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bpqether.c
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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 
90 static const char banner[] __initconst = KERN_INFO \
91  "AX.25: bpqether driver version 004\n";
92 
93 static char bcast_addr[6]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
94 
95 static char bpq_eth_addr[6];
96 
97 static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);
98 static int bpq_device_event(struct notifier_block *, unsigned long, void *);
99 
100 static struct packet_type bpq_packet_type __read_mostly = {
101  .type = cpu_to_be16(ETH_P_BPQ),
102  .func = bpq_rcv,
103 };
104 
105 static struct notifier_block bpq_dev_notifier = {
106  .notifier_call =bpq_device_event,
107 };
108 
109 
110 struct 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 
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 static struct lock_class_key bpq_netdev_addr_lock_key;
127 
128 static 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 
135 static 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  */
147 static 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  */
157 static 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 
168 static 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  */
179 static 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  memcmp(eth->h_source, bpq->acpt_addr, ETH_ALEN))
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);
230 unlock:
231 
232  rcu_read_unlock();
233 
234  return 0;
235 drop_unlock:
236  kfree_skb(skb);
237  goto unlock;
238 
239 drop:
240  kfree_skb(skb);
241  return 0;
242 }
243 
244 /*
245  * Send an AX.25 frame via an ethernet interface
246  */
247 static 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  /*
255  * Just to be *really* sure not to send anything if the interface
256  * is down, the ethernet device may have gone.
257  */
258  if (!netif_running(dev)) {
259  kfree_skb(skb);
260  return NETDEV_TX_OK;
261  }
262 
263  skb_pull(skb, 1); /* Drop KISS byte */
264  size = skb->len;
265 
266  /*
267  * We're about to mess with the skb which may still shared with the
268  * generic networking code so unshare and ensure it's got enough
269  * space for the BPQ headers.
270  */
271  if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) {
272  if (net_ratelimit())
273  pr_err("bpqether: out of memory\n");
274  kfree_skb(skb);
275 
276  return NETDEV_TX_OK;
277  }
278 
279  ptr = skb_push(skb, 2); /* Make space for length */
280 
281  *ptr++ = (size + 5) % 256;
282  *ptr++ = (size + 5) / 256;
283 
284  bpq = netdev_priv(dev);
285 
286  orig_dev = dev;
287  if ((dev = bpq_get_ether_dev(dev)) == NULL) {
288  orig_dev->stats.tx_dropped++;
289  kfree_skb(skb);
290  return NETDEV_TX_OK;
291  }
292 
293  skb->protocol = ax25_type_trans(skb, dev);
294  skb_reset_network_header(skb);
295  dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0);
296  dev->stats.tx_packets++;
297  dev->stats.tx_bytes+=skb->len;
298 
299  dev_queue_xmit(skb);
300  netif_wake_queue(dev);
301  return NETDEV_TX_OK;
302 }
303 
304 /*
305  * Set AX.25 callsign
306  */
307 static int bpq_set_mac_address(struct net_device *dev, void *addr)
308 {
309  struct sockaddr *sa = (struct sockaddr *)addr;
310 
311  memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
312 
313  return 0;
314 }
315 
316 /* Ioctl commands
317  *
318  * SIOCSBPQETHOPT reserved for enhancements
319  * SIOCSBPQETHADDR set the destination and accepted
320  * source ethernet address (broadcast
321  * or multicast: accept all)
322  */
323 static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
324 {
325  struct bpq_ethaddr __user *ethaddr = ifr->ifr_data;
