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 static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 237 int type, int code) 238 { 239 struct dst_entry *dst = &rt->dst; 240 bool rc = true; 241 242 if (type > NR_ICMP_TYPES) 243 goto out; 244 245 /* Don't limit PMTU discovery. */ 246 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 247 goto out; 248 249 /* No rate limit on loopback */ 250 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 251 goto out; 252 253 /* Limit if icmp type is enabled in ratemask. */ 254 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) { 255 if (!rt->peer) 256 rt_bind_peer(rt, 1); 257 rc = inet_peer_xrlim_allow(rt->peer, 258 net->ipv4.sysctl_icmp_ratelimit); 259 } 260 out: 261 return rc; 262 } 263 264 /* 265 * Maintain the counters used in the SNMP statistics for outgoing ICMP 266 */ 267 void icmp_out_count(struct net *net, unsigned char type) 268 { 269 ICMPMSGOUT_INC_STATS(net, type); 270 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 271 } 272 273 /* 274 * Checksum each fragment, and on the first include the headers and final 275 * checksum. 276 */ 277 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 278 struct sk_buff *skb) 279 { 280 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 281 __wsum csum; 282 283 csum = skb_copy_and_csum_bits(icmp_param->skb, 284 icmp_param->offset + offset, 285 to, len, 0); 286 287 skb->csum = csum_block_add(skb->csum, csum, odd); 288 if (icmp_pointers[icmp_param->data.icmph.type].error) 289 nf_ct_attach(skb, icmp_param->skb); 290 return 0; 291 } 292 293 static void icmp_push_reply(struct icmp_bxm *icmp_param, 294 struct ipcm_cookie *ipc, struct rtable **rt) 295 { 296 struct sock *sk; 297 struct sk_buff *skb; 298 299 sk = icmp_sk(dev_net((*rt)->dst.dev)); 300 if (ip_append_data(sk, icmp_glue_bits, icmp_param, 301 icmp_param->data_len+icmp_param->head_len, 302 icmp_param->head_len, 303 ipc, rt, MSG_DONTWAIT) < 0) { 304 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS); 305 ip_flush_pending_frames(sk); 306 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 307 struct icmphdr *icmph = icmp_hdr(skb); 308 __wsum csum = 0; 309 struct sk_buff *skb1; 310 311 skb_queue_walk(&sk->sk_write_queue, skb1) { 312 csum = csum_add(csum, skb1->csum); 313 } 314 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 315 (char *)icmph, 316 icmp_param->head_len, csum); 317 icmph->checksum = csum_fold(csum); 318 skb->ip_summed = CHECKSUM_NONE; 319 ip_push_pending_frames(sk); 320 } 321 } 322 323 /* 324 * Driving logic for building and sending ICMP messages. 325 */ 326 327 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 328 { 329 struct ipcm_cookie ipc; 330 struct rtable *rt = skb_rtable(skb); 331 struct net *net = dev_net(rt->dst.dev); 332 struct sock *sk; 333 struct inet_sock *inet; 334 __be32 daddr; 335 336 if (ip_options_echo(&icmp_param->replyopts, skb)) 337 return; 338 339 sk = icmp_xmit_lock(net); 340 if (sk == NULL) 341 return; 342 inet = inet_sk(sk); 343 344 icmp_param->data.icmph.checksum = 0; 345 346 inet->tos = ip_hdr(skb)->tos; 347 daddr = ipc.addr = rt->rt_src; 348 ipc.opt = NULL; 349 ipc.tx_flags = 0; 350 if (icmp_param->replyopts.optlen) { 351 ipc.opt = &icmp_param->replyopts; 352 if (ipc.opt->srr) 353 daddr = icmp_param->replyopts.faddr; 354 } 355 { 356 struct flowi4 fl4 = { 357 .daddr = daddr, 358 .saddr = rt->rt_spec_dst, 359 .flowi4_tos = RT_TOS(ip_hdr(skb)->tos), 360 .flowi4_proto = IPPROTO_ICMP, 361 }; 362 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 363 rt = ip_route_output_key(net, &fl4); 364 if (IS_ERR(rt)) 365 goto out_unlock; 366 } 367 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type, 368 icmp_param->data.icmph.code)) 369 icmp_push_reply(icmp_param, &ipc, &rt); 370 ip_rt_put(rt); 371 out_unlock: 372 icmp_xmit_unlock(sk); 373 } 374 375 static struct rtable *icmp_route_lookup(struct net *net, struct sk_buff *skb_in, 376 struct iphdr *iph, 377 __be32 saddr, u8 tos, 378 int type, int code, 379 struct icmp_bxm *param) 380 { 381 struct flowi4 fl4 = { 382 .daddr = (param->replyopts.srr ? 