net/ipv6/reassembly.c

   1 /*
   2  *      IPv6 fragment reassembly
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      $Id: reassembly.c,v 1.26 2001/03/07 22:00:57 davem Exp $
   9  *
  10  *      Based on: net/ipv4/ip_fragment.c
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 /*
  19  *      Fixes:
  20  *      Andi Kleen      Make it work with multiple hosts.
  21  *                      More RFC compliance.
  22  *
  23  *      Horst von Brand Add missing #include <linux/string.h>
  24  *      Alexey Kuznetsov        SMP races, threading, cleanup.
  25  *      Patrick McHardy         LRU queue of frag heads for evictor.
  26  *      Mitsuru KANDA @USAGI    Register inet6_protocol{}.
  27  *      David Stevens and
  28  *      YOSHIFUJI,H. @USAGI     Always remove fragment header to
  29  *                              calculate ICV correctly.
  30  */
  31 #include <linux/config.h>
  32 #include <linux/errno.h>
  33 #include <linux/types.h>
  34 #include <linux/string.h>
  35 #include <linux/socket.h>
  36 #include <linux/sockios.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/net.h>
  39 #include <linux/list.h>
  40 #include <linux/netdevice.h>
  41 #include <linux/in6.h>
  42 #include <linux/ipv6.h>
  43 #include <linux/icmpv6.h>
  44 #include <linux/random.h>
  45 #include <linux/jhash.h>
  46
  47 #include <net/sock.h>
  48 #include <net/snmp.h>
  49
  50 #include <net/ipv6.h>
  51 #include <net/protocol.h>
  52 #include <net/transp_v6.h>
  53 #include <net/rawv6.h>
  54 #include <net/ndisc.h>
  55 #include <net/addrconf.h>
  56
  57 int sysctl_ip6frag_high_thresh = 256*1024;
  58 int sysctl_ip6frag_low_thresh = 192*1024;
  59
  60 int sysctl_ip6frag_time = IPV6_FRAG_TIMEOUT;
  61
  62 struct ip6frag_skb_cb
  63 {
  64         struct inet6_skb_parm   h;
  65         int                     offset;
  66 };
  67
  68 #define FRAG6_CB(skb)   ((struct ip6frag_skb_cb*)((skb)->cb))
  69
  70
  71 /*
  72  *      Equivalent of ipv4 struct ipq
  73  */
  74
  75 struct frag_queue
  76 {
  77         struct frag_queue       *next;
  78         struct list_head lru_list;              /* lru list member      */
  79
  80         __u32                   id;             /* fragment id          */
  81         struct in6_addr         saddr;
  82         struct in6_addr         daddr;
  83
  84         spinlock_t              lock;
  85         atomic_t                refcnt;
  86         struct timer_list       timer;          /* expire timer         */
  87         struct sk_buff          *fragments;
  88         int                     len;
  89         int                     meat;
  90         int                     iif;
  91         struct timeval          stamp;
  92         unsigned int            csum;
  93         __u8                    last_in;        /* has first/last segment arrived? */
  94 #define COMPLETE                4
  95 #define FIRST_IN                2
  96 #define LAST_IN                 1
  97         __u16                   nhoffset;
  98         struct frag_queue       **pprev;
  99 };
 100
 101 /* Hash table. */
 102
 103 #define IP6Q_HASHSZ     64
 104
 105 static struct frag_queue *ip6_frag_hash[IP6Q_HASHSZ];
 106 static rwlock_t ip6_frag_lock = RW_LOCK_UNLOCKED;
 107 static u32 ip6_frag_hash_rnd;
 108 static LIST_HEAD(ip6_frag_lru_list);
 109 int ip6_frag_nqueues = 0;
 110
 111 static __inline__ void __fq_unlink(struct frag_queue *fq)
 112 {
 113         if(fq->next)
 114                 fq->next->pprev = fq->pprev;
 115         *fq->pprev = fq->next;
 116         list_del(&fq->lru_list);
 117         ip6_frag_nqueues--;
 118 }
 119
 120 static __inline__ void fq_unlink(struct frag_queue *fq)
 121 {
 122         write_lock(&ip6_frag_lock);
 123         __fq_unlink(fq);
 124         write_unlock(&ip6_frag_lock);
 125 }
 126
 127 static unsigned int ip6qhashfn(u32 id, struct in6_addr *saddr,
 128                                struct in6_addr *daddr)
 129 {
