1 /*
2 * WPA Supplicant - Mesh RSN routines
3 * Copyright (c) 2013-2014, cozybit, Inc. All rights reserved.
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "utils/includes.h"
10
11 #include "utils/common.h"
12 #include "utils/eloop.h"
13 #include "crypto/sha256.h"
14 #include "crypto/random.h"
15 #include "crypto/aes.h"
16 #include "crypto/aes_siv.h"
17 #include "rsn_supp/wpa.h"
18 #include "ap/hostapd.h"
19 #include "ap/wpa_auth.h"
20 #include "ap/sta_info.h"
21 #include "ap/ieee802_11.h"
22 #include "wpa_supplicant_i.h"
23 #include "driver_i.h"
24 #include "wpas_glue.h"
25 #include "mesh_mpm.h"
26 #include "mesh_rsn.h"
27
28 #define MESH_AUTH_TIMEOUT 10
29 #define MESH_AUTH_RETRY 3
30
mesh_auth_timer(void * eloop_ctx,void * user_data)31 void mesh_auth_timer(void *eloop_ctx, void *user_data)
32 {
33 struct wpa_supplicant *wpa_s = eloop_ctx;
34 struct sta_info *sta = user_data;
35 struct hostapd_data *hapd;
36
37 if (sta->sae->state != SAE_ACCEPTED) {
38 wpa_printf(MSG_DEBUG, "AUTH: Re-authenticate with " MACSTR
39 " (attempt %d) ",
40 MAC2STR(sta->addr), sta->sae_auth_retry);
41 wpa_msg(wpa_s, MSG_INFO, MESH_SAE_AUTH_FAILURE "addr=" MACSTR,
42 MAC2STR(sta->addr));
43 if (sta->sae_auth_retry < MESH_AUTH_RETRY) {
44 mesh_rsn_auth_sae_sta(wpa_s, sta);
45 } else {
46 hapd = wpa_s->ifmsh->bss[0];
47
48 if (sta->sae_auth_retry > MESH_AUTH_RETRY) {
49 ap_free_sta(hapd, sta);
50 return;
51 }
52
53 /* block the STA if exceeded the number of attempts */
54 wpa_mesh_set_plink_state(wpa_s, sta, PLINK_BLOCKED);
55 sta->sae->state = SAE_NOTHING;
56 wpa_msg(wpa_s, MSG_INFO, MESH_SAE_AUTH_BLOCKED "addr="
57 MACSTR " duration=%d",
58 MAC2STR(sta->addr),
59 hapd->conf->ap_max_inactivity);
60 }
61 sta->sae_auth_retry++;
62 }
63 }
64
65
auth_logger(void * ctx,const u8 * addr,logger_level level,const char * txt)66 static void auth_logger(void *ctx, const u8 *addr, logger_level level,
67 const char *txt)
68 {
69 if (addr)
70 wpa_printf(MSG_DEBUG, "AUTH: " MACSTR " - %s",
71 MAC2STR(addr), txt);
72 else
73 wpa_printf(MSG_DEBUG, "AUTH: %s", txt);
74 }
75
76
auth_get_psk(void * ctx,const u8 * addr,const u8 * p2p_dev_addr,const u8 * prev_psk,size_t * psk_len)77 static const u8 *auth_get_psk(void *ctx, const u8 *addr,
78 const u8 *p2p_dev_addr, const u8 *prev_psk,
79 size_t *psk_len)
80 {
81 struct mesh_rsn *mesh_rsn = ctx;
82 struct hostapd_data *hapd = mesh_rsn->wpa_s->ifmsh->bss[0];
83 struct sta_info *sta = ap_get_sta(hapd, addr);
84
85 if (psk_len)
86 *psk_len = PMK_LEN;
87 wpa_printf(MSG_DEBUG, "AUTH: %s (addr=" MACSTR " prev_psk=%p)",
88 __func__, MAC2STR(addr), prev_psk);
89
90 if (sta && sta->auth_alg == WLAN_AUTH_SAE) {
91 if (!sta->sae || prev_psk)
92 return NULL;
93 return sta->sae->pmk;
94 }
95
96 return NULL;
97 }
98
99
auth_set_key(void * ctx,int vlan_id,enum wpa_alg alg,const u8 * addr,int idx,u8 * key,size_t key_len)100 static int auth_set_key(void *ctx, int vlan_id, enum wpa_alg alg,
101 const u8 *addr, int idx, u8 *key, size_t key_len)
102 {
103 struct mesh_rsn *mesh_rsn = ctx;
104 u8 seq[6];
