linux-kernel - Re: [patch 28/28] posix clocks: Introduce dynamic clocks

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Date:	Thu, 3 Mar 2011 17:01:14 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	Richard Cochran <richard.cochran@...cron.at>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [patch 28/28] posix clocks: Introduce dynamic clocks

On Thu, Mar 03, 2011 at 03:50:08PM +0100, torbenh wrote:
> On Tue, Feb 01, 2011 at 01:52:35PM -0000, Thomas Gleixner wrote:
> > +static int pc_clock_adjtime(clockid_t id, struct timex *tx)
> > +{
> > +	struct posix_clock_desc cd;
> > +	int err;
> > +
> > +	err = get_clock_desc(id, &cd);
> > +	if (err)
> > +		return err;
> 
> there is no permission check here.
> if i get the clock fd in READ mode, i can still adjtime.
> same for settime.

You are right, but I think the check should be for the capability
instead. Checking the file mode for RDWR seems a bit pedantic to me.

For the normal system timer, clock_settime calls security_settime, but
adjtimex calls capable(CAP_SYS_TIME) directly. Perhaps adjtimex should
also use the security call, too.

Thanks,

Richard

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