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 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 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 77 static const u8 *auth_get_psk(void *ctx, const u8 *addr, 78 const u8 *p2p_dev_addr, const u8 *prev_psk) 79 { 80 struct mesh_rsn *mesh_rsn = ctx; 81 struct hostapd_data *hapd = mesh_rsn->wpa_s->ifmsh->bss[0]; 82 struct sta_info *sta = ap_get_sta(hapd, addr); 83 84 wpa_printf(MSG_DEBUG, "AUTH: %s (addr=" MACSTR " prev_psk=%p)", 85 __func__, MAC2STR(addr), prev_psk); 86 87 if (sta && sta->auth_alg == WLAN_AUTH_SAE) { 88 if (!sta->sae || prev_psk) 89 return NULL; 90 return sta->sae->pmk; 91 } 92 93 return NULL; 94 } 95 96 97 static int auth_set_key(void *ctx, int vlan_id, enum wpa_alg alg, 98 const u8 *addr, int idx, u8 *key, size_t key_len) 99 { 100 struct mesh_rsn *mesh_rsn = ctx; 101 u8 seq[6]; 102 103 os_memset(seq, 0, sizeof(seq)); 104 105 if (addr) { 106 wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d addr=" MACSTR 107 " key_idx=%d)", 108 __func__, alg, MAC2STR(addr), idx); 109 } else { 110 wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d key_idx=%d)", 111 __func__, alg, idx); 112 } 113 wpa_hexdump_key(MSG_DEBUG, "AUTH: set_key - key", key, key_len); 114 115 return wpa_drv_set_key(mesh_rsn->wpa_s, alg, addr, idx, 116 1, seq, 6, key, key_len); 117 } 118 119 120 static int auth_start_ampe(void *ctx, const u8 *addr) 121 { 122 struct mesh_rsn *mesh_rsn = ctx; 123 struct hostapd_data *hapd; 124 struct sta_info *sta; 125 126 if (mesh_rsn->wpa_s->current_ssid->mode != WPAS_MODE_MESH) 127 return -1; 128 129 hapd = mesh_rsn->wpa_s->ifmsh->bss[0]; 130 sta = ap_get_sta(hapd, addr); 131 if (sta) 132 eloop_cancel_timeout(mesh_auth_timer, mesh_rsn->wpa_s, sta); 133 134 mesh_mpm_auth_peer(mesh_rsn->wpa_s, addr); 135 return 0; 136 } 137 138 139 static int __mesh_rsn_auth_init(struct mesh_rsn *rsn, const u8 *addr) 140 { 141 struct wpa_auth_config conf; 142 struct wpa_auth_callbacks cb; 143 u8 seq[6] = {}; 144 145 wpa_printf(MSG_DEBUG, "AUTH: Initializing group state machine"); 146 147 os_memset(&conf, 0, sizeof(conf)); 148 conf.wpa = 2; 149 conf.wpa_key_mgmt = WPA_KEY_MGMT_SAE; 150 conf.wpa_pairwise = WPA_CIPHER_CCMP; 151 conf.rsn_pairwise = WPA_CIPHER_CCMP; 152 conf.wpa_group = WPA_CIPHER_CCMP; 153 conf.eapol_version = 0; 154 conf.wpa_group_rekey = -1; 155 156 os_memset(&cb, 0, sizeof(cb)); 157 cb.ctx = rsn; 158 cb.logger = auth_logger; 159 cb.get_psk = auth_get_psk; 160 cb.set_key = auth_set_key; 161 cb.start_ampe = auth_start_ampe; 162 163 rsn->auth = wpa_init(addr, &conf, &cb); 164 if (rsn->auth == NULL) { 165 wpa_printf(MSG_DEBUG, "AUTH: wpa_init() failed"); 166 return -1; 167 } 168 169 /* TODO: support rekeying */ 170 if (random_get_bytes(rsn->mgtk, 16) < 0) { 171 wpa_deinit(rsn->auth); 172 return -1; 173 } 174 175 /* group mgmt */ 176 wpa_drv_set_key(rsn->wpa_s, WPA_ALG_IGTK, NULL, 4, 1, 177 seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk)); 178 179 /* group privacy / data