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 struct list_head lapbeth_devices = LIST_HEAD_INIT(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)
  90 {
  91         int len, err;
  92         struct lapbethdev *lapbeth;
  93
  94         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  95                 return NET_RX_DROP;
  96
  97         if (!pskb_may_pull(skb, 2))
  98                 goto drop;
  99
 100         rcu_read_lock();
 101         lapbeth = lapbeth_get_x25_dev(dev);
 102         if (!lapbeth)
 103                 goto drop_unlock;
 104         if (!netif_running(lapbeth->axdev))
 105                 goto drop_unlock;
 106
 107         lapbeth->stats.rx_packets++;
 108
 109         len = skb->data[0] + skb->data[1] * 256;
 110         lapbeth->stats.rx_bytes += len;
 111
 112         skb_pull(skb, 2);       /* Remove the length bytes */
 113         skb_trim(skb, len);     /* Set the length of the data */
 114
 115         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 116                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 117                 goto drop_unlock;
 118         }
 119 out:
 120         rcu_read_unlock();
 121         return 0;
 122 drop_unlock:
 123         kfree_skb(skb);
 124         goto out;
 125 drop:
 126         kfree_skb(skb);
 127         return 0;
 128 }
 129
 130 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 131 {
 132         unsigned char *ptr;
 133
 134         skb_push(skb, 1);
 135
 136         if (skb_cow(skb, 1))
 137                 return NET_RX_DROP;
 138
 139         ptr  = skb->data;
 140         *ptr = 0x00;
 141
 142         skb->protocol = x25_type_trans(skb, dev);
 143         skb->dev->last_rx = jiffies;
 144         return netif_rx(skb);
 145 }
 146
 147 /*
 148  *      Send a LAPB frame via an ethernet interface
 149  */
 150 static int lapbeth_xmit(struct sk_buff *skb, struct net_device *dev)
 151 {
 152         int err = -ENODEV;
 153
 154         /*
 155          * Just to be *really* sure not to send anything if the interface
 156          * is down, the ethernet device may have gone.
 157          */
 158         if (!netif_running(dev)) {
 159                 goto drop;
 160         }
 161
 162         switch (skb->data[0]) {
 163         case 0x00:
 164                 err = 0;
 165                 break;
 166         case 0x01:
 167                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 168                         printk(KERN_ERR "lapbeth: lapb_connect_request "
 169                                "error: %d\n", err);
 170                 goto drop_ok;
 171         case 0x02:
 172                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 173                         printk(KERN_ERR "lapbeth: lapb_disconnect_request "
 174                                "err: %d\n", err);
 175                 /* Fall thru */
 176         default:
 177                 goto drop_ok;
 178         }
 179
 180         skb_pull(skb, 1);
 181
 182         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 183                 printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
 184                 err = -ENOMEM;
 185                 goto drop;
 186         }
 187         err = 0;
 188 out:
 189         return err;
 190 drop_ok:
 191         err = 0;
 192 drop:
 193         kfree_skb(skb);
 194         goto out;
 195 }
 196
 197 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 198 {
 199         struct lapbethdev *lapbeth = netdev_priv(ndev);
 200         unsigned char *ptr;
 201         struct net_device *dev;
 202         int size = skb->len;
 203
 204         skb->protocol = htons(ETH_P_X25);
 205
 206         ptr = skb_push(skb, 2);
 207
 208         *ptr++ = size % 256;
 209         *ptr++ = size / 256;
 210
 211         lapbeth->stats.tx_packets++;
 212         lapbeth->stats.tx_bytes += size;
 213
 214         skb->dev = dev = lapbeth->ethdev;
 215
 216         dev->hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 217
 218         dev_queue_xmit(skb);
 219 }
 220
 221 static void lapbeth_connected(struct net_device *dev, int reason)
 222 {
 223         unsigned char *ptr;
 224         struct sk_buff *skb = dev_alloc_skb(1);
 225
 226         if (!skb) {
 227                 printk(KERN_ERR "lapbeth: out of memory\n");
 228                 return;
 229         }
 230
 231         ptr  = skb_put(skb, 1);
 232         *ptr = 0x01;
 233
 234         skb->protocol = x25_type_trans(skb, dev);
 235         skb->dev->last_rx = jiffies;
 236         netif_rx(skb);
 237 }
 238
 239 static void lapbeth_disconnected(struct net_device *dev, int reason)
 240 {
 241         unsigned char *ptr;
 242         struct sk_buff *skb = dev_alloc_skb(1);
 243
 244         if (!skb) {
 245                 printk(KERN_ERR "lapbeth: out of memory\n");
 246                 return;
 247         }
 248
 249         ptr  = skb_put(skb, 1);
 250         *ptr = 0x02;
 251
 252         skb->protocol = x25_type_trans(skb, dev);
 253         skb->dev->last_rx = jiffies;
 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         SET_MODULE_OWNER(dev);
 330 }
 331
 332 /*
 333  *      Setup a new device.
