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Switched to a method proposed by @SoniEx2 to disallow function calls (#15).

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This commit is contained in:
Paul Kulchenko 2015-01-24 13:53:57 -08:00
parent 9ed094ba07
commit d78f212b71
2 changed files with 16 additions and 38 deletions
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44
src/serpent.lua
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@ -104,42 +104,16 @@ local function s(t, opts)
end
local function deserialize(data, opts)
local f, res = (loadstring or load)('return '..data)
if not f then f, res = (loadstring or load)(data) end
local env = (opts and opts.safe == false) and G
or setmetatable({}, {
__index = function(t,k) return t end,
__call = function(t,...) error("cannot call functions") end
})
local f, res = (loadstring or load)('return '..data, nil, nil, env)
if not f then f, res = (loadstring or load)(data, nil, nil, env) end
if not f then return f, res end
if opts and opts.safe == false then return pcall(f) end
local setfenv, getfenv = setfenv, getfenv
if not setfenv then -- Lua 5.2+
-- based on http://lua-users.org/lists/lua-l/2010-06/msg00314.html
-- this assumes f is a function
local function findenv(f)
local level = 1
repeat
local name, value = debug.getupvalue(f, level)
if name == '_ENV' then return level, value end
level = level + 1
until name == nil
return nil end
getfenv = function (f) return(select(2, findenv(f)) or _G) end
setfenv = function (f, t)
local level = findenv(f)
if level then debug.setupvalue(f, level, t) end
return f end
end
local env = {}
env._G = setmetatable(env, { __index = getfenv(f) })
f = setfenv(f, env)
local count, thread = 0, coroutine.running()
local h, m, c = debug.gethook(thread)
debug.sethook(function (e, l) count = count + 1
if count >= 3 then error("cannot call functions") end
end, "c")
local res = {pcall(f)}
count = 0 -- set again, otherwise it's tripped on the next sethook
debug.sethook(thread, h, m, c)
return (table.unpack or unpack)(res)
if setfenv then setfenv(f, env) end
return pcall(f)
end
local function merge(a, b) if b then for k,v in pairs(b) do a[k] = v end end; return a; end

10
t/test.lua
View File

@ -400,15 +400,19 @@ do
local print = _G.print
local ok, res = serpent.load("do print = error end")
assert(ok and _G.print == print and print ~= error,
"not allowing resetting `print` from serialized content (1/3): failed")
"not allowing resetting `print` from serialized content (1/4): failed")
local ok, res = serpent.load("do _G.print = error end")
assert(ok and _G.print == print and _G.print ~= error,
"not allowing resetting `print` from serialized content (2/3): failed")
"not allowing resetting `print` from serialized content (2/4): failed")
local ok, res = serpent.load("do _G._G.print = error end")
assert(ok and _G.print == print and print ~= error,
"not allowing resetting `print` from serialized content (3/3): failed")
"not allowing resetting `print` from serialized content (3/4): failed")
local ok, res = serpent.load("do _G = nil _G.print = error end")
assert(ok and _G.print == print and print ~= error,
"not allowing resetting `print` from serialized content (4/4): failed")
end
print("All tests passed.")