c311b9a12ca688b661cd61ce16847bc834781449
[linux-2.6.git] / net / ipv6 / netfilter / nf_conntrack_reasm.c
1 /*
2  * IPv6 fragment reassembly for connection tracking
3  *
4  * Copyright (C)2004 USAGI/WIDE Project
5  *
6  * Author:
7  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
8  *
9  * Based on: net/ipv6/reassembly.c
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License
13  * as published by the Free Software Foundation; either version
14  * 2 of the License, or (at your option) any later version.
15  */
16
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/string.h>
20 #include <linux/socket.h>
21 #include <linux/sockios.h>
22 #include <linux/jiffies.h>
23 #include <linux/net.h>
24 #include <linux/list.h>
25 #include <linux/netdevice.h>
26 #include <linux/in6.h>
27 #include <linux/ipv6.h>
28 #include <linux/icmpv6.h>
29 #include <linux/random.h>
30 #include <linux/jhash.h>
31
32 #include <net/sock.h>
33 #include <net/snmp.h>
34
35 #include <net/ipv6.h>
36 #include <net/protocol.h>
37 #include <net/transp_v6.h>
38 #include <net/rawv6.h>
39 #include <net/ndisc.h>
40 #include <net/addrconf.h>
41 #include <linux/sysctl.h>
42 #include <linux/netfilter.h>
43 #include <linux/netfilter_ipv6.h>
44 #include <linux/kernel.h>
45 #include <linux/module.h>
46
47 #if 0
48 #define DEBUGP printk
49 #else
50 #define DEBUGP(format, args...)
51 #endif
52
53 #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
54 #define NF_CT_FRAG6_LOW_THRESH 196608  /* == 192*1024 */
55 #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
56
57 unsigned int nf_ct_frag6_high_thresh __read_mostly = 256*1024;
58 unsigned int nf_ct_frag6_low_thresh __read_mostly = 192*1024;
59 unsigned long nf_ct_frag6_timeout __read_mostly = IPV6_FRAG_TIMEOUT;
60
61 struct nf_ct_frag6_skb_cb
62 {
63         struct inet6_skb_parm   h;
64         int                     offset;
65         struct sk_buff          *orig;
66 };
67
68 #define NFCT_FRAG6_CB(skb)      ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
69
70 struct nf_ct_frag6_queue
71 {
72         struct hlist_node       list;
73         struct list_head        lru_list;       /* lru list member      */
74
75         __be32                  id;             /* fragment id          */
76         struct in6_addr         saddr;
77         struct in6_addr         daddr;
78
79         spinlock_t              lock;
80         atomic_t                refcnt;
81         struct timer_list       timer;          /* expire timer         */
82         struct sk_buff          *fragments;
83         int                     len;
84         int                     meat;
85         ktime_t                 stamp;
86         unsigned int            csum;
87         __u8                    last_in;        /* has first/last segment arrived? */
88 #define COMPLETE                4
89 #define FIRST_IN                2
90 #define LAST_IN                 1
91         __u16                   nhoffset;
92 };
93
94 /* Hash table. */
95
96 #define FRAG6Q_HASHSZ   64
97
98 static struct hlist_head nf_ct_frag6_hash[FRAG6Q_HASHSZ];
99 static DEFINE_RWLOCK(nf_ct_frag6_lock);
100 static u32 nf_ct_frag6_hash_rnd;
101 static LIST_HEAD(nf_ct_frag6_lru_list);
102 int nf_ct_frag6_nqueues = 0;
103
104 static __inline__ void __fq_unlink(struct nf_ct_frag6_queue *fq)
105 {
106         hlist_del(&fq->list);
107         list_del(&fq->lru_list);
108         nf_ct_frag6_nqueues--;
109 }
110
111 static __inline__ void fq_unlink(struct nf_ct_frag6_queue *fq)
112 {
113         write_lock(&nf_ct_frag6_lock);
114         __fq_unlink(fq);
115         write_unlock(&nf_ct_frag6_lock);
116 }
117
118 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
119                                struct in6_addr *daddr)
120 {
121         u32 a, b, c;
122
123         a = (__force u32)saddr->s6_addr32[0];
124         b = (__force u32)saddr->s6_addr32[1];
125         c = (__force u32)saddr->s6_addr32[2];
