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 */
49 #define MAXLAPBDEV 100
50
51 struct lapbethdev {
52 struct list_head node;
53 struct net_device *ethdev; /* link to ethernet device */
54 struct net_device *axdev; /* lapbeth device (lapb#) */
55 bool up;
56 spinlock_t up_lock; /* Protects "up" */
57 struct sk_buff_head rx_queue;
58 struct napi_struct napi;
59 };
60
61 static LIST_HEAD(lapbeth_devices);
62
63 static void lapbeth_connected(struct net_device *dev, int reason);
64 static void lapbeth_disconnected(struct net_device *dev, int reason);
65
66 /* ------------------------------------------------------------------------ */
67
68 /* Get the LAPB device for the ethernet device
69 */
lapbeth_get_x25_dev(struct net_device * dev)70 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
71 {
72 struct lapbethdev *lapbeth;
73
74 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
75 if (lapbeth->ethdev == dev)
76 return lapbeth;
77 }
78 return NULL;
79 }
80
dev_is_ethdev(struct net_device * dev)81 static __inline__ int dev_is_ethdev(struct net_device *dev)
82 {
83 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
84 }
85
86 /* ------------------------------------------------------------------------ */
87
lapbeth_napi_poll(struct napi_struct * napi,int budget)88 static int lapbeth_napi_poll(struct napi_struct *napi, int budget)
89 {
90 struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev,
91 napi);
92 struct sk_buff *skb;
93 int processed = 0;
94
95 for (; processed < budget; ++processed) {
96 skb = skb_dequeue(&lapbeth->rx_queue);
97 if (!skb)
98 break;
99 netif_receive_skb_core(skb);
100 }
101
102 if (processed < budget)
103 napi_complete(napi);
104
105 return processed;
106 }
107
108 /* Receive a LAPB frame via an ethernet interface.
109 */
lapbeth_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * ptype,struct net_device * orig_dev)110 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev,
111 struct packet_type *ptype, struct net_device *orig_dev)
112 {
113 int len, err;
114 struct lapbethdev *lapbeth;
115
116 if (dev_net(dev) != &init_net)
117 goto drop;
118
119 skb = skb_share_check(skb, GFP_ATOMIC);
120 if (!skb)
121 return NET_RX_DROP;
122
123 if (!pskb_may_pull(skb, 2))
124 goto drop;
125
126 rcu_read_lock();
127 lapbeth = lapbeth_get_x25_dev(dev);
128 if (!lapbeth)
129 goto drop_unlock_rcu;
130 spin_lock_bh(&lapbeth->up_lock);
131 if (!lapbeth->up)
132 goto drop_unlock;
133
134 len = skb->data[0] + skb->data[1] * 256;
135 dev->stats.rx_packets++;
136 dev->stats.rx_bytes += len;
137
138 skb_pull(skb, 2); /* Remove the length bytes */
139 skb_trim(skb, len); /* Set the length of the data */
140
141 err = lapb_data_received(lapbeth->axdev, skb);
142 if (err != LAPB_OK) {
143 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
144 goto drop_unlock;
145 }
146 out:
147 spin_unlock_bh(&lapbeth->up_lock);
148 rcu_read_unlock();
149 return 0;
150 drop_unlock:
151 kfree_skb(skb);
152 goto out;
153 drop_unlock_rcu:
154 rcu_read_unlock();
155 drop:
156 kfree_skb(skb);
157 return 0;
158 }
159
lapbeth_data_indication(struct net_device * dev,struct sk_buff * skb)160 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
161 {
162 struct lapbethdev *lapbeth = netdev_priv(dev);
163 unsigned char *ptr;
164
165 if (skb_cow(skb, 1)) {
166 kfree_skb(skb);
167 return NET_RX_DROP;
168 }
169
170 skb_push(skb, 1);
171
172 ptr = skb->data;
173 *ptr = X25_IFACE_DATA;
174
175 skb->protocol = x25_type_trans(skb, dev);
176
177 skb_queue_tail(&lapbeth->rx_queue, skb);
178 napi_schedule(&lapbeth->napi);
179 return NET_RX_SUCCESS;
180 }
181
182 /* Send a LAPB frame via an ethernet interface
183 */
lapbeth_xmit(struct sk_buff * skb,struct net_device * dev)184 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
185 struct net_device *dev)
186 {
187 struct lapbethdev *lapbeth = netdev_priv(dev);
188 int err;
189
190 spin_lock_bh(&lapbeth->up_lock);
191 if (!lapbeth->up)
192 goto drop;
193
194 /* There should be a pseudo header of 1 byte added by upper layers.
