hostapd/pmksa_cache.c

   1 /*
   2  * hostapd - PMKSA cache for IEEE 802.11i RSN
   3  * Copyright (c) 2004-2008, 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 "ap.h"
  19 #include "config.h"
  20 #include "common.h"
  21 #include "eloop.h"
  22 #include "sha1.h"
  23 #include "sha256.h"
  24 #include "eapol_sm.h"
  25 #include "pmksa_cache.h"
  26
  27
  28 static const int pmksa_cache_max_entries = 1024;
  29 static const int dot11RSNAConfigPMKLifetime = 43200;
  30
  31 struct rsn_pmksa_cache {
  32 #define PMKID_HASH_SIZE 128
  33 #define PMKID_HASH(pmkid) (unsigned int) ((pmkid)[0] & 0x7f)
  34         struct rsn_pmksa_cache_entry *pmkid[PMKID_HASH_SIZE];
  35         struct rsn_pmksa_cache_entry *pmksa;
  36         int pmksa_count;
  37
  38         void (*free_cb)(struct rsn_pmksa_cache_entry *entry, void *ctx);
  39         void *ctx;
  40 };
  41
  42
  43 /**
  44  * rsn_pmkid - Calculate PMK identifier
  45  * @pmk: Pairwise master key
  46  * @pmk_len: Length of pmk in bytes
  47  * @aa: Authenticator address
  48  * @spa: Supplicant address
  49  * @pmkid: Buffer for PMKID
  50  * @use_sha256: Whether to use SHA256-based KDF
  51  *
  52  * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
  53  * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
  54  */
  55 void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa,
  56                u8 *pmkid, int use_sha256)
  57 {
  58         char *title = "PMK Name";
  59         const u8 *addr[3];
  60         const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
  61         unsigned char hash[SHA256_MAC_LEN];
  62
  63         addr[0] = (u8 *) title;
  64         addr[1] = aa;
  65         addr[2] = spa;
  66
  67 #ifdef CONFIG_IEEE80211W
  68         if (use_sha256)
  69                 hmac_sha256_vector(pmk, pmk_len, 3, addr, len, hash);
  70         else
  71 #endif /* CONFIG_IEEE80211W */
  72                 hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
  73         os_memcpy(pmkid, hash, PMKID_LEN);
  74 }
  75
  76
  77 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
  78
  79
  80 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
  81 {
  82         if (entry == NULL)
  83                 return;
  84         os_free(entry->identity);
  85         radius_free_class(&entry->radius_class);
  86         os_free(entry);
  87 }
  88
  89
  90 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
  91                                    struct rsn_pmksa_cache_entry *entry)
  92 {
  93         struct rsn_pmksa_cache_entry *pos, *prev;
  94
  95         pmksa->pmksa_count--;
  96         pmksa->free_cb(entry, pmksa->ctx);
  97         pos = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
  98         prev = NULL;
  99         while (pos) {
 100                 if (pos == entry) {
 101                         if (prev != NULL) {
 102                                 prev->hnext = pos->hnext;
 103                         } else {
 104                                 pmksa->pmkid[PMKID_HASH(entry->pmkid)] =
 105                                         pos->hnext;
 106                         }
 107                         break;
 108                 }
 109                 prev = pos;
 110                 pos = pos->hnext;
 111         }
 112
 113         pos = pmksa->pmksa;
 114         prev = NULL;
 115         while (pos) {
 116                 if (pos == entry) {
 117                         if (prev != NULL)
 118                                 prev->next = pos->next;
 119                         else
 120                                 pmksa->pmksa = pos->next;
 121                         break;
 122                 }
 123                 prev = pos;
 124                 pos = pos->next;
 125         }
 126         _pmksa_cache_free_entry(entry);
 127 }
 128
 129
 130 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
 131 {
 132         struct rsn_pmksa_cache *pmksa = eloop_ctx;
 133         struct os_time now;
 134
 135         os_get_time(&now);
 136         while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
 137                 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 138                 pmksa->pmksa = entry->next;
 139                 wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
 140                            MACSTR, MAC2STR(entry->spa));
 141                 pmksa_cache_free_entry(pmksa, entry);
 142         }
 143
 144         pmksa_cache_set_expiration(pmksa);
 145 }
 146
 147
 148 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
