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#include <linux/module.h> 66#include <linux/types.h> 67#include <linux/jiffies.h> 68#include <linux/kernel.h> 69#include <linux/fcntl.h> 70#include <linux/socket.h> 71#include <linux/in.h> 72#include <linux/inet.h> 73#include <linux/inetdevice.h> 74#include <linux/netdevice.h> 75#include <linux/string.h> 76#include <linux/netfilter_ipv4.h> 77#include <linux/slab.h> 78#include <net/snmp.h> 79#include <net/ip.h> 80#include <net/route.h> 81#include <net/protocol.h> 82#include <net/icmp.h> 83#include <net/tcp.h> 84#include <net/udp.h> 85#include <net/raw.h> 86#include <linux/skbuff.h> 87#include <net/sock.h> 88#include <linux/errno.h> 89#include <linux/timer.h> 90#include <linux/init.h> 91#include <asm/system.h> 92#include <asm/uaccess.h> 93#include <net/checksum.h> 94#include <net/xfrm.h> 95#include <net/inet_common.h> 96 97/* 98 * Build xmit assembly blocks 99 */ 100 101struct icmp_bxm { 102 struct sk_buff *skb; 103 int offset; 104 int data_len; 105 106 struct { 107 struct icmphdr icmph; 108 __be32 times[3]; 109 } data; 110 int head_len; 111 struct ip_options replyopts; 112 unsigned char optbuf[40]; 113}; 114 115/* An array of errno for error messages from dest unreach. */ 116/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 117 118const struct icmp_err icmp_err_convert[] = { 119 { 120 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 121 .fatal = 0, 122 }, 123 { 124 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 125 .fatal = 0, 126 }, 127 { 128 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 129 .fatal = 1, 130 }, 131 { 132 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 133 .fatal = 1, 134 }, 135 { 136 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 137 .fatal = 0, 138 }, 139 { 140 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 141 .fatal = 0, 142 }, 143 { 144 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 145 .fatal = 1, 146 }, 147 { 148 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 149 .fatal = 1, 150 }, 151 { 152 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 153 .fatal = 1, 154 }, 155 { 156 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 157 .fatal = 1, 158 }, 159 { 160 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 161 .fatal = 1, 162 }, 163 { 164 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 165 .fatal = 0, 166 }, 167 { 168 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 169 .fatal = 0, 170 }, 171 { 172 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 173 .fatal = 1, 174 }, 175 { 176 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 177 .fatal = 1, 178 }, 179 { 180 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 181 .fatal = 1, 182 }, 183}; 184EXPORT_SYMBOL(icmp_err_convert); 185 186/* 187 * ICMP control array. This specifies what to do with each ICMP. 188 */ 189 190struct icmp_control { 191 void (*handler)(struct sk_buff *skb); 192 short error; /* This ICMP is classed as an error message */ 193}; 194 195static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 196 197/* 198 * The ICMP socket(s). This is the most convenient way to flow control 199 * our ICMP output as well as maintain a clean interface throughout 200 * all layers. All Socketless IP sends will soon be gone. 201 * 202 * On SMP we have one ICMP socket per-cpu. 203 */ 204static struct sock *icmp_sk(struct net *net) 205{ 206 return net->ipv4.icmp_sk[smp_processor_id()]; 207} 208 209static inline struct sock *icmp_xmit_lock(struct net *net) 210{ 211 struct sock *sk; 212 213 local_bh_disable(); 214 215 sk = icmp_sk(net); 216 217 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 218 /* This can happen if the output path signals a 219 * dst_link_failure() for an outgoing ICMP packet. 