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         /* There should be a pseudo header of 1 byte added by upper layers.
 164          * Check to make sure it is there before reading it.
 165          */
 166         if (skb->len < 1)
 167                 goto drop;
 168
 169         switch (skb->data[0]) {
 170         case X25_IFACE_DATA:
 171                 break;
 172         case X25_IFACE_CONNECT:
 173                 if ((err = lapb_connect_request(dev)) != LAPB_OK)
 174                         pr_err("lapb_connect_request error: %d\n", err);
 175                 goto drop;
 176         case X25_IFACE_DISCONNECT:
 177                 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
 178                         pr_err("lapb_disconnect_request err: %d\n", err);
 179                 /* Fall thru */
 180         default:
 181                 goto drop;
 182         }
 183
 184         skb_pull(skb, 1);
 185
 186         if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
 187                 pr_err("lapb_data_request error - %d\n", err);
 188                 goto drop;
 189         }
 190 out:
 191         return NETDEV_TX_OK;
 192 drop:
 193         kfree_skb(skb);
 194         goto out;
 195 }
 196
 197 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
 198 {
 199         struct lapbethdev *lapbeth = netdev_priv(ndev);
 200         unsigned char *ptr;
 201         struct net_device *dev;
 202         int size = skb->len;
 203
 204         skb->protocol = htons(ETH_P_X25);
 205
 206         ptr = skb_push(skb, 2);
 207
 208         *ptr++ = size % 256;
 209         *ptr++ = size / 256;
 210
 211         ndev->stats.tx_packets++;
 212         ndev->stats.tx_bytes += size;
 213
 214         skb->dev = dev = lapbeth->ethdev;
 215
 216         skb_reset_network_header(skb);
 217
 218         dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 219
 220         dev_queue_xmit(skb);
 221 }
 222
 223 static void lapbeth_connected(struct net_device *dev, int reason)
 224 {
 225         unsigned char *ptr;
 226         struct sk_buff *skb = dev_alloc_skb(1);
 227
 228         if (!skb) {
 229                 pr_err("out of memory\n");
 230                 return;
 231         }
 232
 233         ptr  = skb_put(skb, 1);
 234         *ptr = X25_IFACE_CONNECT;
 235
 236         skb->protocol = x25_type_trans(skb, dev);
 237         netif_rx(skb);
 238 }
 239
 240 static void lapbeth_disconnected(struct net_device *dev, int reason)
 241 {
 242         unsigned char *ptr;
 243         struct sk_buff *skb = dev_alloc_skb(1);
 244
 245         if (!skb) {
 246                 pr_err("out of memory\n");
 247                 return;
 248         }
 249
 250         ptr  = skb_put(skb, 1);
 251         *ptr = X25_IFACE_DISCONNECT;
 252
 253         skb->protocol = x25_type_trans(skb, dev);
 254         netif_rx(skb);
 255 }
 256
 257 /*
 258  *      Set AX.25 callsign
 259  */
 260 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 261 {
 262         struct sockaddr *sa = addr;
 263         memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
 264         return 0;
 265 }
 266
 267
 268 static const struct lapb_register_struct lapbeth_callbacks = {
 269         .connect_confirmation    = lapbeth_connected,
 270         .connect_indication      = lapbeth_connected,
 271         .disconnect_confirmation = lapbeth_disconnected,
 272         .disconnect_indication   = lapbeth_disconnected,
 273         .data_indication         = lapbeth_data_indication,
 274         .data_transmit           = lapbeth_data_transmit,
 275 };
 276
 277 /*
 278  * open/close a device
 279  */
 280 static int lapbeth_open(struct net_device *dev)
 281 {
 282         int err;
 283
 284         if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
 285                 pr_err("lapb_register error: %d\n", err);
 286                 return -ENODEV;
 287         }
 288
 289         netif_start_queue(dev);
 290         return 0;
 291 }
 292
 293 static int lapbeth_close(struct net_device *dev)
 294 {
 295         int err;
 296
 297         netif_stop_queue(dev);
 298
 299         if ((err = lapb_unregister(dev)) != LAPB_OK)
 300                 pr_err("lapb_unregister error: %d\n", err);
 301
 302         return 0;
 303 }
 304
 305 /* ------------------------------------------------------------------------ */
 306
 307 static const struct net_device_ops lapbeth_netdev_ops = {
 308         .ndo_open            = lapbeth_open,
 309         .ndo_stop            = lapbeth_close,
 310         .ndo_start_xmit      = lapbeth_xmit,
 311         .ndo_set_mac_address = lapbeth_set_mac_address,
 312 };
 313
 314 static void lapbeth_setup(struct net_device *dev)
 315 {
 316         dev->netdev_ops      = &lapbeth_netdev_ops;
 317         dev->needs_free_netdev = true;
 318         dev->type            = ARPHRD_X25;
 319         dev->hard_header_len = 0;
 320         dev->mtu             = 1000;
 321         dev->addr_len        = 0;
 322 }
 323
 324 /*
 325  *      Setup a new device.
