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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/config.h>
  32 #include <linux/errno.h>
  33 #include <linux/types.h>
  34 #include <linux/string.h>
  35 #include <linux/socket.h>
  36 #include <linux/sockios.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/net.h>
  39 #include <linux/list.h>
  40 #include <linux/netdevice.h>
  41 #include <linux/in6.h>
  42 #include <linux/ipv6.h>
  43 #include <linux/icmpv6.h>
  44 #include <linux/random.h>
  45 #include <linux/jhash.h>
  46
  47 #include <net/sock.h>
  48 #include <net/snmp.h>
  49
  50 #include <net/ipv6.h>
  51 #include <net/protocol.h>
  52 #include <net/transp_v6.h>
  53 #include <net/rawv6.h>
  54 #include <net/ndisc.h>
  55 #include <net/addrconf.h>
  56
  57 int sysctl_ip6frag_high_thresh = 256*1024;
  58 int sysctl_ip6frag_low_thresh = 192*1024;
  59
  60 int sysctl_ip6frag_time = IPV6_FRAG_TIMEOUT;
  61
  62 struct ip6frag_skb_cb
  63 {
  64         struct inet6_skb_parm   h;
  65         int                     offset;
  66 };
  67
  68 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  69
  70
  71 /*
  72  *      Equivalent of ipv4 struct ipq
  73  */
  74
  75 struct frag_queue
  76 {
  77         struct frag_queue       *next;
  78         struct list_head lru_list;              /* lru list member      */
  79
  80         __u32                   id;             /* fragment id          */
  81         struct in6_addr         saddr;
  82         struct in6_addr         daddr;
  83
  84         spinlock_t              lock;
  85         atomic_t                refcnt;
  86         struct timer_list       timer;          /* expire timer         */
  87         struct sk_buff          *fragments;
  88         int                     len;
  89         int                     meat;
  90         int                     iif;
  91         struct timeval          stamp;
  92         unsigned int            csum;
  93         __u8                    last_in;        /* has first/last segment arrived? */
  94 #define COMPLETE                4
  95 #define FIRST_IN                2
  96 #define LAST_IN                 1
  97         __u16                   nhoffset;
  98         struct frag_queue       **pprev;
  99 };
 100
 101 /* Hash table. */
 102
 103 #define IP6Q_HASHSZ     64
 104
 105 static struct frag_queue *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 __inline__ void __fq_unlink(struct frag_queue *fq)
 112 {
 113         if(fq->next)
 114                 fq->next->pprev = fq->pprev;
 115         *fq->pprev = fq->next;
 116         list_del(&fq->lru_list);
 117         ip6_frag_nqueues--;
 118 }
 119
 120 static __inline__ void fq_unlink(struct frag_queue *fq)
 121 {
 122         write_lock(&ip6_frag_lock);
 123         __fq_unlink(fq);
 124         write_unlock(&ip6_frag_lock);
 125 }
 126
 127 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
 128                                struct in6_addr *daddr)
 129 {
 130         u32 a, b, c;
 131
 132         a = saddr->s6_addr32[0];
 133         b = saddr->s6_addr32[1];
 134         c = saddr->s6_addr32[2];
 135
 136         a += JHASH_GOLDEN_RATIO;
 137         b += JHASH_GOLDEN_RATIO;
 138         c += ip6_frag_hash_rnd;
 139         __jhash_mix(a, b, c);
 140
 141         a += saddr->s6_addr32[3];
 142         b += daddr->s6_addr32[0];
 143         c += daddr->s6_addr32[1];
 144         __jhash_mix(a, b, c);
 145
 146         a += daddr->s6_addr32[2];
 147         b += daddr->s6_addr32[3];
 148         c += id;
