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   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 /* Memory Tracking Functions. */
 147 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 148 {
 149         if (work)
 150                 *work -= skb->truesize;
 151         atomic_sub(skb->truesize, &ip6_frags.mem);
 152         kfree_skb(skb);
 153 }
 154
 155 static void ip6_frag_free(struct inet_frag_queue *fq)
 156 {
 157         kfree(container_of(fq, struct frag_queue, q));
 158 }
 159
 160 static inline struct frag_queue *frag_alloc_queue(void)
 161 {
 162         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 163
 164         if(!fq)
 165                 return NULL;
 166         atomic_add(sizeof(struct frag_queue), &ip6_frags.mem);
 167         return fq;
 168 }
 169
 170 /* Destruction primitives. */
 171
 172 static __inline__ void fq_put(struct frag_queue *fq)
 173 {
 174         inet_frag_put(&fq->q, &ip6_frags);
 175 }
 176
 177 /* Kill fq entry. It is not destroyed immediately,
 178  * because caller (and someone more) holds reference count.
 179  */
 180 static __inline__ void fq_kill(struct frag_queue *fq)
 181 {
 182         inet_frag_kill(&fq->q, &ip6_frags);
 183 }
 184
 185 static void ip6_evictor(struct inet6_dev *idev)
 186 {
 187         int evicted;
 188
 189         evicted = inet_frag_evictor(&ip6_frags);
 190         if (evicted)
 191                 IP6_ADD_STATS_BH(idev, IPSTATS_MIB_REASMFAILS, evicted);
 192 }
 193
 194 static void ip6_frag_expire(unsigned long data)
 195 {
 196         struct frag_queue *fq = (struct frag_queue *) data;
 197         struct net_device *dev = NULL;
 198
 199         spin_lock(&fq->q.lock);
 200
 201         if (fq->q.last_in & COMPLETE)
 202                 goto out;
 203
 204         fq_kill(fq);
 205
 206         dev = dev_get_by_index(&init_net, fq->iif);
 207         if (!dev)
 208                 goto out;
 209
 210         rcu_read_lock();
 211         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 212         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 213         rcu_read_unlock();
 214
 215         /* Don't send error if the first segment did not arrive. */
 216         if (!(fq->q.last_in&FIRST_IN) || !fq->q.fragments)
 217                 goto out;
 218
 219         /*
 220            But use as source device on which LAST ARRIVED
 221            segment was received. And do not use fq->dev
 222            pointer directly, device might already disappeared.
 223          */
 224         fq->q.fragments->dev = dev;
 225         icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 226 out:
 227         if (dev)
 228                 dev_put(dev);
 229         spin_unlock(&fq->q.lock);
 230         fq_put(fq);
 231 }
 232
 233 /* Creation primitives. */
 234
 235
 236 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
 237 {
 238         struct frag_queue *fq;
 239         unsigned int hash;
 240 #ifdef CONFIG_SMP
 241         struct hlist_node *n;
 242 #endif
 243
 244         write_lock(&ip6_frags.lock);
 245         hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
 246 #ifdef CONFIG_SMP
 247         hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
 248                 if (fq->id == fq_in->id &&
 249                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 250                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 251                         atomic_inc(&fq->q.refcnt);
 252                         write_unlock(&ip6_frags.lock);
 253                         fq_in->q.last_in |= COMPLETE;
 254                         fq_put(fq_in);
 255                         return fq;
 256                 }
 257         }
 258 #endif
 259         fq = fq_in;
 260
 261         if (!mod_timer(&fq->q.timer, jiffies + ip6_frags_ctl.timeout))
 262                 atomic_inc(&fq->q.refcnt);
 263
 264         atomic_inc(&fq->q.refcnt);
 265         hlist_add_head(&fq->q.list, &ip6_frags.hash[hash]);
 266         INIT_LIST_HEAD(&fq->q.lru_list);
 267         list_add_tail(&fq->q.lru_list, &ip6_frags.lru_list);
 268         ip6_frags.nqueues++;
 269         write_unlock(&ip6_frags.lock);
 270         return fq;
 271 }
 272
 273
 274 static struct frag_queue *
 275 ip6_frag_create(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 276                 struct inet6_dev *idev)
 277 {
 278         struct frag_queue *fq;
 279
 280         if ((fq = frag_alloc_queue()) == NULL)
 281                 goto oom;
 282
 283         fq->id = id;
 284         ipv6_addr_copy(&fq->saddr, src);
 285         ipv6_addr_copy(&fq->daddr, dst);
 286
 287         init_timer(&fq->q.timer);
 288         fq->q.timer.function = ip6_frag_expire;
 289         fq->q.timer.data = (long) fq;
 290         spin_lock_init(&fq->q.lock);
 291         atomic_set(&fq->q.refcnt, 1);
 292
 293         return ip6_frag_intern(fq);
 294
 295 oom:
 296         IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 297         return NULL;
 298 }
 299
 300 static __inline__ struct frag_queue *
 301 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 302         struct inet6_dev *idev)
 303 {
 304         struct frag_queue *fq;
 305         struct hlist_node *n;
 306         unsigned int hash;
 307
 308         read_lock(&ip6_frags.lock);
 309         hash = ip6qhashfn(id, src, dst);
