[whatwg] [Web-storage] subdomains / cooperation and limits
ian at hixie.ch
Mon Sep 17 17:22:08 PDT 2012
On Mon, 17 Sep 2012, Brian Kardell wrote:
> Ian, you hit the nail on the head with the text section that raised the
> issue but I still am not entirely sure that I understand... Doesn't this
> imply that in a case like *.wordpress.com would have a (suggested) limit
> of 5mb combined for all of its tons and tons of subdomains (at least
> without additional/constant prompting)?
It wouldn't be "constant" prompting, but yes, the spec does suggest that
if you visit a dozen WordPress-hosted blogs and they all try to load a
bunch of content onto your machine, you should probably have to give
consent or at least be aware of what's going on.
> There are a whole lot of what I would call "common" examples like where
> it seems (to me anyway) unintuitive given the regularity with which this
> kind of case would happen to think that that is what is actually
What's the alternative? Allowing any site to overload your machine with
infinite amounts of content isn't really a viable solution.
> I can understand blocking access to that data pretty easily, but with
> postMessage, being in the same top-level domain doesn't even matter so
> it seems that one could just as easily "subvert the limit" that way.
The difference is that getting a new domain costs money, whereas getting a
subdomain does not. So the cost of attacking someone with subdomains is
much lower than with domains.
> I think it isn't really implemented that way anywhere though, is it?
> That is, do browsers really share the limit across subdomains like
If they do not, they are likely vulnerable to this kind of griefing.
Ian Hickson U+1047E )\._.,--....,'``. fL
http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,.
Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
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