string
- ``nonce``: a random string
In addition generating a redirect URL, we are setting a cookie with
a signed macaroon token containing the state, the nonce and the
client_redirect_url params. Those are then checked when the client
comes back from the provider.
Args:
request: the incoming request from the browser.
We'll respond to it with a redirect and a cookie.
client_redirect_url: the URL that we should redirect the client to
when everything is done (or None for UI Auth)
ui_auth_session_id: The session ID of the ongoing UI Auth (or
None if this is a login).
Returns:
The redirect URL to the authorization endpoint.
"""
state = generate_token()
nonce = generate_token()
if not client_redirect_url:
client_redirect_url = b""
cookie = self._token_generator.generate_oidc_session_token(
state=state,
session_data=OidcSessionData(
idp_id=self.idp_id,
nonce=nonce,
client_redirect_url=client_redirect_url.decode(),
ui_auth_session_id=ui_auth_session_id,
),
)
request.addCookie(
SESSION_COOKIE_NAME,
cookie,
path="/_synapse/client/oidc",
max_age="3600",
httpOnly=True,
sameSite="lax",
)
metadata = await self.load_metadata()
authorization_endpoint = metadata.get("authorization_endpoint")
return prepare_grant_uri(
authorization_endpoint,
client_id=self._client_auth.client_id,
response_type="code",
redirect_uri=self._callback_url,
scope=self._scopes,
state=state,
nonce=nonce,
)
async def handle_oidc_callback(self, request: SynapseRequest) -> None:
"""Handle an incoming request to /_synapse/client/oidc/callback
Since we might want to display OIDC-related errors in a user-friendly
way, we don't raise SynapseError from here. Instead, we call
``self._sso_handler.render_error`` which displays an HTML page for the error.
Most of the OpenID Connect logic happens here:
- first, we check if there was any error returned by the provider and
display it
- then we fetch the session cookie, decode and verify it
- the ``state`` query parameter should match with the one stored in the
session cookie
Once we know the session is legit, we then delegate to the OIDC Provider
implementation, which will exchange the code with the provider and complete the
login/authentication.
Args:
request: the incoming request from the browser.
"""
# The provider might redirect with an error.
# In that case, just display it as-is.
if b"error" in request.args:
# error response from the auth server. see:
# https://tools.ietf.org/html/rfc6749#section-4.1.2.1
# https://openid.net/specs/openid-connect-core-1_0.html#AuthError
error = request.args[b"error"][0].decode()
description = request.args.get(b"error_description",
[b""])[0].decode()
# Most of the errors returned by the provider could be due by
# either the provider misbehaving or Synapse being misconfigured.
# The only exception of that is "access_denied", where the user
# probably cancelled the login flow. In other cases, log those errors.
if error != "access_denied":
logger.error("Error from the OIDC provider: %s %s", error,
description)
self._sso_handler.render_error(request, error, description)
return
# otherwise, it is presumably a successful response. see:
# https://tools.ietf.org/html/rfc6749#section-4.1.2
# Fetch the session cookie
session = request.getCookie(
SESSION_COOKIE_NAME) # type: Optional[bytes]
if session is None:
logger.info("No session cookie found")
self._sso_handler.render_error(request, "missing_session",
"No session cookie found")
return
# Remove the cookie. There is a good chance that if the callback failed
# once, it will fail next time and the code will already be exchanged.
# Removing it early avoids spamming the provider with token requests.
request.addCookie(
SESSION_COOKIE_NAME,
b"",
path="/_synapse/oidc",
expires="Thu, Jan 01 1970 00:00:00 UTC",
httpOnly=True,
sameSite="lax",
)
# Check for the state query parameter
if b"state" not in request.args:
logger.info("State parameter is missing")
self._sso_handler.render_error(request, "invalid_request",
"State parameter is missing")
return
state = request.args[b"state"][0].decode()
# Deserialize the session token and verify it.
try:
session_data = self._token_generator.verify_oidc_session_token(
session, state)
except (MacaroonDeserializationException, ValueError) as e:
logger.exception("Invalid session")
self._sso_handler.render_error(request, "invalid_session", str(e))
return
except MacaroonInvalidSignatureException as e:
logger.exception("Could not verify session")
self._sso_handler.render_error(request, "mismatching_session",
str(e))
return
oidc_provider = self._providers.get(session_data.idp_id)
if not oidc_provider:
logger.error("OIDC session uses unknown IdP %r", oidc_provider)
self._sso_handler.render_error(request, "unknown_idp",
"Unknown IdP")
return
if b"code" not in request.args:
logger.info("Code parameter is missing")
self._sso_handler.render_error(request, "invalid_request",
"Code parameter is missing")
return
code = request.args[b"code"][0].decode()
await oidc_provider.handle_oidc_callback(request, session_data, code)