xref: /linux/net/ipv6/reassembly.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15)
1 /*
2  *	IPv6 fragment reassembly
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	$Id: reassembly.c,v 1.26 2001/03/07 22:00:57 davem Exp $
9  *
10  *	Based on: net/ipv4/ip_fragment.c
11  *
12  *	This program is free software; you can redistribute it and/or
13  *      modify it under the terms of the GNU General Public License
14  *      as published by the Free Software Foundation; either version
15  *      2 of the License, or (at your option) any later version.
16  */
17 
18 /*
19  *	Fixes:
20  *	Andi Kleen	Make it work with multiple hosts.
21  *			More RFC compliance.
22  *
23  *      Horst von Brand Add missing #include <linux/string.h>
24  *	Alexey Kuznetsov	SMP races, threading, cleanup.
25  *	Patrick McHardy		LRU queue of frag heads for evictor.
26  *	Mitsuru KANDA @USAGI	Register inet6_protocol{}.
27  *	David Stevens and
28  *	YOSHIFUJI,H. @USAGI	Always remove fragment header to
29  *				calculate ICV correctly.
30  */
31 #include <linux/config.h>
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 
47 #include <net/sock.h>
48 #include <net/snmp.h>
49 
50 #include <net/ipv6.h>
51 #include <net/protocol.h>
52 #include <net/transp_v6.h>
53 #include <net/rawv6.h>
54 #include <net/ndisc.h>
55 #include <net/addrconf.h>
56 
57 int sysctl_ip6frag_high_thresh = 256*1024;
58 int sysctl_ip6frag_low_thresh = 192*1024;
59 
60 int sysctl_ip6frag_time = IPV6_FRAG_TIMEOUT;
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 /*
72  *	Equivalent of ipv4 struct ipq
73  */
74 
75 struct frag_queue
76 {
77 	struct hlist_node	list;
78 	struct list_head lru_list;		/* lru list member	*/
79 
80 	__u32			id;		/* fragment id		*/
81 	struct in6_addr		saddr;
82 	struct in6_addr		daddr;
83 
84 	spinlock_t		lock;
85 	atomic_t		refcnt;
86 	struct timer_list	timer;		/* expire timer		*/
87 	struct sk_buff		*fragments;
88 	int			len;
89 	int			meat;
90 	int			iif;
91 	struct timeval		stamp;
92 	unsigned int		csum;
93 	__u8			last_in;	/* has first/last segment arrived? */
94 #define COMPLETE		4
95 #define FIRST_IN		2
96 #define LAST_IN			1
97 	__u16			nhoffset;
98 };
99 
100 /* Hash table. */
101 
102 #define IP6Q_HASHSZ	64
103 
104 static struct hlist_head ip6_frag_hash[IP6Q_HASHSZ];
105 static DEFINE_RWLOCK(ip6_frag_lock);
106 static u32 ip6_frag_hash_rnd;
107 static LIST_HEAD(ip6_frag_lru_list);
108 int ip6_frag_nqueues = 0;
109 
110 static __inline__ void __fq_unlink(struct frag_queue *fq)
111 {
112 	hlist_del(&fq->list);
113 	list_del(&fq->lru_list);
114 	ip6_frag_nqueues--;
115 }
116 
117 static __inline__ void fq_unlink(struct frag_queue *fq)
118 {
119 	write_lock(&ip6_frag_lock);
120 	__fq_unlink(fq);
121 	write_unlock(&ip6_frag_lock);
122 }
123 
124 /*
125  * callers should be careful not to use the hash value outside the ipfrag_lock
126  * as doing so could race with ipfrag_hash_rnd being recalculated.