 326  */
 327 static int lapbeth_new_device(struct net_device *dev)
 328 {
 329         struct net_device *ndev;
 330         struct lapbethdev *lapbeth;
 331         int rc = -ENOMEM;
 332
 333         ASSERT_RTNL();
 334
 335         ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
 336                             lapbeth_setup);
 337         if (!ndev)
 338                 goto out;
 339
 340         /* When transmitting data:
 341          * first this driver removes a pseudo header of 1 byte,
 342          * then the lapb module prepends an LAPB header of at most 3 bytes,
 343          * then this driver prepends a length field of 2 bytes,
 344          * then the underlying Ethernet device prepends its own header.
 345          */
 346         ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
 347                                            + dev->needed_headroom;
 348         ndev->needed_tailroom = dev->needed_tailroom;
 349
 350         lapbeth = netdev_priv(ndev);
 351         lapbeth->axdev = ndev;
 352
 353         dev_hold(dev);
 354         lapbeth->ethdev = dev;
 355
 356         rc = -EIO;
 357         if (register_netdevice(ndev))
 358                 goto fail;
 359
 360         list_add_rcu(&lapbeth->node, &lapbeth_devices);
 361         rc = 0;
 362 out:
 363         return rc;
 364 fail:
 365         dev_put(dev);
 366         free_netdev(ndev);
 367         goto out;
 368 }
 369
 370 /*
 371  *      Free a lapb network device.
 372  */
 373 static void lapbeth_free_device(struct lapbethdev *lapbeth)
 374 {
 375         dev_put(lapbeth->ethdev);
 376         list_del_rcu(&lapbeth->node);
 377         unregister_netdevice(lapbeth->axdev);
 378 }
 379
 380 /*
 381  *      Handle device status changes.
 382  *
 383  * Called from notifier with RTNL held.
 384  */
 385 static int lapbeth_device_event(struct notifier_block *this,
 386                                 unsigned long event, void *ptr)
 387 {
 388         struct lapbethdev *lapbeth;
 389         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 390
 391         if (dev_net(dev) != &init_net)
 392                 return NOTIFY_DONE;
 393
 394         if (!dev_is_ethdev(dev))
 395                 return NOTIFY_DONE;
 396
 397         switch (event) {
 398         case NETDEV_UP:
 399                 /* New ethernet device -> new LAPB interface     */
 400                 if (lapbeth_get_x25_dev(dev) == NULL)
 401                         lapbeth_new_device(dev);
 402                 break;
 403         case NETDEV_DOWN:
 404                 /* ethernet device closed -> close LAPB interface */
 405                 lapbeth = lapbeth_get_x25_dev(dev);
 406                 if (lapbeth)
 407                         dev_close(lapbeth->axdev);
 408                 break;
 409         case NETDEV_UNREGISTER:
 410                 /* ethernet device disappears -> remove LAPB interface */
 411                 lapbeth = lapbeth_get_x25_dev(dev);
 412                 if (lapbeth)
 413                         lapbeth_free_device(lapbeth);
 414                 break;
 415         }
 416
 417         return NOTIFY_DONE;
 418 }
 419
 420 /* ------------------------------------------------------------------------ */
 421
 422 static struct packet_type lapbeth_packet_type __read_mostly = {
 423         .type = cpu_to_be16(ETH_P_DEC),
 424         .func = lapbeth_rcv,
 425 };
 426
 427 static struct notifier_block lapbeth_dev_notifier = {
 428         .notifier_call = lapbeth_device_event,
 429 };
 430
 431 static const char banner[] __initconst =
 432         KERN_INFO "LAPB Ethernet driver version 0.02\n";
 433
 434 static int __init lapbeth_init_driver(void)
 435 {
 436         dev_add_pack(&lapbeth_packet_type);
 437
 438         register_netdevice_notifier(&lapbeth_dev_notifier);
 439
 440         printk(banner);
 441
 442         return 0;
 443 }
 444 module_init(lapbeth_init_driver);
 445
 446 static void __exit lapbeth_cleanup_driver(void)
 447 {
 448         struct lapbethdev *lapbeth;
 449         struct list_head *entry, *tmp;
 450
 451         dev_remove_pack(&lapbeth_packet_type);
 452         unregister_netdevice_notifier(&lapbeth_dev_notifier);
 453
 454         rtnl_lock();
 455         list_for_each_safe(entry, tmp, &lapbeth_devices) {
 456                 lapbeth = list_entry(entry, struct lapbethdev, node);
 457
 458                 dev_put(lapbeth->ethdev);
 459                 unregister_netdevice(lapbeth->axdev);
 460         }
 461         rtnl_unlock();
 462 }
 463 module_exit(lapbeth_cleanup_driver);
 464
 465 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 466 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
 467 MODULE_LICENSE("GPL");