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 52 /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 53 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c 54 * as well. Or notify me, at least. --ANK 55 */ 56 57 static int sysctl_ipfrag_max_dist __read_mostly = 64; 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 int iif; 78 unsigned int rid; 79 struct inet_peer *peer; 80 }; 81 82 static inline u8 ip4_frag_ecn(u8 tos) 83 { 84 return 1 << (tos & INET_ECN_MASK); 85 } 86 87 static struct inet_frags ip4_frags; 88 89 int ip_frag_nqueues(struct net *net) 90 { 91 return net->ipv4.frags.nqueues; 92 } 93 94 int ip_frag_mem(struct net *net) 95 { 96 return sum_frag_mem_limit(&net->ipv4.frags); 97 } 98 99 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 100 struct net_device *dev); 101 102 struct ip4_create_arg { 103 struct iphdr *iph; 104 u32 user; 105 }; 106 107 static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 108 { 109 return jhash_3words((__force u32)id << 16 | prot, 110 (__force u32)saddr, (__force u32)daddr, 111 ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); 112 } 113 114 static unsigned int ip4_hashfn(struct inet_frag_queue *q) 115 { 116 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(struct inet_frag_queue *q, void *a) 123 { 124 struct ipq *qp; 125 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 } 134 135 static void ip4_frag_init(struct inet_frag_queue *q, 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 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->user = arg->user; 150 qp->peer = sysctl_ipfrag_max_dist ? 151 inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, 1) : NULL; 152 } 153 154 static __inline__ void ip4_frag_free(struct inet_frag_queue *q) 155 { 156 struct ipq *qp; 157 158 qp = container_of(q, struct ipq, q); 159 if (qp->peer) 160 inet_putpeer(qp->peer); 161 } 162 163 164 /* Destruction primitives. */ 165 166 static __inline__ void ipq_put(struct ipq *ipq) 167 { 168 inet_frag_put(&ipq->q, &ip4_frags); 169 } 170 171 /* Kill ipq entry. It is not destroyed immediately, 172 * because caller (and someone more) holds reference count. 173 */ 174 static void ipq_kill(struct ipq *ipq) 175 { 176 inet_frag_kill(&ipq->q, &ip4_frags); 177 } 178 179 /* Memory limiting on fragments. Evictor trashes the oldest 180 * fragment queue until we are back under the threshold. 181 */ 182 static void ip_evictor(struct net *net) 183 { 184 int evicted; 185 186 evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags, false); 187 if (evicted) 188 IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted); 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 spin_lock(&qp->q.lock); 203 204 if (qp->q.last_in & INET_FRAG_COMPLETE) 205 goto out; 206 207 ipq_kill(qp); 208 209 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT); 210 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); 211 212 if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) { 213 struct sk_buff *head = qp->q.fragments; 214 const struct iphdr *iph; 215 int err; 216 217 rcu_read_lock(); 218 head->dev = dev_get_by_index_rcu(net, qp->iif); 219 if (!head->dev) 220 goto out_rcu_unlock; 221 222 /* skb dst is stale, drop it, and perform route lookup again */ 223 skb_dst_drop(head); 224 iph = ip_hdr(head); 225 err = ip_route_input_noref(head, iph->daddr, iph->saddr, 226 iph->tos, head->dev); 227 if (err) 228 goto out_rcu_unlock; 229 230 /* 231 * Only an end host needs to send an ICMP 232 * "Fragment Reassembly Timeout" message, per RFC792. 