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  * Authors:     Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
   9  *              Alan Cox <alan@lxorguk.ukuu.org.uk>
  10  *
  11  * Fixes:
  12  *              Alan Cox        :       Split from ip.c , see ip_input.c for history.
  13  *              David S. Miller :       Begin massive cleanup...
  14  *              Andi Kleen      :       Add sysctls.
  15  *              xxxx            :       Overlapfrag bug.
  16  *              Ultima          :       ip_expire() kernel panic.
  17  *              Bill Hawes      :       Frag accounting and evictor fixes.
  18  *              John McDonald   :       0 length frag bug.
  19  *              Alexey Kuznetsov:       SMP races, threading, cleanup.
  20  *              Patrick McHardy :       LRU queue of frag heads for evictor.
  21  */
  22
  23 #include <linux/compiler.h>
  24 #include <linux/module.h>
  25 #include <linux/types.h>
  26 #include <linux/mm.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/list.h>
  30 #include <linux/ip.h>
  31 #include <linux/icmp.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/jhash.h>
  34 #include <linux/random.h>
  35 #include <linux/slab.h>
  36 #include <net/route.h>
  37 #include <net/dst.h>
  38 #include <net/sock.h>
  39 #include <net/ip.h>
  40 #include <net/icmp.h>
  41 #include <net/checksum.h>
  42 #include <net/inetpeer.h>
  43 #include <net/inet_frag.h>
  44 #include <linux/tcp.h>
  45 #include <linux/udp.h>
  46 #include <linux/inet.h>
  47 #include <linux/netfilter_ipv4.h>
  48
  49 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
  50  * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
  51  * as well. Or notify me, at least. --ANK
  52  */
  53
  54 static int sysctl_ipfrag_max_dist __read_mostly = 64;
  55
  56 struct ipfrag_skb_cb
  57 {
  58         struct inet_skb_parm    h;
  59         int                     offset;
  60 };
  61
  62 #define FRAG_CB(skb)    ((struct ipfrag_skb_cb *)((skb)->cb))
  63
  64 /* Describe an entry in the "incomplete datagrams" queue. */
  65 struct ipq {
  66         struct inet_frag_queue q;
  67
  68         u32             user;
  69         __be32          saddr;
  70         __be32          daddr;
  71         __be16          id;
  72         u8              protocol;
  73         int             iif;
  74         unsigned int    rid;
  75         struct inet_peer *peer;
  76 };
  77
  78 static struct inet_frags ip4_frags;
  79
  80 int ip_frag_nqueues(struct net *net)
  81 {
  82         return net->ipv4.frags.nqueues;
  83 }
  84
  85 int ip_frag_mem(struct net *net)
  86 {
  87         return atomic_read(&net->ipv4.frags.mem);
  88 }
  89
  90 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
  91                          struct net_device *dev);
  92
  93 struct ip4_create_arg {
  94         struct iphdr *iph;
  95         u32 user;
  96 };
  97
  98 static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot)
  99 {
 100         return jhash_3words((__force u32)id << 16 | prot,
 101                             (__force u32)saddr, (__force u32)daddr,
 102                             ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1);
 103 }
 104
 105 static unsigned int ip4_hashfn(struct inet_frag_queue *q)
 106 {
 107         struct ipq *ipq;
 108
 109         ipq = container_of(q, struct ipq, q);
 110         return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol);
 111 }
 112
 113 static int ip4_frag_match(struct inet_frag_queue *q, void *a)
 114 {
 115         struct ipq *qp;
 116         struct ip4_create_arg *arg = a;
 117
 118         qp = container_of(q, struct ipq, q);
 119         return  qp->id == arg->iph->id &&
 120                         qp->saddr == arg->iph->saddr &&
 121                         qp->daddr == arg->iph->daddr &&
 122                         qp->protocol == arg->iph->protocol &&
 123                         qp->user == arg->user;
 124 }
 125
 126 /* Memory Tracking Functions. */
 127 static void frag_kfree_skb(struct netns_frags *nf, struct sk_buff *skb)
 128 {
 129         atomic_sub(skb->truesize, &nf->mem);
 130         kfree_skb(skb);
 131 }
 132
 133 static void ip4_frag_init(struct inet_frag_queue *q, void *a)
 134 {
 135         struct ipq *qp = container_of(q, struct ipq, q);
 136         struct ip4_create_arg *arg = a;
 137
 138         qp->protocol = arg->iph->protocol;
 139         qp->id = arg->iph->id;
 140         qp->saddr = arg->iph->saddr;
 141         qp->daddr = arg->iph->daddr;
 142         qp->user = arg->user;
 143         qp->peer = sysctl_ipfrag_max_dist ?
