Pin the internal auth port to the value nginx bound at startup (#23909)

/auth grants anonymous admin to any request whose X-Server-Port matches networking.listen.internal, but it read that port off the live config while nginx binds its listeners once at container start and never reloads them, so any path that swaps the running config could move the trusted port without nginx moving with it. Saving networking.listen.internal equal to the external port applied immediately despite the restart-required warning, which handed unauthenticated admin to everything reaching the external port. Snapshot the port at app creation and compare against that instead, and reject a config whose two listeners share a port number, which nginx would refuse to start with anyway.

frigate/api/auth.py

@@ -31,7 +31,7 @@ from frigate.api.media_auth import (
     deny_response_for_media_uri,
     is_role_restricted,
 )
-from frigate.config import AuthConfig, NetworkingConfig, ProxyConfig
+from frigate.config import AuthConfig, ProxyConfig
 from frigate.const import CONFIG_DIR, JWT_SECRET_ENV_VAR, PASSWORD_HASH_ALGORITHM
 from frigate.models import User
 
@@ -620,18 +620,18 @@ def resolve_role(
 def auth(request: Request):
     auth_config: AuthConfig = request.app.frigate_config.auth
     proxy_config: ProxyConfig = request.app.frigate_config.proxy
-    networking_config: NetworkingConfig = request.app.frigate_config.networking
 
     success_response = Response("", status_code=202)
 
-    # handle case where internal port is a string with ip:port
-    internal_port = networking_config.listen.internal
-    if type(internal_port) is str:
-        internal_port = int(internal_port.split(":")[-1])
-
     # dont require auth if the request is on the internal port
-    # this header is set by Frigate's nginx proxy, so it cant be spoofed
-    if int(request.headers.get("x-server-port", default=0)) == internal_port:
+    # this header is set by Frigate's nginx proxy, so it cant be spoofed.
+    # the port is the boot-time snapshot rather than the live config value:
+    # nginx's listeners are fixed at container start, so an in-memory config
+    # change must never move the port that is trusted here
+    if (
+        int(request.headers.get("x-server-port", default=0))
+        == request.app.auth_internal_port
+    ):
         success_response.headers["remote-user"] = "anonymous"
         success_response.headers["remote-role"] = "admin"
         return success_response

frigate/api/fastapi_app.py

@@ -152,6 +152,8 @@ def create_fastapi_app(
     app.include_router(debug_replay.router)
     # App Properties
     app.frigate_config = frigate_config
+    # snapshot the port nginx bound at startup, the live config can be swapped
+    app.auth_internal_port = frigate_config.networking.listen.internal_port
     app.genai_manager = GenAIClientManager(frigate_config)
     app.embeddings = embeddings
     app.detected_frames_processor = detected_frames_processor