Merge branch 'mymerge' of ssh://ozlabs.org/home/sfr/kernel-sfr
[linux-2.6] / net / ipv6 / reassembly.c
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 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
125                                struct in6_addr *daddr)
126 {
127         u32 a, b, c;
128
129         a = saddr->s6_addr32[0];
130         b = saddr->s6_addr32[1];
131         c = saddr->s6_addr32[2];
132
133         a += JHASH_GOLDEN_RATIO;
134         b += JHASH_GOLDEN_RATIO;
135         c += ip6_frag_hash_rnd;
136         __jhash_mix(a, b, c);
137
138         a += saddr->s6_addr32[3];
139         b += daddr->s6_addr32[0];
140         c += daddr->s6_addr32[1];
141         __jhash_mix(a, b, c);
142
143         a += daddr->s6_addr32[2];
144         b += daddr->s6_addr32[3];
145         c += id;
146         __jhash_mix(a, b, c);
147
148         return c & (IP6Q_HASHSZ - 1);
149 }
150
151 static struct timer_list ip6_frag_secret_timer;
152 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
153
154 static void ip6_frag_secret_rebuild(unsigned long dummy)
155 {
156         unsigned long now = jiffies;
157         int i;
158
159         write_lock(&ip6_frag_lock);
160         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
161         for (i = 0; i < IP6Q_HASHSZ; i++) {
162                 struct frag_queue *q;
163                 struct hlist_node *p, *n;
164
165                 hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
166                         unsigned int hval = ip6qhashfn(q->id,
167                                                        &q->saddr,
168                                                        &q->daddr);
169
170                         if (hval != i) {
171                                 hlist_del(&q->list);
172
173                                 /* Relink to new hash chain. */
174                                 hlist_add_head(&q->list,
175                                                &ip6_frag_hash[hval]);
176
177                         }
178                 }
179         }
180         write_unlock(&ip6_frag_lock);
181
182         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
183 }
184
185 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
186
187 /* Memory Tracking Functions. */
188 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
189 {
190         if (work)
191                 *work -= skb->truesize;
192         atomic_sub(skb->truesize, &ip6_frag_mem);
193         kfree_skb(skb);
194 }
195
196 static inline void frag_free_queue(struct frag_queue *fq, int *work)
197 {
198         if (work)
199                 *work -= sizeof(struct frag_queue);
200         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
201         kfree(fq);
202 }
203
204 static inline struct frag_queue *frag_alloc_queue(void)
205 {
206         struct frag_queue *fq = kmalloc(sizeof(struct frag_queue), GFP_ATOMIC);
207
208         if(!fq)
209                 return NULL;
210         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
211         return fq;
212 }
213
214 /* Destruction primitives. */
215
216 /* Complete destruction of fq. */
217 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
218 {
219         struct sk_buff *fp;
220
221         BUG_TRAP(fq->last_in&COMPLETE);
222         BUG_TRAP(del_timer(&fq->timer) == 0);
223
224         /* Release all fragment data. */
225         fp = fq->fragments;
226         while (fp) {
227                 struct sk_buff *xp = fp->next;
228
229                 frag_kfree_skb(fp, work);
230                 fp = xp;
231         }
232
233         frag_free_queue(fq, work);
234 }
235
236 static __inline__ void fq_put(struct frag_queue *fq, int *work)
237 {
238         if (atomic_dec_and_test(&fq->refcnt))
239                 ip6_frag_destroy(fq, work);
240 }
241
242 /* Kill fq entry. It is not destroyed immediately,
243  * because caller (and someone more) holds reference count.
244  */
245 static __inline__ void fq_kill(struct frag_queue *fq)
246 {
247         if (del_timer(&fq->timer))
248                 atomic_dec(&fq->refcnt);
249
250         if (!(fq->last_in & COMPLETE)) {
251                 fq_unlink(fq);
252                 atomic_dec(&fq->refcnt);
253                 fq->last_in |= COMPLETE;
254         }
255 }
256
257 static void ip6_evictor(void)
258 {
259         struct frag_queue *fq;
260         struct list_head *tmp;
261         int work;
262
263         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
264         if (work <= 0)
265                 return;
266
267         while(work > 0) {
268                 read_lock(&ip6_frag_lock);
269                 if (list_empty(&ip6_frag_lru_list)) {
270                         read_unlock(&ip6_frag_lock);
271                         return;
272                 }
273                 tmp = ip6_frag_lru_list.next;
274                 fq = list_entry(tmp, struct frag_queue, lru_list);
275                 atomic_inc(&fq->refcnt);
276                 read_unlock(&ip6_frag_lock);
277
278                 spin_lock(&fq->lock);
279                 if (!(fq->last_in&COMPLETE))
280                         fq_kill(fq);
281                 spin_unlock(&fq->lock);
282
283                 fq_put(fq, &work);
284                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
285         }
286 }
287
288 static void ip6_frag_expire(unsigned long data)
289 {
290         struct frag_queue *fq = (struct frag_queue *) data;
291
292         spin_lock(&fq->lock);
293
294         if (fq->last_in & COMPLETE)
295                 goto out;
296
297         fq_kill(fq);
298
299         IP6_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
300         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
301
302         /* Send error only if the first segment arrived. */
303         if (fq->last_in&FIRST_IN && fq->fragments) {
304                 struct net_device *dev = dev_get_by_index(fq->iif);
305
306                 /*
307                    But use as source device on which LAST ARRIVED
308                    segment was received. And do not use fq->dev
309                    pointer directly, device might already disappeared.