 144                 inet_getpeer(arg->iph->saddr, 1) : NULL;
 145 }
 146
 147 static __inline__ void ip4_frag_free(struct inet_frag_queue *q)
 148 {
 149         struct ipq *qp;
 150
 151         qp = container_of(q, struct ipq, q);
 152         if (qp->peer)
 153                 inet_putpeer(qp->peer);
 154 }
 155
 156
 157 /* Destruction primitives. */
 158
 159 static __inline__ void ipq_put(struct ipq *ipq)
 160 {
 161         inet_frag_put(&ipq->q, &ip4_frags);
 162 }
 163
 164 /* Kill ipq entry. It is not destroyed immediately,
 165  * because caller (and someone more) holds reference count.
 166  */
 167 static void ipq_kill(struct ipq *ipq)
 168 {
 169         inet_frag_kill(&ipq->q, &ip4_frags);
 170 }
 171
 172 /* Memory limiting on fragments.  Evictor trashes the oldest
 173  * fragment queue until we are back under the threshold.
 174  */
 175 static void ip_evictor(struct net *net)
 176 {
 177         int evicted;
 178
 179         evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags);
 180         if (evicted)
 181                 IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted);
 182 }
 183
 184 /*
 185  * Oops, a fragment queue timed out.  Kill it and send an ICMP reply.
 186  */
 187 static void ip_expire(unsigned long arg)
 188 {
 189         struct ipq *qp;
 190         struct net *net;
 191
 192         qp = container_of((struct inet_frag_queue *) arg, struct ipq, q);
 193         net = container_of(qp->q.net, struct net, ipv4.frags);
 194
 195         spin_lock(&qp->q.lock);
 196
 197         if (qp->q.last_in & INET_FRAG_COMPLETE)
 198                 goto out;
 199
 200         ipq_kill(qp);
 201
 202         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT);
 203         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 204
 205         if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) {
 206                 struct sk_buff *head = qp->q.fragments;
 207
 208                 rcu_read_lock();
 209                 head->dev = dev_get_by_index_rcu(net, qp->iif);
 210                 if (!head->dev)
 211                         goto out_rcu_unlock;
 212
 213                 /*
 214                  * Only search router table for the head fragment,
 215                  * when defraging timeout at PRE_ROUTING HOOK.
 216                  */
 217                 if (qp->user == IP_DEFRAG_CONNTRACK_IN && !skb_dst(head)) {
 218                         const struct iphdr *iph = ip_hdr(head);
 219                         int err = ip_route_input(head, iph->daddr, iph->saddr,
 220                                                  iph->tos, head->dev);
 221                         if (unlikely(err))
 222                                 goto out_rcu_unlock;
 223
 224                         /*
 225                          * Only an end host needs to send an ICMP
 226                          * "Fragment Reassembly Timeout" message, per RFC792.
 227                          */
 228                         if (skb_rtable(head)->rt_type != RTN_LOCAL)
 229                                 goto out_rcu_unlock;
 230
 231                 }
 232
 233                 /* Send an ICMP "Fragment Reassembly Timeout" message. */
 234                 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
 235 out_rcu_unlock:
 236                 rcu_read_unlock();
 237         }
 238 out:
 239         spin_unlock(&qp->q.lock);
 240         ipq_put(qp);
 241 }
 242
 243 /* Find the correct entry in the "incomplete datagrams" queue for
 244  * this IP datagram, and create new one, if nothing is found.
