net/wireless/util.c

   1 /*
   2  * Wireless utility functions
   3  *
   4  * Copyright 2007-2009  Johannes Berg <johannes@sipsolutions.net>
   5  */
   6 #include <linux/export.h>
   7 #include <linux/bitops.h>
   8 #include <linux/etherdevice.h>
   9 #include <linux/slab.h>
  10 #include <linux/crc32.h>
  11 #include <net/cfg80211.h>
  12 #include <net/ip.h>
  13 #include "core.h"
  14
  15 struct ieee80211_rate *
  16 ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
  17                             u32 basic_rates, int bitrate)
  18 {
  19         struct ieee80211_rate *result = &sband->bitrates[0];
  20         int i;
  21
  22         for (i = 0; i < sband->n_bitrates; i++) {
  23                 if (!(basic_rates & BIT(i)))
  24                         continue;
  25                 if (sband->bitrates[i].bitrate > bitrate)
  26                         continue;
  27                 result = &sband->bitrates[i];
  28         }
  29
  30         return result;
  31 }
  32 EXPORT_SYMBOL(ieee80211_get_response_rate);
  33
  34 int ieee80211_channel_to_frequency(int chan, enum ieee80211_band band)
  35 {
  36         /* see 802.11 17.3.8.3.2 and Annex J
  37          * there are overlapping channel numbers in 5GHz and 2GHz bands */
  38         if (band == IEEE80211_BAND_5GHZ) {
  39                 if (chan >= 182 && chan <= 196)
  40                         return 4000 + chan * 5;
  41                 else
  42                         return 5000 + chan * 5;
  43         } else { /* IEEE80211_BAND_2GHZ */
  44                 if (chan == 14)
  45                         return 2484;
  46                 else if (chan < 14)
  47                         return 2407 + chan * 5;
  48                 else
  49                         return 0; /* not supported */
  50         }
  51 }
  52 EXPORT_SYMBOL(ieee80211_channel_to_frequency);
  53
  54 int ieee80211_frequency_to_channel(int freq)
  55 {
  56         /* see 802.11 17.3.8.3.2 and Annex J */
  57         if (freq == 2484)
  58                 return 14;
  59         else if (freq < 2484)
  60                 return (freq - 2407) / 5;
  61         else if (freq >= 4910 && freq <= 4980)
  62                 return (freq - 4000) / 5;
  63         else
  64                 return (freq - 5000) / 5;
  65 }
  66 EXPORT_SYMBOL(ieee80211_frequency_to_channel);
  67
  68 struct ieee80211_channel *__ieee80211_get_channel(struct wiphy *wiphy,
  69                                                   int freq)
  70 {
  71         enum ieee80211_band band;
  72         struct ieee80211_supported_band *sband;
  73         int i;
  74
  75         for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
  76                 sband = wiphy->bands[band];
  77
  78                 if (!sband)
  79                         continue;
  80
  81                 for (i = 0; i < sband->n_channels; i++) {
  82                         if (sband->channels[i].center_freq == freq)
  83                                 return &sband->channels[i];
  84                 }
  85         }
  86
  87         return NULL;
  88 }
  89 EXPORT_SYMBOL(__ieee80211_get_channel);
  90
  91 static void set_mandatory_flags_band(struct ieee80211_supported_band *sband,
  92                                      enum ieee80211_band band)
  93 {
  94         int i, want;
  95
  96         switch (band) {
  97         case IEEE80211_BAND_5GHZ:
  98                 want = 3;
  99                 for (i = 0; i < sband->n_bitrates; i++) {
 100                         if (sband->bitrates[i].bitrate == 60 ||
 101                             sband->bitrates[i].bitrate == 120 ||
 102                             sband->bitrates[i].bitrate == 240) {
 103                                 sband->bitrates[i].flags |=
 104                                         IEEE80211_RATE_MANDATORY_A;
 105                                 want--;
 106                         }
 107                 }
 108                 WARN_ON(want);
 109                 break;
 110         case IEEE80211_BAND_2GHZ:
 111                 want = 7;
 112                 for (i = 0; i < sband->n_bitrates; i++) {
 113                         if (sband->bitrates[i].bitrate == 10) {
 114                                 sband->bitrates[i].flags |=
 115                                         IEEE80211_RATE_MANDATORY_B |
 116                                         IEEE80211_RATE_MANDATORY_G;
 117                                 want--;
 118                         }
 119
 120                         if (sband->bitrates[i].bitrate == 20 ||
 121                             sband->bitrates[i].bitrate == 55 ||
 122                             sband->bitrates[i].bitrate == 110 ||
 123                             sband->bitrates[i].bitrate == 60 ||
 124                             sband->bitrates[i].bitrate == 120 ||
 125                             sband->bitrates[i].bitrate == 240) {
 126                                 sband->bitrates[i].flags |=
 127                                         IEEE80211_RATE_MANDATORY_G;
 128                                 want--;
 129                         }
 130
 131                         if (sband->bitrates[i].bitrate != 10 &&
 132                             sband->bitrates[i].bitrate != 20 &&
 133                             sband->bitrates[i].bitrate != 55 &&
 134                             sband->bitrates[i].bitrate != 110)
 135                                 sband->bitrates[i].flags |=
 136                                         IEEE80211_RATE_ERP_G;
 137                 }
 138                 WARN_ON(want != 0 && want != 3 && want != 6);
 139                 break;
 140         case IEEE80211_NUM_BANDS:
 141                 WARN_ON(1);
 142                 break;
 143         }
 144 }
 145
 146 void ieee80211_set_bitrate_flags(struct wiphy *wiphy)
 147 {
 148         enum ieee80211_band band;
 149
 150         for (band = 0; band < IEEE80211_NUM_BANDS; band++)
 151                 if (wiphy->bands[band])
 152                         set_mandatory_flags_band(wiphy->bands[band], band);
 153 }
 154
 155 bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher)
 156 {
 157         int i;
 158         for (i = 0; i < wiphy->n_cipher_suites; i++)
 159                 if (cipher == wiphy->cipher_suites[i])
