xref: /openbmc/linux/drivers/net/hamradio/bpqether.c (revision 22246614)
1 /*
2  *	G8BPQ compatible "AX.25 via ethernet" driver release 004
3  *
4  *	This code REQUIRES 2.0.0 or higher/ NET3.029
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 AX.25 over Ethernet
13  *	using G8BPQ encapsulation. It has been extracted from the protocol
14  *	implementation because
15  *
16  *		- things got unreadable within the protocol stack
17  *		- to cure the protocol stack from "feature-ism"
18  *		- a protocol implementation shouldn't need to know on
19  *		  which hardware it is running
20  *		- user-level programs like the AX.25 utilities shouldn't
21  *		  need to know about the hardware.
22  *		- IP over ethernet encapsulated AX.25 was impossible
23  *		- rxecho.c did not work
24  *		- to have room for extensions
25  *		- it just deserves to "live" as an own driver
26  *
27  *	This driver can use any ethernet destination address, and can be
28  *	limited to accept frames from one dedicated ethernet card only.
29  *
30  *	Note that the driver sets up the BPQ devices automagically on
31  *	startup or (if started before the "insmod" of an ethernet device)
32  *	on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing
33  *	the ethernet device (in fact: as soon as another ethernet or bpq
34  *	device gets "ifconfig"ured).
35  *
36  *	I have heard that several people are thinking of experiments
37  *	with highspeed packet radio using existing ethernet cards.
38  *	Well, this driver is prepared for this purpose, just add
39  *	your tx key control and a txdelay / tailtime algorithm,
40  *	probably some buffering, and /voila/...
41  *
42  *	History
43  *	BPQ   001	Joerg(DL1BKE)		Extracted BPQ code from AX.25
44  *						protocol stack and added my own
45  *						yet existing patches
46  *	BPQ   002	Joerg(DL1BKE)		Scan network device list on
47  *						startup.
48  *	BPQ   003	Joerg(DL1BKE)		Ethernet destination address
49  *						and accepted source address
50  *						can be configured by an ioctl()
51  *						call.
52  *						Fixed to match Linux networking
53  *						changes - 2.1.15.
54  *	BPQ   004	Joerg(DL1BKE)		Fixed to not lock up on ifconfig.
55  */
56 
57 #include <linux/errno.h>
58 #include <linux/types.h>
59 #include <linux/socket.h>
60 #include <linux/in.h>
61 #include <linux/kernel.h>
62 #include <linux/string.h>
63 #include <linux/net.h>
64 #include <net/ax25.h>
65 #include <linux/inet.h>
66 #include <linux/netdevice.h>
67 #include <linux/etherdevice.h>
68 #include <linux/if_arp.h>
69 #include <linux/skbuff.h>
70 #include <net/sock.h>
71 #include <asm/system.h>
72 #include <asm/uaccess.h>
73 #include <linux/mm.h>
74 #include <linux/interrupt.h>
75 #include <linux/notifier.h>
76 #include <linux/proc_fs.h>
77 #include <linux/seq_file.h>
78 #include <linux/stat.h>
79 #include <linux/netfilter.h>
80 #include <linux/module.h>
81 #include <linux/init.h>
82 #include <linux/rtnetlink.h>
83 
84 #include <net/ip.h>
85 #include <net/arp.h>
86 #include <net/net_namespace.h>
87 
88 #include <linux/bpqether.h>
89 
90 static char banner[] __initdata = KERN_INFO "AX.25: bpqether driver version 004\n";
91 
92 static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
93 
94 static char bpq_eth_addr[6];
95 
96 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
97 static int bpq_device_event(struct notifier_block *, unsigned long, void *);
98 
99 static struct packet_type bpq_packet_type = {
100 	.type	= __constant_htons(ETH_P_BPQ),
101 	.func	= bpq_rcv,
102 };
103 
104 static struct notifier_block bpq_dev_notifier = {
105 	.notifier_call =bpq_device_event,
106 };
107 
108 
109 struct bpqdev {
110 	struct list_head bpq_list;	/* list of bpq devices chain */
111 	struct net_device *ethdev;	/* link to ethernet device */
112 	struct net_device *axdev;	/* bpq device (bpq#) */
113 	struct net_device_stats stats;	/* some statistics */
114 	char   dest_addr[6];		/* ether destination address */
115 	char   acpt_addr[6];		/* accept ether frames from this address only */
116 };
117 
118 static LIST_HEAD(bpq_devices);
119 
120 /*
121  * bpqether network devices are paired with ethernet devices below them, so
122  * form a special "super class" of normal ethernet devices; split their locks
123  * off into a separate class since they always nest.
