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 enum skb_drop_reason (*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 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 196 197 /* Called with BH disabled */ 198 static inline struct sock *icmp_xmit_lock(struct net *net) 199 { 200 struct sock *sk; 201 202 sk = this_cpu_read(ipv4_icmp_sk); 203 204 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 205 /* This can happen if the output path signals a 206 * dst_link_failure() for an outgoing ICMP packet. 207 */ 208 return NULL; 209 } 210 sock_net_set(sk, net); 211 return sk; 212 } 213 214 static inline void icmp_xmit_unlock(struct sock *sk) 215 { 216 sock_net_set(sk, &init_net); 217 spin_unlock(&sk->sk_lock.slock); 218 } 219 220 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 221 int sysctl_icmp_msgs_burst __read_mostly = 50; 222 223 static struct { 224 spinlock_t lock; 225 u32 credit; 226 u32 stamp; 227 } icmp_global = { 228 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 229 }; 230 231 /** 232 * icmp_global_allow - Are we allowed to send one more ICMP message ? 233 * 234 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 235 * Returns false if we reached the limit and can not send another packet. 236 * Note: called with BH disabled 237 */ 238 bool icmp_global_allow(void) 239 { 240 u32 credit, delta, incr = 0, now = (u32)jiffies; 241 bool rc = false; 242 243 /* Check if token bucket is empty and cannot be refilled 244 * without taking the spinlock. The READ_ONCE() are paired 245 * with the following WRITE_ONCE() in this same function. 246 */ 247 if (!READ_ONCE(icmp_global.credit)) { 248 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 249 if (delta < HZ / 50) 250 return false; 251 } 252 253 spin_lock(&icmp_global.lock); 254 delta = min_t(u32, now - icmp_global.stamp, HZ); 255 if (delta >= HZ / 50) { 256 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 257 if (incr) 258 WRITE_ONCE(icmp_global.stamp, now); 259 } 260 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 261 if (credit) { 262 /* We want to use a credit of one in average, but need to randomize 263 * it for security reasons. 264 */ 265 credit = max_t(int, credit - prandom_u32_max(3), 0); 266 rc = true; 267 } 268 WRITE_ONCE(icmp_global.credit, credit); 269 spin_unlock(&icmp_global.lock); 270 return rc; 271 } 272 EXPORT_SYMBOL(icmp_global_allow); 273 274 static bool icmpv4_mask_allow(struct net *net, int type, int code) 275 { 276 if (type > NR_ICMP_TYPES) 277 return true; 278 279 /* Don't limit PMTU discovery. */ 280 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 281 return true; 282 283 /* Limit if icmp type is enabled in ratemask. */ 284 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask)) 285 return true; 286 287 return false; 288 } 289 290 static bool icmpv4_global_allow(struct net *net, int type, int code) 291 { 292 if (icmpv4_mask_allow(net, type, code)) 293 return true; 294 295 if (icmp_global_allow()) 296 return true; 297 298 return false; 299 } 300 301 /* 302 * Send an ICMP frame. 303 */ 304 305 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 306 struct flowi4 *fl4, int type, int code) 307 { 308 struct dst_entry *dst = &rt->dst; 309 struct inet_peer *peer; 310 bool rc = true; 311 int vif; 312 313 if (icmpv4_mask_allow(net, type, code)) 314 goto out; 315 316 /* No rate limit on loopback */ 317 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 318 goto out; 319 320 vif = l3mdev_master_ifindex(dst->dev); 321 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 322 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit); 323 if (peer) 324 inet_putpeer(peer); 325 out: 326 return rc; 327 } 328 329 /* 330 * Maintain the counters used in the SNMP statistics for outgoing ICMP 331 */ 332 void icmp_out_count(struct net *net, unsigned char type) 333 { 334 ICMPMSGOUT_INC_STATS(net, type); 335 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 336 } 337 338 /* 339 * Checksum each fragment, and on the first include the headers and final 340 * checksum. 