net/ieee80211/ieee80211_tx.c

   1 /******************************************************************************
   2
   3   Copyright(c) 2003 - 2005 Intel Corporation. All rights reserved.
   4
   5   This program is free software; you can redistribute it and/or modify it
   6   under the terms of version 2 of the GNU General Public License as
   7   published by the Free Software Foundation.
   8
   9   This program is distributed in the hope that it will be useful, but WITHOUT
  10   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12   more details.
  13
  14   You should have received a copy of the GNU General Public License along with
  15   this program; if not, write to the Free Software Foundation, Inc., 59
  16   Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17
  18   The full GNU General Public License is included in this distribution in the
  19   file called LICENSE.
  20
  21   Contact Information:
  22   James P. Ketrenos <ipw2100-admin@linux.intel.com>
  23   Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
  24
  25 ******************************************************************************/
  26 #include <linux/compiler.h>
  27 #include <linux/errno.h>
  28 #include <linux/if_arp.h>
  29 #include <linux/in6.h>
  30 #include <linux/in.h>
  31 #include <linux/ip.h>
  32 #include <linux/kernel.h>
  33 #include <linux/module.h>
  34 #include <linux/netdevice.h>
  35 #include <linux/proc_fs.h>
  36 #include <linux/skbuff.h>
  37 #include <linux/slab.h>
  38 #include <linux/tcp.h>
  39 #include <linux/types.h>
  40 #include <linux/wireless.h>
  41 #include <linux/etherdevice.h>
  42 #include <asm/uaccess.h>
  43
  44 #include <net/ieee80211.h>
  45
  46 /*
  47
  48 802.11 Data Frame
  49
  50       ,-------------------------------------------------------------------.
  51 Bytes |  2   |  2   |    6    |    6    |    6    |  2   | 0..2312 |   4  |
  52       |------|------|---------|---------|---------|------|---------|------|
  53 Desc. | ctrl | dura |  DA/RA  |   TA    |    SA   | Sequ |  Frame  |  fcs |
  54       |      | tion | (BSSID) |         |         | ence |  data   |      |
  55       `--------------------------------------------------|         |------'
  56 Total: 28 non-data bytes                                 `----.----'
  57                                                               |
  58        .- 'Frame data' expands, if WEP enabled, to <----------'
  59        |
  60        V
  61       ,-----------------------.
  62 Bytes |  4  |   0-2296  |  4  |
  63       |-----|-----------|-----|
  64 Desc. | IV  | Encrypted | ICV |
  65       |     | Packet    |     |
  66       `-----|           |-----'
  67             `-----.-----'
  68                   |
  69        .- 'Encrypted Packet' expands to
  70        |
  71        V
  72       ,---------------------------------------------------.
  73 Bytes |  1   |  1   |    1    |    3     |  2   |  0-2304 |
  74       |------|------|---------|----------|------|---------|
  75 Desc. | SNAP | SNAP | Control |Eth Tunnel| Type | IP      |
  76       | DSAP | SSAP |         |          |      | Packet  |
  77       | 0xAA | 0xAA |0x03 (UI)|0x00-00-F8|      |         |
  78       `----------------------------------------------------
  79 Total: 8 non-data bytes
  80
  81 802.3 Ethernet Data Frame
  82
  83       ,-----------------------------------------.
  84 Bytes |   6   |   6   |  2   |  Variable |   4  |
  85       |-------|-------|------|-----------|------|
  86 Desc. | Dest. | Source| Type | IP Packet |  fcs |
  87       |  MAC  |  MAC  |      |           |      |
  88       `-----------------------------------------'
  89 Total: 18 non-data bytes
  90
  91 In the event that fragmentation is required, the incoming payload is split into
  92 N parts of size ieee->fts.  The first fragment contains the SNAP header and the
  93 remaining packets are just data.
  94
  95 If encryption is enabled, each fragment payload size is reduced by enough space
  96 to add the prefix and postfix (IV and ICV totalling 8 bytes in the case of WEP)
  97 So if you have 1500 bytes of payload with ieee->fts set to 500 without
  98 encryption it will take 3 frames.  With WEP it will take 4 frames as the
  99 payload of each frame is reduced to 492 bytes.
