1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * NET3: Implementation of the ICMP protocol layer. 4 * 5 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 6 * 7 * Some of the function names and the icmp unreach table for this 8 * module were derived from [icmp.c 1.0.11 06/02/93] by 9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 10 * Other than that this module is a complete rewrite. 11 * 12 * Fixes: 13 * Clemens Fruhwirth : introduce global icmp rate limiting 14 * with icmp type masking ability instead 15 * of broken per type icmp timeouts. 16 * Mike Shaver : RFC1122 checks. 17 * Alan Cox : Multicast ping reply as self. 18 * Alan Cox : Fix atomicity lockup in ip_build_xmit 19 * call. 20 * Alan Cox : Added 216,128 byte paths to the MTU 21 * code. 22 * Martin Mares : RFC1812 checks. 23 * Martin Mares : Can be configured to follow redirects 24 * if acting as a router _without_ a 25 * routing protocol (RFC 1812). 26 * Martin Mares : Echo requests may be configured to 27 * be ignored (RFC 1812). 28 * Martin Mares : Limitation of ICMP error message 29 * transmit rate (RFC 1812). 30 * Martin Mares : TOS and Precedence set correctly 31 * (RFC 1812). 32 * Martin Mares : Now copying as much data from the 33 * original packet as we can without 34 * exceeding 576 bytes (RFC 1812). 35 * Willy Konynenberg : Transparent proxying support. 36 * Keith Owens : RFC1191 correction for 4.2BSD based 37 * path MTU bug. 38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 39 * valid (RFC 1812). 40 * Andi Kleen : Check all packet lengths properly 41 * and moved all kfree_skb() up to 42 * icmp_rcv. 43 * Andi Kleen : Move the rate limit bookkeeping 44 * into the dest entry and use a token 45 * bucket filter (thanks to ANK). Make 46 * the rates sysctl configurable. 47 * Yu Tianli : Fixed two ugly bugs in icmp_send 48 * - IP option length was accounted wrongly 49 * - ICMP header length was not accounted 50 * at all. 51 * Tristan Greaves : Added sysctl option to ignore bogus 52 * broadcast responses from broken routers. 53 * 54 * To Fix: 55 * 56 * - Should use skb_pull() instead of all the manual checking. 57 * This would also greatly simply some upper layer error handlers. --AK 58 */ 59 60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 61 62 #include <linux/module.h> 63 #include <linux/types.h> 64 #include <linux/jiffies.h> 65 #include <linux/kernel.h> 66 #include <linux/fcntl.h> 67 #include <linux/socket.h> 68 #include <linux/in.h> 69 #include <linux/inet.h> 70 #include <linux/inetdevice.h> 71 #include <linux/netdevice.h> 72 #include <linux/string.h> 73 #include <linux/netfilter_ipv4.h> 74 #include <linux/slab.h> 75 #include <net/snmp.h> 76 #include <net/ip.h> 77 #include <net/route.h> 78 #include <net/protocol.h> 79 #include <net/icmp.h> 80 #include <net/tcp.h> 81 #include <net/udp.h> 82 #include <net/raw.h> 83 #include <net/ping.h> 84 #include <linux/skbuff.h> 85 #include <net/sock.h> 86 #include <linux/errno.h> 87 #include <linux/timer.h> 88 #include <linux/init.h> 89 #include <linux/uaccess.h> 90 #include <net/checksum.h> 91 #include <net/xfrm.h> 92 #include <net/inet_common.h> 93 #include <net/ip_fib.h> 94 #include <net/l3mdev.h> 95 96 /* 97 * Build xmit assembly blocks 98 */ 99 100 struct icmp_bxm { 101 struct sk_buff *skb; 102 int offset; 103 int data_len; 104 105 struct { 106 struct icmphdr icmph; 107 __be32 times[3]; 108 } data; 109 int head_len; 110 struct ip_options_data replyopts; 111 }; 112 113 /* An array of errno for error messages from dest unreach. */ 114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 115 116 const struct icmp_err icmp_err_convert[] = { 117 { 118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 119 .fatal = 0, 120 }, 121 { 122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 123 .fatal = 0, 124 }, 125 { 126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 127 .fatal = 1, 128 }, 129 { 130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 131 .fatal = 1, 132 }, 133 { 134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 135 .fatal = 0, 136 }, 137 { 138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 139 .fatal = 0, 140 }, 141 { 142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 143 .fatal = 1, 144 }, 145 { 146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 147 .fatal = 1, 148 }, 149 { 150 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 151 .fatal = 1, 152 }, 153 { 154 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 155 .fatal = 1, 156 }, 157 { 158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 159 .fatal = 1, 160 }, 161 { 162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 163 .fatal = 0, 164 }, 165 { 166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 167 .fatal = 0, 168 }, 169 { 170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 171 .fatal = 1, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 175 .fatal = 1, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 179 .fatal = 1, 180 }, 181 }; 182 EXPORT_SYMBOL(icmp_err_convert); 183 184 /* 185 * ICMP control array. This specifies what to do with each ICMP. 186 */ 187 188 struct icmp_control { 189 bool (*handler)(struct sk_buff *skb); 190 short error; /* This ICMP is classed as an error message */ 191 }; 192 193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 194 195 /* 196 * The ICMP socket(s). This is the most convenient way to flow control 197 * our ICMP output as well as maintain a clean interface throughout 198 * all layers. All Socketless IP sends will soon be gone. 199 * 200 * On SMP we have one ICMP socket per-cpu. 201 */ 202 static struct sock *icmp_sk(struct net *net) 203 { 204 return this_cpu_read(*net->ipv4.icmp_sk); 205 } 206 207 /* Called with BH disabled */ 208 static inline struct sock *icmp_xmit_lock(struct net *net) 209 { 210 struct sock *sk; 211 212 sk = icmp_sk(net); 213 214 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 215 /* This can happen if the output path signals a 216 * dst_link_failure() for an outgoing ICMP packet. 217 */ 218 return NULL; 219 } 220 return sk; 221 } 222 223 static inline void icmp_xmit_unlock(struct sock *sk) 224 { 225 spin_unlock(&sk->sk_lock.slock); 226 } 227 228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 229 int sysctl_icmp_msgs_burst __read_mostly = 50; 230 231 static struct { 232 spinlock_t lock; 233 u32 credit; 234 u32 stamp; 235 } icmp_global = { 236 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 237 }; 238 239 /** 240 * icmp_global_allow - Are we allowed to send one more ICMP message ? 241 * 242 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec. 243 * Returns false if we reached the limit and can not send another packet. 244 * Note: called with BH disabled 245 */ 246 bool icmp_global_allow(void) 247 { 248 u32 credit, delta, incr = 0, now = (u32)jiffies; 249 bool rc = false; 250 251 /* Check if token bucket is empty and cannot be refilled 252 * without taking the spinlock. 253 */ 254 if (!icmp_global.credit) { 255 delta = min_t(u32, now - icmp_global.stamp, HZ); 256 if (delta < HZ / 50) 257 return false; 258 } 259 260 spin_lock(&icmp_global.lock); 261 delta = min_t(u32, now - icmp_global.stamp, HZ); 262 if (delta >= HZ / 50) { 263 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 264 if (incr) 265 icmp_global.stamp = now; 266 } 267 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 268 if (credit) { 269 credit--; 270 rc = true; 271 } 272 icmp_global.credit = credit; 273 spin_unlock(&icmp_global.lock); 274 return rc; 275 } 276 EXPORT_SYMBOL(icmp_global_allow); 277 278 static bool icmpv4_mask_allow(struct net *net, int type, int code) 279 { 280 if (type > NR_ICMP_TYPES) 281 return true; 282 283 /* Don't limit PMTU discovery. */ 284 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 285 return true; 286 287 /* Limit if icmp type is enabled in ratemask. */ 288 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask)) 289 return true; 290 291 return false; 292 } 293 294 static bool icmpv4_global_allow(struct net *net, int type, int code) 295 { 296 if (icmpv4_mask_allow(net, type, code)) 297 return true; 298 299 if (icmp_global_allow()) 300 return true; 301 302 return false; 303 } 304 305 /* 306 * Send an ICMP frame. 