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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 ADB94C4332F for ; Sun, 8 Sep 2019 16:26:46 +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 B3195214DB for ; Sun, 8 Sep 2019 16:26:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3195214DB 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 46RGrz2BVJzDqTN for ; Mon, 9 Sep 2019 02:26:43 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=cyphar.com (client-ip=2001:67c:2050:104:0:2:25:2; 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 (mx2a.mailbox.org [IPv6:2001:67c:2050:104:0:2:25:2]) (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 46RGpy4jzxzDqLr for ; Mon, 9 Sep 2019 02:24:55 +1000 (AEST) Received: from smtp1.mailbox.org (smtp1.mailbox.org [80.241.60.240]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id F270BA10CE; Sun, 8 Sep 2019 18:24:39 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id RaAVojXx0viX; Sun, 8 Sep 2019 18:24:32 +0200 (CEST) Date: Mon, 9 Sep 2019 02:24:19 +1000 From: Aleksa Sarai To: Jeff Layton Subject: Re: [PATCH v12 11/12] open: openat2(2) syscall Message-ID: <20190908162419.yrzm2s7rflqgdxig@yavin> References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-12-cyphar@cyphar.com> <7236f382d72130f2afbbe8940e72cc67e5c6dce0.camel@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gzznbyzuni6ynbc5" Content-Disposition: inline In-Reply-To: <7236f382d72130f2afbbe8940e72cc67e5c6dce0.camel@kernel.org> 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, Jiri Olsa , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , Shuah Khan , 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 , 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" --gzznbyzuni6ynbc5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-09-07, Jeff Layton wrote: > On Thu, 2019-09-05 at 06:19 +1000, Aleksa Sarai wrote: > > + * @flags: O_* flags. > > + * @mode: O_CREAT/O_TMPFILE file mode. > > + * @upgrade_mask: UPGRADE_* flags (to restrict O_PATH re-opening). > > + * @resolve: RESOLVE_* flags. > > + */ > > +struct open_how { > > + __u32 flags; > > + union { > > + __u16 mode; > > + __u16 upgrade_mask; > > + }; > > + __u16 resolve; > > +}; > > + > > +#define OPEN_HOW_SIZE_VER0 8 /* sizeof first published struct */ > > + >=20 > Hmm, there is no version field. When you want to expand this in the > future, what is the plan? Add a new flag to indicate that it's some > length? The "version number" is the size of the struct. Any extensions we make are appended to the struct (openat2 now takes a size_t argument), and the new copy_struct_{to,from}_user() helpers handle all of the permutations of {old,new} kernel and {old,new} user space. This is how clone3(), sched_[gs]etattr() and perf_event_open() all operate (all of the sigset syscalls operate similarly but don't gracefully handle different kernel vintages -- you just get -EINVAL). --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --gzznbyzuni6ynbc5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXXUrMAAKCRCdlLljIbnQ EgC+AQCVKXVqUiPLaSjLjt+ByWrSsopM/OM3NwCHHZ5oD+CB1gD/cSuQohVmXskg v8dQLpd9K1QW//8GG3Aa/FRHhqPAfAU= =G4Hw -----END PGP SIGNATURE----- --gzznbyzuni6ynbc5--