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
  35 #include <net/ipv6.h>
  36 #include <net/protocol.h>
  37 #include <net/transp_v6.h>
  38 #include <net/rawv6.h>
  39 #include <net/ndisc.h>
  40 #include <net/addrconf.h>
  41 #include <linux/sysctl.h>
  42 #include <linux/netfilter.h>
  43 #include <linux/netfilter_ipv6.h>
  44 #include <linux/kernel.h>
  45 #include <linux/module.h>
  46
  47 #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
  48 #define NF_CT_FRAG6_LOW_THRESH 196608  /* == 192*1024 */
  49 #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
  50
  51 unsigned int nf_ct_frag6_high_thresh __read_mostly = 256*1024;
  52 unsigned int nf_ct_frag6_low_thresh __read_mostly = 192*1024;
  53 unsigned long nf_ct_frag6_timeout __read_mostly = IPV6_FRAG_TIMEOUT;
  54
  55 struct nf_ct_frag6_skb_cb
  56 {
  57         struct inet6_skb_parm   h;
  58         int                     offset;
  59         struct sk_buff          *orig;
  60 };
  61
  62 #define NFCT_FRAG6_CB(skb)      ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
  63
  64 struct nf_ct_frag6_queue
  65 {
  66         struct hlist_node       list;
  67         struct list_head        lru_list;       /* lru list member      */
  68
  69         __be32                  id;             /* fragment id          */
  70         struct in6_addr         saddr;
  71         struct in6_addr         daddr;
  72
  73         spinlock_t              lock;
  74         atomic_t                refcnt;
  75         struct timer_list       timer;          /* expire timer         */
  76         struct sk_buff          *fragments;
  77         int                     len;
  78         int                     meat;
  79         ktime_t                 stamp;
  80         unsigned int            csum;
  81         __u8                    last_in;        /* has first/last segment arrived? */
  82 #define COMPLETE                4
  83 #define FIRST_IN                2
  84 #define LAST_IN                 1
  85         __u16                   nhoffset;
  86 };
  87
  88 /* Hash table. */
  89
  90 #define FRAG6Q_HASHSZ   64
  91
  92 static struct hlist_head nf_ct_frag6_hash[FRAG6Q_HASHSZ];
  93 static DEFINE_RWLOCK(nf_ct_frag6_lock);
  94 static u32 nf_ct_frag6_hash_rnd;
  95 static LIST_HEAD(nf_ct_frag6_lru_list);
  96 int nf_ct_frag6_nqueues = 0;
  97
  98 static __inline__ void __fq_unlink(struct nf_ct_frag6_queue *fq)
  99 {
 100         hlist_del(&fq->list);
 101         list_del(&fq->lru_list);
 102         nf_ct_frag6_nqueues--;
 103 }
 104
 105 static __inline__ void fq_unlink(struct nf_ct_frag6_queue *fq)
 106 {
 107         write_lock(&nf_ct_frag6_lock);
 108         __fq_unlink(fq);
 109         write_unlock(&nf_ct_frag6_lock);
 110 }
 111
 112 static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr,
 113                                struct in6_addr *daddr)
 114 {
 115         u32 a, b, c;
 116
 117         a = (__force u32)saddr->s6_addr32[0];
 118         b = (__force u32)saddr->s6_addr32[1];
 119         c = (__force u32)saddr->s6_addr32[2];
 120
 121         a += JHASH_GOLDEN_RATIO;
 122         b += JHASH_GOLDEN_RATIO;
 123         c += nf_ct_frag6_hash_rnd;
 124         __jhash_mix(a, b, c);
 125
 126         a += (__force u32)saddr->s6_addr32[3];
 127         b += (__force u32)daddr->s6_addr32[0];
 128         c += (__force u32)daddr->s6_addr32[1];
 129         __jhash_mix(a, b, c);
 130
 131         a += (__force u32)daddr->s6_addr32[2];
 132         b += (__force u32)daddr->s6_addr32[3];