326  struct bpqdev *bpq = netdev_priv(dev);
327  struct bpq_req req;
328 
329  if (!capable(CAP_NET_ADMIN))
330  return -EPERM;
331 
332  switch (cmd) {
333  case SIOCSBPQETHOPT:
334  if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req)))
335  return -EFAULT;
336  switch (req.cmd) {
337  case SIOCGBPQETHPARAM:
338  case SIOCSBPQETHPARAM:
339  default:
340  return -EINVAL;
341  }
342 
343  break;
344 
345  case SIOCSBPQETHADDR:
346  if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN))
347  return -EFAULT;
348  if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN))
349  return -EFAULT;
350  break;
351 
352  default:
353  return -EINVAL;
354  }
355 
356  return 0;
357 }
358 
359 /*
360  * open/close a device
361  */
362 static int bpq_open(struct net_device *dev)
363 {
364  netif_start_queue(dev);
365  return 0;
366 }
367 
368 static int bpq_close(struct net_device *dev)
369 {
370  netif_stop_queue(dev);
371  return 0;
372 }
373 
374 
375 /* ------------------------------------------------------------------------ */
376 
377 
378 /*
379  * Proc filesystem
380  */
381 static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
382  __acquires(RCU)
383 {
384  int i = 1;
385  struct bpqdev *bpqdev;
386 
387  rcu_read_lock();
388 
389  if (*pos == 0)
390  return SEQ_START_TOKEN;
391 
392  list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
393  if (i == *pos)
394  return bpqdev;
395  }
396  return NULL;
397 }
398 
399 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
400 {
401  struct list_head *p;
402  struct bpqdev *bpqdev = v;
403 
404  ++*pos;
405 
406  if (v == SEQ_START_TOKEN)
407  p = rcu_dereference(list_next_rcu(&bpq_devices));
408  else
409  p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
410 
411  return (p == &bpq_devices) ? NULL
412  : list_entry(p, struct bpqdev, bpq_list);
413 }
414 
415 static void bpq_seq_stop(struct seq_file *seq, void *v)
416  __releases(RCU)
417 {
418  rcu_read_unlock();
419 }
420 
421 
422 static int bpq_seq_show(struct seq_file *seq, void *v)
423 {
424  if (v == SEQ_START_TOKEN)
425  seq_puts(seq,
426  "dev ether destination accept from\n");
427  else {
428  const struct bpqdev *bpqdev = v;
429 
430  seq_printf(seq, "%-5s %-10s %pM ",
431  bpqdev->axdev->name, bpqdev->ethdev->name,
432  bpqdev->dest_addr);
433 
434  if (is_multicast_ether_addr(bpqdev->acpt_addr))
435  seq_printf(seq, "*\n");
436  else
437  seq_printf(seq, "%pM\n", bpqdev->acpt_addr);
438 
439  }
440  return 0;
441 }
442 
443 static const struct seq_operations bpq_seqops = {
444  .start = bpq_seq_start,
445  .next = bpq_seq_next,
446  .stop = bpq_seq_stop,
447  .show = bpq_seq_show,
448 };
449 
450 static int bpq_info_open(struct inode *inode, struct file *file)
451 {
452  return seq_open(file, &bpq_seqops);
453 }
454 
455 static const struct file_operations bpq_info_fops = {
456  .owner = THIS_MODULE,
457  .open = bpq_info_open,
458  .read = seq_read,
459  .llseek = seq_lseek,
460  .release = seq_release,
461 };
462 
463 
464 /* ------------------------------------------------------------------------ */
465 
466 static const struct net_device_ops bpq_netdev_ops = {
467  .ndo_open = bpq_open,
468  .ndo_stop = bpq_close,
469  .ndo_start_xmit = bpq_xmit,
470  .ndo_set_mac_address = bpq_set_mac_address,
471  .ndo_do_ioctl = bpq_ioctl,
472 };
473 
474 static void bpq_setup(struct net_device *dev)
475 {
476  dev->netdev_ops = &bpq_netdev_ops;
477  dev->destructor = free_netdev;
478 
481 
482  dev->flags = 0;
483 
484 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
485  dev->header_ops = &ax25_header_ops;
486 #endif
487 
488  dev->type = ARPHRD_AX25;
490  dev->mtu = AX25_DEF_PACLEN;
491  dev->addr_len = AX25_ADDR_LEN;
492 
493 }
494 
495 /*
496  * Setup a new device.
