drivers/net/wan/lapbether.c

   1 /*
   2  *      "LAPB via ethernet" driver release 001
   3  *
   4  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      This is a "pseudo" network driver to allow LAPB over Ethernet.
  13  *
  14  *      This driver can use any ethernet destination address, and can be
  15  *      limited to accept frames from one dedicated ethernet card only.
  16  *
  17  *      History
  18  *      LAPBETH 001     Jonathan Naylor         Cloned from bpqether.c
  19  *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
  20  *      2000-11-14      Henner Eisen    dev_hold/put, NETDEV_GOING_DOWN support
  21  */
  22
  23 #include <linux/errno.h>
  24 #include <linux/types.h>
  25 #include <linux/socket.h>
  26 #include <linux/in.h>
  27 #include <linux/kernel.h>
  28 #include <linux/string.h>
  29 #include <linux/net.h>
  30 #include <linux/inet.h>
  31 #include <linux/netdevice.h>
  32 #include <linux/if_arp.h>
  33 #include <linux/skbuff.h>
  34 #include <net/sock.h>
  35 #include <asm/system.h>
  36 #include <asm/uaccess.h>
  37 #include <linux/mm.h>
  38 #include <linux/interrupt.h>
  39 #include <linux/notifier.h>
  40 #include <linux/stat.h>
  41 #include <linux/netfilter.h>
  42 #include <linux/module.h>
  43 #include <linux/lapb.h>
  44 #include <linux/init.h>
  45
  46 #include <net/x25device.h>
  47
  48 static char bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  49
  50 /* If this number is made larger, check that the temporary string buffer
  51  * in lapbeth_new_device is large enough to store the probe device name.*/
  52 #define MAXLAPBDEV 100
  53
  54 struct lapbethdev {
  55         struct list_head        node;
  56         struct net_device       *ethdev;        /* link to ethernet device */
  57         struct net_device       *axdev;         /* lapbeth device (lapb#) */
  58         struct net_device_stats stats;          /* some statistics */
  59 };
  60
  61 static LIST_HEAD(lapbeth_devices);
  62
  63 /* ------------------------------------------------------------------------ */
  64
  65 /*
  66  *      Get the LAPB device for the ethernet device
  67  */
  68 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  69 {
  70         struct lapbethdev *lapbeth;
  71
  72         list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  73                 if (lapbeth->ethdev == dev)
  74                         return lapbeth;
  75         }
  76         return NULL;
  77 }
  78
  79 static __inline__ int dev_is_ethdev(struct net_device *dev)
  80 {
  81         return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  82 }
  83
  84 /* ------------------------------------------------------------------------ */
  85
  86 /*
  87  *      Receive a LAPB frame via an ethernet interface.
  88  */
  89 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  90 {
  91         int len, err;
  92         struct lapbethdev *lapbeth;
  93
  94         if (dev_net(dev) != &init_net)
  95                 goto drop;
  96
  97         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  98                 return NET_RX_DROP;
  99
 100         if (!pskb_may_pull(skb, 2))
 101                 goto drop;
 102
 103         rcu_read_lock();
 104         lapbeth = lapbeth_get_x25_dev(dev);
 105         if (!lapbeth)
 106                 goto drop_unlock;
 107         if (!netif_running(lapbeth->axdev))
 108                 goto drop_unlock;
 109
 110         lapbeth->stats.rx_packets++;
 111
 112         len = skb->data[0] + skb->data[1] * 256;
 113         lapbeth->stats.rx_bytes += len;
 114
 115         skb_pull(skb, 2);       /* Remove the length bytes */
 116         skb_trim(skb, len);     /* Set the length of the data */
 117
 118         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 119                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 120                 goto drop_unlock;
 121         }
 122 out:
 123         rcu_read_unlock();
 124         return 0;
 125 drop_unlock:
 126         kfree_skb(skb);
 127         goto out;
 128 drop:
 129         kfree_skb(skb);
 130         return 0;
 131 }
 132
 133 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 134 {
 135         unsigned char *ptr;
 136
 137         skb_push(skb, 1);
 138
 139         if (skb_cow(skb, 1))
 140                 return NET_RX_DROP;
 141
 142         ptr  = skb->data;
 143         *ptr = 0x00;
 144
 145         skb->protocol = x25_type_trans(skb, dev);
 146         skb->dev->last_rx = jiffies;
 147         return netif_rx(skb);
 148 }
 149
 150 /*
 151  *      Send a LAPB frame via an ethernet interface
 152  */
 153 static int lapbeth_xmit(struct sk_buff *skb, struct net_device *dev)
 154 {
 155         int err = -ENODEV;
 156
 157         /*
 158          * Just to be *really* sure not to send anything if the interface
 159          * is down, the ethernet device may have gone.
