sandbox - Lua Sandboxing - Eliminating Function Creation -

i've read on lua wiki / here / etc. on how sandbox lua code generally. haven't been able find disallows function creation. example, example here provides sample code as:

assert(run [[function f(x) return x^2 end; t={2}; t[1]=f(t[1])]]) 

and that's empty environment. want eliminate ability create function (the 1st part of code) - e.g., allow expressions. idea on how that? have in c somehow? in advance!

if want evaluate expressions only, try this:

function run(s) return loadstring("return "..s)() end 

(error handling omitted)

this simple solution prevent `attacks', not eliminate them because 1 can say

(function () f=function(x) print"hello" end end)() 

which defines new function named f.

your best bet use sandbox , not worry user environment, because it'll not your environment.