linux-kernel - Re: [PATCH 2/2] x86: Allow disabling of sys_iopl, sys

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Message-ID: <20110715000454.07c67429@lxorguk.ukuu.org.uk>
Date:	Fri, 15 Jul 2011 00:04:54 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Mike Waychison <mikew@...gle.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: Allow disabling of sys_iopl, sys_ioperm

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

> On Thu, Jul 14, 2011 at 3:35 PM, H. Peter Anvin <hpa@...or.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.
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