eap_server_tls_common.c revision 214734 
1/*
2 * EAP-TLS/PEAP/TTLS/FAST server common functions
3 * Copyright (c) 2004-2009, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15#include "includes.h"
16
17#include "common.h"
18#include "crypto/sha1.h"
19#include "crypto/tls.h"
20#include "eap_i.h"
21#include "eap_tls_common.h"
22
23
24static void eap_server_tls_free_in_buf(struct eap_ssl_data *data);
25
26
27int eap_server_tls_ssl_init(struct eap_sm *sm, struct eap_ssl_data *data,
28			    int verify_peer)
29{
30	data->eap = sm;
31	data->phase2 = sm->init_phase2;
32
33	data->conn = tls_connection_init(sm->ssl_ctx);
34	if (data->conn == NULL) {
35		wpa_printf(MSG_INFO, "SSL: Failed to initialize new TLS "
36			   "connection");
37		return -1;
38	}
39
40	if (tls_connection_set_verify(sm->ssl_ctx, data->conn, verify_peer)) {
41		wpa_printf(MSG_INFO, "SSL: Failed to configure verification "
42			   "of TLS peer certificate");
43		tls_connection_deinit(sm->ssl_ctx, data->conn);
44		data->conn = NULL;
45		return -1;
46	}
47
48	/* TODO: make this configurable */
49	data->tls_out_limit = 1398;
50	if (data->phase2) {
51		/* Limit the fragment size in the inner TLS authentication
52		 * since the outer authentication with EAP-PEAP does not yet
53		 * support fragmentation */
54		if (data->tls_out_limit > 100)
55			data->tls_out_limit -= 100;
56	}
57	return 0;
58}
59
60
61void eap_server_tls_ssl_deinit(struct eap_sm *sm, struct eap_ssl_data *data)
62{
63	tls_connection_deinit(sm->ssl_ctx, data->conn);
64	eap_server_tls_free_in_buf(data);
65	wpabuf_free(data->tls_out);
66	data->tls_out = NULL;
67}
68
69
70u8 * eap_server_tls_derive_key(struct eap_sm *sm, struct eap_ssl_data *data,
71			       char *label, size_t len)
72{
73	struct tls_keys keys;
74	u8 *rnd = NULL, *out;
75
76	out = os_malloc(len);
77	if (out == NULL)
78		return NULL;
79
80	if (tls_connection_prf(sm->ssl_ctx, data->conn, label, 0, out, len) ==
81	    0)
82		return out;
83
84	if (tls_connection_get_keys(sm->ssl_ctx, data->conn, &keys))
85		goto fail;
86
87	if (keys.client_random == NULL || keys.server_random == NULL ||
88	    keys.master_key == NULL)
89		goto fail;
90
91	rnd = os_malloc(keys.client_random_len + keys.server_random_len);
92	if (rnd == NULL)
93		goto fail;
94	os_memcpy(rnd, keys.client_random, keys.client_random_len);
95	os_memcpy(rnd + keys.client_random_len, keys.server_random,
96		  keys.server_random_len);
97
98	if (tls_prf(keys.master_key, keys.master_key_len,
99		    label, rnd, keys.client_random_len +
100		    keys.server_random_len, out, len))
101		goto fail;
102
103	os_free(rnd);
104	return out;
105
106fail:
107	os_free(out);
108	os_free(rnd);
109	return NULL;
110}
111
112
113struct wpabuf * eap_server_tls_build_msg(struct eap_ssl_data *data,
114					 int eap_type, int version, u8 id)
115{
116	struct wpabuf *req;
117	u8 flags;
118	size_t send_len, plen;
119
120	wpa_printf(MSG_DEBUG, "SSL: Generating Request");
121	if (data->tls_out == NULL) {
122		wpa_printf(MSG_ERROR, "SSL: tls_out NULL in %s", __func__);
123		return NULL;
124	}
125
126	flags = version;
127	send_len = wpabuf_len(data->tls_out) - data->tls_out_pos;
128	if (1 + send_len > data->tls_out_limit) {
129		send_len = data->tls_out_limit - 1;
130		flags |= EAP_TLS_FLAGS_MORE_FRAGMENTS;
131		if (data->tls_out_pos == 0) {
132			flags |= EAP_TLS_FLAGS_LENGTH_INCLUDED;
133			send_len -= 4;
134		}
135	}
136
137	plen = 1 + send_len;
138	if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
139		plen += 4;
140
141	req = eap_msg_alloc(EAP_VENDOR_IETF, eap_type, plen,
142			    EAP_CODE_REQUEST, id);
143	if (req == NULL)
144		return NULL;
145
146	wpabuf_put_u8(req, flags); /* Flags */
