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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
  46 #include <net/sock.h>
  47 #include <net/snmp.h>
  48
  49 #include <net/ipv6.h>
  50 #include <net/ip6_route.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 __read_mostly = 256*1024;
  58 int sysctl_ip6frag_low_thresh __read_mostly = 192*1024;
  59
  60 int sysctl_ip6frag_time __read_mostly = 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 hlist_node       list;
  78         struct list_head lru_list;              /* lru list member      */
  79
  80         __be32                  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 };
  99
 100 /* Hash table. */
 101
 102 #define IP6Q_HASHSZ     64
 103
 104 static struct hlist_head ip6_frag_hash[IP6Q_HASHSZ];
 105 static DEFINE_RWLOCK(ip6_frag_lock);
 106 static u32 ip6_frag_hash_rnd;
 107 static LIST_HEAD(ip6_frag_lru_list);
 108 int ip6_frag_nqueues = 0;
 109
 110 static __inline__ void __fq_unlink(struct frag_queue *fq)
 111 {
 112         hlist_del(&fq->list);
 113         list_del(&fq->lru_list);
 114         ip6_frag_nqueues--;
 115 }
 116
 117 static __inline__ void fq_unlink(struct frag_queue *fq)
 118 {
 119         write_lock(&ip6_frag_lock);
 120         __fq_unlink(fq);
 121         write_unlock(&ip6_frag_lock);
 122 }
 123
 124 /*
 125  * callers should be careful not to use the hash value outside the ipfrag_lock
 126  * as doing so could race with ipfrag_hash_rnd being recalculated.
 127  */
 128 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
 129                                struct in6_addr *daddr)
 130 {
 131         u32 a, b, c;
 132
 133         a = (__force u32)saddr->s6_addr32[0];
 134         b = (__force u32)saddr->s6_addr32[1];
 135         c = (__force u32)saddr->s6_addr32[2];
 136
 137         a += JHASH_GOLDEN_RATIO;
 138         b += JHASH_GOLDEN_RATIO;
 139         c += ip6_frag_hash_rnd;
 140         __jhash_mix(a, b, c);
 141
 142         a += (__force u32)saddr->s6_addr32[3];
 143         b += (__force u32)daddr->s6_addr32[0];
 144         c += (__force u32)daddr->s6_addr32[1];
 145         __jhash_mix(a, b, c);
 146
 147         a += (__force u32)daddr->s6_addr32[2];
 148         b += (__force u32)daddr->s6_addr32[3];
 149         c += (__force u32)id;
 150         __jhash_mix(a, b, c);
 151
 152         return c & (IP6Q_HASHSZ - 1);
 153 }
 154
 155 static struct timer_list ip6_frag_secret_timer;
 156 int sysctl_ip6frag_secret_interval __read_mostly = 10 * 60 * HZ;
 157
 158 static void ip6_frag_secret_rebuild(unsigned long dummy)
 159 {
 160         unsigned long now = jiffies;
 161         int i;
 162
 163         write_lock(&ip6_frag_lock);
 164         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 165         for (i = 0; i < IP6Q_HASHSZ; i++) {
 166                 struct frag_queue *q;
 167                 struct hlist_node *p, *n;
 168
 169                 hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
 170                         unsigned int hval = ip6qhashfn(q->id,
 171                                                        &q->saddr,
 172                                                        &q->daddr);
 173
 174                         if (hval != i) {
 175                                 hlist_del(&q->list);
 176
 177                                 /* Relink to new hash chain. */
 178                                 hlist_add_head(&q->list,
 179                                                &ip6_frag_hash[hval]);
 180
 181                         }
 182                 }
 183         }
 184         write_unlock(&ip6_frag_lock);
 185
 186         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 187 }
 188
 189 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 190
 191 /* Memory Tracking Functions. */
 192 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 193 {
 194         if (work)
 195                 *work -= skb->truesize;
 196         atomic_sub(skb->truesize, &ip6_frag_mem);
 197         kfree_skb(skb);
 198 }
 199
 200 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 201 {
 202         if (work)
 203                 *work -= sizeof(struct frag_queue);
 204         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 205         kfree(fq);
 206 }
 207
 208 static inline struct frag_queue *frag_alloc_queue(void)
 209 {
 210         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 211
 212         if(!fq)
 213                 return NULL;
 214         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 215         return fq;
 216 }
 217
 218 /* Destruction primitives. */
 219
 220 /* Complete destruction of fq. */
 221 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 222 {
 223         struct sk_buff *fp;
 224
 225         BUG_TRAP(fq->last_in&COMPLETE);
 226         BUG_TRAP(del_timer(&fq->timer) == 0);
 227
 228         /* Release all fragment data. */
 229         fp = fq->fragments;
 230         while (fp) {
 231                 struct sk_buff *xp = fp->next;
 232
 233                 frag_kfree_skb(fp, work);
 234                 fp = xp;
 235         }
 236
 237         frag_free_queue(fq, work);
 238 }
 239
 240 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 241 {
 242         if (atomic_dec_and_test(&fq->refcnt))
 243                 ip6_frag_destroy(fq, work);
 244 }
 245
 246 /* Kill fq entry. It is not destroyed immediately,
 247  * because caller (and someone more) holds reference count.
 248  */
 249 static __inline__ void fq_kill(struct frag_queue *fq)
 250 {
 251         if (del_timer(&fq->timer))
 252                 atomic_dec(&fq->refcnt);
 253
 254         if (!(fq->last_in & COMPLETE)) {
 255                 fq_unlink(fq);
 256                 atomic_dec(&fq->refcnt);
 257                 fq->last_in |= COMPLETE;
 258         }
 259 }
 260
 261 static void ip6_evictor(struct inet6_dev *idev)
 262 {
 263         struct frag_queue *fq;
 264         struct list_head *tmp;
 265         int work;
 266
 267         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
 268         if (work <= 0)
 269                 return;
 270
 271         while(work > 0) {
 272                 read_lock(&ip6_frag_lock);
 273                 if (list_empty(&ip6_frag_lru_list)) {
 274                         read_unlock(&ip6_frag_lock);
 275                         return;
 276                 }
 277                 tmp = ip6_frag_lru_list.next;
 278                 fq = list_entry(tmp, struct frag_queue, lru_list);
 279                 atomic_inc(&fq->refcnt);
 280                 read_unlock(&ip6_frag_lock);
 281
 282                 spin_lock(&fq->lock);
 283                 if (!(fq->last_in&COMPLETE))
 284                         fq_kill(fq);
 285                 spin_unlock(&fq->lock);
 286
 287                 fq_put(fq, &work);
 288                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 289         }
 290 }
 291
 292 static void ip6_frag_expire(unsigned long data)
 293 {
 294         struct frag_queue *fq = (struct frag_queue *) data;
 295         struct net_device *dev = NULL;
 296
 297         spin_lock(&fq->lock);
 298
 299         if (fq->last_in & COMPLETE)
 300                 goto out;
 301
 302         fq_kill(fq);
 303
 304         dev = dev_get_by_index(fq->iif);
 305         if (!dev)
 306                 goto out;
 307
 308         rcu_read_lock();
 309         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 310         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 311         rcu_read_unlock();
 312
 313         /* Don't send error if the first segment did not arrive. */
 314         if (!(fq->last_in&FIRST_IN) || !fq->fragments)
 315                 goto out;
 316
 317         /*
 318            But use as source device on which LAST ARRIVED
 319            segment was received. And do not use fq->dev
 320            pointer directly, device might already disappeared.
 321          */
 322         fq->fragments->dev = dev;
 323         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 324 out:
 325         if (dev)
 326                 dev_put(dev);
 327         spin_unlock(&fq->lock);
 328         fq_put(fq, NULL);
 329 }
 330
 331 /* Creation primitives. */
 332
 333
 334 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
 335 {
 336         struct frag_queue *fq;
 337         unsigned int hash;
 338 #ifdef CONFIG_SMP
 339         struct hlist_node *n;
 340 #endif
 341
 342         write_lock(&ip6_frag_lock);
 343         hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
 344 #ifdef CONFIG_SMP
 345         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 346                 if (fq->id == fq_in->id &&
 347                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 348                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 349                         atomic_inc(&fq->refcnt);
 350                         write_unlock(&ip6_frag_lock);
 351                         fq_in->last_in |= COMPLETE;
 352                         fq_put(fq_in, NULL);
 353                         return fq;
 354                 }
 355         }
 356 #endif
 357         fq = fq_in;
 358
 359         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 360                 atomic_inc(&fq->refcnt);
 361
 362         atomic_inc(&fq->refcnt);
 363         hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
 364         INIT_LIST_HEAD(&fq->lru_list);
 365         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 366         ip6_frag_nqueues++;
 367         write_unlock(&ip6_frag_lock);
 368         return fq;
 369 }
 370
 371
 372 static struct frag_queue *
 373 ip6_frag_create(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 374                 struct inet6_dev *idev)
 375 {
 376         struct frag_queue *fq;
 377
 378         if ((fq = frag_alloc_queue()) == NULL)
 379                 goto oom;
 380
 381         fq->id = id;
 382         ipv6_addr_copy(&fq->saddr, src);
 383         ipv6_addr_copy(&fq->daddr, dst);
 384
 385         init_timer(&fq->timer);
 386         fq->timer.function = ip6_frag_expire;
 387         fq->timer.data = (long) fq;
 388         spin_lock_init(&fq->lock);
 389         atomic_set(&fq->refcnt, 1);
 390
 391         return ip6_frag_intern(fq);
 392
 393 oom:
 394         IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 395         return NULL;
 396 }
 397
 398 static __inline__ struct frag_queue *
 399 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 400         struct inet6_dev *idev)
 401 {
 402         struct frag_queue *fq;
 403         struct hlist_node *n;
 404         unsigned int hash;
 405
 406         read_lock(&ip6_frag_lock);
 407         hash = ip6qhashfn(id, src, dst);
