1 /* 2 * NET3: Implementation of the ICMP protocol layer. 3 * 4 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * Some of the function names and the icmp unreach table for this 12 * module were derived from [icmp.c 1.0.11 06/02/93] by 13 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 14 * Other than that this module is a complete rewrite. 15 * 16 * Fixes: 17 * Clemens Fruhwirth : introduce global icmp rate limiting 18 * with icmp type masking ability instead 19 * of broken per type icmp timeouts. 20 * Mike Shaver : RFC1122 checks. 21 * Alan Cox : Multicast ping reply as self. 22 * Alan Cox : Fix atomicity lockup in ip_build_xmit 23 * call. 24 * Alan Cox : Added 216,128 byte paths to the MTU 25 * code. 26 * Martin Mares : RFC1812 checks. 27 * Martin Mares : Can be configured to follow redirects 28 * if acting as a router _without_ a 29 * routing protocol (RFC 1812). 30 * Martin Mares : Echo requests may be configured to 31 * be ignored (RFC 1812). 32 * Martin Mares : Limitation of ICMP error message 33 * transmit rate (RFC 1812). 34 * Martin Mares : TOS and Precedence set correctly 35 * (RFC 1812). 36 * Martin Mares : Now copying as much data from the 37 * original packet as we can without 38 * exceeding 576 bytes (RFC 1812). 39 * Willy Konynenberg : Transparent proxying support. 40 * Keith Owens : RFC1191 correction for 4.2BSD based 41 * path MTU bug. 42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 43 * valid (RFC 1812). 44 * Andi Kleen : Check all packet lengths properly 45 * and moved all kfree_skb() up to 46 * icmp_rcv. 47 * Andi Kleen : Move the rate limit bookkeeping 48 * into the dest entry and use a token 49 * bucket filter (thanks to ANK). Make 50 * the rates sysctl configurable. 51 * Yu Tianli : Fixed two ugly bugs in icmp_send 52 * - IP option length was accounted wrongly 53 * - ICMP header length was not accounted 54 * at all. 55 * Tristan Greaves : Added sysctl option to ignore bogus 56 * broadcast responses from broken routers. 57 * 58 * To Fix: 59 * 60 * - Should use skb_pull() instead of all the manual checking. 61 * This would also greatly simply some upper layer error handlers. --AK 62 * 63 */ 64 65 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 66 67 #include <linux/module.h> 68 #include <linux/types.h> 69 #include <linux/jiffies.h> 70 #include <linux/kernel.h> 71 #include <linux/fcntl.h> 72 #include <linux/socket.h> 73 #include <linux/in.h> 74 #include <linux/inet.h> 75 #include <linux/inetdevice.h> 76 #include <linux/netdevice.h> 77 #include <linux/string.h> 78 #include <linux/netfilter_ipv4.h> 79 #include <linux/slab.h> 80 #include <net/snmp.h> 81 #include <net/ip.h> 82 #include <net/route.h> 83 #include <net/protocol.h> 84 #include <net/icmp.h> 85 #include <net/tcp.h> 86 #include <net/udp.h> 87 #include <net/raw.h> 88 #include <net/ping.h> 89 #include <linux/skbuff.h> 90 #include <net/sock.h> 91 #include <linux/errno.h> 92 #include <linux/timer.h> 93 #include <linux/init.h> 94 #include <asm/uaccess.h> 95 #include <net/checksum.h> 96 #include <net/xfrm.h> 97 #include <net/inet_common.h> 98 #include <net/ip_fib.h> 99 #include <net/l3mdev.h> 100 101 /* 102 * Build xmit assembly blocks 103 */ 104 105 struct icmp_bxm { 106 struct sk_buff *skb; 107 int offset; 108 int data_len; 109 110 struct { 111 struct icmphdr icmph; 112 __be32 times[3]; 113 } data; 114 int head_len; 115 struct ip_options_data replyopts; 116 }; 117 118 /* An array of errno for error messages from dest unreach. */ 119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 120 121 const struct icmp_err icmp_err_convert[] = { 122 { 123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 124 .fatal = 0, 125 }, 126 { 127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 128 .fatal = 0, 129 }, 130 { 131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 132 .fatal = 1, 133 }, 134 { 135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 136 .fatal = 1, 137 }, 138 { 139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 140 .fatal = 0, 141 }, 142 { 