147	if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
148		wpabuf_put_be32(req, wpabuf_len(data->tls_out));
149
150	wpabuf_put_data(req, wpabuf_head_u8(data->tls_out) + data->tls_out_pos,
151			send_len);
152	data->tls_out_pos += send_len;
153
154	if (data->tls_out_pos == wpabuf_len(data->tls_out)) {
155		wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
156			   "(message sent completely)",
157			   (unsigned long) send_len);
158		wpabuf_free(data->tls_out);
159		data->tls_out = NULL;
160		data->tls_out_pos = 0;
161		data->state = MSG;
162	} else {
163		wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
164			   "(%lu more to send)", (unsigned long) send_len,
165			   (unsigned long) wpabuf_len(data->tls_out) -
166			   data->tls_out_pos);
167		data->state = WAIT_FRAG_ACK;
168	}
169
170	return req;
171}
172
173
174struct wpabuf * eap_server_tls_build_ack(u8 id, int eap_type, int version)
175{
176	struct wpabuf *req;
177
178	req = eap_msg_alloc(EAP_VENDOR_IETF, eap_type, 1, EAP_CODE_REQUEST,
179			    id);
180	if (req == NULL)
181		return NULL;
182	wpa_printf(MSG_DEBUG, "SSL: Building ACK");
183	wpabuf_put_u8(req, version); /* Flags */
184	return req;
185}
186
187
188static int eap_server_tls_process_cont(struct eap_ssl_data *data,
189				       const u8 *buf, size_t len)
190{
191	/* Process continuation of a pending message */
192	if (len > wpabuf_tailroom(data->tls_in)) {
193		wpa_printf(MSG_DEBUG, "SSL: Fragment overflow");
194		return -1;
195	}
196
197	wpabuf_put_data(data->tls_in, buf, len);
198	wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes, waiting for %lu "
199		   "bytes more", (unsigned long) len,
200		   (unsigned long) wpabuf_tailroom(data->tls_in));
201
202	return 0;
203}
204
205
206static int eap_server_tls_process_fragment(struct eap_ssl_data *data,
207					   u8 flags, u32 message_length,
208					   const u8 *buf, size_t len)
209{
210	/* Process a fragment that is not the last one of the message */
211	if (data->tls_in == NULL && !(flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)) {
212		wpa_printf(MSG_DEBUG, "SSL: No Message Length field in a "
213			   "fragmented packet");
214		return -1;
215	}
216
217	if (data->tls_in == NULL) {
218		/* First fragment of the message */
219
220		/* Limit length to avoid rogue peers from causing large
221		 * memory allocations. */
222		if (message_length > 65536) {
223			wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
224				   " over 64 kB)");
225			return -1;
226		}
227
228		data->tls_in = wpabuf_alloc(message_length);
229		if (data->tls_in == NULL) {
230			wpa_printf(MSG_DEBUG, "SSL: No memory for message");
231			return -1;
232		}
233		wpabuf_put_data(data->tls_in, buf, len);
234		wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes in first "
235			   "fragment, waiting for %lu bytes more",
236			   (unsigned long) len,
237			   (unsigned long) wpabuf_tailroom(data->tls_in));
238	}
239
240	return 0;
241}
242
243
244int eap_server_tls_phase1(struct eap_sm *sm, struct eap_ssl_data *data)
245{
246	if (data->tls_out) {
247		/* This should not happen.. */
248		wpa_printf(MSG_INFO, "SSL: pending tls_out data when "
249			   "processing new message");
250		wpabuf_free(data->tls_out);
251		WPA_ASSERT(data->tls_out == NULL);
252	}
253
254	data->tls_out = tls_connection_server_handshake(sm->ssl_ctx,
255							data->conn,
256							data->tls_in, NULL);
257	if (data->tls_out == NULL) {
258		wpa_printf(MSG_INFO, "SSL: TLS processing failed");
259		return -1;
260	}
261	if (tls_connection_get_failed(sm->ssl_ctx, data->conn)) {
262		/* TLS processing has failed - return error */
