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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 hlist_node       list;
  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 };
  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 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
 125                                struct in6_addr *daddr)
 126 {
 127         u32 a, b, c;
 128
 129         a = saddr->s6_addr32[0];
 130         b = saddr->s6_addr32[1];
 131         c = saddr->s6_addr32[2];
 132
 133         a += JHASH_GOLDEN_RATIO;
 134         b += JHASH_GOLDEN_RATIO;
 135         c += ip6_frag_hash_rnd;
 136         __jhash_mix(a, b, c);
 137
 138         a += saddr->s6_addr32[3];
 139         b += daddr->s6_addr32[0];
 140         c += daddr->s6_addr32[1];
 141         __jhash_mix(a, b, c);
 142
 143         a += daddr->s6_addr32[2];
 144         b += daddr->s6_addr32[3];
 145         c += id;
 146         __jhash_mix(a, b, c);
 147
 148         return c & (IP6Q_HASHSZ - 1);
 149 }
 150
 151 static struct timer_list ip6_frag_secret_timer;
 152 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
 153
 154 static void ip6_frag_secret_rebuild(unsigned long dummy)
 155 {
 156         unsigned long now = jiffies;
 157         int i;
 158
 159         write_lock(&ip6_frag_lock);
 160         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 161         for (i = 0; i < IP6Q_HASHSZ; i++) {
 162                 struct frag_queue *q;
 163                 struct hlist_node *p, *n;
 164
 165                 hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
 166                         unsigned int hval = ip6qhashfn(q->id,
 167                                                        &q->saddr,
 168                                                        &q->daddr);
 169
 170                         if (hval != i) {
 171                                 hlist_del(&q->list);
 172
 173                                 /* Relink to new hash chain. */
 174                                 hlist_add_head(&q->list,
 175                                                &ip6_frag_hash[hval]);
 176
 177                         }
 178                 }
 179         }
 180         write_unlock(&ip6_frag_lock);
 181
 182         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 183 }
 184
 185 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 186
 187 /* Memory Tracking Functions. */
 188 static inline void frag_kfree_skb(struct sk_buff *skb, int *work)
 189 {
 190         if (work)
 191                 *work -= skb->truesize;
 192         atomic_sub(skb->truesize, &ip6_frag_mem);
 193         kfree_skb(skb);
 194 }
 195
 196 static inline void frag_free_queue(struct frag_queue *fq, int *work)
 197 {
 198         if (work)
 199                 *work -= sizeof(struct frag_queue);
 200         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 201         kfree(fq);
 202 }
 203
 204 static inline struct frag_queue *frag_alloc_queue(void)
 205 {
 206         struct frag_queue *fq = kzalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 207
 208         if(!fq)
 209                 return NULL;
 210         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 211         return fq;
 212 }
 213
 214 /* Destruction primitives. */
 215
 216 /* Complete destruction of fq. */
 217 static void ip6_frag_destroy(struct frag_queue *fq, int *work)
 218 {
 219         struct sk_buff *fp;
 220
 221         BUG_TRAP(fq->last_in&COMPLETE);
 222         BUG_TRAP(del_timer(&fq->timer) == 0);
 223
 224         /* Release all fragment data. */
 225         fp = fq->fragments;
 226         while (fp) {
 227                 struct sk_buff *xp = fp->next;
 228
 229                 frag_kfree_skb(fp, work);
 230                 fp = xp;
 231         }
 232
 233         frag_free_queue(fq, work);
 234 }
 235
 236 static __inline__ void fq_put(struct frag_queue *fq, int *work)
 237 {
 238         if (atomic_dec_and_test(&fq->refcnt))
 239                 ip6_frag_destroy(fq, work);
 240 }
 241
 242 /* Kill fq entry. It is not destroyed immediately,
 243  * because caller (and someone more) holds reference count.
