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   1 /*
   2  *      IPv6 fragment reassembly
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      $Id: reassembly.c,v 1.26 2001/03/07 22:00:57 davem Exp $
   9  *
  10  *      Based on: net/ipv4/ip_fragment.c
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 /*
  19  *      Fixes:
  20  *      Andi Kleen      Make it work with multiple hosts.
  21  *                      More RFC compliance.
  22  *
  23  *      Horst von Brand Add missing #include <linux/string.h>
  24  *      Alexey Kuznetsov        SMP races, threading, cleanup.
  25  *      Patrick McHardy         LRU queue of frag heads for evictor.
  26  *      Mitsuru KANDA @USAGI    Register inet6_protocol{}.
  27  *      David Stevens and
  28  *      YOSHIFUJI,H. @USAGI     Always remove fragment header to
  29  *                              calculate ICV correctly.
  30  */
  31 #include <linux/errno.h>
  32 #include <linux/types.h>
  33 #include <linux/string.h>
  34 #include <linux/socket.h>
  35 #include <linux/sockios.h>
  36 #include <linux/jiffies.h>
  37 #include <linux/net.h>
  38 #include <linux/list.h>
  39 #include <linux/netdevice.h>
  40 #include <linux/in6.h>
  41 #include <linux/ipv6.h>
  42 #include <linux/icmpv6.h>
  43 #include <linux/random.h>
  44 #include <linux/jhash.h>
  45 #include <linux/skbuff.h>
  46
  47 #include <net/sock.h>
  48 #include <net/snmp.h>
  49
  50 #include <net/ipv6.h>
  51 #include <net/ip6_route.h>
  52 #include <net/protocol.h>
  53 #include <net/transp_v6.h>
  54 #include <net/rawv6.h>
  55 #include <net/ndisc.h>
  56 #include <net/addrconf.h>
  57 #include <net/inet_frag.h>
  58
  59 struct ip6frag_skb_cb
  60 {
  61         struct inet6_skb_parm   h;
  62         int                     offset;
  63 };
  64
  65 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  66
  67
  68 /*
  69  *      Equivalent of ipv4 struct ipq
  70  */
  71
  72 struct frag_queue
  73 {
  74         struct inet_frag_queue  q;
  75
  76         __be32                  id;             /* fragment id          */
  77         struct in6_addr         saddr;
  78         struct in6_addr         daddr;
  79
  80         int                     iif;
  81         unsigned int            csum;
  82         __u16                   nhoffset;
  83 };
  84
  85 struct inet_frags_ctl ip6_frags_ctl __read_mostly = {
  86         .high_thresh     = 256 * 1024,
  87         .low_thresh      = 192 * 1024,
  88         .timeout         = IPV6_FRAG_TIMEOUT,
  89         .secret_interval = 10 * 60 * HZ,
  90 };
  91
  92 static struct inet_frags ip6_frags;
  93
  94 int ip6_frag_nqueues(void)
  95 {
  96         return ip6_frags.nqueues;
  97 }
  98
  99 int ip6_frag_mem(void)
 100 {
 101         return atomic_read(&ip6_frags.mem);
 102 }
 103
 104 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 105                           struct net_device *dev);
 106
 107 /*
 108  * callers should be careful not to use the hash value outside the ipfrag_lock
 109  * as doing so could race with ipfrag_hash_rnd being recalculated.
