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 #define pr_fmt(fmt) "IPv4: " fmt 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 <linux/slab.h> 38 #include <net/route.h> 39 #include <net/dst.h> 40 #include <net/sock.h> 41 #include <net/ip.h> 42 #include <net/icmp.h> 43 #include <net/checksum.h> 44 #include <net/inetpeer.h> 45 #include <net/inet_frag.h> 46 #include <linux/tcp.h> 47 #include <linux/udp.h> 48 #include <linux/inet.h> 49 #include <linux/netfilter_ipv4.h> 50 #include <net/inet_ecn.h> 51 #include <net/l3mdev.h> 52 53 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 54 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c 55 * as well. Or notify me, at least. --ANK 56 */ 57 static const char ip_frag_cache_name[] = "ip4-frags"; 58 59 struct ipfrag_skb_cb 60 { 61 struct inet_skb_parm h; 62 int offset; 63 }; 64 65 #define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) 66 67 /* Describe an entry in the "incomplete datagrams" queue. */ 68 struct ipq { 69 struct inet_frag_queue q; 70 71 u32 user; 72 __be32 saddr; 73 __be32 daddr; 74 __be16 id; 75 u8 protocol; 76 u8 ecn; /* RFC3168 support */ 77 u16 max_df_size; /* largest frag with DF set seen */ 78 int iif; 79 int vif; /* L3 master device index */ 80 unsigned int rid; 81 struct inet_peer *peer; 82 }; 83 84 static u8 ip4_frag_ecn(u8 tos) 85 { 86 return 1 << (tos & INET_ECN_MASK); 87 } 88 89 static struct inet_frags ip4_frags; 90 91 int ip_frag_mem(struct net *net) 92 { 93 return sum_frag_mem_limit(&net->ipv4.frags); 94 } 95 96 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 97 struct net_device *dev); 98 99 struct ip4_create_arg { 100 struct iphdr *iph; 101 u32 user; 102 int vif; 103 }; 104 105 static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 106 { 107 net_get_random_once(&ip4_frags.rnd, sizeof(ip4_frags.rnd)); 108 return jhash_3words((__force u32)id << 16 | prot, 109 (__force u32)saddr, (__force u32)daddr, 110 ip4_frags.rnd); 111 } 112 113 static unsigned int ip4_hashfn(const struct inet_frag_queue *q) 114 { 115 const struct ipq *ipq; 116 117 ipq = container_of(q, struct ipq, q); 118 return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); 119 } 120 121 static bool ip4_frag_match(const struct inet_frag_queue *q, const void *a) 122 { 123 const struct ipq *qp; 124 const struct ip4_create_arg *arg = a; 125 126 qp = container_of(q, struct ipq, q); 127 return qp->id == arg->iph->id && 128 qp->saddr == arg->iph->saddr && 129 qp->daddr == arg->iph->daddr && 130 qp->protocol == arg->iph->protocol && 131 qp->user == arg->user && 132 qp->vif == arg->vif; 133 } 134 135 static void ip4_frag_init(struct inet_frag_queue *q, const void *a) 136 { 137 struct ipq *qp = container_of(q, struct ipq, q); 138 struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4, 139 frags); 140 struct net *net = container_of(ipv4, struct net, ipv4); 141 142 const struct ip4_create_arg *arg = a; 143 144 qp->protocol = arg->iph->protocol; 145 qp->id = arg->iph->id; 146 qp->ecn = ip4_frag_ecn(arg->iph->tos); 147 qp->saddr = arg->iph->saddr; 148 qp->daddr = arg->iph->daddr; 149 qp->vif = arg->vif; 150 qp->user = arg->user; 151 qp->peer = q->net->max_dist ? 