341 */ 342 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 343 struct sk_buff *skb) 344 { 345 struct icmp_bxm *icmp_param = from; 346 __wsum csum; 347 348 csum = skb_copy_and_csum_bits(icmp_param->skb, 349 icmp_param->offset + offset, 350 to, len); 351 352 skb->csum = csum_block_add(skb->csum, csum, odd); 353 if (icmp_pointers[icmp_param->data.icmph.type].error) 354 nf_ct_attach(skb, icmp_param->skb); 355 return 0; 356 } 357 358 static void icmp_push_reply(struct sock *sk, 359 struct icmp_bxm *icmp_param, 360 struct flowi4 *fl4, 361 struct ipcm_cookie *ipc, struct rtable **rt) 362 { 363 struct sk_buff *skb; 364 365 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 366 icmp_param->data_len+icmp_param->head_len, 367 icmp_param->head_len, 368 ipc, rt, MSG_DONTWAIT) < 0) { 369 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 370 ip_flush_pending_frames(sk); 371 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 372 struct icmphdr *icmph = icmp_hdr(skb); 373 __wsum csum; 374 struct sk_buff *skb1; 375 376 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 377 (char *)icmph, 378 icmp_param->head_len); 379 skb_queue_walk(&sk->sk_write_queue, skb1) { 380 csum = csum_add(csum, skb1->csum); 381 } 382 icmph->checksum = csum_fold(csum); 383 skb->ip_summed = CHECKSUM_NONE; 384 ip_push_pending_frames(sk, fl4); 385 } 386 } 387 388 /* 389 * Driving logic for building and sending ICMP messages. 390 */ 391 392 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 393 { 394 struct ipcm_cookie ipc; 395 struct rtable *rt = skb_rtable(skb); 396 struct net *net = dev_net(rt->dst.dev); 397 struct flowi4 fl4; 398 struct sock *sk; 399 struct inet_sock *inet; 400 __be32 daddr, saddr; 401 u32 mark = IP4_REPLY_MARK(net, skb->mark); 402 int type = icmp_param->data.icmph.type; 403 int code = icmp_param->data.icmph.code; 404 405 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 406 return; 407 408 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 409 local_bh_disable(); 410 411 /* global icmp_msgs_per_sec */ 412 if (!icmpv4_global_allow(net, type, code)) 413 goto out_bh_enable; 414 415 sk = icmp_xmit_lock(net); 416 if (!sk) 417 goto out_bh_enable; 418 inet = inet_sk(sk); 419 420 icmp_param->data.icmph.checksum = 0; 421 422 ipcm_init(&ipc); 423 inet->tos = ip_hdr(skb)->tos; 424 ipc.sockc.mark = mark; 425 daddr = ipc.addr = ip_hdr(skb)->saddr; 426 saddr = fib_compute_spec_dst(skb); 427 428 if (icmp_param->replyopts.opt.opt.optlen) { 429 ipc.opt = &icmp_param->replyopts.opt; 430 if (ipc.opt->opt.srr) 431 daddr = icmp_param->replyopts.opt.opt.faddr; 432 } 433 memset(&fl4, 0, sizeof(fl4)); 434 fl4.daddr = daddr; 435 fl4.saddr = saddr; 436 fl4.flowi4_mark = mark; 437 fl4.flowi4_uid = sock_net_uid(net, NULL); 438 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 439 fl4.flowi4_proto = IPPROTO_ICMP; 440 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 441 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 442 rt = ip_route_output_key(net, &fl4); 443 if (IS_ERR(rt)) 444 goto out_unlock; 445 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 446 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 447 ip_rt_put(rt); 448 out_unlock: 449 icmp_xmit_unlock(sk); 450 out_bh_enable: 451 local_bh_enable(); 452 } 453 454 /* 455 * The device used for looking up which routing table to use for sending an ICMP 456 * error is preferably the source whenever it is set, which should ensure the 457 * icmp error can be sent to the source host, else lookup using the routing 458 * table of the destination device, else use the main routing table (index 0). 459 */ 460 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 461 { 462 struct net_device *route_lookup_dev = NULL; 463 464 if (skb->dev) 465 route_lookup_dev = skb->dev; 466 else if (skb_dst(skb)) 467 route_lookup_dev = skb_dst(skb)->dev; 468 return route_lookup_dev; 469 } 470 471 static struct rtable *icmp_route_lookup(struct net *net, 472 struct flowi4 *fl4, 473 struct sk_buff *skb_in, 474 const struct iphdr *iph, 475 __be32 saddr, u8 tos, u32 mark, 476 int type, int code, 477 struct icmp_bxm *param) 478 { 479 struct net_device *route_lookup_dev; 480 struct rtable *rt, *rt2; 481 struct flowi4 fl4_dec; 482 int err; 483 484 memset(fl4, 0, sizeof(*fl4)); 485 fl4->daddr = (param->replyopts.opt.opt.srr ? 486 param->replyopts.opt.opt.faddr : iph->saddr); 487 fl4->saddr = saddr; 488 fl4->flowi4_mark = mark; 489 fl4->flowi4_uid = sock_net_uid(net, NULL); 490 fl4->flowi4_tos = RT_TOS(tos); 491 fl4->flowi4_proto = IPPROTO_ICMP; 492 fl4->fl4_icmp_type = type; 493 fl4->fl4_icmp_code = code; 494 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 495 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 496 497 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 498 rt = ip_route_output_key_hash(net, fl4, skb_in); 499 if (IS_ERR(rt)) 500 return rt; 501 502 /* No need to clone since we're just using its address. */ 503 rt2 = rt; 504 505 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 