127  */
128 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
129 			       struct in6_addr *daddr)
130 {
131 	u32 a, b, c;
132 
133 	a = saddr->s6_addr32[0];
134 	b = saddr->s6_addr32[1];
135 	c = saddr->s6_addr32[2];
136 
137 	a += JHASH_GOLDEN_RATIO;
138 	b += JHASH_GOLDEN_RATIO;
139 	c += ip6_frag_hash_rnd;
140 	__jhash_mix(a, b, c);
141 
142 	a += saddr->s6_addr32[3];
143 	b += daddr->s6_addr32[0];
144 	c += daddr->s6_addr32[1];
145 	__jhash_mix(a, b, c);
146 
147 	a += daddr->s6_addr32[2];
148 	b += daddr->s6_addr32[3];
149 	c += id;
150 	__jhash_mix(a, b, c);
151 
152 	return c & (IP6Q_HASHSZ - 1);
153 }
154 
155 static struct timer_list ip6_frag_secret_timer;
156 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
157 
158 static void ip6_frag_secret_rebuild(unsigned long dummy)
159 {
160 	unsigned long now = jiffies;
161 	int i;
162 
163 	write_lock(&ip6_frag_lock);
164 	get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
165 	for (i = 0; i < IP6Q_HASHSZ; i++) {
166 		struct frag_queue *q;
167 		struct hlist_node *p, *n;
168 
169 		hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
170 			unsigned int hval = ip6qhashfn(q->id,
171 						       &q->saddr,
172 						       &q->daddr);
173 
174 			if (hval != i) {
175 				hlist_del(&q->list);
176 
177 				/* Relink to new hash chain. */
178 				hlist_add_head(&q->list,
179 					       &ip6_frag_hash[hval]);
180 
181 			}
182 		}
183 	}
184 	write_unlock(&ip6_frag_lock);
185 
186 	mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
187 }
188 
189 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
190 
191 /* Memory Tracking Functions. */
192 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
193 {
194 	if (work)
195 		*work -= skb->truesize;
196 	atomic_sub(skb->truesize, &ip6_frag_mem);
197 	kfree_skb(skb);
198 }
199 
200 static inline void frag_free_queue(struct frag_queue *fq, int *work)
201 {
202 	if (work)
203 		*work -= sizeof(struct frag_queue);
204 	atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
205 	kfree(fq);
206 }
207 
208 static inline struct frag_queue *frag_alloc_queue(void)
209 {
210 	struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
211 
212 	if(!fq)
213 		return NULL;
214 	atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
215 	return fq;
216 }
217 
218 /* Destruction primitives. */
219 
220 /* Complete destruction of fq. */
221 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
222 {
223 	struct sk_buff *fp;
224 
225 	BUG_TRAP(fq->last_in&COMPLETE);
226 	BUG_TRAP(del_timer(&fq->timer) == 0);
227 
228 	/* Release all fragment data. */
229 	fp = fq->fragments;
230 	while (fp) {
231 		struct sk_buff *xp = fp->next;
232 
233 		frag_kfree_skb(fp, work);
234 		fp = xp;
235 	}
236 
237 	frag_free_queue(fq, work);
238 }
239 
240 static __inline__ void fq_put(struct frag_queue *fq, int *work)
241 {
242 	if (atomic_dec_and_test(&fq->refcnt))
243 		ip6_frag_destroy(fq, work);
244 }
245 
246 /* Kill fq entry. It is not destroyed immediately,
247  * because caller (and someone more) holds reference count.