220 */ 221 local_bh_enable(); 222 return NULL; 223 } 224 return sk; 225} 226 227static inline void icmp_xmit_unlock(struct sock *sk) 228{ 229 spin_unlock_bh(&sk->sk_lock.slock); 230} 231 232/* 233 * Send an ICMP frame. 234 */ 235 236/* 237 * Check transmit rate limitation for given message. 238 * The rate information is held in the destination cache now. 239 * This function is generic and could be used for other purposes 240 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. 241 * 242 * Note that the same dst_entry fields are modified by functions in 243 * route.c too, but these work for packet destinations while xrlim_allow 244 * works for icmp destinations. This means the rate limiting information 245 * for one "ip object" is shared - and these ICMPs are twice limited: 246 * by source and by destination. 247 * 248 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate 249 * SHOULD allow setting of rate limits 250 * 251 * Shared between ICMPv4 and ICMPv6. 252 */ 253#define XRLIM_BURST_FACTOR 6 254int xrlim_allow(struct dst_entry *dst, int timeout) 255{ 256 unsigned long now, token = dst->rate_tokens; 257 int rc = 0; 258 259 now = jiffies; 260 token += now - dst->rate_last; 261 dst->rate_last = now; 262 if (token > XRLIM_BURST_FACTOR * timeout) 263 token = XRLIM_BURST_FACTOR * timeout; 264 if (token >= timeout) { 265 token -= timeout; 266 rc = 1; 267 } 268 dst->rate_tokens = token; 269 return rc; 270} 271EXPORT_SYMBOL(xrlim_allow); 272 273static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 274 int type, int code) 275{ 276 struct dst_entry *dst = &rt->dst; 277 int rc = 1; 278 279 if (type > NR_ICMP_TYPES) 280 goto out; 281 282 /* Don't limit PMTU discovery. */ 283 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 284 goto out; 285 286 /* No rate limit on loopback */ 287 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 288 goto out; 289 290 /* Limit if icmp type is enabled in ratemask. */ 291 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) 292 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit); 293out: 294 return rc; 295} 296 297/* 298 * Maintain the counters used in the SNMP statistics for outgoing ICMP 299 */ 300void icmp_out_count(struct net *net, unsigned char type) 301{ 302 ICMPMSGOUT_INC_STATS(net, type); 303 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 304} 305 306/* 307 * Checksum each fragment, and on the first include the headers and final 308 * checksum. 309 */ 310static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 311 struct sk_buff *skb) 312{ 313 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 314 __wsum csum; 315 316 csum = skb_copy_and_csum_bits(icmp_param->skb, 317 icmp_param->offset + offset, 318 to, len, 0); 319 320 skb->csum = csum_block_add(skb->csum, csum, odd); 321 if (icmp_pointers[icmp_param->data.icmph.type].error) 322 nf_ct_attach(skb, icmp_param->skb); 323 return 0; 324} 325 326static void icmp_push_reply(struct icmp_bxm *icmp_param, 327 struct ipcm_cookie *ipc, struct rtable **rt) 328{ 329 struct sock *sk; 330 struct sk_buff *skb; 331 332 sk = icmp_sk(dev_net((*rt)->dst.dev)); 333 if (ip_append_data(sk, icmp_glue_bits, icmp_param, 334 icmp_param->data_len+icmp_param->head_len, 335 icmp_param->head_len, 336 ipc, rt, MSG_DONTWAIT) < 0) { 337 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS); 338 ip_flush_pending_frames(sk); 339 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 340 struct icmphdr *icmph = icmp_hdr(skb); 341 __wsum csum = 0; 342 struct sk_buff *skb1; 343 344 skb_queue_walk(&sk->sk_write_queue, skb1) { 345 csum = csum_add(csum, skb1->csum); 346 } 347 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 348 (char *)icmph, 349 icmp_param->head_len, csum); 350 icmph->checksum = csum_fold(csum); 351 skb->ip_summed = CHECKSUM_NONE; 352 ip_push_pending_frames(sk); 353 } 354} 355 356/* 357 * Driving logic for building and sending ICMP messages. 