126
127         a += JHASH_GOLDEN_RATIO;
128         b += JHASH_GOLDEN_RATIO;
129         c += nf_ct_frag6_hash_rnd;
130         __jhash_mix(a, b, c);
131
132         a += (__force u32)saddr->s6_addr32[3];
133         b += (__force u32)daddr->s6_addr32[0];
134         c += (__force u32)daddr->s6_addr32[1];
135         __jhash_mix(a, b, c);
136
137         a += (__force u32)daddr->s6_addr32[2];
138         b += (__force u32)daddr->s6_addr32[3];
139         c += (__force u32)id;
140         __jhash_mix(a, b, c);
141
142         return c & (FRAG6Q_HASHSZ - 1);
143 }
144
145 static struct timer_list nf_ct_frag6_secret_timer;
146 int nf_ct_frag6_secret_interval = 10 * 60 * HZ;
147
148 static void nf_ct_frag6_secret_rebuild(unsigned long dummy)
149 {
150         unsigned long now = jiffies;
151         int i;
152
153         write_lock(&nf_ct_frag6_lock);
154         get_random_bytes(&nf_ct_frag6_hash_rnd, sizeof(u32));
155         for (i = 0; i < FRAG6Q_HASHSZ; i++) {
156                 struct nf_ct_frag6_queue *q;
157                 struct hlist_node *p, *n;
158
159                 hlist_for_each_entry_safe(q, p, n, &nf_ct_frag6_hash[i], list) {
160                         unsigned int hval = ip6qhashfn(q->id,
161                                                        &q->saddr,
162                                                        &q->daddr);
163                         if (hval != i) {
164                                 hlist_del(&q->list);
165                                 /* Relink to new hash chain. */
166                                 hlist_add_head(&q->list,
167                                                &nf_ct_frag6_hash[hval]);
168                         }
169                 }
170         }
171         write_unlock(&nf_ct_frag6_lock);
172
173         mod_timer(&nf_ct_frag6_secret_timer, now + nf_ct_frag6_secret_interval);
174 }
175
176 atomic_t nf_ct_frag6_mem = ATOMIC_INIT(0);
177
178 /* Memory Tracking Functions. */
179 static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
180 {
181         if (work)
182                 *work -= skb->truesize;
183         atomic_sub(skb->truesize, &nf_ct_frag6_mem);
184         if (NFCT_FRAG6_CB(skb)->orig)
185                 kfree_skb(NFCT_FRAG6_CB(skb)->orig);
186
187         kfree_skb(skb);
188 }
189
190 static inline void frag_free_queue(struct nf_ct_frag6_queue *fq,
191                                    unsigned int *work)
192 {
193         if (work)
194                 *work -= sizeof(struct nf_ct_frag6_queue);
195         atomic_sub(sizeof(struct nf_ct_frag6_queue), &nf_ct_frag6_mem);
196         kfree(fq);
197 }
198
199 static inline struct nf_ct_frag6_queue *frag_alloc_queue(void)
200 {
201         struct nf_ct_frag6_queue *fq = kmalloc(sizeof(struct nf_ct_frag6_queue), GFP_ATOMIC);
202
203         if (!fq)
204                 return NULL;
205         atomic_add(sizeof(struct nf_ct_frag6_queue), &nf_ct_frag6_mem);
206         return fq;
207 }
208
209 /* Destruction primitives. */
210
211 /* Complete destruction of fq. */
212 static void nf_ct_frag6_destroy(struct nf_ct_frag6_queue *fq,
213                                 unsigned int *work)
214 {
215         struct sk_buff *fp;
216
217         BUG_TRAP(fq->last_in&COMPLETE);
218         BUG_TRAP(del_timer(&fq->timer) == 0);
219
220         /* Release all fragment data. */
221         fp = fq->fragments;
222         while (fp) {
223                 struct sk_buff *xp = fp->next;
224
225                 frag_kfree_skb(fp, work);
226                 fp = xp;
227         }
228
229         frag_free_queue(fq, work);
230 }
231
232 static __inline__ void fq_put(struct nf_ct_frag6_queue *fq, unsigned int *work)
233 {
234         if (atomic_dec_and_test(&fq->refcnt))
235                 nf_ct_frag6_destroy(fq, work);
236 }
237
238 /* Kill fq entry. It is not destroyed immediately,
239  * because caller (and someone more) holds reference count.
