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. The READ_ONCE() are paired 253 * with the following WRITE_ONCE() in this same function. 254 */ 255 if (!READ_ONCE(icmp_global.credit)) { 256 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 257 if (delta < HZ / 50) 258 return false; 259 } 260 261 spin_lock(&icmp_global.lock); 262 delta = min_t(u32, now - icmp_global.stamp, HZ); 263 if (delta >= HZ / 50) { 264 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 265 if (incr) 266 WRITE_ONCE(icmp_global.stamp, now); 267 } 268 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 269 if (credit) { 270 /* We want to use a credit of one in average, but need to randomize 271 * it for security reasons. 272 */ 273 credit = max_t(int, credit - prandom_u32_max(3), 0); 274 rc = true; 275 } 276 WRITE_ONCE(icmp_global.credit, credit); 277 spin_unlock(&icmp_global.lock); 278 return rc; 279 } 280 EXPORT_SYMBOL(icmp_global_allow); 281 282 static bool icmpv4_mask_allow(struct net *net, int type, int code) 283 { 284 if (type > NR_ICMP_TYPES) 285 return true; 286 287 /* Don't limit PMTU discovery. */ 288 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 289 return true; 290 291 /* Limit if icmp type is enabled in ratemask. */ 292 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask)) 293 return true; 294 295 return false; 296 } 297 298 static bool icmpv4_global_allow(struct net *net, int type, int code) 299 { 300 if (icmpv4_mask_allow(net, type, code)) 301 return true; 302 303 if (icmp_global_allow()) 304 return true; 305 306 return false; 307 } 308 309 /* 310 * Send an ICMP frame. 311 */ 312 313 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 314 struct flowi4 *fl4, int type, int code) 315 { 316 struct dst_entry *dst = &rt->dst; 317 struct inet_peer *peer; 318 bool rc = true; 319 int vif; 320 321 if (icmpv4_mask_allow(net, type, code)) 322 goto out; 323 324 /* No rate limit on loopback */ 325 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 326 goto out; 327 328 vif = l3mdev_master_ifindex(dst->dev); 329 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 330 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit); 331 if (peer) 332 inet_putpeer(peer); 333 out: 334 return rc; 335 } 336 337 /* 338 * Maintain the counters used in the SNMP statistics for outgoing ICMP 339 */ 340 void icmp_out_count(struct net *net, unsigned char type) 341 { 342 ICMPMSGOUT_INC_STATS(net, type); 343 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 344 } 345 346 /* 347 * Checksum each fragment, and on the first include the headers and final 348 * checksum. 349 */ 350 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 351 struct sk_buff *skb) 352 { 353 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 354 __wsum csum; 355 356 csum = skb_copy_and_csum_bits(icmp_param->skb, 357 icmp_param->offset + offset, 358 to, len); 359 360 skb->csum = csum_block_add(skb->csum, csum, odd); 361 if (icmp_pointers[icmp_param->data.icmph.type].error) 362 nf_ct_attach(skb, icmp_param->skb); 363 return 0; 364 } 365 366 static void icmp_push_reply(struct icmp_bxm *icmp_param, 367 struct flowi4 *fl4, 368 struct ipcm_cookie *ipc, struct rtable **rt) 369 { 370 struct sock *sk; 371 struct sk_buff *skb; 372 373 sk = icmp_sk(dev_net((*rt)->dst.dev)); 374 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 375 icmp_param->data_len+icmp_param->head_len, 376 icmp_param->head_len, 377 ipc, rt, MSG_DONTWAIT) < 0) { 378 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 379 ip_flush_pending_frames(sk); 380 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 381 struct icmphdr *icmph = icmp_hdr(skb); 382 __wsum csum; 383 struct sk_buff *skb1; 384 385 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 386 (char *)icmph, 387 icmp_param->head_len); 388 skb_queue_walk(&sk->sk_write_queue, skb1) { 389 csum = csum_add(csum, skb1->csum); 390 } 391 icmph->checksum = csum_fold(csum); 392 skb->ip_summed = CHECKSUM_NONE; 393 ip_push_pending_frames(sk, fl4); 394 } 395 } 396 397 /* 398 * Driving logic for building and sending ICMP messages. 