263		wpa_printf(MSG_DEBUG, "SSL: Failed - tls_out available to "
264			   "report error");
265		return -1;
266	}
267
268	return 0;
269}
270
271
272static int eap_server_tls_reassemble(struct eap_ssl_data *data, u8 flags,
273				     const u8 **pos, size_t *left)
274{
275	unsigned int tls_msg_len = 0;
276	const u8 *end = *pos + *left;
277
278	if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED) {
279		if (*left < 4) {
280			wpa_printf(MSG_INFO, "SSL: Short frame with TLS "
281				   "length");
282			return -1;
283		}
284		tls_msg_len = WPA_GET_BE32(*pos);
285		wpa_printf(MSG_DEBUG, "SSL: TLS Message Length: %d",
286			   tls_msg_len);
287		*pos += 4;
288		*left -= 4;
289	}
290
291	wpa_printf(MSG_DEBUG, "SSL: Received packet: Flags 0x%x "
292		   "Message Length %u", flags, tls_msg_len);
293
294	if (data->state == WAIT_FRAG_ACK) {
295		if (*left != 0) {
296			wpa_printf(MSG_DEBUG, "SSL: Unexpected payload in "
297				   "WAIT_FRAG_ACK state");
298			return -1;
299		}
300		wpa_printf(MSG_DEBUG, "SSL: Fragment acknowledged");
301		return 1;
302	}
303
304	if (data->tls_in &&
305	    eap_server_tls_process_cont(data, *pos, end - *pos) < 0)
306		return -1;
307
308	if (flags & EAP_TLS_FLAGS_MORE_FRAGMENTS) {
309		if (eap_server_tls_process_fragment(data, flags, tls_msg_len,
310						    *pos, end - *pos) < 0)
311			return -1;
312
313		data->state = FRAG_ACK;
314		return 1;
315	}
316
317	if (data->state == FRAG_ACK) {
318		wpa_printf(MSG_DEBUG, "SSL: All fragments received");
319		data->state = MSG;
320	}
321
322	if (data->tls_in == NULL) {
323		/* Wrap unfragmented messages as wpabuf without extra copy */
324		wpabuf_set(&data->tmpbuf, *pos, end - *pos);
325		data->tls_in = &data->tmpbuf;
326	}
327
328	return 0;
329}
330
331
332static void eap_server_tls_free_in_buf(struct eap_ssl_data *data)
333{
334	if (data->tls_in != &data->tmpbuf)
335		wpabuf_free(data->tls_in);
336	data->tls_in = NULL;
337}
338
339
340struct wpabuf * eap_server_tls_encrypt(struct eap_sm *sm,
341				       struct eap_ssl_data *data,
342				       const struct wpabuf *plain)
343{
344	struct wpabuf *buf;
345
346	buf = tls_connection_encrypt(sm->ssl_ctx, data->conn,
347				     plain);
348	if (buf == NULL) {
349		wpa_printf(MSG_INFO, "SSL: Failed to encrypt Phase 2 data");
350		return NULL;
351	}
352
353	return buf;
354}
355
356
357int eap_server_tls_process(struct eap_sm *sm, struct eap_ssl_data *data,
358			   struct wpabuf *respData, void *priv, int eap_type,
359			   int (*proc_version)(struct eap_sm *sm, void *priv,
360					       int peer_version),
361			   void (*proc_msg)(struct eap_sm *sm, void *priv,
362					    const struct wpabuf *respData))
363{
364	const u8 *pos;
365	u8 flags;
366	size_t left;
367	int ret, res = 0;
368
369	pos = eap_hdr_validate(EAP_VENDOR_IETF, eap_type, respData, &left);
370	if (pos == NULL || left < 1)
371		return 0; /* Should not happen - frame already validated */
372	flags = *pos++;
373	left--;
374	wpa_printf(MSG_DEBUG, "SSL: Received packet(len=%lu) - Flags 0x%02x",
375		   (unsigned long) wpabuf_len(respData), flags);
376
377	if (proc_version &&
378	    proc_version(sm, priv, flags & EAP_TLS_VERSION_MASK) < 0)
379		return -1;
380
381	ret = eap_server_tls_reassemble(data, flags, &pos, &left);
382	if (ret < 0) {
383		res = -1;
384		goto done;
385	} else if (ret == 1)
386		return 0;
387
388	if (proc_msg)
389		proc_msg(sm, priv, respData);
390
391	if (tls_connection_get_write_alerts(sm->ssl_ctx, data->conn) > 1) {
392		wpa_printf(MSG_INFO, "SSL: Locally detected fatal error in "
393			   "TLS processing");
394		res = -1;
395	}
396
397done:
398	eap_server_tls_free_in_buf(data);
399
400	return res;
401}
402