Implement CSRF protection

backend/helpers.py

@@ -1,7 +1,20 @@
+from aiohttp.web import middleware, Response
 import ssl
 import certifi
+import uuid
 
 ssl_ctx = ssl.create_default_context(cafile=certifi.where())
 
+csrf_token = str(uuid.uuid4())
+
 def get_ssl_context():
-    return ssl_ctx
+    return ssl_ctx
+
+def get_csrf_token():
+    return csrf_token
+
+@middleware
+async def csrf_middleware(request, handler):
+    if str(request.method) == "OPTIONS" or request.headers.get('Authentication') == csrf_token or str(request.rel_url) == "/auth/token" or str(request.rel_url).startswith("/plugins/load_main/") or str(request.rel_url).startswith("/static/") or str(request.rel_url).startswith("/legacy/") or str(request.rel_url).startswith("/steam_resource/"):
+        return await handler(request)
+    return Response(text='Forbidden', status='403')

backend/legacy/library.js

@@ -8,10 +8,13 @@ window.addEventListener("message", function(evt) {
 }, false);
 
 async function call_server_method(method_name, arg_object={}) {
+    const token = await fetch("http://127.0.0.1:1337/auth/token").then(r => r.text());
     const response = await fetch(`http://127.0.0.1:1337/methods/${method_name}`, {
       method: 'POST',
+      credentials: "include",
       headers: {
         'Content-Type': 'application/json',
+        Authentication: token
       },
       body: JSON.stringify(arg_object),
     });
@@ -40,10 +43,13 @@ async function fetch_nocors(url, request={}) {
 async function call_plugin_method(method_name, arg_object={}) {
     if (plugin_name == undefined) 
         throw new Error("Plugin methods can only be called from inside plugins (duh)");
+    const token = await fetch("http://127.0.0.1:1337/auth/token").then(r => r.text());
     const response = await fetch(`http://127.0.0.1:1337/plugins/${plugin_name}/methods/${method_name}`, {
         method: 'POST',
+        credentials: "include",
         headers: {
-        'Content-Type': 'application/json',
+            'Content-Type': 'application/json',
+            Authentication: token
         },
         body: JSON.stringify({
             args: arg_object,

backend/main.py

@@ -20,12 +20,13 @@ from os import path
 from subprocess import call
 
 import aiohttp_cors
-from aiohttp.web import Application, run_app, static
+from aiohttp.web import Application, run_app, static, get, Response
 from aiohttp_jinja2 import setup as jinja_setup
 
 from browser import PluginBrowser
 from injector import inject_to_tab, tab_has_global_var
 from loader import Loader
+from helpers import csrf_middleware, get_csrf_token
 from utilities import Utilities
 from updater import Updater
 
@@ -41,9 +42,10 @@ class PluginManager:
     def __init__(self) -> None:
         self.loop = get_event_loop()
         self.web_app = Application()
+        self.web_app.middlewares.append(csrf_middleware)
         self.cors = aiohttp_cors.setup(self.web_app, defaults={
           "https://steamloopback.host": aiohttp_cors.ResourceOptions(expose_headers="*",
-                allow_headers="*")
+                allow_headers="*", allow_credentials=True)
         })
         self.plugin_loader = Loader(self.web_app, CONFIG["plugin_path"], self.loop, CONFIG["live_reload"])
         self.plugin_browser = PluginBrowser(CONFIG["plugin_path"], self.web_app, self.plugin_loader.plugins)
@@ -57,6 +59,8 @@ class PluginManager:
         self.loop.create_task(self.loader_reinjector())
         self.loop.create_task(self.load_plugins())
         self.loop.set_exception_handler(self.exception_handler)
+        self.web_app.add_routes([get("/auth/token", self.get_auth_token)])
+
         for route in list(self.web_app.router.routes()):
           self.cors.add(route)
         self.web_app.add_routes([static("/static", path.join(path.dirname(__file__), 'static'))])
@@ -67,6 +71,9 @@ class PluginManager:
             return
         loop.default_exception_handler(context)
 
+    async def get_auth_token(self, request):
+        return Response(text=get_csrf_token())
+
     async def wait_for_server(self):
         async with ClientSession() as web:
             while True: