LXR linux/drivers/net/wan/lapbether.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      "LAPB via ethernet" driver release 001
   4 *
   5 *      This code REQUIRES 2.1.15 or higher/ NET3.038
   6 *
   7 *      This is a "pseudo" network driver to allow LAPB over Ethernet.
   8 *
   9 *      This driver can use any ethernet destination address, and can be 
  10 *      limited to accept frames from one dedicated ethernet card only.
  11 *
  12 *      History
  13 *      LAPBETH 001     Jonathan Naylor         Cloned from bpqether.c
  14 *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
  15 *      2000-11-14      Henner Eisen    dev_hold/put, NETDEV_GOING_DOWN support
  16 */
  17
  18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20#include <linux/errno.h>
  21#include <linux/types.h>
  22#include <linux/socket.h>
  23#include <linux/in.h>
  24#include <linux/slab.h>
  25#include <linux/kernel.h>
  26#include <linux/string.h>
  27#include <linux/net.h>
  28#include <linux/inet.h>
  29#include <linux/netdevice.h>
  30#include <linux/if_arp.h>
  31#include <linux/skbuff.h>
  32#include <net/sock.h>
  33#include <linux/uaccess.h>
  34#include <linux/mm.h>
  35#include <linux/interrupt.h>
  36#include <linux/notifier.h>
  37#include <linux/stat.h>
  38#include <linux/module.h>
  39#include <linux/lapb.h>
  40#include <linux/init.h>
  41
  42#include <net/x25device.h>
  43
  44static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  45
  46/* If this number is made larger, check that the temporary string buffer
  47 * in lapbeth_new_device is large enough to store the probe device name.*/
  48#define MAXLAPBDEV 100
  49
  50struct lapbethdev {
  51        struct list_head        node;
  52        struct net_device       *ethdev;        /* link to ethernet device */
  53        struct net_device       *axdev;         /* lapbeth device (lapb#) */
  54};
  55
  56static LIST_HEAD(lapbeth_devices);
  57
  58/* ------------------------------------------------------------------------ */
  59
  60/*
  61 *      Get the LAPB device for the ethernet device
  62 */
  63static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  64{
  65        struct lapbethdev *lapbeth;
  66
  67        list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  68                if (lapbeth->ethdev == dev) 
  69                        return lapbeth;
  70        }
  71        return NULL;
  72}
  73
  74static __inline__ int dev_is_ethdev(struct net_device *dev)
  75{
  76        return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  77}
  78
  79/* ------------------------------------------------------------------------ */
  80
  81/*
  82 *      Receive a LAPB frame via an ethernet interface.
  83 */
  84static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  85{
  86        int len, err;
  87        struct lapbethdev *lapbeth;
  88
  89        if (dev_net(dev) != &init_net)
  90                goto drop;
  91
  92        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  93                return NET_RX_DROP;
  94
  95        if (!pskb_may_pull(skb, 2))
  96                goto drop;
  97
  98        rcu_read_lock();
  99        lapbeth = lapbeth_get_x25_dev(dev);
 100        if (!lapbeth)
 101                goto drop_unlock;
 102        if (!netif_running(lapbeth->axdev))
 103                goto drop_unlock;
 104
 105        len = skb->data[0] + skb->data[1] * 256;
 106        dev->stats.rx_packets++;
 107        dev->stats.rx_bytes += len;
 108
 109        skb_pull(skb, 2);       /* Remove the length bytes */
 110        skb_trim(skb, len);     /* Set the length of the data */
 111
 112        if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 113                printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 114                goto drop_unlock;
 115        }
 116out:
 117        rcu_read_unlock();
 118        return 0;
 119drop_unlock:
 120        kfree_skb(skb);
 121        goto out;
 122drop:
 123        kfree_skb(skb);
 124        return 0;
 125}
 126
 127static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 128{
 129        unsigned char *ptr;
 130
 131        skb_push(skb, 1);
 132
 133        if (skb_cow(skb, 1))
 134                return NET_RX_DROP;
 135
 136        ptr  = skb->data;
 137        *ptr = X25_IFACE_DATA;
 138
 139        skb->protocol = x25_type_trans(skb, dev);
 140        return netif_rx(skb);
 141}
 142
 143/*
 144 *      Send a LAPB frame via an ethernet interface
 145 */
 146static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 147                                      struct net_device *dev)
 148{
 149        int err;
 150
 151        /*
 152         * Just to be *really* sure not to send anything if the interface
 153         * is down, the ethernet device may have gone.