240  */
241 static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
242 {
243         if (del_timer(&fq->timer))
244                 atomic_dec(&fq->refcnt);
245
246         if (!(fq->last_in & COMPLETE)) {
247                 fq_unlink(fq);
248                 atomic_dec(&fq->refcnt);
249                 fq->last_in |= COMPLETE;
250         }
251 }
252
253 static void nf_ct_frag6_evictor(void)
254 {
255         struct nf_ct_frag6_queue *fq;
256         struct list_head *tmp;
257         unsigned int work;
258
259         work = atomic_read(&nf_ct_frag6_mem);
260         if (work <= nf_ct_frag6_low_thresh)
261                 return;
262
263         work -= nf_ct_frag6_low_thresh;
264         while (work > 0) {
265                 read_lock(&nf_ct_frag6_lock);
266                 if (list_empty(&nf_ct_frag6_lru_list)) {
267                         read_unlock(&nf_ct_frag6_lock);
268                         return;
269                 }
270                 tmp = nf_ct_frag6_lru_list.next;
271                 BUG_ON(tmp == NULL);
272                 fq = list_entry(tmp, struct nf_ct_frag6_queue, lru_list);
273                 atomic_inc(&fq->refcnt);
274                 read_unlock(&nf_ct_frag6_lock);
275
276                 spin_lock(&fq->lock);
277                 if (!(fq->last_in&COMPLETE))
278                         fq_kill(fq);
279                 spin_unlock(&fq->lock);
280
281                 fq_put(fq, &work);
282         }
283 }
284
285 static void nf_ct_frag6_expire(unsigned long data)
286 {
287         struct nf_ct_frag6_queue *fq = (struct nf_ct_frag6_queue *) data;
288
289         spin_lock(&fq->lock);
290
291         if (fq->last_in & COMPLETE)
292                 goto out;
293
294         fq_kill(fq);
295
296 out:
297         spin_unlock(&fq->lock);
298         fq_put(fq, NULL);
299 }
300
301 /* Creation primitives. */
302
303 static struct nf_ct_frag6_queue *nf_ct_frag6_intern(unsigned int hash,
304                                           struct nf_ct_frag6_queue *fq_in)
305 {
306         struct nf_ct_frag6_queue *fq;
307 #ifdef CONFIG_SMP
308         struct hlist_node *n;
309 #endif
310
311         write_lock(&nf_ct_frag6_lock);
312 #ifdef CONFIG_SMP
313         hlist_for_each_entry(fq, n, &nf_ct_frag6_hash[hash], list) {
314                 if (fq->id == fq_in->id &&
315                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
316                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
317                         atomic_inc(&fq->refcnt);
318                         write_unlock(&nf_ct_frag6_lock);
319                         fq_in->last_in |= COMPLETE;
320                         fq_put(fq_in, NULL);
321                         return fq;
322                 }
323         }
324 #endif
325         fq = fq_in;
326
327         if (!mod_timer(&fq->timer, jiffies + nf_ct_frag6_timeout))
328                 atomic_inc(&fq->refcnt);
329
330         atomic_inc(&fq->refcnt);
331         hlist_add_head(&fq->list, &nf_ct_frag6_hash[hash]);
332         INIT_LIST_HEAD(&fq->lru_list);
333         list_add_tail(&fq->lru_list, &nf_ct_frag6_lru_list);
334         nf_ct_frag6_nqueues++;
335         write_unlock(&nf_ct_frag6_lock);
336         return fq;
337 }
338
339
340 static struct nf_ct_frag6_queue *
341 nf_ct_frag6_create(unsigned int hash, __be32 id, struct in6_addr *src,                             struct in6_addr *dst)
342 {
343         struct nf_ct_frag6_queue *fq;
344
345         if ((fq = frag_alloc_queue()) == NULL) {
346                 DEBUGP("Can't alloc new queue\n");
347                 goto oom;
348         }
349
350         memset(fq, 0, sizeof(struct nf_ct_frag6_queue));
351
352         fq->id = id;
353         ipv6_addr_copy(&fq->saddr, src);
354         ipv6_addr_copy(&fq->daddr, dst);
355
356         init_timer(&fq->timer);
357         fq->timer.function = nf_ct_frag6_expire;
358         fq->timer.data = (long) fq;
359         spin_lock_init(&fq->lock);
360         atomic_set(&fq->refcnt, 1);
361
362         return nf_ct_frag6_intern(hash, fq);
363
364 oom:
365         return NULL;
366 }
367
368 static __inline__ struct nf_ct_frag6_queue *
369 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
370 {
371         struct nf_ct_frag6_queue *fq;
372         struct hlist_node *n;
373         unsigned int hash = ip6qhashfn(id, src, dst);
374
375         read_lock(&nf_ct_frag6_lock);
376         hlist_for_each_entry(fq, n, &nf_ct_frag6_hash[hash], list) {
377                 if (fq->id == id &&
378                     ipv6_addr_equal(src, &fq->saddr) &&
379                     ipv6_addr_equal(dst, &fq->daddr)) {
380                         atomic_inc(&fq->refcnt);
