From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 778A8C33CB1 for ; Wed, 15 Jan 2020 14:08:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3DCA52084D for ; Wed, 15 Jan 2020 14:08:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729047AbgAOOHT (ORCPT ); Wed, 15 Jan 2020 09:07:19 -0500 Received: from mout.kundenserver.de ([212.227.17.13]:38441 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726132AbgAOOHT (ORCPT ); Wed, 15 Jan 2020 09:07:19 -0500 Received: from [192.168.100.1] ([78.238.229.36]) by mrelayeu.kundenserver.de (mreue107 [213.165.67.119]) with ESMTPSA (Nemesis) id 1MBV2f-1iwQh13Mat-00D2xA; Wed, 15 Jan 2020 15:07:09 +0100 To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, James Bottomley , YunQiang Su References: <20191122150830.15855-1-laurent@vivier.eu> <2a464b33-0b1d-ff35-5aab-77019a072593@vivier.eu> <20200115135527.GG8904@ZenIV.linux.org.uk> From: Laurent Vivier Autocrypt: addr=laurent@vivier.eu; prefer-encrypt=mutual; keydata= mQINBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABtCJMYXVyZW50IFZp dmllciA8bGF1cmVudEB2aXZpZXIuZXU+iQI4BBMBAgAiBQJWBTDeAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRDzDDi9Py++PCEdD/oD8LD5UWxhQrMQCsUgLlXCSM7sxGLkwmmF ozqSSljEGRhffxZvO35wMFcdX9Z0QOabVoFTKrT04YmvbjsErh/dP5zeM/4EhUByeOS7s6Yl HubMXVQTkak9Wa9Eq6irYC6L41QNzz/oTwNEqL1weV1+XC3TNnht9B76lIaELyrJvRfgsp9M rE+PzGPo5h7QHWdL/Cmu8yOtPLa8Y6l/ywEJ040IoiAUfzRoaJs2csMXf0eU6gVBhCJ4bs91 jtWTXhkzdl4tdV+NOwj3j0ukPy+RjqeL2Ej+bomnPTOW8nAZ32dapmu7Fj7VApuQO/BSIHyO NkowMMjB46yohEepJaJZkcgseaus0x960c4ua/SUm/Nm6vioRsxyUmWd2nG0m089pp8LPopq WfAk1l4GciiMepp1Cxn7cnn1kmG6fhzedXZ/8FzsKjvx/aVeZwoEmucA42uGJ3Vk9TiVdZes lqMITkHqDIpHjC79xzlWkXOsDbA2UY/P18AtgJEZQPXbcrRBtdSifCuXdDfHvI+3exIdTpvj BfbgZAar8x+lcsQBugvktlQWPfAXZu4Shobi3/mDYMEDOE92dnNRD2ChNXg2IuvAL4OW40wh gXlkHC1ZgToNGoYVvGcZFug1NI+vCeCFchX+L3bXyLMg3rAfWMFPAZLzn42plIDMsBs+x2yP +bkCDQRWBSYZARAAvFJBFuX9A6eayxUPFaEczlMbGXugs0mazbOYGlyaWsiyfyc3PStHLFPj rSTaeJpPCjBJErwpZUN4BbpkBpaJiMuVO6egrC8Xy8/cnJakHPR2JPEvmj7Gm/L9DphTcE15 92rxXLesWzGBbuYxKsj8LEnrrvLyi3kNW6B5LY3Id+ZmU8YTQ2zLuGV5tLiWKKxc6s3eMXNq wrJTCzdVd6ThXrmUfAHbcFXOycUyf9vD+s+WKpcZzCXwKgm7x1LKsJx3UhuzT8ier1L363RW ZaJBZ9CTPiu8R5NCSn9V+BnrP3wlFbtLqXp6imGhazT9nJF86b5BVKpF8Vl3F0/Y+UZ4gUwL