From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aleksa Sarai Date: Thu, 05 Sep 2019 11:27:18 +0000 Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-Id: <20190905112718.ojg3znly6x3m4mjq@yavin.dot.cyphar.com> MIME-Version: 1 Content-Type: multipart/mixed; boundary="nkbo7v76ghbobp4m" List-Id: References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> In-Reply-To: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> To: Christian Brauner Cc: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Rasmus Villemoes , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg --nkbo7v76ghbobp4m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > A common pattern for syscall extensions is increasing the size of a > > struct passed from userspace, such that the zero-value of the new fields > > result in the old kernel behaviour (allowing for a mix of userspace and > > kernel vintages to operate on one another in most cases). This is done > > in both directions -- hence two helpers -- though it's more common to > > have to copy user space structs into kernel space. > >=20 > > Previously there was no common lib/ function that implemented > > the necessary extension-checking semantics (and different syscalls > > implemented them slightly differently or incompletely[1]). A future > > patch replaces all of the common uses of this pattern to use the new > > copy_struct_{to,from}_user() helpers. > >=20 > > [1]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > > always rejects differently-sized struct arguments. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai >=20 > I would probably split this out into a separate patchset. It can very > well go in before openat2(). Thoughts? Yeah, I'll split this and the related patches out -- though I will admit I'm not sure how you're supposed to deal with multiple independent patchsets that depend on each other. How will folks reviewing openat2(2) know to include the lib/struct_user.c changes? Also, whose tree should it go through? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nkbo7v76ghbobp4m Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXDxEwAKCRCdlLljIbnQ EqovAQD8WBncNVUTEL0Y3xtDhqYMDFHga+X5xWtEwl2PAh4uVQEAhuzdaAU+gBqt VqtP9IF4PFfoqMmGbekI1BKCWI4gmgo= =UsGw -----END PGP SIGNATURE----- --nkbo7v76ghbobp4m-- 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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 B193CC3A5A5 for ; Thu, 5 Sep 2019 11:27:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F39822CF5 for ; Thu, 5 Sep 2019 11:27:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732760AbfIEL14 (ORCPT ); Thu, 5 Sep 2019 07:27:56 -0400 Received: from mx2.mailbox.org ([80.241.60.215]:61762 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726231AbfIEL1z (ORCPT ); Thu, 5 Sep 2019 07:27:55 -0400 Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:105:465:1:1:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 80455A162A; Thu, 5 Sep 2019 13:27:48 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter05.heinlein-hosting.de (spamfilter05.heinlein-hosting.de [80.241.56.123]) (amavisd-new, port 10030) with ESMTP id bvZM-eYrS-l9; Thu, 5 Sep 2019 13:27:44 +0200 (CEST) Date: Thu, 5 Sep 2019 21:27:18 +1000 From: Aleksa Sarai To: Christian Brauner Cc: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Rasmus Villemoes , 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: <20190905112718.ojg3znly6x3m4mjq@yavin.dot.cyphar.com> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nkbo7v76ghbobp4m" Content-Disposition: inline In-Reply-To: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org --nkbo7v76ghbobp4m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > A common pattern for syscall extensions is increasing the size of a > > struct passed from userspace, such that the zero-value of the new fields > > result in the old kernel behaviour (allowing for a mix of userspace and > > kernel vintages to operate on one another in most cases). This is done > > in both directions -- hence two helpers -- though it's more common to > > have to copy user space structs into kernel space. > >=20 > > Previously there was no common lib/ function that implemented > > the necessary extension-checking semantics (and different syscalls > > implemented them slightly differently or incompletely[1]). A future > > patch replaces all of the common uses of this pattern to use the new > > copy_struct_{to,from}_user() helpers. > >=20 > > [1]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > > always rejects differently-sized struct arguments. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai >=20 > I would probably split this out into a separate patchset. It can very > well go in before openat2(). Thoughts? Yeah, I'll split this and the related patches out -- though I will admit I'm not sure how you're supposed to deal with multiple independent patchsets that depend on each other. How will folks reviewing openat2(2) know to include the lib/struct_user.c changes? Also, whose tree should it go through? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nkbo7v76ghbobp4m Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXDxEwAKCRCdlLljIbnQ EqovAQD8WBncNVUTEL0Y3xtDhqYMDFHga+X5xWtEwl2PAh4uVQEAhuzdaAU+gBqt VqtP9IF4PFfoqMmGbekI1BKCWI4gmgo= =UsGw -----END PGP SIGNATURE----- --nkbo7v76ghbobp4m-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aleksa Sarai Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Date: Thu, 5 Sep 2019 21:27:18 +1000 Message-ID: <20190905112718.ojg3znly6x3m4mjq@yavin.dot.cyphar.com> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nkbo7v76ghbobp4m" Return-path: Content-Disposition: inline In-Reply-To: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> Sender: linux-kernel-owner@vger.kernel.org To: Christian Brauner Cc: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Rasmus Villemoes , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg List-Id: linux-api@vger.kernel.org --nkbo7v76ghbobp4m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > A common pattern for syscall extensions is increasing the size of a > > struct passed from userspace, such that the zero-value of the new fields > > result in the old kernel behaviour (allowing for a mix of userspace and > > kernel vintages to operate on one another in most cases). This is done > > in both directions -- hence two helpers -- though it's more common to > > have to copy user space structs into kernel space. > >=20 > > Previously there was no common lib/ function that implemented > > the necessary extension-checking semantics (and different syscalls > > implemented them slightly differently or incompletely[1]). A future > > patch replaces all of the common uses of this pattern to use the new > > copy_struct_{to,from}_user() helpers. > >=20 > > [1]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > > always rejects differently-sized struct arguments. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai >=20 > I would probably split this out into a separate patchset. It can very > well go in before openat2(). Thoughts? Yeah, I'll split this and the related patches out -- though I will admit I'm not sure how you're supposed to deal with multiple independent patchsets that depend on each other. How will folks reviewing openat2(2) know to include the lib/struct_user.c changes? Also, whose tree should it go through? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nkbo7v76ghbobp4m Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXDxEwAKCRCdlLljIbnQ EqovAQD8WBncNVUTEL0Y3xtDhqYMDFHga+X5xWtEwl2PAh4uVQEAhuzdaAU+gBqt VqtP9IF4PFfoqMmGbekI1BKCWI4gmgo= =UsGw -----END PGP SIGNATURE----- --nkbo7v76ghbobp4m-- 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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 3B9EFC3A5A5 for ; Thu, 5 Sep 2019 11:30:54 +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 B7CF32070C for ; Thu, 5 Sep 2019 11:30:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B7CF32070C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.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 46PJQy5S7HzDqgH for ; Thu, 5 Sep 2019 21:30:50 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=cyphar.com (client-ip=80.241.60.215; helo=mx2.mailbox.org; envelope-from=cyphar@cyphar.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=cyphar.com Received: from mx2.mailbox.org (mx2.mailbox.org [80.241.60.215]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46PJMg5JHMzDr41 for ; Thu, 5 Sep 2019 21:27:55 +1000 (AEST) Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:105:465:1:1:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 80455A162A; Thu, 5 Sep 2019 13:27:48 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter05.heinlein-hosting.de (spamfilter05.heinlein-hosting.de [80.241.56.123]) (amavisd-new, port 10030) with ESMTP id bvZM-eYrS-l9; Thu, 5 Sep 2019 13:27:44 +0200 (CEST) Date: Thu, 5 Sep 2019 21:27:18 +1000 From: Aleksa Sarai To: Christian Brauner Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905112718.ojg3znly6x3m4mjq@yavin.dot.cyphar.com> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nkbo7v76ghbobp4m" Content-Disposition: inline In-Reply-To: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> 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 , Rasmus Villemoes , 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, linux-m68k@lists.linux-m68k.org, Al Viro , Andy Lutomirski , Shuah Khan , Namhyung Kim , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.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" --nkbo7v76ghbobp4m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > A common pattern for syscall extensions is increasing the size of a > > struct passed from userspace, such that the zero-value of the new fields > > result in the old kernel behaviour (allowing for a mix of userspace and > > kernel vintages to operate on one another in most cases). This is done > > in both directions -- hence two helpers -- though it's more common to > > have to copy user space structs into kernel space. > >=20 > > Previously there was no common lib/ function that implemented > > the necessary extension-checking semantics (and different syscalls > > implemented them slightly differently or incompletely[1]). A future > > patch replaces all of the common uses of this pattern to use the new > > copy_struct_{to,from}_user() helpers. > >=20 > > [1]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > > always rejects differently-sized struct arguments. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai >=20 > I would probably split this out into a separate patchset. It can very > well go in before openat2(). Thoughts? Yeah, I'll split this and the related patches out -- though I will admit I'm not sure how you're supposed to deal with multiple independent patchsets that depend on each other. How will folks reviewing openat2(2) know to include the lib/struct_user.c changes? Also, whose tree should it go through? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nkbo7v76ghbobp4m Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXDxEwAKCRCdlLljIbnQ EqovAQD8WBncNVUTEL0Y3xtDhqYMDFHga+X5xWtEwl2PAh4uVQEAhuzdaAU+gBqt VqtP9IF4PFfoqMmGbekI1BKCWI4gmgo= =UsGw -----END PGP SIGNATURE----- --nkbo7v76ghbobp4m-- 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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 4B9B9C3A5A5 for ; Thu, 5 Sep 2019 11:28:04 +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 1BC7522CEC for ; Thu, 5 Sep 2019 11:28:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="msumDZzG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1BC7522CEC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.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-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-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9lq7cf/Apsp7kJdhjEqhuQoyacI9iC9W8xVgigEVUqk=; b=msumDZzGpJ6Mm8f7QQxInp69z DRV1EvAP9EnGdAjwg/sl6AeLu7EQXX2PgPD+3VzAfikLj6GjLR0RBPngn2LyEgo243KjF+6/TasFi DN/VPTqyemgEv4Zb5KE695mljR1ptL7p0PiDbnjJE+aRe01G3WIAxgvHmBVExI9LEhprMf79F28sW zm7SXhiC5bBSR5rLmUo/ZXZa9zZmx8VNJsnoBbqRMy1dYowonzNdIFOEhT9J2byS2wqlB7BQ+yXth 6hg12MWqizsPzdF4lBEpLnd73m+9JFAbC6FFUWII88DmdfE8bhHl+glRHzXd1mgV9Yty2djPyVRMq 7iq6PwexQ==; 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 1i5pvl-00065Q-P9; Thu, 05 Sep 2019 11:28:01 +0000 Received: from mx2.mailbox.org ([80.241.60.215]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5pvh-00064D-RN for linux-arm-kernel@lists.infradead.org; Thu, 05 Sep 2019 11:27:59 +0000 Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:105:465:1:1:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 80455A162A; Thu, 5 Sep 2019 13:27:48 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter05.heinlein-hosting.de (spamfilter05.heinlein-hosting.de [80.241.56.123]) (amavisd-new, port 10030) with ESMTP id bvZM-eYrS-l9; Thu, 5 Sep 2019 13:27:44 +0200 (CEST) Date: Thu, 5 Sep 2019 21:27:18 +1000 From: Aleksa Sarai To: Christian Brauner Subject: Re: [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Message-ID: <20190905112718.ojg3znly6x3m4mjq@yavin.dot.cyphar.com> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-2-cyphar@cyphar.com> <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> MIME-Version: 1.0 In-Reply-To: <20190905110915.4vvhicg4ldmpi5u6@wittgenstein> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190905_042758_189983_8C50B6FC X-CRM114-Status: GOOD ( 20.30 ) 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 , Rasmus Villemoes , 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, linux-m68k@lists.linux-m68k.org, Al Viro , Andy Lutomirski , Shuah Khan , Namhyung Kim , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.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: multipart/mixed; boundary="===============3188958737127614295==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============3188958737127614295== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nkbo7v76ghbobp4m" Content-Disposition: inline --nkbo7v76ghbobp4m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-05, Christian Brauner wrote: > On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote: > > A common pattern for syscall extensions is increasing the size of a > > struct passed from userspace, such that the zero-value of the new fields > > result in the old kernel behaviour (allowing for a mix of userspace and > > kernel vintages to operate on one another in most cases). This is done > > in both directions -- hence two helpers -- though it's more common to > > have to copy user space structs into kernel space. > >=20 > > Previously there was no common lib/ function that implemented > > the necessary extension-checking semantics (and different syscalls > > implemented them slightly differently or incompletely[1]). A future > > patch replaces all of the common uses of this pattern to use the new > > copy_struct_{to,from}_user() helpers. > >=20 > > [1]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > > always rejects differently-sized struct arguments. > >=20 > > Suggested-by: Rasmus Villemoes > > Signed-off-by: Aleksa Sarai >=20 > I would probably split this out into a separate patchset. It can very > well go in before openat2(). Thoughts? Yeah, I'll split this and the related patches out -- though I will admit I'm not sure how you're supposed to deal with multiple independent patchsets that depend on each other. How will folks reviewing openat2(2) know to include the lib/struct_user.c changes? Also, whose tree should it go through? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --nkbo7v76ghbobp4m Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXDxEwAKCRCdlLljIbnQ EqovAQD8WBncNVUTEL0Y3xtDhqYMDFHga+X5xWtEwl2PAh4uVQEAhuzdaAU+gBqt VqtP9IF4PFfoqMmGbekI1BKCWI4gmgo= =UsGw -----END PGP SIGNATURE----- --nkbo7v76ghbobp4m-- --===============3188958737127614295== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============3188958737127614295==--