307 */ 308 309 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 310 struct flowi4 *fl4, int type, int code) 311 { 312 struct dst_entry *dst = &rt->dst; 313 struct inet_peer *peer; 314 bool rc = true; 315 int vif; 316 317 if (icmpv4_mask_allow(net, type, code)) 318 goto out; 319 320 /* No rate limit on loopback */ 321 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 322 goto out; 323 324 vif = l3mdev_master_ifindex(dst->dev); 325 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 326 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit); 327 if (peer) 328 inet_putpeer(peer); 329 out: 330 return rc; 331 } 332 333 /* 334 * Maintain the counters used in the SNMP statistics for outgoing ICMP 335 */ 336 void icmp_out_count(struct net *net, unsigned char type) 337 { 338 ICMPMSGOUT_INC_STATS(net, type); 339 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 340 } 341 342 /* 343 * Checksum each fragment, and on the first include the headers and final 344 * checksum. 345 */ 346 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 347 struct sk_buff *skb) 348 { 349 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 350 __wsum csum; 351 352 csum = skb_copy_and_csum_bits(icmp_param->skb, 353 icmp_param->offset + offset, 354 to, len, 0); 355 356 skb->csum = csum_block_add(skb->csum, csum, odd); 357 if (icmp_pointers[icmp_param->data.icmph.type].error) 358 nf_ct_attach(skb, icmp_param->skb); 359 return 0; 360 } 361 362 static void icmp_push_reply(struct icmp_bxm *icmp_param, 363 struct flowi4 *fl4, 364 struct ipcm_cookie *ipc, struct rtable **rt) 365 { 366 struct sock *sk; 367 struct sk_buff *skb; 368 369 sk = icmp_sk(dev_net((*rt)->dst.dev)); 370 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 371 icmp_param->data_len+icmp_param->head_len, 372 icmp_param->head_len, 373 ipc, rt, MSG_DONTWAIT) < 0) { 374 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 375 ip_flush_pending_frames(sk); 376 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 377 struct icmphdr *icmph = icmp_hdr(skb); 378 __wsum csum = 0; 379 struct sk_buff *skb1; 380 381 skb_queue_walk(&sk->sk_write_queue, skb1) { 382 csum = csum_add(csum, skb1->csum); 383 } 384 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 385 (char *)icmph, 386 icmp_param->head_len, csum); 387 icmph->checksum = csum_fold(csum); 388 skb->ip_summed = CHECKSUM_NONE; 389 ip_push_pending_frames(sk, fl4); 390 } 391 } 392 393 /* 394 * Driving logic for building and sending ICMP messages. 395 */ 396 397 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 398 { 399 struct ipcm_cookie ipc; 400 struct rtable *rt = skb_rtable(skb); 401 struct net *net = dev_net(rt->dst.dev); 402 struct flowi4 fl4; 403 struct sock *sk; 404 struct inet_sock *inet; 405 __be32 daddr, saddr; 406 u32 mark = IP4_REPLY_MARK(net, skb->mark); 407 int type = icmp_param->data.icmph.type; 408 int code = icmp_param->data.icmph.code; 409 410 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 411 return; 412 413 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 414 local_bh_disable(); 415 416 /* global icmp_msgs_per_sec */ 417 if (!icmpv4_global_allow(net, type, code)) 418 goto out_bh_enable; 419 420 sk = icmp_xmit_lock(net); 421 if (!sk) 422 goto out_bh_enable; 423 inet = inet_sk(sk); 424 425 icmp_param->data.icmph.checksum = 0; 426 427 ipcm_init(&ipc); 428 inet->tos = ip_hdr(skb)->tos; 429 sk->sk_mark = mark; 430 daddr = ipc.addr = ip_hdr(skb)->saddr; 431 saddr = fib_compute_spec_dst(skb); 432 433 if (icmp_param->replyopts.opt.opt.optlen) { 434 ipc.opt = &icmp_param->replyopts.opt; 435 if (ipc.opt->opt.srr) 436 daddr = icmp_param->replyopts.opt.opt.faddr; 437 } 438 memset(&fl4, 0, sizeof(fl4)); 439 fl4.daddr = daddr; 440 fl4.saddr = saddr; 441 fl4.flowi4_mark = mark; 442 fl4.flowi4_uid = sock_net_uid(net, NULL); 443 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 444 fl4.flowi4_proto = IPPROTO_ICMP; 445 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 446 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 447 rt = ip_route_output_key(net, &fl4); 448 if (IS_ERR(rt)) 449 goto out_unlock; 450 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 451 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 452 ip_rt_put(rt); 453 out_unlock: 454 icmp_xmit_unlock(sk); 455 out_bh_enable: 456 local_bh_enable(); 457 } 458 459 static struct rtable *icmp_route_lookup(struct net *net, 460 struct flowi4 *fl4, 461 struct sk_buff *skb_in, 462 const struct iphdr *iph, 463 __be32 saddr, u8 tos, u32 mark, 464 int type, int code, 465 struct icmp_bxm *param) 466 { 467 struct rtable *rt, *rt2; 468 struct flowi4 fl4_dec; 469 int err; 470 471 memset(fl4, 0, sizeof(*fl4)); 472 fl4->daddr = (param->replyopts.opt.opt.srr ? 