399 */ 400 401 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 402 { 403 struct ipcm_cookie ipc; 404 struct rtable *rt = skb_rtable(skb); 405 struct net *net = dev_net(rt->dst.dev); 406 struct flowi4 fl4; 407 struct sock *sk; 408 struct inet_sock *inet; 409 __be32 daddr, saddr; 410 u32 mark = IP4_REPLY_MARK(net, skb->mark); 411 int type = icmp_param->data.icmph.type; 412 int code = icmp_param->data.icmph.code; 413 414 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 415 return; 416 417 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 418 local_bh_disable(); 419 420 /* global icmp_msgs_per_sec */ 421 if (!icmpv4_global_allow(net, type, code)) 422 goto out_bh_enable; 423 424 sk = icmp_xmit_lock(net); 425 if (!sk) 426 goto out_bh_enable; 427 inet = inet_sk(sk); 428 429 icmp_param->data.icmph.checksum = 0; 430 431 ipcm_init(&ipc); 432 inet->tos = ip_hdr(skb)->tos; 433 ipc.sockc.mark = mark; 434 daddr = ipc.addr = ip_hdr(skb)->saddr; 435 saddr = fib_compute_spec_dst(skb); 436 437 if (icmp_param->replyopts.opt.opt.optlen) { 438 ipc.opt = &icmp_param->replyopts.opt; 439 if (ipc.opt->opt.srr) 440 daddr = icmp_param->replyopts.opt.opt.faddr; 441 } 442 memset(&fl4, 0, sizeof(fl4)); 443 fl4.daddr = daddr; 444 fl4.saddr = saddr; 445 fl4.flowi4_mark = mark; 446 fl4.flowi4_uid = sock_net_uid(net, NULL); 447 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 448 fl4.flowi4_proto = IPPROTO_ICMP; 449 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 450 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 451 rt = ip_route_output_key(net, &fl4); 452 if (IS_ERR(rt)) 453 goto out_unlock; 454 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 455 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 456 ip_rt_put(rt); 457 out_unlock: 458 icmp_xmit_unlock(sk); 459 out_bh_enable: 460 local_bh_enable(); 461 } 462 463 /* 464 * The device used for looking up which routing table to use for sending an ICMP 465 * error is preferably the source whenever it is set, which should ensure the 466 * icmp error can be sent to the source host, else lookup using the routing 467 * table of the destination device, else use the main routing table (index 0). 468 */ 469 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 470 { 471 struct net_device *route_lookup_dev = NULL; 472 473 if (skb->dev) 474 route_lookup_dev = skb->dev; 475 else if (skb_dst(skb)) 476 route_lookup_dev = skb_dst(skb)->dev; 477 return route_lookup_dev; 478 } 479 480 static struct rtable *icmp_route_lookup(struct net *net, 481 struct flowi4 *fl4, 482 struct sk_buff *skb_in, 483 const struct iphdr *iph, 484 __be32 saddr, u8 tos, u32 mark, 485 int type, int code, 486 struct icmp_bxm *param) 487 { 488 struct net_device *route_lookup_dev; 489 struct rtable *rt, *rt2; 490 struct flowi4 fl4_dec; 491 int err; 492 493 memset(fl4, 0, sizeof(*fl4)); 494 fl4->daddr = (param->replyopts.opt.opt.srr ? 495 param->replyopts.opt.opt.faddr : iph->saddr); 496 fl4->saddr = saddr; 497 fl4->flowi4_mark = mark; 498 fl4->flowi4_uid = sock_net_uid(net, NULL); 499 fl4->flowi4_tos = RT_TOS(tos); 500 fl4->flowi4_proto = IPPROTO_ICMP; 501 fl4->fl4_icmp_type = type; 502 fl4->fl4_icmp_code = code; 503 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 504 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 505 506 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 507 rt = ip_route_output_key_hash(net, fl4, skb_in); 508 if (IS_ERR(rt)) 509 return rt; 510 511 /* No need to clone since we're just using its address. */ 512 rt2 = rt; 513 514 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 515 flowi4_to_flowi(fl4), NULL, 0); 516 if (!IS_ERR(rt)) { 517 if (rt != rt2) 518 return rt; 519 } else if (PTR_ERR(rt) == -EPERM) { 520 rt = NULL; 521 } else 522 return rt; 523 524 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 525 if (err) 526 goto relookup_failed; 527 528 if (inet_addr_type_dev_table(net, route_lookup_dev, 529 fl4_dec.saddr) == RTN_LOCAL) { 530 rt2 = __ip_route_output_key(net, &fl4_dec); 531 if (IS_ERR(rt2)) 532 err = PTR_ERR(rt2); 533 } else { 534 struct flowi4 fl4_2 = {}; 535 unsigned long orefdst; 536 537 fl4_2.daddr = fl4_dec.saddr; 538 rt2 = ip_route_output_key(net, &fl4_2); 539 if (IS_ERR(rt2)) { 540 err = PTR_ERR(rt2); 541 goto relookup_failed; 542 } 543 /* Ugh! */ 544 orefdst = skb_in->_skb_refdst; /* save old refdst */ 545 skb_dst_set(skb_in, NULL); 546 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 547 RT_TOS(tos), rt2->dst.dev); 548 549 dst_release(&rt2->dst); 550 rt2 = skb_rtable(skb_in); 551 