1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * The IP fragmentation functionality. 8 * 9 * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> 10 * Alan Cox <alan@lxorguk.ukuu.org.uk> 11 * 12 * Fixes: 13 * Alan Cox : Split from ip.c , see ip_input.c for history. 14 * David S. Miller : Begin massive cleanup... 15 * Andi Kleen : Add sysctls. 16 * xxxx : Overlapfrag bug. 17 * Ultima : ip_expire() kernel panic. 18 * Bill Hawes : Frag accounting and evictor fixes. 19 * John McDonald : 0 length frag bug. 20 * Alexey Kuznetsov: SMP races, threading, cleanup. 21 * Patrick McHardy : LRU queue of frag heads for evictor. 22 */ 23 24 #define pr_fmt(fmt) "IPv4: " fmt 25 26 #include <linux/compiler.h> 27 #include <linux/module.h> 28 #include <linux/types.h> 29 #include <linux/mm.h> 30 #include <linux/jiffies.h> 31 #include <linux/skbuff.h> 32 #include <linux/list.h> 33 #include <linux/ip.h> 34 #include <linux/icmp.h> 35 #include <linux/netdevice.h> 36 #include <linux/jhash.h> 37 #include <linux/random.h> 38 #include <linux/slab.h> 39 #include <net/route.h> 40 #include <net/dst.h> 41 #include <net/sock.h> 42 #include <net/ip.h> 43 #include <net/icmp.h> 44 #include <net/checksum.h> 45 #include <net/inetpeer.h> 46 #include <net/inet_frag.h> 47 #include <linux/tcp.h> 48 #include <linux/udp.h> 49 #include <linux/inet.h> 50 #include <linux/netfilter_ipv4.h> 51 #include <net/inet_ecn.h> 52 #include <net/l3mdev.h> 53 54 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 55 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c 56 * as well. Or notify me, at least. --ANK 57 */ 58 static const char ip_frag_cache_name[] = "ip4-frags"; 59 60 struct ipfrag_skb_cb 61 { 62 struct inet_skb_parm h; 63 int offset; 64 }; 65 66 #define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) 67 68 /* Describe an entry in the "incomplete datagrams" queue. */ 69 struct ipq { 70 struct inet_frag_queue q; 71 72 u32 user; 73 __be32 saddr; 74 __be32 daddr; 75 __be16 id; 76 u8 protocol; 77 u8 ecn; /* RFC3168 support */ 78 u16 max_df_size; /* largest frag with DF set seen */ 79 int iif; 80 int vif; /* L3 master device index */ 81 unsigned int rid; 82 struct inet_peer *peer; 83 }; 84 85 static u8 ip4_frag_ecn(u8 tos) 86 { 87 return 1 << (tos & INET_ECN_MASK); 88 } 89 90 static struct inet_frags ip4_frags; 91 92 int ip_frag_mem(struct net *net) 93 { 94 return sum_frag_mem_limit(&net->ipv4.frags); 95 } 96 97 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 98 struct net_device *dev); 99 100 struct ip4_create_arg { 101 struct iphdr *iph; 102 u32 user; 103 int vif; 104 }; 105 106 static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 107 { 108 net_get_random_once(&ip4_frags.rnd, sizeof(ip4_frags.rnd)); 109 return jhash_3words((__force u32)id << 16 | prot, 110 (__force u32)saddr, (__force u32)daddr, 111 ip4_frags.rnd); 112 } 113 114 static unsigned int ip4_hashfn(const struct inet_frag_queue *q) 115 { 116 const struct ipq *ipq; 117 118 ipq = container_of(q, struct ipq, q); 119 return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); 120 } 121 122 static bool ip4_frag_match(const struct inet_frag_queue *q, const void *a) 123 { 124 const struct ipq *qp; 125 const struct ip4_create_arg *arg = a; 126 127 qp = container_of(q, struct ipq, q); 128 return qp->id == arg->iph->id && 129 qp->saddr == arg->iph->saddr && 130 qp->daddr == arg->iph->daddr && 131 qp->protocol == arg->iph->protocol && 132 qp->user == arg->user && 133 qp->vif == arg->vif; 134 } 135 136 static void ip4_frag_init(struct inet_frag_queue *q, const void *a) 137 { 138 struct ipq *qp = container_of(q, struct ipq, q); 139 struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4, 140 frags); 141 struct net *net = container_of(ipv4, struct net, ipv4); 142 143 const struct ip4_create_arg *arg = a; 144 145 qp->protocol = arg->iph->protocol; 146 qp->id = arg->iph->id; 147 qp->ecn = ip4_frag_ecn(arg->iph->tos); 148 qp->saddr = arg->iph->saddr; 149 qp->daddr = arg->iph->daddr; 150 qp->vif = arg->vif; 151 qp->user = arg->user; 152 qp->peer = q->net->max_dist ? 153 inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, arg->vif, 1) : 154 NULL; 155 } 156 157 static void ip4_frag_free(struct inet_frag_queue *q) 158 { 159 struct ipq *qp; 160 161 qp = container_of(q, struct ipq, q); 162 if (qp->peer) 163 inet_putpeer(qp->peer); 164 } 165 166 167 /* Destruction primitives. */ 168 169 static void ipq_put(struct ipq *ipq) 170 { 171 inet_frag_put(&ipq->q, &ip4_frags); 172 } 173 174 /* Kill ipq entry. It is not destroyed immediately, 175 * because caller (and someone more) holds reference count. 176 */ 177 static void ipq_kill(struct ipq *ipq) 178 { 179 inet_frag_kill(&ipq->q, &ip4_frags); 180 } 181 182 static bool frag_expire_skip_icmp(u32 user) 183 { 184 return user == IP_DEFRAG_AF_PACKET || 185 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN, 186 __IP_DEFRAG_CONNTRACK_IN_END) || 187 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN, 188 __IP_DEFRAG_CONNTRACK_BRIDGE_IN); 189 } 190 191 /* 192 * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 193 */ 194 static void ip_expire(struct timer_list *t) 195 { 196 struct inet_frag_queue *frag = from_timer(frag, t, timer); 197 struct ipq *qp; 198 struct net *net; 199 200 qp = container_of(frag, struct ipq, q); 201 net = container_of(qp->q.net, struct net, ipv4.frags); 202 203 rcu_read_lock(); 204 spin_lock(&qp->q.lock); 205 206 if (qp->q.flags & INET_FRAG_COMPLETE) 207 goto out; 208 209 ipq_kill(qp); 210 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 211 212 if (!inet_frag_evicting(&qp->q)) { 213 struct sk_buff *clone, *head = qp->q.fragments; 214 const struct iphdr *iph; 215 int err; 216 217 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT); 218 219 if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !qp->q.fragments) 220 goto out; 221 222 head->dev = dev_get_by_index_rcu(net, qp->iif); 223 if (!head->dev) 224 goto out; 225 226 227 /* skb has no dst, perform route lookup again */ 228 iph = ip_hdr(head); 229 err = ip_route_input_noref(head, iph->daddr, iph->saddr, 230 iph->tos, head->dev); 231 if (err) 232 goto out; 233 234 /* Only an end host needs to send an ICMP 235 * "Fragment Reassembly Timeout" message, per RFC792. 