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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
  58 int sysctl_ip6frag_high_thresh __read_mostly = 256*1024;
  59 int sysctl_ip6frag_low_thresh __read_mostly = 192*1024;
  60
  61 int sysctl_ip6frag_time __read_mostly = IPV6_FRAG_TIMEOUT;
  62
  63 struct ip6frag_skb_cb
  64 {
  65         struct inet6_skb_parm   h;
  66         int                     offset;
  67 };
  68
  69 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  70
  71
  72 /*
  73  *      Equivalent of ipv4 struct ipq
  74  */
  75
  76 struct frag_queue
  77 {
  78         struct hlist_node       list;
  79         struct list_head lru_list;              /* lru list member      */
  80
  81         __be32                  id;             /* fragment id          */
  82         struct in6_addr         saddr;
  83         struct in6_addr         daddr;
  84
  85         spinlock_t              lock;
  86         atomic_t                refcnt;
  87         struct timer_list       timer;          /* expire timer         */
  88         struct sk_buff          *fragments;
  89         int                     len;
  90         int                     meat;
  91         int                     iif;
  92         ktime_t                 stamp;
  93         unsigned int            csum;
  94         __u8                    last_in;        /* has first/last segment arrived? */
  95 #define COMPLETE                4
  96 #define FIRST_IN                2
  97 #define LAST_IN                 1
  98         __u16                   nhoffset;
  99 };
 100
 101 /* Hash table. */
 102
 103 #define IP6Q_HASHSZ     64
 104
 105 static struct hlist_head ip6_frag_hash[IP6Q_HASHSZ];
 106 static DEFINE_RWLOCK(ip6_frag_lock);
 107 static u32 ip6_frag_hash_rnd;
 108 static LIST_HEAD(ip6_frag_lru_list);
 109 int ip6_frag_nqueues = 0;
 110
 111 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 112                           struct net_device *dev);
 113
 114 static __inline__ void __fq_unlink(struct frag_queue *fq)
 115 {
 116         hlist_del(&fq->list);
 117         list_del(&fq->lru_list);
 118         ip6_frag_nqueues--;
 119 }
 120
 121 static __inline__ void fq_unlink(struct frag_queue *fq)
 122 {
 123         write_lock(&ip6_frag_lock);
 124         __fq_unlink(fq);
 125         write_unlock(&ip6_frag_lock);
 126 }
 127
 128 /*
 129  * callers should be careful not to use the hash value outside the ipfrag_lock
 130  * as doing so could race with ipfrag_hash_rnd being recalculated.
 131  */
 132 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
 133                                struct in6_addr *daddr)
 134 {
 135         u32 a, b, c;
 136
 137         a = (__force u32)saddr->s6_addr32[0];
 138         b = (__force u32)saddr->s6_addr32[1];
 139         c = (__force u32)saddr->s6_addr32[2];
 140
 141         a += JHASH_GOLDEN_RATIO;
 142         b += JHASH_GOLDEN_RATIO;
 143         c += ip6_frag_hash_rnd;
 144         __jhash_mix(a, b, c);
 145
 146         a += (__force u32)saddr->s6_addr32[3];
 147         b += (__force u32)daddr->s6_addr32[0];
 148         c += (__force u32)daddr->s6_addr32[1];
 149         __jhash_mix(a, b, c);
 150
 151         a += (__force u32)daddr->s6_addr32[2];
 152         b += (__force u32)daddr->s6_addr32[3];
 153         c += (__force u32)id;
 154         __jhash_mix(a, b, c);
 155
 156         return c & (IP6Q_HASHSZ - 1);
 157 }
 158
 159 static struct timer_list ip6_frag_secret_timer;
 160 int sysctl_ip6frag_secret_interval __read_mostly = 10 * 60 * HZ;
 161
 162 static void ip6_frag_secret_rebuild(unsigned long dummy)
 163 {
 164         unsigned long now = jiffies;
 165         int i;
 166
 167         write_lock(&ip6_frag_lock);
 168         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 169         for (i = 0; i < IP6Q_HASHSZ; i++) {
 170                 struct frag_queue *q;
 171                 struct hlist_node *p, *n;
 172
 173                 hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
 174                         unsigned int hval = ip6qhashfn(q->id,
 175                                                        &q->saddr,
 176                                                        &q->daddr);
 177
 178                         if (hval != i) {
 179                                 hlist_del(&q->list);
 180
 181                                 /* Relink to new hash chain. */
 182                                 hlist_add_head(&q->list,
