Re: sandboxing turns into pain in the ...

[Tomas <tomas@...>]

	Hi

> Lets consider sandboxing require, here is problems we will encounter:
	We faced that problem some time ago while redesigning CGILua.
Then we started VEnv, which solved some problems (and added others :-)

> 0. We can't do setfenv(require, sandbox), because it'll break global 
> require. So we need a way to clone functions.
	There is a way to dump a function but you lost the upvalues.

> 1. require uses registry to store loaded packages, so setfenv(require, 
> sandbox) won't protect our package.loaded
> 2. We need to sandbox loaders (as well as already loaded packages). Here 
> problems we will encounter:
> 2.1. CFunctions' globals are globals, LuaFunction's globals are environment 
> variables. (Have you ever heard about this malicious difference? 
> OP_GETGLOBAL?! Ha-Ha.). So we need to use different approaches.
	For that reason we gave up with VEnv and started another way:
Rings is the name of the library which creates new Lua States from within
Lua.  We're using it successfully on some production applications from some
months ago.

> 2.2. Callee does not inherit environment of caller. (Ah, you've already 
> sandboxed only caller? Now go and sandbox its children)
	I think this is another point.

	We're almost releasing the first official release of Rings.
Wait just a couple of days :-)

		Tomas