aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/mod_saslauth.lua
blob: 5ba53f21d37f454104982c2a9b5f2ff92d6f73f5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
-- 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 usermanager_get_sasl_handler = require "core.usermanager".get_sasl_handler;
local tostring = tostring;

local secure_auth_only = module:get_option_boolean("c2s_require_encryption", module:get_option_boolean("require_encryption", false));
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", "connection-timeout", "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);
		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);
		--log("debug", "AUTH: %s", text:gsub("[%z\001-\008\011\012\014-\031]", " "));
		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);
	log("debug", "sasl reply: %s", tostring(s));
	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 });
	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
	if text and condition then
		condition = condition .. ": " .. text;
	end
	module:log("info", "SASL EXTERNAL with %s failed: %s", session.to_host, condition);

	session.external_auth = "failed"
	session.external_auth_failure_reason = condition;
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);
	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 });
	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"]:getpeerfinished();
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;
		if origin.encrypted then
			-- check wether 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 socket = origin.conn:socket();
				local info = socket.info and socket:info();
				if info.protocol == "TLSv1.3" then
					log("debug", "Channel binding 'tls-unique' undefined in context of TLS 1.3");
				elseif socket.getpeerfinished and socket:getpeerfinished() then
					sasl_handler:add_cb_handler("tls-unique", tls_unique);
				end
				sasl_handler["userdata"] = {
					["tls-unique"] = socket;
				};
			end
		end
		local mechanisms = st.stanza("mechanisms", mechanisms_attr);
		local sasl_mechanisms = sasl_handler:mechanisms()
		for mechanism in pairs(sasl_mechanisms) do
			if disabled_mechanisms:contains(mechanism) then
				log("debug", "Not offering disabled mechanism %s", mechanism);
			elseif not origin.secure and insecure_mechanisms:contains(mechanism) then
				log("debug", "Not offering mechanism %s on insecure connection", mechanism);
			else
				log("debug", "Offering mechanism %s", mechanism);
				mechanisms:tag("mechanism"):text(mechanism):up();
			end
		end
		if mechanisms[1] then
			features:add_child(mechanisms);
		elseif not next(sasl_mechanisms) then
			log("warn", "No available SASL mechanisms, verify that the configured authentication module is working");
		else
			log("warn", "All available authentication mechanisms are either disabled or not suitable for an insecure connection");
		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);