 130         u32 a, b, c;
 131
 132         a = saddr->s6_addr32[0];
 133         b = saddr->s6_addr32[1];
 134         c = saddr->s6_addr32[2];
 135
 136         a += JHASH_GOLDEN_RATIO;
 137         b += JHASH_GOLDEN_RATIO;
 138         c += ip6_frag_hash_rnd;
 139         __jhash_mix(a, b, c);
 140
 141         a += saddr->s6_addr32[3];
 142         b += daddr->s6_addr32[0];
 143         c += daddr->s6_addr32[1];
 144         __jhash_mix(a, b, c);
 145
 146         a += daddr->s6_addr32[2];
 147         b += daddr->s6_addr32[3];
 148         c += id;
 149         __jhash_mix(a, b, c);
 150
 151         return c & (IP6Q_HASHSZ - 1);
 152 }
 153
 154 static struct timer_list ip6_frag_secret_timer;
 155 int sysctl_ip6frag_secret_interval = 10 * 60 * HZ;
 156
 157 static void ip6_frag_secret_rebuild(unsigned long dummy)
 158 {
 159         unsigned long now = jiffies;
 160         int i;
 161
 162         write_lock(&ip6_frag_lock);
 163         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
 164         for (i = 0; i < IP6Q_HASHSZ; i++) {
 165                 struct frag_queue *q;
 166
 167                 q = ip6_frag_hash[i];
 168                 while (q) {
 169                         struct frag_queue *next = q->next;
 170                         unsigned int hval = ip6qhashfn(q->id,
 171                                                        &q->saddr,
 172                                                        &q->daddr);
 173
 174                         if (hval != i) {
 175                                 /* Unlink. */
 176                                 if (q->next)
 177                                         q->next->pprev = q->pprev;
 178                                 *q->pprev = q->next;
 179
 180                                 /* Relink to new hash chain. */
 181                                 if ((q->next = ip6_frag_hash[hval]) != NULL)
 182                                         q->next->pprev = &q->next;
 183                                 ip6_frag_hash[hval] = q;
 184                                 q->pprev = &ip6_frag_hash[hval];
 185                         }
 186
 187                         q = next;
 188                 }
 189         }
 190         write_unlock(&ip6_frag_lock);
 191
 192         mod_timer(&ip6_frag_secret_timer, now + sysctl_ip6frag_secret_interval);
 193 }
 194
 195 atomic_t ip6_frag_mem = ATOMIC_INIT(0);
 196
 197 /* Memory Tracking Functions. */
 198 static inline void frag_kfree_skb(struct sk_buff *skb)
 199 {
 200         atomic_sub(skb->truesize, &ip6_frag_mem);
 201         kfree_skb(skb);
 202 }
 203
 204 static inline void frag_free_queue(struct frag_queue *fq)
 205 {
 206         atomic_sub(sizeof(struct frag_queue), &ip6_frag_mem);
 207         kfree(fq);
 208 }
 209
 210 static inline struct frag_queue *frag_alloc_queue(void)
 211 {
 212         struct frag_queue *fq = kmalloc(sizeof(struct frag_queue), GFP_ATOMIC);
 213
 214         if(!fq)
 215                 return NULL;
 216         atomic_add(sizeof(struct frag_queue), &ip6_frag_mem);
 217         return fq;
 218 }
 219
 220 /* Destruction primitives. */
 221
 222 /* Complete destruction of fq. */
 223 static void ip6_frag_destroy(struct frag_queue *fq)
 224 {
 225         struct sk_buff *fp;
 226
 227         BUG_TRAP(fq->last_in&COMPLETE);
 228         BUG_TRAP(del_timer(&fq->timer) == 0);
 229
 230         /* Release all fragment data. */
 231         fp = fq->fragments;
 232         while (fp) {
 233                 struct sk_buff *xp = fp->next;
 234
 235                 frag_kfree_skb(fp);
 236                 fp = xp;
 237         }
 238
 239         frag_free_queue(fq);
 240 }
 241
 242 static __inline__ void fq_put(struct frag_queue *fq)
 243 {
 244         if (atomic_dec_and_test(&fq->refcnt))
 245                 ip6_frag_destroy(fq);
 246 }
 247
 248 /* Kill fq entry. It is not destroyed immediately,
 249  * because caller (and someone more) holds reference count.
