1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * G8BPQ compatible "AX.25 via ethernet" driver release 004
4 *
5 * This code REQUIRES 2.0.0 or higher/ NET3.029
6 *
7 * This is a "pseudo" network driver to allow AX.25 over Ethernet
8 * using G8BPQ encapsulation. It has been extracted from the protocol
9 * implementation because
10 *
11 * - things got unreadable within the protocol stack
12 * - to cure the protocol stack from "feature-ism"
13 * - a protocol implementation shouldn't need to know on
14 * which hardware it is running
15 * - user-level programs like the AX.25 utilities shouldn't
16 * need to know about the hardware.
17 * - IP over ethernet encapsulated AX.25 was impossible
18 * - rxecho.c did not work
19 * - to have room for extensions
20 * - it just deserves to "live" as an own driver
21 *
22 * This driver can use any ethernet destination address, and can be
23 * limited to accept frames from one dedicated ethernet card only.
24 *
25 * Note that the driver sets up the BPQ devices automagically on
26 * startup or (if started before the "insmod" of an ethernet device)
27 * on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing
28 * the ethernet device (in fact: as soon as another ethernet or bpq
29 * device gets "ifconfig"ured).
30 *
31 * I have heard that several people are thinking of experiments
32 * with highspeed packet radio using existing ethernet cards.
33 * Well, this driver is prepared for this purpose, just add
34 * your tx key control and a txdelay / tailtime algorithm,
35 * probably some buffering, and /voila/...
36 *
37 * History
38 * BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.25
39 * protocol stack and added my own
40 * yet existing patches
41 * BPQ 002 Joerg(DL1BKE) Scan network device list on
42 * startup.
43 * BPQ 003 Joerg(DL1BKE) Ethernet destination address
44 * and accepted source address
45 * can be configured by an ioctl()
46 * call.
47 * Fixed to match Linux networking
48 * changes - 2.1.15.
49 * BPQ 004 Joerg(DL1BKE) Fixed to not lock up on ifconfig.
50 */
51
52 #include <linux/errno.h>
53 #include <linux/types.h>
54 #include <linux/socket.h>
55 #include <linux/in.h>
56 #include <linux/kernel.h>
57 #include <linux/string.h>
58 #include <linux/net.h>
59 #include <linux/slab.h>
60 #include <net/ax25.h>
61 #include <linux/inet.h>
62 #include <linux/netdevice.h>
63 #include <linux/etherdevice.h>
64 #include <linux/if_arp.h>
65 #include <linux/skbuff.h>
66 #include <net/sock.h>
67 #include <linux/uaccess.h>
68 #include <linux/mm.h>
69 #include <linux/interrupt.h>
70 #include <linux/notifier.h>
71 #include <linux/proc_fs.h>
72 #include <linux/seq_file.h>
73 #include <linux/stat.h>
74 #include <linux/module.h>
75 #include <linux/init.h>
76 #include <linux/rtnetlink.h>
77
78 #include <net/ip.h>
79 #include <net/arp.h>
80 #include <net/net_namespace.h>
81
82 #include <linux/bpqether.h>
83
84 static const char banner[] __initconst = KERN_INFO \
85 "AX.25: bpqether driver version 004\n";
86
87 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
88 static int bpq_device_event(struct notifier_block *, unsigned long, void *);
89
90 static struct packet_type bpq_packet_type __read_mostly = {
91 .type = cpu_to_be16(ETH_P_BPQ),
92 .func = bpq_rcv,
93 };
94
95 static struct notifier_block bpq_dev_notifier = {
96 .notifier_call = bpq_device_event,
97 };
98
99
100 struct bpqdev {
101 struct list_head bpq_list; /* list of bpq devices chain */
102 struct net_device *ethdev; /* link to ethernet device */
103 struct net_device *axdev; /* bpq device (bpq#) */
104 char dest_addr[6]; /* ether destination address */
105 char acpt_addr[6]; /* accept ether frames from this address only */
106 };
107
108 static LIST_HEAD(bpq_devices);
109
110 /*
111 * bpqether network devices are paired with ethernet devices below them, so
112 * form a special "super class" of normal ethernet devices; split their locks
113 * off into a separate class since they always nest.