124  */
125 static struct lock_class_key bpq_netdev_xmit_lock_key;
126 
127 /* ------------------------------------------------------------------------ */
128 
129 
130 /*
131  *	Get the ethernet device for a BPQ device
132  */
133 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev)
134 {
135 	struct bpqdev *bpq = netdev_priv(dev);
136 
137 	return bpq ? bpq->ethdev : NULL;
138 }
139 
140 /*
141  *	Get the BPQ device for the ethernet device
142  */
143 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
144 {
145 	struct bpqdev *bpq;
146 
147 	list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
148 		if (bpq->ethdev == dev)
149 			return bpq->axdev;
150 	}
151 	return NULL;
152 }
153 
154 static inline int dev_is_ethdev(struct net_device *dev)
155 {
156 	return (
157 			dev->type == ARPHRD_ETHER
158 			&& strncmp(dev->name, "dummy", 5)
159 	);
160 }
161 
162 /* ------------------------------------------------------------------------ */
163 
164 
165 /*
166  *	Receive an AX.25 frame via an ethernet interface.
167  */
168 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
169 {
170 	int len;
171 	char * ptr;
172 	struct ethhdr *eth;
173 	struct bpqdev *bpq;
174 
175 	if (dev_net(dev) != &init_net)
176 		goto drop;
177 
178 	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
179 		return NET_RX_DROP;
180 
181 	if (!pskb_may_pull(skb, sizeof(struct ethhdr)))
182 		goto drop;
183 
184 	rcu_read_lock();
185 	dev = bpq_get_ax25_dev(dev);
186 
187 	if (dev == NULL || !netif_running(dev))
188 		goto drop_unlock;
189 
190 	/*
191 	 * if we want to accept frames from just one ethernet device
192 	 * we check the source address of the sender.
193 	 */
194 
195 	bpq = netdev_priv(dev);
196 
197 	eth = eth_hdr(skb);
198 
199 	if (!(bpq->acpt_addr[0] & 0x01) &&
200 	    memcmp(eth->h_source, bpq->acpt_addr, ETH_ALEN))
201 		goto drop_unlock;
202 
203 	if (skb_cow(skb, sizeof(struct ethhdr)))
204 		goto drop_unlock;
205 
206 	len = skb->data[0] + skb->data[1] * 256 - 5;
207 
208 	skb_pull(skb, 2);	/* Remove the length bytes */
209 	skb_trim(skb, len);	/* Set the length of the data */
210 
211 	bpq->stats.rx_packets++;
212 	bpq->stats.rx_bytes += len;
213 
214 	ptr = skb_push(skb, 1);
215 	*ptr = 0;
216 
217 	skb->protocol = ax25_type_trans(skb, dev);
218 	netif_rx(skb);
219 	dev->last_rx = jiffies;
220 unlock:
221 
222 	rcu_read_unlock();
223 
224 	return 0;
225 drop_unlock:
226 	kfree_skb(skb);
227 	goto unlock;
228 
229 drop:
230 	kfree_skb(skb);
231 	return 0;
232 }
233 
234 /*
235  * 	Send an AX.25 frame via an ethernet interface
236  */
237 static int bpq_xmit(struct sk_buff *skb, struct net_device *dev)
238 {
239 	struct sk_buff *newskb;
240 	unsigned char *ptr;
241 	struct bpqdev *bpq;
242 	int size;
243 
244 	/*
245 	 * Just to be *really* sure not to send anything if the interface
246 	 * is down, the ethernet device may have gone.
