xref: /linux/net/ipv6/reassembly.c (revision f9c41a62bba3f3f7ef3541b2a025e3371bcbba97)
1 /*
2  *	IPv6 fragment reassembly
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	Based on: net/ipv4/ip_fragment.c
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 
16 /*
17  *	Fixes:
18  *	Andi Kleen	Make it work with multiple hosts.
19  *			More RFC compliance.
20  *
21  *      Horst von Brand Add missing #include <linux/string.h>
22  *	Alexey Kuznetsov	SMP races, threading, cleanup.
23  *	Patrick McHardy		LRU queue of frag heads for evictor.
24  *	Mitsuru KANDA @USAGI	Register inet6_protocol{}.
25  *	David Stevens and
26  *	YOSHIFUJI,H. @USAGI	Always remove fragment header to
27  *				calculate ICV correctly.
28  */
29 
30 #define pr_fmt(fmt) "IPv6: " fmt
31 
32 #include <linux/errno.h>
33 #include <linux/types.h>
34 #include <linux/string.h>
35 #include <linux/socket.h>
36 #include <linux/sockios.h>
37 #include <linux/jiffies.h>
38 #include <linux/net.h>
39 #include <linux/list.h>
40 #include <linux/netdevice.h>
41 #include <linux/in6.h>
42 #include <linux/ipv6.h>
43 #include <linux/icmpv6.h>
44 #include <linux/random.h>
45 #include <linux/jhash.h>
46 #include <linux/skbuff.h>
47 #include <linux/slab.h>
48 #include <linux/export.h>
49 
50 #include <net/sock.h>
51 #include <net/snmp.h>
52 
53 #include <net/ipv6.h>
54 #include <net/ip6_route.h>
55 #include <net/protocol.h>
56 #include <net/transp_v6.h>
57 #include <net/rawv6.h>
58 #include <net/ndisc.h>
59 #include <net/addrconf.h>
60 #include <net/inet_frag.h>
61 
62 struct ip6frag_skb_cb
63 {
64 	struct inet6_skb_parm	h;
65 	int			offset;
66 };
67 
68 #define FRAG6_CB(skb)	((struct ip6frag_skb_cb*)((skb)->cb))
69 
70 
71 static struct inet_frags ip6_frags;
72 
73 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
74 			  struct net_device *dev);
75 
76 /*
77  * callers should be careful not to use the hash value outside the ipfrag_lock
78  * as doing so could race with ipfrag_hash_rnd being recalculated.
79  */
80 unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
81 			     const struct in6_addr *daddr, u32 rnd)
82 {
83 	u32 c;
84 
85 	c = jhash_3words(ipv6_addr_hash(saddr), ipv6_addr_hash(daddr),
86 			 (__force u32)id, rnd);
87 
88 	return c & (INETFRAGS_HASHSZ - 1);
89 }
90 EXPORT_SYMBOL_GPL(inet6_hash_frag);
91 
92 static unsigned int ip6_hashfn(struct inet_frag_queue *q)
93 {
94 	struct frag_queue *fq;
95 
96 	fq = container_of(q, struct frag_queue, q);
97 	return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd);
98 }
99 
100 bool ip6_frag_match(struct inet_frag_queue *q, void *a)
101 {
102 	struct frag_queue *fq;
103 	struct ip6_create_arg *arg = a;
104 
105 	fq = container_of(q, struct frag_queue, q);
106 	return	fq->id == arg->id &&
107 		fq->user == arg->user &&
108 		ipv6_addr_equal(&fq->saddr, arg->src) &&
109 		ipv6_addr_equal(&fq->daddr, arg->dst);
110 }
111 EXPORT_SYMBOL(ip6_frag_match);
112 
113 void ip6_frag_init(struct inet_frag_queue *q, void *a)
114 {
115 	struct frag_queue *fq = container_of(q, struct frag_queue, q);
116 	struct ip6_create_arg *arg = a;
117 
118 	fq->id = arg->id;
119 	fq->user = arg->user;
120 	fq->saddr = *arg->src;
121 	fq->daddr = *arg->dst;
122 }
123 EXPORT_SYMBOL(ip6_frag_init);
124 
125 void ip6_expire_frag_queue(struct net *net, struct frag_queue *fq,
126 			   struct inet_frags *frags)
127 {
128 	struct net_device *dev = NULL;
129 
130 	spin_lock(&fq->q.lock);
131 
132 	if (fq->q.last_in & INET_FRAG_COMPLETE)
133 		goto out;
134 
135 	inet_frag_kill(&fq->q, frags);
136 
137 	rcu_read_lock();
138 	dev = dev_get_by_index_rcu(net, fq->iif);
139 	if (!dev)
140 		goto out_rcu_unlock;
141 
142 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
143 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
144 
145 	/* Don't send error if the first segment did not arrive. */
146 	if (!(fq->q.last_in & INET_FRAG_FIRST_IN) || !fq->q.fragments)
147 		goto out_rcu_unlock;
148 
149 	/*
150 	   But use as source device on which LAST ARRIVED
151 	   segment was received. And do not use fq->dev
152 	   pointer directly, device might already disappeared.