233 */ 234 if (qp->user == IP_DEFRAG_AF_PACKET || 235 (qp->user == IP_DEFRAG_CONNTRACK_IN && 236 skb_rtable(head)->rt_type != RTN_LOCAL)) 237 goto out_rcu_unlock; 238 239 240 /* Send an ICMP "Fragment Reassembly Timeout" message. */ 241 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); 242 out_rcu_unlock: 243 rcu_read_unlock(); 244 } 245 out: 246 spin_unlock(&qp->q.lock); 247 ipq_put(qp); 248 } 249 250 /* Find the correct entry in the "incomplete datagrams" queue for 251 * this IP datagram, and create new one, if nothing is found. 252 */ 253 static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) 254 { 255 struct inet_frag_queue *q; 256 struct ip4_create_arg arg; 257 unsigned int hash; 258 259 arg.iph = iph; 260 arg.user = user; 261 262 read_lock(&ip4_frags.lock); 263 hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); 264 265 q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); 266 if (IS_ERR_OR_NULL(q)) { 267 inet_frag_maybe_warn_overflow(q, pr_fmt()); 268 return NULL; 269 } 270 return container_of(q, struct ipq, q); 271 } 272 273 /* Is the fragment too far ahead to be part of ipq? */ 274 static inline int ip_frag_too_far(struct ipq *qp) 275 { 276 struct inet_peer *peer = qp->peer; 277 unsigned int max = sysctl_ipfrag_max_dist; 278 unsigned int start, end; 279 280 int rc; 281 282 if (!peer || !max) 283 return 0; 284 285 start = qp->rid; 286 end = atomic_inc_return(&peer->rid); 287 qp->rid = end; 288 289 rc = qp->q.fragments && (end - start) > max; 290 291 if (rc) { 292 struct net *net; 293 294 net = container_of(qp->q.net, struct net, ipv4.frags); 295 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); 296 } 297 298 return rc; 299 } 300 301 static int ip_frag_reinit(struct ipq *qp) 302 { 303 struct sk_buff *fp; 304 unsigned int sum_truesize = 0; 305 306 if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { 307 atomic_inc(&qp->q.refcnt); 308 return -ETIMEDOUT; 309 } 310 311 fp = qp->q.fragments; 312 do { 313 struct sk_buff *xp = fp->next; 314 315 sum_truesize += fp->truesize; 316 kfree_skb(fp); 317 fp = xp; 318 } while (fp); 319 sub_frag_mem_limit(&qp->q, sum_truesize); 320 321 qp->q.last_in = 0; 322 qp->q.len = 0; 323 qp->q.meat = 0; 324 qp->q.fragments = NULL; 325 qp->q.fragments_tail = NULL; 326 qp->iif = 0; 327 qp->ecn = 0; 328 329 return 0; 330 } 331 332 /* Add new segment to existing queue. */ 333 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 334 { 335 struct sk_buff *prev, *next; 336 struct net_device *dev; 337 int flags, offset; 338 int ihl, end; 339 int err = -ENOENT; 340 u8 ecn; 341 342 if (qp->q.last_in & INET_FRAG_COMPLETE) 343 goto err; 344 345 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 346 unlikely(ip_frag_too_far(qp)) && 347 unlikely(err = ip_frag_reinit(qp))) { 348 ipq_kill(qp); 349 goto err; 350 } 351 352 ecn = ip4_frag_ecn(ip_hdr(skb)->tos); 353 offset = ntohs(ip_hdr(skb)->frag_off); 354 flags = offset & ~IP_OFFSET; 355 offset &= IP_OFFSET; 356 offset <<= 3; /* offset is in 8-byte chunks */ 357 ihl = ip_hdrlen(skb); 358 359 /* Determine the position of this fragment. */ 360 end = offset + skb->len - ihl; 361 err = -EINVAL; 362 363 /* Is this the final fragment? */ 364 if ((flags & IP_MF) == 0) { 365 /* If we already have some bits beyond end 366 * or have different end, the segment is corrupted. 