 244  */
 245 static __inline__ void fq_kill(struct frag_queue *fq)
 246 {
 247         if (del_timer(&fq->timer))
 248                 atomic_dec(&fq->refcnt);
 249
 250         if (!(fq->last_in & COMPLETE)) {
 251                 fq_unlink(fq);
 252                 atomic_dec(&fq->refcnt);
 253                 fq->last_in |= COMPLETE;
 254         }
 255 }
 256
 257 static void ip6_evictor(void)
 258 {
 259         struct frag_queue *fq;
 260         struct list_head *tmp;
 261         int work;
 262
 263         work = atomic_read(&ip6_frag_mem) - sysctl_ip6frag_low_thresh;
 264         if (work <= 0)
 265                 return;
 266
 267         while(work > 0) {
 268                 read_lock(&ip6_frag_lock);
 269                 if (list_empty(&ip6_frag_lru_list)) {
 270                         read_unlock(&ip6_frag_lock);
 271                         return;
 272                 }
 273                 tmp = ip6_frag_lru_list.next;
 274                 fq = list_entry(tmp, struct frag_queue, lru_list);
 275                 atomic_inc(&fq->refcnt);
 276                 read_unlock(&ip6_frag_lock);
 277
 278                 spin_lock(&fq->lock);
 279                 if (!(fq->last_in&COMPLETE))
 280                         fq_kill(fq);
 281                 spin_unlock(&fq->lock);
 282
 283                 fq_put(fq, &work);
 284                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 285         }
 286 }
 287
 288 static void ip6_frag_expire(unsigned long data)
 289 {
 290         struct frag_queue *fq = (struct frag_queue *) data;
 291         struct net_device *dev;
 292
 293         spin_lock(&fq->lock);
 294
 295         if (fq->last_in & COMPLETE)
 296                 goto out;
 297
 298         fq_kill(fq);
 299
 300         IP6_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
 301         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 302
 303         /* Don't send error if the first segment did not arrive. */
 304         if (!(fq->last_in&FIRST_IN) || !fq->fragments)
 305                 goto out;
 306
 307         dev = dev_get_by_index(fq->iif);
 308         if (!dev)
 309                 goto out;
 310
 311         /*
 312            But use as source device on which LAST ARRIVED
 313            segment was received. And do not use fq->dev
 314            pointer directly, device might already disappeared.
 315          */
 316         fq->fragments->dev = dev;
 317         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 318         dev_put(dev);
 319 out:
 320         spin_unlock(&fq->lock);
 321         fq_put(fq, NULL);
 322 }
 323
 324 /* Creation primitives. */
 325
 326
 327 static struct frag_queue *ip6_frag_intern(unsigned int hash,
 328                                           struct frag_queue *fq_in)
 329 {
 330         struct frag_queue *fq;
 331 #ifdef CONFIG_SMP
 332         struct hlist_node *n;
 333 #endif
 334
 335         write_lock(&ip6_frag_lock);
 336 #ifdef CONFIG_SMP
 337         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 338                 if (fq->id == fq_in->id &&
 339                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 340                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 341                         atomic_inc(&fq->refcnt);
 342                         write_unlock(&ip6_frag_lock);
 343                         fq_in->last_in |= COMPLETE;
 344                         fq_put(fq_in, NULL);
 345                         return fq;
 346                 }
 347         }
 348 #endif
 349         fq = fq_in;
 350
 351         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 352                 atomic_inc(&fq->refcnt);
 353
 354         atomic_inc(&fq->refcnt);
 355         hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
 356         INIT_LIST_HEAD(&fq->lru_list);
 357         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 358         ip6_frag_nqueues++;
 359         write_unlock(&ip6_frag_lock);
 360         return fq;
 361 }
 362
 363
 364 static struct frag_queue *
 365 ip6_frag_create(unsigned int hash, u32 id, struct in6_addr *src, struct in6_addr *dst)
 366 {
 367         struct frag_queue *fq;
 368
 369         if ((fq = frag_alloc_queue()) == NULL)
 370                 goto oom;
 371
 372         fq->id = id;
 373         ipv6_addr_copy(&fq->saddr, src);
 374         ipv6_addr_copy(&fq->daddr, dst);
 375
 376         init_timer(&fq->timer);
 377         fq->timer.function = ip6_frag_expire;
 378         fq->timer.data = (long) fq;
 379         spin_lock_init(&fq->lock);
 380         atomic_set(&fq->refcnt, 1);
 381
 382         return ip6_frag_intern(hash, fq);
 383
 384 oom:
 385         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 386         return NULL;
 387 }
 388
 389 static __inline__ struct frag_queue *
