gstack/extension/sender-auth.js

66 lines
3.3 KiB
JavaScript

/**
* gstack browse — sender authorization for privileged extension messages
*
* Single decision point for which chrome.runtime.onMessage senders may read
* or spend the browse server's auth token and port. Loaded into the
* background service worker via importScripts() (classic worker — see
* manifest.json) and require()-able from bun tests
* (browse/test/extension-sender-auth.test.ts).
*
* Policy: privileged types are for this extension's own pages only
* (sidepanel / popup — sender.url is chrome-extension://<own id>/...).
* Content scripts run in web-page context (sender.tab is set, sender.url is
* the page URL) and can be influenced by page content; foreign extensions
* have a different sender.id. Both are denied, and a denied sender gets
* { error: 'unauthorized' } with no other fields — never the token, never
* the port. This mirrors the server side of the v1.63 token model: the
* browse server releases AUTH_TOKEN only to the pinned extension Origin via
* POST /extension-token, so the extension must not re-leak it to contexts
* the server would never have trusted.
*/
(function (root) {
'use strict';
// Message types that return or spend the auth token / server port, or leak
// privileged browser state. Every other type in background.js's allowlist
// stays reachable from content scripts — the inspector flow (elementPicked,
// pickerCancelled, inspectResult) and openSidePanel are content-script-
// originated by design.
const PRIVILEGED_TYPES = new Set([
'getPort', // response carries port + connected state + token
'setPort', // repoints the token-bearing client at another port
'getServerUrl', // response carries the server URL (port)
'getToken', // response carries the token
'fetchRefs', // spends the token on an authorized /refs fetch
'command', // spends the token on an arbitrary browse command
'sidebar-command', // spends the token on a server POST
'getTabState', // response carries every open tab's URL + title
]);
// Extension-page senders only: popup / sidepanel / options. A content
// script has sender.tab set and a web-page sender.url; a foreign extension
// has a different sender.id; a sender with no URL has no provenance at all.
// All three are denied.
function isExtensionPageSender(sender, ownExtensionId) {
if (!sender || !ownExtensionId) return false;
if (sender.id !== ownExtensionId) return false;
if (sender.tab) return false;
if (typeof sender.url !== 'string') return false;
return sender.url.startsWith('chrome-extension://' + ownExtensionId + '/');
}
// Returns null when the message may proceed, or the exact response a
// denied sender receives: { error: 'unauthorized' } and nothing else.
function denialFor(msgType, sender, ownExtensionId) {
if (!PRIVILEGED_TYPES.has(msgType)) return null;
if (isExtensionPageSender(sender, ownExtensionId)) return null;
return { error: 'unauthorized' };
}
const api = { PRIVILEGED_TYPES, isExtensionPageSender, denialFor };
if (typeof module !== 'undefined' && module.exports) {
module.exports = api; // bun test (CommonJS require)
}
root.gstackSenderAuth = api; // importScripts() in the service worker
})(typeof self !== 'undefined' ? self : globalThis);