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 #include <net/vrf.h> 100 101 /* 102 * Build xmit assembly blocks 103 */ 104 105 struct icmp_bxm { 106 struct sk_buff *skb; 107 int offset; 108 int data_len; 109 110 struct { 111 struct icmphdr icmph; 112 __be32 times[3]; 113 } data; 114 int head_len; 115 struct ip_options_data replyopts; 116 }; 117 118 /* An array of errno for error messages from dest unreach. */ 119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 120 121 const struct icmp_err icmp_err_convert[] = { 122 { 123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 124 .fatal = 0, 125 }, 126 { 127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 128 .fatal = 0, 129 }, 130 { 131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 132 .fatal = 1, 133 }, 134 { 135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 136 .fatal = 1, 137 }, 138 { 139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 140 .fatal = 0, 141 }, 142 { 143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 144 .fatal = 0, 145 }, 146 { 147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 148 .fatal = 1, 149 }, 150 { 151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 152 .fatal = 1, 153 }, 154 { 155 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 156 .fatal = 1, 157 }, 158 { 159 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 160 .fatal = 1, 161 }, 162 { 163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 164 .fatal = 1, 165 }, 166 { 167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 168 .fatal = 0, 169 }, 170 { 171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 172 .fatal = 0, 173 }, 174 { 175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 176 .fatal = 1, 177 }, 178 { 179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 180 .fatal = 1, 181 }, 182 { 183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 184 .fatal = 1, 185 }, 186 }; 187 EXPORT_SYMBOL(icmp_err_convert); 188 189 /* 190 * ICMP control array. This specifies what to do with each ICMP. 191 */ 192 193 struct icmp_control { 194 bool (*handler)(struct sk_buff *skb); 195 short error; /* This ICMP is classed as an error message */ 196 }; 197 198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 199 200 /* 201 * The ICMP socket(s). This is the most convenient way to flow control 202 * our ICMP output as well as maintain a clean interface throughout 203 * all layers. All Socketless IP sends will soon be gone. 204 * 205 * On SMP we have one ICMP socket per-cpu. 206 */ 207 static struct sock *icmp_sk(struct net *net) 208 { 209 return *this_cpu_ptr(net->ipv4.icmp_sk); 210 } 211 212 static inline struct sock *icmp_xmit_lock(struct net *net) 213 { 214 struct sock *sk; 215 216 local_bh_disable(); 217 218 sk = icmp_sk(net); 219 220 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 221 /* This can happen if the output path signals a 222 * dst_link_failure() for an outgoing ICMP packet. 223 */ 224 local_bh_enable(); 225 return NULL; 226 } 227 return sk; 228 } 229 230 static inline void icmp_xmit_unlock(struct sock *sk) 231 { 232 spin_unlock_bh(&sk->sk_lock.slock); 233 } 234 235 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 236 int sysctl_icmp_msgs_burst __read_mostly = 50; 237 238 static struct { 239 spinlock_t lock; 240 u32 credit; 241 u32 stamp; 242 } icmp_global = { 243 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 244 }; 245 246 /** 247 * icmp_global_allow - Are we allowed to send one more ICMP message ? 248 * 249 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec. 250 * Returns false if we reached the limit and can not send another packet. 