383 param->replyopts.faddr : iph->saddr), 384 .saddr = saddr, 385 .flowi4_tos = RT_TOS(tos), 386 .flowi4_proto = IPPROTO_ICMP, 387 .fl4_icmp_type = type, 388 .fl4_icmp_code = code, 389 }; 390 struct rtable *rt, *rt2; 391 int err; 392 393 security_skb_classify_flow(skb_in, flowi4_to_flowi(&fl4)); 394 rt = __ip_route_output_key(net, &fl4); 395 if (IS_ERR(rt)) 396 return rt; 397 398 /* No need to clone since we're just using its address. */ 399 rt2 = rt; 400 401 if (!fl4.saddr) 402 fl4.saddr = rt->rt_src; 403 404 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 405 flowi4_to_flowi(&fl4), NULL, 0); 406 if (!IS_ERR(rt)) { 407 if (rt != rt2) 408 return rt; 409 } else if (PTR_ERR(rt) == -EPERM) { 410 rt = NULL; 411 } else 412 return rt; 413 414 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4), AF_INET); 415 if (err) 416 goto relookup_failed; 417 418 if (inet_addr_type(net, fl4.saddr) == RTN_LOCAL) { 419 rt2 = __ip_route_output_key(net, &fl4); 420 if (IS_ERR(rt2)) 421 err = PTR_ERR(rt2); 422 } else { 423 struct flowi4 fl4_2 = {}; 424 unsigned long orefdst; 425 426 fl4_2.daddr = fl4.saddr; 427 rt2 = ip_route_output_key(net, &fl4_2); 428 if (IS_ERR(rt2)) { 429 err = PTR_ERR(rt2); 430 goto relookup_failed; 431 } 432 /* Ugh! */ 433 orefdst = skb_in->_skb_refdst; /* save old refdst */ 434 err = ip_route_input(skb_in, fl4.daddr, fl4.saddr, 435 RT_TOS(tos), rt2->dst.dev); 436 437 dst_release(&rt2->dst); 438 rt2 = skb_rtable(skb_in); 439 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 440 } 441 442 if (err) 443 goto relookup_failed; 444 445 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 446 flowi4_to_flowi(&fl4), NULL, 447 XFRM_LOOKUP_ICMP); 448 if (!IS_ERR(rt2)) { 449 dst_release(&rt->dst); 450 rt = rt2; 451 } else if (PTR_ERR(rt2) == -EPERM) { 452 if (rt) 453 dst_release(&rt->dst); 454 return rt2; 455 } else { 456 err = PTR_ERR(rt2); 457 goto relookup_failed; 458 } 459 return rt; 460 461 relookup_failed: 462 if (rt) 463 return rt; 464 return ERR_PTR(err); 465 } 466 467 /* 468 * Send an ICMP message in response to a situation 469 * 470 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 471 * MAY send more (we do). 472 * MUST NOT change this header information. 473 * MUST NOT reply to a multicast/broadcast IP address. 474 * MUST NOT reply to a multicast/broadcast MAC address. 475 * MUST reply to only the first fragment. 476 */ 477 478 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 479 { 480 struct iphdr *iph; 481 int room; 482 struct icmp_bxm icmp_param; 483 struct rtable *rt = skb_rtable(skb_in); 484 struct ipcm_cookie ipc; 485 __be32 saddr; 486 u8 tos; 487 struct net *net; 488 struct sock *sk; 489 490 if (!rt) 491 goto out; 492 net = dev_net(rt->dst.dev); 493 494 /* 495 * Find the original header. It is expected to be valid, of course. 496 * Check this, icmp_send is called from the most obscure devices 497 * sometimes. 