 183                                                &ip6_frag_hash[hval]);
 184
 185                         }
 186                 }
 187         }
 188         write_unlock(&ip6_frag_lock);
 189
 190         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 191 }
 192
 193 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 194
 195 /* Memory Tracking Functions. */
 196 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 197 {
 198         if (work)
 199                 *work -= skb->truesize;
 200         atomic_sub(skb->truesize, &ip6_frag_mem);
 201         kfree_skb(skb);
 202 }
 203
 204 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 205 {
 206         if (work)
 207                 *work -= sizeof(struct frag_queue);
 208         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 209         kfree(fq);
 210 }
 211
 212 static inline struct frag_queue *frag_alloc_queue(void)
 213 {
 214         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 215
 216         if(!fq)
 217                 return NULL;
 218         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 219         return fq;
 220 }
 221
 222 /* Destruction primitives. */
 223
 224 /* Complete destruction of fq. */
 225 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 226 {
 227         struct sk_buff *fp;
 228
 229         BUG_TRAP(fq->last_in&COMPLETE);
 230         BUG_TRAP(del_timer(&fq->timer) == 0);
 231
 232         /* Release all fragment data. */
 233         fp = fq->fragments;
 234         while (fp) {
 235                 struct sk_buff *xp = fp->next;
 236
 237                 frag_kfree_skb(fp, work);
 238                 fp = xp;
 239         }
 240
 241         frag_free_queue(fq, work);
 242 }
 243
 244 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 245 {
 246         if (atomic_dec_and_test(&fq->refcnt))
 247                 ip6_frag_destroy(fq, work);
 248 }
 249
 250 /* Kill fq entry. It is not destroyed immediately,
 251  * because caller (and someone more) holds reference count.
 252  */
 253 static __inline__ void fq_kill(struct frag_queue *fq)
 254 {
 255         if (del_timer(&fq->timer))
 256                 atomic_dec(&fq->refcnt);
 257
 258         if (!(fq->last_in & COMPLETE)) {
 259                 fq_unlink(fq);
 260                 atomic_dec(&fq->refcnt);
 261                 fq->last_in |= COMPLETE;
 262         }
 263 }
 264
 265 static void ip6_evictor(struct inet6_dev *idev)
 266 {
 267         struct frag_queue *fq;
 268         struct list_head *tmp;
 269         int work;
 270
 271         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
 272         if (work <= 0)
 273                 return;
 274
 275         while(work > 0) {
 276                 read_lock(&ip6_frag_lock);
 277                 if (list_empty(&ip6_frag_lru_list)) {
 278                         read_unlock(&ip6_frag_lock);
 279                         return;
 280                 }
 281                 tmp = ip6_frag_lru_list.next;
 282                 fq = list_entry(tmp, struct frag_queue, lru_list);
 283                 atomic_inc(&fq->refcnt);
 284                 read_unlock(&ip6_frag_lock);
 285
 286                 spin_lock(&fq->lock);
 287                 if (!(fq->last_in&COMPLETE))
 288                         fq_kill(fq);
 289                 spin_unlock(&fq->lock);
 290
 291                 fq_put(fq, &work);
 292                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 293         }
 294 }
 295
 296 static void ip6_frag_expire(unsigned long data)
 297 {
 298         struct frag_queue *fq = (struct frag_queue *) data;
 299         struct net_device *dev = NULL;
 300
 301         spin_lock(&fq->lock);
 302
 303         if (fq->last_in & COMPLETE)
 304                 goto out;
 305
 306         fq_kill(fq);
 307
 308         dev = dev_get_by_index(&init_net, fq->iif);
 309         if (!dev)
 310                 goto out;
 311
 312         rcu_read_lock();
 313         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 314         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 315         rcu_read_unlock();
 316
 317         /* Don't send error if the first segment did not arrive. */
 318         if (!(fq->last_in&FIRST_IN) || !fq->fragments)
 319                 goto out;
 320
 321         /*
 322            But use as source device on which LAST ARRIVED
 323            segment was received. And do not use fq->dev
 324            pointer directly, device might already disappeared.