473 param->replyopts.opt.opt.faddr : iph->saddr); 474 fl4->saddr = saddr; 475 fl4->flowi4_mark = mark; 476 fl4->flowi4_uid = sock_net_uid(net, NULL); 477 fl4->flowi4_tos = RT_TOS(tos); 478 fl4->flowi4_proto = IPPROTO_ICMP; 479 fl4->fl4_icmp_type = type; 480 fl4->fl4_icmp_code = code; 481 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev); 482 483 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 484 rt = ip_route_output_key_hash(net, fl4, skb_in); 485 if (IS_ERR(rt)) 486 return rt; 487 488 /* No need to clone since we're just using its address. */ 489 rt2 = rt; 490 491 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 492 flowi4_to_flowi(fl4), NULL, 0); 493 if (!IS_ERR(rt)) { 494 if (rt != rt2) 495 return rt; 496 } else if (PTR_ERR(rt) == -EPERM) { 497 rt = NULL; 498 } else 499 return rt; 500 501 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 502 if (err) 503 goto relookup_failed; 504 505 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev, 506 fl4_dec.saddr) == RTN_LOCAL) { 507 rt2 = __ip_route_output_key(net, &fl4_dec); 508 if (IS_ERR(rt2)) 509 err = PTR_ERR(rt2); 510 } else { 511 struct flowi4 fl4_2 = {}; 512 unsigned long orefdst; 513 514 fl4_2.daddr = fl4_dec.saddr; 515 rt2 = ip_route_output_key(net, &fl4_2); 516 if (IS_ERR(rt2)) { 517 err = PTR_ERR(rt2); 518 goto relookup_failed; 519 } 520 /* Ugh! */ 521 orefdst = skb_in->_skb_refdst; /* save old refdst */ 522 skb_dst_set(skb_in, NULL); 523 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 524 RT_TOS(tos), rt2->dst.dev); 525 526 dst_release(&rt2->dst); 527 rt2 = skb_rtable(skb_in); 528 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 529 } 530 531 if (err) 532 goto relookup_failed; 533 534 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 535 flowi4_to_flowi(&fl4_dec), NULL, 536 XFRM_LOOKUP_ICMP); 537 if (!IS_ERR(rt2)) { 538 dst_release(&rt->dst); 539 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 540 rt = rt2; 541 } else if (PTR_ERR(rt2) == -EPERM) { 542 if (rt) 543 dst_release(&rt->dst); 544 return rt2; 545 } else { 546 err = PTR_ERR(rt2); 547 goto relookup_failed; 548 } 549 return rt; 550 551 relookup_failed: 552 if (rt) 553 return rt; 554 return ERR_PTR(err); 555 } 556 557 /* 558 * Send an ICMP message in response to a situation 559 * 560 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 561 * MAY send more (we do). 562 * MUST NOT change this header information. 563 * MUST NOT reply to a multicast/broadcast IP address. 564 * MUST NOT reply to a multicast/broadcast MAC address. 565 * MUST reply to only the first fragment. 566 */ 567 568 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 569 const struct ip_options *opt) 570 { 571 struct iphdr *iph; 572 int room; 573 struct icmp_bxm icmp_param; 574 struct rtable *rt = skb_rtable(skb_in); 575 struct ipcm_cookie ipc; 576 struct flowi4 fl4; 577 __be32 saddr; 578 u8 tos; 579 u32 mark; 580 struct net *net; 581 struct sock *sk; 582 583 if (!rt) 584 goto out; 585 586 if (rt->dst.dev) 587 net = dev_net(rt->dst.dev); 588 else if (skb_in->dev) 589 net = dev_net(skb_in->dev); 590 else 591 goto out; 592 593 /* 594 * Find the original header. It is expected to be valid, of course. 595 * Check this, icmp_send is called from the most obscure devices 596 * sometimes. 597 */ 598 iph = ip_hdr(skb_in); 599 600 if ((u8 *)iph < skb_in->head || 601 (skb_network_header(skb_in) + sizeof(*iph)) > 602 skb_tail_pointer(skb_in)) 603 goto out; 604 605 /* 606 * No replies to physical multicast/broadcast 607 */ 608 if (skb_in->pkt_type != PACKET_HOST) 609 goto out; 610 611 /* 612 * Now check at the protocol level 613 */ 614 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 615 goto out; 616 617 /* 618 * Only reply to fragment 0. We byte re-order the constant 619 * mask for efficiency. 