 110  */
 111 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
 112                                struct in6_addr *daddr)
 113 {
 114         u32 a, b, c;
 115
 116         a = (__force u32)saddr->s6_addr32[0];
 117         b = (__force u32)saddr->s6_addr32[1];
 118         c = (__force u32)saddr->s6_addr32[2];
 119
 120         a += JHASH_GOLDEN_RATIO;
 121         b += JHASH_GOLDEN_RATIO;
 122         c += ip6_frags.rnd;
 123         __jhash_mix(a, b, c);
 124
 125         a += (__force u32)saddr->s6_addr32[3];
 126         b += (__force u32)daddr->s6_addr32[0];
 127         c += (__force u32)daddr->s6_addr32[1];
 128         __jhash_mix(a, b, c);
 129
 130         a += (__force u32)daddr->s6_addr32[2];
 131         b += (__force u32)daddr->s6_addr32[3];
 132         c += (__force u32)id;
 133         __jhash_mix(a, b, c);
 134
 135         return c & (INETFRAGS_HASHSZ - 1);
 136 }
 137
 138 static void ip6_frag_secret_rebuild(unsigned long dummy)
 139 {
 140         unsigned long now = jiffies;
 141         int i;
 142
 143         write_lock(&ip6_frags.lock);
 144         get_random_bytes(&ip6_frags.rnd, sizeof(u32));
 145         for (i = 0; i < INETFRAGS_HASHSZ; i++) {
 146                 struct frag_queue *q;
 147                 struct hlist_node *p, *n;
 148
 149                 hlist_for_each_entry_safe(q, p, n, &ip6_frags.hash[i], q.list) {
 150                         unsigned int hval = ip6qhashfn(q->id,
 151                                                        &q->saddr,
 152                                                        &q->daddr);
 153
 154                         if (hval != i) {
 155                                 hlist_del(&q->q.list);
 156
 157                                 /* Relink to new hash chain. */
 158                                 hlist_add_head(&q->q.list,
 159                                                &ip6_frags.hash[hval]);
 160
 161                         }
 162                 }
 163         }
 164         write_unlock(&ip6_frags.lock);
 165
 166         mod_timer(&ip6_frags.secret_timer, now + ip6_frags_ctl.secret_interval);
 167 }
 168
 169 /* Memory Tracking Functions. */
 170 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 171 {
 172         if (work)
 173                 *work -= skb->truesize;
 174         atomic_sub(skb->truesize, &ip6_frags.mem);
 175         kfree_skb(skb);
 176 }
 177
 178 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 179 {
 180         if (work)
 181                 *work -= sizeof(struct frag_queue);
 182         atomic_sub(sizeof(struct frag_queue), &ip6_frags.mem);
 183         kfree(fq);
 184 }
 185
 186 static inline struct frag_queue *frag_alloc_queue(void)
 187 {
 188         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 189
 190         if(!fq)
 191                 return NULL;
 192         atomic_add(sizeof(struct frag_queue), &ip6_frags.mem);
 193         return fq;
 194 }
 195
 196 /* Destruction primitives. */
 197
 198 /* Complete destruction of fq. */
 199 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 200 {
 201         struct sk_buff *fp;
 202
 203         BUG_TRAP(fq->q.last_in&COMPLETE);
 204         BUG_TRAP(del_timer(&fq->q.timer) == 0);
 205
 206         /* Release all fragment data. */
 207         fp = fq->q.fragments;
 208         while (fp) {
 209                 struct sk_buff *xp = fp->next;
 210
 211                 frag_kfree_skb(fp, work);
 212                 fp = xp;
 213         }
 214
 215         frag_free_queue(fq, work);
 216 }
 217
 218 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 219 {
 220         if (atomic_dec_and_test(&fq->q.refcnt))
 221                 ip6_frag_destroy(fq, work);
 222 }
 223
 224 /* Kill fq entry. It is not destroyed immediately,
 225  * because caller (and someone more) holds reference count.
 226  */
 227 static __inline__ void fq_kill(struct frag_queue *fq)
 228 {
 229         inet_frag_kill(&fq->q, &ip6_frags);
 230 }
 231
 232 static void ip6_evictor(struct inet6_dev *idev)
 233 {
 234         struct frag_queue *fq;
 235         struct list_head *tmp;
 236         int work;
 237
 238         work = atomic_read(&ip6_frags.mem) - ip6_frags_ctl.low_thresh;
 239         if (work <= 0)
 240                 return;
 241
 242         while(work > 0) {
 243                 read_lock(&ip6_frags.lock);
 244                 if (list_empty(&ip6_frags.lru_list)) {
 245                         read_unlock(&ip6_frags.lock);
 246                         return;
 247                 }
 248                 tmp = ip6_frags.lru_list.next;
 249                 fq = list_entry(tmp, struct frag_queue, q.lru_list);
 250                 atomic_inc(&fq->q.refcnt);
 251                 read_unlock(&ip6_frags.lock);
 252
 253                 spin_lock(&fq->q.lock);
 254                 if (!(fq->q.last_in&COMPLETE))
 255                         fq_kill(fq);
 256                 spin_unlock(&fq->q.lock);
 257
 258                 fq_put(fq, &work);
 259                 IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 260         }
 261 }
 262
 263 static void ip6_frag_expire(unsigned long data)
 264 {
 265         struct frag_queue *fq = (struct frag_queue *) data;
 266         struct net_device *dev = NULL;
 267
 268         spin_lock(&fq->q.lock);
 269
 270         if (fq->q.last_in & COMPLETE)
 271                 goto out;
 272
 273         fq_kill(fq);
 274
 275         dev = dev_get_by_index(&init_net, fq->iif);
 276         if (!dev)
 277                 goto out;
 278
 279         rcu_read_lock();
 280         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 281         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 282         rcu_read_unlock();
 283
 284         /* Don't send error if the first segment did not arrive. */
 285         if (!(fq->q.last_in&FIRST_IN) || !fq->q.fragments)
 286                 goto out;
 287
 288         /*
 289            But use as source device on which LAST ARRIVED
 290            segment was received. And do not use fq->dev
 291            pointer directly, device might already disappeared.
