xref: /linux/net/netrom/nr_route.c (revision b7019ac550eb3916f34d79db583e9b7ea2524afa)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *
4  * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5  * Copyright Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
6  * Copyright Tomi Manninen OH2BNS (oh2bns@sral.fi)
7  */
8 #include <linux/errno.h>
9 #include <linux/types.h>
10 #include <linux/socket.h>
11 #include <linux/in.h>
12 #include <linux/kernel.h>
13 #include <linux/timer.h>
14 #include <linux/string.h>
15 #include <linux/sockios.h>
16 #include <linux/net.h>
17 #include <linux/slab.h>
18 #include <net/ax25.h>
19 #include <linux/inet.h>
20 #include <linux/netdevice.h>
21 #include <net/arp.h>
22 #include <linux/if_arp.h>
23 #include <linux/skbuff.h>
24 #include <net/sock.h>
25 #include <linux/uaccess.h>
26 #include <linux/fcntl.h>
27 #include <linux/termios.h>	/* For TIOCINQ/OUTQ */
28 #include <linux/mm.h>
29 #include <linux/interrupt.h>
30 #include <linux/notifier.h>
31 #include <linux/init.h>
32 #include <linux/spinlock.h>
33 #include <net/netrom.h>
34 #include <linux/seq_file.h>
35 #include <linux/export.h>
36 
37 static unsigned int nr_neigh_no = 1;
38 
39 static HLIST_HEAD(nr_node_list);
40 static DEFINE_SPINLOCK(nr_node_list_lock);
41 static HLIST_HEAD(nr_neigh_list);
42 static DEFINE_SPINLOCK(nr_neigh_list_lock);
43 
44 static struct nr_node *nr_node_get(ax25_address *callsign)
45 {
46 	struct nr_node *found = NULL;
47 	struct nr_node *nr_node;
48 
49 	spin_lock_bh(&nr_node_list_lock);
50 	nr_node_for_each(nr_node, &nr_node_list)
51 		if (ax25cmp(callsign, &nr_node->callsign) == 0) {
52 			nr_node_hold(nr_node);
53 			found = nr_node;
54 			break;
55 		}
56 	spin_unlock_bh(&nr_node_list_lock);
57 	return found;
58 }
59 
60 static struct nr_neigh *nr_neigh_get_dev(ax25_address *callsign,
61 					 struct net_device *dev)
62 {
63 	struct nr_neigh *found = NULL;
64 	struct nr_neigh *nr_neigh;
65 
66 	spin_lock_bh(&nr_neigh_list_lock);
67 	nr_neigh_for_each(nr_neigh, &nr_neigh_list)
68 		if (ax25cmp(callsign, &nr_neigh->callsign) == 0 &&
69 		    nr_neigh->dev == dev) {
70 			nr_neigh_hold(nr_neigh);
71 			found = nr_neigh;
72 			break;
73 		}
74 	spin_unlock_bh(&nr_neigh_list_lock);
75 	return found;
76 }
77 
78 static void nr_remove_neigh(struct nr_neigh *);
79 
80 /*      re-sort the routes in quality order.    */
81 static void re_sort_routes(struct nr_node *nr_node, int x, int y)
82 {
83 	if (nr_node->routes[y].quality > nr_node->routes[x].quality) {
84 		if (nr_node->which == x)
85 			nr_node->which = y;
86 		else if (nr_node->which == y)
87 			nr_node->which = x;
88 
89 		swap(nr_node->routes[x], nr_node->routes[y]);
90 	}
91 }
92 
93 /*
94  *	Add a new route to a node, and in the process add the node and the
95  *	neighbour if it is new.
96  */
97 static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
98 	ax25_address *ax25, ax25_digi *ax25_digi, struct net_device *dev,
99 	int quality, int obs_count)
100 {
101 	struct nr_node  *nr_node;
102 	struct nr_neigh *nr_neigh;
103 	int i, found;
104 	struct net_device *odev;
105 
106 	if ((odev=nr_dev_get(nr)) != NULL) {	/* Can't add routes to ourself */
107 		dev_put(odev);
108 		return -EINVAL;
109 	}
110 
111 	nr_node = nr_node_get(nr);
112 
113 	nr_neigh = nr_neigh_get_dev(ax25, dev);
114 
115 	/*
116 	 * The L2 link to a neighbour has failed in the past
117 	 * and now a frame comes from this neighbour. We assume
118 	 * it was a temporary trouble with the link and reset the
119 	 * routes now (and not wait for a node broadcast).