114 */
115 static struct lock_class_key bpq_netdev_xmit_lock_key;
116 static struct lock_class_key bpq_netdev_addr_lock_key;
117
bpq_set_lockdep_class_one(struct net_device * dev,struct netdev_queue * txq,void * _unused)118 static void bpq_set_lockdep_class_one(struct net_device *dev,
119 struct netdev_queue *txq,
120 void *_unused)
121 {
122 lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key);
123 }
124
bpq_set_lockdep_class(struct net_device * dev)125 static void bpq_set_lockdep_class(struct net_device *dev)
126 {
127 lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key);
128 netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL);
129 }
130
131 /* ------------------------------------------------------------------------ */
132
133
134 /*
135 * Get the ethernet device for a BPQ device
136 */
bpq_get_ether_dev(struct net_device * dev)137 static inline struct net_device *bpq_get_ether_dev(struct net_device *dev)
138 {
139 struct bpqdev *bpq = netdev_priv(dev);
140
141 return bpq ? bpq->ethdev : NULL;
142 }
143
144 /*
145 * Get the BPQ device for the ethernet device
146 */
bpq_get_ax25_dev(struct net_device * dev)147 static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
148 {
149 struct bpqdev *bpq;
150
151 list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list,
152 lockdep_rtnl_is_held()) {
153 if (bpq->ethdev == dev)
154 return bpq->axdev;
155 }
156 return NULL;
157 }
158
dev_is_ethdev(struct net_device * dev)159 static inline int dev_is_ethdev(struct net_device *dev)
160 {
161 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
162 }
163
164 /* ------------------------------------------------------------------------ */
165
166
167 /*
168 * Receive an AX.25 frame via an ethernet interface.
169 */
bpq_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * ptype,struct net_device * orig_dev)170 static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
171 {
172 int len;
173 char * ptr;
174 struct ethhdr *eth;
175 struct bpqdev *bpq;
176
177 if (!net_eq(dev_net(dev), &init_net))
178 goto drop;
179
180 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
181 return NET_RX_DROP;
182
183 if (!pskb_may_pull(skb, sizeof(struct ethhdr)))
184 goto drop;
185
186 rcu_read_lock();
187 dev = bpq_get_ax25_dev(dev);
188
189 if (dev == NULL || !netif_running(dev))
190 goto drop_unlock;
191
192 /*
193 * if we want to accept frames from just one ethernet device
194 * we check the source address of the sender.
195 */
196
197 bpq = netdev_priv(dev);
198
199 eth = eth_hdr(skb);
200
201 if (!(bpq->acpt_addr[0] & 0x01) &&
202 !ether_addr_equal(eth->h_source, bpq->acpt_addr))
203 goto drop_unlock;
204
205 if (skb_cow(skb, sizeof(struct ethhdr)))
206 goto drop_unlock;
207
208 len = skb->data[0] + skb->data[1] * 256 - 5;
209
210 skb_pull(skb, 2); /* Remove the length bytes */
211 skb_trim(skb, len); /* Set the length of the data */
212
213 dev->stats.rx_packets++;
214 dev->stats.rx_bytes += len;
215
216 ptr = skb_push(skb, 1);
217 *ptr = 0;
218
219 skb->protocol = ax25_type_trans(skb, dev);
220 netif_rx(skb);
221 unlock:
222
223 rcu_read_unlock();
224
225 return 0;
226 drop_unlock:
227 kfree_skb(skb);
228 goto unlock;
229
230 drop:
231 kfree_skb(skb);
232 return 0;
233 }
234
235 /*
236 * Send an AX.25 frame via an ethernet interface
237 */
bpq_xmit(struct sk_buff * skb,struct net_device * dev)238 static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev)
239 {
240 unsigned char *ptr;
241 struct bpqdev *bpq;
242 struct net_device *orig_dev;
243 int size;
244
245 if (skb->protocol == htons(ETH_P_IP))
246 return ax25_ip_xmit(skb);
247
248 /*
249 * Just to be *really* sure not to send anything if the interface
250 * is down, the ethernet device may have gone.
251 */
252 if (!netif_running(dev)) {
253 kfree_skb(skb);
254 return NETDEV_TX_OK;
255 }
256
257 skb_pull(skb, 1); /* Drop KISS byte */
258 size = skb->len;
259
260 /*
261 * We're about to mess with the skb which may still shared with the
262 * generic networking code so unshare and ensure it's got enough
263 * space for the BPQ headers.
