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 100struct 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 116const 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}; 182EXPORT_SYMBOL(icmp_err_convert); 183 184/* 185 * ICMP control array. This specifies what to do with each ICMP. 186 */ 187 188struct 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 193static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 194 195static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 196 197/* Called with BH disabled */ 198static 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 214static 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 220int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 221int sysctl_icmp_msgs_burst __read_mostly = 50; 222 223static 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 */ 238bool 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 = READ_ONCE(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, 261 READ_ONCE(sysctl_icmp_msgs_burst)); 262 if (credit) { 263 /* We want to use a credit of one in average, but need to randomize 264 * it for security reasons. 265 */ 266 credit = max_t(int, credit - get_random_u32_below(3), 0); 267 rc = true; 268 } 269 WRITE_ONCE(icmp_global.credit, credit); 270 spin_unlock(&icmp_global.lock); 271 return rc; 272} 273EXPORT_SYMBOL(icmp_global_allow); 274 275static bool icmpv4_mask_allow(struct net *net, int type, int code) 276{ 277 if (type > NR_ICMP_TYPES) 278 return true; 279 280 /* Don't limit PMTU discovery. */ 281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 282 return true; 283 284 /* Limit if icmp type is enabled in ratemask. */ 285 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 286 return true; 287 288 return false; 289} 290 291static bool icmpv4_global_allow(struct net *net, int type, int code) 292{ 293 if (icmpv4_mask_allow(net, type, code)) 294 return true; 295 296 if (icmp_global_allow()) 297 return true; 298 299 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 300 return false; 301} 302 303/* 304 * Send an ICMP frame. 305 */ 306 307static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 308 struct flowi4 *fl4, int type, int code) 309{ 310 struct dst_entry *dst = &rt->dst; 311 struct inet_peer *peer; 312 bool rc = true; 313 int vif; 314 315 if (icmpv4_mask_allow(net, type, code)) 316 goto out; 317 318 /* No rate limit on loopback */ 319 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 320 goto out; 321 322 vif = l3mdev_master_ifindex(dst->dev); 323 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 324 rc = inet_peer_xrlim_allow(peer, 325 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 326 if (peer) 327 inet_putpeer(peer); 328out: 329 if (!rc) 330 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 331 return rc; 332} 333 334/* 335 * Maintain the counters used in the SNMP statistics for outgoing ICMP 336 */ 337void icmp_out_count(struct net *net, unsigned char type) 338{ 339 ICMPMSGOUT_INC_STATS(net, type); 340 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 341} 342 343/* 344 * Checksum each fragment, and on the first include the headers and final 345 * checksum. 346 */ 347static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 348 struct sk_buff *skb) 349{ 350 struct icmp_bxm *icmp_param = from; 351 __wsum csum; 352 353 csum = skb_copy_and_csum_bits(icmp_param->skb, 354 icmp_param->offset + offset, 355 to, len); 356 357 skb->csum = csum_block_add(skb->csum, csum, odd); 358 if (icmp_pointers[icmp_param->data.icmph.type].error) 359 nf_ct_attach(skb, icmp_param->skb); 360 return 0; 361} 362 363static void icmp_push_reply(struct sock *sk, 364 struct icmp_bxm *icmp_param, 365 struct flowi4 *fl4, 366 struct ipcm_cookie *ipc, struct rtable **rt) 367{ 368 struct sk_buff *skb; 369 370 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; 379 struct sk_buff *skb1; 380 381 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 382 (char *)icmph, 383 icmp_param->head_len); 384 skb_queue_walk(&sk->sk_write_queue, skb1) { 385 csum = csum_add(csum, skb1->csum); 386 } 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 397static 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 ipc.sockc.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_common(&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(sk, icmp_param, &fl4, &ipc, &rt); 452 ip_rt_put(rt); 453out_unlock: 454 icmp_xmit_unlock(sk); 455out_bh_enable: 456 local_bh_enable(); 457} 458 459/* 460 * The device used for looking up which routing table to use for sending an ICMP 461 * error is preferably the source whenever it is set, which should ensure the 462 * icmp error can be sent to the source host, else lookup using the routing 463 * table of the destination device, else use the main routing table (index 0). 