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 */ 100 101 struct 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'. */ 117 118 const 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 }; 184 EXPORT_SYMBOL(icmp_err_convert); 185 186 /* 187 * ICMP control array. This specifies what to do with each ICMP. 188 */ 189 190 struct icmp_control { 191 void (*handler)(struct sk_buff *skb); 192 short error; /* This ICMP is classed as an error message */ 193 }; 194 195 static 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 */ 204 static struct sock *icmp_sk(struct net *net) 205 { 206 return net->ipv4.icmp_sk[smp_processor_id()]; 207 } 208 209 static 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 } 226 227 static 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 6 254 int 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 } 271 EXPORT_SYMBOL(xrlim_allow); 272 273 static 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); 293 out: 294 return rc; 295 } 296 297 /* 298 * Maintain the counters used in the SNMP statistics for outgoing ICMP 299 */ 300 void 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 */ 310 static 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 } 325 326 static 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 */ 359 360 static 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.tx_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 = { .fl4_dst= daddr, 390 .fl4_src = rt->rt_spec_dst, 391 .fl4_tos = RT_TOS(ip_hdr(skb)->tos), 392 .proto = IPPROTO_ICMP }; 393 security_skb_classify_flow(skb, &fl); 394 if (ip_route_output_key(net, &rt, &fl)) 395 goto out_unlock; 396 } 397 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type, 398 icmp_param->data.icmph.code)) 399 icmp_push_reply(icmp_param, &ipc, &rt); 400 ip_rt_put(rt); 401 out_unlock: 402 icmp_xmit_unlock(sk); 403 } 404 405 406 /* 407 * Send an ICMP message in response to a situation 408 * 409 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 410 * MAY send more (we do). 411 * MUST NOT change this header information. 412 * MUST NOT reply to a multicast/broadcast IP address. 413 * MUST NOT reply to a multicast/broadcast MAC address. 414 * MUST reply to only the first fragment. 415 */ 416 417 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 418 { 419 struct iphdr *iph; 420 int room; 421 struct icmp_bxm icmp_param; 422 struct rtable *rt = skb_rtable(skb_in); 423 struct ipcm_cookie ipc; 424 __be32 saddr; 425 u8 tos; 426 struct net *net; 427 struct sock *sk; 428 429 if (!rt) 430 goto out; 431 net = dev_net(rt->dst.dev); 432 433 /* 434 * Find the original header. It is expected to be valid, of course. 435 * Check this, icmp_send is called from the most obscure devices 436 * sometimes. 437 */ 438 iph = ip_hdr(skb_in); 439 440 if ((u8 *)iph < skb_in->head || 441 (skb_in->network_header + sizeof(*iph)) > skb_in->tail) 442 goto out; 443 444 /* 445 * No replies to physical multicast/broadcast 446 */ 447 if (skb_in->pkt_type != PACKET_HOST) 448 goto out; 449 450 /* 451 * Now check at the protocol level 452 */ 453 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 454 goto out; 455 456 /* 457 * Only reply to fragment 0. We byte re-order the constant 458 * mask for efficiency. 459 */ 460 if (iph->frag_off & htons(IP_OFFSET)) 461 goto out; 462 463 /* 464 * If we send an ICMP error to an ICMP error a mess would result.. 