120 	 */
121 	if (nr_neigh != NULL && nr_neigh->failed != 0 && quality == 0) {
122 		struct nr_node *nr_nodet;
123 
124 		spin_lock_bh(&nr_node_list_lock);
125 		nr_node_for_each(nr_nodet, &nr_node_list) {
126 			nr_node_lock(nr_nodet);
127 			for (i = 0; i < nr_nodet->count; i++)
128 				if (nr_nodet->routes[i].neighbour == nr_neigh)
129 					if (i < nr_nodet->which)
130 						nr_nodet->which = i;
131 			nr_node_unlock(nr_nodet);
132 		}
133 		spin_unlock_bh(&nr_node_list_lock);
134 	}
135 
136 	if (nr_neigh != NULL)
137 		nr_neigh->failed = 0;
138 
139 	if (quality == 0 && nr_neigh != NULL && nr_node != NULL) {
140 		nr_neigh_put(nr_neigh);
141 		nr_node_put(nr_node);
142 		return 0;
143 	}
144 
145 	if (nr_neigh == NULL) {
146 		if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL) {
147 			if (nr_node)
148 				nr_node_put(nr_node);
149 			return -ENOMEM;
150 		}
151 
152 		nr_neigh->callsign = *ax25;
153 		nr_neigh->digipeat = NULL;
154 		nr_neigh->ax25     = NULL;
155 		nr_neigh->dev      = dev;
156 		nr_neigh->quality  = sysctl_netrom_default_path_quality;
157 		nr_neigh->locked   = 0;
158 		nr_neigh->count    = 0;
159 		nr_neigh->number   = nr_neigh_no++;
160 		nr_neigh->failed   = 0;
161 		refcount_set(&nr_neigh->refcount, 1);
162 
163 		if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
164 			nr_neigh->digipeat = kmemdup(ax25_digi,
165 						     sizeof(*ax25_digi),
166 						     GFP_KERNEL);
167 			if (nr_neigh->digipeat == NULL) {
168 				kfree(nr_neigh);
169 				if (nr_node)
170 					nr_node_put(nr_node);
171 				return -ENOMEM;
172 			}
173 		}
174 
175 		spin_lock_bh(&nr_neigh_list_lock);
176 		hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
177 		nr_neigh_hold(nr_neigh);
178 		spin_unlock_bh(&nr_neigh_list_lock);
179 	}
180 
181 	if (quality != 0 && ax25cmp(nr, ax25) == 0 && !nr_neigh->locked)
182 		nr_neigh->quality = quality;
183 
184 	if (nr_node == NULL) {
185 		if ((nr_node = kmalloc(sizeof(*nr_node), GFP_ATOMIC)) == NULL) {
186 			if (nr_neigh)
187 				nr_neigh_put(nr_neigh);
188 			return -ENOMEM;
189 		}
190 
191 		nr_node->callsign = *nr;
192 		strcpy(nr_node->mnemonic, mnemonic);
193 
194 		nr_node->which = 0;
195 		nr_node->count = 1;
196 		refcount_set(&nr_node->refcount, 1);
197 		spin_lock_init(&nr_node->node_lock);
198 
199 		nr_node->routes[0].quality   = quality;
200 		nr_node->routes[0].obs_count = obs_count;
201 		nr_node->routes[0].neighbour = nr_neigh;
202 
203 		nr_neigh_hold(nr_neigh);
204 		nr_neigh->count++;
205 
206 		spin_lock_bh(&nr_node_list_lock);
207 		hlist_add_head(&nr_node->node_node, &nr_node_list);
208 		/* refcount initialized at 1 */
209 		spin_unlock_bh(&nr_node_list_lock);
210 
211 		return 0;
212 	}
213 	nr_node_lock(nr_node);
214 
215 	if (quality != 0)
216 		strcpy(nr_node->mnemonic, mnemonic);
217 
