need type to carry kernel pointers to user space

[H. Peter Anvin]

Followup to:  <20000119130642.O42897 en sfgoth.com>
By author:    Mitchell Blank Jr <mitch en sfgoth.com>
In newsgroup: linux.dev.kernel
>
> Richard B. Johnson wrote:
> > > Recently, we had a discussion on the linux-atm list about the best approach
> > > for passing kernel pointers to user space, and back. The idea is as follows:
> > [SNIPPED...]
> > 
> > A pointer in user space is not a pointer in kernel space! Kernel data
> > is referenced by a discriptor, referenced as KERNEL_DS, which is not
> > accessible from user-mode privilege.
> 
> Yes, we (the linux-atm folks) of course know that.  The pointer is
> treated as an opaque descriptor in user space, just like a file
> descriptor is passed back from open().  We just need a type
> that is garaunteed to hold a kernel-mode pointer given weird cases
> like sparc64 (suppose mips64 and hppa64 will be similar when support
> for them arrives)
> 

Are you planning to dereference this pointer later?  Can we say
"security hole a mile wide"?

	  -hpa
-- 
<hpa en transmeta.com> at work, <hpa en zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."

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