498 */ 499 iph = ip_hdr(skb_in); 500 501 if ((u8 *)iph < skb_in->head || 502 (skb_in->network_header + sizeof(*iph)) > skb_in->tail) 503 goto out; 504 505 /* 506 * No replies to physical multicast/broadcast 507 */ 508 if (skb_in->pkt_type != PACKET_HOST) 509 goto out; 510 511 /* 512 * Now check at the protocol level 513 */ 514 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 515 goto out; 516 517 /* 518 * Only reply to fragment 0. We byte re-order the constant 519 * mask for efficiency. 520 */ 521 if (iph->frag_off & htons(IP_OFFSET)) 522 goto out; 523 524 /* 525 * If we send an ICMP error to an ICMP error a mess would result.. 526 */ 527 if (icmp_pointers[type].error) { 528 /* 529 * We are an error, check if we are replying to an 530 * ICMP error 531 */ 532 if (iph->protocol == IPPROTO_ICMP) { 533 u8 _inner_type, *itp; 534 535 itp = skb_header_pointer(skb_in, 536 skb_network_header(skb_in) + 537 (iph->ihl << 2) + 538 offsetof(struct icmphdr, 539 type) - 540 skb_in->data, 541 sizeof(_inner_type), 542 &_inner_type); 543 if (itp == NULL) 544 goto out; 545 546 /* 547 * Assume any unknown ICMP type is an error. This 548 * isn't specified by the RFC, but think about it.. 549 */ 550 if (*itp > NR_ICMP_TYPES || 551 icmp_pointers[*itp].error) 552 goto out; 553 } 554 } 555 556 sk = icmp_xmit_lock(net); 557 if (sk == NULL) 558 return; 559 560 /* 561 * Construct source address and options. 562 */ 563 564 saddr = iph->daddr; 565 if (!(rt->rt_flags & RTCF_LOCAL)) { 566 struct net_device *dev = NULL; 567 568 rcu_read_lock(); 569 if (rt_is_input_route(rt) && 570 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 571 dev = dev_get_by_index_rcu(net, rt->rt_iif); 572 573 if (dev) 574 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 575 else 576 saddr = 0; 577 rcu_read_unlock(); 578 } 579 580 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 581 IPTOS_PREC_INTERNETCONTROL) : 582 iph->tos; 583 584 if (ip_options_echo(&icmp_param.replyopts, skb_in)) 585 goto out_unlock; 586 587 588 /* 589 * Prepare data for ICMP header. 590 */ 591 592 icmp_param.data.icmph.type = type; 593 icmp_param.data.icmph.code = code; 594 icmp_param.data.icmph.un.gateway = info; 595 icmp_param.data.icmph.checksum = 0; 596 icmp_param.skb = skb_in; 597 icmp_param.offset = skb_network_offset(skb_in); 598 inet_sk(sk)->tos = tos; 599 ipc.addr = iph->saddr; 600 ipc.opt = &icmp_param.replyopts; 601 ipc.tx_flags = 0; 602 603 rt = icmp_route_lookup(net, skb_in, iph, saddr, tos, 604 type, code, &icmp_param); 605 if (IS_ERR(rt)) 606 goto out_unlock; 607 608 if (!icmpv4_xrlim_allow(net, rt, type, code)) 609 goto ende; 610 611 /* RFC says return as much as we can without exceeding 576 bytes. */ 612 613 room = dst_mtu(&rt->dst); 614 if (room > 576) 615 room = 576; 616 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; 617 room -= sizeof(struct icmphdr); 618 619 icmp_param.data_len = skb_in->len - icmp_param.offset; 620 if (icmp_param.data_len > room) 621 icmp_param.data_len = room; 622 icmp_param.head_len = sizeof(struct icmphdr); 623 624 icmp_push_reply(&icmp_param, &ipc, &rt); 625 ende: 626 ip_rt_put(rt); 627 out_unlock: 628 icmp_xmit_unlock(sk); 629 out:; 630 } 631 EXPORT_SYMBOL(icmp_send); 632 633 634 /* 635 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. 636 */ 637 638 static void icmp_unreach(struct sk_buff *skb) 639 { 640 struct iphdr *iph; 641 struct icmphdr *icmph; 642 int hash, protocol; 643 const struct net_protocol *ipprot; 644 u32 info = 0; 645 struct net *net; 646 647 net = dev_net(skb_dst(skb)->dev); 648 649 /* 650 * Incomplete header ? 651 * Only checks for the IP header, there should be an 652 * additional check for longer headers in upper levels. 