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linux
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
44static 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
50struct lapbethdev {
51 struct list_head node;
52 struct net_device *ethdev; /* link to ethernet device */
53 struct net_device *axdev; /* lapbeth device (lapb#) */
54 bool up;
55 spinlock_t up_lock; /* Protects "up" */
56 struct sk_buff_head rx_queue;
57 struct napi_struct napi;
58};
59
60static LIST_HEAD(lapbeth_devices);
61
62static void lapbeth_connected(struct net_device *dev, int reason);
63static void lapbeth_disconnected(struct net_device *dev, int reason);
64
65/* ------------------------------------------------------------------------ */
66
67/*
68 * Get the LAPB device for the ethernet device
69 */
70static 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
81static __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
88static 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/*
109 * Receive a LAPB frame via an ethernet interface.
110 */
111static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, 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 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
120 return NET_RX_DROP;
121
122 if (!pskb_may_pull(skb, 2))
123 goto drop;
124
125 rcu_read_lock();
126 lapbeth = lapbeth_get_x25_dev(dev);
127 if (!lapbeth)
128 goto drop_unlock_rcu;
129 spin_lock_bh(&lapbeth->up_lock);
130 if (!lapbeth->up)
131 goto drop_unlock;
132
133 len = skb->data[0] + skb->data[1] * 256;
134 dev->stats.rx_packets++;
135 dev->stats.rx_bytes += len;
136
137 skb_pull(skb, 2); /* Remove the length bytes */
138 skb_trim(skb, len); /* Set the length of the data */
139
140 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
141 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
142 goto drop_unlock;
143 }
144out:
145 spin_unlock_bh(&lapbeth->up_lock);
146 rcu_read_unlock();
147 return 0;
148drop_unlock:
149 kfree_skb(skb);
150 goto out;
151drop_unlock_rcu:
152 rcu_read_unlock();
153drop:
154 kfree_skb(skb);
155 return 0;
156}
157
158static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
159{
160 struct lapbethdev *lapbeth = netdev_priv(dev);
161 unsigned char *ptr;
162
163 if (skb_cow(skb, 1)) {
164 kfree_skb(skb);
165 return NET_RX_DROP;
166 }
167
168 skb_push(skb, 1);
169
170 ptr = skb->data;
171 *ptr = X25_IFACE_DATA;
172
173 skb->protocol = x25_type_trans(skb, dev);
174
175 skb_queue_tail(&lapbeth->rx_queue, skb);
176 napi_schedule(&lapbeth->napi);
177 return NET_RX_SUCCESS;
178}
179
180/*
181 * Send a LAPB frame via an ethernet interface
182 */
183static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
184 struct net_device *dev)
185{
186 struct lapbethdev *lapbeth = netdev_priv(dev);
187 int err;
188
189 spin_lock_bh(&lapbeth->up_lock);
190 if (!lapbeth->up)
191 goto drop;
192
193 /* There should be a pseudo header of 1 byte added by upper layers.
194 * Check to make sure it is there before reading it.
195 */
196 if (skb->len < 1)
197 goto drop;
198
199 switch (skb->data[0]) {
200 case X25_IFACE_DATA:
201 break;
202 case X25_IFACE_CONNECT:
203 err = lapb_connect_request(dev);
204 if (err == LAPB_CONNECTED)
205 lapbeth_connected(dev, LAPB_OK);
206 else if (err != LAPB_OK)
207 pr_err("lapb_connect_request error: %d\n", err);
208 goto drop;
209 case X25_IFACE_DISCONNECT:
210 err = lapb_disconnect_request(dev);
211 if (err == LAPB_NOTCONNECTED)
212 lapbeth_disconnected(dev, LAPB_OK);
213 else if (err != LAPB_OK)
214 pr_err("lapb_disconnect_request err: %d\n", err);
215 fallthrough;
216 default:
217 goto drop;
218 }
219
220 skb_pull(skb, 1);
221
222 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
223 pr_err("lapb_data_request error - %d\n", err);
224 goto drop;
225 }
226out:
227 spin_unlock_bh(&lapbeth->up_lock);
228 return NETDEV_TX_OK;
229drop:
230 kfree_skb(skb);
231 goto out;
232}
233
234static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
235{
236 struct lapbethdev *lapbeth = netdev_priv(ndev);
237 unsigned char *ptr;
238 struct net_device *dev;
239 int size = skb->len;
240
241 ptr = skb_push(skb, 2);
242
243 *ptr++ = size % 256;
244 *ptr++ = size / 256;
245
246 ndev->stats.tx_packets++;
247 ndev->stats.tx_bytes += size;
248
249 skb->dev = dev = lapbeth->ethdev;
250
251 skb->protocol = htons(ETH_P_DEC);
252
253 skb_reset_network_header(skb);
254
255 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
256
257 dev_queue_xmit(skb);
258}
259
260static void lapbeth_connected(struct net_device *dev, int reason)
261{
262 struct lapbethdev *lapbeth = netdev_priv(dev);
263 unsigned char *ptr;
264 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
265
266 if (!skb) {
267 pr_err("out of memory\n");
268 return;
269 }
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
280static 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 pr_err("out of memory\n");
288 return;
289 }
290
291 ptr = skb_put(skb, 1);
292 *ptr = X25_IFACE_DISCONNECT;
293
294 skb->protocol = x25_type_trans(skb, dev);
295
296 skb_queue_tail(&lapbeth->rx_queue, skb);
297 napi_schedule(&lapbeth->napi);
298}
299
300/*
