err.no Git - linux-2.6/blob - 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/errno.h>
  32 #include <linux/types.h>
  33 #include <linux/string.h>
  34 #include <linux/socket.h>
  35 #include <linux/sockios.h>
  36 #include <linux/jiffies.h>
  37 #include <linux/net.h>
  38 #include <linux/list.h>
  39 #include <linux/netdevice.h>
  40 #include <linux/in6.h>
  41 #include <linux/ipv6.h>
  42 #include <linux/icmpv6.h>
  43 #include <linux/random.h>
  44 #include <linux/jhash.h>
  45 #include <linux/skbuff.h>
  46
  47 #include <net/sock.h>
  48 #include <net/snmp.h>
  49
  50 #include <net/ipv6.h>
  51 #include <net/ip6_route.h>
  52 #include <net/protocol.h>
  53 #include <net/transp_v6.h>
  54 #include <net/rawv6.h>
  55 #include <net/ndisc.h>
  56 #include <net/addrconf.h>
  57 #include <net/inet_frag.h>
  58
  59 struct ip6frag_skb_cb
  60 {
  61         struct inet6_skb_parm   h;
  62         int                     offset;
  63 };
  64
  65 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  66
  67
  68 /*
  69  *      Equivalent of ipv4 struct ipq
  70  */
  71
  72 struct frag_queue
  73 {
  74         struct inet_frag_queue  q;
  75
  76         __be32                  id;             /* fragment id          */
  77         struct in6_addr         saddr;
  78         struct in6_addr         daddr;
  79
  80         int                     iif;
  81         unsigned int            csum;
  82         __u16                   nhoffset;
  83 };
  84
  85 struct inet_frags_ctl ip6_frags_ctl __read_mostly = {
  86         .high_thresh     = 256 * 1024,
  87         .low_thresh      = 192 * 1024,
  88         .timeout         = IPV6_FRAG_TIMEOUT,
  89         .secret_interval = 10 * 60 * HZ,
  90 };
  91
  92 static struct inet_frags ip6_frags;
  93
  94 int ip6_frag_nqueues(void)
  95 {
  96         return ip6_frags.nqueues;
  97 }
  98
  99 int ip6_frag_mem(void)
 100 {
 101         return atomic_read(&ip6_frags.mem);
 102 }
 103
 104 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 105                           struct net_device *dev);
 106
 107 /*
 108  * callers should be careful not to use the hash value outside the ipfrag_lock
 109  * as doing so could race with ipfrag_hash_rnd being recalculated.
 110  */
 111 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
 112                                struct in6_addr *daddr)
 113 {
 114         u32 a, b, c;
 115
 116         a = (__force u32)saddr->s6_addr32[0];
 117         b = (__force u32)saddr->s6_addr32[1];
 118         c = (__force u32)saddr->s6_addr32[2];
 119
 120         a += JHASH_GOLDEN_RATIO;
 121         b += JHASH_GOLDEN_RATIO;
 122         c += ip6_frags.rnd;
 123         __jhash_mix(a, b, c);
 124
 125         a += (__force u32)saddr->s6_addr32[3];
 126         b += (__force u32)daddr->s6_addr32[0];
 127         c += (__force u32)daddr->s6_addr32[1];
 128         __jhash_mix(a, b, c);
 129
 130         a += (__force u32)daddr->s6_addr32[2];
 131         b += (__force u32)daddr->s6_addr32[3];
 132         c += (__force u32)id;
 133         __jhash_mix(a, b, c);
 134
 135         return c & (INETFRAGS_HASHSZ - 1);
 136 }
 137
 138 static unsigned int ip6_hashfn(struct inet_frag_queue *q)
 139 {
 140         struct frag_queue *fq;
 141
 142         fq = container_of(q, struct frag_queue, q);
 143         return ip6qhashfn(fq->id, &fq->saddr, &fq->daddr);
 144 }
 145
 146 int ip6_frag_equal(struct inet_frag_queue *q1, struct inet_frag_queue *q2)
 147 {
 148         struct frag_queue *fq1, *fq2;
 149
 150         fq1 = container_of(q1, struct frag_queue, q);
 151         fq2 = container_of(q2, struct frag_queue, q);
 152         return (fq1->id == fq2->id &&
 153                         ipv6_addr_equal(&fq2->saddr, &fq1->saddr) &&
 154                         ipv6_addr_equal(&fq2->daddr, &fq1->daddr));
 155 }
 156 EXPORT_SYMBOL(ip6_frag_equal);
 157
 158 /* Memory Tracking Functions. */
 159 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 160 {
 161         if (work)
 162                 *work -= skb->truesize;
 163         atomic_sub(skb->truesize, &ip6_frags.mem);
 164         kfree_skb(skb);
 165 }
 166
 167 static void ip6_frag_free(struct inet_frag_queue *fq)
 168 {
 169         kfree(container_of(fq, struct frag_queue, q));
 170 }
 171
 172 static inline struct frag_queue *frag_alloc_queue(void)
 173 {
 174         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 175
 176         if(!fq)
 177                 return NULL;
 178         atomic_add(sizeof(struct frag_queue), &ip6_frags.mem);
 179         return fq;
 180 }
 181
 182 /* Destruction primitives. */
 183
 184 static __inline__ void fq_put(struct frag_queue *fq)
 185 {
 186         inet_frag_put(&fq->q, &ip6_frags);
 187 }
 188
 189 /* Kill fq entry. It is not destroyed immediately,
 190  * because caller (and someone more) holds reference count.