 160                         return true;
 161         return false;
 162 }
 163
 164 int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
 165                                    struct key_params *params, int key_idx,
 166                                    bool pairwise, const u8 *mac_addr)
 167 {
 168         if (key_idx > 5)
 169                 return -EINVAL;
 170
 171         if (!pairwise && mac_addr && !(rdev->wiphy.flags & WIPHY_FLAG_IBSS_RSN))
 172                 return -EINVAL;
 173
 174         if (pairwise && !mac_addr)
 175                 return -EINVAL;
 176
 177         /*
 178          * Disallow pairwise keys with non-zero index unless it's WEP
 179          * or a vendor specific cipher (because current deployments use
 180          * pairwise WEP keys with non-zero indices and for vendor specific
 181          * ciphers this should be validated in the driver or hardware level
 182          * - but 802.11i clearly specifies to use zero)
 183          */
 184         if (pairwise && key_idx &&
 185             ((params->cipher == WLAN_CIPHER_SUITE_TKIP) ||
 186              (params->cipher == WLAN_CIPHER_SUITE_CCMP) ||
 187              (params->cipher == WLAN_CIPHER_SUITE_AES_CMAC)))
 188                 return -EINVAL;
 189
 190         switch (params->cipher) {
 191         case WLAN_CIPHER_SUITE_WEP40:
 192                 if (params->key_len != WLAN_KEY_LEN_WEP40)
 193                         return -EINVAL;
 194                 break;
 195         case WLAN_CIPHER_SUITE_TKIP:
 196                 if (params->key_len != WLAN_KEY_LEN_TKIP)
 197                         return -EINVAL;
 198                 break;
 199         case WLAN_CIPHER_SUITE_CCMP:
 200                 if (params->key_len != WLAN_KEY_LEN_CCMP)
 201                         return -EINVAL;
 202                 break;
 203         case WLAN_CIPHER_SUITE_WEP104:
 204                 if (params->key_len != WLAN_KEY_LEN_WEP104)
 205                         return -EINVAL;
 206                 break;
 207         case WLAN_CIPHER_SUITE_AES_CMAC:
 208                 if (params->key_len != WLAN_KEY_LEN_AES_CMAC)
 209                         return -EINVAL;
 210                 break;
 211         default:
 212                 /*
 213                  * We don't know anything about this algorithm,
 214                  * allow using it -- but the driver must check
 215                  * all parameters! We still check below whether
 216                  * or not the driver supports this algorithm,
 217                  * of course.
 218                  */
 219                 break;
 220         }
 221
 222         if (params->seq) {
 223                 switch (params->cipher) {
 224                 case WLAN_CIPHER_SUITE_WEP40:
 225                 case WLAN_CIPHER_SUITE_WEP104:
 226                         /* These ciphers do not use key sequence */
 227                         return -EINVAL;
 228                 case WLAN_CIPHER_SUITE_TKIP:
 229                 case WLAN_CIPHER_SUITE_CCMP:
 230                 case WLAN_CIPHER_SUITE_AES_CMAC:
 231                         if (params->seq_len != 6)
 232                                 return -EINVAL;
 233                         break;
 234                 }
 235         }
 236
 237         if (!cfg80211_supported_cipher_suite(&rdev->wiphy, params->cipher))
 238                 return -EINVAL;
 239
 240         return 0;
 241 }
 242
 243 /* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
 244 /* Ethernet-II snap header (RFC1042 for most EtherTypes) */
 245 const unsigned char rfc1042_header[] __aligned(2) =
 246         { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
 247 EXPORT_SYMBOL(rfc1042_header);
 248
 249 /* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
 250 const unsigned char bridge_tunnel_header[] __aligned(2) =
 251         { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
 252 EXPORT_SYMBOL(bridge_tunnel_header);
 253
 254 unsigned int __attribute_const__ ieee80211_hdrlen(__le16 fc)
 255 {
 256         unsigned int hdrlen = 24;
 257
 258         if (ieee80211_is_data(fc)) {
 259                 if (ieee80211_has_a4(fc))
 260                         hdrlen = 30;
 261                 if (ieee80211_is_data_qos(fc)) {
 262                         hdrlen += IEEE80211_QOS_CTL_LEN;
 263                         if (ieee80211_has_order(fc))
 264                                 hdrlen += IEEE80211_HT_CTL_LEN;
 265                 }
 266                 goto out;
 267         }
 268
 269         if (ieee80211_is_ctl(fc)) {
 270                 /*
 271                  * ACK and CTS are 10 bytes, all others 16. To see how
 272                  * to get this condition consider
 273                  *   subtype mask:   0b0000000011110000 (0x00F0)
 274                  *   ACK subtype:    0b0000000011010000 (0x00D0)
 275                  *   CTS subtype:    0b0000000011000000 (0x00C0)
 276                  *   bits that matter:         ^^^      (0x00E0)
 277                  *   value of those: 0b0000000011000000 (0x00C0)
 278                  */
 279                 if ((fc & cpu_to_le16(0x00E0)) == cpu_to_le16(0x00C0))
 280                         hdrlen = 10;
 281                 else
 282                         hdrlen = 16;
 283         }
 284 out:
 285         return hdrlen;
 286 }
 287 EXPORT_SYMBOL(ieee80211_hdrlen);
 288
 289 unsigned int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
 290 {
 291         const struct ieee80211_hdr *hdr =
 292                         (const struct ieee80211_hdr *)skb->data;
 293         unsigned int hdrlen;
 294
 295         if (unlikely(skb->len < 10))
 296                 return 0;
 297         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 298         if (unlikely(hdrlen > skb->len))
 299                 return 0;
 300         return hdrlen;
 301 }
 302 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);
 303
 304 unsigned int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 305 {
 306         int ae = meshhdr->flags & MESH_FLAGS_AE;
 307         /* 802.11-2012, 8.2.4.7.3 */
 308         switch (ae) {
 309         default:
 310         case 0:
 311                 return 6;
 312         case MESH_FLAGS_AE_A4:
 313                 return 12;
 314         case MESH_FLAGS_AE_A5_A6:
