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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/netdev_lock.h>
43#include <net/x25device.h>
44
45static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
46
47/* If this number is made larger, check that the temporary string buffer
48 * in lapbeth_new_device is large enough to store the probe device name.
49 */
50#define MAXLAPBDEV 100
51
52struct lapbethdev {
53 struct list_head node;
54 struct net_device *ethdev; /* link to ethernet device */
55 struct net_device *axdev; /* lapbeth device (lapb#) */
56 bool up;
57 spinlock_t up_lock; /* Protects "up" */
58 struct sk_buff_head rx_queue;
59 struct napi_struct napi;
60};
61
62static LIST_HEAD(lapbeth_devices);
63
64static void lapbeth_connected(struct net_device *dev, int reason);
65static void lapbeth_disconnected(struct net_device *dev, int reason);
66
67/* ------------------------------------------------------------------------ */
68
69/* Get the LAPB device for the ethernet device
70 */
71static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
72{
73 struct lapbethdev *lapbeth;
74
75 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
76 if (lapbeth->ethdev == dev)
77 return lapbeth;
78 }
79 return NULL;
80}
81
82static __inline__ int dev_is_ethdev(struct net_device *dev)
83{
84 return dev->type == ARPHRD_ETHER && !netdev_need_ops_lock(dev);
85}
86
87/* ------------------------------------------------------------------------ */
88
89static int lapbeth_napi_poll(struct napi_struct *napi, int budget)
90{
91 struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev,
92 napi);
93 struct sk_buff *skb;
94 int processed = 0;
95
96 for (; processed < budget; ++processed) {
97 skb = skb_dequeue(&lapbeth->rx_queue);
98 if (!skb)
99 break;
100 netif_receive_skb_core(skb);
101 }
102
103 if (processed < budget)
104 napi_complete(napi);
105
106 return processed;
107}
108
109/* Receive a LAPB frame via an ethernet interface.
110 */
111static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev,
112 struct packet_type *ptype, struct net_device *orig_dev)
113{
114 int len, err;
115 struct lapbethdev *lapbeth;
116
117 if (dev_net(dev) != &init_net)
118 goto drop;
119
120 skb = skb_share_check(skb, GFP_ATOMIC);
121 if (!skb)
122 return NET_RX_DROP;
123
124 if (!pskb_may_pull(skb, 2))
125 goto drop;
126
127 rcu_read_lock();
128 lapbeth = lapbeth_get_x25_dev(dev);
129 if (!lapbeth)
130 goto drop_unlock_rcu;
131 spin_lock_bh(&lapbeth->up_lock);
132 if (!lapbeth->up)
133 goto drop_unlock;
134
135 len = skb->data[0] + skb->data[1] * 256;
136 dev->stats.rx_packets++;
137 dev->stats.rx_bytes += len;
138
139 skb_pull(skb, 2); /* Remove the length bytes */
140 skb_trim(skb, len); /* Set the length of the data */
141
142 err = lapb_data_received(lapbeth->axdev, skb);
143 if (err != LAPB_OK) {
144 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
145 goto drop_unlock;
146 }
147out:
148 spin_unlock_bh(&lapbeth->up_lock);
149 rcu_read_unlock();
150 return 0;
151drop_unlock:
152 kfree_skb(skb);
153 goto out;
154drop_unlock_rcu:
155 rcu_read_unlock();
156drop:
157 kfree_skb(skb);
158 return 0;
159}
160
161static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
162{
163 struct lapbethdev *lapbeth = netdev_priv(dev);
164 unsigned char *ptr;
165
166 if (skb_cow(skb, 1)) {
167 kfree_skb(skb);
168 return NET_RX_DROP;
169 }
170
171 skb_push(skb, 1);
172
173 ptr = skb->data;
174 *ptr = X25_IFACE_DATA;
175
176 skb->protocol = x25_type_trans(skb, dev);
177
178 skb_queue_tail(&lapbeth->rx_queue, skb);
179 napi_schedule(&lapbeth->napi);
180 return NET_RX_SUCCESS;
181}
182
183/* Send a LAPB frame via an ethernet interface
184 */
185static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
186 struct net_device *dev)
187{
188 struct lapbethdev *lapbeth = netdev_priv(dev);
189 int err;
190
191 spin_lock_bh(&lapbeth->up_lock);
192 if (!lapbeth->up)
193 goto drop;
194
195 /* There should be a pseudo header of 1 byte added by upper layers.
196 * Check to make sure it is there before reading it.