 149         __jhash_mix(a, b, c);
 150
 151         return c & (IP6Q_HASHSZ - 1);
 152 }
 153
 154 static struct timer_list ip6_frag_secret_timer;
 155 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
 156
 157 static void ip6_frag_secret_rebuild(unsigned long dummy)
 158 {
 159         unsigned long now = jiffies;
 160         int i;
 161
 162         write_lock(&ip6_frag_lock);
 163         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 164         for (i = 0; i < IP6Q_HASHSZ; i++) {
 165                 struct frag_queue *q;
 166
 167                 q = ip6_frag_hash[i];
 168                 while (q) {
 169                         struct frag_queue *next = q->next;
 170                         unsigned int hval = ip6qhashfn(q->id,
 171                                                        &q->saddr,
 172                                                        &q->daddr);
 173
 174                         if (hval != i) {
 175                                 /* Unlink. */
 176                                 if (q->next)
 177                                         q->next->pprev = q->pprev;
 178                                 *q->pprev = q->next;
 179
 180                                 /* Relink to new hash chain. */
 181                                 if ((q->next = ip6_frag_hash[hval]) != NULL)
 182                                         q->next->pprev = &q->next;
 183                                 ip6_frag_hash[hval] = q;
 184                                 q->pprev = &ip6_frag_hash[hval];
 185                         }
 186
 187                         q = next;
 188                 }
 189         }
 190         write_unlock(&ip6_frag_lock);
 191
 192         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 193 }
 194
 195 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 196
 197 /* Memory Tracking Functions. */
 198 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 199 {
 200         if (work)
 201                 *work -= skb->truesize;
 202         atomic_sub(skb->truesize, &ip6_frag_mem);
 203         kfree_skb(skb);
 204 }
 205
 206 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 207 {
 208         if (work)
 209                 *work -= sizeof(struct frag_queue);
 210         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 211         kfree(fq);
 212 }
 213
 214 static inline struct frag_queue *frag_alloc_queue(void)
 215 {
 216         struct frag_queue *fq = kmalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 217
 218         if(!fq)
 219                 return NULL;
 220         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 221         return fq;
 222 }
 223
 224 /* Destruction primitives. */
 225
 226 /* Complete destruction of fq. */
 227 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 228 {
 229         struct sk_buff *fp;
 230
 231         BUG_TRAP(fq->last_in&COMPLETE);
 232         BUG_TRAP(del_timer(&fq->timer) == 0);
 233
 234         /* Release all fragment data. */
 235         fp = fq->fragments;
 236         while (fp) {
 237                 struct sk_buff *xp = fp->next;
 238
 239                 frag_kfree_skb(fp, work);
 240                 fp = xp;
 241         }
 242
 243         frag_free_queue(fq, work);
 244 }
 245
 246 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 247 {
 248         if (atomic_dec_and_test(&fq->refcnt))
 249                 ip6_frag_destroy(fq, work);
 250 }
 251
 252 /* Kill fq entry. It is not destroyed immediately,
 253  * because caller (and someone more) holds reference count.
