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