diff options
Diffstat (limited to 'mesecons_luacontroller')
| -rw-r--r-- | mesecons_luacontroller/init.lua | 263 |
1 files changed, 216 insertions, 47 deletions
diff --git a/mesecons_luacontroller/init.lua b/mesecons_luacontroller/init.lua index 93703d8..325e16f 100644 --- a/mesecons_luacontroller/init.lua +++ b/mesecons_luacontroller/init.lua @@ -13,8 +13,10 @@ -- newport = merge_port_states(state1, state2): just does result = state1 or state2 for every port -- set_port(pos, rule, state): activates/deactivates the mesecons according to the port states -- set_port_states(pos, ports): Applies new port states to a Luacontroller at pos --- run(pos): runs the code in the controller at pos --- reset_meta(pos, code, errmsg): performs a software-reset, installs new code and prints error messages +-- run_inner(pos, code, event): runs code on the controller at pos and event +-- reset_formspec(pos, code, errmsg): installs new code and prints error messages, without resetting LCID +-- reset_meta(pos, code, errmsg): performs a software-reset, installs new code and prints error message +-- run(pos, event): a wrapper for run_inner which gets code & handles errors via reset_meta -- resetn(pos): performs a hardware reset, turns off all ports -- -- The Sandbox @@ -141,7 +143,7 @@ local function set_port_states(pos, ports) -- Solution / Workaround: -- Remember which output was turned off and ignore next "off" event. local meta = minetest.get_meta(pos) - local ign = minetest.deserialize(meta:get_string("ignore_offevents")) or {} + local ign = minetest.deserialize(meta:get_string("ignore_offevents"), true) or {} if ports.a and not vports.a and not mesecon.is_powered(pos, rules.a) then ign.A = true end if ports.b and not vports.b and not mesecon.is_powered(pos, rules.b) then ign.B = true end if ports.c and not vports.c and not mesecon.is_powered(pos, rules.c) then ign.C = true end @@ -183,7 +185,7 @@ end local function ignore_event(event, meta) if event.type ~= "off" then return false end - local ignore_offevents = minetest.deserialize(meta:get_string("ignore_offevents")) or {} + local ignore_offevents = minetest.deserialize(meta:get_string("ignore_offevents"), true) or {} if ignore_offevents[event.pin.name] then ignore_offevents[event.pin.name] = nil meta:set_string("ignore_offevents", minetest.serialize(ignore_offevents)) @@ -236,6 +238,7 @@ local function remove_functions(x) local seen = {} local function rfuncs(x) + if x == nil then return end if seen[x] then return end seen[x] = true if type(x) ~= "table" then return end @@ -259,37 +262,149 @@ local function remove_functions(x) return x end -local function get_interrupt(pos) +-- itbl: Flat table of functions to run after sandbox cleanup, used to prevent various security hazards +local function get_interrupt(pos, itbl, send_warning) -- iid = interrupt id local function interrupt(time, iid) + -- NOTE: This runs within string metatable sandbox, so don't *rely* on anything of the form (""):y + -- Hence the values get moved out. Should take less time than original, so totally compatible if type(time) ~= "number" then return end - local luac_id = minetest.get_meta(pos):get_int("luac_id") - mesecon.queue:add_action(pos, "lc_interrupt", {luac_id, iid}, time, iid, 1) + table.insert(itbl, function () + -- Outside string metatable sandbox, can safely run this now + local luac_id = minetest.get_meta(pos):get_int("luac_id") + -- Check if IID is dodgy, so you can't use interrupts to store an infinite amount of data. + -- Note that this is safe from alter-after-free because this code gets run after the sandbox has ended. + -- This runs outside of the timer and *shouldn't* harm perf. unless dodgy data is being sent in the first place + iid = remove_functions(iid) + local msg_ser = minetest.serialize(iid) + if #msg_ser <= mesecon.setting("luacontroller_interruptid_maxlen", 256) then + mesecon.queue:add_action(pos, "lc_interrupt", {luac_id, iid}, time, iid, 1) + else + send_warning("An interrupt ID was too large!") + end + end) end return interrupt end -local function get_digiline_send(pos) - if not digiline then return end +-- Given a message object passed to digiline_send, clean it up into a form +-- which is safe to transmit over the network and compute