Add privacy.resistFingerprinting.delegateCanvasProtection to allow po…

…wer users to delegate fingerprinting protection for canvas to extensions; without a properly configured extension, this disables RFP for the canvas entirely.

Signed-off-by: Matt Parnell <[email protected]>

dom/canvas/CanvasUtils.cpp

@@ -138,6 +138,18 @@ bool IsImageExtractionAllowed(Document* aDocument, JSContext* aCx,
 
   // At this point, permission is unknown
   // (nsIPermissionManager::UNKNOWN_ACTION).
+
+  // Check if the user has explicitly disabled all
+  // or delegated all other checks and fingerprinting resistence
+  // to an extension (or nothing) such as canvasblocker
+  bool isDelegateCanvasProtection =
+      StaticPrefs::
+          privacy_resistFingerprinting_delegateCanvasProtection() &&
+      !EventStateManager::IsHandlingUserInput();
+
+  if (isDelegateCanvasProtection) {
+    return true;
+  }
 
   // Check if the request is in response to user input
   bool isAutoBlockCanvas =

modules/libpref/init/StaticPrefList.h

@@ -2568,6 +2568,12 @@ VARCACHE_PREF(
   RelaxedAtomicBool, false
 )
 
+VARCACHE_PREF(
+  "privacy.resistFingerprinting.delegateCanvasProtection",
+   privacy_resistFingerprinting_delegateCanvasProtection,
+  RelaxedAtomicBool, false
+)
+
 VARCACHE_PREF(
   "privacy.storagePrincipal.enabledForTrackers",
    privacy_storagePrincipal_enabledForTrackers,

modules/libpref/init/all.js

@@ -1413,6 +1413,9 @@ sticky_pref("privacy.resistFingerprinting.block_mozAddonManager", false);
 // If you do set it, to work around some broken website, please file a bug with
 // information so we can understand why it is needed.
 pref("privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts", true);
+// In the event the end user wants to use RFP but wishes to fully enable the canvas
+// or delegate it's protection an extension, this option allows for it.
+pref("privacy.resistFingerprinting.delegateCanvasProtection", false);
 // The log level for browser console messages logged in RFPHelper.jsm
 // Change to 'All' and restart to see the messages
 pref("privacy.resistFingerprinting.jsmloglevel", "Warn");