1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * "LAPB via ethernet" driver release 001
4 *
5 * This code REQUIRES 2.1.15 or higher/ NET3.038
6 *
7 * This is a "pseudo" network driver to allow LAPB over Ethernet.
8 *
9 * This driver can use any ethernet destination address, and can be
10 * limited to accept frames from one dedicated ethernet card only.
11 *
12 * History
13 * LAPBETH 001 Jonathan Naylor Cloned from bpqether.c
14 * 2000-10-29 Henner Eisen lapb_data_indication() return status.
15 * 2000-11-14 Henner Eisen dev_hold/put, NETDEV_GOING_DOWN support
16 */
17
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20 #include <linux/errno.h>
21 #include <linux/types.h>
22 #include <linux/socket.h>
23 #include <linux/in.h>
24 #include <linux/slab.h>
25 #include <linux/kernel.h>
26 #include <linux/string.h>
27 #include <linux/net.h>
28 #include <linux/inet.h>
29 #include <linux/netdevice.h>
30 #include <linux/if_arp.h>
31 #include <linux/skbuff.h>
32 #include <net/sock.h>
33 #include <linux/uaccess.h>
34 #include <linux/mm.h>
35 #include <linux/interrupt.h>
36 #include <linux/notifier.h>
37 #include <linux/stat.h>
38 #include <linux/module.h>
39 #include <linux/lapb.h>
40 #include <linux/init.h>
41
42 #include <net/x25device.h>
43
44 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
45
46 /* If this number is made larger, check that the temporary string buffer
47 * in lapbeth_new_device is large enough to store the probe device name.*/
48 #define MAXLAPBDEV 100
49
50 struct lapbethdev {
51 struct list_head node;
52 struct net_device *ethdev; /* link to ethernet device */
53 struct net_device *axdev; /* lapbeth device (lapb#) */
54 };
55
56 static LIST_HEAD(lapbeth_devices);
57
58 /* ------------------------------------------------------------------------ */
59
60 /*
61 * Get the LAPB device for the ethernet device
62 */
lapbeth_get_x25_dev(struct net_device * dev)63 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
64 {
65 struct lapbethdev *lapbeth;
66
67 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
68 if (lapbeth->ethdev == dev)
69 return lapbeth;
70 }
71 return NULL;
72 }
73
dev_is_ethdev(struct net_device * dev)74 static __inline__ int dev_is_ethdev(struct net_device *dev)
75 {
76 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
77 }
78
79 /* ------------------------------------------------------------------------ */
80
81 /*
82 * Receive a LAPB frame via an ethernet interface.
83 */
lapbeth_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * ptype,struct net_device * orig_dev)84 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
85 {
86 int len, err;
87 struct lapbethdev *lapbeth;
88
89 if (dev_net(dev) != &init_net)
90 goto drop;
91
92 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
93 return NET_RX_DROP;
94
95 if (!pskb_may_pull(skb, 2))
96 goto drop;
97
98 rcu_read_lock();
99 lapbeth = lapbeth_get_x25_dev(dev);
100 if (!lapbeth)
101 goto drop_unlock;
102 if (!netif_running(lapbeth->axdev))
103 goto drop_unlock;
104
105 len = skb->data[0] + skb->data[1] * 256;
106 dev->stats.rx_packets++;
107 dev->stats.rx_bytes += len;
108
109 skb_pull(skb, 2); /* Remove the length bytes */
110 skb_trim(skb, len); /* Set the length of the data */
111
112 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
113 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
114 goto drop_unlock;
115 }
116 out:
117 rcu_read_unlock();
118 return 0;
119 drop_unlock:
120 kfree_skb(skb);
121 goto out;
122 drop:
123 kfree_skb(skb);
124 return 0;
125 }
126
lapbeth_data_indication(struct net_device * dev,struct sk_buff * skb)127 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
128 {
129 unsigned char *ptr;
130
131 if (skb_cow(skb, 1)) {
132 kfree_skb(skb);
133 return NET_RX_DROP;
134 }
135
136 skb_push(skb, 1);
137
138 ptr = skb->data;
139 *ptr = X25_IFACE_DATA;
140
141 skb->protocol = x25_type_trans(skb, dev);
142 return netif_rx(skb);
143 }
144
145 /*
146 * Send a LAPB frame via an ethernet interface
147 */
lapbeth_xmit(struct sk_buff * skb,struct net_device * dev)148 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
149 struct net_device *dev)
150 {
151 int err;
152
153 /*
154 * Just to be *really* sure not to send anything if the interface
155 * is down, the ethernet device may have gone.