its "cost" (a very +-- rough estimate of its memory usage). +-- +-- The cleaning comprises the following: +-- 1. Functions (and userdata, though user scripts ought not to get hold of +-- those in the first place) are removed, because they break the model of +-- Digilines as a network that carries basic data, and they could exfiltrate +-- references to mutable objects from one Luacontroller to another, allowing +-- inappropriate high-bandwidth, no-wires communication. +-- 2. Tables are duplicated because, being mutable, they could otherwise be +-- modified after the send is complete in order to change what data arrives +-- at the recipient, perhaps in violation of the previous cleaning rule or +-- in violation of the message size limit. +-- +-- The cost indication is only approximate; it’s not a perfect measurement of +-- the number of bytes of memory used by the message object. +-- +-- Parameters: +-- msg -- the message to clean +-- back_references -- for internal use only; do not provide +-- +-- Returns: +-- 1. The cleaned object. +-- 2. The approximate cost of the object. +local function clean_and_weigh_digiline_message(msg, back_references) + local t = type(msg) + if t == "string" then + -- Strings are immutable so can be passed by reference, and cost their + -- length plus the size of the Lua object header (24 bytes on a 64-bit + -- platform) plus one byte for the NUL terminator. + return msg, #msg + 25 + elseif t == "number" then + -- Numbers are passed by value so need not be touched, and cost 8 bytes + -- as all numbers in Lua are doubles. + return msg, 8 + elseif t == "boolean" then + -- Booleans are passed by value so need not be touched, and cost 1 + -- byte. + return msg, 1 + elseif t == "table" then + -- Tables are duplicated. Check if this table has been seen before + -- (self-referential or shared table); if so, reuse the cleaned value + -- of the previous occurrence, maintaining table topology and avoiding + -- infinite recursion, and charge zero bytes for this as the object has + -- already been counted. + back_references = back_references or {} + local bref = back_references[msg] + if bref then + return bref, 0 + end + -- Construct a new table by cleaning all the keys and values and adding + -- up their costs, plus 8 bytes as a rough estimate of table overhead. + local cost = 8 + local ret = {} + back_references[msg] = ret + for k, v in pairs(msg) do + local k_cost, v_cost + k, k_cost = clean_and_weigh_digiline_message(k, back_references) + v, v_cost = clean_and_weigh_digiline_message(v, back_references) + if k ~= nil and v ~= nil then + -- Only include an element if its key and value are of legal + -- types. + ret[k] = v + end + -- If we only counted the cost of a table element when we actually + -- used it, we would be vulnerable to the following attack: + -- 1. Construct a huge table (too large to pass the cost limit). + -- 2. Insert it somewhere in a table, with a function as a key. + -- 3. Insert it somewhere in another table, with a number as a key. + -- 4. The first occurrence doesn’t pay the cost because functions + -- are stripped and therefore the element is dropped. + -- 5. The second occurrence doesn’t pay the cost because it’s in + -- back_references. + -- By counting the costs regardless of whether the objects will be + -- included, we avoid this attack; it may overestimate the cost of + -- some messages, but only those that won’t be delivered intact + -- anyway because they contain illegal object types. + cost = cost + k_cost + v_cost + end + return ret, cost + else + return nil, 0 + end +end + + +-- itbl: Flat table of functions to run after sandbox cleanup, used to prevent various security hazards +local function get_digiline_send(pos, itbl, send_warning) + if not minetest.global_exists("digilines") then return end + local chan_maxlen = mesecon.setting("luacontroller_digiline_channel_maxlen", 256) + local maxlen = mesecon.setting("luacontroller_digiline_maxlen", 50000) return function(channel, msg) + -- NOTE: This runs within string metatable sandbox, so don't *rely* on anything of the form (""):y + -- or via anything that could. -- Make sure channel is string, number or boolean - if (type(channel) ~= "string" and type(channel) ~= "number" and