xref: /linux/net/core/rtnetlink.c (revision 60b2737de1b1ddfdb90f3ba622634eb49d6f3603)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Routing netlink socket interface: protocol independent part.
7  *
8  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9  *
10  *		This program is free software; you can redistribute it and/or
11  *		modify it under the terms of the GNU General Public License
12  *		as published by the Free Software Foundation; either version
13  *		2 of the License, or (at your option) any later version.
14  *
15  *	Fixes:
16  *	Vitaly E. Lavrov		RTA_OK arithmetics was wrong.
17  */
18 
19 #include <linux/config.h>
20 #include <linux/errno.h>
21 #include <linux/module.h>
22 #include <linux/types.h>
23 #include <linux/socket.h>
24 #include <linux/kernel.h>
25 #include <linux/sched.h>
26 #include <linux/timer.h>
27 #include <linux/string.h>
28 #include <linux/sockios.h>
29 #include <linux/net.h>
30 #include <linux/fcntl.h>
31 #include <linux/mm.h>
32 #include <linux/slab.h>
33 #include <linux/interrupt.h>
34 #include <linux/capability.h>
35 #include <linux/skbuff.h>
36 #include <linux/init.h>
37 #include <linux/security.h>
38 
39 #include <asm/uaccess.h>
40 #include <asm/system.h>
41 #include <asm/string.h>
42 
43 #include <linux/inet.h>
44 #include <linux/netdevice.h>
45 #include <net/ip.h>
46 #include <net/protocol.h>
47 #include <net/arp.h>
48 #include <net/route.h>
49 #include <net/udp.h>
50 #include <net/sock.h>
51 #include <net/pkt_sched.h>
52 
53 DECLARE_MUTEX(rtnl_sem);
54 
55 void rtnl_lock(void)
56 {
57 	rtnl_shlock();
58 }
59 
60 int rtnl_lock_interruptible(void)
61 {
62 	return down_interruptible(&rtnl_sem);
63 }
64 
65 void rtnl_unlock(void)
66 {
67 	rtnl_shunlock();
68 
69 	netdev_run_todo();
70 }
71 
72 int rtattr_parse(struct rtattr *tb[], int maxattr, struct rtattr *rta, int len)
73 {
74 	memset(tb, 0, sizeof(struct rtattr*)*maxattr);
75 
76 	while (RTA_OK(rta, len)) {
77 		unsigned flavor = rta->rta_type;
78 		if (flavor && flavor <= maxattr)
79 			tb[flavor-1] = rta;
80 		rta = RTA_NEXT(rta, len);
81 	}
82 	return 0;
83 }
84 
85 struct sock *rtnl;
86 
87 struct rtnetlink_link * rtnetlink_links[NPROTO];
88 
89 static const int rtm_min[RTM_NR_FAMILIES] =
90 {
91 	[RTM_FAM(RTM_NEWLINK)]      = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
92 	[RTM_FAM(RTM_NEWADDR)]      = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
93 	[RTM_FAM(RTM_NEWROUTE)]     = NLMSG_LENGTH(sizeof(struct rtmsg)),
94 	[RTM_FAM(RTM_NEWNEIGH)]     = NLMSG_LENGTH(sizeof(struct ndmsg)),
95 	[RTM_FAM(RTM_NEWRULE)]      = NLMSG_LENGTH(sizeof(struct rtmsg)),
96 	[RTM_FAM(RTM_NEWQDISC)]     = NLMSG_LENGTH(sizeof(struct tcmsg)),
97 	[RTM_FAM(RTM_NEWTCLASS)]    = NLMSG_LENGTH(sizeof(struct tcmsg)),
98 	[RTM_FAM(RTM_NEWTFILTER)]   = NLMSG_LENGTH(sizeof(struct tcmsg)),