 133         c += (__force u32)id;
 134         __jhash_mix(a, b, c);
 135
 136         return c & (FRAG6Q_HASHSZ - 1);
 137 }
 138
 139 static struct timer_list nf_ct_frag6_secret_timer;
 140 int nf_ct_frag6_secret_interval = 10 * 60 * HZ;
 141
 142 static void nf_ct_frag6_secret_rebuild(unsigned long dummy)
 143 {
 144         unsigned long now = jiffies;
 145         int i;
 146
 147         write_lock(&nf_ct_frag6_lock);
 148         get_random_bytes(&nf_ct_frag6_hash_rnd, sizeof(u32));
 149         for (i = 0; i < FRAG6Q_HASHSZ; i++) {
 150                 struct nf_ct_frag6_queue *q;
 151                 struct hlist_node *p, *n;
 152
 153                 hlist_for_each_entry_safe(q, p, n, &nf_ct_frag6_hash[i], list) {
 154                         unsigned int hval = ip6qhashfn(q->id,
 155                                                        &q->saddr,
 156                                                        &q->daddr);
 157                         if (hval != i) {
 158                                 hlist_del(&q->list);
 159                                 /* Relink to new hash chain. */
 160                                 hlist_add_head(&q->list,
 161                                                &nf_ct_frag6_hash[hval]);
 162                         }
 163                 }
 164         }
 165         write_unlock(&nf_ct_frag6_lock);
 166
 167         mod_timer(&nf_ct_frag6_secret_timer, now + nf_ct_frag6_secret_interval);
 168 }
 169
 170 atomic_t nf_ct_frag6_mem = ATOMIC_INIT(0);
 171
 172 /* Memory Tracking Functions. */
 173 static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
 174 {
 175         if (work)
 176                 *work -= skb->truesize;
 177         atomic_sub(skb->truesize, &nf_ct_frag6_mem);
 178         if (NFCT_FRAG6_CB(skb)->orig)
 179                 kfree_skb(NFCT_FRAG6_CB(skb)->orig);
 180
 181         kfree_skb(skb);
 182 }
 183
 184 static inline void frag_free_queue(struct nf_ct_frag6_queue *fq,
 185                                    unsigned int *work)
 186 {
 187         if (work)
 188                 *work -= sizeof(struct nf_ct_frag6_queue);
 189         atomic_sub(sizeof(struct nf_ct_frag6_queue), &nf_ct_frag6_mem);
 190         kfree(fq);
 191 }
 192
 193 static inline struct nf_ct_frag6_queue *frag_alloc_queue(void)
 194 {
 195         struct nf_ct_frag6_queue *fq = kmalloc(sizeof(struct nf_ct_frag6_queue), GFP_ATOMIC);
 196
 197         if (!fq)
 198                 return NULL;
 199         atomic_add(sizeof(struct nf_ct_frag6_queue), &nf_ct_frag6_mem);
 200         return fq;
 201 }
 202
 203 /* Destruction primitives. */
 204
 205 /* Complete destruction of fq. */
 206 static void nf_ct_frag6_destroy(struct nf_ct_frag6_queue *fq,
 207                                 unsigned int *work)
 208 {
 209         struct sk_buff *fp;
 210
 211         BUG_TRAP(fq->last_in&COMPLETE);
 212         BUG_TRAP(del_timer(&fq->timer) == 0);
 213
 214         /* Release all fragment data. */
 215         fp = fq->fragments;
 216         while (fp) {
 217                 struct sk_buff *xp = fp->next;
 218
 219                 frag_kfree_skb(fp, work);
 220                 fp = xp;
 221         }
 222
 223         frag_free_queue(fq, work);
 224 }
 225
 226 static __inline__ void fq_put(struct nf_ct_frag6_queue *fq, unsigned int *work)
 227 {
 228         if (atomic_dec_and_test(&fq->refcnt))
 229                 nf_ct_frag6_destroy(fq, work);
 230 }
 231
 232 /* Kill fq entry. It is not destroyed immediately,
 233  * because caller (and someone more) holds reference count.