236 */ 237 if (frag_expire_skip_icmp(qp->user) && 238 (skb_rtable(head)->rt_type != RTN_LOCAL)) 239 goto out; 240 241 clone = skb_clone(head, GFP_ATOMIC); 242 243 /* Send an ICMP "Fragment Reassembly Timeout" message. */ 244 if (clone) { 245 spin_unlock(&qp->q.lock); 246 icmp_send(clone, ICMP_TIME_EXCEEDED, 247 ICMP_EXC_FRAGTIME, 0); 248 consume_skb(clone); 249 goto out_rcu_unlock; 250 } 251 } 252 out: 253 spin_unlock(&qp->q.lock); 254 out_rcu_unlock: 255 rcu_read_unlock(); 256 ipq_put(qp); 257 } 258 259 /* Find the correct entry in the "incomplete datagrams" queue for 260 * this IP datagram, and create new one, if nothing is found. 261 */ 262 static struct ipq *ip_find(struct net *net, struct iphdr *iph, 263 u32 user, int vif) 264 { 265 struct inet_frag_queue *q; 266 struct ip4_create_arg arg; 267 unsigned int hash; 268 269 arg.iph = iph; 270 arg.user = user; 271 arg.vif = vif; 272 273 hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); 274 275 q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); 276 if (IS_ERR_OR_NULL(q)) { 277 inet_frag_maybe_warn_overflow(q, pr_fmt()); 278 return NULL; 279 } 280 return container_of(q, struct ipq, q); 281 } 282 283 /* Is the fragment too far ahead to be part of ipq? */ 284 static int ip_frag_too_far(struct ipq *qp) 285 { 286 struct inet_peer *peer = qp->peer; 287 unsigned int max = qp->q.net->max_dist; 288 unsigned int start, end; 289 290 int rc; 291 292 if (!peer || !max) 293 return 0; 294 295 start = qp->rid; 296 end = atomic_inc_return(&peer->rid); 297 qp->rid = end; 298 299 rc = qp->q.fragments && (end - start) > max; 300 301 if (rc) { 302 struct net *net; 303 304 net = container_of(qp->q.net, struct net, ipv4.frags); 305 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 306 } 307 308 return rc; 309 } 310 311 static int ip_frag_reinit(struct ipq *qp) 312 { 313 struct sk_buff *fp; 314 unsigned int sum_truesize = 0; 315 316 if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { 317 refcount_inc(&qp->q.refcnt); 318 return -ETIMEDOUT; 319 } 320 321 fp = qp->q.fragments; 322 do { 323 struct sk_buff *xp = fp->next; 324 325 sum_truesize += fp->truesize; 326 kfree_skb(fp); 327 fp = xp; 328 } while (fp); 329 sub_frag_mem_limit(qp->q.net, sum_truesize); 330 331 qp->q.flags = 0; 332 qp->q.len = 0; 333 qp->q.meat = 0; 334 qp->q.fragments = NULL; 335 qp->q.fragments_tail = NULL; 336 qp->iif = 0; 337 qp->ecn = 0; 338 339 return 0; 340 } 341 342 /* Add new segment to existing queue. */ 343 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 344 { 345 struct sk_buff *prev, *next; 346 struct net_device *dev; 347 unsigned int fragsize; 348 int flags, offset; 349 int ihl, end; 350 int err = -ENOENT; 351 u8 ecn; 352 353 if (qp->q.flags & INET_FRAG_COMPLETE) 354 goto err; 355 356 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 357 unlikely(ip_frag_too_far(qp)) && 358 unlikely(err = ip_frag_reinit(qp))) { 359 ipq_kill(qp); 360 goto err; 361 } 362 363 ecn = ip4_frag_ecn(ip_hdr(skb)->tos); 364 offset = ntohs(ip_hdr(skb)->frag_off); 365 flags = offset & ~IP_OFFSET; 366 offset &= IP_OFFSET; 367 offset <<= 3; /* offset is in 8-byte chunks */ 368 ihl = ip_hdrlen(skb); 369 370 /* Determine the position of this fragment. */ 371 end = offset + skb->len - skb_network_offset(skb) - ihl; 372 err = -EINVAL; 373 374 /* Is this the final fragment? */ 375 if ((flags & IP_MF) == 0) { 376 /* If we already have some bits beyond end 377 * or have different end, the segment is corrupted. 