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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 9DBE9C71155 for ; Wed, 2 Dec 2020 09:56:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47D772222F for ; Wed, 2 Dec 2020 09:56:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388410AbgLBJ4g (ORCPT ); Wed, 2 Dec 2020 04:56:36 -0500 Received: from verein.lst.de ([213.95.11.211]:53361 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388389AbgLBJ4g (ORCPT ); Wed, 2 Dec 2020 04:56:36 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 1049267373; Wed, 2 Dec 2020 10:55:48 +0100 (CET) Date: Wed, 2 Dec 2020 10:55:47 +0100 From: Christoph Hellwig To: Christian Brauner Cc: Christoph Hellwig , Alexander Viro , Christoph Hellwig , linux-fsdevel@vger.kernel.org, John Johansen , James Morris , Mimi Zohar , Dmitry Kasatkin , Stephen Smalley , Casey Schaufler , Arnd Bergmann , Andreas Dilger , OGAWA Hirofumi , Geoffrey Thomas , Mrunal Patel , Josh Triplett , Andy Lutomirski , Theodore Tso , Alban Crequy , Tycho Andersen , David Howells , James Bottomley , Seth Forshee , =?iso-8859-1?Q?St=E9phane?= Graber , Aleksa Sarai , Lennart Poettering , "Eric W. Biederman" , smbarber@chromium.org, Phil Estes , Serge Hallyn , Kees Cook , Todd Kjos , Paul Moore , Jonathan Corbet , containers@lists.linux-foundation.org, fstests@vger.kernel.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, linux-ext4@vger.kernel.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org Subject: Re: [PATCH v3 04/38] fs: add mount_setattr() Message-ID: <20201202095547.GA6408@lst.de> References: <20201128213527.2669807-1-christian.brauner@ubuntu.com> <20201128213527.2669807-5-christian.brauner@ubuntu.com> <20201201104907.GD27730@lst.de> <20201202094218.ym5zqnulwz6gj6eo@wittgenstein> <20201202094751.GA6129@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201202094751.GA6129@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: On Wed, Dec 02, 2020 at 10:47:51AM +0100, Christoph Hellwig wrote: > On Wed, Dec 02, 2020 at 10:42:18AM +0100, Christian Brauner wrote: > > > > + if (upper_32_bits(attr->attr_set)) > > > > + return -EINVAL; > > > > + if (build_attr_flags(lower_32_bits(attr->attr_set), &kattr->attr_set)) > > > > + return -EINVAL; > > > > + > > > > + if (upper_32_bits(attr->attr_clr)) > > > > + return -EINVAL; > > > > + if (build_attr_flags(lower_32_bits(attr->attr_clr), &kattr->attr_clr)) > > > > + return -EINVAL; > > > > > > What is so magic about the upper and lower 32 bits? > > > > Nothing apart from the fact that they arent't currently valid. I can > > think about reworking these lines. Or do you already have a preferred > > way of doing this in mind? > > Just turn the attr_flags argument to build_attr_flags into a u64 and > the first sanity check there will catch all invalid flags, no matter > where they are places. That should also generate more efficient code. And while we're at it: the check for valid flags in the current code is a little weird, given that build_attr_flags checks for them, and but sys_fsmount also has its own slightly narrower checks. I think it might make sense to split the validity check out of build_attr_flags. E.g. something like: static unsigned int attr_flags_to_mnt_flags(u64 attr_flags) { unsigned int mnt_flags = 0; if (attr_flags & MOUNT_ATTR_RDONLY) mnt_flags |= MNT_READONLY; if (attr_flags & MOUNT_ATTR_NOSUID) mnt_flags |= MNT_NOSUID; if (attr_flags & MOUNT_ATTR_NODEV) mnt_flags |= MNT_NODEV; if (attr_flags & MOUNT_ATTR_NOEXEC) mnt_flags |= MNT_NOEXEC; if (attr_flags & MOUNT_ATTR_NODIRATIME) mnt_flags |= MNT_NODIRATIME; return mnt_flags; } #define MOUNT_SETATTR_VALID_FLAGS \ (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \ MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME | \ MOUNT_ATTR_IDMAP) static int build_mount_kattr(const struct mount_attr *attr, size_t usize, struct mount_kattr *kattr, unsigned int flags) { ... if ((attr->attr_set | attr->attr_clr) & ~MOUNT_SETATTR_VALID_FLAGS) return -EINVAL; kattr->attr_set = attr_flags_to_mnt_flags(attr->attr_set); kattr->attr_clr = attr_flags_to_mnt_flags(attr->attr_clr); ... }