358 */ 359 360static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 361{ 362 struct ipcm_cookie ipc; 363 struct rtable *rt = skb_rtable(skb); 364 struct net *net = dev_net(rt->dst.dev); 365 struct sock *sk; 366 struct inet_sock *inet; 367 __be32 daddr; 368 369 if (ip_options_echo(&icmp_param->replyopts, skb)) 370 return; 371 372 sk = icmp_xmit_lock(net); 373 if (sk == NULL) 374 return; 375 inet = inet_sk(sk); 376 377 icmp_param->data.icmph.checksum = 0; 378 379 inet->tos = ip_hdr(skb)->tos; 380 daddr = ipc.addr = rt->rt_src; 381 ipc.opt = NULL; 382 ipc.shtx.flags = 0; 383 if (icmp_param->replyopts.optlen) { 384 ipc.opt = &icmp_param->replyopts; 385 if (ipc.opt->srr) 386 daddr = icmp_param->replyopts.faddr; 387 } 388 { 389 struct flowi fl = { .nl_u = { .ip4_u = 390 { .daddr = daddr, 391 .saddr = rt->rt_spec_dst, 392 .tos = RT_TOS(ip_hdr(skb)->tos) } }, 393 .proto = IPPROTO_ICMP }; 394 security_skb_classify_flow(skb, &fl); 395 if (ip_route_output_key(net, &rt, &fl)) 396 goto out_unlock; 397 } 398 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type, 399 icmp_param->data.icmph.code)) 400 icmp_push_reply(icmp_param, &ipc, &rt); 401 ip_rt_put(rt); 402out_unlock: 403 icmp_xmit_unlock(sk); 404} 405 406 407/* 408 * Send an ICMP message in response to a situation 409 * 410 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 411 * MAY send more (we do). 412 * MUST NOT change this header information. 413 * MUST NOT reply to a multicast/broadcast IP address. 414 * MUST NOT reply to a multicast/broadcast MAC address. 415 * MUST reply to only the first fragment. 416 */ 417 418void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 419{ 420 struct iphdr *iph; 421 int room; 422 struct icmp_bxm icmp_param; 423 struct rtable *rt = skb_rtable(skb_in); 424 struct ipcm_cookie ipc; 425 __be32 saddr; 426 u8 tos; 427 struct net *net; 428 struct sock *sk; 429 430 if (!rt) 431 goto out; 432 net = dev_net(rt->dst.dev); 433 434 /* 435 * Find the original header. It is expected to be valid, of course. 436 * Check this, icmp_send is called from the most obscure devices 437 * sometimes. 438 */ 439 iph = ip_hdr(skb_in); 440 441 if ((u8 *)iph < skb_in->head || 442 (skb_in->network_header + sizeof(*iph)) > skb_in->tail) 443 goto out; 444 445 /* 446 * No replies to physical multicast/broadcast 447 */ 448 if (skb_in->pkt_type != PACKET_HOST) 449 goto out; 450 451 /* 452 * Now check at the protocol level 453 */ 454 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 455 goto out; 456 457 /* 458 * Only reply to fragment 0. We byte re-order the constant 459 * mask for efficiency. 460 */ 461 if (iph->frag_off & htons(IP_OFFSET)) 462 goto out; 463 464 /* 465 * If we send an ICMP error to an ICMP error a mess would result.. 466 */ 467 if (icmp_pointers[type].error) { 468 /* 469 * We are an error, check if we are replying to an 470 * ICMP error 471 */ 472 if (iph->protocol == IPPROTO_ICMP) { 473 u8 _inner_type, *itp; 474 475 itp = skb_header_pointer(skb_in, 476 skb_network_header(skb_in) + 477 (iph->ihl << 2) + 478 offsetof(struct icmphdr, 479 type) - 480 skb_in->data, 481 sizeof(_inner_type), 482 &_inner_type); 483 if (itp == NULL) 484 goto out; 485 486 /* 487 * Assume any unknown ICMP type is an error. This 488 * isn't specified by the RFC, but think about it.. 489 */ 490 if (*itp > NR_ICMP_TYPES || 491 icmp_pointers[*itp].error) 492 goto out; 493 } 494 } 495 496 sk = icmp_xmit_lock(net); 497 if (sk == NULL) 498 return; 499 500 /* 501 * Construct source address and options. 