367 */ 368 if (end < qp->q.len || 369 ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) 370 goto err; 371 qp->q.last_in |= INET_FRAG_LAST_IN; 372 qp->q.len = end; 373 } else { 374 if (end&7) { 375 end &= ~7; 376 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 377 skb->ip_summed = CHECKSUM_NONE; 378 } 379 if (end > qp->q.len) { 380 /* Some bits beyond end -> corruption. */ 381 if (qp->q.last_in & INET_FRAG_LAST_IN) 382 goto err; 383 qp->q.len = end; 384 } 385 } 386 if (end == offset) 387 goto err; 388 389 err = -ENOMEM; 390 if (pskb_pull(skb, ihl) == NULL) 391 goto err; 392 393 err = pskb_trim_rcsum(skb, end - offset); 394 if (err) 395 goto err; 396 397 /* Find out which fragments are in front and at the back of us 398 * in the chain of fragments so far. We must know where to put 399 * this fragment, right? 400 */ 401 prev = qp->q.fragments_tail; 402 if (!prev || FRAG_CB(prev)->offset < offset) { 403 next = NULL; 404 goto found; 405 } 406 prev = NULL; 407 for (next = qp->q.fragments; next != NULL; next = next->next) { 408 if (FRAG_CB(next)->offset >= offset) 409 break; /* bingo! */ 410 prev = next; 411 } 412 413 found: 414 /* We found where to put this one. Check for overlap with 415 * preceding fragment, and, if needed, align things so that 416 * any overlaps are eliminated. 417 */ 418 if (prev) { 419 int i = (FRAG_CB(prev)->offset + prev->len) - offset; 420 421 if (i > 0) { 422 offset += i; 423 err = -EINVAL; 424 if (end <= offset) 425 goto err; 426 err = -ENOMEM; 427 if (!pskb_pull(skb, i)) 428 goto err; 429 if (skb->ip_summed != CHECKSUM_UNNECESSARY) 430 skb->ip_summed = CHECKSUM_NONE; 431 } 432 } 433 434 err = -ENOMEM; 435 436 while (next && FRAG_CB(next)->offset < end) { 437 int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 438 439 if (i < next->len) { 440 /* Eat head of the next overlapped fragment 441 * and leave the loop. The next ones cannot overlap. 442 */ 443 if (!pskb_pull(next, i)) 444 goto err; 445 FRAG_CB(next)->offset += i; 446 qp->q.meat -= i; 447 if (next->ip_summed != CHECKSUM_UNNECESSARY) 448 next->ip_summed = CHECKSUM_NONE; 449 break; 450 } else { 451 struct sk_buff *free_it = next; 452 453 /* Old fragment is completely overridden with 454 * new one drop it. 455 */ 456 next = next->next; 457 458 if (prev) 459 prev->next = next; 460 else 461 qp->q.fragments = next; 462 463 qp->q.meat -= free_it->len; 464 sub_frag_mem_limit(&qp->q, free_it->truesize); 465 kfree_skb(free_it); 466 } 467 } 468 469 FRAG_CB(skb)->offset = offset; 470 471 /* Insert this fragment in the chain of fragments. */ 472 skb->next = next; 473 if (!next) 474 qp->q.fragments_tail = skb; 475 if (prev) 476 prev->next = skb; 477 else 478 qp->q.fragments = skb; 479 480 dev = skb->dev; 481 if (dev) { 482 qp->iif = dev->ifindex; 483 skb->dev = NULL; 484 } 485 qp->q.stamp = skb->tstamp; 486 qp->q.meat += skb->len; 487 qp->ecn |= ecn; 488 add_frag_mem_limit(&qp->q, skb->truesize); 489 if (offset == 0) 490 qp->q.last_in |= INET_FRAG_FIRST_IN; 491 492 if (ip_hdr(skb)->frag_off & htons(IP_DF) && 493 skb->len + ihl > qp->q.max_size) 494 