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 552 } 553 554 if (err) 555 goto relookup_failed; 556 557 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 558 flowi4_to_flowi(&fl4_dec), NULL, 559 XFRM_LOOKUP_ICMP); 560 if (!IS_ERR(rt2)) { 561 dst_release(&rt->dst); 562 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 563 rt = rt2; 564 } else if (PTR_ERR(rt2) == -EPERM) { 565 if (rt) 566 dst_release(&rt->dst); 567 return rt2; 568 } else { 569 err = PTR_ERR(rt2); 570 goto relookup_failed; 571 } 572 return rt; 573 574 relookup_failed: 575 if (rt) 576 return rt; 577 return ERR_PTR(err); 578 } 579 580 /* 581 * Send an ICMP message in response to a situation 582 * 583 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 584 * MAY send more (we do). 585 * MUST NOT change this header information. 586 * MUST NOT reply to a multicast/broadcast IP address. 587 * MUST NOT reply to a multicast/broadcast MAC address. 588 * MUST reply to only the first fragment. 589 */ 590 591 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 592 const struct ip_options *opt) 593 { 594 struct iphdr *iph; 595 int room; 596 struct icmp_bxm icmp_param; 597 struct rtable *rt = skb_rtable(skb_in); 598 struct ipcm_cookie ipc; 599 struct flowi4 fl4; 600 __be32 saddr; 601 u8 tos; 602 u32 mark; 603 struct net *net; 604 struct sock *sk; 605 606 if (!rt) 607 goto out; 608 609 if (rt->dst.dev) 610 net = dev_net(rt->dst.dev); 611 else if (skb_in->dev) 612 net = dev_net(skb_in->dev); 613 else 614 goto out; 615 616 /* 617 * Find the original header. It is expected to be valid, of course. 618 * Check this, icmp_send is called from the most obscure devices 619 * sometimes. 620 */ 621 iph = ip_hdr(skb_in); 622 623 if ((u8 *)iph < skb_in->head || 624 (skb_network_header(skb_in) + sizeof(*iph)) > 625 skb_tail_pointer(skb_in)) 626 goto out; 627 628 /* 629 * No replies to physical multicast/broadcast 630 */ 631 if (skb_in->pkt_type != PACKET_HOST) 632 goto out; 633 634 /* 635 * Now check at the protocol level 636 */ 637 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 638 goto out; 639 640 /* 641 * Only reply to fragment 0. We byte re-order the constant 642 * mask for efficiency. 643 */ 644 if (iph->frag_off & htons(IP_OFFSET)) 645 goto out; 646 647 /* 648 * If we send an ICMP error to an ICMP error a mess would result.. 649 */ 650 if (icmp_pointers[type].error) { 651 /* 652 * We are an error, check if we are replying to an 653 * ICMP error 654 */ 655 if (iph->protocol == IPPROTO_ICMP) { 656 u8 _inner_type, *itp; 657 658 itp = skb_header_pointer(skb_in, 659 skb_network_header(skb_in) + 660 (iph->ihl << 2) + 661 offsetof(struct icmphdr, 662 type) - 663 skb_in->data, 664 sizeof(_inner_type), 665 &_inner_type); 666 if (!itp) 667 goto out; 668 669 /* 670 * Assume any unknown ICMP type is an error. This 671 * isn't specified by the RFC, but think about it.. 672 */ 673 if (*itp > NR_ICMP_TYPES || 674 icmp_pointers[*itp].error) 675 goto out; 676 } 677 } 678 679 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 680 local_bh_disable(); 681 682 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 683 * incoming dev is loopback. If outgoing dev change to not be 684 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 685 */ 686 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 687 !icmpv4_global_allow(net, type, code)) 688 goto out_bh_enable; 689 690 sk = icmp_xmit_lock(net); 691 if (!sk) 692 goto out_bh_enable; 693 694 /* 695 * Construct source address and options. 696 */ 697 698 saddr = iph->daddr; 699 if (!(rt->rt_flags & RTCF_LOCAL)) { 700 struct net_device *dev = NULL; 701 702 rcu_read_lock(); 703 if (rt_is_input_route(rt) && 704 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 705 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 706 707 if (dev) 708 saddr = inet_select_addr(dev, iph->saddr, 709 RT_SCOPE_LINK); 710 else 711 saddr = 0; 712 rcu_read_unlock(); 713 } 714 715 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 716 IPTOS_PREC_INTERNETCONTROL) : 717 iph->tos; 718 mark = IP4_REPLY_MARK(net, skb_in->mark); 719 720 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 721 goto out_unlock; 722 723 724 /* 725 * Prepare data for ICMP header. 