tjh.dev
Linux kernel mirror (for testing)
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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};
55
56static LIST_HEAD(lapbeth_devices);
57
58/* ------------------------------------------------------------------------ */
59
60/*
61 * Get the LAPB device for the ethernet device
62 */
63static 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
74static __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 */
84static 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 }
116out:
117 rcu_read_unlock();
118 return 0;
119drop_unlock:
120 kfree_skb(skb);
121 goto out;
122drop:
123 kfree_skb(skb);
124 return 0;
125}
126
127static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
128{
129 unsigned char *ptr;
130
131 skb_push(skb, 1);
132
133 if (skb_cow(skb, 1))
134 return NET_RX_DROP;
135
136 ptr = skb->data;
137 *ptr = X25_IFACE_DATA;
138
139 skb->protocol = x25_type_trans(skb, dev);
140 return netif_rx(skb);
141}
142
143/*
144 * Send a LAPB frame via an ethernet interface
145 */
146static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
147 struct net_device *dev)
148{
149 int err;
150
151 /*
152 * Just to be *really* sure not to send anything if the interface
153 * is down, the ethernet device may have gone.
154 */
155 if (!netif_running(dev))
156 goto drop;
157
158 switch (skb->data[0]) {
159 case X25_IFACE_DATA:
160 break;
161 case X25_IFACE_CONNECT:
162 if ((err = lapb_connect_request(dev)) != LAPB_OK)
163 pr_err("lapb_connect_request error: %d\n", err);
164 goto drop;
165 case X25_IFACE_DISCONNECT:
166 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
167 pr_err("lapb_disconnect_request err: %d\n", err);
168 /* Fall thru */
169 default:
170 goto drop;
171 }
172
173 skb_pull(skb, 1);
174
175 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
176 pr_err("lapb_data_request error - %d\n", err);
177 goto drop;
178 }
179out:
180 return NETDEV_TX_OK;
181drop:
182 kfree_skb(skb);
183 goto out;
184}
185
186static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
187{
188 struct lapbethdev *lapbeth = netdev_priv(ndev);
189 unsigned char *ptr;
190 struct net_device *dev;
191 int size = skb->len;
192
193 skb->protocol = htons(ETH_P_X25);
194
195 ptr = skb_push(skb, 2);
196
197 *ptr++ = size % 256;
198 *ptr++ = size / 256;
199
200 ndev->stats.tx_packets++;
201 ndev->stats.tx_bytes += size;
202
203 skb->dev = dev = lapbeth->ethdev;
204
205 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
206
207 dev_queue_xmit(skb);
208}
209
210static void lapbeth_connected(struct net_device *dev, int reason)
211{
212 unsigned char *ptr;
213 struct sk_buff *skb = dev_alloc_skb(1);
214
215 if (!skb) {
216 pr_err("out of memory\n");
217 return;
218 }
219
220 ptr = skb_put(skb, 1);
221 *ptr = X25_IFACE_CONNECT;
222
223 skb->protocol = x25_type_trans(skb, dev);
224 netif_rx(skb);
225}
226
227static void lapbeth_disconnected(struct net_device *dev, int reason)
228{
229 unsigned char *ptr;
230 struct sk_buff *skb = dev_alloc_skb(1);
231
232 if (!skb) {
233 pr_err("out of memory\n");
234 return;
235 }
236
237 ptr = skb_put(skb, 1);
238 *ptr = X25_IFACE_DISCONNECT;
239
240 skb->protocol = x25_type_trans(skb, dev);
241 netif_rx(skb);
242}
243
244/*
245 * Set AX.25 callsign
246 */
247static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
248{
249 struct sockaddr *sa = addr;
250 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
251 return 0;
252}
253
254
255static const struct lapb_register_struct lapbeth_callbacks = {
256 .connect_confirmation = lapbeth_connected,
257 .connect_indication = lapbeth_connected,
258 .disconnect_confirmation = lapbeth_disconnected,
259 .disconnect_indication = lapbeth_disconnected,
260 .data_indication = lapbeth_data_indication,
261 .data_transmit = lapbeth_data_transmit,
262};
263
264/*
265 * open/close a device
266 */
267static int lapbeth_open(struct net_device *dev)
268{
269 int err;
270
271 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
272 pr_err("lapb_register error: %d\n", err);
273 return -ENODEV;
274 }
275
276 netif_start_queue(dev);
277 return 0;
278}
279
280static int lapbeth_close(struct net_device *dev)
281{
282 int err;
283
284 netif_stop_queue(dev);
285
286 if ((err = lapb_unregister(dev)) != LAPB_OK)
287 pr_err("lapb_unregister error: %d\n", err);
288
289 return 0;
290}
291
292/* ------------------------------------------------------------------------ */
293
294static const struct net_device_ops lapbeth_netdev_ops = {
295 .ndo_open = lapbeth_open,
296 .ndo_stop = lapbeth_close,
297 .ndo_start_xmit = lapbeth_xmit,
298 .ndo_set_mac_address = lapbeth_set_mac_address,
299};
300
301static void lapbeth_setup(struct net_device *dev)
302{
303 dev->netdev_ops = &lapbeth_netdev_ops;
304 dev->needs_free_netdev = true;
305 dev->type = ARPHRD_X25;
306 dev->mtu = 1000;
307 dev->addr_len = 0;
308}
309
310/*
311 * Setup a new device.