152 inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, arg->vif, 1) : 153 NULL; 154 } 155 156 static void ip4_frag_free(struct inet_frag_queue *q) 157 { 158 struct ipq *qp; 159 160 qp = container_of(q, struct ipq, q); 161 if (qp->peer) 162 inet_putpeer(qp->peer); 163 } 164 165 166 /* Destruction primitives. */ 167 168 static void ipq_put(struct ipq *ipq) 169 { 170 inet_frag_put(&ipq->q, &ip4_frags); 171 } 172 173 /* Kill ipq entry. It is not destroyed immediately, 174 * because caller (and someone more) holds reference count. 175 */ 176 static void ipq_kill(struct ipq *ipq) 177 { 178 inet_frag_kill(&ipq->q, &ip4_frags); 179 } 180 181 static bool frag_expire_skip_icmp(u32 user) 182 { 183 return user == IP_DEFRAG_AF_PACKET || 184 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN, 185 __IP_DEFRAG_CONNTRACK_IN_END) || 186 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN, 187 __IP_DEFRAG_CONNTRACK_BRIDGE_IN); 188 } 189 190 /* 191 * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 192 */ 193 static void ip_expire(unsigned long arg) 194 { 195 struct ipq *qp; 196 struct net *net; 197 198 qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); 199 net = container_of(qp->q.net, struct net, ipv4.frags); 200 201 rcu_read_lock(); 202 spin_lock(&qp->q.lock); 203 204 if (qp->q.flags & INET_FRAG_COMPLETE) 205 goto out; 206 207 ipq_kill(qp); 208 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 209 210 if (!inet_frag_evicting(&qp->q)) { 211 struct sk_buff *clone, *head = qp->q.fragments; 212 const struct iphdr *iph; 213 int err; 214 215 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT); 216 217 if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !qp->q.fragments) 218 goto out; 219 220 head->dev = dev_get_by_index_rcu(net, qp->iif); 221 if (!head->dev) 222 goto out; 223 224 225 /* skb has no dst, perform route lookup again */ 226 iph = ip_hdr(head); 227 err = ip_route_input_noref(head, iph->daddr, iph->saddr, 228 iph->tos, head->dev); 229 if (err) 230 goto out; 231 232 /* Only an end host needs to send an ICMP 233 * "Fragment Reassembly Timeout" message, per RFC792. 234 */ 235 if (frag_expire_skip_icmp(qp->user) && 236 (skb_rtable(head)->rt_type != RTN_LOCAL)) 237 goto out; 238 239 clone = skb_clone(head, GFP_ATOMIC); 240 241 /* Send an ICMP "Fragment Reassembly Timeout" message. */ 242 if (clone) { 243 spin_unlock(&qp->q.lock); 244 icmp_send(clone, ICMP_TIME_EXCEEDED, 245 ICMP_EXC_FRAGTIME, 0); 246 consume_skb(clone); 247 goto out_rcu_unlock; 248 } 249 } 250 out: 251 spin_unlock(&qp->q.lock); 252 out_rcu_unlock: 253 rcu_read_unlock(); 254 ipq_put(qp); 255 } 256 257 /* Find the correct entry in the "incomplete datagrams" queue for 258 * this IP datagram, and create new one, if nothing is found. 259 */ 260 static struct ipq *ip_find(struct net *net, struct iphdr *iph, 261 u32 user, int vif) 262 { 263 struct inet_frag_queue *q; 264 struct ip4_create_arg arg; 265 unsigned int hash; 266 267 arg.iph = iph; 268 arg.user = user; 269 arg.vif = vif; 270 271 hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); 272 273 q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); 274 if (IS_ERR_OR_NULL(q)) { 275 inet_frag_maybe_warn_overflow(q, pr_fmt()); 276 return NULL; 277 } 278 return container_of(q, struct ipq, q); 279 } 280 281 /* Is the fragment too far ahead