506 flowi4_to_flowi(fl4), NULL, 0); 507 if (!IS_ERR(rt)) { 508 if (rt != rt2) 509 return rt; 510 } else if (PTR_ERR(rt) == -EPERM) { 511 rt = NULL; 512 } else 513 return rt; 514 515 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 516 if (err) 517 goto relookup_failed; 518 519 if (inet_addr_type_dev_table(net, route_lookup_dev, 520 fl4_dec.saddr) == RTN_LOCAL) { 521 rt2 = __ip_route_output_key(net, &fl4_dec); 522 if (IS_ERR(rt2)) 523 err = PTR_ERR(rt2); 524 } else { 525 struct flowi4 fl4_2 = {}; 526 unsigned long orefdst; 527 528 fl4_2.daddr = fl4_dec.saddr; 529 rt2 = ip_route_output_key(net, &fl4_2); 530 if (IS_ERR(rt2)) { 531 err = PTR_ERR(rt2); 532 goto relookup_failed; 533 } 534 /* Ugh! */ 535 orefdst = skb_in->_skb_refdst; /* save old refdst */ 536 skb_dst_set(skb_in, NULL); 537 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 538 RT_TOS(tos), rt2->dst.dev); 539 540 dst_release(&rt2->dst); 541 rt2 = skb_rtable(skb_in); 542 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 543 } 544 545 if (err) 546 goto relookup_failed; 547 548 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 549 flowi4_to_flowi(&fl4_dec), NULL, 550 XFRM_LOOKUP_ICMP); 551 if (!IS_ERR(rt2)) { 552 dst_release(&rt->dst); 553 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 554 rt = rt2; 555 } else if (PTR_ERR(rt2) == -EPERM) { 556 if (rt) 557 dst_release(&rt->dst); 558 return rt2; 559 } else { 560 err = PTR_ERR(rt2); 561 goto relookup_failed; 562 } 563 return rt; 564 565 relookup_failed: 566 if (rt) 567 return rt; 568 return ERR_PTR(err); 569 } 570 571 /* 572 * Send an ICMP message in response to a situation 573 * 574 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 575 * MAY send more (we do). 576 * MUST NOT change this header information. 577 * MUST NOT reply to a multicast/broadcast IP address. 578 * MUST NOT reply to a multicast/broadcast MAC address. 579 * MUST reply to only the first fragment. 580 */ 581 582 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 583 const struct ip_options *opt) 584 { 585 struct iphdr *iph; 586 int room; 587 struct icmp_bxm icmp_param; 588 struct rtable *rt = skb_rtable(skb_in); 589 struct ipcm_cookie ipc; 590 struct flowi4 fl4; 591 __be32 saddr; 592 u8 tos; 593 u32 mark; 594 struct net *net; 595 struct sock *sk; 596 597 if (!rt) 598 goto out; 599 600 if (rt->dst.dev) 601 net = dev_net(rt->dst.dev); 602 else if (skb_in->dev) 603 net = dev_net(skb_in->dev); 604 else 605 goto out; 606 607 /* 608 * Find the original header. It is expected to be valid, of course. 609 * Check this, icmp_send is called from the most obscure devices 610 * sometimes. 611 */ 612 iph = ip_hdr(skb_in); 613 614 if ((u8 *)iph < skb_in->head || 615 (skb_network_header(skb_in) + sizeof(*iph)) > 616 skb_tail_pointer(skb_in)) 617 goto out; 618 619 /* 620 * No replies to physical multicast/broadcast 621 */ 622 if (skb_in->pkt_type != PACKET_HOST) 623 goto out; 624 625 /* 626 * Now check at the protocol level 627 */ 628 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 629 goto out; 630 631 /* 632 * Only reply to fragment 0. We byte re-order the constant 633 * mask for efficiency. 634 */ 635 if (iph->frag_off & htons(IP_OFFSET)) 636 goto out; 637 638 /* 639 * If we send an ICMP error to an ICMP error a mess would result.. 640 */ 641 if (icmp_pointers[type].error) { 642 /* 643 * We are an error, check if we are replying to an 644 * ICMP error 645 */ 646 if (iph->protocol == IPPROTO_ICMP) { 647 u8 _inner_type, *itp; 648 649 itp = skb_header_pointer(skb_in, 650 skb_network_header(skb_in) + 651 (iph->ihl << 2) + 652 offsetof(struct icmphdr, 653 type) - 654 skb_in->data, 655 sizeof(_inner_type), 656 &_inner_type); 657 if (!itp) 658 goto out; 659 660 /* 661 * Assume any unknown ICMP type is an error. This 662 * isn't specified by the RFC, but think about it.. 663 */ 664 if (*itp > NR_ICMP_TYPES || 665 icmp_pointers[*itp].error) 666 goto out; 667 } 668 } 669 670 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 671 local_bh_disable(); 672 673 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 674 * incoming dev is loopback. If outgoing dev change to not be 675 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 676 */ 677 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 678 !icmpv4_global_allow(net, type, code)) 679 goto out_bh_enable; 680 681 sk = icmp_xmit_lock(net); 682 if (!sk) 683 goto out_bh_enable; 684 685 /* 686 * Construct source address and options. 687 */ 688 689 saddr = iph->daddr; 690 if (!