264 */
265 if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) {
266 if (net_ratelimit())
267 pr_err("bpqether: out of memory\n");
268 kfree_skb(skb);
269
270 return NETDEV_TX_OK;
271 }
272
273 ptr = skb_push(skb, 2); /* Make space for length */
274
275 *ptr++ = (size + 5) % 256;
276 *ptr++ = (size + 5) / 256;
277
278 bpq = netdev_priv(dev);
279
280 orig_dev = dev;
281 if ((dev = bpq_get_ether_dev(dev)) == NULL) {
282 orig_dev->stats.tx_dropped++;
283 kfree_skb(skb);
284 return NETDEV_TX_OK;
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 dev->stats.tx_packets++;
291 dev->stats.tx_bytes+=skb->len;
292
293 dev_queue_xmit(skb);
294 netif_wake_queue(dev);
295 return NETDEV_TX_OK;
296 }
297
298 /*
299 * Set AX.25 callsign
300 */
bpq_set_mac_address(struct net_device * dev,void * addr)301 static int bpq_set_mac_address(struct net_device *dev, void *addr)
302 {
303 struct sockaddr *sa = (struct sockaddr *)addr;
304
305 dev_addr_set(dev, sa->sa_data);
306
307 return 0;
308 }
309
310 /* Ioctl commands
311 *
312 * SIOCSBPQETHOPT reserved for enhancements
313 * SIOCSBPQETHADDR set the destination and accepted
314 * source ethernet address (broadcast
315 * or multicast: accept all)
316 */
bpq_siocdevprivate(struct net_device * dev,struct ifreq * ifr,void __user * data,int cmd)317 static int bpq_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
318 void __user *data, int cmd)
319 {
320 struct bpq_ethaddr __user *ethaddr = data;
321 struct bpqdev *bpq = netdev_priv(dev);
322 struct bpq_req req;
323
324 if (!capable(CAP_NET_ADMIN))
325 return -EPERM;
326
327 switch (cmd) {
328 case SIOCSBPQETHOPT:
329 if (copy_from_user(&req, data, sizeof(struct bpq_req)))
330 return -EFAULT;
331 switch (req.cmd) {
332 case SIOCGBPQETHPARAM:
333 case SIOCSBPQETHPARAM:
334 default:
335 return -EINVAL;
336 }
337
338 break;
339
340 case SIOCSBPQETHADDR:
341 if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
342 return -EFAULT;
343 if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
344 return -EFAULT;
345 break;
346
347 default:
348 return -EINVAL;
349 }
350
351 return 0;
352 }
353
354 /*
355 * open/close a device
356 */
bpq_open(struct net_device * dev)357 static int bpq_open(struct net_device *dev)
358 {
359 netif_start_queue(dev);
360 return 0;
361 }
362
bpq_close(struct net_device * dev)363 static int bpq_close(struct net_device *dev)
364 {
365 netif_stop_queue(dev);
366 return 0;
367 }
368
369
370 /* ------------------------------------------------------------------------ */
371
372 #ifdef CONFIG_PROC_FS
373 /*
374 * Proc filesystem
375 */
bpq_seq_start(struct seq_file * seq,loff_t * pos)376 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
377 __acquires(RCU)
378 {
379 int i = 1;
380 struct bpqdev *bpqdev;
381
382 rcu_read_lock();
383
384 if (*pos == 0)
385 return SEQ_START_TOKEN;
386
387 list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
388 if (i == *pos)
389 return bpqdev;
390 }
391 return NULL;
392 }
393
bpq_seq_next(struct seq_file * seq,void * v,loff_t * pos)394 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
395 {
396 struct list_head *p;
397 struct bpqdev *bpqdev = v;
398
399 ++*pos;
400
401 if (v == SEQ_START_TOKEN)
402 p = rcu_dereference(list_next_rcu(&bpq_devices));
403 else
404 p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
405
406 return (p == &bpq_devices) ? NULL
407 : list_entry(p, struct bpqdev, bpq_list);
408 }
409
bpq_seq_stop(struct seq_file * seq,void * v)410 static void bpq_seq_stop(struct seq_file *seq, void *v)
411 __releases(RCU)
412 {
413 rcu_read_unlock();
414 }
415
416
bpq_seq_show(struct seq_file * seq,void * v)417 static int bpq_seq_show(struct seq_file *seq, void *v)
418 {
419 if (v == SEQ_START_TOKEN)
420 seq_puts(seq,
421 "dev ether destination accept from\n");
422 else {
423 const struct bpqdev *bpqdev = v;
424
425 seq_printf(seq, "%-5s %-10s %pM ",
426 bpqdev->axdev->name, bpqdev->ethdev->name,
427 bpqdev->dest_addr);
428
429 if (is_multicast_ether_addr(bpqdev->acpt_addr))
430 seq_printf(seq, "*\n");
431 else
432 seq_printf(seq, "%pM\n", bpqdev->acpt_addr);
433
434 }
435 return 0;
436 }
437
438 static const struct seq_operations bpq_seqops = {
439 .start = bpq_seq_start,
440 .next = bpq_seq_next,
441 .stop = bpq_seq_stop,
442 .show = bpq_seq_show,
443 };
444 #endif
445 /* ------------------------------------------------------------------------ */
446
447 static const struct net_device_ops bpq_netdev_ops = {
448 .ndo_open = bpq_open,
449 .ndo_stop = bpq_close,
450 .ndo_start_xmit = bpq_xmit,
451 .ndo_set_mac_address = bpq_set_mac_address,
452 .ndo_siocdevprivate = bpq_siocdevprivate,
453 };
454
bpq_setup(struct net_device * dev)455 static void bpq_setup(struct net_device *dev)
456 {
457 dev->netdev_ops = &bpq_netdev_ops;
458 dev->needs_free_netdev = true;
459
460 dev->flags = 0;
461 dev->features = NETIF_F_LLTX; /* Allow recursion */
462
463 #if IS_ENABLED(CONFIG_AX25)
464 dev->header_ops = &ax25_header_ops;
465 #endif
466
467 dev->type = ARPHRD_AX25;
468 dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
469 dev->mtu = AX25_DEF_PACLEN;
470 dev->addr_len = AX25_ADDR_LEN;
471
472 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
473 dev_addr_set(dev, (u8 *)&ax25_defaddr);
474 }
475
476 /*
477 * Setup a new device.