247 	 */
248 	if (!netif_running(dev)) {
249 		kfree_skb(skb);
250 		return -ENODEV;
251 	}
252 
253 	skb_pull(skb, 1);
254 	size = skb->len;
255 
256 	/*
257 	 * The AX.25 code leaves enough room for the ethernet header, but
258 	 * sendto() does not.
259 	 */
260 	if (skb_headroom(skb) < AX25_BPQ_HEADER_LEN) {	/* Ough! */
261 		if ((newskb = skb_realloc_headroom(skb, AX25_BPQ_HEADER_LEN)) == NULL) {
262 			printk(KERN_WARNING "bpqether: out of memory\n");
263 			kfree_skb(skb);
264 			return -ENOMEM;
265 		}
266 
267 		if (skb->sk != NULL)
268 			skb_set_owner_w(newskb, skb->sk);
269 
270 		kfree_skb(skb);
271 		skb = newskb;
272 	}
273 
274 	ptr = skb_push(skb, 2);
275 
276 	*ptr++ = (size + 5) % 256;
277 	*ptr++ = (size + 5) / 256;
278 
279 	bpq = netdev_priv(dev);
280 
281 	if ((dev = bpq_get_ether_dev(dev)) == NULL) {
282 		bpq->stats.tx_dropped++;
283 		kfree_skb(skb);
284 		return -ENODEV;
285 	}
286 
287 	skb->protocol = ax25_type_trans(skb, dev);
288 	skb_reset_network_header(skb);
289 	dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);
290 	bpq->stats.tx_packets++;
291 	bpq->stats.tx_bytes+=skb->len;
292 
293 	dev_queue_xmit(skb);
294 	netif_wake_queue(dev);
295 	return 0;
296 }
297 
298 /*
299  *	Statistics
300  */
301 static struct net_device_stats *bpq_get_stats(struct net_device *dev)
302 {
303 	struct bpqdev *bpq = netdev_priv(dev);
304 
305 	return &bpq->stats;
306 }
307 
308 /*
309  *	Set AX.25 callsign
310  */
311 static int bpq_set_mac_address(struct net_device *dev, void *addr)
312 {
313     struct sockaddr *sa = (struct sockaddr *)addr;
314 
315     memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
316 
317     return 0;
318 }
319 
320 /*	Ioctl commands
321  *
322  *		SIOCSBPQETHOPT		reserved for enhancements
323  *		SIOCSBPQETHADDR		set the destination and accepted
324  *					source ethernet address (broadcast
325  *					or multicast: accept all)
326  */
327 static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
328 {
329 	struct bpq_ethaddr __user *ethaddr = ifr->ifr_data;
330 	struct bpqdev *bpq = netdev_priv(dev);
331 	struct bpq_req req;
332 
333 	if (!capable(CAP_NET_ADMIN))
334 		return -EPERM;
335 
336 	switch (cmd) {
337 		case SIOCSBPQETHOPT:
338 			if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req)))
339 				return -EFAULT;
340 			switch (req.cmd) {
341 				case SIOCGBPQETHPARAM:
342 				case SIOCSBPQETHPARAM:
343 				default:
344 					return -EINVAL;
345 			}
346 
347 			break;
348 
349 		case SIOCSBPQETHADDR:
350 			if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
351 				return -EFAULT;
352 			if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
353 				return -EFAULT;
354 			break;
355 
356 		default:
357 			return -EINVAL;
358 	}
359 
360 	return 0;
361 }
362 
363 /*
364  * open/close a device
365  */
366 static int bpq_open(struct net_device *dev)
367 {
368 	netif_start_queue(dev);
369 	return 0;
370 }
371 
372 static int bpq_close(struct net_device *dev)
373 {
374 	netif_stop_queue(dev);