502 */ 503 504 saddr = iph->daddr; 505 if (!(rt->rt_flags & RTCF_LOCAL)) { 506 struct net_device *dev = NULL; 507 508 rcu_read_lock(); 509 if (rt->fl.iif && 510 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 511 dev = dev_get_by_index_rcu(net, rt->fl.iif); 512 513 if (dev) 514 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 515 else 516 saddr = 0; 517 rcu_read_unlock(); 518 } 519 520 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 521 IPTOS_PREC_INTERNETCONTROL) : 522 iph->tos; 523 524 if (ip_options_echo(&icmp_param.replyopts, skb_in)) 525 goto out_unlock; 526 527 528 /* 529 * Prepare data for ICMP header. 530 */ 531 532 icmp_param.data.icmph.type = type; 533 icmp_param.data.icmph.code = code; 534 icmp_param.data.icmph.un.gateway = info; 535 icmp_param.data.icmph.checksum = 0; 536 icmp_param.skb = skb_in; 537 icmp_param.offset = skb_network_offset(skb_in); 538 inet_sk(sk)->tos = tos; 539 ipc.addr = iph->saddr; 540 ipc.opt = &icmp_param.replyopts; 541 ipc.shtx.flags = 0; 542 543 { 544 struct flowi fl = { 545 .nl_u = { 546 .ip4_u = { 547 .daddr = icmp_param.replyopts.srr ? 548 icmp_param.replyopts.faddr : 549 iph->saddr, 550 .saddr = saddr, 551 .tos = RT_TOS(tos) 552 } 553 }, 554 .proto = IPPROTO_ICMP, 555 .uli_u = { 556 .icmpt = { 557 .type = type, 558 .code = code 559 } 560 } 561 }; 562 int err; 563 struct rtable *rt2; 564 565 security_skb_classify_flow(skb_in, &fl); 566 if (__ip_route_output_key(net, &rt, &fl)) 567 goto out_unlock; 568 569 /* No need to clone since we're just using its address. */ 570 rt2 = rt; 571 572 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0); 573 switch (err) { 574 case 0: 575 if (rt != rt2) 576 goto route_done; 577 break; 578 case -EPERM: 579 rt = NULL; 580 break; 581 default: 582 goto out_unlock; 583 } 584 585 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET)) 586 goto relookup_failed; 587 588 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL) 589 err = __ip_route_output_key(net, &rt2, &fl); 590 else { 591 struct flowi fl2 = {}; 592 unsigned long orefdst; 593 594 fl2.fl4_dst = fl.fl4_src; 595 if (ip_route_output_key(net, &rt2, &fl2)) 596 goto relookup_failed; 597 598 /* Ugh! */ 599 orefdst = skb_in->_skb_refdst; /* save old refdst */ 600 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src, 601 RT_TOS(tos), rt2->dst.dev); 602 603 dst_release(&rt2->dst); 604 rt2 = skb_rtable(skb_in); 605 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 606 } 607 608 if (err) 609 goto relookup_failed; 610 611 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL, 612 XFRM_LOOKUP_ICMP); 613 switch (err) { 614 case 0: 615 dst_release(&rt->dst); 616 rt = rt2; 617 break; 618 case -EPERM: 619 goto ende; 620 default: 621relookup_failed: 622 if (!rt) 623 goto out_unlock; 624 break; 625 } 626 } 627 628route_done: 629 if (!icmpv4_xrlim_allow(net, rt, type, code)) 630 goto ende; 631 632 /* RFC says return as much as we can without exceeding 576 bytes. */ 633 634 room = dst_mtu(&rt->dst); 635 if (room > 576) 636 room = 576; 637 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; 638 room -= sizeof(struct icmphdr); 639 640 icmp_param.data_len = skb_in->len - icmp_param.offset; 641 if (icmp_param.data_len > room) 642 icmp_param.data_len = room; 643 icmp_param.head_len = sizeof(struct icmphdr); 644 645 icmp_push_reply(&icmp_param, &ipc, &rt); 646ende: 647 ip_rt_put(rt); 648out_unlock: 649 icmp_xmit_unlock(sk); 650out:; 651} 652EXPORT_SYMBOL(icmp_send); 653 654 655/* 656 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. 