net/ipv4/ip_fragment.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              The IP fragmentation functionality.
   7  *
   8  * Version:     $Id: ip_fragment.c,v 1.58.2.1 2002/01/12 07:53:15 davem Exp $
   9  *
  10  * Authors:     Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
  11  *              Alan Cox <Alan.Cox@linux.org>
  12  *
  13  * Fixes:
  14  *              Alan Cox        :       Split from ip.c , see ip_input.c for history.
  15  *              David S. Miller :       Begin massive cleanup...
  16  *              Andi Kleen      :       Add sysctls.
  17  *              xxxx            :       Overlapfrag bug.
  18  *              Ultima          :       ip_expire() kernel panic.
  19  *              Bill Hawes      :       Frag accounting and evictor fixes.
  20  *              John McDonald   :       0 length frag bug.
  21  *              Alexey Kuznetsov:       SMP races, threading, cleanup.
  22  *              Patrick McHardy :       LRU queue of frag heads for evictor.
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/types.h>
  27 #include <linux/mm.h>
  28 #include <linux/sched.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/list.h>
  31 #include <linux/ip.h>
  32 #include <linux/icmp.h>
  33 #include <linux/netdevice.h>
  34 #include <linux/jhash.h>
  35 #include <linux/random.h>
  36 #include <net/sock.h>
  37 #include <net/ip.h>
  38 #include <net/icmp.h>
  39 #include <net/checksum.h>
  40 #include <linux/tcp.h>
  41 #include <linux/udp.h>
  42 #include <linux/inet.h>
  43 #include <linux/netfilter_ipv4.h>
  44
  45 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
  46  * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
  47  * as well. Or notify me, at least. --ANK
  48  */
  49
  50 /* Fragment cache limits. We will commit 256K at one time. Should we
  51  * cross that limit we will prune down to 192K. This should cope with
  52  * even the most extreme cases without allowing an attacker to measurably
  53  * harm machine performance.
  54  */
  55 int sysctl_ipfrag_high_thresh = 256*1024;
  56 int sysctl_ipfrag_low_thresh = 192*1024;
  57
  58 /* Important NOTE! Fragment queue must be destroyed before MSL expires.
  59  * RFC791 is wrong proposing to prolongate timer each fragment arrival by TTL.
  60  */
  61 int sysctl_ipfrag_time = IP_FRAG_TIME;
  62
  63 struct ipfrag_skb_cb
  64 {
  65         struct inet_skb_parm    h;
  66         int                     offset;
  67 };
  68
  69 #define FRAG_CB(skb)    ((struct ipfrag_skb_cb*)((skb)->cb))
  70
  71 /* Describe an entry in the "incomplete datagrams" queue. */
  72 struct ipq {
  73         struct ipq      *next;          /* linked list pointers                 */
  74         struct list_head lru_list;      /* lru list member                      */
  75         u32             user;
  76         u32             saddr;
  77         u32             daddr;
  78         u16             id;
  79         u8              protocol;
  80         u8              last_in;
  81 #define COMPLETE                4
  82 #define FIRST_IN                2
  83 #define LAST_IN                 1
  84
  85         struct sk_buff  *fragments;     /* linked list of received fragments    */
  86         int             len;            /* total length of original datagram    */
  87         int             meat;
  88         spinlock_t      lock;
  89         atomic_t        refcnt;
  90         struct timer_list timer;        /* when will this queue expire?         */
  91         struct ipq      **pprev;
  92         int             iif;
  93         struct timeval  stamp;
  94 };
  95
  96 /* Hash table. */
  97
  98 #define IPQ_HASHSZ      64
  99
 100 /* Per-bucket lock is easy to add now. */
 101 static struct ipq *ipq_hash[IPQ_HASHSZ];
 102 static rwlock_t ipfrag_lock = RW_LOCK_UNLOCKED;
 103 static u32 ipfrag_hash_rnd;
 104 static LIST_HEAD(ipq_lru_list);
 105 int ip_frag_nqueues = 0;
 106
 107 static __inline__ void __ipq_unlink(struct ipq *qp)
 108 {
 109         if(qp->next)
