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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  LAPB release 002
0004  *
0005  *  This code REQUIRES 2.1.15 or higher/ NET3.038
0006  *
0007  *  History
0008  *  LAPB 001    Jonathan Naylor Started Coding
0009  *  LAPB 002    Jonathan Naylor New timer architecture.
0010  *  2000-10-29  Henner Eisen    lapb_data_indication() return status.
0011  */
0012 
0013 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0014 
0015 #include <linux/module.h>
0016 #include <linux/errno.h>
0017 #include <linux/types.h>
0018 #include <linux/socket.h>
0019 #include <linux/in.h>
0020 #include <linux/kernel.h>
0021 #include <linux/jiffies.h>
0022 #include <linux/timer.h>
0023 #include <linux/string.h>
0024 #include <linux/sockios.h>
0025 #include <linux/net.h>
0026 #include <linux/inet.h>
0027 #include <linux/if_arp.h>
0028 #include <linux/skbuff.h>
0029 #include <linux/slab.h>
0030 #include <net/sock.h>
0031 #include <linux/uaccess.h>
0032 #include <linux/fcntl.h>
0033 #include <linux/mm.h>
0034 #include <linux/interrupt.h>
0035 #include <linux/stat.h>
0036 #include <linux/init.h>
0037 #include <net/lapb.h>
0038 
0039 static LIST_HEAD(lapb_list);
0040 static DEFINE_RWLOCK(lapb_list_lock);
0041 
0042 /*
0043  *  Free an allocated lapb control block.
0044  */
0045 static void lapb_free_cb(struct lapb_cb *lapb)
0046 {
0047     kfree(lapb);
0048 }
0049 
0050 static __inline__ void lapb_hold(struct lapb_cb *lapb)
0051 {
0052     refcount_inc(&lapb->refcnt);
0053 }
0054 
0055 static __inline__ void lapb_put(struct lapb_cb *lapb)
0056 {
0057     if (refcount_dec_and_test(&lapb->refcnt))
0058         lapb_free_cb(lapb);
0059 }
0060 
0061 /*
0062  *  Socket removal during an interrupt is now safe.
0063  */
0064 static void __lapb_remove_cb(struct lapb_cb *lapb)
0065 {
0066     if (lapb->node.next) {
0067         list_del(&lapb->node);
0068         lapb_put(lapb);
0069     }
0070 }
0071 
0072 /*
0073  *  Add a socket to the bound sockets list.
0074  */
0075 static void __lapb_insert_cb(struct lapb_cb *lapb)
0076 {
0077     list_add(&lapb->node, &lapb_list);
0078     lapb_hold(lapb);
0079 }
0080 
0081 static struct lapb_cb *__lapb_devtostruct(struct net_device *dev)
0082 {
0083     struct lapb_cb *lapb, *use = NULL;
0084 
0085     list_for_each_entry(lapb, &lapb_list, node) {
0086         if (lapb->dev == dev) {
0087             use = lapb;
0088             break;
0089         }
0090     }
0091 
0092     if (use)
0093         lapb_hold(use);
0094 
0095     return use;
0096 }
0097 
0098 static struct lapb_cb *lapb_devtostruct(struct net_device *dev)
0099 {
0100     struct lapb_cb *rc;
0101 
0102     read_lock_bh(&lapb_list_lock);
0103     rc = __lapb_devtostruct(dev);
0104     read_unlock_bh(&lapb_list_lock);
0105 
0106     return rc;
0107 }
0108 /*
0109  *  Create an empty LAPB control block.