 408         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 409                 if (fq->id == id &&
 410                     ipv6_addr_equal(src, &fq->saddr) &&
 411                     ipv6_addr_equal(dst, &fq->daddr)) {
 412                         atomic_inc(&fq->refcnt);
 413                         read_unlock(&ip6_frag_lock);
 414                         return fq;
 415                 }
 416         }
 417         read_unlock(&ip6_frag_lock);
 418
 419         return ip6_frag_create(id, src, dst, idev);
 420 }
 421
 422
 423 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 424                            struct frag_hdr *fhdr, int nhoff)
 425 {
 426         struct sk_buff *prev, *next;
 427         int offset, end;
 428
 429         if (fq->last_in & COMPLETE)
 430                 goto err;
 431
 432         offset = ntohs(fhdr->frag_off) & ~0x7;
 433         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
 434                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
 435
 436         if ((unsigned int)end > IPV6_MAXPLEN) {
 437                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 438                                  IPSTATS_MIB_INHDRERRORS);
 439                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
 440                 return;
 441         }
 442
 443         if (skb->ip_summed == CHECKSUM_COMPLETE)
 444                 skb->csum = csum_sub(skb->csum,
 445                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
 446
 447         /* Is this the final fragment? */
 448         if (!(fhdr->frag_off & htons(IP6_MF))) {
 449                 /* If we already have some bits beyond end
 450                  * or have different end, the segment is corrupted.
 451                  */
 452                 if (end < fq->len ||
 453                     ((fq->last_in & LAST_IN) && end != fq->len))
 454                         goto err;
 455                 fq->last_in |= LAST_IN;
 456                 fq->len = end;
 457         } else {
 458                 /* Check if the fragment is rounded to 8 bytes.
 459                  * Required by the RFC.
 460                  */
 461                 if (end & 0x7) {
 462                         /* RFC2460 says always send parameter problem in
 463                          * this case. -DaveM
 464                          */
 465                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 466                                          IPSTATS_MIB_INHDRERRORS);
 467                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 468                                           offsetof(struct ipv6hdr, payload_len));
 469                         return;
 470                 }
 471                 if (end > fq->len) {
 472                         /* Some bits beyond end -> corruption. */
 473                         if (fq->last_in & LAST_IN)
 474                                 goto err;
 475                         fq->len = end;
 476                 }
 477         }
 478
 479         if (end == offset)
 480                 goto err;
 481
 482         /* Point into the IP datagram 'data' part. */
 483         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 484                 goto err;
 485
 486         if (pskb_trim_rcsum(skb, end - offset))
 487                 goto err;
 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(ip6_dst_idev(skb->dst), 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                           struct net_device *dev)
 597 {
 598         struct sk_buff *fp, *head = fq->fragments;
 599         int    payload_len;
 600         unsigned int nhoff;
 601
 602         fq_kill(fq);
 603
 604         BUG_TRAP(head != NULL);
 605         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 606
 607         /* Unfragmented part is taken from the first segment. */
 608         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
 609         if (payload_len > IPV6_MAXPLEN)
 610                 goto out_oversize;
 611
 612         /* Head of list must not be cloned. */
 613         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 614                 goto out_oom;
 615
 616         /* If the first fragment is fragmented itself, we split
 617          * it to two chunks: the first with data and paged part
 618          * and the second, holding only fragments. */
 619         if (skb_shinfo(head)->frag_list) {
 620                 struct sk_buff *clone;
 621                 int i, plen = 0;
 622
 623                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 624                         goto out_oom;
 625                 clone->next = head->next;
 626                 head->next = clone;
 627                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 628                 skb_shinfo(head)->frag_list = NULL;
 629                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 630                         plen += skb_shinfo(head)->frags[i].size;
 631                 clone->len = clone->data_len = head->data_len - plen;
 632                 head->data_len -= clone->len;
 633                 head->len -= clone->len;
 634                 clone->csum = 0;
 635                 clone->ip_summed = head->ip_summed;
 636                 atomic_add(clone->truesize, &ip6_frag_mem);
 637         }
 638