(rt->rt_flags & RTCF_LOCAL)) { 691 struct net_device *dev = NULL; 692 693 rcu_read_lock(); 694 if (rt_is_input_route(rt) && 695 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 696 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 697 698 if (dev) 699 saddr = inet_select_addr(dev, iph->saddr, 700 RT_SCOPE_LINK); 701 else 702 saddr = 0; 703 rcu_read_unlock(); 704 } 705 706 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 707 IPTOS_PREC_INTERNETCONTROL) : 708 iph->tos; 709 mark = IP4_REPLY_MARK(net, skb_in->mark); 710 711 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 712 goto out_unlock; 713 714 715 /* 716 * Prepare data for ICMP header. 717 */ 718 719 icmp_param.data.icmph.type = type; 720 icmp_param.data.icmph.code = code; 721 icmp_param.data.icmph.un.gateway = info; 722 icmp_param.data.icmph.checksum = 0; 723 icmp_param.skb = skb_in; 724 icmp_param.offset = skb_network_offset(skb_in); 725 inet_sk(sk)->tos = tos; 726 ipcm_init(&ipc); 727 ipc.addr = iph->saddr; 728 ipc.opt = &icmp_param.replyopts.opt; 729 ipc.sockc.mark = mark; 730 731 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 732 type, code, &icmp_param); 733 if (IS_ERR(rt)) 734 goto out_unlock; 735 736 /* peer icmp_ratelimit */ 737 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 738 goto ende; 739 740 /* RFC says return as much as we can without exceeding 576 bytes. */ 741 742 room = dst_mtu(&rt->dst); 743 if (room > 576) 744 room = 576; 745 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 746 room -= sizeof(struct icmphdr); 747 748 icmp_param.data_len = skb_in->len - icmp_param.offset; 749 if (icmp_param.data_len > room) 750 icmp_param.data_len = room; 751 icmp_param.head_len = sizeof(struct icmphdr); 752 753 /* if we don't have a source address at this point, fall back to the 754 * dummy address instead of sending out a packet with a source address 755 * of 0.0.0.0 756 */ 757 if (!fl4.saddr) 758 fl4.saddr = htonl(INADDR_DUMMY); 759 760 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 761 ende: 762 ip_rt_put(rt); 763 out_unlock: 764 icmp_xmit_unlock(sk); 765 out_bh_enable: 766 local_bh_enable(); 767 out:; 768 } 769 EXPORT_SYMBOL(__icmp_send); 770 771 #if IS_ENABLED(CONFIG_NF_NAT) 772 #include <net/netfilter/nf_conntrack.h> 773 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 774 { 775 struct sk_buff *cloned_skb = NULL; 776 struct ip_options opts = { 0 }; 777 enum ip_conntrack_info ctinfo; 778 struct nf_conn *ct; 779 __be32 orig_ip; 780 781 ct = nf_ct_get(skb_in, &ctinfo); 782 if (!ct || !(ct->status & IPS_SRC_NAT)) { 783 __icmp_send(skb_in, type, code, info, &opts); 784 return; 785 } 786 787 if (skb_shared(skb_in)) 788 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 789 790 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 791 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 792 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 793 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 794 goto out; 795 796 orig_ip = ip_hdr(skb_in)->saddr; 797 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 798 __icmp_send(skb_in, type, code, info, &opts); 799 ip_hdr(skb_in)->saddr = orig_ip; 800 out: 801 consume_skb(cloned_skb); 802 } 803 EXPORT_SYMBOL(icmp_ndo_send); 804 #endif 805 806 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 807 { 808 const struct iphdr *iph = (const struct iphdr *)skb->data; 809 const struct net_protocol *ipprot; 810 int protocol = iph->protocol; 811 812 /* Checkin full IP header plus 8 bytes of protocol to 813 * avoid additional coding at protocol handlers. 814 */ 815 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 816 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 817 return; 818 } 819 820 raw_icmp_error(skb, protocol, info); 821 822 ipprot = rcu_dereference(inet_protos[protocol]); 823 if (ipprot && ipprot->err_handler) 824 ipprot->err_handler(skb, info); 825 } 826 827 static bool icmp_tag_validation(int proto) 828 { 829 bool ok; 830 831 rcu_read_lock(); 832 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 833 rcu_read_unlock(); 834 return ok; 835 } 836 837 /* 838 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 839 * ICMP_PARAMETERPROB. 840 */ 841 842 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 843 { 844 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 845 const struct iphdr *iph; 846 struct icmphdr *icmph; 847 struct net *net; 848 u32 info = 0; 849 850 net = dev_net(skb_dst(skb)->dev); 851 852 /* 853 * Incomplete header ? 854 * Only checks for the IP header, there should be an 855 * additional check for longer headers in upper levels. 