d9cmDKBcmQU/JaRUSWvvolNu1IewZZu3rFSVgcpdaj7F/1aC0t5vLdx9KQRyEAKvEOtCmP4m 38kU/6r33t3JuTJnkigda4+Sfu5kYGsogeYG6dNyjX5wpK5GJIJikEhdkwcLM+BUOOTi+I9u tX03BGSZo7FW/J7S9y0l5a8nooDs2gBRGmUgYKqQJHCDQyYut+hmcr+BGpUn9/pp2FTWijrP inb/Pc96YDQLQA1q2AeAFv3Rx3XoBTGl0RCY4KZ02c0kX/dm3eKfMX40XMegzlXCrqtzUk+N 8LeipEsnOoAQcEONAWWo1HcgUIgCjhJhBEF0AcELOQzitbJGG5UAEQEAAYkCHwQYAQIACQUC VgUmGQIbDAAKCRDzDDi9Py++PCD3D/9VCtydWDdOyMTJvEMRQGbx0GacqpydMEWbE3kUW0ha US5jz5gyJZHKR3wuf1En/3z+CEAEfP1M3xNGjZvpaKZXrgWaVWfXtGLoWAVTfE231NMQKGoB w2Dzx5ivIqxikXB6AanBSVpRpoaHWb06tPNxDL6SVV9lZpUn03DSR6gZEZvyPheNWkvz7bE6 FcqszV/PNvwm0C5Ju7NlJA8PBAQjkIorGnvN/vonbVh5GsRbhYPOc/JVwNNr63P76rZL8Gk/ hb3xtcIEi5CCzab45+URG/lzc6OV2nTj9Lg0SNcRhFZ2ILE3txrmI+aXmAu26+EkxLLfqCVT ohb2SffQha5KgGlOSBXustQSGH0yzzZVZb+HZPEvx6d/HjQ+t9sO1bCpEgPdZjyMuuMp9N1H ctbwGdQM2Qb5zgXO+8ZSzwC+6rHHIdtcB8PH2j+Nd88dVGYlWFKZ36ELeZxD7iJflsE8E8yg OpKgu3nD0ahBDqANU/ZmNNarBJEwvM2vfusmNnWm3QMIwxNuJghRyuFfx694Im1js0ZY3LEU JGSHFG4ZynA+ZFUPA6Xf0wHeJOxGKCGIyeKORsteIqgnkINW9fnKJw2pgk8qHkwVc3Vu+wGS ZiJK0xFusPQehjWTHn9WjMG1zvQ5TQQHxau/2FkP45+nRPco6vVFQe8JmgtRF8WFJA== Subject: Re: [RFC v2] binfmt_misc: pass binfmt_misc flags to the interpreter Message-ID: <20e6c345-b984-7b28-4d3f-c8f3799b8579@vivier.eu> Date: Wed, 15 Jan 2020 15:07:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200115135527.GG8904@ZenIV.linux.org.uk> Content-Type: text/plain; charset=utf-8 Content-Language: fr Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:nTwzQVh2u4oVadeeiv+dIe1lMrHXNviOKXiJwUq0IR1CGR5YW7i lWt3QbVabpPspqHHsb01rMgUnL+DDd8q3xcSKTZHRg+wfeN33hHFfvMIxIrzAtmM6EqKJXI OC/R/nt1EwBexq3Vfn7Vh+VrpZxF94jqcKF+W+Cs71Gmvs1EGlLeITLVHVbaVEPSdL0Ucjs ttL5GiwLcorc9ZFgp5S/w== X-UI-Out-Filterresults: notjunk:1;V03:K0:N1gVj2CRluU=:+oUeag9k4GsJtut/wbXOtF NEXjja5oN1/HXNc6axFNrVfUwocqMGOJnp33bSptcUq+z1HbwSxtTnUKu0NrdtQ5qM87Lb1cK CbY6J8Xj1LDA2ykkEUC6IQCydoZ/ythKi0O/+h7C2JNEbPYVKER3z3OQaVDnIcR3LmTKFaLvU BUvv6k+jlsUHh+iSvpx0r3h2fnn3IRhWyp+z8IN1+4WmSgjX+0ma+IGACjrNbCwh/RO416z1D JDnKZRLCa3qxgjAp51HhTMNqx+Lkx6O2o+q3dHkHlAtLX+B5DZBXD83pQZNFxSkJTLvG8W0FF f2vedyA0VkrVZkBmJkWajasp/d+T76CDkKM9vS0xKlD7WgNGUjADS+OjnOvhTXNk0IF3l2FCb wRqCUY99LfX3flle3T318iAONTBbLD1PVUx1W5Ac2yxty4ICr2z66DhOf2cW3OPHvxLcxOUPF crlj9YWcf7AgU8Z+8S9eVPn5bSeMNpQ0ylZzjdAAAx6RABI/k2YKp7FeyZP4mFx6rNLjV564u