frames */ 180 wpa_drv_set_key(rsn->wpa_s, WPA_ALG_CCMP, NULL, 1, 1, 181 seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk)); 182 183 return 0; 184 } 185 186 187 static void mesh_rsn_deinit(struct mesh_rsn *rsn) 188 { 189 os_memset(rsn->mgtk, 0, sizeof(rsn->mgtk)); 190 if (rsn->auth) 191 wpa_deinit(rsn->auth); 192 } 193 194 195 struct mesh_rsn *mesh_rsn_auth_init(struct wpa_supplicant *wpa_s, 196 struct mesh_conf *conf) 197 { 198 struct mesh_rsn *mesh_rsn; 199 struct hostapd_data *bss = wpa_s->ifmsh->bss[0]; 200 const u8 *ie; 201 size_t ie_len; 202 203 mesh_rsn = os_zalloc(sizeof(*mesh_rsn)); 204 if (mesh_rsn == NULL) 205 return NULL; 206 mesh_rsn->wpa_s = wpa_s; 207 208 if (__mesh_rsn_auth_init(mesh_rsn, wpa_s->own_addr) < 0) { 209 mesh_rsn_deinit(mesh_rsn); 210 os_free(mesh_rsn); 211 return NULL; 212 } 213 214 bss->wpa_auth = mesh_rsn->auth; 215 216 ie = wpa_auth_get_wpa_ie(mesh_rsn->auth, &ie_len); 217 conf->rsn_ie = (u8 *) ie; 218 conf->rsn_ie_len = ie_len; 219 220 wpa_supplicant_rsn_supp_set_config(wpa_s, wpa_s->current_ssid); 221 222 return mesh_rsn; 223 } 224 225 226 static int index_within_array(const int *array, int idx) 227 { 228 int i; 229 230 for (i = 0; i < idx; i++) { 231 if (array[i] == -1) 232 return 0; 233 } 234 235 return 1; 236 } 237 238 239 static int mesh_rsn_sae_group(struct wpa_supplicant *wpa_s, 240 struct sae_data *sae) 241 { 242 int *groups = wpa_s->ifmsh->bss[0]->conf->sae_groups; 243 244 /* Configuration may have changed, so validate current index */ 245 if (!index_within_array(groups, wpa_s->mesh_rsn->sae_group_index)) 246 return -1; 247 248 for (;;) { 249 int group = groups[wpa_s->mesh_rsn->sae_group_index]; 250 251 if (group <= 0) 252 break; 253 if (sae_set_group(sae, group) == 0) { 254 wpa_dbg(wpa_s, MSG_DEBUG, "SME: Selected SAE group %d", 255 sae->group); 256 return 0; 257 } 258 wpa_s->mesh_rsn->sae_group_index++; 259 } 260 261 return -1; 262 } 263 264 265 static int mesh_rsn_build_sae_commit(struct wpa_supplicant *wpa_s, 266 struct wpa_ssid *ssid, 267 struct sta_info *sta) 268 { 269 if (ssid->passphrase == NULL) { 270 wpa_msg(wpa_s, MSG_DEBUG, "SAE: No password available"); 271 return -1; 272 } 273 274 if (mesh_rsn_sae_group(wpa_s, sta->sae) < 0) { 275 wpa_msg(wpa_s, MSG_DEBUG, "SAE: Failed to select group"); 276 return -1; 277 } 278 279 return sae_prepare_commit(wpa_s->own_addr, sta->addr, 280 (u8 *) ssid->passphrase, 281 os_strlen(ssid->passphrase), sta->sae); 282 } 283 284 285 /* initiate new SAE authentication with sta */ 286 int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s, 287 struct sta_info *sta) 288 { 289 struct hostapd_data *hapd = wpa_s->ifmsh->bss[0]; 290 struct wpa_ssid *ssid = wpa_s->current_ssid; 291 struct rsn_pmksa_cache_entry *pmksa; 292 unsigned int rnd; 293 int ret; 294 295 if (!ssid) { 296 wpa_msg(wpa_s, MSG_DEBUG, 297 "AUTH: No current_ssid known to initiate new SAE"); 298 return -1; 299 } 300 301 if (!sta->sae) { 302 sta->sae = os_zalloc(sizeof(*sta->sae)); 303 if (sta->sae == NULL) 