On 14/05/02, Serge E. Hallyn wrote:
> Quoting Richard Guy Briggs (rgb@xxxxxxxxxx):
>
> Most of this looks reasonable, but I'm curious about something,
>
> > +/**
> > + * ns_serial - compute a serial number for the namespace
> > + *
> > + * Compute a serial number for the namespace to uniquely identify it in
> > + * audit records.
> > + */
> > +unsigned int ns_serial(void)
> > +{
> > + static DEFINE_SPINLOCK(serial_lock);
> > + static unsigned int serial = 4; /* reserved for IPC, UTS, user, PID */
> > +
> > + unsigned long flags;
> > + unsigned int ret;
> > +
> > + spin_lock_irqsave(&serial_lock, flags);
> > + do {
> > + ret = ++serial;
> > + } while (unlikely(!ret));
>
> Why exactly are you doing this? Surely if serial is going to
> wrap around we've got a bigger problem than just wanting go
> bump one more time?
Thanks for catching this.
The code was templated off audit_serial() which tries to solve a
different problem and rolling it is much more likely. I hadn't noticed
that rollover protection. However, I *had* thought of making it a long
(which would be the same size on 32-bit arches, but larger on 64-bit)
since a 64-bit system is more likely to roll it out of sheer speed and
resource availability. But perhaps a long long would be safer.
> > + spin_unlock_irqrestore(&serial_lock, flags);
> > +
> > + return ret;
> > +}
- RGB
--
Richard Guy Briggs <rbriggs@xxxxxxxxxx>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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