301 * Set AX.25 callsign
302 */
303static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
304{
305 struct sockaddr *sa = addr;
306 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
307 return 0;
308}
309
310
311static const struct lapb_register_struct lapbeth_callbacks = {
312 .connect_confirmation = lapbeth_connected,
313 .connect_indication = lapbeth_connected,
314 .disconnect_confirmation = lapbeth_disconnected,
315 .disconnect_indication = lapbeth_disconnected,
316 .data_indication = lapbeth_data_indication,
317 .data_transmit = lapbeth_data_transmit,
318};
319
320/*
321 * open/close a device
322 */
323static int lapbeth_open(struct net_device *dev)
324{
325 struct lapbethdev *lapbeth = netdev_priv(dev);
326 int err;
327
328 napi_enable(&lapbeth->napi);
329
330 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
331 pr_err("lapb_register error: %d\n", err);
332 return -ENODEV;
333 }
334
335 spin_lock_bh(&lapbeth->up_lock);
336 lapbeth->up = true;
337 spin_unlock_bh(&lapbeth->up_lock);
338
339 return 0;
340}
341
342static int lapbeth_close(struct net_device *dev)
343{
344 struct lapbethdev *lapbeth = netdev_priv(dev);
345 int err;
346
347 spin_lock_bh(&lapbeth->up_lock);
348 lapbeth->up = false;
349 spin_unlock_bh(&lapbeth->up_lock);
350
351 if ((err = lapb_unregister(dev)) != 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 dev->netdev_ops = &lapbeth_netdev_ops;
371 dev->needs_free_netdev = true;
372 dev->type = ARPHRD_X25;
373 dev->hard_header_len = 0;
374 dev->mtu = 1000;
375 dev->addr_len = 0;
376}
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 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
390 lapbeth_setup);
391 if (!ndev)
392 goto out;
393
394 /* When transmitting data:
395 * first this driver removes a pseudo header of 1 byte,
396 * then the lapb module prepends an LAPB header of at most 3 bytes,
397 * then this driver prepends a length field of 2 bytes,
398 * then the underlying Ethernet device prepends its own header.
399 */
400 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
401 + dev->needed_headroom;
402 ndev->needed_tailroom = dev->needed_tailroom;
403
404 lapbeth = netdev_priv(ndev);
405 lapbeth->axdev = ndev;
406
407 dev_hold(dev);
408 lapbeth->ethdev = dev;
409
410 lapbeth->up = false;
411 spin_lock_init(&lapbeth->up_lock);
412
413 skb_queue_head_init(&lapbeth->rx_queue);
414 netif_napi_add(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
415
416 rc = -EIO;
417 if (register_netdevice(ndev))
418 goto fail;
419
420 list_add_rcu(&lapbeth->node, &lapbeth_devices);
421 rc = 0;
422out:
423 return rc;
424fail:
425 dev_put(dev);
426 free_netdev(ndev);
427 goto out;
428}
429
430/*
431 * Free a lapb network device.
432 */
433static 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/*
441 * Handle device status changes.
442 *
443 * Called from notifier with RTNL held.
444 */
445static int lapbeth_device_event(struct notifier_block *this,
446 unsigned long event, void *ptr)
447{
448 struct lapbethdev *lapbeth;
449 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
450
451 if (dev_net(dev) != &init_net)
452 return NOTIFY_DONE;
453
454 if (!dev_is_ethdev(dev))
455 return NOTIFY_DONE;
456
457 switch (event) {
458 case NETDEV_UP:
459 /* New ethernet device -> new LAPB interface */
460 if (lapbeth_get_x25_dev(dev) == NULL)
461 lapbeth_new_device(dev);
462 break;
463 case NETDEV_GOING_DOWN:
464 /* ethernet device closes -> close LAPB interface */
465 lapbeth = lapbeth_get_x25_dev(dev);
466 if (lapbeth)
467 dev_close(lapbeth->axdev);
468 break;
469 case NETDEV_UNREGISTER:
470 /* ethernet device disappears -> remove LAPB interface */
471 lapbeth = lapbeth_get_x25_dev(dev);
472 if (lapbeth)
473 lapbeth_free_device(lapbeth);
474 break;
475 }
476
477 return NOTIFY_DONE;
478}
479
480/* ------------------------------------------------------------------------ */
481
482static struct packet_type lapbeth_packet_type __read_mostly = {
483 .type = cpu_to_be16(ETH_P_DEC),
484 .func = lapbeth_rcv,
485};
486
487static struct notifier_block lapbeth_dev_notifier = {
488 .notifier_call = lapbeth_device_event,
489};
490
491static const char banner[] __initconst =
492 KERN_INFO "LAPB Ethernet driver version 0.02\n";
493
494static int __init lapbeth_init_driver(void)
495{
496 dev_add_pack(&lapbeth_packet_type);
497
498 register_netdevice_notifier(&lapbeth_dev_notifier);
499
500 printk(banner);
501
502 return 0;
503}
504module_init(lapbeth_init_driver);
505
506static void __exit lapbeth_cleanup_driver(void)
507{
508 struct lapbethdev *lapbeth;
509 struct list_head *entry, *tmp;
510
511 dev_remove_pack(&lapbeth_packet_type);
512 unregister_netdevice_notifier(&lapbeth_dev_notifier);
513
514 rtnl_lock();
515 list_for_each_safe(entry, tmp, &lapbeth_devices) {
516 lapbeth = list_entry(entry, struct lapbethdev, node);
517
518 dev_put(lapbeth->ethdev);
519 unregister_netdevice(lapbeth->axdev);
520 }
521 rtnl_unlock();
522}
523module_exit(lapbeth_cleanup_driver);
524
525MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
526MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
527MODULE_LICENSE("GPL");