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 };
  60
  61 static LIST_HEAD(lapbeth_devices);
  62
  63 /* ------------------------------------------------------------------------ */
  64
  65 /*
  66  *      Get the LAPB device for the ethernet device
  67  */
  68 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
  69 {
  70         struct lapbethdev *lapbeth;
  71
  72         list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
  73                 if (lapbeth->ethdev == dev)
  74                         return lapbeth;
  75         }
  76         return NULL;
  77 }
  78
  79 static __inline__ int dev_is_ethdev(struct net_device *dev)
  80 {
  81         return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
  82 }
  83
  84 /* ------------------------------------------------------------------------ */
  85
  86 /*
  87  *      Receive a LAPB frame via an ethernet interface.
  88  */
  89 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
  90 {
  91         int len, err;
  92         struct lapbethdev *lapbeth;
  93
  94         if (dev_net(dev) != &init_net)
  95                 goto drop;
  96
  97         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
  98                 return NET_RX_DROP;
  99
 100         if (!pskb_may_pull(skb, 2))
 101                 goto drop;
 102
 103         rcu_read_lock();
 104         lapbeth = lapbeth_get_x25_dev(dev);
 105         if (!lapbeth)
 106                 goto drop_unlock;
 107         if (!netif_running(lapbeth->axdev))
 108                 goto drop_unlock;
 109
 110         len = skb->data[0] + skb->data[1] * 256;
 111         dev->stats.rx_packets++;
 112         dev->stats.rx_bytes += len;
 113
 114         skb_pull(skb, 2);       /* Remove the length bytes */
 115         skb_trim(skb, len);     /* Set the length of the data */
 116
 117         if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
 118                 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
 119                 goto drop_unlock;
 120         }
 121 out:
 122         rcu_read_unlock();
 123         return 0;
 124 drop_unlock:
 125         kfree_skb(skb);
 126         goto out;
 127 drop:
 128         kfree_skb(skb);
 129         return 0;
 130 }
 131
 132 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
 133 {
 134         unsigned char *ptr;
 135
 136         skb_push(skb, 1);
 137
 138         if (skb_cow(skb, 1))
 139                 return NET_RX_DROP;
 140
 141         ptr  = skb->data;
 142         *ptr = X25_IFACE_DATA;
 143
 144         skb->protocol = x25_type_trans(skb, dev);
 145         return netif_rx(skb);
 146 }
 147
 148 /*
 149  *      Send a LAPB frame via an ethernet interface
 150  */
 151 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 152                                       struct net_device *dev)
 153 {
 154         int err;
 155
 156         /*
 157          * Just to be *really* sure not to send anything if the interface
 158          * is down, the ethernet device may have gone.
 159          */
 160         if (!netif_running(dev))
 161                 goto drop;
 162
 163         switch (skb->data[0]) {
 164         case X25_IFACE_DATA:
 165                 break;
 166         case X25_IFACE_CONNECT:
 167                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 168                         pr_err("lapb_connect_request error: %d\n", err);
 169                 goto drop;
 170         case X25_IFACE_DISCONNECT:
 171                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 172                         pr_err("lapb_disconnect_request err: %d\n", err);
 173                 /* Fall thru */
 174         default:
 175                 goto drop;
 176         }
 177
 178         skb_pull(skb, 1);
 179
 180         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 181                 pr_err("lapb_data_request error - %d\n", err);
 182                 goto drop;
 183         }
 184 out:
 185         return NETDEV_TX_OK;
 186 drop:
 187         kfree_skb(skb);
 188         goto out;
 189 }
 190
 191 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 192 {
 193         struct lapbethdev *lapbeth = netdev_priv(ndev);
 194         unsigned char *ptr;
 195         struct net_device *dev;
 196         int size = skb->len;
 197
 198         skb->protocol = htons(ETH_P_X25);
 199
 200         ptr = skb_push(skb, 2);
 201
 202         *ptr++ = size % 256;
 203         *ptr++ = size / 256;
 204
 205         ndev->stats.tx_packets++;
 206         ndev->stats.tx_bytes += size;
 207
 208         skb->dev = dev = lapbeth->ethdev;
 209
 210         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 211
 212         dev_queue_xmit(skb);
 213 }
 214
 215 static void lapbeth_connected(struct net_device *dev, int reason)
 216 {
 217         unsigned char *ptr;
 218         struct sk_buff *skb = dev_alloc_skb(1);
 219
 220         if (!skb) {
 221                 pr_err("out of memory\n");
 222                 return;
 223         }
 224
 225         ptr  = skb_put(skb, 1);
 226         *ptr = X25_IFACE_CONNECT;
 227
 228         skb->protocol = x25_type_trans(skb, dev);
 229         netif_rx(skb);
 230 }
 231
 232 static void lapbeth_disconnected(struct net_device *dev, int reason)
 233 {
 234         unsigned char *ptr;
 235         struct sk_buff *skb = dev_alloc_skb(1);
 236
 237         if (!skb) {
 238                 pr_err("out of memory\n");
 239                 return;
 240         }
 241
 242         ptr  = skb_put(skb, 1);
 243         *ptr = X25_IFACE_DISCONNECT;
 244
 245         skb->protocol = x25_type_trans(skb, dev);
 246         netif_rx(skb);
 247 }
 248
 249 /*
 250  *      Set AX.25 callsign
 251  */
 252 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 253 {
 254         struct sockaddr *sa = addr;
 255         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 256         return 0;
 257 }
 258
 259
 260 static const struct lapb_register_struct lapbeth_callbacks = {
 261         .connect_confirmation    = lapbeth_connected,
 262         .connect_indication      = lapbeth_connected,
 263         .disconnect_confirmation = lapbeth_disconnected,
 264         .disconnect_indication   = lapbeth_disconnected,
 265         .data_indication         = lapbeth_data_indication,
 266         .data_transmit           = lapbeth_data_transmit,
 267 };
 268
 269 /*
 270  * open/close a device
 271  */
 272 static int lapbeth_open(struct net_device *dev)
 273 {
 274         int err;
 275
 276         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 277                 pr_err("lapb_register error: %d\n", err);
 278                 return -ENODEV;
 279         }
 280
 281         netif_start_queue(dev);
 282         return 0;
 283 }
 284
 285 static int lapbeth_close(struct net_device *dev)
 286 {
 287         int err;
 288
 289         netif_stop_queue(dev);
 290
 291         if ((err = lapb_unregister(dev)) != LAPB_OK)
 292                 pr_err("lapb_unregister error: %d\n", err);
 293
 294         return 0;
 295 }
 296
 297 /* ------------------------------------------------------------------------ */
 298
 299 static const struct net_device_ops lapbeth_netdev_ops = {
 300         .ndo_open            = lapbeth_open,
 301         .ndo_stop            = lapbeth_close,
 302         .ndo_start_xmit      = lapbeth_xmit,
 303         .ndo_set_mac_address = lapbeth_set_mac_address,
 304 };
 305
 306 static void lapbeth_setup(struct net_device *dev)
 307 {
 308         dev->netdev_ops      = &lapbeth_netdev_ops;
 309         dev->needs_free_netdev = true;
 310         dev->type            = ARPHRD_X25;
 311         dev->hard_header_len = 3;
 312         dev->mtu             = 1000;
 313         dev->addr_len        = 0;
 314 }
 315
 316 /*
 317  *      Setup a new device.