153 	 */
154 	fq->q.fragments->dev = dev;
155 	icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
156 out_rcu_unlock:
157 	rcu_read_unlock();
158 out:
159 	spin_unlock(&fq->q.lock);
160 	inet_frag_put(&fq->q, frags);
161 }
162 EXPORT_SYMBOL(ip6_expire_frag_queue);
163 
164 static void ip6_frag_expire(unsigned long data)
165 {
166 	struct frag_queue *fq;
167 	struct net *net;
168 
169 	fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
170 	net = container_of(fq->q.net, struct net, ipv6.frags);
171 
172 	ip6_expire_frag_queue(net, fq, &ip6_frags);
173 }
174 
175 static __inline__ struct frag_queue *
176 fq_find(struct net *net, __be32 id, const struct in6_addr *src, const struct in6_addr *dst)
177 {
178 	struct inet_frag_queue *q;
179 	struct ip6_create_arg arg;
180 	unsigned int hash;
181 
182 	arg.id = id;
183 	arg.user = IP6_DEFRAG_LOCAL_DELIVER;
184 	arg.src = src;
185 	arg.dst = dst;
186 
187 	read_lock(&ip6_frags.lock);
188 	hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd);
189 
190 	q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
191 	if (IS_ERR_OR_NULL(q)) {
192 		inet_frag_maybe_warn_overflow(q, pr_fmt());
193 		return NULL;
194 	}
195 	return container_of(q, struct frag_queue, q);
196 }
197 
198 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
199 			   struct frag_hdr *fhdr, int nhoff)
200 {
201 	struct sk_buff *prev, *next;
202 	struct net_device *dev;
203 	int offset, end;
204 	struct net *net = dev_net(skb_dst(skb)->dev);
205 
206 	if (fq->q.last_in & INET_FRAG_COMPLETE)
207 		goto err;
208 
209 	offset = ntohs(fhdr->frag_off) & ~0x7;
210 	end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
211 			((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
212 
213 	if ((unsigned int)end > IPV6_MAXPLEN) {
214 		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
215 				 IPSTATS_MIB_INHDRERRORS);
216 		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
217 				  ((u8 *)&fhdr->frag_off -
218 				   skb_network_header(skb)));
219 		return -1;
220 	}
221 
222 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
223 		const unsigned char *nh = skb_network_header(skb);
224 		skb->csum = csum_sub(skb->csum,
225 				     csum_partial(nh, (u8 *)(fhdr + 1) - nh,
226 						  0));
227 	}
228 
229 	/* Is this the final fragment? */
230 	if (!(fhdr->frag_off & htons(IP6_MF))) {
231 		/* If we already have some bits beyond end
232 		 * or have different end, the segment is corrupted.
233 		 */
234 		if (end < fq->q.len ||
235 		    ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len))
236 			goto err;
237 		fq->q.last_in |= INET_FRAG_LAST_IN;
238 		fq->q.len = end;
239 	} else {
240 		/* Check if the fragment is rounded to 8 bytes.