 191  */
 192 static __inline__ void fq_kill(struct frag_queue *fq)
 193 {
 194         inet_frag_kill(&fq->q, &ip6_frags);
 195 }
 196
 197 static void ip6_evictor(struct inet6_dev *idev)
 198 {
 199         int evicted;
 200
 201         evicted = inet_frag_evictor(&ip6_frags);
 202         if (evicted)
 203                 IP6_ADD_STATS_BH(idev, IPSTATS_MIB_REASMFAILS, evicted);
 204 }
 205
 206 static void ip6_frag_expire(unsigned long data)
 207 {
 208         struct frag_queue *fq = (struct frag_queue *) data;
 209         struct net_device *dev = NULL;
 210
 211         spin_lock(&fq->q.lock);
 212
 213         if (fq->q.last_in & COMPLETE)
 214                 goto out;
 215
 216         fq_kill(fq);
 217
 218         dev = dev_get_by_index(&init_net, fq->iif);
 219         if (!dev)
 220                 goto out;
 221
 222         rcu_read_lock();
 223         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 224         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 225         rcu_read_unlock();
 226
 227         /* Don't send error if the first segment did not arrive. */
 228         if (!(fq->q.last_in&FIRST_IN) || !fq->q.fragments)
 229                 goto out;
 230
 231         /*
 232            But use as source device on which LAST ARRIVED
 233            segment was received. And do not use fq->dev
 234            pointer directly, device might already disappeared.
 235          */
 236         fq->q.fragments->dev = dev;
 237         icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 238 out:
 239         if (dev)
 240                 dev_put(dev);
 241         spin_unlock(&fq->q.lock);
 242         fq_put(fq);
 243 }
 244
 245 /* Creation primitives. */
 246
 247
 248 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in,
 249                 unsigned int hash)
 250 {
 251         struct inet_frag_queue *q;
 252
 253         q = inet_frag_intern(&fq_in->q, &ip6_frags, hash);
 254         return container_of(q, struct frag_queue, q);
 255 }
 256
 257
 258 static struct frag_queue *
 259 ip6_frag_create(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 260                 struct inet6_dev *idev, unsigned int hash)
 261 {
 262         struct frag_queue *fq;
 263
 264         if ((fq = frag_alloc_queue()) == NULL)
 265                 goto oom;
 266
 267         fq->id = id;
 268         ipv6_addr_copy(&fq->saddr, src);
 269         ipv6_addr_copy(&fq->daddr, dst);
 270
 271         init_timer(&fq->q.timer);
 272         fq->q.timer.function = ip6_frag_expire;
 273         fq->q.timer.data = (long) fq;
 274         spin_lock_init(&fq->q.lock);
 275         atomic_set(&fq->q.refcnt, 1);
 276
 277         return ip6_frag_intern(fq, hash);
 278
 279 oom:
 280         IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 281         return NULL;
 282 }
 283
 284 static __inline__ struct frag_queue *
 285 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 286         struct inet6_dev *idev)
 287 {
 288         struct frag_queue *fq;
 289         struct hlist_node *n;
 290         unsigned int hash;
 291
 292         read_lock(&ip6_frags.lock);
 293         hash = ip6qhashfn(id, src, dst);
 294         hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
 295                 if (fq->id == id &&
 296                     ipv6_addr_equal(src, &fq->saddr) &&
 297                     ipv6_addr_equal(dst, &fq->daddr)) {
 298                         atomic_inc(&fq->q.refcnt);
 299                         read_unlock(&ip6_frags.lock);
 300                         return fq;
 301                 }
 302         }
 303         read_unlock(&ip6_frags.lock);
 304
 305         return ip6_frag_create(id, src, dst, idev, hash);
 306 }
 307
 308
 309 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 310                            struct frag_hdr *fhdr, int nhoff)
 311 {
 312         struct sk_buff *prev, *next;
 313         struct net_device *dev;
 314         int offset, end;
 315
 316         if (fq->q.last_in & COMPLETE)
 317                 goto err;
 318
 319         offset = ntohs(fhdr->frag_off) & ~0x7;
 320         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 321                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 322
 323         if ((unsigned int)end > IPV6_MAXPLEN) {
 324                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 325                                  IPSTATS_MIB_INHDRERRORS);
 326                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 327                                   ((u8 *)&fhdr->frag_off -
 328                                    skb_network_header(skb)));