0110  */
0111 static struct lapb_cb *lapb_create_cb(void)
0112 {
0113     struct lapb_cb *lapb = kzalloc(sizeof(*lapb), GFP_ATOMIC);
0114 
0115     if (!lapb)
0116         goto out;
0117 
0118     skb_queue_head_init(&lapb->write_queue);
0119     skb_queue_head_init(&lapb->ack_queue);
0120 
0121     timer_setup(&lapb->t1timer, NULL, 0);
0122     timer_setup(&lapb->t2timer, NULL, 0);
0123     lapb->t1timer_running = false;
0124     lapb->t2timer_running = false;
0125 
0126     lapb->t1      = LAPB_DEFAULT_T1;
0127     lapb->t2      = LAPB_DEFAULT_T2;
0128     lapb->n2      = LAPB_DEFAULT_N2;
0129     lapb->mode    = LAPB_DEFAULT_MODE;
0130     lapb->window  = LAPB_DEFAULT_WINDOW;
0131     lapb->state   = LAPB_STATE_0;
0132 
0133     spin_lock_init(&lapb->lock);
0134     refcount_set(&lapb->refcnt, 1);
0135 out:
0136     return lapb;
0137 }
0138 
0139 int lapb_register(struct net_device *dev,
0140           const struct lapb_register_struct *callbacks)
0141 {
0142     struct lapb_cb *lapb;
0143     int rc = LAPB_BADTOKEN;
0144 
0145     write_lock_bh(&lapb_list_lock);
0146 
0147     lapb = __lapb_devtostruct(dev);
0148     if (lapb) {
0149         lapb_put(lapb);
0150         goto out;
0151     }
0152 
0153     lapb = lapb_create_cb();
0154     rc = LAPB_NOMEM;
0155     if (!lapb)
0156         goto out;
0157 
0158     lapb->dev       = dev;
0159     lapb->callbacks = callbacks;
0160 
0161     __lapb_insert_cb(lapb);
0162 
0163     lapb_start_t1timer(lapb);
0164 
0165     rc = LAPB_OK;
0166 out:
0167     write_unlock_bh(&lapb_list_lock);
0168     return rc;
0169 }
0170 EXPORT_SYMBOL(lapb_register);
0171 
0172 int lapb_unregister(struct net_device *dev)
0173 {
0174     struct lapb_cb *lapb;
0175     int rc = LAPB_BADTOKEN;
0176 
0177     write_lock_bh(&lapb_list_lock);
0178     lapb = __lapb_devtostruct(dev);
0179     if (!lapb)
0180         goto out;
0181     lapb_put(lapb);
0182 
0183     /* Wait for other refs to "lapb" to drop */
0184     while (refcount_read(&lapb->refcnt) > 2)
0185         usleep_range(1, 10);
0186 
0187     spin_lock_bh(&lapb->lock);
0188 
0189     lapb_stop_t1timer(lapb);
0190     lapb_stop_t2timer(lapb);
0191 
0192     lapb_clear_queues(lapb);
0193 
0194     spin_unlock_bh(&lapb->lock);
0195 
0196     /* Wait for running timers to stop */
0197     del_timer_sync(&lapb->t1timer);
0198     del_timer_sync(&lapb->t2timer);
0199 
0200     __lapb_remove_cb(lapb);
0201 
0202     lapb_put(lapb);
0203     rc = LAPB_OK;
0204 out:
0205     write_unlock_bh(&lapb_list_lock);
0206     return rc;
0207 }
0208 EXPORT_SYMBOL(lapb_unregister);
0209 
0210 int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms)
0211 {
0212     int rc = LAPB_BADTOKEN;
0213     struct lapb_cb *lapb = lapb_devtostruct(dev);
0214 
0215     if (!lapb)
0216         goto out;
0217 
0218     spin_lock_bh(&lapb->lock);
0219 
0220     parms->t1      = lapb->t1 / HZ;
0221     parms->t2      = lapb->t2 / HZ;
0222     parms->n2      = lapb->n2;
0223     parms->n2count = lapb->n2count;
0224     parms->state   = lapb->state;
0225     parms->window  = lapb->window;
0226     parms->mode    = lapb->mode;
0227 
0228     if (!timer_pending(&lapb->t1timer))
0229         parms->t1timer = 0;
0230     else
0231         parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;
0232 
0233     if (!timer_pending(&lapb->t2timer))
0234         parms->t2timer = 0;
0235     else
0236         parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;
0237 
0238     spin_unlock_bh(&lapb->lock);
0239     lapb_put(lapb);
0240     rc = LAPB_OK;
0241 out:
0242     return rc;
0243 }
0244 EXPORT_SYMBOL(lapb_getparms);
0245 
0246 int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
0247 {
0248     int rc = LAPB_BADTOKEN;
0249     struct lapb_cb *lapb = lapb_devtostruct(dev);
0250 
0251     if (!lapb)
0252         goto out;
0253 
0254     spin_lock_bh(&lapb->lock);
0255 
0256     rc = LAPB_INVALUE;
0257     if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1)
0258         goto out_put;
0259 
0260     if (lapb->state == LAPB_STATE_0) {
0261         if (parms->mode & LAPB_EXTENDED) {
0262             if (parms->window < 1 || parms->window > 127)
0263                 goto out_put;
0264         } else {
0265             if (parms->window < 1 || parms->window > 7)
0266                 goto out_put;
0267         }
0268         lapb->mode    = parms->mode;
0269         lapb->window  = parms->window;
0270     }
0271 
0272     lapb->t1    = parms->t1 * HZ;
0273     lapb->t2    = parms->t2 * HZ;
0274     lapb->n2    = parms->n2;
0275 
0276     rc = LAPB_OK;
0277 out_put:
0278     spin_unlock_bh(&lapb->lock);
0279     lapb_put(lapb);
0280 out:
0281     return rc;
0282 }
0283 EXPORT_SYMBOL(lapb_setparms);
0284 
0285 int lapb_connect_request(struct net_device *dev)
0286 {
0287     struct lapb_cb *lapb = lapb_devtostruct(dev);
0288     int rc = LAPB_BADTOKEN;
0289 
0290     if (!lapb)
0291         goto out;
0292 
0293     spin_lock_bh(&lapb->lock);
0294 
0295     rc = LAPB_OK;
0296     if (lapb->state == LAPB_STATE_1)
0297         goto out_put;
0298 
0299     rc = LAPB_CONNECTED;
0300     if (lapb->state == LAPB_STATE_3 || lapb->state == LAPB_STATE_4)
0301         goto out_put;
0302 
0303     lapb_establish_data_link(lapb);
0304 
0305     lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
0306     lapb->state = LAPB_STATE_1;
0307 
0308     rc = LAPB_OK;
0309 out_put:
0310     spin_unlock_bh(&lapb->lock);
0311     lapb_put(lapb);
0312 out:
0313     return rc;
0314 }
0315 EXPORT_SYMBOL(lapb_connect_request);
0316 
0317 static int __lapb_disconnect_request(struct lapb_cb *lapb)
0318 {
0319     switch (lapb->state) {
0320     case LAPB_STATE_0:
0321         return LAPB_NOTCONNECTED;
0322 
0323     case LAPB_STATE_1:
0324         lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
0325         lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
0326         lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
0327         lapb->state = LAPB_STATE_0;
0328         lapb_start_t1timer(lapb);
0329         return LAPB_NOTCONNECTED;
0330 
0331     case LAPB_STATE_2:
0332         return LAPB_OK;
0333     }
0334 
0335     lapb_clear_queues(lapb);
0336     lapb->n2count = 0;
0337     lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
0338     lapb_start_t1timer(lapb);
0339     lapb_stop_t2timer(lapb);
0340     lapb->state = LAPB_STATE_2;
0341 
0342     lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
0343     lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);
0344 
0345     return LAPB_OK;
0346 }
0347 
0348 int lapb_disconnect_request(struct net_device *dev)
0349 {
0350     struct lapb_cb *lapb = lapb_devtostruct(dev);
0351     int rc = LAPB_BADTOKEN;
0352 
0353     if (!lapb)
0354         goto out;
0355 
0356     spin_lock_bh(&lapb->lock);
0357 
0358     rc = __lapb_disconnect_request(lapb);
0359 
0360     spin_unlock_bh(&lapb->lock);
0361     lapb_put(lapb);
0362 out:
0363     return rc;
0364 }
0365 EXPORT_SYMBOL(lapb_disconnect_request);
0366 
0367 int lapb_data_request(struct net_device *dev, struct sk_buff *skb)
0368 {
0369     struct lapb_cb *lapb = lapb_devtostruct(dev);
0370     int rc = LAPB_BADTOKEN;
0371 
0372     if (!lapb)
0373         goto out;
0374 
0375     spin_lock_bh(&lapb->lock);
0376 
0377     rc = LAPB_NOTCONNECTED;
0378     if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
0379         goto out_put;
0380 
0381     skb_queue_tail(&lapb->write_queue, skb);
0382     lapb_kick(lapb);
0383     rc = LAPB_OK;
0384 out_put:
0385     spin_unlock_bh(&lapb->lock);
0386     lapb_put(lapb);
0387 out:
0388     return rc;
0389 }
0390 EXPORT_SYMBOL(lapb_data_request);
0391 
0392 int lapb_data_received(struct net_device *dev, struct sk_buff *skb)
0393 {
0394     struct lapb_cb *lapb = lapb_devtostruct(dev);
0395     int rc = LAPB_BADTOKEN;
0396 
0397     if (lapb) {
0398         spin_lock_bh(&lapb->lock);
0399         lapb_data_input(lapb, skb);
0400         spin_unlock_bh(&lapb->lock);
0401         lapb_put(lapb);
0402         rc = LAPB_OK;
0403     }
0404 
0405     return rc;
0406 }
0407 EXPORT_SYMBOL(lapb_data_received);
0408 
0409 void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
0410 {
0411     if (lapb->callbacks->connect_confirmation)
0412         lapb->callbacks->connect_confirmation(lapb->dev, reason);
0413 }
0414 
0415 void lapb_connect_indication(struct lapb_cb *lapb, int reason)
0416 {
0417     if (lapb->callbacks->connect_indication)
0418         lapb->callbacks->connect_indication(lapb->dev, reason);
0419 }
0420 
0421 void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
0422 {
0423     if (lapb->callbacks->disconnect_confirmation)
