1 /*
2  * WPA Supplicant - RSN pre-authentication
3  * Copyright (c) 2003-2008, 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 "wpa.h"
19 #include "drivers/driver.h"
20 #include "eloop.h"
21 #include "l2_packet/l2_packet.h"
22 #include "eapol_supp/eapol_supp_sm.h"
23 #include "preauth.h"
24 #include "pmksa_cache.h"
25 #include "wpa_i.h"
26 #include "ieee802_11_defs.h"
27 
28 
29 #if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
30 
31 #define PMKID_CANDIDATE_PRIO_SCAN 1000
32 
33 
34 struct rsn_pmksa_candidate {
35 	struct rsn_pmksa_candidate *next;
36 	u8 bssid[ETH_ALEN];
37 	int priority;
38 };
39 
40 
41 /**
42  * pmksa_candidate_free - Free all entries in PMKSA candidate list
43  * @sm: Pointer to WPA state machine data from wpa_sm_init()
44  */
45 void pmksa_candidate_free(struct wpa_sm *sm)
46 {
47 	struct rsn_pmksa_candidate *entry, *prev;
48 
49 	if (sm == NULL)
50 		return;
51 
52 	entry = sm->pmksa_candidates;
53 	sm->pmksa_candidates = NULL;
54 	while (entry) {
55 		prev = entry;
56 		entry = entry->next;
57 		os_free(prev);
58 	}
59 }
60 
61 
62 static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
63 				const u8 *buf, size_t len)
64 {
65 	struct wpa_sm *sm = ctx;
66 
67 	wpa_printf(MSG_DEBUG, "RX pre-auth from " MACSTR, MAC2STR(src_addr));
68 	wpa_hexdump(MSG_MSGDUMP, "RX pre-auth", buf, len);
69 
70 	if (sm->preauth_eapol == NULL ||
71 	    is_zero_ether_addr(sm->preauth_bssid) ||
72 	    os_memcmp(sm->preauth_bssid, src_addr, ETH_ALEN) != 0) {
73 		wpa_printf(MSG_WARNING, "RSN pre-auth frame received from "
74 			   "unexpected source " MACSTR " - dropped",
75 			   MAC2STR(src_addr));
76 		return;
77 	}
78 
79 	eapol_sm_rx_eapol(sm->preauth_eapol, src_addr, buf, len);
80 }
81 
82 
83 static void rsn_preauth_eapol_cb(struct eapol_sm *eapol, int success,
84 				 void *ctx)
85 {
86 	struct wpa_sm *sm = ctx;
87 	u8 pmk[PMK_LEN];
88 
89 	if (success) {
90 		int res, pmk_len;
91 		pmk_len = PMK_LEN;
92 		res = eapol_sm_get_key(eapol, pmk, PMK_LEN);
93 		if (res) {
94 			/*
95 			 * EAP-LEAP is an exception from other EAP methods: it
96 			 * uses only 16-byte PMK.
97 			 */
98 			res = eapol_sm_get_key(eapol, pmk, 16);
99 			pmk_len = 16;
100 		}
101 		if (res == 0) {
102 			wpa_hexdump_key(MSG_DEBUG, "RSN: PMK from pre-auth",
103 					pmk, pmk_len);
104 			sm->pmk_len = pmk_len;
105 			pmksa_cache_add(sm->pmksa, pmk, pmk_len,
106 					sm->preauth_bssid, sm->own_addr,
107 					sm->network_ctx,
108 					WPA_KEY_MGMT_IEEE8021X);
109 		} else {
110 			wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: failed to get "
111 				"master session key from pre-auth EAPOL state "
112 				"machines");
113 			success = 0;
114 		}
115 	}
116 
117 	wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
118 		" %s", MAC2STR(sm->preauth_bssid),
119 		success ? "completed successfully" : "failed");
120 
121 	rsn_preauth_deinit(sm);
122 	rsn_preauth_candidate_process(sm);
123 }
124 
125 
126 static void rsn_preauth_timeout(void *eloop_ctx, void *timeout_ctx)
127 {
128 	struct wpa_sm *sm = eloop_ctx;
129 
130 	wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
131 		" timed out", MAC2STR(sm->preauth_bssid));
132 	rsn_preauth_deinit(sm);
133 	rsn_preauth_candidate_process(sm);
134 }
135 
136 
137 static int rsn_preauth_eapol_send(void *ctx, int type, const u8 *buf,
138 				  size_t len)
139 {
140 	struct wpa_sm *sm = ctx;
141 	u8 *msg;
142 	size_t msglen;
143 	int res;
144 
145 	/* TODO: could add l2_packet_sendmsg that allows fragments to avoid
146 	 * extra copy here */
147 
148 	if (sm->l2_preauth == NULL)
149 		return -1;
150 
151 	msg = wpa_sm_alloc_eapol(sm, type, buf, len, &msglen, NULL);
152 	if (msg == NULL)
153 		return -1;
154 
155 	wpa_hexdump(MSG_MSGDUMP, "TX EAPOL (preauth)", msg, msglen);
156 	res = l2_packet_send(sm->l2_preauth, sm->preauth_bssid,
157 			     ETH_P_RSN_PREAUTH, msg, msglen);
158 	os_free(msg);
159 	return res;
160 }
161 
162 
163 /**
164  * rsn_preauth_init - Start new RSN pre-authentication
165  * @sm: Pointer to WPA state machine data from wpa_sm_init()
166  * @dst: Authenticator address (BSSID) with which to preauthenticate
167  * @eap_conf: Current EAP configuration
168  * Returns: 0 on success, -1 on another pre-authentication is in progress,
169  * -2 on layer 2 packet initialization failure, -3 on EAPOL state machine
170  * initialization failure, -4 on memory allocation failure
171  *
172  * This function request an RSN pre-authentication with a given destination
173  * address. This is usually called for PMKSA candidates found from scan results
174  * or from driver reports. In addition, ctrl_iface PREAUTH command can trigger
175  * pre-authentication.