99 	[RTM_FAM(RTM_NEWACTION)]    = NLMSG_LENGTH(sizeof(struct tcamsg)),
100 	[RTM_FAM(RTM_NEWPREFIX)]    = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
101 	[RTM_FAM(RTM_GETMULTICAST)] = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
102 	[RTM_FAM(RTM_GETANYCAST)]   = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
103 	[RTM_FAM(RTM_NEWNEIGHTBL)]  = NLMSG_LENGTH(sizeof(struct ndtmsg)),
104 };
105 
106 static const int rta_max[RTM_NR_FAMILIES] =
107 {
108 	[RTM_FAM(RTM_NEWLINK)]      = IFLA_MAX,
109 	[RTM_FAM(RTM_NEWADDR)]      = IFA_MAX,
110 	[RTM_FAM(RTM_NEWROUTE)]     = RTA_MAX,
111 	[RTM_FAM(RTM_NEWNEIGH)]     = NDA_MAX,
112 	[RTM_FAM(RTM_NEWRULE)]      = RTA_MAX,
113 	[RTM_FAM(RTM_NEWQDISC)]     = TCA_MAX,
114 	[RTM_FAM(RTM_NEWTCLASS)]    = TCA_MAX,
115 	[RTM_FAM(RTM_NEWTFILTER)]   = TCA_MAX,
116 	[RTM_FAM(RTM_NEWACTION)]    = TCAA_MAX,
117 	[RTM_FAM(RTM_NEWNEIGHTBL)]  = NDTA_MAX,
118 };
119 
120 void __rta_fill(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
121 {
122 	struct rtattr *rta;
123 	int size = RTA_LENGTH(attrlen);
124 
125 	rta = (struct rtattr*)skb_put(skb, RTA_ALIGN(size));
126 	rta->rta_type = attrtype;
127 	rta->rta_len = size;
128 	memcpy(RTA_DATA(rta), data, attrlen);
129 }
130 
131 size_t rtattr_strlcpy(char *dest, const struct rtattr *rta, size_t size)
132 {
133 	size_t ret = RTA_PAYLOAD(rta);
134 	char *src = RTA_DATA(rta);
135 
136 	if (ret > 0 && src[ret - 1] == '\0')
137 		ret--;
138 	if (size > 0) {
139 		size_t len = (ret >= size) ? size - 1 : ret;
140 		memset(dest, 0, size);
141 		memcpy(dest, src, len);
142 	}
143 	return ret;
144 }
145 
146 int rtnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
147 {
148 	int err = 0;
149 
150 	NETLINK_CB(skb).dst_groups = group;
151 	if (echo)
152 		atomic_inc(&skb->users);
153 	netlink_broadcast(rtnl, skb, pid, group, GFP_KERNEL);
154 	if (echo)
155 		err = netlink_unicast(rtnl, skb, pid, MSG_DONTWAIT);
156 	return err;
157 }
158 
159 int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics)
160 {
161 	struct rtattr *mx = (struct rtattr*)skb->tail;
162 	int i;
163 
164 	RTA_PUT(skb, RTA_METRICS, 0, NULL);
165 	for (i=0; i<RTAX_MAX; i++) {
166 		if (metrics[i])
167 			RTA_PUT(skb, i+1, sizeof(u32), metrics+i);
168 	}
169 	mx->rta_len = skb->tail - (u8*)mx;
170 	if (mx->rta_len == RTA_LENGTH(0))
171 		skb_trim(skb, (u8*)mx - skb->data);
172 	return 0;
173 
174 rtattr_failure:
175 	skb_trim(skb, (u8*)mx - skb->data);
176 	return -1;
177 }
178 
179 
180 static int rtnetlink_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
181 				 int type, u32 pid, u32 seq, u32 change,
182 				 unsigned int flags)
183 {
184 	struct ifinfomsg *r;
185 	struct nlmsghdr  *nlh;
186 	unsigned char	 *b = skb->tail;
187 
188 	nlh = NLMSG_NEW(skb, pid, seq, type, sizeof(*r), flags);
189 	r = NLMSG_DATA(nlh);