 110                 qp->next->pprev = qp->pprev;
 111         *qp->pprev = qp->next;
 112         list_del(&qp->lru_list);
 113         ip_frag_nqueues--;
 114 }
 115
 116 static __inline__ void ipq_unlink(struct ipq *ipq)
 117 {
 118         write_lock(&ipfrag_lock);
 119         __ipq_unlink(ipq);
 120         write_unlock(&ipfrag_lock);
 121 }
 122
 123 static unsigned int ipqhashfn(u16 id, u32 saddr, u32 daddr, u8 prot)
 124 {
 125         return jhash_3words((u32)id << 16 | prot, saddr, daddr,
 126                             ipfrag_hash_rnd) & (IPQ_HASHSZ - 1);
 127 }
 128
 129 static struct timer_list ipfrag_secret_timer;
 130 int sysctl_ipfrag_secret_interval = 10 * 60 * HZ;
 131
 132 static void ipfrag_secret_rebuild(unsigned long dummy)
 133 {
 134         unsigned long now = jiffies;
 135         int i;
 136
 137         write_lock(&ipfrag_lock);
 138         get_random_bytes(&ipfrag_hash_rnd, sizeof(u32));
 139         for (i = 0; i < IPQ_HASHSZ; i++) {
 140                 struct ipq *q;
 141
 142                 q = ipq_hash[i];
 143                 while (q) {
 144                         struct ipq *next = q->next;
 145                         unsigned int hval = ipqhashfn(q->id, q->saddr,
 146                                                       q->daddr, q->protocol);
 147
 148                         if (hval != i) {
 149                                 /* Unlink. */
 150                                 if (q->next)
 151                                         q->next->pprev = q->pprev;
 152                                 *q->pprev = q->next;
 153
 154                                 /* Relink to new hash chain. */
 155                                 if ((q->next = ipq_hash[hval]) != NULL)
 156                                         q->next->pprev = &q->next;
 157                                 ipq_hash[hval] = q;
 158                                 q->pprev = &ipq_hash[hval];
 159                         }
 160
 161                         q = next;
 162                 }
 163         }
 164         write_unlock(&ipfrag_lock);
 165
 166         mod_timer(&ipfrag_secret_timer, now + sysctl_ipfrag_secret_interval);
 167 }
 168
 169 atomic_t ip_frag_mem = ATOMIC_INIT(0);  /* Memory used for fragments */
 170
 171 /* Memory Tracking Functions. */
 172 static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work)
 173 {
 174         if (work)
 175                 *work -= skb->truesize;
 176         atomic_sub(skb->truesize, &ip_frag_mem);
 177         kfree_skb(skb);
 178 }
 179
 180 static __inline__ void frag_free_queue(struct ipq *qp, int *work)
 181 {
 182         if (work)
 183                 *work -= sizeof(struct ipq);
 184         atomic_sub(sizeof(struct ipq), &ip_frag_mem);
 185         kfree(qp);
 186 }
 187
 188 static __inline__ struct ipq *frag_alloc_queue(void)
 189 {
 190         struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC);
 191
 192         if(!qp)
 193                 return NULL;
 194         atomic_add(sizeof(struct ipq), &ip_frag_mem);
 195         return qp;
 196 }
 197
 198
 199 /* Destruction primitives. */
 200
 201 /* Complete destruction of ipq. */
 202 static void ip_frag_destroy(struct ipq *qp, int *work)
 203 {
 204         struct sk_buff *fp;
 205
 206         BUG_TRAP(qp->last_in&COMPLETE);
 207         BUG_TRAP(del_timer(&qp->timer) == 0);
 208
 209         /* Release all fragment data. */
 210         fp = qp->fragments;
 211         while (fp) {
 212                 struct sk_buff *xp = fp->next;
 213
 214                 frag_kfree_skb(fp, work);
 215                 fp = xp;
 216         }
 217
 218         /* Finally, release the queue descriptor itself. */
 219         frag_free_queue(qp, work);
 220 }
 221
 222 static __inline__ void ipq_put(struct ipq *ipq, int *work)
 223 {
 224         if (atomic_dec_and_test(&ipq->refcnt))
 225                 ip_frag_destroy(ipq, work);
 226 }
 227
 228 /* Kill ipq entry. It is not destroyed immediately,
 229  * because caller (and someone more) holds reference count.
