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 ipc.ttl = 0; 357 ipc.tos = -1; 358 359 if (icmp_param->replyopts.opt.opt.optlen) { 360 ipc.opt = &icmp_param->replyopts.opt; 361 if (ipc.opt->opt.srr) 362 daddr = icmp_param->replyopts.opt.opt.faddr; 363 } 364 memset(&fl4, 0, sizeof(fl4)); 365 fl4.daddr = daddr; 366 fl4.saddr = saddr; 367 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 368 fl4.flowi4_proto = IPPROTO_ICMP; 369 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 370 rt = ip_route_output_key(net, &fl4); 371 if (IS_ERR(rt)) 372 goto out_unlock; 373 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type, 374 icmp_param->data.icmph.code)) 375 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 376 ip_rt_put(rt); 377 out_unlock: 378 icmp_xmit_unlock(sk); 379 } 380 381 static struct rtable *icmp_route_lookup(struct net *net, 382 struct flowi4 *fl4, 383 struct sk_buff *skb_in, 384 const struct iphdr *iph, 385 __be32 saddr, u8 tos, 386 int type, int code, 387 struct icmp_bxm *param) 388 { 389 struct rtable *rt, *rt2; 390 struct flowi4 fl4_dec; 391 int err; 392 393 memset(fl4, 0, sizeof(*fl4)); 394 fl4->daddr = (param->replyopts.opt.opt.srr ? 395 param->replyopts.opt.opt.faddr : iph->saddr); 396 fl4->saddr = saddr; 397 fl4->flowi4_tos = RT_TOS(tos); 398 fl4->flowi4_proto = IPPROTO_ICMP; 399 fl4->fl4_icmp_type = type; 400 fl4->fl4_icmp_code = code; 401 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 402 rt = __ip_route_output_key(net, fl4); 403 if (IS_ERR(rt)) 404 return rt; 405 406 /* No need to clone since we're just using its address. */ 407 rt2 = rt; 408 409 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 410 flowi4_to_flowi(fl4), NULL, 0); 411 if (!IS_ERR(rt)) { 412 if (rt != rt2) 413 return rt; 414 } else if (PTR_ERR(rt) == -EPERM) { 415 rt = NULL; 416 } else 417 return rt; 418 419 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 420 if (err) 421 goto relookup_failed; 422 423 if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) { 424 rt2 = __ip_route_output_key(net, &fl4_dec); 425 if (IS_ERR(rt2)) 426 err = PTR_ERR(rt2); 427 } else { 428 struct flowi4 fl4_2 = {}; 429 unsigned long orefdst; 430 431 fl4_2.daddr = fl4_dec.saddr; 432 rt2 = ip_route_output_key(net, &fl4_2); 433 if (IS_ERR(rt2)) { 434 err = PTR_ERR(rt2); 435 goto relookup_failed; 436 } 437 /* Ugh! */ 438 orefdst = skb_in->_skb_refdst; /* save old refdst */ 439 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 440 RT_TOS(tos), rt2->dst.dev); 441 442 dst_release(&rt2->dst); 443 rt2 = skb_rtable(skb_in); 444 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 445 } 446 447 if (err) 448 goto relookup_failed; 449 450 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 451 flowi4_to_flowi(&fl4_dec), NULL, 452 XFRM_LOOKUP_ICMP); 453 if (!IS_ERR(rt2)) { 454 dst_release(&rt->dst); 455 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 456 rt = rt2; 457 } else if (PTR_ERR(rt2) == -EPERM) { 458 if (rt) 459 dst_release(&rt->dst); 460 return rt2; 461 } else { 462 err = PTR_ERR(rt2); 463 goto relookup_failed; 464 } 465 return rt; 466 467 relookup_failed: 468 if (rt) 469 return rt; 470 return ERR_PTR(err); 471 } 472 473 /* 474 * Send an ICMP message in response to a situation 475 * 476 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 477 * MAY send more (we do). 478 * MUST NOT change this header information. 479 * MUST NOT reply to a multicast/broadcast IP address. 480 * MUST NOT reply to a multicast/broadcast MAC address. 481 * MUST reply to only the first fragment. 482 */ 483 484 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 485 { 486 struct iphdr *iph; 487 int room; 488 struct icmp_bxm *icmp_param; 489 struct rtable *rt = skb_rtable(skb_in); 490 struct ipcm_cookie ipc; 491 struct flowi4 fl4; 492 __be32 saddr; 493 u8 tos; 494 struct net *net; 495 struct sock *sk; 496 497 if (!rt) 498 goto out; 499 net = dev_net(rt->dst.dev); 500 501 /* 502 * Find the original header. It is expected to be valid, of course. 