 390 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
 391 {
 392         struct frag_queue *fq;
 393         struct hlist_node *n;
 394         unsigned int hash = ip6qhashfn(id, src, dst);
 395
 396         read_lock(&ip6_frag_lock);
 397         hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
 398                 if (fq->id == id &&
 399                     ipv6_addr_equal(src, &fq->saddr) &&
 400                     ipv6_addr_equal(dst, &fq->daddr)) {
 401                         atomic_inc(&fq->refcnt);
 402                         read_unlock(&ip6_frag_lock);
 403                         return fq;
 404                 }
 405         }
 406         read_unlock(&ip6_frag_lock);
 407
 408         return ip6_frag_create(hash, id, src, dst);
 409 }
 410
 411
 412 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 413                            struct frag_hdr *fhdr, int nhoff)
 414 {
 415         struct sk_buff *prev, *next;
 416         int offset, end;
 417
 418         if (fq->last_in & COMPLETE)
 419                 goto err;
 420
 421         offset = ntohs(fhdr->frag_off) & ~0x7;
 422         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
 423                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
 424
 425         if ((unsigned int)end > IPV6_MAXPLEN) {
 426                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 427                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
 428                 return;
 429         }
 430
 431         if (skb->ip_summed == CHECKSUM_HW)
 432                 skb->csum = csum_sub(skb->csum,
 433                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
 434
 435         /* Is this the final fragment? */
 436         if (!(fhdr->frag_off & htons(IP6_MF))) {
 437                 /* If we already have some bits beyond end
 438                  * or have different end, the segment is corrupted.
 439                  */
 440                 if (end < fq->len ||
 441                     ((fq->last_in & LAST_IN) && end != fq->len))
 442                         goto err;
 443                 fq->last_in |= LAST_IN;
 444                 fq->len = end;
 445         } else {
 446                 /* Check if the fragment is rounded to 8 bytes.
 447                  * Required by the RFC.
 448                  */
 449                 if (end & 0x7) {
 450                         /* RFC2460 says always send parameter problem in
 451                          * this case. -DaveM
 452                          */
 453                         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 454                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 455                                           offsetof(struct ipv6hdr, payload_len));
 456                         return;
 457                 }
 458                 if (end > fq->len) {
 459                         /* Some bits beyond end -> corruption. */
 460                         if (fq->last_in & LAST_IN)
 461                                 goto err;
 462                         fq->len = end;
 463                 }
 464         }
 465
 466         if (end == offset)
 467                 goto err;
 468
 469         /* Point into the IP datagram 'data' part. */
 470         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 471                 goto err;
 472
 473         if (pskb_trim_rcsum(skb, end - offset))
 474                 goto err;
 475
 476         /* Find out which fragments are in front and at the back of us
 477          * in the chain of fragments so far.  We must know where to put
 478          * this fragment, right?
 479          */
 480         prev = NULL;
 481         for(next = fq->fragments; next != NULL; next = next->next) {
 482                 if (FRAG6_CB(next)->offset >= offset)
 483                         break;  /* bingo! */
 484                 prev = next;
 485         }
 486
 487         /* We found where to put this one.  Check for overlap with
 488          * preceding fragment, and, if needed, align things so that
 489          * any overlaps are eliminated.
 490          */
 491         if (prev) {
 492                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 493
 494                 if (i > 0) {
 495                         offset += i;
 496                         if (end <= offset)
 497                                 goto err;
 498                         if (!pskb_pull(skb, i))
 499                                 goto err;
 500                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 501                                 skb->ip_summed = CHECKSUM_NONE;
 502                 }
 503         }
 504
 505         /* Look for overlap with succeeding segments.
 506          * If we can merge fragments, do it.
