1 files changed, 111 insertions, 0 deletions
diff --git a/toolkit/components/antitracking/ContentBlockingAllowList.sys.mjs b/toolkit/components/antitracking/ContentBlockingAllowList.sys.mjs
new file mode 100644
index 0000000000..af1028083c
--- /dev/null
+++ b/toolkit/components/antitracking/ContentBlockingAllowList.sys.mjs
@@ -0,0 +1,111 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
+});
+
+/**
+ * A helper module to manage the Content Blocking Allow List.
+ *
+ * This module provides a couple of utility APIs for adding or
+ * removing a given browser object to the Content Blocking allow
+ * list.
+ */
+export const ContentBlockingAllowList = {
+  _observingLastPBContext: false,
+
+  _maybeSetupLastPBContextObserver() {
+    if (!this._observingLastPBContext) {
+      this._observer = {
+        QueryInterface: ChromeUtils.generateQI([
+          "nsIObserver",
+          "nsISupportsWeakReference",
+        ]),
+
+        observe(subject, topic, data) {
+          if (topic == "last-pb-context-exited") {
+            Services.perms.removeByType("trackingprotection-pb");
+          }
+        },
+      };
+      Services.obs.addObserver(this._observer, "last-pb-context-exited", true);
+      this._observingLastPBContext = true;
+    }
+  },
+
+  _basePrincipalForAntiTrackingCommon(browser) {
+    let principal =
+      browser.browsingContext.currentWindowGlobal
+        ?.contentBlockingAllowListPrincipal;
+    // We can only use content principals for this purpose.
+    if (!principal || !principal.isContentPrincipal) {
+      return null;
+    }
+    return principal;
+  },
+
+  _permissionTypeFor(browser) {
+    return lazy.PrivateBrowsingUtils.isBrowserPrivate(browser)
+      ? "trackingprotection-pb"
+      : "trackingprotection";
+  },
+
+  _expiryFor(browser) {
+    return lazy.PrivateBrowsingUtils.isBrowserPrivate(browser)
+      ? Ci.nsIPermissionManager.EXPIRE_SESSION
+      : Ci.nsIPermissionManager.EXPIRE_NEVER;
+  },
+
+  /**
+   * Returns false if this module cannot handle the current document loaded in
+   * the browser object.  This can happen for example for about: or file:
+   * documents.
+   */
+  canHandle(browser) {
+    return this._basePrincipalForAntiTrackingCommon(browser) != null;
+  },
+
+  /**
+   * Add the given browser object to the Content Blocking allow list.
+   */
+  add(browser) {
+    // Start observing PB last-context-exit notification to do the needed cleanup.
+    this._maybeSetupLastPBContextObserver();
+
+    let prin = this._basePrincipalForAntiTrackingCommon(browser);
+    let type = this._permissionTypeFor(browser);
+    let expire = this._expiryFor(browser);
+    Services.perms.addFromPrincipal(
+      prin,
+      type,
+      Services.perms.ALLOW_ACTION,
+      expire
+    );
+  },
+
+  /**
+   * Remove the given browser object from the Content Blocking allow list.
+   */
+  remove(browser) {
+    let prin = this._basePrincipalForAntiTrackingCommon(browser);
+    let type = this._permissionTypeFor(browser);
+    Services.perms.removeFromPrincipal(prin, type);
+  },
+
+  /**
+   * Returns true if the current browser has loaded a document that is on the
+   * Content Blocking allow list.
+   */
+  includes(browser) {
+    let prin = this._basePrincipalForAntiTrackingCommon(browser);
+    let type = this._permissionTypeFor(browser);
+    return (
+      Services.perms.testExactPermissionFromPrincipal(prin, type) ==
+      Services.perms.ALLOW_ACTION
+    );
+  },
+};