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/system.h>
  39 #include <asm/uaccess.h>
  40 #include <linux/mm.h>
  41 #include <linux/interrupt.h>
  42 #include <linux/notifier.h>
  43 #include <linux/stat.h>
  44 #include <linux/netfilter.h>
  45 #include <linux/module.h>
  46 #include <linux/lapb.h>
  47 #include <linux/init.h>
  48
  49 #include <net/x25device.h>
  50
  51 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  52
  53 /* If this number is made larger, check that the temporary string buffer
  54  * in lapbeth_new_device is large enough to store the probe device name.*/
  55 #define MAXLAPBDEV 100
  56
  57 struct lapbethdev {
  58         struct list_head        node;
  59         struct net_device       *ethdev;        /* link to ethernet device */
  60         struct net_device       *axdev;         /* lapbeth device (lapb#) */
  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;
 109         if (!netif_running(lapbeth->axdev))
 110                 goto drop_unlock;
 111
 112         len = skb->data[0] + skb->data[1] * 256;
 113         dev->stats.rx_packets++;
 114         dev->stats.rx_bytes += len;
 115
 116         skb_pull(skb, 2);       /* Remove the length bytes */
 117         skb_trim(skb, len);     /* Set the length of the data */
 118
 119         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 120                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 121                 goto drop_unlock;
 122         }
 123 out:
 124         rcu_read_unlock();
 125         return 0;
 126 drop_unlock:
 127         kfree_skb(skb);
 128         goto out;
 129 drop:
 130         kfree_skb(skb);
 131         return 0;
 132 }
 133
 134 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 135 {
 136         unsigned char *ptr;
 137
 138         skb_push(skb, 1);
 139
 140         if (skb_cow(skb, 1))
 141                 return NET_RX_DROP;
 142
 143         ptr  = skb->data;
 144         *ptr = X25_IFACE_DATA;
 145
 146         skb->protocol = x25_type_trans(skb, dev);
 147         return netif_rx(skb);
 148 }
 149
 150 /*
 151  *      Send a LAPB frame via an ethernet interface
 152  */
 153 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 154                                       struct net_device *dev)
 155 {
 156         int err;
 157
 158         /*
 159          * Just to be *really* sure not to send anything if the interface
 160          * is down, the ethernet device may have gone.
 161          */
 162         if (!netif_running(dev))
 163                 goto drop;
 164
 165         switch (skb->data[0]) {
 166         case X25_IFACE_DATA:
 167                 break;
 168         case X25_IFACE_CONNECT:
 169                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 170                         pr_err("lapb_connect_request error: %d\n", err);
 171                 goto drop;
 172         case X25_IFACE_DISCONNECT:
 173                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 174                         pr_err("lapb_disconnect_request err: %d\n", err);
 175                 /* Fall thru */
 176         default:
 177                 goto drop;
 178         }
 179
 180         skb_pull(skb, 1);
 181
 182         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 183                 pr_err("lapb_data_request error - %d\n", err);
 184                 goto drop;
 185         }
 186 out:
 187         return NETDEV_TX_OK;
 188 drop:
 189         kfree_skb(skb);
 190         goto out;
 191 }
 192
 193 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 194 {
 195         struct lapbethdev *lapbeth = netdev_priv(ndev);
 196         unsigned char *ptr;
 197         struct net_device *dev;
 198         int size = skb->len;
 199
 200         skb->protocol = htons(ETH_P_X25);
 201
 202         ptr = skb_push(skb, 2);
 203
 204         *ptr++ = size % 256;
 205         *ptr++ = size / 256;
 206
 207         ndev->stats.tx_packets++;
 208         ndev->stats.tx_bytes += size;
 209
 210         skb->dev = dev = lapbeth->ethdev;
 211
 212         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 213
 214         dev_queue_xmit(skb);
 215 }
 216
 217 static void lapbeth_connected(struct net_device *dev, int reason)
 218 {
 219         unsigned char *ptr;
 220         struct sk_buff *skb = dev_alloc_skb(1);
 221
 222         if (!skb) {
 223                 pr_err("out of memory\n");
 224                 return;
 225         }
 226
 227         ptr  = skb_put(skb, 1);
 228         *ptr = X25_IFACE_CONNECT;
 229
 230         skb->protocol = x25_type_trans(skb, dev);
 231         netif_rx(skb);
 232 }
 233
 234 static void lapbeth_disconnected(struct net_device *dev, int reason)
 235 {
 236         unsigned char *ptr;
 237         struct sk_buff *skb = dev_alloc_skb(1);
 238
 239         if (!skb) {
 240                 pr_err("out of memory\n");
 241                 return;
 242         }
 243
 244         ptr  = skb_put(skb, 1);
 245         *ptr = X25_IFACE_DISCONNECT;
 246
 247         skb->protocol = x25_type_trans(skb, dev);
 248         netif_rx(skb);
 249 }
 250
 251 /*
 252  *      Set AX.25 callsign
 253  */
 254 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 255 {
 256         struct sockaddr *sa = addr;
 257         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 258         return 0;
 259 }
 260
 261
 262 static const struct lapb_register_struct lapbeth_callbacks = {
 263         .connect_confirmation    = lapbeth_connected,
 264         .connect_indication      = lapbeth_connected,
 265         .disconnect_confirmation = lapbeth_disconnected,
 266         .disconnect_indication   = lapbeth_disconnected,
 267         .data_indication         = lapbeth_data_indication,
 268         .data_transmit           = lapbeth_data_transmit,
 269 };
 270
 271 /*
 272  * open/close a device
 273  */
 274 static int lapbeth_open(struct net_device *dev)
 275 {
 276         int err;
 277
 278         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 279                 pr_err("lapb_register error: %d\n", err);
 280                 return -ENODEV;
 281         }
 282
 283         netif_start_queue(dev);
 284         return 0;
 285 }
 286
 287 static int lapbeth_close(struct net_device *dev)
 288 {
 289         int err;
 290
 291         netif_stop_queue(dev);
 292
 293         if ((err = lapb_unregister(dev)) != LAPB_OK)
 294                 pr_err("lapb_unregister error: %d\n", err);
 295
 296         return 0;
 297 }
 298
 299 /* ------------------------------------------------------------------------ */
 300
 301 static const struct net_device_ops lapbeth_netdev_ops = {
 302         .ndo_open            = lapbeth_open,
 303         .ndo_stop            = lapbeth_close,
 304         .ndo_start_xmit      = lapbeth_xmit,
 305         .ndo_set_mac_address = lapbeth_set_mac_address,
 306 };
 307
 308 static void lapbeth_setup(struct net_device *dev)
 309 {
 310         dev->netdev_ops      = &lapbeth_netdev_ops;
 311         dev->destructor      = free_netdev;
 312         dev->type            = ARPHRD_X25;
 313         dev->hard_header_len = 3;
 314         dev->mtu             = 1000;
 315         dev->addr_len        = 0;
 316 }
 317
 318 /*
 319  *      Setup a new device.