 160          */
 161         if (!netif_running(dev)) {
 162                 goto drop;
 163         }
 164
 165         switch (skb->data[0]) {
 166         case 0x00:
 167                 err = 0;
 168                 break;
 169         case 0x01:
 170                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 171                         printk(KERN_ERR "lapbeth: lapb_connect_request "
 172                                "error: %d\n", err);
 173                 goto drop_ok;
 174         case 0x02:
 175                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 176                         printk(KERN_ERR "lapbeth: lapb_disconnect_request "
 177                                "err: %d\n", err);
 178                 /* Fall thru */
 179         default:
 180                 goto drop_ok;
 181         }
 182
 183         skb_pull(skb, 1);
 184
 185         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 186                 printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
 187                 err = -ENOMEM;
 188                 goto drop;
 189         }
 190         err = 0;
 191 out:
 192         return err;
 193 drop_ok:
 194         err = 0;
 195 drop:
 196         kfree_skb(skb);
 197         goto out;
 198 }
 199
 200 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 201 {
 202         struct lapbethdev *lapbeth = netdev_priv(ndev);
 203         unsigned char *ptr;
 204         struct net_device *dev;
 205         int size = skb->len;
 206
 207         skb->protocol = htons(ETH_P_X25);
 208
 209         ptr = skb_push(skb, 2);
 210
 211         *ptr++ = size % 256;
 212         *ptr++ = size / 256;
 213
 214         lapbeth->stats.tx_packets++;
 215         lapbeth->stats.tx_bytes += size;
 216
 217         skb->dev = dev = lapbeth->ethdev;
 218
 219         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 220
 221         dev_queue_xmit(skb);
 222 }
 223
 224 static void lapbeth_connected(struct net_device *dev, int reason)
 225 {
 226         unsigned char *ptr;
 227         struct sk_buff *skb = dev_alloc_skb(1);
 228
 229         if (!skb) {
 230                 printk(KERN_ERR "lapbeth: out of memory\n");
 231                 return;
 232         }
 233
 234         ptr  = skb_put(skb, 1);
 235         *ptr = 0x01;
 236
 237         skb->protocol = x25_type_trans(skb, dev);
 238         skb->dev->last_rx = jiffies;
 239         netif_rx(skb);
 240 }
 241
 242 static void lapbeth_disconnected(struct net_device *dev, int reason)
 243 {
 244         unsigned char *ptr;
 245         struct sk_buff *skb = dev_alloc_skb(1);
 246
 247         if (!skb) {
 248                 printk(KERN_ERR "lapbeth: out of memory\n");
 249                 return;
 250         }
 251
 252         ptr  = skb_put(skb, 1);
 253         *ptr = 0x02;
 254
 255         skb->protocol = x25_type_trans(skb, dev);
 256         skb->dev->last_rx = jiffies;
 257         netif_rx(skb);
 258 }
 259
 260 /*
 261  *      Statistics
 262  */
 263 static struct net_device_stats *lapbeth_get_stats(struct net_device *dev)
 264 {
 265         struct lapbethdev *lapbeth = netdev_priv(dev);
 266         return &lapbeth->stats;
 267 }
 268
 269 /*
 270  *      Set AX.25 callsign
 271  */
 272 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 273 {
 274         struct sockaddr *sa = addr;
 275         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 276         return 0;
 277 }
 278
 279
 280 static struct lapb_register_struct lapbeth_callbacks = {
 281         .connect_confirmation    = lapbeth_connected,
 282         .connect_indication      = lapbeth_connected,
 283         .disconnect_confirmation = lapbeth_disconnected,
 284         .disconnect_indication   = lapbeth_disconnected,
 285         .data_indication         = lapbeth_data_indication,
 286         .data_transmit           = lapbeth_data_transmit,
 287
 288 };
 289
 290 /*
 291  * open/close a device
 292  */
 293 static int lapbeth_open(struct net_device *dev)
 294 {
 295         int err;
 296
 297         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 298                 printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
 299                 return -ENODEV;
 300         }
 301
 302         netif_start_queue(dev);
 303         return 0;
 304 }
 305
 306 static int lapbeth_close(struct net_device *dev)
 307 {
 308         int err;
 309
 310         netif_stop_queue(dev);
 311
 312         if ((err = lapb_unregister(dev)) != LAPB_OK)
 313                 printk(KERN_ERR "lapbeth: lapb_unregister error - %d\n", err);
 314
 315         return 0;
 316 }
 317
 318 /* ------------------------------------------------------------------------ */
 319
 320 static void lapbeth_setup(struct net_device *dev)
 321 {
 322         dev->hard_start_xmit = lapbeth_xmit;
 323         dev->open            = lapbeth_open;
 324         dev->stop            = lapbeth_close;
 325         dev->destructor      = free_netdev;
 326         dev->set_mac_address = lapbeth_set_mac_address;
 327         dev->get_stats       = lapbeth_get_stats;
 328         dev->type            = ARPHRD_X25;
 329         dev->hard_header_len = 3;
 330         dev->mtu             = 1000;
 331         dev->addr_len        = 0;
 332 }
 333
 334 /*
 335  *      Setup a new device.