 234  */
 235 static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
 236 {
 237         if (del_timer(&fq->timer))
 238                 atomic_dec(&fq->refcnt);
 239
 240         if (!(fq->last_in & COMPLETE)) {
 241                 fq_unlink(fq);
 242                 atomic_dec(&fq->refcnt);
 243                 fq->last_in |= COMPLETE;
 244         }
 245 }
 246
 247 static void nf_ct_frag6_evictor(void)
 248 {
 249         struct nf_ct_frag6_queue *fq;
 250         struct list_head *tmp;
 251         unsigned int work;
 252
 253         work = atomic_read(&nf_ct_frag6_mem);
 254         if (work <= nf_ct_frag6_low_thresh)
 255                 return;
 256
 257         work -= nf_ct_frag6_low_thresh;
 258         while (work > 0) {
 259                 read_lock(&nf_ct_frag6_lock);
 260                 if (list_empty(&nf_ct_frag6_lru_list)) {
 261                         read_unlock(&nf_ct_frag6_lock);
 262                         return;
 263                 }
 264                 tmp = nf_ct_frag6_lru_list.next;
 265                 BUG_ON(tmp == NULL);
 266                 fq = list_entry(tmp, struct nf_ct_frag6_queue, lru_list);
 267                 atomic_inc(&fq->refcnt);
 268                 read_unlock(&nf_ct_frag6_lock);
 269
 270                 spin_lock(&fq->lock);
 271                 if (!(fq->last_in&COMPLETE))
 272                         fq_kill(fq);
 273                 spin_unlock(&fq->lock);
 274
 275                 fq_put(fq, &work);
 276         }
 277 }
 278
 279 static void nf_ct_frag6_expire(unsigned long data)
 280 {
 281         struct nf_ct_frag6_queue *fq = (struct nf_ct_frag6_queue *) data;
 282
 283         spin_lock(&fq->lock);
 284
 285         if (fq->last_in & COMPLETE)
 286                 goto out;
 287
 288         fq_kill(fq);
 289
 290 out:
 291         spin_unlock(&fq->lock);
 292         fq_put(fq, NULL);
 293 }
 294
 295 /* Creation primitives. */
 296
 297 static struct nf_ct_frag6_queue *nf_ct_frag6_intern(unsigned int hash,
 298                                           struct nf_ct_frag6_queue *fq_in)
 299 {
 300         struct nf_ct_frag6_queue *fq;
 301 #ifdef CONFIG_SMP
 302         struct hlist_node *n;
 303 #endif
 304
 305         write_lock(&nf_ct_frag6_lock);
 306 #ifdef CONFIG_SMP
 307         hlist_for_each_entry(fq, n, &nf_ct_frag6_hash[hash], list) {
 308                 if (fq->id == fq_in->id &&
 309                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
 310                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
 311                         atomic_inc(&fq->refcnt);
 312                         write_unlock(&nf_ct_frag6_lock);
 313                         fq_in->last_in |= COMPLETE;
 314                         fq_put(fq_in, NULL);
 315                         return fq;
 316                 }
 317         }
 318 #endif
 319         fq = fq_in;
 320
 321         if (!mod_timer(&fq->timer, jiffies + nf_ct_frag6_timeout))
 322                 atomic_inc(&fq->refcnt);
 323
 324         atomic_inc(&fq->refcnt);
 325         hlist_add_head(&fq->list, &nf_ct_frag6_hash[hash]);
 326         INIT_LIST_HEAD(&fq->lru_list);
 327         list_add_tail(&fq->lru_list, &nf_ct_frag6_lru_list);
 328         nf_ct_frag6_nqueues++;
 329         write_unlock(&nf_ct_frag6_lock);
 330         return fq;
 331 }
 332
 333
 334 static struct nf_ct_frag6_queue *
