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 #define MESH_AUTH_BLOCK_DURATION 3600 31 32 void mesh_auth_timer(void *eloop_ctx, void *user_data) 33 { 34 struct wpa_supplicant *wpa_s = eloop_ctx; 35 struct sta_info *sta = user_data; 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 if (sta->sae_auth_retry > MESH_AUTH_RETRY) { 47 ap_free_sta(wpa_s->ifmsh->bss[0], sta); 48 return; 49 } 50 51 /* block the STA if exceeded the number of attempts */ 52 wpa_mesh_set_plink_state(wpa_s, sta, PLINK_BLOCKED); 53 sta->sae->state = SAE_NOTHING; 54 if (wpa_s->mesh_auth_block_duration < 55 MESH_AUTH_BLOCK_DURATION) 56 wpa_s->mesh_auth_block_duration += 60; 57 eloop_register_timeout(wpa_s->mesh_auth_block_duration, 58 0, mesh_auth_timer, wpa_s, sta); 59 wpa_msg(wpa_s, MSG_INFO, MESH_SAE_AUTH_BLOCKED "addr=" 60 MACSTR " duration=%d", 61 MAC2STR(sta->addr), 62 wpa_s->mesh_auth_block_duration); 63 } 64 sta->sae_auth_retry++; 65 } 66 } 67 68 69 static void auth_logger(void *ctx, const u8 *addr, logger_level level, 70 const char *txt) 71 { 72 if (addr) 73 wpa_printf(MSG_DEBUG, "AUTH: " MACSTR " - %s", 74 MAC2STR(addr), txt); 75 else 76 wpa_printf(MSG_DEBUG, "AUTH: %s", txt); 77 } 78 79 80 static const u8 *auth_get_psk(void *ctx, const u8 *addr, 81 const u8 *p2p_dev_addr, const u8 *prev_psk) 82 { 83 struct mesh_rsn *mesh_rsn = ctx; 84 struct hostapd_data *hapd = mesh_rsn->wpa_s->ifmsh->bss[0]; 85 struct sta_info *sta = ap_get_sta(hapd, addr); 86 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 99 100 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 } 121 122 123 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 } 140 141 142 static int __mesh_rsn_auth_init(struct mesh_rsn *rsn, const u8 *addr) 143 { 144 struct wpa_auth_config conf; 145 struct wpa_auth_callbacks cb; 146 u8 seq[6] = {}; 147 148 wpa_printf(MSG_DEBUG, "AUTH: Initializing group state machine"); 149 150 os_memset(&conf, 0, sizeof(conf)); 151 conf.wpa = 2; 152 conf.wpa_key_mgmt = WPA_KEY_MGMT_SAE; 153 conf.wpa_pairwise = WPA_CIPHER_CCMP; 154 conf.rsn_pairwise = WPA_CIPHER_CCMP; 155 conf.wpa_group = WPA_CIPHER_CCMP; 156 conf.eapol_version = 0; 157 conf.wpa_group_rekey = -1; 158 159 os_memset(&cb, 0, sizeof(cb)); 160 cb.ctx = rsn; 161 cb.logger = auth_logger; 162 cb.get_psk = auth_get_psk; 163 cb.set_key = auth_set_key; 164 cb.start_ampe = auth_start_ampe; 165 166 rsn->auth = wpa_init(addr, &conf, &cb); 167 if (rsn->auth == NULL) { 168 wpa_printf(MSG_DEBUG, "AUTH: wpa_init() failed"); 169 return -1; 170 } 171 172 /* TODO: support rekeying */ 173 if (random_get_bytes(rsn->mgtk, 16) < 0) { 174 wpa_deinit(rsn->auth); 175 return -1; 176 } 177 178 /* group mgmt */ 179 wpa_drv_set_key(rsn->wpa_s, WPA_ALG_IGTK, NULL, 4, 1, 180 seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk)); 181 182 /* group privacy / data frames */ 183 wpa_drv_set_key(rsn->wpa_s, WPA_ALG_CCMP, NULL, 1, 1, 184 seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk)); 185 186 return 0; 187 } 188 189 190 static void mesh_rsn_deinit(struct mesh_rsn *rsn) 191 { 192 os_memset(rsn->mgtk, 0, sizeof(rsn->mgtk)); 193 wpa_deinit(rsn->auth); 194 } 195 196 197 struct mesh_rsn *mesh_rsn_auth_init(struct wpa_supplicant *wpa_s, 198 struct mesh_conf *conf) 199 { 200 struct mesh_rsn *mesh_rsn; 201 struct hostapd_data *bss = wpa_s->ifmsh->bss[0]; 202 const u8 *ie; 203 size_t ie_len; 204 