net/wireless/util.c

   1 /*
   2  * Wireless utility functions
   3  *
   4  * Copyright 2007-2009  Johannes Berg <johannes@sipsolutions.net>
   5  */
   6 #include <linux/bitops.h>
   7 #include <linux/etherdevice.h>
   8 #include <net/cfg80211.h>
   9 #include <net/ip.h>
  10 #include "core.h"
  11
  12 struct ieee80211_rate *
  13 ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
  14                             u32 basic_rates, int bitrate)
  15 {
  16         struct ieee80211_rate *result = &sband->bitrates[0];
  17         int i;
  18
  19         for (i = 0; i < sband->n_bitrates; i++) {
  20                 if (!(basic_rates & BIT(i)))
  21                         continue;
  22                 if (sband->bitrates[i].bitrate > bitrate)
  23                         continue;
  24                 result = &sband->bitrates[i];
  25         }
  26
  27         return result;
  28 }
  29 EXPORT_SYMBOL(ieee80211_get_response_rate);
  30
  31 int ieee80211_channel_to_frequency(int chan)
  32 {
  33         if (chan < 14)
  34                 return 2407 + chan * 5;
  35
  36         if (chan == 14)
  37                 return 2484;
  38
  39         /* FIXME: 802.11j 17.3.8.3.2 */
  40         return (chan + 1000) * 5;
  41 }
  42 EXPORT_SYMBOL(ieee80211_channel_to_frequency);
  43
  44 int ieee80211_frequency_to_channel(int freq)
  45 {
  46         if (freq == 2484)
  47                 return 14;
  48
  49         if (freq < 2484)
  50                 return (freq - 2407) / 5;
  51
  52         /* FIXME: 802.11j 17.3.8.3.2 */
  53         return freq/5 - 1000;
  54 }
  55 EXPORT_SYMBOL(ieee80211_frequency_to_channel);
  56
  57 struct ieee80211_channel *__ieee80211_get_channel(struct wiphy *wiphy,
  58                                                   int freq)
  59 {
  60         enum ieee80211_band band;
  61         struct ieee80211_supported_band *sband;
  62         int i;
  63
  64         for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
  65                 sband = wiphy->bands[band];
  66
  67                 if (!sband)
  68                         continue;
  69
  70                 for (i = 0; i < sband->n_channels; i++) {
  71                         if (sband->channels[i].center_freq == freq)
  72                                 return &sband->channels[i];
  73                 }
  74         }
  75
  76         return NULL;
  77 }
  78 EXPORT_SYMBOL(__ieee80211_get_channel);
  79
  80 static void set_mandatory_flags_band(struct ieee80211_supported_band *sband,
  81                                      enum ieee80211_band band)
  82 {
  83         int i, want;
  84
  85         switch (band) {
  86         case IEEE80211_BAND_5GHZ:
  87                 want = 3;
  88                 for (i = 0; i < sband->n_bitrates; i++) {
  89                         if (sband->bitrates[i].bitrate == 60 ||
  90                             sband->bitrates[i].bitrate == 120 ||
  91                             sband->bitrates[i].bitrate == 240) {
  92                                 sband->bitrates[i].flags |=
  93                                         IEEE80211_RATE_MANDATORY_A;
  94                                 want--;
  95                         }
  96                 }
  97                 WARN_ON(want);
  98                 break;
  99         case IEEE80211_BAND_2GHZ:
 100                 want = 7;
 101                 for (i = 0; i < sband->n_bitrates; i++) {
 102                         if (sband->bitrates[i].bitrate == 10) {
 103                                 sband->bitrates[i].flags |=
 104                                         IEEE80211_RATE_MANDATORY_B |
 105                                         IEEE80211_RATE_MANDATORY_G;
 106                                 want--;
 107                         }
 108
 109                         if (sband->bitrates[i].bitrate == 20 ||
 110                             sband->bitrates[i].bitrate == 55 ||
 111                             sband->bitrates[i].bitrate == 110 ||
 112                             sband->bitrates[i].bitrate == 60 ||
 113                             sband->bitrates[i].bitrate == 120 ||
 114                             sband->bitrates[i].bitrate == 240) {
 115                                 sband->bitrates[i].flags |=
 116                                         IEEE80211_RATE_MANDATORY_G;
 117                                 want--;
 118                         }
 119
 120                         if (sband->bitrates[i].bitrate != 10 &&
 121                             sband->bitrates[i].bitrate != 20 &&
 122                             sband->bitrates[i].bitrate != 55 &&
 123                             sband->bitrates[i].bitrate != 110)
 124                                 sband->bitrates[i].flags |=
 125                                         IEEE80211_RATE_ERP_G;
 126                 }
 127                 WARN_ON(want != 0 && want != 3 && want != 6);
 128                 break;
 129         case IEEE80211_NUM_BANDS:
 130                 WARN_ON(1);
 131                 break;
 132         }
 133 }
 134
 135 void ieee80211_set_bitrate_flags(struct wiphy *wiphy)
 136 {
 137         enum ieee80211_band band;
 138
 139         for (band = 0; band < IEEE80211_NUM_BANDS; band++)
 140                 if (wiphy->bands[band])
 141                         set_mandatory_flags_band(wiphy->bands[band], band);
 142 }
 143
 144 int cfg80211_validate_key_settings(struct key_params *params, int key_idx,
 145                                    const u8 *mac_addr)
 146 {
 147         if (key_idx > 5)
 148                 return -EINVAL;
 149
 150         /*
 151          * Disallow pairwise keys with non-zero index unless it's WEP
 152          * (because current deployments use pairwise WEP keys with
 153          * non-zero indizes but 802.11i clearly specifies to use zero)
 154          */
 155         if (mac_addr && key_idx &&
 156             params->cipher != WLAN_CIPHER_SUITE_WEP40 &&
 157             params->cipher != WLAN_CIPHER_SUITE_WEP104)
 158                 return -EINVAL;
 159
 160         switch (params->cipher) {
 161         case WLAN_CIPHER_SUITE_WEP40:
 162                 if (params->key_len != WLAN_KEY_LEN_WEP40)
 163                         return -EINVAL;
 164                 break;
 165         case WLAN_CIPHER_SUITE_TKIP:
 166                 if (params->key_len != WLAN_KEY_LEN_TKIP)
 167                         return -EINVAL;
 168                 break;
 169         case WLAN_CIPHER_SUITE_CCMP:
 170                 if (params->key_len != WLAN_KEY_LEN_CCMP)
 171                         return -EINVAL;
 172                 break;
 173         case WLAN_CIPHER_SUITE_WEP104:
 174                 if (params->key_len != WLAN_KEY_LEN_WEP104)
 175                         return -EINVAL;
 176                 break;
 177         case WLAN_CIPHER_SUITE_AES_CMAC:
 178                 if (params->key_len != WLAN_KEY_LEN_AES_CMAC)
 179                         return -EINVAL;
 180                 break;
 181         default:
 182                 return -EINVAL;
 183         }
 184
 185         if (params->seq) {
 186                 switch (params->cipher) {
 187                 case WLAN_CIPHER_SUITE_WEP40:
 188                 case WLAN_CIPHER_SUITE_WEP104:
 189                         /* These ciphers do not use key sequence */
 190                         return -EINVAL;
 191                 case WLAN_CIPHER_SUITE_TKIP:
 192                 case WLAN_CIPHER_SUITE_CCMP:
 193                 case WLAN_CIPHER_SUITE_AES_CMAC:
 194                         if (params->seq_len != 6)
 195                                 return -EINVAL;
 196                         break;
 197                 }
 198         }
 199
 200         return 0;
 201 }
 202
 203 /* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
 204 /* Ethernet-II snap header (RFC1042 for most EtherTypes) */
 205 const unsigned char rfc1042_header[] __aligned(2) =
 206         { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
 207 EXPORT_SYMBOL(rfc1042_header);
 208
 209 /* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
 210 const unsigned char bridge_tunnel_header[] __aligned(2) =
 211         { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
 212 EXPORT_SYMBOL(bridge_tunnel_header);
 213
 214 unsigned int ieee80211_hdrlen(__le16 fc)
 215 {
 216         unsigned int hdrlen = 24;
 217
 218         if (ieee80211_is_data(fc)) {
 219                 if (ieee80211_has_a4(fc))
 220                         hdrlen = 30;
 221                 if (ieee80211_is_data_qos(fc))
 222                         hdrlen += IEEE80211_QOS_CTL_LEN;
 223                 goto out;
 224         }
 225
 226         if (ieee80211_is_ctl(fc)) {
 227                 /*
 228                  * ACK and CTS are 10 bytes, all others 16. To see how
 229                  * to get this condition consider
 230                  *   subtype mask:   0b0000000011110000 (0x00F0)
 231                  *   ACK subtype:    0b0000000011010000 (0x00D0)
 232                  *   CTS subtype:    0b0000000011000000 (0x00C0)
 233                  *   bits that matter:         ^^^      (0x00E0)
 234                  *   value of those: 0b0000000011000000 (0x00C0)
 235                  */
 236                 if ((fc & cpu_to_le16(0x00E0)) == cpu_to_le16(0x00C0))
 237                         hdrlen = 10;
 238                 else
 239                         hdrlen = 16;
 240         }
 241 out:
 242         return hdrlen;
 243 }
 244 EXPORT_SYMBOL(ieee80211_hdrlen);
 245
 246 unsigned int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
 247 {
 248         const struct ieee80211_hdr *hdr =
 249                         (const struct ieee80211_hdr *)skb->data;
 250         unsigned int hdrlen;
 251
 252         if (unlikely(skb->len < 10))
 253                 return 0;
 254         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 255         if (unlikely(hdrlen > skb->len))
 256                 return 0;