620 */ 621 if (iph->frag_off & htons(IP_OFFSET)) 622 goto out; 623 624 /* 625 * If we send an ICMP error to an ICMP error a mess would result.. 626 */ 627 if (icmp_pointers[type].error) { 628 /* 629 * We are an error, check if we are replying to an 630 * ICMP error 631 */ 632 if (iph->protocol == IPPROTO_ICMP) { 633 u8 _inner_type, *itp; 634 635 itp = skb_header_pointer(skb_in, 636 skb_network_header(skb_in) + 637 (iph->ihl << 2) + 638 offsetof(struct icmphdr, 639 type) - 640 skb_in->data, 641 sizeof(_inner_type), 642 &_inner_type); 643 if (!itp) 644 goto out; 645 646 /* 647 * Assume any unknown ICMP type is an error. This 648 * isn't specified by the RFC, but think about it.. 649 */ 650 if (*itp > NR_ICMP_TYPES || 651 icmp_pointers[*itp].error) 652 goto out; 653 } 654 } 655 656 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 657 local_bh_disable(); 658 659 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 660 * incoming dev is loopback. If outgoing dev change to not be 661 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 662 */ 663 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 664 !icmpv4_global_allow(net, type, code)) 665 goto out_bh_enable; 666 667 sk = icmp_xmit_lock(net); 668 if (!sk) 669 goto out_bh_enable; 670 671 /* 672 * Construct source address and options. 673 */ 674 675 saddr = iph->daddr; 676 if (!(rt->rt_flags & RTCF_LOCAL)) { 677 struct net_device *dev = NULL; 678 679 rcu_read_lock(); 680 if (rt_is_input_route(rt) && 681 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 682 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 683 684 if (dev) 685 saddr = inet_select_addr(dev, iph->saddr, 686 RT_SCOPE_LINK); 687 else 688 saddr = 0; 689 rcu_read_unlock(); 690 } 691 692 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 693 IPTOS_PREC_INTERNETCONTROL) : 694 iph->tos; 695 mark = IP4_REPLY_MARK(net, skb_in->mark); 696 697 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 698 goto out_unlock; 699 700 701 /* 702 * Prepare data for ICMP header. 703 */ 704 705 icmp_param.data.icmph.type = type; 706 icmp_param.data.icmph.code = code; 707 icmp_param.data.icmph.un.gateway = info; 708 icmp_param.data.icmph.checksum = 0; 709 icmp_param.skb = skb_in; 710 icmp_param.offset = skb_network_offset(skb_in); 711 inet_sk(sk)->tos = tos; 712 sk->sk_mark = mark; 713 ipcm_init(&ipc); 714 ipc.addr = iph->saddr; 715 ipc.opt = &icmp_param.replyopts.opt; 716 717 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 718 type, code, &icmp_param); 719 if (IS_ERR(rt)) 720 goto out_unlock; 721 722 /* peer icmp_ratelimit */ 723 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 724 goto ende; 725 726 /* RFC says return as much as we can without exceeding 576 bytes. */ 727 728 room = dst_mtu(&rt->dst); 729 if (room > 576) 730 room = 576; 731 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 732 room -= sizeof(struct icmphdr); 733 734 icmp_param.data_len = skb_in->len - icmp_param.offset; 735 if (icmp_param.data_len > room) 736 icmp_param.data_len = room; 737 icmp_param.head_len = sizeof(struct icmphdr); 738 739 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt); 740 ende: 741 ip_rt_put(rt); 742 out_unlock: 743 icmp_xmit_unlock(sk); 744 out_bh_enable: 745 local_bh_enable(); 746 out:; 747 } 748 EXPORT_SYMBOL(__icmp_send); 749 750 751 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 752 { 753 const struct iphdr *iph = (const struct iphdr *) skb->data; 754 const struct net_protocol *ipprot; 755 int protocol = iph->protocol; 756 757 /* Checkin full IP header plus 8 bytes of protocol to 758 * avoid additional coding at protocol handlers. 759 */ 760 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 761 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 762 return; 763 } 764 765 raw_icmp_error(skb, protocol, info); 766 767 ipprot = rcu_dereference(inet_protos[protocol]); 768 if (ipprot && ipprot->err_handler) 769 ipprot->err_handler(skb, info); 770 } 771 772 static bool icmp_tag_validation(int proto) 773 { 774 bool ok; 775 776 rcu_read_lock(); 777 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 778 rcu_read_unlock(); 779 return ok; 780 } 781 782 /* 783 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 784 * ICMP_PARAMETERPROB. 