657 */ 658 659static void icmp_unreach(struct sk_buff *skb) 660{ 661 struct iphdr *iph; 662 struct icmphdr *icmph; 663 int hash, protocol; 664 const struct net_protocol *ipprot; 665 u32 info = 0; 666 struct net *net; 667 668 net = dev_net(skb_dst(skb)->dev); 669 670 /* 671 * Incomplete header ? 672 * Only checks for the IP header, there should be an 673 * additional check for longer headers in upper levels. 674 */ 675 676 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 677 goto out_err; 678 679 icmph = icmp_hdr(skb); 680 iph = (struct iphdr *)skb->data; 681 682 if (iph->ihl < 5) /* Mangled header, drop. */ 683 goto out_err; 684 685 if (icmph->type == ICMP_DEST_UNREACH) { 686 switch (icmph->code & 15) { 687 case ICMP_NET_UNREACH: 688 case ICMP_HOST_UNREACH: 689 case ICMP_PROT_UNREACH: 690 case ICMP_PORT_UNREACH: 691 break; 692 case ICMP_FRAG_NEEDED: 693 if (ipv4_config.no_pmtu_disc) { 694 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n", 695 &iph->daddr); 696 } else { 697 info = ip_rt_frag_needed(net, iph, 698 ntohs(icmph->un.frag.mtu), 699 skb->dev); 700 if (!info) 701 goto out; 702 } 703 break; 704 case ICMP_SR_FAILED: 705 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n", 706 &iph->daddr); 707 break; 708 default: 709 break; 710 } 711 if (icmph->code > NR_ICMP_UNREACH) 712 goto out; 713 } else if (icmph->type == ICMP_PARAMETERPROB) 714 info = ntohl(icmph->un.gateway) >> 24; 715 716 /* 717 * Throw it at our lower layers 718 * 719 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 720 * header. 721 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 722 * transport layer. 723 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 724 * transport layer. 725 */ 726 727 /* 728 * Check the other end isnt violating RFC 1122. Some routers send 729 * bogus responses to broadcast frames. If you see this message 730 * first check your netmask matches at both ends, if it does then 731 * get the other vendor to fix their kit. 732 */ 733 734 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 735 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { 736 if (net_ratelimit()) 737 printk(KERN_WARNING "%pI4 sent an invalid ICMP " 738 "type %u, code %u " 739 "error to a broadcast: %pI4 on %s\n", 740 &ip_hdr(skb)->saddr, 741 icmph->type, icmph->code, 742 &iph->daddr, 743 skb->dev->name); 744 goto out; 745 } 746 747 /* Checkin full IP header plus 8 bytes of protocol to 748 * avoid additional coding at protocol handlers. 749 */ 750 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 751 goto out; 752 753 iph = (struct iphdr *)skb->data; 754 protocol = iph->protocol; 755 756 /* 757 * Deliver ICMP message to raw sockets. Pretty useless feature? 758 */ 759 raw_icmp_error(skb, protocol, info); 760 761 hash = protocol & (MAX_INET_PROTOS - 1); 762 rcu_read_lock(); 763 ipprot = rcu_dereference(inet_protos[hash]); 764 if (ipprot && ipprot->err_handler) 765 ipprot->err_handler(skb, info); 766 rcu_read_unlock(); 767 768out: 769 return; 770out_err: 771 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 772 goto out; 773} 774 775 776/* 777 * Handle ICMP_REDIRECT. 778 */ 779 780static void icmp_redirect(struct sk_buff *skb) 781{ 782 struct iphdr *iph; 783 784 if (skb->len < sizeof(struct iphdr)) 785 goto out_err; 786 787 /* 788 * Get the copied header of the packet that caused the redirect 789 */ 790 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 791 goto out; 792 793 iph = (struct iphdr *)skb->data; 794 795 switch (icmp_hdr(skb)->code & 7) { 796 case ICMP_REDIR_NET: 797 case ICMP_REDIR_NETTOS: 798 /* 799 * As per RFC recommendations now handle it as a host redirect. 