sandbox.lua/sandbox.lua
Enrique García Cota 485a14697c feat(sandbox) explicitly drop support of quotas on LuaJIT
The solution we use in PUC Rio Lua (with debug.sethook) simply does not
work in LuaJIT.

* We have added a `sandbox.quota_supported` field to signal this feature
  (or lack of thereof)
* We explicitly return an error if `options.quota` is passed on a LuaJIT
  environment, in order to prevent LuaJIT users from believing that they
  are protected against infinite loops.
2021-01-05 19:50:12 +01:00

187 lines
5.8 KiB
Lua

local sandbox = {
_VERSION = "sandbox 0.5",
_DESCRIPTION = "A pure-lua solution for running untrusted Lua code.",
_URL = "https://github.com/kikito/sandbox.lua",
_LICENSE = [[
MIT LICENSE
Copyright (c) 2013 Enrique García Cota
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
]],
}
-- quotas don't work in LuaJIT since debug.sethook works differently there
local quota_supported = type(_G.jit) == "nil"
sandbox.quota_supported = quota_supported
-- PUC-Rio Lua 5.1 does not support deactivation of binary code
local mode_supported = _ENV or type(_G.jit) == "table"
sandbox.mode_supported = mode_supported
-- The base environment is merged with the given env option (or an empty table, if no env provided)
--
local BASE_ENV = {}
-- List of non-safe packages/functions:
--
-- * string.rep: can be used to allocate millions of bytes in 1 operation
-- * {set|get}metatable: can be used to modify the metatable of global objects (strings, integers)
-- * collectgarbage: can affect performance of other systems
-- * dofile: can access the server filesystem
-- * _G: It has access to everything. It can be mocked to other things though.
-- * load{file|string}: All unsafe because they can grant acces to global env
-- * raw{get|set|equal}: Potentially unsafe
-- * module|require|module: Can modify the host settings
-- * string.dump: Can display confidential server info (implementation of functions)
-- * string.rep: Can allocate millions of bytes in one go
-- * math.randomseed: Can affect the host sytem
-- * io.*, os.*: Most stuff there is non-save
-- Safe packages/functions below
([[
_VERSION assert error ipairs next pairs
pcall select tonumber tostring type unpack xpcall
coroutine.create coroutine.resume coroutine.running coroutine.status
coroutine.wrap coroutine.yield
math.abs math.acos math.asin math.atan math.atan2 math.ceil
math.cos math.cosh math.deg math.exp math.fmod math.floor
math.frexp math.huge math.ldexp math.log math.log10 math.max
math.min math.modf math.pi math.pow math.rad math.random
math.sin math.sinh math.sqrt math.tan math.tanh
os.clock os.difftime os.time
string.byte string.char string.find string.format string.gmatch
string.gsub string.len string.lower string.match string.reverse
string.sub string.upper
table.insert table.maxn table.remove table.sort
]]):gsub('%S+', function(id)
local module, method = id:match('([^%.]+)%.([^%.]+)')
if module then
BASE_ENV[module] = BASE_ENV[module] or {}
BASE_ENV[module][method] = _G[module][method]
else
BASE_ENV[id] = _G[id]
end
end)
local function protect_module(module, module_name)
return setmetatable({}, {
__index = module,
__newindex = function(_, attr_name, _)
error('Can not modify ' .. module_name .. '.' .. attr_name .. '. Protected by the sandbox.')
end
})
end
('coroutine math os string table'):gsub('%S+', function(module_name)
BASE_ENV[module_name] = protect_module(BASE_ENV[module_name], module_name)
end)
-- auxiliary functions/variables
local string_rep = string.rep
local function merge(dest, source)
for k,v in pairs(source) do
dest[k] = dest[k] or v
end
return dest
end
local function sethook(f, key, quota)
if type(debug) ~= 'table' or type(debug.sethook) ~= 'function' then return end
debug.sethook(f, key, quota)
end
local function cleanup()
sethook()
string.rep = string_rep
end
-- Public interface: sandbox.protect
function sandbox.protect(code, options)
options = options or {}
local quota = false
if options.quota and not quota_supported then
error("options.quota is not supported on this environment (usually LuaJIT). Please unset options.quota")
end
if options.quota ~= false then
quota = options.quota or 500000
end
local env = merge(options.env or {}, BASE_ENV)
env._G = env._G or env
assert(type(code) == 'string', "expected a string")
local f
if mode_supported then
f = assert(load(code, nil, options.mode, env))
else
if options.mode then
error("options.mode is not supported on this environment (usually PUC-Rio Lua 5.1). Please unset options.mode")
end
f = assert(loadstring(code))
setfenv(f, env)
end
return function(...)
if quota and quota_supported then
local timeout = function()
cleanup()
error('Quota exceeded: ' .. tostring(quota))
end
sethook(timeout, "", quota)
end
string.rep = nil
local t = table.pack(pcall(f, ...))
cleanup()
if not t[1] then error(t[2]) end
return table.unpack(t, 2, t.n)
end
end
-- Public interface: sandbox.run
function sandbox.run(code, options, ...)
return sandbox.protect(code, options)(...)
end
-- make sandbox(f) == sandbox.protect(f)
setmetatable(sandbox, {__call = function(_,code,o) return sandbox.protect(code,o) end})
return sandbox