251 * Note: called with BH disabled 252 */ 253 bool icmp_global_allow(void) 254 { 255 u32 credit, delta, incr = 0, now = (u32)jiffies; 256 bool rc = false; 257 258 /* Check if token bucket is empty and cannot be refilled 259 * without taking the spinlock. 260 */ 261 if (!icmp_global.credit) { 262 delta = min_t(u32, now - icmp_global.stamp, HZ); 263 if (delta < HZ / 50) 264 return false; 265 } 266 267 spin_lock(&icmp_global.lock); 268 delta = min_t(u32, now - icmp_global.stamp, HZ); 269 if (delta >= HZ / 50) { 270 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 271 if (incr) 272 icmp_global.stamp = now; 273 } 274 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 275 if (credit) { 276 credit--; 277 rc = true; 278 } 279 icmp_global.credit = credit; 280 spin_unlock(&icmp_global.lock); 281 return rc; 282 } 283 EXPORT_SYMBOL(icmp_global_allow); 284 285 /* 286 * Send an ICMP frame. 287 */ 288 289 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 290 struct flowi4 *fl4, int type, int code) 291 { 292 struct dst_entry *dst = &rt->dst; 293 bool rc = true; 294 295 if (type > NR_ICMP_TYPES) 296 goto out; 297 298 /* Don't limit PMTU discovery. */ 299 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 300 goto out; 301 302 /* No rate limit on loopback */ 303 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 304 goto out; 305 306 /* Limit if icmp type is enabled in ratemask. */ 307 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask)) 308 goto out; 309 310 rc = false; 311 if (icmp_global_allow()) { 312 int vif = vrf_master_ifindex(dst->dev); 313 struct inet_peer *peer; 314 315 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 316 rc = inet_peer_xrlim_allow(peer, 317 net->ipv4.sysctl_icmp_ratelimit); 318 if (peer) 319 inet_putpeer(peer); 320 } 321 out: 322 return rc; 323 } 324 325 /* 326 * Maintain the counters used in the SNMP statistics for outgoing ICMP 327 */ 328 void icmp_out_count(struct net *net, unsigned char type) 329 { 330 ICMPMSGOUT_INC_STATS(net, type); 331 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 332 } 333 334 /* 335 * Checksum each fragment, and on the first include the headers and final 336 * checksum. 337 */ 338 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 339 struct sk_buff *skb) 340 { 341 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 342 __wsum csum; 343 344 csum = skb_copy_and_csum_bits(icmp_param->skb, 345 icmp_param->offset + offset, 346 to, len, 0); 347 348 skb->csum = csum_block_add(skb->csum, csum, odd); 349 if (icmp_pointers[icmp_param->data.icmph.type].error) 350 nf_ct_attach(skb, icmp_param->skb); 351 return 0; 352 } 353 354 static void icmp_push_reply(struct icmp_bxm *icmp_param, 355 struct flowi4 *fl4, 356 struct ipcm_cookie *ipc, struct rtable **rt) 357 { 358 struct sock *sk; 359 struct sk_buff *skb; 360 361 sk = icmp_sk(dev_net((*rt)->dst.dev)); 362 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 363 icmp_param->data_len+icmp_param->head_len, 364 icmp_param->head_len, 365 ipc, rt, MSG_DONTWAIT) < 0) { 366 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS); 367 ip_flush_pending_frames(sk); 368 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 369 struct icmphdr *icmph = icmp_hdr(skb); 370 __wsum csum = 0; 371 struct sk_buff *skb1; 372 373 skb_queue_walk(&sk->sk_write_queue, skb1) { 374 csum = csum_add(csum, skb1->csum); 375 } 376 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 377 (char *)icmph, 378 icmp_param->head_len, csum); 379 icmph->checksum = csum_fold(csum); 380 skb->ip_summed = CHECKSUM_NONE; 381 ip_push_pending_frames(sk, fl4); 382 } 383 } 384 385 /* 386 * Driving logic for building and sending ICMP messages. 