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