On 5/28/10 9:04 AM, Don Pinkster wrote:
My 2 cents:
Why don't we use something as attr_accessible in Ruby on Rails?
This way you can specify which attributes may be set with mass assignment
($form->bind()); and need to be set with explicit setters: $form->setValue()?
We don't have mass-assignement problems with symfony, just remove the
fields you don't want the user to modify.
Now I write this, isnt this wat $this->useOnly() is meant for?
Exactly. You can also just unset() fields.
Fabien
-----Original Message-----
From: "Kris Wallsmith"<[email protected]>
Sent: Friday, 28 May, 2010 07:17
To: "symfony developers"<[email protected]>
Subject: [symfony-devs] Re: Potential Flaw in the Form Framework [1.4]
I've attached a patch to the ticket for review. Please comment.
http://trac.symfony-project.org/ticket/8639
Thanks,
Kris
On 10 May, 12:08, Stephen Melrose<[email protected]> wrote:
It's not that simple Russ.
Where do you perform the check that they are allowed to access/save an
object of a certain ID?
I personally have always checked the object after I've taken it from the
route and before I've passed it to the form. After I've done that, I don't
expect the object to magically be transformed into another record, a.k.a.
something they're not allowed to access, and I bet the vast majority of
symfony developers don't either.
Your point is valid and one I've agreed with throughout this thread, if
you're restricting what a user can edit, you need to make sure you safe
guard your code properly, and that's something I didn't do purely because I
didn't expect the scenario I've detailed to occur, and to be honest, nor
should it.
The ID is passed as a hidden field (for whatever reason), but I don't expect
the PK to be changed. How often would you actually edit a PK?
I'm simply arguing the PK should be read only be default.
On 10 May 2010 20:01, Russ<[email protected]> wrote:
Personally I always check if the user has credentials to edit the
object anyway and I couldn't give a monkeys if they change the id
using Firebug or whatever as long as it's to one they have access to.
If not, they'll get a nice 403 response either way.
The way I see it, editing the ID using Firebug or some other method
would be just the same as if they opened that object up for editing in
the first place... As long as they are allowed to, then so be it.
On May 10, 12:16 pm, Stephen Melrose<[email protected]> wrote:
Hi,
We have discovered what could be a potential flaw in the form
framework. The reason I'm discussing this here is because I'm in mixed
feelings as to whether this is actually bug or not, or rather poor
implementation on our part. Either way, I'm also saying this flaw
should be safe guarded against.
We discovered that a malicious user can use the forms generated by the
form framework to edit content they shouldn't be able to.
They do this by replacing the primary ID in the hidden form field with
that of the record they want to edit. When they hit save, the
validation is run, and the Object is updated with the new ID, so when
the save() is called, the other row is updated.
Now, if we (as in developers) want to restrict editing of content for
certain users, then it is our responsibility to make sure we put safe
guards in place. I'm not arguing this fact.
The reason I believe this to be a problem is how users will actually
guard their code. Most people (including myself) run all the safe
guard checks before the Object is passed into the Form on
construction. I don't then expect the POST data to override the
primary key of the Object on save. Infact, I can't think of an
instance I would ever want this to happen.
I therefore propose that some sort of restriction/block is put in
place by default that stops the PK of an Object being altered on
bind().
Thoughts?
Stephen Melrose
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