 335 nf_ct_frag6_create(unsigned int hash, __be32 id, struct in6_addr *src,                             struct in6_addr *dst)
 336 {
 337         struct nf_ct_frag6_queue *fq;
 338
 339         if ((fq = frag_alloc_queue()) == NULL) {
 340                 pr_debug("Can't alloc new queue\n");
 341                 goto oom;
 342         }
 343
 344         memset(fq, 0, sizeof(struct nf_ct_frag6_queue));
 345
 346         fq->id = id;
 347         ipv6_addr_copy(&fq->saddr, src);
 348         ipv6_addr_copy(&fq->daddr, dst);
 349
 350         setup_timer(&fq->timer, nf_ct_frag6_expire, (unsigned long)fq);
 351         spin_lock_init(&fq->lock);
 352         atomic_set(&fq->refcnt, 1);
 353
 354         return nf_ct_frag6_intern(hash, fq);
 355
 356 oom:
 357         return NULL;
 358 }
 359
 360 static __inline__ struct nf_ct_frag6_queue *
 361 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
 362 {
 363         struct nf_ct_frag6_queue *fq;
 364         struct hlist_node *n;
 365         unsigned int hash = ip6qhashfn(id, src, dst);
 366
 367         read_lock(&nf_ct_frag6_lock);
 368         hlist_for_each_entry(fq, n, &nf_ct_frag6_hash[hash], list) {
 369                 if (fq->id == id &&
 370                     ipv6_addr_equal(src, &fq->saddr) &&
 371                     ipv6_addr_equal(dst, &fq->daddr)) {
 372                         atomic_inc(&fq->refcnt);
 373                         read_unlock(&nf_ct_frag6_lock);
 374                         return fq;
 375                 }
 376         }
 377         read_unlock(&nf_ct_frag6_lock);
 378
 379         return nf_ct_frag6_create(hash, id, src, dst);
 380 }
 381
 382
 383 static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
 384                              struct frag_hdr *fhdr, int nhoff)
 385 {
 386         struct sk_buff *prev, *next;
 387         int offset, end;
 388
 389         if (fq->last_in & COMPLETE) {
 390                 pr_debug("Allready completed\n");
 391                 goto err;
 392         }
 393
 394         offset = ntohs(fhdr->frag_off) & ~0x7;
 395         end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 396                         ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
 397
 398         if ((unsigned int)end > IPV6_MAXPLEN) {
 399                 pr_debug("offset is too large.\n");
 400                 return -1;
 401         }
 402
 403         if (skb->ip_summed == CHECKSUM_COMPLETE) {
 404                 const unsigned char *nh = skb_network_header(skb);
 405                 skb->csum = csum_sub(skb->csum,
 406                                      csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 407                                                   0));
 408         }
 409
 410         /* Is this the final fragment? */
 411         if (!(fhdr->frag_off & htons(IP6_MF))) {
 412                 /* If we already have some bits beyond end
 413                  * or have different end, the segment is corrupted.
 414                  */
 415                 if (end < fq->len ||
 416                     ((fq->last_in & LAST_IN) && end != fq->len)) {
 417                         pr_debug("already received last fragment\n");
 418                         goto err;
 419                 }
 420                 fq->last_in |= LAST_IN;
 421                 fq->len = end;
 422         } else {
 423                 /* Check if the fragment is rounded to 8 bytes.
 424                  * Required by the RFC.