653 */ 654 655 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 656 goto out_err; 657 658 icmph = icmp_hdr(skb); 659 iph = (struct iphdr *)skb->data; 660 661 if (iph->ihl < 5) /* Mangled header, drop. */ 662 goto out_err; 663 664 if (icmph->type == ICMP_DEST_UNREACH) { 665 switch (icmph->code & 15) { 666 case ICMP_NET_UNREACH: 667 case ICMP_HOST_UNREACH: 668 case ICMP_PROT_UNREACH: 669 case ICMP_PORT_UNREACH: 670 break; 671 case ICMP_FRAG_NEEDED: 672 if (ipv4_config.no_pmtu_disc) { 673 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n", 674 &iph->daddr); 675 } else { 676 info = ip_rt_frag_needed(net, iph, 677 ntohs(icmph->un.frag.mtu), 678 skb->dev); 679 if (!info) 680 goto out; 681 } 682 break; 683 case ICMP_SR_FAILED: 684 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n", 685 &iph->daddr); 686 break; 687 default: 688 break; 689 } 690 if (icmph->code > NR_ICMP_UNREACH) 691 goto out; 692 } else if (icmph->type == ICMP_PARAMETERPROB) 693 info = ntohl(icmph->un.gateway) >> 24; 694 695 /* 696 * Throw it at our lower layers 697 * 698 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 699 * header. 700 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 701 * transport layer. 702 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 703 * transport layer. 704 */ 705 706 /* 707 * Check the other end isn't violating RFC 1122. Some routers send 708 * bogus responses to broadcast frames. If you see this message 709 * first check your netmask matches at both ends, if it does then 710 * get the other vendor to fix their kit. 711 */ 712 713 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 714 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { 715 if (net_ratelimit()) 716 printk(KERN_WARNING "%pI4 sent an invalid ICMP " 717 "type %u, code %u " 718 "error to a broadcast: %pI4 on %s\n", 719 &ip_hdr(skb)->saddr, 720 icmph->type, icmph->code, 721 &iph->daddr, 722 skb->dev->name); 723 goto out; 724 } 725 726 /* Checkin full IP header plus 8 bytes of protocol to 727 * avoid additional coding at protocol handlers. 728 */ 729 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 730 goto out; 731 732 iph = (struct iphdr *)skb->data; 733 protocol = iph->protocol; 734 735 /* 736 * Deliver ICMP message to raw sockets. Pretty useless feature? 737 */ 738 raw_icmp_error(skb, protocol, info); 739 740 hash = protocol & (MAX_INET_PROTOS - 1); 741 rcu_read_lock(); 742 ipprot = rcu_dereference(inet_protos[hash]); 743 if (ipprot && ipprot->err_handler) 744 ipprot->err_handler(skb, info); 745 rcu_read_unlock(); 746 747 out: 748 return; 749 out_err: 750 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 751 goto out; 752 } 753 754 755 /* 756 * Handle ICMP_REDIRECT. 757 */ 758 759 static void icmp_redirect(struct sk_buff *skb) 760 { 761 struct iphdr *iph; 762 763 if (skb->len < sizeof(struct iphdr)) 764 goto out_err; 765 766 /* 767 * Get the copied header of the packet that caused the redirect 768 */ 769 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 770 goto out; 771 772 iph = (struct iphdr *)skb->data; 773 774 switch (icmp_hdr(skb)->code & 7) { 775 case ICMP_REDIR_NET: 776 case ICMP_REDIR_NETTOS: 777 /* 778 * As per RFC recommendations now handle it as a host redirect. 779 */ 780 case ICMP_REDIR_HOST: 781 case ICMP_REDIR_HOSTTOS: 782 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, 783 icmp_hdr(skb)->un.gateway, 784 iph->saddr, skb->dev); 785 break; 786 } 787 out: 788 return; 789 out_err: 790 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 791 goto out; 792 } 793 794 /* 795 * Handle ICMP_ECHO ("ping") requests. 796 * 797 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 798 * requests. 