to be part of ipq? */ 282 static int ip_frag_too_far(struct ipq *qp) 283 { 284 struct inet_peer *peer = qp->peer; 285 unsigned int max = qp->q.net->max_dist; 286 unsigned int start, end; 287 288 int rc; 289 290 if (!peer || !max) 291 return 0; 292 293 start = qp->rid; 294 end = atomic_inc_return(&peer->rid); 295 qp->rid = end; 296 297 rc = qp->q.fragments && (end - start) > max; 298 299 if (rc) { 300 struct net *net; 301 302 net = container_of(qp->q.net, struct net, ipv4.frags); 303 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 304 } 305 306 return rc; 307 } 308 309 static int ip_frag_reinit(struct ipq *qp) 310 { 311 struct sk_buff *fp; 312 unsigned int sum_truesize = 0; 313 314 if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { 315 atomic_inc(&qp->q.refcnt); 316 return -ETIMEDOUT; 317 } 318 319 fp = qp->q.fragments; 320 do { 321 struct sk_buff *xp = fp->next; 322 323 sum_truesize += fp->truesize; 324 kfree_skb(fp); 325 fp = xp; 326 } while (fp); 327 sub_frag_mem_limit(qp->q.net, sum_truesize); 328 329 qp->q.flags = 0; 330 qp->q.len = 0; 331 qp->q.meat = 0; 332 qp->q.fragments = NULL; 333 qp->q.fragments_tail = NULL; 334 qp->iif = 0; 335 qp->ecn = 0; 336 337 return 0; 338 } 339 340 /* Add new segment to existing queue. */ 341 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 342 { 343 struct sk_buff *prev, *next; 344 struct net_device *dev; 345 unsigned int fragsize; 346 int flags, offset; 347 int ihl, end; 348 int err = -ENOENT; 349 u8 ecn; 350 351 if (qp->q.flags & INET_FRAG_COMPLETE) 352 goto err; 353 354 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 355 unlikely(ip_frag_too_far(qp)) && 356 unlikely(err = ip_frag_reinit(qp))) { 357 ipq_kill(qp); 358 goto err; 359 } 360 361 ecn = ip4_frag_ecn(ip_hdr(skb)->tos); 362 offset = ntohs(ip_hdr(skb)->frag_off); 363 flags = offset & ~IP_OFFSET; 364 offset &= IP_OFFSET; 365 offset <<= 3; /* offset is in 8-byte chunks */ 366 ihl = ip_hdrlen(skb); 367 368 /* Determine the position of this fragment. */ 369 end = offset + skb->len - skb_network_offset(skb) - ihl; 370 err = -EINVAL; 371 372 /* Is this the final fragment? */ 373 if ((flags & IP_MF) == 0) { 374 /* If we already have some bits beyond end 375 * or have different end, the segment is corrupted. 376 */ 377 if (end < qp->q.len || 378 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len)) 379 goto err; 380 qp->q.flags |= INET_FRAG_LAST_IN; 381 qp->q.len = end; 382 } else { 383 if (end&7) { 384 end &= ~7; 385 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 386 skb->ip_summed = CHECKSUM_NONE; 387 } 388 if (end > qp->q.len) { 389 /* Some bits beyond end -> corruption. */ 390 if (qp->q.flags & INET_FRAG_LAST_IN) 391 goto err; 392 qp->q.len = end; 393 } 394 } 395 if (end == offset) 396 goto err; 397 398 err = -ENOMEM; 399 if (!pskb_pull(skb, skb_network_offset(skb) + ihl)) 400 goto err; 401 402 err = pskb_trim_rcsum(skb, end - offset); 403 if (err) 404 goto err; 405 406 /* Find out which fragments are in front and at the back of us 407 * in the chain of fragments so far. We must know where to put 408 * this fragment, right? 