312 */
313static int lapbeth_new_device(struct net_device *dev)
314{
315 struct net_device *ndev;
316 struct lapbethdev *lapbeth;
317 int rc = -ENOMEM;
318
319 ASSERT_RTNL();
320
321 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
322 lapbeth_setup);
323 if (!ndev)
324 goto out;
325
326 /* When transmitting data:
327 * first this driver removes a pseudo header of 1 byte,
328 * then the lapb module prepends an LAPB header of at most 3 bytes,
329 * then this driver prepends a length field of 2 bytes,
330 * then the underlying Ethernet device prepends its own header.
331 */
332 ndev->hard_header_len = -1 + 3 + 2 + dev->hard_header_len;
333
334 lapbeth = netdev_priv(ndev);
335 lapbeth->axdev = ndev;
336
337 dev_hold(dev);
338 lapbeth->ethdev = dev;
339
340 rc = -EIO;
341 if (register_netdevice(ndev))
342 goto fail;
343
344 list_add_rcu(&lapbeth->node, &lapbeth_devices);
345 rc = 0;
346out:
347 return rc;
348fail:
349 dev_put(dev);
350 free_netdev(ndev);
351 goto out;
352}
353
354/*
355 * Free a lapb network device.
356 */
357static void lapbeth_free_device(struct lapbethdev *lapbeth)
358{
359 dev_put(lapbeth->ethdev);
360 list_del_rcu(&lapbeth->node);
361 unregister_netdevice(lapbeth->axdev);
362}
363
364/*
365 * Handle device status changes.
366 *
367 * Called from notifier with RTNL held.
368 */
369static int lapbeth_device_event(struct notifier_block *this,
370 unsigned long event, void *ptr)
371{
372 struct lapbethdev *lapbeth;
373 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
374
375 if (dev_net(dev) != &init_net)
376 return NOTIFY_DONE;
377
378 if (!dev_is_ethdev(dev))
379 return NOTIFY_DONE;
380
381 switch (event) {
382 case NETDEV_UP:
383 /* New ethernet device -> new LAPB interface */
384 if (lapbeth_get_x25_dev(dev) == NULL)
385 lapbeth_new_device(dev);
386 break;
387 case NETDEV_DOWN:
388 /* ethernet device closed -> close LAPB interface */
389 lapbeth = lapbeth_get_x25_dev(dev);
390 if (lapbeth)
391 dev_close(lapbeth->axdev);
392 break;
393 case NETDEV_UNREGISTER:
394 /* ethernet device disappears -> remove LAPB interface */
395 lapbeth = lapbeth_get_x25_dev(dev);
396 if (lapbeth)
397 lapbeth_free_device(lapbeth);
398 break;
399 }
400
401 return NOTIFY_DONE;
402}
403
404/* ------------------------------------------------------------------------ */
405
406static struct packet_type lapbeth_packet_type __read_mostly = {
407 .type = cpu_to_be16(ETH_P_DEC),
408 .func = lapbeth_rcv,
409};
410
411static struct notifier_block lapbeth_dev_notifier = {
412 .notifier_call = lapbeth_device_event,
413};
414
415static const char banner[] __initconst =
416 KERN_INFO "LAPB Ethernet driver version 0.02\n";
417
418static int __init lapbeth_init_driver(void)
419{
420 dev_add_pack(&lapbeth_packet_type);
421
422 register_netdevice_notifier(&lapbeth_dev_notifier);
423
424 printk(banner);
425
426 return 0;
427}
428module_init(lapbeth_init_driver);
429
430static void __exit lapbeth_cleanup_driver(void)
431{
432 struct lapbethdev *lapbeth;
433 struct list_head *entry, *tmp;
434
435 dev_remove_pack(&lapbeth_packet_type);
436 unregister_netdevice_notifier(&lapbeth_dev_notifier);
437
438 rtnl_lock();
439 list_for_each_safe(entry, tmp, &lapbeth_devices) {
440 lapbeth = list_entry(entry, struct lapbethdev, node);
441
442 dev_put(lapbeth->ethdev);
443 unregister_netdevice(lapbeth->axdev);
444 }
445 rtnl_unlock();
446}
447module_exit(lapbeth_cleanup_driver);
448
449MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
450MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
451MODULE_LICENSE("GPL");