799 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 800 * included in the reply. 801 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 802 * echo requests, MUST have default=NOT. 803 * See also WRT handling of options once they are done and working. 804 */ 805 806 static void icmp_echo(struct sk_buff *skb) 807 { 808 struct net *net; 809 810 net = dev_net(skb_dst(skb)->dev); 811 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 812 struct icmp_bxm icmp_param; 813 814 icmp_param.data.icmph = *icmp_hdr(skb); 815 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 816 icmp_param.skb = skb; 817 icmp_param.offset = 0; 818 icmp_param.data_len = skb->len; 819 icmp_param.head_len = sizeof(struct icmphdr); 820 icmp_reply(&icmp_param, skb); 821 } 822 } 823 824 /* 825 * Handle ICMP Timestamp requests. 826 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 827 * SHOULD be in the kernel for minimum random latency. 828 * MUST be accurate to a few minutes. 829 * MUST be updated at least at 15Hz. 830 */ 831 static void icmp_timestamp(struct sk_buff *skb) 832 { 833 struct timespec tv; 834 struct icmp_bxm icmp_param; 835 /* 836 * Too short. 837 */ 838 if (skb->len < 4) 839 goto out_err; 840 841 /* 842 * Fill in the current time as ms since midnight UT: 843 */ 844 getnstimeofday(&tv); 845 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 846 tv.tv_nsec / NSEC_PER_MSEC); 847 icmp_param.data.times[2] = icmp_param.data.times[1]; 848 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 849 BUG(); 850 icmp_param.data.icmph = *icmp_hdr(skb); 851 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 852 icmp_param.data.icmph.code = 0; 853 icmp_param.skb = skb; 854 icmp_param.offset = 0; 855 icmp_param.data_len = 0; 856 icmp_param.head_len = sizeof(struct icmphdr) + 12; 857 icmp_reply(&icmp_param, skb); 858 out: 859 return; 860 out_err: 861 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 862 goto out; 863 } 864 865 866 /* 867 * Handle ICMP_ADDRESS_MASK requests. (RFC950) 868 * 869 * RFC1122 (3.2.2.9). A host MUST only send replies to 870 * ADDRESS_MASK requests if it's been configured as an address mask 871 * agent. Receiving a request doesn't constitute implicit permission to 872 * act as one. Of course, implementing this correctly requires (SHOULD) 873 * a way to turn the functionality on and off. Another one for sysctl(), 874 * I guess. -- MS 875 * 876 * RFC1812 (4.3.3.9). A router MUST implement it. 877 * A router SHOULD have switch turning it on/off. 878 * This switch MUST be ON by default. 879 * 880 * Gratuitous replies, zero-source replies are not implemented, 881 * that complies with RFC. DO NOT implement them!!! All the idea 882 * of broadcast addrmask replies as specified in RFC950 is broken. 883 * The problem is that it is not uncommon to have several prefixes 884 * on one physical interface. Moreover, addrmask agent can even be 885 * not aware of existing another prefixes. 886 * If source is zero, addrmask agent cannot choose correct prefix. 887 * Gratuitous mask announcements suffer from the same problem. 888 * RFC1812 explains it, but still allows to use ADDRMASK, 889 * that is pretty silly. --ANK 890 * 891 * All these rules are so bizarre, that I removed kernel addrmask 892 * support at all. It is wrong, it is obsolete, nobody uses it in 893 * any case. --ANK 894 * 895 * Furthermore you can do it with a usermode address agent program 896 * anyway... 