 250  */
 251 static __inline__ void fq_kill(struct frag_queue *fq)
 252 {
 253         if (del_timer(&fq->timer))
 254                 atomic_dec(&fq->refcnt);
 255
 256         if (!(fq->last_in & COMPLETE)) {
 257                 fq_unlink(fq);
 258                 atomic_dec(&fq->refcnt);
 259                 fq->last_in |= COMPLETE;
 260         }
 261 }
 262
 263 static void ip6_evictor(void)
 264 {
 265         struct frag_queue *fq;
 266         struct list_head *tmp;
 267
 268         for(;;) {
 269                 if (atomic_read(&ip6_frag_mem) <= sysctl_ip6frag_low_thresh)
 270                         return;
 271                 read_lock(&ip6_frag_lock);
 272                 if (list_empty(&ip6_frag_lru_list)) {
 273                         read_unlock(&ip6_frag_lock);
 274                         return;
 275                 }
 276                 tmp = ip6_frag_lru_list.next;
 277                 fq = list_entry(tmp, struct frag_queue, lru_list);
 278                 atomic_inc(&fq->refcnt);
 279                 read_unlock(&ip6_frag_lock);
 280
 281                 spin_lock(&fq->lock);
 282                 if (!(fq->last_in&COMPLETE))
 283                         fq_kill(fq);
 284                 spin_unlock(&fq->lock);
 285
 286                 fq_put(fq);
 287                 IP6_INC_STATS_BH(ReasmFails);
 288         }
 289 }
 290
 291 static void ip6_frag_expire(unsigned long data)
 292 {
 293         struct frag_queue *fq = (struct frag_queue *) data;
 294
 295         spin_lock(&fq->lock);
 296
 297         if (fq->last_in & COMPLETE)
 298                 goto out;
 299
 300         fq_kill(fq);
 301
 302         IP6_INC_STATS_BH(ReasmTimeout);
 303         IP6_INC_STATS_BH(ReasmFails);
 304
 305         /* Send error only if the first segment arrived. */
 306         if (fq->last_in&FIRST_IN && fq->fragments) {
 307                 struct net_device *dev = dev_get_by_index(fq->iif);
 308
 309                 /*
 310                    But use as source device on which LAST ARRIVED
 311                    segment was received. And do not use fq->dev
 312                    pointer directly, device might already disappeared.
