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,URIBL_BLOCKED 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 4B7E9C742B2 for ; Fri, 12 Jul 2019 10:58:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F7BE2084B for ; Fri, 12 Jul 2019 10:58:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726973AbfGLK6N (ORCPT ); Fri, 12 Jul 2019 06:58:13 -0400 Received: from mx1.mailbox.org ([80.241.60.212]:42972 "EHLO mx1.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbfGLK6N (ORCPT ); Fri, 12 Jul 2019 06:58:13 -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 mx1.mailbox.org (Postfix) with ESMTPS id 648AF5427E; Fri, 12 Jul 2019 12:58:07 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter01.heinlein-hosting.de (spamfilter01.heinlein-hosting.de [80.241.56.115]) (amavisd-new, port 10030) with ESMTP id la_RnxBryad0; Fri, 12 Jul 2019 12:57:56 +0200 (CEST) Date: Fri, 12 Jul 2019 20:57:45 +1000 From: Aleksa Sarai To: Al Viro Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Christian Brauner , David Drysdale , Andy Lutomirski , Linus Torvalds , Eric Biederman , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , Chanho Min , Oleg Nesterov , Aleksa Sarai , 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 v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190712105745.nruaftgeat6irhzr@yavin> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="f3oogwkmh2sysq6o" Content-Disposition: inline In-Reply-To: <20190712043341.GI17978@ZenIV.linux.org.uk> Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org --f3oogwkmh2sysq6o Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-07-12, Al Viro wrote: > On Sun, Jul 07, 2019 at 12:57:32AM +1000, Aleksa Sarai wrote: > > @@ -1442,8 +1464,11 @@ static int follow_dotdot_rcu(struct nameidata *n= d) > > struct inode *inode =3D nd->inode; > > =20 > > while (1) { > > - if (path_equal(&nd->path, &nd->root)) > > + if (path_equal(&nd->path, &nd->root)) { > > + if (unlikely(nd->flags & LOOKUP_BENEATH)) > > + return -EXDEV; >=20 > > @@ -1468,6 +1493,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) > > return -ECHILD; > > if (&mparent->mnt =3D=3D nd->path.mnt) > > break; > > + if (unlikely(nd->flags & LOOKUP_XDEV)) > > + return -EXDEV; > > /* we know that mountpoint was pinned */ > > nd->path.dentry =3D mountpoint; > > nd->path.mnt =3D &mparent->mnt; > > @@ -1482,6 +1509,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) > > return -ECHILD; > > if (!mounted) > > break; > > + if (unlikely(nd->flags & LOOKUP_XDEV)) > > + return -EXDEV; >=20 > Are you sure these failure exits in follow_dotdot_rcu() won't give > suprious hard errors? I could switch to -ECHILD for the *_rcu() checks if you'd prefer that. Though, I'd have (probably naively) thought that you'd have already gotten -ECHILD from the seqlock checks if there was a race during ".." handling. > > + if (unlikely(nd->flags & LOOKUP_BENEATH)) { > > + error =3D dirfd_path_init(nd); > > + if (unlikely(error)) > > + return ERR_PTR(error); > > + nd->root =3D nd->path; > > + if (!(nd->flags & LOOKUP_RCU)) > > + path_get(&nd->root); > > + } > > if (*s =3D=3D '/') { > > if (likely(!nd->root.mnt)) > > set_root(nd); > > @@ -2350,9 +2400,11 @@ static const char *path_init(struct nameidata *n= d, unsigned flags) > > s =3D ERR_PTR(error); > > return s; > > } > > - error =3D dirfd_path_init(nd); > > - if (unlikely(error)) > > - return ERR_PTR(error); > > + if (likely(!nd->path.mnt)) { >=20 > Is that a weird way of saying "if we hadn't already called dirfd_path_ini= t()"? Yes. I did it to be more consistent with the other "have we got the root" checks elsewhere. Is there another way you'd prefer I do it? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --f3oogwkmh2sysq6o Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXShnpgAKCRCdlLljIbnQ EgLTAP4nuVmi0292tyCAkB4Di0UUtazb2EsZPgKq9s2vRoyuFAD/UKONDBSK3VN9 06Id1xrmV0JIYJSqOIdF2oJIncJ8ZwI= =5hbR -----END PGP SIGNATURE----- --f3oogwkmh2sysq6o--