diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 7860f9625e..2ce1425dfa 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -125,7 +125,11 @@ class AuthHandler(BaseHandler):
@defer.inlineCallbacks
def validate_user_via_ui_auth(
- self, requester: Requester, request_body: Dict[str, Any], clientip: str
+ self,
+ requester: Requester,
+ request: SynapseRequest,
+ request_body: Dict[str, Any],
+ clientip: str,
):
"""
Checks that the user is who they claim to be, via a UI auth.
@@ -137,6 +141,8 @@ class AuthHandler(BaseHandler):
Args:
requester: The user, as given by the access token
+ request: The request sent by the client.
+
request_body: The body of the request sent by the client
clientip: The IP address of the client.
@@ -172,7 +178,9 @@ class AuthHandler(BaseHandler):
flows = [[login_type] for login_type in self._supported_login_types]
try:
- result, params, _ = yield self.check_auth(flows, request_body, clientip)
+ result, params, _ = yield self.check_auth(
+ flows, request, request_body, clientip
+ )
except LoginError:
# Update the ratelimite to say we failed (`can_do_action` doesn't raise).
self._failed_uia_attempts_ratelimiter.can_do_action(
@@ -211,7 +219,11 @@ class AuthHandler(BaseHandler):
@defer.inlineCallbacks
def check_auth(
- self, flows: List[List[str]], clientdict: Dict[str, Any], clientip: str
+ self,
+ flows: List[List[str]],
+ request: SynapseRequest,
+ clientdict: Dict[str, Any],
+ clientip: str,
):
"""
Takes a dictionary sent by the client in the login / registration
@@ -231,6 +243,8 @@ class AuthHandler(BaseHandler):
strings representing auth-types. At least one full
flow must be completed in order for auth to be successful.
+ request: The request sent by the client.
+
clientdict: The dictionary from the client root level, not the
'auth' key: this method prompts for auth if none is sent.
@@ -270,13 +284,27 @@ class AuthHandler(BaseHandler):
# email auth link on there). It's probably too open to abuse
# because it lets unauthenticated clients store arbitrary objects
# on a homeserver.
- # Revisit: Assumimg the REST APIs do sensible validation, the data
+ # Revisit: Assuming the REST APIs do sensible validation, the data
# isn't arbintrary.
session["clientdict"] = clientdict
self._save_session(session)
elif "clientdict" in session:
clientdict = session["clientdict"]
+ # Ensure that the queried operation does not vary between stages of
+ # the UI authentication session. This is done by generating a stable
+ # comparator based on the URI, method, and body (minus the auth dict)
+ # and storing it during the initial query. Subsequent queries ensure
+ # that this comparator has not changed.
+ comparator = (request.uri, request.method, clientdict)
+ if "ui_auth" not in session:
+ session["ui_auth"] = comparator
+ elif session["ui_auth"] != comparator:
+ raise SynapseError(
+ 403,
+ "Requested operation has changed during the UI authentication session.",
+ )
+
if not authdict:
raise InteractiveAuthIncompleteError(
self._auth_dict_for_flows(flows, session)
@@ -322,6 +350,7 @@ class AuthHandler(BaseHandler):
creds,
list(clientdict),
)
+
return creds, clientdict, session["id"]
ret = self._auth_dict_for_flows(flows, session)
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