856 */ 857 858 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 859 goto out_err; 860 861 icmph = icmp_hdr(skb); 862 iph = (const struct iphdr *)skb->data; 863 864 if (iph->ihl < 5) { /* Mangled header, drop. */ 865 reason = SKB_DROP_REASON_IP_INHDR; 866 goto out_err; 867 } 868 869 switch (icmph->type) { 870 case ICMP_DEST_UNREACH: 871 switch (icmph->code & 15) { 872 case ICMP_NET_UNREACH: 873 case ICMP_HOST_UNREACH: 874 case ICMP_PROT_UNREACH: 875 case ICMP_PORT_UNREACH: 876 break; 877 case ICMP_FRAG_NEEDED: 878 /* for documentation of the ip_no_pmtu_disc 879 * values please see 880 * Documentation/networking/ip-sysctl.rst 881 */ 882 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 883 default: 884 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 885 &iph->daddr); 886 break; 887 case 2: 888 goto out; 889 case 3: 890 if (!icmp_tag_validation(iph->protocol)) 891 goto out; 892 fallthrough; 893 case 0: 894 info = ntohs(icmph->un.frag.mtu); 895 } 896 break; 897 case ICMP_SR_FAILED: 898 net_dbg_ratelimited("%pI4: Source Route Failed\n", 899 &iph->daddr); 900 break; 901 default: 902 break; 903 } 904 if (icmph->code > NR_ICMP_UNREACH) 905 goto out; 906 break; 907 case ICMP_PARAMETERPROB: 908 info = ntohl(icmph->un.gateway) >> 24; 909 break; 910 case ICMP_TIME_EXCEEDED: 911 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 912 if (icmph->code == ICMP_EXC_FRAGTIME) 913 goto out; 914 break; 915 } 916 917 /* 918 * Throw it at our lower layers 919 * 920 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 921 * header. 922 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 923 * transport layer. 924 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 925 * transport layer. 926 */ 927 928 /* 929 * Check the other end isn't violating RFC 1122. Some routers send 930 * bogus responses to broadcast frames. If you see this message 931 * first check your netmask matches at both ends, if it does then 932 * get the other vendor to fix their kit. 933 */ 934 935 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 936 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 937 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 938 &ip_hdr(skb)->saddr, 939 icmph->type, icmph->code, 940 &iph->daddr, skb->dev->name); 941 goto out; 942 } 943 944 icmp_socket_deliver(skb, info); 945 946 out: 947 return reason; 948 out_err: 949 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 950 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 951 } 952 953 954 /* 955 * Handle ICMP_REDIRECT. 956 */ 957 958 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 959 { 960 if (skb->len < sizeof(struct iphdr)) { 961 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 962 return SKB_DROP_REASON_PKT_TOO_SMALL; 963 } 964 965 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 966 /* there aught to be a stat */ 967 return SKB_DROP_REASON_NOMEM; 968 } 969 970 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 971 return SKB_NOT_DROPPED_YET; 972 } 973 974 /* 975 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 976 * 977 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 978 * requests. 979 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 980 * included in the reply. 981 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 982 * echo requests, MUST have default=NOT. 983 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 984 * Extended Echo Functionality, MUST be disabled by default 985 * See also WRT handling of options once they are done and working. 986 */ 987 988 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 989 { 990 struct icmp_bxm icmp_param; 991 struct net *net; 992 993 net = dev_net(skb_dst(skb)->dev); 994 /* should there be an ICMP stat for ignored echos? */ 995 if (net->ipv4.sysctl_icmp_echo_ignore_all) 996 return SKB_NOT_DROPPED_YET; 997 998 icmp_param.data.icmph = *icmp_hdr(skb); 999 icmp_param.skb = skb; 1000 icmp_param.offset = 0; 1001 icmp_param.data_len = skb->len; 1002 icmp_param.head_len = sizeof(struct icmphdr); 1003 1004 if (icmp_param.data.icmph.type == ICMP_ECHO) 1005 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1006 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1007 return SKB_NOT_DROPPED_YET; 1008 1009 icmp_reply(&icmp_param, skb); 1010 return SKB_NOT_DROPPED_YET; 1011 } 1012 1013 /* Helper for icmp_echo and icmpv6_echo_reply. 1014 * Searches for net_device that matches PROBE interface identifier 1015 * and builds PROBE reply message in icmphdr. 