 254  */
 255 static __inline__ void fq_kill(struct frag_queue *fq)
 256 {
 257         if (del_timer(&fq->timer))
 258                 atomic_dec(&fq->refcnt);
 259
 260         if (!(fq->last_in & COMPLETE)) {
 261                 fq_unlink(fq);
 262                 atomic_dec(&fq->refcnt);
 263                 fq->last_in |= COMPLETE;
 264         }
 265 }
 266
 267 static void ip6_evictor(void)
 268 {
 269         struct frag_queue *fq;
 270         struct list_head *tmp;
 271         int work;
 272
 273         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
 274         if (work <= 0)
 275                 return;
 276
 277         while(work > 0) {
 278                 read_lock(&ip6_frag_lock);
 279                 if (list_empty(&ip6_frag_lru_list)) {
 280                         read_unlock(&ip6_frag_lock);
 281                         return;
 282                 }
 283                 tmp = ip6_frag_lru_list.next;
 284                 fq = list_entry(tmp, struct frag_queue, lru_list);
 285                 atomic_inc(&fq->refcnt);
 286                 read_unlock(&ip6_frag_lock);
 287
 288                 spin_lock(&fq->lock);
 289                 if (!(fq->last_in&COMPLETE))
 290                         fq_kill(fq);
 291                 spin_unlock(&fq->lock);
 292
 293                 fq_put(fq, &work);
 294                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 295         }
 296 }
 297
 298 static void ip6_frag_expire(unsigned long data)
 299 {
 300         struct frag_queue *fq = (struct frag_queue *) data;
 301
 302         spin_lock(&fq->lock);
 303
 304         if (fq->last_in & COMPLETE)
 305                 goto out;
 306
 307         fq_kill(fq);
 308
 309         IP6_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
 310         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 311
 312         /* Send error only if the first segment arrived. */
 313         if (fq->last_in&FIRST_IN && fq->fragments) {
 314                 struct net_device *dev = dev_get_by_index(fq->iif);
 315
 316                 /*
 317                    But use as source device on which LAST ARRIVED
 318                    segment was received. And do not use fq->dev
 319                    pointer directly, device might already disappeared.
 320                  */
 321                 if (dev) {
 322                         fq->fragments->dev = dev;
 323                         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0,
 324                                     dev);
 325                         dev_put(dev);
 326                 }
 327         }
 328 out:
 329         spin_unlock(&fq->lock);
 330         fq_put(fq, NULL);
 331 }
 332
 333 /* Creation primitives. */
 334
 335
 336 static struct frag_queue *ip6_frag_intern(unsigned int hash,
 337                                           struct frag_queue *fq_in)
 338 {
 339         struct frag_queue *fq;
 340
 341         write_lock(&ip6_frag_lock);
 342 #ifdef CONFIG_SMP
 343         for (fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
 344                 if (fq->id == fq_in->id &&
 345                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 346                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 347                         atomic_inc(&fq->refcnt);
 348                         write_unlock(&ip6_frag_lock);
 349                         fq_in->last_in |= COMPLETE;
 350                         fq_put(fq_in, NULL);
 351                         return fq;
 352                 }
 353         }
 354 #endif
 355         fq = fq_in;
 356
 357         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 358                 atomic_inc(&fq->refcnt);
 359
 360         atomic_inc(&fq->refcnt);
 361         if((fq->next = ip6_frag_hash[hash]) != NULL)
 362                 fq->next->pprev = &fq->next;
 363         ip6_frag_hash[hash] = fq;
 364         fq->pprev = &ip6_frag_hash[hash];
 365         INIT_LIST_HEAD(&fq->lru_list);
 366         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 367         ip6_frag_nqueues++;
 368         write_unlock(&ip6_frag_lock);
 369         return fq;
 370 }
 371
 372
 373 static struct frag_queue *
 374 ip6_frag_create(unsigned int hash, u32 id, struct in6_addr *src, struct in6_addr *dst)
 375 {
 376         struct frag_queue *fq;
 377
 378         if ((fq = frag_alloc_queue()) == NULL)
 379                 goto oom;
 380
 381         memset(fq, 0, sizeof(struct frag_queue));
 382
 383         fq->id = id;
 384         ipv6_addr_copy(&fq->saddr, src);
 385         ipv6_addr_copy(&fq->daddr, dst);
 386
 387         init_timer(&fq->timer);
 388         fq->timer.function = ip6_frag_expire;
 389         fq->timer.data = (long) fq;
 390         spin_lock_init(&fq->lock);
 391         atomic_set(&fq->refcnt, 1);
 392
 393         return ip6_frag_intern(hash, fq);
 394
 395 oom:
 396         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 397         return NULL;
 398 }
 399
 400 static __inline__ struct frag_queue *
 401 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
 402 {
 403         struct frag_queue *fq;
 404         unsigned int hash = ip6qhashfn(id, src, dst);