503 * Check this, icmp_send is called from the most obscure devices 504 * sometimes. 505 */ 506 iph = ip_hdr(skb_in); 507 508 if ((u8 *)iph < skb_in->head || 509 (skb_network_header(skb_in) + sizeof(*iph)) > 510 skb_tail_pointer(skb_in)) 511 goto out; 512 513 /* 514 * No replies to physical multicast/broadcast 515 */ 516 if (skb_in->pkt_type != PACKET_HOST) 517 goto out; 518 519 /* 520 * Now check at the protocol level 521 */ 522 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 523 goto out; 524 525 /* 526 * Only reply to fragment 0. We byte re-order the constant 527 * mask for efficiency. 528 */ 529 if (iph->frag_off & htons(IP_OFFSET)) 530 goto out; 531 532 /* 533 * If we send an ICMP error to an ICMP error a mess would result.. 534 */ 535 if (icmp_pointers[type].error) { 536 /* 537 * We are an error, check if we are replying to an 538 * ICMP error 539 */ 540 if (iph->protocol == IPPROTO_ICMP) { 541 u8 _inner_type, *itp; 542 543 itp = skb_header_pointer(skb_in, 544 skb_network_header(skb_in) + 545 (iph->ihl << 2) + 546 offsetof(struct icmphdr, 547 type) - 548 skb_in->data, 549 sizeof(_inner_type), 550 &_inner_type); 551 if (itp == NULL) 552 goto out; 553 554 /* 555 * Assume any unknown ICMP type is an error. This 556 * isn't specified by the RFC, but think about it.. 557 */ 558 if (*itp > NR_ICMP_TYPES || 559 icmp_pointers[*itp].error) 560 goto out; 561 } 562 } 563 564 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC); 565 if (!icmp_param) 566 return; 567 568 sk = icmp_xmit_lock(net); 569 if (sk == NULL) 570 goto out_free; 571 572 /* 573 * Construct source address and options. 574 */ 575 576 saddr = iph->daddr; 577 if (!(rt->rt_flags & RTCF_LOCAL)) { 578 struct net_device *dev = NULL; 579 580 rcu_read_lock(); 581 if (rt_is_input_route(rt) && 582 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 583 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 584 585 if (dev) 586 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 587 else 588 saddr = 0; 589 rcu_read_unlock(); 590 } 591 592 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 593 IPTOS_PREC_INTERNETCONTROL) : 594 iph->tos; 595 596 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in)) 597 goto out_unlock; 598 599 600 /* 601 * Prepare data for ICMP header. 602 */ 603 604 icmp_param->data.icmph.type = type; 605 icmp_param->data.icmph.code = code; 606 icmp_param->data.icmph.un.gateway = info; 607 icmp_param->data.icmph.checksum = 0; 608 icmp_param->skb = skb_in; 609 icmp_param->offset = skb_network_offset(skb_in); 610 inet_sk(sk)->tos = tos; 611 ipc.addr = iph->saddr; 612 ipc.opt = &icmp_param->replyopts.opt; 613 ipc.tx_flags = 0; 614 ipc.ttl = 0; 615 ipc.tos = -1; 616 617 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, 618 type, code, icmp_param); 619 if (IS_ERR(rt)) 620 goto out_unlock; 621 622 if (!icmpv4_xrlim_allow(net, rt, &fl4, 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.opt.opt.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, &fl4, &ipc, &rt); 639 ende: 640 ip_rt_put(rt); 641 out_unlock: 642 icmp_xmit_unlock(sk); 643 out_free: 644 kfree(icmp_param); 645 out:; 646 } 647 EXPORT_SYMBOL(icmp_send); 648 649 650 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 651 { 652 const struct iphdr *iph = (const struct iphdr *) skb->data; 653 const struct net_protocol *ipprot; 654 int protocol = iph->protocol; 655 656 /* Checkin full IP header plus 8 bytes of protocol to 657 * avoid additional coding at protocol handlers. 658 */ 659 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 660 return; 661 662 raw_icmp_error(skb, protocol, info); 663 664 rcu_read_lock(); 665 ipprot = rcu_dereference(inet_protos[protocol]); 666 if (ipprot && ipprot->err_handler) 667 ipprot->err_handler(skb, info); 668 rcu_read_unlock(); 669 } 670 671 /* 672 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and 673 * ICMP_PARAMETERPROB. 