800 */ 801 case ICMP_REDIR_HOST: 802 case ICMP_REDIR_HOSTTOS: 803 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, 804 icmp_hdr(skb)->un.gateway, 805 iph->saddr, skb->dev); 806 break; 807 } 808out: 809 return; 810out_err: 811 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 812 goto out; 813} 814 815/* 816 * Handle ICMP_ECHO ("ping") requests. 817 * 818 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 819 * requests. 820 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 821 * included in the reply. 822 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 823 * echo requests, MUST have default=NOT. 824 * See also WRT handling of options once they are done and working. 825 */ 826 827static void icmp_echo(struct sk_buff *skb) 828{ 829 struct net *net; 830 831 net = dev_net(skb_dst(skb)->dev); 832 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 833 struct icmp_bxm icmp_param; 834 835 icmp_param.data.icmph = *icmp_hdr(skb); 836 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 837 icmp_param.skb = skb; 838 icmp_param.offset = 0; 839 icmp_param.data_len = skb->len; 840 icmp_param.head_len = sizeof(struct icmphdr); 841 icmp_reply(&icmp_param, skb); 842 } 843} 844 845/* 846 * Handle ICMP Timestamp requests. 847 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 848 * SHOULD be in the kernel for minimum random latency. 849 * MUST be accurate to a few minutes. 850 * MUST be updated at least at 15Hz. 851 */ 852static void icmp_timestamp(struct sk_buff *skb) 853{ 854 struct timespec tv; 855 struct icmp_bxm icmp_param; 856 /* 857 * Too short. 858 */ 859 if (skb->len < 4) 860 goto out_err; 861 862 /* 863 * Fill in the current time as ms since midnight UT: 864 */ 865 getnstimeofday(&tv); 866 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 867 tv.tv_nsec / NSEC_PER_MSEC); 868 icmp_param.data.times[2] = icmp_param.data.times[1]; 869 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 870 BUG(); 871 icmp_param.data.icmph = *icmp_hdr(skb); 872 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 873 icmp_param.data.icmph.code = 0; 874 icmp_param.skb = skb; 875 icmp_param.offset = 0; 876 icmp_param.data_len = 0; 877 icmp_param.head_len = sizeof(struct icmphdr) + 12; 878 icmp_reply(&icmp_param, skb); 879out: 880 return; 881out_err: 882 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 883 goto out; 884} 885 886 887/* 888 * Handle ICMP_ADDRESS_MASK requests. (RFC950) 889 * 890 * RFC1122 (3.2.2.9). A host MUST only send replies to 891 * ADDRESS_MASK requests if it's been configured as an address mask 892 * agent. Receiving a request doesn't constitute implicit permission to 893 * act as one. Of course, implementing this correctly requires (SHOULD) 894 * a way to turn the functionality on and off. Another one for sysctl(), 895 * I guess. -- MS 896 * 897 * RFC1812 (4.3.3.9). A router MUST implement it. 898 * A router SHOULD have switch turning it on/off. 899 * This switch MUST be ON by default. 900 * 901 * Gratuitous replies, zero-source replies are not implemented, 902 * that complies with RFC. DO NOT implement them!!! All the idea 903 * of broadcast addrmask replies as specified in RFC950 is broken. 904 * The problem is that it is not uncommon to have several prefixes 905 * on one physical interface. Moreover, addrmask agent can even be 906 * not aware of existing another prefixes. 907 * If source is zero, addrmask agent cannot choose correct prefix. 908 * Gratuitous mask announcements suffer from the same problem. 909 * RFC1812 explains it, but still allows to use ADDRMASK, 910 * that is pretty silly. --ANK 911 * 912 * All these rules are so bizarre, that I removed kernel addrmask 913 * support at all. It is wrong, it is obsolete, nobody uses it in 914 * any case. --ANK 915 * 916 * Furthermore you can do it with a usermode address agent program 917 * anyway... 