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/proc_fs.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/slab.h>
  39 #include <linux/tcp.h>
  40 #include <linux/types.h>
  41 #include <linux/version.h>
  42 #include <linux/wireless.h>
  43 #include <linux/etherdevice.h>
  44 #include <asm/uaccess.h>
  45
  46 #include <net/ieee80211.h>
  47
  48 /*
  49
  50 802.11 Data Frame
  51
  52       ,-------------------------------------------------------------------.
  53 Bytes |  2   |  2   |    6    |    6    |    6    |  2   | 0..2312 |   4  |
  54       |------|------|---------|---------|---------|------|---------|------|
  55 Desc. | ctrl | dura |  DA/RA  |   TA    |    SA   | Sequ |  Frame  |  fcs |
  56       |      | tion | (BSSID) |         |         | ence |  data   |      |
  57       `--------------------------------------------------|         |------'
  58 Total: 28 non-data bytes                                 `----.----'
  59                                                               |
  60        .- 'Frame data' expands to <---------------------------'
  61        |
  62        V
  63       ,---------------------------------------------------.
  64 Bytes |  1   |  1   |    1    |    3     |  2   |  0-2304 |
  65       |------|------|---------|----------|------|---------|
  66 Desc. | SNAP | SNAP | Control |Eth Tunnel| Type | IP      |
  67       | DSAP | SSAP |         |          |      | Packet  |
  68       | 0xAA | 0xAA |0x03 (UI)|0x00-00-F8|      |         |
  69       `-----------------------------------------|         |
  70 Total: 8 non-data bytes                         `----.----'
  71                                                      |
  72        .- 'IP Packet' expands, if WEP enabled, to <--'
  73        |
  74        V
  75       ,-----------------------.
  76 Bytes |  4  |   0-2296  |  4  |
  77       |-----|-----------|-----|
  78 Desc. | IV  | Encrypted | ICV |
  79       |     | IP Packet |     |
  80       `-----------------------'
  81 Total: 8 non-data bytes
  82
  83 802.3 Ethernet Data Frame
  84
  85       ,-----------------------------------------.
  86 Bytes |   6   |   6   |  2   |  Variable |   4  |
  87       |-------|-------|------|-----------|------|
  88 Desc. | Dest. | Source| Type | IP Packet |  fcs |
  89       |  MAC  |  MAC  |      |           |      |
  90       `-----------------------------------------'
  91 Total: 18 non-data bytes
  92
  93 In the event that fragmentation is required, the incoming payload is split into
  94 N parts of size ieee->fts.  The first fragment contains the SNAP header and the
  95 remaining packets are just data.
  96
  97 If encryption is enabled, each fragment payload size is reduced by enough space
  98 to add the prefix and postfix (IV and ICV totalling 8 bytes in the case of WEP)
  99 So if you have 1500 bytes of payload with ieee->fts set to 500 without
 100 encryption it will take 3 frames.  With WEP it will take 4 frames as the
 101 payload of each frame is reduced to 492 bytes.