464 */ 465static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 466{ 467 struct net_device *route_lookup_dev = NULL; 468 469 if (skb->dev) 470 route_lookup_dev = skb->dev; 471 else if (skb_dst(skb)) 472 route_lookup_dev = skb_dst(skb)->dev; 473 return route_lookup_dev; 474} 475 476static struct rtable *icmp_route_lookup(struct net *net, 477 struct flowi4 *fl4, 478 struct sk_buff *skb_in, 479 const struct iphdr *iph, 480 __be32 saddr, u8 tos, u32 mark, 481 int type, int code, 482 struct icmp_bxm *param) 483{ 484 struct net_device *route_lookup_dev; 485 struct rtable *rt, *rt2; 486 struct flowi4 fl4_dec; 487 int err; 488 489 memset(fl4, 0, sizeof(*fl4)); 490 fl4->daddr = (param->replyopts.opt.opt.srr ? 491 param->replyopts.opt.opt.faddr : iph->saddr); 492 fl4->saddr = saddr; 493 fl4->flowi4_mark = mark; 494 fl4->flowi4_uid = sock_net_uid(net, NULL); 495 fl4->flowi4_tos = RT_TOS(tos); 496 fl4->flowi4_proto = IPPROTO_ICMP; 497 fl4->fl4_icmp_type = type; 498 fl4->fl4_icmp_code = code; 499 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 500 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 501 502 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 503 rt = ip_route_output_key_hash(net, fl4, skb_in); 504 if (IS_ERR(rt)) 505 return rt; 506 507 /* No need to clone since we're just using its address. */ 508 rt2 = rt; 509 510 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 511 flowi4_to_flowi(fl4), NULL, 0); 512 if (!IS_ERR(rt)) { 513 if (rt != rt2) 514 return rt; 515 } else if (PTR_ERR(rt) == -EPERM) { 516 rt = NULL; 517 } else 518 return rt; 519 520 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 521 if (err) 522 goto relookup_failed; 523 524 if (inet_addr_type_dev_table(net, route_lookup_dev, 525 fl4_dec.saddr) == RTN_LOCAL) { 526 rt2 = __ip_route_output_key(net, &fl4_dec); 527 if (IS_ERR(rt2)) 528 err = PTR_ERR(rt2); 529 } else { 530 struct flowi4 fl4_2 = {}; 531 unsigned long orefdst; 532 533 fl4_2.daddr = fl4_dec.saddr; 534 rt2 = ip_route_output_key(net, &fl4_2); 535 if (IS_ERR(rt2)) { 536 err = PTR_ERR(rt2); 537 goto relookup_failed; 538 } 539 /* Ugh! */ 540 orefdst = skb_in->_skb_refdst; /* save old refdst */ 541 skb_dst_set(skb_in, NULL); 542 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 543 RT_TOS(tos), rt2->dst.dev); 544 545 dst_release(&rt2->dst); 546 rt2 = skb_rtable(skb_in); 547 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 548 } 549 550 if (err) 551 goto relookup_failed; 552 553 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 554 flowi4_to_flowi(&fl4_dec), NULL, 555 XFRM_LOOKUP_ICMP); 556 if (!IS_ERR(rt2)) { 557 dst_release(&rt->dst); 558 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 559 rt = rt2; 560 } else if (PTR_ERR(rt2) == -EPERM) { 561 if (rt) 562 dst_release(&rt->dst); 563 return rt2; 564 } else { 565 err = PTR_ERR(rt2); 566 goto relookup_failed; 567 } 568 return rt; 569 570relookup_failed: 571 if (rt) 572 return rt; 573 return ERR_PTR(err); 574} 575 576/* 577 * Send an ICMP message in response to a situation 578 * 579 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 580 * MAY send more (we do). 581 * MUST NOT change this header information. 582 * MUST NOT reply to a multicast/broadcast IP address. 583 * MUST NOT reply to a multicast/broadcast MAC address. 584 * MUST reply to only the first fragment. 585 */ 586 587void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 588 const struct ip_options *opt) 589{ 590 struct iphdr *iph; 591 int room; 592 struct icmp_bxm icmp_param; 593 struct rtable *rt = skb_rtable(skb_in); 594 struct ipcm_cookie ipc; 595 struct flowi4 fl4; 596 __be32 saddr; 597 u8 tos; 598 u32 mark; 599 struct net *net; 600 struct sock *sk; 601 602 if (!rt) 603 goto out; 604 605 if (rt->dst.dev) 606 net = dev_net(rt->dst.dev); 607 else if (skb_in->dev) 608 net = dev_net(skb_in->dev); 609 else 610 goto out; 611 612 /* 613 * Find the original header. It is expected to be valid, of course. 614 * Check this, icmp_send is called from the most obscure devices 615 * sometimes. 616 */ 617 iph = ip_hdr(skb_in); 618 619 if ((u8 *)iph < skb_in->head || 620 (skb_network_header(skb_in) + sizeof(*iph)) > 621 skb_tail_pointer(skb_in)) 622 goto out; 623 624 /* 625 * No replies to physical multicast/broadcast 626 */ 627 if (skb_in->pkt_type != PACKET_HOST) 628 goto out; 629 630 /* 631 * Now check at the protocol level 632 */ 633 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 634 goto out; 635 636 /* 637 * Only reply to fragment 0. We byte re-order the constant 638 * mask for efficiency. 639 */ 640 if (iph->frag_off & htons(IP_OFFSET)) 641 goto out; 642 643 /* 644 * If we send an ICMP error to an ICMP error a mess would result.. 