Bug#334113: [Security] kernel allows loadkeys to be used by any user, allowing for local root compromise
On Mon, Oct 17, 2005 at 11:52:11PM -0700, Andrew Morton wrote:
> Horms <horms@verge.net.au> wrote:
> >
> > drivers/char/vt_ioctl.c: vt_ioctl(): line 377
> >
> > /*
> > * To have permissions to do most of the vt ioctls, we either
> > * have
> > * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
> > */
> > perm = 0;
> > if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
> > perm = 1;
> >
> >
> > A simple fix for this might be just checking for capable(CAP_SYS_TTY_CONFIG)
> > in do_kdgkb_ioctl(), which effects KDSKBSENT. This more restrictive
> > approach is probably appropriate for many of the other ioctls that set
> > VT parameters.
>
> I briefly discussed this with Alan and he agreed that that's a reasonable
> approach.
Thanks, thats pretty much what I had in mind. Though I would expect
some minor breakage, at least for people who expect nonsetuid loadkeys
to work. But then again, that is the whole point.
> I'll stick the below in -mm, see what breaks.
>
> --- devel/drivers/char/vt_ioctl.c~setkeys-needs-root 2005-10-17 23:50:37.000000000 -0700
> +++ devel-akpm/drivers/char/vt_ioctl.c 2005-10-17 23:51:43.000000000 -0700
> @@ -192,6 +192,9 @@ do_kdgkb_ioctl(int cmd, struct kbsentry
> int i, j, k;
> int ret;
>
> + if (!capable(CAP_SYS_TTY_CONFIG))
> + return -EPERM;
> +
> kbs = kmalloc(sizeof(*kbs), GFP_KERNEL);
> if (!kbs) {
> ret = -ENOMEM;
> _
--
Horms
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