1 /* 2 * NET3: Implementation of the ICMP protocol layer. 3 * 4 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * Some of the function names and the icmp unreach table for this 12 * module were derived from [icmp.c 1.0.11 06/02/93] by 13 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 14 * Other than that this module is a complete rewrite. 15 * 16 * Fixes: 17 * Clemens Fruhwirth : introduce global icmp rate limiting 18 * with icmp type masking ability instead 19 * of broken per type icmp timeouts. 20 * Mike Shaver : RFC1122 checks. 21 * Alan Cox : Multicast ping reply as self. 22 * Alan Cox : Fix atomicity lockup in ip_build_xmit 23 * call. 24 * Alan Cox : Added 216,128 byte paths to the MTU 25 * code. 26 * Martin Mares : RFC1812 checks. 27 * Martin Mares : Can be configured to follow redirects 28 * if acting as a router _without_ a 29 * routing protocol (RFC 1812). 30 * Martin Mares : Echo requests may be configured to 31 * be ignored (RFC 1812). 32 * Martin Mares : Limitation of ICMP error message 33 * transmit rate (RFC 1812). 34 * Martin Mares : TOS and Precedence set correctly 35 * (RFC 1812). 36 * Martin Mares : Now copying as much data from the 37 * original packet as we can without 38 * exceeding 576 bytes (RFC 1812). 39 * Willy Konynenberg : Transparent proxying support. 40 * Keith Owens : RFC1191 correction for 4.2BSD based 41 * path MTU bug. 42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 43 * valid (RFC 1812). 44 * Andi Kleen : Check all packet lengths properly 45 * and moved all kfree_skb() up to 46 * icmp_rcv. 47 * Andi Kleen : Move the rate limit bookkeeping 48 * into the dest entry and use a token 49 * bucket filter (thanks to ANK). Make 50 * the rates sysctl configurable. 51 * Yu Tianli : Fixed two ugly bugs in icmp_send 52 * - IP option length was accounted wrongly 53 * - ICMP header length was not accounted 54 * at all. 55 * Tristan Greaves : Added sysctl option to ignore bogus 56 * broadcast responses from broken routers. 57 * 58 * To Fix: 59 * 60 * - Should use skb_pull() instead of all the manual checking. 61 * This would also greatly simply some upper layer error handlers. --AK 62 * 63 */ 64 65 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 66 67 #include <linux/module.h> 68 #include <linux/types.h> 69 #include <linux/jiffies.h> 70 #include <linux/kernel.h> 71 #include <linux/fcntl.h> 72 #include <linux/socket.h> 73 #include <linux/in.h> 74 #include <linux/inet.h> 75 #include <linux/inetdevice.h> 76 #include <linux/netdevice.h> 77 #include <linux/string.h> 78 #include <linux/netfilter_ipv4.h> 79 #include <linux/slab.h> 80 #include <net/snmp.h> 81 #include <net/ip.h> 82 #include <net/route.h> 83 #include <net/protocol.h> 84 #include <net/icmp.h> 85 #include <net/tcp.h> 86 #include <net/udp.h> 87 #include <net/raw.h> 88 #include <net/ping.h> 89 #include <linux/skbuff.h> 90 #include <net/sock.h> 91 #include <linux/errno.h> 92 #include <linux/timer.h> 93 #include <linux/init.h> 94 #include <asm/uaccess.h> 95 #include <net/checksum.h> 96 #include <net/xfrm.h> 97 #include <net/inet_common.h> 98 #include <net/ip_fib.h> 99 100 /* 101 * Build xmit assembly blocks 102 */ 103 104 struct icmp_bxm { 105 struct sk_buff *skb; 106 int offset; 107 int data_len; 108 109 struct { 110 struct icmphdr icmph; 111 __be32 times[3]; 112 } data; 113 int head_len; 114 struct ip_options_data replyopts; 115 }; 116 117 /* An array of errno for error messages from dest unreach. */ 118 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 119 120 const struct icmp_err icmp_err_convert[] = { 121 { 122 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 123 .fatal = 0, 124 }, 125 { 126 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 127 .fatal = 0, 128 }, 129 { 130 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 131 .fatal = 1, 132 }, 133 { 134 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 135 .fatal = 1, 136 }, 137 { 138 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 139 .fatal = 0, 140 }, 141 { 142 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 143 .fatal = 0, 144 }, 145 { 146 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 147 .fatal = 1, 148 }, 149 { 150 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 151 .fatal = 1, 152 }, 153 { 154 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 155 .fatal = 1, 156 }, 157 { 158 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 159 .fatal = 1, 160 }, 161 { 162 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 163 .fatal = 1, 164 }, 165 { 166 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 167 .fatal = 0, 168 }, 169 { 170 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 171 .fatal = 0, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 175 .fatal = 1, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 179 .fatal = 1, 180 }, 181 { 182 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 183 .fatal = 1, 184 }, 185 }; 186 EXPORT_SYMBOL(icmp_err_convert); 187 188 /* 189 * ICMP control array. This specifies what to do with each ICMP. 190 */ 191 192 struct icmp_control { 193 void (*handler)(struct sk_buff *skb); 194 short error; /* This ICMP is classed as an error message */ 195 }; 196 197 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 198 199 /* 200 * The ICMP socket(s). This is the most convenient way to flow control 201 * our ICMP output as well as maintain a clean interface throughout 202 * all layers. All Socketless IP sends will soon be gone. 203 * 204 * On SMP we have one ICMP socket per-cpu. 205 */ 206 static struct sock *icmp_sk(struct net *net) 207 { 208 return net->ipv4.icmp_sk[smp_processor_id()]; 209 } 210 211 static inline struct sock *icmp_xmit_lock(struct net *net) 212 { 213 struct sock *sk; 214 215 local_bh_disable(); 216 217 sk = icmp_sk(net); 218 219 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 220 /* This can happen if the output path signals a 221 * dst_link_failure() for an outgoing ICMP packet. 222 */ 223 local_bh_enable(); 224 return NULL; 225 } 226 return sk; 227 } 228 229 static inline void icmp_xmit_unlock(struct sock *sk) 230 { 231 spin_unlock_bh(&sk->sk_lock.slock); 232 } 233 234 /* 235 * Send an ICMP frame. 236 */ 237 238 static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 239 struct flowi4 *fl4, int type, int code) 240 { 241 struct dst_entry *dst = &rt->dst; 242 bool rc = true; 243 244 if (type > NR_ICMP_TYPES) 245 goto out; 246 247 /* Don't limit PMTU discovery. */ 248 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 249 goto out; 250 251 /* No rate limit on loopback */ 252 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 253 goto out; 254 255 /* Limit if icmp type is enabled in ratemask. */ 256 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) { 257 struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1); 258 rc = inet_peer_xrlim_allow(peer, 259 net->ipv4.sysctl_icmp_ratelimit); 260 if (peer) 261 inet_putpeer(peer); 262 } 263 out: 264 return rc; 265 } 266 267 /* 268 * Maintain the counters used in the SNMP statistics for outgoing ICMP 269 */ 270 void icmp_out_count(struct net *net, unsigned char type) 271 { 272 ICMPMSGOUT_INC_STATS(net, type); 273 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 274 } 275 276 /* 277 * Checksum each fragment, and on the first include the headers and final 278 * checksum. 