 154         */
 155        if (!netif_running(dev))
 156                goto drop;
 157
 158        switch (skb->data[0]) {
 159        case X25_IFACE_DATA:
 160                break;
 161        case X25_IFACE_CONNECT:
 162                if ((err = lapb_connect_request(dev)) != LAPB_OK)
 163                        pr_err("lapb_connect_request error: %d\n", err);
 164                goto drop;
 165        case X25_IFACE_DISCONNECT:
 166                if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 167                        pr_err("lapb_disconnect_request err: %d\n", err);
 168                /* Fall thru */
 169        default:
 170                goto drop;
 171        }
 172
 173        skb_pull(skb, 1);
 174
 175        if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 176                pr_err("lapb_data_request error - %d\n", err);
 177                goto drop;
 178        }
 179out:
 180        return NETDEV_TX_OK;
 181drop:
 182        kfree_skb(skb);
 183        goto out;
 184}
 185
 186static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 187{
 188        struct lapbethdev *lapbeth = netdev_priv(ndev);
 189        unsigned char *ptr;
 190        struct net_device *dev;
 191        int size = skb->len;
 192
 193        skb->protocol = htons(ETH_P_X25);
 194
 195        ptr = skb_push(skb, 2);
 196
 197        *ptr++ = size % 256;
 198        *ptr++ = size / 256;
 199
 200        ndev->stats.tx_packets++;
 201        ndev->stats.tx_bytes += size;
 202
 203        skb->dev = dev = lapbeth->ethdev;
 204
 205        dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 206
 207        dev_queue_xmit(skb);
 208}
 209
 210static void lapbeth_connected(struct net_device *dev, int reason)
 211{
 212        unsigned char *ptr;
 213        struct sk_buff *skb = dev_alloc_skb(1);
 214
 215        if (!skb) {
 216                pr_err("out of memory\n");
 217                return;
 218        }
 219
 220        ptr  = skb_put(skb, 1);
 221        *ptr = X25_IFACE_CONNECT;
 222
 223        skb->protocol = x25_type_trans(skb, dev);
 224        netif_rx(skb);
 225}
 226
 227static void lapbeth_disconnected(struct net_device *dev, int reason)
 228{
 229        unsigned char *ptr;
 230        struct sk_buff *skb = dev_alloc_skb(1);
 231
 232        if (!skb) {
 233                pr_err("out of memory\n");
 234                return;
 235        }
 236
 237        ptr  = skb_put(skb, 1);
 238        *ptr = X25_IFACE_DISCONNECT;
 239
 240        skb->protocol = x25_type_trans(skb, dev);
 241        netif_rx(skb);
 242}
 243
 244/*
 245 *      Set AX.25 callsign
 246 */
 247static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 248{
 249        struct sockaddr *sa = addr;
 250        memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 251        return 0;
 252}
 253
 254
 255static const struct lapb_register_struct lapbeth_callbacks = {
 256        .connect_confirmation    = lapbeth_connected,
 257        .connect_indication      = lapbeth_connected,
 258        .disconnect_confirmation = lapbeth_disconnected,
 259        .disconnect_indication   = lapbeth_disconnected,
 260        .data_indication         = lapbeth_data_indication,
 261        .data_transmit           = lapbeth_data_transmit,
 262};
 263
 264/*
 265 * open/close a device
 266 */
 267static int lapbeth_open(struct net_device *dev)
 268{
 269        int err;
 270
 271        if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 272                pr_err("lapb_register error: %d\n", err);
 273                return -ENODEV;
 274        }
 275
 276        netif_start_queue(dev);
 277        return 0;
 278}
 279
 280static int lapbeth_close(struct net_device *dev)
 281{
 282        int err;
 283
 284        netif_stop_queue(dev);
 285
 286        if ((err = lapb_unregister(dev)) != LAPB_OK)
 287                pr_err("lapb_unregister error: %d\n", err);
 288
 289        return 0;
 290}
 291
 292/* ------------------------------------------------------------------------ */
 293
 294static const struct net_device_ops lapbeth_netdev_ops = {
 295        .ndo_open            = lapbeth_open,
 296        .ndo_stop            = lapbeth_close,
 297        .ndo_start_xmit      = lapbeth_xmit,
 298        .ndo_set_mac_address = lapbeth_set_mac_address,
 299};
 300
 301static void lapbeth_setup(struct net_device *dev)
 302{
 303        dev->netdev_ops      = &lapbeth_netdev_ops;
 304        dev->needs_free_netdev = true;
 305        dev->type            = ARPHRD_X25;
 306        dev->hard_header_len = 3;
 307        dev->mtu             = 1000;
 308        dev->addr_len        = 0;
 309}
 310
 311/*
 312 *      Setup a new device.