674 */ 675 676 static void icmp_unreach(struct sk_buff *skb) 677 { 678 const struct iphdr *iph; 679 struct icmphdr *icmph; 680 struct net *net; 681 u32 info = 0; 682 683 net = dev_net(skb_dst(skb)->dev); 684 685 /* 686 * Incomplete header ? 687 * Only checks for the IP header, there should be an 688 * additional check for longer headers in upper levels. 689 */ 690 691 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 692 goto out_err; 693 694 icmph = icmp_hdr(skb); 695 iph = (const struct iphdr *)skb->data; 696 697 if (iph->ihl < 5) /* Mangled header, drop. */ 698 goto out_err; 699 700 if (icmph->type == ICMP_DEST_UNREACH) { 701 switch (icmph->code & 15) { 702 case ICMP_NET_UNREACH: 703 case ICMP_HOST_UNREACH: 704 case ICMP_PROT_UNREACH: 705 case ICMP_PORT_UNREACH: 706 break; 707 case ICMP_FRAG_NEEDED: 708 if (ipv4_config.no_pmtu_disc) { 709 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"), 710 &iph->daddr); 711 } else { 712 info = ntohs(icmph->un.frag.mtu); 713 if (!info) 714 goto out; 715 } 716 break; 717 case ICMP_SR_FAILED: 718 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"), 719 &iph->daddr); 720 break; 721 default: 722 break; 723 } 724 if (icmph->code > NR_ICMP_UNREACH) 725 goto out; 726 } else if (icmph->type == ICMP_PARAMETERPROB) 727 info = ntohl(icmph->un.gateway) >> 24; 728 729 /* 730 * Throw it at our lower layers 731 * 732 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 733 * header. 734 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 735 * transport layer. 736 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 737 * transport layer. 738 */ 739 740 /* 741 * Check the other end isn't violating RFC 1122. Some routers send 742 * bogus responses to broadcast frames. If you see this message 743 * first check your netmask matches at both ends, if it does then 744 * get the other vendor to fix their kit. 745 */ 746 747 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 748 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { 749 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 750 &ip_hdr(skb)->saddr, 751 icmph->type, icmph->code, 752 &iph->daddr, skb->dev->name); 753 goto out; 754 } 755 756 icmp_socket_deliver(skb, info); 757 758 out: 759 return; 760 out_err: 761 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 762 goto out; 763 } 764 765 766 /* 767 * Handle ICMP_REDIRECT. 768 */ 769 770 static void icmp_redirect(struct sk_buff *skb) 771 { 772 if (skb->len < sizeof(struct iphdr)) { 773 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 774 return; 775 } 776 777 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 778 return; 779 780 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway); 781 } 782 783 /* 784 * Handle ICMP_ECHO ("ping") requests. 785 * 786 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 787 * requests. 788 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 789 * included in the reply. 790 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 791 * echo requests, MUST have default=NOT. 792 * See also WRT handling of options once they are done and working. 793 */ 794 795 static void icmp_echo(struct sk_buff *skb) 796 { 797 struct net *net; 798 799 net = dev_net(skb_dst(skb)->dev); 800 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 801 struct icmp_bxm icmp_param; 802 803 icmp_param.data.icmph = *icmp_hdr(skb); 804 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 805 icmp_param.skb = skb; 806 icmp_param.offset = 0; 807 icmp_param.data_len = skb->len; 808 icmp_param.head_len = sizeof(struct icmphdr); 809 icmp_reply(&icmp_param, skb); 810 } 811 } 812 813 /* 814 * Handle ICMP Timestamp requests. 815 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 816 * SHOULD be in the kernel for minimum random latency. 817 * MUST be accurate to a few minutes. 