Re: questions to planned lock-functionality for vts

[David Herrmann]

Hi

On Mon, Mar 23, 2015 at 11:29 AM,  <simone.weiss@xxxxxx> wrote:
>
>> Wait, what's wrong with the existing functionality?
>
> Userspace programms for screensavers can potentially be bypassed
> - if my scrennsaver dies, for example by segfault, my screen is unlocked
> - Redirection is only possible in Kernel, because a vt switch can only
>   be prevented there
> Also it would make the implementation of a Secure-Acess-Key possible
> (could also redirect to VT12)

By moving these calls into the kernel, you don't make them necessarily
fail-safe. This can all be implemented in user-space. By switching to
a dedicated VT (say, VT12) and running VT_SETMODE+VT_PROCESS, you lock
the machine. You can now implement your screensaver. If you run a
spawner-process, you're even safe if your screensaver crashes.

Thanks
David
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