143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 144 .fatal = 0, 145 }, 146 { 147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 148 .fatal = 1, 149 }, 150 { 151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 152 .fatal = 1, 153 }, 154 { 155 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 156 .fatal = 1, 157 }, 158 { 159 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 160 .fatal = 1, 161 }, 162 { 163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 164 .fatal = 1, 165 }, 166 { 167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 168 .fatal = 0, 169 }, 170 { 171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 172 .fatal = 0, 173 }, 174 { 175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 176 .fatal = 1, 177 }, 178 { 179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 180 .fatal = 1, 181 }, 182 { 183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 184 .fatal = 1, 185 }, 186 }; 187 EXPORT_SYMBOL(icmp_err_convert); 188 189 /* 190 * ICMP control array. This specifies what to do with each ICMP. 191 */ 192 193 struct icmp_control { 194 bool (*handler)(struct sk_buff *skb); 195 short error; /* This ICMP is classed as an error message */ 196 }; 197 198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 199 200 /* 201 * The ICMP socket(s). This is the most convenient way to flow control 202 * our ICMP output as well as maintain a clean interface throughout 203 * all layers. All Socketless IP sends will soon be gone. 204 * 205 * On SMP we have one ICMP socket per-cpu. 206 */ 207 static struct sock *icmp_sk(struct net *net) 208 { 209 return *this_cpu_ptr(net->ipv4.icmp_sk); 210 } 211 212 static inline struct sock *icmp_xmit_lock(struct net *net) 213 { 214 struct sock *sk; 215 216 local_bh_disable(); 217 218 sk = icmp_sk(net); 219 220 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 221 /* This can happen if the output path signals a 222 * dst_link_failure() for an outgoing ICMP packet. 223 */ 224 local_bh_enable(); 225 return NULL; 226 } 227 return sk; 228 } 229 230 static inline void icmp_xmit_unlock(struct sock *sk) 231 { 232 spin_unlock_bh(&sk->sk_lock.slock); 233 } 234 235 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 236 int sysctl_icmp_msgs_burst __read_mostly = 50; 237 238 static struct { 239 spinlock_t lock; 240 u32 credit; 241 u32 stamp; 242 } icmp_global = { 243 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 244 }; 245 246 /** 247 * icmp_global_allow - Are we allowed to send one more ICMP message ? 248 * 249 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec. 250 * Returns false if we reached the limit and can not send another packet. 251 * Note: called with BH disabled 252 */ 253 bool icmp_global_allow(void) 254 { 255 u32 credit, delta, incr = 0, now = (u32)jiffies; 256 bool rc = false; 257 258 /* Check if token bucket is empty and cannot be refilled 259 * without taking the spinlock. 260 */ 261 if (!icmp_global.credit) { 262 delta = min_t(u32, now - icmp_global.stamp, HZ); 263 if (delta < HZ / 50) 264 return false; 265 } 266 267 spin_lock(&icmp_global.lock); 268 delta = min_t(u32, now - icmp_global.stamp, HZ); 269 if (delta >= HZ / 50) { 270 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 271 if (incr) 272 icmp_global.stamp = now; 273 } 274 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 275 if (credit) { 276 credit--; 277 rc = true; 278 } 279 icmp_global.credit = credit; 280 spin_unlock(&icmp_global.lock); 281 return rc; 282 } 283 EXPORT_SYMBOL(icmp_global_allow); 284 285 /* 286 * Send an ICMP frame. 