918 */ 919 920static void icmp_address(struct sk_buff *skb) 921{ 922} 923 924/* 925 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain 926 * loudly if an inconsistency is found. 927 * called with rcu_read_lock() 928 */ 929 930static void icmp_address_reply(struct sk_buff *skb) 931{ 932 struct rtable *rt = skb_rtable(skb); 933 struct net_device *dev = skb->dev; 934 struct in_device *in_dev; 935 struct in_ifaddr *ifa; 936 937 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) 938 return; 939 940 in_dev = __in_dev_get_rcu(dev); 941 if (!in_dev) 942 return; 943 944 if (in_dev->ifa_list && 945 IN_DEV_LOG_MARTIANS(in_dev) && 946 IN_DEV_FORWARD(in_dev)) { 947 __be32 _mask, *mp; 948 949 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); 950 BUG_ON(mp == NULL); 951 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { 952 if (*mp == ifa->ifa_mask && 953 inet_ifa_match(rt->rt_src, ifa)) 954 break; 955 } 956 if (!ifa && net_ratelimit()) { 957 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n", 958 mp, dev->name, &rt->rt_src); 959 } 960 } 961} 962 963static void icmp_discard(struct sk_buff *skb) 964{ 965} 966 967/* 968 * Deal with incoming ICMP packets. 969 */ 970int icmp_rcv(struct sk_buff *skb) 971{ 972 struct icmphdr *icmph; 973 struct rtable *rt = skb_rtable(skb); 974 struct net *net = dev_net(rt->dst.dev); 975 976 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 977 struct sec_path *sp = skb_sec_path(skb); 978 int nh; 979 980 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 981 XFRM_STATE_ICMP)) 982 goto drop; 983 984 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 985 goto drop; 986 987 nh = skb_network_offset(skb); 988 skb_set_network_header(skb, sizeof(*icmph)); 989 990 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 991 goto drop; 992 993 skb_set_network_header(skb, nh); 994 } 995 996 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 997 998 switch (skb->ip_summed) { 999 case CHECKSUM_COMPLETE: 1000 if (!csum_fold(skb->csum)) 1001 break; 1002 /* fall through */ 1003 case CHECKSUM_NONE: 1004 skb->csum = 0; 1005 if (__skb_checksum_complete(skb)) 1006 goto error; 1007 } 1008 1009 if (!pskb_pull(skb, sizeof(*icmph))) 1010 goto error; 1011 1012 icmph = icmp_hdr(skb); 1013 1014 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 1015 /* 1016 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1017 * 1018 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1019 * discarded. 1020 */ 1021 if (icmph->type > NR_ICMP_TYPES) 1022 goto error; 1023 1024 1025 /* 1026 * Parse the ICMP message 1027 */ 1028 1029 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1030 /* 1031 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1032 * silently ignored (we let user decide with a sysctl). 1033 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1034 * discarded if to broadcast/multicast. 1035 */ 1036 if ((icmph->type == ICMP_ECHO || 1037 icmph->type == ICMP_TIMESTAMP) && 1038 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1039 goto error; 1040 } 1041 if (icmph->type != ICMP_ECHO && 1042 icmph->type != ICMP_TIMESTAMP && 1043 icmph->type != ICMP_ADDRESS && 1044 icmph->type != ICMP_ADDRESSREPLY) { 1045 goto error; 1046 } 1047 } 1048 1049 icmp_pointers[icmph->type].handler(skb); 1050 1051drop: 1052 kfree_skb(skb); 1053 return 0; 1054error: 1055 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 1056 goto drop; 1057} 1058 1059/* 1060 * This table is the definition of how we handle ICMP. 1061 */ 