 639         /* We have to remove fragment header from datagram and to relocate
 640          * header in order to calculate ICV correctly. */
 641         nhoff = fq->nhoffset;
 642         head->nh.raw[nhoff] = head->h.raw[0];
 643         memmove(head->head + sizeof(struct frag_hdr), head->head,
 644                 (head->data - head->head) - sizeof(struct frag_hdr));
 645         head->mac.raw += sizeof(struct frag_hdr);
 646         head->nh.raw += sizeof(struct frag_hdr);
 647
 648         skb_shinfo(head)->frag_list = head->next;
 649         head->h.raw = head->data;
 650         skb_push(head, head->data - head->nh.raw);
 651         atomic_sub(head->truesize, &ip6_frag_mem);
 652
 653         for (fp=head->next; fp; fp = fp->next) {
 654                 head->data_len += fp->len;
 655                 head->len += fp->len;
 656                 if (head->ip_summed != fp->ip_summed)
 657                         head->ip_summed = CHECKSUM_NONE;
 658                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 659                         head->csum = csum_add(head->csum, fp->csum);
 660                 head->truesize += fp->truesize;
 661                 atomic_sub(fp->truesize, &ip6_frag_mem);
 662         }
 663
 664         head->next = NULL;
 665         head->dev = dev;
 666         skb_set_timestamp(head, &fq->stamp);
 667         head->nh.ipv6h->payload_len = htons(payload_len);
 668         IP6CB(head)->nhoff = nhoff;
 669
 670         *skb_in = head;
 671
 672         /* Yes, and fold redundant checksum back. 8) */
 673         if (head->ip_summed == CHECKSUM_COMPLETE)
 674                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
 675
 676         rcu_read_lock();
 677         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 678         rcu_read_unlock();
 679         fq->fragments = NULL;
 680         return 1;
 681
 682 out_oversize:
 683         if (net_ratelimit())
 684                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 685         goto out_fail;
 686 out_oom:
 687         if (net_ratelimit())
 688                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 689 out_fail:
 690         rcu_read_lock();
 691         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 692         rcu_read_unlock();
 693         return -1;
 694 }
 695
 696 static int ipv6_frag_rcv(struct sk_buff **skbp)
 697 {
 698         struct sk_buff *skb = *skbp;
 699         struct net_device *dev = skb->dev;
 700         struct frag_hdr *fhdr;
 701         struct frag_queue *fq;
 702         struct ipv6hdr *hdr;
 703
 704         hdr = skb->nh.ipv6h;
 705
 706         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMREQDS);
 707
 708         /* Jumbo payload inhibits frag. header */
 709         if (hdr->payload_len==0) {
 710                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 711                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 712                 return -1;
 713         }
 714         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
 715                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 716                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 717                 return -1;
 718         }
 719
 720         hdr = skb->nh.ipv6h;
 721         fhdr = (struct frag_hdr *)skb->h.raw;
 722
 723         if (!(fhdr->frag_off & htons(0xFFF9))) {
 724                 /* It is not a fragmented frame */
 725                 skb->h.raw += sizeof(struct frag_hdr);
 726                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMOKS);
 727
 728                 IP6CB(skb)->nhoff = (u8*)fhdr - skb->nh.raw;
 729                 return 1;
 730         }
 731
 732         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 733                 ip6_evictor(ip6_dst_idev(skb->dst));
 734
 735         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr,
 736                           ip6_dst_idev(skb->dst))) != NULL) {
 737                 int ret = -1;
 738
 739                 spin_lock(&fq->lock);
 740
 741                 ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 742
 743                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
 744                     fq->meat == fq->len)
 745                         ret = ip6_frag_reasm(fq, skbp, dev);
 746
 747                 spin_unlock(&fq->lock);
 748                 fq_put(fq, NULL);
 749                 return ret;
 750         }
 751
 752         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 753         kfree_skb(skb);
 754         return -1;
 755 }
 756
 757 static struct inet6_protocol frag_protocol =
 758 {
 759         .handler        =       ipv6_frag_rcv,
 760         .flags          =       INET6_PROTO_NOPOLICY,
 761 };
 762
 763 void __init ipv6_frag_init(void)
 764 {
 765         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 766                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 767
 768         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 769                                    (jiffies ^ (jiffies >> 6)));
 770
 771         init_timer(&ip6_frag_secret_timer);
 772         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 773         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 774         add_timer(&ip6_frag_secret_timer);
 775 }