type(channel) ~= "boolean") then + if type(channel) == "string" then + if #channel > chan_maxlen then + send_warning("Channel string too long.") + return false + end + elseif (type(channel) ~= "string" and type(channel) ~= "number" and type(channel) ~= "boolean") then + send_warning("Channel must be string, number or boolean.") return false end - -- It is technically possible to send functions over the wire since - -- the high performance impact of stripping those from the data has - -- been decided to not be worth the added realism. - -- Make sure serialized version of the data is not insanely long to - -- prevent DoS-like attacks - local msg_ser = minetest.serialize(msg) - if #msg_ser > mesecon.setting("luacontroller_digiline_maxlen", 50000) then + local msg_cost + msg, msg_cost = clean_and_weigh_digiline_message(msg) + if msg == nil or msg_cost > maxlen then + send_warning("Message was too complex, or contained invalid data.") return false end - minetest.after(0, function() - digiline:receptor_send(pos, digiline.rules.default, channel, msg) + table.insert(itbl, function () + -- Runs outside of string metatable sandbox + local luac_id = minetest.get_meta(pos):get_int("luac_id") + mesecon.queue:add_action(pos, "lc_digiline_relay", {channel, luac_id, msg}) end) return true end @@ -297,11 +412,12 @@ end local safe_globals = { + -- Don't add pcall/xpcall unless willing to deal with the consequences (unless very careful, incredibly likely to allow killing server indirectly) "assert", "error", "ipairs", "next", "pairs", "select", "tonumber", "tostring", "type", "unpack", "_VERSION" } -local function create_environment(pos, mem, event) +local function create_environment(pos, mem, event, itbl, send_warning) -- Gather variables for the environment local vports = minetest.registered_nodes[minetest.get_node(pos).name].virtual_portstates local vports_copy = {} @@ -318,8 +434,8 @@ local function create_environment(pos, mem, event) heat = mesecon.get_heat(pos), heat_max = mesecon.setting("overheat_max", 20), print = safe_print, - interrupt = get_interrupt(pos), - digiline_send = get_digiline_send(pos), + interrupt = get_interrupt(pos, itbl, send_warning), + digiline_send = get_digiline_send(pos, itbl, send_warning), string = { byte = string.byte, char = string.char, @@ -407,10 +523,11 @@ local function create_sandbox(code, env) jit.off(f, true) end + local maxevents = mesecon.setting("luacontroller_maxevents", 10000) return function(...) + -- NOTE: This runs within string metatable sandbox, so the setting's been moved out for safety -- Use instruction counter to stop execution -- after luacontroller_maxevents - local maxevents = mesecon.setting("luacontroller_maxevents", 10000) debug.sethook(timeout, "", maxevents) local ok, ret = pcall(f, ...) debug.sethook() -- Clear hook @@ -421,7 +538,7 @@ end local function load_memory(meta) - return minetest.deserialize(meta:get_string("lc_memory")) or {} + return minetest.deserialize(meta:get_string("lc_memory"), true) or {} end @@ -438,26 +555,42 @@ local function save_memory(pos, meta, mem) end end - -local function run(pos, event) +-- Returns success (boolean), errmsg (string) +-- run (as opposed to run_inner) is responsible for setting up meta according to this output +local function run_inner(pos, code, event) local meta = minetest.get_meta(pos) - if overheat(pos) then return end - if ignore_event(event, meta) then return end + -- Note: These return success, presumably to avoid changing LC ID. + if overheat(pos) then return true, "" end + if ignore_event(event, meta) then return true, "" end -- Load code & mem from meta local mem = load_memory(meta) local code = meta:get_string("code") + -- 'Last warning' label. + local warning = "" + local function send_warning(str) + warning = "Warning: " .. str + end + -- Create environment - local env = create_environment(pos, mem, event) + local itbl = {} + local env = create_environment(pos, mem, event, itbl, send_warning) -- Create the sandbox and execute code local f, msg = create_sandbox(code, env) - if not f then return msg end + if not f then return false, msg end + -- Start string true sandboxing + local onetruestring = getmetatable("") + -- If a string sandbox is already up yet inconsistent, something is very wrong + assert(onetruestring.