 257         return hdrlen;
 258 }
 259 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);
 260
 261 static int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 262 {
 263         int ae = meshhdr->flags & MESH_FLAGS_AE;
 264         /* 7.1.3.5a.2 */
 265         switch (ae) {
 266         case 0:
 267                 return 6;
 268         case 1:
 269                 return 12;
 270         case 2:
 271                 return 18;
 272         case 3:
 273                 return 24;
 274         default:
 275                 return 6;
 276         }
 277 }
 278
 279 int ieee80211_data_to_8023(struct sk_buff *skb, u8 *addr,
 280                            enum nl80211_iftype iftype)
 281 {
 282         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 283         u16 hdrlen, ethertype;
 284         u8 *payload;
 285         u8 dst[ETH_ALEN];
 286         u8 src[ETH_ALEN] __aligned(2);
 287
 288         if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
 289                 return -1;
 290
 291         hdrlen = ieee80211_hdrlen(hdr->frame_control);
 292
 293         /* convert IEEE 802.11 header + possible LLC headers into Ethernet
 294          * header
 295          * IEEE 802.11 address fields:
 296          * ToDS FromDS Addr1 Addr2 Addr3 Addr4
 297          *   0     0   DA    SA    BSSID n/a
 298          *   0     1   DA    BSSID SA    n/a
 299          *   1     0   BSSID SA    DA    n/a
 300          *   1     1   RA    TA    DA    SA
 301          */
 302         memcpy(dst, ieee80211_get_DA(hdr), ETH_ALEN);
 303         memcpy(src, ieee80211_get_SA(hdr), ETH_ALEN);
 304
 305         switch (hdr->frame_control &
 306                 cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 307         case cpu_to_le16(IEEE80211_FCTL_TODS):
 308                 if (unlikely(iftype != NL80211_IFTYPE_AP &&
 309                              iftype != NL80211_IFTYPE_AP_VLAN))
 310                         return -1;
 311                 break;
 312         case cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
 313                 if (unlikely(iftype != NL80211_IFTYPE_WDS &&
 314                              iftype != NL80211_IFTYPE_MESH_POINT))
 315                         return -1;
 316                 if (iftype == NL80211_IFTYPE_MESH_POINT) {
 317                         struct ieee80211s_hdr *meshdr =
 318                                 (struct ieee80211s_hdr *) (skb->data + hdrlen);
 319                         hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
 320                         if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
 321                                 memcpy(dst, meshdr->eaddr1, ETH_ALEN);
 322                                 memcpy(src, meshdr->eaddr2, ETH_ALEN);
 323                         }
 324                 }
 325                 break;
 326         case cpu_to_le16(IEEE80211_FCTL_FROMDS):
 327                 if (iftype != NL80211_IFTYPE_STATION ||
 328                     (is_multicast_ether_addr(dst) &&
 329                      !compare_ether_addr(src, addr)))
 330                         return -1;
 331                 break;
 332         case cpu_to_le16(0):
 333                 if (iftype != NL80211_IFTYPE_ADHOC)
 334                         return -1;
 335                 break;
 336         }
 337
 338         if (unlikely(skb->len - hdrlen < 8))
 339                 return -1;
 340
 341         payload = skb->data + hdrlen;
 342         ethertype = (payload[6] << 8) | payload[7];
 343
 344         if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
 345                     ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
 346                    compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
 347                 /* remove RFC1042 or Bridge-Tunnel encapsulation and
 348                  * replace EtherType */
 349                 skb_pull(skb, hdrlen + 6);
 350                 memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
 351                 memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
 352         } else {
 353                 struct ethhdr *ehdr;
 354                 __be16 len;
 355
 356                 skb_pull(skb, hdrlen);
 357                 len = htons(skb->len);
 358                 ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
 359                 memcpy(ehdr->h_dest, dst, ETH_ALEN);
 360                 memcpy(ehdr->h_source, src, ETH_ALEN);
 361                 ehdr->h_proto = len;
 362         }
 363         return 0;
 364 }
 365 EXPORT_SYMBOL(ieee80211_data_to_8023);
 366
 367 int ieee80211_data_from_8023(struct sk_buff *skb, u8 *addr,
 368                              enum nl80211_iftype iftype, u8 *bssid, bool qos)
 369 {
 370         struct ieee80211_hdr hdr;
 371         u16 hdrlen, ethertype;
 372         __le16 fc;
 373         const u8 *encaps_data;
 374         int encaps_len, skip_header_bytes;
 375         int nh_pos, h_pos;
 376         int head_need;