 315                 return 18;
 316         }
 317 }
 318 EXPORT_SYMBOL(ieee80211_get_mesh_hdrlen);
 319
 320 int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
 321                            enum nl80211_iftype iftype)
 322 {
 323         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 324         u16 hdrlen, ethertype;
 325         u8 *payload;
 326         u8 dst[ETH_ALEN];
 327         u8 src[ETH_ALEN] __aligned(2);
 328
 329         if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
 330                 return -1;
 331
 332         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 333
 334         /* convert IEEE 802.11 header + possible LLC headers into Ethernet
 335          * header
 336          * IEEE 802.11 address fields:
 337          * ToDS FromDS Addr1 Addr2 Addr3 Addr4
 338          *   0     0   DA    SA    BSSID n/a
 339          *   0     1   DA    BSSID SA    n/a
 340          *   1     0   BSSID SA    DA    n/a
 341          *   1     1   RA    TA    DA    SA
 342          */
 343         memcpy(dst, ieee80211_get_DA(hdr), ETH_ALEN);
 344         memcpy(src, ieee80211_get_SA(hdr), ETH_ALEN);
 345
 346         switch (hdr->frame_control &
 347                 cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 348         case cpu_to_le16(IEEE80211_FCTL_TODS):
 349                 if (unlikely(iftype != NL80211_IFTYPE_AP &&
 350                              iftype != NL80211_IFTYPE_AP_VLAN &&
 351                              iftype != NL80211_IFTYPE_P2P_GO))
 352                         return -1;
 353                 break;
 354         case cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
 355                 if (unlikely(iftype != NL80211_IFTYPE_WDS &&
 356                              iftype != NL80211_IFTYPE_MESH_POINT &&
 357                              iftype != NL80211_IFTYPE_AP_VLAN &&
 358                              iftype != NL80211_IFTYPE_STATION))
 359                         return -1;
 360                 if (iftype == NL80211_IFTYPE_MESH_POINT) {
 361                         struct ieee80211s_hdr *meshdr =
 362                                 (struct ieee80211s_hdr *) (skb->data + hdrlen);
 363                         /* make sure meshdr->flags is on the linear part */
 364                         if (!pskb_may_pull(skb, hdrlen + 1))
 365                                 return -1;
 366                         if (meshdr->flags & MESH_FLAGS_AE_A4)
 367                                 return -1;
 368                         if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
 369                                 skb_copy_bits(skb, hdrlen +
 370                                         offsetof(struct ieee80211s_hdr, eaddr1),
 371                                         dst, ETH_ALEN);
 372                                 skb_copy_bits(skb, hdrlen +
 373                                         offsetof(struct ieee80211s_hdr, eaddr2),
 374                                         src, ETH_ALEN);
 375                         }
 376                         hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
 377                 }
 378                 break;
 379         case cpu_to_le16(IEEE80211_FCTL_FROMDS):
 380                 if ((iftype != NL80211_IFTYPE_STATION &&
 381                      iftype != NL80211_IFTYPE_P2P_CLIENT &&
 382                      iftype != NL80211_IFTYPE_MESH_POINT) ||
 383                     (is_multicast_ether_addr(dst) &&
 384                      !compare_ether_addr(src, addr)))
 385                         return -1;
 386                 if (iftype == NL80211_IFTYPE_MESH_POINT) {
 387                         struct ieee80211s_hdr *meshdr =
 388                                 (struct ieee80211s_hdr *) (skb->data + hdrlen);
 389                         /* make sure meshdr->flags is on the linear part */
 390                         if (!pskb_may_pull(skb, hdrlen + 1))
 391                                 return -1;
 392                         if (meshdr->flags & MESH_FLAGS_AE_A5_A6)
 393                                 return -1;
 394                         if (meshdr->flags & MESH_FLAGS_AE_A4)
 395                                 skb_copy_bits(skb, hdrlen +
 396                                         offsetof(struct ieee80211s_hdr, eaddr1),
 397                                         src, ETH_ALEN);
 398                         hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
 399                 }
 400                 break;
 401         case cpu_to_le16(0):
 402                 if (iftype != NL80211_IFTYPE_ADHOC &&
 403                     iftype != NL80211_IFTYPE_STATION)
 404                                 return -1;
 405                 break;
 406         }
 407
 408         if (!pskb_may_pull(skb, hdrlen + 8))
 409                 return -1;
 410
 411         payload = skb->data + hdrlen;
 412         ethertype = (payload[6] << 8) | payload[7];
 413
 414         if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
 415                     ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
 416                    compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
 417                 /* remove RFC1042 or Bridge-Tunnel encapsulation and
 418                  * replace EtherType */
 419                 skb_pull(skb, hdrlen + 6);
 420                 memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
 421                 memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
 422         } else {
 423                 struct ethhdr *ehdr;
 424                 __be16 len;
 425
 426                 skb_pull(skb, hdrlen);
 427                 len = htons(skb->len);
 428                 ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
 429                 memcpy(ehdr->h_dest, dst, ETH_ALEN);
 430                 memcpy(ehdr->h_source, src, ETH_ALEN);
 431                 ehdr->h_proto = len;
 432         }
 433         return 0;
 434 }
 435 EXPORT_SYMBOL(ieee80211_data_to_8023);
 436
 437 int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr,
 438                              enum nl80211_iftype iftype, u8 *bssid, bool qos)
 439 {
 440         struct ieee80211_hdr hdr;
 441         u16 hdrlen, ethertype;
 442         __le16 fc;
 443         const u8 *encaps_data;
