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/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
90static const char banner[] __initconst = KERN_INFO \
91	"AX.25: bpqether driver version 004\n";
92
93static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
94
95static char bpq_eth_addr[6];
96
97static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
98static int bpq_device_event(struct notifier_block *, unsigned long, void *);
99
100static struct packet_type bpq_packet_type __read_mostly = {
101	.type	= cpu_to_be16(ETH_P_BPQ),
102	.func	= bpq_rcv,
103};
104
105static struct notifier_block bpq_dev_notifier = {
106	.notifier_call = bpq_device_event,
107};
108
109
110struct bpqdev {
111	struct list_head bpq_list;	/* list of bpq devices chain */
112	struct net_device *ethdev;	/* link to ethernet device */
113	struct net_device *axdev;	/* bpq device (bpq#) */
114	char   dest_addr[6];		/* ether destination address */
115	char   acpt_addr[6];		/* accept ether frames from this address only */
116};
117
118static 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 */
125static struct lock_class_key bpq_netdev_xmit_lock_key;
126static struct lock_class_key bpq_netdev_addr_lock_key;
127
128static void bpq_set_lockdep_class_one(struct net_device *dev,
129				      struct netdev_queue *txq,
130				      void *_unused)
131{
132	lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key);
133}
134
135static void bpq_set_lockdep_class(struct net_device *dev)
136{
137	lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key);
138	netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL);
139}
140
141/* ------------------------------------------------------------------------ */
142
143
144/*
145 *	Get the ethernet device for a BPQ device
146 */
147static inline struct net_device *bpq_get_ether_dev(struct net_device *dev)
148{
149	struct bpqdev *bpq = netdev_priv(dev);
150
151	return bpq ? bpq->ethdev : NULL;
152}
153
154/*
155 *	Get the BPQ device for the ethernet device
156 */
157static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
158{
159	struct bpqdev *bpq;
160
161	list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
162		if (bpq->ethdev == dev)
163			return bpq->axdev;
164	}
165	return NULL;
166}
167
168static inline int dev_is_ethdev(struct net_device *dev)
169{
170	return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
171}
172
173/* ------------------------------------------------------------------------ */
174
175
176/*
177 *	Receive an AX.25 frame via an ethernet interface.
178 */
179static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
180{
181	int len;
182	char * ptr;
183	struct ethhdr *eth;
184	struct bpqdev *bpq;
185
186	if (!net_eq(dev_net(dev), &init_net))
187		goto drop;
188
189	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
190		return NET_RX_DROP;
191
192	if (!pskb_may_pull(skb, sizeof(struct ethhdr)))
193		goto drop;
194
195	rcu_read_lock();
196	dev = bpq_get_ax25_dev(dev);
197
198	if (dev == NULL || !netif_running(dev))
199		goto drop_unlock;
200
201	/*
202	 * if we want to accept frames from just one ethernet device
203	 * we check the source address of the sender.
204	 */
205
206	bpq = netdev_priv(dev);
207
208	eth = eth_hdr(skb);
209
210	if (!(bpq->acpt_addr[0] & 0x01) &&
211	    !ether_addr_equal(eth->h_source, bpq->acpt_addr))
212		goto drop_unlock;
213
214	if (skb_cow(skb, sizeof(struct ethhdr)))
215		goto drop_unlock;
216
217	len = skb->data[0] + skb->data[1] * 256 - 5;
218
219	skb_pull(skb, 2);	/* Remove the length bytes */
220	skb_trim(skb, len);	/* Set the length of the data */
221
222	dev->stats.rx_packets++;
223	dev->stats.rx_bytes += len;
224
225	ptr = skb_push(skb, 1);
226	*ptr = 0;
227
228	skb->protocol = ax25_type_trans(skb, dev);
229	netif_rx(skb);
230unlock:
231
232	rcu_read_unlock();
233
234	return 0;
235drop_unlock:
236	kfree_skb(skb);
237	goto unlock;
238
239drop:
240	kfree_skb(skb);
241	return 0;
242}
243
244/*
245 * 	Send an AX.25 frame via an ethernet interface
246 */
247static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev)
248{
249	unsigned char *ptr;
250	struct bpqdev *bpq;
251	struct net_device *orig_dev;
252	int size;
253
254	if (skb->protocol == htons(ETH_P_IP))
255		return ax25_ip_xmit(skb);
256
257	/*
258	 * Just to be *really* sure not to send anything if the interface
259	 * is down, the ethernet device may have gone.
260	 */
261	if (!netif_running(dev)) {
262		kfree_skb(skb);
263		return NETDEV_TX_OK;
264	}
265
266	skb_pull(skb, 1);			/* Drop KISS byte */
267	size = skb->len;
268
269	/*
270	 * We're about to mess with the skb which may still shared with the
271	 * generic networking code so unshare and ensure it's got enough
272	 * space for the BPQ headers.