176  */
177 int rsn_preauth_init(struct wpa_sm *sm, const u8 *dst,
178 		     struct eap_peer_config *eap_conf)
179 {
180 	struct eapol_config eapol_conf;
181 	struct eapol_ctx *ctx;
182 
183 	if (sm->preauth_eapol)
184 		return -1;
185 
186 	wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: starting pre-authentication "
187 		"with " MACSTR, MAC2STR(dst));
188 
189 	sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
190 					ETH_P_RSN_PREAUTH,
191 					rsn_preauth_receive, sm, 0);
192 	if (sm->l2_preauth == NULL) {
193 		wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
194 			   "processing for pre-authentication");
195 		return -2;
196 	}
197 
198 	if (sm->bridge_ifname) {
199 		sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
200 						   sm->own_addr,
201 						   ETH_P_RSN_PREAUTH,
202 						   rsn_preauth_receive, sm, 0);
203 		if (sm->l2_preauth_br == NULL) {
204 			wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
205 				   "packet processing (bridge) for "
206 				   "pre-authentication");
207 			return -2;
208 		}
209 	}
210 
211 	ctx = os_zalloc(sizeof(*ctx));
212 	if (ctx == NULL) {
213 		wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
214 		return -4;
215 	}
216 	ctx->ctx = sm->ctx->ctx;
217 	ctx->msg_ctx = sm->ctx->ctx;
218 	ctx->preauth = 1;
219 	ctx->cb = rsn_preauth_eapol_cb;
220 	ctx->cb_ctx = sm;
221 	ctx->scard_ctx = sm->scard_ctx;
222 	ctx->eapol_send = rsn_preauth_eapol_send;
223 	ctx->eapol_send_ctx = sm;
224 	ctx->set_config_blob = sm->ctx->set_config_blob;
225 	ctx->get_config_blob = sm->ctx->get_config_blob;
226 
227 	sm->preauth_eapol = eapol_sm_init(ctx);
228 	if (sm->preauth_eapol == NULL) {
229 		os_free(ctx);
230 		wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
231 			   "state machines for pre-authentication");
232 		return -3;
233 	}
234 	os_memset(&eapol_conf, 0, sizeof(eapol_conf));
235 	eapol_conf.accept_802_1x_keys = 0;
236 	eapol_conf.required_keys = 0;
237 	eapol_conf.fast_reauth = sm->fast_reauth;
238 	eapol_conf.workaround = sm->eap_workaround;
239 	eapol_sm_notify_config(sm->preauth_eapol, eap_conf, &eapol_conf);
240 	/*
241 	 * Use a shorter startPeriod with preauthentication since the first
242 	 * preauth EAPOL-Start frame may end up being dropped due to race
243 	 * condition in the AP between the data receive and key configuration
244 	 * after the 4-Way Handshake.
245 	 */
246 	eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
247 	os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
248 
249 	eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
250 	/* 802.1X::portControl = Auto */
251 	eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
252 
253 	eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
254 			       rsn_preauth_timeout, sm, NULL);
255 
256 	return 0;
257 }
258 
259 
260 /**
261  * rsn_preauth_deinit - Abort RSN pre-authentication
262  * @sm: Pointer to WPA state machine data from wpa_sm_init()
263  *
264  * This function aborts the current RSN pre-authentication (if one is started)
265  * and frees resources allocated for it.