 444         int encaps_len, skip_header_bytes;
 445         int nh_pos, h_pos;
 446         int head_need;
 447
 448         if (unlikely(skb->len < ETH_HLEN))
 449                 return -EINVAL;
 450
 451         nh_pos = skb_network_header(skb) - skb->data;
 452         h_pos = skb_transport_header(skb) - skb->data;
 453
 454         /* convert Ethernet header to proper 802.11 header (based on
 455          * operation mode) */
 456         ethertype = (skb->data[12] << 8) | skb->data[13];
 457         fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);
 458
 459         switch (iftype) {
 460         case NL80211_IFTYPE_AP:
 461         case NL80211_IFTYPE_AP_VLAN:
 462         case NL80211_IFTYPE_P2P_GO:
 463                 fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
 464                 /* DA BSSID SA */
 465                 memcpy(hdr.addr1, skb->data, ETH_ALEN);
 466                 memcpy(hdr.addr2, addr, ETH_ALEN);
 467                 memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
 468                 hdrlen = 24;
 469                 break;
 470         case NL80211_IFTYPE_STATION:
 471         case NL80211_IFTYPE_P2P_CLIENT:
 472                 fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 473                 /* BSSID SA DA */
 474                 memcpy(hdr.addr1, bssid, ETH_ALEN);
 475                 memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 476                 memcpy(hdr.addr3, skb->data, ETH_ALEN);
 477                 hdrlen = 24;
 478                 break;
 479         case NL80211_IFTYPE_ADHOC:
 480                 /* DA SA BSSID */
 481                 memcpy(hdr.addr1, skb->data, ETH_ALEN);
 482                 memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 483                 memcpy(hdr.addr3, bssid, ETH_ALEN);
 484                 hdrlen = 24;
 485                 break;
 486         default:
 487                 return -EOPNOTSUPP;
 488         }
 489
 490         if (qos) {
 491                 fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
 492                 hdrlen += 2;
 493         }
 494
 495         hdr.frame_control = fc;
 496         hdr.duration_id = 0;
 497         hdr.seq_ctrl = 0;
 498
 499         skip_header_bytes = ETH_HLEN;
 500         if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
 501                 encaps_data = bridge_tunnel_header;
 502                 encaps_len = sizeof(bridge_tunnel_header);
 503                 skip_header_bytes -= 2;
 504         } else if (ethertype > 0x600) {
 505                 encaps_data = rfc1042_header;
 506                 encaps_len = sizeof(rfc1042_header);
 507                 skip_header_bytes -= 2;
 508         } else {
 509                 encaps_data = NULL;
 510                 encaps_len = 0;
 511         }
 512
 513         skb_pull(skb, skip_header_bytes);
 514         nh_pos -= skip_header_bytes;
 515         h_pos -= skip_header_bytes;
 516
 517         head_need = hdrlen + encaps_len - skb_headroom(skb);
 518
 519         if (head_need > 0 || skb_cloned(skb)) {
 520                 head_need = max(head_need, 0);
 521                 if (head_need)
 522                         skb_orphan(skb);
 523
 524                 if (pskb_expand_head(skb, head_need, 0, GFP_ATOMIC))
 525                         return -ENOMEM;
 526
 527                 skb->truesize += head_need;
 528         }
 529
 530         if (encaps_data) {
 531                 memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
 532                 nh_pos += encaps_len;
 533                 h_pos += encaps_len;
 534         }
 535
 536         memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);
 537
 538         nh_pos += hdrlen;
 539         h_pos += hdrlen;
 540
 541         /* Update skb pointers to various headers since this modified frame
 542          * is going to go through Linux networking code that may potentially
 543          * need things like pointer to IP header. */
 544         skb_set_mac_header(skb, 0);
 545         skb_set_network_header(skb, nh_pos);
 546         skb_set_transport_header(skb, h_pos);
 547
 548         return 0;
 549 }
 550 EXPORT_SYMBOL(ieee80211_data_from_8023);
 551
 552
 553 void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
 554                               const u8 *addr, enum nl80211_iftype iftype,
 555                               const unsigned int extra_headroom,
 556                               bool has_80211_header)
 557 {
 558         struct sk_buff *frame = NULL;
 559         u16 ethertype;
 560         u8 *payload;
 561         const struct ethhdr *eth;
 562         int remaining, err;
 563         u8 dst[ETH_ALEN], src[ETH_ALEN];
 564
 565         if (has_80211_header) {
 566                 err = ieee80211_data_to_8023(skb, addr, iftype);
 567                 if (err)
 568                         goto out;
 569
 570                 /* skip the wrapping header */
 571                 eth = (struct ethhdr *) skb_pull(skb, sizeof(struct ethhdr));
 572                 if (!eth)
 573                         goto out;
 574         } else {
 575                 eth = (struct ethhdr *) skb->data;
 576         }
 577
 578         while (skb != frame) {
 579                 u8 padding;
 580                 __be16 len = eth->h_proto;
 581                 unsigned int subframe_len = sizeof(struct ethhdr) + ntohs(len);
 582
 583                 remaining = skb->len;
 584                 memcpy(dst, eth->h_dest, ETH_ALEN);
 585                 memcpy(src, eth->h_source, ETH_ALEN);
 586
 587                 padding = (4 - subframe_len) & 0x3;
 588                 /* the last MSDU has no padding */
 589                 if (subframe_len > remaining)
 590                         goto purge;
 591
 592                 skb_pull(skb, sizeof(struct ethhdr));
 593                 /* reuse skb for the last subframe */
 594                 if (remaining <= subframe_len + padding)
 595                         frame = skb;
 596                 else {
 597                         unsigned int hlen = ALIGN(extra_headroom, 4);
 598                         /*
 599                          * Allocate and reserve two bytes more for payload
 600                          * alignment since sizeof(struct ethhdr) is 14.