387 */ 388 389 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 390 { 391 struct ipcm_cookie ipc; 392 struct rtable *rt = skb_rtable(skb); 393 struct net *net = dev_net(rt->dst.dev); 394 struct flowi4 fl4; 395 struct sock *sk; 396 struct inet_sock *inet; 397 __be32 daddr, saddr; 398 u32 mark = IP4_REPLY_MARK(net, skb->mark); 399 400 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb)) 401 return; 402 403 sk = icmp_xmit_lock(net); 404 if (!sk) 405 return; 406 inet = inet_sk(sk); 407 408 icmp_param->data.icmph.checksum = 0; 409 410 inet->tos = ip_hdr(skb)->tos; 411 sk->sk_mark = mark; 412 daddr = ipc.addr = ip_hdr(skb)->saddr; 413 saddr = fib_compute_spec_dst(skb); 414 ipc.opt = NULL; 415 ipc.tx_flags = 0; 416 ipc.ttl = 0; 417 ipc.tos = -1; 418 419 if (icmp_param->replyopts.opt.opt.optlen) { 420 ipc.opt = &icmp_param->replyopts.opt; 421 if (ipc.opt->opt.srr) 422 daddr = icmp_param->replyopts.opt.opt.faddr; 423 } 424 memset(&fl4, 0, sizeof(fl4)); 425 fl4.daddr = daddr; 426 fl4.saddr = saddr; 427 fl4.flowi4_mark = mark; 428 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 429 fl4.flowi4_proto = IPPROTO_ICMP; 430 fl4.flowi4_oif = vrf_master_ifindex(skb->dev); 431 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 432 rt = ip_route_output_key(net, &fl4); 433 if (IS_ERR(rt)) 434 goto out_unlock; 435 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type, 436 icmp_param->data.icmph.code)) 437 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 438 ip_rt_put(rt); 439 out_unlock: 440 icmp_xmit_unlock(sk); 441 } 442 443 static struct rtable *icmp_route_lookup(struct net *net, 444 struct flowi4 *fl4, 445 struct sk_buff *skb_in, 446 const struct iphdr *iph, 447 __be32 saddr, u8 tos, u32 mark, 448 int type, int code, 449 struct icmp_bxm *param) 450 { 451 struct rtable *rt, *rt2; 452 struct flowi4 fl4_dec; 453 int err; 454 455 memset(fl4, 0, sizeof(*fl4)); 456 fl4->daddr = (param->replyopts.opt.opt.srr ? 457 param->replyopts.opt.opt.faddr : iph->saddr); 458 fl4->saddr = saddr; 459 fl4->flowi4_mark = mark; 460 fl4->flowi4_tos = RT_TOS(tos); 461 fl4->flowi4_proto = IPPROTO_ICMP; 462 fl4->fl4_icmp_type = type; 463 fl4->fl4_icmp_code = code; 464 fl4->flowi4_oif = vrf_master_ifindex(skb_in->dev); 465 466 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 467 rt = __ip_route_output_key(net, fl4); 468 if (IS_ERR(rt)) 469 return rt; 470 471 /* No need to clone since we're just using its address. */ 472 rt2 = rt; 473 474 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 475 flowi4_to_flowi(fl4), NULL, 0); 476 if (!IS_ERR(rt)) { 477 if (rt != rt2) 478 return rt; 479 } else if (PTR_ERR(rt) == -EPERM) { 480 rt = NULL; 481 } else 482 return rt; 483 484 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 485 if (err) 486 goto relookup_failed; 487 488 if (inet_addr_type_dev_table(net, skb_in->dev, 489 fl4_dec.saddr) == RTN_LOCAL) { 490 rt2 = __ip_route_output_key(net, &fl4_dec); 491 if (IS_ERR(rt2)) 492 err = PTR_ERR(rt2); 493 } else { 494 struct flowi4 fl4_2 = {}; 495 unsigned long orefdst; 496 497 fl4_2.daddr = fl4_dec.saddr; 498 rt2 = ip_route_output_key(net, &fl4_2); 499 if (IS_ERR(rt2)) { 500 err = PTR_ERR(rt2); 501 goto relookup_failed; 502 } 503 /* Ugh! */ 504 orefdst = skb_in->_skb_refdst; /* save old refdst */ 505 skb_dst_set(skb_in, NULL); 506 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 507 RT_TOS(tos), rt2->dst.dev); 508 509 dst_release(&rt2->dst); 510 rt2 = skb_rtable(skb_in); 511 