381                         read_unlock(&nf_ct_frag6_lock);
382                         return fq;
383                 }
384         }
385         read_unlock(&nf_ct_frag6_lock);
386
387         return nf_ct_frag6_create(hash, id, src, dst);
388 }
389
390
391 static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
392                              struct frag_hdr *fhdr, int nhoff)
393 {
394         struct sk_buff *prev, *next;
395         int offset, end;
396
397         if (fq->last_in & COMPLETE) {
398                 DEBUGP("Allready completed\n");
399                 goto err;
400         }
401
402         offset = ntohs(fhdr->frag_off) & ~0x7;
403         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
404                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
405
406         if ((unsigned int)end > IPV6_MAXPLEN) {
407                 DEBUGP("offset is too large.\n");
408                 return -1;
409         }
410
411         if (skb->ip_summed == CHECKSUM_COMPLETE)
412                 skb->csum = csum_sub(skb->csum,
413                                      csum_partial(skb->nh.raw,
414                                                   (u8*)(fhdr + 1) - skb->nh.raw,
415                                                   0));
416
417         /* Is this the final fragment? */
418         if (!(fhdr->frag_off & htons(IP6_MF))) {
419                 /* If we already have some bits beyond end
420                  * or have different end, the segment is corrupted.
421                  */
422                 if (end < fq->len ||
423                     ((fq->last_in & LAST_IN) && end != fq->len)) {
424                         DEBUGP("already received last fragment\n");
425                         goto err;
426                 }
427                 fq->last_in |= LAST_IN;
428                 fq->len = end;
429         } else {
430                 /* Check if the fragment is rounded to 8 bytes.
431                  * Required by the RFC.
432                  */
433                 if (end & 0x7) {
434                         /* RFC2460 says always send parameter problem in
435                          * this case. -DaveM
436                          */
437                         DEBUGP("the end of this fragment is not rounded to 8 bytes.\n");
438                         return -1;
439                 }
440                 if (end > fq->len) {
441                         /* Some bits beyond end -> corruption. */
442                         if (fq->last_in & LAST_IN) {
443                                 DEBUGP("last packet already reached.\n");
444                                 goto err;
445                         }
446                         fq->len = end;
447                 }
448         }
449
450         if (end == offset)
451                 goto err;
452
453         /* Point into the IP datagram 'data' part. */
454         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
455                 DEBUGP("queue: message is too short.\n");
456                 goto err;
457         }
458         if (pskb_trim_rcsum(skb, end - offset)) {
459                 DEBUGP("Can't trim\n");
460                 goto err;
461         }
462
463         /* Find out which fragments are in front and at the back of us
464          * in the chain of fragments so far.  We must know where to put
465          * this fragment, right?
466          */
467         prev = NULL;
468         for (next = fq->fragments; next != NULL; next = next->next) {
469                 if (NFCT_FRAG6_CB(next)->offset >= offset)
470                         break;  /* bingo! */
471                 prev = next;
472         }
473
474         /* We found where to put this one.  Check for overlap with
475          * preceding fragment, and, if needed, align things so that
476          * any overlaps are eliminated.
477          */
478         if (prev) {
479                 int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset;
480
481                 if (i > 0) {
482                         offset += i;
483                         if (end <= offset) {
484                                 DEBUGP("overlap\n");
485                                 goto err;
486                         }
487                         if (!pskb_pull(skb, i)) {
488                                 DEBUGP("Can't pull\n");
489                                 goto err;
490                         }
491                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
492                                 skb->ip_summed = CHECKSUM_NONE;
493                 }
494         }
495
496         /* Look for overlap with succeeding segments.