 405
 406         read_lock(&ip6_frag_lock);
 407         for(fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
 408                 if (fq->id == id &&
 409                     ipv6_addr_equal(src, &fq->saddr) &&
 410                     ipv6_addr_equal(dst, &fq->daddr)) {
 411                         atomic_inc(&fq->refcnt);
 412                         read_unlock(&ip6_frag_lock);
 413                         return fq;
 414                 }
 415         }
 416         read_unlock(&ip6_frag_lock);
 417
 418         return ip6_frag_create(hash, id, src, dst);
 419 }
 420
 421
 422 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 423                            struct frag_hdr *fhdr, int nhoff)
 424 {
 425         struct sk_buff *prev, *next;
 426         int offset, end;
 427
 428         if (fq->last_in & COMPLETE)
 429                 goto err;
 430
 431         offset = ntohs(fhdr->frag_off) & ~0x7;
 432         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
 433                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
 434
 435         if ((unsigned int)end > IPV6_MAXPLEN) {
 436                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 437                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
 438                 return;
 439         }
 440
 441         if (skb->ip_summed == CHECKSUM_HW)
 442                 skb->csum = csum_sub(skb->csum,
 443                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
 444
 445         /* Is this the final fragment? */
 446         if (!(fhdr->frag_off & htons(IP6_MF))) {
 447                 /* If we already have some bits beyond end
 448                  * or have different end, the segment is corrupted.
 449                  */
 450                 if (end < fq->len ||
 451                     ((fq->last_in & LAST_IN) && end != fq->len))
 452                         goto err;
 453                 fq->last_in |= LAST_IN;
 454                 fq->len = end;
 455         } else {
 456                 /* Check if the fragment is rounded to 8 bytes.
 457                  * Required by the RFC.
 458                  */
 459                 if (end & 0x7) {
 460                         /* RFC2460 says always send parameter problem in
 461                          * this case. -DaveM
 462                          */
 463                         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 464                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 465                                           offsetof(struct ipv6hdr, payload_len));
 466                         return;
 467                 }
 468                 if (end > fq->len) {
 469                         /* Some bits beyond end -> corruption. */
 470                         if (fq->last_in & LAST_IN)
 471                                 goto err;
 472                         fq->len = end;
 473                 }
 474         }
 475
 476         if (end == offset)
 477                 goto err;
 478
 479         /* Point into the IP datagram 'data' part. */
 480         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 481                 goto err;
 482         if (end-offset < skb->len) {
 483                 if (pskb_trim(skb, end - offset))
 484                         goto err;
 485                 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 486                         skb->ip_summed = CHECKSUM_NONE;
 487         }
 488
 489         /* Find out which fragments are in front and at the back of us
 490          * in the chain of fragments so far.  We must know where to put
 491          * this fragment, right?
 492          */
 493         prev = NULL;
 494         for(next = fq->fragments; next != NULL; next = next->next) {
 495                 if (FRAG6_CB(next)->offset >= offset)
 496                         break;  /* bingo! */
 497                 prev = next;
 498         }
 499
 500         /* We found where to put this one.  Check for overlap with
 501          * preceding fragment, and, if needed, align things so that
 502          * any overlaps are eliminated.
 503          */
 504         if (prev) {
 505                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 506
 507                 if (i > 0) {
 508                         offset += i;
 509                         if (end <= offset)
 510                                 goto err;
 511                         if (!pskb_pull(skb, i))
 512                                 goto err;
 513                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 514                                 skb->ip_summed = CHECKSUM_NONE;
 515                 }
 516         }
 517
 518         /* Look for overlap with succeeding segments.
 519          * If we can merge fragments, do it.
 520          */
 521         while (next && FRAG6_CB(next)->offset < end) {
 522                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 523
 524                 if (i < next->len) {
 525                         /* Eat head of the next overlapped fragment
 526                          * and leave the loop. The next ones cannot overlap.
