net/lapb/lapb_iface.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      LAPB release 002
   4  *
   5  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   6  *
   7  *      History
   8  *      LAPB 001        Jonathan Naylor Started Coding
   9  *      LAPB 002        Jonathan Naylor New timer architecture.
  10  *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/module.h>
  16 #include <linux/errno.h>
  17 #include <linux/types.h>
  18 #include <linux/socket.h>
  19 #include <linux/in.h>
  20 #include <linux/kernel.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/timer.h>
  23 #include <linux/string.h>
  24 #include <linux/sockios.h>
  25 #include <linux/net.h>
  26 #include <linux/inet.h>
  27 #include <linux/if_arp.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/slab.h>
  30 #include <net/sock.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/mm.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/stat.h>
  36 #include <linux/init.h>
  37 #include <net/lapb.h>
  38
  39 static LIST_HEAD(lapb_list);
  40 static DEFINE_RWLOCK(lapb_list_lock);
  41
  42 /*
  43  *      Free an allocated lapb control block.
  44  */
  45 static void lapb_free_cb(struct lapb_cb *lapb)
  46 {
  47         kfree(lapb);
  48 }
  49
  50 static __inline__ void lapb_hold(struct lapb_cb *lapb)
  51 {
  52         refcount_inc(&lapb->refcnt);
  53 }
  54
  55 static __inline__ void lapb_put(struct lapb_cb *lapb)
  56 {
  57         if (refcount_dec_and_test(&lapb->refcnt))
  58                 lapb_free_cb(lapb);
  59 }
  60
  61 /*
  62  *      Socket removal during an interrupt is now safe.
  63  */
  64 static void __lapb_remove_cb(struct lapb_cb *lapb)
  65 {
  66         if (lapb->node.next) {
  67                 list_del(&lapb->node);
  68                 lapb_put(lapb);
  69         }
  70 }
  71
  72 /*
  73  *      Add a socket to the bound sockets list.
  74  */
  75 static void __lapb_insert_cb(struct lapb_cb *lapb)
  76 {
  77         list_add(&lapb->node, &lapb_list);
  78         lapb_hold(lapb);
  79 }
  80
  81 static struct lapb_cb *__lapb_devtostruct(struct net_device *dev)
  82 {
  83         struct list_head *entry;
  84         struct lapb_cb *lapb, *use = NULL;
  85
  86         list_for_each(entry, &lapb_list) {
  87                 lapb = list_entry(entry, struct lapb_cb, node);
  88                 if (lapb->dev == dev) {
  89                         use = lapb;
  90                         break;
  91                 }
  92         }
  93
  94         if (use)
  95                 lapb_hold(use);
  96
  97         return use;
  98 }
  99
 100 static struct lapb_cb *lapb_devtostruct(struct net_device *dev)
 101 {
 102         struct lapb_cb *rc;
 103
 104         read_lock_bh(&lapb_list_lock);
 105         rc = __lapb_devtostruct(dev);
 106         read_unlock_bh(&lapb_list_lock);
 107
 108         return rc;
 109 }
 110 /*
 111  *      Create an empty LAPB control block.
 112  */
 113 static struct lapb_cb *lapb_create_cb(void)
 114 {
 115         struct lapb_cb *lapb = kzalloc(sizeof(*lapb), GFP_ATOMIC);
 116
 117         if (!lapb)
 118                 goto out;
 119
 120         skb_queue_head_init(&lapb->write_queue);
 121         skb_queue_head_init(&lapb->ack_queue);
 122
 123         timer_setup(&lapb->t1timer, NULL, 0);
 124         timer_setup(&lapb->t2timer, NULL, 0);
 125         lapb->t1timer_running = false;
 126         lapb->t2timer_running = false;
 127
 128         lapb->t1      = LAPB_DEFAULT_T1;
 129         lapb->t2      = LAPB_DEFAULT_T2;
 130         lapb->n2      = LAPB_DEFAULT_N2;
 131         lapb->mode    = LAPB_DEFAULT_MODE;
 132         lapb->window  = LAPB_DEFAULT_WINDOW;
 133         lapb->state   = LAPB_STATE_0;
 134
 135         spin_lock_init(&lapb->lock);
 136         refcount_set(&lapb->refcnt, 1);
 137 out:
 138         return lapb;
 139 }
 140
 141 int lapb_register(struct net_device *dev,
 142                   const struct lapb_register_struct *callbacks)
 143 {
 144         struct lapb_cb *lapb;
 145         int rc = LAPB_BADTOKEN;
 146
 147         write_lock_bh(&lapb_list_lock);
 148
 149         lapb = __lapb_devtostruct(dev);
 150         if (lapb) {
 151                 lapb_put(lapb);
 152                 goto out;
 153         }
 154
 155         lapb = lapb_create_cb();
 156         rc = LAPB_NOMEM;
 157         if (!lapb)