 245  */
 246 static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user)
 247 {
 248         struct inet_frag_queue *q;
 249         struct ip4_create_arg arg;
 250         unsigned int hash;
 251
 252         arg.iph = iph;
 253         arg.user = user;
 254
 255         read_lock(&ip4_frags.lock);
 256         hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
 257
 258         q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash);
 259         if (q == NULL)
 260                 goto out_nomem;
 261
 262         return container_of(q, struct ipq, q);
 263
 264 out_nomem:
 265         LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n");
 266         return NULL;
 267 }
 268
 269 /* Is the fragment too far ahead to be part of ipq? */
 270 static inline int ip_frag_too_far(struct ipq *qp)
 271 {
 272         struct inet_peer *peer = qp->peer;
 273         unsigned int max = sysctl_ipfrag_max_dist;
 274         unsigned int start, end;
 275
 276         int rc;
 277
 278         if (!peer || !max)
 279                 return 0;
 280
 281         start = qp->rid;
 282         end = atomic_inc_return(&peer->rid);
 283         qp->rid = end;
 284
 285         rc = qp->q.fragments && (end - start) > max;
 286
 287         if (rc) {
 288                 struct net *net;
 289
 290                 net = container_of(qp->q.net, struct net, ipv4.frags);
 291                 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 292         }
 293
 294         return rc;
 295 }
 296
 297 static int ip_frag_reinit(struct ipq *qp)
 298 {
 299         struct sk_buff *fp;
 300
 301         if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
 302                 atomic_inc(&qp->q.refcnt);
 303                 return -ETIMEDOUT;
 304         }
 305
 306         fp = qp->q.fragments;
 307         do {
 308                 struct sk_buff *xp = fp->next;
 309                 frag_kfree_skb(qp->q.net, fp);
 310                 fp = xp;
 311         } while (fp);
 312
 313         qp->q.last_in = 0;
 314         qp->q.len = 0;
 315         qp->q.meat = 0;
 316         qp->q.fragments = NULL;
 317         qp->q.fragments_tail = NULL;
 318         qp->iif = 0;
 319
 320         return 0;
 321 }
 322
 323 /* Add new segment to existing queue. */
 324 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 325 {
 326         struct sk_buff *prev, *next;
 327         struct net_device *dev;
 328         int flags, offset;
 329         int ihl, end;
 330         int err = -ENOENT;
 331
 332         if (qp->q.last_in & INET_FRAG_COMPLETE)
 333                 goto err;
 334
 335         if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
 336             unlikely(ip_frag_too_far(qp)) &&
 337             unlikely(err = ip_frag_reinit(qp))) {
 338                 ipq_kill(qp);
 339                 goto err;
 340         }
 341
 342         offset = ntohs(ip_hdr(skb)->frag_off);
 343         flags = offset & ~IP_OFFSET;
 344         offset &= IP_OFFSET;
 345         offset <<= 3;           /* offset is in 8-byte chunks */
 346         ihl = ip_hdrlen(skb);
 347
 348         /* Determine the position of this fragment. */
 349         end = offset + skb->len - ihl;
 350         err = -EINVAL;
 351
 352         /* Is this the final fragment? */
 353         if ((flags & IP_MF) == 0) {
 354                 /* If we already have some bits beyond end
 355                  * or have different end, the segment is corrrupted.
 356                  */
 357                 if (end < qp->q.len ||
 358                     ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len))
 359                         goto err;
 360                 qp->q.last_in |= INET_FRAG_LAST_IN;
 361                 qp->q.len = end;
 362         } else {
 363                 if (end&7) {
 364                         end &= ~7;
 365                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 366                                 skb->ip_summed = CHECKSUM_NONE;
 367                 }
 368                 if (end > qp->q.len) {
 369                         /* Some bits beyond end -> corruption. */
 370                         if (qp->q.last_in & INET_FRAG_LAST_IN)
 371                                 goto err;
 372                         qp->q.len = end;
 373                 }
 374         }
 375         if (end == offset)
 376                 goto err;
 377
 378         err = -ENOMEM;
 379         if (pskb_pull(skb, ihl) == NULL)
 380                 goto err;
 381
 382         err = pskb_trim_rcsum(skb, end - offset);
 383         if (err)
 384                 goto err;
 385
 386         /* Find out which fragments are in front and at the back of us
 387          * in the chain of fragments so far.  We must know where to put
 388          * this fragment, right?
 389          */
 390         prev = qp->q.fragments_tail;
 391         if (!prev || FRAG_CB(prev)->offset < offset) {
 392                 next = NULL;
 393                 goto found;
 394         }
 395         prev = NULL;
 396         for (next = qp->q.fragments; next != NULL; next = next->next) {
 397                 if (FRAG_CB(next)->offset >= offset)
 398                         break;  /* bingo! */
 399                 prev = next;
 400         }
 401
 402 found:
 403         /* We found where to put this one.  Check for overlap with
 404          * preceding fragment, and, if needed, align things so that
 405          * any overlaps are eliminated.