 336  */
 337 static int lapbeth_new_device(struct net_device *dev)
 338 {
 339         struct net_device *ndev;
 340         struct lapbethdev *lapbeth;
 341         int rc = -ENOMEM;
 342
 343         ASSERT_RTNL();
 344
 345         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 346                            lapbeth_setup);
 347         if (!ndev)
 348                 goto out;
 349
 350         lapbeth = netdev_priv(ndev);
 351         lapbeth->axdev = ndev;
 352
 353         dev_hold(dev);
 354         lapbeth->ethdev = dev;
 355
 356         rc = dev_alloc_name(ndev, ndev->name);
 357         if (rc < 0)
 358                 goto fail;
 359
 360         rc = -EIO;
 361         if (register_netdevice(ndev))
 362                 goto fail;
 363
 364         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 365         rc = 0;
 366 out:
 367         return rc;
 368 fail:
 369         dev_put(dev);
 370         free_netdev(ndev);
 371         kfree(lapbeth);
 372         goto out;
 373 }
 374
 375 /*
 376  *      Free a lapb network device.
 377  */
 378 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 379 {
 380         dev_put(lapbeth->ethdev);
 381         list_del_rcu(&lapbeth->node);
 382         unregister_netdevice(lapbeth->axdev);
 383 }
 384
 385 /*
 386  *      Handle device status changes.
 387  *
 388  * Called from notifier with RTNL held.
 389  */
 390 static int lapbeth_device_event(struct notifier_block *this,
 391                                 unsigned long event, void *ptr)
 392 {
 393         struct lapbethdev *lapbeth;
 394         struct net_device *dev = ptr;
 395
 396         if (dev_net(dev) != &init_net)
 397                 return NOTIFY_DONE;
 398
 399         if (!dev_is_ethdev(dev))
 400                 return NOTIFY_DONE;
 401
 402         switch (event) {
 403         case NETDEV_UP:
 404                 /* New ethernet device -> new LAPB interface     */
 405                 if (lapbeth_get_x25_dev(dev) == NULL)
 406                         lapbeth_new_device(dev);
 407                 break;
 408         case NETDEV_DOWN:
 409                 /* ethernet device closed -> close LAPB interface */
 410                 lapbeth = lapbeth_get_x25_dev(dev);
 411                 if (lapbeth)
 412                         dev_close(lapbeth->axdev);
 413                 break;
 414         case NETDEV_UNREGISTER:
 415                 /* ethernet device disappears -> remove LAPB interface */
 416                 lapbeth = lapbeth_get_x25_dev(dev);
 417                 if (lapbeth)
 418                         lapbeth_free_device(lapbeth);
 419                 break;
 420         }
 421
 422         return NOTIFY_DONE;
 423 }
 424
 425 /* ------------------------------------------------------------------------ */
 426
 427 static struct packet_type lapbeth_packet_type = {
 428         .type = __constant_htons(ETH_P_DEC),
 429         .func = lapbeth_rcv,
 430 };
 431
 432 static struct notifier_block lapbeth_dev_notifier = {
 433         .notifier_call = lapbeth_device_event,
 434 };
 435
 436 static char banner[] __initdata = KERN_INFO "LAPB Ethernet driver version 0.02\n";
 437
 438 static int __init lapbeth_init_driver(void)
 439 {
 440         dev_add_pack(&lapbeth_packet_type);
 441
 442         register_netdevice_notifier(&lapbeth_dev_notifier);
 443
 444         printk(banner);
 445
 446         return 0;
 447 }
 448 module_init(lapbeth_init_driver);
 449
 450 static void __exit lapbeth_cleanup_driver(void)
 451 {
 452         struct lapbethdev *lapbeth;
 453         struct list_head *entry, *tmp;
 454
 455         dev_remove_pack(&lapbeth_packet_type);
 456         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 457
 458         rtnl_lock();
 459         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 460                 lapbeth = list_entry(entry, struct lapbethdev, node);
 461
 462                 dev_put(lapbeth->ethdev);
 463                 unregister_netdevice(lapbeth->axdev);
 464         }
 465         rtnl_unlock();
 466 }
 467 module_exit(lapbeth_cleanup_driver);
 468
 469 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 470 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 471 MODULE_LICENSE("GPL");