 425                  */
 426                 if (end & 0x7) {
 427                         /* RFC2460 says always send parameter problem in
 428                          * this case. -DaveM
 429                          */
 430                         pr_debug("end of fragment not rounded to 8 bytes.\n");
 431                         return -1;
 432                 }
 433                 if (end > fq->len) {
 434                         /* Some bits beyond end -> corruption. */
 435                         if (fq->last_in & LAST_IN) {
 436                                 pr_debug("last packet already reached.\n");
 437                                 goto err;
 438                         }
 439                         fq->len = end;
 440                 }
 441         }
 442
 443         if (end == offset)
 444                 goto err;
 445
 446         /* Point into the IP datagram 'data' part. */
 447         if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
 448                 pr_debug("queue: message is too short.\n");
 449                 goto err;
 450         }
 451         if (pskb_trim_rcsum(skb, end - offset)) {
 452                 pr_debug("Can't trim\n");
 453                 goto err;
 454         }
 455
 456         /* Find out which fragments are in front and at the back of us
 457          * in the chain of fragments so far.  We must know where to put
 458          * this fragment, right?
 459          */
 460         prev = NULL;
 461         for (next = fq->fragments; next != NULL; next = next->next) {
 462                 if (NFCT_FRAG6_CB(next)->offset >= offset)
 463                         break;  /* bingo! */
 464                 prev = next;
 465         }
 466
 467         /* We found where to put this one.  Check for overlap with
 468          * preceding fragment, and, if needed, align things so that
 469          * any overlaps are eliminated.
 470          */
 471         if (prev) {
 472                 int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset;
 473
 474                 if (i > 0) {
 475                         offset += i;
 476                         if (end <= offset) {
 477                                 pr_debug("overlap\n");
 478                                 goto err;
 479                         }
 480                         if (!pskb_pull(skb, i)) {
 481                                 pr_debug("Can't pull\n");
 482                                 goto err;
 483                         }
 484                         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 485                                 skb->ip_summed = CHECKSUM_NONE;
 486                 }
 487         }
 488
 489         /* Look for overlap with succeeding segments.
 490          * If we can merge fragments, do it.
 491          */
 492         while (next && NFCT_FRAG6_CB(next)->offset < end) {
 493                 /* overlap is 'i' bytes */
 494                 int i = end - NFCT_FRAG6_CB(next)->offset;
 495
 496                 if (i < next->len) {
 497                         /* Eat head of the next overlapped fragment
 498                          * and leave the loop. The next ones cannot overlap.
 499                          */
 500                         pr_debug("Eat head of the overlapped parts.: %d", i);
 501                         if (!pskb_pull(next, i))
 502                                 goto err;
 503
 504                         /* next fragment */
 505                         NFCT_FRAG6_CB(next)->offset += i;
 506                         fq->meat -= i;
 507                         if (next->ip_summed != CHECKSUM_UNNECESSARY)
 508                                 next->ip_summed = CHECKSUM_NONE;
 509                         break;
 510                 } else {
 511                         struct sk_buff *free_it = next;
 512
 513                         /* Old fragmnet is completely overridden with
 514                          * new one drop it.
 515                          */
 516                         next = next->next;
 517
 518                         if (prev)
 519                                 prev->next = next;
 520                         else
 521                                 fq->fragments = next;
 522
 523                         fq->meat -= free_it->len;
 524                         frag_kfree_skb(free_it, NULL);
 525                 }
 526         }
 527
 528         NFCT_FRAG6_CB(skb)->offset = offset;
 529
 530         /* Insert this fragment in the chain of fragments. */
 531         skb->next = next;
 532         if (prev)
 533                 prev->next = skb;
 534         else
 535                 fq->fragments = skb;
 536
 537         skb->dev = NULL;
 538         fq->stamp = skb->tstamp;
 539         fq->meat += skb->len;
 540         atomic_add(skb->truesize, &nf_ct_frag6_mem);
 541
 542         /* The first fragment.
 543          * nhoffset is obtained from the first fragment, of course.