 507          */
 508         while (next && FRAG6_CB(next)->offset < end) {
 509                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 510
 511                 if (i < next->len) {
 512                         /* Eat head of the next overlapped fragment
 513                          * and leave the loop. The next ones cannot overlap.
 514                          */
 515                         if (!pskb_pull(next, i))
 516                                 goto err;
 517                         FRAG6_CB(next)->offset += i;    /* next fragment */
 518                         fq->meat -= i;
 519                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 520                                 next->ip_summed = CHECKSUM_NONE;
 521                         break;
 522                 } else {
 523                         struct sk_buff *free_it = next;
 524
 525                         /* Old fragment is completely overridden with
 526                          * new one drop it.
 527                          */
 528                         next = next->next;
 529
 530                         if (prev)
 531                                 prev->next = next;
 532                         else
 533                                 fq->fragments = next;
 534
 535                         fq->meat -= free_it->len;
 536                         frag_kfree_skb(free_it, NULL);
 537                 }
 538         }
 539
 540         FRAG6_CB(skb)->offset = offset;
 541
 542         /* Insert this fragment in the chain of fragments. */
 543         skb->next = next;
 544         if (prev)
 545                 prev->next = skb;
 546         else
 547                 fq->fragments = skb;
 548
 549         if (skb->dev)
 550                 fq->iif = skb->dev->ifindex;
 551         skb->dev = NULL;
 552         skb_get_timestamp(skb, &fq->stamp);
 553         fq->meat += skb->len;
 554         atomic_add(skb->truesize, &ip6_frag_mem);
 555
 556         /* The first fragment.
 557          * nhoffset is obtained from the first fragment, of course.
 558          */
 559         if (offset == 0) {
 560                 fq->nhoffset = nhoff;
 561                 fq->last_in |= FIRST_IN;
 562         }
 563         write_lock(&ip6_frag_lock);
 564         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
 565         write_unlock(&ip6_frag_lock);
 566         return;
 567
 568 err:
 569         IP6_INC_STATS(IPSTATS_MIB_REASMFAILS);
 570         kfree_skb(skb);
 571 }
 572
 573 /*
 574  *      Check if this packet is complete.
 575  *      Returns NULL on failure by any reason, and pointer
 576  *      to current nexthdr field in reassembled frame.
 577  *
 578  *      It is called with locked fq, and caller must check that
 579  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 580  *      the last and the first frames arrived and all the bits are here.
 581  */
 582 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
 583                           struct net_device *dev)
 584 {
 585         struct sk_buff *fp, *head = fq->fragments;
 586         int    payload_len;
 587         unsigned int nhoff;
 588
 589         fq_kill(fq);
 590
 591         BUG_TRAP(head != NULL);
 592         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 593
 594         /* Unfragmented part is taken from the first segment. */
 595         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
 596         if (payload_len > IPV6_MAXPLEN)
 597                 goto out_oversize;
 598
 599         /* Head of list must not be cloned. */
 600         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 601                 goto out_oom;
 602
 603         /* If the first fragment is fragmented itself, we split
 604          * it to two chunks: the first with data and paged part
 605          * and the second, holding only fragments. */
 606         if (skb_shinfo(head)->frag_list) {
 607                 struct sk_buff *clone;
 608                 int i, plen = 0;
 609
 610                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 611                         goto out_oom;
 612                 clone->next = head->next;
 613                 head->next = clone;
 614                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 615                 skb_shinfo(head)->frag_list = NULL;
 616                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 617                         plen += skb_shinfo(head)->frags[i].size;
 618                 clone->len = clone->data_len = head->data_len - plen;
 619                 head->data_len -= clone->len;
 620                 head->len -= clone->len;
 621                 clone->csum = 0;
 622                 clone->ip_summed = head->ip_summed;
 623                 atomic_add(clone->truesize, &ip6_frag_mem);
 624         }
 625
 626         /* We have to remove fragment header from datagram and to relocate
 627          * header in order to calculate ICV correctly. */
