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 1.59 2002/01/12 07:54:56 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/compiler.h> 26 #include <linux/module.h> 27 #include <linux/types.h> 28 #include <linux/mm.h> 29 #include <linux/jiffies.h> 30 #include <linux/skbuff.h> 31 #include <linux/list.h> 32 #include <linux/ip.h> 33 #include <linux/icmp.h> 34 #include <linux/netdevice.h> 35 #include <linux/jhash.h> 36 #include <linux/random.h> 37 #include <net/sock.h> 38 #include <net/ip.h> 39 #include <net/icmp.h> 40 #include <net/checksum.h> 41 #include <net/inetpeer.h> 42 #include <net/inet_frag.h> 43 #include <linux/tcp.h> 44 #include <linux/udp.h> 45 #include <linux/inet.h> 46 #include <linux/netfilter_ipv4.h> 47 48 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 49 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c 50 * as well. Or notify me, at least. --ANK 51 */ 52 53 /* Fragment cache limits. We will commit 256K at one time. Should we 54 * cross that limit we will prune down to 192K. This should cope with 55 * even the most extreme cases without allowing an attacker to measurably 56 * harm machine performance. 57 */ 58 int sysctl_ipfrag_high_thresh __read_mostly = 256*1024; 59 int sysctl_ipfrag_low_thresh __read_mostly = 192*1024; 60 61 int sysctl_ipfrag_max_dist __read_mostly = 64; 62 63 /* Important NOTE! Fragment queue must be destroyed before MSL expires. 64 * RFC791 is wrong proposing to prolongate timer each fragment arrival by TTL. 65 */ 66 int sysctl_ipfrag_time __read_mostly = IP_FRAG_TIME; 67 68 struct ipfrag_skb_cb 69 { 70 struct inet_skb_parm h; 71 int offset; 72 }; 73 74 #define FRAG_CB(skb) ((struct ipfrag_skb_cb*)((skb)->cb)) 75 76 /* Describe an entry in the "incomplete datagrams" queue. */ 77 struct ipq { 78 struct inet_frag_queue q; 79 80 u32 user; 81 __be32 saddr; 82 __be32 daddr; 83 __be16 id; 84 u8 protocol; 85 int iif; 86 unsigned int rid; 87 struct inet_peer *peer; 88 }; 89 90 /* Hash table. */ 91 92 #define IPQ_HASHSZ 64 93 94 /* Per-bucket lock is easy to add now. */ 95 static struct hlist_head ipq_hash[IPQ_HASHSZ]; 96 static DEFINE_RWLOCK(ipfrag_lock); 97 static u32 ipfrag_hash_rnd; 98 static LIST_HEAD(ipq_lru_list); 99 int ip_frag_nqueues = 0; 100 101 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 102 struct net_device *dev); 103 104 static __inline__ void __ipq_unlink(struct ipq *qp) 105 { 106 hlist_del(&qp->q.list); 107 list_del(&qp->q.lru_list); 108 ip_frag_nqueues--; 109 } 110 111 static __inline__ void ipq_unlink(struct ipq *ipq) 112 { 113 write_lock(&ipfrag_lock); 114 __ipq_unlink(ipq); 115 write_unlock(&ipfrag_lock); 116 } 117 118 static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 119 { 120 return jhash_3words((__force u32)id << 16 | prot, 121 (__force u32)saddr, (__force u32)daddr, 122 ipfrag_hash_rnd) & (IPQ_HASHSZ - 1); 123 } 124 125 static struct timer_list ipfrag_secret_timer; 126 int sysctl_ipfrag_secret_interval __read_mostly = 10 * 60 * HZ; 127 128 static void ipfrag_secret_rebuild(unsigned long dummy) 129 { 130 unsigned long now = jiffies; 131 int i; 132 133 write_lock(&ipfrag_lock); 134 get_random_bytes(&ipfrag_hash_rnd, sizeof(u32)); 135 for (i = 0; i < IPQ_HASHSZ; i++) { 136 struct ipq *q; 137 struct hlist_node *p, *n; 138 139 hlist_for_each_entry_safe(q, p, n, &ipq_hash[i], q.list) { 140 unsigned int hval = ipqhashfn(q->id, q->saddr, 141 q->daddr, q->protocol); 142 143 if (hval != i) { 144 hlist_del(&q->q.list); 145 146 /* Relink to new hash chain. */ 147 hlist_add_head(&q->q.list, &ipq_hash[hval]); 148 } 149 } 150 } 151 write_unlock(&ipfrag_lock); 152 153 mod_timer(&ipfrag_secret_timer, now + sysctl_ipfrag_secret_interval); 154 } 155 156 atomic_t ip_frag_mem = ATOMIC_INIT(0); /* Memory used for fragments */ 157 158 /* Memory Tracking Functions. */ 159 static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work) 160 { 161 if (work) 162 *work -= skb->truesize; 163 atomic_sub(skb->truesize, &ip_frag_mem); 164 kfree_skb(skb); 165 } 166 167 static __inline__ void frag_free_queue(struct ipq *qp, int *work) 168 { 169 if (work) 170 *work -= sizeof(struct ipq); 171 atomic_sub(sizeof(struct ipq), &ip_frag_mem); 172 kfree(qp); 173 } 174 175 static __inline__ struct ipq *frag_alloc_queue(void) 176 { 177 struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC); 178 179 if (!qp) 180 return NULL; 181 atomic_add(sizeof(struct ipq), &ip_frag_mem); 182 return qp; 183 } 184 185 186 /* Destruction primitives. */ 187 188 /* Complete destruction of ipq. */ 189 static void ip_frag_destroy(struct ipq *qp, int *work) 190 { 191 struct sk_buff *fp; 192 193 BUG_TRAP(qp->q.last_in&COMPLETE); 194 BUG_TRAP(del_timer(&qp->q.timer) == 0); 195 196 if (qp->peer) 197 inet_putpeer(qp->peer); 198 199 /* Release all fragment data. */ 200 fp = qp->q.fragments; 201 while (fp) { 202 struct sk_buff *xp = fp->next; 203 204 frag_kfree_skb(fp, work); 205 fp = xp; 206 } 207 208 /* Finally, release the queue descriptor itself. */ 209 frag_free_queue(qp, work); 210 } 211 212 static __inline__ void ipq_put(struct ipq *ipq, int *work) 213 { 214 if (atomic_dec_and_test(&ipq->q.refcnt)) 215 ip_frag_destroy(ipq, work); 216 } 217 218 /* Kill ipq entry. It is not destroyed immediately, 219 * because caller (and someone more) holds reference count. 220 */ 221 static void ipq_kill(struct ipq *ipq) 222 { 223 if (del_timer(&ipq->q.timer)) 224 atomic_dec(&ipq->q.refcnt); 225 226 if (!(ipq->q.last_in & COMPLETE)) { 227 ipq_unlink(ipq); 228 atomic_dec(&ipq->q.refcnt); 229 ipq->q.last_in |= COMPLETE; 230 } 231 } 232 233 /* Memory limiting on fragments. Evictor trashes the oldest 234 * fragment queue until we are back under the threshold. 235 */ 236 static void ip_evictor(void) 237 { 238 struct ipq *qp; 239 struct list_head *tmp; 240 int work; 241 242 work = atomic_read(&ip_frag_mem) - sysctl_ipfrag_low_thresh; 243 if (work <= 0) 244 return; 245 246 while (work > 0) { 247 read_lock(&ipfrag_lock); 248 if (list_empty(&ipq_lru_list)) { 249 read_unlock(&ipfrag_lock); 250 return; 251 } 252 tmp = ipq_lru_list.next; 253 qp = list_entry(tmp, struct ipq, q.lru_list); 254 atomic_inc(&qp->q.refcnt); 255 read_unlock(&ipfrag_lock); 256 257 spin_lock(&qp->q.lock); 258 if (!