 329                 return -1;
 330         }
 331
 332         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 333                 const unsigned char *nh = skb_network_header(skb);
 334                 skb->csum = csum_sub(skb->csum,
 335                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 336                                                   0));
 337         }
 338
 339         /* Is this the final fragment? */
 340         if (!(fhdr->frag_off & htons(IP6_MF))) {
 341                 /* If we already have some bits beyond end
 342                  * or have different end, the segment is corrupted.
 343                  */
 344                 if (end < fq->q.len ||
 345                     ((fq->q.last_in & LAST_IN) && end != fq->q.len))
 346                         goto err;
 347                 fq->q.last_in |= LAST_IN;
 348                 fq->q.len = end;
 349         } else {
 350                 /* Check if the fragment is rounded to 8 bytes.
 351                  * Required by the RFC.
 352                  */
 353                 if (end & 0x7) {
 354                         /* RFC2460 says always send parameter problem in
 355                          * this case. -DaveM
 356                          */
 357                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 358                                          IPSTATS_MIB_INHDRERRORS);
 359                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 360                                           offsetof(struct ipv6hdr, payload_len));
 361                         return -1;
 362                 }
 363                 if (end > fq->q.len) {
 364                         /* Some bits beyond end -> corruption. */
 365                         if (fq->q.last_in & LAST_IN)
 366                                 goto err;
 367                         fq->q.len = end;
 368                 }
 369         }
 370
 371         if (end == offset)
 372                 goto err;
 373
 374         /* Point into the IP datagram 'data' part. */
 375         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 376                 goto err;
 377
 378         if (pskb_trim_rcsum(skb, end - offset))
 379                 goto err;
 380
 381         /* Find out which fragments are in front and at the back of us
 382          * in the chain of fragments so far.  We must know where to put
 383          * this fragment, right?
 384          */
 385         prev = NULL;
 386         for(next = fq->q.fragments; next != NULL; next = next->next) {
 387                 if (FRAG6_CB(next)->offset >= offset)
 388                         break;  /* bingo! */
 389                 prev = next;
 390         }
 391
 392         /* We found where to put this one.  Check for overlap with
 393          * preceding fragment, and, if needed, align things so that
 394          * any overlaps are eliminated.
 395          */
 396         if (prev) {
 397                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 398
 399                 if (i > 0) {
 400                         offset += i;
 401                         if (end <= offset)
 402                                 goto err;
 403                         if (!pskb_pull(skb, i))
 404                                 goto err;
 405                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 406                                 skb->ip_summed = CHECKSUM_NONE;
 407                 }
 408         }
 409
 410         /* Look for overlap with succeeding segments.
 411          * If we can merge fragments, do it.
 412          */
 413         while (next && FRAG6_CB(next)->offset < end) {
 414                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 415
 416                 if (i < next->len) {
 417                         /* Eat head of the next overlapped fragment
 418                          * and leave the loop. The next ones cannot overlap.
 419                          */
 420                         if (!pskb_pull(next, i))
 421                                 goto err;
 422                         FRAG6_CB(next)->offset += i;    /* next fragment */
 423                         fq->q.meat -= i;
 424                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 425                                 next->ip_summed = CHECKSUM_NONE;
 426                         break;
 427                 } else {
 428                         struct sk_buff *free_it = next;
 429
 430                         /* Old fragment is completely overridden with
 431                          * new one drop it.