409 */ 410 prev = qp->q.fragments_tail; 411 if (!prev || FRAG_CB(prev)->offset < offset) { 412 next = NULL; 413 goto found; 414 } 415 prev = NULL; 416 for (next = qp->q.fragments; next != NULL; next = next->next) { 417 if (FRAG_CB(next)->offset >= offset) 418 break; /* bingo! */ 419 prev = next; 420 } 421 422 found: 423 /* We found where to put this one. Check for overlap with 424 * preceding fragment, and, if needed, align things so that 425 * any overlaps are eliminated. 426 */ 427 if (prev) { 428 int i = (FRAG_CB(prev)->offset + prev->len) - offset; 429 430 if (i > 0) { 431 offset += i; 432 err = -EINVAL; 433 if (end <= offset) 434 goto err; 435 err = -ENOMEM; 436 if (!pskb_pull(skb, i)) 437 goto err; 438 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 439 skb->ip_summed = CHECKSUM_NONE; 440 } 441 } 442 443 err = -ENOMEM; 444 445 while (next && FRAG_CB(next)->offset < end) { 446 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 447 448 if (i < next->len) { 449 /* Eat head of the next overlapped fragment 450 * and leave the loop. The next ones cannot overlap. 451 */ 452 if (!pskb_pull(next, i)) 453 goto err; 454 FRAG_CB(next)->offset += i; 455 qp->q.meat -= i; 456 if (next->ip_summed != CHECKSUM_UNNECESSARY) 457 next->ip_summed = CHECKSUM_NONE; 458 break; 459 } else { 460 struct sk_buff *free_it = next; 461 462 /* Old fragment is completely overridden with 463 * new one drop it. 464 */ 465 next = next->next; 466 467 if (prev) 468 prev->next = next; 469 else 470 qp->q.fragments = next; 471 472 qp->q.meat -= free_it->len; 473 sub_frag_mem_limit(qp->q.net, free_it->truesize); 474 kfree_skb(free_it); 475 } 476 } 477 478 FRAG_CB(skb)->offset = offset; 479 480 /* Insert this fragment in the chain of fragments. */ 481 skb->next = next; 482 if (!next) 483 qp->q.fragments_tail = skb; 484 if (prev) 485 prev->next = skb; 486 else 487 qp->q.fragments = skb; 488 489 dev = skb->dev; 490 if (dev) { 491 qp->iif = dev->ifindex; 492 skb->dev = NULL; 493 } 494 qp->q.stamp = skb->tstamp; 495 qp->q.meat += skb->len; 496 qp->ecn |= ecn; 497 add_frag_mem_limit(qp->q.net, skb->truesize); 498 if (offset == 0) 499 qp->q.flags |= INET_FRAG_FIRST_IN; 500 501 fragsize = skb->len + ihl; 502 503 if (fragsize > qp->q.max_size) 504 qp->q.max_size = fragsize; 505 506 if (ip_hdr(skb)->frag_off & htons(IP_DF) && 507 fragsize > qp->max_df_size) 508 qp->max_df_size = fragsize; 509 510 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && 511 qp->q.meat == qp->q.len) { 512 unsigned long orefdst = skb->_skb_refdst; 513 514 skb->_skb_refdst = 0UL; 515 err = ip_frag_reasm(qp, prev, dev); 516 skb->_skb_refdst = orefdst; 517 return err; 518 } 519 520 skb_dst_drop(skb); 521 return -EINPROGRESS; 522 523 err: 524 kfree_skb(skb); 525 return err; 526 } 527 528 529 /* Build a new IP datagram from all its fragments. */ 530 531 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 532 struct net_device *dev) 533 { 534 struct net *net = container_of(qp->q.net, struct net, ipv4.frags); 535 struct iphdr *iph; 536 struct sk_buff *fp, *head = qp->q.fragments; 537 int len; 538 int ihlen; 539 int err; 540 u8 ecn; 541 542 ipq_kill(qp); 543 544 ecn = ip_frag_ecn_table[qp->ecn]; 545 if (unlikely(ecn == 0xff)) { 546 err = -EINVAL; 547 goto out_fail; 548 } 549 /* Make the one we just received the head. */ 550 if (prev) { 551 head = prev->next; 552 fp = skb_clone(head, GFP_ATOMIC); 553 