190 	r->ifi_family = AF_UNSPEC;
191 	r->ifi_type = dev->type;
192 	r->ifi_index = dev->ifindex;
193 	r->ifi_flags = dev_get_flags(dev);
194 	r->ifi_change = change;
195 
196 	RTA_PUT(skb, IFLA_IFNAME, strlen(dev->name)+1, dev->name);
197 
198 	if (1) {
199 		u32 txqlen = dev->tx_queue_len;
200 		RTA_PUT(skb, IFLA_TXQLEN, sizeof(txqlen), &txqlen);
201 	}
202 
203 	if (1) {
204 		u32 weight = dev->weight;
205 		RTA_PUT(skb, IFLA_WEIGHT, sizeof(weight), &weight);
206 	}
207 
208 	if (1) {
209 		struct rtnl_link_ifmap map = {
210 			.mem_start   = dev->mem_start,
211 			.mem_end     = dev->mem_end,
212 			.base_addr   = dev->base_addr,
213 			.irq         = dev->irq,
214 			.dma         = dev->dma,
215 			.port        = dev->if_port,
216 		};
217 		RTA_PUT(skb, IFLA_MAP, sizeof(map), &map);
218 	}
219 
220 	if (dev->addr_len) {
221 		RTA_PUT(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr);
222 		RTA_PUT(skb, IFLA_BROADCAST, dev->addr_len, dev->broadcast);
223 	}
224 
225 	if (1) {
226 		u32 mtu = dev->mtu;
227 		RTA_PUT(skb, IFLA_MTU, sizeof(mtu), &mtu);
228 	}
229 
230 	if (dev->ifindex != dev->iflink) {
231 		u32 iflink = dev->iflink;
232 		RTA_PUT(skb, IFLA_LINK, sizeof(iflink), &iflink);
233 	}
234 
235 	if (dev->qdisc_sleeping)
236 		RTA_PUT(skb, IFLA_QDISC,
237 			strlen(dev->qdisc_sleeping->ops->id) + 1,
238 			dev->qdisc_sleeping->ops->id);
239 
240 	if (dev->master) {
241 		u32 master = dev->master->ifindex;
242 		RTA_PUT(skb, IFLA_MASTER, sizeof(master), &master);
243 	}
244 
245 	if (dev->get_stats) {
246 		unsigned long *stats = (unsigned long*)dev->get_stats(dev);
247 		if (stats) {
248 			struct rtattr  *a;
249 			__u32	       *s;
250 			int		i;
251 			int		n = sizeof(struct rtnl_link_stats)/4;
252 
253 			a = __RTA_PUT(skb, IFLA_STATS, n*4);
254 			s = RTA_DATA(a);
255 			for (i=0; i<n; i++)
256 				s[i] = stats[i];
257 		}
258 	}
259 	nlh->nlmsg_len = skb->tail - b;
260 	return skb->len;
261 
262 nlmsg_failure:
263 rtattr_failure:
264 	skb_trim(skb, b - skb->data);
265 	return -1;
266 }
267 
268 static int rtnetlink_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
269 {
270 	int idx;
271 	int s_idx = cb->args[0];
272 	struct net_device *dev;
273 
274 	read_lock(&dev_base_lock);
275 	for (dev=dev_base, idx=0; dev; dev = dev->next, idx++) {
276 		if (idx < s_idx)
277 			continue;
278 		if (rtnetlink_fill_ifinfo(skb, dev, RTM_NEWLINK,
279 					  NETLINK_CB(cb->skb).pid,
280 					  cb->nlh->nlmsg_seq, 0,
281 					  NLM_F_MULTI) <= 0)
282 			break;
283 	}
284 	read_unlock(&dev_base_lock);
285 	cb->args[0] = idx;
286 
287 	return skb->len;
288 }
289 
290 static int do_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
291 {
292 	struct ifinfomsg  *ifm = NLMSG_DATA(nlh);
293 	struct rtattr    **ida = arg;
294 	struct net_device *dev;
295 	int err, send_addr_notify = 0;