218 	for (found = 0, i = 0; i < nr_node->count; i++) {
219 		if (nr_node->routes[i].neighbour == nr_neigh) {
220 			nr_node->routes[i].quality   = quality;
221 			nr_node->routes[i].obs_count = obs_count;
222 			found = 1;
223 			break;
224 		}
225 	}
226 
227 	if (!found) {
228 		/* We have space at the bottom, slot it in */
229 		if (nr_node->count < 3) {
230 			nr_node->routes[2] = nr_node->routes[1];
231 			nr_node->routes[1] = nr_node->routes[0];
232 
233 			nr_node->routes[0].quality   = quality;
234 			nr_node->routes[0].obs_count = obs_count;
235 			nr_node->routes[0].neighbour = nr_neigh;
236 
237 			nr_node->which++;
238 			nr_node->count++;
239 			nr_neigh_hold(nr_neigh);
240 			nr_neigh->count++;
241 		} else {
242 			/* It must be better than the worst */
243 			if (quality > nr_node->routes[2].quality) {
244 				nr_node->routes[2].neighbour->count--;
245 				nr_neigh_put(nr_node->routes[2].neighbour);
246 
247 				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
248 					nr_remove_neigh(nr_node->routes[2].neighbour);
249 
250 				nr_node->routes[2].quality   = quality;
251 				nr_node->routes[2].obs_count = obs_count;
252 				nr_node->routes[2].neighbour = nr_neigh;
253 
254 				nr_neigh_hold(nr_neigh);
255 				nr_neigh->count++;
256 			}
257 		}
258 	}
259 
260 	/* Now re-sort the routes in quality order */
261 	switch (nr_node->count) {
262 	case 3:
263 		re_sort_routes(nr_node, 0, 1);
264 		re_sort_routes(nr_node, 1, 2);
265 		/* fall through */
266 	case 2:
267 		re_sort_routes(nr_node, 0, 1);
268 	case 1:
269 		break;
270 	}
271 
272 	for (i = 0; i < nr_node->count; i++) {
273 		if (nr_node->routes[i].neighbour == nr_neigh) {
274 			if (i < nr_node->which)
275 				nr_node->which = i;
276 			break;
277 		}
278 	}
279 
280 	nr_neigh_put(nr_neigh);
281 	nr_node_unlock(nr_node);
282 	nr_node_put(nr_node);
283 	return 0;
284 }
285 
286 static inline void __nr_remove_node(struct nr_node *nr_node)
287 {
288 	hlist_del_init(&nr_node->node_node);
289 	nr_node_put(nr_node);
290 }
291 
292 #define nr_remove_node_locked(__node) \
293 	__nr_remove_node(__node)
294 
295 static void nr_remove_node(struct nr_node *nr_node)
296 {
297 	spin_lock_bh(&nr_node_list_lock);
298 	__nr_remove_node(nr_node);
299 	spin_unlock_bh(&nr_node_list_lock);
300 }
301 
302 static inline void __nr_remove_neigh(struct nr_neigh *nr_neigh)
303 {
304 	hlist_del_init(&nr_neigh->neigh_node);
305 	nr_neigh_put(nr_neigh);
306 }
307 
308 #define nr_remove_neigh_locked(__neigh) \
309 	__nr_remove_neigh(__neigh)
310 
311 static void nr_remove_neigh(struct nr_neigh *nr_neigh)
312 {
313 	spin_lock_bh(&nr_neigh_list_lock);
314 	__nr_remove_neigh(nr_neigh);
315 	spin_unlock_bh(&nr_neigh_list_lock);
316 }
317 
318 /*
319  *	"Delete" a node. Strictly speaking remove a route to a node. The node
320  *	is only deleted if no routes are left to it.
