security-and-privacy/CanvasBlocker
security-and-privacy/CanvasBlocker
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Code Releases Activity

Added askOnlyOnce and blockReadout and major code changes

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This commit is contained in:
kkapsner 2014-10-08 03:16:23 +02:00
parent 4c2596f880
commit b2f6aee8f9
6 changed files with 199 additions and 59 deletions
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canvasblocker.xpi
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197
data/inject.js
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@ -1,8 +1,78 @@
/* global self, window, console, unsafeWindow */
(function(){
"use strict";
var getContext = unsafeWindow.HTMLCanvasElement.prototype.getContext;
var originalGetContext = unsafeWindow.HTMLCanvasElement.prototype.getContext;
var originalToDataURL = unsafeWindow.HTMLCanvasElement.prototype.toDataURL;
var originalGetImageData = unsafeWindow.CanvasRenderingContext2D.prototype.getImageData;
var askFunctionName = Math.random().toString(16);
function transformFunctionToUnsafeWindow(func, name){
var funcString = func.toString();
var parameter = funcString.match(/^function\s*\(([^\)]*)\)\s*\{/)[1];
funcString = funcString
.replace(/^function\s*\(([^\)]*)\)\s*\{|\}\s*$/g, "")
.replace(/(^|\n|\r)\t{3}/g, "$1")
.replace(/askFunctionName/g, JSON.stringify(askFunctionName))
.replace(/askForPermission/g, _("askForPermission"))
.replace(/askForInvisiblePermission/g, _("askForInvisiblePermission"));
var unsafeFunction = new unsafeWindow.Function(parameter, funcString);
unsafeFunction.toString =
unsafeFunction.toLocaleString =
unsafeFunction.toSource = new unsafeWindow.Function(
"return \"function " + name + "() {\\n [native code]\\n}\";"
);
return unsafeFunction;
}
function setAPIFunctions(getContext, toDataURL, getImageData){
delete unsafeWindow.HTMLCanvasElement.prototype[askFunctionName];
if (getContext){
if (getContext === true){
getContext = originalGetContext;
}
else {
var secretObject = new unsafeWindow.Object();
Object.defineProperties(
secretObject,
{
getContext: {value: originalGetContext},
confirm: {value: unsafeWindow.confirm}
}
);
Object.defineProperty(
unsafeWindow.HTMLCanvasElement.prototype,
askFunctionName,
{
value: secretObject,
configurable: true,
enumerable: false
}
);
getContext = transformFunctionToUnsafeWindow(getContext, "getContext");
}
}
unsafeWindow.HTMLCanvasElement.prototype.getContext = getContext;
if (toDataURL){
if (toDataURL === true){
toDataURL = originalToDataURL;
}
else {
toDataURL = transformFunctionToUnsafeWindow(toDataURL, "toDataURL");
}
}
unsafeWindow.HTMLCanvasElement.prototype.toDataURL = toDataURL;
if (getImageData){
if (getImageData === true){
getImageData = originalGetImageData;
}
else {
getImageData = transformFunctionToUnsafeWindow(getImageData, "getImageData");
}
}
unsafeWindow.CanvasRenderingContext2D.prototype.getImageData = getImageData;
}
function checkPDF(blocking){
if (document.contentType.match(/\/pdf$/i)){
@ -14,24 +84,14 @@
function block(force){
if (force || !checkPDF("block")){
// consoe.log("block");
delete unsafeWindow.HTMLCanvasElement.prototype[askFunctionName];
unsafeWindow.HTMLCanvasElement.prototype.getContext = null;
setAPIFunctions(null, null, null);
}
}
function askVisible(force){
function askVisible(force, askOnlyOnce){
if (force || !checkPDF("askVisible")){
Object.defineProperty(
unsafeWindow.HTMLCanvasElement.prototype,
askFunctionName,
{
value: getContext,
enumerable: false
}
);
unsafeWindow.HTMLCanvasElement.prototype.getContext = new unsafeWindow.Function(
setAPIFunctions(
askOnlyOnce?
function(){
if (this.parentNode){
var oldBorder = this.style.border;
@ -41,11 +101,37 @@
// catch (e){
// console.log(e.stack.split(/\s*(?:-?>|@)\s*/));
// }
var allow = confirm(confirmText);
var allow = this[askFunctionName].confirm.call(window, confirmText);
this.style.border = oldBorder;
if (allow){
this.getContext = this["askFunctionName"];
return this["askFunctionName"].apply(this, arguments);
HTMLCanvasElement.prototype.getContext = this[askFunctionName].getContext;
delete HTMLCanvasElement.prototype[askFunctionName];
return this.getContext.apply(this, arguments);
}
else {
HTMLCanvasElement.prototype.getContext = null;
delete HTMLCanvasElement.prototype[askFunctionName];
return null;
}
}
else {
return null;
}
}:
function(){
if (this.parentNode){
var oldBorder = this.style.border;
this.style.border = "2px dashed red";
var confirmText = "askForPermission";
// try {throw new Error();}
// catch (e){
// console.log(e.stack.split(/\s*(?:-?>|@)\s*/));
// }
var allow = this[askFunctionName].confirm.call(window, confirmText);
this.style.border = oldBorder;
if (allow){
this.getContext = this[askFunctionName].getContext;
return this.getContext.apply(this, arguments);
}
else {
this.getContext = null;
@ -55,25 +141,16 @@
else {
return null;
}
}.toString()
.replace(/^function\s*\(\)\s*\{|\}\s*$/g, "")
.replace(/askFunctionName/g, askFunctionName)
.replace(/askForPermission/g, _("askForPermission"))
},
true,
true
);
}
}
function askInvisible(force){
function askInvisible(force, askOnlyOnce){
if (force || !checkPDF("askInvisible")){
Object.defineProperty(
unsafeWindow.HTMLCanvasElement.prototype,
askFunctionName,
{
value: getContext,
enumerable: false
}
);
unsafeWindow.HTMLCanvasElement.prototype.getContext = new unsafeWindow.Function(
setAPIFunctions(
askOnlyOnce?
function(){
var oldBorder = this.style.border;
this.style.border = "2px dashed red";
@ -81,32 +158,63 @@
this.parentNode?
"askForPermission":
"askForInvisiblePermission";
var allow = confirm(confirmText);
var allow = this[askFunctionName].confirm.call(window, confirmText);
this.style.border = oldBorder;
if (allow){
this.getContext = this["askFunctionName"];
return this["askFunctionName"].apply(this, arguments);
HTMLCanvasElement.prototype.getContext = this[askFunctionName].getContext;
delete HTMLCanvasElement.prototype[askFunctionName];
return this.getContext.apply(this, arguments);
}
else {
HTMLCanvasElement.prototype.getContext = null;
delete HTMLCanvasElement.prototype[askFunctionName];
return null;
}
}:
function(){
var oldBorder = this.style.border;
this.style.border = "2px dashed red";
var confirmText =
this.parentNode?
"askForPermission":
"askForInvisiblePermission";
var allow = this[askFunctionName].confirm.call(window, confirmText);
this.style.border = oldBorder;
if (allow){
this.getContext = this[askFunctionName].getContext;
return this.getContext.apply(this, arguments);
}
else {
this.getContext = null;
return null;
}
}.toString()
.replace(/^function\s*\(\)\s*\{|\}\s*$/g, "")
.replace(/askFunctionName/g, askFunctionName)
.replace(/askForPermission/g, _("askForPermission"))
.replace(/askForInvisiblePermission/g, _("askForInvisiblePermission"))
},
true,
true
);
}
}
function blockReadout(force){
if (force || !checkPDF("blockReadout")){
setAPIFunctions(
true,
function(){
return "data:image/png;base64";
},
function(sx, sy, sw, sh){
var imageData = this.createImageData(sw, sh);
return imageData;
}
);
}
}
function unblock(){
// console.log("unblock");
unsafeWindow.HTMLCanvasElement.prototype.getContext = getContext;
setAPIFunctions(true, true, true);
}
var _ = function(name){
return _[name] || name;
}
};
self.port.on("setTranslation", function(name, translation){
_[name] = translation;
});
@ -115,6 +223,7 @@
self.port.on("block", block);
self.port.on("askVisible", askVisible);
self.port.on("askInvisible", askInvisible);
self.port.on("blockReadout", blockReadout);
self.port.on("unblock", unblock);
//self.port.on("detach", unblock); // produces memory leak due to the reference to unsafeWindow
}());

