ip_fragment.c revision 2bad35b7c9588eb5e65c03bcae54e7eb6b1a6504 
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 *		The IP fragmentation functionality.
7 *
8 * Authors:	Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
9 *		Alan Cox <alan@lxorguk.ukuu.org.uk>
10 *
11 * Fixes:
12 *		Alan Cox	:	Split from ip.c , see ip_input.c for history.
13 *		David S. Miller :	Begin massive cleanup...
14 *		Andi Kleen	:	Add sysctls.
15 *		xxxx		:	Overlapfrag bug.
16 *		Ultima          :       ip_expire() kernel panic.
17 *		Bill Hawes	:	Frag accounting and evictor fixes.
18 *		John McDonald	:	0 length frag bug.
19 *		Alexey Kuznetsov:	SMP races, threading, cleanup.
20 *		Patrick McHardy :	LRU queue of frag heads for evictor.
21 */
22
23#include <linux/compiler.h>
24#include <linux/module.h>
25#include <linux/types.h>
26#include <linux/mm.h>
27#include <linux/jiffies.h>
28#include <linux/skbuff.h>
29#include <linux/list.h>
30#include <linux/ip.h>
31#include <linux/icmp.h>
32#include <linux/netdevice.h>
33#include <linux/jhash.h>
34#include <linux/random.h>
35#include <net/sock.h>
36#include <net/ip.h>
37#include <net/icmp.h>
38#include <net/checksum.h>
39#include <net/inetpeer.h>
40#include <net/inet_frag.h>
41#include <linux/tcp.h>
42#include <linux/udp.h>
43#include <linux/inet.h>
44#include <linux/netfilter_ipv4.h>
45
46/* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
47 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
48 * as well. Or notify me, at least. --ANK
49 */
50
51static int sysctl_ipfrag_max_dist __read_mostly = 64;
52
53struct ipfrag_skb_cb
54{
55	struct inet_skb_parm	h;
56	int			offset;
57};
58
59#define FRAG_CB(skb)	((struct ipfrag_skb_cb *)((skb)->cb))
60
61/* Describe an entry in the "incomplete datagrams" queue. */
62struct ipq {
63	struct inet_frag_queue q;
64
65	u32		user;
66	__be32		saddr;
67	__be32		daddr;
68	__be16		id;
69	u8		protocol;
70	int             iif;
71	unsigned int    rid;
72	struct inet_peer *peer;
73};
74
75static struct inet_frags ip4_frags;
76
77int ip_frag_nqueues(struct net *net)
78{
79	return net->ipv4.frags.nqueues;
80}
81
82int ip_frag_mem(struct net *net)
83{
84	return atomic_read(&net->ipv4.frags.mem);
85}
86
87static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
88			 struct net_device *dev);
89
90struct ip4_create_arg {
91	struct iphdr *iph;
92	u32 user;
93};
94
95static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot)
96{
97	return jhash_3words((__force u32)id << 16 | prot,
98			    (__force u32)saddr, (__force u32)daddr,
99			    ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1);
100}
101
102static unsigned int ip4_hashfn(struct inet_frag_queue *q)
103{
104	struct ipq *ipq;
105
106	ipq = container_of(q, struct ipq, q);
107	return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol);
108}
109
110static int ip4_frag_match(struct inet_frag_queue *q, void *a)
111{
112	struct ipq *qp;
113	struct ip4_create_arg *arg = a;
114
115	qp = container_of(q, struct ipq, q);
116	return (qp->id == arg->iph->id &&
117			qp->saddr == arg->iph->saddr &&
118			qp->daddr == arg->iph->daddr &&
119			qp->protocol == arg->iph->protocol &&
120			qp->user == arg->user);
121}
122
123/* Memory Tracking Functions. */
124static __inline__ void frag_kfree_skb(struct netns_frags *nf,
125		struct sk_buff *skb, int *work)
126{
127	if (work)
128		*work -= skb->truesize;
129	atomic_sub(skb->truesize, &nf->mem);
130	kfree_skb(skb);
131}
132
133static void ip4_frag_init(struct inet_frag_queue *q, void *a)
134{
135	struct ipq *qp = container_of(q, struct ipq, q);
136	struct ip4_create_arg *arg = a;
137
138	qp->protocol = arg->iph->protocol;
139	qp->id = arg->iph->id;
140	qp->saddr = arg->iph->saddr;
141	qp->daddr = arg->iph->daddr;
142	qp->user = arg->user;
143	qp->peer = sysctl_ipfrag_max_dist ?