0424         lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
0425 }
0426 
0427 void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
0428 {
0429     if (lapb->callbacks->disconnect_indication)
0430         lapb->callbacks->disconnect_indication(lapb->dev, reason);
0431 }
0432 
0433 int lapb_data_indication(struct lapb_cb *lapb, struct sk_buff *skb)
0434 {
0435     if (lapb->callbacks->data_indication)
0436         return lapb->callbacks->data_indication(lapb->dev, skb);
0437 
0438     kfree_skb(skb);
0439     return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
0440 }
0441 
0442 int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb)
0443 {
0444     int used = 0;
0445 
0446     if (lapb->callbacks->data_transmit) {
0447         lapb->callbacks->data_transmit(lapb->dev, skb);
0448         used = 1;
0449     }
0450 
0451     return used;
0452 }
0453 
0454 /* Handle device status changes. */
0455 static int lapb_device_event(struct notifier_block *this, unsigned long event,
0456                  void *ptr)
0457 {
0458     struct net_device *dev = netdev_notifier_info_to_dev(ptr);
0459     struct lapb_cb *lapb;
0460 
0461     if (!net_eq(dev_net(dev), &init_net))
0462         return NOTIFY_DONE;
0463 
0464     if (dev->type != ARPHRD_X25)
0465         return NOTIFY_DONE;
0466 
0467     lapb = lapb_devtostruct(dev);
0468     if (!lapb)
0469         return NOTIFY_DONE;
0470 
0471     spin_lock_bh(&lapb->lock);
0472 
0473     switch (event) {
0474     case NETDEV_UP:
0475         lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name);
0476 
0477         if (netif_carrier_ok(dev)) {
0478             lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev,
0479                  dev->name);
0480             if (lapb->mode & LAPB_DCE) {
0481                 lapb_start_t1timer(lapb);
0482             } else {
0483                 if (lapb->state == LAPB_STATE_0) {
0484                     lapb->state = LAPB_STATE_1;
0485                     lapb_establish_data_link(lapb);
0486                 }
0487             }
0488         }
0489         break;
0490     case NETDEV_GOING_DOWN:
0491         if (netif_carrier_ok(dev))
0492             __lapb_disconnect_request(lapb);
0493         break;
0494     case NETDEV_DOWN:
0495         lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name);
0496         lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
0497         lapb_clear_queues(lapb);
0498         lapb->state = LAPB_STATE_0;
0499         lapb->n2count   = 0;
0500         lapb_stop_t1timer(lapb);
0501         lapb_stop_t2timer(lapb);
0502         break;
0503     case NETDEV_CHANGE:
0504         if (netif_carrier_ok(dev)) {
0505             lapb_dbg(0, "(%p): Carrier detected: %s\n", dev,
0506                  dev->name);
0507             if (lapb->mode & LAPB_DCE) {
0508                 lapb_start_t1timer(lapb);
0509             } else {
0510                 if (lapb->state == LAPB_STATE_0) {
0511                     lapb->state = LAPB_STATE_1;
0512                     lapb_establish_data_link(lapb);
0513                 }
0514             }
0515         } else {
0516             lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name);
0517             lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
0518             lapb_clear_queues(lapb);
0519             lapb->state = LAPB_STATE_0;
0520             lapb->n2count   = 0;
0521             lapb_stop_t1timer(lapb);
0522             lapb_stop_t2timer(lapb);
0523         }
0524         break;
0525     }
0526 
0527     spin_unlock_bh(&lapb->lock);
0528     lapb_put(lapb);
0529     return NOTIFY_DONE;
0530 }
0531 
0532 static struct notifier_block lapb_dev_notifier = {
0533     .notifier_call = lapb_device_event,
0534 };
0535 
0536 static int __init lapb_init(void)
0537 {
0538     return register_netdevice_notifier(&lapb_dev_notifier);
0539 }
0540 
0541 static void __exit lapb_exit(void)
0542 {
0543     WARN_ON(!list_empty(&lapb_list));
0544 
0545     unregister_netdevice_notifier(&lapb_dev_notifier);
0546 }
0547 
0548 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
0549 MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
0550 MODULE_LICENSE("GPL");
0551 
0552 module_init(lapb_init);
0553 module_exit(lapb_exit);
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