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 BE92AC2D0F2 for ; Tue, 31 Mar 2020 14:39:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B0AD20784 for ; Tue, 31 Mar 2020 14:39:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730095AbgCaOj1 (ORCPT ); Tue, 31 Mar 2020 10:39:27 -0400 Received: from mout-p-201.mailbox.org ([80.241.56.171]:19264 "EHLO mout-p-201.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgCaOj0 (ORCPT ); Tue, 31 Mar 2020 10:39:26 -0400 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 mout-p-201.mailbox.org (Postfix) with ESMTPS id 48sBmX0b2jzQlF1; Tue, 31 Mar 2020 16:39:24 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by gerste.heinlein-support.de (gerste.heinlein-support.de [91.198.250.173]) (amavisd-new, port 10030) with ESMTP id FoOKAboSO1mL; Tue, 31 Mar 2020 16:39:20 +0200 (CEST) Date: Wed, 1 Apr 2020 01:39:11 +1100 From: Aleksa Sarai To: "Michael Kerrisk (man-pages)" Cc: Al Viro , Christian Brauner , Aleksa Sarai , linux-man@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH man-pages v2 2/2] openat2.2: document new openat2(2) syscall Message-ID: <20200331143911.lokfoq3lqfri2mgy@yavin.dot.cyphar.com> References: <20200202151907.23587-1-cyphar@cyphar.com> <20200202151907.23587-3-cyphar@cyphar.com> <1567baea-5476-6d21-4f03-142def0f62e3@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="l2lpn76pgjx5xchv" Content-Disposition: inline In-Reply-To: <1567baea-5476-6d21-4f03-142def0f62e3@gmail.com> X-Rspamd-Queue-Id: CF12A1743 X-Rspamd-Score: -2.96 / 15.00 / 200.00 Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org --l2lpn76pgjx5xchv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2020-03-30, Michael Kerrisk (man-pages) wrote: > Hello Aleksa, >=20 > On 2/2/20 4:19 PM, Aleksa Sarai wrote: > > Rather than trying to merge the new syscall documentation into open.2 > > (which would probably result in the man-page being incomprehensible), > > instead the new syscall gets its own dedicated page with links between > > open(2) and openat2(2) to avoid duplicating information such as the list > > of O_* flags or common errors. > >=20 > > In addition to describing all of the key flags, information about the > > extensibility design is provided so that users can better understand why > > they need to pass sizeof(struct open_how) and how their programs will > > work across kernels. After some discussions with David Laight, I also > > included explicit instructions to zero the structure to avoid issues > > when recompiling with new headers. > >=20 > > Signed-off-by: Aleksa Sarai >=20 > Thanks. I've applied this patch, but also done quite a lot of > editing of the page. The current draft is below (and also pushed=20 > to Git). Could I ask you to review the page, to see if I injected > any error during my edits. Looks good to me. > In addition, I've added a number of FIXMEs in comments > in the page source. Can you please check these, and let me > know your thoughts. Will do, see below. > .\" FIXME I find the "previously-functional systems" in the previous > .\" sentence a little odd (since openat2() ia new sysycall), so I would > .\" like to clarify a little... > .\" Are you referring to the scenario where someone might take an > .\" existing application that uses openat() and replaces the uses > .\" of openat() with openat2()? In which case, is it correct to > .\" understand that you mean that one should not just indiscriminately > .\" add the RESOLVE_NO_XDEV flag to all of the openat2() calls? > .\" If I'm not on the right track, could you point me in the right > .\" direction please. This is mostly meant as a warning to hopefully avoid applications because the developer didn't realise that system paths may contain symlinks or bind-mounts. For an application which has switched to openat2() and then uses RESOLVE_NO_SYMLINKS for a non-security reason, it's possible that on some distributions (or future versions of a distribution) that their application will stop working because a system path suddenly contains a symlink or is a bind-mount. This was a concern which was brought up on LWN some time ago. If you can think of a phrasing that makes this more clear, I'd appreciate it. > .\" FIXME: what specific details in symlink(7) are being referred > .\" by the following sentence? It's not clear. The section on magic-links, but you're right that the sentence ordering is a bit odd. It should probably go after the first sentence. > .\" FIXME I found the following hard to understand (in particular, the > .\" meaning of "scoped" is unclear) , and reworded as below. Is it okay? > .\" Absolute symbolic links and ".." path components will be scoped to > .\" .IR dirfd . Scoped does broadly mean "interpreted relative to", though the difference is mainly that when I said scoped it's meant to be more of an assertive claim ("the kernel promises to always treat this path inside dirfd"). But "interpreted relative to" is a clearer way of phrasing the semantics, so I'm okay with this change. > .\" FIXME The next piece is unclear (to me). What kind of ".." escape > .\" attempts does chroot() not detect that RESOLVE_IN_ROOT does? If the root is moved, you can escape from a chroot(2). But this sentence might not really belong in a man-page since it's describing (important) aspects of the implementation and not the semantics. --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --l2lpn76pgjx5xchv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXoNWDAAKCRCdlLljIbnQ EuhhAQDrGJcSC2tvaVHSZirH1uENpWOgqxV1HHQaNXnurRE1MwD/eS7jz/feBrZa HAM6s15BEz8f1DvF4UAf0nb8LHajngw= =O1HR -----END PGP SIGNATURE----- --l2lpn76pgjx5xchv--