497          * If we can merge fragments, do it.
498          */
499         while (next && NFCT_FRAG6_CB(next)->offset < end) {
500                 /* overlap is 'i' bytes */
501                 int i = end - NFCT_FRAG6_CB(next)->offset;
502
503                 if (i < next->len) {
504                         /* Eat head of the next overlapped fragment
505                          * and leave the loop. The next ones cannot overlap.
506                          */
507                         DEBUGP("Eat head of the overlapped parts.: %d", i);
508                         if (!pskb_pull(next, i))
509                                 goto err;
510
511                         /* next fragment */
512                         NFCT_FRAG6_CB(next)->offset += i;
513                         fq->meat -= i;
514                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
515                                 next->ip_summed = CHECKSUM_NONE;
516                         break;
517                 } else {
518                         struct sk_buff *free_it = next;
519
520                         /* Old fragmnet is completely overridden with
521                          * new one drop it.
522                          */
523                         next = next->next;
524
525                         if (prev)
526                                 prev->next = next;
527                         else
528                                 fq->fragments = next;
529
530                         fq->meat -= free_it->len;
531                         frag_kfree_skb(free_it, NULL);
532                 }
533         }
534
535         NFCT_FRAG6_CB(skb)->offset = offset;
536
537         /* Insert this fragment in the chain of fragments. */
538         skb->next = next;
539         if (prev)
540                 prev->next = skb;
541         else
542                 fq->fragments = skb;
543
544         skb->dev = NULL;
545         fq->stamp = skb->tstamp;
546         fq->meat += skb->len;
547         atomic_add(skb->truesize, &nf_ct_frag6_mem);
548
549         /* The first fragment.
550          * nhoffset is obtained from the first fragment, of course.
551          */
552         if (offset == 0) {
553                 fq->nhoffset = nhoff;
554                 fq->last_in |= FIRST_IN;
555         }
556         write_lock(&nf_ct_frag6_lock);
557         list_move_tail(&fq->lru_list, &nf_ct_frag6_lru_list);
558         write_unlock(&nf_ct_frag6_lock);
559         return 0;
560
561 err:
562         return -1;
563 }
564
565 /*
566  *      Check if this packet is complete.
567  *      Returns NULL on failure by any reason, and pointer
568  *      to current nexthdr field in reassembled frame.
569  *
570  *      It is called with locked fq, and caller must check that
571  *      queue is eligible for reassembly i.e. it is not COMPLETE,
572  *      the last and the first frames arrived and all the bits are here.
573  */
574 static struct sk_buff *
575 nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
576 {
577         struct sk_buff *fp, *op, *head = fq->fragments;
578         int    payload_len;
579
580         fq_kill(fq);
581
582         BUG_TRAP(head != NULL);
583         BUG_TRAP(NFCT_FRAG6_CB(head)->offset == 0);
584
585         /* Unfragmented part is taken from the first segment. */
586         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
587         if (payload_len > IPV6_MAXPLEN) {
588                 DEBUGP("payload len is too large.\n");
589                 goto out_oversize;
590         }
591
592         /* Head of list must not be cloned. */
593         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
594                 DEBUGP("skb is cloned but can't expand head");
595                 goto out_oom;
596         }
597
598         /* If the first fragment is fragmented itself, we split
599          * it to two chunks: the first with data and paged part
600          * and the second, holding only fragments. */
601         if (skb_shinfo(head)->frag_list) {
602                 struct sk_buff *clone;
603                 int i, plen = 0;
604
605                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
606                         DEBUGP("Can't alloc skb\n");
607                         goto out_oom;
608                 }
609                 clone->next = head->next;
610                 head->next = clone;
611                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
612                 skb_shinfo(head)->frag_list = NULL;
613                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
614                         plen += skb_shinfo(head)->frags[i].size;