144		inet_getpeer(arg->iph->saddr, 1) : NULL;
145}
146
147static __inline__ void ip4_frag_free(struct inet_frag_queue *q)
148{
149	struct ipq *qp;
150
151	qp = container_of(q, struct ipq, q);
152	if (qp->peer)
153		inet_putpeer(qp->peer);
154}
155
156
157/* Destruction primitives. */
158
159static __inline__ void ipq_put(struct ipq *ipq)
160{
161	inet_frag_put(&ipq->q, &ip4_frags);
162}
163
164/* Kill ipq entry. It is not destroyed immediately,
165 * because caller (and someone more) holds reference count.
166 */
167static void ipq_kill(struct ipq *ipq)
168{
169	inet_frag_kill(&ipq->q, &ip4_frags);
170}
171
172/* Memory limiting on fragments.  Evictor trashes the oldest
173 * fragment queue until we are back under the threshold.
174 */
175static void ip_evictor(struct net *net)
176{
177	int evicted;
178
179	evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags);
180	if (evicted)
181		IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted);
182}
183
184/*
185 * Oops, a fragment queue timed out.  Kill it and send an ICMP reply.
186 */
187static void ip_expire(unsigned long arg)
188{
189	struct ipq *qp;
190	struct net *net;
191
192	qp = container_of((struct inet_frag_queue *) arg, struct ipq, q);
193	net = container_of(qp->q.net, struct net, ipv4.frags);
194
195	spin_lock(&qp->q.lock);
196
197	if (qp->q.last_in & INET_FRAG_COMPLETE)
198		goto out;
199
200	ipq_kill(qp);
201
202	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT);
203	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
204
205	if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) {
206		struct sk_buff *head = qp->q.fragments;
207
208		/* Send an ICMP "Fragment Reassembly Timeout" message. */
209		if ((head->dev = dev_get_by_index(net, qp->iif)) != NULL) {
210			icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
211			dev_put(head->dev);
212		}
213	}
214out:
215	spin_unlock(&qp->q.lock);
216	ipq_put(qp);
217}
218
219/* Find the correct entry in the "incomplete datagrams" queue for
220 * this IP datagram, and create new one, if nothing is found.