266  */
267 void rsn_preauth_deinit(struct wpa_sm *sm)
268 {
269 	if (sm == NULL || !sm->preauth_eapol)
270 		return;
271 
272 	eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
273 	eapol_sm_deinit(sm->preauth_eapol);
274 	sm->preauth_eapol = NULL;
275 	os_memset(sm->preauth_bssid, 0, ETH_ALEN);
276 
277 	l2_packet_deinit(sm->l2_preauth);
278 	sm->l2_preauth = NULL;
279 	if (sm->l2_preauth_br) {
280 		l2_packet_deinit(sm->l2_preauth_br);
281 		sm->l2_preauth_br = NULL;
282 	}
283 }
284 
285 
286 /**
287  * rsn_preauth_candidate_process - Process PMKSA candidates
288  * @sm: Pointer to WPA state machine data from wpa_sm_init()
289  *
290  * Go through the PMKSA candidates and start pre-authentication if a candidate
291  * without an existing PMKSA cache entry is found. Processed candidates will be
292  * removed from the list.
293  */
294 void rsn_preauth_candidate_process(struct wpa_sm *sm)
295 {
296 	struct rsn_pmksa_candidate *candidate;
297 
298 	if (sm->pmksa_candidates == NULL)
299 		return;
300 
301 	/* TODO: drop priority for old candidate entries */
302 
303 	wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
304 		"list");
305 	if (sm->preauth_eapol ||
306 	    sm->proto != WPA_PROTO_RSN ||
307 	    wpa_sm_get_state(sm) != WPA_COMPLETED ||
308 	    (sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X &&
309 	     sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X_SHA256)) {
310 		wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: not in suitable state "
311 			"for new pre-authentication");
312 		return; /* invalid state for new pre-auth */
313 	}
314 
315 	while (sm->pmksa_candidates) {
316 		struct rsn_pmksa_cache_entry *p = NULL;
317 		candidate = sm->pmksa_candidates;
318 		p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL);
319 		if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
320 		    (p == NULL || p->opportunistic)) {
321 			wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA "
322 				"candidate " MACSTR
323 				" selected for pre-authentication",
324 				MAC2STR(candidate->bssid));
325 			sm->pmksa_candidates = candidate->next;
326 			rsn_preauth_init(sm, candidate->bssid,
327 					 sm->eap_conf_ctx);
328 			os_free(candidate);
329 			return;
330 		}
331 		wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA candidate "
332 			MACSTR " does not need pre-authentication anymore",
333 			MAC2STR(candidate->bssid));
334 		/* Some drivers (e.g., NDIS) expect to get notified about the
335 		 * PMKIDs again, so report the existing data now. */
336 		if (p) {
337 			wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
338 		}
339 
340 		sm->pmksa_candidates = candidate->next;
341 		os_free(candidate);
342 	}
343 	wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
344 		"candidates");
345 }
346 
347 
348 /**
349  * pmksa_candidate_add - Add a new PMKSA candidate
350  * @sm: Pointer to WPA state machine data from wpa_sm_init()
351  * @bssid: BSSID (authenticator address) of the candidate
352  * @prio: Priority (the smaller number, the higher priority)
353  * @preauth: Whether the candidate AP advertises support for pre-authentication
354  *
355  * This function is used to add PMKSA candidates for RSN pre-authentication. It
356  * is called from scan result processing and from driver events for PMKSA
357  * candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
358  */
359 void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
360 			 int prio, int preauth)
361 {
362 	struct rsn_pmksa_candidate *cand, *prev, *pos;
363 
364 	if (sm->network_ctx && sm->proactive_key_caching)
365 		pmksa_cache_get_opportunistic(sm->pmksa, sm->network_ctx,
366 					      bssid);
367 
368 	if (!preauth) {
369 		wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
370 			   "preauth flag");
371 		return;
372 	}
373 
374 	/* If BSSID already on candidate list, update the priority of the old
375 	 * entry. Do not override priority based on normal scan results. */
376 	prev = NULL;
377 	cand = sm->pmksa_candidates;
378 	while (cand) {
379 		if (os_memcmp(cand->bssid, bssid, ETH_ALEN) == 0) {
380 			if (prev)
381 				prev->next = cand->next;
382 			else
383 				sm->pmksa_candidates = cand->next;
384 			break;
385 		}
386 		prev = cand;
387 		cand = cand->next;
388 	}
389 
390 	if (cand) {
391 		if (prio < PMKID_CANDIDATE_PRIO_SCAN)
392 			cand->priority = prio;
393 	} else {
394 		cand = os_zalloc(sizeof(*cand));
395 		if (cand == NULL)
396 			return;
397 		os_memcpy(cand->bssid, bssid, ETH_ALEN);
398 		cand->priority = prio;
399 	}
400 
401 	/* Add candidate to the list; order by increasing priority value. i.e.,
402 	 * highest priority (smallest value) first. */
403 	prev = NULL;
404 	pos = sm->pmksa_candidates;
405 	while (pos) {
406 		if (cand->priority <= pos->priority)
407 			break;
408 		prev = pos;
409 		pos = pos->next;
410 	}
411 	cand->next = pos;
412 	if (prev)
413 		prev->next = cand;
414 	else
415 		sm->pmksa_candidates = cand;
416 
417 	wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: added PMKSA cache "
418 		"candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
419 	rsn_preauth_candidate_process(sm);
420 }
421 
422 
423 /* TODO: schedule periodic scans if current AP supports preauth */
424 
425 /**
426  * rsn_preauth_scan_results - Process scan results to find PMKSA candidates
427  * @sm: Pointer to WPA state machine data from wpa_sm_init()
428  * @results: Scan results
429  *
430  * This functions goes through the scan results and adds all suitable APs
431  * (Authenticators) into PMKSA candidate list.
