Re: [patch 0/2] Tmpfs acls

[Gabor Gombas]

On Tue, Jan 10, 2006 at 12:07:58AM +0000, Matthew Garrett wrote:

> Handwavy problem scenario - user A logs in, is given access to the 
> soundcard. Starts running a program that when given appropriate signals 
> will record from the system microphone. Logs out. Waits for user B, who 
> he suspects is having an affair with his wife, and then monitors any 
> conversations that user B has. ACLs on their own don't seem to solve 
> this any more than just statically assigning group membership to users.

This scenario is not a permission but a locking problem. User B should
just claim the microphone exclusively and that should fail if user A
keeps an fd open.

For the generic case maybe a new lock type would be useful, that would
fail iff a process with a different effective UID keeps the device open.

Gabor

-- 
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     MTA SZTAKI Computer and Automation Research Institute
                Hungarian Academy of Sciences
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