304 return -1; 305 } 306 307 pmksa = wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr); 308 if (pmksa) { 309 if (!sta->wpa_sm) 310 sta->wpa_sm = wpa_auth_sta_init(hapd->wpa_auth, 311 sta->addr, NULL); 312 if (!sta->wpa_sm) { 313 wpa_printf(MSG_ERROR, 314 "mesh: Failed to initialize RSN state machine"); 315 return -1; 316 } 317 318 wpa_printf(MSG_DEBUG, 319 "AUTH: Mesh PMKSA cache entry found for " MACSTR 320 " - try to use PMKSA caching instead of new SAE authentication", 321 MAC2STR(sta->addr)); 322 wpa_auth_pmksa_set_to_sm(pmksa, sta->wpa_sm, hapd->wpa_auth, 323 sta->sae->pmkid, sta->sae->pmk); 324 sae_accept_sta(hapd, sta); 325 sta->mesh_sae_pmksa_caching = 1; 326 return 0; 327 } 328 sta->mesh_sae_pmksa_caching = 0; 329 330 if (mesh_rsn_build_sae_commit(wpa_s, ssid, sta)) 331 return -1; 332 333 wpa_msg(wpa_s, MSG_DEBUG, 334 "AUTH: started authentication with SAE peer: " MACSTR, 335 MAC2STR(sta->addr)); 336 337 wpa_supplicant_set_state(wpa_s, WPA_AUTHENTICATING); 338 ret = auth_sae_init_committed(hapd, sta); 339 if (ret) 340 return ret; 341 342 eloop_cancel_timeout(mesh_auth_timer, wpa_s, sta); 343 rnd = rand() % MESH_AUTH_TIMEOUT; 344 eloop_register_timeout(MESH_AUTH_TIMEOUT + rnd, 0, mesh_auth_timer, 345 wpa_s, sta); 346 return 0; 347 } 348 349 350 void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid) 351 { 352 os_memcpy(pmkid, sta->sae->pmkid, SAE_PMKID_LEN); 353 } 354 355 356 static void 357 mesh_rsn_derive_aek(struct mesh_rsn *rsn, struct sta_info *sta) 358 { 359 u8 *myaddr = rsn->wpa_s->own_addr; 360 u8 *peer = sta->addr; 361 u8 *addr1 = peer, *addr2 = myaddr; 362 u8 context[AES_BLOCK_SIZE]; 363 364 /* SAE */ 365 RSN_SELECTOR_PUT(context, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP)); 366 367 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) { 368 addr1 = myaddr; 369 addr2 = peer; 370 } 371 os_memcpy(context + 4, addr1, ETH_ALEN); 372 os_memcpy(context + 10, addr2, ETH_ALEN); 373 374 sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), "AEK Derivation", 375 context, sizeof(context), sta->aek, sizeof(sta->aek)); 376 } 377 378 379 /* derive mesh temporal key from pmk */ 380 int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta) 381 { 382 u8 *ptr; 383 u8 *min, *max; 384 u16 min_lid, max_lid; 385 size_t nonce_len = sizeof(sta->my_nonce); 386 size_t lid_len = sizeof(sta->my_lid); 387 u8 *myaddr = wpa_s->own_addr; 388 u8 *peer = sta->addr; 389 /* 2 nonces, 2 linkids, akm suite, 2 mac addrs */ 390 u8 context[64 + 4 + 4 + 12]; 391 392 ptr = context; 393 if (os_memcmp(sta->my_nonce, sta->peer_nonce, nonce_len) < 0) { 394 min = sta->my_nonce; 395 max = sta->peer_nonce; 396 } else { 397 min = sta->peer_nonce; 398 max = sta->my_nonce; 399 } 400 os_memcpy(ptr, min, nonce_len); 401 os_memcpy(ptr + nonce_len, max, nonce_len); 402 ptr += 2 * nonce_len; 403 404 if (sta->my_lid < sta->peer_lid) { 405 min_lid = host_to_le16(sta->my_lid); 406 max_lid = host_to_le16(sta->peer_lid); 407 } else { 408 min_lid = host_to_le16(sta->peer_lid); 