Re: [PATCH] SELinux: Add security hook definition for getioprio and insert hooks

[Stephen Smalley <sds@tycho.nsa.gov>]

On Fri, 2006-06-30 at 14:37 -0500, Serge E. Hallyn wrote:
> Quoting James Morris (jmorris@namei.org):
> ...
> > +static int get_task_ioprio(struct task_struct *p)
> > +{
> > +	int ret;
> > +
> > +	ret = security_task_getioprio(p);
> > +	if (ret)
> > +		goto out;
> > +	ret = p->ioprio;
> > +out:
> > +	return ret;
> > +}
> ...
> >  			do_each_task_pid(who, PIDTYPE_PGID, p) {
> > +				tmpio = get_task_ioprio(p);
> > +				if (tmpio < 0)
> > +					continue;
> >  				if (ret == -ESRCH)
> > -					ret = p->ioprio;
> > +					ret = tmpio;
> >  				else
> > -					ret = ioprio_best(ret, p->ioprio);
> > +					ret = ioprio_best(ret, tmpio);
> ...
> > + * @task_getioprio
> > + *	Check permission before getting the ioprio value of @p.
> > + *	@p contains the task_struct of process.
> > + *	Return 0 if permission is granted.
> 
> A return value >0 is a problem here but isn't mentioned.  the
> get_task_ioprio() helper will return the the security_task_getioprio()
> return value in htat case, but the do_each_task_pid loop will take it
> as a valid return value.

True, but that isn't limited to that hook - think what happens if
inode_permission returns an arbitrary positive integer. 

-- 
Stephen Smalley
National Security Agency

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