726 */ 727 728 icmp_param.data.icmph.type = type; 729 icmp_param.data.icmph.code = code; 730 icmp_param.data.icmph.un.gateway = info; 731 icmp_param.data.icmph.checksum = 0; 732 icmp_param.skb = skb_in; 733 icmp_param.offset = skb_network_offset(skb_in); 734 inet_sk(sk)->tos = tos; 735 ipcm_init(&ipc); 736 ipc.addr = iph->saddr; 737 ipc.opt = &icmp_param.replyopts.opt; 738 ipc.sockc.mark = mark; 739 740 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 741 type, code, &icmp_param); 742 if (IS_ERR(rt)) 743 goto out_unlock; 744 745 /* peer icmp_ratelimit */ 746 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 747 goto ende; 748 749 /* RFC says return as much as we can without exceeding 576 bytes. */ 750 751 room = dst_mtu(&rt->dst); 752 if (room > 576) 753 room = 576; 754 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 755 room -= sizeof(struct icmphdr); 756 757 icmp_param.data_len = skb_in->len - icmp_param.offset; 758 if (icmp_param.data_len > room) 759 icmp_param.data_len = room; 760 icmp_param.head_len = sizeof(struct icmphdr); 761 762 /* if we don't have a source address at this point, fall back to the 763 * dummy address instead of sending out a packet with a source address 764 * of 0.0.0.0 765 */ 766 if (!fl4.saddr) 767 fl4.saddr = htonl(INADDR_DUMMY); 768 769 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt); 770 ende: 771 ip_rt_put(rt); 772 out_unlock: 773 icmp_xmit_unlock(sk); 774 out_bh_enable: 775 local_bh_enable(); 776 out:; 777 } 778 EXPORT_SYMBOL(__icmp_send); 779 780 #if IS_ENABLED(CONFIG_NF_NAT) 781 #include <net/netfilter/nf_conntrack.h> 782 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 783 { 784 struct sk_buff *cloned_skb = NULL; 785 struct ip_options opts = { 0 }; 786 enum ip_conntrack_info ctinfo; 787 struct nf_conn *ct; 788 __be32 orig_ip; 789 790 ct = nf_ct_get(skb_in, &ctinfo); 791 if (!ct || !(ct->status & IPS_SRC_NAT)) { 792 __icmp_send(skb_in, type, code, info, &opts); 793 return; 794 } 795 796 if (skb_shared(skb_in)) 797 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 798 799 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 800 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 801 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 802 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 803 goto out; 804 805 orig_ip = ip_hdr(skb_in)->saddr; 806 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 807 __icmp_send(skb_in, type, code, info, &opts); 808 ip_hdr(skb_in)->saddr = orig_ip; 809 out: 810 consume_skb(cloned_skb); 811 } 812 EXPORT_SYMBOL(icmp_ndo_send); 813 #endif 814 815 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 816 { 817 const struct iphdr *iph = (const struct iphdr *)skb->data; 818 const struct net_protocol *ipprot; 819 int protocol = iph->protocol; 820 821 /* Checkin full IP header plus 8 bytes of protocol to 822 * avoid additional coding at protocol handlers. 823 */ 824 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 825 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 826 return; 827 } 828 829 raw_icmp_error(skb, protocol, info); 830 831 ipprot = rcu_dereference(inet_protos[protocol]); 832 if (ipprot && ipprot->err_handler) 833 ipprot->err_handler(skb, info); 834 } 835 836 static bool icmp_tag_validation(int proto) 837 { 838 bool ok; 839 840 rcu_read_lock(); 841 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 842 rcu_read_unlock(); 843 return ok; 844 } 845 846 /* 847 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 848 * ICMP_PARAMETERPROB. 849 */ 850 851 static bool icmp_unreach(struct sk_buff *skb) 852 { 853 const struct iphdr *iph; 854 struct icmphdr *icmph; 855 struct net *net; 856 u32 info = 0; 857 858 net = dev_net(skb_dst(skb)->dev); 859 860 /* 861 * Incomplete header ? 862 * Only checks for the IP header, there should be an 863 * additional check for longer headers in upper levels. 