 292          */
 293         fq->q.fragments->dev = dev;
 294         icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 295 out:
 296         if (dev)
 297                 dev_put(dev);
 298         spin_unlock(&fq->q.lock);
 299         fq_put(fq, NULL);
 300 }
 301
 302 /* Creation primitives. */
 303
 304
 305 static struct frag_queue *ip6_frag_intern(struct frag_queue *fq_in)
 306 {
 307         struct frag_queue *fq;
 308         unsigned int hash;
 309 #ifdef CONFIG_SMP
 310         struct hlist_node *n;
 311 #endif
 312
 313         write_lock(&ip6_frags.lock);
 314         hash = ip6qhashfn(fq_in->id, &fq_in->saddr, &fq_in->daddr);
 315 #ifdef CONFIG_SMP
 316         hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
 317                 if (fq->id == fq_in->id &&
 318                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 319                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 320                         atomic_inc(&fq->q.refcnt);
 321                         write_unlock(&ip6_frags.lock);
 322                         fq_in->q.last_in |= COMPLETE;
 323                         fq_put(fq_in, NULL);
 324                         return fq;
 325                 }
 326         }
 327 #endif
 328         fq = fq_in;
 329
 330         if (!mod_timer(&fq->q.timer, jiffies + ip6_frags_ctl.timeout))
 331                 atomic_inc(&fq->q.refcnt);
 332
 333         atomic_inc(&fq->q.refcnt);
 334         hlist_add_head(&fq->q.list, &ip6_frags.hash[hash]);
 335         INIT_LIST_HEAD(&fq->q.lru_list);
 336         list_add_tail(&fq->q.lru_list, &ip6_frags.lru_list);
 337         ip6_frags.nqueues++;
 338         write_unlock(&ip6_frags.lock);
 339         return fq;
 340 }
 341
 342
 343 static struct frag_queue *
 344 ip6_frag_create(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 345                 struct inet6_dev *idev)
 346 {
 347         struct frag_queue *fq;
 348
 349         if ((fq = frag_alloc_queue()) == NULL)
 350                 goto oom;
 351
 352         fq->id = id;
 353         ipv6_addr_copy(&fq->saddr, src);
 354         ipv6_addr_copy(&fq->daddr, dst);
 355
 356         init_timer(&fq->q.timer);
 357         fq->q.timer.function = ip6_frag_expire;
 358         fq->q.timer.data = (long) fq;
 359         spin_lock_init(&fq->q.lock);
 360         atomic_set(&fq->q.refcnt, 1);
 361
 362         return ip6_frag_intern(fq);
 363
 364 oom:
 365         IP6_INC_STATS_BH(idev, IPSTATS_MIB_REASMFAILS);
 366         return NULL;
 367 }
 368
 369 static __inline__ struct frag_queue *
 370 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst,
 371         struct inet6_dev *idev)
 372 {
 373         struct frag_queue *fq;
 374         struct hlist_node *n;
 375         unsigned int hash;
 376
 377         read_lock(&ip6_frags.lock);
 378         hash = ip6qhashfn(id, src, dst);
 379         hlist_for_each_entry(fq, n, &ip6_frags.hash[hash], q.list) {
 380                 if (fq->id == id &&
 381                     ipv6_addr_equal(src, &fq->saddr) &&
 382                     ipv6_addr_equal(dst, &fq->daddr)) {
 383                         atomic_inc(&fq->q.refcnt);
 384                         read_unlock(&ip6_frags.lock);
 385                         return fq;
 386                 }
 387         }
 388         read_unlock(&ip6_frags.lock);
 389
 390         return ip6_frag_create(id, src, dst, idev);
 391 }
 392
 393
 394 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 395                            struct frag_hdr *fhdr, int nhoff)
 396 {
 397         struct sk_buff *prev, *next;
 398         struct net_device *dev;
 399         int offset, end;
 400
 401         if (fq->q.last_in & COMPLETE)
 402                 goto err;
 403
 404         offset = ntohs(fhdr->frag_off) & ~0x7;
 405         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 406                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 407
 408         if ((unsigned int)end > IPV6_MAXPLEN) {
 409                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 410                                  IPSTATS_MIB_INHDRERRORS);
 411                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 412                                   ((u8 *)&fhdr->frag_off -
 413                                    skb_network_header(skb)));
 414                 return -1;
 415         }
 416
 417         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 418                 const unsigned char *nh = skb_network_header(skb);