1016 * 1017 * Returns false if PROBE responses are disabled via sysctl 1018 */ 1019 1020 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1021 { 1022 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1023 struct icmp_ext_echo_iio *iio, _iio; 1024 struct net *net = dev_net(skb->dev); 1025 struct net_device *dev; 1026 char buff[IFNAMSIZ]; 1027 u16 ident_len; 1028 u8 status; 1029 1030 if (!net->ipv4.sysctl_icmp_echo_enable_probe) 1031 return false; 1032 1033 /* We currently only support probing interfaces on the proxy node 1034 * Check to ensure L-bit is set 1035 */ 1036 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1037 return false; 1038 /* Clear status bits in reply message */ 1039 icmphdr->un.echo.sequence &= htons(0xFF00); 1040 if (icmphdr->type == ICMP_EXT_ECHO) 1041 icmphdr->type = ICMP_EXT_ECHOREPLY; 1042 else 1043 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1044 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1045 /* Size of iio is class_type dependent. 1046 * Only check header here and assign length based on ctype in the switch statement 1047 */ 1048 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1049 if (!ext_hdr || !iio) 1050 goto send_mal_query; 1051 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1052 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1053 goto send_mal_query; 1054 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1055 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1056 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1057 if (!iio) 1058 goto send_mal_query; 1059 1060 status = 0; 1061 dev = NULL; 1062 switch (iio->extobj_hdr.class_type) { 1063 case ICMP_EXT_ECHO_CTYPE_NAME: 1064 if (ident_len >= IFNAMSIZ) 1065 goto send_mal_query; 1066 memset(buff, 0, sizeof(buff)); 1067 memcpy(buff, &iio->ident.name, ident_len); 1068 dev = dev_get_by_name(net, buff); 1069 break; 1070 case ICMP_EXT_ECHO_CTYPE_INDEX: 1071 if (ident_len != sizeof(iio->ident.ifindex)) 1072 goto send_mal_query; 1073 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1074 break; 1075 case ICMP_EXT_ECHO_CTYPE_ADDR: 1076 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1077 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1078 iio->ident.addr.ctype3_hdr.addrlen) 1079 goto send_mal_query; 1080 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1081 case ICMP_AFI_IP: 1082 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1083 goto send_mal_query; 1084 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1085 break; 1086 #if IS_ENABLED(CONFIG_IPV6) 1087 case ICMP_AFI_IP6: 1088 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1089 goto send_mal_query; 1090 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1091 dev_hold(dev); 1092 break; 1093 #endif 1094 default: 1095 goto send_mal_query; 1096 } 1097 break; 1098 default: 1099 goto send_mal_query; 1100 } 1101 if (!dev) { 1102 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1103 return true; 1104 } 1105 /* Fill bits in reply message */ 1106 if (dev->flags & IFF_UP) 1107 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1108 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1109 status |= ICMP_EXT_ECHOREPLY_IPV4; 1110 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1111 status |= ICMP_EXT_ECHOREPLY_IPV6; 1112 dev_put(dev); 1113 icmphdr->un.echo.sequence |= htons(status); 1114 return true; 1115 send_mal_query: 1116 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1117 return true; 1118 } 1119 EXPORT_SYMBOL_GPL(icmp_build_probe); 1120 1121 /* 1122 * Handle ICMP Timestamp requests. 1123 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1124 * SHOULD be in the kernel for minimum random latency. 1125 * MUST be accurate to a few minutes. 1126 * MUST be updated at least at 15Hz. 1127 */ 1128 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1129 { 1130 struct icmp_bxm icmp_param; 1131 /* 1132 * Too short. 1133 */ 1134 if (skb->len < 4) 1135 goto out_err; 1136 1137 /* 1138 * Fill in the current time as ms since midnight UT: 1139 */ 1140 icmp_param.data.times[1] = inet_current_timestamp(); 1141 icmp_param.data.times[2] = icmp_param.data.times[1]; 1142 1143 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1144 1145 icmp_param.data.icmph = *icmp_hdr(skb); 1146 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1147 icmp_param.data.icmph.code = 0; 1148 icmp_param.skb = skb; 1149 icmp_param.offset = 0; 1150 icmp_param.data_len = 0; 1151 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1152 icmp_reply(&icmp_param, skb); 1153 return SKB_NOT_DROPPED_YET; 1154 1155 out_err: 1156 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1157 return SKB_DROP_REASON_PKT_TOO_SMALL; 1158 } 1159 1160 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1161 { 1162 /* pretend it was a success */ 1163 return SKB_NOT_DROPPED_YET; 1164 } 1165 1166 /* 1167 * Deal with incoming ICMP packets. 