378 */ 379 if (end < qp->q.len || 380 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len)) 381 goto err; 382 qp->q.flags |= INET_FRAG_LAST_IN; 383 qp->q.len = end; 384 } else { 385 if (end&7) { 386 end &= ~7; 387 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 388 skb->ip_summed = CHECKSUM_NONE; 389 } 390 if (end > qp->q.len) { 391 /* Some bits beyond end -> corruption. */ 392 if (qp->q.flags & INET_FRAG_LAST_IN) 393 goto err; 394 qp->q.len = end; 395 } 396 } 397 if (end == offset) 398 goto err; 399 400 err = -ENOMEM; 401 if (!pskb_pull(skb, skb_network_offset(skb) + ihl)) 402 goto err; 403 404 err = pskb_trim_rcsum(skb, end - offset); 405 if (err) 406 goto err; 407 408 /* Find out which fragments are in front and at the back of us 409 * in the chain of fragments so far. We must know where to put 410 * this fragment, right? 411 */ 412 prev = qp->q.fragments_tail; 413 if (!prev || FRAG_CB(prev)->offset < offset) { 414 next = NULL; 415 goto found; 416 } 417 prev = NULL; 418 for (next = qp->q.fragments; next != NULL; next = next->next) { 419 if (FRAG_CB(next)->offset >= offset) 420 break; /* bingo! */ 421 prev = next; 422 } 423 424 found: 425 /* We found where to put this one. Check for overlap with 426 * preceding fragment, and, if needed, align things so that 427 * any overlaps are eliminated. 428 */ 429 if (prev) { 430 int i = (FRAG_CB(prev)->offset + prev->len) - offset; 431 432 if (i > 0) { 433 offset += i; 434 err = -EINVAL; 435 if (end <= offset) 436 goto err; 437 err = -ENOMEM; 438 if (!pskb_pull(skb, i)) 439 goto err; 440 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 441 skb->ip_summed = CHECKSUM_NONE; 442 } 443 } 444 445 err = -ENOMEM; 446 447 while (next && FRAG_CB(next)->offset < end) { 448 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 449 450 if (i < next->len) { 451 /* Eat head of the next overlapped fragment 452 * and leave the loop. The next ones cannot overlap. 453 */ 454 if (!pskb_pull(next, i)) 455 goto err; 456 FRAG_CB(next)->offset += i; 457 qp->q.meat -= i; 458 if (next->ip_summed != CHECKSUM_UNNECESSARY) 459 next->ip_summed = CHECKSUM_NONE; 460 break; 461 } else { 462 struct sk_buff *free_it = next; 463 464 /* Old fragment is completely overridden with 465 * new one drop it. 466 */ 467 next = next->next; 468 469 if (prev) 470 prev->next = next; 471 else 472 qp->q.fragments = next; 473 474 qp->q.meat -= free_it->len; 475 sub_frag_mem_limit(qp->q.net, free_it->truesize); 476 kfree_skb(free_it); 477 } 478 } 479 480 FRAG_CB(skb)->offset = offset; 481 482 /* Insert this fragment in the chain of fragments. */ 483 skb->next = next; 484 if (!next) 485 qp->q.fragments_tail = skb; 486 if (prev) 487 prev->next = skb; 488 else 489 qp->q.fragments = skb; 490 491 dev = skb->dev; 492 if (dev) { 493 qp->iif = dev->ifindex; 494 skb->dev = NULL; 495 } 496 qp->q.stamp = skb->tstamp; 497 qp->q.meat += skb->len; 498 qp->ecn |= ecn; 499 add_frag_mem_limit(qp->q.net, skb->truesize); 500 if (offset == 0) 501 qp->q.flags |= INET_FRAG_FIRST_IN; 502 503 fragsize = skb->len + ihl; 504 505 if (fragsize > qp->q.max_size) 506 qp->q.max_size = fragsize; 507 508 if (ip_hdr(skb)->frag_off & htons(IP_DF) && 509 fragsize > qp->max_df_size) 510 qp->max_df_size = fragsize; 511 512 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && 513 qp->q.meat == qp->q.len) { 514 unsigned long orefdst = skb->_skb_refdst; 515 516 skb->_skb_refdst = 0UL; 517 err = ip_frag_reasm(qp, prev, dev); 518 skb->_skb_refdst = orefdst; 519 return err; 520 } 521 522 skb_dst_drop(skb); 523 return -EINPROGRESS; 524 525 err: 526 kfree_skb(skb); 527 return err; 528 } 529 530 531 /* Build a new IP datagram from all its fragments. */ 532 533 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 534 struct net_device *dev) 535 { 536 struct net *net = container_of(qp->q.net, struct net, ipv4.frags); 537 struct iphdr *iph; 538 struct sk_buff *fp, *head = qp->q.fragments; 539 int len; 540 int ihlen; 541 int err; 542 u8 ecn; 543 544 ipq_kill(qp); 545 546 ecn = ip_frag_ecn_table[qp->ecn]; 547 if (unlikely(ecn == 0xff)) { 548 err = -EINVAL; 549 goto out_fail; 550 } 551 /* Make the one we just received the head. */ 552 if (prev) { 553 head = prev->next; 554 fp = skb_clone(head, GFP_ATOMIC); 555 if (!fp) 556 goto out_nomem; 557 558 fp->next = head->next; 559 if (!fp->next) 560 qp->q.fragments_tail = fp; 561 prev->next = fp; 562 563 skb_morph(head, qp->q.fragments); 564 head->next = qp->q.fragments->next; 565 566 consume_skb(qp->q.fragments); 567 qp->q.fragments = head; 568 } 569 570 WARN_ON(!head); 571 WARN_ON(FRAG_CB(head)->offset != 0); 572 573 /* Allocate a new buffer for the datagram. */ 574 ihlen = ip_hdrlen(head); 575 len = ihlen + qp->q.len; 576 577 err = -E2BIG; 578 if (len > 65535) 579 goto out_oversize; 580 581 /* Head of list must not be cloned. */ 582 if (skb_unclone(head, GFP_ATOMIC)) 583 goto out_nomem; 584 585 /* If the first fragment is fragmented itself, we split 586 * it to two chunks: the first with data and paged part 587 * and the second, holding only fragments. */ 588 if (skb_has_frag_list(head)) { 589 struct sk_buff *clone; 590 int i, plen = 0; 591 592 clone = alloc_skb(0, GFP_ATOMIC); 593 if (!clone) 594 goto out_nomem; 595 clone->next = head->next; 596 head->next = clone; 597 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 598 skb_frag_list_init(head); 599 for (i = 0; i < skb_shinfo(head)->nr_frags; i++) 600 plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 601 clone->len = clone->data_len = head->data_len - plen; 602 head->data_len -= clone->len; 603 head->len -= clone->len; 604 clone->csum = 0; 605 clone->ip_summed = head->ip_summed; 606 add_frag_mem_limit(qp->q.net, clone->truesize); 607 } 608 609 skb_shinfo(head)->frag_list = head->next; 610 skb_push(head, head->data - skb_network_header(head)); 611 612 for (fp=head->next; fp; fp = fp->next) { 613 head->data_len += fp->len; 614 head->len += fp->len; 615 if (head->ip_summed != fp->ip_summed) 616 head->ip_summed = CHECKSUM_NONE; 617 else if (head->ip_summed == CHECKSUM_COMPLETE) 618 head->csum = csum_add(head->csum, fp->csum); 619 head->truesize += fp->truesize; 620 } 621 sub_frag_mem_limit(qp->q.net, head->truesize); 622 623 head->next = NULL; 624 head->dev = dev; 625 head->tstamp = qp->q.stamp; 626 IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); 627 628 iph = ip_hdr(head); 629 iph->tot_len = htons(len); 630 iph->tos |= ecn; 631 632 /* When we set IP_DF on a refragmented skb we must also force a 633 * call to ip_fragment to avoid forwarding a DF-skb of size s while 634 * original sender only sent fragments of size f (where f < s). 