xref: /linux/net/ipv6/icmp.c (revision 36ca1195ad7f760a6af3814cb002bd3a3d4b4db1)
1 /*
2  *	Internet Control Message Protocol (ICMPv6)
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	$Id: icmp.c,v 1.38 2002/02/08 03:57:19 davem Exp $
9  *
10  *	Based on net/ipv4/icmp.c
11  *
12  *	RFC 1885
13  *
14  *	This program is free software; you can redistribute it and/or
15  *      modify it under the terms of the GNU General Public License
16  *      as published by the Free Software Foundation; either version
17  *      2 of the License, or (at your option) any later version.
18  */
19 
20 /*
21  *	Changes:
22  *
23  *	Andi Kleen		:	exception handling
24  *	Andi Kleen			add rate limits. never reply to a icmp.
25  *					add more length checks and other fixes.
26  *	yoshfuji		:	ensure to sent parameter problem for
27  *					fragments.
28  *	YOSHIFUJI Hideaki @USAGI:	added sysctl for icmp rate limit.
29  *	Randy Dunlap and
30  *	YOSHIFUJI Hideaki @USAGI:	Per-interface statistics support
31  *	Kazunori MIYAZAWA @USAGI:       change output process to use ip6_append_data
32  */
33 
34 #include <linux/module.h>
35 #include <linux/errno.h>
36 #include <linux/types.h>
37 #include <linux/socket.h>
38 #include <linux/in.h>
39 #include <linux/kernel.h>
40 #include <linux/sched.h>
41 #include <linux/sockios.h>
42 #include <linux/net.h>
43 #include <linux/skbuff.h>
44 #include <linux/init.h>
45 
46 #ifdef CONFIG_SYSCTL
47 #include <linux/sysctl.h>
48 #endif
49 
50 #include <linux/inet.h>
51 #include <linux/netdevice.h>
52 #include <linux/icmpv6.h>
53 
54 #include <net/ip.h>
55 #include <net/sock.h>
56 
57 #include <net/ipv6.h>
58 #include <net/ip6_checksum.h>
59 #include <net/protocol.h>
60 #include <net/raw.h>
61 #include <net/rawv6.h>
62 #include <net/transp_v6.h>
63 #include <net/ip6_route.h>
64 #include <net/addrconf.h>
65 #include <net/icmp.h>
66 
67 #include <asm/uaccess.h>
68 #include <asm/system.h>
69 
70 DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics);
71 
72 /*
73  *	The ICMP socket(s). This is the most convenient way to flow control
74  *	our ICMP output as well as maintain a clean interface throughout
75  *	all layers. All Socketless IP sends will soon be gone.
76  *
77  *	On SMP we have one ICMP socket per-cpu.
78  */
79 static DEFINE_PER_CPU(struct socket *, __icmpv6_socket) = NULL;
80 #define icmpv6_socket	__get_cpu_var(__icmpv6_socket)
81 
82 static int icmpv6_rcv(struct sk_buff **pskb, unsigned int *nhoffp);
83 
84 static struct inet6_protocol icmpv6_protocol = {
85 	.handler	=	icmpv6_rcv,
86 	.flags		=	INET6_PROTO_FINAL,
87 };
88 
89 static __inline__ int icmpv6_xmit_lock(void)
90 {
91 	local_bh_disable();
92 
93 	if (unlikely(!spin_trylock(&icmpv6_socket->sk->sk_lock.slock))) {
94 		/* This can happen if the output path (f.e. SIT or
95 		 * ip6ip6 tunnel) signals dst_link_failure() for an
96 		 * outgoing ICMP6 packet.
97 		 */
98 		local_bh_enable();
99 		return 1;
100 	}
101 	return 0;
102 }
103 
104 static __inline__ void icmpv6_xmit_unlock(void)
105 {
106 	spin_unlock_bh(&icmpv6_socket->sk->sk_lock.slock);
107 }
108 
109 /*
110  * Slightly more convenient version of icmpv6_send.
111  */
112 void icmpv6_param_prob(struct sk_buff *skb, int code, int pos)
113 {
114 	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
115 	kfree_skb(skb);
116 }
117 
118 /*
119  * Figure out, may we reply to this packet with icmp error.
