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 <linux/slab.h>
65#include <net/ax25.h>
66#include <linux/inet.h>
67#include <linux/netdevice.h>
68#include <linux/etherdevice.h>
69#include <linux/if_arp.h>
70#include <linux/skbuff.h>
71#include <net/sock.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/module.h>
80#include <linux/init.h>
81#include <linux/rtnetlink.h>
82
83#include <net/ip.h>
84#include <net/arp.h>
85#include <net/net_namespace.h>
86
87#include <linux/bpqether.h>
88
89static const char banner[] __initconst = KERN_INFO \
90	"AX.25: bpqether driver version 004\n";
91
92static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
93
94static char bpq_eth_addr[6];
95
96static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
97static int bpq_device_event(struct notifier_block *, unsigned long, void *);
98
99static struct packet_type bpq_packet_type __read_mostly = {
100	.type	= cpu_to_be16(ETH_P_BPQ),
101	.func	= bpq_rcv,
102};
103
104static struct notifier_block bpq_dev_notifier = {
105	.notifier_call = bpq_device_event,
106};
107
108
109struct 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	char   dest_addr[6];		/* ether destination address */
114	char   acpt_addr[6];		/* accept ether frames from this address only */
115};
116
117static LIST_HEAD(bpq_devices);
118
119/*
120 * bpqether network devices are paired with ethernet devices below them, so
121 * form a special "super class" of normal ethernet devices; split their locks
122 * off into a separate class since they always nest.
123 */
124static struct lock_class_key bpq_netdev_xmit_lock_key;
125static struct lock_class_key bpq_netdev_addr_lock_key;
126
127static void bpq_set_lockdep_class_one(struct net_device *dev,
128				      struct netdev_queue *txq,
129				      void *_unused)
130{
131	lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key);
132}
133
134static void bpq_set_lockdep_class(struct net_device *dev)
135{
136	lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key);
137	netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL);
138}
139
140/* ------------------------------------------------------------------------ */
141
142
143/*
144 *	Get the ethernet device for a BPQ device
145 */
146static inline struct net_device *bpq_get_ether_dev(struct net_device *dev)
147{
148	struct bpqdev *bpq = netdev_priv(dev);
149
150	return bpq ? bpq->ethdev : NULL;
151}
152
153/*
154 *	Get the BPQ device for the ethernet device
155 */
156static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
157{
158	struct bpqdev *bpq;
159
160	list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
161		if (bpq->ethdev == dev)
162			return bpq->axdev;
163	}
164	return NULL;
165}
166
167static inline int dev_is_ethdev(struct net_device *dev)
168{
169	return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
170}
171
172/* ------------------------------------------------------------------------ */
173
174
175/*
176 *	Receive an AX.25 frame via an ethernet interface.
177 */
178static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
179{
180	int len;
181	char * ptr;
182	struct ethhdr *eth;
183	struct bpqdev *bpq;
184
185	if (!net_eq(dev_net(dev), &init_net))
186		goto drop;
187
188	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
189		return NET_RX_DROP;
190
191	if (!pskb_may_pull(skb, sizeof(struct ethhdr)))
192		goto drop;
193
194	rcu_read_lock();
195	dev = bpq_get_ax25_dev(dev);
196
197	if (dev == NULL || !netif_running(dev))
198		goto drop_unlock;
199
200	/*
201	 * if we want to accept frames from just one ethernet device
202	 * we check the source address of the sender.
203	 */
204
205	bpq = netdev_priv(dev);
206
207	eth = eth_hdr(skb);
208
209	if (!(bpq->acpt_addr[0] & 0x01) &&
210	    !ether_addr_equal(eth->h_source, bpq->acpt_addr))
211		goto drop_unlock;
212
213	if (skb_cow(skb, sizeof(struct ethhdr)))
214		goto drop_unlock;
215
216	len = skb->data[0] + skb->data[1] * 256 - 5;
217
218	skb_pull(skb, 2);	/* Remove the length bytes */
219	skb_trim(skb, len);	/* Set the length of the data */
220
221	dev->stats.rx_packets++;
222	dev->stats.rx_bytes += len;
223
224	ptr = skb_push(skb, 1);
225	*ptr = 0;
226
227	skb->protocol = ax25_type_trans(skb, dev);
228	netif_rx(skb);
229unlock:
230
231	rcu_read_unlock();
232
233	return 0;
234drop_unlock:
235	kfree_skb(skb);
236	goto unlock;
237
238drop:
239	kfree_skb(skb);
240	return 0;
241}
242
243/*
244 * 	Send an AX.25 frame via an ethernet interface
245 */
246static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev)
247{
248	unsigned char *ptr;
249	struct bpqdev *bpq;
250	struct net_device *orig_dev;
251	int size;
252
253	if (skb->protocol == htons(ETH_P_IP))
254		return ax25_ip_xmit(skb);
255
256	/*
257	 * Just to be *really* sure not to send anything if the interface
258	 * is down, the ethernet device may have gone.
