net/ipv6/netfilter/nf_conntrack_reasm.c

   1 /*
   2  * IPv6 fragment reassembly for connection tracking
   3  *
   4  * Copyright (C)2004 USAGI/WIDE Project
   5  *
   6  * Author:
   7  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   8  *
   9  * Based on: net/ipv6/reassembly.c
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version
  14  * 2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/errno.h>
  18 #include <linux/types.h>
  19 #include <linux/string.h>
  20 #include <linux/socket.h>
  21 #include <linux/sockios.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/net.h>
  24 #include <linux/list.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/in6.h>
  27 #include <linux/ipv6.h>
  28 #include <linux/icmpv6.h>
  29 #include <linux/random.h>
  30 #include <linux/jhash.h>
  31
  32 #include <net/sock.h>
  33 #include <net/snmp.h>
  34 #include <net/inet_frag.h>
  35
  36 #include <net/ipv6.h>
  37 #include <net/protocol.h>
  38 #include <net/transp_v6.h>
  39 #include <net/rawv6.h>
  40 #include <net/ndisc.h>
  41 #include <net/addrconf.h>
  42 #include <linux/sysctl.h>
  43 #include <linux/netfilter.h>
  44 #include <linux/netfilter_ipv6.h>
  45 #include <linux/kernel.h>
  46 #include <linux/module.h>
  47
  48 #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
  49 #define NF_CT_FRAG6_LOW_THRESH 196608  /* == 192*1024 */
  50 #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
  51
  52 struct nf_ct_frag6_skb_cb
  53 {
  54         struct inet6_skb_parm   h;
  55         int                     offset;
  56         struct sk_buff          *orig;
  57 };
  58
  59 #define NFCT_FRAG6_CB(skb)      ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
  60
  61 struct nf_ct_frag6_queue
  62 {
  63         struct inet_frag_queue  q;
  64
  65         __be32                  id;             /* fragment id          */
  66         struct in6_addr         saddr;
  67         struct in6_addr         daddr;
  68
  69         unsigned int            csum;
  70         __u16                   nhoffset;
  71 };
  72
  73 struct inet_frags_ctl nf_frags_ctl __read_mostly = {
  74         .high_thresh     = 256 * 1024,
  75         .low_thresh      = 192 * 1024,
  76         .timeout         = IPV6_FRAG_TIMEOUT,
  77         .secret_interval = 10 * 60 * HZ,
  78 };
  79
  80 static struct inet_frags nf_frags;
  81
  82 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
  83                                struct in6_addr *daddr)
  84 {
  85         u32 a, b, c;
  86
  87         a = (__force u32)saddr->s6_addr32[0];
  88         b = (__force u32)saddr->s6_addr32[1];
  89         c = (__force u32)saddr->s6_addr32[2];
  90
  91         a += JHASH_GOLDEN_RATIO;
  92         b += JHASH_GOLDEN_RATIO;
  93         c += nf_frags.rnd;
  94         __jhash_mix(a, b, c);
  95
  96         a += (__force u32)saddr->s6_addr32[3];
  97         b += (__force u32)daddr->s6_addr32[0];
  98         c += (__force u32)daddr->s6_addr32[1];
  99         __jhash_mix(a, b, c);
 100
 101         a += (__force u32)daddr->s6_addr32[2];
 102         b += (__force u32)daddr->s6_addr32[3];
 103         c += (__force u32)id;
 104         __jhash_mix(a, b, c);
 105
 106         return c & (INETFRAGS_HASHSZ - 1);
 107 }
 108
 109 static unsigned int nf_hashfn(struct inet_frag_queue *q)
 110 {
 111         struct nf_ct_frag6_queue *nq;
 112
 113         nq = container_of(q, struct nf_ct_frag6_queue, q);
 114         return ip6qhashfn(nq->id, &nq->saddr, &nq->daddr);
 115 }
 116
 117 static void nf_skb_free(struct sk_buff *skb)
 118 {
 119         if (NFCT_FRAG6_CB(skb)->orig)
 120                 kfree_skb(NFCT_FRAG6_CB(skb)->orig);
 121 }
 122
 123 /* Memory Tracking Functions. */
 124 static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
 125 {
 126         if (work)
 127                 *work -= skb->truesize;
 128         atomic_sub(skb->truesize, &nf_frags.mem);
 129         nf_skb_free(skb);
 130         kfree_skb(skb);
 131 }
 132
 133 static void nf_frag_free(struct inet_frag_queue *q)
 134 {
 135         kfree(container_of(q, struct nf_ct_frag6_queue, q));
 136 }
 137
 138 static inline struct nf_ct_frag6_queue *frag_alloc_queue(void)
 139 {
 140         struct nf_ct_frag6_queue *fq = kmalloc(sizeof(struct nf_ct_frag6_queue), GFP_ATOMIC);
 141
 142         if (!fq)
 143                 return NULL;
 144         atomic_add(sizeof(struct nf_ct_frag6_queue), &nf_frags.mem);
 145         return fq;
 146 }
 147
 148 /* Destruction primitives. */
 149
 150 static __inline__ void fq_put(struct nf_ct_frag6_queue *fq)
 151 {
 152         inet_frag_put(&fq->q, &nf_frags);
 153 }
 154
 155 /* Kill fq entry. It is not destroyed immediately,
 156  * because caller (and someone more) holds reference count.