 230  */
 231 static __inline__ void ipq_kill(struct ipq *ipq)
 232 {
 233         if (del_timer(&ipq->timer))
 234                 atomic_dec(&ipq->refcnt);
 235
 236         if (!(ipq->last_in & COMPLETE)) {
 237                 ipq_unlink(ipq);
 238                 atomic_dec(&ipq->refcnt);
 239                 ipq->last_in |= COMPLETE;
 240         }
 241 }
 242
 243 /* Memory limiting on fragments.  Evictor trashes the oldest
 244  * fragment queue until we are back under the threshold.
 245  */
 246 static void ip_evictor(void)
 247 {
 248         struct ipq *qp;
 249         struct list_head *tmp;
 250         int work;
 251
 252         work = atomic_read(&ip_frag_mem) - sysctl_ipfrag_low_thresh;
 253         if (work <= 0)
 254                 return;
 255
 256         while (work > 0) {
 257                 read_lock(&ipfrag_lock);
 258                 if (list_empty(&ipq_lru_list)) {
 259                         read_unlock(&ipfrag_lock);
 260                         return;
 261                 }
 262                 tmp = ipq_lru_list.next;
 263                 qp = list_entry(tmp, struct ipq, lru_list);
 264                 atomic_inc(&qp->refcnt);
 265                 read_unlock(&ipfrag_lock);
 266
 267                 spin_lock(&qp->lock);
 268                 if (!(qp->last_in&COMPLETE))
 269                         ipq_kill(qp);
 270                 spin_unlock(&qp->lock);
 271
 272                 ipq_put(qp, &work);
 273                 IP_INC_STATS_BH(IpReasmFails);
 274         }
 275 }
 276
 277 /*
 278  * Oops, a fragment queue timed out.  Kill it and send an ICMP reply.
 279  */
 280 static void ip_expire(unsigned long arg)
 281 {
 282         struct ipq *qp = (struct ipq *) arg;
 283
 284         spin_lock(&qp->lock);
 285
 286         if (qp->last_in & COMPLETE)
 287                 goto out;
 288
 289         ipq_kill(qp);
 290
 291         IP_INC_STATS_BH(IpReasmTimeout);
 292         IP_INC_STATS_BH(IpReasmFails);
 293
 294         if ((qp->last_in&FIRST_IN) && qp->fragments != NULL) {
 295                 struct sk_buff *head = qp->fragments;
 296                 /* Send an ICMP "Fragment Reassembly Timeout" message. */
 297                 if ((head->dev = dev_get_by_index(qp->iif)) != NULL) {
 298                         icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
 299                         dev_put(head->dev);
 300                 }
 301         }
 302 out:
 303         spin_unlock(&qp->lock);
 304         ipq_put(qp, NULL);
 305 }
 306
 307 /* Creation primitives. */
 308
 309 static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
 310 {
 311         struct ipq *qp;
 312
 313         write_lock(&ipfrag_lock);
 314 #ifdef CONFIG_SMP
 315         /* With SMP race we have to recheck hash table, because
 316          * such entry could be created on other cpu, while we
 317          * promoted read lock to write lock.
