From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Brauner Date: Thu, 05 Sep 2019 11:29:59 +0000 Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-Id: <20190905112958.ldzyzyuqn5akkhzy@wittgenstein> List-Id: References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Rasmus Villemoes Cc: Aleksa Sarai , Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote: > On 05/09/2019 13.05, Christian Brauner wrote: > > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > >> + if (unlikely(!access_ok(dst, usize))) > >> + return -EFAULT; > >> + > >> + /* Deal with trailing bytes. */ > >> + if (usize < ksize) { > >> + if (memchr_inv(src + size, 0, rest)) > >> + return -EFBIG; > >> + } else if (usize > ksize) { > >> + if (__memzero_user(dst + size, rest)) > >> + return -EFAULT; > > > > Is zeroing that memory really our job? Seems to me we should just check > > it is zeroed. > > Of course it is, otherwise you'd require userspace to clear the output > buffer it gives us, which in the majority of cases is wasted work. It's > much easier to reason about if we just say "the kernel populates [uaddr, > uaddr + usize)". I don't really mind either way so sure. :) 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=-2.2 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 0E381C41514 for ; Thu, 5 Sep 2019 11:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E27AE22CF6 for ; Thu, 5 Sep 2019 11:30:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388474AbfIELae (ORCPT ); Thu, 5 Sep 2019 07:30:34 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:60466 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725921AbfIELad (ORCPT ); Thu, 5 Sep 2019 07:30:33 -0400 Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i5pxg-0002oG-P2; Thu, 05 Sep 2019 11:30:00 +0000 Date: Thu, 5 Sep 2019 13:29:59 +0200 From: Christian Brauner To: Rasmus Villemoes Cc: Aleksa Sarai , Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905112958.ldzyzyuqn5akkhzy@wittgenstein> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote: > On 05/09/2019 13.05, Christian Brauner wrote: > > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > >> + if (unlikely(!access_ok(dst, usize))) > >> + return -EFAULT; > >> + > >> + /* Deal with trailing bytes. */ > >> + if (usize < ksize) { > >> + if (memchr_inv(src + size, 0, rest)) > >> + return -EFBIG; > >> + } else if (usize > ksize) { > >> + if (__memzero_user(dst + size, rest)) > >> + return -EFAULT; > > > > Is zeroing that memory really our job? Seems to me we should just check > > it is zeroed. > > Of course it is, otherwise you'd require userspace to clear the output > buffer it gives us, which in the majority of cases is wasted work. It's > much easier to reason about if we just say "the kernel populates [uaddr, > uaddr + usize)". I don't really mind either way so sure. :) From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Brauner Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Date: Thu, 5 Sep 2019 13:29:59 +0200 Message-ID: <20190905112958.ldzyzyuqn5akkhzy@wittgenstein> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Rasmus Villemoes Cc: Aleksa Sarai , Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov List-Id: linux-api@vger.kernel.org On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote: > On 05/09/2019 13.05, Christian Brauner wrote: > > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > >> + if (unlikely(!access_ok(dst, usize))) > >> + return -EFAULT; > >> + > >> + /* Deal with trailing bytes. */ > >> + if (usize < ksize) { > >> + if (memchr_inv(src + size, 0, rest)) > >> + return -EFBIG; > >> + } else if (usize > ksize) { > >> + if (__memzero_user(dst + size, rest)) > >> + return -EFAULT; > > > > Is zeroing that memory really our job? Seems to me we should just check > > it is zeroed. > > Of course it is, otherwise you'd require userspace to clear the output > buffer it gives us, which in the majority of cases is wasted work. It's > much easier to reason about if we just say "the kernel populates [uaddr, > uaddr + usize)". I don't really mind either way so sure. :) 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 2C24AC43331 for ; Sat, 7 Sep 2019 09:01:44 +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 A689E208C3 for ; Sat, 7 Sep 2019 09:01:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A689E208C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ubuntu.com 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 46QT1x2QdBzDr4R for ; Sat, 7 Sep 2019 19:01:41 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=ubuntu.com (client-ip=91.189.89.112; helo=youngberry.canonical.com; envelope-from=christian.brauner@ubuntu.