Tighten CORS rules (#7503)

* tighten cors rules

* add changeset

* cors policy

* cors

* add changeset

* lint

* changes

* changes

* changes

* logging

* add null

* changes

* changes

* options

* options

* safe changes

* let browser enforce cors

* clean

* route utils

* fix

* fix test

* fix

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>

Author: abidlabs

.changeset/olive-symbols-heal.md

@@ -0,0 +1,5 @@
+---
+"gradio": patch
+---
+
+feat:Tighten CORS rules

gradio/route_utils.py

@@ -9,6 +9,7 @@
 from dataclasses import dataclass as python_dataclass
 from tempfile import NamedTemporaryFile, _TemporaryFileWrapper
 from typing import TYPE_CHECKING, AsyncGenerator, BinaryIO, List, Optional, Tuple, Union
+from urllib.parse import urlparse
 
 import fastapi
 import httpx
@@ -17,6 +18,7 @@
 from multipart.multipart import parse_options_header
 from starlette.datastructures import FormData, Headers, UploadFile
 from starlette.formparsers import MultiPartException, MultipartPart
+from starlette.middleware.base import BaseHTTPMiddleware
 
 from gradio import processing_utils, utils
 from gradio.data_classes import PredictBody
@@ -583,3 +585,58 @@ def starts_with_protocol(string: str) -> bool:
     """
     pattern = r"^[a-zA-Z][a-zA-Z0-9+\-.]*://"
     return re.match(pattern, string) is not None
+
+
+def get_hostname(url: str) -> str:
+    """
+    Returns the hostname of a given url, or an empty string if the url cannot be parsed.
+    Examples:
+        get_hostname("https://www.gradio.app") -> "www.gradio.app"
+        get_hostname("localhost:7860") -> "localhost"
+        get_hostname("127.0.0.1") -> "127.0.0.1"
+    """
+    if not url:
+        return ""
+    if "://" not in url:
+        url = "http://" + url
+    try:
+        return urlparse(url).hostname or ""
+    except Exception:
+        return ""
+
+
+class CustomCORSMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request: fastapi.Request, call_next):
+        host: str = request.headers.get("host", "")
+        origin: str = request.headers.get("origin", "")
+        host_name = get_hostname(host)
+        origin_name = get_hostname(origin)
+
+        # Any of these hosts suggests that the Gradio app is running locally.
+        # Note: "null" is a special case that happens if a Gradio app is running
+        # as an embedded web component in a local static webpage.
+        localhost_aliases = ["localhost", "127.0.0.1", "0.0.0.0", "null"]
+        is_preflight = (
+            request.method == "OPTIONS"
+            and "access-control-request-method" in request.headers
+        )
+
+        if host_name in localhost_aliases and origin_name not in localhost_aliases:
+            allow_origin_header = None
+        else:
+            allow_origin_header = origin
+
+        if is_preflight:
+            response = fastapi.Response()
+        else:
+            response = await call_next(request)
+
+        if allow_origin_header:
+            response.headers["Access-Control-Allow-Origin"] = allow_origin_header
+        response.headers[
+            "Access-Control-Allow-Methods"
+        ] = "GET, POST, PUT, DELETE, OPTIONS"
+        response.headers[
+            "Access-Control-Allow-Headers"
+        ] = "Origin, Content-Type, Accept"
+        return response

gradio/routes.py

@@ -29,7 +29,6 @@
 import markupsafe
 import orjson
 from fastapi import BackgroundTasks, Depends, FastAPI, HTTPException, status
-from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import (
     FileResponse,
     HTMLResponse,
@@ -55,6 +54,7 @@
 from gradio.processing_utils import add_root_url
 from gradio.queueing import Estimation
 from gradio.route_utils import (  # noqa: F401
+    CustomCORSMiddleware,
     FileUploadProgress,
     FileUploadProgressNotQueuedError,
     FileUploadProgressNotTrackedError,
@@ -196,12 +196,7 @@ def create_app(
         app.configure_app(blocks)
 
         if not wasm_utils.IS_WASM:
-            app.add_middleware(
-                CORSMiddleware,
-                allow_origins=["*"],
-                allow_methods=["*"],
-                allow_headers=["*"],
-            )
+            app.add_middleware(CustomCORSMiddleware)
 
         @app.get("/user")
         @app.get("/user/")

test/test_routes.py

@@ -462,6 +462,24 @@ def test_can_get_config_that_includes_non_pickle_able_objects(self):
         response = client.get("/config/")
         assert response.is_success
 
+    def test_cors_restrictions(self):
+        io = gr.Interface(lambda s: s.name, gr.File(), gr.File())
+        app, _, _ = io.launch(prevent_thread_lock=True)
+        client = TestClient(app)
+        custom_headers = {
+            "host": "localhost:7860",
+            "origin": "https://example.com",
+        }
+        file_response = client.get("/config", headers=custom_headers)
+        assert "access-control-allow-origin" not in file_response.headers
+        custom_headers = {
+            "host": "localhost:7860",
+            "origin": "127.0.0.1",
+        }
+        file_response = client.get("/config", headers=custom_headers)
+        assert file_response.headers["access-control-allow-origin"] == "127.0.0.1"
+        io.close()
+
 
 class TestApp:
     def test_create_app(self):