net/ieee80211/ieee80211_tx.c

   1 /******************************************************************************
   2
   3   Copyright(c) 2003 - 2004 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/config.h>
  28 #include <linux/errno.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/in6.h>
  31 #include <linux/in.h>
  32 #include <linux/ip.h>
  33 #include <linux/kernel.h>
  34 #include <linux/module.h>
  35 #include <linux/netdevice.h>
  36 #include <linux/pci.h>
  37 #include <linux/proc_fs.h>
  38 #include <linux/skbuff.h>
  39 #include <linux/slab.h>
  40 #include <linux/tcp.h>
  41 #include <linux/types.h>
  42 #include <linux/version.h>
  43 #include <linux/wireless.h>
  44 #include <linux/etherdevice.h>
  45 #include <asm/uaccess.h>
  46
  47 #include <net/ieee80211.h>
  48
  49
  50 /*
  51
  52
  53 802.11 Data Frame
  54
  55       ,-------------------------------------------------------------------.
  56 Bytes |  2   |  2   |    6    |    6    |    6    |  2   | 0..2312 |   4  |
  57       |------|------|---------|---------|---------|------|---------|------|
  58 Desc. | ctrl | dura |  DA/RA  |   TA    |    SA   | Sequ |  Frame  |  fcs |
  59       |      | tion | (BSSID) |         |         | ence |  data   |      |
  60       `--------------------------------------------------|         |------'
  61 Total: 28 non-data bytes                                 `----.----'
  62                                                               |
  63        .- 'Frame data' expands to <---------------------------'
  64        |
  65        V
  66       ,---------------------------------------------------.
  67 Bytes |  1   |  1   |    1    |    3     |  2   |  0-2304 |
  68       |------|------|---------|----------|------|---------|
  69 Desc. | SNAP | SNAP | Control |Eth Tunnel| Type | IP      |
  70       | DSAP | SSAP |         |          |      | Packet  |
  71       | 0xAA | 0xAA |0x03 (UI)|0x00-00-F8|      |         |
  72       `-----------------------------------------|         |
  73 Total: 8 non-data bytes                         `----.----'
  74                                                      |
  75        .- 'IP Packet' expands, if WEP enabled, to <--'
  76        |
  77        V
  78       ,-----------------------.
  79 Bytes |  4  |   0-2296  |  4  |
  80       |-----|-----------|-----|
  81 Desc. | IV  | Encrypted | ICV |
  82       |     | IP Packet |     |
  83       `-----------------------'
  84 Total: 8 non-data bytes
  85
  86
  87 802.3 Ethernet Data Frame
  88
  89       ,-----------------------------------------.
  90 Bytes |   6   |   6   |  2   |  Variable |   4  |
  91       |-------|-------|------|-----------|------|
  92 Desc. | Dest. | Source| Type | IP Packet |  fcs |
  93       |  MAC  |  MAC  |      |           |      |
  94       `-----------------------------------------'
  95 Total: 18 non-data bytes
  96
  97 In the event that fragmentation is required, the incoming payload is split into
  98 N parts of size ieee->fts.  The first fragment contains the SNAP header and the
  99 remaining packets are just data.
 100
 101 If encryption is enabled, each fragment payload size is reduced by enough space
 102 to add the prefix and postfix (IV and ICV totalling 8 bytes in the case of WEP)
 103 So if you have 1500 bytes of payload with ieee->fts set to 500 without
 104 encryption it will take 3 frames.  With WEP it will take 4 frames as the
 105 payload of each frame is reduced to 492 bytes.