321  */
322 static int nr_del_node(ax25_address *callsign, ax25_address *neighbour, struct net_device *dev)
323 {
324 	struct nr_node  *nr_node;
325 	struct nr_neigh *nr_neigh;
326 	int i;
327 
328 	nr_node = nr_node_get(callsign);
329 
330 	if (nr_node == NULL)
331 		return -EINVAL;
332 
333 	nr_neigh = nr_neigh_get_dev(neighbour, dev);
334 
335 	if (nr_neigh == NULL) {
336 		nr_node_put(nr_node);
337 		return -EINVAL;
338 	}
339 
340 	nr_node_lock(nr_node);
341 	for (i = 0; i < nr_node->count; i++) {
342 		if (nr_node->routes[i].neighbour == nr_neigh) {
343 			nr_neigh->count--;
344 			nr_neigh_put(nr_neigh);
345 
346 			if (nr_neigh->count == 0 && !nr_neigh->locked)
347 				nr_remove_neigh(nr_neigh);
348 			nr_neigh_put(nr_neigh);
349 
350 			nr_node->count--;
351 
352 			if (nr_node->count == 0) {
353 				nr_remove_node(nr_node);
354 			} else {
355 				switch (i) {
356 				case 0:
357 					nr_node->routes[0] = nr_node->routes[1];
358 					/* fall through */
359 				case 1:
360 					nr_node->routes[1] = nr_node->routes[2];
361 				case 2:
362 					break;
363 				}
364 				nr_node_put(nr_node);
365 			}
366 			nr_node_unlock(nr_node);
367 
368 			return 0;
369 		}
370 	}
371 	nr_neigh_put(nr_neigh);
372 	nr_node_unlock(nr_node);
373 	nr_node_put(nr_node);
374 
375 	return -EINVAL;
376 }
377 
378 /*
379  *	Lock a neighbour with a quality.
380  */
381 static int __must_check nr_add_neigh(ax25_address *callsign,
382 	ax25_digi *ax25_digi, struct net_device *dev, unsigned int quality)
383 {
384 	struct nr_neigh *nr_neigh;
385 
386 	nr_neigh = nr_neigh_get_dev(callsign, dev);
387 	if (nr_neigh) {
388 		nr_neigh->quality = quality;
389 		nr_neigh->locked  = 1;
390 		nr_neigh_put(nr_neigh);
391 		return 0;
392 	}
393 
394 	if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL)
395 		return -ENOMEM;
396 
397 	nr_neigh->callsign = *callsign;
398 	nr_neigh->digipeat = NULL;
399 	nr_neigh->ax25     = NULL;
400 	nr_neigh->dev      = dev;
401 	nr_neigh->quality  = quality;
402 	nr_neigh->locked   = 1;
403 	nr_neigh->count    = 0;
404 	nr_neigh->number   = nr_neigh_no++;
405 	nr_neigh->failed   = 0;
406 	refcount_set(&nr_neigh->refcount, 1);
407 
408 	if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
409 		nr_neigh->digipeat = kmemdup(ax25_digi, sizeof(*ax25_digi),
410 					     GFP_KERNEL);
411 		if (nr_neigh->digipeat == NULL) {
412 			kfree(nr_neigh);
413 			return -ENOMEM;
414 		}
415 	}
416 
417 	spin_lock_bh(&nr_neigh_list_lock);
418 	hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
419 	/* refcount is initialized at 1 */
420 	spin_unlock_bh(&nr_neigh_list_lock);
421 
422 	return 0;
423 }
424 
425 /*
426  *	"Delete" a neighbour. The neighbour is only removed if the number
427  *	of nodes that may use it is zero.
428  */
429 static int nr_del_neigh(ax25_address *callsign, struct net_device *dev, unsigned int quality)
430 {
431 	struct nr_neigh *nr_neigh;
432 
433 	nr_neigh = nr_neigh_get_dev(callsign, dev);
434 
435 	if (nr_neigh == NULL) return -EINVAL;
436 
437 	nr_neigh->quality = quality;
438 	nr_neigh->locked  = 0;
439 
440 	if (nr_neigh->count == 0)
441 		nr_remove_neigh(nr_neigh);
442 	nr_neigh_put(nr_neigh);
443 
444 	return 0;
445 }
446 
447 /*
448  *	Decrement the obsolescence count by one. If a route is reduced to a
449  *	count of zero, remove it. Also remove any unlocked neighbours with
450  *	zero nodes routing via it.