 419                 skb->csum = csum_sub(skb->csum,
 420                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 421                                                   0));
 422         }
 423
 424         /* Is this the final fragment? */
 425         if (!(fhdr->frag_off & htons(IP6_MF))) {
 426                 /* If we already have some bits beyond end
 427                  * or have different end, the segment is corrupted.
 428                  */
 429                 if (end < fq->q.len ||
 430                     ((fq->q.last_in & LAST_IN) && end != fq->q.len))
 431                         goto err;
 432                 fq->q.last_in |= LAST_IN;
 433                 fq->q.len = end;
 434         } else {
 435                 /* Check if the fragment is rounded to 8 bytes.
 436                  * Required by the RFC.
 437                  */
 438                 if (end & 0x7) {
 439                         /* RFC2460 says always send parameter problem in
 440                          * this case. -DaveM
 441                          */
 442                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 443                                          IPSTATS_MIB_INHDRERRORS);
 444                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 445                                           offsetof(struct ipv6hdr, payload_len));
 446                         return -1;
 447                 }
 448                 if (end > fq->q.len) {
 449                         /* Some bits beyond end -> corruption. */
 450                         if (fq->q.last_in & LAST_IN)
 451                                 goto err;
 452                         fq->q.len = end;
 453                 }
 454         }
 455
 456         if (end == offset)
 457                 goto err;
 458
 459         /* Point into the IP datagram 'data' part. */
 460         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 461                 goto err;
 462
 463         if (pskb_trim_rcsum(skb, end - offset))
 464                 goto err;
 465
 466         /* Find out which fragments are in front and at the back of us
 467          * in the chain of fragments so far.  We must know where to put
 468          * this fragment, right?
 469          */
 470         prev = NULL;
 471         for(next = fq->q.fragments; next != NULL; next = next->next) {
 472                 if (FRAG6_CB(next)->offset >= offset)
 473                         break;  /* bingo! */
 474                 prev = next;
 475         }
 476
 477         /* We found where to put this one.  Check for overlap with
 478          * preceding fragment, and, if needed, align things so that
 479          * any overlaps are eliminated.
 480          */
 481         if (prev) {
 482                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 483
 484                 if (i > 0) {
 485                         offset += i;
 486                         if (end <= offset)
 487                                 goto err;
 488                         if (!pskb_pull(skb, i))
 489                                 goto err;
 490                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 491                                 skb->ip_summed = CHECKSUM_NONE;
 492                 }
 493         }
 494
 495         /* Look for overlap with succeeding segments.
 496          * If we can merge fragments, do it.
 497          */
 498         while (next && FRAG6_CB(next)->offset < end) {
 499                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 500
 501                 if (i < next->len) {
 502                         /* Eat head of the next overlapped fragment
 503                          * and leave the loop. The next ones cannot overlap.
 504                          */
 505                         if (!pskb_pull(next, i))
 506                                 goto err;
 507                         FRAG6_CB(next)->offset += i;    /* next fragment */
 508                         fq->q.meat -= i;
 509                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 510                                 next->ip_summed = CHECKSUM_NONE;
 511                         break;
 512                 } else {
 513                         struct sk_buff *free_it = next;
 514
 515                         /* Old fragment is completely overridden with
 516                          * new one drop it.
