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 };
  59
  60 static LIST_HEAD(lapbeth_devices);
  61
  62 /* ------------------------------------------------------------------------ */
  63
  64 /*
  65  *      Get the LAPB device for the ethernet device
  66  */
  67 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  68 {
  69         struct lapbethdev *lapbeth;
  70
  71         list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  72                 if (lapbeth->ethdev == dev)
  73                         return lapbeth;
  74         }
  75         return NULL;
  76 }
  77
  78 static __inline__ int dev_is_ethdev(struct net_device *dev)
  79 {
  80         return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  81 }
  82
  83 /* ------------------------------------------------------------------------ */
  84
  85 /*
  86  *      Receive a LAPB frame via an ethernet interface.
  87  */
  88 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  89 {
  90         int len, err;
  91         struct lapbethdev *lapbeth;
  92
  93         if (dev_net(dev) != &init_net)
  94                 goto drop;
  95
  96         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  97                 return NET_RX_DROP;
  98
  99         if (!pskb_may_pull(skb, 2))
 100                 goto drop;
 101
 102         rcu_read_lock();
 103         lapbeth = lapbeth_get_x25_dev(dev);
 104         if (!lapbeth)
 105                 goto drop_unlock;
 106         if (!netif_running(lapbeth->axdev))
 107                 goto drop_unlock;
 108
 109         len = skb->data[0] + skb->data[1] * 256;
 110         dev->stats.rx_packets++;
 111         dev->stats.rx_bytes += len;
 112
 113         skb_pull(skb, 2);       /* Remove the length bytes */
 114         skb_trim(skb, len);     /* Set the length of the data */
 115
 116         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 117                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 118                 goto drop_unlock;
 119         }
 120 out:
 121         rcu_read_unlock();
 122         return 0;
 123 drop_unlock:
 124         kfree_skb(skb);
 125         goto out;
 126 drop:
 127         kfree_skb(skb);
 128         return 0;
 129 }
 130
 131 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 132 {
 133         unsigned char *ptr;
 134
 135         skb_push(skb, 1);
 136
 137         if (skb_cow(skb, 1))
 138                 return NET_RX_DROP;
 139
 140         ptr  = skb->data;
 141         *ptr = 0x00;
 142
 143         skb->protocol = x25_type_trans(skb, dev);
 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;
 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         switch (skb->data[0]) {
 162         case 0x00:
 163                 break;
 164         case 0x01:
 165                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 166                         printk(KERN_ERR "lapbeth: lapb_connect_request "
 167                                "error: %d\n", err);
 168                 goto drop;
 169         case 0x02:
 170                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 171                         printk(KERN_ERR "lapbeth: lapb_disconnect_request "
 172                                "err: %d\n", err);
 173                 /* Fall thru */
 174         default:
 175                 goto drop;
 176         }
 177
 178         skb_pull(skb, 1);
 179
 180         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 181                 printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
 182                 goto drop;
 183         }
 184 out:
 185         return NETDEV_TX_OK;
 186 drop:
 187         kfree_skb(skb);
 188         goto out;
 189 }
 190
 191 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 192 {
 193         struct lapbethdev *lapbeth = netdev_priv(ndev);
 194         unsigned char *ptr;
 195         struct net_device *dev;
 196         int size = skb->len;
 197
 198         skb->protocol = htons(ETH_P_X25);
 199
 200         ptr = skb_push(skb, 2);
 201
 202         *ptr++ = size % 256;
 203         *ptr++ = size / 256;
 204
 205         ndev->stats.tx_packets++;
 206         ndev->stats.tx_bytes += size;
 207
 208         skb->dev = dev = lapbeth->ethdev;
 209
 210         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 211
 212         dev_queue_xmit(skb);
 213 }
 214
 215 static void lapbeth_connected(struct net_device *dev, int reason)
 216 {
 217         unsigned char *ptr;
 218         struct sk_buff *skb = dev_alloc_skb(1);
 219
 220         if (!skb) {
 221                 printk(KERN_ERR "lapbeth: out of memory\n");
 222                 return;
 223         }
 224
 225         ptr  = skb_put(skb, 1);
 226         *ptr = 0x01;
 227
 228         skb->protocol = x25_type_trans(skb, dev);
 229         netif_rx(skb);
 230 }
 231
 232 static void lapbeth_disconnected(struct net_device *dev, int reason)
 233 {
 234         unsigned char *ptr;
 235         struct sk_buff *skb = dev_alloc_skb(1);
 236
 237         if (!skb) {
 238                 printk(KERN_ERR "lapbeth: out of memory\n");
 239                 return;
 240         }
 241
 242         ptr  = skb_put(skb, 1);
 243         *ptr = 0x02;
 244
 245         skb->protocol = x25_type_trans(skb, dev);
 246         netif_rx(skb);
 247 }
 248
 249 /*
 250  *      Set AX.25 callsign
 251  */
 252 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 253 {
 254         struct sockaddr *sa = addr;
 255         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 256         return 0;
 257 }
 258
 259
 260 static struct lapb_register_struct lapbeth_callbacks = {
 261         .connect_confirmation    = lapbeth_connected,
 262         .connect_indication      = lapbeth_connected,
 263         .disconnect_confirmation = lapbeth_disconnected,
 264         .disconnect_indication   = lapbeth_disconnected,
 265         .data_indication         = lapbeth_data_indication,
 266         .data_transmit           = lapbeth_data_transmit,
 267
 268 };
 269
 270 /*
 271  * open/close a device
 272  */
 273 static int lapbeth_open(struct net_device *dev)
 274 {
 275         int err;
 276
 277         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 278                 printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
 279                 return -ENODEV;
 280         }
 281
 282         netif_start_queue(dev);
 283         return 0;
 284 }
 285
 286 static int lapbeth_close(struct net_device *dev)
 287 {
 288         int err;
 289
 290         netif_stop_queue(dev);
 291
 292         if ((err = lapb_unregister(dev)) != LAPB_OK)
 293                 printk(KERN_ERR "lapbeth: lapb_unregister error - %d\n", err);
 294
 295         return 0;
 296 }
 297
 298 /* ------------------------------------------------------------------------ */
 299
 300 static const struct net_device_ops lapbeth_netdev_ops = {
 301         .ndo_open            = lapbeth_open,
 302         .ndo_stop            = lapbeth_close,
 303         .ndo_start_xmit      = lapbeth_xmit,
 304         .ndo_set_mac_address = lapbeth_set_mac_address,
 305 };
 306
 307 static void lapbeth_setup(struct net_device *dev)
 308 {
 309         dev->netdev_ops      = &lapbeth_netdev_ops;
 310         dev->destructor      = free_netdev;
 311         dev->type            = ARPHRD_X25;
 312         dev->hard_header_len = 3;
 313         dev->mtu             = 1000;
 314         dev->addr_len        = 0;
 315 }
 316
 317 /*
 318  *      Setup a new device.