241 		 * Required by the RFC.
242 		 */
243 		if (end & 0x7) {
244 			/* RFC2460 says always send parameter problem in
245 			 * this case. -DaveM
246 			 */
247 			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
248 					 IPSTATS_MIB_INHDRERRORS);
249 			icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
250 					  offsetof(struct ipv6hdr, payload_len));
251 			return -1;
252 		}
253 		if (end > fq->q.len) {
254 			/* Some bits beyond end -> corruption. */
255 			if (fq->q.last_in & INET_FRAG_LAST_IN)
256 				goto err;
257 			fq->q.len = end;
258 		}
259 	}
260 
261 	if (end == offset)
262 		goto err;
263 
264 	/* Point into the IP datagram 'data' part. */
265 	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
266 		goto err;
267 
268 	if (pskb_trim_rcsum(skb, end - offset))
269 		goto err;
270 
271 	/* Find out which fragments are in front and at the back of us
272 	 * in the chain of fragments so far.  We must know where to put
273 	 * this fragment, right?
274 	 */
275 	prev = fq->q.fragments_tail;
276 	if (!prev || FRAG6_CB(prev)->offset < offset) {
277 		next = NULL;
278 		goto found;
279 	}
280 	prev = NULL;
281 	for(next = fq->q.fragments; next != NULL; next = next->next) {
282 		if (FRAG6_CB(next)->offset >= offset)
283 			break;	/* bingo! */
284 		prev = next;
285 	}
286 
287 found:
288 	/* RFC5722, Section 4, amended by Errata ID : 3089
289 	 *                          When reassembling an IPv6 datagram, if
290 	 *   one or more its constituent fragments is determined to be an
291 	 *   overlapping fragment, the entire datagram (and any constituent
292 	 *   fragments) MUST be silently discarded.
293 	 */
294 
295 	/* Check for overlap with preceding fragment. */
296 	if (prev &&
297 	    (FRAG6_CB(prev)->offset + prev->len) > offset)
298 		goto discard_fq;
299 
300 	/* Look for overlap with succeeding segment. */
301 	if (next && FRAG6_CB(next)->offset < end)
302 		goto discard_fq;
303 
304 	FRAG6_CB(skb)->offset = offset;
305 
306 	/* Insert this fragment in the chain of fragments. */
307 	skb->next = next;
308 	if (!next)
309 		fq->q.fragments_tail = skb;
310 	if (prev)
311 		prev->next = skb;
312 	else
313 		fq->q.fragments = skb;
314 
315 	dev = skb->dev;
316 	if (dev) {
317 		fq->iif = dev->ifindex;
318 		skb->dev = NULL;
319 	}
320 	fq->q.stamp = skb->tstamp;
321 	fq->q.meat += skb->len;
322 	add_frag_mem_limit(&fq->q, skb->truesize);
323 
324 	/* The first fragment.
325 	 * nhoffset is obtained from the first fragment, of course.
326 	 */
327 	if (offset == 0) {
328 		fq->nhoffset = nhoff;
329 		fq->q.last_in |= INET_FRAG_FIRST_IN;
330 	}
331 
332 	if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
333 	    fq->q.meat == fq->q.len)
334 		return ip6_frag_reasm(fq, prev, dev);
335 
336 	inet_frag_lru_move(&fq->q);
337 	return -1;
338 
339 discard_fq:
340 	inet_frag_kill(&fq->q, &ip6_frags);
341 err:
342 	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
343 		      IPSTATS_MIB_REASMFAILS);
344 	kfree_skb(skb);
345 	return -1;
346 }
347 
348 /*
349  *	Check if this packet is complete.
350  *	Returns NULL on failure by any reason, and pointer
351  *	to current nexthdr field in reassembled frame.
352  *
353  *	It is called with locked fq, and caller must check that
354  *	queue is eligible for reassembly i.e. it is not COMPLETE,
355  *	the last and the first frames arrived and all the bits are here.