 601                          */
 602                         frame = dev_alloc_skb(hlen + subframe_len + 2);
 603                         if (!frame)
 604                                 goto purge;
 605
 606                         skb_reserve(frame, hlen + sizeof(struct ethhdr) + 2);
 607                         memcpy(skb_put(frame, ntohs(len)), skb->data,
 608                                 ntohs(len));
 609
 610                         eth = (struct ethhdr *)skb_pull(skb, ntohs(len) +
 611                                                         padding);
 612                         if (!eth) {
 613                                 dev_kfree_skb(frame);
 614                                 goto purge;
 615                         }
 616                 }
 617
 618                 skb_reset_network_header(frame);
 619                 frame->dev = skb->dev;
 620                 frame->priority = skb->priority;
 621
 622                 payload = frame->data;
 623                 ethertype = (payload[6] << 8) | payload[7];
 624
 625                 if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
 626                             ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
 627                            compare_ether_addr(payload,
 628                                               bridge_tunnel_header) == 0)) {
 629                         /* remove RFC1042 or Bridge-Tunnel
 630                          * encapsulation and replace EtherType */
 631                         skb_pull(frame, 6);
 632                         memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
 633                         memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
 634                 } else {
 635                         memcpy(skb_push(frame, sizeof(__be16)), &len,
 636                                 sizeof(__be16));
 637                         memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
 638                         memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
 639                 }
 640                 __skb_queue_tail(list, frame);
 641         }
 642
 643         return;
 644
 645  purge:
 646         __skb_queue_purge(list);
 647  out:
 648         dev_kfree_skb(skb);
 649 }
 650 EXPORT_SYMBOL(ieee80211_amsdu_to_8023s);
 651
 652 /* Given a data frame determine the 802.1p/1d tag to use. */
 653 unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 654 {
 655         unsigned int dscp;
 656
 657         /* skb->priority values from 256->263 are magic values to
 658          * directly indicate a specific 802.1d priority.  This is used
 659          * to allow 802.1d priority to be passed directly in from VLAN
 660          * tags, etc.
 661          */
 662         if (skb->priority >= 256 && skb->priority <= 263)
 663                 return skb->priority - 256;
 664
 665         switch (skb->protocol) {
 666         case htons(ETH_P_IP):
 667                 dscp = ip_hdr(skb)->tos & 0xfc;
 668                 break;
 669         default:
 670                 return 0;
 671         }
 672
 673         return dscp >> 5;
 674 }
 675 EXPORT_SYMBOL(cfg80211_classify8021d);
 676
 677 const u8 *ieee80211_bss_get_ie(struct cfg80211_bss *bss, u8 ie)
 678 {
 679         u8 *end, *pos;
 680
 681         pos = bss->information_elements;
 682         if (pos == NULL)
 683                 return NULL;
 684         end = pos + bss->len_information_elements;
 685
 686         while (pos + 1 < end) {
 687                 if (pos + 2 + pos[1] > end)
 688                         break;
 689                 if (pos[0] == ie)
 690                         return pos;
 691                 pos += 2 + pos[1];
 692         }
 693
 694         return NULL;
 695 }
 696 EXPORT_SYMBOL(ieee80211_bss_get_ie);
 697
 698 void cfg80211_upload_connect_keys(struct wireless_dev *wdev)
 699 {
 700         struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);
 701         struct net_device *dev = wdev->netdev;
 702         int i;
 703
 704         if (!wdev->connect_keys)
 705                 return;
 706
 707         for (i = 0; i < 6; i++) {
 708                 if (!wdev->connect_keys->params[i].cipher)
 709                         continue;
 710                 if (rdev->ops->add_key(wdev->wiphy, dev, i, false, NULL,
 711                                         &wdev->connect_keys->params[i])) {
 712                         netdev_err(dev, "failed to set key %d\n", i);
 713                         continue;
 714                 }
 715                 if (wdev->connect_keys->def == i)
 716                         if (rdev->ops->set_default_key(wdev->wiphy, dev,
 717                                                        i, true, true)) {
 718                                 netdev_err(dev, "failed to set defkey %d\n", i);
 719                                 continue;
 720                         }
 721                 if (wdev->connect_keys->defmgmt == i)
 722                         if (rdev->ops->set_default_mgmt_key(wdev->wiphy, dev, i))
 723                                 netdev_err(dev, "failed to set mgtdef %d\n", i);
 724         }
 725
 726         kfree(wdev->connect_keys);
 727         wdev->connect_keys = NULL;
 728 }
 729
 730 void cfg80211_process_wdev_events(struct wireless_dev *wdev)
 731 {
 732         struct cfg80211_event *ev;
 733         unsigned long flags;
 734         const u8 *bssid = NULL;
 735
 736         spin_lock_irqsave(&wdev->event_lock, flags);
 737         while (!list_empty(&wdev->event_list)) {
 738                 ev = list_first_entry(&wdev->event_list,
 739                                       struct cfg80211_event, list);
 740                 list_del(&ev->list);
 741                 spin_unlock_irqrestore(&wdev->event_lock, flags);
 742
 743                 wdev_lock(wdev);
 744                 switch (ev->type) {
 745                 case EVENT_CONNECT_RESULT:
 746                         if (!is_zero_ether_addr(ev->cr.bssid))
 747                                 bssid = ev->cr.bssid;
 748                         __cfg80211_connect_result(
 749                                 wdev->netdev, bssid,
