Re: BPF_MISC+BPF_COP and BPF_COPX

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Fri, Aug 09, 2013 at 09:34:25PM +0100, Mindaugas Rasiukevicius wrote:
> Steven,
> 
> Steven Bellovin <smb%cs.columbia.edu@localhost> wrote:
> > There's a one-word summary: *assurance*.  With the current design,
> > it's easy to *know* what can happen.  With a Turing-complete extension,
> > it isn't.
> 
> It is still easy and the concept itself is very simple.  I mentioned that
> this extension does not make byte-code Turing-complete and the rest is in
> your control.  Darren ignored it.

Yes, but since the extension makes the program no longer consist solely
of bytecode, it tends to give the impression that the program may now
be, in total, in a Turing-complete language.  It blurs the boundary
between the program and its interpreter, by allowing the bytecode to
directly call into the interpreter.  Or am I missing something?

I think what you want to do may be a good idea, in the end, but I do
think it calls for what others are requesting: a real problem statement
and an explanation of why the proposed solution is safer than it would
at first appear.

Thor