279 */ 280 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 281 struct sk_buff *skb) 282 { 283 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 284 __wsum csum; 285 286 csum = skb_copy_and_csum_bits(icmp_param->skb, 287 icmp_param->offset + offset, 288 to, len, 0); 289 290 skb->csum = csum_block_add(skb->csum, csum, odd); 291 if (icmp_pointers[icmp_param->data.icmph.type].error) 292 nf_ct_attach(skb, icmp_param->skb); 293 return 0; 294 } 295 296 static void icmp_push_reply(struct icmp_bxm *icmp_param, 297 struct flowi4 *fl4, 298 struct ipcm_cookie *ipc, struct rtable **rt) 299 { 300 struct sock *sk; 301 struct sk_buff *skb; 302 303 sk = icmp_sk(dev_net((*rt)->dst.dev)); 304 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 305 icmp_param->data_len+icmp_param->head_len, 306 icmp_param->head_len, 307 ipc, rt, MSG_DONTWAIT) < 0) { 308 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS); 309 ip_flush_pending_frames(sk); 310 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 311 struct icmphdr *icmph = icmp_hdr(skb); 312 __wsum csum = 0; 313 struct sk_buff *skb1; 314 315 skb_queue_walk(&sk->sk_write_queue, skb1) { 316 csum = csum_add(csum, skb1->csum); 317 } 318 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 319 (char *)icmph, 320 icmp_param->head_len, csum); 321 icmph->checksum = csum_fold(csum); 322 skb->ip_summed = CHECKSUM_NONE; 323 ip_push_pending_frames(sk, fl4); 324 } 325 } 326 327 /* 328 * Driving logic for building and sending ICMP messages. 329 */ 330 331 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 332 { 333 struct ipcm_cookie ipc; 334 struct rtable *rt = skb_rtable(skb); 335 struct net *net = dev_net(rt->dst.dev); 336 struct flowi4 fl4; 337 struct sock *sk; 338 struct inet_sock *inet; 339 __be32 daddr, saddr; 340 341 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb)) 342 return; 343 344 sk = icmp_xmit_lock(net); 345 if (sk == NULL) 346 return; 347 inet = inet_sk(sk); 348 349 icmp_param->data.icmph.checksum = 0; 350 351 inet->tos = ip_hdr(skb)->tos; 352 daddr = ipc.addr = ip_hdr(skb)->saddr; 353 saddr = fib_compute_spec_dst(skb); 354 ipc.opt = NULL; 355 ipc.tx_flags = 0; 356 if (icmp_param->replyopts.opt.opt.optlen) { 357 ipc.opt = &icmp_param->replyopts.opt; 358 if (ipc.opt->opt.srr) 359 daddr = icmp_param->replyopts.opt.opt.faddr; 360 } 361 memset(&fl4, 0, sizeof(fl4)); 362 fl4.daddr = daddr; 363 fl4.saddr = saddr; 364 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 365 fl4.flowi4_proto = IPPROTO_ICMP; 366 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 367 rt = ip_route_output_key(net, &fl4); 368 if (IS_ERR(rt)) 369 goto out_unlock; 370 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type, 371 icmp_param->data.icmph.code)) 372 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 373 ip_rt_put(rt); 374 out_unlock: 375 icmp_xmit_unlock(sk); 376 } 377 378 static struct rtable *icmp_route_lookup(struct net *net, 379 struct flowi4 *fl4, 380 struct sk_buff *skb_in, 381 const struct iphdr *iph, 382 __be32 saddr, u8 tos, 383 int type, int code, 384 struct icmp_bxm *param) 385 { 386 struct rtable *rt, *rt2; 387 struct flowi4 fl4_dec; 388 int err; 389 390 memset(fl4, 0, sizeof(*fl4)); 391 fl4->daddr = (param->replyopts.opt.opt.srr ? 392 param->replyopts.opt.opt.faddr : iph->saddr); 393 fl4->saddr = saddr; 394 fl4->flowi4_tos = RT_TOS(tos); 395 fl4->flowi4_proto = IPPROTO_ICMP; 396 fl4->fl4_icmp_type = type; 397 fl4->fl4_icmp_code = code; 398 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 399 rt = __ip_route_output_key(net, fl4); 400 if (IS_ERR(rt)) 401 return rt; 402 403 /* No need to clone since we're just using its address. */ 404 rt2 = rt; 405 406 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 407 flowi4_to_flowi(fl4), NULL, 0); 408 if (!IS_ERR(rt)) { 409 if (rt != rt2) 410 return rt; 411 } else if (PTR_ERR(rt) == -EPERM) { 412 rt = NULL; 413 } else 414 return rt; 415 416 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 417 if (err) 418 goto relookup_failed; 419 420 if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) { 421 rt2 = __ip_route_output_key(net, &fl4_dec); 422 if (IS_ERR(rt2)) 423 err = PTR_ERR(rt2); 424 } else { 425 struct flowi4 fl4_2 = {}; 426 unsigned long orefdst; 427 428 fl4_2.daddr = fl4_dec.saddr; 429 rt2 = ip_route_output_key(net, &fl4_2); 430 if (IS_ERR(rt2)) { 431 err = PTR_ERR(rt2); 432 goto relookup_failed; 433 } 434 /* Ugh! */ 435 orefdst = skb_in->_skb_refdst; /* save old refdst */ 436 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 437 RT_TOS(tos), rt2->dst.dev); 438 439 dst_release(&rt2->dst); 440 rt2 = skb_rtable(skb_in); 441 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 442 } 443 444 if (err) 445 goto relookup_failed; 446 447 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 448 flowi4_to_flowi(&fl4_dec), NULL, 449 XFRM_LOOKUP_ICMP); 450 if (!IS_ERR(rt2)) { 451 dst_release(&rt->dst); 452 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 453 rt = rt2; 454 } else if (PTR_ERR(rt2) == -EPERM) { 455 if (rt) 456 dst_release(&rt->dst); 457 return rt2; 458 } else { 459 err = PTR_ERR(rt2); 460 goto relookup_failed; 461 } 462 return rt; 463 464 relookup_failed: 465 if (rt) 466 return rt; 467 return ERR_PTR(err); 468 } 469 470 /* 471 * Send an ICMP message in response to a situation 472 * 473 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 474 * MAY send more (we do). 475 * MUST NOT change this header information. 476 * MUST NOT reply to a multicast/broadcast IP address. 477 * MUST NOT reply to a multicast/broadcast MAC address. 478 * MUST reply to only the first fragment. 479 */ 480 481 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 482 { 483 struct iphdr *iph; 484 int room; 485 struct icmp_bxm icmp_param; 486 struct rtable *rt = skb_rtable(skb_in); 487 struct ipcm_cookie ipc; 488 struct flowi4 fl4; 489 __be32 saddr; 490 u8 tos; 491 struct net *net; 492 struct sock *sk; 493 494 if (!rt) 495 goto out; 496 net = dev_net(rt->dst.dev); 497 498 /* 499 * Find the original header. It is expected to be valid, of course. 500 * Check this, icmp_send is called from the most obscure devices 501 * sometimes. 502 */ 503 iph = ip_hdr(skb_in); 504 505 if ((u8 *)iph < skb_in->head || 506 (skb_in->network_header + sizeof(*iph)) > skb_in->tail) 507 goto out; 508 509 /* 510 * No replies to physical multicast/broadcast 511 */ 512 if (skb_in->pkt_type != PACKET_HOST) 513 goto out; 514 515 /* 516 * Now check at the protocol level 517 */ 518 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 519 goto out; 520 521 /* 522 * Only reply to fragment 0. We byte re-order the constant 523 * mask for efficiency. 524 */ 525 if (iph->frag_off & htons(IP_OFFSET)) 526 goto out; 527 528 /* 529 * If we send an ICMP error to an ICMP error a mess would result.. 530 */ 531 if (icmp_pointers[type].error) { 532 /* 533 * We are an error, check if we are replying to an 534 * ICMP error 535 */ 536 if (iph->protocol == IPPROTO_ICMP) { 537 u8 _inner_type, *itp; 538 539 itp = skb_header_pointer(skb_in, 540 skb_network_header(skb_in) + 541 (iph->ihl << 2) + 542 offsetof(struct icmphdr, 543 type) - 544 skb_in->data, 545 sizeof(_inner_type), 546 &_inner_type); 547 if (itp == NULL) 548 goto out; 549 550 /* 551 * Assume any unknown ICMP type is an error. This 552 * isn't specified by the RFC, but think about it.. 553 */ 554 if (*itp > NR_ICMP_TYPES || 555 icmp_pointers[*itp].error) 556 goto out; 557 } 558 } 559 560 sk = icmp_xmit_lock(net); 561 if (sk == NULL) 562 return; 563 564 /* 565 * Construct source address and options. 566 */ 567 568 saddr = iph->daddr; 569 if (!(rt->rt_flags & RTCF_LOCAL)) { 570 struct net_device *dev = NULL; 571 572 rcu_read_lock(); 573 if (rt_is_input_route(rt) && 574 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 575 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 576 577 if (dev) 578 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 579 else 580 saddr = 0; 581 rcu_read_unlock(); 582 } 583 584 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 585 IPTOS_PREC_INTERNETCONTROL) : 586 iph->tos; 587 588 if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in)) 589 goto out_unlock; 590 591 592 /* 593 * Prepare data for ICMP header. 