296 
297 	if (ifm->ifi_index >= 0)
298 		dev = dev_get_by_index(ifm->ifi_index);
299 	else if (ida[IFLA_IFNAME - 1]) {
300 		char ifname[IFNAMSIZ];
301 
302 		if (rtattr_strlcpy(ifname, ida[IFLA_IFNAME - 1],
303 		                   IFNAMSIZ) >= IFNAMSIZ)
304 			return -EINVAL;
305 		dev = dev_get_by_name(ifname);
306 	} else
307 		return -EINVAL;
308 
309 	if (!dev)
310 		return -ENODEV;
311 
312 	err = -EINVAL;
313 
314 	if (ifm->ifi_flags)
315 		dev_change_flags(dev, ifm->ifi_flags);
316 
317 	if (ida[IFLA_MAP - 1]) {
318 		struct rtnl_link_ifmap *u_map;
319 		struct ifmap k_map;
320 
321 		if (!dev->set_config) {
322 			err = -EOPNOTSUPP;
323 			goto out;
324 		}
325 
326 		if (!netif_device_present(dev)) {
327 			err = -ENODEV;
328 			goto out;
329 		}
330 
331 		if (ida[IFLA_MAP - 1]->rta_len != RTA_LENGTH(sizeof(*u_map)))
332 			goto out;
333 
334 		u_map = RTA_DATA(ida[IFLA_MAP - 1]);
335 
336 		k_map.mem_start = (unsigned long) u_map->mem_start;
337 		k_map.mem_end = (unsigned long) u_map->mem_end;
338 		k_map.base_addr = (unsigned short) u_map->base_addr;
339 		k_map.irq = (unsigned char) u_map->irq;
340 		k_map.dma = (unsigned char) u_map->dma;
341 		k_map.port = (unsigned char) u_map->port;
342 
343 		err = dev->set_config(dev, &k_map);
344 
345 		if (err)
346 			goto out;
347 	}
348 
349 	if (ida[IFLA_ADDRESS - 1]) {
350 		if (!dev->set_mac_address) {
351 			err = -EOPNOTSUPP;
352 			goto out;
353 		}
354 		if (!netif_device_present(dev)) {
355 			err = -ENODEV;
356 			goto out;
357 		}
358 		if (ida[IFLA_ADDRESS - 1]->rta_len != RTA_LENGTH(dev->addr_len))
359 			goto out;
360 
361 		err = dev->set_mac_address(dev, RTA_DATA(ida[IFLA_ADDRESS - 1]));
362 		if (err)
363 			goto out;
364 		send_addr_notify = 1;
365 	}
366 
367 	if (ida[IFLA_BROADCAST - 1]) {
368 		if (ida[IFLA_BROADCAST - 1]->rta_len != RTA_LENGTH(dev->addr_len))
369 			goto out;
370 		memcpy(dev->broadcast, RTA_DATA(ida[IFLA_BROADCAST - 1]),
371 		       dev->addr_len);
372 		send_addr_notify = 1;
373 	}
374 
375 	if (ida[IFLA_MTU - 1]) {
376 		if (ida[IFLA_MTU - 1]->rta_len != RTA_LENGTH(sizeof(u32)))
377 			goto out;
378 		err = dev_set_mtu(dev, *((u32 *) RTA_DATA(ida[IFLA_MTU - 1])));
379 
380 		if (err)
381 			goto out;
382 
383 	}
384 
385 	if (ida[IFLA_TXQLEN - 1]) {
386 		if (ida[IFLA_TXQLEN - 1]->rta_len != RTA_LENGTH(sizeof(u32)))
387 			goto out;
388 
389 		dev->tx_queue_len = *((u32 *) RTA_DATA(ida[IFLA_TXQLEN - 1]));
390 	}
391 
392 	if (ida[IFLA_WEIGHT - 1]) {
393 		if (ida[IFLA_WEIGHT - 1]->rta_len != RTA_LENGTH(sizeof(u32)))
394 			goto out;
395 
396 		dev->weight = *((u32 *) RTA_DATA(ida[IFLA_WEIGHT - 1]));
397 	}
398 
399 	if (ifm->ifi_index >= 0 && ida[IFLA_IFNAME - 1]) {
400 		char ifname[IFNAMSIZ];
401 
402 		if (rtattr_strlcpy(ifname, ida[IFLA_IFNAME - 1],