 325          */
 326         fq->fragments->dev = dev;
 327         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 328 out:
 329         if (dev)
 330                 dev_put(dev);
 331         spin_unlock(&fq->lock);
 332         fq_put(fq, NULL);
 333 }
 334
 335 /* Creation primitives. */
 336
 337
 338 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
 339 {
 340         struct frag_queue *fq;
 341         unsigned int hash;
 342 #ifdef CONFIG_SMP
 343         struct hlist_node *n;
 344 #endif
 345
 346         write_lock(&ip6_frag_lock);
 347         hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
 348 #ifdef CONFIG_SMP
 349         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 350                 if (fq->id == fq_in->id &&
 351                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 352                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 353                         atomic_inc(&fq->refcnt);
 354                         write_unlock(&ip6_frag_lock);
 355                         fq_in->last_in |= COMPLETE;
 356                         fq_put(fq_in, NULL);
 357                         return fq;
 358                 }
 359         }
 360 #endif
 361         fq = fq_in;
 362
 363         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 364                 atomic_inc(&fq->refcnt);
 365
 366         atomic_inc(&fq->refcnt);
 367         hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
 368         INIT_LIST_HEAD(&fq->lru_list);
 369         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 370         ip6_frag_nqueues++;
 371         write_unlock(&ip6_frag_lock);
 372         return fq;
 373 }
 374
 375
 376 static struct frag_queue *
 377 ip6_frag_create(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 378                 struct inet6_dev *idev)
 379 {
 380         struct frag_queue *fq;
 381
 382         if ((fq = frag_alloc_queue()) == NULL)
 383                 goto oom;
 384
 385         fq->id = id;
 386         ipv6_addr_copy(&fq->saddr, src);
 387         ipv6_addr_copy(&fq->daddr, dst);
 388
 389         init_timer(&fq->timer);
 390         fq->timer.function = ip6_frag_expire;
 391         fq->timer.data = (long) fq;
 392         spin_lock_init(&fq->lock);
 393         atomic_set(&fq->refcnt, 1);
 394
 395         return ip6_frag_intern(fq);
 396
 397 oom:
 398         IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 399         return NULL;
 400 }
 401
 402 static __inline__ struct frag_queue *
 403 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 404         struct inet6_dev *idev)
 405 {
 406         struct frag_queue *fq;
 407         struct hlist_node *n;
 408         unsigned int hash;
 409
 410         read_lock(&ip6_frag_lock);
 411         hash = ip6qhashfn(id, src, dst);
 412         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 413                 if (fq->id == id &&
 414                     ipv6_addr_equal(src, &fq->saddr) &&
 415                     ipv6_addr_equal(dst, &fq->daddr)) {
 416                         atomic_inc(&fq->refcnt);
 417                         read_unlock(&ip6_frag_lock);
 418                         return fq;
 419                 }
 420         }
 421         read_unlock(&ip6_frag_lock);
 422
 423         return ip6_frag_create(id, src, dst, idev);
 424 }
 425
 426
 427 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 428                            struct frag_hdr *fhdr, int nhoff)
 429 {
 430         struct sk_buff *prev, *next;
 431         struct net_device *dev;
 432         int offset, end;
 433
 434         if (fq->last_in & COMPLETE)
 435                 goto err;
 436
 437         offset = ntohs(fhdr->frag_off) & ~0x7;
 438         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 439                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 440
 441         if ((unsigned int)end > IPV6_MAXPLEN) {
 442                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 443                                  IPSTATS_MIB_INHDRERRORS);
 444                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 445                                   ((u8 *)&fhdr->frag_off -
 446                                    skb_network_header(skb)));
 447                 return -1;
 448         }
 449
 450         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 451                 const unsigned char *nh = skb_network_header(skb);
 452                 skb->csum = csum_sub(skb->csum,
 453                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 454                                                   0));
 455         }
 456
 457         /* Is this the final fragment? */
 458         if (!(fhdr->frag_off & htons(IP6_MF))) {
 459                 /* If we already have some bits beyond end
 460                  * or have different end, the segment is corrupted.
