From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gao feng Subject: Re: [PATCH 08/11] pidns: Deny strange cases when creating pid namespaces. Date: Wed, 21 Nov 2012 10:25:43 +0800 Message-ID: <50AC3BA7.3090100@cn.fujitsu.com> References: <8739097bkk.fsf@xmission.com> <1353083750-3621-1-git-send-email-ebiederm@xmission.com> <1353083750-3621-8-git-send-email-ebiederm@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1353083750-3621-8-git-send-email-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Eric W. Biederman" Cc: Linux Containers , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton , Oleg Nesterov List-Id: containers.vger.kernel.org on 2012/11/17 00:35, Eric W. Biederman wrote: > From: "Eric W. Biederman" > > task_active_pid_ns(current) != current->ns_proxy->pid_ns will > soon be allowed to support unshare and setns. > > The definition of creating a child pid namespace when > task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that > we create a child pid namespace of current->ns_proxy->pid_ns. However > that leads to strange cases like trying to have a single process be > init in multiple pid namespaces, which is racy and hard to think > about. > > The definition of creating a child pid namespace when > task_active_pid_ns(current) != current->ns_proxy->pid_ns could be that > we create a child pid namespace of task_active_pid_ns(current). While > that seems less racy it does not provide any utility. > > Therefore define the semantics of creating a child pid namespace when > task_active_pid_ns(current) != current->ns_proxy->pid_ns to be that the > pid namespace creation fails. That is easy to implement and easy > to think about. > > Signed-off-by: "Eric W. Biederman" > --- Acked-by: Gao feng