 750                                 ev->cr.req_ie, ev->cr.req_ie_len,
 751                                 ev->cr.resp_ie, ev->cr.resp_ie_len,
 752                                 ev->cr.status,
 753                                 ev->cr.status == WLAN_STATUS_SUCCESS,
 754                                 NULL);
 755                         break;
 756                 case EVENT_ROAMED:
 757                         __cfg80211_roamed(wdev, ev->rm.channel, ev->rm.bssid,
 758                                           ev->rm.req_ie, ev->rm.req_ie_len,
 759                                           ev->rm.resp_ie, ev->rm.resp_ie_len);
 760                         break;
 761                 case EVENT_DISCONNECTED:
 762                         __cfg80211_disconnected(wdev->netdev,
 763                                                 ev->dc.ie, ev->dc.ie_len,
 764                                                 ev->dc.reason, true);
 765                         break;
 766                 case EVENT_IBSS_JOINED:
 767                         __cfg80211_ibss_joined(wdev->netdev, ev->ij.bssid);
 768                         break;
 769                 }
 770                 wdev_unlock(wdev);
 771
 772                 kfree(ev);
 773
 774                 spin_lock_irqsave(&wdev->event_lock, flags);
 775         }
 776         spin_unlock_irqrestore(&wdev->event_lock, flags);
 777 }
 778
 779 void cfg80211_process_rdev_events(struct cfg80211_registered_device *rdev)
 780 {
 781         struct wireless_dev *wdev;
 782
 783         ASSERT_RTNL();
 784         ASSERT_RDEV_LOCK(rdev);
 785
 786         mutex_lock(&rdev->devlist_mtx);
 787
 788         list_for_each_entry(wdev, &rdev->netdev_list, list)
 789                 cfg80211_process_wdev_events(wdev);
 790
 791         mutex_unlock(&rdev->devlist_mtx);
 792 }
 793
 794 int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 795                           struct net_device *dev, enum nl80211_iftype ntype,
 796                           u32 *flags, struct vif_params *params)
 797 {
 798         int err;
 799         enum nl80211_iftype otype = dev->ieee80211_ptr->iftype;
 800
 801         ASSERT_RDEV_LOCK(rdev);
 802
 803         /* don't support changing VLANs, you just re-create them */
 804         if (otype == NL80211_IFTYPE_AP_VLAN)
 805                 return -EOPNOTSUPP;
 806
 807         if (!rdev->ops->change_virtual_intf ||
 808             !(rdev->wiphy.interface_modes & (1 << ntype)))
 809                 return -EOPNOTSUPP;
 810
 811         /* if it's part of a bridge, reject changing type to station/ibss */
 812         if ((dev->priv_flags & IFF_BRIDGE_PORT) &&
 813             (ntype == NL80211_IFTYPE_ADHOC ||
 814              ntype == NL80211_IFTYPE_STATION ||
 815              ntype == NL80211_IFTYPE_P2P_CLIENT))
 816                 return -EBUSY;
 817
 818         if (ntype != otype && netif_running(dev)) {
 819                 err = cfg80211_can_change_interface(rdev, dev->ieee80211_ptr,
 820                                                     ntype);
 821                 if (err)
 822                         return err;
 823
 824                 dev->ieee80211_ptr->use_4addr = false;
 825                 dev->ieee80211_ptr->mesh_id_up_len = 0;
 826
 827                 switch (otype) {
 828                 case NL80211_IFTYPE_ADHOC:
 829                         cfg80211_leave_ibss(rdev, dev, false);
 830                         break;
 831                 case NL80211_IFTYPE_STATION:
 832                 case NL80211_IFTYPE_P2P_CLIENT:
 833                         cfg80211_disconnect(rdev, dev,
 834                                             WLAN_REASON_DEAUTH_LEAVING, true);
 835                         break;
 836                 case NL80211_IFTYPE_MESH_POINT:
 837                         /* mesh should be handled? */
 838                         break;
 839                 default:
 840                         break;
 841                 }
 842
 843                 cfg80211_process_rdev_events(rdev);
 844         }
 845
 846         err = rdev->ops->change_virtual_intf(&rdev->wiphy, dev,
 847                                              ntype, flags, params);
 848
 849         WARN_ON(!err && dev->ieee80211_ptr->iftype != ntype);
 850
 851         if (!err && params && params->use_4addr != -1)
 852                 dev->ieee80211_ptr->use_4addr = params->use_4addr;
 853
 854         if (!err) {
 855                 dev->priv_flags &= ~IFF_DONT_BRIDGE;
 856                 switch (ntype) {
 857                 case NL80211_IFTYPE_STATION:
 858                         if (dev->ieee80211_ptr->use_4addr)
 859                                 break;
 860                         /* fall through */
 861                 case NL80211_IFTYPE_P2P_CLIENT:
 862                 case NL80211_IFTYPE_ADHOC:
 863                         dev->priv_flags |= IFF_DONT_BRIDGE;
 864                         break;
 865                 case NL80211_IFTYPE_P2P_GO:
 866                 case NL80211_IFTYPE_AP:
 867                 case NL80211_IFTYPE_AP_VLAN:
 868                 case NL80211_IFTYPE_WDS:
 869                 case NL80211_IFTYPE_MESH_POINT:
 870                         /* bridging OK */
 871                         break;
 872                 case NL80211_IFTYPE_MONITOR:
 873                         /* monitor can't bridge anyway */
 874                         break;
 875                 case NL80211_IFTYPE_UNSPECIFIED:
 876                 case NUM_NL80211_IFTYPES:
 877                         /* not happening */
 878                         break;
 879                 }
 880         }
 881
 882         return err;
 883 }
 884
 885 u16 cfg80211_calculate_bitrate(struct rate_info *rate)
 886 {
 887         int modulation, streams, bitrate;
 888
 889         if (!(rate->flags & RATE_INFO_FLAGS_MCS))
 890                 return rate->legacy;
 891
 892         /* the formula below does only work for MCS values smaller than 32 */
 893         if (rate->mcs >= 32)
 894                 return 0;
 895
 896         modulation = rate->mcs & 7;
 897         streams = (rate->mcs >> 3) + 1;
 898
 899         bitrate = (rate->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH) ?