 406          */
 407         if (prev) {
 408                 int i = (FRAG_CB(prev)->offset + prev->len) - offset;
 409
 410                 if (i > 0) {
 411                         offset += i;
 412                         err = -EINVAL;
 413                         if (end <= offset)
 414                                 goto err;
 415                         err = -ENOMEM;
 416                         if (!pskb_pull(skb, i))
 417                                 goto err;
 418                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 419                                 skb->ip_summed = CHECKSUM_NONE;
 420                 }
 421         }
 422
 423         err = -ENOMEM;
 424
 425         while (next && FRAG_CB(next)->offset < end) {
 426                 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */
 427
 428                 if (i < next->len) {
 429                         /* Eat head of the next overlapped fragment
 430                          * and leave the loop. The next ones cannot overlap.
 431                          */
 432                         if (!pskb_pull(next, i))
 433                                 goto err;
 434                         FRAG_CB(next)->offset += i;
 435                         qp->q.meat -= i;
 436                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 437                                 next->ip_summed = CHECKSUM_NONE;
 438                         break;
 439                 } else {
 440                         struct sk_buff *free_it = next;
 441
 442                         /* Old fragment is completely overridden with
 443                          * new one drop it.
 444                          */
 445                         next = next->next;
 446
 447                         if (prev)
 448                                 prev->next = next;
 449                         else
 450                                 qp->q.fragments = next;
 451
 452                         qp->q.meat -= free_it->len;
 453                         frag_kfree_skb(qp->q.net, free_it);
 454                 }
 455         }
 456
 457         FRAG_CB(skb)->offset = offset;
 458
 459         /* Insert this fragment in the chain of fragments. */
 460         skb->next = next;
 461         if (!next)
 462                 qp->q.fragments_tail = skb;
 463         if (prev)
 464                 prev->next = skb;
 465         else
 466                 qp->q.fragments = skb;
 467
 468         dev = skb->dev;
 469         if (dev) {
 470                 qp->iif = dev->ifindex;
 471                 skb->dev = NULL;
 472         }
 473         qp->q.stamp = skb->tstamp;
 474         qp->q.meat += skb->len;
 475         atomic_add(skb->truesize, &qp->q.net->mem);
 476         if (offset == 0)
 477                 qp->q.last_in |= INET_FRAG_FIRST_IN;
 478
 479         if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
 480             qp->q.meat == qp->q.len)
 481                 return ip_frag_reasm(qp, prev, dev);
 482
 483         write_lock(&ip4_frags.lock);
 484         list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list);
 485         write_unlock(&ip4_frags.lock);
 486         return -EINPROGRESS;
 487
 488 err:
 489         kfree_skb(skb);
 490         return err;
 491 }
 492
 493
 494 /* Build a new IP datagram from all its fragments. */
 495
 496 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 497                          struct net_device *dev)
 498 {
 499         struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
 500         struct iphdr *iph;
 501         struct sk_buff *fp, *head = qp->q.fragments;
 502         int len;
 503         int ihlen;
 504         int err;
 505
 506         ipq_kill(qp);
 507
 508         /* Make the one we just received the head. */
 509         if (prev) {
 510                 head = prev->next;
 511                 fp = skb_clone(head, GFP_ATOMIC);
 512                 if (!fp)
 513                         goto out_nomem;
 514
 515                 fp->next = head->next;
 516                 if (!fp->next)
 517                         qp->q.fragments_tail = fp;
 518                 prev->next = fp;
 519
 520                 skb_morph(head, qp->q.fragments);
 521                 head->next = qp->q.fragments->next;
 522
 523                 kfree_skb(qp->q.fragments);
 524                 qp->q.fragments = head;
 525         }
 526
 527         WARN_ON(head == NULL);
 528         WARN_ON(FRAG_CB(head)->offset != 0);
 529
 530         /* Allocate a new buffer for the datagram. */
 531         ihlen = ip_hdrlen(head);
 532         len = ihlen + qp->q.len;
 533
 534         err = -E2BIG;
