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Date: Tue, 10 Feb 2015 12:57:49 -0600
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Seth Jennings <sjenning@redhat.com>, Jiri Kosina <jkosina@suse.cz>,
        Vojtech Pavlik <vojtech@suse.cz>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 7/9] proc: add /proc/<pid>/universe to show livepatch
 status
Message-ID: <20150210185749.GK21643@treble.redhat.com>
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On Tue, Feb 10, 2015 at 07:47:12PM +0100, Jiri Slaby wrote:
> On 02/09/2015, 06:31 PM, Josh Poimboeuf wrote:
> > Expose the per-task klp_universe value so users can determine which
> > tasks are holding up completion of a patching operation.
> > 
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > ---
> >  fs/proc/base.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/fs/proc/base.c b/fs/proc/base.c
> > index 3f3d7ae..b9fe6b5 100644
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -2528,6 +2528,14 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
> >  	return err;
> >  }
> >  
> > +#ifdef CONFIG_LIVEPATCH
> > +static int proc_pid_klp_universe(struct seq_file *m, struct pid_namespace *ns,
> > +				 struct pid *pid, struct task_struct *task)
> > +{
> > +	return seq_printf(m, "%d\n", task->klp_universe);
> > +}
> > +#endif /* CONFIG_LIVEPATCH */
> > +
> >  /*
> >   * Thread groups
> >   */
> > @@ -2628,6 +2636,9 @@ static const struct pid_entry tgid_base_stuff[] = {
> >  #ifdef CONFIG_CHECKPOINT_RESTORE
> >  	REG("timers",	  S_IRUGO, proc_timers_operations),
> >  #endif
> > +#ifdef CONFIG_LIVEPATCH
> > +	ONE("universe", S_IRUGO, proc_pid_klp_universe),
> 
> I am not sure if this can be UGO or if it should be USR only instead.
> Leaving for discussion, but I incline to use USR to avoid *any* info
> leakage.

That's fine.  I can't think of any reason why a non-root user would need
to know the task's universe.

-- 
Josh
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