xref: /openbmc/linux/drivers/net/wan/lapbether.c (revision e23feb16)
1 /*
2  *	"LAPB via ethernet" driver release 001
3  *
4  *	This code REQUIRES 2.1.15 or higher/ NET3.038
5  *
6  *	This module:
7  *		This module is free software; you can redistribute it and/or
8  *		modify it under the terms of the GNU General Public License
9  *		as published by the Free Software Foundation; either version
10  *		2 of the License, or (at your option) any later version.
11  *
12  *	This is a "pseudo" network driver to allow LAPB over Ethernet.
13  *
14  *	This driver can use any ethernet destination address, and can be
15  *	limited to accept frames from one dedicated ethernet card only.
16  *
17  *	History
18  *	LAPBETH 001	Jonathan Naylor		Cloned from bpqether.c
19  *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
20  *	2000-11-14	Henner Eisen	dev_hold/put, NETDEV_GOING_DOWN support
21  */
22 
23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24 
25 #include <linux/errno.h>
26 #include <linux/types.h>
27 #include <linux/socket.h>
28 #include <linux/in.h>
29 #include <linux/slab.h>
30 #include <linux/kernel.h>
31 #include <linux/string.h>
32 #include <linux/net.h>
33 #include <linux/inet.h>
34 #include <linux/netdevice.h>
35 #include <linux/if_arp.h>
36 #include <linux/skbuff.h>
37 #include <net/sock.h>
38 #include <asm/uaccess.h>
39 #include <linux/mm.h>
40 #include <linux/interrupt.h>
41 #include <linux/notifier.h>
42 #include <linux/stat.h>
43 #include <linux/netfilter.h>
44 #include <linux/module.h>
45 #include <linux/lapb.h>
46 #include <linux/init.h>
47 
48 #include <net/x25device.h>
49 
50 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
51 
52 /* If this number is made larger, check that the temporary string buffer
53  * in lapbeth_new_device is large enough to store the probe device name.*/
54 #define MAXLAPBDEV 100
55 
56 struct lapbethdev {
57 	struct list_head	node;
58 	struct net_device	*ethdev;	/* link to ethernet device */
59 	struct net_device	*axdev;		/* lapbeth device (lapb#) */
60 };
61 
62 static LIST_HEAD(lapbeth_devices);
63 
64 /* ------------------------------------------------------------------------ */
65 
66 /*
67  *	Get the LAPB device for the ethernet device
68  */
69 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
70 {
71 	struct lapbethdev *lapbeth;
72 
73 	list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
74 		if (lapbeth->ethdev == dev)
75 			return lapbeth;
76 	}
77 	return NULL;
78 }
79 
80 static __inline__ int dev_is_ethdev(struct net_device *dev)
81 {
82 	return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
83 }
84 
85 /* ------------------------------------------------------------------------ */
86 
87 /*
88  *	Receive a LAPB frame via an ethernet interface.
89  */
90 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
91 {
92 	int len, err;
93 	struct lapbethdev *lapbeth;
94 
95 	if (dev_net(dev) != &init_net)
96 		goto drop;
97 
98 	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
99 		return NET_RX_DROP;
100 
101 	if (!pskb_may_pull(skb, 2))
102 		goto drop;
103 
104 	rcu_read_lock();
105 	lapbeth = lapbeth_get_x25_dev(dev);
106 	if (!lapbeth)
107 		goto drop_unlock;
108 	if (!netif_running(lapbeth->axdev))
109 		goto drop_unlock;
110 
111 	len = skb->data[0] + skb->data[1] * 256;
112 	dev->stats.rx_packets++;
113 	dev->stats.rx_bytes += len;
114 
115 	skb_pull(skb, 2);	/* Remove the length bytes */
116 	skb_trim(skb, len);	/* Set the length of the data */
117 
118 	if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
119 		printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
120 		goto drop_unlock;
121 	}
122 out:
123 	rcu_read_unlock();
124 	return 0;
125 drop_unlock:
126 	kfree_skb(skb);
127 	goto out;
128 drop:
129 	kfree_skb(skb);
130 	return 0;
131 }
132 
133 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
134 {
135 	unsigned char *ptr;
136 
137 	skb_push(skb, 1);
138 
139 	if (skb_cow(skb, 1))
140 		return NET_RX_DROP;
141 
142 	ptr  = skb->data;
143 	*ptr = X25_IFACE_DATA;
144 
145 	skb->protocol = x25_type_trans(skb, dev);
146 	return netif_rx(skb);
147 }
148 
149 /*
150  *	Send a LAPB frame via an ethernet interface
151  */
152 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
153 				      struct net_device *dev)
154 {
155 	int err;
156 
157 	/*
158 	 * Just to be *really* sure not to send anything if the interface
159 	 * is down, the ethernet device may have gone.