287 */ 288 289 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 290 struct flowi4 *fl4, int type, int code) 291 { 292 struct dst_entry *dst = &rt->dst; 293 bool rc = true; 294 295 if (type > NR_ICMP_TYPES) 296 goto out; 297 298 /* Don't limit PMTU discovery. */ 299 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 300 goto out; 301 302 /* No rate limit on loopback */ 303 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 304 goto out; 305 306 /* Limit if icmp type is enabled in ratemask. */ 307 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask)) 308 goto out; 309 310 rc = false; 311 if (icmp_global_allow()) { 312 int vif = l3mdev_master_ifindex(dst->dev); 313 struct inet_peer *peer; 314 315 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 316 rc = inet_peer_xrlim_allow(peer, 317 net->ipv4.sysctl_icmp_ratelimit); 318 if (peer) 319 inet_putpeer(peer); 320 } 321 out: 322 return rc; 323 } 324 325 /* 326 * Maintain the counters used in the SNMP statistics for outgoing ICMP 327 */ 328 void icmp_out_count(struct net *net, unsigned char type) 329 { 330 ICMPMSGOUT_INC_STATS(net, type); 331 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 332 } 333 334 /* 335 * Checksum each fragment, and on the first include the headers and final 336 * checksum. 337 */ 338 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 339 struct sk_buff *skb) 340 { 341 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 342 __wsum csum; 343 344 csum = skb_copy_and_csum_bits(icmp_param->skb, 345 icmp_param->offset + offset, 346 to, len, 0); 347 348 skb->csum = csum_block_add(skb->csum, csum, odd); 349 if (icmp_pointers[icmp_param->data.icmph.type].error) 350 nf_ct_attach(skb, icmp_param->skb); 351 return 0; 352 } 353 354 static void icmp_push_reply(struct icmp_bxm *icmp_param, 355 struct flowi4 *fl4, 356 struct ipcm_cookie *ipc, struct rtable **rt) 357 { 358 struct sock *sk; 359 struct sk_buff *skb; 360 361 sk = icmp_sk(dev_net((*rt)->dst.dev)); 362 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 363 icmp_param->data_len+icmp_param->head_len, 364 icmp_param->head_len, 365 ipc, rt, MSG_DONTWAIT) < 0) { 366 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 367 ip_flush_pending_frames(sk); 368 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 369 struct icmphdr *icmph = icmp_hdr(skb); 370 __wsum csum = 0; 371 struct sk_buff *skb1; 372 373 skb_queue_walk(&sk->sk_write_queue, skb1) { 374 csum = csum_add(csum, skb1->csum); 375 } 376 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 377 (char *)icmph, 378 icmp_param->head_len, csum); 379 icmph->checksum = csum_fold(csum); 380 skb->ip_summed = CHECKSUM_NONE; 381 ip_push_pending_frames(sk, fl4); 382 } 383 } 384 385 /* 386 * Driving logic for building and sending ICMP messages. 387 */ 388 389 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 390 { 391 struct ipcm_cookie ipc; 392 struct rtable *rt = skb_rtable(skb); 393 struct net *net = dev_net(rt->dst.dev); 394 struct flowi4 fl4; 395 struct sock *sk; 396 struct inet_sock *inet; 397 __be32 daddr, saddr; 398 u32 mark = IP4_REPLY_MARK(net, skb->mark); 399 400 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb)) 401 return; 402 403 sk = icmp_xmit_lock(net); 404 if (!sk) 405 return; 406 inet = inet_sk(sk); 407 408 icmp_param->data.icmph.checksum = 0; 409 410 inet->tos = ip_hdr(skb)->tos; 411 sk->sk_mark = mark; 412 daddr = ipc.addr = ip_hdr(skb)->saddr; 413 saddr = fib_compute_spec_dst(skb); 414 ipc.opt = NULL; 415 ipc.tx_flags = 0; 416 ipc.ttl = 0; 417 ipc.tos = -1; 418 419 if (icmp_param->replyopts.opt.opt.optlen) { 420 ipc.opt = &icmp_param->replyopts.opt; 421 if (ipc.opt->opt.srr) 422 daddr = icmp_param->replyopts.opt.opt.faddr; 423 } 424 memset(&fl4, 0, sizeof(fl4)); 425 fl4.daddr = daddr; 426 fl4.saddr = saddr; 427 fl4.flowi4_mark = mark; 428 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 429 fl4.flowi4_proto = IPPROTO_ICMP; 430 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 431 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 432 rt = ip_route_output_key(net, &fl4); 433 if (IS_ERR(rt)) 434 goto out_unlock; 435 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type, 436 icmp_param->data.icmph.code)) 437 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 438 ip_rt_put(rt); 439 out_unlock: 440 icmp_xmit_unlock(sk); 441 } 442 443 #ifdef CONFIG_IP_ROUTE_MULTIPATH 444 445 /* Source and destination is swapped. See ip_multipath_icmp_hash */ 446 static int icmp_multipath_hash_skb(const struct sk_buff *skb) 447 { 448 const struct iphdr *iph = ip_hdr(skb); 449 450 return fib_multipath_hash(iph->daddr, iph->saddr); 451 } 452 453 #else 454 455 #define icmp_multipath_hash_skb(skb) (-1) 456 457 #endif 458 459 static struct rtable *icmp_route_lookup(struct net *net, 460 struct flowi4 *fl4, 461 struct sk_buff *skb_in, 462 const struct iphdr *iph, 463 __be32 saddr, u8 tos, u32 mark, 464 int type, int code, 465 struct icmp_bxm *param) 466 { 467 struct rtable *rt, *rt2; 468 struct flowi4 fl4_dec; 469 int err; 470 471 memset(fl4, 0, sizeof(*fl4)); 472 fl4->daddr = (param->replyopts.opt.opt.srr ? 