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 512 } 513 514 if (err) 515 goto relookup_failed; 516 517 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 518 flowi4_to_flowi(&fl4_dec), NULL, 519 XFRM_LOOKUP_ICMP); 520 if (!IS_ERR(rt2)) { 521 dst_release(&rt->dst); 522 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 523 rt = rt2; 524 } else if (PTR_ERR(rt2) == -EPERM) { 525 if (rt) 526 dst_release(&rt->dst); 527 return rt2; 528 } else { 529 err = PTR_ERR(rt2); 530 goto relookup_failed; 531 } 532 return rt; 533 534 relookup_failed: 535 if (rt) 536 return rt; 537 return ERR_PTR(err); 538 } 539 540 /* 541 * Send an ICMP message in response to a situation 542 * 543 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 544 * MAY send more (we do). 545 * MUST NOT change this header information. 546 * MUST NOT reply to a multicast/broadcast IP address. 547 * MUST NOT reply to a multicast/broadcast MAC address. 548 * MUST reply to only the first fragment. 549 */ 550 551 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) 552 { 553 struct iphdr *iph; 554 int room; 555 struct icmp_bxm *icmp_param; 556 struct rtable *rt = skb_rtable(skb_in); 557 struct ipcm_cookie ipc; 558 struct flowi4 fl4; 559 __be32 saddr; 560 u8 tos; 561 u32 mark; 562 struct net *net; 563 struct sock *sk; 564 565 if (!rt) 566 goto out; 567 net = dev_net(rt->dst.dev); 568 569 /* 570 * Find the original header. It is expected to be valid, of course. 571 * Check this, icmp_send is called from the most obscure devices 572 * sometimes. 573 */ 574 iph = ip_hdr(skb_in); 575 576 if ((u8 *)iph < skb_in->head || 577 (skb_network_header(skb_in) + sizeof(*iph)) > 578 skb_tail_pointer(skb_in)) 579 goto out; 580 581 /* 582 * No replies to physical multicast/broadcast 583 */ 584 if (skb_in->pkt_type != PACKET_HOST) 585 goto out; 586 587 /* 588 * Now check at the protocol level 589 */ 590 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 591 goto out; 592 593 /* 594 * Only reply to fragment 0. We byte re-order the constant 595 * mask for efficiency. 596 */ 597 if (iph->frag_off & htons(IP_OFFSET)) 598 goto out; 599 600 /* 601 * If we send an ICMP error to an ICMP error a mess would result.. 602 */ 603 if (icmp_pointers[type].error) { 604 /* 605 * We are an error, check if we are replying to an 606 * ICMP error 607 */ 608 if (iph->protocol == IPPROTO_ICMP) { 609 u8 _inner_type, *itp; 610 611 itp = skb_header_pointer(skb_in, 612 skb_network_header(skb_in) + 613 (iph->ihl << 2) + 614 offsetof(struct icmphdr, 615 type) - 616 skb_in->data, 617 sizeof(_inner_type), 618 &_inner_type); 619 if (!itp) 620 goto out; 621 622 /* 623 * Assume any unknown ICMP type is an error. This 624 * isn't specified by the RFC, but think about it.. 625 */ 626 if (*itp > NR_ICMP_TYPES || 627 icmp_pointers[*itp].error) 628 goto out; 629 } 630 } 631 632 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC); 633 if (!icmp_param) 634 return; 635 636 sk = icmp_xmit_lock(net); 637 if (!sk) 638 goto out_free; 639 640 /* 641 * Construct source address and options. 642 */ 643 644 saddr = iph->daddr; 645 if (!(rt->rt_flags & RTCF_LOCAL)) { 646 struct net_device *dev = NULL; 647 648 rcu_read_lock(); 649 if (rt_is_input_route(rt) && 650 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 651 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 652 653 if (dev) 654 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 655 else 656 saddr = 0; 657 rcu_read_unlock(); 658 } 659 660 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 661 IPTOS_PREC_INTERNETCONTROL) : 662 iph->tos; 663 mark = IP4_REPLY_MARK(net, skb_in->mark); 664 665 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in)) 666 goto out_unlock; 667 668 669 /* 670 * Prepare data for ICMP header. 