 461                  */
 462                 if (end < fq->len ||
 463                     ((fq->last_in & LAST_IN) && end != fq->len))
 464                         goto err;
 465                 fq->last_in |= LAST_IN;
 466                 fq->len = end;
 467         } else {
 468                 /* Check if the fragment is rounded to 8 bytes.
 469                  * Required by the RFC.
 470                  */
 471                 if (end & 0x7) {
 472                         /* RFC2460 says always send parameter problem in
 473                          * this case. -DaveM
 474                          */
 475                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 476                                          IPSTATS_MIB_INHDRERRORS);
 477                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 478                                           offsetof(struct ipv6hdr, payload_len));
 479                         return -1;
 480                 }
 481                 if (end > fq->len) {
 482                         /* Some bits beyond end -> corruption. */
 483                         if (fq->last_in & LAST_IN)
 484                                 goto err;
 485                         fq->len = end;
 486                 }
 487         }
 488
 489         if (end == offset)
 490                 goto err;
 491
 492         /* Point into the IP datagram 'data' part. */
 493         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 494                 goto err;
 495
 496         if (pskb_trim_rcsum(skb, end - offset))
 497                 goto err;
 498
 499         /* Find out which fragments are in front and at the back of us
 500          * in the chain of fragments so far.  We must know where to put
 501          * this fragment, right?
 502          */
 503         prev = NULL;
 504         for(next = fq->fragments; next != NULL; next = next->next) {
 505                 if (FRAG6_CB(next)->offset >= offset)
 506                         break;  /* bingo! */
 507                 prev = next;
 508         }
 509
 510         /* We found where to put this one.  Check for overlap with
 511          * preceding fragment, and, if needed, align things so that
 512          * any overlaps are eliminated.
 513          */
 514         if (prev) {
 515                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 516
 517                 if (i > 0) {
 518                         offset += i;
 519                         if (end <= offset)
 520                                 goto err;
 521                         if (!pskb_pull(skb, i))
 522                                 goto err;
 523                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 524                                 skb->ip_summed = CHECKSUM_NONE;
 525                 }
 526         }
 527
 528         /* Look for overlap with succeeding segments.
 529          * If we can merge fragments, do it.
 530          */
 531         while (next && FRAG6_CB(next)->offset < end) {
 532                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 533
 534                 if (i < next->len) {
 535                         /* Eat head of the next overlapped fragment
 536                          * and leave the loop. The next ones cannot overlap.
 537                          */
 538                         if (!pskb_pull(next, i))
 539                                 goto err;
 540                         FRAG6_CB(next)->offset += i;    /* next fragment */
 541                         fq->meat -= i;
 542                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 543                                 next->ip_summed = CHECKSUM_NONE;
 544                         break;
 545                 } else {
 546                         struct sk_buff *free_it = next;
 547
 548                         /* Old fragment is completely overridden with
 549                          * new one drop it.