248  */
249 static __inline__ void fq_kill(struct frag_queue *fq)
250 {
251 	if (del_timer(&fq->timer))
252 		atomic_dec(&fq->refcnt);
253 
254 	if (!(fq->last_in & COMPLETE)) {
255 		fq_unlink(fq);
256 		atomic_dec(&fq->refcnt);
257 		fq->last_in |= COMPLETE;
258 	}
259 }
260 
261 static void ip6_evictor(void)
262 {
263 	struct frag_queue *fq;
264 	struct list_head *tmp;
265 	int work;
266 
267 	work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
268 	if (work <= 0)
269 		return;
270 
271 	while(work > 0) {
272 		read_lock(&ip6_frag_lock);
273 		if (list_empty(&ip6_frag_lru_list)) {
274 			read_unlock(&ip6_frag_lock);
275 			return;
276 		}
277 		tmp = ip6_frag_lru_list.next;
278 		fq = list_entry(tmp, struct frag_queue, lru_list);
279 		atomic_inc(&fq->refcnt);
280 		read_unlock(&ip6_frag_lock);
281 
282 		spin_lock(&fq->lock);
283 		if (!(fq->last_in&COMPLETE))
284 			fq_kill(fq);
285 		spin_unlock(&fq->lock);
286 
287 		fq_put(fq, &work);
288 		IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
289 	}
290 }
291 
292 static void ip6_frag_expire(unsigned long data)
293 {
294 	struct frag_queue *fq = (struct frag_queue *) data;
295 	struct net_device *dev;
296 
297 	spin_lock(&fq->lock);
298 
299 	if (fq->last_in & COMPLETE)
300 		goto out;
301 
302 	fq_kill(fq);
303 
304 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
305 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
306 
307 	/* Don't send error if the first segment did not arrive. */
308 	if (!(fq->last_in&FIRST_IN) || !fq->fragments)
309 		goto out;
310 
311 	dev = dev_get_by_index(fq->iif);
312 	if (!dev)
313 		goto out;
314 
315 	/*
316 	   But use as source device on which LAST ARRIVED
317 	   segment was received. And do not use fq->dev
318 	   pointer directly, device might already disappeared.
319 	 */
320 	fq->fragments->dev = dev;
321 	icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
322 	dev_put(dev);
323 out:
324 	spin_unlock(&fq->lock);
325 	fq_put(fq, NULL);
326 }
327 
328 /* Creation primitives. */
329 
330 
331 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
332 {
333 	struct frag_queue *fq;
334 	unsigned int hash;
335 #ifdef CONFIG_SMP
336 	struct hlist_node *n;
337 #endif
338 
339 	write_lock(&ip6_frag_lock);
340 	hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
341 #ifdef CONFIG_SMP
342 	hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
343 		if (fq->id == fq_in->id &&
344 		    ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
345 		    ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
346 			atomic_inc(&fq->refcnt);
347 			write_unlock(&ip6_frag_lock);
348 			fq_in->last_in |= COMPLETE;
349 			fq_put(fq_in, NULL);
350 			return fq;
351 		}
352 	}
353 #endif
354 	fq = fq_in;
355 
356 	if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
357 		atomic_inc(&fq->refcnt);
358 
359 	atomic_inc(&fq->refcnt);
360 	hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
361 	INIT_LIST_HEAD(&fq->lru_list);
362 	list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
363 	ip6_frag_nqueues++;
364 	write_unlock(&ip6_frag_lock);
365 	return fq;
366 }
367 
368 
369 static struct frag_queue *
370 ip6_frag_create(u32 id, struct in6_addr *src, struct in6_addr *dst)
371 {
372 	struct frag_queue *fq;
373 
374 	if ((fq = frag_alloc_queue()) == NULL)
375 		goto oom;
376 
377 	fq->id = id;
378 	ipv6_addr_copy(&fq->saddr, src);
379 	ipv6_addr_copy(&fq->daddr, dst);
380 
381 	init_timer(&fq->timer);
382 	fq->timer.function = ip6_frag_expire;
383 	fq->timer.data = (long) fq;
384 	spin_lock_init(&fq->lock);
385 	atomic_set(&fq->refcnt, 1);
386 
387 	return ip6_frag_intern(fq);
388 
389 oom:
390 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
391 	return NULL;
392 }
393 
394 static __inline__ struct frag_queue *
