diff options
Diffstat (limited to 'synapse/handlers')
| -rw-r--r-- | synapse/handlers/oidc_handler.py | 74 |
1 files changed, 52 insertions, 22 deletions
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py index c00b9c57c6..07db1e31e4 100644 --- a/synapse/handlers/oidc_handler.py +++ b/synapse/handlers/oidc_handler.py @@ -48,7 +48,26 @@ if TYPE_CHECKING: logger = logging.getLogger(__name__) -SESSION_COOKIE_NAME = b"oidc_session" +# we want the cookie to be returned to us even when the request is the POSTed +# result of a form on another domain, as is used with `response_mode=form_post`. +# +# Modern browsers will not do so unless we set SameSite=None; however *older* +# browsers (including all versions of Safari on iOS 12?) don't support +# SameSite=None, and interpret it as SameSite=Strict: +# https://bugs.webkit.org/show_bug.cgi?id=198181 +# +# As a rather painful workaround, we set *two* cookies, one with SameSite=None +# and one with no SameSite, in the hope that at least one of them will get +# back to us. +# +# Secure is necessary for SameSite=None (and, empirically, also breaks things +# on iOS 12.) +# +# Here we have the names of the cookies, and the options we use to set them. +_SESSION_COOKIES = [ + (b"oidc_session", b"Path=/_synapse/client/oidc; HttpOnly; Secure; SameSite=None"), + (b"oidc_session_no_samesite", b"Path=/_synapse/client/oidc; HttpOnly"), +] #: A token exchanged from the token endpoint, as per RFC6749 sec 5.1. and #: OpenID.Core sec 3.1.3.3. @@ -149,26 +168,33 @@ class OidcHandler: # 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: + # Fetch the session cookie. See the comments on SESSION_COOKIES for why there + # are two. + + for cookie_name, _ in _SESSION_COOKIES: + session = request.getCookie(cookie_name) # type: Optional[bytes] + if session is not None: + break + else: logger.info("Received OIDC callback, with no session cookie") 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 + # Remove the cookies. 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", - ) + # Removing the cookies early avoids spamming the provider with token requests. + # + # we have to build the header by hand rather than calling request.addCookie + # because the latter does not support SameSite=None + # (https://twistedmatrix.com/trac/ticket/10088) + + for cookie_name, options in _SESSION_COOKIES: + request.cookies.append( + b"%s=; Expires=Thu, Jan 01 1970 00:00:00 UTC; %s" + % (cookie_name, options) + ) # Check for the state query parameter if b"state" not in request.args: @@ -722,14 +748,18 @@ class OidcProvider: 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", - ) + + # Set the cookies. See the comments on _SESSION_COOKIES for why there are two. + # + # we have to build the header by hand rather than calling request.addCookie + # because the latter does not support SameSite=None + # (https://twistedmatrix.com/trac/ticket/10088) + + for cookie_name, options in _SESSION_COOKIES: + request.cookies.append( + b"%s=%s; Max-Age=3600; %s" + % (cookie_name, cookie.encode("utf-8"), options) + ) metadata = await self.load_metadata() authorization_endpoint = metadata.get("authorization_endpoint") |