375 	return 0;
376 }
377 
378 
379 /* ------------------------------------------------------------------------ */
380 
381 
382 /*
383  *	Proc filesystem
384  */
385 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
386 {
387 	int i = 1;
388 	struct bpqdev *bpqdev;
389 
390 	rcu_read_lock();
391 
392 	if (*pos == 0)
393 		return SEQ_START_TOKEN;
394 
395 	list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
396 		if (i == *pos)
397 			return bpqdev;
398 	}
399 	return NULL;
400 }
401 
402 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
403 {
404 	struct list_head *p;
405 
406 	++*pos;
407 
408 	if (v == SEQ_START_TOKEN)
409 		p = rcu_dereference(bpq_devices.next);
410 	else
411 		p = rcu_dereference(((struct bpqdev *)v)->bpq_list.next);
412 
413 	return (p == &bpq_devices) ? NULL
414 		: list_entry(p, struct bpqdev, bpq_list);
415 }
416 
417 static void bpq_seq_stop(struct seq_file *seq, void *v)
418 {
419 	rcu_read_unlock();
420 }
421 
422 
423 static int bpq_seq_show(struct seq_file *seq, void *v)
424 {
425 	if (v == SEQ_START_TOKEN)
426 		seq_puts(seq,
427 			 "dev   ether      destination        accept from\n");
428 	else {
429 		const struct bpqdev *bpqdev = v;
430 		DECLARE_MAC_BUF(mac);
431 
432 		seq_printf(seq, "%-5s %-10s %s  ",
433 			bpqdev->axdev->name, bpqdev->ethdev->name,
434 			print_mac(mac, bpqdev->dest_addr));
435 
436 		if (is_multicast_ether_addr(bpqdev->acpt_addr))
437 			seq_printf(seq, "*\n");
438 		else
439 			seq_printf(seq, "%s\n", print_mac(mac, bpqdev->acpt_addr));
440 
441 	}
442 	return 0;
443 }
444 
445 static struct seq_operations bpq_seqops = {
446 	.start = bpq_seq_start,
447 	.next = bpq_seq_next,
448 	.stop = bpq_seq_stop,
449 	.show = bpq_seq_show,
450 };
451 
452 static int bpq_info_open(struct inode *inode, struct file *file)
453 {
454 	return seq_open(file, &bpq_seqops);
455 }
456 
457 static const struct file_operations bpq_info_fops = {
458 	.owner = THIS_MODULE,
459 	.open = bpq_info_open,
460 	.read = seq_read,
461 	.llseek = seq_lseek,
462 	.release = seq_release,
463 };
464 
465 
466 /* ------------------------------------------------------------------------ */
467 
468 
469 static void bpq_setup(struct net_device *dev)
470 {
471 
472 	dev->hard_start_xmit = bpq_xmit;
473 	dev->open	     = bpq_open;
474 	dev->stop	     = bpq_close;
475 	dev->set_mac_address = bpq_set_mac_address;
476 	dev->get_stats	     = bpq_get_stats;
477 	dev->do_ioctl	     = bpq_ioctl;
478 	dev->destructor	     = free_netdev;
479 
480 	memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
481 	memcpy(dev->dev_addr,  &ax25_defaddr, AX25_ADDR_LEN);
482 
483 	dev->flags      = 0;
484 
485 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
486 	dev->header_ops      = &ax25_header_ops;
487 #endif
488 
489 	dev->type            = ARPHRD_AX25;
490 	dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
491 	dev->mtu             = AX25_DEF_PACLEN;
492 	dev->addr_len        = AX25_ADDR_LEN;
493 
494 }
495 
496 /*
497  *	Setup a new device.