 544          */
 545         if (offset == 0) {
 546                 fq->nhoffset = nhoff;
 547                 fq->last_in |= FIRST_IN;
 548         }
 549         write_lock(&nf_ct_frag6_lock);
 550         list_move_tail(&fq->lru_list, &nf_ct_frag6_lru_list);
 551         write_unlock(&nf_ct_frag6_lock);
 552         return 0;
 553
 554 err:
 555         return -1;
 556 }
 557
 558 /*
 559  *      Check if this packet is complete.
 560  *      Returns NULL on failure by any reason, and pointer
 561  *      to current nexthdr field in reassembled frame.
 562  *
 563  *      It is called with locked fq, and caller must check that
 564  *      queue is eligible for reassembly i.e. it is not COMPLETE,
 565  *      the last and the first frames arrived and all the bits are here.
 566  */
 567 static struct sk_buff *
 568 nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
 569 {
 570         struct sk_buff *fp, *op, *head = fq->fragments;
 571         int    payload_len;
 572
 573         fq_kill(fq);
 574
 575         BUG_TRAP(head != NULL);
 576         BUG_TRAP(NFCT_FRAG6_CB(head)->offset == 0);
 577
 578         /* Unfragmented part is taken from the first segment. */
 579         payload_len = ((head->data - skb_network_header(head)) -
 580                        sizeof(struct ipv6hdr) + fq->len -
 581                        sizeof(struct frag_hdr));
 582         if (payload_len > IPV6_MAXPLEN) {
 583                 pr_debug("payload len is too large.\n");
 584                 goto out_oversize;
 585         }
 586
 587         /* Head of list must not be cloned. */
 588         if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
 589                 pr_debug("skb is cloned but can't expand head");
 590                 goto out_oom;
 591         }
 592
 593         /* If the first fragment is fragmented itself, we split
 594          * it to two chunks: the first with data and paged part
 595          * and the second, holding only fragments. */
 596         if (skb_shinfo(head)->frag_list) {
 597                 struct sk_buff *clone;
 598                 int i, plen = 0;
 599
 600                 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
 601                         pr_debug("Can't alloc skb\n");
 602                         goto out_oom;
 603                 }
 604                 clone->next = head->next;
 605                 head->next = clone;
 606                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 607                 skb_shinfo(head)->frag_list = NULL;
 608                 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 609                         plen += skb_shinfo(head)->frags[i].size;
 610                 clone->len = clone->data_len = head->data_len - plen;
 611                 head->data_len -= clone->len;
 612                 head->len -= clone->len;
 613                 clone->csum = 0;
 614                 clone->ip_summed = head->ip_summed;
 615
 616                 NFCT_FRAG6_CB(clone)->orig = NULL;
 617                 atomic_add(clone->truesize, &nf_ct_frag6_mem);
 618         }
 619
 620         /* We have to remove fragment header from datagram and to relocate
 621          * header in order to calculate ICV correctly. */
 622         skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
 623         memmove(head->head + sizeof(struct frag_hdr), head->head,
 624                 (head->data - head->head) - sizeof(struct frag_hdr));
 625         head->mac_header += sizeof(struct frag_hdr);
 626         head->network_header += sizeof(struct frag_hdr);
 627
 628         skb_shinfo(head)->frag_list = head->next;
 629         skb_reset_transport_header(head);
 630         skb_push(head, head->data - skb_network_header(head));
 631         atomic_sub(head->truesize, &nf_ct_frag6_mem);
 632
 633         for (fp=head->next; fp; fp = fp->next) {
 634                 head->data_len += fp->len;
 635                 head->len += fp->len;
 636                 if (head->ip_summed != fp->ip_summed)
 637                         head->ip_summed = CHECKSUM_NONE;
 638                 else if (head->ip_summed == CHECKSUM_COMPLETE)