451  */
452 static int nr_dec_obs(void)
453 {
454 	struct nr_neigh *nr_neigh;
455 	struct nr_node  *s;
456 	struct hlist_node *nodet;
457 	int i;
458 
459 	spin_lock_bh(&nr_node_list_lock);
460 	nr_node_for_each_safe(s, nodet, &nr_node_list) {
461 		nr_node_lock(s);
462 		for (i = 0; i < s->count; i++) {
463 			switch (s->routes[i].obs_count) {
464 			case 0:		/* A locked entry */
465 				break;
466 
467 			case 1:		/* From 1 -> 0 */
468 				nr_neigh = s->routes[i].neighbour;
469 
470 				nr_neigh->count--;
471 				nr_neigh_put(nr_neigh);
472 
473 				if (nr_neigh->count == 0 && !nr_neigh->locked)
474 					nr_remove_neigh(nr_neigh);
475 
476 				s->count--;
477 
478 				switch (i) {
479 				case 0:
480 					s->routes[0] = s->routes[1];
481 					/* Fallthrough */
482 				case 1:
483 					s->routes[1] = s->routes[2];
484 				case 2:
485 					break;
486 				}
487 				break;
488 
489 			default:
490 				s->routes[i].obs_count--;
491 				break;
492 
493 			}
494 		}
495 
496 		if (s->count <= 0)
497 			nr_remove_node_locked(s);
498 		nr_node_unlock(s);
499 	}
500 	spin_unlock_bh(&nr_node_list_lock);
501 
502 	return 0;
503 }
504 
505 /*
506  *	A device has been removed. Remove its routes and neighbours.
507  */
508 void nr_rt_device_down(struct net_device *dev)
509 {
510 	struct nr_neigh *s;
511 	struct hlist_node *nodet, *node2t;
512 	struct nr_node  *t;
513 	int i;
514 
515 	spin_lock_bh(&nr_neigh_list_lock);
516 	nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
517 		if (s->dev == dev) {
518 			spin_lock_bh(&nr_node_list_lock);
519 			nr_node_for_each_safe(t, node2t, &nr_node_list) {
520 				nr_node_lock(t);
521 				for (i = 0; i < t->count; i++) {
522 					if (t->routes[i].neighbour == s) {
523 						t->count--;
524 
525 						switch (i) {
526 						case 0:
527 							t->routes[0] = t->routes[1];
528 							/* fall through */
529 						case 1:
530 							t->routes[1] = t->routes[2];
531 						case 2:
532 							break;
533 						}
534 					}
535 				}
536 
537 				if (t->count <= 0)
538 					nr_remove_node_locked(t);
539 				nr_node_unlock(t);
540 			}
541 			spin_unlock_bh(&nr_node_list_lock);
542 
543 			nr_remove_neigh_locked(s);
544 		}
545 	}
546 	spin_unlock_bh(&nr_neigh_list_lock);
547 }
548 
549 /*
550  *	Check that the device given is a valid AX.25 interface that is "up".
551  *	Or a valid ethernet interface with an AX.25 callsign binding.
552  */
553 static struct net_device *nr_ax25_dev_get(char *devname)
554 {
555 	struct net_device *dev;
556 
557 	if ((dev = dev_get_by_name(&init_net, devname)) == NULL)
558 		return NULL;
559 
560 	if ((dev->flags & IFF_UP) && dev->type == ARPHRD_AX25)
561 		return dev;
562 
563 	dev_put(dev);
564 	return NULL;
565 }
566 
567 /*
568  *	Find the first active NET/ROM device, usually "nr0".
569  */
570 struct net_device *nr_dev_first(void)
571 {
572 	struct net_device *dev, *first = NULL;
573 
574 	rcu_read_lock();
575 	for_each_netdev_rcu(&init_net, dev) {
576 		if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM)
577 			if (first == NULL || strncmp(dev->name, first->name, 3) < 0)
578 				first = dev;
579 	}
580 	if (first)
581 		dev_hold(first);
582 	rcu_read_unlock();
583 
584 	return first;
585 }
586 
587 /*
588  *	Find the NET/ROM device for the given callsign.
589  */
590 struct net_device *nr_dev_get(ax25_address *addr)
591 {
592 	struct net_device *dev;
593 
594 	rcu_read_lock();
595 	for_each_netdev_rcu(&init_net, dev) {
596 		if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM &&
597 		    ax25cmp(addr, (ax25_address *)dev->dev_addr) == 0) {
598 			dev_hold(dev);
599 			goto out;
600 		}
601 	}
602 	dev = NULL;
603 out:
604 	rcu_read_unlock();
605 	return dev;
606 }
607 
608 static ax25_digi *nr_call_to_digi(ax25_digi *digi, int ndigis,
609 	ax25_address *digipeaters)
610 {
611 	int i;
612 
613 	if (ndigis == 0)
614 		return NULL;
615 
616 	for (i = 0; i < ndigis; i++) {
617 		digi->calls[i]    = digipeaters[i];
618 		digi->repeated[i] = 0;
619 	}
620 
621 	digi->ndigi      = ndigis;
622 	digi->lastrepeat = -1;
623 
624 	return digi;
625 }
626 
627 /*
628  *	Handle the ioctls that control the routing functions.