259	 */
260	if (!netif_running(dev)) {
261		kfree_skb(skb);
262		return NETDEV_TX_OK;
263	}
264
265	skb_pull(skb, 1);			/* Drop KISS byte */
266	size = skb->len;
267
268	/*
269	 * We're about to mess with the skb which may still shared with the
270	 * generic networking code so unshare and ensure it's got enough
271	 * space for the BPQ headers.
272	 */
273	if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) {
274		if (net_ratelimit())
275			pr_err("bpqether: out of memory\n");
276		kfree_skb(skb);
277
278		return NETDEV_TX_OK;
279	}
280
281	ptr = skb_push(skb, 2);			/* Make space for length */
282
283	*ptr++ = (size + 5) % 256;
284	*ptr++ = (size + 5) / 256;
285
286	bpq = netdev_priv(dev);
287
288	orig_dev = dev;
289	if ((dev = bpq_get_ether_dev(dev)) == NULL) {
290		orig_dev->stats.tx_dropped++;
291		kfree_skb(skb);
292		return NETDEV_TX_OK;
293	}
294
295	skb->protocol = ax25_type_trans(skb, dev);
296	skb_reset_network_header(skb);
297	dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);
298	dev->stats.tx_packets++;
299	dev->stats.tx_bytes+=skb->len;
300
301	dev_queue_xmit(skb);
302	netif_wake_queue(dev);
303	return NETDEV_TX_OK;
304}
305
306/*
307 *	Set AX.25 callsign
308 */
309static int bpq_set_mac_address(struct net_device *dev, void *addr)
310{
311    struct sockaddr *sa = (struct sockaddr *)addr;
312
313    memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
314
315    return 0;
316}
317
318/*	Ioctl commands
319 *
320 *		SIOCSBPQETHOPT		reserved for enhancements
321 *		SIOCSBPQETHADDR		set the destination and accepted
322 *					source ethernet address (broadcast
323 *					or multicast: accept all)
324 */
325static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
326{
327	struct bpq_ethaddr __user *ethaddr = ifr->ifr_data;
328	struct bpqdev *bpq = netdev_priv(dev);
329	struct bpq_req req;
330
331	if (!capable(CAP_NET_ADMIN))
332		return -EPERM;
333
334	switch (cmd) {
335		case SIOCSBPQETHOPT:
336			if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req)))
337				return -EFAULT;
338			switch (req.cmd) {
339				case SIOCGBPQETHPARAM:
340				case SIOCSBPQETHPARAM:
341				default:
342					return -EINVAL;
343			}
344
345			break;
346
347		case SIOCSBPQETHADDR:
348			if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
349				return -EFAULT;
350			if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
351				return -EFAULT;
352			break;
353
354		default:
355			return -EINVAL;
356	}
357
358	return 0;
359}
360
361/*
362 * open/close a device
363 */
364static int bpq_open(struct net_device *dev)
365{
366	netif_start_queue(dev);
367	return 0;
368}
369
370static int bpq_close(struct net_device *dev)
371{
372	netif_stop_queue(dev);
373	return 0;
374}
375
376
377/* ------------------------------------------------------------------------ */
378
379
380/*
381 *	Proc filesystem
382 */
383static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
384	__acquires(RCU)
385{
386	int i = 1;
387	struct bpqdev *bpqdev;
388
389	rcu_read_lock();
390
391	if (*pos == 0)
392		return SEQ_START_TOKEN;
393
394	list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
395		if (i == *pos)
396			return bpqdev;
397	}
398	return NULL;
399}
400
401static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
402{
403	struct list_head *p;
404	struct bpqdev *bpqdev = v;
405
406	++*pos;
407
408	if (v == SEQ_START_TOKEN)
409		p = rcu_dereference(list_next_rcu(&bpq_devices));
410	else
411		p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
412
413	return (p == &bpq_devices) ? NULL
414		: list_entry(p, struct bpqdev, bpq_list);
415}
416
417static void bpq_seq_stop(struct seq_file *seq, void *v)
418	__releases(RCU)
419{
420	rcu_read_unlock();
421}
422
423
424static int bpq_seq_show(struct seq_file *seq, void *v)
425{
426	if (v == SEQ_START_TOKEN)
427		seq_puts(seq,
428			 "dev   ether      destination        accept from\n");
429	else {
430		const struct bpqdev *bpqdev = v;
431
432		seq_printf(seq, "%-5s %-10s %pM  ",
433			bpqdev->axdev->name, bpqdev->ethdev->name,
434			bpqdev->dest_addr);
435