 313                  */
 314                 if (dev) {
 315                         fq->fragments->dev = dev;
 316                         icmpv6_send(fq->fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0,
 317                                     dev);
 318                         dev_put(dev);
 319                 }
 320         }
 321 out:
 322         spin_unlock(&fq->lock);
 323         fq_put(fq);
 324 }
 325
 326 /* Creation primitives. */
 327
 328
 329 static struct frag_queue *ip6_frag_intern(unsigned int hash,
 330                                           struct frag_queue *fq_in)
 331 {
 332         struct frag_queue *fq;
 333
 334         write_lock(&ip6_frag_lock);
 335 #ifdef CONFIG_SMP
 336         for (fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
 337                 if (fq->id == fq_in->id &&
 338                     !ipv6_addr_cmp(&fq_in->saddr, &fq->saddr) &&
 339                     !ipv6_addr_cmp(&fq_in->daddr, &fq->daddr)) {
 340                         atomic_inc(&fq->refcnt);
 341                         write_unlock(&ip6_frag_lock);
 342                         fq_in->last_in |= COMPLETE;
 343                         fq_put(fq_in);
 344                         return fq;
 345                 }
 346         }
 347 #endif
 348         fq = fq_in;
 349
 350         if (!mod_timer(&fq->timer, jiffies + sysctl_ip6frag_time))
 351                 atomic_inc(&fq->refcnt);
 352
 353         atomic_inc(&fq->refcnt);
 354         if((fq->next = ip6_frag_hash[hash]) != NULL)
 355                 fq->next->pprev = &fq->next;
 356         ip6_frag_hash[hash] = fq;
 357         fq->pprev = &ip6_frag_hash[hash];
 358         INIT_LIST_HEAD(&fq->lru_list);
 359         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
 360         ip6_frag_nqueues++;
 361         write_unlock(&ip6_frag_lock);
 362         return fq;
 363 }
 364
 365
 366 static struct frag_queue *
 367 ip6_frag_create(unsigned int hash, u32 id, struct in6_addr *src, struct in6_addr *dst)
 368 {
 369         struct frag_queue *fq;
 370
 371         if ((fq = frag_alloc_queue()) == NULL)
 372                 goto oom;
 373
 374         memset(fq, 0, sizeof(struct frag_queue));
 375
 376         fq->id = id;
 377         ipv6_addr_copy(&fq->saddr, src);
 378         ipv6_addr_copy(&fq->daddr, dst);
 379
 380         init_timer(&fq->timer);
 381         fq->timer.function = ip6_frag_expire;
 382         fq->timer.data = (long) fq;
 383         fq->lock = SPIN_LOCK_UNLOCKED;
 384         atomic_set(&fq->refcnt, 1);
 385
 386         return ip6_frag_intern(hash, fq);
 387
 388 oom:
 389         IP6_INC_STATS_BH(ReasmFails);
 390         return NULL;
 391 }
 392
 393 static __inline__ struct frag_queue *
 394 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
 395 {
 396         struct frag_queue *fq;
 397         unsigned int hash = ip6qhashfn(id, src, dst);
 398
 399         read_lock(&ip6_frag_lock);
 400         for(fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
 401                 if (fq->id == id &&
 402                     !ipv6_addr_cmp(src, &fq->saddr) &&
 403                     !ipv6_addr_cmp(dst, &fq->daddr)) {
 404                         atomic_inc(&fq->refcnt);
 405                         read_unlock(&ip6_frag_lock);
 406                         return fq;
 407                 }
 408         }
 409         read_unlock(&ip6_frag_lock);
 410
 411         return ip6_frag_create(hash, id, src, dst);
 412 }
 413
 414
 415 static void ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 416                            struct frag_hdr *fhdr, int nhoff)
 417 {
 418         struct sk_buff *prev, *next;
 419         int offset, end;
 420
 421         if (fq->last_in & COMPLETE)
 422                 goto err;
 423
 424         offset = ntohs(fhdr->frag_off) & ~0x7;
 425         end = offset + (ntohs(skb->nh.ipv6h->payload_len) -
 426                         ((u8 *) (fhdr + 1) - (u8 *) (skb->nh.ipv6h + 1)));
 427
 428         if ((unsigned int)end > IPV6_MAXPLEN) {
 429                 IP6_INC_STATS_BH(InHdrErrors);
 430                 icmpv6_param_prob(skb,ICMPV6_HDR_FIELD, (u8*)&fhdr->frag_off - skb->nh.raw);
 431                 return;
 432         }
 433
 434         if (skb->ip_summed == CHECKSUM_HW)
 435                 skb->csum = csum_sub(skb->csum,
 436                                      csum_partial(skb->nh.raw, (u8*)(fhdr+1)-skb->nh.raw, 0));
 437
 438         /* Is this the final fragment? */
 439         if (!(fhdr->frag_off & htons(IP6_MF))) {
 440                 /* If we already have some bits beyond end
 441                  * or have different end, the segment is corrupted.