 158                 goto out;
 159
 160         lapb->dev       = dev;
 161         lapb->callbacks = callbacks;
 162
 163         __lapb_insert_cb(lapb);
 164
 165         lapb_start_t1timer(lapb);
 166
 167         rc = LAPB_OK;
 168 out:
 169         write_unlock_bh(&lapb_list_lock);
 170         return rc;
 171 }
 172 EXPORT_SYMBOL(lapb_register);
 173
 174 int lapb_unregister(struct net_device *dev)
 175 {
 176         struct lapb_cb *lapb;
 177         int rc = LAPB_BADTOKEN;
 178
 179         write_lock_bh(&lapb_list_lock);
 180         lapb = __lapb_devtostruct(dev);
 181         if (!lapb)
 182                 goto out;
 183         lapb_put(lapb);
 184
 185         /* Wait for other refs to "lapb" to drop */
 186         while (refcount_read(&lapb->refcnt) > 2)
 187                 usleep_range(1, 10);
 188
 189         spin_lock_bh(&lapb->lock);
 190
 191         lapb_stop_t1timer(lapb);
 192         lapb_stop_t2timer(lapb);
 193
 194         lapb_clear_queues(lapb);
 195
 196         spin_unlock_bh(&lapb->lock);
 197
 198         /* Wait for running timers to stop */
 199         del_timer_sync(&lapb->t1timer);
 200         del_timer_sync(&lapb->t2timer);
 201
 202         __lapb_remove_cb(lapb);
 203
 204         lapb_put(lapb);
 205         rc = LAPB_OK;
 206 out:
 207         write_unlock_bh(&lapb_list_lock);
 208         return rc;
 209 }
 210 EXPORT_SYMBOL(lapb_unregister);
 211
 212 int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms)
 213 {
 214         int rc = LAPB_BADTOKEN;
 215         struct lapb_cb *lapb = lapb_devtostruct(dev);
 216
 217         if (!lapb)
 218                 goto out;
 219
 220         spin_lock_bh(&lapb->lock);
 221
 222         parms->t1      = lapb->t1 / HZ;
 223         parms->t2      = lapb->t2 / HZ;
 224         parms->n2      = lapb->n2;
 225         parms->n2count = lapb->n2count;
 226         parms->state   = lapb->state;
 227         parms->window  = lapb->window;
 228         parms->mode    = lapb->mode;
 229
 230         if (!timer_pending(&lapb->t1timer))
 231                 parms->t1timer = 0;
 232         else
 233                 parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;
 234
 235         if (!timer_pending(&lapb->t2timer))
 236                 parms->t2timer = 0;
 237         else
 238                 parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;
 239
 240         spin_unlock_bh(&lapb->lock);
 241         lapb_put(lapb);
 242         rc = LAPB_OK;
 243 out:
 244         return rc;
 245 }
 246 EXPORT_SYMBOL(lapb_getparms);
 247
 248 int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
 249 {
 250         int rc = LAPB_BADTOKEN;
 251         struct lapb_cb *lapb = lapb_devtostruct(dev);
 252
 253         if (!lapb)
 254                 goto out;
 255
 256         spin_lock_bh(&lapb->lock);
 257
 258         rc = LAPB_INVALUE;
 259         if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1)
 260                 goto out_put;
 261
 262         if (lapb->state == LAPB_STATE_0) {
 263                 if (parms->mode & LAPB_EXTENDED) {
 264                         if (parms->window < 1 || parms->window > 127)
 265                                 goto out_put;
 266                 } else {
 267                         if (parms->window < 1 || parms->window > 7)
 268                                 goto out_put;
 269                 }
 270                 lapb->mode    = parms->mode;
 271                 lapb->window  = parms->window;
 272         }
 273
 274         lapb->t1    = parms->t1 * HZ;
 275         lapb->t2    = parms->t2 * HZ;
 276         lapb->n2    = parms->n2;
 277
 278         rc = LAPB_OK;
 279 out_put:
 280         spin_unlock_bh(&lapb->lock);
 281         lapb_put(lapb);
 282 out:
 283         return rc;
 284 }
 285 EXPORT_SYMBOL(lapb_setparms);
 286
 287 int lapb_connect_request(struct net_device *dev)
 288 {
 289         struct lapb_cb *lapb = lapb_devtostruct(dev);
 290         int rc = LAPB_BADTOKEN;
 291
 292         if (!lapb)
 293                 goto out;
 294
 295         spin_lock_bh(&lapb->lock);
 296
 297         rc = LAPB_OK;
 298         if (lapb->state == LAPB_STATE_1)
 299                 goto out_put;
 300
 301         rc = LAPB_CONNECTED;
 302         if (lapb->state == LAPB_STATE_3 || lapb->state == LAPB_STATE_4)
 303                 goto out_put;
 304