615                 clone->len = clone->data_len = head->data_len - plen;
616                 head->data_len -= clone->len;
617                 head->len -= clone->len;
618                 clone->csum = 0;
619                 clone->ip_summed = head->ip_summed;
620
621                 NFCT_FRAG6_CB(clone)->orig = NULL;
622                 atomic_add(clone->truesize, &nf_ct_frag6_mem);
623         }
624
625         /* We have to remove fragment header from datagram and to relocate
626          * header in order to calculate ICV correctly. */
627         head->nh.raw[fq->nhoffset] = head->h.raw[0];
628         memmove(head->head + sizeof(struct frag_hdr), head->head,
629                 (head->data - head->head) - sizeof(struct frag_hdr));
630         head->mac.raw += sizeof(struct frag_hdr);
631         head->nh.raw += sizeof(struct frag_hdr);
632
633         skb_shinfo(head)->frag_list = head->next;
634         head->h.raw = head->data;
635         skb_push(head, head->data - head->nh.raw);
636         atomic_sub(head->truesize, &nf_ct_frag6_mem);
637
638         for (fp=head->next; fp; fp = fp->next) {
639                 head->data_len += fp->len;
640                 head->len += fp->len;
641                 if (head->ip_summed != fp->ip_summed)
642                         head->ip_summed = CHECKSUM_NONE;
643                 else if (head->ip_summed == CHECKSUM_COMPLETE)
644                         head->csum = csum_add(head->csum, fp->csum);
645                 head->truesize += fp->truesize;
646                 atomic_sub(fp->truesize, &nf_ct_frag6_mem);
647         }
648
649         head->next = NULL;
650         head->dev = dev;
651         head->tstamp = fq->stamp;
652         head->nh.ipv6h->payload_len = htons(payload_len);
653
654         /* Yes, and fold redundant checksum back. 8) */
655         if (head->ip_summed == CHECKSUM_COMPLETE)
656                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
657
658         fq->fragments = NULL;
659
660         /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
661         fp = skb_shinfo(head)->frag_list;
662         if (NFCT_FRAG6_CB(fp)->orig == NULL)
663                 /* at above code, head skb is divided into two skbs. */
664                 fp = fp->next;
665
666         op = NFCT_FRAG6_CB(head)->orig;
667         for (; fp; fp = fp->next) {
668                 struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
669
670                 op->next = orig;
671                 op = orig;
672                 NFCT_FRAG6_CB(fp)->orig = NULL;
673         }
674
675         return head;
676
677 out_oversize:
678         if (net_ratelimit())
679                 printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len);
680         goto out_fail;
681 out_oom:
682         if (net_ratelimit())
683                 printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n");
684 out_fail:
685         return NULL;
686 }
687
688 /*
689  * find the header just before Fragment Header.
690  *
691  * if success return 0 and set ...
692  * (*prevhdrp): the value of "Next Header Field" in the header
693  *              just before Fragment Header.
694  * (*prevhoff): the offset of "Next Header Field" in the header
695  *              just before Fragment Header.
696  * (*fhoff)   : the offset of Fragment Header.
697  *
698  * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
699  *
700  */
701 static int
702 find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
703 {
704         u8 nexthdr = skb->nh.ipv6h->nexthdr;
705         u8 prev_nhoff = (u8 *)&skb->nh.ipv6h->nexthdr - skb->data;
706         int start = (u8 *)(skb->nh.ipv6h+1) - skb->data;
707         int len = skb->len - start;
708         u8 prevhdr = NEXTHDR_IPV6;
709
710         while (nexthdr != NEXTHDR_FRAGMENT) {
711                 struct ipv6_opt_hdr hdr;
712                 int hdrlen;
713
714                 if (!ipv6_ext_hdr(nexthdr)) {
715                         return -1;
716                 }
717                 if (len < (int)sizeof(struct ipv6_opt_hdr)) {
718                         DEBUGP("too short\n");
719                         return -1;
720                 }
721                 if (nexthdr == NEXTHDR_NONE) {
722                         DEBUGP("next header is none\n");
723                         return -1;
724                 }
725                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
726                         BUG();
727                 if (nexthdr == NEXTHDR_AUTH)
728                         hdrlen = (hdr.hdrlen+2)<<2;
729                 else
730                         hdrlen = ipv6_optlen(&hdr);
731
732                 prevhdr = nexthdr;