465 */ 466 if (icmp_pointers[type].error) { 467 /* 468 * We are an error, check if we are replying to an 469 * ICMP error 470 */ 471 if (iph->protocol == IPPROTO_ICMP) { 472 u8 _inner_type, *itp; 473 474 itp = skb_header_pointer(skb_in, 475 skb_network_header(skb_in) + 476 (iph->ihl << 2) + 477 offsetof(struct icmphdr, 478 type) - 479 skb_in->data, 480 sizeof(_inner_type), 481 &_inner_type); 482 if (itp == NULL) 483 goto out; 484 485 /* 486 * Assume any unknown ICMP type is an error. This 487 * isn't specified by the RFC, but think about it.. 488 */ 489 if (*itp > NR_ICMP_TYPES || 490 icmp_pointers[*itp].error) 491 goto out; 492 } 493 } 494 495 sk = icmp_xmit_lock(net); 496 if (sk == NULL) 497 return; 498 499 /* 500 * Construct source address and options. 501 */ 502 503 saddr = iph->daddr; 504 if (!(rt->rt_flags & RTCF_LOCAL)) { 505 struct net_device *dev = NULL; 506 507 rcu_read_lock(); 508 if (rt_is_input_route(rt) && 509 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 510 dev = dev_get_by_index_rcu(net, rt->fl.iif); 511 512 if (dev) 513 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 514 else 515 saddr = 0; 516 rcu_read_unlock(); 517 } 518 519 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 520 IPTOS_PREC_INTERNETCONTROL) : 521 iph->tos; 522 523 if (ip_options_echo(&icmp_param.replyopts, skb_in)) 524 goto out_unlock; 525 526 527 /* 528 * Prepare data for ICMP header. 529 */ 530 531 icmp_param.data.icmph.type = type; 532 icmp_param.data.icmph.code = code; 533 icmp_param.data.icmph.un.gateway = info; 534 icmp_param.data.icmph.checksum = 0; 535 icmp_param.skb = skb_in; 536 icmp_param.offset = skb_network_offset(skb_in); 537 inet_sk(sk)->tos = tos; 538 ipc.addr = iph->saddr; 539 ipc.opt = &icmp_param.replyopts; 540 ipc.tx_flags = 0; 541 542 { 543 struct flowi fl = { 544 .fl4_dst = icmp_param.replyopts.srr ? 545 icmp_param.replyopts.faddr : iph->saddr, 546 .fl4_src = saddr, 547 .fl4_tos = RT_TOS(tos), 548 .proto = IPPROTO_ICMP, 549 .fl_icmp_type = type, 550 .fl_icmp_code = code, 551 }; 552 int err; 553 struct rtable *rt2; 554 555 security_skb_classify_flow(skb_in, &fl); 556 if (__ip_route_output_key(net, &rt, &fl)) 557 goto out_unlock; 558 559 /* No need to clone since we're just using its address. */ 560 rt2 = rt; 561 562 if (!fl.nl_u.ip4_u.saddr) 563 fl.nl_u.ip4_u.saddr = rt->rt_src; 564 565 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0); 566 switch (err) { 567 case 0: 568 if (rt != rt2) 569 goto route_done; 570 break; 571 case -EPERM: 572 rt = NULL; 573 break; 574 default: 575 goto out_unlock; 576 } 577 578 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET)) 579 goto relookup_failed; 580 581 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL) 582 err = __ip_route_output_key(net, &rt2, &fl); 583 else { 584 struct flowi fl2 = {}; 585 unsigned long orefdst; 586 587 fl2.fl4_dst = fl.fl4_src; 588 if (ip_route_output_key(net, &rt2, &fl2)) 589 goto relookup_failed; 590 591 /* Ugh! */ 592 orefdst = skb_in->_skb_refdst; /* save old refdst */ 593 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src, 594 RT_TOS(tos), rt2->dst.dev); 595 596 dst_release(&rt2->dst); 597 rt2 = skb_rtable(skb_in); 598 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 599 } 600 601 if (err) 602 goto relookup_failed; 603 604 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL, 605 XFRM_LOOKUP_ICMP); 606 switch (err) { 607 case 0: 608 dst_release(&rt->dst); 609 rt = rt2; 610 break; 611 case -EPERM: 612 goto ende; 613 default: 614 relookup_failed: 615 if (!rt) 616 goto out_unlock; 617 break; 618 } 619 } 620 621 route_done: 622 if (!icmpv4_xrlim_allow(net, rt, type, code)) 623 goto ende; 624 625 /* RFC says return as much as we can without exceeding 576 bytes. */ 626 627 room = dst_mtu(&rt->dst); 628 if (room > 576) 629 room = 576; 630 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; 631 room -= sizeof(struct icmphdr); 632 633 icmp_param.data_len = skb_in->len - icmp_param.offset; 634 if (icmp_param.data_len > room) 635 icmp_param.data_len = room; 636 icmp_param.head_len = sizeof(struct icmphdr); 637 638 icmp_push_reply(&icmp_param, &ipc, &rt); 639 ende: 640 ip_rt_put(rt); 641 out_unlock: 642 icmp_xmit_unlock(sk); 643 out:; 644 } 645 EXPORT_SYMBOL(icmp_send); 646 647 648 /* 649 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. 