 310         hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
 311                 if (fq->id == id &&
 312                     ipv6_addr_equal(src, &fq->saddr) &&
 313                     ipv6_addr_equal(dst, &fq->daddr)) {
 314                         atomic_inc(&fq->q.refcnt);
 315                         read_unlock(&ip6_frags.lock);
 316                         return fq;
 317                 }
 318         }
 319         read_unlock(&ip6_frags.lock);
 320
 321         return ip6_frag_create(id, src, dst, idev);
 322 }
 323
 324
 325 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 326                            struct frag_hdr *fhdr, int nhoff)
 327 {
 328         struct sk_buff *prev, *next;
 329         struct net_device *dev;
 330         int offset, end;
 331
 332         if (fq->q.last_in & COMPLETE)
 333                 goto err;
 334
 335         offset = ntohs(fhdr->frag_off) & ~0x7;
 336         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 337                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 338
 339         if ((unsigned int)end > IPV6_MAXPLEN) {
 340                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 341                                  IPSTATS_MIB_INHDRERRORS);
 342                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 343                                   ((u8 *)&fhdr->frag_off -
 344                                    skb_network_header(skb)));
 345                 return -1;
 346         }
 347
 348         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 349                 const unsigned char *nh = skb_network_header(skb);
 350                 skb->csum = csum_sub(skb->csum,
 351                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 352                                                   0));
 353         }
 354
 355         /* Is this the final fragment? */
 356         if (!(fhdr->frag_off & htons(IP6_MF))) {
 357                 /* If we already have some bits beyond end
 358                  * or have different end, the segment is corrupted.
 359                  */
 360                 if (end < fq->q.len ||
 361                     ((fq->q.last_in & LAST_IN) && end != fq->q.len))
 362                         goto err;
 363                 fq->q.last_in |= LAST_IN;
 364                 fq->q.len = end;
 365         } else {
 366                 /* Check if the fragment is rounded to 8 bytes.
 367                  * Required by the RFC.
 368                  */
 369                 if (end & 0x7) {
 370                         /* RFC2460 says always send parameter problem in
 371                          * this case. -DaveM
 372                          */
 373                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 374                                          IPSTATS_MIB_INHDRERRORS);
 375                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 376                                           offsetof(struct ipv6hdr, payload_len));
 377                         return -1;
 378                 }
 379                 if (end > fq->q.len) {
 380                         /* Some bits beyond end -> corruption. */
 381                         if (fq->q.last_in & LAST_IN)
 382                                 goto err;
 383                         fq->q.len = end;
 384                 }
 385         }
 386
 387         if (end == offset)
 388                 goto err;
 389
 390         /* Point into the IP datagram 'data' part. */
 391         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 392                 goto err;
 393
 394         if (pskb_trim_rcsum(skb, end - offset))
 395                 goto err;
 396
 397         /* Find out which fragments are in front and at the back of us
 398          * in the chain of fragments so far.  We must know where to put
 399          * this fragment, right?
 400          */
 401         prev = NULL;
 402         for(next = fq->q.fragments; next != NULL; next = next->next) {
 403                 if (FRAG6_CB(next)->offset >= offset)
 404                         break;  /* bingo! */
 405                 prev = next;
 406         }
 407
 408         /* We found where to put this one.  Check for overlap with
 409          * preceding fragment, and, if needed, align things so that
 410          * any overlaps are eliminated.
 411          */
 412         if (prev) {
 413                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 414
 415                 if (i > 0) {
 416                         offset += i;
 417                         if (end <= offset)
 418                                 goto err;
 419                         if (!pskb_pull(skb, i))
 420                                 goto err;
 421                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 422                                 skb->ip_summed = CHECKSUM_NONE;
 423                 }
 424         }
 425
 426         /* Look for overlap with succeeding segments.
 427          * If we can merge fragments, do it.
 428          */
 429         while (next && FRAG6_CB(next)->offset < end) {
 430                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 431
 432                 if (i < next->len) {
 433                         /* Eat head of the next overlapped fragment
 434                          * and leave the loop. The next ones cannot overlap.