221 */
222static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user)
223{
224	struct inet_frag_queue *q;
225	struct ip4_create_arg arg;
226	unsigned int hash;
227
228	arg.iph = iph;
229	arg.user = user;
230
231	read_lock(&ip4_frags.lock);
232	hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
233
234	q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash);
235	if (q == NULL)
236		goto out_nomem;
237
238	return container_of(q, struct ipq, q);
239
240out_nomem:
241	LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n");
242	return NULL;
243}
244
245/* Is the fragment too far ahead to be part of ipq? */
246static inline int ip_frag_too_far(struct ipq *qp)
247{
248	struct inet_peer *peer = qp->peer;
249	unsigned int max = sysctl_ipfrag_max_dist;
250	unsigned int start, end;
251
252	int rc;
253
254	if (!peer || !max)
255		return 0;
256
257	start = qp->rid;
258	end = atomic_inc_return(&peer->rid);
259	qp->rid = end;
260
261	rc = qp->q.fragments && (end - start) > max;
262
263	if (rc) {
264		struct net *net;
265
266		net = container_of(qp->q.net, struct net, ipv4.frags);
267		IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
268	}
269
270	return rc;
271}
272
273static int ip_frag_reinit(struct ipq *qp)
274{
275	struct sk_buff *fp;
276
277	if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
278		atomic_inc(&qp->q.refcnt);
279		return -ETIMEDOUT;
280	}
281
282	fp = qp->q.fragments;
283	do {
284		struct sk_buff *xp = fp->next;
285		frag_kfree_skb(qp->q.net, fp, NULL);
286		fp = xp;
287	} while (fp);
288
289	qp->q.last_in = 0;
290	qp->q.len = 0;
291	qp->q.meat = 0;
292	qp->q.fragments = NULL;
293	qp->iif = 0;
294
295	return 0;
296}
297
298/* Add new segment to existing queue. */
299static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
300{
301	struct sk_buff *prev, *next;
302	struct net_device *dev;
303	int flags, offset;
304	int ihl, end;
305	int err = -ENOENT;
306
307	if (qp->q.last_in & INET_FRAG_COMPLETE)
308		goto err;
309
310	if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
311	    unlikely(ip_frag_too_far(qp)) &&
312	    unlikely(err = ip_frag_reinit(qp))) {
313		ipq_kill(qp);
314		goto err;
315	}
316
317	offset = ntohs(ip_hdr(skb)->frag_off);
318	flags = offset & ~IP_OFFSET;
319	offset &= IP_OFFSET;
320	offset <<= 3;		/* offset is in 8-byte chunks */
321	ihl = ip_hdrlen(skb);
322
323	/* Determine the position of this fragment. */
324	end = offset + skb->len - ihl;
325	err = -EINVAL;
326
327	/* Is this the final fragment? */
328	if ((flags & IP_MF) == 0) {
329		/* If we already have some bits beyond end
330		 * or have different end, the segment is corrrupted.
331		 */
332		if (end < qp->q.len ||
333		    ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len))
334			goto err;
335		qp->q.last_in |= INET_FRAG_LAST_IN;
336		qp->q.len = end;
337	} else {
338		if (end&7) {
339			end &= ~7;
340			if (skb->ip_summed != CHECKSUM_UNNECESSARY)
341				skb->ip_summed = CHECKSUM_NONE;
342		}
343		if (end > qp->q.len) {
344			/* Some bits beyond end -> corruption. */
345			if (qp->q.last_in & INET_FRAG_LAST_IN)
346				goto err;
347			qp->q.len = end;
348		}
349	}
350	if (end == offset)
351		goto err;
352
353	err = -ENOMEM;
354	if (pskb_pull(skb, ihl) == NULL)
355		goto err;
356
357	err = pskb_trim_rcsum(skb, end - offset);
358	if (err)
359		goto err;
360
361	/* Find out which fragments are in front and at the back of us
362	 * in the chain of fragments so far.  We must know where to put
363	 * this fragment, right?
364	 */
365	prev = NULL;
366	for (next = qp->q.fragments; next != NULL; next = next->next) {
367		if (FRAG_CB(next)->offset >= offset)
368			break;	/* bingo! */
369		prev = next;
370	}
371
372	/* We found where to put this one.  Check for overlap with
373	 * preceding fragment, and, if needed, align things so that
374	 * any overlaps are eliminated.
375	 */
376	if (prev) {
377		int i = (FRAG_CB(prev)->offset + prev->len) - offset;
378
379		if (i > 0) {
380			offset += i;
381			err = -EINVAL;
382			if (end <= offset)
383				goto err;
384			err = -ENOMEM;
385			if (!pskb_pull(skb, i))
386				goto err;
387			if (skb->ip_summed != CHECKSUM_UNNECESSARY)
388				skb->ip_summed = CHECKSUM_NONE;
389		}
390	}
391
392	err = -ENOMEM;
393
394	while (next && FRAG_CB(next)->offset < end) {
395		int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */
396
397		if (i < next->len) {
398			/* Eat head of the next overlapped fragment
399			 * and leave the loop. The next ones cannot overlap.
