hostapd/pmksa_cache.c

   1 /*
   2  * hostapd - PMKSA cache for IEEE 802.11i RSN
   3  * Copyright (c) 2004-2006, 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 "ieee802_1x.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  *
  50  * IEEE Std 802.11i-2004 - 8.5.1.2 Pairwise key hierarchy
  51  * PMKID = HMAC-SHA1-128(PMK, "PMK Name" || AA || SPA)
  52  */
  53 void rsn_pmkid(const u8 *pmk, size_t pmk_len, const u8 *aa, const u8 *spa,
  54                u8 *pmkid)
  55 {
  56         char *title = "PMK Name";
  57         const u8 *addr[3];
  58         const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
  59         unsigned char hash[SHA1_MAC_LEN];
  60
  61         addr[0] = (u8 *) title;
  62         addr[1] = aa;
  63         addr[2] = spa;
  64
  65         hmac_sha1_vector(pmk, pmk_len, 3, addr, len, hash);
  66         os_memcpy(pmkid, hash, PMKID_LEN);
  67 }
  68
  69
  70 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa);
  71
  72
  73 static void _pmksa_cache_free_entry(struct rsn_pmksa_cache_entry *entry)
  74 {
  75         if (entry == NULL)
  76                 return;
  77         os_free(entry->identity);
  78         ieee802_1x_free_radius_class(&entry->radius_class);
  79         os_free(entry);
  80 }
  81
  82
  83 static void pmksa_cache_free_entry(struct rsn_pmksa_cache *pmksa,
  84                                    struct rsn_pmksa_cache_entry *entry)
  85 {
  86         struct rsn_pmksa_cache_entry *pos, *prev;
  87
  88         pmksa->pmksa_count--;
  89         pmksa->free_cb(entry, pmksa->ctx);
  90         pos = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
  91         prev = NULL;
  92         while (pos) {
  93                 if (pos == entry) {
  94                         if (prev != NULL) {
  95                                 prev->hnext = pos->hnext;
  96                         } else {
  97                                 pmksa->pmkid[PMKID_HASH(entry->pmkid)] =
  98                                         pos->hnext;
  99                         }
 100                         break;
 101                 }
 102                 prev = pos;
 103                 pos = pos->hnext;
 104         }
 105
 106         pos = pmksa->pmksa;
 107         prev = NULL;
 108         while (pos) {
 109                 if (pos == entry) {
 110                         if (prev != NULL)
 111                                 prev->next = pos->next;
 112                         else
 113                                 pmksa->pmksa = pos->next;
 114                         break;
 115                 }
 116                 prev = pos;
 117                 pos = pos->next;
 118         }
 119         _pmksa_cache_free_entry(entry);
 120 }
 121
 122
 123 static void pmksa_cache_expire(void *eloop_ctx, void *timeout_ctx)
 124 {
 125         struct rsn_pmksa_cache *pmksa = eloop_ctx;
 126         struct os_time now;
 127
 128         os_get_time(&now);
 129         while (pmksa->pmksa && pmksa->pmksa->expiration <= now.sec) {
 130                 struct rsn_pmksa_cache_entry *entry = pmksa->pmksa;
 131                 pmksa->pmksa = entry->next;
 132                 wpa_printf(MSG_DEBUG, "RSN: expired PMKSA cache entry for "
 133                            MACSTR, MAC2STR(entry->spa));
 134                 pmksa_cache_free_entry(pmksa, entry);
 135         }
 136
 137         pmksa_cache_set_expiration(pmksa);
 138 }
 139
 140
 141 static void pmksa_cache_set_expiration(struct rsn_pmksa_cache *pmksa)
 142 {
 143         int sec;
 144         struct os_time now;
 145
 146         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 147         if (pmksa->pmksa == NULL)
 148                 return;
 149         os_get_time(&now);
 150         sec = pmksa->pmksa->expiration - now.sec;
 151         if (sec < 0)
 152                 sec = 0;
 153         eloop_register_timeout(sec + 1, 0, pmksa_cache_expire, pmksa, NULL);
 154 }
 155
 156
 157 static void pmksa_cache_from_eapol_data(struct rsn_pmksa_cache_entry *entry,
 158                                         struct eapol_state_machine *eapol)
 159 {
