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         return netif_rx(skb);
 147 }
 148
 149 /*
 150  *      Send a LAPB frame via an ethernet interface
 151  */
 152 static int lapbeth_xmit(struct sk_buff *skb, struct net_device *dev)
 153 {
 154         int err = -ENODEV;
 155
 156         /*
 157          * Just to be *really* sure not to send anything if the interface
 158          * is down, the ethernet device may have gone.
 159          */
 160         if (!netif_running(dev)) {
 161                 goto drop;
 162         }
 163
 164         switch (skb->data[0]) {
 165         case 0x00:
 166                 err = 0;
 167                 break;
 168         case 0x01:
 169                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 170                         printk(KERN_ERR "lapbeth: lapb_connect_request "
 171                                "error: %d\n", err);
 172                 goto drop_ok;
 173         case 0x02:
 174                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 175                         printk(KERN_ERR "lapbeth: lapb_disconnect_request "
 176                                "err: %d\n", err);
 177                 /* Fall thru */
 178         default:
 179                 goto drop_ok;
 180         }
 181
 182         skb_pull(skb, 1);
 183
 184         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 185                 printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
 186                 err = -ENOMEM;
 187                 goto drop;
 188         }
 189         err = 0;
 190 out:
 191         return err;
 192 drop_ok:
 193         err = 0;
 194 drop:
 195         kfree_skb(skb);
 196         goto out;
 197 }
 198
 199 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 200 {
 201         struct lapbethdev *lapbeth = netdev_priv(ndev);
 202         unsigned char *ptr;
 203         struct net_device *dev;
 204         int size = skb->len;
 205
 206         skb->protocol = htons(ETH_P_X25);
 207
 208         ptr = skb_push(skb, 2);
 209
 210         *ptr++ = size % 256;
 211         *ptr++ = size / 256;
 212
 213         lapbeth->stats.tx_packets++;
 214         lapbeth->stats.tx_bytes += size;
 215
 216         skb->dev = dev = lapbeth->ethdev;
 217
 218         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 219
 220         dev_queue_xmit(skb);
 221 }
 222
 223 static void lapbeth_connected(struct net_device *dev, int reason)
 224 {
 225         unsigned char *ptr;
 226         struct sk_buff *skb = dev_alloc_skb(1);
 227
 228         if (!skb) {
 229                 printk(KERN_ERR "lapbeth: out of memory\n");
 230                 return;
 231         }
 232
 233         ptr  = skb_put(skb, 1);
 234         *ptr = 0x01;
 235
 236         skb->protocol = x25_type_trans(skb, dev);
 237         netif_rx(skb);
 238 }
 239
 240 static void lapbeth_disconnected(struct net_device *dev, int reason)
 241 {
 242         unsigned char *ptr;
 243         struct sk_buff *skb = dev_alloc_skb(1);
 244
 245         if (!skb) {
 246                 printk(KERN_ERR "lapbeth: out of memory\n");
 247                 return;
 248         }
 249
 250         ptr  = skb_put(skb, 1);
 251         *ptr = 0x02;
 252
 253         skb->protocol = x25_type_trans(skb, dev);
 254         netif_rx(skb);
 255 }
 256
 257 /*
 258  *      Statistics
 259  */
 260 static struct net_device_stats *lapbeth_get_stats(struct net_device *dev)
 261 {
 262         struct lapbethdev *lapbeth = netdev_priv(dev);
 263         return &lapbeth->stats;
 264 }
 265
 266 /*
 267  *      Set AX.25 callsign
 268  */
 269 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 270 {
 271         struct sockaddr *sa = addr;
 272         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 273         return 0;
 274 }
 275
 276
 277 static struct lapb_register_struct lapbeth_callbacks = {
 278         .connect_confirmation    = lapbeth_connected,
 279         .connect_indication      = lapbeth_connected,
 280         .disconnect_confirmation = lapbeth_disconnected,
 281         .disconnect_indication   = lapbeth_disconnected,
 282         .data_indication         = lapbeth_data_indication,
 283         .data_transmit           = lapbeth_data_transmit,
 284
 285 };
 286
 287 /*
 288  * open/close a device
 289  */
 290 static int lapbeth_open(struct net_device *dev)
 291 {
 292         int err;
 293
 294         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 295                 printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
 296                 return -ENODEV;
 297         }
 298
 299         netif_start_queue(dev);
 300         return 0;
 301 }
 302
 303 static int lapbeth_close(struct net_device *dev)
 304 {
 305         int err;
 306
 307         netif_stop_queue(dev);
 308
 309         if ((err = lapb_unregister(dev)) != LAPB_OK)
 310                 printk(KERN_ERR "lapbeth: lapb_unregister error - %d\n", err);
 311
 312         return 0;
 313 }
 314
 315 /* ------------------------------------------------------------------------ */
 316
 317 static void lapbeth_setup(struct net_device *dev)
 318 {
 319         dev->hard_start_xmit = lapbeth_xmit;
 320         dev->open            = lapbeth_open;
 321         dev->stop            = lapbeth_close;
 322         dev->destructor      = free_netdev;
 323         dev->set_mac_address = lapbeth_set_mac_address;
 324         dev->get_stats       = lapbeth_get_stats;
 325         dev->type            = ARPHRD_X25;
 326         dev->hard_header_len = 3;
 327         dev->mtu             = 1000;
 328         dev->addr_len        = 0;
 329 }
 330
 331 /*
 332  *      Setup a new device.