 100
 101 * SKB visualization
 102 *
 103 *  ,- skb->data
 104 * |
 105 * |    ETHERNET HEADER        ,-<-- PAYLOAD
 106 * |                           |     14 bytes from skb->data
 107 * |  2 bytes for Type --> ,T. |     (sizeof ethhdr)
 108 * |                       | | |
 109 * |,-Dest.--. ,--Src.---. | | |
 110 * |  6 bytes| | 6 bytes | | | |
 111 * v         | |         | | | |
 112 * 0         | v       1 | v | v           2
 113 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
 114 *     ^     | ^         | ^ |
 115 *     |     | |         | | |
 116 *     |     | |         | `T' <---- 2 bytes for Type
 117 *     |     | |         |
 118 *     |     | '---SNAP--' <-------- 6 bytes for SNAP
 119 *     |     |
 120 *     `-IV--' <-------------------- 4 bytes for IV (WEP)
 121 *
 122 *      SNAP HEADER
 123 *
 124 */
 125
 126 static u8 P802_1H_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0xf8 };
 127 static u8 RFC1042_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0x00 };
 128
 129 static int ieee80211_copy_snap(u8 * data, __be16 h_proto)
 130 {
 131         struct ieee80211_snap_hdr *snap;
 132         u8 *oui;
 133
 134         snap = (struct ieee80211_snap_hdr *)data;
 135         snap->dsap = 0xaa;
 136         snap->ssap = 0xaa;
 137         snap->ctrl = 0x03;
 138
 139         if (h_proto == htons(ETH_P_AARP) || h_proto == htons(ETH_P_IPX))
 140                 oui = P802_1H_OUI;
 141         else
 142                 oui = RFC1042_OUI;
 143         snap->oui[0] = oui[0];
 144         snap->oui[1] = oui[1];
 145         snap->oui[2] = oui[2];
 146
 147         memcpy(data + SNAP_SIZE, &h_proto, sizeof(u16));
 148
 149         return SNAP_SIZE + sizeof(u16);
 150 }
 151
 152 static int ieee80211_encrypt_fragment(struct ieee80211_device *ieee,
 153                                              struct sk_buff *frag, int hdr_len)
 154 {
 155         struct ieee80211_crypt_data *crypt = ieee->crypt[ieee->tx_keyidx];
 156         int res;
 157
 158         if (crypt == NULL)
 159                 return -1;
 160
 161         /* To encrypt, frame format is:
 162          * IV (4 bytes), clear payload (including SNAP), ICV (4 bytes) */
 163         atomic_inc(&crypt->refcnt);
 164         res = 0;
 165         if (crypt->ops && crypt->ops->encrypt_mpdu)
 166                 res = crypt->ops->encrypt_mpdu(frag, hdr_len, crypt->priv);
 167
 168         atomic_dec(&crypt->refcnt);
 169         if (res < 0) {
 170                 printk(KERN_INFO "%s: Encryption failed: len=%d.\n",
 171                        ieee->dev->name, frag->len);
 172                 ieee->ieee_stats.tx_discards++;
 173                 return -1;
 174         }
 175
 176         return 0;
 177 }
 178
 179 void ieee80211_txb_free(struct ieee80211_txb *txb)
 180 {
 181         int i;
 182         if (unlikely(!txb))
 183                 return;
 184         for (i = 0; i < txb->nr_frags; i++)
 185                 if (txb->fragments[i])
 186                         dev_kfree_skb_any(txb->fragments[i]);
 187         kfree(txb);
 188 }
 189
 190 static struct ieee80211_txb *ieee80211_alloc_txb(int nr_frags, int txb_size,
 191                                                  int headroom, gfp_t gfp_mask)
 192 {
 193         struct ieee80211_txb *txb;
 194         int i;
 195         txb = kmalloc(sizeof(struct ieee80211_txb) + (sizeof(u8 *) * nr_frags),
 196                       gfp_mask);
 197         if (!txb)
 198                 return NULL;
 199
 200         memset(txb, 0, sizeof(struct ieee80211_txb));
 201         txb->nr_frags = nr_frags;
 202         txb->frag_size = txb_size;
 203
 204         for (i = 0; i < nr_frags; i++) {
 205                 txb->fragments[i] = __dev_alloc_skb(txb_size + headroom,
 206                                                     gfp_mask);
 207                 if (unlikely(!txb->fragments[i])) {
 208                         i--;
 209                         break;
 210                 }
 211                 skb_reserve(txb->fragments[i], headroom);
 212         }
 213         if (unlikely(i != nr_frags)) {
 214                 while (i >= 0)
 215                         dev_kfree_skb_any(txb->fragments[i--]);
 216                 kfree(txb);
 217                 return NULL;
 218         }
 219         return txb;
 220 }
 221
 222 static int ieee80211_classify(struct sk_buff *skb)
 223 {
 224         struct ethhdr *eth;
 225         struct iphdr *ip;
 226
 227         eth = (struct ethhdr *)skb->data;
 228         if (eth->h_proto != htons(ETH_P_IP))
 229                 return 0;
 230
 231         ip = ip_hdr(skb);
 232         switch (ip->tos & 0xfc) {
 233         case 0x20:
 234                 return 2;
 235         case 0x40:
 236                 return 1;