195 * Check to make sure it is there before reading it.
196 */
197 if (skb->len < 1)
198 goto drop;
199
200 switch (skb->data[0]) {
201 case X25_IFACE_DATA:
202 break;
203 case X25_IFACE_CONNECT:
204 err = lapb_connect_request(dev);
205 if (err == LAPB_CONNECTED)
206 lapbeth_connected(dev, LAPB_OK);
207 else if (err != LAPB_OK)
208 pr_err("lapb_connect_request error: %d\n", err);
209 goto drop;
210 case X25_IFACE_DISCONNECT:
211 err = lapb_disconnect_request(dev);
212 if (err == LAPB_NOTCONNECTED)
213 lapbeth_disconnected(dev, LAPB_OK);
214 else if (err != LAPB_OK)
215 pr_err("lapb_disconnect_request err: %d\n", err);
216 fallthrough;
217 default:
218 goto drop;
219 }
220
221 skb_pull(skb, 1);
222
223 err = lapb_data_request(dev, skb);
224 if (err != LAPB_OK) {
225 pr_err("lapb_data_request error - %d\n", err);
226 goto drop;
227 }
228 out:
229 spin_unlock_bh(&lapbeth->up_lock);
230 return NETDEV_TX_OK;
231 drop:
232 kfree_skb(skb);
233 goto out;
234 }
235
lapbeth_data_transmit(struct net_device * ndev,struct sk_buff * skb)236 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
237 {
238 struct lapbethdev *lapbeth = netdev_priv(ndev);
239 unsigned char *ptr;
240 struct net_device *dev;
241 int size = skb->len;
242
243 ptr = skb_push(skb, 2);
244
245 *ptr++ = size % 256;
246 *ptr++ = size / 256;
247
248 ndev->stats.tx_packets++;
249 ndev->stats.tx_bytes += size;
250
251 skb->dev = dev = lapbeth->ethdev;
252
253 skb->protocol = htons(ETH_P_DEC);
254
255 skb_reset_network_header(skb);
256
257 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
258
259 dev_queue_xmit(skb);
260 }
261
lapbeth_connected(struct net_device * dev,int reason)262 static void lapbeth_connected(struct net_device *dev, int reason)
263 {
264 struct lapbethdev *lapbeth = netdev_priv(dev);
265 unsigned char *ptr;
266 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
267
268 if (!skb)
269 return;
270
271 ptr = skb_put(skb, 1);
272 *ptr = X25_IFACE_CONNECT;
273
274 skb->protocol = x25_type_trans(skb, dev);
275
276 skb_queue_tail(&lapbeth->rx_queue, skb);
277 napi_schedule(&lapbeth->napi);
278 }
279
lapbeth_disconnected(struct net_device * dev,int reason)280 static void lapbeth_disconnected(struct net_device *dev, int reason)
281 {
282 struct lapbethdev *lapbeth = netdev_priv(dev);
283 unsigned char *ptr;
284 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
285
286 if (!skb)
287 return;
288
289 ptr = skb_put(skb, 1);
290 *ptr = X25_IFACE_DISCONNECT;
291
292 skb->protocol = x25_type_trans(skb, dev);
293
294 skb_queue_tail(&lapbeth->rx_queue, skb);
295 napi_schedule(&lapbeth->napi);
296 }
297
298 /* Set AX.25 callsign
299 */
lapbeth_set_mac_address(struct net_device * dev,void * addr)300 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
