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 <linux/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
  49 static 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
  55 struct lapbethdev {
  56         struct list_head        node;
  57         struct net_device       *ethdev;        /* link to ethernet device */
  58         struct net_device       *axdev;         /* lapbeth device (lapb#) */
  59         bool                    up;
  60         spinlock_t              up_lock;        /* Protects "up" */
  61 };
  62
  63 static LIST_HEAD(lapbeth_devices);
  64
  65 /* ------------------------------------------------------------------------ */
  66
  67 /*
  68  *      Get the LAPB device for the ethernet device
  69  */
  70 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  71 {
  72         struct lapbethdev *lapbeth;
  73
  74         list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  75                 if (lapbeth->ethdev == dev)
  76                         return lapbeth;
  77         }
  78         return NULL;
  79 }
  80
  81 static __inline__ int dev_is_ethdev(struct net_device *dev)
  82 {
  83         return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  84 }
  85
  86 /* ------------------------------------------------------------------------ */
  87
  88 /*
  89  *      Receive a LAPB frame via an ethernet interface.
  90  */
  91 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  92 {
  93         int len, err;
  94         struct lapbethdev *lapbeth;
  95
  96         if (dev_net(dev) != &init_net)
  97                 goto drop;
  98
  99         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
 100                 return NET_RX_DROP;
 101
 102         if (!pskb_may_pull(skb, 2))
 103                 goto drop;
 104
 105         rcu_read_lock();
 106         lapbeth = lapbeth_get_x25_dev(dev);
 107         if (!lapbeth)
 108                 goto drop_unlock_rcu;
 109         spin_lock_bh(&lapbeth->up_lock);
 110         if (!lapbeth->up)
 111                 goto drop_unlock;
 112
 113         len = skb->data[0] + skb->data[1] * 256;
 114         dev->stats.rx_packets++;
 115         dev->stats.rx_bytes += len;
 116
 117         skb_pull(skb, 2);       /* Remove the length bytes */
 118         skb_trim(skb, len);     /* Set the length of the data */
 119
 120         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 121                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 122                 goto drop_unlock;
 123         }
 124 out:
 125         spin_unlock_bh(&lapbeth->up_lock);
 126         rcu_read_unlock();
 127         return 0;
 128 drop_unlock:
 129         kfree_skb(skb);
 130         goto out;
 131 drop_unlock_rcu:
 132         rcu_read_unlock();
 133 drop:
 134         kfree_skb(skb);
 135         return 0;
 136 }
 137
 138 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 139 {
 140         unsigned char *ptr;
 141
 142         skb_push(skb, 1);
 143
 144         if (skb_cow(skb, 1))
 145                 return NET_RX_DROP;
 146
 147         ptr  = skb->data;
 148         *ptr = X25_IFACE_DATA;
 149
 150         skb->protocol = x25_type_trans(skb, dev);
 151         return netif_rx(skb);
 152 }
 153
 154 /*
 155  *      Send a LAPB frame via an ethernet interface
 156  */
 157 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 158                                       struct net_device *dev)
 159 {
 160         struct lapbethdev *lapbeth = netdev_priv(dev);
 161         int err;
 162
 163         spin_lock_bh(&lapbeth->up_lock);
 164         if (!lapbeth->up)
 165                 goto drop;
 166
 167         /* There should be a pseudo header of 1 byte added by upper layers.
 168          * Check to make sure it is there before reading it.