 527                          */
 528                         if (!pskb_pull(next, i))
 529                                 goto err;
 530                         FRAG6_CB(next)->offset += i;    /* next fragment */
 531                         fq->meat -= i;
 532                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 533                                 next->ip_summed = CHECKSUM_NONE;
 534                         break;
 535                 } else {
 536                         struct sk_buff *free_it = next;
 537
 538                         /* Old fragment is completely overridden with
 539                          * new one drop it.
 540                          */
 541                         next = next->next;
 542
 543                         if (prev)
 544                                 prev->next = next;
 545                         else
 546                                 fq->fragments = next;
 547
 548                         fq->meat -= free_it->len;
 549                         frag_kfree_skb(free_it, NULL);
 550                 }
 551         }
 552
 553         FRAG6_CB(skb)->offset = offset;
 554
 555         /* Insert this fragment in the chain of fragments. */
 556         skb->next = next;
 557         if (prev)
 558                 prev->next = skb;
 559         else
 560                 fq->fragments = skb;
 561
 562         if (skb->dev)
 563                 fq->iif = skb->dev->ifindex;
 564         skb->dev = NULL;
 565         skb_get_timestamp(skb, &fq->stamp);
 566         fq->meat += skb->len;
 567         atomic_add(skb->truesize, &ip6_frag_mem);
 568
 569         /* The first fragment.
 570          * nhoffset is obtained from the first fragment, of course.
 571          */
 572         if (offset == 0) {
 573                 fq->nhoffset = nhoff;
 574                 fq->last_in |= FIRST_IN;
 575         }
 576         write_lock(&ip6_frag_lock);
 577         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
 578         write_unlock(&ip6_frag_lock);
 579         return;
 580
 581 err:
 582         IP6_INC_STATS(IPSTATS_MIB_REASMFAILS);
 583         kfree_skb(skb);
 584 }
 585
 586 /*
 587  *      Check if this packet is complete.
 588  *      Returns NULL on failure by any reason, and pointer
 589  *      to current nexthdr field in reassembled frame.
 590  *
 591  *      It is called with locked fq, and caller must check that
 592  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 593  *      the last and the first frames arrived and all the bits are here.
 594  */
 595 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
 596                           unsigned int *nhoffp,
 597                           struct net_device *dev)
 598 {
 599         struct sk_buff *fp, *head = fq->fragments;
 600         int    payload_len;
 601         unsigned int nhoff;
 602
 603         fq_kill(fq);
 604
 605         BUG_TRAP(head != NULL);
 606         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 607
 608         /* Unfragmented part is taken from the first segment. */
 609         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
 610         if (payload_len > IPV6_MAXPLEN)
 611                 goto out_oversize;
 612
 613         /* Head of list must not be cloned. */
 614         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 615                 goto out_oom;
 616
 617         /* If the first fragment is fragmented itself, we split
 618          * it to two chunks: the first with data and paged part
 619          * and the second, holding only fragments. */
 620         if (skb_shinfo(head)->frag_list) {
 621                 struct sk_buff *clone;
 622                 int i, plen = 0;
 623
 624                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 625                         goto out_oom;
 626                 clone->next = head->next;
 627                 head->next = clone;
 628                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 629                 skb_shinfo(head)->frag_list = NULL;
 630                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 631                         plen += skb_shinfo(head)->frags[i].size;
 632                 clone->len = clone->data_len = head->data_len - plen;
 633                 head->data_len -= clone->len;
 634                 head->len -= clone->len;
 635                 clone->csum = 0;
 636                 clone->ip_summed = head->ip_summed;
 637                 atomic_add(clone->truesize, &ip6_frag_mem);
 638         }
 639
 640         /* We have to remove fragment header from datagram and to relocate
 641          * header in order to calculate ICV correctly. */
 642         nhoff = fq->nhoffset;
 643         head->nh.raw[nhoff] = head->h.raw[0];
 644         memmove(head->head + sizeof(struct frag_hdr), head->head,
