Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751729AbaDYVS0 (ORCPT ); Fri, 25 Apr 2014 17:18:26 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:60272 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751659AbaDYVSY (ORCPT ); Fri, 25 Apr 2014 17:18:24 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andy Lutomirski Cc: "linux-kernel\@vger.kernel.org" , "Serge E. Hallyn" , Linux Containers References: <87ha5h42va.fsf@x220.int.ebiederm.org> <87tx9h2m2w.fsf@x220.int.ebiederm.org> Date: Fri, 25 Apr 2014 14:17:46 -0700 In-Reply-To: (Andy Lutomirski's message of "Fri, 25 Apr 2014 13:46:23 -0700") Message-ID: <87oazpyupx.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX195mVktTqqfKQm167J7SR7KRhZvRnEwJd4= X-SA-Exim-Connect-IP: 98.234.51.111 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -0.0 BAYES_20 BODY: Bayes spam probability is 5 to 20% * [score: 0.0742] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Andy Lutomirski X-Spam-Relay-Country: Subject: Re: pid ns feature request X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 13:58:17 -0700) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Lutomirski writes: > On Fri, Apr 25, 2014 at 1:25 PM, Eric W. Biederman > wrote: >> Andy Lutomirski writes: >> >>> On Fri, Apr 25, 2014 at 12:37 PM, Eric W. Biederman >>> wrote: >>>> Andy Lutomirski writes: >>>> >>>>> Unless I'm missing some trick, it's currently rather painful to mount >>>>> a namespace /proc. You have to actually be in the pid namespace to >>>>> mount the correct /proc instance, and you can't unmount the old /proc >>>>> until you've mounted the new /proc. This means that you have to fork >>>>> into the new pid namespace before you can finish setting it up. >>>> >>>> Yes. You have to be inside just about all namespaces before you can >>>> finish setting them up. >>>> >>>> I don't know the context in which needed to be inside the pid namespace >>>> is a burden. >>> >>> I'm trying to sandbox myself. I unshare everything, setup up new >>> mounts, pivot_root, umount the old stuff, fork, and wait around for >>> the child to finish. >>> >>> This doesn't work: the parent can't mount the new /proc, and the child >>> can't either because it's too late. >>> >>> The only solution I can think of without kernel changes is to fork the >>> child (pid 1) before pivot_root, which makes everything more >>> complicated. I suppose I can unshare, fork immediately, have the >>> child set up all the mounts, and then wake the parent, but this is an >>> annoying bit of extra complexity for no obvious gain. >> >> Or perhaps just use clone and clone flags. >> >> What are you doing with the parent process? What value does it serve? > > I'm not entirely sure. I'm hacking on this thing: > > https://github.com/amluto/sandstorm/tree/userns > > which isn't really my code. But there's an inner sandbox and an outer > sandbox, and only the inner sandbox is in a pid namespace. > > I suppose what what I'm doing is a bit strange. A bit. But doing strange things is good. Right now most of my energy is focused on closely the last of the design issues. So I don't have much energy for new namespace related features right now. Eric -- 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/