864 */ 865 866 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 867 goto out_err; 868 869 icmph = icmp_hdr(skb); 870 iph = (const struct iphdr *)skb->data; 871 872 if (iph->ihl < 5) /* Mangled header, drop. */ 873 goto out_err; 874 875 switch (icmph->type) { 876 case ICMP_DEST_UNREACH: 877 switch (icmph->code & 15) { 878 case ICMP_NET_UNREACH: 879 case ICMP_HOST_UNREACH: 880 case ICMP_PROT_UNREACH: 881 case ICMP_PORT_UNREACH: 882 break; 883 case ICMP_FRAG_NEEDED: 884 /* for documentation of the ip_no_pmtu_disc 885 * values please see 886 * Documentation/networking/ip-sysctl.rst 887 */ 888 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 889 default: 890 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 891 &iph->daddr); 892 break; 893 case 2: 894 goto out; 895 case 3: 896 if (!icmp_tag_validation(iph->protocol)) 897 goto out; 898 fallthrough; 899 case 0: 900 info = ntohs(icmph->un.frag.mtu); 901 } 902 break; 903 case ICMP_SR_FAILED: 904 net_dbg_ratelimited("%pI4: Source Route Failed\n", 905 &iph->daddr); 906 break; 907 default: 908 break; 909 } 910 if (icmph->code > NR_ICMP_UNREACH) 911 goto out; 912 break; 913 case ICMP_PARAMETERPROB: 914 info = ntohl(icmph->un.gateway) >> 24; 915 break; 916 case ICMP_TIME_EXCEEDED: 917 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 918 if (icmph->code == ICMP_EXC_FRAGTIME) 919 goto out; 920 break; 921 } 922 923 /* 924 * Throw it at our lower layers 925 * 926 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 927 * header. 928 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 929 * transport layer. 930 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 931 * transport layer. 932 */ 933 934 /* 935 * Check the other end isn't violating RFC 1122. Some routers send 936 * bogus responses to broadcast frames. If you see this message 937 * first check your netmask matches at both ends, if it does then 938 * get the other vendor to fix their kit. 939 */ 940 941 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 942 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 943 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 944 &ip_hdr(skb)->saddr, 945 icmph->type, icmph->code, 946 &iph->daddr, skb->dev->name); 947 goto out; 948 } 949 950 icmp_socket_deliver(skb, info); 951 952 out: 953 return true; 954 out_err: 955 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 956 return false; 957 } 958 959 960 /* 961 * Handle ICMP_REDIRECT. 962 */ 963 964 static bool icmp_redirect(struct sk_buff *skb) 965 { 966 if (skb->len < sizeof(struct iphdr)) { 967 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 968 return false; 969 } 970 971 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 972 /* there aught to be a stat */ 973 return false; 974 } 975 976 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 977 return true; 978 } 979 980 /* 981 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 982 * 983 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 984 * requests. 985 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 986 * included in the reply. 987 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 988 * echo requests, MUST have default=NOT. 989 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 990 * Extended Echo Functionality, MUST be disabled by default 991 * See also WRT handling of options once they are done and working. 992 */ 993 994 static bool icmp_echo(struct sk_buff *skb) 995 { 996 struct icmp_bxm icmp_param; 997 struct net *net; 998 999 net = dev_net(skb_dst(skb)->dev); 1000 /* should there be an ICMP stat for ignored echos? */ 1001 if (net->ipv4.sysctl_icmp_echo_ignore_all) 1002 return true; 1003 1004 icmp_param.data.icmph = *icmp_hdr(skb); 1005 icmp_param.skb = skb; 1006 icmp_param.offset = 0; 1007 icmp_param.data_len = skb->len; 1008 icmp_param.head_len = sizeof(struct icmphdr); 1009 1010 if (icmp_param.data.icmph.type == ICMP_ECHO) 1011 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1012 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1013 return true; 1014 1015 icmp_reply(&icmp_param, skb); 1016 return true; 1017 } 1018 1019 /* Helper for icmp_echo and icmpv6_echo_reply. 1020 * Searches for net_device that matches PROBE interface identifier 1021 * and builds PROBE reply message in icmphdr. 1022 * 1023 * Returns false if PROBE responses are disabled via sysctl 1024 */ 1025 1026 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1027 { 1028 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1029 struct icmp_ext_echo_iio *iio, _iio; 1030 struct net *net = dev_net(skb->dev); 1031 struct net_device *dev; 1032 char buff[IFNAMSIZ]; 1033 u16 ident_len; 1034 u8 status; 1035 1036 if (!net->ipv4.sysctl_icmp_echo_enable_probe) 1037 return false; 1038 1039 /* We currently only support probing interfaces on the proxy node 1040 * Check to ensure L-bit is set 1041 */ 1042 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1043 return false; 1044 /* Clear status bits in reply message */ 1045 icmphdr->un.echo.sequence &= htons(0xFF00); 1046 if (icmphdr->type == ICMP_EXT_ECHO) 1047 icmphdr->type = ICMP_EXT_ECHOREPLY; 1048 else 1049 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1050 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1051 /* Size of iio is class_type dependent. 