629  */
630 int nr_rt_ioctl(unsigned int cmd, void __user *arg)
631 {
632 	struct nr_route_struct nr_route;
633 	struct net_device *dev;
634 	ax25_digi digi;
635 	int ret;
636 
637 	switch (cmd) {
638 	case SIOCADDRT:
639 		if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
640 			return -EFAULT;
641 		if (nr_route.ndigis > AX25_MAX_DIGIS)
642 			return -EINVAL;
643 		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
644 			return -EINVAL;
645 		switch (nr_route.type) {
646 		case NETROM_NODE:
647 			if (strnlen(nr_route.mnemonic, 7) == 7) {
648 				ret = -EINVAL;
649 				break;
650 			}
651 
652 			ret = nr_add_node(&nr_route.callsign,
653 				nr_route.mnemonic,
654 				&nr_route.neighbour,
655 				nr_call_to_digi(&digi, nr_route.ndigis,
656 						nr_route.digipeaters),
657 				dev, nr_route.quality,
658 				nr_route.obs_count);
659 			break;
660 		case NETROM_NEIGH:
661 			ret = nr_add_neigh(&nr_route.callsign,
662 				nr_call_to_digi(&digi, nr_route.ndigis,
663 						nr_route.digipeaters),
664 				dev, nr_route.quality);
665 			break;
666 		default:
667 			ret = -EINVAL;
668 		}
669 		dev_put(dev);
670 		return ret;
671 
672 	case SIOCDELRT:
673 		if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
674 			return -EFAULT;
675 		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
676 			return -EINVAL;
677 		switch (nr_route.type) {
678 		case NETROM_NODE:
679 			ret = nr_del_node(&nr_route.callsign,
680 				&nr_route.neighbour, dev);
681 			break;
682 		case NETROM_NEIGH:
683 			ret = nr_del_neigh(&nr_route.callsign,
684 				dev, nr_route.quality);
685 			break;
686 		default:
687 			ret = -EINVAL;
688 		}
689 		dev_put(dev);
690 		return ret;
691 
692 	case SIOCNRDECOBS:
693 		return nr_dec_obs();
694 
695 	default:
696 		return -EINVAL;
697 	}
698 
699 	return 0;
700 }
701 
702 /*
703  * 	A level 2 link has timed out, therefore it appears to be a poor link,
704  *	then don't use that neighbour until it is reset.
705  */
706 void nr_link_failed(ax25_cb *ax25, int reason)
707 {
708 	struct nr_neigh *s, *nr_neigh = NULL;
709 	struct nr_node  *nr_node = NULL;
710 
711 	spin_lock_bh(&nr_neigh_list_lock);
712 	nr_neigh_for_each(s, &nr_neigh_list) {
713 		if (s->ax25 == ax25) {
714 			nr_neigh_hold(s);
715 			nr_neigh = s;
716 			break;
717 		}
718 	}
719 	spin_unlock_bh(&nr_neigh_list_lock);
720 
721 	if (nr_neigh == NULL)
722 		return;
723 
724 	nr_neigh->ax25 = NULL;
725 	ax25_cb_put(ax25);
726 
727 	if (++nr_neigh->failed < sysctl_netrom_link_fails_count) {
728 		nr_neigh_put(nr_neigh);
729 		return;
730 	}
731 	spin_lock_bh(&nr_node_list_lock);
732 	nr_node_for_each(nr_node, &nr_node_list) {
733 		nr_node_lock(nr_node);
734 		if (nr_node->which < nr_node->count &&
735 		    nr_node->routes[nr_node->which].neighbour == nr_neigh)
736 			nr_node->which++;
737 		nr_node_unlock(nr_node);
738 	}
739 	spin_unlock_bh(&nr_node_list_lock);
740 	nr_neigh_put(nr_neigh);
741 }
742 
743 /*
744  *	Route a frame to an appropriate AX.25 connection. A NULL ax25_cb
745  *	indicates an internally generated frame.
746  */
747 int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25)
748 {
749 	ax25_address *nr_src, *nr_dest;
750 	struct nr_neigh *nr_neigh;
751 	struct nr_node  *nr_node;
752 	struct net_device *dev;
753 	unsigned char *dptr;
754 	ax25_cb *ax25s;
755 	int ret;
756 	struct sk_buff *skbn;
757 
758 
759 	nr_src  = (ax25_address *)(skb->data + 0);
760 	nr_dest = (ax25_address *)(skb->data + 7);
761 
762 	if (ax25 != NULL) {
763 		ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat,
764 				  ax25->ax25_dev->dev, 0,
765 				  sysctl_netrom_obsolescence_count_initialiser);
766 		if (ret)
767 			return ret;
768 	}
769 
770 	if ((dev = nr_dev_get(nr_dest)) != NULL) {	/* Its for me */
771 		if (ax25 == NULL)			/* Its from me */
772 			ret = nr_loopback_queue(skb);
773 		else
774 			ret = nr_rx_frame(skb, dev);
775 		dev_put(dev);
776 		return ret;
777 	}
778 
779 	if (!sysctl_netrom_routing_control && ax25 != NULL)
780 		return 0;
781 
782 	/* Its Time-To-Live has expired */
783 	if (skb->data[14] == 1) {
784 		return 0;
785 	}
786 
787 	nr_node = nr_node_get(nr_dest);
788 	if (nr_node == NULL)
789 		return 0;
790 	nr_node_lock(nr_node);
791 
792 	if (nr_node->which >= nr_node->count) {
793 		nr_node_unlock(nr_node);
794 		nr_node_put(nr_node);
795 		return 0;
796 	}
797 
798 	nr_neigh = nr_node->routes[nr_node->which].neighbour;
799 
800 	if ((dev = nr_dev_first()) == NULL) {
801 		nr_node_unlock(nr_node);
802 		nr_node_put(nr_node);
803 		return 0;
804 	}
805 
806 	/* We are going to change the netrom headers so we should get our
807 	   own skb, we also did not know until now how much header space
808 	   we had to reserve... - RXQ */
809 	if ((skbn=skb_copy_expand(skb, dev->hard_header_len, 0, GFP_ATOMIC)) == NULL) {
810 		nr_node_unlock(nr_node);
811 		nr_node_put(nr_node);
812 		dev_put(dev);
813 		return 0;
814 	}
815 	kfree_skb(skb);
816 	skb=skbn;
817 	skb->data[14]--;
818 
819 	dptr  = skb_push(skb, 1);
820 	*dptr = AX25_P_NETROM;
821 
822 	ax25s = nr_neigh->ax25;
823 	nr_neigh->ax25 = ax25_send_frame(skb, 256,
824 					 (ax25_address *)dev->dev_addr,
825 					 &nr_neigh->callsign,
826 					 nr_neigh->digipeat, nr_neigh->dev);
827 	if (ax25s)
828 		ax25_cb_put(ax25s);
829 
830 	dev_put(dev);
831 	ret = (nr_neigh->ax25 != NULL);
832 	nr_node_unlock(nr_node);
833 	nr_node_put(nr_node);
834 
835 	return ret;
836 }
837 
838 #ifdef CONFIG_PROC_FS
839 
840 static void *nr_node_start(struct seq_file *seq, loff_t *pos)
841 {
842 	spin_lock_bh(&nr_node_list_lock);
843 	return seq_hlist_start_head(&nr_node_list, *pos);
844 }
845 
846 static void *nr_node_next(struct seq_file *seq, void *v, loff_t *pos)
847 {
848 	return seq_hlist_next(v, &nr_node_list, pos);
849 }
850 
851 static void nr_node_stop(struct seq_file *seq, void *v)
852 {
853 	spin_unlock_bh(&nr_node_list_lock);
854 }
855 
856 static int nr_node_show(struct seq_file *seq, void *v)
857 {
858 	char buf[11];
859 	int i;
860 
861 	if (v == SEQ_START_TOKEN)
862 		seq_puts(seq,
863 			 "callsign  mnemonic w n qual obs neigh qual obs neigh qual obs neigh\n");
