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/module.h>
  44#include <linux/lapb.h>
  45#include <linux/init.h>
  46
  47#include <net/x25device.h>
  48
  49static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  50
  51/* If this number is made larger, check that the temporary string buffer
  52 * in lapbeth_new_device is large enough to store the probe device name.*/
  53#define MAXLAPBDEV 100
  54
  55struct lapbethdev {
  56        struct list_head        node;
  57        struct net_device       *ethdev;        /* link to ethernet device */
  58        struct net_device       *axdev;         /* lapbeth device (lapb#) */
  59};
  60
  61static LIST_HEAD(lapbeth_devices);
  62
  63/* ------------------------------------------------------------------------ */
  64
  65/*
  66 *      Get the LAPB device for the ethernet device
  67 */
  68static 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
  79static __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 */
  89static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  90{
  91        int len, err;
  92        struct lapbethdev *lapbeth;
  93
  94        if (dev_net(dev) != &init_net)
  95                goto drop;
  96
  97        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  98                return NET_RX_DROP;
  99
 100        if (!pskb_may_pull(skb, 2))
 101                goto drop;
 102
 103        rcu_read_lock();
 104        lapbeth = lapbeth_get_x25_dev(dev);
 105        if (!lapbeth)
 106                goto drop_unlock;
 107        if (!netif_running(lapbeth->axdev))
 108                goto drop_unlock;
 109
 110        len = skb->data[0] + skb->data[1] * 256;
 111        dev->stats.rx_packets++;
 112        dev->stats.rx_bytes += len;
 113
 114        skb_pull(skb, 2);       /* Remove the length bytes */
 115        skb_trim(skb, len);     /* Set the length of the data */
 116
 117        if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 118                printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 119                goto drop_unlock;
 120        }
 121out:
 122        rcu_read_unlock();
 123        return 0;
 124drop_unlock:
 125        kfree_skb(skb);
 126        goto out;
 127drop:
 128        kfree_skb(skb);
 129        return 0;
 130}
 131
 132static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 133{
 134        unsigned char *ptr;
 135
 136        skb_push(skb, 1);
 137
 138        if (skb_cow(skb, 1))
 139                return NET_RX_DROP;
 140
 141        ptr  = skb->data;
 142        *ptr = X25_IFACE_DATA;
 143
 144        skb->protocol = x25_type_trans(skb, dev);
 145        return netif_rx(skb);
 146}
 147
 148/*
 149 *      Send a LAPB frame via an ethernet interface
 150 */
 151static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 152                                      struct net_device *dev)
 153{
 154        int err;
 155
 156        /*
 157         * Just to be *really* sure not to send anything if the interface
 158         * is down, the ethernet device may have gone.
 159         */
 160        if (!netif_running(dev))
 161                goto drop;
 162
 163        switch (skb->data[0]) {
 164        case X25_IFACE_DATA:
 165                break;
 166        case X25_IFACE_CONNECT:
 167                if ((err = lapb_connect_request(dev)) != LAPB_OK)
 168                        pr_err("lapb_connect_request error: %d\n", err);
 169                goto drop;
 170        case X25_IFACE_DISCONNECT:
 171                if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 172                        pr_err("lapb_disconnect_request 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                pr_err("lapb_data_request error - %d\n", err);
 182                goto drop;
 183        }
 184out:
 185        return NETDEV_TX_OK;
 186drop:
 187        kfree_skb(skb);
 188        goto out;
 189}
 190
 191static 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
 215static 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                pr_err("out of memory\n");
 222                return;
 223        }
 224
 225        ptr  = skb_put(skb, 1);
 226        *ptr = X25_IFACE_CONNECT;
 227
 228        skb->protocol = x25_type_trans(skb, dev);
 229        netif_rx(skb);
 230}
 231
 232static 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                pr_err("out of memory\n");
 239                return;
 240        }
 241
 242        ptr  = skb_put(skb, 1);
 243        *ptr = X25_IFACE_DISCONNECT;
 244
 245        skb->protocol = x25_type_trans(skb, dev);
 246        netif_rx(skb);
 247}
 248
 249/*
 250 *      Set AX.25 callsign
 251 */
 252static 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
 260static const 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 * open/close a device
 271 */
 272static int lapbeth_open(struct net_device *dev)
 273{
 274        int err;
 275
 276        if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 277                pr_err("lapb_register error: %d\n", err);
 278                return -ENODEV;
 279        }
 280
 281        netif_start_queue(dev);
 282        return 0;
 283}
 284
 285static int lapbeth_close(struct net_device *dev)
 286{
 287        int err;
 288
 289        netif_stop_queue(dev);
 290
 291        if ((err = lapb_unregister(dev)) != LAPB_OK)
 292                pr_err("lapb_unregister error: %d\n", err);
 293
 294        return 0;
 295}
 296
 297/* ------------------------------------------------------------------------ */
 298
 299static const struct net_device_ops lapbeth_netdev_ops = {
 300        .ndo_open            = lapbeth_open,
 301        .ndo_stop            = lapbeth_close,
 302        .ndo_start_xmit      = lapbeth_xmit,
 303        .ndo_set_mac_address = lapbeth_set_mac_address,
 304};
 305
 306static void lapbeth_setup(struct net_device *dev)
 307{
 308        dev->netdev_ops      = &lapbeth_netdev_ops;
 309        dev->destructor      = free_netdev;
 310        dev->type            = ARPHRD_X25;
 311        dev->hard_header_len = 3;
 312        dev->mtu             = 1000;
 313        dev->addr_len        = 0;
 314}
 315
 316/*
 317 *      Setup a new device.