1052 * Only check header here and assign length based on ctype in the switch statement 1053 */ 1054 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1055 if (!ext_hdr || !iio) 1056 goto send_mal_query; 1057 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1058 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1059 goto send_mal_query; 1060 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1061 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1062 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1063 if (!iio) 1064 goto send_mal_query; 1065 1066 status = 0; 1067 dev = NULL; 1068 switch (iio->extobj_hdr.class_type) { 1069 case ICMP_EXT_ECHO_CTYPE_NAME: 1070 if (ident_len >= IFNAMSIZ) 1071 goto send_mal_query; 1072 memset(buff, 0, sizeof(buff)); 1073 memcpy(buff, &iio->ident.name, ident_len); 1074 dev = dev_get_by_name(net, buff); 1075 break; 1076 case ICMP_EXT_ECHO_CTYPE_INDEX: 1077 if (ident_len != sizeof(iio->ident.ifindex)) 1078 goto send_mal_query; 1079 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1080 break; 1081 case ICMP_EXT_ECHO_CTYPE_ADDR: 1082 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1083 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1084 iio->ident.addr.ctype3_hdr.addrlen) 1085 goto send_mal_query; 1086 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1087 case ICMP_AFI_IP: 1088 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1089 goto send_mal_query; 1090 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1091 break; 1092 #if IS_ENABLED(CONFIG_IPV6) 1093 case ICMP_AFI_IP6: 1094 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1095 goto send_mal_query; 1096 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1097 dev_hold(dev); 1098 break; 1099 #endif 1100 default: 1101 goto send_mal_query; 1102 } 1103 break; 1104 default: 1105 goto send_mal_query; 1106 } 1107 if (!dev) { 1108 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1109 return true; 1110 } 1111 /* Fill bits in reply message */ 1112 if (dev->flags & IFF_UP) 1113 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1114 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1115 status |= ICMP_EXT_ECHOREPLY_IPV4; 1116 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1117 status |= ICMP_EXT_ECHOREPLY_IPV6; 1118 dev_put(dev); 1119 icmphdr->un.echo.sequence |= htons(status); 1120 return true; 1121 send_mal_query: 1122 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1123 return true; 1124 } 1125 EXPORT_SYMBOL_GPL(icmp_build_probe); 1126 1127 /* 1128 * Handle ICMP Timestamp requests. 1129 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1130 * SHOULD be in the kernel for minimum random latency. 1131 * MUST be accurate to a few minutes. 1132 * MUST be updated at least at 15Hz. 1133 */ 1134 static bool icmp_timestamp(struct sk_buff *skb) 1135 { 1136 struct icmp_bxm icmp_param; 1137 /* 1138 * Too short. 1139 */ 1140 if (skb->len < 4) 1141 goto out_err; 1142 1143 /* 1144 * Fill in the current time as ms since midnight UT: 1145 */ 1146 icmp_param.data.times[1] = inet_current_timestamp(); 1147 icmp_param.data.times[2] = icmp_param.data.times[1]; 1148 1149 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1150 1151 icmp_param.data.icmph = *icmp_hdr(skb); 1152 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1153 icmp_param.data.icmph.code = 0; 1154 icmp_param.skb = skb; 1155 icmp_param.offset = 0; 1156 icmp_param.data_len = 0; 1157 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1158 icmp_reply(&icmp_param, skb); 1159 return true; 1160 1161 out_err: 1162 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1163 return false; 1164 } 1165 1166 static bool icmp_discard(struct sk_buff *skb) 1167 { 1168 /* pretend it was a success */ 1169 return true; 1170 } 1171 1172 /* 1173 * Deal with incoming ICMP packets. 