400			 */
401			if (!pskb_pull(next, i))
402				goto err;
403			FRAG_CB(next)->offset += i;
404			qp->q.meat -= i;
405			if (next->ip_summed != CHECKSUM_UNNECESSARY)
406				next->ip_summed = CHECKSUM_NONE;
407			break;
408		} else {
409			struct sk_buff *free_it = next;
410
411			/* Old fragment is completely overridden with
412			 * new one drop it.
413			 */
414			next = next->next;
415
416			if (prev)
417				prev->next = next;
418			else
419				qp->q.fragments = next;
420
421			qp->q.meat -= free_it->len;
422			frag_kfree_skb(qp->q.net, free_it, NULL);
423		}
424	}
425
426	FRAG_CB(skb)->offset = offset;
427
428	/* Insert this fragment in the chain of fragments. */
429	skb->next = next;
430	if (prev)
431		prev->next = skb;
432	else
433		qp->q.fragments = skb;
434
435	dev = skb->dev;
436	if (dev) {
437		qp->iif = dev->ifindex;
438		skb->dev = NULL;
439	}
440	qp->q.stamp = skb->tstamp;
441	qp->q.meat += skb->len;
442	atomic_add(skb->truesize, &qp->q.net->mem);
443	if (offset == 0)
444		qp->q.last_in |= INET_FRAG_FIRST_IN;
445
446	if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
447	    qp->q.meat == qp->q.len)
448		return ip_frag_reasm(qp, prev, dev);
449
450	write_lock(&ip4_frags.lock);
451	list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list);
452	write_unlock(&ip4_frags.lock);
453	return -EINPROGRESS;
454
455err:
456	kfree_skb(skb);
457	return err;
458}
459
460
461/* Build a new IP datagram from all its fragments. */
462
463static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
464			 struct net_device *dev)
465{
466	struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
467	struct iphdr *iph;
468	struct sk_buff *fp, *head = qp->q.fragments;
469	int len;
470	int ihlen;
471	int err;
472
473	ipq_kill(qp);
474
475	/* Make the one we just received the head. */
476	if (prev) {
477		head = prev->next;
478		fp = skb_clone(head, GFP_ATOMIC);
479		if (!fp)
480			goto out_nomem;
481
482		fp->next = head->next;
483		prev->next = fp;
484
485		skb_morph(head, qp->q.fragments);
486		head->next = qp->q.fragments->next;
487
488		kfree_skb(qp->q.fragments);
489		qp->q.fragments = head;
490	}
491
492	WARN_ON(head == NULL);
493	WARN_ON(FRAG_CB(head)->offset != 0);
494
495	/* Allocate a new buffer for the datagram. */
496	ihlen = ip_hdrlen(head);
497	len = ihlen + qp->q.len;
498
499	err = -E2BIG;
500	if (len > 65535)
501		goto out_oversize;
502
503	/* Head of list must not be cloned. */
504	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
505		goto out_nomem;
506
507	/* If the first fragment is fragmented itself, we split
508	 * it to two chunks: the first with data and paged part
509	 * and the second, holding only fragments. */
510	if (skb_shinfo(head)->frag_list) {
511		struct sk_buff *clone;
512		int i, plen = 0;
513
514		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
515			goto out_nomem;
516		clone->next = head->next;
517		head->next = clone;
518		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
519		skb_shinfo(head)->frag_list = NULL;
520		for (i=0; i<skb_shinfo(head)->nr_frags; i++)
521			plen += skb_shinfo(head)->frags[i].size;
522		clone->len = clone->data_len = head->data_len - plen;
523		head->data_len -= clone->len;