635 * 636 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest 637 * frag seen to avoid sending tiny DF-fragments in case skb was built 638 * from one very small df-fragment and one large non-df frag. 639 */ 640 if (qp->max_df_size == qp->q.max_size) { 641 IPCB(head)->flags |= IPSKB_FRAG_PMTU; 642 iph->frag_off = htons(IP_DF); 643 } else { 644 iph->frag_off = 0; 645 } 646 647 ip_send_check(iph); 648 649 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS); 650 qp->q.fragments = NULL; 651 qp->q.fragments_tail = NULL; 652 return 0; 653 654 out_nomem: 655 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp); 656 err = -ENOMEM; 657 goto out_fail; 658 out_oversize: 659 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); 660 out_fail: 661 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 662 return err; 663 } 664 665 /* Process an incoming IP datagram fragment. */ 666 int ip_defrag(struct net *net, struct sk_buff *skb, u32 user) 667 { 668 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev; 669 int vif = l3mdev_master_ifindex_rcu(dev); 670 struct ipq *qp; 671 672 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS); 673 skb_orphan(skb); 674 675 /* Lookup (or create) queue header */ 676 qp = ip_find(net, ip_hdr(skb), user, vif); 677 if (qp) { 678 int ret; 679 680 spin_lock(&qp->q.lock); 681 682 ret = ip_frag_queue(qp, skb); 683 684 spin_unlock(&qp->q.lock); 685 ipq_put(qp); 686 return ret; 687 } 688 689 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); 690 kfree_skb(skb); 691 return -ENOMEM; 692 } 693 EXPORT_SYMBOL(ip_defrag); 694 695 struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user) 696 { 697 struct iphdr iph; 698 int netoff; 699 u32 len; 700 701 if (skb->protocol != htons(ETH_P_IP)) 702 return skb; 703 704 netoff = skb_network_offset(skb); 705 706 if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0) 707 return skb; 708 709 if (iph.ihl < 5 || iph.version != 4) 710 return skb; 711 712 len = ntohs(iph.tot_len); 713 if (skb->len < netoff + len || len < (iph.ihl * 4)) 714 return skb; 715 716 if (ip_is_fragment(&iph)) { 717 skb = skb_share_check(skb, GFP_ATOMIC); 718 if (skb) { 719 if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) 720 return skb; 721 if (pskb_trim_rcsum(skb, netoff + len)) 722 return skb; 723 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 724 if (ip_defrag(net, skb, user)) 725 return NULL; 726 skb_clear_hash(skb); 727 } 728 } 729 return skb; 730 } 731 EXPORT_SYMBOL(ip_check_defrag); 732 733 #ifdef CONFIG_SYSCTL 734 static int zero; 735 736 static struct ctl_table ip4_frags_ns_ctl_table[] = { 737 { 738 .procname = "ipfrag_high_thresh", 739 .data = &init_net.ipv4.frags.high_thresh, 740 .maxlen = sizeof(int), 741 .mode = 0644, 742 .proc_handler = proc_dointvec_minmax, 743 .extra1 = &init_net.ipv4.frags.low_thresh 744 }, 745 { 746 .procname = "ipfrag_low_thresh", 747 .data = &init_net.ipv4.frags.low_thresh, 748 .maxlen = sizeof(int), 749 .mode = 0644, 750 .proc_handler = proc_dointvec_minmax, 751 .extra1 = &zero, 752 .extra2 = &init_net.ipv4.frags.high_thresh 753 }, 754 { 755 .procname = "ipfrag_time", 756 .data = &init_net.ipv4.frags.timeout, 