650 */ 651 652 static void icmp_unreach(struct sk_buff *skb) 653 { 654 struct iphdr *iph; 655 struct icmphdr *icmph; 656 int hash, protocol; 657 const struct net_protocol *ipprot; 658 u32 info = 0; 659 struct net *net; 660 661 net = dev_net(skb_dst(skb)->dev); 662 663 /* 664 * Incomplete header ? 665 * Only checks for the IP header, there should be an 666 * additional check for longer headers in upper levels. 667 */ 668 669 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 670 goto out_err; 671 672 icmph = icmp_hdr(skb); 673 iph = (struct iphdr *)skb->data; 674 675 if (iph->ihl < 5) /* Mangled header, drop. */ 676 goto out_err; 677 678 if (icmph->type == ICMP_DEST_UNREACH) { 679 switch (icmph->code & 15) { 680 case ICMP_NET_UNREACH: 681 case ICMP_HOST_UNREACH: 682 case ICMP_PROT_UNREACH: 683 case ICMP_PORT_UNREACH: 684 break; 685 case ICMP_FRAG_NEEDED: 686 if (ipv4_config.no_pmtu_disc) { 687 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n", 688 &iph->daddr); 689 } else { 690 info = ip_rt_frag_needed(net, iph, 691 ntohs(icmph->un.frag.mtu), 692 skb->dev); 693 if (!info) 694 goto out; 695 } 696 break; 697 case ICMP_SR_FAILED: 698 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n", 699 &iph->daddr); 700 break; 701 default: 702 break; 703 } 704 if (icmph->code > NR_ICMP_UNREACH) 705 goto out; 706 } else if (icmph->type == ICMP_PARAMETERPROB) 707 info = ntohl(icmph->un.gateway) >> 24; 708 709 /* 710 * Throw it at our lower layers 711 * 712 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 713 * header. 714 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 715 * transport layer. 716 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 717 * transport layer. 718 */ 719 720 /* 721 * Check the other end isnt violating RFC 1122. Some routers send 722 * bogus responses to broadcast frames. If you see this message 723 * first check your netmask matches at both ends, if it does then 724 * get the other vendor to fix their kit. 725 */ 726 727 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 728 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { 729 if (net_ratelimit()) 730 printk(KERN_WARNING "%pI4 sent an invalid ICMP " 731 "type %u, code %u " 732 "error to a broadcast: %pI4 on %s\n", 733 &ip_hdr(skb)->saddr, 734 icmph->type, icmph->code, 735 &iph->daddr, 736 skb->dev->name); 737 goto out; 738 } 739 740 /* Checkin full IP header plus 8 bytes of protocol to 741 * avoid additional coding at protocol handlers. 742 */ 743 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 744 goto out; 745 746 iph = (struct iphdr *)skb->data; 747 protocol = iph->protocol; 748 749 /* 750 * Deliver ICMP message to raw sockets. Pretty useless feature? 751 */ 752 raw_icmp_error(skb, protocol, info); 753 754 hash = protocol & (MAX_INET_PROTOS - 1); 755 rcu_read_lock(); 756 ipprot = rcu_dereference(inet_protos[hash]); 757 if (ipprot && ipprot->err_handler) 758 ipprot->err_handler(skb, info); 759 rcu_read_unlock(); 760 761 out: 762 return; 763 out_err: 764 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 765 goto out; 766 } 767 768 769 /* 770 * Handle ICMP_REDIRECT. 771 */ 772 773 static void icmp_redirect(struct sk_buff *skb) 774 { 775 struct iphdr *iph; 776 777 if (skb->len < sizeof(struct iphdr)) 778 goto out_err; 779 780 /* 781 * Get the copied header of the packet that caused the redirect 782 */ 783 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 784 goto out; 785 786 iph = (struct iphdr *)skb->data; 787 788 switch (icmp_hdr(skb)->code & 7) { 789 case ICMP_REDIR_NET: 790 case ICMP_REDIR_NETTOS: 791 /* 792 * As per RFC recommendations now handle it as a host redirect. 