From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id ED3557FED for ; Thu, 29 Jan 2015 17:54:58 -0600 (CST) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay3.corp.sgi.com (Postfix) with ESMTP id 6A8DDAC005 for ; Thu, 29 Jan 2015 15:54:55 -0800 (PST) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id Iqgtj1b12CHHPFZb for ; Thu, 29 Jan 2015 15:54:52 -0800 (PST) Date: Fri, 30 Jan 2015 10:53:15 +1100 From: Dave Chinner Subject: Re: [PATCH 6/9] xfs: XFS_IOCTL_SETXATTR can run in user namespaces Message-ID: <20150129235315.GG6282@dastard> References: <1422328486-24661-1-git-send-email-david@fromorbit.com> <1422328486-24661-7-git-send-email-david@fromorbit.com> <20150129153515.GF17652@laptop.bfoster> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20150129153515.GF17652@laptop.bfoster> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Brian Foster Cc: iustin@k1024.org, xfs@oss.sgi.com On Thu, Jan 29, 2015 at 10:35:15AM -0500, Brian Foster wrote: > On Tue, Jan 27, 2015 at 02:14:43PM +1100, Dave Chinner wrote: > > From: Dave Chinner > > > > Currently XFS_IOCTL_SETXATTR will fail if run in a user namespace as > > it it not allowed to change project IDs. The current code, however, > > also prevents any other change being made as well, so things like > > extent size hints cannot be set in user namespaces. This is wrong, > > so only disallow access to project IDs and related flags from inside > > the init namespace. > > > > Signed-off-by: Dave Chinner > > --- > > fs/xfs/xfs_ioctl.c | 22 +++++++++++++--------- > > 1 file changed, 13 insertions(+), 9 deletions(-) > > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > > index 563d2b4..ae6e1e3 100644 > > --- a/fs/xfs/xfs_ioctl.c > > +++ b/fs/xfs/xfs_ioctl.c > > @@ -1120,6 +1120,19 @@ xfs_ioctl_setattr( > > return -EINVAL; > > > > /* > > + * Project Quota ID state is only allowed to change from within the init > > + * namespace. Enforce that restriction only if we are trying to change > > + * the quota ID state. Everything else is allowed in user namespaces. > > + */ > > + if (current_user_ns() != &init_user_ns) { > > + if (xfs_get_projid(ip) != fa->fsx_projid) > > + return -EINVAL; > > + if ((fa->fsx_xflags & XFS_XFLAG_PROJINHERIT) ^ > > + (ip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)) > > Why not use != here? Looks fine, anyways: Because ^ has an implicit cast of the variables to boolean (i.e flag set or not), whereas != will only work if XFS_XFLAG_PROJINHERIT = XFS_DIFLAG_PROJINHERIT. Given that the moment we add more DIFLAGs to the xfs inode, the current "XFLAG value must match DIFLAG value" rule is going to be broken, I think that logical evaluation is a much safer practice for these types of comparisons. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs