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=-3.7 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 9F344C4741F for ; Thu, 1 Oct 2020 15:00:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6108720780 for ; Thu, 1 Oct 2020 15:00:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732531AbgJAPAZ (ORCPT ); Thu, 1 Oct 2020 11:00:25 -0400 Received: from mout.kundenserver.de ([212.227.126.130]:42215 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732346AbgJAPAY (ORCPT ); Thu, 1 Oct 2020 11:00:24 -0400 Received: from mail-qk1-f173.google.com ([209.85.222.173]) by mrelayeu.kundenserver.de (mreue010 [212.227.15.129]) with ESMTPSA (Nemesis) id 1MuDLZ-1kgCk73nLB-00uc2i; Thu, 01 Oct 2020 17:00:23 +0200 Received: by mail-qk1-f173.google.com with SMTP id 16so5612946qkf.4; Thu, 01 Oct 2020 08:00:22 -0700 (PDT) X-Gm-Message-State: AOAM5331+w8bgQrCxRMPqcOme7w6K1gGgLjLOSQJCy6De703+xLDX+Jw HsXC0qoJW46kUafEqNYyl9v98GBmt40Ftp4Kw5g= X-Google-Smtp-Source: ABdhPJxUXkolZ9fkyZnoOE6+N9rQNNdvkpgtMVVCFkZvmQm6oj8Q44LcJPYHCsuwUgBq+y/DreAZeDMmeSJj+dRqpUk= X-Received: by 2002:ae9:c30d:: with SMTP id n13mr8131383qkg.138.1601564421695; Thu, 01 Oct 2020 08:00:21 -0700 (PDT) MIME-Version: 1.0 References: <20200918120536.1464804-1-arnd@arndb.de> <20200918120536.1464804-2-arnd@arndb.de> <20200919054831.GN30063@infradead.org> <20200929175255.GA2330@infradead.org> In-Reply-To: <20200929175255.GA2330@infradead.org> From: Arnd Bergmann Date: Thu, 1 Oct 2020 17:00:03 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/2] dev_ioctl: split out SIOC?IFMAP ioctls To: Christoph Hellwig Cc: "David S. Miller" , Jakub Kicinski , Jiri Pirko , Taehee Yoo , Eric Dumazet , Alexei Starovoitov , Andrew Lunn , Jens Axboe , Networking , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:r2f5IAT6FyggvoqpFdYQrXng6bOKyGAs/6TZM/Yz9/Kov2LlZVZ VLuVp8Of+nXz9FBot3eCym5rr0XTx/NSM15qiPu9ydBg6119V6oI+z8PE0QetKjOUtsN1w/ 9HQcFqBURe32r+17TJjoIaW6ovVFCHQiPS4Ri0y3ihiElNol98ZhcJUtct5s07x56KjQVoi Qhmmbv7c52DRUbIlza4OA== X-UI-Out-Filterresults: notjunk:1;V03:K0:2M/x444AChQ=:p5N7YqCJrl7c+MTXtV3EOD JyHcgOgTeIYH98vgRR2K8J9e/OLT3cqKTzY5ZGttGNkTE5VeKw/GsrICRWRKsKylMqbz/fDBT JTSYW26+ljhn1q58pgviTbKiF3HSscg9pIZEAfXiJ/kqCJDN2F/dLREFP6JNnABh3rbpxxr// dRCO4eDX5k2VmKzp+GGmSNmtMimnTV3U8HfLUiBP3Og6KPUv8DXcQqk6POohVt3n8fGToA6vp Zccv89I3hfSOKppjkYfMN8lMMxkpJP1R7IFboEcezlN6j6zpTAvMgsEQJCl+7YNwTfCIRnKpM MPt5odRwLuURfo7wq0gsDiLZBMYujvBbl7wyK3J/i3fXaARKwCEO1Kbf02kdkCS8dBatdv90w XLWfBahZ1xEnIx9rVYvml2iYIMNPRFtw6vp8Dqx2stFNMnZ431fhjwvCvEZ6Ykjznq7VYASu2 iz8d4A2C4ha0MZkpLnpWFuSxtKRsqQMYotv/kqj/EeCvDHVQ2Sqlfkh4+JMOdxupXd/pOPS0f QozhnUPQUxWc+Z6CcwHEp2WB2XmHRQGpFvJ0Sqt96CJ+pX9NPfiG4cabwjPqiZZ1sqO/DbyRx s2JDXi1Ss3sdQ/13CLoPnZxTQbHlap9WIE42EI4NBV1xPL16ULGZSRhmLaNBoFQqsTW54ycsX 3rBB/yz56eSNgcqeZvQEehrSIBcbRB2u22dNwhLveCBvuCGKC50YTEyf87BOoj7ocrOtFpdes ITlbBLtEnY5Ng2PTnoZsnwk8Iy2i5uf/DJ8g5V6+/VyBbqdN3KA0tOvANNpNyLecl/LzK7HGO e39FSo130HzPzjsBReUKqusFORuNXUD3GrdLoSUOyjmfeFLzGKK8uumpYYR9YTc/Yxz2Inv Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Sep 29, 2020 at 7:53 PM Christoph Hellwig wrote: > On Fri, Sep 25, 2020 at 02:28:29PM +0200, Arnd Bergmann wrote: > > Do you mean we should check that the (larger) user space size > > remains what it is for future changes, or that the (smaller) > > kernel size remains the same on all kernels, or maybe both? > > I had something like: > > BUILD_BUG_ON(sizeof(struct ifmap) > > sizeof(struct ifreq) - IFNAMSIZ); > > plus a suitable comment in mind. But that condition is true on all 64-bit architectures, which is the fundamental issue I'm working around. I can try to capture that better in the comment though. My expectation here is that passing the smaller 'ifreq' structure to ndo_do_ioctl() is safe as long as all drivers use only the remaining members of ifr_ifru that all fit into the first 16 bytes. Do you see a problem with that assumption? Arnd