 102
 103 * SKB visualization
 104 *
 105 *  ,- skb->data
 106 * |
 107 * |    ETHERNET HEADER        ,-<-- PAYLOAD
 108 * |                           |     14 bytes from skb->data
 109 * |  2 bytes for Type --> ,T. |     (sizeof ethhdr)
 110 * |                       | | |
 111 * |,-Dest.--. ,--Src.---. | | |
 112 * |  6 bytes| | 6 bytes | | | |
 113 * v         | |         | | | |
 114 * 0         | v       1 | v | v           2
 115 * 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
 116 *     ^     | ^         | ^ |
 117 *     |     | |         | | |
 118 *     |     | |         | `T' <---- 2 bytes for Type
 119 *     |     | |         |
 120 *     |     | '---SNAP--' <-------- 6 bytes for SNAP
 121 *     |     |
 122 *     `-IV--' <-------------------- 4 bytes for IV (WEP)
 123 *
 124 *      SNAP HEADER
 125 *
 126 */
 127
 128 static u8 P802_1H_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0xf8 };
 129 static u8 RFC1042_OUI[P80211_OUI_LEN] = { 0x00, 0x00, 0x00 };
 130
 131 static inline int ieee80211_put_snap(u8 * data, u16 h_proto)
 132 {
 133         struct ieee80211_snap_hdr *snap;
 134         u8 *oui;
 135
 136         snap = (struct ieee80211_snap_hdr *)data;
 137         snap->dsap = 0xaa;
 138         snap->ssap = 0xaa;
 139         snap->ctrl = 0x03;
 140
 141         if (h_proto == 0x8137 || h_proto == 0x80f3)
 142                 oui = P802_1H_OUI;
 143         else
 144                 oui = RFC1042_OUI;
 145         snap->oui[0] = oui[0];
 146         snap->oui[1] = oui[1];
 147         snap->oui[2] = oui[2];
 148
 149         *(u16 *) (data + SNAP_SIZE) = htons(h_proto);
 150
 151         return SNAP_SIZE + sizeof(u16);
 152 }
 153
 154 static inline int ieee80211_encrypt_fragment(struct ieee80211_device *ieee,
 155                                              struct sk_buff *frag, int hdr_len)
 156 {
 157         struct ieee80211_crypt_data *crypt = ieee->crypt[ieee->tx_keyidx];
 158         int res;
 159
 160         /* To encrypt, frame format is:
 161          * IV (4 bytes), clear payload (including SNAP), ICV (4 bytes) */
 162
 163         // PR: FIXME: Copied from hostap. Check fragmentation/MSDU/MPDU encryption.
 164         /* Host-based IEEE 802.11 fragmentation for TX is not yet supported, so
 165          * call both MSDU and MPDU encryption functions from here. */
 166         atomic_inc(&crypt->refcnt);
 167         res = 0;
 168         if (crypt->ops->encrypt_msdu)
 169                 res = crypt->ops->encrypt_msdu(frag, hdr_len, crypt->priv);
 170         if (res == 0 && crypt->ops->encrypt_mpdu)
 171                 res = crypt->ops->encrypt_mpdu(frag, hdr_len, crypt->priv);
 172
 173         atomic_dec(&crypt->refcnt);
 174         if (res < 0) {
 175                 printk(KERN_INFO "%s: Encryption failed: len=%d.\n",
 176                        ieee->dev->name, frag->len);
 177                 ieee->ieee_stats.tx_discards++;
 178                 return -1;
 179         }
 180
 181         return 0;
 182 }
 183
 184 void ieee80211_txb_free(struct ieee80211_txb *txb)
 185 {
 186         int i;
 187         if (unlikely(!txb))
 188                 return;
 189         for (i = 0; i < txb->nr_frags; i++)
 190                 if (txb->fragments[i])
 191                         dev_kfree_skb_any(txb->fragments[i]);
 192         kfree(txb);
 193 }
 194
 195 static struct ieee80211_txb *ieee80211_alloc_txb(int nr_frags, int txb_size,
 196                                                  int gfp_mask)
 197 {
 198         struct ieee80211_txb *txb;
 199         int i;
 200         txb = kmalloc(sizeof(struct ieee80211_txb) + (sizeof(u8 *) * nr_frags),
 201                       gfp_mask);
 202         if (!txb)
 203                 return NULL;
 204
 205         memset(txb, 0, sizeof(struct ieee80211_txb));
 206         txb->nr_frags = nr_frags;
 207         txb->frag_size = txb_size;
 208
 209         for (i = 0; i < nr_frags; i++) {
 210                 txb->fragments[i] = dev_alloc_skb(txb_size);
 211                 if (unlikely(!txb->fragments[i])) {
 212                         i--;
 213                         break;
 214                 }
 215         }