120  *
121  * We do not reply, if:
122  *	- it was icmp error message.
123  *	- it is truncated, so that it is known, that protocol is ICMPV6
124  *	  (i.e. in the middle of some exthdr)
125  *
126  *	--ANK (980726)
127  */
128 
129 static int is_ineligible(struct sk_buff *skb)
130 {
131 	int ptr = (u8*)(skb->nh.ipv6h+1) - skb->data;
132 	int len = skb->len - ptr;
133 	__u8 nexthdr = skb->nh.ipv6h->nexthdr;
134 
135 	if (len < 0)
136 		return 1;
137 
138 	ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr);
139 	if (ptr < 0)
140 		return 0;
141 	if (nexthdr == IPPROTO_ICMPV6) {
142 		u8 _type, *tp;
143 		tp = skb_header_pointer(skb,
144 			ptr+offsetof(struct icmp6hdr, icmp6_type),
145 			sizeof(_type), &_type);
146 		if (tp == NULL ||
147 		    !(*tp & ICMPV6_INFOMSG_MASK))
148 			return 1;
149 	}
150 	return 0;
151 }
152 
153 static int sysctl_icmpv6_time = 1*HZ;
154 
155 /*
156  * Check the ICMP output rate limit
157  */
158 static inline int icmpv6_xrlim_allow(struct sock *sk, int type,
159 				     struct flowi *fl)
160 {
161 	struct dst_entry *dst;
162 	int res = 0;
163 
164 	/* Informational messages are not limited. */
165 	if (type & ICMPV6_INFOMSG_MASK)
166 		return 1;
167 
168 	/* Do not limit pmtu discovery, it would break it. */
169 	if (type == ICMPV6_PKT_TOOBIG)
170 		return 1;
171 
172 	/*
173 	 * Look up the output route.
174 	 * XXX: perhaps the expire for routing entries cloned by
175 	 * this lookup should be more aggressive (not longer than timeout).
176 	 */
177 	dst = ip6_route_output(sk, fl);
178 	if (dst->error) {
179 		IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
180 	} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
181 		res = 1;
182 	} else {
183 		struct rt6_info *rt = (struct rt6_info *)dst;
184 		int tmo = sysctl_icmpv6_time;
185 
186 		/* Give more bandwidth to wider prefixes. */
187 		if (rt->rt6i_dst.plen < 128)
188 			tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
189 
190 		res = xrlim_allow(dst, tmo);
191 	}
192 	dst_release(dst);
193 	return res;
194 }
195 
196 /*
197  *	an inline helper for the "simple" if statement below
198  *	checks if parameter problem report is caused by an
199  *	unrecognized IPv6 option that has the Option Type
200  *	highest-order two bits set to 10
201  */
202 
203 static __inline__ int opt_unrec(struct sk_buff *skb, __u32 offset)
204 {
205 	u8 _optval, *op;
206 
207 	offset += skb->nh.raw - skb->data;
208 	op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
209 	if (op == NULL)
210 		return 1;
211 	return (*op & 0xC0) == 0x80;
212 }
213 
214 static int icmpv6_push_pending_frames(struct sock *sk, struct flowi *fl, struct icmp6hdr *thdr, int len)
215 {
216 	struct sk_buff *skb;
217 	struct icmp6hdr *icmp6h;
218 	int err = 0;
219 
220 	if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
221 		goto out;
222 
223 	icmp6h = (struct icmp6hdr*) skb->h.raw;
224 	memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
225 	icmp6h->icmp6_cksum = 0;
226 
227 	if (skb_queue_len(&sk->sk_write_queue) == 1) {