160 	 */
161 	if (!netif_running(dev))
162 		goto drop;
163 
164 	switch (skb->data[0]) {
165 	case X25_IFACE_DATA:
166 		break;
167 	case X25_IFACE_CONNECT:
168 		if ((err = lapb_connect_request(dev)) != LAPB_OK)
169 			pr_err("lapb_connect_request error: %d\n", err);
170 		goto drop;
171 	case X25_IFACE_DISCONNECT:
172 		if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
173 			pr_err("lapb_disconnect_request err: %d\n", err);
174 		/* Fall thru */
175 	default:
176 		goto drop;
177 	}
178 
179 	skb_pull(skb, 1);
180 
181 	if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
182 		pr_err("lapb_data_request error - %d\n", err);
183 		goto drop;
184 	}
185 out:
186 	return NETDEV_TX_OK;
187 drop:
188 	kfree_skb(skb);
189 	goto out;
190 }
191 
192 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
193 {
194 	struct lapbethdev *lapbeth = netdev_priv(ndev);
195 	unsigned char *ptr;
196 	struct net_device *dev;
197 	int size = skb->len;
198 
199 	skb->protocol = htons(ETH_P_X25);
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 	dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
212 
213 	dev_queue_xmit(skb);
214 }
215 
216 static void lapbeth_connected(struct net_device *dev, int reason)
217 {
218 	unsigned char *ptr;
219 	struct sk_buff *skb = dev_alloc_skb(1);
220 
221 	if (!skb) {
222 		pr_err("out of memory\n");
223 		return;
224 	}
225 
226 	ptr  = skb_put(skb, 1);
227 	*ptr = X25_IFACE_CONNECT;
228 
229 	skb->protocol = x25_type_trans(skb, dev);
230 	netif_rx(skb);
231 }
232 
233 static void lapbeth_disconnected(struct net_device *dev, int reason)
234 {
235 	unsigned char *ptr;
236 	struct sk_buff *skb = dev_alloc_skb(1);
237 
238 	if (!skb) {
239 		pr_err("out of memory\n");
240 		return;
241 	}
242 
243 	ptr  = skb_put(skb, 1);
244 	*ptr = X25_IFACE_DISCONNECT;
245 
246 	skb->protocol = x25_type_trans(skb, dev);
247 	netif_rx(skb);
248 }
249 
250 /*
251  *	Set AX.25 callsign
252  */
253 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
254 {
255 	struct sockaddr *sa = addr;
256 	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
257 	return 0;
258 }
259 
260 
261 static const struct lapb_register_struct lapbeth_callbacks = {
262 	.connect_confirmation    = lapbeth_connected,
263 	.connect_indication      = lapbeth_connected,
264 	.disconnect_confirmation = lapbeth_disconnected,
265 	.disconnect_indication   = lapbeth_disconnected,
266 	.data_indication         = lapbeth_data_indication,
267 	.data_transmit           = lapbeth_data_transmit,
268 };
269 
270 /*
271  * open/close a device
272  */
273 static int lapbeth_open(struct net_device *dev)
274 {
275 	int err;
276 
277 	if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
278 		pr_err("lapb_register error: %d\n", err);
279 		return -ENODEV;
280 	}
281 
282 	netif_start_queue(dev);
283 	return 0;
284 }
285 
286 static int lapbeth_close(struct net_device *dev)
287 {
288 	int err;
289 
290 	netif_stop_queue(dev);
291 
292 	if ((err = lapb_unregister(dev)) != LAPB_OK)
293 		pr_err("lapb_unregister error: %d\n", err);
294 
295 	return 0;
296 }
297 
298 /* ------------------------------------------------------------------------ */
299 
300 static const struct net_device_ops lapbeth_netdev_ops = {
301 	.ndo_open	     = lapbeth_open,
302 	.ndo_stop	     = lapbeth_close,
303 	.ndo_start_xmit	     = lapbeth_xmit,
304 	.ndo_set_mac_address = lapbeth_set_mac_address,
305 };
306 
307 static void lapbeth_setup(struct net_device *dev)
308 {
309 	dev->netdev_ops	     = &lapbeth_netdev_ops;
310 	dev->destructor	     = free_netdev;
311 	dev->type            = ARPHRD_X25;
312 	dev->hard_header_len = 3;
313 	dev->mtu             = 1000;
314 	dev->addr_len        = 0;
315 }
316 
317 /*
318  *	Setup a new device.
319  */
320 static int lapbeth_new_device(struct net_device *dev)
321 {
322 	struct net_device *ndev;
323 	struct lapbethdev *lapbeth;
324 	int rc = -ENOMEM;
325 
326 	ASSERT_RTNL();
327 
328 	ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d",
329 			   lapbeth_setup);
330 	if (!ndev)
331 		goto out;
332 
333 	lapbeth = netdev_priv(ndev);
334 	lapbeth->axdev = ndev;
335 
336 	dev_hold(dev);
337 	lapbeth->ethdev = dev;
338 
339 	rc = -EIO;
340 	if (register_netdevice(ndev))
341 		goto fail;
342 
343 	list_add_rcu(&lapbeth->node, &lapbeth_devices);
344 	rc = 0;
345 out:
346 	return rc;
347 fail:
348 	dev_put(dev);
349 	free_netdev(ndev);
350 	kfree(lapbeth);
351 	goto out;
352 }
353 
354 /*
355  *	Free a lapb network device.
356  */
357 static 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  */
369 static 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 
406 static struct packet_type lapbeth_packet_type __read_mostly = {
407 	.type = cpu_to_be16(ETH_P_DEC),
408 	.func = lapbeth_rcv,
409 };
410 
411 static struct notifier_block lapbeth_dev_notifier = {
412 	.notifier_call = lapbeth_device_event,
413 };
414 
415 static const char banner[] __initconst =
416 	KERN_INFO "LAPB Ethernet driver version 0.02\n";
417 
418 static 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 }
428 module_init(lapbeth_init_driver);
429 
430 static 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 }
447 module_exit(lapbeth_cleanup_driver);
448 
449 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
450 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
451 MODULE_LICENSE("GPL");
452