From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752784AbdAZE2P (ORCPT ); Wed, 25 Jan 2017 23:28:15 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:49008 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbdAZE2N (ORCPT ); Wed, 25 Jan 2017 23:28:13 -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> <877f5jlvs1.fsf@xmission.com> <87tw8nkh4k.fsf@xmission.com> Date: Thu, 26 Jan 2017 17:23:46 +1300 In-Reply-To: (Michael Kerrisk's message of "Wed, 25 Jan 2017 16:50:22 +1300") Message-ID: <87a8aea1pp.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=1cWbfF-0008CF-He;;;mid=<87a8aea1pp.fsf@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=101.100.131.98;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+d7HNKgFwUCm6EolfZibOEXt4oxBX49lg= 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 * 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: 0.4466] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_TooManySym_02 5+ unique symbols in subject X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;"Michael Kerrisk \(man-pages\)" X-Spam-Relay-Country: X-Spam-Timing: total 5538 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 2.9 (0.1%), b_tie_ro: 2.1 (0.0%), parse: 0.73 (0.0%), extract_message_metadata: 10 (0.2%), get_uri_detail_list: 0.96 (0.0%), tests_pri_-1000: 6 (0.1%), tests_pri_-950: 1.12 (0.0%), tests_pri_-900: 0.98 (0.0%), tests_pri_-400: 20 (0.4%), check_bayes: 19 (0.3%), b_tokenize: 5 (0.1%), b_tok_get_all: 7 (0.1%), b_comp_prob: 1.80 (0.0%), b_tok_touch_all: 2.4 (0.0%), b_finish: 0.64 (0.0%), tests_pri_0: 293 (5.3%), check_dkim_signature: 0.48 (0.0%), check_dkim_adsp: 2.7 (0.0%), tests_pri_500: 5201 (93.9%), poll_dns_idle: 5195 (93.8%), 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: > On 25 January 2017 at 15:28, Eric W. Biederman wrote: >> My concern is that the difference between returning -EOVERFLOW and >> overflow_uid is primarily about usability. If you haven't played with >> the usability I don't trust that we have made the proper trade off. > > So, I had not initially included the no-UID-mapping case, and when you > proposed -EOVERFLOW for that case, it seemed better. > > On reflection, mapping to the overflow_uid seems simpler. Taking the > example shown in my other mail a short time ago, the unmapped UID 0 > from the outer namespace would map to the overflow_uid (which UID my > program would print), but my program would still correctly report that > the UID 0 process in the outer namespace might (subject to LSM checks) > have capabilities in the inner namespace. > > So, it seems that reverting the EOVERFLOW change is in order (and my > example program thus needs no changes). Does that sound reasonable to > you? It does. I just care that you have thought through the tradeoffs of that corner of the interface design. Eric