105
106 os_memset(seq, 0, sizeof(seq));
107
108 if (addr) {
109 wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d addr=" MACSTR
110 " key_idx=%d)",
111 __func__, alg, MAC2STR(addr), idx);
112 } else {
113 wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d key_idx=%d)",
114 __func__, alg, idx);
115 }
116 wpa_hexdump_key(MSG_DEBUG, "AUTH: set_key - key", key, key_len);
117
118 return wpa_drv_set_key(mesh_rsn->wpa_s, alg, addr, idx,
119 1, seq, 6, key, key_len);
120 }
121
122
auth_start_ampe(void * ctx,const u8 * addr)123 static int auth_start_ampe(void *ctx, const u8 *addr)
124 {
125 struct mesh_rsn *mesh_rsn = ctx;
126 struct hostapd_data *hapd;
127 struct sta_info *sta;
128
129 if (mesh_rsn->wpa_s->current_ssid->mode != WPAS_MODE_MESH)
130 return -1;
131
132 hapd = mesh_rsn->wpa_s->ifmsh->bss[0];
133 sta = ap_get_sta(hapd, addr);
134 if (sta)
135 eloop_cancel_timeout(mesh_auth_timer, mesh_rsn->wpa_s, sta);
136
137 mesh_mpm_auth_peer(mesh_rsn->wpa_s, addr);
138 return 0;
139 }
140
141
__mesh_rsn_auth_init(struct mesh_rsn * rsn,const u8 * addr,enum mfp_options ieee80211w)142 static int __mesh_rsn_auth_init(struct mesh_rsn *rsn, const u8 *addr,
143 enum mfp_options ieee80211w)
144 {
145 struct wpa_auth_config conf;
146 static const struct wpa_auth_callbacks cb = {
147 .logger = auth_logger,
148 .get_psk = auth_get_psk,
149 .set_key = auth_set_key,
150 .start_ampe = auth_start_ampe,
151 };
152 u8 seq[6] = {};
153
154 wpa_printf(MSG_DEBUG, "AUTH: Initializing group state machine");
155
156 os_memset(&conf, 0, sizeof(conf));
157 conf.wpa = WPA_PROTO_RSN;
158 conf.wpa_key_mgmt = WPA_KEY_MGMT_SAE;
159 conf.wpa_pairwise = rsn->pairwise_cipher;
160 conf.rsn_pairwise = rsn->pairwise_cipher;
161 conf.wpa_group = rsn->group_cipher;
162 conf.eapol_version = 0;
163 conf.wpa_group_rekey = -1;
164 conf.wpa_group_update_count = 4;
165 conf.wpa_pairwise_update_count = 4;
166 #ifdef CONFIG_IEEE80211W
167 conf.ieee80211w = ieee80211w;
168 if (ieee80211w != NO_MGMT_FRAME_PROTECTION)
169 conf.group_mgmt_cipher = rsn->mgmt_group_cipher;
170 #endif /* CONFIG_IEEE80211W */
171
172 rsn->auth = wpa_init(addr, &conf, &cb, rsn);
173 if (rsn->auth == NULL) {
174 wpa_printf(MSG_DEBUG, "AUTH: wpa_init() failed");
175 return -1;
176 }
177
178 /* TODO: support rekeying */
179 rsn->mgtk_len = wpa_cipher_key_len(conf.wpa_group);
180 if (random_get_bytes(rsn->mgtk, rsn->mgtk_len) < 0)
181 return -1;
182 rsn->mgtk_key_id = 1;
183
184 #ifdef CONFIG_IEEE80211W
185 if (ieee80211w != NO_MGMT_FRAME_PROTECTION) {
186 rsn->igtk_len = wpa_cipher_key_len(conf.group_mgmt_cipher);
187 if (random_get_bytes(rsn->igtk, rsn->igtk_len) < 0)
188 return -1;
189 rsn->igtk_key_id = 4;
190
191 /* group mgmt */
192 wpa_hexdump_key(MSG_DEBUG, "mesh: Own TX IGTK",
193 rsn->igtk, rsn->igtk_len);
194 wpa_drv_set_key(rsn->wpa_s,
195 wpa_cipher_to_alg(rsn->mgmt_group_cipher), NULL,
196 rsn->igtk_key_id, 1,
197 seq, sizeof(seq), rsn->igtk, rsn->igtk_len);
198 }
199 #endif /* CONFIG_IEEE80211W */
200
201 /* group privacy / data frames */