498  */
499 static int bpq_new_device(struct net_device *edev)
500 {
501 	int err;
502 	struct net_device *ndev;
503 	struct bpqdev *bpq;
504 
505 	ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d",
506 			   bpq_setup);
507 	if (!ndev)
508 		return -ENOMEM;
509 
510 
511 	bpq = netdev_priv(ndev);
512 	dev_hold(edev);
513 	bpq->ethdev = edev;
514 	bpq->axdev = ndev;
515 
516 	memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr));
517 	memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr));
518 
519 	err = dev_alloc_name(ndev, ndev->name);
520 	if (err < 0)
521 		goto error;
522 
523 	err = register_netdevice(ndev);
524 	if (err)
525 		goto error;
526 	lockdep_set_class(&ndev->_xmit_lock, &bpq_netdev_xmit_lock_key);
527 
528 	/* List protected by RTNL */
529 	list_add_rcu(&bpq->bpq_list, &bpq_devices);
530 	return 0;
531 
532  error:
533 	dev_put(edev);
534 	free_netdev(ndev);
535 	return err;
536 
537 }
538 
539 static void bpq_free_device(struct net_device *ndev)
540 {
541 	struct bpqdev *bpq = netdev_priv(ndev);
542 
543 	dev_put(bpq->ethdev);
544 	list_del_rcu(&bpq->bpq_list);
545 
546 	unregister_netdevice(ndev);
547 }
548 
549 /*
550  *	Handle device status changes.
551  */
552 static int bpq_device_event(struct notifier_block *this,unsigned long event, void *ptr)
553 {
554 	struct net_device *dev = (struct net_device *)ptr;
555 
556 	if (dev_net(dev) != &init_net)
557 		return NOTIFY_DONE;
558 
559 	if (!dev_is_ethdev(dev))
560 		return NOTIFY_DONE;
561 
562 	switch (event) {
563 	case NETDEV_UP:		/* new ethernet device -> new BPQ interface */
564 		if (bpq_get_ax25_dev(dev) == NULL)
565 			bpq_new_device(dev);
566 		break;
567 
568 	case NETDEV_DOWN:	/* ethernet device closed -> close BPQ interface */
569 		if ((dev = bpq_get_ax25_dev(dev)) != NULL)
570 			dev_close(dev);
571 		break;
572 
573 	case NETDEV_UNREGISTER:	/* ethernet device removed -> free BPQ interface */
574 		if ((dev = bpq_get_ax25_dev(dev)) != NULL)
575 			bpq_free_device(dev);
576 		break;
577 	default:
578 		break;
579 	}
580 
581 	return NOTIFY_DONE;
582 }
583 
584 
585 /* ------------------------------------------------------------------------ */
586 
587 /*
588  * Initialize driver. To be called from af_ax25 if not compiled as a
589  * module
590  */
591 static int __init bpq_init_driver(void)
592 {
593 #ifdef CONFIG_PROC_FS
594 	if (!proc_net_fops_create(&init_net, "bpqether", S_IRUGO, &bpq_info_fops)) {
595 		printk(KERN_ERR
596 			"bpq: cannot create /proc/net/bpqether entry.\n");
597 		return -ENOENT;
598 	}
599 #endif  /* CONFIG_PROC_FS */
600 
601 	dev_add_pack(&bpq_packet_type);
602 
603 	register_netdevice_notifier(&bpq_dev_notifier);
604 
605 	printk(banner);
606 
607 	return 0;
608 }
609 
610 static void __exit bpq_cleanup_driver(void)
611 {
612 	struct bpqdev *bpq;
613 
614 	dev_remove_pack(&bpq_packet_type);
615 
616 	unregister_netdevice_notifier(&bpq_dev_notifier);
617 
618 	proc_net_remove(&init_net, "bpqether");
619 
620 	rtnl_lock();
621 	while (!list_empty(&bpq_devices)) {
622 		bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list);
623 		bpq_free_device(bpq->axdev);
624 	}
625 	rtnl_unlock();
626 }
627 
628 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");
629 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
630 MODULE_LICENSE("GPL");
631 module_init(bpq_init_driver);
632 module_exit(bpq_cleanup_driver);
633