__index == string) + onetruestring.__index = env.string local success, msg = pcall(f) - if not success then return msg end + onetruestring.__index = string + -- End string true sandboxing + if not success then return false, msg end if type(env.port) ~= "table" then - return "Ports set are invalid." + return false, "Ports set are invalid." end -- Actually set the ports @@ -465,17 +598,18 @@ local function run(pos, event) -- Save memory. This may burn the luacontroller if a memory overflow occurs. save_memory(pos, meta, env.mem) -end -mesecon.queue:add_function("lc_interrupt", function (pos, luac_id, iid) - -- There is no luacontroller anymore / it has been reprogrammed / replaced / burnt - if (minetest.get_meta(pos):get_int("luac_id") ~= luac_id) then return end - if (minetest.registered_nodes[minetest.get_node(pos).name].is_burnt) then return end - run(pos, {type="interrupt", iid = iid}) -end) + -- Execute deferred tasks + for _, v in ipairs(itbl) do + local failure = v() + if failure then + return false, failure + end + end + return true, warning +end -local function reset_meta(pos, code, errmsg) - local meta = minetest.get_meta(pos) +local function reset_formspec(meta, code, errmsg) meta:set_string("code", code) code = minetest.formspec_escape(code or "") errmsg = minetest.formspec_escape(tostring(errmsg or "")) @@ -485,13 +619,50 @@ local function reset_meta(pos, code, errmsg) "image_button[4.75,8.75;2.5,1;jeija_luac_runbutton.png;program;]".. "image_button_exit[11.72,-0.25;0.425,0.4;jeija_close_window.png;exit;]".. "label[0.1,9;"..errmsg.."]") +end + +local function reset_meta(pos, code, errmsg) + local meta = minetest.get_meta(pos) + reset_formspec(meta, code, errmsg) meta:set_int("luac_id", math.random(1, 65535)) end +-- Wraps run_inner with LC-reset-on-error +local function run(pos, event) + local meta = minetest.get_meta(pos) + local code = meta:get_string("code") + local ok, errmsg = run_inner(pos, code, event) + if not ok then + reset_meta(pos, code, errmsg) + else + reset_formspec(meta, code, errmsg) + end + return ok, errmsg +end + local function reset(pos) set_port_states(pos, {a=false, b=false, c=false, d=false}) end +----------------------- +-- A.Queue callbacks -- +----------------------- + +mesecon.queue:add_function("lc_interrupt", function (pos, luac_id, iid) + -- There is no luacontroller anymore / it has been reprogrammed / replaced / burnt + if (minetest.get_meta(pos):get_int("luac_id") ~= luac_id) then return end + if (minetest.registered_nodes[minetest.get_node(pos).name].is_burnt) then return end + run(pos, {type="interrupt", iid = iid}) +end) + +mesecon.queue:add_function("lc_digiline_relay", function (pos, channel, luac_id, msg) + if not digiline then return end + -- This check is only really necessary because in case of server crash, old actions can be thrown into the future + if (minetest.get_meta(pos):get_int("luac_id") ~= luac_id) then return end + if (minetest.registered_nodes[minetest.get_node(pos).name].is_burnt) then return end + -- The actual work + digiline:receptor_send(pos, digiline.rules.default, channel, msg) +end) ----------------------- -- Node Registration -- @@ -518,6 +689,7 @@ local digiline = { receptor = {}, effector = { action = function(pos, node, channel, msg) + msg = clean_and_weigh_digiline_message(msg) run(pos, {type = "digiline", channel = channel, msg = msg}) end } @@ -531,12 +703,7 @@ end local function set_program(pos, code) reset(pos) reset_meta(pos, code) - local err = run(pos, {type="program"}) - if err then - reset_meta(pos, code, err) - return false, err - end - return true + return run(pos, {type="program"}) end local function on_receive_fields(pos, form_name, fields, sender) @@ -625,6 +792,7 @@ for d = 0, 1 do }, inventory_image = top, paramtype = "light", + is_ground_content = false, groups = groups, drop = BASENAME.."0000", sunlight_propagates = true, @@ -672,6 +840,7 @@ minetest.register_node(BASENAME .. "_burnt", { inventory_image = "jeija_luacontroller_burnt_top.png", is_burnt = true, paramtype = "light", + is_ground_content = false, groups = {dig_immediate=2, not_in_creative_inventory=1}, drop = BASENAME.."0000", sunlight_propagates = true, |