478 */
bpq_new_device(struct net_device * edev)479 static int bpq_new_device(struct net_device *edev)
480 {
481 int err;
482 struct net_device *ndev;
483 struct bpqdev *bpq;
484
485 ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN,
486 bpq_setup);
487 if (!ndev)
488 return -ENOMEM;
489
490
491 bpq = netdev_priv(ndev);
492 dev_hold(edev);
493 bpq->ethdev = edev;
494 bpq->axdev = ndev;
495
496 eth_broadcast_addr(bpq->dest_addr);
497 eth_broadcast_addr(bpq->acpt_addr);
498
499 err = register_netdevice(ndev);
500 if (err)
501 goto error;
502 bpq_set_lockdep_class(ndev);
503
504 /* List protected by RTNL */
505 list_add_rcu(&bpq->bpq_list, &bpq_devices);
506 return 0;
507
508 error:
509 dev_put(edev);
510 free_netdev(ndev);
511 return err;
512
513 }
514
bpq_free_device(struct net_device * ndev)515 static void bpq_free_device(struct net_device *ndev)
516 {
517 struct bpqdev *bpq = netdev_priv(ndev);
518
519 dev_put(bpq->ethdev);
520 list_del_rcu(&bpq->bpq_list);
521
522 unregister_netdevice(ndev);
523 }
524
525 /*
526 * Handle device status changes.
527 */
bpq_device_event(struct notifier_block * this,unsigned long event,void * ptr)528 static int bpq_device_event(struct notifier_block *this,
529 unsigned long event, void *ptr)
530 {
531 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
532
533 if (!net_eq(dev_net(dev), &init_net))
534 return NOTIFY_DONE;
535
536 if (!dev_is_ethdev(dev) && !bpq_get_ax25_dev(dev))
537 return NOTIFY_DONE;
538
539 switch (event) {
540 case NETDEV_UP: /* new ethernet device -> new BPQ interface */
541 if (bpq_get_ax25_dev(dev) == NULL)
542 bpq_new_device(dev);
543 break;
544
545 case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */
546 if ((dev = bpq_get_ax25_dev(dev)) != NULL)
547 dev_close(dev);
548 break;
549
550 case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */
551 if ((dev = bpq_get_ax25_dev(dev)) != NULL)
552 bpq_free_device(dev);
553 break;
554 default:
555 break;
556 }
557
558 return NOTIFY_DONE;
559 }
560
561
562 /* ------------------------------------------------------------------------ */
563
564 /*
565 * Initialize driver. To be called from af_ax25 if not compiled as a
566 * module
567 */
bpq_init_driver(void)568 static int __init bpq_init_driver(void)
569 {
570 #ifdef CONFIG_PROC_FS
571 if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) {
572 printk(KERN_ERR
573 "bpq: cannot create /proc/net/bpqether entry.\n");
574 return -ENOENT;
575 }
576 #endif /* CONFIG_PROC_FS */
577
578 dev_add_pack(&bpq_packet_type);
579
580 register_netdevice_notifier(&bpq_dev_notifier);
581
582 printk(banner);
583
584 return 0;
585 }
586
bpq_cleanup_driver(void)587 static void __exit bpq_cleanup_driver(void)
588 {
589 struct bpqdev *bpq;
590
591 dev_remove_pack(&bpq_packet_type);
592
593 unregister_netdevice_notifier(&bpq_dev_notifier);
594
595 remove_proc_entry("bpqether", init_net.proc_net);
596
597 rtnl_lock();
598 while (!list_empty(&bpq_devices)) {
599 bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list);
600 bpq_free_device(bpq->axdev);
601 }
602 rtnl_unlock();
603 }
604
605 MODULE_AUTHOR("Joerg Reuter DL1BKE <jreuter@yaina.de>");
606 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
607 MODULE_LICENSE("GPL");
608 module_init(bpq_init_driver);
609 module_exit(bpq_cleanup_driver);
610