202 wpa_hexdump_key(MSG_DEBUG, "mesh: Own TX MGTK",
203 rsn->mgtk, rsn->mgtk_len);
204 wpa_drv_set_key(rsn->wpa_s, wpa_cipher_to_alg(rsn->group_cipher), NULL,
205 rsn->mgtk_key_id, 1, seq, sizeof(seq),
206 rsn->mgtk, rsn->mgtk_len);
207
208 return 0;
209 }
210
211
mesh_rsn_deinit(struct mesh_rsn * rsn)212 static void mesh_rsn_deinit(struct mesh_rsn *rsn)
213 {
214 os_memset(rsn->mgtk, 0, sizeof(rsn->mgtk));
215 rsn->mgtk_len = 0;
216 os_memset(rsn->igtk, 0, sizeof(rsn->igtk));
217 rsn->igtk_len = 0;
218 if (rsn->auth)
219 wpa_deinit(rsn->auth);
220 }
221
222
mesh_rsn_auth_init(struct wpa_supplicant * wpa_s,struct mesh_conf * conf)223 struct mesh_rsn *mesh_rsn_auth_init(struct wpa_supplicant *wpa_s,
224 struct mesh_conf *conf)
225 {
226 struct mesh_rsn *mesh_rsn;
227 struct hostapd_data *bss = wpa_s->ifmsh->bss[0];
228 const u8 *ie;
229 size_t ie_len;
230 #ifdef CONFIG_PMKSA_CACHE_EXTERNAL
231 struct external_pmksa_cache *entry;
232 #endif /* CONFIG_PMKSA_CACHE_EXTERNAL */
233
234 mesh_rsn = os_zalloc(sizeof(*mesh_rsn));
235 if (mesh_rsn == NULL)
236 return NULL;
237 mesh_rsn->wpa_s = wpa_s;
238 mesh_rsn->pairwise_cipher = conf->pairwise_cipher;
239 mesh_rsn->group_cipher = conf->group_cipher;
240 mesh_rsn->mgmt_group_cipher = conf->mgmt_group_cipher;
241
242 if (__mesh_rsn_auth_init(mesh_rsn, wpa_s->own_addr,
243 conf->ieee80211w) < 0) {
244 mesh_rsn_deinit(mesh_rsn);
245 os_free(mesh_rsn);
246 return NULL;
247 }
248
249 bss->wpa_auth = mesh_rsn->auth;
250
251 #ifdef CONFIG_PMKSA_CACHE_EXTERNAL
252 while ((entry = dl_list_last(&wpa_s->mesh_external_pmksa_cache,
253 struct external_pmksa_cache,
254 list)) != NULL) {
255 int ret;
256
257 ret = wpa_auth_pmksa_add_entry(bss->wpa_auth,
258 entry->pmksa_cache);
259 dl_list_del(&entry->list);
260 os_free(entry);
261
262 if (ret < 0)
263 return NULL;
264 }
265 #endif /* CONFIG_PMKSA_CACHE_EXTERNAL */
266
267 ie = wpa_auth_get_wpa_ie(mesh_rsn->auth, &ie_len);
268 conf->rsn_ie = (u8 *) ie;
269 conf->rsn_ie_len = ie_len;
270
271 wpa_supplicant_rsn_supp_set_config(wpa_s, wpa_s->current_ssid);
272
273 return mesh_rsn;
274 }
275
276
index_within_array(const int * array,int idx)277 static int index_within_array(const int *array, int idx)
278 {
279 int i;
280
281 for (i = 0; i < idx; i++) {
282 if (array[i] == -1)
283 return 0;
284 }
285
286 return 1;
287 }
288
289
mesh_rsn_sae_group(struct wpa_supplicant * wpa_s,struct sae_data * sae)290 static int mesh_rsn_sae_group(struct wpa_supplicant *wpa_s,
291 struct sae_data *sae)
292 {
293 int *groups = wpa_s->ifmsh->bss[0]->conf->sae_groups;
294
295 /* Configuration may have changed, so validate current index */
296 if (!index_within_array(groups, wpa_s->mesh_rsn->sae_group_index))
297 return -1;
298
299 for (;;) {
300 int group = groups[wpa_s->mesh_rsn->sae_group_index];
301
302 if (group <= 0)
303 break;
304 if (sae_set_group(sae, group) == 0) {
305 wpa_dbg(wpa_s, MSG_DEBUG, "SME: Selected SAE group %d",
306 sae->group);
307 return 0;
308 }
309 wpa_s->mesh_rsn->sae_group_index++;
310 }
311
312 return -1;
313 }
314
315