785 */ 786 787 static bool icmp_unreach(struct sk_buff *skb) 788 { 789 const struct iphdr *iph; 790 struct icmphdr *icmph; 791 struct net *net; 792 u32 info = 0; 793 794 net = dev_net(skb_dst(skb)->dev); 795 796 /* 797 * Incomplete header ? 798 * Only checks for the IP header, there should be an 799 * additional check for longer headers in upper levels. 800 */ 801 802 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 803 goto out_err; 804 805 icmph = icmp_hdr(skb); 806 iph = (const struct iphdr *)skb->data; 807 808 if (iph->ihl < 5) /* Mangled header, drop. */ 809 goto out_err; 810 811 switch (icmph->type) { 812 case ICMP_DEST_UNREACH: 813 switch (icmph->code & 15) { 814 case ICMP_NET_UNREACH: 815 case ICMP_HOST_UNREACH: 816 case ICMP_PROT_UNREACH: 817 case ICMP_PORT_UNREACH: 818 break; 819 case ICMP_FRAG_NEEDED: 820 /* for documentation of the ip_no_pmtu_disc 821 * values please see 822 * Documentation/networking/ip-sysctl.txt 823 */ 824 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 825 default: 826 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 827 &iph->daddr); 828 break; 829 case 2: 830 goto out; 831 case 3: 832 if (!icmp_tag_validation(iph->protocol)) 833 goto out; 834 /* fall through */ 835 case 0: 836 info = ntohs(icmph->un.frag.mtu); 837 } 838 break; 839 case ICMP_SR_FAILED: 840 net_dbg_ratelimited("%pI4: Source Route Failed\n", 841 &iph->daddr); 842 break; 843 default: 844 break; 845 } 846 if (icmph->code > NR_ICMP_UNREACH) 847 goto out; 848 break; 849 case ICMP_PARAMETERPROB: 850 info = ntohl(icmph->un.gateway) >> 24; 851 break; 852 case ICMP_TIME_EXCEEDED: 853 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 854 if (icmph->code == ICMP_EXC_FRAGTIME) 855 goto out; 856 break; 857 } 858 859 /* 860 * Throw it at our lower layers 861 * 862 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 863 * header. 864 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 865 * transport layer. 866 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 867 * transport layer. 868 */ 869 870 /* 871 * Check the other end isn't violating RFC 1122. Some routers send 872 * bogus responses to broadcast frames. If you see this message 873 * first check your netmask matches at both ends, if it does then 874 * get the other vendor to fix their kit. 875 */ 876 877 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 878 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 879 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 880 &ip_hdr(skb)->saddr, 881 icmph->type, icmph->code, 882 &iph->daddr, skb->dev->name); 883 goto out; 884 } 885 886 icmp_socket_deliver(skb, info); 887 888 out: 889 return true; 890 out_err: 891 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 892 return false; 893 } 894 895 896 /* 897 * Handle ICMP_REDIRECT. 898 */ 899 900 static bool icmp_redirect(struct sk_buff *skb) 901 { 902 if (skb->len < sizeof(struct iphdr)) { 903 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 904 return false; 905 } 906 907 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 908 /* there aught to be a stat */ 909 return false; 910 } 911 912 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 913 return true; 914 } 915 916 /* 917 * Handle ICMP_ECHO ("ping") requests. 918 * 919 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 920 * requests. 921 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 922 * included in the reply. 923 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 924 * echo requests, MUST have default=NOT. 925 * See also WRT handling of options once they are done and working. 