671 */ 672 673 icmp_param->data.icmph.type = type; 674 icmp_param->data.icmph.code = code; 675 icmp_param->data.icmph.un.gateway = info; 676 icmp_param->data.icmph.checksum = 0; 677 icmp_param->skb = skb_in; 678 icmp_param->offset = skb_network_offset(skb_in); 679 inet_sk(sk)->tos = tos; 680 sk->sk_mark = mark; 681 ipc.addr = iph->saddr; 682 ipc.opt = &icmp_param->replyopts.opt; 683 ipc.tx_flags = 0; 684 ipc.ttl = 0; 685 ipc.tos = -1; 686 687 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 688 type, code, icmp_param); 689 if (IS_ERR(rt)) 690 goto out_unlock; 691 692 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 693 goto ende; 694 695 /* RFC says return as much as we can without exceeding 576 bytes. */ 696 697 room = dst_mtu(&rt->dst); 698 if (room > 576) 699 room = 576; 700 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen; 701 room -= sizeof(struct icmphdr); 702 703 icmp_param->data_len = skb_in->len - icmp_param->offset; 704 if (icmp_param->data_len > room) 705 icmp_param->data_len = room; 706 icmp_param->head_len = sizeof(struct icmphdr); 707 708 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 709 ende: 710 ip_rt_put(rt); 711 out_unlock: 712 icmp_xmit_unlock(sk); 713 out_free: 714 kfree(icmp_param); 715 out:; 716 } 717 EXPORT_SYMBOL(icmp_send); 718 719 720 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 721 { 722 const struct iphdr *iph = (const struct iphdr *) skb->data; 723 const struct net_protocol *ipprot; 724 int protocol = iph->protocol; 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 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 731 return; 732 } 733 734 raw_icmp_error(skb, protocol, info); 735 736 ipprot = rcu_dereference(inet_protos[protocol]); 737 if (ipprot && ipprot->err_handler) 738 ipprot->err_handler(skb, info); 739 } 740 741 static bool icmp_tag_validation(int proto) 742 { 743 bool ok; 744 745 rcu_read_lock(); 746 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 747 rcu_read_unlock(); 748 return ok; 749 } 750 751 /* 752 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and 753 * ICMP_PARAMETERPROB. 754 */ 755 756 static bool icmp_unreach(struct sk_buff *skb) 757 { 758 const struct iphdr *iph; 759 struct icmphdr *icmph; 760 struct net *net; 761 u32 info = 0; 762 763 net = dev_net(skb_dst(skb)->dev); 764 765 /* 766 * Incomplete header ? 767 * Only checks for the IP header, there should be an 768 * additional check for longer headers in upper levels. 769 */ 770 771 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 772 goto out_err; 773 774 icmph = icmp_hdr(skb); 775 iph = (const struct iphdr *)skb->data; 776 777 if (iph->ihl < 5) /* Mangled header, drop. */ 778 goto out_err; 779 780 if (icmph->type == ICMP_DEST_UNREACH) { 781 switch (icmph->code & 15) { 782 case ICMP_NET_UNREACH: 783 case ICMP_HOST_UNREACH: 784 case ICMP_PROT_UNREACH: 785 case ICMP_PORT_UNREACH: 786 break; 787 case ICMP_FRAG_NEEDED: 788 /* for documentation of the ip_no_pmtu_disc 789 * values please see 790 * Documentation/networking/ip-sysctl.txt 791 */ 792 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 793 default: 794 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 795 &iph->daddr); 796 break; 797 case 2: 798 goto out; 799 case 3: 800 if (!icmp_tag_validation(iph->protocol)) 801 goto out; 802 /* fall through */ 803 case 0: 804 info = ntohs(icmph->un.frag.mtu); 805 } 806 break; 807 case ICMP_SR_FAILED: 808 net_dbg_ratelimited("%pI4: Source Route Failed\n", 809 &iph->daddr); 810 break; 811 default: 812 break; 813 } 814 if (icmph->code > NR_ICMP_UNREACH) 815 goto out; 816 } else if (icmph->type == ICMP_PARAMETERPROB) 817 info = ntohl(icmph->un.gateway) >> 24; 818 819 /* 820 * Throw it at our lower layers 821 * 822 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 823 * header. 