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 = -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         ndev->stats.tx_packets++;
 212         ndev->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         netif_rx(skb);
 236 }
 237
 238 static void lapbeth_disconnected(struct net_device *dev, int reason)
 239 {
 240         unsigned char *ptr;
 241         struct sk_buff *skb = dev_alloc_skb(1);
 242
 243         if (!skb) {
 244                 printk(KERN_ERR "lapbeth: out of memory\n");
 245                 return;
 246         }
 247
 248         ptr  = skb_put(skb, 1);
 249         *ptr = 0x02;
 250
 251         skb->protocol = x25_type_trans(skb, dev);
 252         netif_rx(skb);
 253 }
 254
 255 /*
 256  *      Set AX.25 callsign
 257  */
 258 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 259 {
 260         struct sockaddr *sa = addr;
 261         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 262         return 0;
 263 }
 264
 265
 266 static struct lapb_register_struct lapbeth_callbacks = {
 267         .connect_confirmation    = lapbeth_connected,
 268         .connect_indication      = lapbeth_connected,
 269         .disconnect_confirmation = lapbeth_disconnected,
 270         .disconnect_indication   = lapbeth_disconnected,
 271         .data_indication         = lapbeth_data_indication,
 272         .data_transmit           = lapbeth_data_transmit,
 273
 274 };
 275
 276 /*
 277  * open/close a device
 278  */
 279 static int lapbeth_open(struct net_device *dev)
 280 {
 281         int err;
 282
 283         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 284                 printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
 285                 return -ENODEV;
 286         }
 287
 288         netif_start_queue(dev);
 289         return 0;
 290 }
 291
 292 static int lapbeth_close(struct net_device *dev)
 293 {
 294         int err;
 295
 296         netif_stop_queue(dev);
 297
 298         if ((err = lapb_unregister(dev)) != LAPB_OK)
 299                 printk(KERN_ERR "lapbeth: lapb_unregister error - %d\n", err);
 300
 301         return 0;
 302 }
 303
 304 /* ------------------------------------------------------------------------ */
 305
 306 static void lapbeth_setup(struct net_device *dev)
 307 {
 308         dev->hard_start_xmit = lapbeth_xmit;
 309         dev->open            = lapbeth_open;
 310         dev->stop            = lapbeth_close;
 311         dev->destructor      = free_netdev;
 312         dev->set_mac_address = lapbeth_set_mac_address;
 313         dev->type            = ARPHRD_X25;
 314         dev->hard_header_len = 3;
 315         dev->mtu             = 1000;
 316         dev->addr_len        = 0;
 317 }
 318
 319 /*
 320  *      Setup a new device.
 321  */
 322 static int lapbeth_new_device(struct net_device *dev)
 323 {
 324         struct net_device *ndev;
 325         struct lapbethdev *lapbeth;
 326         int rc = -ENOMEM;
 327
 328         ASSERT_RTNL();
 329
 330         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 331                            lapbeth_setup);
 332         if (!ndev)
 333                 goto out;
 334
 335         lapbeth = netdev_priv(ndev);
 336         lapbeth->axdev = ndev;
 337
 338         dev_hold(dev);
 339         lapbeth->ethdev = dev;
 340
 341         rc = dev_alloc_name(ndev, ndev->name);
 342         if (rc < 0)
 343                 goto fail;
 344
 345         rc = -EIO;
 346         if (register_netdevice(ndev))
 347                 goto fail;
 348
 349         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 350         rc = 0;
 351 out:
 352         return rc;
 353 fail:
 354         dev_put(dev);
 355         free_netdev(ndev);
 356         kfree(lapbeth);
 357         goto out;
 358 }
 359
 360 /*
 361  *      Free a lapb network device.
 362  */
 363 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 364 {
 365         dev_put(lapbeth->ethdev);
 366         list_del_rcu(&lapbeth->node);
 367         unregister_netdevice(lapbeth->axdev);
 368 }
 369
 370 /*
 371  *      Handle device status changes.
 372  *
 373  * Called from notifier with RTNL held.
 374  */
 375 static int lapbeth_device_event(struct notifier_block *this,
 376                                 unsigned long event, void *ptr)
 377 {
 378         struct lapbethdev *lapbeth;
 379         struct net_device *dev = ptr;
 380
 381         if (dev_net(dev) != &init_net)
 382                 return NOTIFY_DONE;
 383
 384         if (!dev_is_ethdev(dev))
 385                 return NOTIFY_DONE;
 386
 387         switch (event) {
 388         case NETDEV_UP:
 389                 /* New ethernet device -> new LAPB interface     */
 390                 if (lapbeth_get_x25_dev(dev) == NULL)
 391                         lapbeth_new_device(dev);
 392                 break;
 393         case NETDEV_DOWN:
 394                 /* ethernet device closed -> close LAPB interface */
 395                 lapbeth = lapbeth_get_x25_dev(dev);
 396                 if (lapbeth)
 397                         dev_close(lapbeth->axdev);
 398                 break;
 399         case NETDEV_UNREGISTER:
 400                 /* ethernet device disappears -> remove LAPB interface */
 401                 lapbeth = lapbeth_get_x25_dev(dev);
 402                 if (lapbeth)
 403                         lapbeth_free_device(lapbeth);
 404                 break;
 405         }
 406
 407         return NOTIFY_DONE;
 408 }
 409
 410 /* ------------------------------------------------------------------------ */
 411
 412 static struct packet_type lapbeth_packet_type __read_mostly = {
 413         .type = cpu_to_be16(ETH_P_DEC),
 414         .func = lapbeth_rcv,
 415 };
 416
 417 static struct notifier_block lapbeth_dev_notifier = {
 418         .notifier_call = lapbeth_device_event,
 419 };
 420
 421 static const char banner[] __initconst =
 422         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 423
 424 static int __init lapbeth_init_driver(void)
 425 {
 426         dev_add_pack(&lapbeth_packet_type);
 427
 428         register_netdevice_notifier(&lapbeth_dev_notifier);
 429
 430         printk(banner);
 431
 432         return 0;
 433 }
 434 module_init(lapbeth_init_driver);
 435
 436 static void __exit lapbeth_cleanup_driver(void)
 437 {
 438         struct lapbethdev *lapbeth;
 439         struct list_head *entry, *tmp;
 440
 441         dev_remove_pack(&lapbeth_packet_type);
 442         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 443
 444         rtnl_lock();
 445         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 446                 lapbeth = list_entry(entry, struct lapbethdev, node);
 447
 448                 dev_put(lapbeth->ethdev);
 449                 unregister_netdevice(lapbeth->axdev);
 450         }
 451         rtnl_unlock();
 452 }
 453 module_exit(lapbeth_cleanup_driver);
 454
 455 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 456 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 457 MODULE_LICENSE("GPL");