473 param->replyopts.opt.opt.faddr : iph->saddr); 474 fl4->saddr = saddr; 475 fl4->flowi4_mark = mark; 476 fl4->flowi4_tos = RT_TOS(tos); 477 fl4->flowi4_proto = IPPROTO_ICMP; 478 fl4->fl4_icmp_type = type; 479 fl4->fl4_icmp_code = code; 480 fl4->flowi4_oif = l3mdev_master_ifindex(skb_in->dev); 481 482 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 483 rt = __ip_route_output_key_hash(net, fl4, 484 icmp_multipath_hash_skb(skb_in)); 485 if (IS_ERR(rt)) 486 return rt; 487 488 /* No need to clone since we're just using its address. */ 489 rt2 = rt; 490 491 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 492 flowi4_to_flowi(fl4), NULL, 0); 493 if (!IS_ERR(rt)) { 494 if (rt != rt2) 495 return rt; 496 } else if (PTR_ERR(rt) == -EPERM) { 497 rt = NULL; 498 } else 499 return rt; 500 501 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 502 if (err) 503 goto relookup_failed; 504 505 if (inet_addr_type_dev_table(net, skb_in->dev, 506 fl4_dec.saddr) == RTN_LOCAL) { 507 rt2 = __ip_route_output_key(net, &fl4_dec); 508 if (IS_ERR(rt2)) 509 err = PTR_ERR(rt2); 510 } else { 511 struct flowi4 fl4_2 = {}; 512 unsigned long orefdst; 513 514 fl4_2.daddr = fl4_dec.saddr; 515 rt2 = ip_route_output_key(net, &fl4_2); 516 if (IS_ERR(rt2)) { 517 err = PTR_ERR(rt2); 518 goto relookup_failed; 519 } 520 /* Ugh! */ 521 orefdst = skb_in->_skb_refdst; /* save old refdst */ 522 skb_dst_set(skb_in, NULL); 523 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 524 RT_TOS(tos), rt2->dst.dev); 525 526 dst_release(&rt2->dst); 527 rt2 = skb_rtable(skb_in); 528 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 529 } 530 531 if (err) 532 goto relookup_failed; 533 534 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 535 flowi4_to_flowi(&fl4_dec), NULL, 536 XFRM_LOOKUP_ICMP); 537 if (!IS_ERR(rt2)) { 538 dst_release(&rt->dst); 539 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 540 rt = rt2; 541 } else if (PTR_ERR(rt2) == -EPERM) { 542 if (rt) 543 dst_release(&rt->dst); 544 return rt2; 545 } else { 546 err = PTR_ERR(rt2); 547 goto relookup_failed; 548 } 549 return rt; 550 551 relookup_failed: 552 if (rt) 553 return rt; 554 return ERR_PTR(err); 555 } 556 557 /* 558 * Send an ICMP message in response to a situation 559 * 560 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 561 * MAY send more (we do). 562 * MUST NOT change this header information. 563 * MUST NOT reply to a multicast/broadcast IP address. 564 * MUST NOT reply to a multicast/broadcast MAC address. 565 * MUST reply to only the first fragment. 566 */ 567 568 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 569 { 570 struct iphdr *iph; 571 int room; 572 struct icmp_bxm *icmp_param; 573 struct rtable *rt = skb_rtable(skb_in); 574 struct ipcm_cookie ipc; 575 struct flowi4 fl4; 576 __be32 saddr; 577 u8 tos; 578 u32 mark; 579 struct net *net; 580 struct sock *sk; 581 582 if (!rt) 583 goto out; 584 net = dev_net(rt->dst.dev); 585 586 /* 587 * Find the original header. It is expected to be valid, of course. 588 * Check this, icmp_send is called from the most obscure devices 589 * sometimes. 590 */ 591 iph = ip_hdr(skb_in); 592 593 if ((u8 *)iph < skb_in->head || 594 (skb_network_header(skb_in) + sizeof(*iph)) > 595 skb_tail_pointer(skb_in)) 596 goto out; 597 598 /* 599 * No replies to physical multicast/broadcast 600 */ 601 if (skb_in->pkt_type != PACKET_HOST) 602 goto out; 603 604 /* 605 * Now check at the protocol level 606 */ 607 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 608 goto out; 609 610 /* 611 * Only reply to fragment 0. We byte re-order the constant 612 * mask for efficiency. 