Re: [PATCH 2/2] x86: Allow disabling of sys_iopl, sys_ioperm

Alan Cox
2011-07-14T23:08:56Z

On Thu, 14 Jul 2011 15:40:03 -0700
Mike Waychison <mikew@google.com> wrote:

> On Thu, Jul 14, 2011 at 3:35 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> > On 07/14/2011 03:31 PM, Andrew Morton wrote:
> >>
> >> sys_iopl() is missing asmlinkage.
> >>
> >> It would be far more conventional to use cond_syscall().  Perhaps by
> >> adding a CONFIG_X86 area into kernel/sys_ni.c
> >>
> >> fyi, I'm offering special deals on checkpatch.pl site licenses this month.
> >
> > Again, I don't think this makes sense as a compile-time-only option.
>
> echo "enabled" > /proc/sys/kernel/iopl_available
> echo "disabled" > /proc/sys/kernel/iopl_available
> echo "locked" > /proc/sys/kernel/iopl_available

In all these cases if I can obtain module loading permission or I use the
privileges required to operate these calls for something else then I can
replace them anyway, so "locked" is meaningless.