310                  */
311                 if (dev) {
312                         fq->fragments->dev = dev;
313                         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0,
314                                     dev);
315                         dev_put(dev);
316                 }
317         }
318 out:
319         spin_unlock(&fq->lock);
320         fq_put(fq, NULL);
321 }
322
323 /* Creation primitives. */
324
325
326 static struct frag_queue *ip6_frag_intern(unsigned int hash,
327                                           struct frag_queue *fq_in)
328 {
329         struct frag_queue *fq;
330 #ifdef CONFIG_SMP
331         struct hlist_node *n;
332 #endif
333
334         write_lock(&ip6_frag_lock);
335 #ifdef CONFIG_SMP
336         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
337                 if (fq->id == fq_in->id && 
338                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
339                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
340                         atomic_inc(&fq->refcnt);
341                         write_unlock(&ip6_frag_lock);
342                         fq_in->last_in |= COMPLETE;
343                         fq_put(fq_in, NULL);
344                         return fq;
345                 }
346         }
347 #endif
348         fq = fq_in;
349
350         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
351                 atomic_inc(&fq->refcnt);
352
353         atomic_inc(&fq->refcnt);
354         hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
355         INIT_LIST_HEAD(&fq->lru_list);
356         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
357         ip6_frag_nqueues++;
358         write_unlock(&ip6_frag_lock);
359         return fq;
360 }
361
362
363 static struct frag_queue *
364 ip6_frag_create(unsigned int hash, u32 id, struct in6_addr *src, struct in6_addr *dst)
365 {
366         struct frag_queue *fq;
367
368         if ((fq = frag_alloc_queue()) == NULL)
369                 goto oom;
370
371         memset(fq, 0, sizeof(struct frag_queue));
372
373         fq->id = id;
374         ipv6_addr_copy(&fq->saddr, src);
375         ipv6_addr_copy(&fq->daddr, dst);
376
377         init_timer(&fq->timer);
378         fq->timer.function = ip6_frag_expire;
379         fq->timer.data = (long) fq;
380         spin_lock_init(&fq->lock);
381         atomic_set(&fq->refcnt, 1);
382
383         return ip6_frag_intern(hash, fq);
384
385 oom:
386         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
387         return NULL;
388 }
389
390 static __inline__ struct frag_queue *
391 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
392 {
393         struct frag_queue *fq;
394         struct hlist_node *n;
395         unsigned int hash = ip6qhashfn(id, src, dst);
396
397         read_lock(&ip6_frag_lock);
398         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
399                 if (fq->id == id && 
400                     ipv6_addr_equal(src, &fq->saddr) &&
401                     ipv6_addr_equal(dst, &fq->daddr)) {
402                         atomic_inc(&fq->refcnt);
403                         read_unlock(&ip6_frag_lock);
404                         return fq;
405                 }
406         }
407         read_unlock(&ip6_frag_lock);
408
409         return ip6_frag_create(hash, id, src, dst);
410 }
411
412
413 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, 
414                            struct frag_hdr *fhdr, int nhoff)
415 {
416         struct sk_buff *prev, *next;
417         int offset, end;
418
419         if (fq->last_in & COMPLETE)
420                 goto err;
421
422         offset = ntohs(fhdr->frag_off) & ~0x7;
423         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
424                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
425
426         if ((unsigned int)end > IPV6_MAXPLEN) {
427                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
428                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
429                 return;
430         }
431
432         if (skb->ip_summed == CHECKSUM_HW)
433                 skb->csum = csum_sub(skb->csum,
434                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
435
436         /* Is this the final fragment? */
437         if (!(fhdr->frag_off & htons(IP6_MF))) {
438                 /* If we already have some bits beyond end
439                  * or have different end, the segment is corrupted.
440                  */
441                 if (end < fq->len ||
442                     ((fq->last_in & LAST_IN) && end != fq->len))
443                         goto err;
444                 fq->last_in |= LAST_IN;
445                 fq->len = end;
446         } else {
447                 /* Check if the fragment is rounded to 8 bytes.