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46PJQl2Q6kzDqck for ; Thu, 5 Sep 2019 21:30:39 +1000 (AEST) Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i5pxg-0002oG-P2; Thu, 05 Sep 2019 11:30:00 +0000 Date: Thu, 5 Sep 2019 13:29:59 +0200 From: Christian Brauner To: Rasmus Villemoes Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905112958.ldzyzyuqn5akkhzy@wittgenstein> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Mailman-Approved-At: Sat, 07 Sep 2019 18:55:13 +1000 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-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , Jiri Olsa , Alexander Shishkin , Ingo Molnar , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, Aleksa Sarai , Al Viro , Andy Lutomirski , Shuah Khan , Namhyung Kim , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote: > On 05/09/2019 13.05, Christian Brauner wrote: > > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > >> + if (unlikely(!access_ok(dst, usize))) > >> + return -EFAULT; > >> + > >> + /* Deal with trailing bytes. */ > >> + if (usize < ksize) { > >> + if (memchr_inv(src + size, 0, rest)) > >> + return -EFBIG; > >> + } else if (usize > ksize) { > >> + if (__memzero_user(dst + size, rest)) > >> + return -EFAULT; > > > > Is zeroing that memory really our job? Seems to me we should just check > > it is zeroed. > > Of course it is, otherwise you'd require userspace to clear the output > buffer it gives us, which in the majority of cases is wasted work. It's > much easier to reason about if we just say "the kernel populates [uaddr, > uaddr + usize)". I don't really mind either way so sure. :) 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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 D704BC3A5A5 for ; Thu, 5 Sep 2019 11:30:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 AE3452070C for ; Thu, 5 Sep 2019 11:30:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="UOwrrne3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE3452070C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RIWHq4grzlPYhhooLTHE7FmNX6hUv8ddWnKeAfhvwRw=; b=UOwrrne3mkf3Ut QKMO+UgZPXDsWkduIoybZHKHNrL/pVpfQyOhwsIC8Fpfkj2F/Q743j0nmsan1xgiq9tzp0ULVk5dv KPup3BnhexKnMtA9777BtM0/a3/xZpa4cliU0Ns9MG+B4h18BHKyHx5nTv80b/uT6fhzmQjZNV9Xq lyKWLAvLXSHiwJXyeUgJTTemsIQiCBuqswJ3W9K0vKMAFOtGvn0OW3llpRIY6KqaADRTjSJpBpO9I MSrd3R/IY8WbOcJ/1h12zS+gLlft9i9UGiye9GaxwQ1BlMOguzScSCkFYgwPBf+ousx10PCyigtXS sdpcDMrhOInvih8Iw7NA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i5pyI-0007z6-Cb; Thu, 05 Sep 2019 11:30:38 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5pyE-0007xq-Un for linux-arm-kernel@lists.infradead.org; Thu, 05 Sep 2019 11:30:36 +0000 Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i5pxg-0002oG-P2; Thu, 05 Sep 2019 11:30:00 +0000 Date: Thu, 5 Sep 2019 13:29:59 +0200 From: Christian Brauner To: Rasmus Villemoes Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905112958.ldzyzyuqn5akkhzy@wittgenstein> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110544.d6c5t7rx25kvywmi@wittgenstein> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190905_043035_133677_7EEC0526 X-CRM114-Status: GOOD ( 12.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , Jiri Olsa , Alexander Shishkin , Ingo Molnar , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, Aleksa Sarai , Al Viro , Andy Lutomirski , Shuah Khan , Namhyung Kim , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote: > On 05/09/2019 13.05, Christian Brauner wrote: > > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > >> + if (unlikely(!access_ok(dst, usize))) > >> + return -EFAULT; > >> + > >> + /* Deal with trailing bytes. */ > >> + if (usize < ksize) { > >> + if (memchr_inv(src + size, 0, rest)) > >> + return -EFBIG; > >> + } else if (usize > ksize) { > >> + if (__memzero_user(dst + size, rest)) > >> + return -EFAULT; > > > > Is zeroing that memory really our job? Seems to me we should just check > > it is zeroed. > > Of course it is, otherwise you'd require userspace to clear the output > buffer it gives us, which in the majority of cases is wasted work. It's > much easier to reason about if we just say "the kernel populates [uaddr, > uaddr + usize)". I don't really mind either way so sure. :) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel