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#include <linux/errno.h>
24#include <linux/types.h>
25#include <linux/socket.h>
26#include <linux/in.h>
27#include <linux/kernel.h>
28#include <linux/string.h>
29#include <linux/net.h>
30#include <linux/inet.h>
31#include <linux/netdevice.h>
32#include <linux/if_arp.h>
33#include <linux/skbuff.h>
34#include <net/sock.h>
35#include <asm/system.h>
36#include <asm/uaccess.h>
37#include <linux/mm.h>
38#include <linux/interrupt.h>
39#include <linux/notifier.h>
40#include <linux/stat.h>
41#include <linux/netfilter.h>
42#include <linux/module.h>
43#include <linux/lapb.h>
44#include <linux/init.h>
45
46#include <net/x25device.h>
47
48static char bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
49
50/* If this number is made larger, check that the temporary string buffer
51 * in lapbeth_new_device is large enough to store the probe device name.*/
52#define MAXLAPBDEV 100
53
54struct lapbethdev {
55	struct list_head	node;
56	struct net_device	*ethdev;	/* link to ethernet device */
57	struct net_device	*axdev;		/* lapbeth device (lapb#) */
58	struct net_device_stats stats;		/* some statistics */
59};
60
61static struct list_head lapbeth_devices = LIST_HEAD_INIT(lapbeth_devices);
62
63/* ------------------------------------------------------------------------ */
64
65/*
66 *	Get the LAPB device for the ethernet device
67 */
68static 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
79static __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 */
89static 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 ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
95		return NET_RX_DROP;
96
97	if (!pskb_may_pull(skb, 2))
98		goto drop;
99
100	rcu_read_lock();
101	lapbeth = lapbeth_get_x25_dev(dev);
102	if (!lapbeth)
103		goto drop_unlock;
104	if (!netif_running(lapbeth->axdev))
105		goto drop_unlock;
106
107	lapbeth->stats.rx_packets++;
108
109	len = skb->data[0] + skb->data[1] * 256;
110	lapbeth->stats.rx_bytes += len;
111
112	skb_pull(skb, 2);	/* Remove the length bytes */
113	skb_trim(skb, len);	/* Set the length of the data */
114
115	if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
116		printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
117		goto drop_unlock;
118	}
119out:
120	rcu_read_unlock();
121	return 0;
122drop_unlock:
123	kfree_skb(skb);
124	goto out;
125drop:
126	kfree_skb(skb);
127	return 0;
128}
129
130static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
131{
132	unsigned char *ptr;
133
134	skb_push(skb, 1);
135
136	if (skb_cow(skb, 1))
137		return NET_RX_DROP;
138
139	ptr  = skb->data;
140	*ptr = 0x00;
141
142	skb->protocol = x25_type_trans(skb, dev);
143	skb->dev->last_rx = jiffies;
144	return netif_rx(skb);
145}
146
147/*
148 *	Send a LAPB frame via an ethernet interface
149 */
150static int lapbeth_xmit(struct sk_buff *skb, struct net_device *dev)
151{
152	int err = -ENODEV;
153
154	/*
155	 * Just to be *really* sure not to send anything if the interface
156	 * is down, the ethernet device may have gone.
157	 */
158	if (!netif_running(dev)) {
159		goto drop;
160	}
161
162	switch (skb->data[0]) {
163	case 0x00:
164		err = 0;
165		break;
166	case 0x01:
167		if ((err = lapb_connect_request(dev)) != LAPB_OK)
168			printk(KERN_ERR "lapbeth: lapb_connect_request "
169			       "error: %d\n", err);
170		goto drop_ok;
171	case 0x02:
172		if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
173			printk(KERN_ERR "lapbeth: lapb_disconnect_request "
174			       "err: %d\n", err);
175		/* Fall thru */
176	default:
177		goto drop_ok;
178	}
179
180	skb_pull(skb, 1);
181
182	if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
183		printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
184		err = -ENOMEM;
185		goto drop;
186	}
187	err = 0;
188out:
189	return err;
190drop_ok:
191	err = 0;
192drop:
193	kfree_skb(skb);
194	goto out;
195}
196
197static 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	lapbeth->stats.tx_packets++;
212	lapbeth->stats.tx_bytes += size;
213
214	skb->dev = dev = lapbeth->ethdev;
215
216	dev->hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
217
218	dev_queue_xmit(skb);
219}
220
221static void lapbeth_connected(struct net_device *dev, int reason)
222{
223	unsigned char *ptr;
224	struct sk_buff *skb = dev_alloc_skb(1);
225
226	if (!skb) {
227		printk(KERN_ERR "lapbeth: out of memory\n");
228		return;
229	}
230
231	ptr  = skb_put(skb, 1);
232	*ptr = 0x01;
233
234	skb->protocol = x25_type_trans(skb, dev);
235	skb->dev->last_rx = jiffies;
236	netif_rx(skb);
237}
238
239static void lapbeth_disconnected(struct net_device *dev, int reason)
240{
241	unsigned char *ptr;
242	struct sk_buff *skb = dev_alloc_skb(1);
243
244	if (!skb) {
245		printk(KERN_ERR "lapbeth: out of memory\n");
246		return;
247	}
248
249	ptr  = skb_put(skb, 1);
250	*ptr = 0x02;
251
252	skb->protocol = x25_type_trans(skb, dev);
253	skb->dev->last_rx = jiffies;
254	netif_rx(skb);
255}
256
257/*
258 *	Statistics
259 */
260static struct net_device_stats *lapbeth_get_stats(struct net_device *dev)
261{
262	struct lapbethdev *lapbeth = netdev_priv(dev);
263	return &lapbeth->stats;
264}
265
266/*
267 *	Set AX.25 callsign
268 */
269static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
270{
271	struct sockaddr *sa = addr;
272	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
273	return 0;
274}
275
276
277static struct lapb_register_struct lapbeth_callbacks = {
278	.connect_confirmation    = lapbeth_connected,
279	.connect_indication      = lapbeth_connected,
280	.disconnect_confirmation = lapbeth_disconnected,
281	.disconnect_indication   = lapbeth_disconnected,
282	.data_indication         = lapbeth_data_indication,
283	.data_transmit           = lapbeth_data_transmit,
284
285};
286
287/*
288 * open/close a device
289 */
290static int lapbeth_open(struct net_device *dev)
291{
292	int err;
293
294	if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
295		printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
296		return -ENODEV;
297	}
298
299	netif_start_queue(dev);
300	return 0;
301}
302
303static int lapbeth_close(struct net_device *dev)
304{
305	int err;
306
307	netif_stop_queue(dev);
308
309	if ((err = lapb_unregister(dev)) != LAPB_OK)
310		printk(KERN_ERR "lapbeth: lapb_unregister error - %d\n", err);
311
312	return 0;
313}
314
315/* ------------------------------------------------------------------------ */
316
317static void lapbeth_setup(struct net_device *dev)
318{
319	dev->hard_start_xmit = lapbeth_xmit;
320	dev->open	     = lapbeth_open;
321	dev->stop	     = lapbeth_close;
322	dev->destructor	     = free_netdev;
323	dev->set_mac_address = lapbeth_set_mac_address;
324	dev->get_stats	     = lapbeth_get_stats;
325	dev->type            = ARPHRD_X25;
326	dev->hard_header_len = 3;
327	dev->mtu             = 1000;
328	dev->addr_len        = 0;
329	SET_MODULE_OWNER(dev);
330}
331
332/*
333 *	Setup a new device.
334 */
335static int lapbeth_new_device(struct net_device *dev)
336{
337	struct net_device *ndev;
338	struct lapbethdev *lapbeth;
339	int rc = -ENOMEM;
340
341	ASSERT_RTNL();
342
343	ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
344			   lapbeth_setup);
345	if (!ndev)
346		goto out;
347
348	lapbeth = netdev_priv(ndev);
349	lapbeth->axdev = ndev;
350
351	dev_hold(dev);
352	lapbeth->ethdev = dev;
353
354	rc = dev_alloc_name(ndev, ndev->name);
355	if (rc < 0)
356		goto fail;
357
358	rc = -EIO;
359	if (register_netdevice(ndev))
360		goto fail;
361
362	list_add_rcu(&lapbeth->node, &lapbeth_devices);
363	rc = 0;
364out:
365	return rc;
366fail:
367	dev_put(dev);
368	free_netdev(ndev);
369	kfree(lapbeth);
370	goto out;
371}
372
373/*
374 *	Free a lapb network device.
375 */
376static void lapbeth_free_device(struct lapbethdev *lapbeth)
377{
378	dev_put(lapbeth->ethdev);
379	list_del_rcu(&lapbeth->node);
380	unregister_netdevice(lapbeth->axdev);
381}
382
383/*
384 *	Handle device status changes.
385 *
386 * Called from notifier with RTNL held.
387 */
388static int lapbeth_device_event(struct notifier_block *this,
389				unsigned long event, void *ptr)
390{
391	struct lapbethdev *lapbeth;
392	struct net_device *dev = ptr;
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
422static struct packet_type lapbeth_packet_type = {
423	.type = __constant_htons(ETH_P_DEC),
424	.func = lapbeth_rcv,
425};
426
427static struct notifier_block lapbeth_dev_notifier = {
428	.notifier_call = lapbeth_device_event,
429};
430
431static char banner[] __initdata = KERN_INFO "LAPB Ethernet driver version 0.02\n";
432
433static int __init lapbeth_init_driver(void)
434{
435	dev_add_pack(&lapbeth_packet_type);
436
437	register_netdevice_notifier(&lapbeth_dev_notifier);
438
439	printk(banner);
440
441	return 0;
442}
443module_init(lapbeth_init_driver);
444
445static void __exit lapbeth_cleanup_driver(void)
446{
447	struct lapbethdev *lapbeth;
448	struct list_head *entry, *tmp;
449
450	dev_remove_pack(&lapbeth_packet_type);
451	unregister_netdevice_notifier(&lapbeth_dev_notifier);
452
453	rtnl_lock();
454	list_for_each_safe(entry, tmp, &lapbeth_devices) {
455		lapbeth = list_entry(entry, struct lapbethdev, node);
456
457		unregister_netdevice(lapbeth->axdev);
458	}
459	rtnl_unlock();
460}
461module_exit(lapbeth_cleanup_driver);
462
463MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
464MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
465MODULE_LICENSE("GPL");
466