Re: documentation on permissions for cdrom device -- where?

[Kalle Olavi Niemitalo <tosi@ees2.oulu.fi>]

Wichert Akkerman <wakkerma@cs.leidenuniv.nl> writes:

> Previously Kalle Olavi Niemitalo wrote:
> > This solution isn't very good either, since the user can create a
> > setgid program when she's at the console and run it later.  Or she can
> > leave a shell running in screen(1).  Or just leave a process holding
> > the device open.
> 
> The obvious solution to that is the revoke() system call, which should
> be used by anything that does things like spawning a login-shell and
> giving away groups. It should be in the 2.1 kernels.

Okay, so that prevents her from just keeping the device open.  But how
about the two other ways, which rely on preserving the group id and
using it to open the device later?

You could mount all user-writable directories -o nosuid and kill all
user processes after she logs out, but that would seem rather fascist
to me.

Or did you mean to junk the groups and instead chown the
audio/scanner/whatever to the console user, like the tty devices are
chowned to their respective users?