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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/errno.h>
26#include <linux/types.h>
27#include <linux/socket.h>
28#include <linux/in.h>
29#include <linux/slab.h>
30#include <linux/kernel.h>
31#include <linux/string.h>
32#include <linux/net.h>
33#include <linux/inet.h>
34#include <linux/netdevice.h>
35#include <linux/if_arp.h>
36#include <linux/skbuff.h>
37#include <net/sock.h>
38#include <asm/uaccess.h>
39#include <linux/mm.h>
40#include <linux/interrupt.h>
41#include <linux/notifier.h>
42#include <linux/stat.h>
43#include <linux/netfilter.h>
44#include <linux/module.h>
45#include <linux/lapb.h>
46#include <linux/init.h>
47
48#include <net/x25device.h>
49
50static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
51
52/* If this number is made larger, check that the temporary string buffer
53 * in lapbeth_new_device is large enough to store the probe device name.*/
54#define MAXLAPBDEV 100
55
56struct lapbethdev {
57	struct list_head	node;
58	struct net_device	*ethdev;	/* link to ethernet device */
59	struct net_device	*axdev;		/* lapbeth device (lapb#) */
60};
61
62static LIST_HEAD(lapbeth_devices);
63
64/* ------------------------------------------------------------------------ */
65
66/*
67 *	Get the LAPB device for the ethernet device
68 */
69static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
70{
71	struct lapbethdev *lapbeth;
72
73	list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
74		if (lapbeth->ethdev == dev)
75			return lapbeth;
76	}
77	return NULL;
78}
79
80static __inline__ int dev_is_ethdev(struct net_device *dev)
81{
82	return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
83}
84
85/* ------------------------------------------------------------------------ */
86
87/*
88 *	Receive a LAPB frame via an ethernet interface.
89 */
90static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
91{
92	int len, err;
93	struct lapbethdev *lapbeth;
94
95	if (dev_net(dev) != &init_net)
96		goto drop;
97
98	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
99		return NET_RX_DROP;
100
101	if (!pskb_may_pull(skb, 2))
102		goto drop;
103
104	rcu_read_lock();
105	lapbeth = lapbeth_get_x25_dev(dev);
106	if (!lapbeth)
107		goto drop_unlock;
108	if (!netif_running(lapbeth->axdev))
109		goto drop_unlock;
110
111	len = skb->data[0] + skb->data[1] * 256;
112	dev->stats.rx_packets++;
113	dev->stats.rx_bytes += len;
114
115	skb_pull(skb, 2);	/* Remove the length bytes */
116	skb_trim(skb, len);	/* Set the length of the data */
117
118	if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
119		printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
120		goto drop_unlock;
121	}
122out:
123	rcu_read_unlock();
124	return 0;
125drop_unlock:
126	kfree_skb(skb);
127	goto out;
128drop:
129	kfree_skb(skb);
130	return 0;
131}
132
133static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
134{
135	unsigned char *ptr;
136
137	skb_push(skb, 1);
138
139	if (skb_cow(skb, 1))
140		return NET_RX_DROP;
141
142	ptr  = skb->data;
143	*ptr = X25_IFACE_DATA;
144
145	skb->protocol = x25_type_trans(skb, dev);
146	return netif_rx(skb);
147}
148
149/*
150 *	Send a LAPB frame via an ethernet interface
151 */
152static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
153				      struct net_device *dev)
154{
155	int err;
156
157	/*
158	 * Just to be *really* sure not to send anything if the interface
159	 * is down, the ethernet device may have gone.
160	 */
161	if (!netif_running(dev))
162		goto drop;
163
164	switch (skb->data[0]) {
165	case X25_IFACE_DATA:
166		break;
167	case X25_IFACE_CONNECT:
168		if ((err = lapb_connect_request(dev)) != LAPB_OK)
169			pr_err("lapb_connect_request error: %d\n", err);
170		goto drop;
171	case X25_IFACE_DISCONNECT:
172		if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
173			pr_err("lapb_disconnect_request err: %d\n", err);
174		/* Fall thru */
175	default:
176		goto drop;
177	}
178
179	skb_pull(skb, 1);
180
181	if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
182		pr_err("lapb_data_request error - %d\n", err);
183		goto drop;
184	}
185out:
186	return NETDEV_TX_OK;
187drop:
188	kfree_skb(skb);
189	goto out;
190}
191
192static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
193{
194	struct lapbethdev *lapbeth = netdev_priv(ndev);
195	unsigned char *ptr;
196	struct net_device *dev;
197	int size = skb->len;
198
199	skb->protocol = htons(ETH_P_X25);
200
201	ptr = skb_push(skb, 2);
202
203	*ptr++ = size % 256;
204	*ptr++ = size / 256;
205
206	ndev->stats.tx_packets++;
207	ndev->stats.tx_bytes += size;
208
209	skb->dev = dev = lapbeth->ethdev;
210
211	dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
212
213	dev_queue_xmit(skb);
214}
215
216static void lapbeth_connected(struct net_device *dev, int reason)
217{
218	unsigned char *ptr;
219	struct sk_buff *skb = dev_alloc_skb(1);
220
221	if (!skb) {
222		pr_err("out of memory\n");
223		return;
224	}
225
226	ptr  = skb_put(skb, 1);
227	*ptr = X25_IFACE_CONNECT;
228
229	skb->protocol = x25_type_trans(skb, dev);
230	netif_rx(skb);
231}
232
233static void lapbeth_disconnected(struct net_device *dev, int reason)
234{
235	unsigned char *ptr;
236	struct sk_buff *skb = dev_alloc_skb(1);
237
238	if (!skb) {
239		pr_err("out of memory\n");
240		return;
241	}
242
243	ptr  = skb_put(skb, 1);
244	*ptr = X25_IFACE_DISCONNECT;
245
246	skb->protocol = x25_type_trans(skb, dev);
247	netif_rx(skb);
248}
249
250/*
251 *	Set AX.25 callsign
252 */
253static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
254{
255	struct sockaddr *sa = addr;
256	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
257	return 0;
258}
259
260
261static const struct lapb_register_struct lapbeth_callbacks = {
262	.connect_confirmation    = lapbeth_connected,
263	.connect_indication      = lapbeth_connected,
264	.disconnect_confirmation = lapbeth_disconnected,
265	.disconnect_indication   = lapbeth_disconnected,
266	.data_indication         = lapbeth_data_indication,
267	.data_transmit           = lapbeth_data_transmit,
268};
269
270/*
271 * open/close a device
272 */
273static int lapbeth_open(struct net_device *dev)
274{
275	int err;
276
277	if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
278		pr_err("lapb_register error: %d\n", err);
279		return -ENODEV;
280	}
281
282	netif_start_queue(dev);
283	return 0;
284}
285
286static int lapbeth_close(struct net_device *dev)
287{
288	int err;
289
290	netif_stop_queue(dev);
291
292	if ((err = lapb_unregister(dev)) != LAPB_OK)
293		pr_err("lapb_unregister error: %d\n", err);
294
295	return 0;
296}
297
298/* ------------------------------------------------------------------------ */
299
300static const struct net_device_ops lapbeth_netdev_ops = {
301	.ndo_open	     = lapbeth_open,
302	.ndo_stop	     = lapbeth_close,
303	.ndo_start_xmit	     = lapbeth_xmit,
304	.ndo_set_mac_address = lapbeth_set_mac_address,
305};
306
307static void lapbeth_setup(struct net_device *dev)
308{
309	dev->netdev_ops	     = &lapbeth_netdev_ops;
310	dev->destructor	     = free_netdev;
311	dev->type            = ARPHRD_X25;
312	dev->hard_header_len = 3;
313	dev->mtu             = 1000;
314	dev->addr_len        = 0;
315}
316
317/*
318 *	Setup a new device.
319 */
320static int lapbeth_new_device(struct net_device *dev)
321{
322	struct net_device *ndev;
323	struct lapbethdev *lapbeth;
324	int rc = -ENOMEM;
325
326	ASSERT_RTNL();
327
328	ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
329			   lapbeth_setup);
330	if (!ndev)
331		goto out;
332
333	lapbeth = netdev_priv(ndev);
334	lapbeth->axdev = ndev;
335
336	dev_hold(dev);
337	lapbeth->ethdev = dev;
338
339	rc = -EIO;
340	if (register_netdevice(ndev))
341		goto fail;
342
343	list_add_rcu(&lapbeth->node, &lapbeth_devices);
344	rc = 0;
345out:
346	return rc;
347fail:
348	dev_put(dev);
349	free_netdev(ndev);
350	kfree(lapbeth);
351	goto out;
352}
353
354/*
355 *	Free a lapb network device.
356 */
357static void lapbeth_free_device(struct lapbethdev *lapbeth)
358{
359	dev_put(lapbeth->ethdev);
360	list_del_rcu(&lapbeth->node);
361	unregister_netdevice(lapbeth->axdev);
362}
363
364/*
365 *	Handle device status changes.
366 *
367 * Called from notifier with RTNL held.
368 */
369static int lapbeth_device_event(struct notifier_block *this,
370				unsigned long event, void *ptr)
371{
372	struct lapbethdev *lapbeth;
373	struct net_device *dev = ptr;
374
375	if (dev_net(dev) != &init_net)
376		return NOTIFY_DONE;
377
378	if (!dev_is_ethdev(dev))
379		return NOTIFY_DONE;
380
381	switch (event) {
382	case NETDEV_UP:
383		/* New ethernet device -> new LAPB interface	 */
384		if (lapbeth_get_x25_dev(dev) == NULL)
385			lapbeth_new_device(dev);
386		break;
387	case NETDEV_DOWN:
388		/* ethernet device closed -> close LAPB interface */
389		lapbeth = lapbeth_get_x25_dev(dev);
390		if (lapbeth)
391			dev_close(lapbeth->axdev);
392		break;
393	case NETDEV_UNREGISTER:
394		/* ethernet device disappears -> remove LAPB interface */
395		lapbeth = lapbeth_get_x25_dev(dev);
396		if (lapbeth)
397			lapbeth_free_device(lapbeth);
398		break;
399	}
400
401	return NOTIFY_DONE;
402}
403
404/* ------------------------------------------------------------------------ */
405
406static struct packet_type lapbeth_packet_type __read_mostly = {
407	.type = cpu_to_be16(ETH_P_DEC),
408	.func = lapbeth_rcv,
409};
410
411static struct notifier_block lapbeth_dev_notifier = {
412	.notifier_call = lapbeth_device_event,
413};
414
415static const char banner[] __initconst =
416	KERN_INFO "LAPB Ethernet driver version 0.02\n";
417
418static int __init lapbeth_init_driver(void)
419{
420	dev_add_pack(&lapbeth_packet_type);
421
422	register_netdevice_notifier(&lapbeth_dev_notifier);
423
424	printk(banner);
425
426	return 0;
427}
428module_init(lapbeth_init_driver);
429
430static void __exit lapbeth_cleanup_driver(void)
431{
432	struct lapbethdev *lapbeth;
433	struct list_head *entry, *tmp;
434
435	dev_remove_pack(&lapbeth_packet_type);
436	unregister_netdevice_notifier(&lapbeth_dev_notifier);
437
438	rtnl_lock();
439	list_for_each_safe(entry, tmp, &lapbeth_devices) {
440		lapbeth = list_entry(entry, struct lapbethdev, node);
441
442		dev_put(lapbeth->ethdev);
443		unregister_netdevice(lapbeth->axdev);
444	}
445	rtnl_unlock();
446}
447module_exit(lapbeth_cleanup_driver);
448
449MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
450MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
451MODULE_LICENSE("GPL");
452