156 */
157 if (!netif_running(dev))
158 goto drop;
159
160 /* There should be a pseudo header of 1 byte added by upper layers.
161 * Check to make sure it is there before reading it.
162 */
163 if (skb->len < 1)
164 goto drop;
165
166 switch (skb->data[0]) {
167 case X25_IFACE_DATA:
168 break;
169 case X25_IFACE_CONNECT:
170 if ((err = lapb_connect_request(dev)) != LAPB_OK)
171 pr_err("lapb_connect_request error: %d\n", err);
172 goto drop;
173 case X25_IFACE_DISCONNECT:
174 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
175 pr_err("lapb_disconnect_request err: %d\n", err);
176 fallthrough;
177 default:
178 goto drop;
179 }
180
181 skb_pull(skb, 1);
182
183 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
184 pr_err("lapb_data_request error - %d\n", err);
185 goto drop;
186 }
187 out:
188 return NETDEV_TX_OK;
189 drop:
190 kfree_skb(skb);
191 goto out;
192 }
193
lapbeth_data_transmit(struct net_device * ndev,struct sk_buff * skb)194 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
195 {
196 struct lapbethdev *lapbeth = netdev_priv(ndev);
197 unsigned char *ptr;
198 struct net_device *dev;
199 int size = skb->len;
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 skb->protocol = htons(ETH_P_DEC);
212
213 skb_reset_network_header(skb);
214
215 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
216
217 dev_queue_xmit(skb);
218 }
219
lapbeth_connected(struct net_device * dev,int reason)220 static void lapbeth_connected(struct net_device *dev, int reason)
221 {
222 unsigned char *ptr;
223 struct sk_buff *skb = dev_alloc_skb(1);
224
225 if (!skb) {
226 pr_err("out of memory\n");
227 return;
228 }
229
230 ptr = skb_put(skb, 1);
231 *ptr = X25_IFACE_CONNECT;
232
233 skb->protocol = x25_type_trans(skb, dev);
234 netif_rx(skb);
235 }
236
lapbeth_disconnected(struct net_device * dev,int reason)237 static void lapbeth_disconnected(struct net_device *dev, int reason)
238 {
239 unsigned char *ptr;
240 struct sk_buff *skb = dev_alloc_skb(1);
241
242 if (!skb) {
243 pr_err("out of memory\n");
244 return;
245 }
246
247 ptr = skb_put(skb, 1);
248 *ptr = X25_IFACE_DISCONNECT;
249
250 skb->protocol = x25_type_trans(skb, dev);
251 netif_rx(skb);
252 }
253
254 /*
255 * Set AX.25 callsign
256 */
lapbeth_set_mac_address(struct net_device * dev,void * addr)257 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
258 {
259 struct sockaddr *sa = addr;
260 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
261 return 0;
262 }
263
264
265 static const struct lapb_register_struct lapbeth_callbacks = {
266 .connect_confirmation = lapbeth_connected,
267 .connect_indication = lapbeth_connected,
268 .disconnect_confirmation = lapbeth_disconnected,
269 .disconnect_indication = lapbeth_disconnected,
270 .data_indication = lapbeth_data_indication,
271 .data_transmit = lapbeth_data_transmit,
272 };
273
274 /*
275 * open/close a device
276 */
lapbeth_open(struct net_device * dev)277 static int lapbeth_open(struct net_device *dev)
278 {
279 int err;
280
281 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
282 pr_err("lapb_register error: %d\n", err);
283 return -ENODEV;
284 }
285
286 netif_start_queue(dev);
287 return 0;
288 }
289
lapbeth_close(struct net_device * dev)290 static int lapbeth_close(struct net_device *dev)
291 {
292 int err;
293
294 netif_stop_queue(dev);
295
296 if ((err = lapb_unregister(dev)) != LAPB_OK)
297 pr_err("lapb_unregister error: %d\n", err);
298
299 return 0;
300 }
301
302 /* ------------------------------------------------------------------------ */
303
304 static const struct net_device_ops lapbeth_netdev_ops = {
305 .ndo_open = lapbeth_open,
306 .ndo_stop = lapbeth_close,
307 .ndo_start_xmit = lapbeth_xmit,
308 .ndo_set_mac_address = lapbeth_set_mac_address,
309 };
310
lapbeth_setup(struct net_device * dev)311 static void lapbeth_setup(struct net_device *dev)
312 {
313 dev->netdev_ops = &lapbeth_netdev_ops;
314 dev->needs_free_netdev = true;
315 dev->type = ARPHRD_X25;
316 dev->hard_header_len = 0;
317 dev->mtu = 1000;
318 dev->addr_len = 0;
319 }
320
321 /*
322 * Setup a new device.
