From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [PATCH 1/2] implement uid mount option for ext2 Date: Fri, 24 Jul 2009 10:52:01 -0600 Message-ID: <20090724165201.GA4231@webber.adilger.int> References: <1248348991-849-1-git-send-email-ludwig.nussel@suse.de> <1248431444-18842-1-git-send-email-ludwig.nussel@suse.de> <1248431444-18842-2-git-send-email-ludwig.nussel@suse.de> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII Content-Transfer-Encoding: 7BIT Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Ludwig Nussel Return-path: Received: from sca-es-mail-1.Sun.COM ([192.18.43.132]:38711 "EHLO sca-es-mail-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753398AbZGXQwd (ORCPT ); Fri, 24 Jul 2009 12:52:33 -0400 Content-disposition: inline In-reply-to: <1248431444-18842-2-git-send-email-ludwig.nussel@suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Jul 24, 2009 12:30 +0200, Ludwig Nussel wrote: > @@ -1353,7 +1356,13 @@ int ext2_write_inode(struct inode *inode, int do_sync) > > ext2_get_inode_flags(ei); > raw_inode->i_mode = cpu_to_le16(inode->i_mode); > + if (EXT2_SB(sb)->s_uid && > + inode->i_uid == EXT2_SB(sb)->s_uid) { > + raw_inode->i_uid_high = 0; > + raw_inode->i_uid_low = 0; > + raw_inode->i_gid_high = 0; > + raw_inode->i_gid_low = 0; I would suggest to also clear the SUID flag on this inode. Otherwise, it opens the risk of creating SUID root files that might be handled incorrectly. To be honest, rather than mapping the specified file to uid == 0/gid == 0 it would be more useful (and safe) to allow specifying a mapping from one UID to another, or have the on-disk UID always be set to/from the specified UID. Given that your original problem is for the user having UIDX on system X and UIDY on system Y, you should just specify the X->Y mapping explicitly, instead of an implicit X->0 mapping. Otherwise, if the user is unable to access root-owned files on either one of system X or Y your current patch fails. I would have the option be something like "uid={local_uid}={disk_uid}" (which hopefully the option parser can handle), or "uid=X:Y" if not. That way, the on-disk filesystem will remain correct for at least one of the two systems. If someone wants to specify disk_uid=0 that is fine, but it shouldn't be the only option. PS - please also send a patch for ext4. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.