403 		                   IFNAMSIZ) >= IFNAMSIZ)
404 			goto out;
405 		err = dev_change_name(dev, ifname);
406 		if (err)
407 			goto out;
408 	}
409 
410 	err = 0;
411 
412 out:
413 	if (send_addr_notify)
414 		call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
415 
416 	dev_put(dev);
417 	return err;
418 }
419 
420 static int rtnetlink_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
421 {
422 	int idx;
423 	int s_idx = cb->family;
424 
425 	if (s_idx == 0)
426 		s_idx = 1;
427 	for (idx=1; idx<NPROTO; idx++) {
428 		int type = cb->nlh->nlmsg_type-RTM_BASE;
429 		if (idx < s_idx || idx == PF_PACKET)
430 			continue;
431 		if (rtnetlink_links[idx] == NULL ||
432 		    rtnetlink_links[idx][type].dumpit == NULL)
433 			continue;
434 		if (idx > s_idx)
435 			memset(&cb->args[0], 0, sizeof(cb->args));
436 		if (rtnetlink_links[idx][type].dumpit(skb, cb))
437 			break;
438 	}
439 	cb->family = idx;
440 
441 	return skb->len;
442 }
443 
444 void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change)
445 {
446 	struct sk_buff *skb;
447 	int size = NLMSG_SPACE(sizeof(struct ifinfomsg) +
448 			       sizeof(struct rtnl_link_ifmap) +
449 			       sizeof(struct rtnl_link_stats) + 128);
450 
451 	skb = alloc_skb(size, GFP_KERNEL);
452 	if (!skb)
453 		return;
454 
455 	if (rtnetlink_fill_ifinfo(skb, dev, type, current->pid, 0, change, 0) < 0) {
456 		kfree_skb(skb);
457 		return;
458 	}
459 	NETLINK_CB(skb).dst_groups = RTMGRP_LINK;
460 	netlink_broadcast(rtnl, skb, 0, RTMGRP_LINK, GFP_KERNEL);
461 }
462 
463 static int rtnetlink_done(struct netlink_callback *cb)
464 {
465 	return 0;
466 }
467 
468 /* Protected by RTNL sempahore.  */
469 static struct rtattr **rta_buf;
470 static int rtattr_max;
471 
472 /* Process one rtnetlink message. */
473 
474 static __inline__ int
475 rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, int *errp)
476 {
477 	struct rtnetlink_link *link;
478 	struct rtnetlink_link *link_tab;
479 	int sz_idx, kind;
480 	int min_len;
481 	int family;
482 	int type;
483 	int err;
484 
485 	/* Only requests are handled by kernel now */
486 	if (!(nlh->nlmsg_flags&NLM_F_REQUEST))
487 		return 0;
488 
489 	type = nlh->nlmsg_type;
490 
491 	/* A control message: ignore them */
492 	if (type < RTM_BASE)
493 		return 0;
494 
495 	/* Unknown message: reply with EINVAL */
496 	if (type > RTM_MAX)
497 		goto err_inval;
498 
499 	type -= RTM_BASE;
500 
501 	/* All the messages must have at least 1 byte length */
502 	if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct rtgenmsg)))
503 		return 0;
504 
505 	family = ((struct rtgenmsg*)NLMSG_DATA(nlh))->rtgen_family;
506 	if (family >= NPROTO) {
507 		*errp = -EAFNOSUPPORT;
508 		return -1;
509 	}
510 
511 	link_tab = rtnetlink_links[family];
512 	if (link_tab == NULL)
513 		link_tab = rtnetlink_links[PF_UNSPEC];
