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, lockdep_rtnl_is_held()) {
  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        if (skb_cow(skb, 1)) {
 132                kfree_skb(skb);
 133                return NET_RX_DROP;
 134        }
 135
 136        skb_push(skb, 1);
 137
 138        ptr  = skb->data;
 139        *ptr = X25_IFACE_DATA;
 140
 141        skb->protocol = x25_type_trans(skb, dev);
 142        return netif_rx(skb);
 143}
 144
 145/*
 146 *      Send a LAPB frame via an ethernet interface
 147 */
 148static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 149                                      struct net_device *dev)
 150{
 151        int err;
 152
 153        /*
 154         * Just to be *really* sure not to send anything if the interface
 155         * is down, the ethernet device may have gone.
 156         */
 157        if (!netif_running(dev))
 158                goto drop;
 159
 160        /* There should be a pseudo header of 1 byte added by upper layers.
 161         * Check to make sure it is there before reading it.
 162         */
 163        if (skb->len < 1)
 164                goto drop;
 165
 166        switch (skb->data[0]) {
 167        case X25_IFACE_DATA:
 168                break;
 169        case X25_IFACE_CONNECT:
 170                if ((err = lapb_connect_request(dev)) != LAPB_OK)
 171                        pr_err("lapb_connect_request error: %d\n", err);
 172                goto drop;
 173        case X25_IFACE_DISCONNECT:
 174                if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 175                        pr_err("lapb_disconnect_request err: %d\n", err);
 176                fallthrough;
 177        default:
 178                goto drop;
 179        }
 180
 181        skb_pull(skb, 1);
 182
 183        if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 184                pr_err("lapb_data_request error - %d\n", err);
 185                goto drop;
 186        }
 187out:
 188        return NETDEV_TX_OK;
 189drop:
 190        kfree_skb(skb);
 191        goto out;
 192}
 193
 194static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 195{
 196        struct lapbethdev *lapbeth = netdev_priv(ndev);
 197        unsigned char *ptr;
 198        struct net_device *dev;
 199        int size = skb->len;
 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        skb->protocol = htons(ETH_P_DEC);
 212
 213        skb_reset_network_header(skb);
 214
 215        dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 216
 217        dev_queue_xmit(skb);
 218}
 219
 220static void lapbeth_connected(struct net_device *dev, int reason)
 221{
 222        unsigned char *ptr;
 223        struct sk_buff *skb = dev_alloc_skb(1);
 224
 225        if (!skb) {
 226                pr_err("out of memory\n");
 227                return;
 228        }
 229
 230        ptr  = skb_put(skb, 1);
 231        *ptr = X25_IFACE_CONNECT;
 232
 233        skb->protocol = x25_type_trans(skb, dev);
 234        netif_rx(skb);
 235}
 236
 237static void lapbeth_disconnected(struct net_device *dev, int reason)
 238{
 239        unsigned char *ptr;
 240        struct sk_buff *skb = dev_alloc_skb(1);
 241
 242        if (!skb) {
 243                pr_err("out of memory\n");
 244                return;
 245        }
 246
 247        ptr  = skb_put(skb, 1);
 248        *ptr = X25_IFACE_DISCONNECT;
 249
 250        skb->protocol = x25_type_trans(skb, dev);
 251        netif_rx(skb);
 252}
 253
 254/*
 255 *      Set AX.25 callsign
 256 */
 257static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 258{
 259        struct sockaddr *sa = addr;
 260        memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 261        return 0;
 262}
 263
 264
 265static const struct lapb_register_struct lapbeth_callbacks = {
 266        .connect_confirmation    = lapbeth_connected,
 267        .connect_indication      = lapbeth_connected,
 268        .disconnect_confirmation = lapbeth_disconnected,
 269        .disconnect_indication   = lapbeth_disconnected,
 270        .data_indication         = lapbeth_data_indication,
 271        .data_transmit           = lapbeth_data_transmit,
 272};
 273
 274/*
 275 * open/close a device
 276 */
 277static int lapbeth_open(struct net_device *dev)
 278{
 279        int err;
 280
 281        if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 282                pr_err("lapb_register error: %d\n", err);
 283                return -ENODEV;
 284        }
 285
 286        netif_start_queue(dev);
 287        return 0;
 288}
 289
 290static int lapbeth_close(struct net_device *dev)
 291{
 292        int err;
 293
 294        netif_stop_queue(dev);
 295
 296        if ((err = lapb_unregister(dev)) != LAPB_OK)
 297                pr_err("lapb_unregister error: %d\n", err);
 298
 299        return 0;
 300}
 301
 302/* ------------------------------------------------------------------------ */
 303
 304static const struct net_device_ops lapbeth_netdev_ops = {
 305        .ndo_open            = lapbeth_open,
 306        .ndo_stop            = lapbeth_close,
 307        .ndo_start_xmit      = lapbeth_xmit,
 308        .ndo_set_mac_address = lapbeth_set_mac_address,
 309};
 310
 311static void lapbeth_setup(struct net_device *dev)
 312{
 313        dev->netdev_ops      = &lapbeth_netdev_ops;
 314        dev->needs_free_netdev = true;
 315        dev->type            = ARPHRD_X25;
 316        dev->hard_header_len = 0;
 317        dev->mtu             = 1000;
 318        dev->addr_len        = 0;
 319}
 320
 321/*
 322 *      Setup a new device.