 149 {
 150         int sec;
 151         struct os_time now;
 152
 153         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 154         if (pmksa->pmksa == NULL)
 155                 return;
 156         os_get_time(&now);
 157         sec = pmksa->pmksa->expiration - now.sec;
 158         if (sec < 0)
 159                 sec = 0;
 160         eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
 161 }
 162
 163
 164 static void pmksa_cache_from_eapol_data(struct rsn_pmksa_cache_entry *entry,
 165                                         struct eapol_state_machine *eapol)
 166 {
 167         if (eapol == NULL)
 168                 return;
 169
 170         if (eapol->identity) {
 171                 entry->identity = os_malloc(eapol->identity_len);
 172                 if (entry->identity) {
 173                         entry->identity_len = eapol->identity_len;
 174                         os_memcpy(entry->identity, eapol->identity,
 175                                   eapol->identity_len);
 176                 }
 177         }
 178
 179         radius_copy_class(&entry->radius_class, &eapol->radius_class);
 180
 181         entry->eap_type_authsrv = eapol->eap_type_authsrv;
 182         entry->vlan_id = eapol->sta->vlan_id;
 183 }
 184
 185
 186 void pmksa_cache_to_eapol_data(struct rsn_pmksa_cache_entry *entry,
 187                                struct eapol_state_machine *eapol)
 188 {
 189         if (entry == NULL || eapol == NULL)
 190                 return;
 191
 192         if (entry->identity) {
 193                 os_free(eapol->identity);
 194                 eapol->identity = os_malloc(entry->identity_len);
 195                 if (eapol->identity) {
 196                         eapol->identity_len = entry->identity_len;
 197                         os_memcpy(eapol->identity, entry->identity,
 198                                   entry->identity_len);
 199                 }
 200                 wpa_hexdump_ascii(MSG_DEBUG, "STA identity from PMKSA",
 201                                   eapol->identity, eapol->identity_len);
 202         }
 203
 204         radius_free_class(&eapol->radius_class);
 205         radius_copy_class(&eapol->radius_class, &entry->radius_class);
 206         if (eapol->radius_class.attr) {
 207                 wpa_printf(MSG_DEBUG, "Copied %lu Class attribute(s) from "
 208                            "PMKSA", (unsigned long) eapol->radius_class.count);
 209         }
 210
 211         eapol->eap_type_authsrv = entry->eap_type_authsrv;
 212         eapol->sta->vlan_id = entry->vlan_id;
 213 }
 214
 215
 216 static void pmksa_cache_link_entry(struct rsn_pmksa_cache *pmksa,
 217                                    struct rsn_pmksa_cache_entry *entry)
 218 {
 219         struct rsn_pmksa_cache_entry *pos, *prev;
 220
 221         /* Add the new entry; order by expiration time */
 222         pos = pmksa->pmksa;
 223         prev = NULL;
 224         while (pos) {
 225                 if (pos->expiration > entry->expiration)
 226                         break;
 227                 prev = pos;
 228                 pos = pos->next;
 229         }
 230         if (prev == NULL) {
 231                 entry->next = pmksa->pmksa;
 232                 pmksa->pmksa = entry;
 233         } else {
 234                 entry->next = prev->next;
 235                 prev->next = entry;
 236         }
 237         entry->hnext = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
 238         pmksa->pmkid[PMKID_HASH(entry->pmkid)] = entry;
 239
 240         pmksa->pmksa_count++;
 241         wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
 242                    MAC2STR(entry->spa));
 243         wpa_hexdump(MSG_DEBUG, "RSN: added PMKID", entry->pmkid, PMKID_LEN);
 244 }
 245
 246
 247 /**
 248  * pmksa_cache_add - Add a PMKSA cache entry
 249  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 250  * @pmk: The new pairwise master key
 251  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
 252  * @aa: Authenticator address
 253  * @spa: Supplicant address
 254  * @session_timeout: Session timeout
 255  * @eapol: Pointer to EAPOL state machine data
 256  * @akmp: WPA_KEY_MGMT_* used in key derivation
 257  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
 258  *
 259  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
 260  * cache. If an old entry is already in the cache for the same Supplicant,
 261  * this entry will be replaced with the new entry. PMKID will be calculated
 262  * based on the PMK.