1168 */ 1169 int icmp_rcv(struct sk_buff *skb) 1170 { 1171 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1172 struct rtable *rt = skb_rtable(skb); 1173 struct net *net = dev_net(rt->dst.dev); 1174 struct icmphdr *icmph; 1175 1176 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1177 struct sec_path *sp = skb_sec_path(skb); 1178 int nh; 1179 1180 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1181 XFRM_STATE_ICMP)) { 1182 reason = SKB_DROP_REASON_XFRM_POLICY; 1183 goto drop; 1184 } 1185 1186 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1187 goto drop; 1188 1189 nh = skb_network_offset(skb); 1190 skb_set_network_header(skb, sizeof(*icmph)); 1191 1192 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1193 skb)) { 1194 reason = SKB_DROP_REASON_XFRM_POLICY; 1195 goto drop; 1196 } 1197 1198 skb_set_network_header(skb, nh); 1199 } 1200 1201 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1202 1203 if (skb_checksum_simple_validate(skb)) 1204 goto csum_error; 1205 1206 if (!pskb_pull(skb, sizeof(*icmph))) 1207 goto error; 1208 1209 icmph = icmp_hdr(skb); 1210 1211 ICMPMSGIN_INC_STATS(net, icmph->type); 1212 1213 /* Check for ICMP Extended Echo (PROBE) messages */ 1214 if (icmph->type == ICMP_EXT_ECHO) { 1215 /* We can't use icmp_pointers[].handler() because it is an array of 1216 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1217 */ 1218 reason = icmp_echo(skb); 1219 goto reason_check; 1220 } 1221 1222 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1223 reason = ping_rcv(skb); 1224 goto reason_check; 1225 } 1226 1227 /* 1228 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1229 * 1230 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1231 * discarded. 1232 */ 1233 if (icmph->type > NR_ICMP_TYPES) { 1234 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1235 goto error; 1236 } 1237 1238 /* 1239 * Parse the ICMP message 1240 */ 1241 1242 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1243 /* 1244 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1245 * silently ignored (we let user decide with a sysctl). 1246 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1247 * discarded if to broadcast/multicast. 1248 */ 1249 if ((icmph->type == ICMP_ECHO || 1250 icmph->type == ICMP_TIMESTAMP) && 1251 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1252 reason = SKB_DROP_REASON_INVALID_PROTO; 1253 goto error; 1254 } 1255 if (icmph->type != ICMP_ECHO && 1256 icmph->type != ICMP_TIMESTAMP && 1257 icmph->type != ICMP_ADDRESS && 1258 icmph->type != ICMP_ADDRESSREPLY) { 1259 reason = SKB_DROP_REASON_INVALID_PROTO; 1260 goto error; 1261 } 1262 } 1263 1264 reason = icmp_pointers[icmph->type].handler(skb); 1265 reason_check: 1266 if (!reason) { 1267 consume_skb(skb); 1268 return NET_RX_SUCCESS; 1269 } 1270 1271 drop: 1272 kfree_skb_reason(skb, reason); 1273 return NET_RX_DROP; 1274 csum_error: 1275 reason = SKB_DROP_REASON_ICMP_CSUM; 1276 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1277 error: 1278 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1279 goto drop; 1280 } 1281 1282 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1283 { 1284 struct icmp_extobj_hdr *objh, _objh; 1285 struct icmp_ext_hdr *exth, _exth; 1286 u16 olen; 1287 1288 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1289 if (!exth) 1290 return false; 1291 if (exth->version != 2) 1292 return true; 1293 1294 if (exth->checksum && 1295 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1296 return false; 1297 1298 off += sizeof(_exth); 1299 while (off < skb->len) { 1300 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1301 if (!objh) 1302 return false; 1303 1304 olen = ntohs(objh->length); 1305 if (olen < sizeof(_objh)) 1306 return false; 1307 1308 off += olen; 1309 if (off > skb->len) 1310 return false; 1311 } 1312 1313 return true; 1314 } 1315 1316 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1317 struct sock_ee_data_rfc4884 *out, 1318 int thlen, int off) 1319 { 1320 int hlen; 1321 1322 /* original datagram headers: end of icmph to payload (skb->data) */ 1323 hlen = -skb_transport_offset(skb) - thlen; 1324 1325 /* per rfc 4884: minimal