mesh_rsn_build_sae_commit(struct wpa_supplicant * wpa_s,struct wpa_ssid * ssid,struct sta_info * sta)316 static int mesh_rsn_build_sae_commit(struct wpa_supplicant *wpa_s,
317 struct wpa_ssid *ssid,
318 struct sta_info *sta)
319 {
320 const char *password;
321
322 password = ssid->sae_password;
323 if (!password)
324 password = ssid->passphrase;
325 if (!password) {
326 wpa_msg(wpa_s, MSG_DEBUG, "SAE: No password available");
327 return -1;
328 }
329
330 if (mesh_rsn_sae_group(wpa_s, sta->sae) < 0) {
331 wpa_msg(wpa_s, MSG_DEBUG, "SAE: Failed to select group");
332 return -1;
333 }
334
335 return sae_prepare_commit(wpa_s->own_addr, sta->addr,
336 (u8 *) password, os_strlen(password),
337 sta->sae);
338 }
339
340
341 /* initiate new SAE authentication with sta */
mesh_rsn_auth_sae_sta(struct wpa_supplicant * wpa_s,struct sta_info * sta)342 int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s,
343 struct sta_info *sta)
344 {
345 struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
346 struct wpa_ssid *ssid = wpa_s->current_ssid;
347 struct rsn_pmksa_cache_entry *pmksa;
348 unsigned int rnd;
349 int ret;
350
351 if (!ssid) {
352 wpa_msg(wpa_s, MSG_DEBUG,
353 "AUTH: No current_ssid known to initiate new SAE");
354 return -1;
355 }
356
357 if (!sta->sae) {
358 sta->sae = os_zalloc(sizeof(*sta->sae));
359 if (sta->sae == NULL)
360 return -1;
361 }
362
363 pmksa = wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr, NULL);
364 if (pmksa) {
365 if (!sta->wpa_sm)
366 sta->wpa_sm = wpa_auth_sta_init(hapd->wpa_auth,
367 sta->addr, NULL);
368 if (!sta->wpa_sm) {
369 wpa_printf(MSG_ERROR,
370 "mesh: Failed to initialize RSN state machine");
371 return -1;
372 }
373
374 wpa_printf(MSG_DEBUG,
375 "AUTH: Mesh PMKSA cache entry found for " MACSTR
376 " - try to use PMKSA caching instead of new SAE authentication",
377 MAC2STR(sta->addr));
378 wpa_auth_pmksa_set_to_sm(pmksa, sta->wpa_sm, hapd->wpa_auth,
379 sta->sae->pmkid, sta->sae->pmk);
380 sae_accept_sta(hapd, sta);
381 sta->mesh_sae_pmksa_caching = 1;
382 return 0;
383 }
384 sta->mesh_sae_pmksa_caching = 0;
385
386 if (mesh_rsn_build_sae_commit(wpa_s, ssid, sta))
387 return -1;
388
389 wpa_msg(wpa_s, MSG_DEBUG,
390 "AUTH: started authentication with SAE peer: " MACSTR,
391 MAC2STR(sta->addr));
392
393 ret = auth_sae_init_committed(hapd, sta);
394 if (ret)
395 return ret;
396
397 eloop_cancel_timeout(mesh_auth_timer, wpa_s, sta);
398 rnd = rand() % MESH_AUTH_TIMEOUT;
399 eloop_register_timeout(MESH_AUTH_TIMEOUT + rnd, 0, mesh_auth_timer,
400 wpa_s, sta);
401 return 0;
402 }
403
404
mesh_rsn_get_pmkid(struct mesh_rsn * rsn,struct sta_info * sta,u8 * pmkid)405 void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid)
406 {
407 os_memcpy(pmkid, sta->sae->pmkid, SAE_PMKID_LEN);
408 }
409
410
411 static void
mesh_rsn_derive_aek(struct mesh_rsn * rsn,struct sta_info * sta)412 mesh_rsn_derive_aek(struct mesh_rsn *rsn, struct sta_info *sta)
413 {
414 u8 *myaddr = rsn->wpa_s->own_addr;
415 u8 *peer = sta->addr;
416 u8 *addr1, *addr2;