197 */
198 if (skb->len < 1)
199 goto drop;
200
201 switch (skb->data[0]) {
202 case X25_IFACE_DATA:
203 break;
204 case X25_IFACE_CONNECT:
205 err = lapb_connect_request(dev);
206 if (err == LAPB_CONNECTED)
207 lapbeth_connected(dev, LAPB_OK);
208 else if (err != LAPB_OK)
209 pr_err("lapb_connect_request error: %d\n", err);
210 goto drop;
211 case X25_IFACE_DISCONNECT:
212 err = lapb_disconnect_request(dev);
213 if (err == LAPB_NOTCONNECTED)
214 lapbeth_disconnected(dev, LAPB_OK);
215 else if (err != LAPB_OK)
216 pr_err("lapb_disconnect_request err: %d\n", err);
217 fallthrough;
218 default:
219 goto drop;
220 }
221
222 skb_pull(skb, 1);
223
224 err = lapb_data_request(dev, skb);
225 if (err != LAPB_OK) {
226 pr_err("lapb_data_request error - %d\n", err);
227 goto drop;
228 }
229out:
230 spin_unlock_bh(&lapbeth->up_lock);
231 return NETDEV_TX_OK;
232drop:
233 kfree_skb(skb);
234 goto out;
235}
236
237static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
238{
239 struct lapbethdev *lapbeth = netdev_priv(ndev);
240 unsigned char *ptr;
241 struct net_device *dev;
242 int size = skb->len;
243
244 ptr = skb_push(skb, 2);
245
246 *ptr++ = size % 256;
247 *ptr++ = size / 256;
248
249 ndev->stats.tx_packets++;
250 ndev->stats.tx_bytes += size;
251
252 skb->dev = dev = lapbeth->ethdev;
253
254 skb->protocol = htons(ETH_P_DEC);
255
256 skb_reset_network_header(skb);
257
258 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
259
260 dev_queue_xmit(skb);
261}
262
263static void lapbeth_connected(struct net_device *dev, int reason)
264{
265 struct lapbethdev *lapbeth = netdev_priv(dev);
266 unsigned char *ptr;
267 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
268
269 if (!skb)
270 return;
271
272 ptr = skb_put(skb, 1);
273 *ptr = X25_IFACE_CONNECT;
274
275 skb->protocol = x25_type_trans(skb, dev);
276
277 skb_queue_tail(&lapbeth->rx_queue, skb);
278 napi_schedule(&lapbeth->napi);
279}
280
281static void lapbeth_disconnected(struct net_device *dev, int reason)
282{
283 struct lapbethdev *lapbeth = netdev_priv(dev);
284 unsigned char *ptr;
285 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
286
287 if (!skb)
288 return;
289
290 ptr = skb_put(skb, 1);
291 *ptr = X25_IFACE_DISCONNECT;
292
293 skb->protocol = x25_type_trans(skb, dev);
294
295 skb_queue_tail(&lapbeth->rx_queue, skb);
296 napi_schedule(&lapbeth->napi);
297}
298
299/* Set AX.25 callsign
300 */
301static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
302{
303 struct sockaddr *sa = addr;
304
305 dev_addr_set(dev, sa->sa_data);
306 return 0;
307}
308
309static const struct lapb_register_struct lapbeth_callbacks = {
310 .connect_confirmation = lapbeth_connected,
311 .connect_indication = lapbeth_connected,
312 .disconnect_confirmation = lapbeth_disconnected,
313 .disconnect_indication = lapbeth_disconnected,
314 .data_indication = lapbeth_data_indication,
315 .data_transmit = lapbeth_data_transmit,
316};
317
318/* open/close a device
319 */
320static int lapbeth_open(struct net_device *dev)
321{
322 struct lapbethdev *lapbeth = netdev_priv(dev);
323 int err;
324
325 napi_enable(&lapbeth->napi);
326
327 err = lapb_register(dev, &lapbeth_callbacks);
328 if (err != LAPB_OK) {
329 napi_disable(&lapbeth->napi);
330 pr_err("lapb_register error: %d\n", err);
331 return -ENODEV;
332 }
333
334 spin_lock_bh(&lapbeth->up_lock);
335 lapbeth->up = true;
336 spin_unlock_bh(&lapbeth->up_lock);
337
338 return 0;
339}
340
341static int lapbeth_close(struct net_device *dev)
342{
343 struct lapbethdev *lapbeth = netdev_priv(dev);
344 int err;
345
346 spin_lock_bh(&lapbeth->up_lock);
347 lapbeth->up = false;
348 spin_unlock_bh(&lapbeth->up_lock);
349
350 err = lapb_unregister(dev);
351 if (err != LAPB_OK)
352 pr_err("lapb_unregister error: %d\n", err);
353
354 napi_disable(&lapbeth->napi);
355
356 return 0;
357}
358
359/* ------------------------------------------------------------------------ */
360
361static const struct net_device_ops lapbeth_netdev_ops = {
362 .ndo_open = lapbeth_open,
363 .ndo_stop = lapbeth_close,
364 .ndo_start_xmit = lapbeth_xmit,
365 .ndo_set_mac_address = lapbeth_set_mac_address,
366};
367
368static void lapbeth_setup(struct net_device *dev)
369{
370 netdev_lockdep_set_classes(dev);
371 dev->netdev_ops = &lapbeth_netdev_ops;
372 dev->needs_free_netdev = true;
373 dev->type = ARPHRD_X25;
374 dev->hard_header_len = 0;
375 dev->mtu = 1000;
376 dev->addr_len = 0;
377}
378
379/* Setup a new device.