409 max_lid = host_to_le16(sta->my_lid); 410 } 411 os_memcpy(ptr, &min_lid, lid_len); 412 os_memcpy(ptr + lid_len, &max_lid, lid_len); 413 ptr += 2 * lid_len; 414 415 /* SAE */ 416 RSN_SELECTOR_PUT(ptr, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP)); 417 ptr += 4; 418 419 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) { 420 min = myaddr; 421 max = peer; 422 } else { 423 min = peer; 424 max = myaddr; 425 } 426 os_memcpy(ptr, min, ETH_ALEN); 427 os_memcpy(ptr + ETH_ALEN, max, ETH_ALEN); 428 429 sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), 430 "Temporal Key Derivation", context, sizeof(context), 431 sta->mtk, sizeof(sta->mtk)); 432 return 0; 433 } 434 435 436 void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta) 437 { 438 if (random_get_bytes(sta->my_nonce, 32) < 0) { 439 wpa_printf(MSG_INFO, "mesh: Failed to derive random nonce"); 440 /* TODO: How to handle this more cleanly? */ 441 } 442 os_memset(sta->peer_nonce, 0, 32); 443 mesh_rsn_derive_aek(wpa_s->mesh_rsn, sta); 444 } 445 446 447 /* insert AMPE and encrypted MIC at @ie. 448 * @mesh_rsn: mesh RSN context 449 * @sta: STA we're sending to 450 * @cat: pointer to category code in frame header. 451 * @buf: wpabuf to add encrypted AMPE and MIC to. 452 * */ 453 int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta, 454 const u8 *cat, struct wpabuf *buf) 455 { 456 struct ieee80211_ampe_ie *ampe; 457 u8 const *ie = wpabuf_head_u8(buf) + wpabuf_len(buf); 458 u8 *ampe_ie = NULL, *mic_ie = NULL, *mic_payload; 459 const u8 *aad[] = { rsn->wpa_s->own_addr, sta->addr, cat }; 460 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, ie - cat }; 461 int ret = 0; 462 463 if (AES_BLOCK_SIZE + 2 + sizeof(*ampe) + 2 > wpabuf_tailroom(buf)) { 464 wpa_printf(MSG_ERROR, "protect frame: buffer too small"); 465 return -EINVAL; 466 } 467 468 ampe_ie = os_zalloc(2 + sizeof(*ampe)); 469 if (!ampe_ie) { 470 wpa_printf(MSG_ERROR, "protect frame: out of memory"); 471 return -ENOMEM; 472 } 473 474 mic_ie = os_zalloc(2 + AES_BLOCK_SIZE); 475 if (!mic_ie) { 476 wpa_printf(MSG_ERROR, "protect frame: out of memory"); 477 ret = -ENOMEM; 478 goto free; 479 } 480 481 /* IE: AMPE */ 482 ampe_ie[0] = WLAN_EID_AMPE; 483 ampe_ie[1] = sizeof(*ampe); 484 ampe = (struct ieee80211_ampe_ie *) (ampe_ie + 2); 485 486 RSN_SELECTOR_PUT(ampe->selected_pairwise_suite, 487 wpa_cipher_to_suite(WPA_PROTO_RSN, WPA_CIPHER_CCMP)); 488 os_memcpy(ampe->local_nonce, sta->my_nonce, 32); 489 os_memcpy(ampe->peer_nonce, sta->peer_nonce, 32); 490 /* incomplete: see 13.5.4 */ 491 /* TODO: static mgtk for now since we don't support rekeying! */ 492 os_memcpy(ampe->mgtk, rsn->mgtk, 16); 493 /* TODO: Populate Key RSC */ 494 /* expire in 13 decades or so */ 495 os_memset(ampe->key_expiration, 0xff, 4); 496 497 /* IE: MIC */ 498 mic_ie[0] = WLAN_EID_MIC; 499 mic_ie[1] = AES_BLOCK_SIZE; 500 wpabuf_put_data(buf, mic_ie, 2); 501 /* MIC field is output ciphertext */ 502 503 /* encrypt after MIC */ 504 mic_payload = (u8 *) wpabuf_put(buf, 2 + sizeof(*ampe) + 505 AES_BLOCK_SIZE); 506 507 if (aes_siv_encrypt(sta->aek, ampe_ie, 2 + sizeof(*ampe), 3, 508 aad, aad_len, mic_payload)) { 509 wpa_printf(MSG_ERROR, "protect frame: failed to encrypt"); 510 ret = -ENOMEM; 511 goto free; 512 } 513 514 free: 515 os_free(ampe_ie); 516 os_free(mic_ie); 517 518 return ret; 519 } 520 521 522 int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta, 523 struct ieee802_11_elems *elems, const u8 *cat, 524 const u8 *chosen_pmk, 525 const u8 *start, size_t elems_len) 526 { 527 int ret = 0; 528 struct ieee80211_ampe_ie *ampe; 529 u8 null_nonce[32] = {}; 530 u8 ampe_eid; 531 u8 ampe_ie_len; 532 u8 *ampe_buf, *crypt = NULL; 533 size_t crypt_len; 534 const u8 *aad[] = { sta->addr, wpa_s->own_addr, cat }; 535 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, 536 (elems->mic - 2) - cat }; 537 538 if (!sta->sae) { 539 struct hostapd_data *hapd = wpa_s->ifmsh->bss[0]; 540 541 if (!wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr)) { 542 wpa_printf(MSG_INFO, 543 "Mesh RSN: SAE is not prepared yet"); 544 return -1; 545 } 546 mesh_rsn_auth_sae_sta(wpa_s, sta); 547 } 548 549 if (chosen_pmk && os_memcmp(chosen_pmk, sta->sae->pmkid, PMKID_LEN)) { 550 wpa_msg(wpa_s, MSG_DEBUG, 551 "Mesh RSN: Invalid PMKID (Chosen PMK did not match calculated PMKID)"); 552 return -1; 553 } 554 555 if (!elems->mic || elems->mic_len < AES_BLOCK_SIZE) { 556 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing mic ie"); 557 return -1; 558 } 559 560 ampe_buf = (u8 *) elems->mic + elems->mic_len; 561 if ((int) elems_len < ampe_buf - start) 562 return -1; 563 564 crypt_len = elems_len - (elems->mic - start); 565 if (crypt_len < 2) { 566 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing ampe ie"); 567 return -1; 568 } 569 570 /* crypt is modified by siv_decrypt */ 571 crypt = os_zalloc(crypt_len); 572 if (!crypt) { 573 wpa_printf(MSG_ERROR, "Mesh RSN: out of memory"); 574 ret = -ENOMEM; 575 goto free; 576 } 577 578 os_memcpy(crypt, elems->mic, crypt_len); 579 580 if (aes_siv_decrypt(sta->aek, crypt, crypt_len, 3, 581 aad, aad_len, ampe_buf)) { 582 wpa_printf(MSG_ERROR, "Mesh RSN: frame verification failed!"); 583 ret = -1; 584 goto free; 585 } 586 587 ampe_eid = *ampe_buf++; 588 ampe_ie_len = *ampe_buf++; 589 590 if (ampe_eid != WLAN_EID_AMPE || 591 ampe_ie_len < sizeof(struct ieee80211_ampe_ie)) { 592 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid ampe ie"); 593 ret = -1; 594 goto free; 595 } 596 597 ampe = (struct ieee80211_ampe_ie *) ampe_buf; 598 if (os_memcmp(ampe->peer_nonce, null_nonce, 32) != 0 && 599 os_memcmp(ampe->peer_nonce, sta->my_nonce, 32) != 0) { 600 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid peer nonce"); 601 ret = -1; 602 goto free; 603 } 604 os_memcpy(sta->peer_nonce, ampe->local_nonce, 605 sizeof(ampe->local_nonce)); 606 os_memcpy(sta->mgtk, ampe->mgtk, sizeof(ampe->mgtk)); 607 608 /* todo parse mgtk expiration */ 609 free: 610 os_free(crypt); 611 return ret; 612 } 613
