edit_inline Manipulator processor allows "stealing" of related objects

[jag@…]

This may be the desired behavior, but I'd probably consider it a security bug. I'll let you decide, and if you agree, I'll come up with a patch for it...

Let's say I have a shopping cart system. So I have two models:

 class ShoppingCart(models.Model):
   # ... snip ...
 
 class ShoppingCartItem(models.Model):
   shoppingcart = models.ForeignKey(ShoppingCart, edit_inline=models.STACKED)
   product = models.ForeignKey(Product, core=True)
   quantity = models.IntegerField()
   # ... snip ...

Then I have a view using django.views.generic.create_update.update_object and a template that contains:

 
 <form action="." method="post">
  <input type="text" name="shoppingcartitem.0.id" value="3" />
  <input type="text" name="shoppingcartitem.0.product" value="3" />
  <input type="text" name="shoppingcartitem.0.quantity" value="3" />
  <input type="submit" />
 </form>
 

If Alice creates a shopping cart with one item, 3 "Product 3"'s as above, and then Mallory comes in to her own shopping cart (not actually accessing the same ShoppingCart object as Alice but a distinct on of her own) and posts to this view with the values: shoppingcartitem.0.id=3&shoppingcartitem.0.product=3&shoppingcartitem.0.quantity=100, the item will be removed from Alice's cart and placed into Mallory's cart with a quantity of 100.

I would expect that Django would beef about either a) letting Mallory reassign the ForeignKey value for ShoppingCartItem(pk=3) or b) letting Mallory alter the value of ShoppingCartItem's not related to the ShoppingCart object she's viewing. Neither occurs.

Thoughts?

-jag

[Gary Wilson <gary.wilson@…>]

seems like a nasty bug to me.

[Fast exchanger]

Cool website! Your web site is helpful, All the best!

[James Bennett]

A foreign key is just a foreign key; it has no inherent "meaning". If the Bar model has a foreign key to Foo, that could mean "User A owns this instance and changing it is a security breach", but it could also mean "User A is working with this instance right now but User B can take it over" or it could "mean" something else entirely. It's up to you -- the developer of your specific application -- to decide what the foreign key "means" and implement the appropriate logic.