File

plugins/mod_admin_socket.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 13592:34da8cc10b82
line wrap: on
line source

module:set_global();

local have_unix, unix = pcall(require, "socket.unix");

if have_unix and type(unix) == "function" then
	-- COMPAT #1717
	-- Before the introduction of datagram support, only the stream socket
	-- constructor was exported instead of a module table. Due to the lack of a
	-- proper release of LuaSocket, distros have settled on shipping either the
	-- last RC tag or some commit since then.
	-- Here we accommodate both variants.
	unix = { stream = unix };
end
if not have_unix or type(unix) ~= "table" then
	module:log_status("error", "LuaSocket unix socket support not available or incompatible, ensure it is up to date");
	return;
end

local server = require "prosody.net.server";

local adminstream = require "prosody.util.adminstream";
local st = require "prosody.util.stanza";

local socket_path = module:get_option_path("admin_socket", "prosody.sock", "data");

local sessions = module:shared("sessions");

local function fire_admin_event(session, stanza)
	local event_data = {
		origin = session, stanza = stanza;
	};
	local event_name;
	if stanza.attr.xmlns then
		event_name = "admin/"..stanza.attr.xmlns..":"..stanza.name;
	else
		event_name = "admin/"..stanza.name;
	end
	module:log("debug", "Firing %s", event_name);
	local ret = module:fire_event(event_name, event_data);
	if ret == nil then
		session.send(st.stanza("repl-result", { type = "error" }):text("No module handled this query. Is mod_admin_shell enabled?"));
	end
	return ret;
end

module:hook("server-stopping", function ()
	for _, session in pairs(sessions) do
		session:close("system-shutdown");
	end
	os.remove(socket_path);
end);

--- Unix domain socket management

local conn, sock;

local admin_server = adminstream.server(sessions, fire_admin_event);
local listeners = admin_server.listeners;

module:hook_object_event(admin_server.events, "disconnected", function (event)
	return module:fire_event("admin-disconnected", event);
end);

local function accept_connection()
	module:log("debug", "accepting...");
	local client = sock:accept();
	if not client then return; end
	server.wrapclient(client, "unix", 0, listeners, "*a");
end

function module.load()
	sock = unix.stream();
	sock:settimeout(0);
	os.remove(socket_path);
	local ok, err = sock:bind(socket_path);
	if not ok then
		module:log_status("error", "Unable to bind admin socket %s: %s", socket_path, err);
		return;
	end
	local ok, err = sock:listen();
	if not ok then
		module:log_status("error", "Unable to listen on admin socket %s: %s", socket_path, err);
		return;
	end
	if server.wrapserver then
		conn = server.wrapserver(sock, socket_path, 0, listeners);
	else
		conn = server.watchfd(sock:getfd(), accept_connection);
	end
end

function module.unload()
	if conn then
		conn:close();
	end
	if sock then
		sock:close();
	end
	os.remove(socket_path);
end