 442                  */
 443                 if (end < fq->len ||
 444                     ((fq->last_in & LAST_IN) && end != fq->len))
 445                         goto err;
 446                 fq->last_in |= LAST_IN;
 447                 fq->len = end;
 448         } else {
 449                 /* Check if the fragment is rounded to 8 bytes.
 450                  * Required by the RFC.
 451                  */
 452                 if (end & 0x7) {
 453                         /* RFC2460 says always send parameter problem in
 454                          * this case. -DaveM
 455                          */
 456                         IP6_INC_STATS_BH(InHdrErrors);
 457                         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 458                                           offsetof(struct ipv6hdr, payload_len));
 459                         return;
 460                 }
 461                 if (end > fq->len) {
 462                         /* Some bits beyond end -> corruption. */
 463                         if (fq->last_in & LAST_IN)
 464                                 goto err;
 465                         fq->len = end;
 466                 }
 467         }
 468
 469         if (end == offset)
 470                 goto err;
 471
 472         /* Point into the IP datagram 'data' part. */
 473         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 474                 goto err;
 475         if (end-offset < skb->len) {
 476                 if (pskb_trim(skb, end - offset))
 477                         goto err;
 478                 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 479                         skb->ip_summed = CHECKSUM_NONE;
 480         }
 481
 482         /* Find out which fragments are in front and at the back of us
 483          * in the chain of fragments so far.  We must know where to put
 484          * this fragment, right?
 485          */
 486         prev = NULL;
 487         for(next = fq->fragments; next != NULL; next = next->next) {
 488                 if (FRAG6_CB(next)->offset >= offset)
 489                         break;  /* bingo! */
 490                 prev = next;
 491         }
 492
 493         /* We found where to put this one.  Check for overlap with
 494          * preceding fragment, and, if needed, align things so that
 495          * any overlaps are eliminated.
 496          */
 497         if (prev) {
 498                 int i = (FRAG6_CB(prev)->offset + prev->len) - offset;
 499
 500                 if (i > 0) {
 501                         offset += i;
 502                         if (end <= offset)
 503                                 goto err;
 504                         if (!pskb_pull(skb, i))
 505                                 goto err;
 506                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 507                                 skb->ip_summed = CHECKSUM_NONE;
 508                 }
 509         }
 510
 511         /* Look for overlap with succeeding segments.
 512          * If we can merge fragments, do it.
 513          */
 514         while (next && FRAG6_CB(next)->offset < end) {
 515                 int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */
 516
 517                 if (i < next->len) {
 518                         /* Eat head of the next overlapped fragment
 519                          * and leave the loop. The next ones cannot overlap.
 520                          */
 521                         if (!pskb_pull(next, i))
 522                                 goto err;
 523                         FRAG6_CB(next)->offset += i;    /* next fragment */
 524                         fq->meat -= i;
 525                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 526                                 next->ip_summed = CHECKSUM_NONE;
 527                         break;
 528                 } else {
 529                         struct sk_buff *free_it = next;
 530
 531                         /* Old fragment is completely overridden with
 532                          * new one drop it.
 533                          */
 534                         next = next->next;
 535
 536                         if (prev)
 537                                 prev->next = next;
 538                         else
 539                                 fq->fragments = next;
 540
 541                         fq->meat -= free_it->len;
 542                         frag_kfree_skb(free_it);
 543                 }
 544         }
 545
 546         FRAG6_CB(skb)->offset = offset;
 547
 548         /* Insert this fragment in the chain of fragments. */
 549         skb->next = next;
 550         if (prev)
 551                 prev->next = skb;
 552         else
 553                 fq->fragments = skb;
 554
 555         if (skb->dev)
 556                 fq->iif = skb->dev->ifindex;
 557         skb->dev = NULL;
 558         fq->stamp = skb->stamp;
 559         fq->meat += skb->len;
 560         atomic_add(skb->truesize, &ip6_frag_mem);
 561
 562         /* The first fragment.