273	 */
274	if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) {
275		if (net_ratelimit())
276			pr_err("bpqether: out of memory\n");
277		kfree_skb(skb);
278
279		return NETDEV_TX_OK;
280	}
281
282	ptr = skb_push(skb, 2);			/* Make space for length */
283
284	*ptr++ = (size + 5) % 256;
285	*ptr++ = (size + 5) / 256;
286
287	bpq = netdev_priv(dev);
288
289	orig_dev = dev;
290	if ((dev = bpq_get_ether_dev(dev)) == NULL) {
291		orig_dev->stats.tx_dropped++;
292		kfree_skb(skb);
293		return NETDEV_TX_OK;
294	}
295
296	skb->protocol = ax25_type_trans(skb, dev);
297	skb_reset_network_header(skb);
298	dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);
299	dev->stats.tx_packets++;
300	dev->stats.tx_bytes+=skb->len;
301
302	dev_queue_xmit(skb);
303	netif_wake_queue(dev);
304	return NETDEV_TX_OK;
305}
306
307/*
308 *	Set AX.25 callsign
309 */
310static int bpq_set_mac_address(struct net_device *dev, void *addr)
311{
312    struct sockaddr *sa = (struct sockaddr *)addr;
313
314    memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
315
316    return 0;
317}
318
319/*	Ioctl commands
320 *
321 *		SIOCSBPQETHOPT		reserved for enhancements
322 *		SIOCSBPQETHADDR		set the destination and accepted
323 *					source ethernet address (broadcast
324 *					or multicast: accept all)
325 */
326static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
327{
328	struct bpq_ethaddr __user *ethaddr = ifr->ifr_data;
329	struct bpqdev *bpq = netdev_priv(dev);
330	struct bpq_req req;
331
332	if (!capable(CAP_NET_ADMIN))
333		return -EPERM;
334
335	switch (cmd) {
336		case SIOCSBPQETHOPT:
337			if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req)))
338				return -EFAULT;
339			switch (req.cmd) {
340				case SIOCGBPQETHPARAM:
341				case SIOCSBPQETHPARAM:
342				default:
343					return -EINVAL;
344			}
345
346			break;
347
348		case SIOCSBPQETHADDR:
349			if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
350				return -EFAULT;
351			if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
352				return -EFAULT;
353			break;
354
355		default:
356			return -EINVAL;
357	}
358
359	return 0;
360}
361
362/*
363 * open/close a device
364 */
365static int bpq_open(struct net_device *dev)
366{
367	netif_start_queue(dev);
368	return 0;
369}
370
371static int bpq_close(struct net_device *dev)
372{
373	netif_stop_queue(dev);
374	return 0;
375}
376
377
378/* ------------------------------------------------------------------------ */
379
380
381/*
382 *	Proc filesystem
383 */
384static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
385	__acquires(RCU)
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
402static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
403{
404	struct list_head *p;
405	struct bpqdev *bpqdev = v;
406
407	++*pos;
408
409	if (v == SEQ_START_TOKEN)
410		p = rcu_dereference(list_next_rcu(&bpq_devices));
411	else
412		p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
413
414	return (p == &bpq_devices) ? NULL
415		: list_entry(p, struct bpqdev, bpq_list);
416}
417
418static void bpq_seq_stop(struct seq_file *seq, void *v)
419	__releases(RCU)
420{
421	rcu_read_unlock();
422}
423
424
425static int bpq_seq_show(struct seq_file *seq, void *v)
426{
427	if (v == SEQ_START_TOKEN)
428		seq_puts(seq,
429			 "dev   ether      destination        accept from\n");
430	else {
431		const struct bpqdev *bpqdev = v;
432
433		seq_printf(seq, "%-5s %-10s %pM  ",
434			bpqdev->axdev->name, bpqdev->ethdev->name,
435			bpqdev->dest_addr);
436
437		if (is_multicast_ether_addr(bpqdev->acpt_addr))
438			seq_printf(seq, "*\n");
439		else
440			seq_printf(seq, "%pM\n", bpqdev->acpt_addr);
441
442	}
443	return 0;
444}
445
446static const struct seq_operations bpq_seqops = {
447	.start = bpq_seq_start,
448	.next = bpq_seq_next,
449	.stop = bpq_seq_stop,
450	.show = bpq_seq_show,
451};
452
453static int bpq_info_open(struct inode *inode, struct file *file)
454{
455	return seq_open(file, &bpq_seqops);
456}
457
458static const struct file_operations bpq_info_fops = {
459	.owner = THIS_MODULE,
460	.open = bpq_info_open,
461	.read = seq_read,
462	.llseek = seq_lseek,
463	.release = seq_release,
464};
465
466
467/* ------------------------------------------------------------------------ */
468
469static const struct net_device_ops bpq_netdev_ops = {
470	.ndo_open	     = bpq_open,
471	.ndo_stop	     = bpq_close,
472	.ndo_start_xmit	     = bpq_xmit,
473	.ndo_set_mac_address = bpq_set_mac_address,
474	.ndo_do_ioctl	     = bpq_ioctl,
475};
476
477static void bpq_setup(struct net_device *dev)
478{
479	dev->netdev_ops	     = &bpq_netdev_ops;
480	dev->destructor	     = free_netdev;
481
482	memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
483	memcpy(dev->dev_addr,  &ax25_defaddr, AX25_ADDR_LEN);
484
485	dev->flags      = 0;
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