1174 */ 1175 int icmp_rcv(struct sk_buff *skb) 1176 { 1177 struct icmphdr *icmph; 1178 struct rtable *rt = skb_rtable(skb); 1179 struct net *net = dev_net(rt->dst.dev); 1180 bool success; 1181 1182 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1183 struct sec_path *sp = skb_sec_path(skb); 1184 int nh; 1185 1186 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1187 XFRM_STATE_ICMP)) 1188 goto drop; 1189 1190 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1191 goto drop; 1192 1193 nh = skb_network_offset(skb); 1194 skb_set_network_header(skb, sizeof(*icmph)); 1195 1196 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 1197 goto drop; 1198 1199 skb_set_network_header(skb, nh); 1200 } 1201 1202 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1203 1204 if (skb_checksum_simple_validate(skb)) 1205 goto csum_error; 1206 1207 if (!pskb_pull(skb, sizeof(*icmph))) 1208 goto error; 1209 1210 icmph = icmp_hdr(skb); 1211 1212 ICMPMSGIN_INC_STATS(net, icmph->type); 1213 1214 /* Check for ICMP Extended Echo (PROBE) messages */ 1215 if (icmph->type == ICMP_EXT_ECHO) { 1216 /* We can't use icmp_pointers[].handler() because it is an array of 1217 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1218 */ 1219 success = icmp_echo(skb); 1220 goto success_check; 1221 } 1222 1223 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1224 success = ping_rcv(skb); 1225 goto success_check; 1226 } 1227 1228 /* 1229 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1230 * 1231 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1232 * discarded. 1233 */ 1234 if (icmph->type > NR_ICMP_TYPES) 1235 goto error; 1236 1237 /* 1238 * Parse the ICMP message 1239 */ 1240 1241 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1242 /* 1243 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1244 * silently ignored (we let user decide with a sysctl). 1245 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1246 * discarded if to broadcast/multicast. 1247 */ 1248 if ((icmph->type == ICMP_ECHO || 1249 icmph->type == ICMP_TIMESTAMP) && 1250 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1251 goto error; 1252 } 1253 if (icmph->type != ICMP_ECHO && 1254 icmph->type != ICMP_TIMESTAMP && 1255 icmph->type != ICMP_ADDRESS && 1256 icmph->type != ICMP_ADDRESSREPLY) { 1257 goto error; 1258 } 1259 } 1260 1261 success = icmp_pointers[icmph->type].handler(skb); 1262 success_check: 1263 if (success) { 1264 consume_skb(skb); 1265 return NET_RX_SUCCESS; 1266 } 1267 1268 drop: 1269 kfree_skb(skb); 1270 return NET_RX_DROP; 1271 csum_error: 1272 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1273 error: 1274 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1275 goto drop; 1276 } 1277 1278 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1279 { 1280 struct icmp_extobj_hdr *objh, _objh; 1281 struct icmp_ext_hdr *exth, _exth; 1282 u16 olen; 1283 1284 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1285 if (!exth) 1286 return false; 1287 if (exth->version != 2) 1288 return true; 1289 1290 if (exth->checksum && 1291 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1292 return false; 1293 1294 off += sizeof(_exth); 1295 while (off < skb->len) { 1296 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1297 if (!objh) 1298 return false; 1299 1300 olen = ntohs(objh->length); 1301 if (olen < sizeof(_objh)) 1302 return false; 1303 1304 off += olen; 1305 if (off > skb->len) 1306 return false; 1307 } 1308 1309 return true; 1310 } 1311 1312 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1313 struct sock_ee_data_rfc4884 *out, 1314 int thlen, int off) 1315 { 1316 int hlen; 1317 1318 /* original datagram headers: end of icmph to payload (skb->data) */ 1319 hlen = -skb_transport_offset(skb) - thlen; 1320 1321 /* per rfc 4884: minimal datagram length of 128 bytes */ 1322 if (off < 128 || off < hlen) 1323 return; 1324 1325 /* kernel has stripped headers: return payload offset in bytes */ 1326 off -= hlen; 1327 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1328 return; 1329 1330 out->len = off; 1331 1332 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1333 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1334 } 1335 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1336 1337 int icmp_err(struct sk_buff *skb, u32 info) 1338 { 1339 struct iphdr *iph = (struct iphdr *)skb->data; 1340 int offset = iph->ihl<<2; 1341 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1342 int type = icmp_hdr(skb)->type; 1343 int code = icmp_hdr(skb)->code; 1344 struct net *net = dev_net(skb->dev); 1345 1346 /* 1347 * Use ping_err to handle all icmp errors except those 1348 * triggered by ICMP_ECHOREPLY which sent from kernel. 