613 */ 614 if (iph->frag_off & htons(IP_OFFSET)) 615 goto out; 616 617 /* 618 * If we send an ICMP error to an ICMP error a mess would result.. 619 */ 620 if (icmp_pointers[type].error) { 621 /* 622 * We are an error, check if we are replying to an 623 * ICMP error 624 */ 625 if (iph->protocol == IPPROTO_ICMP) { 626 u8 _inner_type, *itp; 627 628 itp = skb_header_pointer(skb_in, 629 skb_network_header(skb_in) + 630 (iph->ihl << 2) + 631 offsetof(struct icmphdr, 632 type) - 633 skb_in->data, 634 sizeof(_inner_type), 635 &_inner_type); 636 if (!itp) 637 goto out; 638 639 /* 640 * Assume any unknown ICMP type is an error. This 641 * isn't specified by the RFC, but think about it.. 642 */ 643 if (*itp > NR_ICMP_TYPES || 644 icmp_pointers[*itp].error) 645 goto out; 646 } 647 } 648 649 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC); 650 if (!icmp_param) 651 return; 652 653 sk = icmp_xmit_lock(net); 654 if (!sk) 655 goto out_free; 656 657 /* 658 * Construct source address and options. 659 */ 660 661 saddr = iph->daddr; 662 if (!(rt->rt_flags & RTCF_LOCAL)) { 663 struct net_device *dev = NULL; 664 665 rcu_read_lock(); 666 if (rt_is_input_route(rt) && 667 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 668 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 669 670 if (dev) 671 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 672 else 673 saddr = 0; 674 rcu_read_unlock(); 675 } 676 677 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 678 IPTOS_PREC_INTERNETCONTROL) : 679 iph->tos; 680 mark = IP4_REPLY_MARK(net, skb_in->mark); 681 682 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in)) 683 goto out_unlock; 684 685 686 /* 687 * Prepare data for ICMP header. 688 */ 689 690 icmp_param->data.icmph.type = type; 691 icmp_param->data.icmph.code = code; 692 icmp_param->data.icmph.un.gateway = info; 693 icmp_param->data.icmph.checksum = 0; 694 icmp_param->skb = skb_in; 695 icmp_param->offset = skb_network_offset(skb_in); 696 inet_sk(sk)->tos = tos; 697 sk->sk_mark = mark; 698 ipc.addr = iph->saddr; 699 ipc.opt = &icmp_param->replyopts.opt; 700 ipc.tx_flags = 0; 701 ipc.ttl = 0; 702 ipc.tos = -1; 703 704 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 705 type, code, icmp_param); 706 if (IS_ERR(rt)) 707 goto out_unlock; 708 709 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 710 goto ende; 711 712 /* RFC says return as much as we can without exceeding 576 bytes. */ 713 714 room = dst_mtu(&rt->dst); 715 if (room > 576) 716 room = 576; 717 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen; 718 room -= sizeof(struct icmphdr); 719 720 icmp_param->data_len = skb_in->len - icmp_param->offset; 721 if (icmp_param->data_len > room) 722 icmp_param->data_len = room; 723 icmp_param->head_len = sizeof(struct icmphdr); 724 725 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 726 ende: 727 ip_rt_put(rt); 728 out_unlock: 729 icmp_xmit_unlock(sk); 730 out_free: 731 kfree(icmp_param); 732 out:; 733 } 734 EXPORT_SYMBOL(icmp_send); 735 736 737 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 738 { 739 const struct iphdr *iph = (const struct iphdr *) skb->data; 740 const struct net_protocol *ipprot; 741 int protocol = iph->protocol; 742 743 /* Checkin full IP header plus 8 bytes of protocol to 744 * avoid additional coding at protocol handlers. 745 */ 746 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 747 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 748 return; 749 } 750 751 raw_icmp_error(skb, protocol, info); 752 753 ipprot = rcu_dereference(inet_protos[protocol]); 754 if (ipprot && ipprot->err_handler) 755 ipprot->err_handler(skb, info); 756 } 757 758 static bool icmp_tag_validation(int proto) 759 { 760 bool ok; 761 762 rcu_read_lock(); 763 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 764 rcu_read_unlock(); 765 return ok; 766 } 767 768 /* 769 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and 770 * ICMP_PARAMETERPROB. 