 639                         head->csum = csum_add(head->csum, fp->csum);
 640                 head->truesize += fp->truesize;
 641                 atomic_sub(fp->truesize, &nf_ct_frag6_mem);
 642         }
 643
 644         head->next = NULL;
 645         head->dev = dev;
 646         head->tstamp = fq->stamp;
 647         ipv6_hdr(head)->payload_len = htons(payload_len);
 648
 649         /* Yes, and fold redundant checksum back. 8) */
 650         if (head->ip_summed == CHECKSUM_COMPLETE)
 651                 head->csum = csum_partial(skb_network_header(head),
 652                                           skb_network_header_len(head),
 653                                           head->csum);
 654
 655         fq->fragments = NULL;
 656
 657         /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
 658         fp = skb_shinfo(head)->frag_list;
 659         if (NFCT_FRAG6_CB(fp)->orig == NULL)
 660                 /* at above code, head skb is divided into two skbs. */
 661                 fp = fp->next;
 662
 663         op = NFCT_FRAG6_CB(head)->orig;
 664         for (; fp; fp = fp->next) {
 665                 struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
 666
 667                 op->next = orig;
 668                 op = orig;
 669                 NFCT_FRAG6_CB(fp)->orig = NULL;
 670         }
 671
 672         return head;
 673
 674 out_oversize:
 675         if (net_ratelimit())
 676                 printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len);
 677         goto out_fail;
 678 out_oom:
 679         if (net_ratelimit())
 680                 printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n");
 681 out_fail:
 682         return NULL;
 683 }
 684
 685 /*
 686  * find the header just before Fragment Header.
 687  *
 688  * if success return 0 and set ...
 689  * (*prevhdrp): the value of "Next Header Field" in the header
 690  *              just before Fragment Header.
 691  * (*prevhoff): the offset of "Next Header Field" in the header
 692  *              just before Fragment Header.
 693  * (*fhoff)   : the offset of Fragment Header.
 694  *
 695  * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
 696  *
 697  */
 698 static int
 699 find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
 700 {
 701         u8 nexthdr = ipv6_hdr(skb)->nexthdr;
 702         const int netoff = skb_network_offset(skb);
 703         u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr);
 704         int start = netoff + sizeof(struct ipv6hdr);
 705         int len = skb->len - start;
 706         u8 prevhdr = NEXTHDR_IPV6;
 707
 708         while (nexthdr != NEXTHDR_FRAGMENT) {
 709                 struct ipv6_opt_hdr hdr;
 710                 int hdrlen;
 711
 712                 if (!ipv6_ext_hdr(nexthdr)) {
 713                         return -1;
 714                 }
 715                 if (len < (int)sizeof(struct ipv6_opt_hdr)) {
 716                         pr_debug("too short\n");
 717                         return -1;
 718                 }
 719                 if (nexthdr == NEXTHDR_NONE) {
 720                         pr_debug("next header is none\n");
 721                         return -1;
 722                 }
 723                 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 724                         BUG();
 725                 if (nexthdr == NEXTHDR_AUTH)
 726                         hdrlen = (hdr.hdrlen+2)<<2;
 727                 else
 728                         hdrlen = ipv6_optlen(&hdr);
 729
 730                 prevhdr = nexthdr;
 731                 prev_nhoff = start;
 732
 733                 nexthdr = hdr.nexthdr;
 734                 len -= hdrlen;
 735                 start += hdrlen;
 736         }
 737
 738         if (len < 0)
 739                 return -1;
 740
 741         *prevhdrp = prevhdr;
 742         *prevhoff = prev_nhoff;
 743         *fhoff = start;
 744
 745         return 0;
 746 }
 747
 748 struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
 749 {
 750         struct sk_buff *clone;
 751         struct net_device *dev = skb->dev;
 752         struct frag_hdr *fhdr;
 753         struct nf_ct_frag6_queue *fq;
 754         struct ipv6hdr *hdr;