228 		skb->csum = csum_partial((char *)icmp6h,
229 					sizeof(struct icmp6hdr), skb->csum);
230 		icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
231 						      &fl->fl6_dst,
232 						      len, fl->proto,
233 						      skb->csum);
234 	} else {
235 		u32 tmp_csum = 0;
236 
237 		skb_queue_walk(&sk->sk_write_queue, skb) {
238 			tmp_csum = csum_add(tmp_csum, skb->csum);
239 		}
240 
241 		tmp_csum = csum_partial((char *)icmp6h,
242 					sizeof(struct icmp6hdr), tmp_csum);
243 		tmp_csum = csum_ipv6_magic(&fl->fl6_src,
244 					   &fl->fl6_dst,
245 					   len, fl->proto, tmp_csum);
246 		icmp6h->icmp6_cksum = tmp_csum;
247 	}
248 	if (icmp6h->icmp6_cksum == 0)
249 		icmp6h->icmp6_cksum = -1;
250 	ip6_push_pending_frames(sk);
251 out:
252 	return err;
253 }
254 
255 struct icmpv6_msg {
256 	struct sk_buff	*skb;
257 	int		offset;
258 };
259 
260 static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
261 {
262 	struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
263 	struct sk_buff *org_skb = msg->skb;
264 	__u32 csum = 0;
265 
266 	csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
267 				      to, len, csum);
268 	skb->csum = csum_block_add(skb->csum, csum, odd);
269 	return 0;
270 }
271 
272 /*
273  *	Send an ICMP message in response to a packet in error
274  */
275 void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
276 		 struct net_device *dev)
277 {
278 	struct inet6_dev *idev = NULL;
279 	struct ipv6hdr *hdr = skb->nh.ipv6h;
280 	struct sock *sk;
281 	struct ipv6_pinfo *np;
282 	struct in6_addr *saddr = NULL;
283 	struct dst_entry *dst;
284 	struct icmp6hdr tmp_hdr;
285 	struct flowi fl;
286 	struct icmpv6_msg msg;
287 	int iif = 0;
288 	int addr_type = 0;
289 	int len;
290 	int hlimit;
291 	int err = 0;
292 
293 	if ((u8*)hdr < skb->head || (u8*)(hdr+1) > skb->tail)
294 		return;
295 
296 	/*
297 	 *	Make sure we respect the rules
298 	 *	i.e. RFC 1885 2.4(e)
299 	 *	Rule (e.1) is enforced by not using icmpv6_send
300 	 *	in any code that processes icmp errors.
301 	 */
302 	addr_type = ipv6_addr_type(&hdr->daddr);
303 
304 	if (ipv6_chk_addr(&hdr->daddr, skb->dev, 0))
305 		saddr = &hdr->daddr;
306 
307 	/*
308 	 *	Dest addr check
309 	 */
310 
311 	if ((addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST)) {
312 		if (type != ICMPV6_PKT_TOOBIG &&
313 		    !(type == ICMPV6_PARAMPROB &&
314 		      code == ICMPV6_UNK_OPTION &&
315 		      (opt_unrec(skb, info))))
316 			return;
317 
318 		saddr = NULL;
319 	}
320 
321 	addr_type = ipv6_addr_type(&hdr->saddr);
322 
323 	/*
324 	 *	Source addr check
325 	 */
326 
327 	if (addr_type & IPV6_ADDR_LINKLOCAL)
328 		iif = skb->dev->ifindex;
329 
330 	/*
331 	 *	Must not send if we know that source is Anycast also.
332 	 *	for now we don't know that.
333 	 */
334 	if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
335 		LIMIT_NETDEBUG(
336 			printk(KERN_DEBUG "icmpv6_send: addr_any/mcast source\n"));
337 		return;
338 	}
339 
340 	/*
341 	 *	Never answer to a ICMP packet.