448                  * Required by the RFC.
449                  */
450                 if (end & 0x7) {
451                         /* RFC2460 says always send parameter problem in
452                          * this case. -DaveM
453                          */
454                         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
455                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, 
456                                           offsetof(struct ipv6hdr, payload_len));
457                         return;
458                 }
459                 if (end > fq->len) {
460                         /* Some bits beyond end -> corruption. */
461                         if (fq->last_in & LAST_IN)
462                                 goto err;
463                         fq->len = end;
464                 }
465         }
466
467         if (end == offset)
468                 goto err;
469
470         /* Point into the IP datagram 'data' part. */
471         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
472                 goto err;
473         
474         if (pskb_trim_rcsum(skb, end - offset))
475                 goto err;
476
477         /* Find out which fragments are in front and at the back of us
478          * in the chain of fragments so far.  We must know where to put
479          * this fragment, right?
480          */
481         prev = NULL;
482         for(next = fq->fragments; next != NULL; next = next->next) {
483                 if (FRAG6_CB(next)->offset >= offset)
484                         break;  /* bingo! */
485                 prev = next;
486         }
487
488         /* We found where to put this one.  Check for overlap with
489          * preceding fragment, and, if needed, align things so that
490          * any overlaps are eliminated.
491          */
492         if (prev) {
493                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
494
495                 if (i > 0) {
496                         offset += i;
497                         if (end <= offset)
498                                 goto err;
499                         if (!pskb_pull(skb, i))
500                                 goto err;
501                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
502                                 skb->ip_summed = CHECKSUM_NONE;
503                 }
504         }
505
506         /* Look for overlap with succeeding segments.
507          * If we can merge fragments, do it.
508          */
509         while (next && FRAG6_CB(next)->offset < end) {
510                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
511
512                 if (i < next->len) {
513                         /* Eat head of the next overlapped fragment
514                          * and leave the loop. The next ones cannot overlap.
515                          */
516                         if (!pskb_pull(next, i))
517                                 goto err;
518                         FRAG6_CB(next)->offset += i;    /* next fragment */
519                         fq->meat -= i;
520                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
521                                 next->ip_summed = CHECKSUM_NONE;
522                         break;
523                 } else {
524                         struct sk_buff *free_it = next;
525
526                         /* Old fragment is completely overridden with
527                          * new one drop it.
528                          */
529                         next = next->next;
530
531                         if (prev)
532                                 prev->next = next;
533                         else
534                                 fq->fragments = next;
535
536                         fq->meat -= free_it->len;
537                         frag_kfree_skb(free_it, NULL);
538                 }
539         }
540
541         FRAG6_CB(skb)->offset = offset;
542
543         /* Insert this fragment in the chain of fragments. */
544         skb->next = next;
545         if (prev)
546                 prev->next = skb;
547         else
548                 fq->fragments = skb;
549
550         if (skb->dev)
551                 fq->iif = skb->dev->ifindex;
552         skb->dev = NULL;
553         skb_get_timestamp(skb, &fq->stamp);
554         fq->meat += skb->len;
555         atomic_add(skb->truesize, &ip6_frag_mem);
556
557         /* The first fragment.
558          * nhoffset is obtained from the first fragment, of course.
559          */
560         if (offset == 0) {
561                 fq->nhoffset = nhoff;
562                 fq->last_in |= FIRST_IN;
563         }
564         write_lock(&ip6_frag_lock);
565         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
566         write_unlock(&ip6_frag_lock);
567         return;
568
569 err:
570         IP6_INC_STATS(IPSTATS_MIB_REASMFAILS);
571         kfree_skb(skb);
572 }
573
574 /*
575  *      Check if this packet is complete.
576  *      Returns NULL on failure by any reason, and pointer
577  *      to current nexthdr field in reassembled frame.
578  *
579  *      It is called with locked fq, and caller must check that
580  *      queue is eligible for reassembly i.e. it is not COMPLETE,
581  *      the last and the first frames arrived and all the bits are here.
