File

plugins/mod_saslauth.lua @ 12591:494577d883ff

util.table: Fix inaccurate comment Probably a duplicate of the comment next to Lmove, recorded by mistake Lpack can probably be removed at some point in the near future once we are confident it is not used anywhere.
author Kim Alvefur <zash@zash.se>
date Mon, 11 Jul 2022 20:02:10 +0200
parent 12541:97af41d580f7
child 12594:29685403be32
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.
--
-- luacheck: ignore 431/log


local st = require "util.stanza";
local sm_bind_resource = require "core.sessionmanager".bind_resource;
local sm_make_authenticated = require "core.sessionmanager".make_authenticated;
local base64 = require "util.encodings".base64;
local set = require "util.set";
local errors = require "util.error";

local usermanager_get_sasl_handler = require "core.usermanager".get_sasl_handler;

local secure_auth_only = module:get_option_boolean("c2s_require_encryption", module:get_option_boolean("require_encryption", true));
local allow_unencrypted_plain_auth = module:get_option_boolean("allow_unencrypted_plain_auth", false)
local insecure_mechanisms = module:get_option_set("insecure_sasl_mechanisms", allow_unencrypted_plain_auth and {} or {"PLAIN", "LOGIN"});
local disabled_mechanisms = module:get_option_set("disable_sasl_mechanisms", { "DIGEST-MD5" });

local log = module._log;

local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';
local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';

local function build_reply(status, ret, err_msg)
	local reply = st.stanza(status, {xmlns = xmlns_sasl});
	if status == "failure" then
		reply:tag(ret):up();
		if err_msg then reply:tag("text"):text(err_msg); end
	elseif status == "challenge" or status == "success" then
		if ret == "" then
			reply:text("=")
		elseif ret then
			reply:text(base64.encode(ret));
		end
	else
		module:log("error", "Unknown sasl status: %s", status);
	end
	return reply;
end

local function handle_status(session, status, ret, err_msg)
	if not session.sasl_handler then
		return "failure", "temporary-auth-failure", "Connection gone";
	end
	if status == "failure" then
		module:fire_event("authentication-failure", { session = session, condition = ret, text = err_msg });
		session.sasl_handler = session.sasl_handler:clean_clone();
	elseif status == "success" then
		local ok, err = sm_make_authenticated(session, session.sasl_handler.username, session.sasl_handler.scope);
		if ok then
			module:fire_event("authentication-success", { session = session });
			session.sasl_handler = nil;
			session:reset_stream();
		else
			module:log("warn", "SASL succeeded but username was invalid");
			module:fire_event("authentication-failure", { session = session, condition = "not-authorized", text = err });
			session.sasl_handler = session.sasl_handler:clean_clone();
			return "failure", "not-authorized", "User authenticated successfully, but username was invalid";
		end
	end
	return status, ret, err_msg;
end

local function sasl_process_cdata(session, stanza)
	local text = stanza[1];
	if text then
		text = base64.decode(text);
		if not text then
			session.sasl_handler = nil;
			session.send(build_reply("failure", "incorrect-encoding"));
			return true;
		end
	end
	local status, ret, err_msg = session.sasl_handler:process(text);
	status, ret, err_msg = handle_status(session, status, ret, err_msg);
	local s = build_reply(status, ret, err_msg);
	session.send(s);
	return true;
end

module:hook_tag(xmlns_sasl, "success", function (session)
	if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
	module:log("debug", "SASL EXTERNAL with %s succeeded", session.to_host);
	session.external_auth = "succeeded"
	session:reset_stream();
	session:open_stream(session.from_host, session.to_host);

	module:fire_event("s2s-authenticated", { session = session, host = session.to_host, mechanism = "EXTERNAL" });
	return true;
end)

module:hook_tag(xmlns_sasl, "failure", function (session, stanza)
	if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end

	local text = stanza:get_child_text("text");
	local condition = "unknown-condition";
	for child in stanza:childtags() do
		if child.name ~= "text" then
			condition = child.name;
			break;
		end
	end
	local err = errors.new({
			-- TODO type = what?
			text = text,
			condition = condition,
		}, {
			session = session,
			stanza = stanza,
		});

	module:log("info", "SASL EXTERNAL with %s failed: %s", session.to_host, err);

	session.external_auth = "failed"
	session.external_auth_failure_reason = err;
end, 500)

module:hook_tag(xmlns_sasl, "failure", function (session, stanza) -- luacheck: ignore 212/stanza
	session.log("debug", "No fallback from SASL EXTERNAL failure, giving up");
	session:close(nil, session.external_auth_failure_reason, errors.new({
				type = "wait", condition = "remote-server-timeout",
				text = "Could not authenticate to remote server",
		}, { session = session, sasl_failure = session.external_auth_failure_reason, }));
	return true;
end, 90)