 169          */
 170         if (skb->len < 1)
 171                 goto drop;
 172
 173         switch (skb->data[0]) {
 174         case X25_IFACE_DATA:
 175                 break;
 176         case X25_IFACE_CONNECT:
 177                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 178                         pr_err("lapb_connect_request error: %d\n", err);
 179                 goto drop;
 180         case X25_IFACE_DISCONNECT:
 181                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 182                         pr_err("lapb_disconnect_request err: %d\n", err);
 183                 /* Fall thru */
 184         default:
 185                 goto drop;
 186         }
 187
 188         skb_pull(skb, 1);
 189
 190         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 191                 pr_err("lapb_data_request error - %d\n", err);
 192                 goto drop;
 193         }
 194 out:
 195         spin_unlock_bh(&lapbeth->up_lock);
 196         return NETDEV_TX_OK;
 197 drop:
 198         kfree_skb(skb);
 199         goto out;
 200 }
 201
 202 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 203 {
 204         struct lapbethdev *lapbeth = netdev_priv(ndev);
 205         unsigned char *ptr;
 206         struct net_device *dev;
 207         int size = skb->len;
 208
 209         ptr = skb_push(skb, 2);
 210
 211         *ptr++ = size % 256;
 212         *ptr++ = size / 256;
 213
 214         ndev->stats.tx_packets++;
 215         ndev->stats.tx_bytes += size;
 216
 217         skb->dev = dev = lapbeth->ethdev;
 218
 219         skb->protocol = htons(ETH_P_DEC);
 220
 221         skb_reset_network_header(skb);
 222
 223         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 224
 225         dev_queue_xmit(skb);
 226 }
 227
 228 static void lapbeth_connected(struct net_device *dev, int reason)
 229 {
 230         unsigned char *ptr;
 231         struct sk_buff *skb = dev_alloc_skb(1);
 232
 233         if (!skb) {
 234                 pr_err("out of memory\n");
 235                 return;
 236         }
 237
 238         ptr  = skb_put(skb, 1);
 239         *ptr = X25_IFACE_CONNECT;
 240
 241         skb->protocol = x25_type_trans(skb, dev);
 242         netif_rx(skb);
 243 }
 244
 245 static void lapbeth_disconnected(struct net_device *dev, int reason)
 246 {
 247         unsigned char *ptr;
 248         struct sk_buff *skb = dev_alloc_skb(1);
 249
 250         if (!skb) {
 251                 pr_err("out of memory\n");
 252                 return;
 253         }
 254
 255         ptr  = skb_put(skb, 1);
 256         *ptr = X25_IFACE_DISCONNECT;
 257
 258         skb->protocol = x25_type_trans(skb, dev);
 259         netif_rx(skb);
 260 }
 261
 262 /*
 263  *      Set AX.25 callsign
 264  */
 265 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 266 {
 267         struct sockaddr *sa = addr;
 268         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 269         return 0;
 270 }
 271
 272
 273 static const struct lapb_register_struct lapbeth_callbacks = {
 274         .connect_confirmation    = lapbeth_connected,
 275         .connect_indication      = lapbeth_connected,
 276         .disconnect_confirmation = lapbeth_disconnected,
 277         .disconnect_indication   = lapbeth_disconnected,
 278         .data_indication         = lapbeth_data_indication,
 279         .data_transmit           = lapbeth_data_transmit,
 280 };
 281
 282 /*
 283  * open/close a device
 284  */
 285 static int lapbeth_open(struct net_device *dev)
 286 {
 287         struct lapbethdev *lapbeth = netdev_priv(dev);
 288         int err;
 289
 290         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 291                 pr_err("lapb_register error: %d\n", err);
 292                 return -ENODEV;
 293         }
 294
 295         spin_lock_bh(&lapbeth->up_lock);
 296         lapbeth->up = true;
 297         spin_unlock_bh(&lapbeth->up_lock);
 298
 299         return 0;
 300 }
 301
 302 static int lapbeth_close(struct net_device *dev)
 303 {
 304         struct lapbethdev *lapbeth = netdev_priv(dev);
 305         int err;
 306
 307         spin_lock_bh(&lapbeth->up_lock);
 308         lapbeth->up = false;
 309         spin_unlock_bh(&lapbeth->up_lock);
 310
 311         if ((err = lapb_unregister(dev)) != LAPB_OK)
 312                 pr_err("lapb_unregister error: %d\n", err);
 313
 314         return 0;
 315 }
 316
 317 /* ------------------------------------------------------------------------ */
 318
 319 static const struct net_device_ops lapbeth_netdev_ops = {
 320         .ndo_open            = lapbeth_open,
 321         .ndo_stop            = lapbeth_close,
 322         .ndo_start_xmit      = lapbeth_xmit,
 323         .ndo_set_mac_address = lapbeth_set_mac_address,
 324 };
 325
 326 static void lapbeth_setup(struct net_device *dev)
 327 {
 328         dev->netdev_ops      = &lapbeth_netdev_ops;
 329         dev->needs_free_netdev = true;
 330         dev->type            = ARPHRD_X25;
 331         dev->hard_header_len = 0;
 332         dev->mtu             = 1000;
 333         dev->addr_len        = 0;
 334 }
 335
 336 /*
 337  *      Setup a new device.