 106
 107 * SKB visualization
 108 *
 109 *  ,- skb->data
 110 * |
 111 * |    ETHERNET HEADER        ,-<-- PAYLOAD
 112 * |                           |     14 bytes from skb->data
 113 * |  2 bytes for Type --> ,T. |     (sizeof ethhdr)
 114 * |                       | | |
 115 * |,-Dest.--. ,--Src.---. | | |
 116 * |  6 bytes| | 6 bytes | | | |
 117 * v         | |         | | | |
 118 * 0         | v       1 | v | v           2
 119 * 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
 120 *     ^     | ^         | ^ |
 121 *     |     | |         | | |
 122 *     |     | |         | `T' <---- 2 bytes for Type
 123 *     |     | |         |
 124 *     |     | '---SNAP--' <-------- 6 bytes for SNAP
 125 *     |     |
 126 *     `-IV--' <-------------------- 4 bytes for IV (WEP)
 127 *
 128 *      SNAP HEADER
 129 *
 130 */
 131
 132 static u8 P802_1H_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0xf8 };
 133 static u8 RFC1042_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0x00 };
 134
 135 static inline int ieee80211_put_snap(u8 *data, u16 h_proto)
 136 {
 137         struct ieee80211_snap_hdr *snap;
 138         u8 *oui;
 139
 140         snap = (struct ieee80211_snap_hdr *)data;
 141         snap->dsap = 0xaa;
 142         snap->ssap = 0xaa;
 143         snap->ctrl = 0x03;
 144
 145         if (h_proto == 0x8137 || h_proto == 0x80f3)
 146                 oui = P802_1H_OUI;
 147         else
 148                 oui = RFC1042_OUI;
 149         snap->oui[0] = oui[0];
 150         snap->oui[1] = oui[1];
 151         snap->oui[2] = oui[2];
 152
 153         *(u16 *)(data + SNAP_SIZE) = htons(h_proto);
 154
 155         return SNAP_SIZE + sizeof(u16);
 156 }
 157
 158 static inline int ieee80211_encrypt_fragment(
 159         struct ieee80211_device *ieee,
 160         struct sk_buff *frag,
 161         int hdr_len)
 162 {
 163         struct ieee80211_crypt_data* crypt = ieee->crypt[ieee->tx_keyidx];
 164         int res;
 165
 166 #ifdef CONFIG_IEEE80211_CRYPT_TKIP
 167         struct ieee80211_hdr *header;
 168
 169         if (ieee->tkip_countermeasures &&
 170             crypt && crypt->ops && strcmp(crypt->ops->name, "TKIP") == 0) {
 171                 header = (struct ieee80211_hdr *) frag->data;
 172                 if (net_ratelimit()) {
 173                         printk(KERN_DEBUG "%s: TKIP countermeasures: dropped "
 174                                "TX packet to " MAC_FMT "\n",
 175                                ieee->dev->name, MAC_ARG(header->addr1));
 176                 }
 177                 return -1;
 178         }
 179 #endif
 180         /* To encrypt, frame format is:
 181          * IV (4 bytes), clear payload (including SNAP), ICV (4 bytes) */
 182
 183         // PR: FIXME: Copied from hostap. Check fragmentation/MSDU/MPDU encryption.
 184         /* Host-based IEEE 802.11 fragmentation for TX is not yet supported, so
 185          * call both MSDU and MPDU encryption functions from here. */
 186         atomic_inc(&crypt->refcnt);
 187         res = 0;
 188         if (crypt->ops->encrypt_msdu)
 189                 res = crypt->ops->encrypt_msdu(frag, hdr_len, crypt->priv);
 190         if (res == 0 && crypt->ops->encrypt_mpdu)
 191                 res = crypt->ops->encrypt_mpdu(frag, hdr_len, crypt->priv);
 192
 193         atomic_dec(&crypt->refcnt);
 194         if (res < 0) {
 195                 printk(KERN_INFO "%s: Encryption failed: len=%d.\n",
 196                        ieee->dev->name, frag->len);
 197                 ieee->ieee_stats.tx_discards++;
 198                 return -1;
 199         }
 200
 201         return 0;
 202 }
 203
 204
 205 void ieee80211_txb_free(struct ieee80211_txb *txb) {
 206         int i;
 207         if (unlikely(!txb))
 208                 return;
 209         for (i = 0; i < txb->nr_frags; i++)
 210                 if (txb->fragments[i])
 211                         dev_kfree_skb_any(txb->fragments[i]);
 212         kfree(txb);
 213 }
 214
 215 static struct ieee80211_txb *ieee80211_alloc_txb(int nr_frags, int txb_size,
 216                                                  int gfp_mask)
 217 {
 218         struct ieee80211_txb *txb;
 219         int i;
 220         txb = kmalloc(
 221                 sizeof(struct ieee80211_txb) + (sizeof(u8*) * nr_frags),
 222                 gfp_mask);
 223         if (!txb)
 224                 return NULL;
 225
 226         memset(txb, 0, sizeof(struct ieee80211_txb));