 550                          */
 551                         next = next->next;
 552
 553                         if (prev)
 554                                 prev->next = next;
 555                         else
 556                                 fq->fragments = next;
 557
 558                         fq->meat -= free_it->len;
 559                         frag_kfree_skb(free_it, NULL);
 560                 }
 561         }
 562
 563         FRAG6_CB(skb)->offset = offset;
 564
 565         /* Insert this fragment in the chain of fragments. */
 566         skb->next = next;
 567         if (prev)
 568                 prev->next = skb;
 569         else
 570                 fq->fragments = skb;
 571
 572         dev = skb->dev;
 573         if (dev) {
 574                 fq->iif = dev->ifindex;
 575                 skb->dev = NULL;
 576         }
 577         fq->stamp = skb->tstamp;
 578         fq->meat += skb->len;
 579         atomic_add(skb->truesize, &ip6_frag_mem);
 580
 581         /* The first fragment.
 582          * nhoffset is obtained from the first fragment, of course.
 583          */
 584         if (offset == 0) {
 585                 fq->nhoffset = nhoff;
 586                 fq->last_in |= FIRST_IN;
 587         }
 588
 589         if (fq->last_in == (FIRST_IN | LAST_IN) && fq->meat == fq->len)
 590                 return ip6_frag_reasm(fq, prev, dev);
 591
 592         write_lock(&ip6_frag_lock);
 593         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
 594         write_unlock(&ip6_frag_lock);
 595         return -1;
 596
 597 err:
 598         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 599         kfree_skb(skb);
 600         return -1;
 601 }
 602
 603 /*
 604  *      Check if this packet is complete.
 605  *      Returns NULL on failure by any reason, and pointer
 606  *      to current nexthdr field in reassembled frame.
 607  *
 608  *      It is called with locked fq, and caller must check that
 609  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 610  *      the last and the first frames arrived and all the bits are here.
 611  */
 612 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 613                           struct net_device *dev)
 614 {
 615         struct sk_buff *fp, *head = fq->fragments;
 616         int    payload_len;
 617         unsigned int nhoff;
 618
 619         fq_kill(fq);
 620
 621         /* Make the one we just received the head. */
 622         if (prev) {
 623                 head = prev->next;
 624                 fp = skb_clone(head, GFP_ATOMIC);
 625
 626                 if (!fp)
 627                         goto out_oom;
 628
 629                 fp->next = head->next;
 630                 prev->next = fp;
 631
 632                 skb_morph(head, fq->fragments);
 633                 head->next = fq->fragments->next;
 634
 635                 kfree_skb(fq->fragments);
 636                 fq->fragments = head;
 637         }
 638
 639         BUG_TRAP(head != NULL);
 640         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 641
 642         /* Unfragmented part is taken from the first segment. */
 643         payload_len = ((head->data - skb_network_header(head)) -
 644                        sizeof(struct ipv6hdr) + fq->len -
 645                        sizeof(struct frag_hdr));
 646         if (payload_len > IPV6_MAXPLEN)
 647                 goto out_oversize;
 648
 649         /* Head of list must not be cloned. */
 650         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 651                 goto out_oom;
 652
 653         /* If the first fragment is fragmented itself, we split
 654          * it to two chunks: the first with data and paged part
 655          * and the second, holding only fragments. */
 656         if (skb_shinfo(head)->frag_list) {
 657                 struct sk_buff *clone;
 658                 int i, plen = 0;
 659
 660                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 661                         goto out_oom;
 662                 clone->next = head->next;
 663                 head->next = clone;
 664                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 665                 skb_shinfo(head)->frag_list = NULL;
 666                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 667                         plen += skb_shinfo(head)->frags[i].size;
 668                 clone->len = clone->data_len = head->data_len - plen;
 669                 head->data_len -= clone->len;
 670                 head->len -= clone->len;
 671                 clone->csum = 0;
 672                 clone->ip_summed = head->ip_summed;
 673                 atomic_add(clone->truesize, &ip6_frag_mem);
 674         }
 675
 676         /* We have to remove fragment header from datagram and to relocate
 677          * header in order to calculate ICV correctly. */
 678         nhoff = fq->nhoffset;
 679         skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
 680         memmove(head->head + sizeof(struct frag_hdr), head->head,
 681                 (head->data - head->head) - sizeof(struct frag_hdr));