 263  */
 264 struct rsn_pmksa_cache_entry *
 265 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
 266                 const u8 *aa, const u8 *spa, int session_timeout,
 267                 struct eapol_state_machine *eapol, int akmp)
 268 {
 269         struct rsn_pmksa_cache_entry *entry, *pos;
 270         struct os_time now;
 271
 272         if (pmk_len > PMK_LEN)
 273                 return NULL;
 274
 275         entry = os_zalloc(sizeof(*entry));
 276         if (entry == NULL)
 277                 return NULL;
 278         os_memcpy(entry->pmk, pmk, pmk_len);
 279         entry->pmk_len = pmk_len;
 280         rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid,
 281                   wpa_key_mgmt_sha256(akmp));
 282         os_get_time(&now);
 283         entry->expiration = now.sec;
 284         if (session_timeout > 0)
 285                 entry->expiration += session_timeout;
 286         else
 287                 entry->expiration += dot11RSNAConfigPMKLifetime;
 288         entry->akmp = akmp;
 289         os_memcpy(entry->spa, spa, ETH_ALEN);
 290         pmksa_cache_from_eapol_data(entry, eapol);
 291
 292         /* Replace an old entry for the same STA (if found) with the new entry
 293          */
 294         pos = pmksa_cache_get(pmksa, spa, NULL);
 295         if (pos)
 296                 pmksa_cache_free_entry(pmksa, pos);
 297
 298         if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
 299                 /* Remove the oldest entry to make room for the new entry */
 300                 wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
 301                            "entry (for " MACSTR ") to make room for new one",
 302                            MAC2STR(pmksa->pmksa->spa));
 303                 pmksa_cache_free_entry(pmksa, pmksa->pmksa);
 304         }
 305
 306         pmksa_cache_link_entry(pmksa, entry);
 307
 308         return entry;
 309 }
 310
 311
 312 struct rsn_pmksa_cache_entry *
 313 pmksa_cache_add_okc(struct rsn_pmksa_cache *pmksa,
 314                     const struct rsn_pmksa_cache_entry *old_entry,
 315                     const u8 *aa, const u8 *pmkid)
 316 {
 317         struct rsn_pmksa_cache_entry *entry;
 318
 319         entry = os_zalloc(sizeof(*entry));
 320         if (entry == NULL)
 321                 return NULL;
 322         os_memcpy(entry->pmkid, pmkid, PMKID_LEN);
 323         os_memcpy(entry->pmk, old_entry->pmk, old_entry->pmk_len);
 324         entry->pmk_len = old_entry->pmk_len;
 325         entry->expiration = old_entry->expiration;
 326         entry->akmp = old_entry->akmp;
 327         os_memcpy(entry->spa, old_entry->spa, ETH_ALEN);
 328         entry->opportunistic = 1;
 329         if (old_entry->identity) {
 330                 entry->identity = os_malloc(old_entry->identity_len);
 331                 if (entry->identity) {
 332                         entry->identity_len = old_entry->identity_len;
 333                         os_memcpy(entry->identity, old_entry->identity,
 334                                   old_entry->identity_len);
 335                 }
 336         }
 337         radius_copy_class(&entry->radius_class, &old_entry->radius_class);
 338         entry->eap_type_authsrv = old_entry->eap_type_authsrv;
 339         entry->vlan_id = old_entry->vlan_id;
 340         entry->opportunistic = 1;
 341
 342         pmksa_cache_link_entry(pmksa, entry);
 343
 344         return entry;
 345 }
 346
 347
 348 /**
 349  * pmksa_cache_deinit - Free all entries in PMKSA cache