(qp->q.last_in&COMPLETE)) 259 ipq_kill(qp); 260 spin_unlock(&qp->q.lock); 261 262 ipq_put(qp, &work); 263 IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 264 } 265 } 266 267 /* 268 * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 269 */ 270 static void ip_expire(unsigned long arg) 271 { 272 struct ipq *qp = (struct ipq *) arg; 273 274 spin_lock(&qp->q.lock); 275 276 if (qp->q.last_in & COMPLETE) 277 goto out; 278 279 ipq_kill(qp); 280 281 IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); 282 IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 283 284 if ((qp->q.last_in&FIRST_IN) && qp->q.fragments != NULL) { 285 struct sk_buff *head = qp->q.fragments; 286 /* Send an ICMP "Fragment Reassembly Timeout" message. */ 287 if ((head->dev = dev_get_by_index(&init_net, qp->iif)) != NULL) { 288 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); 289 dev_put(head->dev); 290 } 291 } 292 out: 293 spin_unlock(&qp->q.lock); 294 ipq_put(qp, NULL); 295 } 296 297 /* Creation primitives. */ 298 299 static struct ipq *ip_frag_intern(struct ipq *qp_in) 300 { 301 struct ipq *qp; 302 #ifdef CONFIG_SMP 303 struct hlist_node *n; 304 #endif 305 unsigned int hash; 306 307 write_lock(&ipfrag_lock); 308 hash = ipqhashfn(qp_in->id, qp_in->saddr, qp_in->daddr, 309 qp_in->protocol); 310 #ifdef CONFIG_SMP 311 /* With SMP race we have to recheck hash table, because 312 * such entry could be created on other cpu, while we 313 * promoted read lock to write lock. 314 */ 315 hlist_for_each_entry(qp, n, &ipq_hash[hash], q.list) { 316 if (qp->id == qp_in->id && 317 qp->saddr == qp_in->saddr && 318 qp->daddr == qp_in->daddr && 319 qp->protocol == qp_in->protocol && 320 qp->user == qp_in->user) { 321 atomic_inc(&qp->q.refcnt); 322 write_unlock(&ipfrag_lock); 323 qp_in->q.last_in |= COMPLETE; 324 ipq_put(qp_in, NULL); 325 return qp; 326 } 327 } 328 #endif 329 qp = qp_in; 330 331 if (!mod_timer(&qp->q.timer, jiffies + sysctl_ipfrag_time)) 332 atomic_inc(&qp->q.refcnt); 333 334 atomic_inc(&qp->q.refcnt); 335 hlist_add_head(&qp->q.list, &ipq_hash[hash]); 336 INIT_LIST_HEAD(&qp->q.lru_list); 337 list_add_tail(&qp->q.lru_list, &ipq_lru_list); 338 ip_frag_nqueues++; 339 write_unlock(&ipfrag_lock); 340 return qp; 341 } 342 343 /* Add an entry to the 'ipq' queue for a newly received IP datagram. */ 344 static struct ipq *ip_frag_create(struct iphdr *iph, u32 user) 345 { 346 struct ipq *qp; 347 348 if ((qp = frag_alloc_queue()) == NULL) 349 goto out_nomem; 350 351 qp->protocol = iph->protocol; 352 qp->q.last_in = 0; 353 qp->id = iph->id; 354 qp->saddr = iph->saddr; 355 qp->daddr = iph->daddr; 356 qp->user = user; 357 qp->q.len = 0; 358 qp->q.meat = 0; 359 qp->q.fragments = NULL; 360 qp->iif = 0; 361 qp->peer = sysctl_ipfrag_max_dist ? inet_getpeer(iph->saddr, 1) : NULL; 362 363 /* Initialize a timer for this entry. */ 364 init_timer(&qp->q.timer); 365 qp->q.timer.data = (unsigned long) qp; /* pointer to queue */ 366 qp->q.timer.function = ip_expire; /* expire function */ 367 spin_lock_init(&qp->q.lock); 368 atomic_set(&qp->q.refcnt, 1); 369 370 return ip_frag_intern(qp); 371 372 out_nomem: 373 LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); 374 return NULL; 375 } 376 377 /* Find the correct entry in the "incomplete datagrams" queue for 378 * this IP datagram, and create new one, if nothing is found. 379 */ 380 static inline struct ipq *ip_find(struct iphdr *iph, u32 user) 381 { 382 __be16 id = iph->id; 383 __be32 saddr = iph->saddr; 384 __be32 daddr = iph->daddr; 385 __u8 protocol = iph->protocol; 386 unsigned int hash; 387 struct ipq *qp; 388 struct hlist_node *n; 389 390 read_lock(&ipfrag_lock); 391 hash = ipqhashfn(id, saddr, daddr, protocol); 392 hlist_for_each_entry(qp, n, &ipq_hash[hash], q.list) { 393 if (qp->id == id && 394 qp->saddr == saddr && 395 qp->daddr == daddr && 396 qp->protocol == protocol && 397 qp->user == user) { 398 atomic_inc(&qp->q.refcnt); 399 read_unlock(&ipfrag_lock); 400 return qp; 401 } 402 } 403 read_unlock(&ipfrag_lock); 404 405 return ip_frag_create(iph, user); 406 } 407 408 /* Is the fragment too far ahead to be part of ipq? */ 409 static inline int ip_frag_too_far(struct ipq *qp) 410 { 411 struct inet_peer *peer = qp->peer; 412 unsigned int max = sysctl_ipfrag_max_dist; 413 unsigned int start, end; 414 415 int rc; 416 417 if (!peer || !max) 418 return 0; 419 420 start = qp->rid; 421 end = atomic_inc_return(&peer->rid); 422 qp->rid = end; 423 424 rc = qp->q.fragments && (end - start) > max; 425 426 if (rc) { 427 IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 428 } 429 430 return rc; 431 } 432 433 static int ip_frag_reinit(struct ipq *qp) 434 { 435 struct sk_buff *fp; 436 437 if (!mod_timer(&qp->q.timer, jiffies + sysctl_ipfrag_time)) { 438 atomic_inc(&qp->q.refcnt); 439 return -ETIMEDOUT; 440 } 441 442 fp = qp->q.fragments; 443 do { 444 struct sk_buff *xp = fp->next; 445 frag_kfree_skb(fp, NULL); 446 fp = xp; 447 } while (fp); 448 449 qp->q.last_in = 0; 450 qp->q.len = 0; 451 qp->q.meat = 0; 452 qp->q.fragments = NULL; 453 qp->iif = 0; 454 455 return 0; 456 } 457 458 /* Add new segment to existing queue. */ 459 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 460 { 461 struct sk_buff *prev, *next; 462 struct net_device *dev; 463 int flags, offset; 464 int ihl, end; 465 int err = -ENOENT; 466 467 if (qp->q.last_in & COMPLETE) 468 goto err; 469 470 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 471 unlikely(ip_frag_too_far(qp)) && 472 unlikely(err = ip_frag_reinit(qp))) { 473 ipq_kill(qp); 474 goto err; 475 } 476 477 offset = ntohs(ip_hdr(skb)->frag_off); 478 flags = offset & ~IP_OFFSET; 479 offset &= IP_OFFSET; 480 offset <<= 3; /* offset is in 8-byte chunks */ 481 ihl = ip_hdrlen(skb); 482 483 /* Determine the position of this fragment. */ 484 end = offset + skb->len - ihl; 485 err = -EINVAL; 486 487 /* Is this the final fragment? */ 488 if ((flags & IP_MF) == 0) { 489 /* If we already have some bits beyond end 490 * or have different end, the segment is corrrupted. 491 */ 492 if (end < qp->q.len || 493 ((qp->q.last_in & LAST_IN) && end != qp->q.len)) 494 goto err; 495 qp->q.last_in |= LAST_IN; 496 qp->q.len = end; 497 } else { 498 if (end&7) { 499 end &= ~7; 500 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 501 skb->ip_summed = CHECKSUM_NONE; 502 } 503 if (end > qp->q.len) { 504 /* Some bits beyond end -> corruption. */ 505 if (qp->q.last_in & LAST_IN) 506 goto err; 507 qp->q.len = end; 508 } 509 } 510 if (end == offset) 511 goto err; 512 513 err = -ENOMEM; 514 if (pskb_pull(skb, ihl) == NULL) 515 goto err; 516 517 err = pskb_trim_rcsum(skb, end - offset); 518 if (err) 519 goto err; 520 521 /* Find out which fragments are in front and at the back of us 522 * in the chain of fragments so far. We must know where to put 523 * this fragment, right? 