301 {
302 struct sockaddr *sa = addr;
303
304 dev_addr_set(dev, sa->sa_data);
305 return 0;
306 }
307
308 static const struct lapb_register_struct lapbeth_callbacks = {
309 .connect_confirmation = lapbeth_connected,
310 .connect_indication = lapbeth_connected,
311 .disconnect_confirmation = lapbeth_disconnected,
312 .disconnect_indication = lapbeth_disconnected,
313 .data_indication = lapbeth_data_indication,
314 .data_transmit = lapbeth_data_transmit,
315 };
316
317 /* open/close a device
318 */
lapbeth_open(struct net_device * dev)319 static int lapbeth_open(struct net_device *dev)
320 {
321 struct lapbethdev *lapbeth = netdev_priv(dev);
322 int err;
323
324 napi_enable(&lapbeth->napi);
325
326 err = lapb_register(dev, &lapbeth_callbacks);
327 if (err != LAPB_OK) {
328 napi_disable(&lapbeth->napi);
329 pr_err("lapb_register error: %d\n", err);
330 return -ENODEV;
331 }
332
333 spin_lock_bh(&lapbeth->up_lock);
334 lapbeth->up = true;
335 spin_unlock_bh(&lapbeth->up_lock);
336
337 return 0;
338 }
339
lapbeth_close(struct net_device * dev)340 static int lapbeth_close(struct net_device *dev)
341 {
342 struct lapbethdev *lapbeth = netdev_priv(dev);
343 int err;
344
345 spin_lock_bh(&lapbeth->up_lock);
346 lapbeth->up = false;
347 spin_unlock_bh(&lapbeth->up_lock);
348
349 err = lapb_unregister(dev);
350 if (err != LAPB_OK)
351 pr_err("lapb_unregister error: %d\n", err);
352
353 napi_disable(&lapbeth->napi);
354
355 return 0;
356 }
357
358 /* ------------------------------------------------------------------------ */
359
360 static const struct net_device_ops lapbeth_netdev_ops = {
361 .ndo_open = lapbeth_open,
362 .ndo_stop = lapbeth_close,
363 .ndo_start_xmit = lapbeth_xmit,
364 .ndo_set_mac_address = lapbeth_set_mac_address,
365 };
366
lapbeth_setup(struct net_device * dev)367 static void lapbeth_setup(struct net_device *dev)
368 {
369 dev->netdev_ops = &lapbeth_netdev_ops;
370 dev->needs_free_netdev = true;
371 dev->type = ARPHRD_X25;
372 dev->hard_header_len = 0;
373 dev->mtu = 1000;
374 dev->addr_len = 0;
375 }
376
377 /* Setup a new device.
378 */
lapbeth_new_device(struct net_device * dev)379 static int lapbeth_new_device(struct net_device *dev)
380 {
381 struct net_device *ndev;
382 struct lapbethdev *lapbeth;
383 int rc = -ENOMEM;
384
385 ASSERT_RTNL();
386
387 if (dev->type != ARPHRD_ETHER)
388 return -EINVAL;
389
390 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
391 lapbeth_setup);
392 if (!ndev)
393 goto out;
394
395 /* When transmitting data:
396 * first this driver removes a pseudo header of 1 byte,
397 * then the lapb module prepends an LAPB header of at most 3 bytes,
398 * then this driver prepends a length field of 2 bytes,
399 * then the underlying Ethernet device prepends its own header.