793 */ 794 case ICMP_REDIR_HOST: 795 case ICMP_REDIR_HOSTTOS: 796 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, 797 icmp_hdr(skb)->un.gateway, 798 iph->saddr, skb->dev); 799 break; 800 } 801 out: 802 return; 803 out_err: 804 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 805 goto out; 806 } 807 808 /* 809 * Handle ICMP_ECHO ("ping") requests. 810 * 811 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 812 * requests. 813 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 814 * included in the reply. 815 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 816 * echo requests, MUST have default=NOT. 817 * See also WRT handling of options once they are done and working. 818 */ 819 820 static void icmp_echo(struct sk_buff *skb) 821 { 822 struct net *net; 823 824 net = dev_net(skb_dst(skb)->dev); 825 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 826 struct icmp_bxm icmp_param; 827 828 icmp_param.data.icmph = *icmp_hdr(skb); 829 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 830 icmp_param.skb = skb; 831 icmp_param.offset = 0; 832 icmp_param.data_len = skb->len; 833 icmp_param.head_len = sizeof(struct icmphdr); 834 icmp_reply(&icmp_param, skb); 835 } 836 } 837 838 /* 839 * Handle ICMP Timestamp requests. 840 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 841 * SHOULD be in the kernel for minimum random latency. 842 * MUST be accurate to a few minutes. 843 * MUST be updated at least at 15Hz. 844 */ 845 static void icmp_timestamp(struct sk_buff *skb) 846 { 847 struct timespec tv; 848 struct icmp_bxm icmp_param; 849 /* 850 * Too short. 851 */ 852 if (skb->len < 4) 853 goto out_err; 854 855 /* 856 * Fill in the current time as ms since midnight UT: 857 */ 858 getnstimeofday(&tv); 859 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 860 tv.tv_nsec / NSEC_PER_MSEC); 861 icmp_param.data.times[2] = icmp_param.data.times[1]; 862 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 863 BUG(); 864 icmp_param.data.icmph = *icmp_hdr(skb); 865 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 866 icmp_param.data.icmph.code = 0; 867 icmp_param.skb = skb; 868 icmp_param.offset = 0; 869 icmp_param.data_len = 0; 870 icmp_param.head_len = sizeof(struct icmphdr) + 12; 871 icmp_reply(&icmp_param, skb); 872 out: 873 return; 874 out_err: 875 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 876 goto out; 877 } 878 879 880 /* 881 * Handle ICMP_ADDRESS_MASK requests. (RFC950) 882 * 883 * RFC1122 (3.2.2.9). A host MUST only send replies to 884 * ADDRESS_MASK requests if it's been configured as an address mask 885 * agent. Receiving a request doesn't constitute implicit permission to 886 * act as one. Of course, implementing this correctly requires (SHOULD) 887 * a way to turn the functionality on and off. Another one for sysctl(), 888 * I guess. -- MS 889 * 890 * RFC1812 (4.3.3.9). A router MUST implement it. 891 * A router SHOULD have switch turning it on/off. 892 * This switch MUST be ON by default. 893 * 894 * Gratuitous replies, zero-source replies are not implemented, 895 * that complies with RFC. DO NOT implement them!!! All the idea 896 * of broadcast addrmask replies as specified in RFC950 is broken. 897 * The problem is that it is not uncommon to have several prefixes 898 * on one physical interface. Moreover, addrmask agent can even be 899 * not aware of existing another prefixes. 900 * If source is zero, addrmask agent cannot choose correct prefix. 901 * Gratuitous mask announcements suffer from the same problem. 