 323 */
 324static int lapbeth_new_device(struct net_device *dev)
 325{
 326        struct net_device *ndev;
 327        struct lapbethdev *lapbeth;
 328        int rc = -ENOMEM;
 329
 330        ASSERT_RTNL();
 331
 332        ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 333                            lapbeth_setup);
 334        if (!ndev)
 335                goto out;
 336
 337        /* When transmitting data:
 338         * first this driver removes a pseudo header of 1 byte,
 339         * then the lapb module prepends an LAPB header of at most 3 bytes,
 340         * then this driver prepends a length field of 2 bytes,
 341         * then the underlying Ethernet device prepends its own header.
 342         */
 343        ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
 344                                           + dev->needed_headroom;
 345        ndev->needed_tailroom = dev->needed_tailroom;
 346
 347        lapbeth = netdev_priv(ndev);
 348        lapbeth->axdev = ndev;
 349
 350        dev_hold(dev);
 351        lapbeth->ethdev = dev;
 352
 353        rc = -EIO;
 354        if (register_netdevice(ndev))
 355                goto fail;
 356
 357        list_add_rcu(&lapbeth->node, &lapbeth_devices);
 358        rc = 0;
 359out:
 360        return rc;
 361fail:
 362        dev_put(dev);
 363        free_netdev(ndev);
 364        goto out;
 365}
 366
 367/*
 368 *      Free a lapb network device.
 369 */
 370static void lapbeth_free_device(struct lapbethdev *lapbeth)
 371{
 372        dev_put(lapbeth->ethdev);
 373        list_del_rcu(&lapbeth->node);
 374        unregister_netdevice(lapbeth->axdev);
 375}
 376
 377/*
 378 *      Handle device status changes.
 379 *
 380 * Called from notifier with RTNL held.
 381 */
 382static int lapbeth_device_event(struct notifier_block *this,
 383                                unsigned long event, void *ptr)
 384{
 385        struct lapbethdev *lapbeth;
 386        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 387
 388        if (dev_net(dev) != &init_net)
 389                return NOTIFY_DONE;
 390
 391        if (!dev_is_ethdev(dev))
 392                return NOTIFY_DONE;
 393
 394        switch (event) {
 395        case NETDEV_UP:
 396                /* New ethernet device -> new LAPB interface     */
 397                if (lapbeth_get_x25_dev(dev) == NULL)
 398                        lapbeth_new_device(dev);
 399                break;
 400        case NETDEV_DOWN:       
 401                /* ethernet device closed -> close LAPB interface */
 402                lapbeth = lapbeth_get_x25_dev(dev);
 403                if (lapbeth) 
 404                        dev_close(lapbeth->axdev);
 405                break;
 406        case NETDEV_UNREGISTER:
 407                /* ethernet device disappears -> remove LAPB interface */
 408                lapbeth = lapbeth_get_x25_dev(dev);
 409                if (lapbeth)
 410                        lapbeth_free_device(lapbeth);
 411                break;
 412        }
 413
 414        return NOTIFY_DONE;
 415}
 416
 417/* ------------------------------------------------------------------------ */
 418
 419static struct packet_type lapbeth_packet_type __read_mostly = {
 420        .type = cpu_to_be16(ETH_P_DEC),
 421        .func = lapbeth_rcv,
 422};
 423
 424static struct notifier_block lapbeth_dev_notifier = {
 425        .notifier_call = lapbeth_device_event,
 426};
 427
 428static const char banner[] __initconst =
 429        KERN_INFO "LAPB Ethernet driver version 0.02\n";
 430
 431static int __init lapbeth_init_driver(void)
 432{
 433        dev_add_pack(&lapbeth_packet_type);
 434
 435        register_netdevice_notifier(&lapbeth_dev_notifier);
 436
 437        printk(banner);
 438
 439        return 0;
 440}
 441module_init(lapbeth_init_driver);
 442
 443static void __exit lapbeth_cleanup_driver(void)
 444{
 445        struct lapbethdev *lapbeth;
 446        struct list_head *entry, *tmp;
 447
 448        dev_remove_pack(&lapbeth_packet_type);
 449        unregister_netdevice_notifier(&lapbeth_dev_notifier);
 450
 451        rtnl_lock();
 452        list_for_each_safe(entry, tmp, &lapbeth_devices) {
 453                lapbeth = list_entry(entry, struct lapbethdev, node);
 454
 455                dev_put(lapbeth->ethdev);
 456                unregister_netdevice(lapbeth->axdev);
 457        }
 458        rtnl_unlock();
 459}
 460module_exit(lapbeth_cleanup_driver);
 461
 462MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 463MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 464MODULE_LICENSE("GPL");
 465