security-and-privacy/CanvasBlocker
security-and-privacy/CanvasBlocker
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Removed bug with faking webgl and added readPixels for webgl2.

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Fixes #96 and #97.
This commit is contained in:
kkapsner 2016-12-26 14:36:01 +01:00
parent 6748771402
commit 6d7a9fc22a
2 changed files with 63 additions and 54 deletions
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92
lib/intercept.js
View File

@ -26,56 +26,58 @@
if (siteStatus.mode !== "allow"){
apiNames.forEach(function(name){
var changedFunction = changedFunctions[name];
var original = window.wrappedJSObject[changedFunction.object].prototype[name];
if (changedFunction.getStatus(undefined, siteStatus).active){
Object.defineProperty(
window.wrappedJSObject[changedFunction.object].prototype,
name,
{
enumerable: true,
configureable: false,
get: function(){
if (!window.location.href){
return undef;
}
var error = new Error();
if (checkStack(error.stack)){
return original;
}
var funcStatus = changedFunction.getStatus(this, siteStatus);
if (funcStatus.active){
if (funcStatus.mode === "ask"){
funcStatus.mode = ask({window: window, type: changedFunction.type, canvas: this, errorStack: error.stack});
(Array.isArray(changedFunction.object)? changedFunction.object: [changedFunction.object]).forEach(function(object){
var original = window.wrappedJSObject[object].prototype[name];
Object.defineProperty(
window.wrappedJSObject[object].prototype,
name,
{
enumerable: true,
configureable: false,
get: function(){
if (!window.location.href){
return undef;
}
switch (funcStatus.mode){
case "allow":
return original;
case "fake":
setRandomSupplyByType(prefs("rng"));
var fake = changedFunction.fakeGenerator(prefs, function(messageId){
notify({url: window.location.href, errorStack: error.stack, messageId});
}, original);
switch (fake){
case true:
return original;
case false:
return undef;
default:
return exportFunction(fake, window.wrappedJSObject);
}
//case "block":
default:
return undef;
var error = new Error();
if (checkStack(error.stack)){
return original;
}
var funcStatus = changedFunction.getStatus(this, siteStatus);
if (funcStatus.active){
if (funcStatus.mode === "ask"){
funcStatus.mode = ask({window: window, type: changedFunction.type, canvas: this, errorStack: error.stack});
}
switch (funcStatus.mode){
case "allow":
return original;
case "fake":
setRandomSupplyByType(prefs("rng"));
var fake = changedFunction.fakeGenerator(prefs, function(messageId){
notify({url: window.location.href, errorStack: error.stack, messageId});
}, original);
switch (fake){
case true:
return original;
case false:
return undef;
default:
return exportFunction(fake, window.wrappedJSObject);
}
//case "block":
default:
return undef;
}
}
else {
return original;
}
}
else {
return original;
}
}
}
);
);
});
}
});
}

25
lib/modifiedAPI.js
View File

@ -17,30 +17,37 @@
window.HTMLCanvasElement.prototype.getContext.call(canvas, "experimental-webgl2");
}
function getImageData(window, context){
var imageData;
var source;
if (context instanceof window.CanvasRenderingContext2D){
return window.CanvasRenderingContext2D.prototype.getImageData.call(context, 0, 0, context.canvas.width, context.canvas.height);
imageData = window.CanvasRenderingContext2D.prototype.getImageData.call(context, 0, 0, context.canvas.width, context.canvas.height);
source = imageData.data;
}
else {
var imageData = new window.wrappedJSObject.ImageData(context.canvas.width, context.canvas.height);
var source = new Uint8Array(imageData.data.length);
window.WebGLRenderingContext.prototype.readPixels.call(
context,
0, 0, context.canvas.width, context.canvas.height,
context.RGBA, context.UNSIGNED_BYTE,
imageData.data
source
);
return imageData;
}
return {
imageData,
source
};
}
function getFakeCanvas(window, original){
var context = getContext(window, original);
var imageData = getImageData(window, context);
var data = imageData.data;
var l = data.length;
var {imageData, source} = getImageData(window, context);
var desc = imageData.data;
var l = desc.length;
var rng = randomSupply.getRng(l, window);
for (var i = 0; i < l; i += 1){
data[i] = rng(data[i], i);
for (var i = 0; i < l; i += 10){
desc[i] = rng(source[i], i);
}
var canvas = original.cloneNode(true);
context = window.HTMLCanvasElement.prototype.getContext.call(canvas, "2d");
@ -249,7 +256,7 @@
status.active = hasType(status, "readout") || hasType(status, "input");
return status;
},
object: "WebGLRenderingContext",
object: ["WebGLRenderingContext", "WebGL2RenderingContext"],
fakeGenerator: function(prefs, notify){
return function readPixels(x, y, width, height, format, type, pixels){
// not able to use the getFakeCanvas function because the context type is wrong...