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 <dchinner@xxxxxxxxxx>
> >
> > 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 <dchinner@xxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxxxxx
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