514 	link = &link_tab[type];
515 
516 	sz_idx = type>>2;
517 	kind = type&3;
518 
519 	if (kind != 2 && security_netlink_recv(skb)) {
520 		*errp = -EPERM;
521 		return -1;
522 	}
523 
524 	if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {
525 		u32 rlen;
526 
527 		if (link->dumpit == NULL)
528 			link = &(rtnetlink_links[PF_UNSPEC][type]);
529 
530 		if (link->dumpit == NULL)
531 			goto err_inval;
532 
533 		if ((*errp = netlink_dump_start(rtnl, skb, nlh,
534 						link->dumpit,
535 						rtnetlink_done)) != 0) {
536 			return -1;
537 		}
538 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
539 		if (rlen > skb->len)
540 			rlen = skb->len;
541 		skb_pull(skb, rlen);
542 		return -1;
543 	}
544 
545 	memset(rta_buf, 0, (rtattr_max * sizeof(struct rtattr *)));
546 
547 	min_len = rtm_min[sz_idx];
548 	if (nlh->nlmsg_len < min_len)
549 		goto err_inval;
550 
551 	if (nlh->nlmsg_len > min_len) {
552 		int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
553 		struct rtattr *attr = (void*)nlh + NLMSG_ALIGN(min_len);
554 
555 		while (RTA_OK(attr, attrlen)) {
556 			unsigned flavor = attr->rta_type;
557 			if (flavor) {
558 				if (flavor > rta_max[sz_idx])
559 					goto err_inval;
560 				rta_buf[flavor-1] = attr;
561 			}
562 			attr = RTA_NEXT(attr, attrlen);
563 		}
564 	}
565 
566 	if (link->doit == NULL)
567 		link = &(rtnetlink_links[PF_UNSPEC][type]);
568 	if (link->doit == NULL)
569 		goto err_inval;
570 	err = link->doit(skb, nlh, (void *)&rta_buf[0]);
571 
572 	*errp = err;
573 	return err;
574 
575 err_inval:
576 	*errp = -EINVAL;
577 	return -1;
578 }
579 
580 /*
581  * Process one packet of messages.
582  * Malformed skbs with wrong lengths of messages are discarded silently.
583  */
584 
585 static inline int rtnetlink_rcv_skb(struct sk_buff *skb)
586 {
587 	int err;
588 	struct nlmsghdr * nlh;
589 
590 	while (skb->len >= NLMSG_SPACE(0)) {
591 		u32 rlen;
592 
593 		nlh = (struct nlmsghdr *)skb->data;
594 		if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
595 			return 0;
596 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
597 		if (rlen > skb->len)
598 			rlen = skb->len;
599 		if (rtnetlink_rcv_msg(skb, nlh, &err)) {
600 			/* Not error, but we must interrupt processing here:
601 			 *   Note, that in this case we do not pull message
602 			 *   from skb, it will be processed later.
603 			 */
604 			if (err == 0)
605 				return -1;
606 			netlink_ack(skb, nlh, err);
607 		} else if (nlh->nlmsg_flags&NLM_F_ACK)
608 			netlink_ack(skb, nlh, 0);
609 		skb_pull(skb, rlen);
610 	}
611 
612 	return 0;
613 }
614 
615 /*
616  *  rtnetlink input queue processing routine:
617  *	- process as much as there was in the queue upon entry.
618  *	- feed skbs to rtnetlink_rcv_skb, until it refuse a message,
619  *	  that will occur, when a dump started.