436		if (is_multicast_ether_addr(bpqdev->acpt_addr))
437			seq_printf(seq, "*\n");
438		else
439			seq_printf(seq, "%pM\n", bpqdev->acpt_addr);
440
441	}
442	return 0;
443}
444
445static const 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
452static int bpq_info_open(struct inode *inode, struct file *file)
453{
454	return seq_open(file, &bpq_seqops);
455}
456
457static 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
468static const struct net_device_ops bpq_netdev_ops = {
469	.ndo_open	     = bpq_open,
470	.ndo_stop	     = bpq_close,
471	.ndo_start_xmit	     = bpq_xmit,
472	.ndo_set_mac_address = bpq_set_mac_address,
473	.ndo_do_ioctl	     = bpq_ioctl,
474};
475
476static void bpq_setup(struct net_device *dev)
477{
478	dev->netdev_ops	     = &bpq_netdev_ops;
479	dev->destructor	     = free_netdev;
480
481	memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
482	memcpy(dev->dev_addr,  &ax25_defaddr, AX25_ADDR_LEN);
483
484	dev->flags      = 0;
485	dev->features	= NETIF_F_LLTX;	/* Allow recursion */
486
487#if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
488	dev->header_ops      = &ax25_header_ops;
489#endif
490
491	dev->type            = ARPHRD_AX25;
492	dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
493	dev->mtu             = AX25_DEF_PACLEN;
494	dev->addr_len        = AX25_ADDR_LEN;
495
496}
497
498/*
499 *	Setup a new device.
500 */
501static int bpq_new_device(struct net_device *edev)
502{
503	int err;
504	struct net_device *ndev;
505	struct bpqdev *bpq;
506
507	ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN,
508			    bpq_setup);
509	if (!ndev)
510		return -ENOMEM;
511
512
513	bpq = netdev_priv(ndev);
514	dev_hold(edev);
515	bpq->ethdev = edev;
516	bpq->axdev = ndev;
517
518	memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr));
519	memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr));
520
521	err = register_netdevice(ndev);
522	if (err)
523		goto error;
524	bpq_set_lockdep_class(ndev);
525
526	/* List protected by RTNL */
527	list_add_rcu(&bpq->bpq_list, &bpq_devices);
528	return 0;
529
530 error:
531	dev_put(edev);
532	free_netdev(ndev);
533	return err;
534
535}
536
537static void bpq_free_device(struct net_device *ndev)
538{
539	struct bpqdev *bpq = netdev_priv(ndev);
540
541	dev_put(bpq->ethdev);
542	list_del_rcu(&bpq->bpq_list);
543
544	unregister_netdevice(ndev);
545}
546
547/*
548 *	Handle device status changes.
549 */
550static int bpq_device_event(struct notifier_block *this,
551			    unsigned long event, void *ptr)
552{
553	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
554
555	if (!net_eq(dev_net(dev), &init_net))
556		return NOTIFY_DONE;
557
558	if (!dev_is_ethdev(dev))
559		return NOTIFY_DONE;
560
561	switch (event) {
562	case NETDEV_UP:		/* new ethernet device -> new BPQ interface */
563		if (bpq_get_ax25_dev(dev) == NULL)
564			bpq_new_device(dev);
565		break;
566
567	case NETDEV_DOWN:	/* ethernet device closed -> close BPQ interface */
568		if ((dev = bpq_get_ax25_dev(dev)) != NULL)
569			dev_close(dev);
570		break;
571
572	case NETDEV_UNREGISTER:	/* ethernet device removed -> free BPQ interface */
573		if ((dev = bpq_get_ax25_dev(dev)) != NULL)
574			bpq_free_device(dev);
575		break;
576	default:
577		break;
578	}
579
580	return NOTIFY_DONE;
581}
582
583
584/* ------------------------------------------------------------------------ */
585
586/*
587 * Initialize driver. To be called from af_ax25 if not compiled as a
588 * module
589 */
590static int __init bpq_init_driver(void)
591{
592#ifdef CONFIG_PROC_FS
593	if (!proc_create("bpqether", S_IRUGO, init_net.proc_net,
594			 &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
610static 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	remove_proc_entry("bpqether", init_net.proc_net);
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
628MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");
629MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
630MODULE_LICENSE("GPL");
631module_init(bpq_init_driver);
632module_exit(bpq_cleanup_driver);
633