 157  */
 158 static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
 159 {
 160         inet_frag_kill(&fq->q, &nf_frags);
 161 }
 162
 163 static void nf_ct_frag6_evictor(void)
 164 {
 165         inet_frag_evictor(&nf_frags);
 166 }
 167
 168 static void nf_ct_frag6_expire(unsigned long data)
 169 {
 170         struct nf_ct_frag6_queue *fq = (struct nf_ct_frag6_queue *) data;
 171
 172         spin_lock(&fq->q.lock);
 173
 174         if (fq->q.last_in & COMPLETE)
 175                 goto out;
 176
 177         fq_kill(fq);
 178
 179 out:
 180         spin_unlock(&fq->q.lock);
 181         fq_put(fq);
 182 }
 183
 184 /* Creation primitives. */
 185
 186 static struct nf_ct_frag6_queue *nf_ct_frag6_intern(unsigned int hash,
 187                                           struct nf_ct_frag6_queue *fq_in)
 188 {
 189         struct nf_ct_frag6_queue *fq;
 190 #ifdef CONFIG_SMP
 191         struct hlist_node *n;
 192 #endif
 193
 194         write_lock(&nf_frags.lock);
 195 #ifdef CONFIG_SMP
 196         hlist_for_each_entry(fq, n, &nf_frags.hash[hash], q.list) {
 197                 if (fq->id == fq_in->id &&
 198                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 199                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 200                         atomic_inc(&fq->q.refcnt);
 201                         write_unlock(&nf_frags.lock);
 202                         fq_in->q.last_in |= COMPLETE;
 203                         fq_put(fq_in);
 204                         return fq;
 205                 }
 206         }
 207 #endif
 208         fq = fq_in;
 209
 210         if (!mod_timer(&fq->q.timer, jiffies + nf_frags_ctl.timeout))
 211                 atomic_inc(&fq->q.refcnt);
 212
 213         atomic_inc(&fq->q.refcnt);
 214         hlist_add_head(&fq->q.list, &nf_frags.hash[hash]);
 215         INIT_LIST_HEAD(&fq->q.lru_list);
 216         list_add_tail(&fq->q.lru_list, &nf_frags.lru_list);
 217         nf_frags.nqueues++;
 218         write_unlock(&nf_frags.lock);
 219         return fq;
 220 }
 221
 222
 223 static struct nf_ct_frag6_queue *
 224 nf_ct_frag6_create(unsigned int hash, __be32 id, struct in6_addr *src,                             struct in6_addr *dst)
 225 {
 226         struct nf_ct_frag6_queue *fq;
 227
 228         if ((fq = frag_alloc_queue()) == NULL) {
 229                 pr_debug("Can't alloc new queue\n");
 230                 goto oom;
 231         }
 232
 233         memset(fq, 0, sizeof(struct nf_ct_frag6_queue));
 234
 235         fq->id = id;
 236         ipv6_addr_copy(&fq->saddr, src);
 237         ipv6_addr_copy(&fq->daddr, dst);
 238
 239         setup_timer(&fq->q.timer, nf_ct_frag6_expire, (unsigned long)fq);
 240         spin_lock_init(&fq->q.lock);
 241         atomic_set(&fq->q.refcnt, 1);
 242
 243         return nf_ct_frag6_intern(hash, fq);
 244
 245 oom:
 246         return NULL;
 247 }
 248
 249 static __inline__ struct nf_ct_frag6_queue *
 250 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
 251 {
 252         struct nf_ct_frag6_queue *fq;
 253         struct hlist_node *n;
 254         unsigned int hash = ip6qhashfn(id, src, dst);
 255
 256         read_lock(&nf_frags.lock);
 257         hlist_for_each_entry(fq, n, &nf_frags.hash[hash], q.list) {
 258                 if (fq->id == id &&
 259                     ipv6_addr_equal(src, &fq->saddr) &&
 260                     ipv6_addr_equal(dst, &fq->daddr)) {
 261                         atomic_inc(&fq->q.refcnt);
 262                         read_unlock(&nf_frags.lock);
 263                         return fq;
 264                 }
 265         }
 266         read_unlock(&nf_frags.lock);
 267
 268         return nf_ct_frag6_create(hash, id, src, dst);
 269 }
 270
 271
 272 static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
 273                              struct frag_hdr *fhdr, int nhoff)
 274 {
 275         struct sk_buff *prev, *next;
 276         int offset, end;
 277
 278         if (fq->q.last_in & COMPLETE) {
 279                 pr_debug("Allready completed\n");
 280                 goto err;
 281         }
 282
 283         offset = ntohs(fhdr->frag_off) & ~0x7;