594 */ 595 596 icmp_param.data.icmph.type = type; 597 icmp_param.data.icmph.code = code; 598 icmp_param.data.icmph.un.gateway = info; 599 icmp_param.data.icmph.checksum = 0; 600 icmp_param.skb = skb_in; 601 icmp_param.offset = skb_network_offset(skb_in); 602 inet_sk(sk)->tos = tos; 603 ipc.addr = iph->saddr; 604 ipc.opt = &icmp_param.replyopts.opt; 605 ipc.tx_flags = 0; 606 607 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, 608 type, code, &icmp_param); 609 if (IS_ERR(rt)) 610 goto out_unlock; 611 612 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 613 goto ende; 614 615 /* RFC says return as much as we can without exceeding 576 bytes. */ 616 617 room = dst_mtu(&rt->dst); 618 if (room > 576) 619 room = 576; 620 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 621 room -= sizeof(struct icmphdr); 622 623 icmp_param.data_len = skb_in->len - icmp_param.offset; 624 if (icmp_param.data_len > room) 625 icmp_param.data_len = room; 626 icmp_param.head_len = sizeof(struct icmphdr); 627 628 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt); 629 ende: 630 ip_rt_put(rt); 631 out_unlock: 632 icmp_xmit_unlock(sk); 633 out:; 634 } 635 EXPORT_SYMBOL(icmp_send); 636 637 638 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 639 { 640 const struct iphdr *iph = (const struct iphdr *) skb->data; 641 const struct net_protocol *ipprot; 642 int protocol = iph->protocol; 643 644 /* Checkin full IP header plus 8 bytes of protocol to 645 * avoid additional coding at protocol handlers. 646 */ 647 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 648 return; 649 650 raw_icmp_error(skb, protocol, info); 651 652 rcu_read_lock(); 653 ipprot = rcu_dereference(inet_protos[protocol]); 654 if (ipprot && ipprot->err_handler) 655 ipprot->err_handler(skb, info); 656 rcu_read_unlock(); 657 } 658 659 /* 660 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. 661 */ 662 663 static void icmp_unreach(struct sk_buff *skb) 664 { 665 const struct iphdr *iph; 666 struct icmphdr *icmph; 667 struct net *net; 668 u32 info = 0; 669 670 net = dev_net(skb_dst(skb)->dev); 671 672 /* 673 * Incomplete header ? 674 * Only checks for the IP header, there should be an 675 * additional check for longer headers in upper levels. 676 */ 677 678 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 679 goto out_err; 680 681 icmph = icmp_hdr(skb); 682 iph = (const struct iphdr *)skb->data; 683 684 if (iph->ihl < 5) /* Mangled header, drop. */ 685 goto out_err; 686 687 if (icmph->type == ICMP_DEST_UNREACH) { 688 switch (icmph->code & 15) { 689 case ICMP_NET_UNREACH: 690 case ICMP_HOST_UNREACH: 691 case ICMP_PROT_UNREACH: 692 case ICMP_PORT_UNREACH: 693 break; 694 case ICMP_FRAG_NEEDED: 695 if (ipv4_config.no_pmtu_disc) { 696 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"), 697 &iph->daddr); 698 } else { 699 info = ntohs(icmph->un.frag.mtu); 700 if (!info) 701 goto out; 702 } 703 break; 704 case ICMP_SR_FAILED: 705 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%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 isn't 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 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 737 &ip_hdr(skb)->saddr, 738 icmph->type, icmph->code, 739 &iph->daddr, skb->dev->name); 740 goto out; 741 } 742 743 icmp_socket_deliver(skb, info); 744 745 out: 746 return; 747 out_err: 748 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 749 goto out; 750 } 751 752 753 /* 754 * Handle ICMP_REDIRECT. 755 */ 756 757 static void icmp_redirect(struct sk_buff *skb) 758 { 759 if (skb->len < sizeof(struct iphdr)) { 760 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 761 return; 762 } 763 764 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 765 return; 766 767 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway); 768 } 769 770 /* 771 * Handle ICMP_ECHO ("ping") requests. 772 * 773 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 774 * requests. 775 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 776 * included in the reply. 