417 u8 context[RSN_SELECTOR_LEN + 2 * ETH_ALEN], *ptr = context;
418
419 /*
420 * AEK = KDF-Hash-256(PMK, "AEK Derivation", Selected AKM Suite ||
421 * min(localMAC, peerMAC) || max(localMAC, peerMAC))
422 */
423 /* Selected AKM Suite: SAE */
424 RSN_SELECTOR_PUT(ptr, RSN_AUTH_KEY_MGMT_SAE);
425 ptr += RSN_SELECTOR_LEN;
426
427 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
428 addr1 = myaddr;
429 addr2 = peer;
430 } else {
431 addr1 = peer;
432 addr2 = myaddr;
433 }
434 os_memcpy(ptr, addr1, ETH_ALEN);
435 ptr += ETH_ALEN;
436 os_memcpy(ptr, addr2, ETH_ALEN);
437
438 sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), "AEK Derivation",
439 context, sizeof(context), sta->aek, sizeof(sta->aek));
440 }
441
442
443 /* derive mesh temporal key from pmk */
mesh_rsn_derive_mtk(struct wpa_supplicant * wpa_s,struct sta_info * sta)444 int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta)
445 {
446 u8 *ptr;
447 u8 *min, *max;
448 u8 *myaddr = wpa_s->own_addr;
449 u8 *peer = sta->addr;
450 u8 context[2 * WPA_NONCE_LEN + 2 * 2 + RSN_SELECTOR_LEN + 2 * ETH_ALEN];
451
452 /*
453 * MTK = KDF-Hash-Length(PMK, "Temporal Key Derivation", min(localNonce,
454 * peerNonce) || max(localNonce, peerNonce) || min(localLinkID,
455 * peerLinkID) || max(localLinkID, peerLinkID) || Selected AKM Suite ||
456 * min(localMAC, peerMAC) || max(localMAC, peerMAC))
457 */
458 ptr = context;
459 if (os_memcmp(sta->my_nonce, sta->peer_nonce, WPA_NONCE_LEN) < 0) {
460 min = sta->my_nonce;
461 max = sta->peer_nonce;
462 } else {
463 min = sta->peer_nonce;
464 max = sta->my_nonce;
465 }
466 os_memcpy(ptr, min, WPA_NONCE_LEN);
467 ptr += WPA_NONCE_LEN;
468 os_memcpy(ptr, max, WPA_NONCE_LEN);
469 ptr += WPA_NONCE_LEN;
470
471 if (sta->my_lid < sta->peer_lid) {
472 WPA_PUT_LE16(ptr, sta->my_lid);
473 ptr += 2;
474 WPA_PUT_LE16(ptr, sta->peer_lid);
475 ptr += 2;
476 } else {
477 WPA_PUT_LE16(ptr, sta->peer_lid);
478 ptr += 2;
479 WPA_PUT_LE16(ptr, sta->my_lid);
480 ptr += 2;
481 }
482
483 /* Selected AKM Suite: SAE */
484 RSN_SELECTOR_PUT(ptr, RSN_AUTH_KEY_MGMT_SAE);
485 ptr += RSN_SELECTOR_LEN;
486
487 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
488 min = myaddr;
489 max = peer;
490 } else {
491 min = peer;
492 max = myaddr;
493 }
494 os_memcpy(ptr, min, ETH_ALEN);
495 ptr += ETH_ALEN;
496 os_memcpy(ptr, max, ETH_ALEN);
497
498 sta->mtk_len = wpa_cipher_key_len(wpa_s->mesh_rsn->pairwise_cipher);
499 sha256_prf(sta->sae->pmk, SAE_PMK_LEN,
500 "Temporal Key Derivation", context, sizeof(context),
501 sta->mtk, sta->mtk_len);
502 return 0;
503 }
504
505
mesh_rsn_init_ampe_sta(struct wpa_supplicant * wpa_s,struct sta_info * sta)506 void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta)
507 {
508 if (random_get_bytes(sta->my_nonce, WPA_NONCE_LEN) < 0) {
509 wpa_printf(MSG_INFO, "mesh: Failed to derive random nonce");
510 /* TODO: How to handle this more cleanly? */
511 }
512 os_memset(sta->peer_nonce, 0, WPA_NONCE_LEN);
513 mesh_rsn_derive_aek(wpa_s->mesh_rsn, sta);
514 }
515
516
517 /* insert AMPE and encrypted MIC at @ie.