 284         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 285                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 286
 287         if ((unsigned int)end > IPV6_MAXPLEN) {
 288                 pr_debug("offset is too large.\n");
 289                 return -1;
 290         }
 291
 292         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 293                 const unsigned char *nh = skb_network_header(skb);
 294                 skb->csum = csum_sub(skb->csum,
 295                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 296                                                   0));
 297         }
 298
 299         /* Is this the final fragment? */
 300         if (!(fhdr->frag_off & htons(IP6_MF))) {
 301                 /* If we already have some bits beyond end
 302                  * or have different end, the segment is corrupted.
 303                  */
 304                 if (end < fq->q.len ||
 305                     ((fq->q.last_in & LAST_IN) && end != fq->q.len)) {
 306                         pr_debug("already received last fragment\n");
 307                         goto err;
 308                 }
 309                 fq->q.last_in |= LAST_IN;
 310                 fq->q.len = end;
 311         } else {
 312                 /* Check if the fragment is rounded to 8 bytes.
 313                  * Required by the RFC.
 314                  */
 315                 if (end & 0x7) {
 316                         /* RFC2460 says always send parameter problem in
 317                          * this case. -DaveM
 318                          */
 319                         pr_debug("end of fragment not rounded to 8 bytes.\n");
 320                         return -1;
 321                 }
 322                 if (end > fq->q.len) {
 323                         /* Some bits beyond end -> corruption. */
 324                         if (fq->q.last_in & LAST_IN) {
 325                                 pr_debug("last packet already reached.\n");
 326                                 goto err;
 327                         }
 328                         fq->q.len = end;
 329                 }
 330         }
 331
 332         if (end == offset)
 333                 goto err;
 334
 335         /* Point into the IP datagram 'data' part. */
 336         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
 337                 pr_debug("queue: message is too short.\n");
 338                 goto err;
 339         }
 340         if (pskb_trim_rcsum(skb, end - offset)) {
 341                 pr_debug("Can't trim\n");
 342                 goto err;
 343         }
 344
 345         /* Find out which fragments are in front and at the back of us
 346          * in the chain of fragments so far.  We must know where to put
 347          * this fragment, right?
 348          */
 349         prev = NULL;
 350         for (next = fq->q.fragments; next != NULL; next = next->next) {
 351                 if (NFCT_FRAG6_CB(next)->offset >= offset)
 352                         break;  /* bingo! */
 353                 prev = next;
 354         }
 355
 356         /* We found where to put this one.  Check for overlap with
 357          * preceding fragment, and, if needed, align things so that
 358          * any overlaps are eliminated.
 359          */
 360         if (prev) {
 361                 int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset;
 362
 363                 if (i > 0) {
 364                         offset += i;
 365                         if (end <= offset) {
 366                                 pr_debug("overlap\n");
 367                                 goto err;
 368                         }
 369                         if (!pskb_pull(skb, i)) {
 370                                 pr_debug("Can't pull\n");
 371                                 goto err;
 372                         }
 373                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 374                                 skb->ip_summed = CHECKSUM_NONE;
 375                 }
 376         }
 377
 378         /* Look for overlap with succeeding segments.
 379          * If we can merge fragments, do it.