400 */
401 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
402 + dev->needed_headroom;
403 ndev->needed_tailroom = dev->needed_tailroom;
404
405 lapbeth = netdev_priv(ndev);
406 lapbeth->axdev = ndev;
407
408 dev_hold(dev);
409 lapbeth->ethdev = dev;
410
411 lapbeth->up = false;
412 spin_lock_init(&lapbeth->up_lock);
413
414 skb_queue_head_init(&lapbeth->rx_queue);
415 netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
416
417 rc = -EIO;
418 if (register_netdevice(ndev))
419 goto fail;
420
421 list_add_rcu(&lapbeth->node, &lapbeth_devices);
422 rc = 0;
423 out:
424 return rc;
425 fail:
426 dev_put(dev);
427 free_netdev(ndev);
428 goto out;
429 }
430
431 /* Free a lapb network device.
432 */
lapbeth_free_device(struct lapbethdev * lapbeth)433 static void lapbeth_free_device(struct lapbethdev *lapbeth)
434 {
435 dev_put(lapbeth->ethdev);
436 list_del_rcu(&lapbeth->node);
437 unregister_netdevice(lapbeth->axdev);
438 }
439
440 /* Handle device status changes.
441 *
442 * Called from notifier with RTNL held.
443 */
lapbeth_device_event(struct notifier_block * this,unsigned long event,void * ptr)444 static int lapbeth_device_event(struct notifier_block *this,
445 unsigned long event, void *ptr)
446 {
447 struct lapbethdev *lapbeth;
448 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
449
450 if (dev_net(dev) != &init_net)
451 return NOTIFY_DONE;
452
453 if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev))
454 return NOTIFY_DONE;
455
456 switch (event) {
457 case NETDEV_UP:
458 /* New ethernet device -> new LAPB interface */
459 if (!lapbeth_get_x25_dev(dev))
460 lapbeth_new_device(dev);
461 break;
462 case NETDEV_GOING_DOWN:
463 /* ethernet device closes -> close LAPB interface */
464 lapbeth = lapbeth_get_x25_dev(dev);
465 if (lapbeth)
466 dev_close(lapbeth->axdev);
467 break;
468 case NETDEV_UNREGISTER:
469 /* ethernet device disappears -> remove LAPB interface */
470 lapbeth = lapbeth_get_x25_dev(dev);
471 if (lapbeth)
472 lapbeth_free_device(lapbeth);
473 break;
474 }
475
476 return NOTIFY_DONE;
477 }
478
479 /* ------------------------------------------------------------------------ */
480
481 static struct packet_type lapbeth_packet_type __read_mostly = {
482 .type = cpu_to_be16(ETH_P_DEC),
483 .func = lapbeth_rcv,
484 };
485
486 static struct notifier_block lapbeth_dev_notifier = {
487 .notifier_call = lapbeth_device_event,
488 };
489
490 static const char banner[] __initconst =
491 KERN_INFO "LAPB Ethernet driver version 0.02\n";
492
lapbeth_init_driver(void)493 static int __init lapbeth_init_driver(void)
494 {
495 dev_add_pack(&lapbeth_packet_type);
496
497 register_netdevice_notifier(&lapbeth_dev_notifier);
498
499 printk(banner);
500
501 return 0;
502 }
503 module_init(lapbeth_init_driver);
504
lapbeth_cleanup_driver(void)505 static void __exit lapbeth_cleanup_driver(void)
506 {
507 struct lapbethdev *lapbeth;
508 struct list_head *entry, *tmp;
509
510 dev_remove_pack(&lapbeth_packet_type);
511 unregister_netdevice_notifier(&lapbeth_dev_notifier);
512
513 rtnl_lock();
514 list_for_each_safe(entry, tmp, &lapbeth_devices) {
515 lapbeth = list_entry(entry, struct lapbethdev, node);
516
517 dev_put(lapbeth->ethdev);
518 unregister_netdevice(lapbeth->axdev);
519 }
520 rtnl_unlock();
521 }
522 module_exit(lapbeth_cleanup_driver);
523
524 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
525 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
526 MODULE_LICENSE("GPL");
527