if (!fp) 554 goto out_nomem; 555 556 fp->next = head->next; 557 if (!fp->next) 558 qp->q.fragments_tail = fp; 559 prev->next = fp; 560 561 skb_morph(head, qp->q.fragments); 562 head->next = qp->q.fragments->next; 563 564 consume_skb(qp->q.fragments); 565 qp->q.fragments = head; 566 } 567 568 WARN_ON(!head); 569 WARN_ON(FRAG_CB(head)->offset != 0); 570 571 /* Allocate a new buffer for the datagram. */ 572 ihlen = ip_hdrlen(head); 573 len = ihlen + qp->q.len; 574 575 err = -E2BIG; 576 if (len > 65535) 577 goto out_oversize; 578 579 /* Head of list must not be cloned. */ 580 if (skb_unclone(head, GFP_ATOMIC)) 581 goto out_nomem; 582 583 /* If the first fragment is fragmented itself, we split 584 * it to two chunks: the first with data and paged part 585 * and the second, holding only fragments. */ 586 if (skb_has_frag_list(head)) { 587 struct sk_buff *clone; 588 int i, plen = 0; 589 590 clone = alloc_skb(0, GFP_ATOMIC); 591 if (!clone) 592 goto out_nomem; 593 clone->next = head->next; 594 head->next = clone; 595 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 596 skb_frag_list_init(head); 597 for (i = 0; i < skb_shinfo(head)->nr_frags; i++) 598 plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 599 clone->len = clone->data_len = head->data_len - plen; 600 head->data_len -= clone->len; 601 head->len -= clone->len; 602 clone->csum = 0; 603 clone->ip_summed = head->ip_summed; 604 add_frag_mem_limit(qp->q.net, clone->truesize); 605 } 606 607 skb_shinfo(head)->frag_list = head->next; 608 skb_push(head, head->data - skb_network_header(head)); 609 610 for (fp=head->next; fp; fp = fp->next) { 611 head->data_len += fp->len; 612 head->len += fp->len; 613 if (head->ip_summed != fp->ip_summed) 614 head->ip_summed = CHECKSUM_NONE; 615 else if (head->ip_summed == CHECKSUM_COMPLETE) 616 head->csum = csum_add(head->csum, fp->csum); 617 head->truesize += fp->truesize; 618 } 619 sub_frag_mem_limit(qp->q.net, head->truesize); 620 621 head->next = NULL; 622 head->dev = dev; 623 head->tstamp = qp->q.stamp; 624 IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); 625 626 iph = ip_hdr(head); 627 iph->tot_len = htons(len); 628 iph->tos |= ecn; 629 630 /* When we set IP_DF on a refragmented skb we must also force a 631 * call to ip_fragment to avoid forwarding a DF-skb of size s while 632 * original sender only sent fragments of size f (where f < s). 633 * 634 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest 635 * frag seen to avoid sending tiny DF-fragments in case skb was built 636 * from one very small df-fragment and one large non-df frag. 637 */ 638 if (qp->max_df_size == qp->q.max_size) { 639 IPCB(head)->flags |= IPSKB_FRAG_PMTU; 640 iph->frag_off = htons(IP_DF); 641 } else { 642 iph->frag_off = 0; 643 } 644 645 ip_send_check(iph); 646 647 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS); 648 qp->q.fragments = NULL; 649 qp->q.fragments_tail = NULL; 650 return 0; 651 652 out_nomem: 653 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp); 654 err = -ENOMEM; 655 goto out_fail; 656 out_oversize: 657 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); 658 out_fail: 659 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 660 return err; 661 } 662 663 /* Process an incoming IP datagram