File

core/s2smanager.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 12972:ead41e25ebc0
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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 hosts = prosody.hosts;
local pairs, setmetatable = pairs, setmetatable;

local logger_init = require "prosody.util.logger".init;
local sessionlib = require "prosody.util.session";

local log = logger_init("s2smanager");

local prosody = _G.prosody;
local incoming_s2s = {};
_G.incoming_s2s = incoming_s2s;
prosody.incoming_s2s = incoming_s2s;
local fire_event = prosody.events.fire_event;

local _ENV = nil;
-- luacheck: std none

local function new_incoming(conn)
	local host_session = sessionlib.new("s2sin");
	sessionlib.set_id(host_session);
	sessionlib.set_logger(host_session);
	sessionlib.set_conn(host_session, conn);
	host_session.direction = "incoming";
	host_session.incoming = true;
	host_session.hosts = {};
	incoming_s2s[host_session] = true;
	return host_session;
end

local function new_outgoing(from_host, to_host)
	local host_session = sessionlib.new("s2sout");
	sessionlib.set_id(host_session);
	sessionlib.set_logger(host_session);
	host_session.to_host = to_host;
	host_session.from_host = from_host;
	host_session.host = from_host;
	host_session.notopen = true;
	host_session.direction = "outgoing";
	host_session.outgoing = true;
	host_session.hosts = {};
	hosts[from_host].s2sout[to_host] = host_session;
	return host_session;
end

local resting_session = { -- Resting, not dead
		destroyed = true;
		type = "s2s_destroyed";
		direction = "destroyed";
		open_stream = function (session)
			session.log("debug", "Attempt to open stream on resting session");
		end;
		close = function (session)
			session.log("debug", "Attempt to close already-closed session");
		end;
		reset_stream = function (session)
			session.log("debug", "Attempt to reset stream of already-closed session");
		end;
		filter = function (type, data) return data; end; --luacheck: ignore 212/type
	}; resting_session.__index = resting_session;

local function retire_session(session, reason)
	local log = session.log or log; --luacheck: ignore 431/log
	for k in pairs(session) do
		if k ~= "log" and k ~= "id" and k ~= "conn" then
			session[k] = nil;
		end
	end

	session.destruction_reason = reason;

	function session.send(data) log("debug", "Discarding data sent to resting session: %s", data); end
	function session.data(data) log("debug", "Discarding data received from resting session: %s", data); end
	session.thread = { run = function (_, data) return session.data(data) end };
	session.sends2s = session.send;
	return setmetatable(session, resting_session);
end

local function destroy_session(session, reason, bounce_reason)
	if session.destroyed then return; end
	local log = session.log or log;
	log("debug", "Destroying %s session %s->%s%s%s", session.direction, session.from_host, session.to_host, reason and ": " or "", reason or "");

	if session.direction == "outgoing" then
		hosts[session.from_host].s2sout[session.to_host] = nil;
		session:bounce_sendq(bounce_reason or reason);
	elseif session.direction == "incoming" then
		if session.outgoing and hosts[session.to_host].s2sout[session.from_host] == session then
			hosts[session.to_host].s2sout[session.from_host] = nil;
		end
		incoming_s2s[session] = nil;
	end

	local event_data = { session = session, reason = reason };
	fire_event("s2s-destroyed", event_data);
	if session.type == "s2sout" then
		fire_event("s2sout-destroyed", event_data);
		if hosts[session.from_host] then
			hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
		end
	elseif session.type == "s2sin" then
		fire_event("s2sin-destroyed", event_data);
		if hosts[session.to_host] then
			hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
		end
	end

	retire_session(session, reason); -- Clean session until it is GC'd
	return true;
end

return {
	incoming_s2s = incoming_s2s;
	new_incoming = new_incoming;
	new_outgoing = new_outgoing;
	retire_session = retire_session;
	destroy_session = destroy_session;
};