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
  50 static 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
  56 struct 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
  62 static LIST_HEAD(lapbeth_devices);
  63
  64 /* ------------------------------------------------------------------------ */
  65
  66 /*
  67  *      Get the LAPB device for the ethernet device
  68  */
  69 static 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
  80 static __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  */
  90 static 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         }
 122 out:
 123         rcu_read_unlock();
 124         return 0;
 125 drop_unlock:
 126         kfree_skb(skb);
 127         goto out;
 128 drop:
 129         kfree_skb(skb);
 130         return 0;
 131 }
 132
 133 static 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  */
 152 static 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         }
 185 out:
 186         return NETDEV_TX_OK;
 187 drop:
 188         kfree_skb(skb);
 189         goto out;
 190 }
 191
 192 static 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
 216 static 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
 233 static 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  */
 253 static 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
 261 static 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  */
 273 static 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
 286 static 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
 300 static 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
 307 static 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  */
 320 static 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;
 345 out:
 346         return rc;
 347 fail:
 348         dev_put(dev);
 349         free_netdev(ndev);
 350         kfree(lapbeth);
 351         goto out;
 352 }
 353
 354 /*
 355  *      Free a lapb network device.
 356  */
 357 static 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  */
 369 static int lapbeth_device_event(struct notifier_block *this,
 370                                 unsigned long event, void *ptr)
 371 {
 372         struct lapbethdev *lapbeth;
 373         struct net_device *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
 406 static struct packet_type lapbeth_packet_type __read_mostly = {
 407         .type = cpu_to_be16(ETH_P_DEC),
 408         .func = lapbeth_rcv,
 409 };
 410
 411 static struct notifier_block lapbeth_dev_notifier = {
 412         .notifier_call = lapbeth_device_event,
 413 };
 414
 415 static const char banner[] __initconst =
 416         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 417
 418 static 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 }
 428 module_init(lapbeth_init_driver);
 429
 430 static 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 }
 447 module_exit(lapbeth_cleanup_driver);
 448
 449 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 450 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 451 MODULE_LICENSE("GPL");