1062static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1063 [ICMP_ECHOREPLY] = { 1064 .handler = icmp_discard, 1065 }, 1066 [1] = { 1067 .handler = icmp_discard, 1068 .error = 1, 1069 }, 1070 [2] = { 1071 .handler = icmp_discard, 1072 .error = 1, 1073 }, 1074 [ICMP_DEST_UNREACH] = { 1075 .handler = icmp_unreach, 1076 .error = 1, 1077 }, 1078 [ICMP_SOURCE_QUENCH] = { 1079 .handler = icmp_unreach, 1080 .error = 1, 1081 }, 1082 [ICMP_REDIRECT] = { 1083 .handler = icmp_redirect, 1084 .error = 1, 1085 }, 1086 [6] = { 1087 .handler = icmp_discard, 1088 .error = 1, 1089 }, 1090 [7] = { 1091 .handler = icmp_discard, 1092 .error = 1, 1093 }, 1094 [ICMP_ECHO] = { 1095 .handler = icmp_echo, 1096 }, 1097 [9] = { 1098 .handler = icmp_discard, 1099 .error = 1, 1100 }, 1101 [10] = { 1102 .handler = icmp_discard, 1103 .error = 1, 1104 }, 1105 [ICMP_TIME_EXCEEDED] = { 1106 .handler = icmp_unreach, 1107 .error = 1, 1108 }, 1109 [ICMP_PARAMETERPROB] = { 1110 .handler = icmp_unreach, 1111 .error = 1, 1112 }, 1113 [ICMP_TIMESTAMP] = { 1114 .handler = icmp_timestamp, 1115 }, 1116 [ICMP_TIMESTAMPREPLY] = { 1117 .handler = icmp_discard, 1118 }, 1119 [ICMP_INFO_REQUEST] = { 1120 .handler = icmp_discard, 1121 }, 1122 [ICMP_INFO_REPLY] = { 1123 .handler = icmp_discard, 1124 }, 1125 [ICMP_ADDRESS] = { 1126 .handler = icmp_address, 1127 }, 1128 [ICMP_ADDRESSREPLY] = { 1129 .handler = icmp_address_reply, 1130 }, 1131}; 1132 1133static void __net_exit icmp_sk_exit(struct net *net) 1134{ 1135 int i; 1136 1137 for_each_possible_cpu(i) 1138 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1139 kfree(net->ipv4.icmp_sk); 1140 net->ipv4.icmp_sk = NULL; 1141} 1142 1143static int __net_init icmp_sk_init(struct net *net) 1144{ 1145 int i, err; 1146 1147 net->ipv4.icmp_sk = 1148 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); 1149 if (net->ipv4.icmp_sk == NULL) 1150 return -ENOMEM; 1151 1152 for_each_possible_cpu(i) { 1153 struct sock *sk; 1154 1155 err = inet_ctl_sock_create(&sk, PF_INET, 1156 SOCK_RAW, IPPROTO_ICMP, net); 1157 if (err < 0) 1158 goto fail; 1159 1160 net->ipv4.icmp_sk[i] = sk; 1161 1162 /* Enough space for 2 64K ICMP packets, including 1163 * sk_buff struct overhead. 1164 */ 1165 sk->sk_sndbuf = 1166 (2 * ((64 * 1024) + sizeof(struct sk_buff))); 1167 1168 /* 1169 * Speedup sock_wfree() 1170 */ 1171 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1172 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1173 } 1174 1175 /* Control parameters for ECHO replies. */ 1176 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1177 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1178 1179 /* Control parameter - ignore bogus broadcast responses? */ 1180 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1181 1182 /* 1183 * Configurable global rate limit. 1184 * 1185 * ratelimit defines tokens/packet consumed for dst->rate_token 1186 * bucket ratemask defines which icmp types are ratelimited by 1187 * setting it's bit position. 1188 * 1189 * default: 1190 * dest unreachable (3), source quench (4), 1191 * time exceeded (11), parameter problem (12) 1192 */ 1193 1194 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1195 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1196 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1197 1198 return 0; 1199 1200fail: 1201 for_each_possible_cpu(i) 1202 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1203 kfree(net->ipv4.icmp_sk); 1204 return err; 1205} 1206 1207static struct pernet_operations __net_initdata icmp_sk_ops = { 1208 .init = icmp_sk_init, 1209 .exit = icmp_sk_exit, 1210}; 1211 1212int __init icmp_init(void) 1213{ 1214 return register_pernet_subsys(&icmp_sk_ops); 1215} 1216