Re: "cp -a" on a NFS mounted volume results in a zero length file

[Stephen Smalley <sds tycho nsa gov>]

On Sat, 2007-01-27 at 14:54 -0700, Paul Dickson wrote:
> On Sat, 27 Jan 2007 14:31:29 -0700, Paul Dickson wrote:
> 
> > I'm a bit behind on the devel kernels.  I'm currently running 2906
> > (2.6.20rc4)...
> > 
> > In my BZ (https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=219900) I
> > found (and got a fix for) the case were doing a "cp -a src dest" resulted
> > in the dest file being zero length.
> > 
> > Has this been apply to the most recent kernels (either devel or vanilla)?
> > Should I bring this up on LKML for 2.6.20?
> 
> The patch adds NFS support for SELinux xattrs.

No, it makes NFS lie about setting the SELinux attribute, while not
truly setting it at all (other than in-core).  So it is then lost when
the inode is evicted from memory or the system reboots.  The patch was
rejected upstream.  The problem lies in cp (coreutils), not NFS, IIUC -
it is making faulty assumptions about setxattr() always being supported
when getxattr() is.

-- 
Stephen Smalley
National Security Agency