 755         int fhoff, nhoff;
 756         u8 prevhdr;
 757         struct sk_buff *ret_skb = NULL;
 758
 759         /* Jumbo payload inhibits frag. header */
 760         if (ipv6_hdr(skb)->payload_len == 0) {
 761                 pr_debug("payload len = 0\n");
 762                 return skb;
 763         }
 764
 765         if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
 766                 return skb;
 767
 768         clone = skb_clone(skb, GFP_ATOMIC);
 769         if (clone == NULL) {
 770                 pr_debug("Can't clone skb\n");
 771                 return skb;
 772         }
 773
 774         NFCT_FRAG6_CB(clone)->orig = skb;
 775
 776         if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
 777                 pr_debug("message is too short.\n");
 778                 goto ret_orig;
 779         }
 780
 781         skb_set_transport_header(clone, fhoff);
 782         hdr = ipv6_hdr(clone);
 783         fhdr = (struct frag_hdr *)skb_transport_header(clone);
 784
 785         if (!(fhdr->frag_off & htons(0xFFF9))) {
 786                 pr_debug("Invalid fragment offset\n");
 787                 /* It is not a fragmented frame */
 788                 goto ret_orig;
 789         }
 790
 791         if (atomic_read(&nf_ct_frag6_mem) > nf_ct_frag6_high_thresh)
 792                 nf_ct_frag6_evictor();
 793
 794         fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
 795         if (fq == NULL) {
 796                 pr_debug("Can't find and can't create new queue\n");
 797                 goto ret_orig;
 798         }
 799
 800         spin_lock(&fq->lock);
 801
 802         if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
 803                 spin_unlock(&fq->lock);
 804                 pr_debug("Can't insert skb to queue\n");
 805                 fq_put(fq, NULL);
 806                 goto ret_orig;
 807         }
 808
 809         if (fq->last_in == (FIRST_IN|LAST_IN) && fq->meat == fq->len) {
 810                 ret_skb = nf_ct_frag6_reasm(fq, dev);
 811                 if (ret_skb == NULL)
 812                         pr_debug("Can't reassemble fragmented packets\n");
 813         }
 814         spin_unlock(&fq->lock);
 815
 816         fq_put(fq, NULL);
 817         return ret_skb;
 818
 819 ret_orig:
 820         kfree_skb(clone);
 821         return skb;
 822 }
 823
 824 void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
 825                         struct net_device *in, struct net_device *out,
 826                         int (*okfn)(struct sk_buff *))
 827 {
 828         struct sk_buff *s, *s2;
 829
 830         for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
 831                 nf_conntrack_put_reasm(s->nfct_reasm);
 832                 nf_conntrack_get_reasm(skb);
 833                 s->nfct_reasm = skb;
 834
 835                 s2 = s->next;
 836                 s->next = NULL;
 837
 838                 NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn,
 839                                NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
 840                 s = s2;
 841         }
 842         nf_conntrack_put_reasm(skb);
 843 }
 844
 845 int nf_ct_frag6_kfree_frags(struct sk_buff *skb)
 846 {
 847         struct sk_buff *s, *s2;
 848
 849         for (s = NFCT_FRAG6_CB(skb)->orig; s; s = s2) {
 850
 851                 s2 = s->next;
 852                 kfree_skb(s);
 853         }
 854
 855         kfree_skb(skb);
 856
 857         return 0;
 858 }
 859
 860 int nf_ct_frag6_init(void)
 861 {
 862         nf_ct_frag6_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
 863                                    (jiffies ^ (jiffies >> 6)));
 864
 865         setup_timer(&nf_ct_frag6_secret_timer, nf_ct_frag6_secret_rebuild, 0);
 866         nf_ct_frag6_secret_timer.expires = jiffies
 867                                            + nf_ct_frag6_secret_interval;
 868         add_timer(&nf_ct_frag6_secret_timer);
 869
 870         return 0;
 871 }
 872
 873 void nf_ct_frag6_cleanup(void)
 874 {
 875         del_timer(&nf_ct_frag6_secret_timer);
 876         nf_ct_frag6_low_thresh = 0;
 877         nf_ct_frag6_evictor();
 878 }