757 .maxlen = sizeof(int), 758 .mode = 0644, 759 .proc_handler = proc_dointvec_jiffies, 760 }, 761 { 762 .procname = "ipfrag_max_dist", 763 .data = &init_net.ipv4.frags.max_dist, 764 .maxlen = sizeof(int), 765 .mode = 0644, 766 .proc_handler = proc_dointvec_minmax, 767 .extra1 = &zero 768 }, 769 { } 770 }; 771 772 /* secret interval has been deprecated */ 773 static int ip4_frags_secret_interval_unused; 774 static struct ctl_table ip4_frags_ctl_table[] = { 775 { 776 .procname = "ipfrag_secret_interval", 777 .data = &ip4_frags_secret_interval_unused, 778 .maxlen = sizeof(int), 779 .mode = 0644, 780 .proc_handler = proc_dointvec_jiffies, 781 }, 782 { } 783 }; 784 785 static int __net_init ip4_frags_ns_ctl_register(struct net *net) 786 { 787 struct ctl_table *table; 788 struct ctl_table_header *hdr; 789 790 table = ip4_frags_ns_ctl_table; 791 if (!net_eq(net, &init_net)) { 792 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); 793 if (!table) 794 goto err_alloc; 795 796 table[0].data = &net->ipv4.frags.high_thresh; 797 table[0].extra1 = &net->ipv4.frags.low_thresh; 798 table[0].extra2 = &init_net.ipv4.frags.high_thresh; 799 table[1].data = &net->ipv4.frags.low_thresh; 800 table[1].extra2 = &net->ipv4.frags.high_thresh; 801 table[2].data = &net->ipv4.frags.timeout; 802 table[3].data = &net->ipv4.frags.max_dist; 803 } 804 805 hdr = register_net_sysctl(net, "net/ipv4", table); 806 if (!hdr) 807 goto err_reg; 808 809 net->ipv4.frags_hdr = hdr; 810 return 0; 811 812 err_reg: 813 if (!net_eq(net, &init_net)) 814 kfree(table); 815 err_alloc: 816 return -ENOMEM; 817 } 818 819 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) 820 { 821 struct ctl_table *table; 822 823 table = net->ipv4.frags_hdr->ctl_table_arg; 824 unregister_net_sysctl_table(net->ipv4.frags_hdr); 825 kfree(table); 826 } 827 828 static void __init ip4_frags_ctl_register(void) 829 { 830 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); 831 } 832 #else 833 static int ip4_frags_ns_ctl_register(struct net *net) 834 { 835 return 0; 836 } 837 838 static void ip4_frags_ns_ctl_unregister(struct net *net) 839 { 840 } 841 842 static void __init ip4_frags_ctl_register(void) 843 { 844 } 845 #endif 846 847 static int __net_init ipv4_frags_init_net(struct net *net) 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 inet_frags_init_net(&net->ipv4.frags); 875 876 return ip4_frags_ns_ctl_register(net); 877 } 878 879 static void __net_exit ipv4_frags_exit_net(struct net *net) 880 { 881 ip4_frags_ns_ctl_unregister(net); 882 inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); 883 } 884 885 static struct pernet_operations ip4_frags_ops = { 886 .init = ipv4_frags_init_net, 887 .exit = ipv4_frags_exit_net, 888 .async = true, 889 }; 890 891 void __init ipfrag_init(void) 892 { 893 ip4_frags_ctl_register(); 894 register_pernet_subsys(&ip4_frags_ops); 895 ip4_frags.hashfn = ip4_hashfn; 896 ip4_frags.constructor = ip4_frag_init; 897 ip4_frags.destructor = ip4_frag_free; 898 ip4_frags.qsize = sizeof(struct ipq); 899 ip4_frags.match = ip4_frag_match; 900 ip4_frags.frag_expire = ip_expire; 901 ip4_frags.frags_cache_name = ip_frag_cache_name; 902 if (inet_frags_init(&ip4_frags)) 903 panic("IP: failed to allocate ip4_frags cache\n"); 904 } 905