824 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 825 * transport layer. 826 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 827 * transport layer. 828 */ 829 830 /* 831 * Check the other end isn't violating RFC 1122. Some routers send 832 * bogus responses to broadcast frames. If you see this message 833 * first check your netmask matches at both ends, if it does then 834 * get the other vendor to fix their kit. 835 */ 836 837 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 838 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 839 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 840 &ip_hdr(skb)->saddr, 841 icmph->type, icmph->code, 842 &iph->daddr, skb->dev->name); 843 goto out; 844 } 845 846 icmp_socket_deliver(skb, info); 847 848 out: 849 return true; 850 out_err: 851 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 852 return false; 853 } 854 855 856 /* 857 * Handle ICMP_REDIRECT. 858 */ 859 860 static bool icmp_redirect(struct sk_buff *skb) 861 { 862 if (skb->len < sizeof(struct iphdr)) { 863 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); 864 return false; 865 } 866 867 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 868 /* there aught to be a stat */ 869 return false; 870 } 871 872 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway); 873 return true; 874 } 875 876 /* 877 * Handle ICMP_ECHO ("ping") requests. 878 * 879 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 880 * requests. 881 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 882 * included in the reply. 883 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 884 * echo requests, MUST have default=NOT. 885 * See also WRT handling of options once they are done and working. 886 */ 887 888 static bool icmp_echo(struct sk_buff *skb) 889 { 890 struct net *net; 891 892 net = dev_net(skb_dst(skb)->dev); 893 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 894 struct icmp_bxm icmp_param; 895 896 icmp_param.data.icmph = *icmp_hdr(skb); 897 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 898 icmp_param.skb = skb; 899 icmp_param.offset = 0; 900 icmp_param.data_len = skb->len; 901 icmp_param.head_len = sizeof(struct icmphdr); 902 icmp_reply(&icmp_param, skb); 903 } 904 /* should there be an ICMP stat for ignored echos? */ 905 return true; 906 } 907 908 /* 909 * Handle ICMP Timestamp requests. 910 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 911 * SHOULD be in the kernel for minimum random latency. 912 * MUST be accurate to a few minutes. 913 * MUST be updated at least at 15Hz. 914 */ 915 static bool icmp_timestamp(struct sk_buff *skb) 916 { 917 struct timespec tv; 918 struct icmp_bxm icmp_param; 919 /* 920 * Too short. 921 */ 922 if (skb->len < 4) 923 goto out_err; 924 925 /* 926 * Fill in the current time as ms since midnight UT: 927 */ 928 getnstimeofday(&tv); 929 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + 930 tv.tv_nsec / NSEC_PER_MSEC); 931 icmp_param.data.times[2] = icmp_param.data.times[1]; 932 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) 933 BUG(); 934 icmp_param.data.icmph = *icmp_hdr(skb); 935 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 936 icmp_param.data.icmph.code = 0; 937 icmp_param.skb = skb; 938 icmp_param.offset = 0; 939 icmp_param.data_len = 0; 940 icmp_param.head_len = sizeof(struct icmphdr) + 12; 941 icmp_reply(&icmp_param, skb); 942 return true; 943 944 out_err: 945 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 946 return false; 947 } 948 949 static bool icmp_discard(struct sk_buff *skb) 950 { 951 /* pretend it was a success */ 952 return true; 953 } 954 955 /* 956 * Deal with incoming ICMP packets. 