 435                          */
 436                         if (!pskb_pull(next, i))
 437                                 goto err;
 438                         FRAG6_CB(next)->offset += i;    /* next fragment */
 439                         fq->q.meat -= i;
 440                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 441                                 next->ip_summed = CHECKSUM_NONE;
 442                         break;
 443                 } else {
 444                         struct sk_buff *free_it = next;
 445
 446                         /* Old fragment is completely overridden with
 447                          * new one drop it.
 448                          */
 449                         next = next->next;
 450
 451                         if (prev)
 452                                 prev->next = next;
 453                         else
 454                                 fq->q.fragments = next;
 455
 456                         fq->q.meat -= free_it->len;
 457                         frag_kfree_skb(free_it, NULL);
 458                 }
 459         }
 460
 461         FRAG6_CB(skb)->offset = offset;
 462
 463         /* Insert this fragment in the chain of fragments. */
 464         skb->next = next;
 465         if (prev)
 466                 prev->next = skb;
 467         else
 468                 fq->q.fragments = skb;
 469
 470         dev = skb->dev;
 471         if (dev) {
 472                 fq->iif = dev->ifindex;
 473                 skb->dev = NULL;
 474         }
 475         fq->q.stamp = skb->tstamp;
 476         fq->q.meat += skb->len;
 477         atomic_add(skb->truesize, &ip6_frags.mem);
 478
 479         /* The first fragment.
 480          * nhoffset is obtained from the first fragment, of course.
 481          */
 482         if (offset == 0) {
 483                 fq->nhoffset = nhoff;
 484                 fq->q.last_in |= FIRST_IN;
 485         }
 486
 487         if (fq->q.last_in == (FIRST_IN | LAST_IN) && fq->q.meat == fq->q.len)
 488                 return ip6_frag_reasm(fq, prev, dev);
 489
 490         write_lock(&ip6_frags.lock);
 491         list_move_tail(&fq->q.lru_list, &ip6_frags.lru_list);
 492         write_unlock(&ip6_frags.lock);
 493         return -1;
 494
 495 err:
 496         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 497         kfree_skb(skb);
 498         return -1;
 499 }
 500
 501 /*
 502  *      Check if this packet is complete.
 503  *      Returns NULL on failure by any reason, and pointer
 504  *      to current nexthdr field in reassembled frame.
 505  *
 506  *      It is called with locked fq, and caller must check that
 507  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 508  *      the last and the first frames arrived and all the bits are here.
 509  */
 510 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 511                           struct net_device *dev)
 512 {
 513         struct sk_buff *fp, *head = fq->q.fragments;
 514         int    payload_len;
 515         unsigned int nhoff;
 516
 517         fq_kill(fq);
 518
 519         /* Make the one we just received the head. */
 520         if (prev) {
 521                 head = prev->next;
 522                 fp = skb_clone(head, GFP_ATOMIC);
 523
 524                 if (!fp)
 525                         goto out_oom;
 526
 527                 fp->next = head->next;
 528                 prev->next = fp;
 529
 530                 skb_morph(head, fq->q.fragments);
 531                 head->next = fq->q.fragments->next;
 532
 533                 kfree_skb(fq->q.fragments);
 534                 fq->q.fragments = head;
 535         }
 536
 537         BUG_TRAP(head != NULL);
 538         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 539
 540         /* Unfragmented part is taken from the first segment. */
 541         payload_len = ((head->data - skb_network_header(head)) -
 542                        sizeof(struct ipv6hdr) + fq->q.len -
 543                        sizeof(struct frag_hdr));
 544         if (payload_len > IPV6_MAXPLEN)
 545                 goto out_oversize;
 546
 547         /* Head of list must not be cloned. */
 548         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 549                 goto out_oom;
 550
 551         /* If the first fragment is fragmented itself, we split
 552          * it to two chunks: the first with data and paged part
 553          * and the second, holding only fragments. */
 554         if (skb_shinfo(head)->frag_list) {
 555                 struct sk_buff *clone;
 556                 int i, plen = 0;
 557
 558                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 559                         goto out_oom;
 560                 clone->next = head->next;
 561                 head->next = clone;
 562                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 563                 skb_shinfo(head)->frag_list = NULL;
 564                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 565                         plen += skb_shinfo(head)->frags[i].size;
 566                 clone->len = clone->data_len = head->data_len - plen;
 567                 head->data_len -= clone->len;
 568                 head->len -= clone->len;
 569                 clone->csum = 0;
 570                 clone->ip_summed = head->ip_summed;
 571                 atomic_add(clone->truesize, &ip6_frags.mem);
