[Pkg-kbd-devel] Bug#522453: fgconsole doesn't work as user

[Michael Schutte]

retitle 522453 non-root users cannot access the console from X
tags 522453 + wontfix
thanks

Hi Mauro,

Thanks for your report.

On Fri, Apr 03, 2009 at 10:51:11PM +0200, Mauro Sacchetto wrote:
> When I enter in a console, fgconsole works always fine.
> If I launch after the X-server, fgconsole works again.
> But if I enter with automatic login in X-server as simple user
> (I use KDE), fgconsole does work no more:
> ======================================================
> samiel at debian:~$ fgconsole
> Couldnt get a file descriptor referring to the console
> ======================================================
> for all /dev/tty are root's ownership.
> So it works fine only for root.

This is true.  It doesn’t only affect fgconsole, but also chvt, openvt
and any other kbd utility which tries to get a console file descriptor.
These programs do their job by trying to open/ioctl these files (in this
order):

	/proc/self/fd/0		(is a pseudo tty in your case)
	/dev/tty		(also PTY)
	/dev/tty0		(only accessible to root)
	/dev/vc/0		(doesn’t exist nowadays)
	/dev/console		(root)
	std{in,out,err}		(PTY)

As none of these is able to respond to a VT_GETSTATE ioctl, fgconsole
and friends fail.  I’m afraid this situation won’t change.

Have a look at sudo if you need unprivileged users to run these
utilities in a secure manner.

All the best,
-- 
Michael Schutte <michi at uiae.at>
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