wpa_supplicant/mesh_rsn.c

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