1349 */ 1350 if (icmph->type != ICMP_ECHOREPLY) { 1351 ping_err(skb, offset, info); 1352 return 0; 1353 } 1354 1355 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1356 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1357 else if (type == ICMP_REDIRECT) 1358 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1359 1360 return 0; 1361 } 1362 1363 /* 1364 * This table is the definition of how we handle ICMP. 1365 */ 1366 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1367 [ICMP_ECHOREPLY] = { 1368 .handler = ping_rcv, 1369 }, 1370 [1] = { 1371 .handler = icmp_discard, 1372 .error = 1, 1373 }, 1374 [2] = { 1375 .handler = icmp_discard, 1376 .error = 1, 1377 }, 1378 [ICMP_DEST_UNREACH] = { 1379 .handler = icmp_unreach, 1380 .error = 1, 1381 }, 1382 [ICMP_SOURCE_QUENCH] = { 1383 .handler = icmp_unreach, 1384 .error = 1, 1385 }, 1386 [ICMP_REDIRECT] = { 1387 .handler = icmp_redirect, 1388 .error = 1, 1389 }, 1390 [6] = { 1391 .handler = icmp_discard, 1392 .error = 1, 1393 }, 1394 [7] = { 1395 .handler = icmp_discard, 1396 .error = 1, 1397 }, 1398 [ICMP_ECHO] = { 1399 .handler = icmp_echo, 1400 }, 1401 [9] = { 1402 .handler = icmp_discard, 1403 .error = 1, 1404 }, 1405 [10] = { 1406 .handler = icmp_discard, 1407 .error = 1, 1408 }, 1409 [ICMP_TIME_EXCEEDED] = { 1410 .handler = icmp_unreach, 1411 .error = 1, 1412 }, 1413 [ICMP_PARAMETERPROB] = { 1414 .handler = icmp_unreach, 1415 .error = 1, 1416 }, 1417 [ICMP_TIMESTAMP] = { 1418 .handler = icmp_timestamp, 1419 }, 1420 [ICMP_TIMESTAMPREPLY] = { 1421 .handler = icmp_discard, 1422 }, 1423 [ICMP_INFO_REQUEST] = { 1424 .handler = icmp_discard, 1425 }, 1426 [ICMP_INFO_REPLY] = { 1427 .handler = icmp_discard, 1428 }, 1429 [ICMP_ADDRESS] = { 1430 .handler = icmp_discard, 1431 }, 1432 [ICMP_ADDRESSREPLY] = { 1433 .handler = icmp_discard, 1434 }, 1435 }; 1436 1437 static void __net_exit icmp_sk_exit(struct net *net) 1438 { 1439 int i; 1440 1441 for_each_possible_cpu(i) 1442 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1443 free_percpu(net->ipv4.icmp_sk); 1444 net->ipv4.icmp_sk = NULL; 1445 } 1446 1447 static int __net_init icmp_sk_init(struct net *net) 1448 { 1449 int i, err; 1450 1451 net->ipv4.icmp_sk = alloc_percpu(struct sock *); 1452 if (!net->ipv4.icmp_sk) 1453 return -ENOMEM; 1454 1455 for_each_possible_cpu(i) { 1456 struct sock *sk; 1457 1458 err = inet_ctl_sock_create(&sk, PF_INET, 1459 SOCK_RAW, IPPROTO_ICMP, net); 1460 if (err < 0) 1461 goto fail; 1462 1463 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk; 1464 1465 /* Enough space for 2 64K ICMP packets, including 1466 * sk_buff/skb_shared_info struct overhead. 1467 */ 1468 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1469 1470 /* 1471 * Speedup sock_wfree() 1472 */ 1473 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1474 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1475 } 1476 1477 /* Control parameters for ECHO replies. */ 1478 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1479 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1480 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1481 1482 /* Control parameter - ignore bogus broadcast responses? */ 1483 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1484 1485 /* 1486 * Configurable global rate limit. 1487 * 1488 * ratelimit defines tokens/packet consumed for dst->rate_token 1489 * bucket ratemask defines which icmp types are ratelimited by 1490 * setting it's bit position. 1491 * 1492 * default: 1493 * dest unreachable (3), source quench (4), 1494 * time exceeded (11), parameter problem (12) 1495 */ 1496 1497 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1498 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1499 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1500 1501 return 0; 1502 1503 fail: 1504 icmp_sk_exit(net); 1505 return err; 1506 } 1507 1508 static struct pernet_operations __net_initdata icmp_sk_ops = { 1509 .init = icmp_sk_init, 1510 .exit = icmp_sk_exit, 1511 }; 1512 1513 int __init icmp_init(void) 1514 { 1515 return register_pernet_subsys(&icmp_sk_ops); 1516 } 1517