926 */ 927 928 static bool icmp_echo(struct sk_buff *skb) 929 { 930 struct net *net; 931 932 net = dev_net(skb_dst(skb)->dev); 933 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 934 struct icmp_bxm icmp_param; 935 936 icmp_param.data.icmph = *icmp_hdr(skb); 937 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 938 icmp_param.skb = skb; 939 icmp_param.offset = 0; 940 icmp_param.data_len = skb->len; 941 icmp_param.head_len = sizeof(struct icmphdr); 942 icmp_reply(&icmp_param, skb); 943 } 944 /* should there be an ICMP stat for ignored echos? */ 945 return true; 946 } 947 948 /* 949 * Handle ICMP Timestamp requests. 950 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 951 * SHOULD be in the kernel for minimum random latency. 952 * MUST be accurate to a few minutes. 953 * MUST be updated at least at 15Hz. 954 */ 955 static bool icmp_timestamp(struct sk_buff *skb) 956 { 957 struct icmp_bxm icmp_param; 958 /* 959 * Too short. 960 */ 961 if (skb->len < 4) 962 goto out_err; 963 964 /* 965 * Fill in the current time as ms since midnight UT: 966 */ 967 icmp_param.data.times[1] = inet_current_timestamp(); 968 icmp_param.data.times[2] = icmp_param.data.times[1]; 969 970 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 971 972 icmp_param.data.icmph = *icmp_hdr(skb); 973 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 974 icmp_param.data.icmph.code = 0; 975 icmp_param.skb = skb; 976 icmp_param.offset = 0; 977 icmp_param.data_len = 0; 978 icmp_param.head_len = sizeof(struct icmphdr) + 12; 979 icmp_reply(&icmp_param, skb); 980 return true; 981 982 out_err: 983 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 984 return false; 985 } 986 987 static bool icmp_discard(struct sk_buff *skb) 988 { 989 /* pretend it was a success */ 990 return true; 991 } 992 993 /* 994 * Deal with incoming ICMP packets. 995 */ 996 int icmp_rcv(struct sk_buff *skb) 997 { 998 struct icmphdr *icmph; 999 struct rtable *rt = skb_rtable(skb); 1000 struct net *net = dev_net(rt->dst.dev); 1001 bool success; 1002 1003 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1004 struct sec_path *sp = skb_sec_path(skb); 1005 int nh; 1006 1007 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1008 XFRM_STATE_ICMP)) 1009 goto drop; 1010 1011 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1012 goto drop; 1013 1014 nh = skb_network_offset(skb); 1015 skb_set_network_header(skb, sizeof(*icmph)); 1016 1017 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 1018 goto drop; 1019 1020 skb_set_network_header(skb, nh); 1021 } 1022 1023 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1024 1025 if (skb_checksum_simple_validate(skb)) 1026 goto csum_error; 1027 1028 if (!pskb_pull(skb, sizeof(*icmph))) 1029 goto error; 1030 1031 icmph = icmp_hdr(skb); 1032 1033 ICMPMSGIN_INC_STATS(net, icmph->type); 1034 /* 1035 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1036 * 1037 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1038 * discarded. 1039 */ 1040 if (icmph->type > NR_ICMP_TYPES) 1041 goto error; 1042 1043 1044 /* 1045 * Parse the ICMP message 1046 */ 1047 1048 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1049 /* 1050 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1051 * silently ignored (we let user decide with a sysctl). 1052 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1053 * discarded if to broadcast/multicast. 1054 */ 1055 if ((icmph->type == ICMP_ECHO || 1056 icmph->type == ICMP_TIMESTAMP) && 1057 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1058 goto error; 1059 } 1060 if (icmph->type != ICMP_ECHO && 1061 icmph->type != ICMP_TIMESTAMP && 1062 icmph->type != ICMP_ADDRESS && 1063 icmph->type != ICMP_ADDRESSREPLY) { 1064 goto error; 1065 } 1066 } 1067 1068 success = icmp_pointers[icmph->type].handler(skb); 1069 1070 if (success) { 1071 consume_skb(skb); 1072 return NET_RX_SUCCESS; 1073 } 1074 1075 drop: 1076 kfree_skb(skb); 1077 return NET_RX_DROP; 1078 csum_error: 1079 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1080 error: 1081 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1082 goto drop; 1083 } 1084 1085 int icmp_err(struct sk_buff *skb, u32 info) 1086 { 1087 struct iphdr *iph = (struct iphdr *)skb->data; 1088 int offset = iph->ihl<<2; 1089 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1090 int type = icmp_hdr(skb)->type; 1091 int code = icmp_hdr(skb)->code; 1092 struct net *net = dev_net(skb->dev); 1093 1094 /* 1095 * Use ping_err to handle all icmp errors except those 1096 * triggered by ICMP_ECHOREPLY which sent from kernel. 