 320  */
 321 static int lapbeth_new_device(struct net_device *dev)
 322 {
 323         struct net_device *ndev;
 324         struct lapbethdev *lapbeth;
 325         int rc = -ENOMEM;
 326
 327         ASSERT_RTNL();
 328
 329         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
 330                            lapbeth_setup);
 331         if (!ndev)
 332                 goto out;
 333
 334         lapbeth = netdev_priv(ndev);
 335         lapbeth->axdev = ndev;
 336
 337         dev_hold(dev);
 338         lapbeth->ethdev = dev;
 339
 340         rc = -EIO;
 341         if (register_netdevice(ndev))
 342                 goto fail;
 343
 344         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 345         rc = 0;
 346 out:
 347         return rc;
 348 fail:
 349         dev_put(dev);
 350         free_netdev(ndev);
 351         kfree(lapbeth);
 352         goto out;
 353 }
 354
 355 /*
 356  *      Free a lapb network device.
 357  */
 358 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 359 {
 360         dev_put(lapbeth->ethdev);
 361         list_del_rcu(&lapbeth->node);
 362         unregister_netdevice(lapbeth->axdev);
 363 }
 364
 365 /*
 366  *      Handle device status changes.
 367  *
 368  * Called from notifier with RTNL held.
 369  */
 370 static int lapbeth_device_event(struct notifier_block *this,
 371                                 unsigned long event, void *ptr)
 372 {
 373         struct lapbethdev *lapbeth;
 374         struct net_device *dev = ptr;
 375
 376         if (dev_net(dev) != &init_net)
 377                 return NOTIFY_DONE;
 378
 379         if (!dev_is_ethdev(dev))
 380                 return NOTIFY_DONE;
 381
 382         switch (event) {
 383         case NETDEV_UP:
 384                 /* New ethernet device -> new LAPB interface     */
 385                 if (lapbeth_get_x25_dev(dev) == NULL)
 386                         lapbeth_new_device(dev);
 387                 break;
 388         case NETDEV_DOWN:
 389                 /* ethernet device closed -> close LAPB interface */
 390                 lapbeth = lapbeth_get_x25_dev(dev);
 391                 if (lapbeth)
 392                         dev_close(lapbeth->axdev);
 393                 break;
 394         case NETDEV_UNREGISTER:
 395                 /* ethernet device disappears -> remove LAPB interface */
 396                 lapbeth = lapbeth_get_x25_dev(dev);
 397                 if (lapbeth)
 398                         lapbeth_free_device(lapbeth);
 399                 break;
 400         }
 401
 402         return NOTIFY_DONE;
 403 }
 404
 405 /* ------------------------------------------------------------------------ */
 406
 407 static struct packet_type lapbeth_packet_type __read_mostly = {
 408         .type = cpu_to_be16(ETH_P_DEC),
 409         .func = lapbeth_rcv,
 410 };
 411
 412 static struct notifier_block lapbeth_dev_notifier = {
 413         .notifier_call = lapbeth_device_event,
 414 };
 415
 416 static const char banner[] __initconst =
 417         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 418
 419 static int __init lapbeth_init_driver(void)
 420 {
 421         dev_add_pack(&lapbeth_packet_type);
 422
 423         register_netdevice_notifier(&lapbeth_dev_notifier);
 424
 425         printk(banner);
 426
 427         return 0;
 428 }
 429 module_init(lapbeth_init_driver);
 430
 431 static void __exit lapbeth_cleanup_driver(void)
 432 {
 433         struct lapbethdev *lapbeth;
 434         struct list_head *entry, *tmp;
 435
 436         dev_remove_pack(&lapbeth_packet_type);
 437         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 438
 439         rtnl_lock();
 440         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 441                 lapbeth = list_entry(entry, struct lapbethdev, node);
 442
 443                 dev_put(lapbeth->ethdev);
 444                 unregister_netdevice(lapbeth->axdev);
 445         }
 446         rtnl_unlock();
 447 }
 448 module_exit(lapbeth_cleanup_driver);
 449
 450 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 451 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 452 MODULE_LICENSE("GPL");