356  */
357 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
358 			  struct net_device *dev)
359 {
360 	struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
361 	struct sk_buff *fp, *head = fq->q.fragments;
362 	int    payload_len;
363 	unsigned int nhoff;
364 	int sum_truesize;
365 
366 	inet_frag_kill(&fq->q, &ip6_frags);
367 
368 	/* Make the one we just received the head. */
369 	if (prev) {
370 		head = prev->next;
371 		fp = skb_clone(head, GFP_ATOMIC);
372 
373 		if (!fp)
374 			goto out_oom;
375 
376 		fp->next = head->next;
377 		if (!fp->next)
378 			fq->q.fragments_tail = fp;
379 		prev->next = fp;
380 
381 		skb_morph(head, fq->q.fragments);
382 		head->next = fq->q.fragments->next;
383 
384 		consume_skb(fq->q.fragments);
385 		fq->q.fragments = head;
386 	}
387 
388 	WARN_ON(head == NULL);
389 	WARN_ON(FRAG6_CB(head)->offset != 0);
390 
391 	/* Unfragmented part is taken from the first segment. */
392 	payload_len = ((head->data - skb_network_header(head)) -
393 		       sizeof(struct ipv6hdr) + fq->q.len -
394 		       sizeof(struct frag_hdr));
395 	if (payload_len > IPV6_MAXPLEN)
396 		goto out_oversize;
397 
398 	/* Head of list must not be cloned. */
399 	if (skb_unclone(head, GFP_ATOMIC))
400 		goto out_oom;
401 
402 	/* If the first fragment is fragmented itself, we split
403 	 * it to two chunks: the first with data and paged part
404 	 * and the second, holding only fragments. */
405 	if (skb_has_frag_list(head)) {
406 		struct sk_buff *clone;
407 		int i, plen = 0;
408 
409 		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
410 			goto out_oom;
411 		clone->next = head->next;
412 		head->next = clone;
413 		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
414 		skb_frag_list_init(head);
415 		for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
416 			plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
417 		clone->len = clone->data_len = head->data_len - plen;
418 		head->data_len -= clone->len;
419 		head->len -= clone->len;
420 		clone->csum = 0;
421 		clone->ip_summed = head->ip_summed;
422 		add_frag_mem_limit(&fq->q, clone->truesize);
423 	}
424 
425 	/* We have to remove fragment header from datagram and to relocate
426 	 * header in order to calculate ICV correctly. */
427 	nhoff = fq->nhoffset;
428 	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
429 	memmove(head->head + sizeof(struct frag_hdr), head->head,
430 		(head->data - head->head) - sizeof(struct frag_hdr));
431 	head->mac_header += sizeof(struct frag_hdr);
432 	head->network_header += sizeof(struct frag_hdr);
433 
434 	skb_reset_transport_header(head);
435 	skb_push(head, head->data - skb_network_header(head));
436 
437 	sum_truesize = head->truesize;
438 	for (fp = head->next; fp;) {
439 		bool headstolen;
440 		int delta;
441 		struct sk_buff *next = fp->next;
442 
443 		sum_truesize += fp->truesize;
444 		if (head->ip_summed != fp->ip_summed)
445 			head->ip_summed = CHECKSUM_NONE;
446 		else if (head->ip_summed == CHECKSUM_COMPLETE)
447 			head->csum = csum_add(head->csum, fp->csum);
448 
449 		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
450 			kfree_skb_partial(fp, headstolen);
451 		} else {
452 			if (!skb_shinfo(head)->frag_list)
453 				skb_shinfo(head)->frag_list = fp;
454 			head->data_len += fp->len;
455 			head->len += fp->len;
456 			head->truesize += fp->truesize;
457 		}
458 		fp = next;
459 	}
460 	sub_frag_mem_limit(&fq->q, sum_truesize);
461 
462 	head->next = NULL;
463 	head->dev = dev;
464 	head->tstamp = fq->q.stamp;
465 	ipv6_hdr(head)->payload_len = htons(payload_len);
466 	IP6CB(head)->nhoff = nhoff;
467 