771 */ 772 773 static bool icmp_unreach(struct sk_buff *skb) 774 { 775 const struct iphdr *iph; 776 struct icmphdr *icmph; 777 struct net *net; 778 u32 info = 0; 779 780 net = dev_net(skb_dst(skb)->dev); 781 782 /* 783 * Incomplete header ? 784 * Only checks for the IP header, there should be an 785 * additional check for longer headers in upper levels. 786 */ 787 788 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 789 goto out_err; 790 791 icmph = icmp_hdr(skb); 792 iph = (const struct iphdr *)skb->data; 793 794 if (iph->ihl < 5) /* Mangled header, drop. */ 795 goto out_err; 796 797 if (icmph->type == ICMP_DEST_UNREACH) { 798 switch (icmph->code & 15) { 799 case ICMP_NET_UNREACH: 800 case ICMP_HOST_UNREACH: 801 case ICMP_PROT_UNREACH: 802 case ICMP_PORT_UNREACH: 803 break; 804 case ICMP_FRAG_NEEDED: 805 /* for documentation of the ip_no_pmtu_disc 806 * values please see 807 * Documentation/networking/ip-sysctl.txt 808 */ 809 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 810 default: 811 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 812 &iph->daddr); 813 break; 814 case 2: 815 goto out; 816 case 3: 817 if (!icmp_tag_validation(iph->protocol)) 818 goto out; 819 /* fall through */ 820 case 0: 821 info = ntohs(icmph->un.frag.mtu); 822 } 823 break; 824 case ICMP_SR_FAILED: 825 net_dbg_ratelimited("%pI4: Source Route Failed\n", 826 &iph->daddr); 827 break; 828 default: 829 break; 830 } 831 if (icmph->code > NR_ICMP_UNREACH) 832 goto out; 833 } else if (icmph->type == ICMP_PARAMETERPROB) 834 info = ntohl(icmph->un.gateway) >> 24; 835 836 /* 837 * Throw it at our lower layers 838 * 839 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 840 * header. 841 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 842 * transport layer. 843 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 844 * transport layer. 845 */ 846 847 /* 848 * Check the other end isn't violating RFC 1122. Some routers send 849 * bogus responses to broadcast frames. If you see this message 850 * first check your netmask matches at both ends, if it does then 851 * get the other vendor to fix their kit. 852 */ 853 854 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 855 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 856 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 857 &ip_hdr(skb)->saddr, 858 icmph->type, icmph->code, 859 &iph->daddr, skb->dev->name); 860 goto out; 861 } 862 863 icmp_socket_deliver(skb, info); 864 865 out: 866 return true; 867 out_err: 868 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 869 return false; 870 } 871 872 873 /* 874 * Handle ICMP_REDIRECT. 875 */ 876 877 static bool icmp_redirect(struct sk_buff *skb) 878 { 879 if (skb->len < sizeof(struct iphdr)) { 880 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 881 return false; 882 } 883 884 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 885 /* there aught to be a stat */ 886 return false; 887 } 888 889 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway); 890 return true; 891 } 892 893 /* 894 * Handle ICMP_ECHO ("ping") requests. 895 * 896 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 897 * requests. 898 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 899 * included in the reply. 900 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 901 * echo requests, MUST have default=NOT. 902 * See also WRT handling of options once they are done and working. 903 */ 904 905 static bool icmp_echo(struct sk_buff *skb) 906 { 907 struct net *net; 908 909 net = dev_net(skb_dst(skb)->dev); 910 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 911 struct icmp_bxm icmp_param; 912 913 icmp_param.data.icmph = *icmp_hdr(skb); 914 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 915 icmp_param.skb = skb; 916 icmp_param.offset = 0; 917 icmp_param.data_len = skb->len; 918 icmp_param.head_len = sizeof(struct icmphdr); 919 icmp_reply(&icmp_param, skb); 920 } 921 /* should there be an ICMP stat for ignored echos? */ 922 return true; 923 } 924 925 /* 926 * Handle ICMP Timestamp requests. 