 227         txb->nr_frags = nr_frags;
 228         txb->frag_size = txb_size;
 229
 230         for (i = 0; i < nr_frags; i++) {
 231                 txb->fragments[i] = dev_alloc_skb(txb_size);
 232                 if (unlikely(!txb->fragments[i])) {
 233                         i--;
 234                         break;
 235                 }
 236         }
 237         if (unlikely(i != nr_frags)) {
 238                 while (i >= 0)
 239                         dev_kfree_skb_any(txb->fragments[i--]);
 240                 kfree(txb);
 241                 return NULL;
 242         }
 243         return txb;
 244 }
 245
 246 /* SKBs are added to the ieee->tx_queue. */
 247 int ieee80211_xmit(struct sk_buff *skb,
 248                    struct net_device *dev)
 249 {
 250         struct ieee80211_device *ieee = netdev_priv(dev);
 251         struct ieee80211_txb *txb = NULL;
 252         struct ieee80211_hdr *frag_hdr;
 253         int i, bytes_per_frag, nr_frags, bytes_last_frag, frag_size;
 254         unsigned long flags;
 255         struct net_device_stats *stats = &ieee->stats;
 256         int ether_type, encrypt;
 257         int bytes, fc, hdr_len;
 258         struct sk_buff *skb_frag;
 259         struct ieee80211_hdr header = { /* Ensure zero initialized */
 260                 .duration_id = 0,
 261                 .seq_ctl = 0
 262         };
 263         u8 dest[ETH_ALEN], src[ETH_ALEN];
 264
 265         struct ieee80211_crypt_data* crypt;
 266
 267         spin_lock_irqsave(&ieee->lock, flags);
 268
 269         /* If there is no driver handler to take the TXB, dont' bother
 270          * creating it... */
 271         if (!ieee->hard_start_xmit) {
 272                 printk(KERN_WARNING "%s: No xmit handler.\n",
 273                        ieee->dev->name);
 274                 goto success;
 275         }
 276
 277         if (unlikely(skb->len < SNAP_SIZE + sizeof(u16))) {
 278                 printk(KERN_WARNING "%s: skb too small (%d).\n",
 279                        ieee->dev->name, skb->len);
 280                 goto success;
 281         }
 282
 283         ether_type = ntohs(((struct ethhdr *)skb->data)->h_proto);
 284
 285         crypt = ieee->crypt[ieee->tx_keyidx];
 286
 287         encrypt = !(ether_type == ETH_P_PAE && ieee->ieee802_1x) &&
 288                 ieee->host_encrypt && crypt && crypt->ops;
 289
 290         if (!encrypt && ieee->ieee802_1x &&
 291             ieee->drop_unencrypted && ether_type != ETH_P_PAE) {
 292                 stats->tx_dropped++;
 293                 goto success;
 294         }
 295
 296 #ifdef CONFIG_IEEE80211_DEBUG
 297         if (crypt && !encrypt && ether_type == ETH_P_PAE) {
 298                 struct eapol *eap = (struct eapol *)(skb->data +
 299                         sizeof(struct ethhdr) - SNAP_SIZE - sizeof(u16));
 300                 IEEE80211_DEBUG_EAP("TX: IEEE 802.11 EAPOL frame: %s\n",
 301                         eap_get_type(eap->type));
 302         }
 303 #endif
 304
 305         /* Save source and destination addresses */
 306         memcpy(&dest, skb->data, ETH_ALEN);
 307         memcpy(&src, skb->data+ETH_ALEN, ETH_ALEN);
 308
 309         /* Advance the SKB to the start of the payload */
 310         skb_pull(skb, sizeof(struct ethhdr));
 311
 312         /* Determine total amount of storage required for TXB packets */
 313         bytes = skb->len + SNAP_SIZE + sizeof(u16);
 314
 315         if (encrypt)
 316                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA |
 317                         IEEE80211_FCTL_WEP;
 318         else
 319                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;
 320
 321         if (ieee->iw_mode == IW_MODE_INFRA) {
 322                 fc |= IEEE80211_FCTL_TODS;
 323                 /* To DS: Addr1 = BSSID, Addr2 = SA,
 324                    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,
 330                    Addr3 = BSSID */
 331                 memcpy(&header.addr1, dest, ETH_ALEN);
 332                 memcpy(&header.addr2, src, ETH_ALEN);
 333                 memcpy(&header.addr3, ieee->bssid, ETH_ALEN);
 334         }
 335         header.frame_ctl = cpu_to_le16(fc);
 336         hdr_len = IEEE80211_3ADDR_LEN;
 337
 338         /* Determine fragmentation size based on destination (multicast
 339          * and broadcast are not fragmented) */
 340         if (is_multicast_ether_addr(dest) ||
 341             is_broadcast_ether_addr(dest))