 563          * nhoffset is obtained from the first fragment, of course.
 564          */
 565         if (offset == 0) {
 566                 fq->nhoffset = nhoff;
 567                 fq->last_in |= FIRST_IN;
 568         }
 569         write_lock(&ip6_frag_lock);
 570         list_move_tail(&fq->lru_list, &ip6_frag_lru_list);
 571         write_unlock(&ip6_frag_lock);
 572         return;
 573
 574 err:
 575         IP6_INC_STATS(ReasmFails);
 576         kfree_skb(skb);
 577 }
 578
 579 /*
 580  *      Check if this packet is complete.
 581  *      Returns NULL on failure by any reason, and pointer
 582  *      to current nexthdr field in reassembled frame.
 583  *
 584  *      It is called with locked fq, and caller must check that
 585  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 586  *      the last and the first frames arrived and all the bits are here.
 587  */
 588 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff **skb_in,
 589                           unsigned int *nhoffp,
 590                           struct net_device *dev)
 591 {
 592         struct sk_buff *fp, *head = fq->fragments;
 593         int    payload_len;
 594         unsigned int nhoff;
 595
 596         fq_kill(fq);
 597
 598         BUG_TRAP(head != NULL);
 599         BUG_TRAP(FRAG6_CB(head)->offset == 0);
 600
 601         /* Unfragmented part is taken from the first segment. */
 602         payload_len = (head->data - head->nh.raw) - sizeof(struct ipv6hdr) + fq->len - sizeof(struct frag_hdr);
 603         if (payload_len > IPV6_MAXPLEN)
 604                 goto out_oversize;
 605
 606         /* Head of list must not be cloned. */
 607         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 608                 goto out_oom;
 609
 610         /* If the first fragment is fragmented itself, we split
 611          * it to two chunks: the first with data and paged part
 612          * and the second, holding only fragments. */
 613         if (skb_shinfo(head)->frag_list) {
 614                 struct sk_buff *clone;
 615                 int i, plen = 0;
 616
 617                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 618                         goto out_oom;
 619                 clone->next = head->next;
 620                 head->next = clone;
 621                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 622                 skb_shinfo(head)->frag_list = NULL;
 623                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 624                         plen += skb_shinfo(head)->frags[i].size;
 625                 clone->len = clone->data_len = head->data_len - plen;
 626                 head->data_len -= clone->len;
 627                 head->len -= clone->len;
 628                 clone->csum = 0;
 629                 clone->ip_summed = head->ip_summed;
 630                 atomic_add(clone->truesize, &ip6_frag_mem);
 631         }
 632
 633         /* We have to remove fragment header from datagram and to relocate
 634          * header in order to calculate ICV correctly. */
 635         nhoff = fq->nhoffset;
 636         head->nh.raw[nhoff] = head->h.raw[0];
 637         memmove(head->head + sizeof(struct frag_hdr), head->head,
 638                 (head->data - head->head) - sizeof(struct frag_hdr));
 639         head->mac.raw += sizeof(struct frag_hdr);
 640         head->nh.raw += sizeof(struct frag_hdr);
 641
 642         skb_shinfo(head)->frag_list = head->next;
 643         head->h.raw = head->data;
 644         skb_push(head, head->data - head->nh.raw);
 645         atomic_sub(head->truesize, &ip6_frag_mem);
 646
 647         for (fp=head->next; fp; fp = fp->next) {
 648                 head->data_len += fp->len;
 649                 head->len += fp->len;
 650                 if (head->ip_summed != fp->ip_summed)
 651                         head->ip_summed = CHECKSUM_NONE;
 652                 else if (head->ip_summed == CHECKSUM_HW)
 653                         head->csum = csum_add(head->csum, fp->csum);