 380          */
 381         while (next && NFCT_FRAG6_CB(next)->offset < end) {
 382                 /* overlap is 'i' bytes */
 383                 int i = end - NFCT_FRAG6_CB(next)->offset;
 384
 385                 if (i < next->len) {
 386                         /* Eat head of the next overlapped fragment
 387                          * and leave the loop. The next ones cannot overlap.
 388                          */
 389                         pr_debug("Eat head of the overlapped parts.: %d", i);
 390                         if (!pskb_pull(next, i))
 391                                 goto err;
 392
 393                         /* next fragment */
 394                         NFCT_FRAG6_CB(next)->offset += i;
 395                         fq->q.meat -= i;
 396                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 397                                 next->ip_summed = CHECKSUM_NONE;
 398                         break;
 399                 } else {
 400                         struct sk_buff *free_it = next;
 401
 402                         /* Old fragmnet is completely overridden with
 403                          * new one drop it.
 404                          */
 405                         next = next->next;
 406
 407                         if (prev)
 408                                 prev->next = next;
 409                         else
 410                                 fq->q.fragments = next;
 411
 412                         fq->q.meat -= free_it->len;
 413                         frag_kfree_skb(free_it, NULL);
 414                 }
 415         }
 416
 417         NFCT_FRAG6_CB(skb)->offset = offset;
 418
 419         /* Insert this fragment in the chain of fragments. */
 420         skb->next = next;
 421         if (prev)
 422                 prev->next = skb;
 423         else
 424                 fq->q.fragments = skb;
 425
 426         skb->dev = NULL;
 427         fq->q.stamp = skb->tstamp;
 428         fq->q.meat += skb->len;
 429         atomic_add(skb->truesize, &nf_frags.mem);
 430
 431         /* The first fragment.
 432          * nhoffset is obtained from the first fragment, of course.
 433          */
 434         if (offset == 0) {
 435                 fq->nhoffset = nhoff;
 436                 fq->q.last_in |= FIRST_IN;
 437         }
 438         write_lock(&nf_frags.lock);
 439         list_move_tail(&fq->q.lru_list, &nf_frags.lru_list);
 440         write_unlock(&nf_frags.lock);
 441         return 0;
 442
 443 err:
 444         return -1;
 445 }
 446
 447 /*
 448  *      Check if this packet is complete.
 449  *      Returns NULL on failure by any reason, and pointer
 450  *      to current nexthdr field in reassembled frame.
 451  *
 452  *      It is called with locked fq, and caller must check that
 453  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 454  *      the last and the first frames arrived and all the bits are here.
 455  */
 456 static struct sk_buff *
 457 nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
 458 {
 459         struct sk_buff *fp, *op, *head = fq->q.fragments;
 460         int    payload_len;
 461
 462         fq_kill(fq);
 463
 464         BUG_TRAP(head != NULL);
 465         BUG_TRAP(NFCT_FRAG6_CB(head)->offset == 0);
 466
 467         /* Unfragmented part is taken from the first segment. */
 468         payload_len = ((head->data - skb_network_header(head)) -
 469                        sizeof(struct ipv6hdr) + fq->q.len -
 470                        sizeof(struct frag_hdr));
 471         if (payload_len > IPV6_MAXPLEN) {
 472                 pr_debug("payload len is too large.\n");
 473                 goto out_oversize;
 474         }
 475
 476         /* Head of list must not be cloned. */
 477         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
 478                 pr_debug("skb is cloned but can't expand head");
 479                 goto out_oom;
 480         }
 481
 482         /* If the first fragment is fragmented itself, we split
 483          * it to two chunks: the first with data and paged part
 484          * and the second, holding only fragments. */
 485         if (skb_shinfo(head)->frag_list) {
 486                 struct sk_buff *clone;
 487                 int i, plen = 0;
 488
 489                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
 490                         pr_debug("Can't alloc skb\n");
 491                         goto out_oom;
 492                 }
 493                 clone->next = head->next;
 494                 head->next = clone;
 495                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 496                 skb_shinfo(head)->frag_list = NULL;
 497                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 498                         plen += skb_shinfo(head)->frags[i].size;