323 */
lapbeth_new_device(struct net_device * dev)324 static int lapbeth_new_device(struct net_device *dev)
325 {
326 struct net_device *ndev;
327 struct lapbethdev *lapbeth;
328 int rc = -ENOMEM;
329
330 ASSERT_RTNL();
331
332 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
333 lapbeth_setup);
334 if (!ndev)
335 goto out;
336
337 /* When transmitting data:
338 * first this driver removes a pseudo header of 1 byte,
339 * then the lapb module prepends an LAPB header of at most 3 bytes,
340 * then this driver prepends a length field of 2 bytes,
341 * then the underlying Ethernet device prepends its own header.
342 */
343 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
344 + dev->needed_headroom;
345 ndev->needed_tailroom = dev->needed_tailroom;
346
347 lapbeth = netdev_priv(ndev);
348 lapbeth->axdev = ndev;
349
350 dev_hold(dev);
351 lapbeth->ethdev = dev;
352
353 rc = -EIO;
354 if (register_netdevice(ndev))
355 goto fail;
356
357 list_add_rcu(&lapbeth->node, &lapbeth_devices);
358 rc = 0;
359 out:
360 return rc;
361 fail:
362 dev_put(dev);
363 free_netdev(ndev);
364 goto out;
365 }
366
367 /*
368 * Free a lapb network device.
369 */
lapbeth_free_device(struct lapbethdev * lapbeth)370 static void lapbeth_free_device(struct lapbethdev *lapbeth)
371 {
372 dev_put(lapbeth->ethdev);
373 list_del_rcu(&lapbeth->node);
374 unregister_netdevice(lapbeth->axdev);
375 }
376
377 /*
378 * Handle device status changes.
379 *
380 * Called from notifier with RTNL held.
381 */
lapbeth_device_event(struct notifier_block * this,unsigned long event,void * ptr)382 static int lapbeth_device_event(struct notifier_block *this,
383 unsigned long event, void *ptr)
384 {
385 struct lapbethdev *lapbeth;
386 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
387
388 if (dev_net(dev) != &init_net)
389 return NOTIFY_DONE;
390
391 if (!dev_is_ethdev(dev))
392 return NOTIFY_DONE;
393
394 switch (event) {
395 case NETDEV_UP:
396 /* New ethernet device -> new LAPB interface */
397 if (lapbeth_get_x25_dev(dev) == NULL)
398 lapbeth_new_device(dev);
399 break;
400 case NETDEV_DOWN:
401 /* ethernet device closed -> close LAPB interface */
402 lapbeth = lapbeth_get_x25_dev(dev);
403 if (lapbeth)
404 dev_close(lapbeth->axdev);
405 break;
406 case NETDEV_UNREGISTER:
407 /* ethernet device disappears -> remove LAPB interface */
408 lapbeth = lapbeth_get_x25_dev(dev);
409 if (lapbeth)
410 lapbeth_free_device(lapbeth);
411 break;
412 }
413
414 return NOTIFY_DONE;
415 }
416
417 /* ------------------------------------------------------------------------ */
418
419 static struct packet_type lapbeth_packet_type __read_mostly = {
420 .type = cpu_to_be16(ETH_P_DEC),
421 .func = lapbeth_rcv,
422 };
423
424 static struct notifier_block lapbeth_dev_notifier = {
425 .notifier_call = lapbeth_device_event,
426 };
427
428 static const char banner[] __initconst =
429 KERN_INFO "LAPB Ethernet driver version 0.02\n";
430
lapbeth_init_driver(void)431 static int __init lapbeth_init_driver(void)
432 {
433 dev_add_pack(&lapbeth_packet_type);
434
435 register_netdevice_notifier(&lapbeth_dev_notifier);
436
437 printk(banner);
438
439 return 0;
440 }
441 module_init(lapbeth_init_driver);
442
lapbeth_cleanup_driver(void)443 static void __exit lapbeth_cleanup_driver(void)
444 {
445 struct lapbethdev *lapbeth;
446 struct list_head *entry, *tmp;
447
448 dev_remove_pack(&lapbeth_packet_type);
449 unregister_netdevice_notifier(&lapbeth_dev_notifier);
450
451 rtnl_lock();
452 list_for_each_safe(entry, tmp, &lapbeth_devices) {
453 lapbeth = list_entry(entry, struct lapbethdev, node);
454
455 dev_put(lapbeth->ethdev);
456 unregister_netdevice(lapbeth->axdev);
457 }
458 rtnl_unlock();
459 }
460 module_exit(lapbeth_cleanup_driver);
461
462 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
463 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
464 MODULE_LICENSE("GPL");
465