524		head->len -= clone->len;
525		clone->csum = 0;
526		clone->ip_summed = head->ip_summed;
527		atomic_add(clone->truesize, &qp->q.net->mem);
528	}
529
530	skb_shinfo(head)->frag_list = head->next;
531	skb_push(head, head->data - skb_network_header(head));
532	atomic_sub(head->truesize, &qp->q.net->mem);
533
534	for (fp=head->next; fp; fp = fp->next) {
535		head->data_len += fp->len;
536		head->len += fp->len;
537		if (head->ip_summed != fp->ip_summed)
538			head->ip_summed = CHECKSUM_NONE;
539		else if (head->ip_summed == CHECKSUM_COMPLETE)
540			head->csum = csum_add(head->csum, fp->csum);
541		head->truesize += fp->truesize;
542		atomic_sub(fp->truesize, &qp->q.net->mem);
543	}
544
545	head->next = NULL;
546	head->dev = dev;
547	head->tstamp = qp->q.stamp;
548
549	iph = ip_hdr(head);
550	iph->frag_off = 0;
551	iph->tot_len = htons(len);
552	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
553	qp->q.fragments = NULL;
554	return 0;
555
556out_nomem:
557	LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing "
558			      "queue %p\n", qp);
559	err = -ENOMEM;
560	goto out_fail;
561out_oversize:
562	if (net_ratelimit())
563		printk(KERN_INFO "Oversized IP packet from %pI4.\n",
564			&qp->saddr);
565out_fail:
566	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_REASMFAILS);
567	return err;
568}
569
570/* Process an incoming IP datagram fragment. */
571int ip_defrag(struct sk_buff *skb, u32 user)
572{
573	struct ipq *qp;
574	struct net *net;
575
576	net = skb->dev ? dev_net(skb->dev) : dev_net(skb->dst->dev);
577	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS);
578
579	/* Start by cleaning up the memory. */
580	if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh)
581		ip_evictor(net);
582
583	/* Lookup (or create) queue header */
584	if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) {
585		int ret;
586
587		spin_lock(&qp->q.lock);
588
589		ret = ip_frag_queue(qp, skb);
590
591		spin_unlock(&qp->q.lock);
592		ipq_put(qp);
593		return ret;
594	}
595
596	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
597	kfree_skb(skb);
598	return -ENOMEM;
599}
600
601#ifdef CONFIG_SYSCTL
602static int zero;
603
604static struct ctl_table ip4_frags_ns_ctl_table[] = {
605	{
606		.ctl_name	= NET_IPV4_IPFRAG_HIGH_THRESH,
607		.procname	= "ipfrag_high_thresh",
608		.data		= &init_net.ipv4.frags.high_thresh,
609		.maxlen		= sizeof(int),
610		.mode		= 0644,
611		.proc_handler	= proc_dointvec
612	},
613	{
614		.ctl_name	= NET_IPV4_IPFRAG_LOW_THRESH,
615		.procname	= "ipfrag_low_thresh",
616		.data		= &init_net.ipv4.frags.low_thresh,
617		.maxlen		= sizeof(int),
618		.mode		= 0644,
619		.proc_handler	= proc_dointvec
620	},
621	{
622		.ctl_name	= NET_IPV4_IPFRAG_TIME,
623		.procname	= "ipfrag_time",
624		.data		= &init_net.ipv4.frags.timeout,
625		.maxlen		= sizeof(int),
626		.mode		= 0644,
627		.proc_handler	= proc_dointvec_jiffies,
628		.strategy	= sysctl_jiffies
629	},
630	{ }
631};
632
633static struct ctl_table ip4_frags_ctl_table[] = {
634	{
635		.ctl_name	= NET_IPV4_IPFRAG_SECRET_INTERVAL,
636		.procname	= "ipfrag_secret_interval",
637		.data		= &ip4_frags.secret_interval,
638		.maxlen		= sizeof(int),