518 * @mesh_rsn: mesh RSN context
519 * @sta: STA we're sending to
520 * @cat: pointer to category code in frame header.
521 * @buf: wpabuf to add encrypted AMPE and MIC to.
522 * */
mesh_rsn_protect_frame(struct mesh_rsn * rsn,struct sta_info * sta,const u8 * cat,struct wpabuf * buf)523 int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta,
524 const u8 *cat, struct wpabuf *buf)
525 {
526 struct ieee80211_ampe_ie *ampe;
527 u8 const *ie = wpabuf_head_u8(buf) + wpabuf_len(buf);
528 u8 *ampe_ie, *pos, *mic_payload;
529 const u8 *aad[] = { rsn->wpa_s->own_addr, sta->addr, cat };
530 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, ie - cat };
531 int ret = 0;
532 size_t len;
533
534 len = sizeof(*ampe);
535 if (cat[1] == PLINK_OPEN)
536 len += rsn->mgtk_len + WPA_KEY_RSC_LEN + 4;
537 #ifdef CONFIG_IEEE80211W
538 if (cat[1] == PLINK_OPEN && rsn->igtk_len)
539 len += 2 + 6 + rsn->igtk_len;
540 #endif /* CONFIG_IEEE80211W */
541
542 if (2 + AES_BLOCK_SIZE + 2 + len > wpabuf_tailroom(buf)) {
543 wpa_printf(MSG_ERROR, "protect frame: buffer too small");
544 return -EINVAL;
545 }
546
547 ampe_ie = os_zalloc(2 + len);
548 if (!ampe_ie) {
549 wpa_printf(MSG_ERROR, "protect frame: out of memory");
550 return -ENOMEM;
551 }
552
553 /* IE: AMPE */
554 ampe_ie[0] = WLAN_EID_AMPE;
555 ampe_ie[1] = len;
556 ampe = (struct ieee80211_ampe_ie *) (ampe_ie + 2);
557
558 RSN_SELECTOR_PUT(ampe->selected_pairwise_suite,
559 RSN_CIPHER_SUITE_CCMP);
560 os_memcpy(ampe->local_nonce, sta->my_nonce, WPA_NONCE_LEN);
561 os_memcpy(ampe->peer_nonce, sta->peer_nonce, WPA_NONCE_LEN);
562
563 pos = (u8 *) (ampe + 1);
564 if (cat[1] != PLINK_OPEN)
565 goto skip_keys;
566
567 /* TODO: Key Replay Counter[8] optionally for
568 * Mesh Group Key Inform/Acknowledge frames */
569
570 /* TODO: static mgtk for now since we don't support rekeying! */
571 /*
572 * GTKdata[variable]:
573 * MGTK[variable] || Key RSC[8] || GTKExpirationTime[4]
574 */
575 os_memcpy(pos, rsn->mgtk, rsn->mgtk_len);
576 pos += rsn->mgtk_len;
577 wpa_drv_get_seqnum(rsn->wpa_s, NULL, rsn->mgtk_key_id, pos);
578 pos += WPA_KEY_RSC_LEN;
579 /* Use fixed GTKExpirationTime for now */
580 WPA_PUT_LE32(pos, 0xffffffff);
581 pos += 4;
582
583 #ifdef CONFIG_IEEE80211W
584 /*
585 * IGTKdata[variable]:
586 * Key ID[2], IPN[6], IGTK[variable]
587 */
588 if (rsn->igtk_len) {
589 WPA_PUT_LE16(pos, rsn->igtk_key_id);
590 pos += 2;
591 wpa_drv_get_seqnum(rsn->wpa_s, NULL, rsn->igtk_key_id, pos);
592 pos += 6;
593 os_memcpy(pos, rsn->igtk, rsn->igtk_len);
594 }
595 #endif /* CONFIG_IEEE80211W */
596
597 skip_keys:
598 wpa_hexdump_key(MSG_DEBUG, "mesh: Plaintext AMPE element",
599 ampe_ie, 2 + len);
600
601 /* IE: MIC */
602 wpabuf_put_u8(buf, WLAN_EID_MIC);
603 wpabuf_put_u8(buf, AES_BLOCK_SIZE);
604 /* MIC field is output ciphertext */
605
606 /* encrypt after MIC */
607 mic_payload = wpabuf_put(buf, 2 + len + AES_BLOCK_SIZE);
608
609 if (aes_siv_encrypt(sta->aek, sizeof(sta->aek), ampe_ie, 2 + len, 3,
610 aad, aad_len, mic_payload)) {
611 wpa_printf(MSG_ERROR, "protect frame: failed to encrypt");
612 ret = -ENOMEM;
613 }
614
615 os_free(ampe_ie);
616
617 return ret;
618 }
619
620
mesh_rsn_process_ampe(struct wpa_supplicant * wpa_s,struct sta_info * sta,struct ieee802_11_elems * elems,const u8 * cat,const u8 * chosen_pmk,const u8 * start,size_t elems_len)621 int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta,