524 */ 525 prev = NULL; 526 for (next = qp->q.fragments; next != NULL; next = next->next) { 527 if (FRAG_CB(next)->offset >= offset) 528 break; /* bingo! */ 529 prev = next; 530 } 531 532 /* We found where to put this one. Check for overlap with 533 * preceding fragment, and, if needed, align things so that 534 * any overlaps are eliminated. 535 */ 536 if (prev) { 537 int i = (FRAG_CB(prev)->offset + prev->len) - offset; 538 539 if (i > 0) { 540 offset += i; 541 err = -EINVAL; 542 if (end <= offset) 543 goto err; 544 err = -ENOMEM; 545 if (!pskb_pull(skb, i)) 546 goto err; 547 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 548 skb->ip_summed = CHECKSUM_NONE; 549 } 550 } 551 552 err = -ENOMEM; 553 554 while (next && FRAG_CB(next)->offset < end) { 555 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 556 557 if (i < next->len) { 558 /* Eat head of the next overlapped fragment 559 * and leave the loop. The next ones cannot overlap. 560 */ 561 if (!pskb_pull(next, i)) 562 goto err; 563 FRAG_CB(next)->offset += i; 564 qp->q.meat -= i; 565 if (next->ip_summed != CHECKSUM_UNNECESSARY) 566 next->ip_summed = CHECKSUM_NONE; 567 break; 568 } else { 569 struct sk_buff *free_it = next; 570 571 /* Old fragment is completely overridden with 572 * new one drop it. 573 */ 574 next = next->next; 575 576 if (prev) 577 prev->next = next; 578 else 579 qp->q.fragments = next; 580 581 qp->q.meat -= free_it->len; 582 frag_kfree_skb(free_it, NULL); 583 } 584 } 585 586 FRAG_CB(skb)->offset = offset; 587 588 /* Insert this fragment in the chain of fragments. */ 589 skb->next = next; 590 if (prev) 591 prev->next = skb; 592 else 593 qp->q.fragments = skb; 594 595 dev = skb->dev; 596 if (dev) { 597 qp->iif = dev->ifindex; 598 skb->dev = NULL; 599 } 600 qp->q.stamp = skb->tstamp; 601 qp->q.meat += skb->len; 602 atomic_add(skb->truesize, &ip_frag_mem); 603 if (offset == 0) 604 qp->q.last_in |= FIRST_IN; 605 606 if (qp->q.last_in == (FIRST_IN | LAST_IN) && qp->q.meat == qp->q.len) 607 return ip_frag_reasm(qp, prev, dev); 608 609 write_lock(&ipfrag_lock); 610 list_move_tail(&qp->q.lru_list, &ipq_lru_list); 611 write_unlock(&ipfrag_lock); 612 return -EINPROGRESS; 613 614 err: 615 kfree_skb(skb); 616 return err; 617 } 618 619 620 /* Build a new IP datagram from all its fragments. */ 621 622 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 623 struct net_device *dev) 624 { 625 struct iphdr *iph; 626 struct sk_buff *fp, *head = qp->q.fragments; 627 int len; 628 int ihlen; 629 int err; 630 631 ipq_kill(qp); 632 633 /* Make the one we just received the head. */ 634 if (prev) { 635 head = prev->next; 636 fp = skb_clone(head, GFP_ATOMIC); 637 638 if (!fp) 639 goto out_nomem; 640 641 fp->next = head->next; 642 prev->next = fp; 643 644 skb_morph(head, qp->q.fragments); 645 head->next = qp->q.fragments->next; 646 647 kfree_skb(qp->q.fragments); 648 qp->q.fragments = head; 649 } 650 651 BUG_TRAP(head != NULL); 652 BUG_TRAP(FRAG_CB(head)->offset == 0); 653 654 /* Allocate a new buffer for the datagram. */ 655 ihlen = ip_hdrlen(head); 656 len = ihlen + qp->q.len; 657 658 err = -E2BIG; 659 if (len > 65535) 660 goto out_oversize; 661 662 /* Head of list must not be cloned. */ 663 err = -ENOMEM; 664 if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) 665 goto out_nomem; 666 667 /* If the first fragment is fragmented itself, we split 668 * it to two chunks: the first with data and paged part 669 * and the second, holding only fragments. */ 670 if (skb_shinfo(head)->frag_list) { 671 struct sk_buff *clone; 672 int i, plen = 0; 673 674 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) 675 goto out_nomem; 676 clone->next = head->next; 677 head->next = clone; 678 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 679 skb_shinfo(head)->frag_list = NULL; 680 for (i=0; i<skb_shinfo(head)->nr_frags; i++) 681 plen += skb_shinfo(head)->frags[i].size; 682 clone->len = clone->data_len = head->data_len - plen; 683 head->data_len -= clone->len; 684 head->len -= clone->len; 685 clone->csum = 0; 686 clone->ip_summed = head->ip_summed; 687 atomic_add(clone->truesize, &ip_frag_mem); 688 } 689 690 skb_shinfo(head)->frag_list = head->next; 691 skb_push(head, head->data - skb_network_header(head)); 692 atomic_sub(head->truesize, &ip_frag_mem); 693 694 for (fp=head->next; fp; fp = fp->next) { 695 head->data_len += fp->len; 696 head->len += fp->len; 697 if (head->ip_summed != fp->ip_summed) 698 head->ip_summed = CHECKSUM_NONE; 699 else if (head->ip_summed == CHECKSUM_COMPLETE) 700 head->csum = csum_add(head->csum, fp->csum); 701 head->truesize += fp->truesize; 702 atomic_sub(fp->truesize, &ip_frag_mem); 703 } 704 705 head->next = NULL; 706 head->dev = dev; 707 head->tstamp = qp->q.stamp; 708 709 iph = ip_hdr(head); 710 iph->frag_off = 0; 711 iph->tot_len = htons(len); 712 IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); 713 qp->q.fragments = NULL; 714 return 0; 715 716 out_nomem: 717 LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " 718 "queue %p\n", qp); 719 goto out_fail; 720 out_oversize: 721 if (net_ratelimit()) 722 printk(KERN_INFO 723 "Oversized IP packet from %d.%d.%d.%d.\n", 724 NIPQUAD(qp->saddr)); 725 out_fail: 726 IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 727 return err; 728 } 729 730 /* Process an incoming IP datagram fragment. */ 731 int ip_defrag(struct sk_buff *skb, u32 user) 732 { 733 struct ipq *qp; 734 735 IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); 736 737 /* Start by cleaning up the memory. */ 738 if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh) 739 ip_evictor(); 740 741 /* Lookup (or create) queue header */ 742 if ((qp = ip_find(ip_hdr(skb), user)) != NULL) { 743 int ret; 744 745 spin_lock(&qp->q.lock); 746 747 ret = ip_frag_queue(qp, skb); 748 749 spin_unlock(&qp->q.lock); 750 ipq_put(qp, NULL); 751 return ret; 752 } 753 754 IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 755 kfree_skb(skb); 756 return -ENOMEM; 757 } 758 759 void __init ipfrag_init(void) 760 { 761 ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ 762 (jiffies ^ (jiffies >> 6))); 763 764 init_timer(&ipfrag_secret_timer); 765 ipfrag_secret_timer.function = ipfrag_secret_rebuild; 766 ipfrag_secret_timer.expires = jiffies + sysctl_ipfrag_secret_interval; 767 add_timer(&ipfrag_secret_timer); 768 } 769 770 EXPORT_SYMBOL(ip_defrag); 771