LXR linux/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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25#include <linux/errno.h>
  26#include <linux/types.h>
  27#include <linux/socket.h>
  28#include <linux/in.h>
  29#include <linux/slab.h>
  30#include <linux/kernel.h>
  31#include <linux/string.h>
  32#include <linux/net.h>
  33#include <linux/inet.h>
  34#include <linux/netdevice.h>
  35#include <linux/if_arp.h>
  36#include <linux/skbuff.h>
  37#include <net/sock.h>
  38#include <asm/uaccess.h>
  39#include <linux/mm.h>
  40#include <linux/interrupt.h>
  41#include <linux/notifier.h>
  42#include <linux/stat.h>
  43#include <linux/netfilter.h>
  44#include <linux/module.h>
  45#include <linux/lapb.h>
  46#include <linux/init.h>
  47
  48#include <net/x25device.h>
  49
  50static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  51
  52/* If this number is made larger, check that the temporary string buffer
  53 * in lapbeth_new_device is large enough to store the probe device name.*/
  54#define MAXLAPBDEV 100
  55
  56struct lapbethdev {
  57        struct list_head        node;
  58        struct net_device       *ethdev;        /* link to ethernet device */
  59        struct net_device       *axdev;         /* lapbeth device (lapb#) */
  60};
  61
  62static LIST_HEAD(lapbeth_devices);
  63
  64/* ------------------------------------------------------------------------ */
  65
  66/*
  67 *      Get the LAPB device for the ethernet device
  68 */
  69static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  70{
  71        struct lapbethdev *lapbeth;
  72
  73        list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  74                if (lapbeth->ethdev == dev) 
  75                        return lapbeth;
  76        }
  77        return NULL;
  78}
  79
  80static __inline__ int dev_is_ethdev(struct net_device *dev)
  81{
  82        return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  83}
  84
  85/* ------------------------------------------------------------------------ */
  86
  87/*
  88 *      Receive a LAPB frame via an ethernet interface.
  89 */
  90static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  91{
  92        int len, err;
  93        struct lapbethdev *lapbeth;
  94
  95        if (dev_net(dev) != &init_net)
  96                goto drop;
  97
  98        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  99                return NET_RX_DROP;
 100
 101        if (!pskb_may_pull(skb, 2))
 102                goto drop;
 103
 104        rcu_read_lock();
 105        lapbeth = lapbeth_get_x25_dev(dev);
 106        if (!lapbeth)
 107                goto drop_unlock;
 108        if (!netif_running(lapbeth->axdev))
 109                goto drop_unlock;
 110
 111        len = skb->data[0] + skb->data[1] * 256;
 112        dev->stats.rx_packets++;
 113        dev->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        }
 122out:
 123        rcu_read_unlock();
 124        return 0;
 125drop_unlock:
 126        kfree_skb(skb);
 127        goto out;
 128drop:
 129        kfree_skb(skb);
 130        return 0;
 131}
 132
 133static 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 = X25_IFACE_DATA;
 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 */
 152static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 153                                      struct net_device *dev)
 154{
 155        int err;
 156
 157        /*
 158         * Just to be *really* sure not to send anything if the interface
 159         * is down, the ethernet device may have gone.
 160         */
 161        if (!netif_running(dev))
 162                goto drop;
 163
 164        switch (skb->data[0]) {
 165        case X25_IFACE_DATA:
 166                break;
 167        case X25_IFACE_CONNECT:
 168                if ((err = lapb_connect_request(dev)) != LAPB_OK)
 169                        pr_err("lapb_connect_request error: %d\n", err);
 170                goto drop;
 171        case X25_IFACE_DISCONNECT:
 172                if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 173                        pr_err("lapb_disconnect_request 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                pr_err("lapb_data_request error - %d\n", err);
 183                goto drop;
 184        }
 185out:
 186        return NETDEV_TX_OK;
 187drop:
 188        kfree_skb(skb);
 189        goto out;
 190}
 191
 192static 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
 216static 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                pr_err("out of memory\n");
 223                return;
 224        }
 225
 226        ptr  = skb_put(skb, 1);
 227        *ptr = X25_IFACE_CONNECT;
 228
 229        skb->protocol = x25_type_trans(skb, dev);
 230        netif_rx(skb);
 231}
 232
 233static 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                pr_err("out of memory\n");
 240                return;
 241        }
 242
 243        ptr  = skb_put(skb, 1);
 244        *ptr = X25_IFACE_DISCONNECT;
 245
 246        skb->protocol = x25_type_trans(skb, dev);
 247        netif_rx(skb);
 248}
 249
 250/*
 251 *      Set AX.25 callsign
 252 */
 253static 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
 261static const 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 * open/close a device
 272 */
 273static int lapbeth_open(struct net_device *dev)
 274{
 275        int err;
 276
 277        if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 278                pr_err("lapb_register error: %d\n", err);
 279                return -ENODEV;
 280        }
 281
 282        netif_start_queue(dev);
 283        return 0;
 284}
 285
 286static 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                pr_err("lapb_unregister error: %d\n", err);
 294
 295        return 0;
 296}
 297
 298/* ------------------------------------------------------------------------ */
 299
 300static 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
 307static 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 */
 320static 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 = -EIO;
 340        if (register_netdevice(ndev))
 341                goto fail;
 342
 343        list_add_rcu(&lapbeth->node, &lapbeth_devices);
 344        rc = 0;
 345out:
 346        return rc;
 347fail:
 348        dev_put(dev);
 349        free_netdev(ndev);
 350        kfree(lapbeth);
 351        goto out;
 352}
 353
 354/*
 355 *      Free a lapb network device.