module:hook_tag("http://etherx.jabber.org/streams", "features", function (session, stanza)
	if session.type ~= "s2sout_unauthed" or not session.secure then return; end

	local mechanisms = stanza:get_child("mechanisms", xmlns_sasl)
	if mechanisms then
		for mech in mechanisms:childtags() do
			if mech[1] == "EXTERNAL" then
				module:log("debug", "Initiating SASL EXTERNAL with %s", session.to_host);
				local reply = st.stanza("auth", {xmlns = xmlns_sasl, mechanism = "EXTERNAL"});
				reply:text(base64.encode(session.from_host))
				session.sends2s(reply)
				session.external_auth = "attempting"
				return true
			end
		end
	end
end, 150);

local function s2s_external_auth(session, stanza)
	if session.external_auth ~= "offered" then return end -- Unexpected request

	local mechanism = stanza.attr.mechanism;

	if mechanism ~= "EXTERNAL" then
		session.sends2s(build_reply("failure", "invalid-mechanism"));
		return true;
	end

	if not session.secure then
		session.sends2s(build_reply("failure", "encryption-required"));
		return true;
	end

	local text = stanza[1];
	if not text then
		session.sends2s(build_reply("failure", "malformed-request"));
		return true;
	end

	text = base64.decode(text);
	if not text then
		session.sends2s(build_reply("failure", "incorrect-encoding"));
		return true;
	end

	-- The text value is either "" or equals session.from_host
	if not ( text == "" or text == session.from_host ) then
		session.sends2s(build_reply("failure", "invalid-authzid"));
		return true;
	end

	-- We've already verified the external cert identity before offering EXTERNAL
	if session.cert_chain_status ~= "valid" or session.cert_identity_status ~= "valid" then
		session.sends2s(build_reply("failure", "not-authorized"));
		session:close();
		return true;
	end

	-- Success!
	session.external_auth = "succeeded";
	session.sends2s(build_reply("success"));
	module:log("info", "Accepting SASL EXTERNAL identity from %s", session.from_host);
	module:fire_event("s2s-authenticated", { session = session, host = session.from_host, mechanism = mechanism });
	session:reset_stream();
	return true;
end

module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:auth", function(event)
	local session, stanza = event.origin, event.stanza;
	if session.type == "s2sin_unauthed" then
		return s2s_external_auth(session, stanza)
	end

	if session.type ~= "c2s_unauthed" or module:get_host_type() ~= "local" then return; end

	if session.sasl_handler and session.sasl_handler.selected then
		session.sasl_handler = nil; -- allow starting a new SASL negotiation before completing an old one
	end
	if not session.sasl_handler then
		session.sasl_handler = usermanager_get_sasl_handler(module.host, session);
	end
	local mechanism = stanza.attr.mechanism;
	if not session.secure and (secure_auth_only or insecure_mechanisms:contains(mechanism)) then
		session.send(build_reply("failure", "encryption-required"));
		return true;
	elseif disabled_mechanisms:contains(mechanism) then
		session.send(build_reply("failure", "invalid-mechanism"));
		return true;
	end
	local valid_mechanism = session.sasl_handler:select(mechanism);
	if not valid_mechanism then
		session.send(build_reply("failure", "invalid-mechanism"));
		return true;
	end
	return sasl_process_cdata(session, stanza);
end);
module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:response", function(event)
	local session = event.origin;
	if not(session.sasl_handler and session.sasl_handler.selected) then
		session.send(build_reply("failure", "not-authorized", "Out of order SASL element"));
		return true;
	end
	return sasl_process_cdata(session, event.stanza);
end);
module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:abort", function(event)
	local session = event.origin;
	session.sasl_handler = nil;
	session.send(build_reply("failure", "aborted"));
	return true;
end);

local function tls_unique(self)
	return self.userdata["tls-unique"]:ssl_peerfinished();
end