 318 */
 319static int lapbeth_new_device(struct net_device *dev)
 320{
 321        struct net_device *ndev;
 322        struct lapbethdev *lapbeth;
 323        int rc = -ENOMEM;
 324
 325        ASSERT_RTNL();
 326
 327        ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 328                            lapbeth_setup);
 329        if (!ndev)
 330                goto out;
 331
 332        lapbeth = netdev_priv(ndev);
 333        lapbeth->axdev = ndev;
 334
 335        dev_hold(dev);
 336        lapbeth->ethdev = dev;
 337
 338        rc = -EIO;
 339        if (register_netdevice(ndev))
 340                goto fail;
 341
 342        list_add_rcu(&lapbeth->node, &lapbeth_devices);
 343        rc = 0;
 344out:
 345        return rc;
 346fail:
 347        dev_put(dev);
 348        free_netdev(ndev);
 349        kfree(lapbeth);
 350        goto out;
 351}
 352
 353/*
 354 *      Free a lapb network device.
 355 */
 356static void lapbeth_free_device(struct lapbethdev *lapbeth)
 357{
 358        dev_put(lapbeth->ethdev);
 359        list_del_rcu(&lapbeth->node);
 360        unregister_netdevice(lapbeth->axdev);
 361}
 362
 363/*
 364 *      Handle device status changes.
 365 *
 366 * Called from notifier with RTNL held.
 367 */
 368static int lapbeth_device_event(struct notifier_block *this,
 369                                unsigned long event, void *ptr)
 370{
 371        struct lapbethdev *lapbeth;
 372        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 373
 374        if (dev_net(dev) != &init_net)
 375                return NOTIFY_DONE;
 376
 377        if (!dev_is_ethdev(dev))
 378                return NOTIFY_DONE;
 379
 380        switch (event) {
 381        case NETDEV_UP:
 382                /* New ethernet device -> new LAPB interface     */
 383                if (lapbeth_get_x25_dev(dev) == NULL)
 384                        lapbeth_new_device(dev);
 385                break;
 386        case NETDEV_DOWN:       
 387                /* ethernet device closed -> close LAPB interface */
 388                lapbeth = lapbeth_get_x25_dev(dev);
 389                if (lapbeth) 
 390                        dev_close(lapbeth->axdev);
 391                break;
 392        case NETDEV_UNREGISTER:
 393                /* ethernet device disappears -> remove LAPB interface */
 394                lapbeth = lapbeth_get_x25_dev(dev);
 395                if (lapbeth)
 396                        lapbeth_free_device(lapbeth);
 397                break;
 398        }
 399
 400        return NOTIFY_DONE;
 401}
 402
 403/* ------------------------------------------------------------------------ */
 404
 405static struct packet_type lapbeth_packet_type __read_mostly = {
 406        .type = cpu_to_be16(ETH_P_DEC),
 407        .func = lapbeth_rcv,
 408};
 409
 410static struct notifier_block lapbeth_dev_notifier = {
 411        .notifier_call = lapbeth_device_event,
 412};
 413
 414static const char banner[] __initconst =
 415        KERN_INFO "LAPB Ethernet driver version 0.02\n";
 416
 417static int __init lapbeth_init_driver(void)
 418{
 419        dev_add_pack(&lapbeth_packet_type);
 420
 421        register_netdevice_notifier(&lapbeth_dev_notifier);
 422
 423        printk(banner);
 424
 425        return 0;
 426}
 427module_init(lapbeth_init_driver);
 428
 429static void __exit lapbeth_cleanup_driver(void)
 430{
 431        struct lapbethdev *lapbeth;
 432        struct list_head *entry, *tmp;
 433
 434        dev_remove_pack(&lapbeth_packet_type);
 435        unregister_netdevice_notifier(&lapbeth_dev_notifier);
 436
 437        rtnl_lock();
 438        list_for_each_safe(entry, tmp, &lapbeth_devices) {
 439                lapbeth = list_entry(entry, struct lapbethdev, node);
 440
 441                dev_put(lapbeth->ethdev);
 442                unregister_netdevice(lapbeth->axdev);
 443        }
 444        rtnl_unlock();
 445}
 446module_exit(lapbeth_cleanup_driver);
 447
 448MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 449MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 450MODULE_LICENSE("GPL");
 451