 517                          */
 518                         next = next->next;
 519
 520                         if (prev)
 521                                 prev->next = next;
 522                         else
 523                                 fq->q.fragments = next;
 524
 525                         fq->q.meat -= free_it->len;
 526                         frag_kfree_skb(free_it, NULL);
 527                 }
 528         }
 529
 530         FRAG6_CB(skb)->offset = offset;
 531
 532         /* Insert this fragment in the chain of fragments. */
 533         skb->next = next;
 534         if (prev)
 535                 prev->next = skb;
 536         else
 537                 fq->q.fragments = skb;
 538
 539         dev = skb->dev;
 540         if (dev) {
 541                 fq->iif = dev->ifindex;
 542                 skb->dev = NULL;
 543         }
 544         fq->q.stamp = skb->tstamp;
 545         fq->q.meat += skb->len;
 546         atomic_add(skb->truesize, &ip6_frags.mem);
 547
 548         /* The first fragment.
 549          * nhoffset is obtained from the first fragment, of course.
 550          */
 551         if (offset == 0) {
 552                 fq->nhoffset = nhoff;
 553                 fq->q.last_in |= FIRST_IN;
 554         }
 555
 556         if (fq->q.last_in == (FIRST_IN | LAST_IN) && fq->q.meat == fq->q.len)
 557                 return ip6_frag_reasm(fq, prev, dev);
 558
 559         write_lock(&ip6_frags.lock);
 560         list_move_tail(&fq->q.lru_list, &ip6_frags.lru_list);
 561         write_unlock(&ip6_frags.lock);
 562         return -1;
 563
 564 err:
 565         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMFAILS);
 566         kfree_skb(skb);
 567         return -1;
 568 }
 569
 570 /*
 571  *      Check if this packet is complete.
 572  *      Returns NULL on failure by any reason, and pointer
 573  *      to current nexthdr field in reassembled frame.
 574  *
 575  *      It is called with locked fq, and caller must check that
 576  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 577  *      the last and the first frames arrived and all the bits are here.
 578  */
 579 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 580                           struct net_device *dev)
 581 {
 582         struct sk_buff *fp, *head = fq->q.fragments;
 583         int    payload_len;
 584         unsigned int nhoff;
 585
 586         fq_kill(fq);
 587
 588         /* Make the one we just received the head. */
 589         if (prev) {
 590                 head = prev->next;
 591                 fp = skb_clone(head, GFP_ATOMIC);
 592
 593                 if (!fp)
 594                         goto out_oom;
 595
 596                 fp->next = head->next;
 597                 prev->next = fp;
 598
 599                 skb_morph(head, fq->q.fragments);
 600                 head->next = fq->q.fragments->next;
 601
 602                 kfree_skb(fq->q.fragments);
 603                 fq->q.fragments = head;
 604         }
 605
 606         BUG_TRAP(head != NULL);
 607         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 608
 609         /* Unfragmented part is taken from the first segment. */
 610         payload_len = ((head->data - skb_network_header(head)) -
 611                        sizeof(struct ipv6hdr) + fq->q.len -
 612                        sizeof(struct frag_hdr));
 613         if (payload_len > IPV6_MAXPLEN)
 614                 goto out_oversize;
 615
 616         /* Head of list must not be cloned. */
 617         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 618                 goto out_oom;
 619
 620         /* If the first fragment is fragmented itself, we split
 621          * it to two chunks: the first with data and paged part
 622          * and the second, holding only fragments. */
 623         if (skb_shinfo(head)->frag_list) {
 624                 struct sk_buff *clone;
 625                 int i, plen = 0;
 626
 627                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 628                         goto out_oom;
 629                 clone->next = head->next;
 630                 head->next = clone;
 631                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 632                 skb_shinfo(head)->frag_list = NULL;
 633                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 634                         plen += skb_shinfo(head)->frags[i].size;
 635                 clone->len = clone->data_len = head->data_len - plen;
 636                 head->data_len -= clone->len;
 637                 head->len -= clone->len;
 638                 clone->csum = 0;
 639                 clone->ip_summed = head->ip_summed;
 640                 atomic_add(clone->truesize, &ip6_frags.mem);
 641         }
 642
 643         /* We have to remove fragment header from datagram and to relocate