432  */
433 void rsn_preauth_scan_results(struct wpa_sm *sm,
434 			      struct wpa_scan_results *results)
435 {
436 	struct wpa_scan_res *r;
437 	struct wpa_ie_data ie;
438 	int i;
439 	struct rsn_pmksa_cache_entry *pmksa;
440 
441 	if (sm->ssid_len == 0)
442 		return;
443 
444 	/*
445 	 * TODO: is it ok to free all candidates? What about the entries
446 	 * received from EVENT_PMKID_CANDIDATE?
447 	 */
448 	pmksa_candidate_free(sm);
449 
450 	for (i = results->num - 1; i >= 0; i--) {
451 		const u8 *ssid, *rsn;
452 
453 		r = results->res[i];
454 
455 		ssid = wpa_scan_get_ie(r, WLAN_EID_SSID);
456 		if (ssid == NULL || ssid[1] != sm->ssid_len ||
457 		    os_memcmp(ssid + 2, sm->ssid, ssid[1]) != 0)
458 			continue;
459 
460 		if (os_memcmp(r->bssid, sm->bssid, ETH_ALEN) == 0)
461 			continue;
462 
463 		rsn = wpa_scan_get_ie(r, WLAN_EID_RSN);
464 		if (rsn == NULL || wpa_parse_wpa_ie(rsn, 2 + rsn[1], &ie))
465 			continue;
466 
467 		pmksa = pmksa_cache_get(sm->pmksa, r->bssid, NULL);
468 		if (pmksa &&
469 		    (!pmksa->opportunistic ||
470 		     !(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
471 			continue;
472 
473 		/*
474 		 * Give less priority to candidates found from normal
475 		 * scan results.
476 		 */
477 		pmksa_candidate_add(sm, r->bssid,
478 				    PMKID_CANDIDATE_PRIO_SCAN,
479 				    ie.capabilities & WPA_CAPABILITY_PREAUTH);
480 	}
481 }
482 
483 
484 #ifdef CONFIG_CTRL_IFACE
485 /**
486  * rsn_preauth_get_status - Get pre-authentication status
487  * @sm: Pointer to WPA state machine data from wpa_sm_init()
488  * @buf: Buffer for status information
489  * @buflen: Maximum buffer length
490  * @verbose: Whether to include verbose status information
491  * Returns: Number of bytes written to buf.
492  *
493  * Query WPA2 pre-authentication for status information. This function fills in
494  * a text area with current status information. If the buffer (buf) is not
495  * large enough, status information will be truncated to fit the buffer.
496  */
497 int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
498 			   int verbose)
499 {
500 	char *pos = buf, *end = buf + buflen;
501 	int res, ret;
502 
503 	if (sm->preauth_eapol) {
504 		ret = os_snprintf(pos, end - pos, "Pre-authentication "
505 				  "EAPOL state machines:\n");
506 		if (ret < 0 || ret >= end - pos)
507 			return pos - buf;
508 		pos += ret;
509 		res = eapol_sm_get_status(sm->preauth_eapol,
510 					  pos, end - pos, verbose);
511 		if (res >= 0)
512 			pos += res;
513 	}
514 
515 	return pos - buf;
516 }
517 #endif /* CONFIG_CTRL_IFACE */
518 
519 
520 /**
521  * rsn_preauth_in_progress - Verify whether pre-authentication is in progress
522  * @sm: Pointer to WPA state machine data from wpa_sm_init()
523  */
524 int rsn_preauth_in_progress(struct wpa_sm *sm)
525 {
526 	return sm->preauth_eapol != NULL;
527 }
528 
529 #endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
530