 432                          */
 433                         next = next->next;
 434
 435                         if (prev)
 436                                 prev->next = next;
 437                         else
 438                                 fq->q.fragments = next;
 439
 440                         fq->q.meat -= free_it->len;
 441                         frag_kfree_skb(free_it, NULL);
 442                 }
 443         }
 444
 445         FRAG6_CB(skb)->offset = offset;
 446
 447         /* Insert this fragment in the chain of fragments. */
 448         skb->next = next;
 449         if (prev)
 450                 prev->next = skb;
 451         else
 452                 fq->q.fragments = skb;
 453
 454         dev = skb->dev;
 455         if (dev) {
 456                 fq->iif = dev->ifindex;
 457                 skb->dev = NULL;
 458         }
 459         fq->q.stamp = skb->tstamp;
 460         fq->q.meat += skb->len;
 461         atomic_add(skb->truesize, &ip6_frags.mem);
 462
 463         /* The first fragment.
 464          * nhoffset is obtained from the first fragment, of course.
 465          */
 466         if (offset == 0) {
 467                 fq->nhoffset = nhoff;
 468                 fq->q.last_in |= FIRST_IN;
 469         }
 470
 471         if (fq->q.last_in == (FIRST_IN | LAST_IN) && fq->q.meat == fq->q.len)
 472                 return ip6_frag_reasm(fq, prev, dev);
 473
 474         write_lock(&ip6_frags.lock);
 475         list_move_tail(&fq->q.lru_list, &ip6_frags.lru_list);
 476         write_unlock(&ip6_frags.lock);
 477         return -1;
 478
 479 err:
 480         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 481         kfree_skb(skb);
 482         return -1;
 483 }
 484
 485 /*
 486  *      Check if this packet is complete.
 487  *      Returns NULL on failure by any reason, and pointer
 488  *      to current nexthdr field in reassembled frame.
 489  *
 490  *      It is called with locked fq, and caller must check that
 491  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 492  *      the last and the first frames arrived and all the bits are here.
 493  */
 494 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 495                           struct net_device *dev)
 496 {
 497         struct sk_buff *fp, *head = fq->q.fragments;
 498         int    payload_len;
 499         unsigned int nhoff;
 500
 501         fq_kill(fq);
 502
 503         /* Make the one we just received the head. */
 504         if (prev) {
 505                 head = prev->next;
 506                 fp = skb_clone(head, GFP_ATOMIC);
 507
 508                 if (!fp)
 509                         goto out_oom;
 510
 511                 fp->next = head->next;
 512                 prev->next = fp;
 513
 514                 skb_morph(head, fq->q.fragments);
 515                 head->next = fq->q.fragments->next;
 516
 517                 kfree_skb(fq->q.fragments);
 518                 fq->q.fragments = head;
 519         }
 520
 521         BUG_TRAP(head != NULL);
 522         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 523
 524         /* Unfragmented part is taken from the first segment. */
 525         payload_len = ((head->data - skb_network_header(head)) -
 526                        sizeof(struct ipv6hdr) + fq->q.len -
 527                        sizeof(struct frag_hdr));
 528         if (payload_len > IPV6_MAXPLEN)
 529                 goto out_oversize;
 530
 531         /* Head of list must not be cloned. */
 532         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 533                 goto out_oom;
 534
 535         /* If the first fragment is fragmented itself, we split
 536          * it to two chunks: the first with data and paged part
 537          * and the second, holding only fragments. */
 538         if (skb_shinfo(head)->frag_list) {
 539                 struct sk_buff *clone;
 540                 int i, plen = 0;
 541
 542                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 543                         goto out_oom;
 544                 clone->next = head->next;
 545                 head->next = clone;
 546                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 547                 skb_shinfo(head)->frag_list = NULL;
 548                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 549                         plen += skb_shinfo(head)->frags[i].size;
 550                 clone->len = clone->data_len = head->data_len - plen;
 551                 head->data_len -= clone->len;
 552                 head->len -= clone->len;
 553                 clone->csum = 0;
 554                 clone->ip_summed = head->ip_summed;
 555                 atomic_add(clone->truesize, &ip6_frags.mem);
 556         }
 557
 558         /* We have to remove fragment header from datagram and to relocate
 559          * header in order to calculate ICV correctly. */
 560         nhoff = fq->nhoffset;
 561         skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
 562         memmove(head->head + sizeof(struct frag_hdr), head->head,