qp->q.max_size = skb->len + ihl; 495 496 if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && 497 qp->q.meat == qp->q.len) 498 return ip_frag_reasm(qp, prev, dev); 499 500 inet_frag_lru_move(&qp->q); 501 return -EINPROGRESS; 502 503 err: 504 kfree_skb(skb); 505 return err; 506 } 507 508 509 /* Build a new IP datagram from all its fragments. */ 510 511 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 512 struct net_device *dev) 513 { 514 struct net *net = container_of(qp->q.net, struct net, ipv4.frags); 515 struct iphdr *iph; 516 struct sk_buff *fp, *head = qp->q.fragments; 517 int len; 518 int ihlen; 519 int err; 520 int sum_truesize; 521 u8 ecn; 522 523 ipq_kill(qp); 524 525 ecn = ip_frag_ecn_table[qp->ecn]; 526 if (unlikely(ecn == 0xff)) { 527 err = -EINVAL; 528 goto out_fail; 529 } 530 /* Make the one we just received the head. */ 531 if (prev) { 532 head = prev->next; 533 fp = skb_clone(head, GFP_ATOMIC); 534 if (!fp) 535 goto out_nomem; 536 537 fp->next = head->next; 538 if (!fp->next) 539 qp->q.fragments_tail = fp; 540 prev->next = fp; 541 542 skb_morph(head, qp->q.fragments); 543 head->next = qp->q.fragments->next; 544 545 consume_skb(qp->q.fragments); 546 qp->q.fragments = head; 547 } 548 549 WARN_ON(head == NULL); 550 WARN_ON(FRAG_CB(head)->offset != 0); 551 552 /* Allocate a new buffer for the datagram. */ 553 ihlen = ip_hdrlen(head); 554 len = ihlen + qp->q.len; 555 556 err = -E2BIG; 557 if (len > 65535) 558 goto out_oversize; 559 560 /* Head of list must not be cloned. */ 561 if (skb_unclone(head, GFP_ATOMIC)) 562 goto out_nomem; 563 564 /* If the first fragment is fragmented itself, we split 565 * it to two chunks: the first with data and paged part 566 * and the second, holding only fragments. */ 567 if (skb_has_frag_list(head)) { 568 struct sk_buff *clone; 569 int i, plen = 0; 570 571 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) 572 goto out_nomem; 573 clone->next = head->next; 574 head->next = clone; 575 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 576 skb_frag_list_init(head); 577 for (i = 0; i < skb_shinfo(head)->nr_frags; i++) 578 plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 579 clone->len = clone->data_len = head->data_len - plen; 580 head->data_len -= clone->len; 581 head->len -= clone->len; 582 clone->csum = 0; 583 clone->ip_summed = head->ip_summed; 584 add_frag_mem_limit(&qp->q, clone->truesize); 585 } 586 587 skb_push(head, head->data - skb_network_header(head)); 588 589 sum_truesize = head->truesize; 590 for (fp = head->next; fp;) { 591 bool headstolen; 592 int delta; 593 struct sk_buff *next = fp->next; 594 595 sum_truesize += fp->truesize; 596 if (head->ip_summed != fp->ip_summed) 597 head->ip_summed = CHECKSUM_NONE; 598 else if (head->ip_summed == CHECKSUM_COMPLETE) 599 head->csum = csum_add(head->csum, fp->csum); 600 601 if (skb_try_coalesce(head, fp, &headstolen, &delta)) { 602 kfree_skb_partial(fp, headstolen); 603 } else { 604 if (!skb_shinfo(head)->frag_list) 605 skb_shinfo(head)->frag_list = fp; 606 head->data_len += fp->len; 607 head->len += fp->len; 608 head->truesize += fp->truesize; 609 } 610 fp = next; 611 } 612 sub_frag_mem_limit(&qp->q, sum_truesize); 613 614 head->next = NULL; 615 head->dev = dev; 616 head->tstamp = qp->q.stamp; 617 IPCB(head)->frag_max_size = qp->q.max_size; 