380 */
381static int lapbeth_new_device(struct net_device *dev)
382{
383 struct net_device *ndev;
384 struct lapbethdev *lapbeth;
385 int rc = -ENOMEM;
386
387 ASSERT_RTNL();
388
389 if (dev->type != ARPHRD_ETHER)
390 return -EINVAL;
391
392 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
393 lapbeth_setup);
394 if (!ndev)
395 goto out;
396
397 /* When transmitting data:
398 * first this driver removes a pseudo header of 1 byte,
399 * then the lapb module prepends an LAPB header of at most 3 bytes,
400 * then this driver prepends a length field of 2 bytes,
401 * then the underlying Ethernet device prepends its own header.
402 */
403 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
404 + dev->needed_headroom;
405 ndev->needed_tailroom = dev->needed_tailroom;
406
407 lapbeth = netdev_priv(ndev);
408 lapbeth->axdev = ndev;
409
410 dev_hold(dev);
411 lapbeth->ethdev = dev;
412
413 lapbeth->up = false;
414 spin_lock_init(&lapbeth->up_lock);
415
416 skb_queue_head_init(&lapbeth->rx_queue);
417 netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
418
419 rc = -EIO;
420 if (register_netdevice(ndev))
421 goto fail;
422
423 list_add_rcu(&lapbeth->node, &lapbeth_devices);
424 rc = 0;
425out:
426 return rc;
427fail:
428 dev_put(dev);
429 free_netdev(ndev);
430 goto out;
431}
432
433/* Free a lapb network device.
434 */
435static void lapbeth_free_device(struct lapbethdev *lapbeth)
436{
437 dev_put(lapbeth->ethdev);
438 list_del_rcu(&lapbeth->node);
439 unregister_netdevice(lapbeth->axdev);
440}
441
442/* Handle device status changes.
443 *
444 * Called from notifier with RTNL held.
445 */
446static int lapbeth_device_event(struct notifier_block *this,
447 unsigned long event, void *ptr)
448{
449 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
450 struct lapbethdev *lapbeth;
451
452 if (dev_net(dev) != &init_net)
453 return NOTIFY_DONE;
454
455 lapbeth = lapbeth_get_x25_dev(dev);
456 if (!dev_is_ethdev(dev) && !lapbeth)
457 return NOTIFY_DONE;
458
459 switch (event) {
460 case NETDEV_UP:
461 /* New ethernet device -> new LAPB interface */
462 if (!lapbeth)
463 lapbeth_new_device(dev);
464 break;
465 case NETDEV_GOING_DOWN:
466 /* ethernet device closes -> close LAPB interface */
467 if (lapbeth)
468 dev_close(lapbeth->axdev);
469 break;
470 case NETDEV_UNREGISTER:
471 /* ethernet device disappears -> remove LAPB interface */
472 if (lapbeth)
473 lapbeth_free_device(lapbeth);
474 break;
475 case NETDEV_PRE_TYPE_CHANGE:
476 /* Our underlying device type must not change. */
477 if (lapbeth)
478 return NOTIFY_BAD;
479 }
480
481 return NOTIFY_DONE;
482}
483
484/* ------------------------------------------------------------------------ */
485
486static struct packet_type lapbeth_packet_type __read_mostly = {
487 .type = cpu_to_be16(ETH_P_DEC),
488 .func = lapbeth_rcv,
489};
490
491static struct notifier_block lapbeth_dev_notifier = {
492 .notifier_call = lapbeth_device_event,
493};
494
495static const char banner[] __initconst =
496 KERN_INFO "LAPB Ethernet driver version 0.02\n";
497
498static int __init lapbeth_init_driver(void)
499{
500 int err;
501
502 dev_add_pack(&lapbeth_packet_type);
503
504 err = register_netdevice_notifier(&lapbeth_dev_notifier);
505 if (err) {
506 dev_remove_pack(&lapbeth_packet_type);
507 return err;
508 }
509
510 printk(banner);
511
512 return 0;
513}
514module_init(lapbeth_init_driver);
515
516static void __exit lapbeth_cleanup_driver(void)
517{
518 struct lapbethdev *lapbeth;
519 struct list_head *entry, *tmp;
520
521 dev_remove_pack(&lapbeth_packet_type);
522 unregister_netdevice_notifier(&lapbeth_dev_notifier);
523
524 rtnl_lock();
525 list_for_each_safe(entry, tmp, &lapbeth_devices) {
526 lapbeth = list_entry(entry, struct lapbethdev, node);
527
528 dev_put(lapbeth->ethdev);
529 unregister_netdevice(lapbeth->axdev);
530 }
531 rtnl_unlock();
532}
533module_exit(lapbeth_cleanup_driver);
534
535MODULE_AUTHOR("Jonathan Naylor <[email protected]>");
536MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
537MODULE_LICENSE("GPL");