 237         case 0x60:
 238                 return 3;
 239         case 0x80:
 240                 return 4;
 241         case 0xa0:
 242                 return 5;
 243         case 0xc0:
 244                 return 6;
 245         case 0xe0:
 246                 return 7;
 247         default:
 248                 return 0;
 249         }
 250 }
 251
 252 /* Incoming skb is converted to a txb which consists of
 253  * a block of 802.11 fragment packets (stored as skbs) */
 254 int ieee80211_xmit(struct sk_buff *skb, struct net_device *dev)
 255 {
 256         struct ieee80211_device *ieee = netdev_priv(dev);
 257         struct ieee80211_txb *txb = NULL;
 258         struct ieee80211_hdr_3addrqos *frag_hdr;
 259         int i, bytes_per_frag, nr_frags, bytes_last_frag, frag_size,
 260             rts_required;
 261         unsigned long flags;
 262         struct net_device_stats *stats = &ieee->stats;
 263         int encrypt, host_encrypt, host_encrypt_msdu, host_build_iv;
 264         __be16 ether_type;
 265         int bytes, fc, hdr_len;
 266         struct sk_buff *skb_frag;
 267         struct ieee80211_hdr_3addrqos header = {/* Ensure zero initialized */
 268                 .duration_id = 0,
 269                 .seq_ctl = 0,
 270                 .qos_ctl = 0
 271         };
 272         u8 dest[ETH_ALEN], src[ETH_ALEN];
 273         struct ieee80211_crypt_data *crypt;
 274         int priority = skb->priority;
 275         int snapped = 0;
 276
 277         if (ieee->is_queue_full && (*ieee->is_queue_full) (dev, priority))
 278                 return NETDEV_TX_BUSY;
 279
 280         spin_lock_irqsave(&ieee->lock, flags);
 281
 282         /* If there is no driver handler to take the TXB, dont' bother
 283          * creating it... */
 284         if (!ieee->hard_start_xmit) {
 285                 printk(KERN_WARNING "%s: No xmit handler.\n", ieee->dev->name);
 286                 goto success;
 287         }
 288
 289         if (unlikely(skb->len < SNAP_SIZE + sizeof(u16))) {
 290                 printk(KERN_WARNING "%s: skb too small (%d).\n",
 291                        ieee->dev->name, skb->len);
 292                 goto success;
 293         }
 294
 295         ether_type = ((struct ethhdr *)skb->data)->h_proto;
 296
 297         crypt = ieee->crypt[ieee->tx_keyidx];
 298
 299         encrypt = !(ether_type == htons(ETH_P_PAE) && ieee->ieee802_1x) &&
 300             ieee->sec.encrypt;
 301
 302         host_encrypt = ieee->host_encrypt && encrypt && crypt;
 303         host_encrypt_msdu = ieee->host_encrypt_msdu && encrypt && crypt;
 304         host_build_iv = ieee->host_build_iv && encrypt && crypt;
 305
 306         if (!encrypt && ieee->ieee802_1x &&
 307             ieee->drop_unencrypted && ether_type != htons(ETH_P_PAE)) {
 308                 stats->tx_dropped++;
 309                 goto success;
 310         }
 311
 312         /* Save source and destination addresses */
 313         skb_copy_from_linear_data(skb, dest, ETH_ALEN);
 314         skb_copy_from_linear_data_offset(skb, ETH_ALEN, src, ETH_ALEN);
 315
 316         if (host_encrypt || host_build_iv)
 317                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA |
 318                     IEEE80211_FCTL_PROTECTED;
 319         else
 320                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;
 321
 322         if (ieee->iw_mode == IW_MODE_INFRA) {
 323                 fc |= IEEE80211_FCTL_TODS;
 324                 /* To DS: Addr1 = BSSID, Addr2 = SA, Addr3 = DA */
 325                 memcpy(header.addr1, ieee->bssid, ETH_ALEN);
 326                 memcpy(header.addr2, src, ETH_ALEN);
 327                 memcpy(header.addr3, dest, ETH_ALEN);
 328         } else if (ieee->iw_mode == IW_MODE_ADHOC) {
 329                 /* not From/To DS: Addr1 = DA, Addr2 = SA, Addr3 = BSSID */
 330                 memcpy(header.addr1, dest, ETH_ALEN);
 331                 memcpy(header.addr2, src, ETH_ALEN);
 332                 memcpy(header.addr3, ieee->bssid, ETH_ALEN);
 333         }
 334         hdr_len = IEEE80211_3ADDR_LEN;
 335
 336         if (ieee->is_qos_active && ieee->is_qos_active(dev, skb)) {
 337                 fc |= IEEE80211_STYPE_QOS_DATA;
 338                 hdr_len += 2;
 339
 340                 skb->priority = ieee80211_classify(skb);
 341                 header.qos_ctl |= cpu_to_le16(skb->priority & IEEE80211_QCTL_TID);
 342         }
 343         header.frame_ctl = cpu_to_le16(fc);
 344
 345         /* Advance the SKB to the start of the payload */
 346         skb_pull(skb, sizeof(struct ethhdr));
 347
 348         /* Determine total amount of storage required for TXB packets */
 349         bytes = skb->len + SNAP_SIZE + sizeof(u16);
