Chris G Demetriou <Chris_G_Demetriou@LAGAVULIN.PDL.CS.CMU.EDU> wrote:
 > The aperture 'driver' is _NOT_ a device driver.  Assuming you think
 > that the 'kernel security level' scheme is worth anything, it is
 > simply a security hole.  the only thing that it does is provide a
 > mechanism by which /dev/mem can be mapped read-write regardless of the
 > setting of the kernel security level.  This allows any process which
 > can write /dev/mem the ability to completely disable kernel
   security.

The 'driver' allows only one open at a time. Since the Xserver keeps
the 'device' open while running, someone running X (ou a machine
running xdm) has kernel security. 

 > There are other possiblities that could be better than the aperture
 > driver.  for instance, allow mappings of /dev/vga both in the normal
 > VGA video RAM area, and above however much RAM happens to be in the
 > machine.  It's not clear how safe _that_ is to me, however, for other
 > reasons. 

For now,  even mmap'ing of /dev/vga has been disabled so no one can
run X with kernel security. 




					Matthieu