342 	 */
343 	if (is_ineligible(skb)) {
344 		LIMIT_NETDEBUG(
345 			printk(KERN_DEBUG "icmpv6_send: no reply to icmp error\n"));
346 		return;
347 	}
348 
349 	memset(&fl, 0, sizeof(fl));
350 	fl.proto = IPPROTO_ICMPV6;
351 	ipv6_addr_copy(&fl.fl6_dst, &hdr->saddr);
352 	if (saddr)
353 		ipv6_addr_copy(&fl.fl6_src, saddr);
354 	fl.oif = iif;
355 	fl.fl_icmp_type = type;
356 	fl.fl_icmp_code = code;
357 
358 	if (icmpv6_xmit_lock())
359 		return;
360 
361 	sk = icmpv6_socket->sk;
362 	np = inet6_sk(sk);
363 
364 	if (!icmpv6_xrlim_allow(sk, type, &fl))
365 		goto out;
366 
367 	tmp_hdr.icmp6_type = type;
368 	tmp_hdr.icmp6_code = code;
369 	tmp_hdr.icmp6_cksum = 0;
370 	tmp_hdr.icmp6_pointer = htonl(info);
371 
372 	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
373 		fl.oif = np->mcast_oif;
374 
375 	err = ip6_dst_lookup(sk, &dst, &fl);
376 	if (err)
377 		goto out;
378 	if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
379 		goto out_dst_release;
380 
381 	if (ipv6_addr_is_multicast(&fl.fl6_dst))
382 		hlimit = np->mcast_hops;
383 	else
384 		hlimit = np->hop_limit;
385 	if (hlimit < 0)
386 		hlimit = dst_metric(dst, RTAX_HOPLIMIT);
387 	if (hlimit < 0)
388 		hlimit = ipv6_get_hoplimit(dst->dev);
389 
390 	msg.skb = skb;
391 	msg.offset = skb->nh.raw - skb->data;
392 
393 	len = skb->len - msg.offset;
394 	len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) -sizeof(struct icmp6hdr));
395 	if (len < 0) {
396 		LIMIT_NETDEBUG(
397 			printk(KERN_DEBUG "icmp: len problem\n"));
398 		goto out_dst_release;
399 	}
400 
401 	idev = in6_dev_get(skb->dev);
402 
403 	err = ip6_append_data(sk, icmpv6_getfrag, &msg,
404 			      len + sizeof(struct icmp6hdr),
405 			      sizeof(struct icmp6hdr),
406 			      hlimit, NULL, &fl, (struct rt6_info*)dst,
407 			      MSG_DONTWAIT);
408 	if (err) {
409 		ip6_flush_pending_frames(sk);
410 		goto out_put;
411 	}
412 	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, len + sizeof(struct icmp6hdr));
413 
414 	if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
415 		ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_OUTDESTUNREACHS, type - ICMPV6_DEST_UNREACH);
416 	ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTMSGS);
417 
418 out_put:
419 	if (likely(idev != NULL))
420 		in6_dev_put(idev);
421 out_dst_release:
422 	dst_release(dst);
423 out:
424 	icmpv6_xmit_unlock();
425 }
426 
427 static void icmpv6_echo_reply(struct sk_buff *skb)
428 {
429 	struct sock *sk;
430 	struct inet6_dev *idev;
431 	struct ipv6_pinfo *np;
432 	struct in6_addr *saddr = NULL;
433 	struct icmp6hdr *icmph = (struct icmp6hdr *) skb->h.raw;
434 	struct icmp6hdr tmp_hdr;
435 	struct flowi fl;
436 	struct icmpv6_msg msg;
437 	struct dst_entry *dst;
438 	int err = 0;
439 	int hlimit;
440 
441 	saddr = &skb->nh.ipv6h->daddr;
442 
443 	if (!ipv6_unicast_destination(skb))
444 		saddr = NULL;
445 
446 	memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
447 	tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;
448 
449 	memset(&fl, 0, sizeof(fl));
450 	fl.proto = IPPROTO_ICMPV6;
451 	ipv6_addr_copy(&fl.fl6_dst, &skb->nh.ipv6h->saddr);
452 	if (saddr)
453 		ipv6_addr_copy(&fl.fl6_src, saddr);
454 	fl.oif = skb->dev->ifindex;
455 	fl.fl_icmp_type = ICMPV6_ECHO_REPLY;
456 
457 	if (icmpv6_xmit_lock())