 305         lapb_establish_data_link(lapb);
 306
 307         lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
 308         lapb->state = LAPB_STATE_1;
 309
 310         rc = LAPB_OK;
 311 out_put:
 312         spin_unlock_bh(&lapb->lock);
 313         lapb_put(lapb);
 314 out:
 315         return rc;
 316 }
 317 EXPORT_SYMBOL(lapb_connect_request);
 318
 319 static int __lapb_disconnect_request(struct lapb_cb *lapb)
 320 {
 321         switch (lapb->state) {
 322         case LAPB_STATE_0:
 323                 return LAPB_NOTCONNECTED;
 324
 325         case LAPB_STATE_1:
 326                 lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
 327                 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 328                 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 329                 lapb->state = LAPB_STATE_0;
 330                 lapb_start_t1timer(lapb);
 331                 return LAPB_NOTCONNECTED;
 332
 333         case LAPB_STATE_2:
 334                 return LAPB_OK;
 335         }
 336
 337         lapb_clear_queues(lapb);
 338         lapb->n2count = 0;
 339         lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 340         lapb_start_t1timer(lapb);
 341         lapb_stop_t2timer(lapb);
 342         lapb->state = LAPB_STATE_2;
 343
 344         lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
 345         lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);
 346
 347         return LAPB_OK;
 348 }
 349
 350 int lapb_disconnect_request(struct net_device *dev)
 351 {
 352         struct lapb_cb *lapb = lapb_devtostruct(dev);
 353         int rc = LAPB_BADTOKEN;
 354
 355         if (!lapb)
 356                 goto out;
 357
 358         spin_lock_bh(&lapb->lock);
 359
 360         rc = __lapb_disconnect_request(lapb);
 361
 362         spin_unlock_bh(&lapb->lock);
 363         lapb_put(lapb);
 364 out:
 365         return rc;
 366 }
 367 EXPORT_SYMBOL(lapb_disconnect_request);
 368
 369 int lapb_data_request(struct net_device *dev, struct sk_buff *skb)
 370 {
 371         struct lapb_cb *lapb = lapb_devtostruct(dev);
 372         int rc = LAPB_BADTOKEN;
 373
 374         if (!lapb)
 375                 goto out;
 376
 377         spin_lock_bh(&lapb->lock);
 378
 379         rc = LAPB_NOTCONNECTED;
 380         if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
 381                 goto out_put;
 382
 383         skb_queue_tail(&lapb->write_queue, skb);
 384         lapb_kick(lapb);
 385         rc = LAPB_OK;
 386 out_put:
 387         spin_unlock_bh(&lapb->lock);
 388         lapb_put(lapb);
 389 out:
 390         return rc;
 391 }
 392 EXPORT_SYMBOL(lapb_data_request);
 393
 394 int lapb_data_received(struct net_device *dev, struct sk_buff *skb)
 395 {
 396         struct lapb_cb *lapb = lapb_devtostruct(dev);
 397         int rc = LAPB_BADTOKEN;
 398
 399         if (lapb) {
 400                 spin_lock_bh(&lapb->lock);
 401                 lapb_data_input(lapb, skb);
 402                 spin_unlock_bh(&lapb->lock);
 403                 lapb_put(lapb);
 404                 rc = LAPB_OK;
 405         }
 406
 407         return rc;
 408 }
 409 EXPORT_SYMBOL(lapb_data_received);
 410
 411 void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
 412 {
 413         if (lapb->callbacks->connect_confirmation)
 414                 lapb->callbacks->connect_confirmation(lapb->dev, reason);
 415 }
 416
 417 void lapb_connect_indication(struct lapb_cb *lapb, int reason)
 418 {
 419         if (lapb->callbacks->connect_indication)
 420                 lapb->callbacks->connect_indication(lapb->dev, reason);
 421 }
 422
 423 void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
 424 {
 425         if (lapb->callbacks->disconnect_confirmation)
 426                 lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
 427 }
 428
 429 void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
 430 {
 431         if (lapb->callbacks->disconnect_indication)
 432                 lapb->callbacks->disconnect_indication(lapb->dev, reason);
 433 }
 434
 435 int lapb_data_indication(struct lapb_cb *lapb, struct sk_buff *skb)
 436 {
 437         if (lapb->callbacks->data_indication)
 438                 return lapb->callbacks->data_indication(lapb->dev, skb);
 439
 440         kfree_skb(skb);
 441         return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