927 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 928 * SHOULD be in the kernel for minimum random latency. 929 * MUST be accurate to a few minutes. 930 * MUST be updated at least at 15Hz. 931 */ 932 static bool icmp_timestamp(struct sk_buff *skb) 933 { 934 struct icmp_bxm icmp_param; 935 /* 936 * Too short. 937 */ 938 if (skb->len < 4) 939 goto out_err; 940 941 /* 942 * Fill in the current time as ms since midnight UT: 943 */ 944 icmp_param.data.times[1] = inet_current_timestamp(); 945 icmp_param.data.times[2] = icmp_param.data.times[1]; 946 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 947 BUG(); 948 icmp_param.data.icmph = *icmp_hdr(skb); 949 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 950 icmp_param.data.icmph.code = 0; 951 icmp_param.skb = skb; 952 icmp_param.offset = 0; 953 icmp_param.data_len = 0; 954 icmp_param.head_len = sizeof(struct icmphdr) + 12; 955 icmp_reply(&icmp_param, skb); 956 return true; 957 958 out_err: 959 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 960 return false; 961 } 962 963 static bool icmp_discard(struct sk_buff *skb) 964 { 965 /* pretend it was a success */ 966 return true; 967 } 968 969 /* 970 * Deal with incoming ICMP packets. 971 */ 972 int icmp_rcv(struct sk_buff *skb) 973 { 974 struct icmphdr *icmph; 975 struct rtable *rt = skb_rtable(skb); 976 struct net *net = dev_net(rt->dst.dev); 977 bool success; 978 979 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 980 struct sec_path *sp = skb_sec_path(skb); 981 int nh; 982 983 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 984 XFRM_STATE_ICMP)) 985 goto drop; 986 987 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 988 goto drop; 989 990 nh = skb_network_offset(skb); 991 skb_set_network_header(skb, sizeof(*icmph)); 992 993 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 994 goto drop; 995 996 skb_set_network_header(skb, nh); 997 } 998 999 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1000 1001 if (skb_checksum_simple_validate(skb)) 1002 goto csum_error; 1003 1004 if (!pskb_pull(skb, sizeof(*icmph))) 1005 goto error; 1006 1007 icmph = icmp_hdr(skb); 1008 1009 ICMPMSGIN_INC_STATS(net, icmph->type); 1010 /* 1011 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1012 * 1013 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1014 * discarded. 1015 */ 1016 if (icmph->type > NR_ICMP_TYPES) 1017 goto error; 1018 1019 1020 /* 1021 * Parse the ICMP message 1022 */ 1023 1024 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1025 /* 1026 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1027 * silently ignored (we let user decide with a sysctl). 1028 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1029 * discarded if to broadcast/multicast. 1030 */ 1031 if ((icmph->type == ICMP_ECHO || 1032 icmph->type == ICMP_TIMESTAMP) && 1033 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1034 goto error; 1035 } 1036 if (icmph->type != ICMP_ECHO && 1037 icmph->type != ICMP_TIMESTAMP && 1038 icmph->type != ICMP_ADDRESS && 1039 icmph->type != ICMP_ADDRESSREPLY) { 1040 goto error; 1041 } 1042 } 1043 1044 success = icmp_pointers[icmph->type].handler(skb); 1045 1046 if (success) { 1047 consume_skb(skb); 1048 return 0; 1049 } 1050 1051 drop: 1052 kfree_skb(skb); 1053 return 0; 1054 csum_error: 1055 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1056 error: 1057 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1058 goto drop; 1059 } 1060 1061 void icmp_err(struct sk_buff *skb, u32 info) 1062 { 1063 struct iphdr *iph = (struct iphdr *)skb->data; 1064 int offset = iph->ihl<<2; 1065 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1066 int type = icmp_hdr(skb)->type; 1067 int code = icmp_hdr(skb)->code; 1068 struct net *net = dev_net(skb->dev); 1069 1070 /* 1071 * Use ping_err to handle all icmp errors except those 1072 * triggered by ICMP_ECHOREPLY which sent from kernel. 