733                 prev_nhoff = start;
734
735                 nexthdr = hdr.nexthdr;
736                 len -= hdrlen;
737                 start += hdrlen;
738         }
739
740         if (len < 0)
741                 return -1;
742
743         *prevhdrp = prevhdr;
744         *prevhoff = prev_nhoff;
745         *fhoff = start;
746
747         return 0;
748 }
749
750 struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
751 {
752         struct sk_buff *clone;
753         struct net_device *dev = skb->dev;
754         struct frag_hdr *fhdr;
755         struct nf_ct_frag6_queue *fq;
756         struct ipv6hdr *hdr;
757         int fhoff, nhoff;
758         u8 prevhdr;
759         struct sk_buff *ret_skb = NULL;
760
761         /* Jumbo payload inhibits frag. header */
762         if (skb->nh.ipv6h->payload_len == 0) {
763                 DEBUGP("payload len = 0\n");
764                 return skb;
765         }
766
767         if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
768                 return skb;
769
770         clone = skb_clone(skb, GFP_ATOMIC);
771         if (clone == NULL) {
772                 DEBUGP("Can't clone skb\n");
773                 return skb;
774         }
775
776         NFCT_FRAG6_CB(clone)->orig = skb;
777
778         if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
779                 DEBUGP("message is too short.\n");
780                 goto ret_orig;
781         }
782
783         clone->h.raw = clone->data + fhoff;
784         hdr = clone->nh.ipv6h;
785         fhdr = (struct frag_hdr *)clone->h.raw;
786
787         if (!(fhdr->frag_off & htons(0xFFF9))) {
788                 DEBUGP("Invalid fragment offset\n");
789                 /* It is not a fragmented frame */
790                 goto ret_orig;
791         }
792
793         if (atomic_read(&nf_ct_frag6_mem) > nf_ct_frag6_high_thresh)
794                 nf_ct_frag6_evictor();
795
796         fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
797         if (fq == NULL) {
798                 DEBUGP("Can't find and can't create new queue\n");
799                 goto ret_orig;
800         }
801
802         spin_lock(&fq->lock);
803
804         if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
805                 spin_unlock(&fq->lock);
806                 DEBUGP("Can't insert skb to queue\n");
807                 fq_put(fq, NULL);
808                 goto ret_orig;
809         }
810
811         if (fq->last_in == (FIRST_IN|LAST_IN) && fq->meat == fq->len) {
812                 ret_skb = nf_ct_frag6_reasm(fq, dev);
813                 if (ret_skb == NULL)
814                         DEBUGP("Can't reassemble fragmented packets\n");
815         }
816         spin_unlock(&fq->lock);
817
818         fq_put(fq, NULL);
819         return ret_skb;
820
821 ret_orig:
822         kfree_skb(clone);
823         return skb;
824 }
825
826 void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
827                         struct net_device *in, struct net_device *out,
828                         int (*okfn)(struct sk_buff *))
829 {
830         struct sk_buff *s, *s2;
831
832         for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
833                 nf_conntrack_put_reasm(s->nfct_reasm);
834                 nf_conntrack_get_reasm(skb);
835                 s->nfct_reasm = skb;
836
837                 s2 = s->next;
838                 s->next = NULL;
839
840                 NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn,
841                                NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
842                 s = s2;
843         }
844         nf_conntrack_put_reasm(skb);
845 }
846
847 int nf_ct_frag6_kfree_frags(struct sk_buff *skb)
848 {
849         struct sk_buff *s, *s2;
850
851         for (s = NFCT_FRAG6_CB(skb)->orig; s; s = s2) {
852
853                 s2 = s->next;
854                 kfree_skb(s);
855         }
856
857         kfree_skb(skb);
858
859         return 0;
860 }
861
862 int nf_ct_frag6_init(void)
863 {
864         nf_ct_frag6_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
865                                    (jiffies ^ (jiffies >> 6)));
866
867         init_timer(&nf_ct_frag6_secret_timer);
868         nf_ct_frag6_secret_timer.function = nf_ct_frag6_secret_rebuild;
869         nf_ct_frag6_secret_timer.expires = jiffies
870                                            + nf_ct_frag6_secret_interval;
871         add_timer(&nf_ct_frag6_secret_timer);
872
873         return 0;
874 }
875
876 void nf_ct_frag6_cleanup(void)
877 {
878         del_timer(&nf_ct_frag6_secret_timer);
879         nf_ct_frag6_low_thresh = 0;
880         nf_ct_frag6_evictor();
881 }