 334  */
 335 static int lapbeth_new_device(struct net_device *dev)
 336 {
 337         struct net_device *ndev;
 338         struct lapbethdev *lapbeth;
 339         int rc = -ENOMEM;
 340
 341         ASSERT_RTNL();
 342
 343         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 344                            lapbeth_setup);
 345         if (!ndev)
 346                 goto out;
 347
 348         lapbeth = netdev_priv(ndev);
 349         lapbeth->axdev = ndev;
 350
 351         dev_hold(dev);
 352         lapbeth->ethdev = dev;
 353
 354         rc = dev_alloc_name(ndev, ndev->name);
 355         if (rc < 0)
 356                 goto fail;
 357
 358         rc = -EIO;
 359         if (register_netdevice(ndev))
 360                 goto fail;
 361
 362         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 363         rc = 0;
 364 out:
 365         return rc;
 366 fail:
 367         dev_put(dev);
 368         free_netdev(ndev);
 369         kfree(lapbeth);
 370         goto out;
 371 }
 372
 373 /*
 374  *      Free a lapb network device.
 375  */
 376 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 377 {
 378         dev_put(lapbeth->ethdev);
 379         list_del_rcu(&lapbeth->node);
 380         unregister_netdevice(lapbeth->axdev);
 381 }
 382
 383 /*
 384  *      Handle device status changes.
 385  *
 386  * Called from notifier with RTNL held.
 387  */
 388 static int lapbeth_device_event(struct notifier_block *this,
 389                                 unsigned long event, void *ptr)
 390 {
 391         struct lapbethdev *lapbeth;
 392         struct net_device *dev = ptr;
 393
 394         if (!dev_is_ethdev(dev))
 395                 return NOTIFY_DONE;
 396
 397         switch (event) {
 398         case NETDEV_UP:
 399                 /* New ethernet device -> new LAPB interface     */
 400                 if (lapbeth_get_x25_dev(dev) == NULL)
 401                         lapbeth_new_device(dev);
 402                 break;
 403         case NETDEV_DOWN:
 404                 /* ethernet device closed -> close LAPB interface */
 405                 lapbeth = lapbeth_get_x25_dev(dev);
 406                 if (lapbeth)
 407                         dev_close(lapbeth->axdev);
 408                 break;
 409         case NETDEV_UNREGISTER:
 410                 /* ethernet device disappears -> remove LAPB interface */
 411                 lapbeth = lapbeth_get_x25_dev(dev);
 412                 if (lapbeth)
 413                         lapbeth_free_device(lapbeth);
 414                 break;
 415         }
 416
 417         return NOTIFY_DONE;
 418 }
 419
 420 /* ------------------------------------------------------------------------ */
 421
 422 static struct packet_type lapbeth_packet_type = {
 423         .type = __constant_htons(ETH_P_DEC),
 424         .func = lapbeth_rcv,
 425 };
 426
 427 static struct notifier_block lapbeth_dev_notifier = {
 428         .notifier_call = lapbeth_device_event,
 429 };
 430
 431 static char banner[] __initdata = KERN_INFO "LAPB Ethernet driver version 0.02\n";
 432
 433 static int __init lapbeth_init_driver(void)
 434 {
 435         dev_add_pack(&lapbeth_packet_type);
 436
 437         register_netdevice_notifier(&lapbeth_dev_notifier);
 438
 439         printk(banner);
 440
 441         return 0;
 442 }
 443 module_init(lapbeth_init_driver);
 444
 445 static void __exit lapbeth_cleanup_driver(void)
 446 {
 447         struct lapbethdev *lapbeth;
 448         struct list_head *entry, *tmp;
 449
 450         dev_remove_pack(&lapbeth_packet_type);
 451         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 452
 453         rtnl_lock();
 454         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 455                 lapbeth = list_entry(entry, struct lapbethdev, node);
 456
 457                 unregister_netdevice(lapbeth->axdev);
 458         }
 459         rtnl_unlock();
 460 }
 461 module_exit(lapbeth_cleanup_driver);
 462
 463 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 464 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 465 MODULE_LICENSE("GPL");