468 	/* Yes, and fold redundant checksum back. 8) */
469 	if (head->ip_summed == CHECKSUM_COMPLETE)
470 		head->csum = csum_partial(skb_network_header(head),
471 					  skb_network_header_len(head),
472 					  head->csum);
473 
474 	rcu_read_lock();
475 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
476 	rcu_read_unlock();
477 	fq->q.fragments = NULL;
478 	fq->q.fragments_tail = NULL;
479 	return 1;
480 
481 out_oversize:
482 	net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
483 	goto out_fail;
484 out_oom:
485 	net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
486 out_fail:
487 	rcu_read_lock();
488 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
489 	rcu_read_unlock();
490 	return -1;
491 }
492 
493 static int ipv6_frag_rcv(struct sk_buff *skb)
494 {
495 	struct frag_hdr *fhdr;
496 	struct frag_queue *fq;
497 	const struct ipv6hdr *hdr = ipv6_hdr(skb);
498 	struct net *net = dev_net(skb_dst(skb)->dev);
499 	int evicted;
500 
501 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
502 
503 	/* Jumbo payload inhibits frag. header */
504 	if (hdr->payload_len==0)
505 		goto fail_hdr;
506 
507 	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
508 				 sizeof(struct frag_hdr))))
509 		goto fail_hdr;
510 
511 	hdr = ipv6_hdr(skb);
512 	fhdr = (struct frag_hdr *)skb_transport_header(skb);
513 
514 	if (!(fhdr->frag_off & htons(0xFFF9))) {
515 		/* It is not a fragmented frame */
516 		skb->transport_header += sizeof(struct frag_hdr);
517 		IP6_INC_STATS_BH(net,
518 				 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
519 
520 		IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
521 		return 1;
522 	}
523 
524 	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags, false);
525 	if (evicted)
526 		IP6_ADD_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
527 				 IPSTATS_MIB_REASMFAILS, evicted);
528 
529 	fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr);
530 	if (fq != NULL) {
531 		int ret;
532 
533 		spin_lock(&fq->q.lock);
534 
535 		ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
536 
537 		spin_unlock(&fq->q.lock);
538 		inet_frag_put(&fq->q, &ip6_frags);
539 		return ret;
540 	}
541 
542 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
543 	kfree_skb(skb);
544 	return -1;
545 
546 fail_hdr:
547 	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
548 	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
549 	return -1;
550 }
551 
552 static const struct inet6_protocol frag_protocol =
553 {
554 	.handler	=	ipv6_frag_rcv,
555 	.flags		=	INET6_PROTO_NOPOLICY,
556 };
557 
558 #ifdef CONFIG_SYSCTL
559 static struct ctl_table ip6_frags_ns_ctl_table[] = {
560 	{
561 		.procname	= "ip6frag_high_thresh",
562 		.data		= &init_net.ipv6.frags.high_thresh,
563 		.maxlen		= sizeof(int),
564 		.mode		= 0644,
565 		.proc_handler	= proc_dointvec
566 	},
567 	{
568 		.procname	= "ip6frag_low_thresh",
569 		.data		= &init_net.ipv6.frags.low_thresh,
570 		.maxlen		= sizeof(int),
571 		.mode		= 0644,
572 		.proc_handler	= proc_dointvec
573 	},
574 	{
575 		.procname	= "ip6frag_time",
576 		.data		= &init_net.ipv6.frags.timeout,
577 		.maxlen		= sizeof(int),
578 		.mode		= 0644,
579 		.proc_handler	= proc_dointvec_jiffies,
580 	},
581 	{ }
582 };
583 
584 static struct ctl_table ip6_frags_ctl_table[] = {
585 	{
586 		.procname	= "ip6frag_secret_interval",
587 		.data		= &ip6_frags.secret_interval,
588 		.maxlen		= sizeof(int),
589 		.mode		= 0644,
590 		.proc_handler	= proc_dointvec_jiffies,
591 	},
592 	{ }
593 };
594 
595 static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
596 {
597 	struct ctl_table *table;