458 		return;
459 
460 	sk = icmpv6_socket->sk;
461 	np = inet6_sk(sk);
462 
463 	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
464 		fl.oif = np->mcast_oif;
465 
466 	err = ip6_dst_lookup(sk, &dst, &fl);
467 	if (err)
468 		goto out;
469 	if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
470 		goto out_dst_release;
471 
472 	if (ipv6_addr_is_multicast(&fl.fl6_dst))
473 		hlimit = np->mcast_hops;
474 	else
475 		hlimit = np->hop_limit;
476 	if (hlimit < 0)
477 		hlimit = dst_metric(dst, RTAX_HOPLIMIT);
478 	if (hlimit < 0)
479 		hlimit = ipv6_get_hoplimit(dst->dev);
480 
481 	idev = in6_dev_get(skb->dev);
482 
483 	msg.skb = skb;
484 	msg.offset = 0;
485 
486 	err = ip6_append_data(sk, icmpv6_getfrag, &msg, skb->len + sizeof(struct icmp6hdr),
487 				sizeof(struct icmp6hdr), hlimit, NULL, &fl,
488 				(struct rt6_info*)dst, MSG_DONTWAIT);
489 
490 	if (err) {
491 		ip6_flush_pending_frames(sk);
492 		goto out_put;
493 	}
494 	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, skb->len + sizeof(struct icmp6hdr));
495 
496         ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTECHOREPLIES);
497         ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTMSGS);
498 
499 out_put:
500 	if (likely(idev != NULL))
501 		in6_dev_put(idev);
502 out_dst_release:
503 	dst_release(dst);
504 out:
505 	icmpv6_xmit_unlock();
506 }
507 
508 static void icmpv6_notify(struct sk_buff *skb, int type, int code, u32 info)
509 {
510 	struct in6_addr *saddr, *daddr;
511 	struct inet6_protocol *ipprot;
512 	struct sock *sk;
513 	int inner_offset;
514 	int hash;
515 	u8 nexthdr;
516 
517 	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
518 		return;
519 
520 	nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
521 	if (ipv6_ext_hdr(nexthdr)) {
522 		/* now skip over extension headers */
523 		inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
524 		if (inner_offset<0)
525 			return;
526 	} else {
527 		inner_offset = sizeof(struct ipv6hdr);
528 	}
529 
530 	/* Checkin header including 8 bytes of inner protocol header. */
531 	if (!pskb_may_pull(skb, inner_offset+8))
532 		return;
533 
534 	saddr = &skb->nh.ipv6h->saddr;
535 	daddr = &skb->nh.ipv6h->daddr;
536 
537 	/* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
538 	   Without this we will not able f.e. to make source routed
539 	   pmtu discovery.
540 	   Corresponding argument (opt) to notifiers is already added.
541 	   --ANK (980726)
542 	 */
543 
544 	hash = nexthdr & (MAX_INET_PROTOS - 1);
545 
546 	rcu_read_lock();
547 	ipprot = rcu_dereference(inet6_protos[hash]);
548 	if (ipprot && ipprot->err_handler)
549 		ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
550 	rcu_read_unlock();
551 
552 	read_lock(&raw_v6_lock);
553 	if ((sk = sk_head(&raw_v6_htable[hash])) != NULL) {
554 		while((sk = __raw_v6_lookup(sk, nexthdr, daddr, saddr))) {
555 			rawv6_err(sk, skb, NULL, type, code, inner_offset, info);
556 			sk = sk_next(sk);
557 		}
558 	}
559 	read_unlock(&raw_v6_lock);
560 }
561 
562 /*
563  *	Handle icmp messages
564  */
565 
566 static int icmpv6_rcv(struct sk_buff **pskb, unsigned int *nhoffp)
567 {
568 	struct sk_buff *skb = *pskb;
569 	struct net_device *dev = skb->dev;
570 	struct inet6_dev *idev = __in6_dev_get(dev);
571 	struct in6_addr *saddr, *daddr;
