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--