1073 */ 1074 if (icmph->type != ICMP_ECHOREPLY) { 1075 ping_err(skb, offset, info); 1076 return; 1077 } 1078 1079 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1080 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0); 1081 else if (type == ICMP_REDIRECT) 1082 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0); 1083 } 1084 1085 /* 1086 * This table is the definition of how we handle ICMP. 1087 */ 1088 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1089 [ICMP_ECHOREPLY] = { 1090 .handler = ping_rcv, 1091 }, 1092 [1] = { 1093 .handler = icmp_discard, 1094 .error = 1, 1095 }, 1096 [2] = { 1097 .handler = icmp_discard, 1098 .error = 1, 1099 }, 1100 [ICMP_DEST_UNREACH] = { 1101 .handler = icmp_unreach, 1102 .error = 1, 1103 }, 1104 [ICMP_SOURCE_QUENCH] = { 1105 .handler = icmp_unreach, 1106 .error = 1, 1107 }, 1108 [ICMP_REDIRECT] = { 1109 .handler = icmp_redirect, 1110 .error = 1, 1111 }, 1112 [6] = { 1113 .handler = icmp_discard, 1114 .error = 1, 1115 }, 1116 [7] = { 1117 .handler = icmp_discard, 1118 .error = 1, 1119 }, 1120 [ICMP_ECHO] = { 1121 .handler = icmp_echo, 1122 }, 1123 [9] = { 1124 .handler = icmp_discard, 1125 .error = 1, 1126 }, 1127 [10] = { 1128 .handler = icmp_discard, 1129 .error = 1, 1130 }, 1131 [ICMP_TIME_EXCEEDED] = { 1132 .handler = icmp_unreach, 1133 .error = 1, 1134 }, 1135 [ICMP_PARAMETERPROB] = { 1136 .handler = icmp_unreach, 1137 .error = 1, 1138 }, 1139 [ICMP_TIMESTAMP] = { 1140 .handler = icmp_timestamp, 1141 }, 1142 [ICMP_TIMESTAMPREPLY] = { 1143 .handler = icmp_discard, 1144 }, 1145 [ICMP_INFO_REQUEST] = { 1146 .handler = icmp_discard, 1147 }, 1148 [ICMP_INFO_REPLY] = { 1149 .handler = icmp_discard, 1150 }, 1151 [ICMP_ADDRESS] = { 1152 .handler = icmp_discard, 1153 }, 1154 [ICMP_ADDRESSREPLY] = { 1155 .handler = icmp_discard, 1156 }, 1157 }; 1158 1159 static void __net_exit icmp_sk_exit(struct net *net) 1160 { 1161 int i; 1162 1163 for_each_possible_cpu(i) 1164 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1165 free_percpu(net->ipv4.icmp_sk); 1166 net->ipv4.icmp_sk = NULL; 1167 } 1168 1169 static int __net_init icmp_sk_init(struct net *net) 1170 { 1171 int i, err; 1172 1173 net->ipv4.icmp_sk = alloc_percpu(struct sock *); 1174 if (!net->ipv4.icmp_sk) 1175 return -ENOMEM; 1176 1177 for_each_possible_cpu(i) { 1178 struct sock *sk; 1179 1180 err = inet_ctl_sock_create(&sk, PF_INET, 1181 SOCK_RAW, IPPROTO_ICMP, net); 1182 if (err < 0) 1183 goto fail; 1184 1185 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk; 1186 1187 /* Enough space for 2 64K ICMP packets, including 1188 * sk_buff/skb_shared_info struct overhead. 1189 */ 1190 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1191 1192 /* 1193 * Speedup sock_wfree() 1194 */ 1195 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1196 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1197 } 1198 1199 /* Control parameters for ECHO replies. */ 1200 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1201 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1202 1203 /* Control parameter - ignore bogus broadcast responses? */ 1204 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1205 1206 /* 1207 * Configurable global rate limit. 1208 * 1209 * ratelimit defines tokens/packet consumed for dst->rate_token 1210 * bucket ratemask defines which icmp types are ratelimited by 1211 * setting it's bit position. 1212 * 1213 * default: 1214 * dest unreachable (3), source quench (4), 1215 * time exceeded (11), parameter problem (12) 1216 */ 1217 1218 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1219 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1220 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1221 1222 return 0; 1223 1224 fail: 1225 for_each_possible_cpu(i) 1226 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1227 free_percpu(net->ipv4.icmp_sk); 1228 return err; 1229 } 1230 1231 static struct pernet_operations __net_initdata icmp_sk_ops = { 1232 .init = icmp_sk_init, 1233 .exit = icmp_sk_exit, 1234 }; 1235 1236 int __init icmp_init(void) 1237 { 1238 return register_pernet_subsys(&icmp_sk_ops); 1239 } 1240