395 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
396 {
397 	struct frag_queue *fq;
398 	struct hlist_node *n;
399 	unsigned int hash;
400 
401 	read_lock(&ip6_frag_lock);
402 	hash = ip6qhashfn(id, src, dst);
403 	hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
404 		if (fq->id == id &&
405 		    ipv6_addr_equal(src, &fq->saddr) &&
406 		    ipv6_addr_equal(dst, &fq->daddr)) {
407 			atomic_inc(&fq->refcnt);
408 			read_unlock(&ip6_frag_lock);
409 			return fq;
410 		}
411 	}
412 	read_unlock(&ip6_frag_lock);
413 
414 	return ip6_frag_create(id, src, dst);
415 }
416 
417 
418 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
419 			   struct frag_hdr *fhdr, int nhoff)
420 {
421 	struct sk_buff *prev, *next;
422 	int offset, end;
423 
424 	if (fq->last_in & COMPLETE)
425 		goto err;
426 
427 	offset = ntohs(fhdr->frag_off) & ~0x7;
428 	end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
429 			((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
430 
431 	if ((unsigned int)end > IPV6_MAXPLEN) {
432 		IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
433  		icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
434  		return;
435 	}
436 
437  	if (skb->ip_summed == CHECKSUM_HW)
438  		skb->csum = csum_sub(skb->csum,
439  				     csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
440 
441 	/* Is this the final fragment? */
442 	if (!(fhdr->frag_off & htons(IP6_MF))) {
443 		/* If we already have some bits beyond end
444 		 * or have different end, the segment is corrupted.
445 		 */
446 		if (end < fq->len ||
447 		    ((fq->last_in & LAST_IN) && end != fq->len))
448 			goto err;
449 		fq->last_in |= LAST_IN;
450 		fq->len = end;
451 	} else {
452 		/* Check if the fragment is rounded to 8 bytes.
453 		 * Required by the RFC.
454 		 */
455 		if (end & 0x7) {
456 			/* RFC2460 says always send parameter problem in
457 			 * this case. -DaveM
458 			 */
459 			IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
460 			icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
461 					  offsetof(struct ipv6hdr, payload_len));
462 			return;
463 		}
464 		if (end > fq->len) {
465 			/* Some bits beyond end -> corruption. */
466 			if (fq->last_in & LAST_IN)
467 				goto err;
468 			fq->len = end;
469 		}
470 	}
471 
472 	if (end == offset)
473 		goto err;
474 
475 	/* Point into the IP datagram 'data' part. */
476 	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
477 		goto err;
478 
479 	if (pskb_trim_rcsum(skb, end - offset))
480 		goto err;
481 
482 	/* Find out which fragments are in front and at the back of us
483 	 * in the chain of fragments so far.  We must know where to put
484 	 * this fragment, right?
485 	 */
486 	prev = NULL;
487 	for(next = fq->fragments; next != NULL; next = next->next) {
488 		if (FRAG6_CB(next)->offset >= offset)
489 			break;	/* bingo! */
490 		prev = next;
491 	}
492 
493 	/* We found where to put this one.  Check for overlap with
494 	 * preceding fragment, and, if needed, align things so that
495 	 * any overlaps are eliminated.
496 	 */
497 	if (prev) {
498 		int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
499 
500 		if (i > 0) {
501 			offset += i;
502 			if (end <= offset)
503 				goto err;
504 			if (!pskb_pull(skb, i))
505 				goto err;
506 			if (skb->ip_summed != CHECKSUM_UNNECESSARY)
507 				skb->ip_summed = CHECKSUM_NONE;
508 		}
509 	}
510 
511 	/* Look for overlap with succeeding segments.
512 	 * If we can merge fragments, do it.
513 	 */
514 	while (next && FRAG6_CB(next)->offset < end) {
515 		int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
516 
517 		if (i < next->len) {
518 			/* Eat head of the next overlapped fragment
519 			 * and leave the loop. The next ones cannot overlap.