 535         if (len > 65535)
 536                 goto out_oversize;
 537
 538         /* Head of list must not be cloned. */
 539         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 540                 goto out_nomem;
 541
 542         /* If the first fragment is fragmented itself, we split
 543          * it to two chunks: the first with data and paged part
 544          * and the second, holding only fragments. */
 545         if (skb_has_frag_list(head)) {
 546                 struct sk_buff *clone;
 547                 int i, plen = 0;
 548
 549                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 550                         goto out_nomem;
 551                 clone->next = head->next;
 552                 head->next = clone;
 553                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 554                 skb_frag_list_init(head);
 555                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 556                         plen += skb_shinfo(head)->frags[i].size;
 557                 clone->len = clone->data_len = head->data_len - plen;
 558                 head->data_len -= clone->len;
 559                 head->len -= clone->len;
 560                 clone->csum = 0;
 561                 clone->ip_summed = head->ip_summed;
 562                 atomic_add(clone->truesize, &qp->q.net->mem);
 563         }
 564
 565         skb_shinfo(head)->frag_list = head->next;
 566         skb_push(head, head->data - skb_network_header(head));
 567
 568         for (fp=head->next; fp; fp = fp->next) {
 569                 head->data_len += fp->len;
 570                 head->len += fp->len;
 571                 if (head->ip_summed != fp->ip_summed)
 572                         head->ip_summed = CHECKSUM_NONE;
 573                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 574                         head->csum = csum_add(head->csum, fp->csum);
 575                 head->truesize += fp->truesize;
 576         }
 577         atomic_sub(head->truesize, &qp->q.net->mem);
 578
 579         head->next = NULL;
 580         head->dev = dev;
 581         head->tstamp = qp->q.stamp;
 582
 583         iph = ip_hdr(head);
 584         iph->frag_off = 0;
 585         iph->tot_len = htons(len);
 586         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
 587         qp->q.fragments = NULL;
 588         qp->q.fragments_tail = NULL;
 589         return 0;
 590
 591 out_nomem:
 592         LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing "
 593                               "queue %p\n", qp);
 594         err = -ENOMEM;
 595         goto out_fail;
 596 out_oversize:
 597         if (net_ratelimit())
 598                 printk(KERN_INFO "Oversized IP packet from %pI4.\n",
 599                         &qp->saddr);
 600 out_fail:
 601         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 602         return err;
 603 }
 604
 605 /* Process an incoming IP datagram fragment. */
 606 int ip_defrag(struct sk_buff *skb, u32 user)
 607 {
 608         struct ipq *qp;
 609         struct net *net;
 610
 611         net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev);
 612         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS);
 613
 614         /* Start by cleaning up the memory. */
 615         if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh)
 616                 ip_evictor(net);
 617
 618         /* Lookup (or create) queue header */
 619         if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) {
 620                 int ret;
 621
 622                 spin_lock(&qp->q.lock);
 623
 624                 ret = ip_frag_queue(qp, skb);
 625
 626                 spin_unlock(&qp->q.lock);
 627                 ipq_put(qp);
 628                 return ret;
 629         }
 630
 631         IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 632         kfree_skb(skb);
 633         return -ENOMEM;
 634 }
 635 EXPORT_SYMBOL(ip_defrag);
 636
 637 #ifdef CONFIG_SYSCTL
 638 static int zero;
 639
 640 static struct ctl_table ip4_frags_ns_ctl_table[] = {
 641         {
 642                 .procname       = "ipfrag_high_thresh",
 643                 .data           = &init_net.ipv4.frags.high_thresh,
 644                 .maxlen         = sizeof(int),
 645                 .mode           = 0644,
 646                 .proc_handler   = proc_dointvec
 647         },
 648         {
 649                 .procname       = "ipfrag_low_thresh",
 650                 .data           = &init_net.ipv4.frags.low_thresh,
 651                 .maxlen         = sizeof(int),
 652                 .mode           = 0644,