 216         if (unlikely(i != nr_frags)) {
 217                 while (i >= 0)
 218                         dev_kfree_skb_any(txb->fragments[i--]);
 219                 kfree(txb);
 220                 return NULL;
 221         }
 222         return txb;
 223 }
 224
 225 /* SKBs are added to the ieee->tx_queue. */
 226 int ieee80211_xmit(struct sk_buff *skb, struct net_device *dev)
 227 {
 228         struct ieee80211_device *ieee = netdev_priv(dev);
 229         struct ieee80211_txb *txb = NULL;
 230         struct ieee80211_hdr *frag_hdr;
 231         int i, bytes_per_frag, nr_frags, bytes_last_frag, frag_size;
 232         unsigned long flags;
 233         struct net_device_stats *stats = &ieee->stats;
 234         int ether_type, encrypt;
 235         int bytes, fc, hdr_len;
 236         struct sk_buff *skb_frag;
 237         struct ieee80211_hdr header = { /* Ensure zero initialized */
 238                 .duration_id = 0,
 239                 .seq_ctl = 0
 240         };
 241         u8 dest[ETH_ALEN], src[ETH_ALEN];
 242
 243         struct ieee80211_crypt_data *crypt;
 244
 245         spin_lock_irqsave(&ieee->lock, flags);
 246
 247         /* If there is no driver handler to take the TXB, dont' bother
 248          * creating it... */
 249         if (!ieee->hard_start_xmit) {
 250                 printk(KERN_WARNING "%s: No xmit handler.\n", ieee->dev->name);
 251                 goto success;
 252         }
 253
 254         if (unlikely(skb->len < SNAP_SIZE + sizeof(u16))) {
 255                 printk(KERN_WARNING "%s: skb too small (%d).\n",
 256                        ieee->dev->name, skb->len);
 257                 goto success;
 258         }
 259
 260         ether_type = ntohs(((struct ethhdr *)skb->data)->h_proto);
 261
 262         crypt = ieee->crypt[ieee->tx_keyidx];
 263
 264         encrypt = !(ether_type == ETH_P_PAE && ieee->ieee802_1x) &&
 265             ieee->host_encrypt && crypt && crypt->ops;
 266
 267         if (!encrypt && ieee->ieee802_1x &&
 268             ieee->drop_unencrypted && ether_type != ETH_P_PAE) {
 269                 stats->tx_dropped++;
 270                 goto success;
 271         }
 272
 273         /* Save source and destination addresses */
 274         memcpy(dest, skb->data, ETH_ALEN);
 275         memcpy(src, skb->data + ETH_ALEN, ETH_ALEN);
 276
 277         /* Advance the SKB to the start of the payload */
 278         skb_pull(skb, sizeof(struct ethhdr));
 279
 280         /* Determine total amount of storage required for TXB packets */
 281         bytes = skb->len + SNAP_SIZE + sizeof(u16);
 282
 283         if (encrypt)
 284                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA |
 285                     IEEE80211_FCTL_PROTECTED;
 286         else
 287                 fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;
 288
 289         if (ieee->iw_mode == IW_MODE_INFRA) {
 290                 fc |= IEEE80211_FCTL_TODS;
 291                 /* To DS: Addr1 = BSSID, Addr2 = SA,
 292                    Addr3 = DA */
 293                 memcpy(header.addr1, ieee->bssid, ETH_ALEN);
 294                 memcpy(header.addr2, src, ETH_ALEN);
 295                 memcpy(header.addr3, dest, ETH_ALEN);
 296         } else if (ieee->iw_mode == IW_MODE_ADHOC) {
 297                 /* not From/To DS: Addr1 = DA, Addr2 = SA,
 298                    Addr3 = BSSID */
 299                 memcpy(header.addr1, dest, ETH_ALEN);
 300                 memcpy(header.addr2, src, ETH_ALEN);
 301                 memcpy(header.addr3, ieee->bssid, ETH_ALEN);
 302         }
 303         header.frame_ctl = cpu_to_le16(fc);
 304         hdr_len = IEEE80211_3ADDR_LEN;
 305
 306         /* Determine fragmentation size based on destination (multicast
 307          * and broadcast are not fragmented) */
 308         if (is_multicast_ether_addr(dest) || is_broadcast_ether_addr(dest))
 309                 frag_size = MAX_FRAG_THRESHOLD;
 310         else
 311                 frag_size = ieee->fts;
 312
 313         /* Determine amount of payload per fragment.  Regardless of if
 314          * this stack is providing the full 802.11 header, one will
