File

util/dependencies.lua @ 13801:a5d5fefb8b68 13.0

mod_tls: Enable Prosody's certificate checking for incoming s2s connections (fixes #1916) (thanks Damian, Zash) Various options in Prosody allow control over the behaviour of the certificate verification process For example, some deployments choose to allow falling back to traditional "dialback" authentication (XEP-0220), while others verify via DANE, hard-coded fingerprints, or other custom plugins. Implementing this flexibility requires us to override OpenSSL's default certificate verification, to allow Prosody to verify the certificate itself, apply custom policies and make decisions based on the outcome. To enable our custom logic, we have to suppress OpenSSL's default behaviour of aborting the connection with a TLS alert message. With LuaSec, this can be achieved by using the verifyext "lsec_continue" flag. We also need to use the lsec_ignore_purpose flag, because XMPP s2s uses server certificates as "client" certificates (for mutual TLS verification in outgoing s2s connections). Commit 99d2100d2918 moved these settings out of the defaults and into mod_s2s, because we only really need these changes for s2s, and they should be opt-in, rather than automatically applied to all TLS services we offer. That commit was incomplete, because it only added the flags for incoming direct TLS connections. StartTLS connections are handled by mod_tls, which was not applying the lsec_* flags. It previously worked because they were already in the defaults. This resulted in incoming s2s connections with "invalid" certificates being aborted early by OpenSSL, even if settings such as `s2s_secure_auth = false` or DANE were present in the config. Outgoing s2s connections inherit verify "none" from the defaults, which means OpenSSL will receive the cert but will not terminate the connection when it is deemed invalid. This means we don't need lsec_continue there, and we also don't need lsec_ignore_purpose (because the remote peer is a "server"). Wondering why we can't just use verify "none" for incoming s2s? It's because in that mode, OpenSSL won't request a certificate from the peer for incoming connections. Setting verify "peer" is how you ask OpenSSL to request a certificate from the client, but also what triggers its built-in verification.
author Matthew Wild <mwild1@gmail.com>
date Tue, 01 Apr 2025 17:26:56 +0100
parent 13114:025c38ee885d
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-- 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, err) -- luacheck: ignore err
	-- TODO print something about the underlying error, useful for debugging
	print("");
	print("**************************");
	print("Prosody was unable to find "..tostring(name));
	print("This package can be obtained in the following ways:");
	print("");
	for _, row in ipairs(sources) do
		print(string.format("%15s | %s", table.unpack(row)));
	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 5.2" then
		print "***********************************"
		print("Unsupported Lua version: ".._VERSION);
		print("At least Lua 5.2 is required.");
		print "***********************************"
		return false;
	end

	local fatal;

	local lxp, err = softreq "lxp"

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

	local socket, err = softreq "socket"

	if not socket then
		missingdep("luasocket", {
				{ "Debian/Ubuntu", "sudo apt install lua-socket" };
				{ "luarocks", "luarocks install luasocket" };
				{ "Source", "http://www.tecgraf.puc-rio.br/~diego/professional/luasocket/" };
			}, nil, err);
		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 install lua-filesystem" };
			{ "Source", "http://www.keplerproject.org/luafilesystem/" };
		}, nil, err);
		fatal = true;
	end

	local ssl, err = softreq "ssl"

	if not ssl then
		missingdep("LuaSec", {
				{ "Debian/Ubuntu", "sudo apt install lua-sec" };
				{ "luarocks", "luarocks install luasec" };
				{ "Source", "https://github.com/brunoos/luasec" };
			}, nil, err);
	end

	local bit, err = softreq"prosody.util.bitcompat";

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

	local unbound, err = softreq"lunbound"; -- luacheck: ignore 211/err
	if not unbound then
		missingdep("lua-unbound", {
				{ "Debian/Ubuntu", "sudo apt install lua-unbound" };
				{ "luarocks", "luarocks install luaunbound" };
				{ "Source", "https://www.zash.se/luaunbound.html" };
			}, "Old DNS resolver library will be used", err);
	else
		package.preload["prosody.net.adns"] = function ()
			local ub = require "prosody.net.unbound";
			return ub;
		end
	end

	local encodings, err = softreq "prosody.util.encodings"
	if not encodings then
		if err:match("module '[^']*' not found") then
			missingdep("prosody.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 "prosody.util.hashes"
	if not hashes then
		if err:match("module '[^']*' not found") then
			missingdep("prosody.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 5.4" then
		prosody.log("warn", "Support for %s is experimental, please report any issues", _VERSION);
	elseif _VERSION < "Lua 5.2" then
		prosody.log("warn", "%s support is deprecated, upgrade as soon as possible", _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;
};