 313 */
 314static int lapbeth_new_device(struct net_device *dev)
 315{
 316        struct net_device *ndev;
 317        struct lapbethdev *lapbeth;
 318        int rc = -ENOMEM;
 319
 320        ASSERT_RTNL();
 321
 322        ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 323                            lapbeth_setup);
 324        if (!ndev)
 325                goto out;
 326
 327        lapbeth = netdev_priv(ndev);
 328        lapbeth->axdev = ndev;
 329
 330        dev_hold(dev);
 331        lapbeth->ethdev = dev;
 332
 333        rc = -EIO;
 334        if (register_netdevice(ndev))
 335                goto fail;
 336
 337        list_add_rcu(&lapbeth->node, &lapbeth_devices);
 338        rc = 0;
 339out:
 340        return rc;
 341fail:
 342        dev_put(dev);
 343        free_netdev(ndev);
 344        goto out;
 345}
 346
 347/*
 348 *      Free a lapb network device.
 349 */
 350static void lapbeth_free_device(struct lapbethdev *lapbeth)
 351{
 352        dev_put(lapbeth->ethdev);
 353        list_del_rcu(&lapbeth->node);
 354        unregister_netdevice(lapbeth->axdev);
 355}
 356
 357/*
 358 *      Handle device status changes.
 359 *
 360 * Called from notifier with RTNL held.
 361 */
 362static int lapbeth_device_event(struct notifier_block *this,
 363                                unsigned long event, void *ptr)
 364{
 365        struct lapbethdev *lapbeth;
 366        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 367
 368        if (dev_net(dev) != &init_net)
 369                return NOTIFY_DONE;
 370
 371        if (!dev_is_ethdev(dev))
 372                return NOTIFY_DONE;
 373
 374        switch (event) {
 375        case NETDEV_UP:
 376                /* New ethernet device -> new LAPB interface     */
 377                if (lapbeth_get_x25_dev(dev) == NULL)
 378                        lapbeth_new_device(dev);
 379                break;
 380        case NETDEV_DOWN:       
 381                /* ethernet device closed -> close LAPB interface */
 382                lapbeth = lapbeth_get_x25_dev(dev);
 383                if (lapbeth) 
 384                        dev_close(lapbeth->axdev);
 385                break;
 386        case NETDEV_UNREGISTER:
 387                /* ethernet device disappears -> remove LAPB interface */
 388                lapbeth = lapbeth_get_x25_dev(dev);
 389                if (lapbeth)
 390                        lapbeth_free_device(lapbeth);
 391                break;
 392        }
 393
 394        return NOTIFY_DONE;
 395}
 396
 397/* ------------------------------------------------------------------------ */
 398
 399static struct packet_type lapbeth_packet_type __read_mostly = {
 400        .type = cpu_to_be16(ETH_P_DEC),
 401        .func = lapbeth_rcv,
 402};
 403
 404static struct notifier_block lapbeth_dev_notifier = {
 405        .notifier_call = lapbeth_device_event,
 406};
 407
 408static const char banner[] __initconst =
 409        KERN_INFO "LAPB Ethernet driver version 0.02\n";
 410
 411static int __init lapbeth_init_driver(void)
 412{
 413        dev_add_pack(&lapbeth_packet_type);
 414
 415        register_netdevice_notifier(&lapbeth_dev_notifier);
 416
 417        printk(banner);
 418
 419        return 0;
 420}
 421module_init(lapbeth_init_driver);
 422
 423static void __exit lapbeth_cleanup_driver(void)
 424{
 425        struct lapbethdev *lapbeth;
 426        struct list_head *entry, *tmp;
 427
 428        dev_remove_pack(&lapbeth_packet_type);
 429        unregister_netdevice_notifier(&lapbeth_dev_notifier);
 430
 431        rtnl_lock();
 432        list_for_each_safe(entry, tmp, &lapbeth_devices) {
 433                lapbeth = list_entry(entry, struct lapbethdev, node);
 434
 435                dev_put(lapbeth->ethdev);
 436                unregister_netdevice(lapbeth->axdev);
 437        }
 438        rtnl_unlock();
 439}
 440module_exit(lapbeth_cleanup_driver);
 441
 442MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 443MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 444MODULE_LICENSE("GPL");
 445