Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932331AbaJGXmp (ORCPT ); Tue, 7 Oct 2014 19:42:45 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:34545 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932287AbaJGXmm (ORCPT ); Tue, 7 Oct 2014 19:42:42 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andy Lutomirski Cc: Serge Hallyn , Al Viro , Andrey Vagin , Linux FS Devel , "linux-kernel\@vger.kernel.org" , Linux API , Andrey Vagin , Andrew Morton , Cyrill Gorcunov , Pavel Emelyanov , Serge Hallyn , Rob Landley References: <1412683977-29543-1-git-send-email-avagin@openvz.org> <20141007133039.GG7996@ZenIV.linux.org.uk> <20141007133339.GH7996@ZenIV.linux.org.uk> <87r3yjy64e.fsf@x220.int.ebiederm.org> <20141007204627.GI28519@ubuntumail> <87wq8bvbzg.fsf@x220.int.ebiederm.org> <20141007213257.GJ28519@ubuntumail> <87zjd7r1z9.fsf@x220.int.ebiederm.org> <87h9zfpkm3.fsf@x220.int.ebiederm.org> Date: Tue, 07 Oct 2014 16:42:10 -0700 In-Reply-To: (Andy Lutomirski's message of "Tue, 7 Oct 2014 15:44:26 -0700") Message-ID: <87siizla5p.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: U2FsdGVkX19JhcV9WlQt1tOtn6wjDR3OeiiqFOhHhfI= 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 * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -0.0 BAYES_40 BODY: Bayes spam probability is 20 to 40% * [score: 0.3413] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa03 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa03 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Andy Lutomirski X-Spam-Relay-Country: X-Spam-Timing: total 477 ms - load_scoreonly_sql: 0.06 (0.0%), signal_user_changed: 5 (1.0%), parse: 1.38 (0.3%), extract_message_metadata: 12 (2.4%), get_uri_detail_list: 3 (0.5%), tests_pri_-1000: 10 (2.1%), tests_pri_-950: 2 (0.4%), tests_pri_-900: 1.55 (0.3%), tests_pri_-400: 36 (7.5%), check_bayes: 34 (7.2%), tests_pri_0: 399 (83.7%), tests_pri_500: 6 (1.3%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH] [RFC] mnt: add ability to clone mntns starting with the current root X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) 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 Tue, Oct 7, 2014 at 3:42 PM, Eric W. Biederman wrote: >> Andy Lutomirski writes: >> >>> On Tue, Oct 7, 2014 at 2:42 PM, Eric W. Biederman wrote: >>>> >>>> I am squinting and looking this way and that but while I can imagine >>>> someone more clever than I can think up some unique property of rootfs >>>> that makes it a little more exploitable than just mounting a ramfs, >>>> but since you have to be root to exploit those properties I think the >>>> game is pretty much lost. >>> >>> Yes. rootfs might not be empty, it might have totally insane >>> permissions, and it's globally shared, which makes it into a wonderful >>> channel to pass things around that shouldn't be passed around. >> >> But if only root with proc mounted can reach it... I don't know. > > It doesn't have to be global root. It could be userns root. > >> There might be a case for setting MNT_LOCKED when we overmount "/" >> as root but I don't yet see it. >> >>> Can non-root do this? You'd need to be in a userns with a "/" that >>> isn't MNT_LOCKED. Can this happen on any normal setup? >>> >>> FWIW, I think we should unconditionally MNT_LOCKED the root on userns >>> unshare, even if it's the only mount. >> >> To the best of my knowledge MNT_LOCKED is set uncondintially on userns >> unshare. > > Only if list_empty(&old->mnt_expire), whatever that means, I think. An autofs or nfs automounted mount. Can those ever become root? 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/