From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751257AbdAYCbC (ORCPT ); Tue, 24 Jan 2017 21:31:02 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:44437 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751154AbdAYCbA (ORCPT ); Tue, 24 Jan 2017 21:31:00 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: "Michael Kerrisk \(man-pages\)" Cc: "Serge E. Hallyn" , Linux API , lkml , "linux-fsdevel\@vger.kernel.org" , Andrey Vagin , James Bottomley , "W. Trevor King" , Alexander Viro References: <93e5c7f9-9dc1-6c93-ad20-0ba053d8bfef@gmail.com> <963f76f9-3ae5-b316-e688-00d3e59cad30@gmail.com> <87d1fblx2s.fsf@xmission.com> Date: Wed, 25 Jan 2017 15:26:38 +1300 In-Reply-To: (Michael Kerrisk's message of "Wed, 25 Jan 2017 15:24:35 +1300") Message-ID: <877f5jlvs1.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1cWDMK-0005SH-BI;;;mid=<877f5jlvs1.fsf@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=101.100.131.98;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+9K/GCZl6vWJU25jhX6VDmODKE6yxAs5s= X-SA-Exim-Connect-IP: 101.100.131.98 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 * 1.0 XM_Body_Obfu01 BODY: Obfuscations * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4101] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_02 5+ unique symbols in subject * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *;"Michael Kerrisk \(man-pages\)" X-Spam-Relay-Country: X-Spam-Timing: total 5540 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 2.5 (0.0%), b_tie_ro: 1.73 (0.0%), parse: 0.72 (0.0%), extract_message_metadata: 11 (0.2%), get_uri_detail_list: 1.18 (0.0%), tests_pri_-1000: 6 (0.1%), tests_pri_-950: 1.17 (0.0%), tests_pri_-900: 0.96 (0.0%), tests_pri_-400: 19 (0.3%), check_bayes: 18 (0.3%), b_tokenize: 6 (0.1%), b_tok_get_all: 6 (0.1%), b_comp_prob: 1.80 (0.0%), b_tok_touch_all: 2.1 (0.0%), b_finish: 0.65 (0.0%), tests_pri_0: 1150 (20.8%), check_dkim_signature: 0.45 (0.0%), check_dkim_adsp: 2.8 (0.0%), tests_pri_500: 4346 (78.5%), poll_dns_idle: 4339 (78.3%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH v4 0/2] Add further ioctl() operations for namespace discovery X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -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 "Michael Kerrisk (man-pages)" writes: > Hi Eric, > > On 25 January 2017 at 14:58, Eric W. Biederman wrote: >> "Michael Kerrisk (man-pages)" writes: >> >>> I would like to write code that discovers the namespace setup on a live >>> system. The NS_GET_PARENT and NS_GET_USERNS ioctl() operations added in >>> Linux 4.9 provide much of what I want, but there are still a couple of >>> small pieces missing. Those pieces are added with this patch series. >> >> So it looks like the -EOVERFLOW change broke your example program. >> Causing it to abort if -EOVERFLOW is hit. Do we really want to return >> -EOVERFLOW? Or do you want to fix your program? > > Bother! Yes, I should have kept the example program in sync. (I > overlooked that it was not any more in sync.) > > So, I want to make sure I understand correctly, before I aswer your > question. Suppose we have > > 1. Outer namespace owned by UID 0 > 2. Inner namespace owned by UID 1000 > 3. A UID mapping in the inner namespace that maps '0 1000 1' > 4. A processs, X, in the outer namespace with UID 0 (and all caps). > > That's the case you're meaning, right? I think so I just noticed you did not handle -EOVERFLOW in the one NS_GET_OWNER_UID call. > So, UID 0 doesn't have a > mapping into the inner namespace, but does have all capabilities in > that inner namespace, right? That is correct. Eric