 499                 clone->len = clone->data_len = head->data_len - plen;
 500                 head->data_len -= clone->len;
 501                 head->len -= clone->len;
 502                 clone->csum = 0;
 503                 clone->ip_summed = head->ip_summed;
 504
 505                 NFCT_FRAG6_CB(clone)->orig = NULL;
 506                 atomic_add(clone->truesize, &nf_frags.mem);
 507         }
 508
 509         /* We have to remove fragment header from datagram and to relocate
 510          * header in order to calculate ICV correctly. */
 511         skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
 512         memmove(head->head + sizeof(struct frag_hdr), head->head,
 513                 (head->data - head->head) - sizeof(struct frag_hdr));
 514         head->mac_header += sizeof(struct frag_hdr);
 515         head->network_header += sizeof(struct frag_hdr);
 516
 517         skb_shinfo(head)->frag_list = head->next;
 518         skb_reset_transport_header(head);
 519         skb_push(head, head->data - skb_network_header(head));
 520         atomic_sub(head->truesize, &nf_frags.mem);
 521
 522         for (fp=head->next; fp; fp = fp->next) {
 523                 head->data_len += fp->len;
 524                 head->len += fp->len;
 525                 if (head->ip_summed != fp->ip_summed)
 526                         head->ip_summed = CHECKSUM_NONE;
 527                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 528                         head->csum = csum_add(head->csum, fp->csum);
 529                 head->truesize += fp->truesize;
 530                 atomic_sub(fp->truesize, &nf_frags.mem);
 531         }
 532
 533         head->next = NULL;
 534         head->dev = dev;
 535         head->tstamp = fq->q.stamp;
 536         ipv6_hdr(head)->payload_len = htons(payload_len);
 537
 538         /* Yes, and fold redundant checksum back. 8) */
 539         if (head->ip_summed == CHECKSUM_COMPLETE)
 540                 head->csum = csum_partial(skb_network_header(head),
 541                                           skb_network_header_len(head),
 542                                           head->csum);
 543
 544         fq->q.fragments = NULL;
 545
 546         /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
 547         fp = skb_shinfo(head)->frag_list;
 548         if (NFCT_FRAG6_CB(fp)->orig == NULL)
 549                 /* at above code, head skb is divided into two skbs. */
 550                 fp = fp->next;
 551
 552         op = NFCT_FRAG6_CB(head)->orig;
 553         for (; fp; fp = fp->next) {
 554                 struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
 555
 556                 op->next = orig;
 557                 op = orig;
 558                 NFCT_FRAG6_CB(fp)->orig = NULL;
 559         }
 560
 561         return head;
 562
 563 out_oversize:
 564         if (net_ratelimit())
 565                 printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len);
 566         goto out_fail;
 567 out_oom:
 568         if (net_ratelimit())
 569                 printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n");
 570 out_fail:
 571         return NULL;
 572 }
 573
 574 /*
 575  * find the header just before Fragment Header.
 576  *
 577  * if success return 0 and set ...
 578  * (*prevhdrp): the value of "Next Header Field" in the header
 579  *              just before Fragment Header.
 580  * (*prevhoff): the offset of "Next Header Field" in the header
 581  *              just before Fragment Header.
 582  * (*fhoff)   : the offset of Fragment Header.
 583  *
 584  * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
 585  *
 586  */
 587 static int
 588 find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
 589 {
 590         u8 nexthdr = ipv6_hdr(skb)->nexthdr;
 591         const int netoff = skb_network_offset(skb);
 592         u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr);
 593         int start = netoff + sizeof(struct ipv6hdr);
 594         int len = skb->len - start;
 595         u8 prevhdr = NEXTHDR_IPV6;
 596
 597         while (nexthdr != NEXTHDR_FRAGMENT) {
 598                 struct ipv6_opt_hdr hdr;
 599                 int hdrlen;
 600
 601                 if (!ipv6_ext_hdr(nexthdr)) {
 602                         return -1;
 603                 }
 604                 if (len < (int)sizeof(struct ipv6_opt_hdr)) {
 605                         pr_debug("too short\n");
 606                         return -1;
 607                 }
 608                 if (nexthdr == NEXTHDR_NONE) {
 609                         pr_debug("next header is none\n");
 610                         return -1;
 611                 }
 612                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 613                         BUG();
 614                 if (nexthdr == NEXTHDR_AUTH)
