Hi Andrea,
I'm really having a hard time understanding where the security issue is
here.
From what I understand, you've properly hidden the "Private" constructor.
I am not surprised if code can reach the [[Prototype]] of an instance
and I wouldn't consider that a flaw. I would consider that the
[[Prototype]] is part of the object and accessing the [[Prototype]] is
like accessing a property or the [[Class]], it's just introspection.
David
Le 17/03/2013 03:04, Andrea Giammarchi a écrit :
That conversation on `fn. caller` left me many doubts about extra
things too.
As example, I understand the fact a function that do not want to be
accessed should not be accessed when any accepted object could due
tweaked to retrieve it via caller, that's OK, but what about private
"classes" and the fact there's no way to ensure them private?
Despite the sense, the good and the bad, this is perfectly valid JS code:
var myNameSpace = function () {
var queue = [];
function Private() {
this.init();
}
function initBeforeDOM() {
queue.push(this);
}
function initAfterDOM() {
// do stuff
}
Private.prototype.init = initBeforeDOM;
window.addEventListener('DOMContentLoaded', function(){
Private.prototype.init = initAfterDOM;
queue.forEach(function (instance) {
initAfterDOM.call(instance);
});
});
// trying to make Private inaccessible
Object.defineProperty(
Private.prototype,
'constructor',
{value: Object,
enumerable:false,
writable:false,
configurable:false}
);
return {
generate: function () {
return new Private;
}
};
}();
var o = myNameSpace.generate();
var proto = Object.getPrototypeOf(o);
alert(proto.constructor);
alert(proto.init);
Above code is also based on few concepts I always found cool about JS
like the possibility to mutate all objects at once through the
prototype, usually considered a bad practice, but technically the
best/fastest/memory-safe way we have in JS to create state machines
behaviors through distributed instances so ... **way too cool**
Well, I've got a problem, even if the constructor might be
unreachable, there is something I cannot secure at all which is the
constructor prototype.
Not a single mechanism, in current JS, lets me make a prototype safe
from operations, potentially nasty and disastrous, as
`Object.getPrototypeOf(generic)` is.
Thoughts? Thanks.
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