 318          */
 319         for(qp = ipq_hash[hash]; qp; qp = qp->next) {
 320                 if(qp->id == qp_in->id          &&
 321                    qp->saddr == qp_in->saddr    &&
 322                    qp->daddr == qp_in->daddr    &&
 323                    qp->protocol == qp_in->protocol &&
 324                    qp->user == qp_in->user) {
 325                         atomic_inc(&qp->refcnt);
 326                         write_unlock(&ipfrag_lock);
 327                         qp_in->last_in |= COMPLETE;
 328                         ipq_put(qp_in, NULL);
 329                         return qp;
 330                 }
 331         }
 332 #endif
 333         qp = qp_in;
 334
 335         if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time))
 336                 atomic_inc(&qp->refcnt);
 337
 338         atomic_inc(&qp->refcnt);
 339         if((qp->next = ipq_hash[hash]) != NULL)
 340                 qp->next->pprev = &qp->next;
 341         ipq_hash[hash] = qp;
 342         qp->pprev = &ipq_hash[hash];
 343         INIT_LIST_HEAD(&qp->lru_list);
 344         list_add_tail(&qp->lru_list, &ipq_lru_list);
 345         ip_frag_nqueues++;
 346         write_unlock(&ipfrag_lock);
 347         return qp;
 348 }
 349
 350 /* Add an entry to the 'ipq' queue for a newly received IP datagram. */
 351 static struct ipq *ip_frag_create(unsigned hash, struct iphdr *iph, u32 user)
 352 {
 353         struct ipq *qp;
 354
 355         if ((qp = frag_alloc_queue()) == NULL)
 356                 goto out_nomem;
 357
 358         qp->protocol = iph->protocol;
 359         qp->last_in = 0;
 360         qp->id = iph->id;
 361         qp->saddr = iph->saddr;
 362         qp->daddr = iph->daddr;
 363         qp->user = user;
 364         qp->len = 0;
 365         qp->meat = 0;
 366         qp->fragments = NULL;
 367         qp->iif = 0;
 368
 369         /* Initialize a timer for this entry. */
 370         init_timer(&qp->timer);
 371         qp->timer.data = (unsigned long) qp;    /* pointer to queue     */
 372         qp->timer.function = ip_expire;         /* expire function      */
 373         qp->lock = SPIN_LOCK_UNLOCKED;
 374         atomic_set(&qp->refcnt, 1);
 375
 376         return ip_frag_intern(hash, qp);
 377
 378 out_nomem:
 379         NETDEBUG(if (net_ratelimit()) printk(KERN_ERR "ip_frag_create: no memory left !\n"));
 380         return NULL;
 381 }
 382
 383 /* Find the correct entry in the "incomplete datagrams" queue for
 384  * this IP datagram, and create new one, if nothing is found.
 385  */
 386 static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
 387 {
 388         __u16 id = iph->id;
 389         __u32 saddr = iph->saddr;
 390         __u32 daddr = iph->daddr;
 391         __u8 protocol = iph->protocol;
 392         unsigned int hash = ipqhashfn(id, saddr, daddr, protocol);
 393         struct ipq *qp;
 394
 395         read_lock(&ipfrag_lock);
 396         for(qp = ipq_hash[hash]; qp; qp = qp->next) {
 397                 if(qp->id == id         &&
 398                    qp->saddr == saddr   &&
 399                    qp->daddr == daddr   &&
 400                    qp->protocol == protocol &&
 401                    qp->user == user) {
 402                         atomic_inc(&qp->refcnt);
 403                         read_unlock(&ipfrag_lock);
 404                         return qp;
 405                 }
 406         }
 407         read_unlock(&ipfrag_lock);
 408
 409         return ip_frag_create(hash, iph, user);
 410 }
 411
 412 /* Add new segment to existing queue. */
 413 static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 414 {
 415         struct sk_buff *prev, *next;
 416         int flags, offset;
 417         int ihl, end;
 418
 419         if (qp->last_in & COMPLETE)
 420                 goto err;
 421
 422         offset = ntohs(skb->nh.iph->frag_off);
 423         flags = offset & ~IP_OFFSET;
 424         offset &= IP_OFFSET;
 425         offset <<= 3;           /* offset is in 8-byte chunks */
 426         ihl = skb->nh.iph->ihl * 4;
 427
 428         /* Determine the position of this fragment. */
 429         end = offset + skb->len - ihl;
 430
 431         /* Is this the final fragment? */
 432         if ((flags & IP_MF) == 0) {
 433                 /* If we already have some bits beyond end
 434                  * or have different end, the segment is corrrupted.
