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  */
lapb_free_cb(struct lapb_cb * lapb)45 static void lapb_free_cb(struct lapb_cb *lapb)
46 {
47 	kfree(lapb);
48 }
49 
lapb_hold(struct lapb_cb * lapb)50 static __inline__ void lapb_hold(struct lapb_cb *lapb)
51 {
52 	refcount_inc(&lapb->refcnt);
53 }
54 
lapb_put(struct lapb_cb * lapb)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  */
__lapb_remove_cb(struct lapb_cb * lapb)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  */
__lapb_insert_cb(struct lapb_cb * lapb)75 static void __lapb_insert_cb(struct lapb_cb *lapb)
76 {
77 	list_add(&lapb->node, &lapb_list);
78 	lapb_hold(lapb);
79 }
80 
__lapb_devtostruct(struct net_device * dev)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 
lapb_devtostruct(struct net_device * dev)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  */
lapb_create_cb(void)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 
126 	lapb->t1      = LAPB_DEFAULT_T1;
127 	lapb->t2      = LAPB_DEFAULT_T2;
128 	lapb->n2      = LAPB_DEFAULT_N2;
129 	lapb->mode    = LAPB_DEFAULT_MODE;
130 	lapb->window  = LAPB_DEFAULT_WINDOW;
131 	lapb->state   = LAPB_STATE_0;
132 	refcount_set(&lapb->refcnt, 1);
133 out:
134 	return lapb;
135 }
136 
lapb_register(struct net_device * dev,const struct lapb_register_struct * callbacks)137 int lapb_register(struct net_device *dev,
138 		  const struct lapb_register_struct *callbacks)
139 {
140 	struct lapb_cb *lapb;
141 	int rc = LAPB_BADTOKEN;
142 
143 	write_lock_bh(&lapb_list_lock);
144 
145 	lapb = __lapb_devtostruct(dev);
146 	if (lapb) {
147 		lapb_put(lapb);
148 		goto out;
149 	}
150 
151 	lapb = lapb_create_cb();
152 	rc = LAPB_NOMEM;
153 	if (!lapb)
154 		goto out;
155 
156 	lapb->dev       = dev;
157 	lapb->callbacks = callbacks;
158 
159 	__lapb_insert_cb(lapb);
160 
161 	lapb_start_t1timer(lapb);
162 
163 	rc = LAPB_OK;
164 out:
165 	write_unlock_bh(&lapb_list_lock);
166 	return rc;
167 }
168 EXPORT_SYMBOL(lapb_register);
169 
lapb_unregister(struct net_device * dev)170 int lapb_unregister(struct net_device *dev)
171 {
172 	struct lapb_cb *lapb;
173 	int rc = LAPB_BADTOKEN;
174 
175 	write_lock_bh(&lapb_list_lock);
176 	lapb = __lapb_devtostruct(dev);
177 	if (!lapb)
178 		goto out;
179 	lapb_put(lapb);
180 
181 	lapb_stop_t1timer(lapb);
182 	lapb_stop_t2timer(lapb);
183 
184 	lapb_clear_queues(lapb);
185 
186 	__lapb_remove_cb(lapb);
187 
188 	lapb_put(lapb);
189 	rc = LAPB_OK;
190 out:
191 	write_unlock_bh(&lapb_list_lock);
192 	return rc;
193 }
194 EXPORT_SYMBOL(lapb_unregister);
195 
lapb_getparms(struct net_device * dev,struct lapb_parms_struct * parms)196 int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms)
197 {
198 	int rc = LAPB_BADTOKEN;
199 	struct lapb_cb *lapb = lapb_devtostruct(dev);
200 
201 	if (!lapb)
202 		goto out;
203 
204 	parms->t1      = lapb->t1 / HZ;
205 	parms->t2      = lapb->t2 / HZ;
206 	parms->n2      = lapb->n2;
207 	parms->n2count = lapb->n2count;
208 	parms->state   = lapb->state;
209 	parms->window  = lapb->window;
210 	parms->mode    = lapb->mode;
211 
212 	if (!timer_pending(&lapb->t1timer))
213 		parms->t1timer = 0;
214 	else
215 		parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;
216 
217 	if (!timer_pending(&lapb->t2timer))
218 		parms->t2timer = 0;
219 	else
220 		parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;
221 
222 	lapb_put(lapb);
223 	rc = LAPB_OK;
224 out:
225 	return rc;
226 }
227 EXPORT_SYMBOL(lapb_getparms);
228 
lapb_setparms(struct net_device * dev,struct lapb_parms_struct * parms)229 int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
230 {
231 	int rc = LAPB_BADTOKEN;
232 	struct lapb_cb *lapb = lapb_devtostruct(dev);
233 
234 	if (!lapb)
235 		goto out;
236 
237 	rc = LAPB_INVALUE;
238 	if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1)
239 		goto out_put;
240 
241 	if (lapb->state == LAPB_STATE_0) {
242 		if (parms->mode & LAPB_EXTENDED) {
243 			if (parms->window < 1 || parms->window > 127)
244 				goto out_put;
245 		} else {
246 			if (parms->window < 1 || parms->window > 7)
247 				goto out_put;
248 		}
249 		lapb->mode    = parms->mode;
250 		lapb->window  = parms->window;
251 	}
252 
253 	lapb->t1    = parms->t1 * HZ;
254 	lapb->t2    = parms->t2 * HZ;
255 	lapb->n2    = parms->n2;
256 
257 	rc = LAPB_OK;
258 out_put:
259 	lapb_put(lapb);
260 out:
261 	return rc;
262 }
263 EXPORT_SYMBOL(lapb_setparms);
264 
lapb_connect_request(struct net_device * dev)265 int lapb_connect_request(struct net_device *dev)
266 {
267 	struct lapb_cb *lapb = lapb_devtostruct(dev);
268 	int rc = LAPB_BADTOKEN;
269 
270 	if (!lapb)
271 		goto out;
272 
273 	rc = LAPB_OK;
274 	if (lapb->state == LAPB_STATE_1)
275 		goto out_put;
276 
277 	rc = LAPB_CONNECTED;
278 	if (lapb->state == LAPB_STATE_3 || lapb->state == LAPB_STATE_4)
279 		goto out_put;
280 
281 	lapb_establish_data_link(lapb);
282 
283 	lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
284 	lapb->state = LAPB_STATE_1;
285 
286 	rc = LAPB_OK;
287 out_put:
288 	lapb_put(lapb);
289 out:
290 	return rc;
291 }
292 EXPORT_SYMBOL(lapb_connect_request);
293 
lapb_disconnect_request(struct net_device * dev)294 int lapb_disconnect_request(struct net_device *dev)
295 {
296 	struct lapb_cb *lapb = lapb_devtostruct(dev);
297 	int rc = LAPB_BADTOKEN;
298 
299 	if (!lapb)
300 		goto out;
301 
302 	switch (lapb->state) {
303 	case LAPB_STATE_0:
304 		rc = LAPB_NOTCONNECTED;
305 		goto out_put;
306 
307 	case LAPB_STATE_1:
308 		lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
309 		lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
310 		lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
311 		lapb->state = LAPB_STATE_0;
312 		lapb_start_t1timer(lapb);
313 		rc = LAPB_NOTCONNECTED;
314 		goto out_put;
315 
316 	case LAPB_STATE_2:
317 		rc = LAPB_OK;
318 		goto out_put;
319 	}
320 
321 	lapb_clear_queues(lapb);
322 	lapb->n2count = 0;
323 	lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
324 	lapb_start_t1timer(lapb);
325 	lapb_stop_t2timer(lapb);
326 	lapb->state = LAPB_STATE_2;
327 
328 	lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
329 	lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);
330 
331 	rc = LAPB_OK;
332 out_put:
333 	lapb_put(lapb);
334 out:
335 	return rc;
336 }
337 EXPORT_SYMBOL(lapb_disconnect_request);
338 
lapb_data_request(struct net_device * dev,struct sk_buff * skb)339 int lapb_data_request(struct net_device *dev, struct sk_buff *skb)
340 {
341 	struct lapb_cb *lapb = lapb_devtostruct(dev);
342 	int rc = LAPB_BADTOKEN;
343 
344 	if (!lapb)
345 		goto out;
346 
347 	rc = LAPB_NOTCONNECTED;
348 	if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
349 		goto out_put;
350 
351 	skb_queue_tail(&lapb->write_queue, skb);
352 	lapb_kick(lapb);
353 	rc = LAPB_OK;
354 out_put:
355 	lapb_put(lapb);
356 out:
357 	return rc;
358 }
359 EXPORT_SYMBOL(lapb_data_request);
360 
lapb_data_received(struct net_device * dev,struct sk_buff * skb)361 int lapb_data_received(struct net_device *dev, struct sk_buff *skb)
362 {
363 	struct lapb_cb *lapb = lapb_devtostruct(dev);
364 	int rc = LAPB_BADTOKEN;
365 
366 	if (lapb) {
367 		lapb_data_input(lapb, skb);
368 		lapb_put(lapb);
369 		rc = LAPB_OK;
370 	}
371 
372 	return rc;
373 }
374 EXPORT_SYMBOL(lapb_data_received);
375 
lapb_connect_confirmation(struct lapb_cb * lapb,int reason)376 void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
377 {
378 	if (lapb->callbacks->connect_confirmation)
379 		lapb->callbacks->connect_confirmation(lapb->dev, reason);
380 }
381 
lapb_connect_indication(struct lapb_cb * lapb,int reason)382 void lapb_connect_indication(struct lapb_cb *lapb, int reason)
383 {
384 	if (lapb->callbacks->connect_indication)
385 		lapb->callbacks->connect_indication(lapb->dev, reason);
386 }
387 
lapb_disconnect_confirmation(struct lapb_cb * lapb,int reason)388 void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
389 {
390 	if (lapb->callbacks->disconnect_confirmation)
391 		lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
392 }
393 
lapb_disconnect_indication(struct lapb_cb * lapb,int reason)394 void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
395 {
396 	if (lapb->callbacks->disconnect_indication)
397 		lapb->callbacks->disconnect_indication(lapb->dev, reason);
398 }
399 
lapb_data_indication(struct lapb_cb * lapb,struct sk_buff * skb)400 int lapb_data_indication(struct lapb_cb *lapb, struct sk_buff *skb)
401 {
402 	if (lapb->callbacks->data_indication)
403 		return lapb->callbacks->data_indication(lapb->dev, skb);
404 
405 	kfree_skb(skb);
406 	return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
407 }
408 
lapb_data_transmit(struct lapb_cb * lapb,struct sk_buff * skb)409 int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb)
410 {
411 	int used = 0;
412 
413 	if (lapb->callbacks->data_transmit) {
414 		lapb->callbacks->data_transmit(lapb->dev, skb);
415 		used = 1;
416 	}
417 
418 	return used;
419 }
420 
lapb_init(void)421 static int __init lapb_init(void)
422 {
423 	return 0;
424 }
425 
lapb_exit(void)426 static void __exit lapb_exit(void)
427 {
428 	WARN_ON(!list_empty(&lapb_list));
429 }
430 
431 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
432 MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
433 MODULE_LICENSE("GPL");
434 
435 module_init(lapb_init);
436 module_exit(lapb_exit);
437