 563                 (head->data - head->head) - sizeof(struct frag_hdr));
 564         head->mac_header += sizeof(struct frag_hdr);
 565         head->network_header += sizeof(struct frag_hdr);
 566
 567         skb_shinfo(head)->frag_list = head->next;
 568         skb_reset_transport_header(head);
 569         skb_push(head, head->data - skb_network_header(head));
 570         atomic_sub(head->truesize, &ip6_frags.mem);
 571
 572         for (fp=head->next; fp; fp = fp->next) {
 573                 head->data_len += fp->len;
 574                 head->len += fp->len;
 575                 if (head->ip_summed != fp->ip_summed)
 576                         head->ip_summed = CHECKSUM_NONE;
 577                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 578                         head->csum = csum_add(head->csum, fp->csum);
 579                 head->truesize += fp->truesize;
 580                 atomic_sub(fp->truesize, &ip6_frags.mem);
 581         }
 582
 583         head->next = NULL;
 584         head->dev = dev;
 585         head->tstamp = fq->q.stamp;
 586         ipv6_hdr(head)->payload_len = htons(payload_len);
 587         IP6CB(head)->nhoff = nhoff;
 588
 589         /* Yes, and fold redundant checksum back. 8) */
 590         if (head->ip_summed == CHECKSUM_COMPLETE)
 591                 head->csum = csum_partial(skb_network_header(head),
 592                                           skb_network_header_len(head),
 593                                           head->csum);
 594
 595         rcu_read_lock();
 596         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 597         rcu_read_unlock();
 598         fq->q.fragments = NULL;
 599         return 1;
 600
 601 out_oversize:
 602         if (net_ratelimit())
 603                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 604         goto out_fail;
 605 out_oom:
 606         if (net_ratelimit())
 607                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 608 out_fail:
 609         rcu_read_lock();
 610         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 611         rcu_read_unlock();
 612         return -1;
 613 }
 614
 615 static int ipv6_frag_rcv(struct sk_buff *skb)
 616 {
 617         struct frag_hdr *fhdr;
 618         struct frag_queue *fq;
 619         struct ipv6hdr *hdr = ipv6_hdr(skb);
 620
 621         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMREQDS);
 622
 623         /* Jumbo payload inhibits frag. header */
 624         if (hdr->payload_len==0) {
 625                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 626                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 627                                   skb_network_header_len(skb));
 628                 return -1;
 629         }
 630         if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
 631                                  sizeof(struct frag_hdr)))) {
 632                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 633                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 634                                   skb_network_header_len(skb));
 635                 return -1;
 636         }
 637
 638         hdr = ipv6_hdr(skb);
 639         fhdr = (struct frag_hdr *)skb_transport_header(skb);
 640
 641         if (!(fhdr->frag_off & htons(0xFFF9))) {
 642                 /* It is not a fragmented frame */
 643                 skb->transport_header += sizeof(struct frag_hdr);
 644                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMOKS);
 645
 646                 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
 647                 return 1;
 648         }
 649
 650         if (atomic_read(&ip6_frags.mem) > ip6_frags_ctl.high_thresh)
 651                 ip6_evictor(ip6_dst_idev(skb->dst));
 652
 653         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr,
 654                           ip6_dst_idev(skb->dst))) != NULL) {
 655                 int ret;
 656
 657                 spin_lock(&fq->q.lock);
 658
 659                 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 660
 661                 spin_unlock(&fq->q.lock);
 662                 fq_put(fq);
 663                 return ret;
 664         }
 665
 666         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 667         kfree_skb(skb);
 668         return -1;
 669 }
 670
 671 static struct inet6_protocol frag_protocol =
 672 {
 673         .handler        =       ipv6_frag_rcv,
 674         .flags          =       INET6_PROTO_NOPOLICY,
 675 };
 676
 677 void __init ipv6_frag_init(void)
 678 {
 679         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 680                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 681
 682         ip6_frags.ctl = &ip6_frags_ctl;
 683         ip6_frags.hashfn = ip6_hashfn;
 684         ip6_frags.destructor = ip6_frag_free;
 685         ip6_frags.skb_free = NULL;
 686         ip6_frags.qsize = sizeof(struct frag_queue);
 687         ip6_frags.equal = ip6_frag_equal;
 688         inet_frags_init(&ip6_frags);
 689 }