 442 }
 443
 444 int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb)
 445 {
 446         int used = 0;
 447
 448         if (lapb->callbacks->data_transmit) {
 449                 lapb->callbacks->data_transmit(lapb->dev, skb);
 450                 used = 1;
 451         }
 452
 453         return used;
 454 }
 455
 456 /* Handle device status changes. */
 457 static int lapb_device_event(struct notifier_block *this, unsigned long event,
 458                              void *ptr)
 459 {
 460         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 461         struct lapb_cb *lapb;
 462
 463         if (!net_eq(dev_net(dev), &init_net))
 464                 return NOTIFY_DONE;
 465
 466         if (dev->type != ARPHRD_X25)
 467                 return NOTIFY_DONE;
 468
 469         lapb = lapb_devtostruct(dev);
 470         if (!lapb)
 471                 return NOTIFY_DONE;
 472
 473         spin_lock_bh(&lapb->lock);
 474
 475         switch (event) {
 476         case NETDEV_UP:
 477                 lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name);
 478
 479                 if (netif_carrier_ok(dev)) {
 480                         lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev,
 481                                  dev->name);
 482                         if (lapb->mode & LAPB_DCE) {
 483                                 lapb_start_t1timer(lapb);
 484                         } else {
 485                                 if (lapb->state == LAPB_STATE_0) {
 486                                         lapb->state = LAPB_STATE_1;
 487                                         lapb_establish_data_link(lapb);
 488                                 }
 489                         }
 490                 }
 491                 break;
 492         case NETDEV_GOING_DOWN:
 493                 if (netif_carrier_ok(dev))
 494                         __lapb_disconnect_request(lapb);
 495                 break;
 496         case NETDEV_DOWN:
 497                 lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name);
 498                 lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
 499                 lapb_clear_queues(lapb);
 500                 lapb->state = LAPB_STATE_0;
 501                 lapb->n2count   = 0;
 502                 lapb_stop_t1timer(lapb);
 503                 lapb_stop_t2timer(lapb);
 504                 break;
 505         case NETDEV_CHANGE:
 506                 if (netif_carrier_ok(dev)) {
 507                         lapb_dbg(0, "(%p): Carrier detected: %s\n", dev,
 508                                  dev->name);
 509                         if (lapb->mode & LAPB_DCE) {
 510                                 lapb_start_t1timer(lapb);
 511                         } else {
 512                                 if (lapb->state == LAPB_STATE_0) {
 513                                         lapb->state = LAPB_STATE_1;
 514                                         lapb_establish_data_link(lapb);
 515                                 }
 516                         }
 517                 } else {
 518                         lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name);
 519                         lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
 520                         lapb_clear_queues(lapb);
 521                         lapb->state = LAPB_STATE_0;
 522                         lapb->n2count   = 0;
 523                         lapb_stop_t1timer(lapb);
 524                         lapb_stop_t2timer(lapb);
 525                 }
 526                 break;
 527         }
 528
 529         spin_unlock_bh(&lapb->lock);
 530         lapb_put(lapb);
 531         return NOTIFY_DONE;
 532 }
 533
 534 static struct notifier_block lapb_dev_notifier = {
 535         .notifier_call = lapb_device_event,
 536 };
 537
 538 static int __init lapb_init(void)
 539 {
 540         return register_netdevice_notifier(&lapb_dev_notifier);
 541 }
 542
 543 static void __exit lapb_exit(void)
 544 {
 545         WARN_ON(!list_empty(&lapb_list));
 546
 547         unregister_netdevice_notifier(&lapb_dev_notifier);
 548 }
 549
 550 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 551 MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
 552 MODULE_LICENSE("GPL");
 553
 554 module_init(lapb_init);
 555 module_exit(lapb_exit);