 338  */
 339 static int lapbeth_new_device(struct net_device *dev)
 340 {
 341         struct net_device *ndev;
 342         struct lapbethdev *lapbeth;
 343         int rc = -ENOMEM;
 344
 345         ASSERT_RTNL();
 346
 347         if (dev->type != ARPHRD_ETHER)
 348                 return -EINVAL;
 349
 350         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 351                             lapbeth_setup);
 352         if (!ndev)
 353                 goto out;
 354
 355         /* When transmitting data:
 356          * first this driver removes a pseudo header of 1 byte,
 357          * then the lapb module prepends an LAPB header of at most 3 bytes,
 358          * then this driver prepends a length field of 2 bytes,
 359          * then the underlying Ethernet device prepends its own header.
 360          */
 361         ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
 362                                            + dev->needed_headroom;
 363         ndev->needed_tailroom = dev->needed_tailroom;
 364
 365         lapbeth = netdev_priv(ndev);
 366         lapbeth->axdev = ndev;
 367
 368         dev_hold(dev);
 369         lapbeth->ethdev = dev;
 370
 371         lapbeth->up = false;
 372         spin_lock_init(&lapbeth->up_lock);
 373
 374         rc = -EIO;
 375         if (register_netdevice(ndev))
 376                 goto fail;
 377
 378         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 379         rc = 0;
 380 out:
 381         return rc;
 382 fail:
 383         dev_put(dev);
 384         free_netdev(ndev);
 385         goto out;
 386 }
 387
 388 /*
 389  *      Free a lapb network device.
 390  */
 391 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 392 {
 393         dev_put(lapbeth->ethdev);
 394         list_del_rcu(&lapbeth->node);
 395         unregister_netdevice(lapbeth->axdev);
 396 }
 397
 398 /*
 399  *      Handle device status changes.
 400  *
 401  * Called from notifier with RTNL held.
 402  */
 403 static int lapbeth_device_event(struct notifier_block *this,
 404                                 unsigned long event, void *ptr)
 405 {
 406         struct lapbethdev *lapbeth;
 407         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 408
 409         if (dev_net(dev) != &init_net)
 410                 return NOTIFY_DONE;
 411
 412         if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev))
 413                 return NOTIFY_DONE;
 414
 415         switch (event) {
 416         case NETDEV_UP:
 417                 /* New ethernet device -> new LAPB interface     */
 418                 if (lapbeth_get_x25_dev(dev) == NULL)
 419                         lapbeth_new_device(dev);
 420                 break;
 421         case NETDEV_DOWN:
 422                 /* ethernet device closed -> close LAPB interface */
 423                 lapbeth = lapbeth_get_x25_dev(dev);
 424                 if (lapbeth)
 425                         dev_close(lapbeth->axdev);
 426                 break;
 427         case NETDEV_UNREGISTER:
 428                 /* ethernet device disappears -> remove LAPB interface */
 429                 lapbeth = lapbeth_get_x25_dev(dev);
 430                 if (lapbeth)
 431                         lapbeth_free_device(lapbeth);
 432                 break;
 433         }
 434
 435         return NOTIFY_DONE;
 436 }
 437
 438 /* ------------------------------------------------------------------------ */
 439
 440 static struct packet_type lapbeth_packet_type __read_mostly = {
 441         .type = cpu_to_be16(ETH_P_DEC),
 442         .func = lapbeth_rcv,
 443 };
 444
 445 static struct notifier_block lapbeth_dev_notifier = {
 446         .notifier_call = lapbeth_device_event,
 447 };
 448
 449 static const char banner[] __initconst =
 450         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 451
 452 static int __init lapbeth_init_driver(void)
 453 {
 454         dev_add_pack(&lapbeth_packet_type);
 455
 456         register_netdevice_notifier(&lapbeth_dev_notifier);
 457
 458         printk(banner);
 459
 460         return 0;
 461 }
 462 module_init(lapbeth_init_driver);
 463
 464 static void __exit lapbeth_cleanup_driver(void)
 465 {
 466         struct lapbethdev *lapbeth;
 467         struct list_head *entry, *tmp;
 468
 469         dev_remove_pack(&lapbeth_packet_type);
 470         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 471
 472         rtnl_lock();
 473         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 474                 lapbeth = list_entry(entry, struct lapbethdev, node);
 475
 476                 dev_put(lapbeth->ethdev);
 477                 unregister_netdevice(lapbeth->axdev);
 478         }
 479         rtnl_unlock();
 480 }
 481 module_exit(lapbeth_cleanup_driver);
 482
 483 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 484 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 485 MODULE_LICENSE("GPL");