local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };
local bind_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-bind' };
local xmpp_session_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-session' };
module:hook("stream-features", function(event)
	local origin, features = event.origin, event.features;
	local log = origin.log or log;
	if not origin.username then
		if secure_auth_only and not origin.secure then
			log("debug", "Not offering authentication on insecure connection");
			return;
		end
		local sasl_handler = usermanager_get_sasl_handler(module.host, origin)
		origin.sasl_handler = sasl_handler;
		local channel_bindings = set.new()
		if origin.encrypted then
			-- check whether LuaSec has the nifty binding to the function needed for tls-unique
			-- FIXME: would be nice to have this check only once and not for every socket
			if sasl_handler.add_cb_handler then
				local info = origin.conn:ssl_info();
				if info and info.protocol == "TLSv1.3" then
					log("debug", "Channel binding 'tls-unique' undefined in context of TLS 1.3");
				elseif origin.conn.ssl_peerfinished and origin.conn:ssl_peerfinished() then
					log("debug", "Channel binding 'tls-unique' supported");
					sasl_handler:add_cb_handler("tls-unique", tls_unique);
					channel_bindings:add("tls-unique");
				else
					log("debug", "Channel binding 'tls-unique' not supported (by LuaSec?)");
				end
				sasl_handler["userdata"] = {
					["tls-unique"] = origin.conn;
				};
			else
				log("debug", "Channel binding not supported by SASL handler");
			end
		end
		local mechanisms = st.stanza("mechanisms", mechanisms_attr);
		local sasl_mechanisms = sasl_handler:mechanisms()
		local available_mechanisms = set.new();
		for mechanism in pairs(sasl_mechanisms) do
			available_mechanisms:add(mechanism);
		end
		log("debug", "SASL mechanisms supported by handler: %s", available_mechanisms);

		local usable_mechanisms = available_mechanisms - disabled_mechanisms;

		local available_disabled = set.intersection(available_mechanisms, disabled_mechanisms);
		if not available_disabled:empty() then
			log("debug", "Not offering disabled mechanisms: %s", available_disabled);
		end

		local available_insecure = set.intersection(available_mechanisms, insecure_mechanisms);
		if not origin.secure and not available_insecure:empty() then
			log("debug", "Session is not secure, not offering insecure mechanisms: %s", available_insecure);
			usable_mechanisms = usable_mechanisms - insecure_mechanisms;
		end

		if not usable_mechanisms:empty() then
			log("debug", "Offering usable mechanisms: %s", usable_mechanisms);
			for mechanism in usable_mechanisms do
				mechanisms:tag("mechanism"):text(mechanism):up();
			end
			if not channel_bindings:empty() then
				-- XXX XEP-0440 is Experimental
				mechanisms:tag("sasl-channel-binding", {xmlns='urn:xmpp:sasl-cb:0'})
				for channel_binding in channel_bindings do
					mechanisms:tag("channel-binding", {type=channel_binding}):up()
				end
				mechanisms:up();
			end
			features:add_child(mechanisms);
			return;
		end

		local authmod = module:get_option_string("authentication", "internal_hashed");
		if available_mechanisms:empty() then
			log("warn", "No available SASL mechanisms, verify that the configured authentication module '%s' is loaded and configured correctly", authmod);
			return;
		end

		if not origin.secure and not available_insecure:empty() then
			if not available_disabled:empty() then
				log("warn", "All SASL mechanisms provided by authentication module '%s' are forbidden on insecure connections (%s) or disabled (%s)",
					authmod, available_insecure, available_disabled);
			else
				log("warn", "All SASL mechanisms provided by authentication module '%s' are forbidden on insecure connections (%s)",
					authmod, available_insecure);
			end
		elseif not available_disabled:empty() then
			log("warn", "All SASL mechanisms provided by authentication module '%s' are disabled (%s)",
				authmod, available_disabled);
		end

	else
		features:tag("bind", bind_attr):tag("required"):up():up();
		features:tag("session", xmpp_session_attr):tag("optional"):up():up();
	end
end);

module:hook("s2s-stream-features", function(event)
	local origin, features = event.origin, event.features;
	if origin.secure and origin.type == "s2sin_unauthed" then
		-- Offer EXTERNAL only if both chain and identity is valid.
		if origin.cert_chain_status == "valid" and origin.cert_identity_status == "valid" then
			module:log("debug", "Offering SASL EXTERNAL");
			origin.external_auth = "offered"
			features:tag("mechanisms", { xmlns = xmlns_sasl })
				:tag("mechanism"):text("EXTERNAL")
			:up():up();
		end
	end
end);

module:hook("stanza/iq/urn:ietf:params:xml:ns:xmpp-bind:bind", function(event)
	local origin, stanza = event.origin, event.stanza;
	local resource;
	if stanza.attr.type == "set" then
		local bind = stanza.tags[1];
		resource = bind:get_child("resource");
		resource = resource and #resource.tags == 0 and resource[1] or nil;
	end
	local success, err_type, err, err_msg = sm_bind_resource(origin, resource);
	if success then
		origin.send(st.reply(stanza)
			:tag("bind", { xmlns = xmlns_bind })
			:tag("jid"):text(origin.full_jid));
		origin.log("debug", "Resource bound: %s", origin.full_jid);
	else
		origin.send(st.error_reply(stanza, err_type, err, err_msg));
		origin.log("debug", "Resource bind failed: %s", err_msg or err);
	end
	return true;
end);

local function handle_legacy_session(event)
	event.origin.send(st.reply(event.stanza));
	return true;
end

module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);
module:hook("iq/host/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);