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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 7EADCC43463 for ; Sun, 20 Sep 2020 13:58:59 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F03B21531 for ; Sun, 20 Sep 2020 13:58:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F03B21531 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arndb.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BvTgz5VwSzDql5 for ; 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Sun, 20 Sep 2020 06:56:03 -0700 (PDT) MIME-Version: 1.0 References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200918134012.GY3421308@ZenIV.linux.org.uk> <20200918134406.GA17064@lst.de> <20200918135822.GZ3421308@ZenIV.linux.org.uk> <20200918151615.GA23432@lst.de> <20200919220920.GI3421308@ZenIV.linux.org.uk> In-Reply-To: <20200919220920.GI3421308@ZenIV.linux.org.uk> From: Arnd Bergmann Date: Sun, 20 Sep 2020 15:55:47 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag To: Al Viro Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:hIwIr1JJ6yOCSp8oOy/p434f8n0zpo6W7GSzBYIjHMmV+utLHRU GSWoOhl0c7+gIy926b80cYup9N3TuBf3K7vxRLkvSShR9417FdtgPMacytszznFVFx7muTl 6GMcpRmPY3AFz74ktblKT+bqaAlrOIaHOxPGbtBGFtHvZQ5h7uG5Vqw4hDyWRAFWQ2R90Mo CisApVasOxCjvhfejmwpQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:lZGCWuaVZWI=:vMPkfL03HsFwxo02CyFkmj 37lmyQKOKCeBlcu3R7JuszPEtUkFmVFyNkzByhfKe7dfi814Kkdrscv0m+qv9Hd24bebg5fsJ MpuboD0PXZAVFH54JfPBebRVvqnSvFd4dwJm3LH4i2sCBwzFla80EUFeYYaVvZxXqBlDOl/Wo ZNs00civUd4+4n2jYt7ks81nyp2nbzcmRSirhD6kiZGVpNVvW7qw7e9m2SuL9NPFKwWf7EkOn L16fS1F4NPiSuEe8XsYZM7jpxpMX/p14cuwCUeXjk8bdm9P64PtOR51LKCipqFyfPOTJVhNXP JmRS14iQCZQokI9YDT1etwT4v9bJwbEK4WOtQyexo4niOeQM8n4JxyPmnoP0f27L1povMksNy YaFgDj8xlN2zeSk7H9IF5YpnyitSl5aYAS0JKOa6u5AL51I7aLFNZfmvnu0sUKPQzr8BkLNtj PXqR6RMN/NlNnY7vObFQ5bswWAlFirbLLnnv/1WRIVWhkmhV04h2kdZvLm3KZWeasGmDTXTmz e9EDnmCmXY6vEapUIMg5pFQAkEoWJOuZf+JZqvP+vZmk0wgolCacFFf0dszoHEJleASl568PR N92V+QWKdKmhLdldyzjBFUfxcH3gzULgaBiWsozcJCdx9kWGbQEJKGHOHYhaIG0AY8lEpqEor x3iUzhezRZhkzZSmiEZjFHfni8JezhyiWAnotM7WL+K+Agjytnr62umFZQ4AE2b7Sy5MNhHF9 MOed39IXe4+z9n7h/Cr71DgWIYVMNcSwLc6ZXtmBlRj16ckH1aRx8ZoDRQ+h0KTvhs1X92+XU SNwegUbNyF+N6NNIO311Rdq30BK3M8uliSUrogcfo8N5Ylw3EI3Z/QFkNpHFWtX600G/wO5 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio , "open list:BROADCOM NVRAM DRIVER" , David Howells , Linux-MM , keyrings@vger.kernel.org, sparclinux , Christoph Hellwig , linux-arch , linux-s390 , linux-scsi , the arch/x86 maintainers , linux-block , io-uring@vger.kernel.org, Linux ARM , Jens Axboe , Parisc List , Networking , "linux-kernel@vger.kernel.org" , LSM List , Linux FS-devel Mailing List , Andrew Morton , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Sep 20, 2020 at 12:09 AM Al Viro wrote: > On Fri, Sep 18, 2020 at 05:16:15PM +0200, Christoph Hellwig wrote: > > On Fri, Sep 18, 2020 at 02:58:22PM +0100, Al Viro wrote: > > > Said that, why not provide a variant that would take an explicit > > > "is it compat" argument and use it there? And have the normal > > > one pass in_compat_syscall() to that... > > > > That would help to not introduce a regression with this series yes. > > But it wouldn't fix existing bugs when io_uring is used to access > > read or write methods that use in_compat_syscall(). One example that > > I recently ran into is drivers/scsi/sg.c. > > So screw such read/write methods - don't use them with io_uring. > That, BTW, is one of the reasons I'm sceptical about burying the > decisions deep into the callchain - we don't _want_ different > data layouts on read/write depending upon the 32bit vs. 64bit > caller, let alone the pointer-chasing garbage that is /dev/sg. Would it be too late to limit what kind of file descriptors we allow io_uring to read/write on? If io_uring can get changed to return -EINVAL on trying to read/write something other than S_IFREG file descriptors, that particular problem space gets a lot simpler, but this is of course only possible if nobody actually relies on it yet. Arnd