520 			 */
521 			if (!pskb_pull(next, i))
522 				goto err;
523 			FRAG6_CB(next)->offset += i;	/* next fragment */
524 			fq->meat -= i;
525 			if (next->ip_summed != CHECKSUM_UNNECESSARY)
526 				next->ip_summed = CHECKSUM_NONE;
527 			break;
528 		} else {
529 			struct sk_buff *free_it = next;
530 
531 			/* Old fragment is completely overridden with
532 			 * new one drop it.
533 			 */
534 			next = next->next;
535 
536 			if (prev)
537 				prev->next = next;
538 			else
539 				fq->fragments = next;
540 
541 			fq->meat -= free_it->len;
542 			frag_kfree_skb(free_it, NULL);
543 		}
544 	}
545 
546 	FRAG6_CB(skb)->offset = offset;
547 
548 	/* Insert this fragment in the chain of fragments. */
549 	skb->next = next;
550 	if (prev)
551 		prev->next = skb;
552 	else
553 		fq->fragments = skb;
554 
555 	if (skb->dev)
556 		fq->iif = skb->dev->ifindex;
557 	skb->dev = NULL;
558 	skb_get_timestamp(skb, &fq->stamp);
559 	fq->meat += skb->len;
560 	atomic_add(skb->truesize, &ip6_frag_mem);
561 
562 	/* The first fragment.
563 	 * nhoffset is obtained from the first fragment, of course.
564 	 */
565 	if (offset == 0) {
566 		fq->nhoffset = nhoff;
567 		fq->last_in |= FIRST_IN;
568 	}
569 	write_lock(&ip6_frag_lock);
570 	list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
571 	write_unlock(&ip6_frag_lock);
572 	return;
573 
574 err:
575 	IP6_INC_STATS(IPSTATS_MIB_REASMFAILS);
576 	kfree_skb(skb);
577 }
578 
579 /*
580  *	Check if this packet is complete.
581  *	Returns NULL on failure by any reason, and pointer
582  *	to current nexthdr field in reassembled frame.
583  *
584  *	It is called with locked fq, and caller must check that
585  *	queue is eligible for reassembly i.e. it is not COMPLETE,
586  *	the last and the first frames arrived and all the bits are here.
587  */
588 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
589 			  struct net_device *dev)
590 {
591 	struct sk_buff *fp, *head = fq->fragments;
592 	int    payload_len;
593 	unsigned int nhoff;
594 
595 	fq_kill(fq);
596 
597 	BUG_TRAP(head != NULL);
598 	BUG_TRAP(FRAG6_CB(head)->offset == 0);
599 
600 	/* Unfragmented part is taken from the first segment. */
601 	payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
602 	if (payload_len > IPV6_MAXPLEN)
603 		goto out_oversize;
604 
605 	/* Head of list must not be cloned. */
606 	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
607 		goto out_oom;
608 
609 	/* If the first fragment is fragmented itself, we split
610 	 * it to two chunks: the first with data and paged part
611 	 * and the second, holding only fragments. */
612 	if (skb_shinfo(head)->frag_list) {
613 		struct sk_buff *clone;
614 		int i, plen = 0;
615 
616 		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
617 			goto out_oom;
618 		clone->next = head->next;
619 		head->next = clone;
620 		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
621 		skb_shinfo(head)->frag_list = NULL;
622 		for (i=0; i<skb_shinfo(head)->nr_frags; i++)
623 			plen += skb_shinfo(head)->frags[i].size;
624 		clone->len = clone->data_len = head->data_len - plen;
625 		head->data_len -= clone->len;
626 		head->len -= clone->len;
627 		clone->csum = 0;
628 		clone->ip_summed = head->ip_summed;
629 		atomic_add(clone->truesize, &ip6_frag_mem);
630 	}
631 
632 	/* We have to remove fragment header from datagram and to relocate
633 	 * header in order to calculate ICV correctly. */
634 	nhoff = fq->nhoffset;
635 	head->nh.raw[nhoff] = head->h.raw[0];
636 	memmove(head->head + sizeof(struct frag_hdr), head->head,
637 		(head->data - head->head) - sizeof(struct frag_hdr));
638 	head->mac.raw += sizeof(struct frag_hdr);
639 	head->nh.raw += sizeof(struct frag_hdr);