205 mesh_rsn = os_zalloc(sizeof(*mesh_rsn)); 206 if (mesh_rsn == NULL) 207 return NULL; 208 mesh_rsn->wpa_s = wpa_s; 209 210 if (__mesh_rsn_auth_init(mesh_rsn, wpa_s->own_addr) < 0) { 211 mesh_rsn_deinit(mesh_rsn); 212 return NULL; 213 } 214 215 bss->wpa_auth = mesh_rsn->auth; 216 217 ie = wpa_auth_get_wpa_ie(mesh_rsn->auth, &ie_len); 218 conf->ies = (u8 *) ie; 219 conf->ie_len = ie_len; 220 221 wpa_supplicant_rsn_supp_set_config(wpa_s, wpa_s->current_ssid); 222 223 return mesh_rsn; 224 } 225 226 227 static int index_within_array(const int *array, int idx) 228 { 229 int i; 230 231 for (i = 0; i < idx; i++) { 232 if (array[i] == -1) 233 return 0; 234 } 235 236 return 1; 237 } 238 239 240 static int mesh_rsn_sae_group(struct wpa_supplicant *wpa_s, 241 struct sae_data *sae) 242 { 243 int *groups = wpa_s->ifmsh->bss[0]->conf->sae_groups; 244 245 /* Configuration may have changed, so validate current index */ 246 if (!index_within_array(groups, wpa_s->mesh_rsn->sae_group_index)) 247 return -1; 248 249 for (;;) { 250 int group = groups[wpa_s->mesh_rsn->sae_group_index]; 251 252 if (group <= 0) 253 break; 254 if (sae_set_group(sae, group) == 0) { 255 wpa_dbg(wpa_s, MSG_DEBUG, "SME: Selected SAE group %d", 256 sae->group); 257 return 0; 258 } 259 wpa_s->mesh_rsn->sae_group_index++; 260 } 261 262 return -1; 263 } 264 265 266 static int mesh_rsn_build_sae_commit(struct wpa_supplicant *wpa_s, 267 struct wpa_ssid *ssid, 268 struct sta_info *sta) 269 { 270 if (ssid->passphrase == NULL) { 271 wpa_msg(wpa_s, MSG_DEBUG, "SAE: No password available"); 272 return -1; 273 } 274 275 if (mesh_rsn_sae_group(wpa_s, sta->sae) < 0) { 276 wpa_msg(wpa_s, MSG_DEBUG, "SAE: Failed to select group"); 277 return -1; 278 } 279 280 return sae_prepare_commit(wpa_s->own_addr, sta->addr, 281 (u8 *) ssid->passphrase, 282 os_strlen(ssid->passphrase), sta->sae); 283 } 284 285 286 /* initiate new SAE authentication with sta */ 287 int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s, 288 struct sta_info *sta) 289 { 290 struct hostapd_data *hapd = wpa_s->ifmsh->bss[0]; 291 struct wpa_ssid *ssid = wpa_s->current_ssid; 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 if (mesh_rsn_build_sae_commit(wpa_s, ssid, sta)) 308 return -1; 309 310 wpa_msg(wpa_s, MSG_DEBUG, 311 "AUTH: started authentication with SAE peer: " MACSTR, 312 MAC2STR(sta->addr)); 313 314 wpa_supplicant_set_state(wpa_s, WPA_AUTHENTICATING); 315 ret = auth_sae_init_committed(hapd, sta); 316 if (ret) 317 return ret; 318 319 eloop_cancel_timeout(mesh_auth_timer, wpa_s, sta); 320 rnd = rand() % MESH_AUTH_TIMEOUT; 321 eloop_register_timeout(MESH_AUTH_TIMEOUT + rnd, 0, mesh_auth_timer, 322 wpa_s, sta); 323 return 0; 324 } 325 326 327 void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid) 328 { 329 /* don't expect wpa auth to cache the pmkid for now */ 330 rsn_pmkid(sta->sae->pmk, PMK_LEN, rsn->wpa_s->own_addr, 331 sta->addr, pmkid, 332 wpa_key_mgmt_sha256(wpa_auth_sta_key_mgmt(sta->wpa_sm))); 333 } 334 335 336 static void 337 mesh_rsn_derive_aek(struct mesh_rsn *rsn, struct sta_info *sta) 338 { 339 u8 *myaddr = rsn->wpa_s->own_addr; 340 u8 *peer = sta->addr; 341 u8 *addr1 = peer, *addr2 = myaddr; 342 u8 context[AES_BLOCK_SIZE]; 343 344 /* SAE */ 345 RSN_SELECTOR_PUT(context, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP)); 346 347 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) { 