File

util/dependencies.lua @ 12181:783056b4e448 0.11 0.11.12

util.xml: Do not allow doctypes, comments or processing instructions Yes. This is as bad as it sounds. CVE pending. In Prosody itself, this only affects mod_websocket, which uses util.xml to parse the <open/> frame, thus allowing unauthenticated remote DoS using Billion Laughs. However, third-party modules using util.xml may also be affected by this. This commit installs handlers which disallow the use of doctype declarations and processing instructions without any escape hatch. It, by default, also introduces such a handler for comments, however, there is a way to enable comments nontheless. This is because util.xml is used to parse human-facing data, where comments are generally a desirable feature, and also because comments are generally harmless.
author Jonas Schäfer <jonas@wielicki.name>
date Mon, 10 Jan 2022 18:23:54 +0100
parent 11140:e17b98feb0b7
child 11141:a5acd6354845
line wrap: on
line source

-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local function softreq(...) local ok, lib =  pcall(require, ...); if ok then return lib; else return nil, lib; end end

-- Required to be able to find packages installed with luarocks
if not softreq "luarocks.loader" then -- LuaRocks 2.x
	softreq "luarocks.require"; -- LuaRocks <1.x
end

local function missingdep(name, sources, msg)
	print("");
	print("**************************");
	print("Prosody was unable to find "..tostring(name));
	print("This package can be obtained in the following ways:");
	print("");
	local longest_platform = 0;
	for platform in pairs(sources) do
		longest_platform = math.max(longest_platform, #platform);
	end
	for platform, source in pairs(sources) do
		print("", platform..":"..(" "):rep(4+longest_platform-#platform)..source);
	end
	print("");
	print(msg or (name.." is required for Prosody to run, so we will now exit."));
	print("More help can be found on our website, at https://prosody.im/doc/depends");
	print("**************************");
	print("");
end

local function check_dependencies()
	if _VERSION < "Lua 5.1" then
		print "***********************************"
		print("Unsupported Lua version: ".._VERSION);
		print("At least Lua 5.1 is required.");
		print "***********************************"
		return false;
	end

	local fatal;

	local lxp = softreq "lxp"

	if not lxp then
		missingdep("luaexpat", {
				["Debian/Ubuntu"] = "sudo apt-get install lua-expat";
				["luarocks"] = "luarocks install luaexpat";
				["Source"] = "http://matthewwild.co.uk/projects/luaexpat/";
			});
		fatal = true;
	end

	local socket = softreq "socket"

	if not socket then
		missingdep("luasocket", {
				["Debian/Ubuntu"] = "sudo apt-get install lua-socket";
				["luarocks"] = "luarocks install luasocket";
				["Source"] = "http://www.tecgraf.puc-rio.br/~diego/professional/luasocket/";
			});
		fatal = true;
	elseif not socket.tcp4 then
		-- COMPAT LuaSocket before being IP-version agnostic
		socket.tcp4 = socket.tcp;
		socket.udp4 = socket.udp;
	end

	local lfs, err = softreq "lfs"
	if not lfs then
		missingdep("luafilesystem", {
			["luarocks"] = "luarocks install luafilesystem";
			["Debian/Ubuntu"] = "sudo apt-get install lua-filesystem";
			["Source"] = "http://www.keplerproject.org/luafilesystem/";
		});
		fatal = true;
	end

	local ssl = softreq "ssl"

	if not ssl then
		missingdep("LuaSec", {
				["Debian/Ubuntu"] = "sudo apt-get install lua-sec";
				["luarocks"] = "luarocks install luasec";
				["Source"] = "https://github.com/brunoos/luasec";
			}, "SSL/TLS support will not be available");
	end

	local bit = softreq"bit" or softreq"bit32";

	if not bit then
		missingdep("lua-bitops", {
			["Debian/Ubuntu"] = "sudo apt-get install lua-bitop";
			["luarocks"] = "luarocks install luabitop";
			["Source"] = "http://bitop.luajit.org/";
		}, "WebSocket support will not be available");
	end

	local encodings, err = softreq "util.encodings"
	if not encodings then
		if err:match("module '[^']*' not found") then
			missingdep("util.encodings", {
				["Windows"] = "Make sure you have encodings.dll from the Prosody distribution in util/";
				["GNU/Linux"] = "Run './configure' and 'make' in the Prosody source directory to build util/encodings.so";
			});
		else
			print "***********************************"
			print("util/encodings couldn't be loaded. Check that you have a recent version of libidn");
			print ""
			print("The full error was:");
			print(err)
			print "***********************************"
		end
		fatal = true;
	end

	local hashes, err = softreq "util.hashes"
	if not hashes then
		if err:match("module '[^']*' not found") then
			missingdep("util.hashes", {
				["Windows"] = "Make sure you have hashes.dll from the Prosody distribution in util/";
				["GNU/Linux"] = "Run './configure' and 'make' in the Prosody source directory to build util/hashes.so";
			});
		else
			print "***********************************"
			print("util/hashes couldn't be loaded. Check that you have a recent version of OpenSSL (libcrypto in particular)");
			print ""
			print("The full error was:");
			print(err)
			print "***********************************"
		end
		fatal = true;
	end

	return not fatal;
end

local function log_warnings()
	if _VERSION > "Lua 5.2" then
		prosody.log("warn", "Support for %s is experimental, please report any issues", _VERSION);
	end
	local ssl = softreq"ssl";
	if ssl then
		local major, minor, veryminor, patched = ssl._VERSION:match("(%d+)%.(%d+)%.?(%d*)(M?)");
		if not major or ((tonumber(major) == 0 and (tonumber(minor) or 0) <= 3 and (tonumber(veryminor) or 0) <= 2) and patched ~= "M") then
			prosody.log("error", "This version of LuaSec contains a known bug that causes disconnects, see https://prosody.im/doc/depends");
		end
	end
	local lxp = softreq"lxp";
	if lxp then
		if not pcall(lxp.new, { StartDoctypeDecl = false }) then
			prosody.log("error", "The version of LuaExpat on your system leaves Prosody "
				.."vulnerable to denial-of-service attacks. You should upgrade to "
				.."LuaExpat 1.3.0 or higher as soon as possible. See "
				.."https://prosody.im/doc/depends#luaexpat for more information.");
		end
		if not lxp.new({}).getcurrentbytecount then
			prosody.log("error", "The version of LuaExpat on your system does not support "
				.."stanza size limits, which may leave servers on untrusted "
				.."networks (e.g. the internet) vulnerable to denial-of-service "
				.."attacks. You should upgrade to LuaExpat 1.3.0 or higher as "
				.."soon as possible. See "
				.."https://prosody.im/doc/depends#luaexpat for more information.");
		end
	end
end

return {
	softreq = softreq;
	missingdep = missingdep;
	check_dependencies = check_dependencies;
	log_warnings = log_warnings;
};