639		.mode		= 0644,
640		.proc_handler	= proc_dointvec_jiffies,
641		.strategy	= sysctl_jiffies
642	},
643	{
644		.procname	= "ipfrag_max_dist",
645		.data		= &sysctl_ipfrag_max_dist,
646		.maxlen		= sizeof(int),
647		.mode		= 0644,
648		.proc_handler	= proc_dointvec_minmax,
649		.extra1		= &zero
650	},
651	{ }
652};
653
654static int ip4_frags_ns_ctl_register(struct net *net)
655{
656	struct ctl_table *table;
657	struct ctl_table_header *hdr;
658
659	table = ip4_frags_ns_ctl_table;
660	if (net != &init_net) {
661		table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
662		if (table == NULL)
663			goto err_alloc;
664
665		table[0].data = &net->ipv4.frags.high_thresh;
666		table[1].data = &net->ipv4.frags.low_thresh;
667		table[2].data = &net->ipv4.frags.timeout;
668	}
669
670	hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, table);
671	if (hdr == NULL)
672		goto err_reg;
673
674	net->ipv4.frags_hdr = hdr;
675	return 0;
676
677err_reg:
678	if (net != &init_net)
679		kfree(table);
680err_alloc:
681	return -ENOMEM;
682}
683
684static void ip4_frags_ns_ctl_unregister(struct net *net)
685{
686	struct ctl_table *table;
687
688	table = net->ipv4.frags_hdr->ctl_table_arg;
689	unregister_net_sysctl_table(net->ipv4.frags_hdr);
690	kfree(table);
691}
692
693static void ip4_frags_ctl_register(void)
694{
695	register_net_sysctl_rotable(net_ipv4_ctl_path, ip4_frags_ctl_table);
696}
697#else
698static inline int ip4_frags_ns_ctl_register(struct net *net)
699{
700	return 0;
701}
702
703static inline void ip4_frags_ns_ctl_unregister(struct net *net)
704{
705}
706
707static inline void ip4_frags_ctl_register(void)
708{
709}
710#endif
711
712static int ipv4_frags_init_net(struct net *net)
713{
714	/*
715	 * Fragment cache limits. We will commit 256K at one time. Should we
716	 * cross that limit we will prune down to 192K. This should cope with
717	 * even the most extreme cases without allowing an attacker to
718	 * measurably harm machine performance.
719	 */
720	net->ipv4.frags.high_thresh = 256 * 1024;
721	net->ipv4.frags.low_thresh = 192 * 1024;
722	/*
723	 * Important NOTE! Fragment queue must be destroyed before MSL expires.
724	 * RFC791 is wrong proposing to prolongate timer each fragment arrival
725	 * by TTL.
726	 */
727	net->ipv4.frags.timeout = IP_FRAG_TIME;
728
729	inet_frags_init_net(&net->ipv4.frags);
730
731	return ip4_frags_ns_ctl_register(net);
732}
733
734static void ipv4_frags_exit_net(struct net *net)
735{
736	ip4_frags_ns_ctl_unregister(net);
737	inet_frags_exit_net(&net->ipv4.frags, &ip4_frags);
738}
739
740static struct pernet_operations ip4_frags_ops = {
741	.init = ipv4_frags_init_net,
742	.exit = ipv4_frags_exit_net,
743};
744
745void __init ipfrag_init(void)
746{
747	ip4_frags_ctl_register();
748	register_pernet_subsys(&ip4_frags_ops);
749	ip4_frags.hashfn = ip4_hashfn;
750	ip4_frags.constructor = ip4_frag_init;
751	ip4_frags.destructor = ip4_frag_free;
752	ip4_frags.skb_free = NULL;
753	ip4_frags.qsize = sizeof(struct ipq);
754	ip4_frags.match = ip4_frag_match;
755	ip4_frags.frag_expire = ip_expire;
756	ip4_frags.secret_interval = 10 * 60 * HZ;
757	inet_frags_init(&ip4_frags);
758}
759
760EXPORT_SYMBOL(ip_defrag);
761