640 
641 	skb_shinfo(head)->frag_list = head->next;
642 	head->h.raw = head->data;
643 	skb_push(head, head->data - head->nh.raw);
644 	atomic_sub(head->truesize, &ip6_frag_mem);
645 
646 	for (fp=head->next; fp; fp = fp->next) {
647 		head->data_len += fp->len;
648 		head->len += fp->len;
649 		if (head->ip_summed != fp->ip_summed)
650 			head->ip_summed = CHECKSUM_NONE;
651 		else if (head->ip_summed == CHECKSUM_HW)
652 			head->csum = csum_add(head->csum, fp->csum);
653 		head->truesize += fp->truesize;
654 		atomic_sub(fp->truesize, &ip6_frag_mem);
655 	}
656 
657 	head->next = NULL;
658 	head->dev = dev;
659 	skb_set_timestamp(head, &fq->stamp);
660 	head->nh.ipv6h->payload_len = htons(payload_len);
661 	IP6CB(head)->nhoff = nhoff;
662 
663 	*skb_in = head;
664 
665 	/* Yes, and fold redundant checksum back. 8) */
666 	if (head->ip_summed == CHECKSUM_HW)
667 		head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
668 
669 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
670 	fq->fragments = NULL;
671 	return 1;
672 
673 out_oversize:
674 	if (net_ratelimit())
675 		printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
676 	goto out_fail;
677 out_oom:
678 	if (net_ratelimit())
679 		printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
680 out_fail:
681 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
682 	return -1;
683 }
684 
685 static int ipv6_frag_rcv(struct sk_buff **skbp)
686 {
687 	struct sk_buff *skb = *skbp;
688 	struct net_device *dev = skb->dev;
689 	struct frag_hdr *fhdr;
690 	struct frag_queue *fq;
691 	struct ipv6hdr *hdr;
692 
693 	hdr = skb->nh.ipv6h;
694 
695 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
696 
697 	/* Jumbo payload inhibits frag. header */
698 	if (hdr->payload_len==0) {
699 		IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
700 		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
701 		return -1;
702 	}
703 	if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
704 		IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
705 		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
706 		return -1;
707 	}
708 
709 	hdr = skb->nh.ipv6h;
710 	fhdr = (struct frag_hdr *)skb->h.raw;
711 
712 	if (!(fhdr->frag_off & htons(0xFFF9))) {
713 		/* It is not a fragmented frame */
714 		skb->h.raw += sizeof(struct frag_hdr);
715 		IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
716 
717 		IP6CB(skb)->nhoff = (u8*)fhdr - skb->nh.raw;
718 		return 1;
719 	}
720 
721 	if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
722 		ip6_evictor();
723 
724 	if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
725 		int ret = -1;
726 
727 		spin_lock(&fq->lock);
728 
729 		ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
730 
731 		if (fq->last_in == (FIRST_IN|LAST_IN) &&
732 		    fq->meat == fq->len)
733 			ret = ip6_frag_reasm(fq, skbp, dev);
734 
735 		spin_unlock(&fq->lock);
736 		fq_put(fq, NULL);
737 		return ret;
738 	}
739 
740 	IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
741 	kfree_skb(skb);
742 	return -1;
743 }
744 
745 static struct inet6_protocol frag_protocol =
746 {
747 	.handler	=	ipv6_frag_rcv,
748 	.flags		=	INET6_PROTO_NOPOLICY,
749 };
750 
751 void __init ipv6_frag_init(void)
752 {
753 	if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
754 		printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
755 
756 	ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
757 				   (jiffies ^ (jiffies >> 6)));
758 
759 	init_timer(&ip6_frag_secret_timer);
760 	ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
761 	ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
762 	add_timer(&ip6_frag_secret_timer);
763 }
764