902 * RFC1812 explains it, but still allows to use ADDRMASK, 903 * that is pretty silly. --ANK 904 * 905 * All these rules are so bizarre, that I removed kernel addrmask 906 * support at all. It is wrong, it is obsolete, nobody uses it in 907 * any case. --ANK 908 * 909 * Furthermore you can do it with a usermode address agent program 910 * anyway... 911 */ 912 913 static void icmp_address(struct sk_buff *skb) 914 { 915 #if 0 916 if (net_ratelimit()) 917 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n"); 918 #endif 919 } 920 921 /* 922 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain 923 * loudly if an inconsistency is found. 924 * called with rcu_read_lock() 925 */ 926 927 static void icmp_address_reply(struct sk_buff *skb) 928 { 929 struct rtable *rt = skb_rtable(skb); 930 struct net_device *dev = skb->dev; 931 struct in_device *in_dev; 932 struct in_ifaddr *ifa; 933 934 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) 935 return; 936 937 in_dev = __in_dev_get_rcu(dev); 938 if (!in_dev) 939 return; 940 941 if (in_dev->ifa_list && 942 IN_DEV_LOG_MARTIANS(in_dev) && 943 IN_DEV_FORWARD(in_dev)) { 944 __be32 _mask, *mp; 945 946 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); 947 BUG_ON(mp == NULL); 948 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { 949 if (*mp == ifa->ifa_mask && 950 inet_ifa_match(rt->rt_src, ifa)) 951 break; 952 } 953 if (!ifa && net_ratelimit()) { 954 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n", 955 mp, dev->name, &rt->rt_src); 956 } 957 } 958 } 959 960 static void icmp_discard(struct sk_buff *skb) 961 { 962 } 963 964 /* 965 * Deal with incoming ICMP packets. 966 */ 967 int icmp_rcv(struct sk_buff *skb) 968 { 969 struct icmphdr *icmph; 970 struct rtable *rt = skb_rtable(skb); 971 struct net *net = dev_net(rt->dst.dev); 972 973 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 974 struct sec_path *sp = skb_sec_path(skb); 975 int nh; 976 977 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 978 XFRM_STATE_ICMP)) 979 goto drop; 980 981 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 982 goto drop; 983 984 nh = skb_network_offset(skb); 985 skb_set_network_header(skb, sizeof(*icmph)); 986 987 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 988 goto drop; 989 990 skb_set_network_header(skb, nh); 991 } 992 993 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 994 995 switch (skb->ip_summed) { 996 case CHECKSUM_COMPLETE: 997 if (!csum_fold(skb->csum)) 998 break; 999 /* fall through */ 1000 case CHECKSUM_NONE: 1001 skb->csum = 0; 1002 if (__skb_checksum_complete(skb)) 1003 goto error; 1004 } 1005 1006 if (!pskb_pull(skb, sizeof(*icmph))) 1007 goto error; 1008 1009 icmph = icmp_hdr(skb); 1010 1011 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 1012 /* 1013 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1014 * 1015 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1016 * discarded. 1017 */ 1018 if (icmph->type > NR_ICMP_TYPES) 1019 goto error; 1020 1021 1022 /* 1023 * Parse the ICMP message 1024 */ 1025 1026 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1027 /* 1028 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1029 * silently ignored (we let user decide with a sysctl). 1030 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1031 * discarded if to broadcast/multicast. 1032 */ 1033 if ((icmph->type == ICMP_ECHO || 1034 icmph->type == ICMP_TIMESTAMP) && 1035 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1036 goto error; 1037 } 1038 if (icmph->type != ICMP_ECHO && 1039 icmph->type != ICMP_TIMESTAMP && 1040 icmph->type != ICMP_ADDRESS && 1041 icmph->type != ICMP_ADDRESSREPLY) { 1042 goto error; 1043 } 1044 } 1045 1046 icmp_pointers[icmph->type].handler(skb); 1047 1048 drop: 1049 kfree_skb(skb); 1050 return 0; 1051 error: 1052 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 1053 goto drop; 1054 } 1055 1056 /* 1057 * This table