 342                 frag_size = MAX_FRAG_THRESHOLD;
 343         else
 344                 frag_size = ieee->fts;
 345
 346         /* Determine amount of payload per fragment.  Regardless of if
 347          * this stack is providing the full 802.11 header, one will
 348          * eventually be affixed to this fragment -- so we must account for
 349          * it when determining the amount of payload space. */
 350         bytes_per_frag = frag_size - IEEE80211_3ADDR_LEN;
 351         if (ieee->config &
 352             (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 353                 bytes_per_frag -= IEEE80211_FCS_LEN;
 354
 355         /* Each fragment may need to have room for encryptiong pre/postfix */
 356         if (encrypt)
 357                 bytes_per_frag -= crypt->ops->extra_prefix_len +
 358                         crypt->ops->extra_postfix_len;
 359
 360         /* Number of fragments is the total bytes_per_frag /
 361          * payload_per_fragment */
 362         nr_frags = bytes / bytes_per_frag;
 363         bytes_last_frag = bytes % bytes_per_frag;
 364         if (bytes_last_frag)
 365                 nr_frags++;
 366         else
 367                 bytes_last_frag = bytes_per_frag;
 368
 369         /* When we allocate the TXB we allocate enough space for the reserve
 370          * and full fragment bytes (bytes_per_frag doesn't include prefix,
 371          * postfix, header, FCS, etc.) */
 372         txb = ieee80211_alloc_txb(nr_frags, frag_size, GFP_ATOMIC);
 373         if (unlikely(!txb)) {
 374                 printk(KERN_WARNING "%s: Could not allocate TXB\n",
 375                        ieee->dev->name);
 376                 goto failed;
 377         }
 378         txb->encrypted = encrypt;
 379         txb->payload_size = bytes;
 380
 381         for (i = 0; i < nr_frags; i++) {
 382                 skb_frag = txb->fragments[i];
 383
 384                 if (encrypt)
 385                         skb_reserve(skb_frag, crypt->ops->extra_prefix_len);
 386
 387                 frag_hdr = (struct ieee80211_hdr *)skb_put(skb_frag, hdr_len);
 388                 memcpy(frag_hdr, &header, hdr_len);
 389
 390                 /* If this is not the last fragment, then add the MOREFRAGS
 391                  * bit to the frame control */
 392                 if (i != nr_frags - 1) {
 393                         frag_hdr->frame_ctl = cpu_to_le16(
 394                                 fc | IEEE80211_FCTL_MOREFRAGS);
 395                         bytes = bytes_per_frag;
 396                 } else {
 397                         /* The last fragment takes the remaining length */
 398                         bytes = bytes_last_frag;
 399                 }
 400
 401                 /* Put a SNAP header on the first fragment */
 402                 if (i == 0) {
 403                         ieee80211_put_snap(
 404                                 skb_put(skb_frag, SNAP_SIZE + sizeof(u16)),
 405                                 ether_type);
 406                         bytes -= SNAP_SIZE + sizeof(u16);
 407                 }
 408
 409                 memcpy(skb_put(skb_frag, bytes), skb->data, bytes);
 410
 411                 /* Advance the SKB... */
 412                 skb_pull(skb, bytes);
 413
 414                 /* Encryption routine will move the header forward in order
 415                  * to insert the IV between the header and the payload */
 416                 if (encrypt)
 417                         ieee80211_encrypt_fragment(ieee, skb_frag, hdr_len);
 418                 if (ieee->config &
 419                     (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 420                         skb_put(skb_frag, 4);
 421         }
 422
 423
 424  success:
 425         spin_unlock_irqrestore(&ieee->lock, flags);
 426
 427         dev_kfree_skb_any(skb);
 428
 429         if (txb) {
 430                 if ((*ieee->hard_start_xmit)(txb, dev) == 0) {
 431                         stats->tx_packets++;
 432                         stats->tx_bytes += txb->payload_size;
 433                         return 0;
 434                 }
 435                 ieee80211_txb_free(txb);
 436         }
 437
 438         return 0;
 439
 440  failed:
 441         spin_unlock_irqrestore(&ieee->lock, flags);
 442         netif_stop_queue(dev);
 443         stats->tx_errors++;
 444         return 1;
 445
 446 }
 447
 448 EXPORT_SYMBOL(ieee80211_txb_free);