620  */
621 
622 static void rtnetlink_rcv(struct sock *sk, int len)
623 {
624 	unsigned int qlen = skb_queue_len(&sk->sk_receive_queue);
625 
626 	do {
627 		struct sk_buff *skb;
628 
629 		rtnl_lock();
630 
631 		if (qlen > skb_queue_len(&sk->sk_receive_queue))
632 			qlen = skb_queue_len(&sk->sk_receive_queue);
633 
634 		for (; qlen; qlen--) {
635 			skb = skb_dequeue(&sk->sk_receive_queue);
636 			if (rtnetlink_rcv_skb(skb)) {
637 				if (skb->len)
638 					skb_queue_head(&sk->sk_receive_queue,
639 						       skb);
640 				else {
641 					kfree_skb(skb);
642 					qlen--;
643 				}
644 				break;
645 			}
646 			kfree_skb(skb);
647 		}
648 
649 		up(&rtnl_sem);
650 
651 		netdev_run_todo();
652 	} while (qlen);
653 }
654 
655 static struct rtnetlink_link link_rtnetlink_table[RTM_NR_MSGTYPES] =
656 {
657 	[RTM_GETLINK     - RTM_BASE] = { .dumpit = rtnetlink_dump_ifinfo },
658 	[RTM_SETLINK     - RTM_BASE] = { .doit   = do_setlink		 },
659 	[RTM_GETADDR     - RTM_BASE] = { .dumpit = rtnetlink_dump_all	 },
660 	[RTM_GETROUTE    - RTM_BASE] = { .dumpit = rtnetlink_dump_all	 },
661 	[RTM_NEWNEIGH    - RTM_BASE] = { .doit   = neigh_add		 },
662 	[RTM_DELNEIGH    - RTM_BASE] = { .doit   = neigh_delete		 },
663 	[RTM_GETNEIGH    - RTM_BASE] = { .dumpit = neigh_dump_info	 },
664 	[RTM_GETRULE     - RTM_BASE] = { .dumpit = rtnetlink_dump_all	 },
665 	[RTM_GETNEIGHTBL - RTM_BASE] = { .dumpit = neightbl_dump_info	 },
666 	[RTM_SETNEIGHTBL - RTM_BASE] = { .doit   = neightbl_set		 },
667 };
668 
669 static int rtnetlink_event(struct notifier_block *this, unsigned long event, void *ptr)
670 {
671 	struct net_device *dev = ptr;
672 	switch (event) {
673 	case NETDEV_UNREGISTER:
674 		rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
675 		break;
676 	case NETDEV_REGISTER:
677 		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
678 		break;
679 	case NETDEV_UP:
680 	case NETDEV_DOWN:
681 		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
682 		break;
683 	case NETDEV_CHANGE:
684 	case NETDEV_GOING_DOWN:
685 		break;
686 	default:
687 		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
688 		break;
689 	}
690 	return NOTIFY_DONE;
691 }
692 
693 static struct notifier_block rtnetlink_dev_notifier = {
694 	.notifier_call	= rtnetlink_event,
695 };
696 
697 void __init rtnetlink_init(void)
698 {
699 	int i;
700 
701 	rtattr_max = 0;
702 	for (i = 0; i < ARRAY_SIZE(rta_max); i++)
703 		if (rta_max[i] > rtattr_max)
704 			rtattr_max = rta_max[i];
705 	rta_buf = kmalloc(rtattr_max * sizeof(struct rtattr *), GFP_KERNEL);
706 	if (!rta_buf)
707 		panic("rtnetlink_init: cannot allocate rta_buf\n");
708 
709 	rtnl = netlink_kernel_create(NETLINK_ROUTE, rtnetlink_rcv);
710 	if (rtnl == NULL)
711 		panic("rtnetlink_init: cannot initialize rtnetlink\n");
712 	netlink_set_nonroot(NETLINK_ROUTE, NL_NONROOT_RECV);
713 	register_netdevice_notifier(&rtnetlink_dev_notifier);
714 	rtnetlink_links[PF_UNSPEC] = link_rtnetlink_table;
715 	rtnetlink_links[PF_PACKET] = link_rtnetlink_table;
716 }
717 
718 EXPORT_SYMBOL(__rta_fill);
719 EXPORT_SYMBOL(rtattr_strlcpy);
720 EXPORT_SYMBOL(rtattr_parse);
721 EXPORT_SYMBOL(rtnetlink_links);
722 EXPORT_SYMBOL(rtnetlink_put_metrics);
723 EXPORT_SYMBOL(rtnl);
724 EXPORT_SYMBOL(rtnl_lock);
725 EXPORT_SYMBOL(rtnl_lock_interruptible);
726 EXPORT_SYMBOL(rtnl_sem);
727 EXPORT_SYMBOL(rtnl_unlock);
728