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