Re: [PATCH 3/7] SLIM main patch

[Arjan van de Ven <arjan@infradead.org>]

On Wed, 2006-08-23 at 15:20 -0700, Kylene Jo Hall wrote:
> On Wed, 2006-08-23 at 16:41 -0400, Benjamin LaHaise wrote:
> > On Wed, Aug 23, 2006 at 01:35:56PM -0700, Kylene Jo Hall wrote:
> > > Example: The current process is running at the USER level and writing to
> > > a USER file in /home/user/.  The process then attempts to read an
> > > UNTRUSTED file.  The current process will become UNTRUSTED and the read
> > > allowed to proceed but first write access to all USER files is revoked
> > > including the ones it has open.
> > 
> > Don't threads share file tables?  What is preventing malicious code from 
> > starting another thread which continues writing to the file that the 
> > revoke attempt is made on?
> 
> Well if they do share file tables then revoking write access from the
> file in the file table will revoke access for all threads.  It looks
> like sharing or copying the file table is based on a flag to the clone
> call and we are looking into whether you could exploit that situation.


well there's many corner cases; like dup2(), or sending the fd over unix
domains (and having it pending there while the revoke happens, and later
accept it)....


-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/