897 */ 898 899 static void icmp_address(struct sk_buff *skb) 900 { 901 #if 0 902 if (net_ratelimit()) 903 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n"); 904 #endif 905 } 906 907 /* 908 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain 909 * loudly if an inconsistency is found. 910 * called with rcu_read_lock() 911 */ 912 913 static void icmp_address_reply(struct sk_buff *skb) 914 { 915 struct rtable *rt = skb_rtable(skb); 916 struct net_device *dev = skb->dev; 917 struct in_device *in_dev; 918 struct in_ifaddr *ifa; 919 920 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) 921 return; 922 923 in_dev = __in_dev_get_rcu(dev); 924 if (!in_dev) 925 return; 926 927 if (in_dev->ifa_list && 928 IN_DEV_LOG_MARTIANS(in_dev) && 929 IN_DEV_FORWARD(in_dev)) { 930 __be32 _mask, *mp; 931 932 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); 933 BUG_ON(mp == NULL); 934 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { 935 if (*mp == ifa->ifa_mask && 936 inet_ifa_match(rt->rt_src, ifa)) 937 break; 938 } 939 if (!ifa && net_ratelimit()) { 940 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n", 941 mp, dev->name, &rt->rt_src); 942 } 943 } 944 } 945 946 static void icmp_discard(struct sk_buff *skb) 947 { 948 } 949 950 /* 951 * Deal with incoming ICMP packets. 952 */ 953 int icmp_rcv(struct sk_buff *skb) 954 { 955 struct icmphdr *icmph; 956 struct rtable *rt = skb_rtable(skb); 957 struct net *net = dev_net(rt->dst.dev); 958 959 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 960 struct sec_path *sp = skb_sec_path(skb); 961 int nh; 962 963 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 964 XFRM_STATE_ICMP)) 965 goto drop; 966 967 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 968 goto drop; 969 970 nh = skb_network_offset(skb); 971 skb_set_network_header(skb, sizeof(*icmph)); 972 973 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 974 goto drop; 975 976 skb_set_network_header(skb, nh); 977 } 978 979 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 980 981 switch (skb->ip_summed) { 982 case CHECKSUM_COMPLETE: 983 if (!csum_fold(skb->csum)) 984 break; 985 /* fall through */ 986 case CHECKSUM_NONE: 987 skb->csum = 0; 988 if (__skb_checksum_complete(skb)) 989 goto error; 990 } 991 992 if (!pskb_pull(skb, sizeof(*icmph))) 993 goto error; 994 995 icmph = icmp_hdr(skb); 996 997 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 998 /* 999 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1000 * 1001 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1002 * discarded. 1003 */ 1004 if (icmph->type > NR_ICMP_TYPES) 1005 goto error; 1006 1007 1008 /* 1009 * Parse the ICMP message 1010 */ 1011 1012 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1013 /* 1014 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1015 * silently ignored (we let user decide with a sysctl). 1016 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1017 * discarded if to broadcast/multicast. 1018 */ 1019 if ((icmph->type == ICMP_ECHO || 1020 icmph->type == ICMP_TIMESTAMP) && 1021 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1022 goto error; 1023 } 1024 if (icmph->type != ICMP_ECHO && 1025 icmph->type != ICMP_TIMESTAMP && 1026 icmph->type != ICMP_ADDRESS && 1027 icmph->type != ICMP_ADDRESSREPLY) { 1028 goto error; 1029 } 1030 } 1031 1032 icmp_pointers[icmph->type].handler(skb); 1033 1034 drop: 1035 kfree_skb(skb); 1036 return 0; 1037 error: 1038 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 1039 goto drop; 1040 } 1041 1042 /* 1043 * This table is the definition of how we handle ICMP. 1044 */ 1045 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1046 [ICMP_ECHOREPLY] = { 1047 .handler = icmp_discard, 1048 }, 