582  */
583 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
584                           unsigned int *nhoffp,
585                           struct net_device *dev)
586 {
587         struct sk_buff *fp, *head = fq->fragments;
588         int    payload_len;
589         unsigned int nhoff;
590
591         fq_kill(fq);
592
593         BUG_TRAP(head != NULL);
594         BUG_TRAP(FRAG6_CB(head)->offset == 0);
595
596         /* Unfragmented part is taken from the first segment. */
597         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
598         if (payload_len > IPV6_MAXPLEN)
599                 goto out_oversize;
600
601         /* Head of list must not be cloned. */
602         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
603                 goto out_oom;
604
605         /* If the first fragment is fragmented itself, we split
606          * it to two chunks: the first with data and paged part
607          * and the second, holding only fragments. */
608         if (skb_shinfo(head)->frag_list) {
609                 struct sk_buff *clone;
610                 int i, plen = 0;
611
612                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
613                         goto out_oom;
614                 clone->next = head->next;
615                 head->next = clone;
616                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
617                 skb_shinfo(head)->frag_list = NULL;
618                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
619                         plen += skb_shinfo(head)->frags[i].size;
620                 clone->len = clone->data_len = head->data_len - plen;
621                 head->data_len -= clone->len;
622                 head->len -= clone->len;
623                 clone->csum = 0;
624                 clone->ip_summed = head->ip_summed;
625                 atomic_add(clone->truesize, &ip6_frag_mem);
626         }
627
628         /* We have to remove fragment header from datagram and to relocate
629          * header in order to calculate ICV correctly. */
630         nhoff = fq->nhoffset;
631         head->nh.raw[nhoff] = head->h.raw[0];
632         memmove(head->head + sizeof(struct frag_hdr), head->head, 
633                 (head->data - head->head) - sizeof(struct frag_hdr));
634         head->mac.raw += sizeof(struct frag_hdr);
635         head->nh.raw += sizeof(struct frag_hdr);
636
637         skb_shinfo(head)->frag_list = head->next;
638         head->h.raw = head->data;
639         skb_push(head, head->data - head->nh.raw);
640         atomic_sub(head->truesize, &ip6_frag_mem);
641
642         for (fp=head->next; fp; fp = fp->next) {
643                 head->data_len += fp->len;
644                 head->len += fp->len;
645                 if (head->ip_summed != fp->ip_summed)
646                         head->ip_summed = CHECKSUM_NONE;
647                 else if (head->ip_summed == CHECKSUM_HW)
648                         head->csum = csum_add(head->csum, fp->csum);
649                 head->truesize += fp->truesize;
650                 atomic_sub(fp->truesize, &ip6_frag_mem);
651         }
652
653         head->next = NULL;
654         head->dev = dev;
655         skb_set_timestamp(head, &fq->stamp);
656         head->nh.ipv6h->payload_len = htons(payload_len);
657
658         *skb_in = head;
659
660         /* Yes, and fold redundant checksum back. 8) */
661         if (head->ip_summed == CHECKSUM_HW)
662                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
663
664         IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
665         fq->fragments = NULL;
666         *nhoffp = nhoff;
667         return 1;
668
669 out_oversize:
670         if (net_ratelimit())
671                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
672         goto out_fail;
673 out_oom:
674         if (net_ratelimit())
675                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
676 out_fail:
677         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
678         return -1;
679 }
680
681 static int ipv6_frag_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
682 {
683         struct sk_buff *skb = *skbp; 
684         struct net_device *dev = skb->dev;
685         struct frag_hdr *fhdr;
686         struct frag_queue *fq;
687         struct ipv6hdr *hdr;
688
689         hdr = skb->nh.ipv6h;
690
691         IP6_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
692
693         /* Jumbo payload inhibits frag. header */
694         if (hdr->payload_len==0) {
695                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
696                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
697                 return -1;
698         }
699         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
700                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
701                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
702                 return -1;
703         }
704
705         hdr = skb->nh.ipv6h;
706         fhdr = (struct frag_hdr *)skb->h.raw;
707
708         if (!(fhdr->frag_off & htons(0xFFF9))) {
709                 /* It is not a fragmented frame */
710                 skb->h.raw += sizeof(struct frag_hdr);
711                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
712
713                 *nhoffp = (u8*)fhdr - skb->nh.raw;
714                 return 1;
715         }
716
717         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
718                 ip6_evictor();
719
720         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
721                 int ret = -1;
722
723                 spin_lock(&fq->lock);
724
725                 ip6_frag_queue(fq, skb, fhdr, *nhoffp);
726
727                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
728                     fq->meat == fq->len)
729                         ret = ip6_frag_reasm(fq, skbp, nhoffp, dev);
730
731                 spin_unlock(&fq->lock);
732                 fq_put(fq, NULL);
733                 return ret;
734         }
735
736         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
737         kfree_skb(skb);
738         return -1;
739 }
740
741 static struct inet6_protocol frag_protocol =
742 {
743         .handler        =       ipv6_frag_rcv,
744         .flags          =       INET6_PROTO_NOPOLICY,
745 };
746
747 void __init ipv6_frag_init(void)
748 {
749         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
750                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
751
752         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
753                                    (jiffies ^ (jiffies >> 6)));
754
755         init_timer(&ip6_frag_secret_timer);
756         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
757         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
758         add_timer(&ip6_frag_secret_timer);
759 }