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