Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756243AbYGAJsT (ORCPT ); Tue, 1 Jul 2008 05:48:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751444AbYGAJsB (ORCPT ); Tue, 1 Jul 2008 05:48:01 -0400 Received: from e28smtp02.in.ibm.com ([59.145.155.2]:44700 "EHLO e28esmtp02.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753972AbYGAJsA (ORCPT ); Tue, 1 Jul 2008 05:48:00 -0400 Date: Tue, 1 Jul 2008 15:17:34 +0530 From: Dhaval Giani To: Paul Menage Cc: Andrew Morton , Balbir Singh , Sudhir Kumar , lkml , containers@lists.osdl.org Subject: Re: Attaching PID 0 to a cgroup Message-ID: <20080701094734.GE3925@linux.vnet.ibm.com> Reply-To: Dhaval Giani References: <20080701094545.GD3925@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080701094545.GD3925@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2122 Lines: 67 [put in the wrong alias for containers list correcting it.] On Tue, Jul 01, 2008 at 03:15:45PM +0530, Dhaval Giani wrote: > Hi Paul, > > Attaching PID 0 to a cgroup caused the current task to be attached to > the cgroup. Looking at the code, > > if (pid) { > rcu_read_lock(); > tsk = find_task_by_vpid(pid); > if (!tsk || tsk->flags & PF_EXITING) { > rcu_read_unlock(); > return -ESRCH; > } > get_task_struct(tsk); > rcu_read_unlock(); > > if ((current->euid) && (current->euid != tsk->uid) > && (current->euid != tsk->suid)) { > put_task_struct(tsk); > return -EACCES; > } > } else { > tsk = current; > get_task_struct(tsk); > } > > I was wondering, why this was done. It seems to be unexpected behavior. > Wouldn't something like the following be a better response? (I've used > EINVAL, but I can change it to ESRCH if that is better.) > > --- > cgroups: Don't allow PID 0 to be attached to a group > > Currently when one trys to attach PID 0 to a cgroup, it attaches > the current task. That is not expected behavior. It should return > an error instead. > > Signed-off-by: Dhaval Giani > > Index: linux-2.6/kernel/cgroup.c > =================================================================== > --- linux-2.6.orig/kernel/cgroup.c > +++ linux-2.6/kernel/cgroup.c > @@ -1309,8 +1309,7 @@ static int attach_task_by_pid(struct cgr > return -EACCES; > } > } else { > - tsk = current; > - get_task_struct(tsk); > + return -EINVAL; > } > > ret = cgroup_attach_task(cgrp, tsk); > -- > regards, > Dhaval -- regards, Dhaval -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/