 572         }
 573
 574         /* We have to remove fragment header from datagram and to relocate
 575          * header in order to calculate ICV correctly. */
 576         nhoff = fq->nhoffset;
 577         skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
 578         memmove(head->head + sizeof(struct frag_hdr), head->head,
 579                 (head->data - head->head) - sizeof(struct frag_hdr));
 580         head->mac_header += sizeof(struct frag_hdr);
 581         head->network_header += sizeof(struct frag_hdr);
 582
 583         skb_shinfo(head)->frag_list = head->next;
 584         skb_reset_transport_header(head);
 585         skb_push(head, head->data - skb_network_header(head));
 586         atomic_sub(head->truesize, &ip6_frags.mem);
 587
 588         for (fp=head->next; fp; fp = fp->next) {
 589                 head->data_len += fp->len;
 590                 head->len += fp->len;
 591                 if (head->ip_summed != fp->ip_summed)
 592                         head->ip_summed = CHECKSUM_NONE;
 593                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 594                         head->csum = csum_add(head->csum, fp->csum);
 595                 head->truesize += fp->truesize;
 596                 atomic_sub(fp->truesize, &ip6_frags.mem);
 597         }
 598
 599         head->next = NULL;
 600         head->dev = dev;
 601         head->tstamp = fq->q.stamp;
 602         ipv6_hdr(head)->payload_len = htons(payload_len);
 603         IP6CB(head)->nhoff = nhoff;
 604
 605         /* Yes, and fold redundant checksum back. 8) */
 606         if (head->ip_summed == CHECKSUM_COMPLETE)
 607                 head->csum = csum_partial(skb_network_header(head),
 608                                           skb_network_header_len(head),
 609                                           head->csum);
 610
 611         rcu_read_lock();
 612         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 613         rcu_read_unlock();
 614         fq->q.fragments = NULL;
 615         return 1;
 616
 617 out_oversize:
 618         if (net_ratelimit())
 619                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 620         goto out_fail;
 621 out_oom:
 622         if (net_ratelimit())
 623                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 624 out_fail:
 625         rcu_read_lock();
 626         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 627         rcu_read_unlock();
 628         return -1;
 629 }
 630
 631 static int ipv6_frag_rcv(struct sk_buff *skb)
 632 {
 633         struct frag_hdr *fhdr;
 634         struct frag_queue *fq;
 635         struct ipv6hdr *hdr = ipv6_hdr(skb);
 636
 637         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMREQDS);
 638
 639         /* Jumbo payload inhibits frag. header */
 640         if (hdr->payload_len==0) {
 641                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 642                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 643                                   skb_network_header_len(skb));
 644                 return -1;
 645         }
 646         if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
 647                                  sizeof(struct frag_hdr)))) {
 648                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 649                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 650                                   skb_network_header_len(skb));
 651                 return -1;
 652         }
 653
 654         hdr = ipv6_hdr(skb);
 655         fhdr = (struct frag_hdr *)skb_transport_header(skb);
 656
 657         if (!(fhdr->frag_off & htons(0xFFF9))) {
 658                 /* It is not a fragmented frame */
 659                 skb->transport_header += sizeof(struct frag_hdr);
 660                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMOKS);
 661
 662                 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
 663                 return 1;
 664         }
 665
 666         if (atomic_read(&ip6_frags.mem) > ip6_frags_ctl.high_thresh)
 667                 ip6_evictor(ip6_dst_idev(skb->dst));
 668
 669         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr,
 670                           ip6_dst_idev(skb->dst))) != NULL) {
 671                 int ret;
 672
 673                 spin_lock(&fq->q.lock);
 674
 675                 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 676
 677                 spin_unlock(&fq->q.lock);
 678                 fq_put(fq);
 679                 return ret;
 680         }
 681
 682         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 683         kfree_skb(skb);
 684         return -1;
 685 }
 686
 687 static struct inet6_protocol frag_protocol =
 688 {
 689         .handler        =       ipv6_frag_rcv,
 690         .flags          =       INET6_PROTO_NOPOLICY,
 691 };
 692
 693 void __init ipv6_frag_init(void)
 694 {
 695         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 696                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 697
 698         ip6_frags.ctl = &ip6_frags_ctl;
 699         ip6_frags.hashfn = ip6_hashfn;
 700         ip6_frags.destructor = ip6_frag_free;
 701         ip6_frags.skb_free = NULL;
 702         ip6_frags.qsize = sizeof(struct frag_queue);
 703         inet_frags_init(&ip6_frags);
 704 }