 435                  */
 436                 if (end < qp->len ||
 437                     ((qp->last_in & LAST_IN) && end != qp->len))
 438                         goto err;
 439                 qp->last_in |= LAST_IN;
 440                 qp->len = end;
 441         } else {
 442                 if (end&7) {
 443                         end &= ~7;
 444                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 445                                 skb->ip_summed = CHECKSUM_NONE;
 446                 }
 447                 if (end > qp->len) {
 448                         /* Some bits beyond end -> corruption. */
 449                         if (qp->last_in & LAST_IN)
 450                                 goto err;
 451                         qp->len = end;
 452                 }
 453         }
 454         if (end == offset)
 455                 goto err;
 456
 457         if (pskb_pull(skb, ihl) == NULL)
 458                 goto err;
 459         if (pskb_trim(skb, end-offset))
 460                 goto err;
 461
 462         /* Find out which fragments are in front and at the back of us
 463          * in the chain of fragments so far.  We must know where to put
 464          * this fragment, right?
 465          */
 466         prev = NULL;
 467         for(next = qp->fragments; next != NULL; next = next->next) {
 468                 if (FRAG_CB(next)->offset >= offset)
 469                         break;  /* bingo! */
 470                 prev = next;
 471         }
 472
 473         /* We found where to put this one.  Check for overlap with
 474          * preceding fragment, and, if needed, align things so that
 475          * any overlaps are eliminated.
 476          */
 477         if (prev) {
 478                 int i = (FRAG_CB(prev)->offset + prev->len) - offset;
 479
 480                 if (i > 0) {
 481                         offset += i;
 482                         if (end <= offset)
 483                                 goto err;
 484                         if (!pskb_pull(skb, i))
 485                                 goto err;
 486                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 487                                 skb->ip_summed = CHECKSUM_NONE;
 488                 }
 489         }
 490
 491         while (next && FRAG_CB(next)->offset < end) {
 492                 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */
 493
 494                 if (i < next->len) {
 495                         /* Eat head of the next overlapped fragment
 496                          * and leave the loop. The next ones cannot overlap.
 497                          */
 498                         if (!pskb_pull(next, i))
 499                                 goto err;
 500                         FRAG_CB(next)->offset += i;
 501                         qp->meat -= i;
 502                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 503                                 next->ip_summed = CHECKSUM_NONE;
 504                         break;
 505                 } else {
 506                         struct sk_buff *free_it = next;
 507
 508                         /* Old fragmnet is completely overridden with
 509                          * new one drop it.
 510                          */
 511                         next = next->next;
 512
 513                         if (prev)
 514                                 prev->next = next;
 515                         else
 516                                 qp->fragments = next;
 517
 518                         qp->meat -= free_it->len;
 519                         frag_kfree_skb(free_it, NULL);
 520                 }
 521         }
 522
 523         FRAG_CB(skb)->offset = offset;
 524
 525         /* Insert this fragment in the chain of fragments. */
 526         skb->next = next;
 527         if (prev)
 528                 prev->next = skb;
 529         else
 530                 qp->fragments = skb;
 531
 532         if (skb->dev)
 533                 qp->iif = skb->dev->ifindex;
 534         skb->dev = NULL;
 535         qp->stamp = skb->stamp;
 536         qp->meat += skb->len;
 537         atomic_add(skb->truesize, &ip_frag_mem);
 538         if (offset == 0)
 539                 qp->last_in |= FIRST_IN;
 540
 541         write_lock(&ipfrag_lock);
 542         list_move_tail(&qp->lru_list, &ipq_lru_list);
 543         write_unlock(&ipfrag_lock);
 544
 545         return;
 546
 547 err:
 548         kfree_skb(skb);
 549 }
 550
 551
 552 /* Build a new IP datagram from all its fragments. */
 553
 554 static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev)
 555 {
 556         struct iphdr *iph;
 557         struct sk_buff *fp, *head = qp->fragments;
 558         int len;
 559         int ihlen;
 560
 561         ipq_kill(qp);