 350
 351         /* Encrypt msdu first on the whole data packet. */
 352         if ((host_encrypt || host_encrypt_msdu) &&
 353             crypt && crypt->ops && crypt->ops->encrypt_msdu) {
 354                 int res = 0;
 355                 int len = bytes + hdr_len + crypt->ops->extra_msdu_prefix_len +
 356                     crypt->ops->extra_msdu_postfix_len;
 357                 struct sk_buff *skb_new = dev_alloc_skb(len);
 358
 359                 if (unlikely(!skb_new))
 360                         goto failed;
 361
 362                 skb_reserve(skb_new, crypt->ops->extra_msdu_prefix_len);
 363                 memcpy(skb_put(skb_new, hdr_len), &header, hdr_len);
 364                 snapped = 1;
 365                 ieee80211_copy_snap(skb_put(skb_new, SNAP_SIZE + sizeof(u16)),
 366                                     ether_type);
 367                 skb_copy_from_linear_data(skb, skb_put(skb_new, skb->len), skb->len);
 368                 res = crypt->ops->encrypt_msdu(skb_new, hdr_len, crypt->priv);
 369                 if (res < 0) {
 370                         IEEE80211_ERROR("msdu encryption failed\n");
 371                         dev_kfree_skb_any(skb_new);
 372                         goto failed;
 373                 }
 374                 dev_kfree_skb_any(skb);
 375                 skb = skb_new;
 376                 bytes += crypt->ops->extra_msdu_prefix_len +
 377                     crypt->ops->extra_msdu_postfix_len;
 378                 skb_pull(skb, hdr_len);
 379         }
 380
 381         if (host_encrypt || ieee->host_open_frag) {
 382                 /* Determine fragmentation size based on destination (multicast
 383                  * and broadcast are not fragmented) */
 384                 if (is_multicast_ether_addr(dest) ||
 385                     is_broadcast_ether_addr(dest))
 386                         frag_size = MAX_FRAG_THRESHOLD;
 387                 else
 388                         frag_size = ieee->fts;
 389
 390                 /* Determine amount of payload per fragment.  Regardless of if
 391                  * this stack is providing the full 802.11 header, one will
 392                  * eventually be affixed to this fragment -- so we must account
 393                  * for it when determining the amount of payload space. */
 394                 bytes_per_frag = frag_size - hdr_len;
 395                 if (ieee->config &
 396                     (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 397                         bytes_per_frag -= IEEE80211_FCS_LEN;
 398
 399                 /* Each fragment may need to have room for encryptiong
 400                  * pre/postfix */
 401                 if (host_encrypt)
 402                         bytes_per_frag -= crypt->ops->extra_mpdu_prefix_len +
 403                             crypt->ops->extra_mpdu_postfix_len;
 404
 405                 /* Number of fragments is the total
 406                  * bytes_per_frag / payload_per_fragment */
 407                 nr_frags = bytes / bytes_per_frag;
 408                 bytes_last_frag = bytes % bytes_per_frag;
 409                 if (bytes_last_frag)
 410                         nr_frags++;
 411                 else
 412                         bytes_last_frag = bytes_per_frag;
 413         } else {
 414                 nr_frags = 1;
 415                 bytes_per_frag = bytes_last_frag = bytes;
 416                 frag_size = bytes + hdr_len;
 417         }
 418
 419         rts_required = (frag_size > ieee->rts
 420                         && ieee->config & CFG_IEEE80211_RTS);
 421         if (rts_required)
 422                 nr_frags++;
 423
 424         /* When we allocate the TXB we allocate enough space for the reserve
 425          * and full fragment bytes (bytes_per_frag doesn't include prefix,
 426          * postfix, header, FCS, etc.) */
 427         txb = ieee80211_alloc_txb(nr_frags, frag_size,
 428                                   ieee->tx_headroom, GFP_ATOMIC);
 429         if (unlikely(!txb)) {
 430                 printk(KERN_WARNING "%s: Could not allocate TXB\n",
 431                        ieee->dev->name);
 432                 goto failed;
 433         }
 434         txb->encrypted = encrypt;
 435         if (host_encrypt)
 436                 txb->payload_size = frag_size * (nr_frags - 1) +
 437                     bytes_last_frag;
 438         else
 439                 txb->payload_size = bytes;
 440
 441         if (rts_required) {
 442                 skb_frag = txb->fragments[0];
 443                 frag_hdr =
 444                     (struct ieee80211_hdr_3addrqos *)skb_put(skb_frag, hdr_len);
 445
 446                 /*
 447                  * Set header frame_ctl to the RTS.