818 * MUST be updated at least at 15Hz. 819 */ 820 static void icmp_timestamp(struct sk_buff *skb) 821 { 822 struct timespec tv; 823 struct icmp_bxm icmp_param; 824 /* 825 * Too short. 826 */ 827 if (skb->len < 4) 828 goto out_err; 829 830 /* 831 * Fill in the current time as ms since midnight UT: 832 */ 833 getnstimeofday(&tv); 834 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 835 tv.tv_nsec / NSEC_PER_MSEC); 836 icmp_param.data.times[2] = icmp_param.data.times[1]; 837 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 838 BUG(); 839 icmp_param.data.icmph = *icmp_hdr(skb); 840 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 841 icmp_param.data.icmph.code = 0; 842 icmp_param.skb = skb; 843 icmp_param.offset = 0; 844 icmp_param.data_len = 0; 845 icmp_param.head_len = sizeof(struct icmphdr) + 12; 846 icmp_reply(&icmp_param, skb); 847 out: 848 return; 849 out_err: 850 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 851 goto out; 852 } 853 854 static void icmp_discard(struct sk_buff *skb) 855 { 856 } 857 858 /* 859 * Deal with incoming ICMP packets. 860 */ 861 int icmp_rcv(struct sk_buff *skb) 862 { 863 struct icmphdr *icmph; 864 struct rtable *rt = skb_rtable(skb); 865 struct net *net = dev_net(rt->dst.dev); 866 867 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 868 struct sec_path *sp = skb_sec_path(skb); 869 int nh; 870 871 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 872 XFRM_STATE_ICMP)) 873 goto drop; 874 875 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 876 goto drop; 877 878 nh = skb_network_offset(skb); 879 skb_set_network_header(skb, sizeof(*icmph)); 880 881 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 882 goto drop; 883 884 skb_set_network_header(skb, nh); 885 } 886 887 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 888 889 switch (skb->ip_summed) { 890 case CHECKSUM_COMPLETE: 891 if (!csum_fold(skb->csum)) 892 break; 893 /* fall through */ 894 case CHECKSUM_NONE: 895 skb->csum = 0; 896 if (__skb_checksum_complete(skb)) 897 goto csum_error; 898 } 899 900 if (!pskb_pull(skb, sizeof(*icmph))) 901 goto error; 902 903 icmph = icmp_hdr(skb); 904 905 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 906 /* 907 * 18 is the highest 'known' ICMP type. Anything else is a mystery 908 * 909 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 910 * discarded. 911 */ 912 if (icmph->type > NR_ICMP_TYPES) 913 goto error; 914 915 916 /* 917 * Parse the ICMP message 918 */ 919 920 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 921 /* 922 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 923 * silently ignored (we let user decide with a sysctl). 924 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 925 * discarded if to broadcast/multicast. 926 */ 927 if ((icmph->type == ICMP_ECHO || 928 icmph->type == ICMP_TIMESTAMP) && 929 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 930 goto error; 931 } 932 if (icmph->type != ICMP_ECHO && 933 icmph->type != ICMP_TIMESTAMP && 934 icmph->type != ICMP_ADDRESS && 935 icmph->type != ICMP_ADDRESSREPLY) { 936 goto error; 937 } 938 } 939 940 icmp_pointers[icmph->type].handler(skb); 941 942 drop: 943 kfree_skb(skb); 944 return 0; 945 csum_error: 946 ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS); 947 error: 948 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 949 goto drop; 950 } 951 952 void icmp_err(struct sk_buff *skb, u32 info) 953 { 954 struct iphdr *iph = (struct iphdr *)skb->data; 955 int offset = iph->ihl<<2; 956 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 957 int type = icmp_hdr(skb)->type; 958 int code = icmp_hdr(skb)->code; 959 struct net *net = dev_net(skb->dev); 960 961 /* 962 * Use ping_err to handle all icmp errors except those 963 * triggered by ICMP_ECHOREPLY which sent from kernel. 