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