datagram length of 128 bytes */ 1326 if (off < 128 || off < hlen) 1327 return; 1328 1329 /* kernel has stripped headers: return payload offset in bytes */ 1330 off -= hlen; 1331 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1332 return; 1333 1334 out->len = off; 1335 1336 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1337 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1338 } 1339 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1340 1341 int icmp_err(struct sk_buff *skb, u32 info) 1342 { 1343 struct iphdr *iph = (struct iphdr *)skb->data; 1344 int offset = iph->ihl<<2; 1345 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1346 int type = icmp_hdr(skb)->type; 1347 int code = icmp_hdr(skb)->code; 1348 struct net *net = dev_net(skb->dev); 1349 1350 /* 1351 * Use ping_err to handle all icmp errors except those 1352 * triggered by ICMP_ECHOREPLY which sent from kernel. 1353 */ 1354 if (icmph->type != ICMP_ECHOREPLY) { 1355 ping_err(skb, offset, info); 1356 return 0; 1357 } 1358 1359 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1360 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1361 else if (type == ICMP_REDIRECT) 1362 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1363 1364 return 0; 1365 } 1366 1367 /* 1368 * This table is the definition of how we handle ICMP. 1369 */ 1370 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1371 [ICMP_ECHOREPLY] = { 1372 .handler = ping_rcv, 1373 }, 1374 [1] = { 1375 .handler = icmp_discard, 1376 .error = 1, 1377 }, 1378 [2] = { 1379 .handler = icmp_discard, 1380 .error = 1, 1381 }, 1382 [ICMP_DEST_UNREACH] = { 1383 .handler = icmp_unreach, 1384 .error = 1, 1385 }, 1386 [ICMP_SOURCE_QUENCH] = { 1387 .handler = icmp_unreach, 1388 .error = 1, 1389 }, 1390 [ICMP_REDIRECT] = { 1391 .handler = icmp_redirect, 1392 .error = 1, 1393 }, 1394 [6] = { 1395 .handler = icmp_discard, 1396 .error = 1, 1397 }, 1398 [7] = { 1399 .handler = icmp_discard, 1400 .error = 1, 1401 }, 1402 [ICMP_ECHO] = { 1403 .handler = icmp_echo, 1404 }, 1405 [9] = { 1406 .handler = icmp_discard, 1407 .error = 1, 1408 }, 1409 [10] = { 1410 .handler = icmp_discard, 1411 .error = 1, 1412 }, 1413 [ICMP_TIME_EXCEEDED] = { 1414 .handler = icmp_unreach, 1415 .error = 1, 1416 }, 1417 [ICMP_PARAMETERPROB] = { 1418 .handler = icmp_unreach, 1419 .error = 1, 1420 }, 1421 [ICMP_TIMESTAMP] = { 1422 .handler = icmp_timestamp, 1423 }, 1424 [ICMP_TIMESTAMPREPLY] = { 1425 .handler = icmp_discard, 1426 }, 1427 [ICMP_INFO_REQUEST] = { 1428 .handler = icmp_discard, 1429 }, 1430 [ICMP_INFO_REPLY] = { 1431 .handler = icmp_discard, 1432 }, 1433 [ICMP_ADDRESS] = { 1434 .handler = icmp_discard, 1435 }, 1436 [ICMP_ADDRESSREPLY] = { 1437 .handler = icmp_discard, 1438 }, 1439 }; 1440 1441 static int __net_init icmp_sk_init(struct net *net) 1442 { 1443 /* Control parameters for ECHO replies. */ 1444 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1445 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1446 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1447 1448 /* Control parameter - ignore bogus broadcast responses? */ 1449 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1450 1451 /* 1452 * Configurable global rate limit. 1453 * 1454 * ratelimit defines tokens/packet consumed for dst->rate_token 1455 * bucket ratemask defines which icmp types are ratelimited by 1456 * setting it's bit position. 1457 * 1458 * default: 1459 * dest unreachable (3), source quench (4), 1460 * time exceeded (11), parameter problem (12) 1461 */ 1462 1463 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1464 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1465 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1466 1467 return 0; 1468 } 1469 1470 static struct pernet_operations __net_initdata icmp_sk_ops = { 1471 .init = icmp_sk_init, 1472 }; 1473 1474 int __init icmp_init(void) 1475 { 1476 int err, i; 1477 1478 for_each_possible_cpu(i) { 1479 struct sock *sk; 1480 1481 err = inet_ctl_sock_create(&sk, PF_INET, 1482 SOCK_RAW, IPPROTO_ICMP, &init_net); 1483 if (err < 0) 1484 return err; 1485 1486 per_cpu(ipv4_icmp_sk, i) = sk; 1487 1488 /* Enough space for 2 64K ICMP packets, including 1489 * sk_buff/skb_shared_info struct overhead. 1490 */ 1491 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1492 1493 /* 1494 * Speedup sock_wfree() 1495 */ 1496 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1497 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1498 } 1499 return register_pernet_subsys(&icmp_sk_ops); 1500 } 1501