864 	else {
865 		struct nr_node *nr_node = hlist_entry(v, struct nr_node,
866 						      node_node);
867 
868 		nr_node_lock(nr_node);
869 		seq_printf(seq, "%-9s %-7s  %d %d",
870 			ax2asc(buf, &nr_node->callsign),
871 			(nr_node->mnemonic[0] == '\0') ? "*" : nr_node->mnemonic,
872 			nr_node->which + 1,
873 			nr_node->count);
874 
875 		for (i = 0; i < nr_node->count; i++) {
876 			seq_printf(seq, "  %3d   %d %05d",
877 				nr_node->routes[i].quality,
878 				nr_node->routes[i].obs_count,
879 				nr_node->routes[i].neighbour->number);
880 		}
881 		nr_node_unlock(nr_node);
882 
883 		seq_puts(seq, "\n");
884 	}
885 	return 0;
886 }
887 
888 const struct seq_operations nr_node_seqops = {
889 	.start = nr_node_start,
890 	.next = nr_node_next,
891 	.stop = nr_node_stop,
892 	.show = nr_node_show,
893 };
894 
895 static void *nr_neigh_start(struct seq_file *seq, loff_t *pos)
896 {
897 	spin_lock_bh(&nr_neigh_list_lock);
898 	return seq_hlist_start_head(&nr_neigh_list, *pos);
899 }
900 
901 static void *nr_neigh_next(struct seq_file *seq, void *v, loff_t *pos)
902 {
903 	return seq_hlist_next(v, &nr_neigh_list, pos);
904 }
905 
906 static void nr_neigh_stop(struct seq_file *seq, void *v)
907 {
908 	spin_unlock_bh(&nr_neigh_list_lock);
909 }
910 
911 static int nr_neigh_show(struct seq_file *seq, void *v)
912 {
913 	char buf[11];
914 	int i;
915 
916 	if (v == SEQ_START_TOKEN)
917 		seq_puts(seq, "addr  callsign  dev  qual lock count failed digipeaters\n");
918 	else {
919 		struct nr_neigh *nr_neigh;
920 
921 		nr_neigh = hlist_entry(v, struct nr_neigh, neigh_node);
922 		seq_printf(seq, "%05d %-9s %-4s  %3d    %d   %3d    %3d",
923 			nr_neigh->number,
924 			ax2asc(buf, &nr_neigh->callsign),
925 			nr_neigh->dev ? nr_neigh->dev->name : "???",
926 			nr_neigh->quality,
927 			nr_neigh->locked,
928 			nr_neigh->count,
929 			nr_neigh->failed);
930 
931 		if (nr_neigh->digipeat != NULL) {
932 			for (i = 0; i < nr_neigh->digipeat->ndigi; i++)
933 				seq_printf(seq, " %s",
934 					   ax2asc(buf, &nr_neigh->digipeat->calls[i]));
935 		}
936 
937 		seq_puts(seq, "\n");
938 	}
939 	return 0;
940 }
941 
942 const struct seq_operations nr_neigh_seqops = {
943 	.start = nr_neigh_start,
944 	.next = nr_neigh_next,
945 	.stop = nr_neigh_stop,
946 	.show = nr_neigh_show,
947 };
948 #endif
949 
950 /*
951  *	Free all memory associated with the nodes and routes lists.
952  */
953 void nr_rt_free(void)
954 {
955 	struct nr_neigh *s = NULL;
956 	struct nr_node  *t = NULL;
957 	struct hlist_node *nodet;
958 
959 	spin_lock_bh(&nr_neigh_list_lock);
960 	spin_lock_bh(&nr_node_list_lock);
961 	nr_node_for_each_safe(t, nodet, &nr_node_list) {
962 		nr_node_lock(t);
963 		nr_remove_node_locked(t);
964 		nr_node_unlock(t);
965 	}
966 	nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
967 		while(s->count) {
968 			s->count--;
969 			nr_neigh_put(s);
970 		}
971 		nr_remove_neigh_locked(s);
972 	}
973 	spin_unlock_bh(&nr_node_list_lock);
974 	spin_unlock_bh(&nr_neigh_list_lock);
975 }
976