 350  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 351  */
 352 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
 353 {
 354         struct rsn_pmksa_cache_entry *entry, *prev;
 355         int i;
 356
 357         if (pmksa == NULL)
 358                 return;
 359
 360         entry = pmksa->pmksa;
 361         while (entry) {
 362                 prev = entry;
 363                 entry = entry->next;
 364                 _pmksa_cache_free_entry(prev);
 365         }
 366         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 367         for (i = 0; i < PMKID_HASH_SIZE; i++)
 368                 pmksa->pmkid[i] = NULL;
 369         os_free(pmksa);
 370 }
 371
 372
 373 /**
 374  * pmksa_cache_get - Fetch a PMKSA cache entry
 375  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 376  * @spa: Supplicant address or %NULL to match any
 377  * @pmkid: PMKID or %NULL to match any
 378  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
 379  */
 380 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
 381                                                const u8 *spa, const u8 *pmkid)
 382 {
 383         struct rsn_pmksa_cache_entry *entry;
 384
 385         if (pmkid)
 386                 entry = pmksa->pmkid[PMKID_HASH(pmkid)];
 387         else
 388                 entry = pmksa->pmksa;
 389         while (entry) {
 390                 if ((spa == NULL ||
 391                      os_memcmp(entry->spa, spa, ETH_ALEN) == 0) &&
 392                     (pmkid == NULL ||
 393                      os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
 394                         return entry;
 395                 entry = pmkid ? entry->hnext : entry->next;
 396         }
 397         return NULL;
 398 }
 399
 400
 401 /**
 402  * pmksa_cache_get_okc - Fetch a PMKSA cache entry using OKC
 403  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 404  * @aa: Authenticator address
 405  * @spa: Supplicant address
 406  * @pmkid: PMKID
 407  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
 408  *
 409  * Use opportunistic key caching (OKC) to find a PMK for a supplicant.
 410  */
 411 struct rsn_pmksa_cache_entry * pmksa_cache_get_okc(
 412         struct rsn_pmksa_cache *pmksa, const u8 *aa, const u8 *spa,
 413         const u8 *pmkid)
 414 {
 415         struct rsn_pmksa_cache_entry *entry;
 416         u8 new_pmkid[PMKID_LEN];
 417
 418         entry = pmksa->pmksa;
 419         while (entry) {
 420                 if (os_memcmp(entry->spa, spa, ETH_ALEN) != 0)
 421                         continue;
 422                 rsn_pmkid(entry->pmk, entry->pmk_len, aa, spa, new_pmkid,
 423                           wpa_key_mgmt_sha256(entry->akmp));
 424                 if (os_memcmp(new_pmkid, pmkid, PMKID_LEN) == 0)
 425                         return entry;
 426                 entry = entry->next;
 427         }
 428         return NULL;
 429 }
 430
 431
 432 /**
 433  * pmksa_cache_init - Initialize PMKSA cache
 434  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
 435  * @ctx: Context pointer for free_cb function
 436  * Returns: Pointer to PMKSA cache data or %NULL on failure
 437  */
 438 struct rsn_pmksa_cache *
 439 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
 440                                  void *ctx), void *ctx)
 441 {
 442         struct rsn_pmksa_cache *pmksa;
 443
 444         pmksa = os_zalloc(sizeof(*pmksa));
 445         if (pmksa) {
 446                 pmksa->free_cb = free_cb;
 447                 pmksa->ctx = ctx;
 448         }
 449
 450         return pmksa;
 451 }