 333  */
 334 static int lapbeth_new_device(struct net_device *dev)
 335 {
 336         struct net_device *ndev;
 337         struct lapbethdev *lapbeth;
 338         int rc = -ENOMEM;
 339
 340         ASSERT_RTNL();
 341
 342         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 343                            lapbeth_setup);
 344         if (!ndev)
 345                 goto out;
 346
 347         lapbeth = netdev_priv(ndev);
 348         lapbeth->axdev = ndev;
 349
 350         dev_hold(dev);
 351         lapbeth->ethdev = dev;
 352
 353         rc = dev_alloc_name(ndev, ndev->name);
 354         if (rc < 0)
 355                 goto fail;
 356
 357         rc = -EIO;
 358         if (register_netdevice(ndev))
 359                 goto fail;
 360
 361         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 362         rc = 0;
 363 out:
 364         return rc;
 365 fail:
 366         dev_put(dev);
 367         free_netdev(ndev);
 368         kfree(lapbeth);
 369         goto out;
 370 }
 371
 372 /*
 373  *      Free a lapb network device.
 374  */
 375 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 376 {
 377         dev_put(lapbeth->ethdev);
 378         list_del_rcu(&lapbeth->node);
 379         unregister_netdevice(lapbeth->axdev);
 380 }
 381
 382 /*
 383  *      Handle device status changes.
 384  *
 385  * Called from notifier with RTNL held.
 386  */
 387 static int lapbeth_device_event(struct notifier_block *this,
 388                                 unsigned long event, void *ptr)
 389 {
 390         struct lapbethdev *lapbeth;
 391         struct net_device *dev = ptr;
 392
 393         if (dev_net(dev) != &init_net)
 394                 return NOTIFY_DONE;
 395
 396         if (!dev_is_ethdev(dev))
 397                 return NOTIFY_DONE;
 398
 399         switch (event) {
 400         case NETDEV_UP:
 401                 /* New ethernet device -> new LAPB interface     */
 402                 if (lapbeth_get_x25_dev(dev) == NULL)
 403                         lapbeth_new_device(dev);
 404                 break;
 405         case NETDEV_DOWN:
 406                 /* ethernet device closed -> close LAPB interface */
 407                 lapbeth = lapbeth_get_x25_dev(dev);
 408                 if (lapbeth)
 409                         dev_close(lapbeth->axdev);
 410                 break;
 411         case NETDEV_UNREGISTER:
 412                 /* ethernet device disappears -> remove LAPB interface */
 413                 lapbeth = lapbeth_get_x25_dev(dev);
 414                 if (lapbeth)
 415                         lapbeth_free_device(lapbeth);
 416                 break;
 417         }
 418
 419         return NOTIFY_DONE;
 420 }
 421
 422 /* ------------------------------------------------------------------------ */
 423
 424 static struct packet_type lapbeth_packet_type __read_mostly = {
 425         .type = cpu_to_be16(ETH_P_DEC),
 426         .func = lapbeth_rcv,
 427 };
 428
 429 static struct notifier_block lapbeth_dev_notifier = {
 430         .notifier_call = lapbeth_device_event,
 431 };
 432
 433 static const char banner[] __initconst =
 434         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 435
 436 static int __init lapbeth_init_driver(void)
 437 {
 438         dev_add_pack(&lapbeth_packet_type);
 439
 440         register_netdevice_notifier(&lapbeth_dev_notifier);
 441
 442         printk(banner);
 443
 444         return 0;
 445 }
 446 module_init(lapbeth_init_driver);
 447
 448 static void __exit lapbeth_cleanup_driver(void)
 449 {
 450         struct lapbethdev *lapbeth;
 451         struct list_head *entry, *tmp;
 452
 453         dev_remove_pack(&lapbeth_packet_type);
 454         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 455
 456         rtnl_lock();
 457         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 458                 lapbeth = list_entry(entry, struct lapbethdev, node);
 459
 460                 dev_put(lapbeth->ethdev);
 461                 unregister_netdevice(lapbeth->axdev);
 462         }
 463         rtnl_unlock();
 464 }
 465 module_exit(lapbeth_cleanup_driver);
 466
 467 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 468 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 469 MODULE_LICENSE("GPL");