 160         if (eapol == NULL)
 161                 return;
 162
 163         if (eapol->identity) {
 164                 entry->identity = os_malloc(eapol->identity_len);
 165                 if (entry->identity) {
 166                         entry->identity_len = eapol->identity_len;
 167                         os_memcpy(entry->identity, eapol->identity,
 168                                   eapol->identity_len);
 169                 }
 170         }
 171
 172         ieee802_1x_copy_radius_class(&entry->radius_class,
 173                                      &eapol->radius_class);
 174
 175         entry->eap_type_authsrv = eapol->eap_type_authsrv;
 176         entry->vlan_id = eapol->sta->vlan_id;
 177 }
 178
 179
 180 void pmksa_cache_to_eapol_data(struct rsn_pmksa_cache_entry *entry,
 181                                struct eapol_state_machine *eapol)
 182 {
 183         if (entry == NULL || eapol == NULL)
 184                 return;
 185
 186         if (entry->identity) {
 187                 os_free(eapol->identity);
 188                 eapol->identity = os_malloc(entry->identity_len);
 189                 if (eapol->identity) {
 190                         eapol->identity_len = entry->identity_len;
 191                         os_memcpy(eapol->identity, entry->identity,
 192                                   entry->identity_len);
 193                 }
 194                 wpa_hexdump_ascii(MSG_DEBUG, "STA identity from PMKSA",
 195                                   eapol->identity, eapol->identity_len);
 196         }
 197
 198         ieee802_1x_free_radius_class(&eapol->radius_class);
 199         ieee802_1x_copy_radius_class(&eapol->radius_class,
 200                                      &entry->radius_class);
 201         if (eapol->radius_class.attr) {
 202                 wpa_printf(MSG_DEBUG, "Copied %lu Class attribute(s) from "
 203                            "PMKSA", (unsigned long) eapol->radius_class.count);
 204         }
 205
 206         eapol->eap_type_authsrv = entry->eap_type_authsrv;
 207         eapol->sta->vlan_id = entry->vlan_id;
 208 }
 209
 210
 211 /**
 212  * pmksa_cache_add - Add a PMKSA cache entry
 213  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 214  * @pmk: The new pairwise master key
 215  * @pmk_len: PMK length in bytes, usually PMK_LEN (32)
 216  * @aa: Authenticator address
 217  * @spa: Supplicant address
 218  * @session_timeout: Session timeout
 219  * @eapol: Pointer to EAPOL state machine data
 220  * Returns: Pointer to the added PMKSA cache entry or %NULL on error
 221  *
 222  * This function create a PMKSA entry for a new PMK and adds it to the PMKSA
 223  * cache. If an old entry is already in the cache for the same Supplicant,
 224  * this entry will be replaced with the new entry. PMKID will be calculated
 225  * based on the PMK.
 226  */
 227 struct rsn_pmksa_cache_entry *
 228 pmksa_cache_add(struct rsn_pmksa_cache *pmksa, const u8 *pmk, size_t pmk_len,
 229                 const u8 *aa, const u8 *spa, int session_timeout,
 230                 struct eapol_state_machine *eapol)
 231 {
 232         struct rsn_pmksa_cache_entry *entry, *pos, *prev;
 233         struct os_time now;
 234
 235         if (pmk_len > PMK_LEN)
 236                 return NULL;
 237
 238         entry = os_zalloc(sizeof(*entry));
 239         if (entry == NULL)
 240                 return NULL;
 241         os_memcpy(entry->pmk, pmk, pmk_len);
 242         entry->pmk_len = pmk_len;
 243         rsn_pmkid(pmk, pmk_len, aa, spa, entry->pmkid);
 244         os_get_time(&now);
 245         entry->expiration = now.sec;
 246         if (session_timeout > 0)
 247                 entry->expiration += session_timeout;
 248         else
 249                 entry->expiration += dot11RSNAConfigPMKLifetime;
 250         entry->akmp = WPA_KEY_MGMT_IEEE8021X;
 251         os_memcpy(entry->spa, spa, ETH_ALEN);
 252         pmksa_cache_from_eapol_data(entry, eapol);
 253
 254         /* Replace an old entry for the same STA (if found) with the new entry
 255          */
 256         pos = pmksa_cache_get(pmksa, spa, NULL);
 257         if (pos)