622 struct ieee802_11_elems *elems, const u8 *cat,
623 const u8 *chosen_pmk,
624 const u8 *start, size_t elems_len)
625 {
626 int ret = 0;
627 struct ieee80211_ampe_ie *ampe;
628 u8 null_nonce[WPA_NONCE_LEN] = {};
629 u8 ampe_eid;
630 u8 ampe_ie_len;
631 u8 *ampe_buf, *crypt = NULL, *pos, *end;
632 size_t crypt_len;
633 const u8 *aad[] = { sta->addr, wpa_s->own_addr, cat };
634 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN,
635 (elems->mic - 2) - cat };
636 size_t key_len;
637
638 if (!sta->sae) {
639 struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
640
641 if (!wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr, NULL)) {
642 wpa_printf(MSG_INFO,
643 "Mesh RSN: SAE is not prepared yet");
644 return -1;
645 }
646 mesh_rsn_auth_sae_sta(wpa_s, sta);
647 }
648
649 if (chosen_pmk && os_memcmp(chosen_pmk, sta->sae->pmkid, PMKID_LEN)) {
650 wpa_msg(wpa_s, MSG_DEBUG,
651 "Mesh RSN: Invalid PMKID (Chosen PMK did not match calculated PMKID)");
652 return -1;
653 }
654
655 if (!elems->mic || elems->mic_len < AES_BLOCK_SIZE) {
656 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing mic ie");
657 return -1;
658 }
659
660 ampe_buf = (u8 *) elems->mic + elems->mic_len;
661 if ((int) elems_len < ampe_buf - start)
662 return -1;
663
664 crypt_len = elems_len - (elems->mic - start);
665 if (crypt_len < 2 + AES_BLOCK_SIZE) {
666 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing ampe ie");
667 return -1;
668 }
669
670 /* crypt is modified by siv_decrypt */
671 crypt = os_zalloc(crypt_len);
672 if (!crypt) {
673 wpa_printf(MSG_ERROR, "Mesh RSN: out of memory");
674 ret = -ENOMEM;
675 goto free;
676 }
677
678 os_memcpy(crypt, elems->mic, crypt_len);
679
680 if (aes_siv_decrypt(sta->aek, sizeof(sta->aek), crypt, crypt_len, 3,
681 aad, aad_len, ampe_buf)) {
682 wpa_printf(MSG_ERROR, "Mesh RSN: frame verification failed!");
683 ret = -2;
684 goto free;
685 }
686
687 crypt_len -= AES_BLOCK_SIZE;
688 wpa_hexdump_key(MSG_DEBUG, "mesh: Decrypted AMPE element",
689 ampe_buf, crypt_len);
690
691 ampe_eid = *ampe_buf++;
692 ampe_ie_len = *ampe_buf++;
693
694 if (ampe_eid != WLAN_EID_AMPE ||
695 (size_t) 2 + ampe_ie_len > crypt_len ||
696 ampe_ie_len < sizeof(struct ieee80211_ampe_ie)) {
697 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid ampe ie");
698 ret = -1;
699 goto free;
700 }
701
702 ampe = (struct ieee80211_ampe_ie *) ampe_buf;
703 pos = (u8 *) (ampe + 1);
704 end = ampe_buf + ampe_ie_len;
705 if (os_memcmp(ampe->peer_nonce, null_nonce, WPA_NONCE_LEN) != 0 &&
706 os_memcmp(ampe->peer_nonce, sta->my_nonce, WPA_NONCE_LEN) != 0) {
707 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid peer nonce");
708 ret = -1;
709 goto free;
710 }
711 os_memcpy(sta->peer_nonce, ampe->local_nonce,
712 sizeof(ampe->local_nonce));
713
714 /* TODO: Key Replay Counter[8] in Mesh Group Key Inform/Acknowledge
715 * frames */
716
717 /*
718 * GTKdata shall not be included in Mesh Peering Confirm. While the
719 * standard does not state the same about IGTKdata, that same constraint
720 * needs to apply for it. It makes no sense to include the keys in Mesh
721 * Peering Close frames either, so while the standard does not seem to
722 * have a shall statement for these, they are described without
723 * mentioning GTKdata.
