On 3/28/06, Pavel Kankovsky <peak@argo.troja.mff.cuni.cz> wrote:
On Mon, 27 Mar 2006, Brian Eaton wrote:
You lost me here. How would you design a MAC policy that lets firefox
remember my password for a web site, but doesn't let arbitrary code
running via a buffer overflow get at that same password?
Let's call the object where the password is stored P, the subject
representing the site where P is used X, and the subject representing an
arbitrary evil site Y.
The (partial) mandatory policy is as follows:
1. X has "need to know" for P and is allowed to read it.
2. Y (or any other site) is not allowed to read P.
As soon as the browser process reads P, its (potential) ability to send
any data to Y is lost forever because information flow from P to Y is
prohibited by the mandatory policy. This is a dynamic variant of the
*-property of the Bell-LaPadula security model.
Ah, OK, I see what you're talking about now. I hadn't considered the
possibility of applying ACLs to network connections. The policy
design would be fairly tricky.
For one thing, you have proxy servers. When using a proxy, nearly all
of the connections are going to the same host.
Also, you have to deal with the many-to-many mapping of web sites to
IP addresses on the web. The ACL policy needs to say that the site
"www.example.com" has access to the password, but it is entirely
possible that "www.example.com" shares an IP address with several
other sites.
Regards,
Brian
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