 682         head->mac_header += sizeof(struct frag_hdr);
 683         head->network_header += sizeof(struct frag_hdr);
 684
 685         skb_shinfo(head)->frag_list = head->next;
 686         skb_reset_transport_header(head);
 687         skb_push(head, head->data - skb_network_header(head));
 688         atomic_sub(head->truesize, &ip6_frag_mem);
 689
 690         for (fp=head->next; fp; fp = fp->next) {
 691                 head->data_len += fp->len;
 692                 head->len += fp->len;
 693                 if (head->ip_summed != fp->ip_summed)
 694                         head->ip_summed = CHECKSUM_NONE;
 695                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 696                         head->csum = csum_add(head->csum, fp->csum);
 697                 head->truesize += fp->truesize;
 698                 atomic_sub(fp->truesize, &ip6_frag_mem);
 699         }
 700
 701         head->next = NULL;
 702         head->dev = dev;
 703         head->tstamp = fq->stamp;
 704         ipv6_hdr(head)->payload_len = htons(payload_len);
 705         IP6CB(head)->nhoff = nhoff;
 706
 707         /* Yes, and fold redundant checksum back. 8) */
 708         if (head->ip_summed == CHECKSUM_COMPLETE)
 709                 head->csum = csum_partial(skb_network_header(head),
 710                                           skb_network_header_len(head),
 711                                           head->csum);
 712
 713         rcu_read_lock();
 714         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 715         rcu_read_unlock();
 716         fq->fragments = NULL;
 717         return 1;
 718
 719 out_oversize:
 720         if (net_ratelimit())
 721                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 722         goto out_fail;
 723 out_oom:
 724         if (net_ratelimit())
 725                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 726 out_fail:
 727         rcu_read_lock();
 728         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 729         rcu_read_unlock();
 730         return -1;
 731 }
 732
 733 static int ipv6_frag_rcv(struct sk_buff **skbp)
 734 {
 735         struct sk_buff *skb = *skbp;
 736         struct frag_hdr *fhdr;
 737         struct frag_queue *fq;
 738         struct ipv6hdr *hdr = ipv6_hdr(skb);
 739
 740         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMREQDS);
 741
 742         /* Jumbo payload inhibits frag. header */
 743         if (hdr->payload_len==0) {
 744                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 745                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 746                                   skb_network_header_len(skb));
 747                 return -1;
 748         }
 749         if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
 750                                  sizeof(struct frag_hdr)))) {
 751                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 752                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 753                                   skb_network_header_len(skb));
 754                 return -1;
 755         }
 756
 757         hdr = ipv6_hdr(skb);
 758         fhdr = (struct frag_hdr *)skb_transport_header(skb);
 759
 760         if (!(fhdr->frag_off & htons(0xFFF9))) {
 761                 /* It is not a fragmented frame */
 762                 skb->transport_header += sizeof(struct frag_hdr);
 763                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMOKS);
 764
 765                 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
 766                 return 1;
 767         }
 768
 769         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 770                 ip6_evictor(ip6_dst_idev(skb->dst));
 771
 772         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr,
 773                           ip6_dst_idev(skb->dst))) != NULL) {
 774                 int ret;
 775
 776                 spin_lock(&fq->lock);
 777
 778                 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 779
 780                 spin_unlock(&fq->lock);
 781                 fq_put(fq, NULL);
 782                 return ret;
 783         }
 784
 785         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 786         kfree_skb(skb);
 787         return -1;
 788 }
 789
 790 static struct inet6_protocol frag_protocol =
 791 {
 792         .handler        =       ipv6_frag_rcv,
 793         .flags          =       INET6_PROTO_NOPOLICY,
 794 };
 795
 796 void __init ipv6_frag_init(void)
 797 {
 798         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 799                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 800
 801         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 802                                    (jiffies ^ (jiffies >> 6)));
 803
 804         init_timer(&ip6_frag_secret_timer);
 805         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 806         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 807         add_timer(&ip6_frag_secret_timer);
 808 }