777 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 778 * echo requests, MUST have default=NOT. 779 * See also WRT handling of options once they are done and working. 780 */ 781 782 static void icmp_echo(struct sk_buff *skb) 783 { 784 struct net *net; 785 786 net = dev_net(skb_dst(skb)->dev); 787 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 788 struct icmp_bxm icmp_param; 789 790 icmp_param.data.icmph = *icmp_hdr(skb); 791 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 792 icmp_param.skb = skb; 793 icmp_param.offset = 0; 794 icmp_param.data_len = skb->len; 795 icmp_param.head_len = sizeof(struct icmphdr); 796 icmp_reply(&icmp_param, skb); 797 } 798 } 799 800 /* 801 * Handle ICMP Timestamp requests. 802 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 803 * SHOULD be in the kernel for minimum random latency. 804 * MUST be accurate to a few minutes. 805 * MUST be updated at least at 15Hz. 806 */ 807 static void icmp_timestamp(struct sk_buff *skb) 808 { 809 struct timespec tv; 810 struct icmp_bxm icmp_param; 811 /* 812 * Too short. 813 */ 814 if (skb->len < 4) 815 goto out_err; 816 817 /* 818 * Fill in the current time as ms since midnight UT: 819 */ 820 getnstimeofday(&tv); 821 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 822 tv.tv_nsec / NSEC_PER_MSEC); 823 icmp_param.data.times[2] = icmp_param.data.times[1]; 824 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 825 BUG(); 826 icmp_param.data.icmph = *icmp_hdr(skb); 827 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 828 icmp_param.data.icmph.code = 0; 829 icmp_param.skb = skb; 830 icmp_param.offset = 0; 831 icmp_param.data_len = 0; 832 icmp_param.head_len = sizeof(struct icmphdr) + 12; 833 icmp_reply(&icmp_param, skb); 834 out: 835 return; 836 out_err: 837 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 838 goto out; 839 } 840 841 static void icmp_discard(struct sk_buff *skb) 842 { 843 } 844 845 /* 846 * Deal with incoming ICMP packets. 847 */ 848 int icmp_rcv(struct sk_buff *skb) 849 { 850 struct icmphdr *icmph; 851 struct rtable *rt = skb_rtable(skb); 852 struct net *net = dev_net(rt->dst.dev); 853 854 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 855 struct sec_path *sp = skb_sec_path(skb); 856 int nh; 857 858 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 859 XFRM_STATE_ICMP)) 860 goto drop; 861 862 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 863 goto drop; 864 865 nh = skb_network_offset(skb); 866 skb_set_network_header(skb, sizeof(*icmph)); 867 868 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 869 goto drop; 870 871 skb_set_network_header(skb, nh); 872 } 873 874 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 875 876 switch (skb->ip_summed) { 877 case CHECKSUM_COMPLETE: 878 if (!csum_fold(skb->csum)) 879 break; 880 /* fall through */ 881 case CHECKSUM_NONE: 882 skb->csum = 0; 883 if (__skb_checksum_complete(skb)) 884 goto error; 885 } 886 887 if (!pskb_pull(skb, sizeof(*icmph))) 888 goto error; 889 890 icmph = icmp_hdr(skb); 891 892 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 893 /* 894 * 18 is the highest 'known' ICMP type. Anything else is a mystery 895 * 896 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 897 * discarded. 898 */ 899 if (icmph->type > NR_ICMP_TYPES) 900 goto error; 901 902 903 /* 904 * Parse the ICMP message 905 */ 906 907 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 908 /* 909 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 910 * silently ignored (we let user decide with a sysctl). 911 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 912 * discarded if to broadcast/multicast. 