1097 */ 1098 if (icmph->type != ICMP_ECHOREPLY) { 1099 ping_err(skb, offset, info); 1100 return 0; 1101 } 1102 1103 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1104 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1105 else if (type == ICMP_REDIRECT) 1106 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1107 1108 return 0; 1109 } 1110 1111 /* 1112 * This table is the definition of how we handle ICMP. 1113 */ 1114 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1115 [ICMP_ECHOREPLY] = { 1116 .handler = ping_rcv, 1117 }, 1118 [1] = { 1119 .handler = icmp_discard, 1120 .error = 1, 1121 }, 1122 [2] = { 1123 .handler = icmp_discard, 1124 .error = 1, 1125 }, 1126 [ICMP_DEST_UNREACH] = { 1127 .handler = icmp_unreach, 1128 .error = 1, 1129 }, 1130 [ICMP_SOURCE_QUENCH] = { 1131 .handler = icmp_unreach, 1132 .error = 1, 1133 }, 1134 [ICMP_REDIRECT] = { 1135 .handler = icmp_redirect, 1136 .error = 1, 1137 }, 1138 [6] = { 1139 .handler = icmp_discard, 1140 .error = 1, 1141 }, 1142 [7] = { 1143 .handler = icmp_discard, 1144 .error = 1, 1145 }, 1146 [ICMP_ECHO] = { 1147 .handler = icmp_echo, 1148 }, 1149 [9] = { 1150 .handler = icmp_discard, 1151 .error = 1, 1152 }, 1153 [10] = { 1154 .handler = icmp_discard, 1155 .error = 1, 1156 }, 1157 [ICMP_TIME_EXCEEDED] = { 1158 .handler = icmp_unreach, 1159 .error = 1, 1160 }, 1161 [ICMP_PARAMETERPROB] = { 1162 .handler = icmp_unreach, 1163 .error = 1, 1164 }, 1165 [ICMP_TIMESTAMP] = { 1166 .handler = icmp_timestamp, 1167 }, 1168 [ICMP_TIMESTAMPREPLY] = { 1169 .handler = icmp_discard, 1170 }, 1171 [ICMP_INFO_REQUEST] = { 1172 .handler = icmp_discard, 1173 }, 1174 [ICMP_INFO_REPLY] = { 1175 .handler = icmp_discard, 1176 }, 1177 [ICMP_ADDRESS] = { 1178 .handler = icmp_discard, 1179 }, 1180 [ICMP_ADDRESSREPLY] = { 1181 .handler = icmp_discard, 1182 }, 1183 }; 1184 1185 static void __net_exit icmp_sk_exit(struct net *net) 1186 { 1187 int i; 1188 1189 for_each_possible_cpu(i) 1190 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1191 free_percpu(net->ipv4.icmp_sk); 1192 net->ipv4.icmp_sk = NULL; 1193 } 1194 1195 static int __net_init icmp_sk_init(struct net *net) 1196 { 1197 int i, err; 1198 1199 net->ipv4.icmp_sk = alloc_percpu(struct sock *); 1200 if (!net->ipv4.icmp_sk) 1201 return -ENOMEM; 1202 1203 for_each_possible_cpu(i) { 1204 struct sock *sk; 1205 1206 err = inet_ctl_sock_create(&sk, PF_INET, 1207 SOCK_RAW, IPPROTO_ICMP, net); 1208 if (err < 0) 1209 goto fail; 1210 1211 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk; 1212 1213 /* Enough space for 2 64K ICMP packets, including 1214 * sk_buff/skb_shared_info struct overhead. 1215 */ 1216 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1217 1218 /* 1219 * Speedup sock_wfree() 1220 */ 1221 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1222 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1223 } 1224 1225 /* Control parameters for ECHO replies. */ 1226 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1227 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1228 1229 /* Control parameter - ignore bogus broadcast responses? */ 1230 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1231 1232 /* 1233 * Configurable global rate limit. 1234 * 1235 * ratelimit defines tokens/packet consumed for dst->rate_token 1236 * bucket ratemask defines which icmp types are ratelimited by 1237 * setting it's bit position. 1238 * 1239 * default: 1240 * dest unreachable (3), source quench (4), 1241 * time exceeded (11), parameter problem (12) 1242 */ 1243 1244 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1245 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1246 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1247 1248 return 0; 1249 1250 fail: 1251 icmp_sk_exit(net); 1252 return err; 1253 } 1254 1255 static struct pernet_operations __net_initdata icmp_sk_ops = { 1256 .init = icmp_sk_init, 1257 .exit = icmp_sk_exit, 1258 }; 1259 1260 int __init icmp_init(void) 1261 { 1262 return register_pernet_subsys(&icmp_sk_ops); 1263 } 1264