 562
 563         BUG_TRAP(head != NULL);
 564         BUG_TRAP(FRAG_CB(head)->offset == 0);
 565
 566         /* Allocate a new buffer for the datagram. */
 567         ihlen = head->nh.iph->ihl*4;
 568         len = ihlen + qp->len;
 569
 570         if(len > 65535)
 571                 goto out_oversize;
 572
 573         /* Head of list must not be cloned. */
 574         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 575                 goto out_nomem;
 576
 577         /* If the first fragment is fragmented itself, we split
 578          * it to two chunks: the first with data and paged part
 579          * and the second, holding only fragments. */
 580         if (skb_shinfo(head)->frag_list) {
 581                 struct sk_buff *clone;
 582                 int i, plen = 0;
 583
 584                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 585                         goto out_nomem;
 586                 clone->next = head->next;
 587                 head->next = clone;
 588                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 589                 skb_shinfo(head)->frag_list = NULL;
 590                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 591                         plen += skb_shinfo(head)->frags[i].size;
 592                 clone->len = clone->data_len = head->data_len - plen;
 593                 head->data_len -= clone->len;
 594                 head->len -= clone->len;
 595                 clone->csum = 0;
 596                 clone->ip_summed = head->ip_summed;
 597                 atomic_add(clone->truesize, &ip_frag_mem);
 598         }
 599
 600         skb_shinfo(head)->frag_list = head->next;
 601         skb_push(head, head->data - head->nh.raw);
 602         atomic_sub(head->truesize, &ip_frag_mem);
 603
 604         for (fp=head->next; fp; fp = fp->next) {
 605                 head->data_len += fp->len;
 606                 head->len += fp->len;
 607                 if (head->ip_summed != fp->ip_summed)
 608                         head->ip_summed = CHECKSUM_NONE;
 609                 else if (head->ip_summed == CHECKSUM_HW)
 610                         head->csum = csum_add(head->csum, fp->csum);
 611                 head->truesize += fp->truesize;
 612                 atomic_sub(fp->truesize, &ip_frag_mem);
 613         }
 614
 615         head->next = NULL;
 616         head->dev = dev;
 617         head->stamp = qp->stamp;
 618
 619         iph = head->nh.iph;
 620         iph->frag_off = 0;
 621         iph->tot_len = htons(len);
 622         IP_INC_STATS_BH(IpReasmOKs);
 623         qp->fragments = NULL;
 624         return head;
 625
 626 out_nomem:
 627         NETDEBUG(if (net_ratelimit())
 628                  printk(KERN_ERR
 629                         "IP: queue_glue: no memory for gluing queue %p\n",
 630                         qp));
 631         goto out_fail;
 632 out_oversize:
 633         if (net_ratelimit())
 634                 printk(KERN_INFO
 635                         "Oversized IP packet from %d.%d.%d.%d.\n",
 636                         NIPQUAD(qp->saddr));
 637 out_fail:
 638         IP_INC_STATS_BH(IpReasmFails);
 639         return NULL;
 640 }
 641
 642 /* Process an incoming IP datagram fragment. */
 643 struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user)
 644 {
 645         struct iphdr *iph = skb->nh.iph;
 646         struct ipq *qp;
 647         struct net_device *dev;
 648
 649         IP_INC_STATS_BH(IpReasmReqds);
 650
 651         /* Start by cleaning up the memory. */
 652         if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh)
 653                 ip_evictor();
 654
 655         dev = skb->dev;
 656
 657         /* Lookup (or create) queue header */
 658         if ((qp = ip_find(iph, user)) != NULL) {
 659                 struct sk_buff *ret = NULL;
 660
 661                 spin_lock(&qp->lock);
 662
 663                 ip_frag_queue(qp, skb);
 664
 665                 if (qp->last_in == (FIRST_IN|LAST_IN) &&
 666                     qp->meat == qp->len)
 667                         ret = ip_frag_reasm(qp, dev);
 668
 669                 spin_unlock(&qp->lock);
 670                 ipq_put(qp, NULL);
 671                 return ret;
 672         }
 673
 674         IP_INC_STATS_BH(IpReasmFails);
 675         kfree_skb(skb);
 676         return NULL;
 677 }
 678
 679 void ipfrag_init(void)
 680 {
 681         ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 682                                  (jiffies ^ (jiffies >> 6)));
 683
 684         init_timer(&ipfrag_secret_timer);
 685         ipfrag_secret_timer.function = ipfrag_secret_rebuild;
 686         ipfrag_secret_timer.expires = jiffies + sysctl_ipfrag_secret_interval;
 687         add_timer(&ipfrag_secret_timer);
 688 }