957 */ 958 int icmp_rcv(struct sk_buff *skb) 959 { 960 struct icmphdr *icmph; 961 struct rtable *rt = skb_rtable(skb); 962 struct net *net = dev_net(rt->dst.dev); 963 bool success; 964 965 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 966 struct sec_path *sp = skb_sec_path(skb); 967 int nh; 968 969 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 970 XFRM_STATE_ICMP)) 971 goto drop; 972 973 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 974 goto drop; 975 976 nh = skb_network_offset(skb); 977 skb_set_network_header(skb, sizeof(*icmph)); 978 979 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 980 goto drop; 981 982 skb_set_network_header(skb, nh); 983 } 984 985 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); 986 987 if (skb_checksum_simple_validate(skb)) 988 goto csum_error; 989 990 if (!pskb_pull(skb, sizeof(*icmph))) 991 goto error; 992 993 icmph = icmp_hdr(skb); 994 995 ICMPMSGIN_INC_STATS_BH(net, icmph->type); 996 /* 997 * 18 is the highest 'known' ICMP type. Anything else is a mystery 998 * 999 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1000 * discarded. 1001 */ 1002 if (icmph->type > NR_ICMP_TYPES) 1003 goto error; 1004 1005 1006 /* 1007 * Parse the ICMP message 1008 */ 1009 1010 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1011 /* 1012 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1013 * silently ignored (we let user decide with a sysctl). 1014 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1015 * discarded if to broadcast/multicast. 1016 */ 1017 if ((icmph->type == ICMP_ECHO || 1018 icmph->type == ICMP_TIMESTAMP) && 1019 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1020 goto error; 1021 } 1022 if (icmph->type != ICMP_ECHO && 1023 icmph->type != ICMP_TIMESTAMP && 1024 icmph->type != ICMP_ADDRESS && 1025 icmph->type != ICMP_ADDRESSREPLY) { 1026 goto error; 1027 } 1028 } 1029 1030 success = icmp_pointers[icmph->type].handler(skb); 1031 1032 if (success) { 1033 consume_skb(skb); 1034 return 0; 1035 } 1036 1037 drop: 1038 kfree_skb(skb); 1039 return 0; 1040 csum_error: 1041 ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS); 1042 error: 1043 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 1044 goto drop; 1045 } 1046 1047 void icmp_err(struct sk_buff *skb, u32 info) 1048 { 1049 struct iphdr *iph = (struct iphdr *)skb->data; 1050 int offset = iph->ihl<<2; 1051 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1052 int type = icmp_hdr(skb)->type; 1053 int code = icmp_hdr(skb)->code; 1054 struct net *net = dev_net(skb->dev); 1055 1056 /* 1057 * Use ping_err to handle all icmp errors except those 1058 * triggered by ICMP_ECHOREPLY which sent from kernel. 