598 	struct ctl_table_header *hdr;
599 
600 	table = ip6_frags_ns_ctl_table;
601 	if (!net_eq(net, &init_net)) {
602 		table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
603 		if (table == NULL)
604 			goto err_alloc;
605 
606 		table[0].data = &net->ipv6.frags.high_thresh;
607 		table[1].data = &net->ipv6.frags.low_thresh;
608 		table[2].data = &net->ipv6.frags.timeout;
609 
610 		/* Don't export sysctls to unprivileged users */
611 		if (net->user_ns != &init_user_ns)
612 			table[0].procname = NULL;
613 	}
614 
615 	hdr = register_net_sysctl(net, "net/ipv6", table);
616 	if (hdr == NULL)
617 		goto err_reg;
618 
619 	net->ipv6.sysctl.frags_hdr = hdr;
620 	return 0;
621 
622 err_reg:
623 	if (!net_eq(net, &init_net))
624 		kfree(table);
625 err_alloc:
626 	return -ENOMEM;
627 }
628 
629 static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
630 {
631 	struct ctl_table *table;
632 
633 	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
634 	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
635 	if (!net_eq(net, &init_net))
636 		kfree(table);
637 }
638 
639 static struct ctl_table_header *ip6_ctl_header;
640 
641 static int ip6_frags_sysctl_register(void)
642 {
643 	ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6",
644 			ip6_frags_ctl_table);
645 	return ip6_ctl_header == NULL ? -ENOMEM : 0;
646 }
647 
648 static void ip6_frags_sysctl_unregister(void)
649 {
650 	unregister_net_sysctl_table(ip6_ctl_header);
651 }
652 #else
653 static inline int ip6_frags_ns_sysctl_register(struct net *net)
654 {
655 	return 0;
656 }
657 
658 static inline void ip6_frags_ns_sysctl_unregister(struct net *net)
659 {
660 }
661 
662 static inline int ip6_frags_sysctl_register(void)
663 {
664 	return 0;
665 }
666 
667 static inline void ip6_frags_sysctl_unregister(void)
668 {
669 }
670 #endif
671 
672 static int __net_init ipv6_frags_init_net(struct net *net)
673 {
674 	net->ipv6.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
675 	net->ipv6.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
676 	net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;
677 
678 	inet_frags_init_net(&net->ipv6.frags);
679 
680 	return ip6_frags_ns_sysctl_register(net);
681 }
682 
683 static void __net_exit ipv6_frags_exit_net(struct net *net)
684 {
685 	ip6_frags_ns_sysctl_unregister(net);
686 	inet_frags_exit_net(&net->ipv6.frags, &ip6_frags);
687 }
688 
689 static struct pernet_operations ip6_frags_ops = {
690 	.init = ipv6_frags_init_net,
691 	.exit = ipv6_frags_exit_net,
692 };
693 
694 int __init ipv6_frag_init(void)
695 {
696 	int ret;
697 
698 	ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
699 	if (ret)
700 		goto out;
701 
702 	ret = ip6_frags_sysctl_register();
703 	if (ret)
704 		goto err_sysctl;
705 
706 	ret = register_pernet_subsys(&ip6_frags_ops);
707 	if (ret)
708 		goto err_pernet;
709 
710 	ip6_frags.hashfn = ip6_hashfn;
711 	ip6_frags.constructor = ip6_frag_init;
712 	ip6_frags.destructor = NULL;
713 	ip6_frags.skb_free = NULL;
714 	ip6_frags.qsize = sizeof(struct frag_queue);
715 	ip6_frags.match = ip6_frag_match;
716 	ip6_frags.frag_expire = ip6_frag_expire;
717 	ip6_frags.secret_interval = 10 * 60 * HZ;
718 	inet_frags_init(&ip6_frags);
719 out:
720 	return ret;
721 
722 err_pernet:
723 	ip6_frags_sysctl_unregister();
724 err_sysctl:
725 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
726 	goto out;
727 }
728 
729 void ipv6_frag_exit(void)
730 {
731 	inet_frags_fini(&ip6_frags);
732 	ip6_frags_sysctl_unregister();
733 	unregister_pernet_subsys(&ip6_frags_ops);
734 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
735 }
736