nZcf34KWahCDcQqjRHFGtAvVkGX81k4Fiq5OzgQxyqB3Vey4RgTlo5VxzRx6qGqt+UPFrHKDc tf66QzjuL/INKVMvG2VMwUQx3VW87014ky1aM2Op7EMtddpU5WZ2jp++sis3AB2Ey1ASqCWeq 54cdZOxza40DaHG2wLGM9e9xP+DB4/c/GLKRgqy6sv1uUrh5jzJ7g2r/gWUE5LKOinl1qe7j0 YHU3+Pwc4i9H5rlCZQUBkxIXtFRXgKFqOBJ3TxfvrwrPgYllmzmOcWRiEIrsRX/4pN8nTli/E 04IRpm6u0bkcHf9L3hS6nhWuBja/Ydy75PxVG4lE3xXvrggbjZ6jxJlc3xRvp0VDvj6q9eALp gLUttve8FxwjWPR0E0ykZF44ocjWdzMsotlSPMsMc= Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Le 15/01/2020 à 14:55, Al Viro a écrit : > On Wed, Jan 15, 2020 at 01:19:16PM +0100, Laurent Vivier wrote: >> Le 07/01/2020 à 15:50, Laurent Vivier a écrit : >>> Hi, >>> >>> this change is simple, easy to read and understand but it is really >>> needed by user space application interpreter to know the status of the >>> system configuration. >>> >>> Could we have a comment saying if there is a problem or if it is good to >>> be merged? >> >> Anyone? > > FWIW, one thing that looks worrying here is that these bits become > userland ABI after this patch - specific values passed in that thing > can't be changed. And no a single mention of that in fs/binfmt_misc.c, > leaving a nasty trap. As far as one can tell, their values are fair game > for reordering, etc. - not even visible outside of fs/binfmt_misc.c; > purely internal constants. And the effect of such modifications after > your patch will not be "everything breaks, patch gets caught by somebody's > tests" - it will be a quiet breakage for some users. > >>>> #define MISC_FMT_OPEN_BINARY (1 << 30) >>>> #define MISC_FMT_CREDENTIALS (1 << 29) >>>> #define MISC_FMT_OPEN_FILE (1 << 28) >>>> +#define MISC_FMT_FLAGS_MASK (MISC_FMT_PRESERVE_ARGV0 | MISC_FMT_OPEN_BINARY | \ >>>> + MISC_FMT_CREDENTIALS | MISC_FMT_OPEN_FILE) > > IOW, you are making those parts of userland ABI cast in stone forever. > Whether this bit assignment does make sense or not, such things really > should not be hidden. > Thank you for your answer. So I think the patch from YunQiang Su is a better approach than mine, much cleaner, see: binfmt_misc: pass info about P flag by AT_FLAGS https://patchwork.kernel.org/patch/10902935/ It does the same thing as my patch but uses a dedicated value for AT_FLAGS. Perhaps YunQiang can send a new version (without the kdebug() part)? Thanks, Laurent