348 addr1 = myaddr; 349 addr2 = peer; 350 } 351 os_memcpy(context + 4, addr1, ETH_ALEN); 352 os_memcpy(context + 10, addr2, ETH_ALEN); 353 354 sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), "AEK Derivation", 355 context, sizeof(context), sta->aek, sizeof(sta->aek)); 356 } 357 358 359 /* derive mesh temporal key from pmk */ 360 int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta) 361 { 362 u8 *ptr; 363 u8 *min, *max; 364 u16 min_lid, max_lid; 365 size_t nonce_len = sizeof(sta->my_nonce); 366 size_t lid_len = sizeof(sta->my_lid); 367 u8 *myaddr = wpa_s->own_addr; 368 u8 *peer = sta->addr; 369 /* 2 nonces, 2 linkids, akm suite, 2 mac addrs */ 370 u8 context[64 + 4 + 4 + 12]; 371 372 ptr = context; 373 if (os_memcmp(sta->my_nonce, sta->peer_nonce, nonce_len) < 0) { 374 min = sta->my_nonce; 375 max = sta->peer_nonce; 376 } else { 377 min = sta->peer_nonce; 378 max = sta->my_nonce; 379 } 380 os_memcpy(ptr, min, nonce_len); 381 os_memcpy(ptr + nonce_len, max, nonce_len); 382 ptr += 2 * nonce_len; 383 384 if (sta->my_lid < sta->peer_lid) { 385 min_lid = host_to_le16(sta->my_lid); 386 max_lid = host_to_le16(sta->peer_lid); 387 } else { 388 min_lid = host_to_le16(sta->peer_lid); 389 max_lid = host_to_le16(sta->my_lid); 390 } 391 os_memcpy(ptr, &min_lid, lid_len); 392 os_memcpy(ptr + lid_len, &max_lid, lid_len); 393 ptr += 2 * lid_len; 394 395 /* SAE */ 396 RSN_SELECTOR_PUT(ptr, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP)); 397 ptr += 4; 398 399 if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) { 400 min = myaddr; 401 max = peer; 402 } else { 403 min = peer; 404 max = myaddr; 405 } 406 os_memcpy(ptr, min, ETH_ALEN); 407 os_memcpy(ptr + ETH_ALEN, max, ETH_ALEN); 408 409 sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), 410 "Temporal Key Derivation", context, sizeof(context), 411 sta->mtk, sizeof(sta->mtk)); 412 return 0; 413 } 414 415 416 void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta) 417 { 418 if (random_get_bytes(sta->my_nonce, 32) < 0) { 419 wpa_printf(MSG_INFO, "mesh: Failed to derive random nonce"); 420 /* TODO: How to handle this more cleanly? */ 421 } 422 os_memset(sta->peer_nonce, 0, 32); 423 mesh_rsn_derive_aek(wpa_s->mesh_rsn, sta); 424 } 425 426 427 /* insert AMPE and encrypted MIC at @ie. 428 * @mesh_rsn: mesh RSN context 429 * @sta: STA we're sending to 430 * @cat: pointer to category code in frame header. 431 * @buf: wpabuf to add encrypted AMPE and MIC to. 432 * */ 433 int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta, 434 const u8 *cat, struct wpabuf *buf) 435 { 436 struct ieee80211_ampe_ie *ampe; 437 u8 const *ie = wpabuf_head_u8(buf) + wpabuf_len(buf); 438 u8 *ampe_ie = NULL, *mic_ie = NULL, *mic_payload; 439 const u8 *aad[] = { rsn->wpa_s->own_addr, sta->addr, cat }; 440 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, ie - cat }; 441 int ret = 0; 442 443 if (AES_BLOCK_SIZE + 2 + sizeof(*ampe) + 2 > wpabuf_tailroom(buf)) { 444 wpa_printf(MSG_ERROR, "protect frame: buffer too small"); 445 return -EINVAL; 446 } 447 448 ampe_ie = os_zalloc(2 + sizeof(*ampe)); 449 if (!ampe_ie) { 450 wpa_printf(MSG_ERROR, "protect frame: out of memory"); 451 return -ENOMEM; 452 } 453 454 mic_ie = os_zalloc(2 + AES_BLOCK_SIZE); 455 if (!mic_ie) { 456 wpa_printf(MSG_ERROR, "protect frame: out of memory"); 457 ret = -ENOMEM; 