 900                         13500000 : 6500000;
 901
 902         if (modulation < 4)
 903                 bitrate *= (modulation + 1);
 904         else if (modulation == 4)
 905                 bitrate *= (modulation + 2);
 906         else
 907                 bitrate *= (modulation + 3);
 908
 909         bitrate *= streams;
 910
 911         if (rate->flags & RATE_INFO_FLAGS_SHORT_GI)
 912                 bitrate = (bitrate / 9) * 10;
 913
 914         /* do NOT round down here */
 915         return (bitrate + 50000) / 100000;
 916 }
 917
 918 int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
 919                                  u32 beacon_int)
 920 {
 921         struct wireless_dev *wdev;
 922         int res = 0;
 923
 924         if (!beacon_int)
 925                 return -EINVAL;
 926
 927         mutex_lock(&rdev->devlist_mtx);
 928
 929         list_for_each_entry(wdev, &rdev->netdev_list, list) {
 930                 if (!wdev->beacon_interval)
 931                         continue;
 932                 if (wdev->beacon_interval != beacon_int) {
 933                         res = -EINVAL;
 934                         break;
 935                 }
 936         }
 937
 938         mutex_unlock(&rdev->devlist_mtx);
 939
 940         return res;
 941 }
 942
 943 int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
 944                                   struct wireless_dev *wdev,
 945                                   enum nl80211_iftype iftype)
 946 {
 947         struct wireless_dev *wdev_iter;
 948         u32 used_iftypes = BIT(iftype);
 949         int num[NUM_NL80211_IFTYPES];
 950         int total = 1;
 951         int i, j;
 952
 953         ASSERT_RTNL();
 954
 955         /* Always allow software iftypes */
 956         if (rdev->wiphy.software_iftypes & BIT(iftype))
 957                 return 0;
 958
 959         /*
 960          * Drivers will gradually all set this flag, until all
 961          * have it we only enforce for those that set it.
 962          */
 963         if (!(rdev->wiphy.flags & WIPHY_FLAG_ENFORCE_COMBINATIONS))
 964                 return 0;
 965
 966         memset(num, 0, sizeof(num));
 967
 968         num[iftype] = 1;
 969
 970         mutex_lock(&rdev->devlist_mtx);
 971         list_for_each_entry(wdev_iter, &rdev->netdev_list, list) {
 972                 if (wdev_iter == wdev)
 973                         continue;
 974                 if (!netif_running(wdev_iter->netdev))
 975                         continue;
 976
 977                 if (rdev->wiphy.software_iftypes & BIT(wdev_iter->iftype))
 978                         continue;
 979
 980                 num[wdev_iter->iftype]++;
 981                 total++;
 982                 used_iftypes |= BIT(wdev_iter->iftype);
 983         }
 984         mutex_unlock(&rdev->devlist_mtx);
 985
 986         if (total == 1)
 987                 return 0;
 988
 989         for (i = 0; i < rdev->wiphy.n_iface_combinations; i++) {
 990                 const struct ieee80211_iface_combination *c;
 991                 struct ieee80211_iface_limit *limits;
 992                 u32 all_iftypes = 0;
 993
 994                 c = &rdev->wiphy.iface_combinations[i];
 995
 996                 limits = kmemdup(c->limits, sizeof(limits[0]) * c->n_limits,
 997                                  GFP_KERNEL);
 998                 if (!limits)
 999                         return -ENOMEM;
1000                 if (total > c->max_interfaces)
1001                         goto cont;
1002
1003                 for (iftype = 0; iftype < NUM_NL80211_IFTYPES; iftype++) {
1004                         if (rdev->wiphy.software_iftypes & BIT(iftype))
1005                                 continue;
1006                         for (j = 0; j < c->n_limits; j++) {
1007                                 all_iftypes |= limits[j].types;
1008                                 if (!(limits[j].types & BIT(iftype)))
1009                                         continue;
1010                                 if (limits[j].max < num[iftype])
1011                                         goto cont;
1012                                 limits[j].max -= num[iftype];
1013                         }
1014                 }
1015
1016                 /*
1017                  * Finally check that all iftypes that we're currently
1018                  * using are actually part of this combination. If they
1019                  * aren't then we can't use this combination and have
1020                  * to continue to the next.
1021                  */
1022                 if ((all_iftypes & used_iftypes) != used_iftypes)
1023                         goto cont;
1024
1025                 /*
1026                  * This combination covered all interface types and
1027                  * supported the requested numbers, so we're good.
1028                  */
1029                 kfree(limits);
1030                 return 0;
1031  cont:
1032                 kfree(limits);
1033         }
1034
1035         return -EBUSY;
1036 }
1037
1038 int ieee80211_get_ratemask(struct ieee80211_supported_band *sband,
1039                            const u8 *rates, unsigned int n_rates,
1040                            u32 *mask)
1041 {
1042         int i, j;
1043
1044         if (!sband)
1045                 return -EINVAL;
1046
1047         if (n_rates == 0 || n_rates > NL80211_MAX_SUPP_RATES)
1048                 return -EINVAL;
1049
1050         *mask = 0;
1051
1052         for (i = 0; i < n_rates; i++) {
1053                 int rate = (rates[i] & 0x7f) * 5;
1054                 bool found = false;
1055
1056                 for (j = 0; j < sband->n_bitrates; j++) {
1057                         if (sband->bitrates[j].bitrate == rate) {
1058                                 found = true;
1059                                 *mask |= BIT(j);
1060                                 break;
1061                         }
1062                 }
1063                 if (!found)
1064                         return -EINVAL;
1065         }
1066
1067         /*
1068          * mask must have at least one bit set here since we
1069          * didn't accept a 0-length rates array nor allowed
1070          * entries in the array that didn't exist
1071          */
1072
1073         return 0;
1074 }
1075
1076 u32 ieee802_11_parse_elems_crc(u8 *start, size_t len,
1077                                struct ieee802_11_elems *elems,
1078                                u64 filter, u32 crc)
1079 {
1080         size_t left = len;
1081         u8 *pos = start;
1082         bool calc_crc = filter != 0;
1083
1084         memset(elems, 0, sizeof(*elems));
1085         elems->ie_start = start;
1086         elems->total_len = len;
1087
1088         while (left >= 2) {
1089                 u8 id, elen;
1090
1091                 id = *pos++;
1092                 elen = *pos++;
1093                 left -= 2;
1094
1095                 if (elen > left)
1096                         break;
1097