 615                         hdrlen = (hdr.hdrlen+2)<<2;
 616                 else
 617                         hdrlen = ipv6_optlen(&hdr);
 618
 619                 prevhdr = nexthdr;
 620                 prev_nhoff = start;
 621
 622                 nexthdr = hdr.nexthdr;
 623                 len -= hdrlen;
 624                 start += hdrlen;
 625         }
 626
 627         if (len < 0)
 628                 return -1;
 629
 630         *prevhdrp = prevhdr;
 631         *prevhoff = prev_nhoff;
 632         *fhoff = start;
 633
 634         return 0;
 635 }
 636
 637 struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
 638 {
 639         struct sk_buff *clone;
 640         struct net_device *dev = skb->dev;
 641         struct frag_hdr *fhdr;
 642         struct nf_ct_frag6_queue *fq;
 643         struct ipv6hdr *hdr;
 644         int fhoff, nhoff;
 645         u8 prevhdr;
 646         struct sk_buff *ret_skb = NULL;
 647
 648         /* Jumbo payload inhibits frag. header */
 649         if (ipv6_hdr(skb)->payload_len == 0) {
 650                 pr_debug("payload len = 0\n");
 651                 return skb;
 652         }
 653
 654         if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
 655                 return skb;
 656
 657         clone = skb_clone(skb, GFP_ATOMIC);
 658         if (clone == NULL) {
 659                 pr_debug("Can't clone skb\n");
 660                 return skb;
 661         }
 662
 663         NFCT_FRAG6_CB(clone)->orig = skb;
 664
 665         if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
 666                 pr_debug("message is too short.\n");
 667                 goto ret_orig;
 668         }
 669
 670         skb_set_transport_header(clone, fhoff);
 671         hdr = ipv6_hdr(clone);
 672         fhdr = (struct frag_hdr *)skb_transport_header(clone);
 673
 674         if (!(fhdr->frag_off & htons(0xFFF9))) {
 675                 pr_debug("Invalid fragment offset\n");
 676                 /* It is not a fragmented frame */
 677                 goto ret_orig;
 678         }
 679
 680         if (atomic_read(&nf_frags.mem) > nf_frags_ctl.high_thresh)
 681                 nf_ct_frag6_evictor();
 682
 683         fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
 684         if (fq == NULL) {
 685                 pr_debug("Can't find and can't create new queue\n");
 686                 goto ret_orig;
 687         }
 688
 689         spin_lock(&fq->q.lock);
 690
 691         if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
 692                 spin_unlock(&fq->q.lock);
 693                 pr_debug("Can't insert skb to queue\n");
 694                 fq_put(fq);
 695                 goto ret_orig;
 696         }
 697
 698         if (fq->q.last_in == (FIRST_IN|LAST_IN) && fq->q.meat == fq->q.len) {
 699                 ret_skb = nf_ct_frag6_reasm(fq, dev);
 700                 if (ret_skb == NULL)
 701                         pr_debug("Can't reassemble fragmented packets\n");
 702         }
 703         spin_unlock(&fq->q.lock);
 704
 705         fq_put(fq);
 706         return ret_skb;
 707
 708 ret_orig:
 709         kfree_skb(clone);
 710         return skb;
 711 }
 712
 713 void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
 714                         struct net_device *in, struct net_device *out,
 715                         int (*okfn)(struct sk_buff *))
 716 {
 717         struct sk_buff *s, *s2;
 718
 719         for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
 720                 nf_conntrack_put_reasm(s->nfct_reasm);
 721                 nf_conntrack_get_reasm(skb);
 722                 s->nfct_reasm = skb;
 723
 724                 s2 = s->next;
 725                 s->next = NULL;
 726
 727                 NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn,
 728                                NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
 729                 s = s2;
 730         }
 731         nf_conntrack_put_reasm(skb);
 732 }
 733
 734 int nf_ct_frag6_kfree_frags(struct sk_buff *skb)
 735 {
 736         struct sk_buff *s, *s2;
 737
 738         for (s = NFCT_FRAG6_CB(skb)->orig; s; s = s2) {
 739
 740                 s2 = s->next;
 741                 kfree_skb(s);
 742         }
 743
 744         kfree_skb(skb);
 745
 746         return 0;
 747 }
 748
 749 int nf_ct_frag6_init(void)
 750 {
 751         nf_frags.ctl = &nf_frags_ctl;
 752         nf_frags.hashfn = nf_hashfn;
 753         nf_frags.destructor = nf_frag_free;
 754         nf_frags.skb_free = nf_skb_free;
 755         nf_frags.qsize = sizeof(struct nf_ct_frag6_queue);
 756         inet_frags_init(&nf_frags);
 757
 758         return 0;
 759 }
 760
 761 void nf_ct_frag6_cleanup(void)
 762 {
 763         inet_frags_fini(&nf_frags);
 764
 765         nf_frags_ctl.low_thresh = 0;
 766         nf_ct_frag6_evictor();
 767 }