724 *
725 * An earlier implementation used to add GTKdata to both Mesh Peering
726 * Open and Mesh Peering Confirm frames, so ignore the possibly present
727 * GTKdata frame without rejecting the frame as a backwards
728 * compatibility mechanism.
729 */
730 if (cat[1] != PLINK_OPEN) {
731 if (end > pos) {
732 wpa_hexdump_key(MSG_DEBUG,
733 "mesh: Ignore unexpected GTKdata(etc.) fields in the end of AMPE element in Mesh Peering Confirm/Close",
734 pos, end - pos);
735 }
736 goto free;
737 }
738
739 /*
740 * GTKdata[variable]:
741 * MGTK[variable] || Key RSC[8] || GTKExpirationTime[4]
742 */
743 sta->mgtk_key_id = 1; /* FIX: Where to get Key ID? */
744 key_len = wpa_cipher_key_len(wpa_s->mesh_rsn->group_cipher);
745 if ((int) key_len + WPA_KEY_RSC_LEN + 4 > end - pos) {
746 wpa_dbg(wpa_s, MSG_DEBUG, "mesh: Truncated AMPE element");
747 ret = -1;
748 goto free;
749 }
750 sta->mgtk_len = key_len;
751 os_memcpy(sta->mgtk, pos, sta->mgtk_len);
752 wpa_hexdump_key(MSG_DEBUG, "mesh: GTKdata - MGTK",
753 sta->mgtk, sta->mgtk_len);
754 pos += sta->mgtk_len;
755 wpa_hexdump(MSG_DEBUG, "mesh: GTKdata - MGTK - Key RSC",
756 pos, WPA_KEY_RSC_LEN);
757 os_memcpy(sta->mgtk_rsc, pos, sizeof(sta->mgtk_rsc));
758 pos += WPA_KEY_RSC_LEN;
759 wpa_printf(MSG_DEBUG,
760 "mesh: GTKdata - MGTK - GTKExpirationTime: %u seconds",
761 WPA_GET_LE32(pos));
762 pos += 4;
763
764 #ifdef CONFIG_IEEE80211W
765 /*
766 * IGTKdata[variable]:
767 * Key ID[2], IPN[6], IGTK[variable]
768 */
769 key_len = wpa_cipher_key_len(wpa_s->mesh_rsn->mgmt_group_cipher);
770 if (end - pos >= (int) (2 + 6 + key_len)) {
771 sta->igtk_key_id = WPA_GET_LE16(pos);
772 wpa_printf(MSG_DEBUG, "mesh: IGTKdata - Key ID %u",
773 sta->igtk_key_id);
774 pos += 2;
775 os_memcpy(sta->igtk_rsc, pos, sizeof(sta->igtk_rsc));
776 wpa_hexdump(MSG_DEBUG, "mesh: IGTKdata - IPN",
777 sta->igtk_rsc, sizeof(sta->igtk_rsc));
778 pos += 6;
779 os_memcpy(sta->igtk, pos, key_len);
780 sta->igtk_len = key_len;
781 wpa_hexdump_key(MSG_DEBUG, "mesh: IGTKdata - IGTK",
782 sta->igtk, sta->igtk_len);
783 }
784 #endif /* CONFIG_IEEE80211W */
785
786 free:
787 os_free(crypt);
788 return ret;
789 }
790