Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755073AbaJGV0f (ORCPT ); Tue, 7 Oct 2014 17:26:35 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:43060 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbaJGV0d (ORCPT ); Tue, 7 Oct 2014 17:26:33 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andy Lutomirski Cc: 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> Date: Tue, 07 Oct 2014 14:26:00 -0700 In-Reply-To: (Andy Lutomirski's message of "Tue, 7 Oct 2014 14:02:53 -0700") Message-ID: <87siizshav.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: U2FsdGVkX18y7jht3ZYUD6EuBq0BPwBLZj8FToq0u9g= 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: No description available. * -0.0 BAYES_40 BODY: Bayes spam probability is 20 to 40% * [score: 0.3124] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa04 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa04 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Andy Lutomirski X-Spam-Relay-Country: X-Spam-Timing: total 187 ms - load_scoreonly_sql: 0.06 (0.0%), signal_user_changed: 3.0 (1.6%), b_tie_ro: 2.1 (1.1%), parse: 0.76 (0.4%), extract_message_metadata: 11 (5.8%), get_uri_detail_list: 0.91 (0.5%), tests_pri_-1000: 5 (2.9%), tests_pri_-950: 1.13 (0.6%), tests_pri_-900: 0.91 (0.5%), tests_pri_-400: 16 (8.8%), check_bayes: 16 (8.3%), b_tokenize: 4.5 (2.4%), b_tok_get_all: 6 (3.1%), b_comp_prob: 1.56 (0.8%), b_tok_touch_all: 1.74 (0.9%), b_finish: 0.60 (0.3%), tests_pri_0: 140 (75.1%), tests_pri_500: 4.9 (2.6%), 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 in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Lutomirski writes: > Why should MNT_LOCKED on submounts be enforced? > > Is it because, if you retain a reference to the detached tree, then > you can see under the submounts? Yes. MNT_DETACH is a recursive operation that detaches all of the mount and all of it's submounts. Which means you can see under the submounts if you have a reference to a detached mount. > If so, let's fix *that*. Because > otherwise the whole model of pivot_root + detach will break. I am not certain what you are referring to. pivot_root doesn't manipulate the mount tree so you can see under anything. What I believe is the appropriate fix is to fail umount2(...,MNT_DETACH) if there are any referenced mount points being detached that have a locked submount. > Also, damn it, we need change_the_ns_root instead of pivot_root. I > doubt that any container programs actually want to keep the old root > attached after pivot_root. Shrug. Except for chroot_fs_refs() pivot_root is a cheap. I'm not particularly in favor of merging pivot_root and umount2. The number of weird cases in the current api are high. A merged piece of code would just make them higher. I am hoping that one more round of bug fixing will at least get the bugs for having unprivileged mounts fixed in the current API. 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/