 628         nhoff = fq->nhoffset;
 629         head->nh.raw[nhoff] = head->h.raw[0];
 630         memmove(head->head + sizeof(struct frag_hdr), head->head,
 631                 (head->data - head->head) - sizeof(struct frag_hdr));
 632         head->mac.raw += sizeof(struct frag_hdr);
 633         head->nh.raw += sizeof(struct frag_hdr);
 634
 635         skb_shinfo(head)->frag_list = head->next;
 636         head->h.raw = head->data;
 637         skb_push(head, head->data - head->nh.raw);
 638         atomic_sub(head->truesize, &ip6_frag_mem);
 639
 640         for (fp=head->next; fp; fp = fp->next) {
 641                 head->data_len += fp->len;
 642                 head->len += fp->len;
 643                 if (head->ip_summed != fp->ip_summed)
 644                         head->ip_summed = CHECKSUM_NONE;
 645                 else if (head->ip_summed == CHECKSUM_HW)
 646                         head->csum = csum_add(head->csum, fp->csum);
 647                 head->truesize += fp->truesize;
 648                 atomic_sub(fp->truesize, &ip6_frag_mem);
 649         }
 650
 651         head->next = NULL;
 652         head->dev = dev;
 653         skb_set_timestamp(head, &fq->stamp);
 654         head->nh.ipv6h->payload_len = htons(payload_len);
 655         IP6CB(head)->nhoff = nhoff;
 656
 657         *skb_in = head;
 658
 659         /* Yes, and fold redundant checksum back. 8) */
 660         if (head->ip_summed == CHECKSUM_HW)
 661                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
 662
 663         IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 664         fq->fragments = NULL;
 665         return 1;
 666
 667 out_oversize:
 668         if (net_ratelimit())
 669                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 670         goto out_fail;
 671 out_oom:
 672         if (net_ratelimit())
 673                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 674 out_fail:
 675         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 676         return -1;
 677 }
 678
 679 static int ipv6_frag_rcv(struct sk_buff **skbp)
 680 {
 681         struct sk_buff *skb = *skbp;
 682         struct net_device *dev = skb->dev;
 683         struct frag_hdr *fhdr;
 684         struct frag_queue *fq;
 685         struct ipv6hdr *hdr;
 686
 687         hdr = skb->nh.ipv6h;
 688
 689         IP6_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
 690
 691         /* Jumbo payload inhibits frag. header */
 692         if (hdr->payload_len==0) {
 693                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 694                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 695                 return -1;
 696         }
 697         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
 698                 IP6_INC_STATS(IPSTATS_MIB_INHDRERRORS);
 699                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 700                 return -1;
 701         }
 702
 703         hdr = skb->nh.ipv6h;
 704         fhdr = (struct frag_hdr *)skb->h.raw;
 705
 706         if (!(fhdr->frag_off & htons(0xFFF9))) {
 707                 /* It is not a fragmented frame */
 708                 skb->h.raw += sizeof(struct frag_hdr);
 709                 IP6_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
 710
 711                 IP6CB(skb)->nhoff = (u8*)fhdr - skb->nh.raw;
 712                 return 1;
 713         }
 714
 715         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 716                 ip6_evictor();
 717
 718         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
 719                 int ret = -1;
 720
 721                 spin_lock(&fq->lock);
 722
 723                 ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
 724
 725                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
 726                     fq->meat == fq->len)
 727                         ret = ip6_frag_reasm(fq, skbp, dev);
 728
 729                 spin_unlock(&fq->lock);
 730                 fq_put(fq, NULL);
 731                 return ret;
 732         }
 733
 734         IP6_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 735         kfree_skb(skb);
 736         return -1;
 737 }
 738
 739 static struct inet6_protocol frag_protocol =
 740 {
 741         .handler        =       ipv6_frag_rcv,
 742         .flags          =       INET6_PROTO_NOPOLICY,
 743 };
 744
 745 void __init ipv6_frag_init(void)
 746 {
 747         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 748                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 749
 750         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 751                                    (jiffies ^ (jiffies >> 6)));
 752
 753         init_timer(&ip6_frag_secret_timer);
 754         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 755         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 756         add_timer(&ip6_frag_secret_timer);
 757 }