1049 [1] = { 1050 .handler = icmp_discard, 1051 .error = 1, 1052 }, 1053 [2] = { 1054 .handler = icmp_discard, 1055 .error = 1, 1056 }, 1057 [ICMP_DEST_UNREACH] = { 1058 .handler = icmp_unreach, 1059 .error = 1, 1060 }, 1061 [ICMP_SOURCE_QUENCH] = { 1062 .handler = icmp_unreach, 1063 .error = 1, 1064 }, 1065 [ICMP_REDIRECT] = { 1066 .handler = icmp_redirect, 1067 .error = 1, 1068 }, 1069 [6] = { 1070 .handler = icmp_discard, 1071 .error = 1, 1072 }, 1073 [7] = { 1074 .handler = icmp_discard, 1075 .error = 1, 1076 }, 1077 [ICMP_ECHO] = { 1078 .handler = icmp_echo, 1079 }, 1080 [9] = { 1081 .handler = icmp_discard, 1082 .error = 1, 1083 }, 1084 [10] = { 1085 .handler = icmp_discard, 1086 .error = 1, 1087 }, 1088 [ICMP_TIME_EXCEEDED] = { 1089 .handler = icmp_unreach, 1090 .error = 1, 1091 }, 1092 [ICMP_PARAMETERPROB] = { 1093 .handler = icmp_unreach, 1094 .error = 1, 1095 }, 1096 [ICMP_TIMESTAMP] = { 1097 .handler = icmp_timestamp, 1098 }, 1099 [ICMP_TIMESTAMPREPLY] = { 1100 .handler = icmp_discard, 1101 }, 1102 [ICMP_INFO_REQUEST] = { 1103 .handler = icmp_discard, 1104 }, 1105 [ICMP_INFO_REPLY] = { 1106 .handler = icmp_discard, 1107 }, 1108 [ICMP_ADDRESS] = { 1109 .handler = icmp_address, 1110 }, 1111 [ICMP_ADDRESSREPLY] = { 1112 .handler = icmp_address_reply, 1113 }, 1114 }; 1115 1116 static void __net_exit icmp_sk_exit(struct net *net) 1117 { 1118 int i; 1119 1120 for_each_possible_cpu(i) 1121 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1122 kfree(net->ipv4.icmp_sk); 1123 net->ipv4.icmp_sk = NULL; 1124 } 1125 1126 static int __net_init icmp_sk_init(struct net *net) 1127 { 1128 int i, err; 1129 1130 net->ipv4.icmp_sk = 1131 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); 1132 if (net->ipv4.icmp_sk == NULL) 1133 return -ENOMEM; 1134 1135 for_each_possible_cpu(i) { 1136 struct sock *sk; 1137 1138 err = inet_ctl_sock_create(&sk, PF_INET, 1139 SOCK_RAW, IPPROTO_ICMP, net); 1140 if (err < 0) 1141 goto fail; 1142 1143 net->ipv4.icmp_sk[i] = sk; 1144 1145 /* Enough space for 2 64K ICMP packets, including 1146 * sk_buff struct overhead. 1147 */ 1148 sk->sk_sndbuf = 1149 (2 * ((64 * 1024) + sizeof(struct sk_buff))); 1150 1151 /* 1152 * Speedup sock_wfree() 1153 */ 1154 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1155 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1156 } 1157 1158 /* Control parameters for ECHO replies. */ 1159 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1160 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1161 1162 /* Control parameter - ignore bogus broadcast responses? */ 1163 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1164 1165 /* 1166 * Configurable global rate limit. 1167 * 1168 * ratelimit defines tokens/packet consumed for dst->rate_token 1169 * bucket ratemask defines which icmp types are ratelimited by 1170 * setting it's bit position. 1171 * 1172 * default: 1173 * dest unreachable (3), source quench (4), 1174 * time exceeded (11), parameter problem (12) 1175 */ 1176 1177 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1178 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1179 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1180 1181 return 0; 1182 1183 fail: 1184 for_each_possible_cpu(i) 1185 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1186 kfree(net->ipv4.icmp_sk); 1187 return err; 1188 } 1189 1190 static struct pernet_operations __net_initdata icmp_sk_ops = { 1191 .init = icmp_sk_init, 1192 .exit = icmp_sk_exit, 1193 }; 1194 1195 int __init icmp_init(void) 1196 { 1197 return register_pernet_subsys(&icmp_sk_ops); 1198 } 1199