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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 53611C433DB for ; Thu, 14 Jan 2021 22:11:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B88822A84 for ; Thu, 14 Jan 2021 22:11:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728311AbhANWLm (ORCPT ); Thu, 14 Jan 2021 17:11:42 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:46492 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726880AbhANWLl (ORCPT ); Thu, 14 Jan 2021 17:11:41 -0500 Received: from ip5f5af0a0.dynamic.kabel-deutschland.de ([95.90.240.160] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1l0ApP-0007xM-ND; Thu, 14 Jan 2021 22:10:51 +0000 Date: Thu, 14 Jan 2021 23:10:48 +0100 From: Christian Brauner To: Dave Chinner Cc: 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 , =?utf-8?B?U3TDqXBoYW5l?= Graber , Linus Torvalds , 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, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH v5 37/42] xfs: support idmapped mounts Message-ID: <20210114221048.ppf2pfuxrjak4kvm@wittgenstein> References: <20210112220124.837960-1-christian.brauner@ubuntu.com> <20210112220124.837960-38-christian.brauner@ubuntu.com> <20210114205154.GL331610@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210114205154.GL331610@dread.disaster.area> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Fri, Jan 15, 2021 at 07:51:54AM +1100, Dave Chinner wrote: > On Tue, Jan 12, 2021 at 11:01:19PM +0100, Christian Brauner wrote: > > From: Christoph Hellwig > > > > Enable idmapped mounts for xfs. This basically just means passing down > > the user_namespace argument from the VFS methods down to where it is > > passed to helper. > > > > Signed-off-by: Christoph Hellwig > .... > > @@ -654,6 +658,7 @@ xfs_vn_change_ok( > > */ > > static int > > xfs_setattr_nonsize( > > + struct user_namespace *mnt_userns, > > struct xfs_inode *ip, > > struct iattr *iattr) > > { > > @@ -813,7 +818,7 @@ xfs_setattr_nonsize( > > * Posix ACL code seems to care about this issue either. > > */ > > if (mask & ATTR_MODE) { > > - error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode); > > + error = posix_acl_chmod(mnt_userns, inode, inode->i_mode); > > if (error) > > return error; > > } > > @@ -868,7 +873,7 @@ xfs_setattr_size( > > * Use the regular setattr path to update the timestamps. > > */ > > iattr->ia_valid &= ~ATTR_SIZE; > > - return xfs_setattr_nonsize(ip, iattr); > > + return xfs_setattr_nonsize(&init_user_ns, ip, iattr); > > Shouldn't that be passing mnt_userns? Hey Dave, Thanks for taking a look. This is the time updating codepath. xfs_setattr_size(); -> xfs_setattr_nonsize(&init_user_ns); The xfs_setattr_size() helper will assert: ASSERT((iattr->ia_valid & (ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET| ATTR_MTIME_SET|ATTR_KILL_PRIV|ATTR_TIMES_SET)) == 0); While the xfs_setattr_nonsize() helper will further assert: ASSERT((mask & ATTR_SIZE) == 0); so xfs_setattr_nonsize() in this callpath is only used to update the if (!(iattr->ia_valid & (ATTR_CTIME|ATTR_MTIME))) return 0; so there's no interactions with idmappings in any way. Simply passing mnt_userns might be clearer though. But if this would be using the wrong idmapping the xfstest suite I added would've immediately caught that and failed. But this specific codepath can also be reliably hit from userspace by doing ftruncate(fd, 0) so just to be extra sure I added truncate tests to the xfstests now for both the idmapped and non-idmapped case. Christian