 654                 head->truesize += fp->truesize;
 655                 atomic_sub(fp->truesize, &ip6_frag_mem);
 656         }
 657
 658         head->next = NULL;
 659         head->dev = dev;
 660         head->stamp = fq->stamp;
 661         head->nh.ipv6h->payload_len = ntohs(payload_len);
 662
 663         *skb_in = head;
 664
 665         /* Yes, and fold redundant checksum back. 8) */
 666         if (head->ip_summed == CHECKSUM_HW)
 667                 head->csum = csum_partial(head->nh.raw, head->h.raw-head->nh.raw, head->csum);
 668
 669         IP6_INC_STATS_BH(ReasmOKs);
 670         fq->fragments = NULL;
 671         *nhoffp = nhoff;
 672         return 1;
 673
 674 out_oversize:
 675         if (net_ratelimit())
 676                 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 677         goto out_fail;
 678 out_oom:
 679         if (net_ratelimit())
 680                 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 681 out_fail:
 682         IP6_INC_STATS_BH(ReasmFails);
 683         return -1;
 684 }
 685
 686 static int ipv6_frag_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
 687 {
 688         struct sk_buff *skb = *skbp;
 689         struct net_device *dev = skb->dev;
 690         struct frag_hdr *fhdr;
 691         struct frag_queue *fq;
 692         struct ipv6hdr *hdr;
 693
 694         hdr = skb->nh.ipv6h;
 695
 696         IP6_INC_STATS_BH(ReasmReqds);
 697
 698         /* Jumbo payload inhibits frag. header */
 699         if (hdr->payload_len==0) {
 700                 IP6_INC_STATS(InHdrErrors);
 701                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 702                 return -1;
 703         }
 704         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+sizeof(struct frag_hdr))) {
 705                 IP6_INC_STATS(InHdrErrors);
 706                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb->h.raw-skb->nh.raw);
 707                 return -1;
 708         }
 709
 710         hdr = skb->nh.ipv6h;
 711         fhdr = (struct frag_hdr *)skb->h.raw;
 712
 713         if (!(fhdr->frag_off & htons(0xFFF9))) {
 714                 /* It is not a fragmented frame */
 715                 skb->h.raw += sizeof(struct frag_hdr);
 716                 IP6_INC_STATS_BH(ReasmOKs);
 717
 718                 *nhoffp = (u8*)fhdr - skb->nh.raw;
 719                 return 1;
 720         }
 721
 722         if (atomic_read(&ip6_frag_mem) > sysctl_ip6frag_high_thresh)
 723                 ip6_evictor();
 724
 725         if ((fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr)) != NULL) {
 726                 int ret = -1;
 727
 728                 spin_lock(&fq->lock);
 729
 730                 ip6_frag_queue(fq, skb, fhdr, *nhoffp);
 731
 732                 if (fq->last_in == (FIRST_IN|LAST_IN) &&
 733                     fq->meat == fq->len)
 734                         ret = ip6_frag_reasm(fq, skbp, nhoffp, dev);
 735
 736                 spin_unlock(&fq->lock);
 737                 fq_put(fq);
 738                 return ret;
 739         }
 740
 741         IP6_INC_STATS_BH(ReasmFails);
 742         kfree_skb(skb);
 743         return -1;
 744 }
 745
 746 static struct inet6_protocol frag_protocol =
 747 {
 748         .handler        =       ipv6_frag_rcv,
 749         .flags          =       INET6_PROTO_NOPOLICY,
 750 };
 751
 752 void __init ipv6_frag_init(void)
 753 {
 754         if (inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT) < 0)
 755                 printk(KERN_ERR "ipv6_frag_init: Could not register protocol\n");
 756
 757         ip6_frag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 758                                    (jiffies ^ (jiffies >> 6)));
 759
 760         init_timer(&ip6_frag_secret_timer);
 761         ip6_frag_secret_timer.function = ip6_frag_secret_rebuild;
 762         ip6_frag_secret_timer.expires = jiffies + sysctl_ip6frag_secret_interval;
 763         add_timer(&ip6_frag_secret_timer);
 764 }