File

net/server.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 13453:0b48cf880e79
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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 log(level, format, ...)
	print("net.server", level, format:format(...));
end

local default_backend = "select";
local server_type = default_backend;

if (prosody and prosody.config_loaded) then
	default_backend = "epoll";
	log = require"prosody.util.logger".init("net.server");
	server_type = require"prosody.core.configmanager".get("*", "network_backend") or default_backend;

	if require"prosody.core.configmanager".get("*", "use_libevent") then
		server_type = "event";
	end
elseif pcall(require, "prosody.util.poll") then
	server_type = "epoll";
end

if server_type == "event" then
	if not pcall(require, "luaevent.core") then
		log("error", "libevent not found, falling back to %s", default_backend);
		server_type = default_backend;
	end
end

local server;
local set_config;
if server_type == "event" then
	server = require "prosody.net.server_event";

	local defaults = {};
	for k,v in pairs(server.cfg) do
		defaults[k] = v;
	end
	function set_config(settings)
		local event_settings = {
			ACCEPT_DELAY = settings.accept_retry_interval;
			ACCEPT_QUEUE = settings.tcp_backlog;
			CLEAR_DELAY = settings.event_clear_interval;
			CONNECT_TIMEOUT = settings.connect_timeout;
			DEBUG = settings.debug;
			HANDSHAKE_TIMEOUT = settings.ssl_handshake_timeout;
			MAX_CONNECTIONS = settings.max_connections;
			MAX_HANDSHAKE_ATTEMPTS = settings.max_ssl_handshake_roundtrips;
			MAX_READ_LENGTH = settings.max_receive_buffer_size;
			MAX_SEND_LENGTH = settings.max_send_buffer_size;
			READ_TIMEOUT = settings.read_timeout;
			WRITE_TIMEOUT = settings.send_timeout;
		};

		for k,default in pairs(defaults) do
			server.cfg[k] = event_settings[k] or default;
		end
	end
elseif server_type == "select" then
	-- TODO Remove completely.
	log("warn", "select is deprecated, the new default is epoll. For more info see https://prosody.im/doc/network_backend");
	server = require "prosody.net.server_select";

	local defaults = {};
	for k,v in pairs(server.getsettings()) do
		defaults[k] = v;
	end
	function set_config(settings)
		local select_settings = {};
		for k,default in pairs(defaults) do
			select_settings[k] = settings[k] or default;
		end
		server.changesettings(select_settings);
	end
else
	server = require("prosody.net.server_"..server_type);
	set_config = server.set_config;
	if not server.get_backend then
		function server.get_backend()
			return server_type;
		end
	end
end

-- If server.hook_signal exists, replace signal.signal()
local has_signal, signal = pcall(require, "prosody.util.signal");
if has_signal then
	if server.hook_signal then
		function signal.signal(signal_id, handler)
			if type(signal_id) == "string" then
				signal_id = signal[signal_id:upper()];
			end
			if type(signal_id) ~= "number" then
				return false, "invalid-signal";
			end
			return server.hook_signal(signal_id, handler);
		end
	else
		server.hook_signal = signal.signal;
	end
else
	if not server.hook_signal then
		server.hook_signal = function()
			return false, "signal hooking not supported"
		end
	end
end

if prosody and set_config then
	local config_get = require "prosody.core.configmanager".get;
	local function load_config()
		local settings = config_get("*", "network_settings") or {};
		return set_config(settings);
	end
	load_config();
	prosody.events.add_handler("config-reloaded", load_config);
end

if prosody and server.tls_builder then
	local tls_builder = server.tls_builder;
	-- resolving the basedir here avoids util.sslconfig depending on
	-- prosody.paths.config
	function server.tls_builder()
		return tls_builder(prosody.paths.config or "")
	end
end

-- require "prosody.net.server" shall now forever return this,
-- ie. server_select or server_event as chosen above.
return server;