 315          * eventually be affixed to this fragment -- so we must account for
 316          * it when determining the amount of payload space. */
 317         bytes_per_frag = frag_size - IEEE80211_3ADDR_LEN;
 318         if (ieee->config &
 319             (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 320                 bytes_per_frag -= IEEE80211_FCS_LEN;
 321
 322         /* Each fragment may need to have room for encryptiong pre/postfix */
 323         if (encrypt)
 324                 bytes_per_frag -= crypt->ops->extra_prefix_len +
 325                     crypt->ops->extra_postfix_len;
 326
 327         /* Number of fragments is the total bytes_per_frag /
 328          * payload_per_fragment */
 329         nr_frags = bytes / bytes_per_frag;
 330         bytes_last_frag = bytes % bytes_per_frag;
 331         if (bytes_last_frag)
 332                 nr_frags++;
 333         else
 334                 bytes_last_frag = bytes_per_frag;
 335
 336         /* When we allocate the TXB we allocate enough space for the reserve
 337          * and full fragment bytes (bytes_per_frag doesn't include prefix,
 338          * postfix, header, FCS, etc.) */
 339         txb = ieee80211_alloc_txb(nr_frags, frag_size, GFP_ATOMIC);
 340         if (unlikely(!txb)) {
 341                 printk(KERN_WARNING "%s: Could not allocate TXB\n",
 342                        ieee->dev->name);
 343                 goto failed;
 344         }
 345         txb->encrypted = encrypt;
 346         txb->payload_size = bytes;
 347
 348         for (i = 0; i < nr_frags; i++) {
 349                 skb_frag = txb->fragments[i];
 350
 351                 if (encrypt)
 352                         skb_reserve(skb_frag, crypt->ops->extra_prefix_len);
 353
 354                 frag_hdr = (struct ieee80211_hdr *)skb_put(skb_frag, hdr_len);
 355                 memcpy(frag_hdr, &header, hdr_len);
 356
 357                 /* If this is not the last fragment, then add the MOREFRAGS
 358                  * bit to the frame control */
 359                 if (i != nr_frags - 1) {
 360                         frag_hdr->frame_ctl =
 361                             cpu_to_le16(fc | IEEE80211_FCTL_MOREFRAGS);
 362                         bytes = bytes_per_frag;
 363                 } else {
 364                         /* The last fragment takes the remaining length */
 365                         bytes = bytes_last_frag;
 366                 }
 367
 368                 /* Put a SNAP header on the first fragment */
 369                 if (i == 0) {
 370                         ieee80211_put_snap(skb_put
 371                                            (skb_frag, SNAP_SIZE + sizeof(u16)),
 372                                            ether_type);
 373                         bytes -= SNAP_SIZE + sizeof(u16);
 374                 }
 375
 376                 memcpy(skb_put(skb_frag, bytes), skb->data, bytes);
 377
 378                 /* Advance the SKB... */
 379                 skb_pull(skb, bytes);
 380
 381                 /* Encryption routine will move the header forward in order
 382                  * to insert the IV between the header and the payload */
 383                 if (encrypt)
 384                         ieee80211_encrypt_fragment(ieee, skb_frag, hdr_len);
 385                 if (ieee->config &
 386                     (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 387                         skb_put(skb_frag, 4);
 388         }
 389
 390       success:
 391         spin_unlock_irqrestore(&ieee->lock, flags);
 392
 393         dev_kfree_skb_any(skb);
 394
 395         if (txb) {
 396                 if ((*ieee->hard_start_xmit) (txb, dev) == 0) {
 397                         stats->tx_packets++;
 398                         stats->tx_bytes += txb->payload_size;
 399                         return 0;
 400                 }
 401                 ieee80211_txb_free(txb);
 402         }
 403
 404         return 0;
 405
 406       failed:
 407         spin_unlock_irqrestore(&ieee->lock, flags);
 408         netif_stop_queue(dev);
 409         stats->tx_errors++;
 410         return 1;
 411
 412 }
 413
 414 EXPORT_SYMBOL(ieee80211_txb_free);