1059 */ 1060 if (icmph->type != ICMP_ECHOREPLY) { 1061 ping_err(skb, offset, info); 1062 return; 1063 } 1064 1065 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1066 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0); 1067 else if (type == ICMP_REDIRECT) 1068 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0); 1069 } 1070 1071 /* 1072 * This table is the definition of how we handle ICMP. 1073 */ 1074 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1075 [ICMP_ECHOREPLY] = { 1076 .handler = ping_rcv, 1077 }, 1078 [1] = { 1079 .handler = icmp_discard, 1080 .error = 1, 1081 }, 1082 [2] = { 1083 .handler = icmp_discard, 1084 .error = 1, 1085 }, 1086 [ICMP_DEST_UNREACH] = { 1087 .handler = icmp_unreach, 1088 .error = 1, 1089 }, 1090 [ICMP_SOURCE_QUENCH] = { 1091 .handler = icmp_unreach, 1092 .error = 1, 1093 }, 1094 [ICMP_REDIRECT] = { 1095 .handler = icmp_redirect, 1096 .error = 1, 1097 }, 1098 [6] = { 1099 .handler = icmp_discard, 1100 .error = 1, 1101 }, 1102 [7] = { 1103 .handler = icmp_discard, 1104 .error = 1, 1105 }, 1106 [ICMP_ECHO] = { 1107 .handler = icmp_echo, 1108 }, 1109 [9] = { 1110 .handler = icmp_discard, 1111 .error = 1, 1112 }, 1113 [10] = { 1114 .handler = icmp_discard, 1115 .error = 1, 1116 }, 1117 [ICMP_TIME_EXCEEDED] = { 1118 .handler = icmp_unreach, 1119 .error = 1, 1120 }, 1121 [ICMP_PARAMETERPROB] = { 1122 .handler = icmp_unreach, 1123 .error = 1, 1124 }, 1125 [ICMP_TIMESTAMP] = { 1126 .handler = icmp_timestamp, 1127 }, 1128 [ICMP_TIMESTAMPREPLY] = { 1129 .handler = icmp_discard, 1130 }, 1131 [ICMP_INFO_REQUEST] = { 1132 .handler = icmp_discard, 1133 }, 1134 [ICMP_INFO_REPLY] = { 1135 .handler = icmp_discard, 1136 }, 1137 [ICMP_ADDRESS] = { 1138 .handler = icmp_discard, 1139 }, 1140 [ICMP_ADDRESSREPLY] = { 1141 .handler = icmp_discard, 1142 }, 1143 }; 1144 1145 static void __net_exit icmp_sk_exit(struct net *net) 1146 { 1147 int i; 1148 1149 for_each_possible_cpu(i) 1150 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1151 free_percpu(net->ipv4.icmp_sk); 1152 net->ipv4.icmp_sk = NULL; 1153 } 1154 1155 static int __net_init icmp_sk_init(struct net *net) 1156 { 1157 int i, err; 1158 1159 net->ipv4.icmp_sk = alloc_percpu(struct sock *); 1160 if (!net->ipv4.icmp_sk) 1161 return -ENOMEM; 1162 1163 for_each_possible_cpu(i) { 1164 struct sock *sk; 1165 1166 err = inet_ctl_sock_create(&sk, PF_INET, 1167 SOCK_RAW, IPPROTO_ICMP, net); 1168 if (err < 0) 1169 goto fail; 1170 1171 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk; 1172 1173 /* Enough space for 2 64K ICMP packets, including 1174 * sk_buff/skb_shared_info struct overhead. 1175 */ 1176 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1177 1178 /* 1179 * Speedup sock_wfree() 1180 */ 1181 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1182 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1183 } 1184 1185 /* Control parameters for ECHO replies. */ 1186 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1187 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1188 1189 /* Control parameter - ignore bogus broadcast responses? */ 1190 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1191 1192 /* 1193 * Configurable global rate limit. 1194 * 1195 * ratelimit defines tokens/packet consumed for dst->rate_token 1196 * bucket ratemask defines which icmp types are ratelimited by 1197 * setting it's bit position. 1198 * 1199 * default: 1200 * dest unreachable (3), source quench (4), 1201 * time exceeded (11), parameter problem (12) 1202 */ 1203 1204 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1205 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1206 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1207 1208 return 0; 1209 1210 fail: 1211 for_each_possible_cpu(i) 1212 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1213 free_percpu(net->ipv4.icmp_sk); 1214 return err; 1215 } 1216 1217 static struct pernet_operations __net_initdata icmp_sk_ops = { 1218 .init = icmp_sk_init, 1219 .exit = icmp_sk_exit, 1220 }; 1221 1222 int __init icmp_init(void) 1223 { 1224 return register_pernet_subsys(&icmp_sk_ops); 1225 } 1226