 319  */
 320 static int lapbeth_new_device(struct net_device *dev)
 321 {
 322         struct net_device *ndev;
 323         struct lapbethdev *lapbeth;
 324         int rc = -ENOMEM;
 325
 326         ASSERT_RTNL();
 327
 328         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 329                            lapbeth_setup);
 330         if (!ndev)
 331                 goto out;
 332
 333         lapbeth = netdev_priv(ndev);
 334         lapbeth->axdev = ndev;
 335
 336         dev_hold(dev);
 337         lapbeth->ethdev = dev;
 338
 339         rc = dev_alloc_name(ndev, ndev->name);
 340         if (rc < 0)
 341                 goto fail;
 342
 343         rc = -EIO;
 344         if (register_netdevice(ndev))
 345                 goto fail;
 346
 347         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 348         rc = 0;
 349 out:
 350         return rc;
 351 fail:
 352         dev_put(dev);
 353         free_netdev(ndev);
 354         kfree(lapbeth);
 355         goto out;
 356 }
 357
 358 /*
 359  *      Free a lapb network device.
 360  */
 361 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 362 {
 363         dev_put(lapbeth->ethdev);
 364         list_del_rcu(&lapbeth->node);
 365         unregister_netdevice(lapbeth->axdev);
 366 }
 367
 368 /*
 369  *      Handle device status changes.
 370  *
 371  * Called from notifier with RTNL held.
 372  */
 373 static int lapbeth_device_event(struct notifier_block *this,
 374                                 unsigned long event, void *ptr)
 375 {
 376         struct lapbethdev *lapbeth;
 377         struct net_device *dev = ptr;
 378
 379         if (dev_net(dev) != &init_net)
 380                 return NOTIFY_DONE;
 381
 382         if (!dev_is_ethdev(dev))
 383                 return NOTIFY_DONE;
 384
 385         switch (event) {
 386         case NETDEV_UP:
 387                 /* New ethernet device -> new LAPB interface     */
 388                 if (lapbeth_get_x25_dev(dev) == NULL)
 389                         lapbeth_new_device(dev);
 390                 break;
 391         case NETDEV_DOWN:
 392                 /* ethernet device closed -> close LAPB interface */
 393                 lapbeth = lapbeth_get_x25_dev(dev);
 394                 if (lapbeth)
 395                         dev_close(lapbeth->axdev);
 396                 break;
 397         case NETDEV_UNREGISTER:
 398                 /* ethernet device disappears -> remove LAPB interface */
 399                 lapbeth = lapbeth_get_x25_dev(dev);
 400                 if (lapbeth)
 401                         lapbeth_free_device(lapbeth);
 402                 break;
 403         }
 404
 405         return NOTIFY_DONE;
 406 }
 407
 408 /* ------------------------------------------------------------------------ */
 409
 410 static struct packet_type lapbeth_packet_type __read_mostly = {
 411         .type = cpu_to_be16(ETH_P_DEC),
 412         .func = lapbeth_rcv,
 413 };
 414
 415 static struct notifier_block lapbeth_dev_notifier = {
 416         .notifier_call = lapbeth_device_event,
 417 };
 418
 419 static const char banner[] __initconst =
 420         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 421
 422 static int __init lapbeth_init_driver(void)
 423 {
 424         dev_add_pack(&lapbeth_packet_type);
 425
 426         register_netdevice_notifier(&lapbeth_dev_notifier);
 427
 428         printk(banner);
 429
 430         return 0;
 431 }
 432 module_init(lapbeth_init_driver);
 433
 434 static void __exit lapbeth_cleanup_driver(void)
 435 {
 436         struct lapbethdev *lapbeth;
 437         struct list_head *entry, *tmp;
 438
 439         dev_remove_pack(&lapbeth_packet_type);
 440         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 441
 442         rtnl_lock();
 443         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 444                 lapbeth = list_entry(entry, struct lapbethdev, node);
 445
 446                 dev_put(lapbeth->ethdev);
 447                 unregister_netdevice(lapbeth->axdev);
 448         }
 449         rtnl_unlock();
 450 }
 451 module_exit(lapbeth_cleanup_driver);
 452
 453 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 454 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 455 MODULE_LICENSE("GPL");