 645                 (head->data - head->head) - sizeof(struct frag_hdr));
 646         head->mac.raw += sizeof(struct frag_hdr);
 647         head->nh.raw += sizeof(struct frag_hdr);
 648
 649         skb_shinfo(head)->frag_list = head->next;
 650         head->h.raw = head->data;
 651         skb_push(head, head->data - head->nh.raw);
 652         atomic_sub(head->truesize, &ip6_frag_mem);
 653
 654         for (fp=head->next; fp; fp = fp->next) {
 655                 head->data_len += fp->len;
 656                 head->len += fp->len;
 657                 if (head->ip_summed != fp->ip_summed)
 658                         head->ip_summed = CHECKSUM_NONE;
 659                 else if (head->ip_summed == CHECKSUM_HW)
 660                         head->csum = csum_add(head->csum, fp->csum);
 661                 head->truesize += fp->truesize;
 662                 atomic_sub(fp->truesize, &ip6_frag_mem);
 663         }
 664
 665         head->next = NULL;
 666         head->dev = dev;
 667         skb_set_timestamp(head, &fq->stamp);
 668         head->nh.ipv6h->payload_len = htons(payload_len);
 669
 670         *skb_in = head;
 671
 672         /* Yes, and fold redundant checksum back. 8) */
 673         if (head->ip_summed == CHECKSUM_HW)
 674                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
 675
 676         IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 677         fq->fragments = NULL;
 678         *nhoffp = nhoff;
 679         return 1;
 680
 681 out_oversize:
 682         if (net_ratelimit())
 683                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 684         goto out_fail;
 685 out_oom:
 686         if (net_ratelimit())
 687                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 688 out_fail:
 689         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 690         return -1;
 691 }
 692
 693 static int ipv6_frag_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
 694 {
 695         struct sk_buff *skb = *skbp;
 696         struct net_device *dev = skb->dev;
 697         struct frag_hdr *fhdr;
 698         struct frag_queue *fq;
 699         struct ipv6hdr *hdr;
 700
 701         hdr = skb->nh.ipv6h;
 702
 703         IP6_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
 704
 705         /* Jumbo payload inhibits frag. header */
 706         if (hdr->payload_len==0) {
 707                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 708                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 709                 return -1;
 710         }
 711         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
 712                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 713                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 714                 return -1;
 715         }
 716
 717         hdr = skb->nh.ipv6h;
 718         fhdr = (struct frag_hdr *)skb->h.raw;
 719
 720         if (!(fhdr->frag_off & htons(0xFFF9))) {
 721                 /* It is not a fragmented frame */
 722                 skb->h.raw += sizeof(struct frag_hdr);
 723                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 724
 725                 *nhoffp = (u8*)fhdr - skb->nh.raw;
 726                 return 1;
 727         }
 728
 729         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 730                 ip6_evictor();
 731
 732         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
 733                 int ret = -1;
 734
 735                 spin_lock(&fq->lock);
 736
 737                 ip6_frag_queue(fq, skb, fhdr, *nhoffp);
 738
 739                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
 740                     fq->meat == fq->len)
 741                         ret = ip6_frag_reasm(fq, skbp, nhoffp, dev);
 742
 743                 spin_unlock(&fq->lock);
 744                 fq_put(fq, NULL);
 745                 return ret;
 746         }
 747
 748         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 749         kfree_skb(skb);
 750         return -1;
 751 }
 752
 753 static struct inet6_protocol frag_protocol =
 754 {
 755         .handler        =       ipv6_frag_rcv,
 756         .flags          =       INET6_PROTO_NOPOLICY,
 757 };
 758
 759 void __init ipv6_frag_init(void)
 760 {
 761         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 762                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 763
 764         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 765                                    (jiffies ^ (jiffies >> 6)));
 766
 767         init_timer(&ip6_frag_secret_timer);
 768         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 769         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 770         add_timer(&ip6_frag_secret_timer);
 771 }