 258                 pmksa_cache_free_entry(pmksa, pos);
 259
 260         if (pmksa->pmksa_count >= pmksa_cache_max_entries && pmksa->pmksa) {
 261                 /* Remove the oldest entry to make room for the new entry */
 262                 wpa_printf(MSG_DEBUG, "RSN: removed the oldest PMKSA cache "
 263                            "entry (for " MACSTR ") to make room for new one",
 264                            MAC2STR(pmksa->pmksa->spa));
 265                 pmksa_cache_free_entry(pmksa, pmksa->pmksa);
 266         }
 267
 268         /* Add the new entry; order by expiration time */
 269         pos = pmksa->pmksa;
 270         prev = NULL;
 271         while (pos) {
 272                 if (pos->expiration > entry->expiration)
 273                         break;
 274                 prev = pos;
 275                 pos = pos->next;
 276         }
 277         if (prev == NULL) {
 278                 entry->next = pmksa->pmksa;
 279                 pmksa->pmksa = entry;
 280         } else {
 281                 entry->next = prev->next;
 282                 prev->next = entry;
 283         }
 284         entry->hnext = pmksa->pmkid[PMKID_HASH(entry->pmkid)];
 285         pmksa->pmkid[PMKID_HASH(entry->pmkid)] = entry;
 286
 287         pmksa->pmksa_count++;
 288         wpa_printf(MSG_DEBUG, "RSN: added PMKSA cache entry for " MACSTR,
 289                    MAC2STR(entry->spa));
 290         wpa_hexdump(MSG_DEBUG, "RSN: added PMKID", entry->pmkid, PMKID_LEN);
 291
 292         return entry;
 293 }
 294
 295
 296 /**
 297  * pmksa_cache_deinit - Free all entries in PMKSA cache
 298  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 299  */
 300 void pmksa_cache_deinit(struct rsn_pmksa_cache *pmksa)
 301 {
 302         struct rsn_pmksa_cache_entry *entry, *prev;
 303         int i;
 304
 305         if (pmksa == NULL)
 306                 return;
 307
 308         entry = pmksa->pmksa;
 309         while (entry) {
 310                 prev = entry;
 311                 entry = entry->next;
 312                 _pmksa_cache_free_entry(prev);
 313         }
 314         eloop_cancel_timeout(pmksa_cache_expire, pmksa, NULL);
 315         for (i = 0; i < PMKID_HASH_SIZE; i++)
 316                 pmksa->pmkid[i] = NULL;
 317         os_free(pmksa);
 318 }
 319
 320
 321 /**
 322  * pmksa_cache_get - Fetch a PMKSA cache entry
 323  * @pmksa: Pointer to PMKSA cache data from pmksa_cache_init()
 324  * @spa: Supplicant address or %NULL to match any
 325  * @pmkid: PMKID or %NULL to match any
 326  * Returns: Pointer to PMKSA cache entry or %NULL if no match was found
 327  */
 328 struct rsn_pmksa_cache_entry * pmksa_cache_get(struct rsn_pmksa_cache *pmksa,
 329                                                const u8 *spa, const u8 *pmkid)
 330 {
 331         struct rsn_pmksa_cache_entry *entry;
 332
 333         if (pmkid)
 334                 entry = pmksa->pmkid[PMKID_HASH(pmkid)];
 335         else
 336                 entry = pmksa->pmksa;
 337         while (entry) {
 338                 if ((spa == NULL ||
 339                      os_memcmp(entry->spa, spa, ETH_ALEN) == 0) &&
 340                     (pmkid == NULL ||
 341                      os_memcmp(entry->pmkid, pmkid, PMKID_LEN) == 0))
 342                         return entry;
 343                 entry = pmkid ? entry->hnext : entry->next;
 344         }
 345         return NULL;
 346 }
 347
 348
 349 /**
 350  * pmksa_cache_init - Initialize PMKSA cache
 351  * @free_cb: Callback function to be called when a PMKSA cache entry is freed
 352  * @ctx: Context pointer for free_cb function
 353  * Returns: Pointer to PMKSA cache data or %NULL on failure
 354  */
 355 struct rsn_pmksa_cache *
 356 pmksa_cache_init(void (*free_cb)(struct rsn_pmksa_cache_entry *entry,
 357                                  void *ctx), void *ctx)
 358 {
 359         struct rsn_pmksa_cache *pmksa;
 360
 361         pmksa = os_zalloc(sizeof(*pmksa));
 362         if (pmksa) {
 363                 pmksa->free_cb = free_cb;
 364                 pmksa->ctx = ctx;
 365         }
 366
 367         return pmksa;
 368 }