 448                  */
 449                 header.frame_ctl =
 450                     cpu_to_le16(IEEE80211_FTYPE_CTL | IEEE80211_STYPE_RTS);
 451                 memcpy(frag_hdr, &header, hdr_len);
 452
 453                 /*
 454                  * Restore header frame_ctl to the original data setting.
 455                  */
 456                 header.frame_ctl = cpu_to_le16(fc);
 457
 458                 if (ieee->config &
 459                     (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 460                         skb_put(skb_frag, 4);
 461
 462                 txb->rts_included = 1;
 463                 i = 1;
 464         } else
 465                 i = 0;
 466
 467         for (; i < nr_frags; i++) {
 468                 skb_frag = txb->fragments[i];
 469
 470                 if (host_encrypt || host_build_iv)
 471                         skb_reserve(skb_frag,
 472                                     crypt->ops->extra_mpdu_prefix_len);
 473
 474                 frag_hdr =
 475                     (struct ieee80211_hdr_3addrqos *)skb_put(skb_frag, hdr_len);
 476                 memcpy(frag_hdr, &header, hdr_len);
 477
 478                 /* If this is not the last fragment, then add the MOREFRAGS
 479                  * bit to the frame control */
 480                 if (i != nr_frags - 1) {
 481                         frag_hdr->frame_ctl =
 482                             cpu_to_le16(fc | IEEE80211_FCTL_MOREFRAGS);
 483                         bytes = bytes_per_frag;
 484                 } else {
 485                         /* The last fragment takes the remaining length */
 486                         bytes = bytes_last_frag;
 487                 }
 488
 489                 if (i == 0 && !snapped) {
 490                         ieee80211_copy_snap(skb_put
 491                                             (skb_frag, SNAP_SIZE + sizeof(u16)),
 492                                             ether_type);
 493                         bytes -= SNAP_SIZE + sizeof(u16);
 494                 }
 495
 496                 skb_copy_from_linear_data(skb, skb_put(skb_frag, bytes), bytes);
 497
 498                 /* Advance the SKB... */
 499                 skb_pull(skb, bytes);
 500
 501                 /* Encryption routine will move the header forward in order
 502                  * to insert the IV between the header and the payload */
 503                 if (host_encrypt)
 504                         ieee80211_encrypt_fragment(ieee, skb_frag, hdr_len);
 505                 else if (host_build_iv) {
 506                         atomic_inc(&crypt->refcnt);
 507                         if (crypt->ops->build_iv)
 508                                 crypt->ops->build_iv(skb_frag, hdr_len,
 509                                       ieee->sec.keys[ieee->sec.active_key],
 510                                       ieee->sec.key_sizes[ieee->sec.active_key],
 511                                       crypt->priv);
 512                         atomic_dec(&crypt->refcnt);
 513                 }
 514
 515                 if (ieee->config &
 516                     (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 517                         skb_put(skb_frag, 4);
 518         }
 519
 520       success:
 521         spin_unlock_irqrestore(&ieee->lock, flags);
 522
 523         dev_kfree_skb_any(skb);
 524
 525         if (txb) {
 526                 int ret = (*ieee->hard_start_xmit) (txb, dev, priority);
 527                 if (ret == 0) {
 528                         stats->tx_packets++;
 529                         stats->tx_bytes += txb->payload_size;
 530                         return 0;
 531                 }
 532
 533                 ieee80211_txb_free(txb);
 534         }
 535
 536         return 0;
 537
 538       failed:
 539         spin_unlock_irqrestore(&ieee->lock, flags);
 540         netif_stop_queue(dev);
 541         stats->tx_errors++;
 542         return 1;
 543 }
 544
 545 EXPORT_SYMBOL(ieee80211_txb_free);