497  */
498 static int bpq_new_device(struct net_device *edev)
499 {
500  int err;
501  struct net_device *ndev;
502  struct bpqdev *bpq;
503 
504  ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d",
505  bpq_setup);
506  if (!ndev)
507  return -ENOMEM;
508 
509 
510  bpq = netdev_priv(ndev);
511  dev_hold(edev);
512  bpq->ethdev = edev;
513  bpq->axdev = ndev;
514 
515  memcpy(bpq->dest_addr, bcast_addr, sizeof(bpq_eth_addr));
516  memcpy(bpq->acpt_addr, bcast_addr, sizeof(bpq_eth_addr));
517 
518  err = register_netdevice(ndev);
519  if (err)
520  goto error;
521  bpq_set_lockdep_class(ndev);
522 
523  /* List protected by RTNL */
524  list_add_rcu(&bpq->bpq_list, &bpq_devices);
525  return 0;
526 
527  error:
528  dev_put(edev);
529  free_netdev(ndev);
530  return err;
531 
532 }
533 
534 static void bpq_free_device(struct net_device *ndev)
535 {
536  struct bpqdev *bpq = netdev_priv(ndev);
537 
538  dev_put(bpq->ethdev);
539  list_del_rcu(&bpq->bpq_list);
540 
541  unregister_netdevice(ndev);
542 }
543 
544 /*
545  * Handle device status changes.
546  */
547 static int bpq_device_event(struct notifier_block *this,unsigned long event, void *ptr)
548 {
549  struct net_device *dev = (struct net_device *)ptr;
550 
551  if (!net_eq(dev_net(dev), &init_net))
552  return NOTIFY_DONE;
553 
554  if (!dev_is_ethdev(dev))
555  return NOTIFY_DONE;
556 
557  switch (event) {
558  case NETDEV_UP: /* new ethernet device -> new BPQ interface */
559  if (bpq_get_ax25_dev(dev) == NULL)
560  bpq_new_device(dev);
561  break;
562 
563  case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */
564  if ((dev = bpq_get_ax25_dev(dev)) != NULL)
565  dev_close(dev);
566  break;
567 
568  case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */
569  if ((dev = bpq_get_ax25_dev(dev)) != NULL)
570  bpq_free_device(dev);
571  break;
572  default:
573  break;
574  }
575 
576  return NOTIFY_DONE;
577 }
578 
579 
580 /* ------------------------------------------------------------------------ */
581 
582 /*
583  * Initialize driver. To be called from af_ax25 if not compiled as a
584  * module
585  */
586 static int __init bpq_init_driver(void)
587 {
588 #ifdef CONFIG_PROC_FS
589  if (!proc_net_fops_create(&init_net, "bpqether", S_IRUGO, &bpq_info_fops)) {
591  "bpq: cannot create /proc/net/bpqether entry.\n");
592  return -ENOENT;
593  }
594 #endif /* CONFIG_PROC_FS */
595 
596  dev_add_pack(&bpq_packet_type);
597 
598  register_netdevice_notifier(&bpq_dev_notifier);
599 
600  printk(banner);
601 
602  return 0;
603 }
604 
605 static void __exit bpq_cleanup_driver(void)
606 {
607  struct bpqdev *bpq;
608 
609  dev_remove_pack(&bpq_packet_type);
610 
611  unregister_netdevice_notifier(&bpq_dev_notifier);
612 
613  proc_net_remove(&init_net, "bpqether");
614 
615  rtnl_lock();
616  while (!list_empty(&bpq_devices)) {
617  bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list);
618  bpq_free_device(bpq->axdev);
619  }
620  rtnl_unlock();
621 }
622 
623 MODULE_AUTHOR("Joerg Reuter DL1BKE <[email protected]>");
624 MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet");
625 MODULE_LICENSE("GPL");
626 module_init(bpq_init_driver);
627 module_exit(bpq_cleanup_driver);