fragment. */ 664 int ip_defrag(struct net *net, struct sk_buff *skb, u32 user) 665 { 666 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev; 667 int vif = l3mdev_master_ifindex_rcu(dev); 668 struct ipq *qp; 669 670 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS); 671 skb_orphan(skb); 672 673 /* Lookup (or create) queue header */ 674 qp = ip_find(net, ip_hdr(skb), user, vif); 675 if (qp) { 676 int ret; 677 678 spin_lock(&qp->q.lock); 679 680 ret = ip_frag_queue(qp, skb); 681 682 spin_unlock(&qp->q.lock); 683 ipq_put(qp); 684 return ret; 685 } 686 687 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 688 kfree_skb(skb); 689 return -ENOMEM; 690 } 691 EXPORT_SYMBOL(ip_defrag); 692 693 struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user) 694 { 695 struct iphdr iph; 696 int netoff; 697 u32 len; 698 699 if (skb->protocol != htons(ETH_P_IP)) 700 return skb; 701 702 netoff = skb_network_offset(skb); 703 704 if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0) 705 return skb; 706 707 if (iph.ihl < 5 || iph.version != 4) 708 return skb; 709 710 len = ntohs(iph.tot_len); 711 if (skb->len < netoff + len || len < (iph.ihl * 4)) 712 return skb; 713 714 if (ip_is_fragment(&iph)) { 715 skb = skb_share_check(skb, GFP_ATOMIC); 716 if (skb) { 717 if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) 718 return skb; 719 if (pskb_trim_rcsum(skb, netoff + len)) 720 return skb; 721 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 722 if (ip_defrag(net, skb, user)) 723 return NULL; 724 skb_clear_hash(skb); 725 } 726 } 727 return skb; 728 } 729 EXPORT_SYMBOL(ip_check_defrag); 730 731 #ifdef CONFIG_SYSCTL 732 static int zero; 733 734 static struct ctl_table ip4_frags_ns_ctl_table[] = { 735 { 736 .procname = "ipfrag_high_thresh", 737 .data = &init_net.ipv4.frags.high_thresh, 738 .maxlen = sizeof(int), 739 .mode = 0644, 740 .proc_handler = proc_dointvec_minmax, 741 .extra1 = &init_net.ipv4.frags.low_thresh 742 }, 743 { 744 .procname = "ipfrag_low_thresh", 745 .data = &init_net.ipv4.frags.low_thresh, 746 .maxlen = sizeof(int), 747 .mode = 0644, 748 .proc_handler = proc_dointvec_minmax, 749 .extra1 = &zero, 750 .extra2 = &init_net.ipv4.frags.high_thresh 751 }, 752 { 753 .procname = "ipfrag_time", 754 .data = &init_net.ipv4.frags.timeout, 755 .maxlen = sizeof(int), 756 .mode = 0644, 757 .proc_handler = proc_dointvec_jiffies, 758 }, 759 { 760 .procname = "ipfrag_max_dist", 761 .data = &init_net.ipv4.frags.max_dist, 762 .maxlen = sizeof(int), 763 .mode = 0644, 764 .proc_handler = proc_dointvec_minmax, 765 .extra1 = &zero 766 }, 767 { } 768 }; 769 770 /* secret interval has been deprecated */ 771 static int ip4_frags_secret_interval_unused; 772 static struct ctl_table ip4_frags_ctl_table[] = { 773 { 774 .procname = "ipfrag_secret_interval", 775 .data = &ip4_frags_secret_interval_unused, 776 .maxlen = sizeof(int), 777 .mode = 0644, 778 .proc_handler = proc_dointvec_jiffies, 779 }, 780 { } 781 }; 782 783 static int __net_init ip4_frags_ns_ctl_register(struct net *net) 784 { 785 struct ctl_table *table; 786 struct ctl_table_header *hdr; 787 788 table = ip4_frags_ns_ctl_table; 789 if (!net_eq(net, &init_net)) { 790 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); 791 if (!table) 792 