xref: /kernel/linux/linux-5.10/net/lapb/lapb_iface.c (revision 8c2ecf20) 
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
39static LIST_HEAD(lapb_list);
40static DEFINE_RWLOCK(lapb_list_lock);
41
42/*
43 *	Free an allocated lapb control block.
44 */
45static void lapb_free_cb(struct lapb_cb *lapb)
46{
47	kfree(lapb);
48}
49
50static __inline__ void lapb_hold(struct lapb_cb *lapb)
51{
52	refcount_inc(&lapb->refcnt);
53}
54
55static __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 */
64static 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 */
75static void __lapb_insert_cb(struct lapb_cb *lapb)
76{
77	list_add(&lapb->node, &lapb_list);
78	lapb_hold(lapb);
79}
80
81static 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
100static 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 */
113static 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);
133out:
134	return lapb;
135}
136
137int 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;
164out:
165	write_unlock_bh(&lapb_list_lock);
166	return rc;
167}
168EXPORT_SYMBOL(lapb_register);
169
170int 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;
190out:
191	write_unlock_bh(&lapb_list_lock);
192	return rc;
193}
194EXPORT_SYMBOL(lapb_unregister);
195
196int 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;
224out:
225	return rc;
226}
227EXPORT_SYMBOL(lapb_getparms);
228
229int 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;
258out_put:
259	lapb_put(lapb);
260out:
261	return rc;
262}
263EXPORT_SYMBOL(lapb_setparms);
264
265int 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;
287out_put:
288	lapb_put(lapb);
289out:
290	return rc;
291}
292EXPORT_SYMBOL(lapb_connect_request);
293
294int 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;
332out_put:
333	lapb_put(lapb);
334out:
335	return rc;
336}
337EXPORT_SYMBOL(lapb_disconnect_request);
338
339int 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;
354out_put:
355	lapb_put(lapb);
356out:
357	return rc;
358}
359EXPORT_SYMBOL(lapb_data_request);
360
361int 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}
374EXPORT_SYMBOL(lapb_data_received);
375
376void 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
382void 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
388void 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
394void 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
400int 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
409int 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
421static int __init lapb_init(void)
422{
423	return 0;
424}
425
426static void __exit lapb_exit(void)
427{
428	WARN_ON(!list_empty(&lapb_list));
429}
430
431MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
432MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
433MODULE_LICENSE("GPL");
434
435module_init(lapb_init);
436module_exit(lapb_exit);
437