458 goto free; 459 } 460 461 /* IE: AMPE */ 462 ampe_ie[0] = WLAN_EID_AMPE; 463 ampe_ie[1] = sizeof(*ampe); 464 ampe = (struct ieee80211_ampe_ie *) (ampe_ie + 2); 465 466 RSN_SELECTOR_PUT(ampe->selected_pairwise_suite, 467 wpa_cipher_to_suite(WPA_PROTO_RSN, WPA_CIPHER_CCMP)); 468 os_memcpy(ampe->local_nonce, sta->my_nonce, 32); 469 os_memcpy(ampe->peer_nonce, sta->peer_nonce, 32); 470 /* incomplete: see 13.5.4 */ 471 /* TODO: static mgtk for now since we don't support rekeying! */ 472 os_memcpy(ampe->mgtk, rsn->mgtk, 16); 473 /* TODO: Populate Key RSC */ 474 /* expire in 13 decades or so */ 475 os_memset(ampe->key_expiration, 0xff, 4); 476 477 /* IE: MIC */ 478 mic_ie[0] = WLAN_EID_MIC; 479 mic_ie[1] = AES_BLOCK_SIZE; 480 wpabuf_put_data(buf, mic_ie, 2); 481 /* MIC field is output ciphertext */ 482 483 /* encrypt after MIC */ 484 mic_payload = (u8 *) wpabuf_put(buf, 2 + sizeof(*ampe) + 485 AES_BLOCK_SIZE); 486 487 if (aes_siv_encrypt(sta->aek, ampe_ie, 2 + sizeof(*ampe), 3, 488 aad, aad_len, mic_payload)) { 489 wpa_printf(MSG_ERROR, "protect frame: failed to encrypt"); 490 ret = -ENOMEM; 491 goto free; 492 } 493 494 free: 495 os_free(ampe_ie); 496 os_free(mic_ie); 497 498 return ret; 499 } 500 501 502 int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta, 503 struct ieee802_11_elems *elems, const u8 *cat, 504 const u8 *start, size_t elems_len) 505 { 506 int ret = 0; 507 struct ieee80211_ampe_ie *ampe; 508 u8 null_nonce[32] = {}; 509 u8 ampe_eid; 510 u8 ampe_ie_len; 511 u8 *ampe_buf, *crypt = NULL; 512 size_t crypt_len; 513 const u8 *aad[] = { sta->addr, wpa_s->own_addr, cat }; 514 const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, 515 (elems->mic - 2) - cat }; 516 517 if (!elems->mic || elems->mic_len < AES_BLOCK_SIZE) { 518 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing mic ie"); 519 return -1; 520 } 521 522 ampe_buf = (u8 *) elems->mic + elems->mic_len; 523 if ((int) elems_len < ampe_buf - start) 524 return -1; 525 526 crypt_len = elems_len - (elems->mic - start); 527 if (crypt_len < 2) { 528 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing ampe ie"); 529 return -1; 530 } 531 532 /* crypt is modified by siv_decrypt */ 533 crypt = os_zalloc(crypt_len); 534 if (!crypt) { 535 wpa_printf(MSG_ERROR, "Mesh RSN: out of memory"); 536 ret = -ENOMEM; 537 goto free; 538 } 539 540 os_memcpy(crypt, elems->mic, crypt_len); 541 542 if (aes_siv_decrypt(sta->aek, crypt, crypt_len, 3, 543 aad, aad_len, ampe_buf)) { 544 wpa_printf(MSG_ERROR, "Mesh RSN: frame verification failed!"); 545 ret = -1; 546 goto free; 547 } 548 549 ampe_eid = *ampe_buf++; 550 ampe_ie_len = *ampe_buf++; 551 552 if (ampe_eid != WLAN_EID_AMPE || 553 ampe_ie_len < sizeof(struct ieee80211_ampe_ie)) { 554 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid ampe ie"); 555 ret = -1; 556 goto free; 557 } 558 559 ampe = (struct ieee80211_ampe_ie *) ampe_buf; 560 if (os_memcmp(ampe->peer_nonce, null_nonce, 32) != 0 && 561 os_memcmp(ampe->peer_nonce, sta->my_nonce, 32) != 0) { 562 wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid peer nonce"); 563 ret = -1; 564 goto free; 565 } 566 os_memcpy(sta->peer_nonce, ampe->local_nonce, 567 sizeof(ampe->local_nonce)); 568 os_memcpy(sta->mgtk, ampe->mgtk, sizeof(ampe->mgtk)); 569 570 /* todo parse mgtk expiration */ 571 free: 572 os_free(crypt); 573 return ret; 574 } 575