Re: Multiple lua instances

[Rob Kendrick <rjek@...>]

On Tue, 19 Jan 2010 17:49:47 +0100
ingmar wirths <ingmania@googlemail.com> wrote:

> > The idea is that if a Lua function can't see another Lua function,
> > it can't call it, and it can't magic up a reference to it (unless
> > you expose the debug interface, of course. :)  
> 
> Allright, but since these restrictions are all implemented in lua, how
> can i enforce them, given that the user should be permitted to modify
> his ai? From the point of my limited knowledge so far, i guess the
> user could trivially escape from a sandbox, by just rewriting
> everything. Am i missing something here?

Because to /create/ the sandbox requires the calling of functions that
must be written in C and are included by default.  You simply don't put
those functions in your sand box.

Trivial example:

	function sandboxed_function()
		print "hello, world!"
	end

	setfenv(sandboxed_function, { print = print })

	sandboxed_function()

Try altering the body of sandboxed_function as much as you like, the
only thing it'll be able to call is print.

B.