41
lib/main.js
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@ -85,54 +85,67 @@
// }
function checkWorker(worker){
var url = new URL(worker.url);
var mode = "block";
switch (prefs.blockMode){
case "blockEverything":
worker.port.emit("block");
mode = "block";
break;
case "allowOnlyWhiteList":
if (whiteList.match(url)){
worker.port.emit("unblock");
mode = "unblock";
}
else {
worker.port.emit("block");
mode = "block";
}
break;
case "askVisible":
if (whiteList.match(url)){
worker.port.emit("unblock");
mode = "unblock";
}
else if (blackList.match(url)){
worker.port.emit("block");
mode = "block";
}
else {
worker.port.emit("askVisible");
mode = "askVisible";
}
break;
case "askInvisible":
if (whiteList.match(url)){
worker.port.emit("unblock");
mode = "unblock";
}
else if (blackList.match(url)){
worker.port.emit("block");
mode = "block";
}
else {
worker.port.emit("askInvisible");
mode = "askInvisible";
}
break;
case "blockReadout":
if (whiteList.match(url)){
mode = "unblock";
}
else if (blackList.match(url)){
mode = "block";
}
else {
mode = "blockReadout";
}
break;
case "blockOnlyBlackList":
if (blackList.match(url)){
worker.port.emit("block");
mode = "block";
}
else {
worker.port.emit("unblock");
mode = "unblock";
}
break;
case "allowEverything":
worker.port.emit("unblock");
mode = "unblock";
break;
default:
console.log("Unknown blocking mode.");
console.log("Unknown blocking mode. Default to block everything.");
}
worker.port.emit(mode, false, prefs.askOnlyOnce);
}
@ -151,7 +164,7 @@
this.emit("unblock");
}
else {
this.emit(blocking, true);
this.emit(blocking, true, prefs.askOnlyOnce);
}
});
worker.port.emit("setTranslation", "askForPermission", _("askForPermission"));

