From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751033Ab1JHEY0 (ORCPT ); Sat, 8 Oct 2011 00:24:26 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:60166 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773Ab1JHEYZ (ORCPT ); Sat, 8 Oct 2011 00:24:25 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Lennart Poettering Cc: Matt Helsley , Kay Sievers , linux-kernel@vger.kernel.org, harald@redhat.com, david@fubar.dk, greg@kroah.com References: <1317943022.1095.25.camel@mop> <20111007074904.GC16723@count0.beaverton.ibm.com> <20111007160113.GB14201@tango.0pointer.de> Date: Fri, 07 Oct 2011 21:24:37 -0700 In-Reply-To: <20111007160113.GB14201@tango.0pointer.de> (Lennart Poettering's message of "Fri, 7 Oct 2011 18:01:14 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in02.mta.xmission.com;;;ip=98.207.153.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/yScGR7fLhe5FlhBve/eL+MhqS3NBpd10= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa05 1397; Body=1 Fuz1=1 Fuz2=1] * 0.8 RDNS_NONE Delivered to internal network by a host with no rDNS * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa05 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Lennart Poettering X-Spam-Relay-Country: ** Subject: Re: A =?utf-8?Q?Plumber=E2=80=99s?= Wish List for Linux X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Lennart Poettering writes: > On Fri, 07.10.11 00:49, Matt Helsley (matthltc@us.ibm.com) wrote: > >> >> On Fri, Oct 07, 2011 at 01:17:02AM +0200, Kay Sievers wrote: >> >> >> >> > * simple, reliable and future-proof way to detect whether a specific pid >> > is running in a CLONE_NEWPID container, i.e. not in the root PID >> > namespace. Currently, there are available a few ugly hacks to detect >> >> Is that precisely what's needed or would it be sufficient to know >> that the pid is running in a child pid namespace of the current pid >> namespace? If so, I think this could eventually be done by comparing >> the inode numbers assigned to /proc//ns/pid to those of >> /proc/1/ns/pid. > > I think the most interesting test would be to figure out for a process > if itself is running in a PID namespace. And for that comparing inodes > wouldn't work since the namespace process would never get access to the > inode of the outside init. Strictly correct answer. All processes are running in a pid namespace. I think we can implement that in a libc header. static inline bool in_pid_namespace(void) { return true; } Why does it matter if you are running in something other than the initial pid namespace? I expect what you are really after is something else entirely, and you are asking the wrong question. Eric