913 */ 914 if ((icmph->type == ICMP_ECHO || 915 icmph->type == ICMP_TIMESTAMP) && 916 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 917 goto error; 918 } 919 if (icmph->type != ICMP_ECHO && 920 icmph->type != ICMP_TIMESTAMP && 921 icmph->type != ICMP_ADDRESS && 922 icmph->type != ICMP_ADDRESSREPLY) { 923 goto error; 924 } 925 } 926 927 icmp_pointers[icmph->type].handler(skb); 928 929 drop: 930 kfree_skb(skb); 931 return 0; 932 error: 933 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 934 goto drop; 935 } 936 937 /* 938 * This table is the definition of how we handle ICMP. 939 */ 940 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 941 [ICMP_ECHOREPLY] = { 942 .handler = ping_rcv, 943 }, 944 [1] = { 945 .handler = icmp_discard, 946 .error = 1, 947 }, 948 [2] = { 949 .handler = icmp_discard, 950 .error = 1, 951 }, 952 [ICMP_DEST_UNREACH] = { 953 .handler = icmp_unreach, 954 .error = 1, 955 }, 956 [ICMP_SOURCE_QUENCH] = { 957 .handler = icmp_unreach, 958 .error = 1, 959 }, 960 [ICMP_REDIRECT] = { 961 .handler = icmp_redirect, 962 .error = 1, 963 }, 964 [6] = { 965 .handler = icmp_discard, 966 .error = 1, 967 }, 968 [7] = { 969 .handler = icmp_discard, 970 .error = 1, 971 }, 972 [ICMP_ECHO] = { 973 .handler = icmp_echo, 974 }, 975 [9] = { 976 .handler = icmp_discard, 977 .error = 1, 978 }, 979 [10] = { 980 .handler = icmp_discard, 981 .error = 1, 982 }, 983 [ICMP_TIME_EXCEEDED] = { 984 .handler = icmp_unreach, 985 .error = 1, 986 }, 987 [ICMP_PARAMETERPROB] = { 988 .handler = icmp_unreach, 989 .error = 1, 990 }, 991 [ICMP_TIMESTAMP] = { 992 .handler = icmp_timestamp, 993 }, 994 [ICMP_TIMESTAMPREPLY] = { 995 .handler = icmp_discard, 996 }, 997 [ICMP_INFO_REQUEST] = { 998 .handler = icmp_discard, 999 }, 1000 [ICMP_INFO_REPLY] = { 1001 .handler = icmp_discard, 1002 }, 1003 [ICMP_ADDRESS] = { 1004 .handler = icmp_discard, 1005 }, 1006 [ICMP_ADDRESSREPLY] = { 1007 .handler = icmp_discard, 1008 }, 1009 }; 1010 1011 static void __net_exit icmp_sk_exit(struct net *net) 1012 { 1013 int i; 1014 1015 for_each_possible_cpu(i) 1016 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1017 kfree(net->ipv4.icmp_sk); 1018 net->ipv4.icmp_sk = NULL; 1019 } 1020 1021 static int __net_init icmp_sk_init(struct net *net) 1022 { 1023 int i, err; 1024 1025 net->ipv4.icmp_sk = 1026 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); 1027 if (net->ipv4.icmp_sk == NULL) 1028 return -ENOMEM; 1029 1030 for_each_possible_cpu(i) { 1031 struct sock *sk; 1032 1033 err = inet_ctl_sock_create(&sk, PF_INET, 1034 SOCK_RAW, IPPROTO_ICMP, net); 1035 if (err < 0) 1036 goto fail; 1037 1038 net->ipv4.icmp_sk[i] = sk; 1039 1040 /* Enough space for 2 64K ICMP packets, including 1041 * sk_buff/skb_shared_info struct overhead. 1042 */ 1043 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1044 1045 /* 1046 * Speedup sock_wfree() 1047 */ 1048 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1049 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1050 } 1051 1052 /* Control parameters for ECHO replies. */ 1053 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1054 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1055 1056 /* Control parameter - ignore bogus broadcast responses? */ 1057 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1058 1059 /* 1060 * Configurable global rate limit. 1061 * 1062 * ratelimit defines tokens/packet consumed for dst->rate_token 1063 * bucket ratemask defines which icmp types are ratelimited by 1064 * setting it's bit position. 1065 * 1066 * default: 1067 * dest unreachable (3), source quench (4), 1068 * time exceeded (11), parameter problem (12) 1069 */ 1070 1071 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1072 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1073 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1074 1075 return 0; 1076 1077 fail: 1078 for_each_possible_cpu(i) 1079 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1080 kfree(net->ipv4.icmp_sk); 1081 return err; 1082 } 1083 1084 static struct pernet_operations __net_initdata icmp_sk_ops = { 1085 .init = icmp_sk_init, 1086 .exit = icmp_sk_exit, 1087 }; 1088 1089 int __init icmp_init(void) 1090 { 1091 return register_pernet_subsys(&icmp_sk_ops); 1092 } 1093