1098                 if (calc_crc && id < 64 && (filter & (1ULL << id)))
1099                         crc = crc32_be(crc, pos - 2, elen + 2);
1100
1101                 switch (id) {
1102                 case WLAN_EID_SSID:
1103                         elems->ssid = pos;
1104                         elems->ssid_len = elen;
1105                         break;
1106                 case WLAN_EID_SUPP_RATES:
1107                         elems->supp_rates = pos;
1108                         elems->supp_rates_len = elen;
1109                         break;
1110                 case WLAN_EID_FH_PARAMS:
1111                         elems->fh_params = pos;
1112                         elems->fh_params_len = elen;
1113                         break;
1114                 case WLAN_EID_DS_PARAMS:
1115                         elems->ds_params = pos;
1116                         elems->ds_params_len = elen;
1117                         break;
1118                 case WLAN_EID_CF_PARAMS:
1119                         elems->cf_params = pos;
1120                         elems->cf_params_len = elen;
1121                         break;
1122                 case WLAN_EID_TIM:
1123                         if (elen >= sizeof(struct ieee80211_tim_ie)) {
1124                                 elems->tim = (void *)pos;
1125                                 elems->tim_len = elen;
1126                         }
1127                         break;
1128                 case WLAN_EID_IBSS_PARAMS:
1129                         elems->ibss_params = pos;
1130                         elems->ibss_params_len = elen;
1131                         break;
1132                 case WLAN_EID_CHALLENGE:
1133                         elems->challenge = pos;
1134                         elems->challenge_len = elen;
1135                         break;
1136                 case WLAN_EID_VENDOR_SPECIFIC:
1137                         if (elen >= 4 && pos[0] == 0x00 && pos[1] == 0x50 &&
1138                             pos[2] == 0xf2) {
1139                                 /* Microsoft OUI (00:50:F2) */
1140
1141                                 if (calc_crc)
1142                                         crc = crc32_be(crc, pos - 2, elen + 2);
1143
1144                                 if (pos[3] == 1) {
1145                                         /* OUI Type 1 - WPA IE */
1146                                         elems->wpa = pos;
1147                                         elems->wpa_len = elen;
1148                                 } else if (elen >= 5 && pos[3] == 2) {
1149                                         /* OUI Type 2 - WMM IE */
1150                                         if (pos[4] == 0) {
1151                                                 elems->wmm_info = pos;
1152                                                 elems->wmm_info_len = elen;
1153                                         } else if (pos[4] == 1) {
1154                                                 elems->wmm_param = pos;
1155                                                 elems->wmm_param_len = elen;
1156                                         }
1157                                 }
1158                         }
1159                         break;
1160                 case WLAN_EID_RSN:
1161                         elems->rsn = pos;
1162                         elems->rsn_len = elen;
1163                         break;
1164                 case WLAN_EID_ERP_INFO:
1165                         elems->erp_info = pos;
1166                         elems->erp_info_len = elen;
1167                         break;
1168                 case WLAN_EID_EXT_SUPP_RATES:
1169                         elems->ext_supp_rates = pos;
1170                         elems->ext_supp_rates_len = elen;
1171                         break;
1172                 case WLAN_EID_HT_CAPABILITY:
1173                         if (elen >= sizeof(struct ieee80211_ht_cap))
1174                                 elems->ht_cap_elem = (void *)pos;
1175                         break;
1176                 case WLAN_EID_HT_INFORMATION:
1177                         if (elen >= sizeof(struct ieee80211_ht_info))
1178                                 elems->ht_info_elem = (void *)pos;
1179                         break;
1180                 case WLAN_EID_MESH_ID:
1181                         elems->mesh_id = pos;
1182                         elems->mesh_id_len = elen;
1183                         break;
1184                 case WLAN_EID_MESH_CONFIG:
1185                         if (elen >= sizeof(struct ieee80211_meshconf_ie))
1186                                 elems->mesh_config = (void *)pos;
1187                         break;
1188                 case WLAN_EID_PEER_MGMT:
1189                         elems->peering = pos;
1190                         elems->peering_len = elen;
1191                         break;
1192                 case WLAN_EID_PREQ:
1193                         elems->preq = pos;
1194                         elems->preq_len = elen;
1195                         break;
1196                 case WLAN_EID_PREP:
1197                         elems->prep = pos;
1198                         elems->prep_len = elen;
1199                         break;
1200                 case WLAN_EID_PERR:
1201                         elems->perr = pos;
1202                         elems->perr_len = elen;
1203                         break;
1204                 case WLAN_EID_RANN:
1205                         if (elen >= sizeof(struct ieee80211_rann_ie))
1206                                 elems->rann = (void *)pos;
1207                         break;
1208                 case WLAN_EID_CHANNEL_SWITCH:
1209                         elems->ch_switch_elem = pos;
1210                         elems->ch_switch_elem_len = elen;
1211                         break;
1212                 case WLAN_EID_QUIET:
1213                         if (!elems->quiet_elem) {
1214                                 elems->quiet_elem = pos;
1215                                 elems->quiet_elem_len = elen;
1216                         }
1217                         elems->num_of_quiet_elem++;
1218                         break;
1219                 case WLAN_EID_COUNTRY:
1220                         elems->country_elem = pos;
1221                         elems->country_elem_len = elen;
1222                         break;
1223                 case WLAN_EID_PWR_CONSTRAINT:
1224                         elems->pwr_constr_elem = pos;
1225                         elems->pwr_constr_elem_len = elen;
1226                         break;
1227                 case WLAN_EID_TIMEOUT_INTERVAL:
1228                         elems->timeout_int = pos;
1229                         elems->timeout_int_len = elen;
1230                         break;
1231                 default:
1232                         break;
1233                 }
1234
1235                 left -= elen;
1236                 pos += elen;
1237         }
1238
1239         return crc;
1240 }
1241 EXPORT_SYMBOL(ieee802_11_parse_elems_crc);