618 619 iph = ip_hdr(head); 620 /* max_size != 0 implies at least one fragment had IP_DF set */ 621 iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0; 622 iph->tot_len = htons(len); 623 iph->tos |= ecn; 624 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); 625 qp->q.fragments = NULL; 626 qp->q.fragments_tail = NULL; 627 return 0; 628 629 out_nomem: 630 LIMIT_NETDEBUG(KERN_ERR pr_fmt("queue_glue: no memory for gluing queue %p\n"), 631 qp); 632 err = -ENOMEM; 633 goto out_fail; 634 out_oversize: 635 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); 636 out_fail: 637 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); 638 return err; 639 } 640 641 /* Process an incoming IP datagram fragment. */ 642 int ip_defrag(struct sk_buff *skb, u32 user) 643 { 644 struct ipq *qp; 645 struct net *net; 646 647 net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); 648 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); 649 650 /* Start by cleaning up the memory. */ 651 ip_evictor(net); 652 653 /* Lookup (or create) queue header */ 654 if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { 655 int ret; 656 657 spin_lock(&qp->q.lock); 658 659 ret = ip_frag_queue(qp, skb); 660 661 spin_unlock(&qp->q.lock); 662 ipq_put(qp); 663 return ret; 664 } 665 666 IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); 667 kfree_skb(skb); 668 return -ENOMEM; 669 } 670 EXPORT_SYMBOL(ip_defrag); 671 672 struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user) 673 { 674 struct iphdr iph; 675 u32 len; 676 677 if (skb->protocol != htons(ETH_P_IP)) 678 return skb; 679 680 if (!skb_copy_bits(skb, 0, &iph, sizeof(iph))) 681 return skb; 682 683 if (iph.ihl < 5 || iph.version != 4) 684 return skb; 685 686 len = ntohs(iph.tot_len); 687 if (skb->len < len || len < (iph.ihl * 4)) 688 return skb; 689 690 if (ip_is_fragment(&iph)) { 691 skb = skb_share_check(skb, GFP_ATOMIC); 692 if (skb) { 693 if (!pskb_may_pull(skb, iph.ihl*4)) 694 return skb; 695 if (pskb_trim_rcsum(skb, len)) 696 return skb; 697 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 698 if (ip_defrag(skb, user)) 699 return NULL; 700 skb->rxhash = 0; 701 } 702 } 703 return skb; 704 } 705 EXPORT_SYMBOL(ip_check_defrag); 706 707 #ifdef CONFIG_SYSCTL 708 static int zero; 709 710 static struct ctl_table ip4_frags_ns_ctl_table[] = { 711 { 712 .procname = "ipfrag_high_thresh", 713 .data = &init_net.ipv4.frags.high_thresh, 714 .maxlen = sizeof(int), 715 .mode = 0644, 716 .proc_handler = proc_dointvec 717 }, 718 { 719 .procname = "ipfrag_low_thresh", 720 .data = &init_net.ipv4.frags.low_thresh, 721 .maxlen = sizeof(int), 722 .mode = 0644, 723 .proc_handler = proc_dointvec 724 }, 725 { 726 .procname = "ipfrag_time", 727 .data = &init_net.ipv4.frags.timeout, 728 .maxlen = sizeof(int), 729 .mode = 0644, 730 .proc_handler = proc_dointvec_jiffies, 731 }, 732 { } 733 }; 734 735 static struct ctl_table ip4_frags_ctl_table[] = { 736 { 737 .procname = "ipfrag_secret_interval", 738 .data = &ip4_frags.secret_interval, 739 .maxlen = sizeof(int), 740 .mode = 0644, 741 .proc_handler = proc_dointvec_jiffies, 742 }, 743 { 744 .procname = "ipfrag_max_dist", 745 .data = &sysctl_ipfrag_max_dist, 746 .maxlen = sizeof(int), 747 .mode = 0644, 748 .proc_handler = proc_dointvec_minmax, 749 .extra1 = &zero 750 }, 751 { } 752 }; 753 754 static int __net_init ip4_frags_ns_ctl_register(struct net *net) 755 { 756 struct ctl_table *table; 757 struct ctl_table_header *hdr; 758 759 table = ip4_frags_ns_ctl_table; 760 if (!net_eq(net, &init_net)) { 761 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); 762 if (table == NULL) 763 goto err_alloc; 764 765 table[0].data = &net->ipv4.frags.high_thresh; 766 table[1].data = &net->ipv4.frags.low_thresh; 767 table[2].data = &net->ipv4.frags.timeout; 768 769 /* Don't export sysctls to unprivileged users */ 770 if (net->user_ns != &init_user_ns) 771 table[0].procname = NULL; 772 } 773 774 hdr = register_net_sysctl(net, "net/ipv4", table); 775 if (hdr == NULL) 776 goto err_reg; 777 778 net->ipv4.frags_hdr = hdr; 779 return 0; 780 781 err_reg: 782 if (!net_eq(net, &init_net)) 783 kfree(table); 784 err_alloc: 785 return -ENOMEM; 786 } 787 788 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) 789 { 790 struct ctl_table *table; 791 792 table = net->ipv4.frags_hdr->ctl_table_arg; 793 unregister_net_sysctl_table(net->ipv4.frags_hdr); 794 kfree(table); 795 } 796 797 static void ip4_frags_ctl_register(void) 798 { 799 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); 800 } 801 #else 802 static inline int ip4_frags_ns_ctl_register(struct net *net) 803 { 804 return 0; 805 } 806 807 static inline void ip4_frags_ns_ctl_unregister(struct net *net) 808 { 809 } 810 811 static inline void ip4_frags_ctl_register(void) 812 { 813 } 814 #endif 815 816 static int __net_init ipv4_frags_init_net(struct net *net) 817 { 818 /* Fragment cache limits. 819 * 820 * The fragment memory accounting code, (tries to) account for 821 * the real memory usage, by measuring both the size of frag 822 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue)) 823 * and the SKB's truesize. 824 * 825 * A 64K fragment consumes 129736 bytes (44*2944)+200 826 * (1500 truesize == 2944, sizeof(struct ipq) == 200) 827 * 828 * We will commit 4MB at one time. Should we cross that limit 829 * we will prune down to 3MB, making room for approx 8 big 64K 830 * fragments 8x128k. 831 */ 832 net->ipv4.frags.high_thresh = 4 * 1024 * 1024; 833 net->ipv4.frags.low_thresh = 3 * 1024 * 1024; 834 /* 835 * Important NOTE! Fragment queue must be destroyed before MSL expires. 836 * RFC791 is wrong proposing to prolongate timer each fragment arrival 837 * by TTL. 838 */ 839 net->ipv4.frags.timeout = IP_FRAG_TIME; 840 841 inet_frags_init_net(&net->ipv4.frags); 842 843 return ip4_frags_ns_ctl_register(net); 844 } 845 846 static void __net_exit ipv4_frags_exit_net(struct net *net) 847 { 848 ip4_frags_ns_ctl_unregister(net); 849 inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); 850 } 851 852 static struct pernet_operations ip4_frags_ops = { 853 .init = ipv4_frags_init_net, 854 .exit = ipv4_frags_exit_net, 855 }; 856 857 void __init ipfrag_init(void) 858 { 859 ip4_frags_ctl_register(); 860 register_pernet_subsys(&ip4_frags_ops); 861 ip4_frags.hashfn = ip4_hashfn; 862 ip4_frags.constructor = ip4_frag_init; 863 ip4_frags.destructor = ip4_frag_free; 864 ip4_frags.skb_free = NULL; 865 ip4_frags.qsize = sizeof(struct ipq); 866 ip4_frags.match = ip4_frag_match; 867 ip4_frags.frag_expire = ip_expire; 868 ip4_frags.secret_interval = 10 * 60 * HZ; 869 inet_frags_init(&ip4_frags); 870 } 871