572 	struct ipv6hdr *orig_hdr;
573 	struct icmp6hdr *hdr;
574 	int type;
575 
576 	ICMP6_INC_STATS_BH(idev, ICMP6_MIB_INMSGS);
577 
578 	saddr = &skb->nh.ipv6h->saddr;
579 	daddr = &skb->nh.ipv6h->daddr;
580 
581 	/* Perform checksum. */
582 	if (skb->ip_summed == CHECKSUM_HW) {
583 		skb->ip_summed = CHECKSUM_UNNECESSARY;
584 		if (csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
585 				    skb->csum)) {
586 			LIMIT_NETDEBUG(
587 				printk(KERN_DEBUG "ICMPv6 hw checksum failed\n"));
588 			skb->ip_summed = CHECKSUM_NONE;
589 		}
590 	}
591 	if (skb->ip_summed == CHECKSUM_NONE) {
592 		if (csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
593 				    skb_checksum(skb, 0, skb->len, 0))) {
594 			LIMIT_NETDEBUG(
595 				printk(KERN_DEBUG "ICMPv6 checksum failed [%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x > %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x]\n",
596 				       NIP6(*saddr), NIP6(*daddr)));
597 			goto discard_it;
598 		}
599 	}
600 
601 	if (!pskb_pull(skb, sizeof(struct icmp6hdr)))
602 		goto discard_it;
603 
604 	hdr = (struct icmp6hdr *) skb->h.raw;
605 
606 	type = hdr->icmp6_type;
607 
608 	if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
609 		ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_INDESTUNREACHS, type - ICMPV6_DEST_UNREACH);
610 	else if (type >= ICMPV6_ECHO_REQUEST && type <= NDISC_REDIRECT)
611 		ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_INECHOS, type - ICMPV6_ECHO_REQUEST);
612 
613 	switch (type) {
614 	case ICMPV6_ECHO_REQUEST:
615 		icmpv6_echo_reply(skb);
616 		break;
617 
618 	case ICMPV6_ECHO_REPLY:
619 		/* we couldn't care less */
620 		break;
621 
622 	case ICMPV6_PKT_TOOBIG:
623 		/* BUGGG_FUTURE: if packet contains rthdr, we cannot update
624 		   standard destination cache. Seems, only "advanced"
625 		   destination cache will allow to solve this problem
626 		   --ANK (980726)
627 		 */
628 		if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
629 			goto discard_it;
630 		hdr = (struct icmp6hdr *) skb->h.raw;
631 		orig_hdr = (struct ipv6hdr *) (hdr + 1);
632 		rt6_pmtu_discovery(&orig_hdr->daddr, &orig_hdr->saddr, dev,
633 				   ntohl(hdr->icmp6_mtu));
634 
635 		/*
636 		 *	Drop through to notify
637 		 */
638 
639 	case ICMPV6_DEST_UNREACH:
640 	case ICMPV6_TIME_EXCEED:
641 	case ICMPV6_PARAMPROB:
642 		icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
643 		break;
644 
645 	case NDISC_ROUTER_SOLICITATION:
646 	case NDISC_ROUTER_ADVERTISEMENT:
647 	case NDISC_NEIGHBOUR_SOLICITATION:
648 	case NDISC_NEIGHBOUR_ADVERTISEMENT:
649 	case NDISC_REDIRECT:
650 		ndisc_rcv(skb);
651 		break;
652 
653 	case ICMPV6_MGM_QUERY:
654 		igmp6_event_query(skb);
655 		break;
656 
657 	case ICMPV6_MGM_REPORT:
658 		igmp6_event_report(skb);
659 		break;
660 
661 	case ICMPV6_MGM_REDUCTION:
662 	case ICMPV6_NI_QUERY:
663 	case ICMPV6_NI_REPLY:
664 	case ICMPV6_MLD2_REPORT:
665 	case ICMPV6_DHAAD_REQUEST:
666 	case ICMPV6_DHAAD_REPLY:
667 	case ICMPV6_MOBILE_PREFIX_SOL:
668 	case ICMPV6_MOBILE_PREFIX_ADV:
669 		break;
670 
671 	default:
672 		LIMIT_NETDEBUG(
673 			printk(KERN_DEBUG "icmpv6: msg of unknown type\n"));
674 
675 		/* informational */
676 		if (type & ICMPV6_INFOMSG_MASK)
677 			break;
678 
679 		/*
680 		 * error of unknown type.