 644          * header in order to calculate ICV correctly. */
 645         nhoff = fq->nhoffset;
 646         skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
 647         memmove(head->head + sizeof(struct frag_hdr), head->head,
 648                 (head->data - head->head) - sizeof(struct frag_hdr));
 649         head->mac_header += sizeof(struct frag_hdr);
 650         head->network_header += sizeof(struct frag_hdr);
 651
 652         skb_shinfo(head)->frag_list = head->next;
 653         skb_reset_transport_header(head);
 654         skb_push(head, head->data - skb_network_header(head));
 655         atomic_sub(head->truesize, &ip6_frags.mem);
 656
 657         for (fp=head->next; fp; fp = fp->next) {
 658                 head->data_len += fp->len;
 659                 head->len += fp->len;
 660                 if (head->ip_summed != fp->ip_summed)
 661                         head->ip_summed = CHECKSUM_NONE;
 662                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 663                         head->csum = csum_add(head->csum, fp->csum);
 664                 head->truesize += fp->truesize;
 665                 atomic_sub(fp->truesize, &ip6_frags.mem);
 666         }
 667
 668         head->next = NULL;
 669         head->dev = dev;
 670         head->tstamp = fq->q.stamp;
 671         ipv6_hdr(head)->payload_len = htons(payload_len);
 672         IP6CB(head)->nhoff = nhoff;
 673
 674         /* Yes, and fold redundant checksum back. 8) */
 675         if (head->ip_summed == CHECKSUM_COMPLETE)
 676                 head->csum = csum_partial(skb_network_header(head),
 677                                           skb_network_header_len(head),
 678                                           head->csum);
 679
 680         rcu_read_lock();
 681         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 682         rcu_read_unlock();
 683         fq->q.fragments = NULL;
 684         return 1;
 685
 686 out_oversize:
 687         if (net_ratelimit())
 688                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 689         goto out_fail;
 690 out_oom:
 691         if (net_ratelimit())
 692                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 693 out_fail:
 694         rcu_read_lock();
 695         IP6_INC_STATS_BH(__in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 696         rcu_read_unlock();
 697         return -1;
 698 }
 699
 700 static int ipv6_frag_rcv(struct sk_buff **skbp)
 701 {
 702         struct sk_buff *skb = *skbp;
 703         struct frag_hdr *fhdr;
 704         struct frag_queue *fq;
 705         struct ipv6hdr *hdr = ipv6_hdr(skb);
 706
 707         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMREQDS);
 708
 709         /* Jumbo payload inhibits frag. header */
 710         if (hdr->payload_len==0) {
 711                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 712                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 713                                   skb_network_header_len(skb));
 714                 return -1;
 715         }
 716         if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
 717                                  sizeof(struct frag_hdr)))) {
 718                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 719                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 720                                   skb_network_header_len(skb));
 721                 return -1;
 722         }
 723
 724         hdr = ipv6_hdr(skb);
 725         fhdr = (struct frag_hdr *)skb_transport_header(skb);
 726
 727         if (!(fhdr->frag_off & htons(0xFFF9))) {
 728                 /* It is not a fragmented frame */
 729                 skb->transport_header += sizeof(struct frag_hdr);
 730                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_REASMOKS);
 731
 732                 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
 733                 return 1;
 734         }
 735
 736         if (atomic_read(&ip6_frags.mem) > ip6_frags_ctl.high_thresh)
 737                 ip6_evictor(ip6_dst_idev(skb->dst));
 738
 739         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr,
 740                           ip6_dst_idev(skb->dst))) != NULL) {
 741                 int ret;
 742
 743                 spin_lock(&fq->q.lock);
 744
 745                 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 746
 747                 spin_unlock(&fq->q.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         init_timer(&ip6_frags.secret_timer);
 769         ip6_frags.secret_timer.function = ip6_frag_secret_rebuild;
 770         ip6_frags.secret_timer.expires = jiffies + ip6_frags_ctl.secret_interval;
 771         add_timer(&ip6_frags.secret_timer);
 772
 773         ip6_frags.ctl = &ip6_frags_ctl;
 774         inet_frags_init(&ip6_frags);
 775 }