 356 */
 357static void lapbeth_free_device(struct lapbethdev *lapbeth)
 358{
 359        dev_put(lapbeth->ethdev);
 360        list_del_rcu(&lapbeth->node);
 361        unregister_netdevice(lapbeth->axdev);
 362}
 363
 364/*
 365 *      Handle device status changes.
 366 *
 367 * Called from notifier with RTNL held.
 368 */
 369static int lapbeth_device_event(struct notifier_block *this,
 370                                unsigned long event, void *ptr)
 371{
 372        struct lapbethdev *lapbeth;
 373        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 374
 375        if (dev_net(dev) != &init_net)
 376                return NOTIFY_DONE;
 377
 378        if (!dev_is_ethdev(dev))
 379                return NOTIFY_DONE;
 380
 381        switch (event) {
 382        case NETDEV_UP:
 383                /* New ethernet device -> new LAPB interface     */
 384                if (lapbeth_get_x25_dev(dev) == NULL)
 385                        lapbeth_new_device(dev);
 386                break;
 387        case NETDEV_DOWN:       
 388                /* ethernet device closed -> close LAPB interface */
 389                lapbeth = lapbeth_get_x25_dev(dev);
 390                if (lapbeth) 
 391                        dev_close(lapbeth->axdev);
 392                break;
 393        case NETDEV_UNREGISTER:
 394                /* ethernet device disappears -> remove LAPB interface */
 395                lapbeth = lapbeth_get_x25_dev(dev);
 396                if (lapbeth)
 397                        lapbeth_free_device(lapbeth);
 398                break;
 399        }
 400
 401        return NOTIFY_DONE;
 402}
 403
 404/* ------------------------------------------------------------------------ */
 405
 406static struct packet_type lapbeth_packet_type __read_mostly = {
 407        .type = cpu_to_be16(ETH_P_DEC),
 408        .func = lapbeth_rcv,
 409};
 410
 411static struct notifier_block lapbeth_dev_notifier = {
 412        .notifier_call = lapbeth_device_event,
 413};
 414
 415static const char banner[] __initconst =
 416        KERN_INFO "LAPB Ethernet driver version 0.02\n";
 417
 418static int __init lapbeth_init_driver(void)
 419{
 420        dev_add_pack(&lapbeth_packet_type);
 421
 422        register_netdevice_notifier(&lapbeth_dev_notifier);
 423
 424        printk(banner);
 425
 426        return 0;
 427}
 428module_init(lapbeth_init_driver);
 429
 430static void __exit lapbeth_cleanup_driver(void)
 431{
 432        struct lapbethdev *lapbeth;
 433        struct list_head *entry, *tmp;
 434
 435        dev_remove_pack(&lapbeth_packet_type);
 436        unregister_netdevice_notifier(&lapbeth_dev_notifier);
 437
 438        rtnl_lock();
 439        list_for_each_safe(entry, tmp, &lapbeth_devices) {
 440                lapbeth = list_entry(entry, struct lapbethdev, node);
 441
 442                dev_put(lapbeth->ethdev);
 443                unregister_netdevice(lapbeth->axdev);
 444        }
 445        rtnl_unlock();
 446}
 447module_exit(lapbeth_cleanup_driver);
 448
 449MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 450MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 451MODULE_LICENSE("GPL");
 452