4
locale/de-DE.properties
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@ -11,9 +11,13 @@ blockMode_options.block everything= alles blockieren
blockMode_options.allow only white list= nur Einträge der Whitelist erlauben
blockMode_options.ask for permission for visible <canvas>= bei sichtbaren <canvas> um Erlaubnis fragen
blockMode_options.ask for permision for invisible <canvas>= bei unsichtbaren <canvas> um Erlaubnis fragen
blockMode_options.block readout API= Auslese-API blockieren
blockMode_options.block only black list= nur Einträge der Blacklist blockieren
blockMode_options.allow everything= alles erlauben
askOnlyOnce_title= Nur einmal nachfragen
askOnlyOnce_description= Wenn eine Seite öfters versucht, die <canvas>-API abzurufen, erscheint jedes mal eine Nachfrage. Mit diesem Schalter wird pro Seitenbesuch nur einmal nachgefragt. Bei manchen Seiten kann es trotzdem zu mehrmaligem Nachfragen kommen.
allowPDFCanvas_title= <canvas> in PDFs erlauben
allowPDFCanvas_description= Die native pdf.js verwendet <canvas> um den Inhalt von PDFs anzuzeigen. Wenn dies nicht markiert ist, werden viele Nachfragedialoge erscheinen oder die PDF Ansicht nicht funktionieren.

4
locale/en-US.properties
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@ -11,9 +11,13 @@ blockMode_options.block everything= block everything
blockMode_options.allow only white list= allow only white list
blockMode_options.ask for permission for visible <canvas>= ask for permission for visible <canvas>
blockMode_options.ask for permision for invisible <canvas>= ask for permision for invisible <canvas>
blockMode_options.block readout API= block readout API
blockMode_options.block only black list= block only black list
blockMode_options.allow everything= allow everything
askOnlyOnce_title= Ask only once
askOnlyOnce_description= If a page tries to access the <canvas>-API several times a confirm message will appear every time. This switch tries to make only one confirmation. Never the less on some pages there will be more.
allowPDFCanvas_title= Allow canvas in PDFs
allowPDFCanvas_description= The native pdf.js uses <canvas> to display the PDF content. If this is unchecked there will lots of annoying ask dialogs or the PDF display will not work.

12
package.json
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@ -38,6 +38,10 @@
"value": "askInvisible",
"label": "ask for permision for invisible <canvas>"
},
{
"value": "blockReadout",
"label": "block readout API"
},
{
"value": "blockOnlyBlackList",
"label": "block only black list"
@ -48,6 +52,12 @@
}
]
},
{
"name": "askOnlyOnce",
"title": "Ask only once",
"type": "bool",
"value": false
},
{
"name": "allowPDFCanvas",
"title": "Allow canvas in PDFs",
@ -57,6 +67,6 @@
],
"author": "Korbinian Kapsner",
"license": "MPL 2.0",
"version": "0.1.3",
"version": "0.1.4",
"permissions": {"private-browsing": true}
}