Re: kernel allows loadkeys to be used by any user, allowing for local root compromise

[Rudolf Polzer]

Scripsis, quam aut quem »Krzysztof Halasa« appellare soleo:
> Rudolf Polzer <debian-ne@xxxxxxxxxxxx> writes:
> > However, pool computers like in this case are neither servers nor
> > terminals.  If they were terminals, we would need about 30 servers to
> > handle the load of 100 active students. So they are workstation
> > installations that do most of the work locally.
> 
> Ok. So they are exposed to known attacks with quite high probability.

Which others? Are there other places that assume only trusted users can access
the console?

> >> Hope they don't change the keys in the process.
> >
> > They HAVE to do that,
> 
> Well, I meant physical keys to match them to loaded keymaps :-)

;)

> > However, Xorg and XFree86 have about the same problem: you can remap
> > Ctrl-Alt-Backspace. So it would be good if the SAK also worked there which
> > would require it to set a "sane" video mode.
> 
> I assume that one can notice that Ctrl-Alt-Backspace doesn't work,
> and stop there.

Not if a malicious X program does "chvt 1; chvt 7" when Ctrl-Alt-Backspace is
pressed.

> I think SAK/X11 video mode issue is possible to fix, though.

It would require a video driver that can actually reset the video mode.
Framebuffer drivers usually can do that. For the standard VGA text mode, at
least savetextmode/restoretextmode from svgalib don't work on the graphics
cards I have.
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