From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758682AbZBRWen (ORCPT ); Wed, 18 Feb 2009 17:34:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757796AbZBRWbx (ORCPT ); Wed, 18 Feb 2009 17:31:53 -0500 Received: from kroah.org ([198.145.64.141]:34677 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757780AbZBRWbw (ORCPT ); Wed, 18 Feb 2009 17:31:52 -0500 Date: Wed, 18 Feb 2009 14:28:57 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, "Eric W. Biederman" , Sukadev Bhattiprolu , Oleg Nesterov , Roland McGrath , Bastian Blank , Pavel Emelyanov , Nadia Derbey , Serge Hallyn Subject: [patch 01/36] pid: implement ns_of_pid Message-ID: <20090218222857.GB10668@kroah.com> References: <20090218222447.432108614@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="pid-implement-ns_of_pid.patch" In-Reply-To: <20090218222841.GA10668@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Eric W. Biederman commit f9fb860f67b9542cd78d1558dec7058092b57d8e upstream. A current problem with the pid namespace is that it is easy to do pid related work after exit_task_namespaces which drops the nsproxy pointer. However if we are doing pid namespace related work we are always operating on some struct pid which retains the pid_namespace pointer of the pid namespace it was allocated in. So provide ns_of_pid which allows us to find the pid namespace a pid was allocated in. Using this we have the needed infrastructure to do pid namespace related work at anytime we have a struct pid, removing the chance of accidentally having a NULL pointer dereference when accessing current->nsproxy. Signed-off-by: Eric W. Biederman Signed-off-by: Sukadev Bhattiprolu Cc: Oleg Nesterov Cc: Roland McGrath Cc: Bastian Blank Cc: Pavel Emelyanov Cc: Nadia Derbey Acked-by: Serge Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/pid.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -123,6 +123,24 @@ extern struct pid *alloc_pid(struct pid_ extern void free_pid(struct pid *pid); /* + * ns_of_pid() returns the pid namespace in which the specified pid was + * allocated. + * + * NOTE: + * ns_of_pid() is expected to be called for a process (task) that has + * an attached 'struct pid' (see attach_pid(), detach_pid()) i.e @pid + * is expected to be non-NULL. If @pid is NULL, caller should handle + * the resulting NULL pid-ns. + */ +static inline struct pid_namespace *ns_of_pid(struct pid *pid) +{ + struct pid_namespace *ns = NULL; + if (pid) + ns = pid->numbers[pid->level].ns; + return ns; +} + +/* * the helpers to get the pid's id seen from different namespaces * * pid_nr() : global id, i.e. the id seen from the init namespace;