is the definition of how we handle ICMP. 1058 */ 1059 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1060 [ICMP_ECHOREPLY] = { 1061 .handler = icmp_discard, 1062 }, 1063 [1] = { 1064 .handler = icmp_discard, 1065 .error = 1, 1066 }, 1067 [2] = { 1068 .handler = icmp_discard, 1069 .error = 1, 1070 }, 1071 [ICMP_DEST_UNREACH] = { 1072 .handler = icmp_unreach, 1073 .error = 1, 1074 }, 1075 [ICMP_SOURCE_QUENCH] = { 1076 .handler = icmp_unreach, 1077 .error = 1, 1078 }, 1079 [ICMP_REDIRECT] = { 1080 .handler = icmp_redirect, 1081 .error = 1, 1082 }, 1083 [6] = { 1084 .handler = icmp_discard, 1085 .error = 1, 1086 }, 1087 [7] = { 1088 .handler = icmp_discard, 1089 .error = 1, 1090 }, 1091 [ICMP_ECHO] = { 1092 .handler = icmp_echo, 1093 }, 1094 [9] = { 1095 .handler = icmp_discard, 1096 .error = 1, 1097 }, 1098 [10] = { 1099 .handler = icmp_discard, 1100 .error = 1, 1101 }, 1102 [ICMP_TIME_EXCEEDED] = { 1103 .handler = icmp_unreach, 1104 .error = 1, 1105 }, 1106 [ICMP_PARAMETERPROB] = { 1107 .handler = icmp_unreach, 1108 .error = 1, 1109 }, 1110 [ICMP_TIMESTAMP] = { 1111 .handler = icmp_timestamp, 1112 }, 1113 [ICMP_TIMESTAMPREPLY] = { 1114 .handler = icmp_discard, 1115 }, 1116 [ICMP_INFO_REQUEST] = { 1117 .handler = icmp_discard, 1118 }, 1119 [ICMP_INFO_REPLY] = { 1120 .handler = icmp_discard, 1121 }, 1122 [ICMP_ADDRESS] = { 1123 .handler = icmp_address, 1124 }, 1125 [ICMP_ADDRESSREPLY] = { 1126 .handler = icmp_address_reply, 1127 }, 1128 }; 1129 1130 static void __net_exit icmp_sk_exit(struct net *net) 1131 { 1132 int i; 1133 1134 for_each_possible_cpu(i) 1135 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1136 kfree(net->ipv4.icmp_sk); 1137 net->ipv4.icmp_sk = NULL; 1138 } 1139 1140 static int __net_init icmp_sk_init(struct net *net) 1141 { 1142 int i, err; 1143 1144 net->ipv4.icmp_sk = 1145 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); 1146 if (net->ipv4.icmp_sk == NULL) 1147 return -ENOMEM; 1148 1149 for_each_possible_cpu(i) { 1150 struct sock *sk; 1151 1152 err = inet_ctl_sock_create(&sk, PF_INET, 1153 SOCK_RAW, IPPROTO_ICMP, net); 1154 if (err < 0) 1155 goto fail; 1156 1157 net->ipv4.icmp_sk[i] = sk; 1158 1159 /* Enough space for 2 64K ICMP packets, including 1160 * sk_buff struct overhead. 1161 */ 1162 sk->sk_sndbuf = 1163 (2 * ((64 * 1024) + sizeof(struct sk_buff))); 1164 1165 /* 1166 * Speedup sock_wfree() 1167 */ 1168 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1169 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1170 } 1171 1172 /* Control parameters for ECHO replies. */ 1173 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1174 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1175 1176 /* Control parameter - ignore bogus broadcast responses? */ 1177 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1178 1179 /* 1180 * Configurable global rate limit. 1181 * 1182 * ratelimit defines tokens/packet consumed for dst->rate_token 1183 * bucket ratemask defines which icmp types are ratelimited by 1184 * setting it's bit position. 1185 * 1186 * default: 1187 * dest unreachable (3), source quench (4), 1188 * time exceeded (11), parameter problem (12) 1189 */ 1190 1191 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1192 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1193 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1194 1195 return 0; 1196 1197 fail: 1198 for_each_possible_cpu(i) 1199 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1200 kfree(net->ipv4.icmp_sk); 1201 return err; 1202 } 1203 1204 static struct pernet_operations __net_initdata icmp_sk_ops = { 1205 .init = icmp_sk_init, 1206 .exit = icmp_sk_exit, 1207 }; 1208 1209 int __init icmp_init(void) 1210 { 1211 return register_pernet_subsys(&icmp_sk_ops); 1212 } 1213