681 		 * must pass to upper level
682 		 */
683 
684 		icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
685 	};
686 	kfree_skb(skb);
687 	return 0;
688 
689 discard_it:
690 	ICMP6_INC_STATS_BH(idev, ICMP6_MIB_INERRORS);
691 	kfree_skb(skb);
692 	return 0;
693 }
694 
695 int __init icmpv6_init(struct net_proto_family *ops)
696 {
697 	struct sock *sk;
698 	int err, i, j;
699 
700 	for (i = 0; i < NR_CPUS; i++) {
701 		if (!cpu_possible(i))
702 			continue;
703 
704 		err = sock_create_kern(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6,
705 				       &per_cpu(__icmpv6_socket, i));
706 		if (err < 0) {
707 			printk(KERN_ERR
708 			       "Failed to initialize the ICMP6 control socket "
709 			       "(err %d).\n",
710 			       err);
711 			goto fail;
712 		}
713 
714 		sk = per_cpu(__icmpv6_socket, i)->sk;
715 		sk->sk_allocation = GFP_ATOMIC;
716 
717 		/* Enough space for 2 64K ICMP packets, including
718 		 * sk_buff struct overhead.
719 		 */
720 		sk->sk_sndbuf =
721 			(2 * ((64 * 1024) + sizeof(struct sk_buff)));
722 
723 		sk->sk_prot->unhash(sk);
724 	}
725 
726 
727 	if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0) {
728 		printk(KERN_ERR "Failed to register ICMP6 protocol\n");
729 		err = -EAGAIN;
730 		goto fail;
731 	}
732 
733 	return 0;
734 
735  fail:
736 	for (j = 0; j < i; j++) {
737 		if (!cpu_possible(j))
738 			continue;
739 		sock_release(per_cpu(__icmpv6_socket, j));
740 	}
741 
742 	return err;
743 }
744 
745 void icmpv6_cleanup(void)
746 {
747 	int i;
748 
749 	for (i = 0; i < NR_CPUS; i++) {
750 		if (!cpu_possible(i))
751 			continue;
752 		sock_release(per_cpu(__icmpv6_socket, i));
753 	}
754 	inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
755 }
756 
757 static struct icmp6_err {
758 	int err;
759 	int fatal;
760 } tab_unreach[] = {
761 	{	/* NOROUTE */
762 		.err	= ENETUNREACH,
763 		.fatal	= 0,
764 	},
765 	{	/* ADM_PROHIBITED */
766 		.err	= EACCES,
767 		.fatal	= 1,
768 	},
769 	{	/* Was NOT_NEIGHBOUR, now reserved */
770 		.err	= EHOSTUNREACH,
771 		.fatal	= 0,
772 	},
773 	{	/* ADDR_UNREACH	*/
774 		.err	= EHOSTUNREACH,
775 		.fatal	= 0,
776 	},
777 	{	/* PORT_UNREACH	*/
778 		.err	= ECONNREFUSED,
779 		.fatal	= 1,
780 	},
781 };
782 
783 int icmpv6_err_convert(int type, int code, int *err)
784 {
785 	int fatal = 0;
786 
787 	*err = EPROTO;
788 
789 	switch (type) {
790 	case ICMPV6_DEST_UNREACH:
791 		fatal = 1;
792 		if (code <= ICMPV6_PORT_UNREACH) {
793 			*err  = tab_unreach[code].err;
794 			fatal = tab_unreach[code].fatal;
795 		}
796 		break;
797 
798 	case ICMPV6_PKT_TOOBIG:
799 		*err = EMSGSIZE;
800 		break;
801 
802 	case ICMPV6_PARAMPROB:
803 		*err = EPROTO;
804 		fatal = 1;
805 		break;
806 
807 	case ICMPV6_TIME_EXCEED:
808 		*err = EHOSTUNREACH;
809 		break;
810 	};
811 
812 	return fatal;
813 }
814 
815 #ifdef CONFIG_SYSCTL
816 ctl_table ipv6_icmp_table[] = {
817 	{
818 		.ctl_name	= NET_IPV6_ICMP_RATELIMIT,
819 		.procname	= "ratelimit",
820 		.data		= &sysctl_icmpv6_time,
821 		.maxlen		= sizeof(int),
822 		.mode		= 0644,
823 		.proc_handler	= &proc_dointvec
824 	},
825 	{ .ctl_name = 0 },
826 };
827 #endif
828 
829