goto err_alloc; 793 794 table[0].data = &net->ipv4.frags.high_thresh; 795 table[0].extra1 = &net->ipv4.frags.low_thresh; 796 table[0].extra2 = &init_net.ipv4.frags.high_thresh; 797 table[1].data = &net->ipv4.frags.low_thresh; 798 table[1].extra2 = &net->ipv4.frags.high_thresh; 799 table[2].data = &net->ipv4.frags.timeout; 800 table[3].data = &net->ipv4.frags.max_dist; 801 } 802 803 hdr = register_net_sysctl(net, "net/ipv4", table); 804 if (!hdr) 805 goto err_reg; 806 807 net->ipv4.frags_hdr = hdr; 808 return 0; 809 810 err_reg: 811 if (!net_eq(net, &init_net)) 812 kfree(table); 813 err_alloc: 814 return -ENOMEM; 815 } 816 817 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) 818 { 819 struct ctl_table *table; 820 821 table = net->ipv4.frags_hdr->ctl_table_arg; 822 unregister_net_sysctl_table(net->ipv4.frags_hdr); 823 kfree(table); 824 } 825 826 static void __init ip4_frags_ctl_register(void) 827 { 828 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); 829 } 830 #else 831 static int ip4_frags_ns_ctl_register(struct net *net) 832 { 833 return 0; 834 } 835 836 static void ip4_frags_ns_ctl_unregister(struct net *net) 837 { 838 } 839 840 static void __init ip4_frags_ctl_register(void) 841 { 842 } 843 #endif 844 845 static int __net_init ipv4_frags_init_net(struct net *net) 846 { 847 int res; 848 849 /* Fragment cache limits. 850 * 851 * The fragment memory accounting code, (tries to) account for 852 * the real memory usage, by measuring both the size of frag 853 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue)) 854 * and the SKB's truesize. 855 * 856 * A 64K fragment consumes 129736 bytes (44*2944)+200 857 * (1500 truesize == 2944, sizeof(struct ipq) == 200) 858 * 859 * We will commit 4MB at one time. Should we cross that limit 860 * we will prune down to 3MB, making room for approx 8 big 64K 861 * fragments 8x128k. 862 */ 863 net->ipv4.frags.high_thresh = 4 * 1024 * 1024; 864 net->ipv4.frags.low_thresh = 3 * 1024 * 1024; 865 /* 866 * Important NOTE! Fragment queue must be destroyed before MSL expires. 867 * RFC791 is wrong proposing to prolongate timer each fragment arrival 868 * by TTL. 869 */ 870 net->ipv4.frags.timeout = IP_FRAG_TIME; 871 872 net->ipv4.frags.max_dist = 64; 873 874 res = inet_frags_init_net(&net->ipv4.frags); 875 if (res) 876 return res; 877 res = ip4_frags_ns_ctl_register(net); 878 if (res) 879 inet_frags_uninit_net(&net->ipv4.frags); 880 return res; 881 } 882 883 static void __net_exit ipv4_frags_exit_net(struct net *net) 884 { 885 ip4_frags_ns_ctl_unregister(net); 886 inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); 887 } 888 889 static struct pernet_operations ip4_frags_ops = { 890 .init = ipv4_frags_init_net, 891 .exit = ipv4_frags_exit_net, 892 }; 893 894 void __init ipfrag_init(void) 895 { 896 ip4_frags_ctl_register(); 897 register_pernet_subsys(&ip4_frags_ops); 898 ip4_frags.hashfn = ip4_hashfn; 899 ip4_frags.constructor = ip4_frag_init; 900 ip4_frags.destructor = ip4_frag_free; 901 ip4_frags.qsize = sizeof(struct ipq); 902 ip4_frags.match = ip4_frag_match; 903 ip4_frags.frag_expire = ip_expire; 904 ip4_frags.frags_cache_name = ip_frag_cache_name; 905 if (inet_frags_init(&ip4_frags)) 906 panic("IP: failed to allocate ip4_frags cache\n"); 907 } 908