964 */ 965 if (icmph->type != ICMP_ECHOREPLY) { 966 ping_err(skb, offset, info); 967 return; 968 } 969 970 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 971 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0); 972 else if (type == ICMP_REDIRECT) 973 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0); 974 } 975 976 /* 977 * This table is the definition of how we handle ICMP. 978 */ 979 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 980 [ICMP_ECHOREPLY] = { 981 .handler = ping_rcv, 982 }, 983 [1] = { 984 .handler = icmp_discard, 985 .error = 1, 986 }, 987 [2] = { 988 .handler = icmp_discard, 989 .error = 1, 990 }, 991 [ICMP_DEST_UNREACH] = { 992 .handler = icmp_unreach, 993 .error = 1, 994 }, 995 [ICMP_SOURCE_QUENCH] = { 996 .handler = icmp_unreach, 997 .error = 1, 998 }, 999 [ICMP_REDIRECT] = { 1000 .handler = icmp_redirect, 1001 .error = 1, 1002 }, 1003 [6] = { 1004 .handler = icmp_discard, 1005 .error = 1, 1006 }, 1007 [7] = { 1008 .handler = icmp_discard, 1009 .error = 1, 1010 }, 1011 [ICMP_ECHO] = { 1012 .handler = icmp_echo, 1013 }, 1014 [9] = { 1015 .handler = icmp_discard, 1016 .error = 1, 1017 }, 1018 [10] = { 1019 .handler = icmp_discard, 1020 .error = 1, 1021 }, 1022 [ICMP_TIME_EXCEEDED] = { 1023 .handler = icmp_unreach, 1024 .error = 1, 1025 }, 1026 [ICMP_PARAMETERPROB] = { 1027 .handler = icmp_unreach, 1028 .error = 1, 1029 }, 1030 [ICMP_TIMESTAMP] = { 1031 .handler = icmp_timestamp, 1032 }, 1033 [ICMP_TIMESTAMPREPLY] = { 1034 .handler = icmp_discard, 1035 }, 1036 [ICMP_INFO_REQUEST] = { 1037 .handler = icmp_discard, 1038 }, 1039 [ICMP_INFO_REPLY] = { 1040 .handler = icmp_discard, 1041 }, 1042 [ICMP_ADDRESS] = { 1043 .handler = icmp_discard, 1044 }, 1045 [ICMP_ADDRESSREPLY] = { 1046 .handler = icmp_discard, 1047 }, 1048 }; 1049 1050 static void __net_exit icmp_sk_exit(struct net *net) 1051 { 1052 int i; 1053 1054 for_each_possible_cpu(i) 1055 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1056 kfree(net->ipv4.icmp_sk); 1057 net->ipv4.icmp_sk = NULL; 1058 } 1059 1060 static int __net_init icmp_sk_init(struct net *net) 1061 { 1062 int i, err; 1063 1064 net->ipv4.icmp_sk = 1065 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); 1066 if (net->ipv4.icmp_sk == NULL) 1067 return -ENOMEM; 1068 1069 for_each_possible_cpu(i) { 1070 struct sock *sk; 1071 1072 err = inet_ctl_sock_create(&sk, PF_INET, 1073 SOCK_RAW, IPPROTO_ICMP, net); 1074 if (err < 0) 1075 goto fail; 1076 1077 net->ipv4.icmp_sk[i] = sk; 1078 1079 /* Enough space for 2 64K ICMP packets, including 1080 * sk_buff/skb_shared_info struct overhead. 1081 */ 1082 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1083 1084 /* 1085 * Speedup sock_wfree() 1086 */ 1087 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1088 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1089 } 1090 1091 /* Control parameters for ECHO replies. */ 1092 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1093 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1094 1095 /* Control parameter - ignore bogus broadcast responses? */ 1096 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1097 1098 /* 1099 * Configurable global rate limit. 1100 * 1101 * ratelimit defines tokens/packet consumed for dst->rate_token 1102 * bucket ratemask defines which icmp types are ratelimited by 1103 * setting it's bit position. 1104 * 1105 * default: 1106 * dest unreachable (3), source quench (4), 1107 * time exceeded (11), parameter problem (12) 1108 */ 1109 1110 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1111 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1112 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1113 1114 return 0; 1115 1116 fail: 1117 for_each_possible_cpu(i) 1118 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); 1119 kfree(net->ipv4.icmp_sk); 1120 return err; 1121 } 1122 1123 static struct pernet_operations __net_initdata icmp_sk_ops = { 1124 .init = icmp_sk_init, 1125 .exit = icmp_sk_exit, 1126 }; 1127 1128 int __init icmp_init(void) 1129 { 1130 return register_pernet_subsys(&icmp_sk_ops); 1131 } 1132