 653                 .proc_handler   = proc_dointvec
 654         },
 655         {
 656                 .procname       = "ipfrag_time",
 657                 .data           = &init_net.ipv4.frags.timeout,
 658                 .maxlen         = sizeof(int),
 659                 .mode           = 0644,
 660                 .proc_handler   = proc_dointvec_jiffies,
 661         },
 662         { }
 663 };
 664
 665 static struct ctl_table ip4_frags_ctl_table[] = {
 666         {
 667                 .procname       = "ipfrag_secret_interval",
 668                 .data           = &ip4_frags.secret_interval,
 669                 .maxlen         = sizeof(int),
 670                 .mode           = 0644,
 671                 .proc_handler   = proc_dointvec_jiffies,
 672         },
 673         {
 674                 .procname       = "ipfrag_max_dist",
 675                 .data           = &sysctl_ipfrag_max_dist,
 676                 .maxlen         = sizeof(int),
 677                 .mode           = 0644,
 678                 .proc_handler   = proc_dointvec_minmax,
 679                 .extra1         = &zero
 680         },
 681         { }
 682 };
 683
 684 static int __net_init ip4_frags_ns_ctl_register(struct net *net)
 685 {
 686         struct ctl_table *table;
 687         struct ctl_table_header *hdr;
 688
 689         table = ip4_frags_ns_ctl_table;
 690         if (!net_eq(net, &init_net)) {
 691                 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
 692                 if (table == NULL)
 693                         goto err_alloc;
 694
 695                 table[0].data = &net->ipv4.frags.high_thresh;
 696                 table[1].data = &net->ipv4.frags.low_thresh;
 697                 table[2].data = &net->ipv4.frags.timeout;
 698         }
 699
 700         hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, table);
 701         if (hdr == NULL)
 702                 goto err_reg;
 703
 704         net->ipv4.frags_hdr = hdr;
 705         return 0;
 706
 707 err_reg:
 708         if (!net_eq(net, &init_net))
 709                 kfree(table);
 710 err_alloc:
 711         return -ENOMEM;
 712 }
 713
 714 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
 715 {
 716         struct ctl_table *table;
 717
 718         table = net->ipv4.frags_hdr->ctl_table_arg;
 719         unregister_net_sysctl_table(net->ipv4.frags_hdr);
 720         kfree(table);
 721 }
 722
 723 static void ip4_frags_ctl_register(void)
 724 {
 725         register_net_sysctl_rotable(net_ipv4_ctl_path, ip4_frags_ctl_table);
 726 }
 727 #else
 728 static inline int ip4_frags_ns_ctl_register(struct net *net)
 729 {
 730         return 0;
 731 }
 732
 733 static inline void ip4_frags_ns_ctl_unregister(struct net *net)
 734 {
 735 }
 736
 737 static inline void ip4_frags_ctl_register(void)
 738 {
 739 }
 740 #endif
 741
 742 static int __net_init ipv4_frags_init_net(struct net *net)
 743 {
 744         /*
 745          * Fragment cache limits. We will commit 256K at one time. Should we
 746          * cross that limit we will prune down to 192K. This should cope with
 747          * even the most extreme cases without allowing an attacker to
 748          * measurably harm machine performance.
 749          */
 750         net->ipv4.frags.high_thresh = 256 * 1024;
 751         net->ipv4.frags.low_thresh = 192 * 1024;
 752         /*
 753          * Important NOTE! Fragment queue must be destroyed before MSL expires.
 754          * RFC791 is wrong proposing to prolongate timer each fragment arrival
 755          * by TTL.
 756          */
 757         net->ipv4.frags.timeout = IP_FRAG_TIME;
 758
 759         inet_frags_init_net(&net->ipv4.frags);
 760
 761         return ip4_frags_ns_ctl_register(net);
 762 }
 763
 764 static void __net_exit ipv4_frags_exit_net(struct net *net)
 765 {
 766         ip4_frags_ns_ctl_unregister(net);
 767         inet_frags_exit_net(&net->ipv4.frags, &ip4_frags);
 768 }
 769
 770 static struct pernet_operations ip4_frags_ops = {
 771         .init = ipv4_frags_init_net,
 772         .exit = ipv4_frags_exit_net,
 773 };
 774
 775 void __init ipfrag_init(void)
 776 {
 777         ip4_frags_ctl_register();
 778         register_pernet_subsys(&ip4_frags_ops);
 779         ip4_frags.hashfn = ip4_hashfn;
 780         ip4_frags.constructor = ip4_frag_init;
 781         ip4_frags.destructor = ip4_frag_free;
 782         ip4_frags.skb_free = NULL;
 783         ip4_frags.qsize = sizeof(struct ipq);
 784         ip4_frags.match = ip4_frag_match;
 785         ip4_frags.frag_expire = ip_expire;
 786         ip4_frags.secret_interval = 10 * 60 * HZ;
 787         inet_frags_init(&ip4_frags);
 788 }