 377
 378         if (unlikely(skb->len < ETH_HLEN))
 379                 return -EINVAL;
 380
 381         nh_pos = skb_network_header(skb) - skb->data;
 382         h_pos = skb_transport_header(skb) - skb->data;
 383
 384         /* convert Ethernet header to proper 802.11 header (based on
 385          * operation mode) */
 386         ethertype = (skb->data[12] << 8) | skb->data[13];
 387         fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);
 388
 389         switch (iftype) {
 390         case NL80211_IFTYPE_AP:
 391         case NL80211_IFTYPE_AP_VLAN:
 392                 fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
 393                 /* DA BSSID SA */
 394                 memcpy(hdr.addr1, skb->data, ETH_ALEN);
 395                 memcpy(hdr.addr2, addr, ETH_ALEN);
 396                 memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
 397                 hdrlen = 24;
 398                 break;
 399         case NL80211_IFTYPE_STATION:
 400                 fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 401                 /* BSSID SA DA */
 402                 memcpy(hdr.addr1, bssid, ETH_ALEN);
 403                 memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 404                 memcpy(hdr.addr3, skb->data, ETH_ALEN);
 405                 hdrlen = 24;
 406                 break;
 407         case NL80211_IFTYPE_ADHOC:
 408                 /* DA SA BSSID */
 409                 memcpy(hdr.addr1, skb->data, ETH_ALEN);
 410                 memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 411                 memcpy(hdr.addr3, bssid, ETH_ALEN);
 412                 hdrlen = 24;
 413                 break;
 414         default:
 415                 return -EOPNOTSUPP;
 416         }
 417
 418         if (qos) {
 419                 fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
 420                 hdrlen += 2;
 421         }
 422
 423         hdr.frame_control = fc;
 424         hdr.duration_id = 0;
 425         hdr.seq_ctrl = 0;
 426
 427         skip_header_bytes = ETH_HLEN;
 428         if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
 429                 encaps_data = bridge_tunnel_header;
 430                 encaps_len = sizeof(bridge_tunnel_header);
 431                 skip_header_bytes -= 2;
 432         } else if (ethertype > 0x600) {
 433                 encaps_data = rfc1042_header;
 434                 encaps_len = sizeof(rfc1042_header);
 435                 skip_header_bytes -= 2;
 436         } else {
 437                 encaps_data = NULL;
 438                 encaps_len = 0;
 439         }
 440
 441         skb_pull(skb, skip_header_bytes);
 442         nh_pos -= skip_header_bytes;
 443         h_pos -= skip_header_bytes;
 444
 445         head_need = hdrlen + encaps_len - skb_headroom(skb);
 446
 447         if (head_need > 0 || skb_cloned(skb)) {
 448                 head_need = max(head_need, 0);
 449                 if (head_need)
 450                         skb_orphan(skb);
 451
 452                 if (pskb_expand_head(skb, head_need, 0, GFP_ATOMIC)) {
 453                         printk(KERN_ERR "failed to reallocate Tx buffer\n");
 454                         return -ENOMEM;
 455                 }
 456                 skb->truesize += head_need;
 457         }
 458
 459         if (encaps_data) {
 460                 memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
 461                 nh_pos += encaps_len;
 462                 h_pos += encaps_len;
 463         }
 464
 465         memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);
 466
 467         nh_pos += hdrlen;
 468         h_pos += hdrlen;
 469
 470         /* Update skb pointers to various headers since this modified frame
 471          * is going to go through Linux networking code that may potentially
 472          * need things like pointer to IP header. */
 473         skb_set_mac_header(skb, 0);
 474         skb_set_network_header(skb, nh_pos);
 475         skb_set_transport_header(skb, h_pos);
 476
 477         return 0;
 478 }
 479 EXPORT_SYMBOL(ieee80211_data_from_8023);
 480
 481 /* Given a data frame determine the 802.1p/1d tag to use. */
 482 unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 483 {
 484         unsigned int dscp;
 485
 486         /* skb->priority values from 256->263 are magic values to
 487          * directly indicate a specific 802.1d priority.  This is used
 488          * to allow 802.1d priority to be passed directly in from VLAN
 489          * tags, etc.
 490          */
 491         if (skb->priority >= 256 && skb->priority <= 263)
 492                 return skb->priority - 256;
 493
 494         switch (skb->protocol) {
 495         case htons(ETH_P_IP):
 496                 dscp = ip_hdr(skb)->tos & 0xfc;
 497                 break;
 498         default:
 499                 return 0;
 500         }
 501
 502         return dscp >> 5;
 503 }
 504 EXPORT_SYMBOL(cfg80211_classify8021d);