 318  */
 319 static int lapbeth_new_device(struct net_device *dev)
 320 {
 321         struct net_device *ndev;
 322         struct lapbethdev *lapbeth;
 323         int rc = -ENOMEM;
 324
 325         ASSERT_RTNL();
 326
 327         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 328                             lapbeth_setup);
 329         if (!ndev)
 330                 goto out;
 331
 332         lapbeth = netdev_priv(ndev);
 333         lapbeth->axdev = ndev;
 334
 335         dev_hold(dev);
 336         lapbeth->ethdev = dev;
 337
 338         rc = -EIO;
 339         if (register_netdevice(ndev))
 340                 goto fail;
 341
 342         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 343         rc = 0;
 344 out:
 345         return rc;
 346 fail:
 347         dev_put(dev);
 348         free_netdev(ndev);
 349         kfree(lapbeth);
 350         goto out;
 351 }
 352
 353 /*
 354  *      Free a lapb network device.
 355  */
 356 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 357 {
 358         dev_put(lapbeth->ethdev);
 359         list_del_rcu(&lapbeth->node);
 360         unregister_netdevice(lapbeth->axdev);
 361 }
 362
 363 /*
 364  *      Handle device status changes.
 365  *
 366  * Called from notifier with RTNL held.
 367  */
 368 static int lapbeth_device_event(struct notifier_block *this,
 369                                 unsigned long event, void *ptr)
 370 {
 371         struct lapbethdev *lapbeth;
 372         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 373
 374         if (dev_net(dev) != &init_net)
 375                 return NOTIFY_DONE;
 376
 377         if (!dev_is_ethdev(dev))
 378                 return NOTIFY_DONE;
 379
 380         switch (event) {
 381         case NETDEV_UP:
 382                 /* New ethernet device -> new LAPB interface     */
 383                 if (lapbeth_get_x25_dev(dev) == NULL)
 384                         lapbeth_new_device(dev);
 385                 break;
 386         case NETDEV_DOWN:
 387                 /* ethernet device closed -> close LAPB interface */
 388                 lapbeth = lapbeth_get_x25_dev(dev);
 389                 if (lapbeth)
 390                         dev_close(lapbeth->axdev);
 391                 break;
 392         case NETDEV_UNREGISTER:
 393                 /* ethernet device disappears -> remove LAPB interface */
 394                 lapbeth = lapbeth_get_x25_dev(dev);
 395                 if (lapbeth)
 396                         lapbeth_free_device(lapbeth);
 397                 break;
 398         }
 399
 400         return NOTIFY_DONE;
 401 }
 402
 403 /* ------------------------------------------------------------------------ */
 404
 405 static struct packet_type lapbeth_packet_type __read_mostly = {
 406         .type = cpu_to_be16(ETH_P_DEC),
 407         .func = lapbeth_rcv,
 408 };
 409
 410 static struct notifier_block lapbeth_dev_notifier = {
 411         .notifier_call = lapbeth_device_event,
 412 };
 413
 414 static const char banner[] __initconst =
 415         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 416
 417 static int __init lapbeth_init_driver(void)
 418 {
 419         dev_add_pack(&lapbeth_packet_type);
 420
 421         register_netdevice_notifier(&lapbeth_dev_notifier);
 422
 423         printk(banner);
 424
 425         return 0;
 426 }
 427 module_init(lapbeth_init_driver);
 428
 429 static void __exit lapbeth_cleanup_driver(void)
 430 {
 431         struct lapbethdev *lapbeth;
 432         struct list_head *entry, *tmp;
 433
 434         dev_remove_pack(&lapbeth_packet_type);
 435         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 436
 437         rtnl_lock();
 438         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 439                 lapbeth = list_entry(entry, struct lapbethdev, node);
 440
 441                 dev_put(lapbeth->ethdev);
 442                 unregister_netdevice(lapbeth->axdev);
 443         }
 444         rtnl_unlock();
 445 }
 446 module_exit(lapbeth_cleanup_driver);
 447
 448 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 449 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 450 MODULE_LICENSE("GPL");