645 */ 646 if (icmp_pointers[type].error) { 647 /* 648 * We are an error, check if we are replying to an 649 * ICMP error 650 */ 651 if (iph->protocol == IPPROTO_ICMP) { 652 u8 _inner_type, *itp; 653 654 itp = skb_header_pointer(skb_in, 655 skb_network_header(skb_in) + 656 (iph->ihl << 2) + 657 offsetof(struct icmphdr, 658 type) - 659 skb_in->data, 660 sizeof(_inner_type), 661 &_inner_type); 662 if (!itp) 663 goto out; 664 665 /* 666 * Assume any unknown ICMP type is an error. This 667 * isn't specified by the RFC, but think about it.. 668 */ 669 if (*itp > NR_ICMP_TYPES || 670 icmp_pointers[*itp].error) 671 goto out; 672 } 673 } 674 675 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 676 local_bh_disable(); 677 678 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 679 * incoming dev is loopback. If outgoing dev change to not be 680 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 681 */ 682 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 683 !icmpv4_global_allow(net, type, code)) 684 goto out_bh_enable; 685 686 sk = icmp_xmit_lock(net); 687 if (!sk) 688 goto out_bh_enable; 689 690 /* 691 * Construct source address and options. 692 */ 693 694 saddr = iph->daddr; 695 if (!(rt->rt_flags & RTCF_LOCAL)) { 696 struct net_device *dev = NULL; 697 698 rcu_read_lock(); 699 if (rt_is_input_route(rt) && 700 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 701 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 702 703 if (dev) 704 saddr = inet_select_addr(dev, iph->saddr, 705 RT_SCOPE_LINK); 706 else 707 saddr = 0; 708 rcu_read_unlock(); 709 } 710 711 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 712 IPTOS_PREC_INTERNETCONTROL) : 713 iph->tos; 714 mark = IP4_REPLY_MARK(net, skb_in->mark); 715 716 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 717 goto out_unlock; 718 719 720 /* 721 * Prepare data for ICMP header. 722 */ 723 724 icmp_param.data.icmph.type = type; 725 icmp_param.data.icmph.code = code; 726 icmp_param.data.icmph.un.gateway = info; 727 icmp_param.data.icmph.checksum = 0; 728 icmp_param.skb = skb_in; 729 icmp_param.offset = skb_network_offset(skb_in); 730 inet_sk(sk)->tos = tos; 731 ipcm_init(&ipc); 732 ipc.addr = iph->saddr; 733 ipc.opt = &icmp_param.replyopts.opt; 734 ipc.sockc.mark = mark; 735 736 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 737 type, code, &icmp_param); 738 if (IS_ERR(rt)) 739 goto out_unlock; 740 741 /* peer icmp_ratelimit */ 742 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 743 goto ende; 744 745 /* RFC says return as much as we can without exceeding 576 bytes. */ 746 747 room = dst_mtu(&rt->dst); 748 if (room > 576) 749 room = 576; 750 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 751 room -= sizeof(struct icmphdr); 752 /* Guard against tiny mtu. We need to include at least one 753 * IP network header for this message to make any sense. 754 */ 755 if (room <= (int)sizeof(struct iphdr)) 756 goto ende; 757 758 icmp_param.data_len = skb_in->len - icmp_param.offset; 759 if (icmp_param.data_len > room) 760 icmp_param.data_len = room; 761 icmp_param.head_len = sizeof(struct icmphdr); 762 763 /* if we don't have a source address at this point, fall back to the 764 * dummy address instead of sending out a packet with a source address 765 * of 0.0.0.0 766 */ 767 if (!fl4.saddr) 768 fl4.saddr = htonl(INADDR_DUMMY); 769 770 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 771ende: 772 ip_rt_put(rt); 773out_unlock: 774 icmp_xmit_unlock(sk); 775out_bh_enable: 776 local_bh_enable(); 777out:; 778} 779EXPORT_SYMBOL(__icmp_send); 780 781#if IS_ENABLED(CONFIG_NF_NAT) 782#include <net/netfilter/nf_conntrack.h> 783void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 784{ 785 struct sk_buff *cloned_skb = NULL; 786 struct ip_options opts = { 0 }; 787 enum ip_conntrack_info ctinfo; 788 struct nf_conn *ct; 789 __be32 orig_ip; 790 791 ct = nf_ct_get(skb_in, &ctinfo); 792 if (!ct || !(ct->status & IPS_SRC_NAT)) { 793 __icmp_send(skb_in, type, code, info, &opts); 794 return; 795 } 796 797 if (skb_shared(skb_in)) 798 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 799 800 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 801 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 802 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 803 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 804 goto out; 805 806 orig_ip = ip_hdr(skb_in)->saddr; 807 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 808 __icmp_send(skb_in, type, code, info, &opts); 809 ip_hdr(skb_in)->saddr = orig_ip; 810out: 811 consume_skb(cloned_skb); 812} 813EXPORT_SYMBOL(icmp_ndo_send); 814#endif 815 816static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 817{ 818 const struct iphdr *iph = (const struct iphdr *)skb->data; 819 const struct net_protocol *ipprot; 820 int protocol = iph->protocol; 821 822 /* Checkin full IP header plus 8 bytes of protocol to 823 * avoid additional coding at protocol handlers. 824 */ 825 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 826 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 827 return; 828 } 829 830 raw_icmp_error(skb, protocol, info); 831 832 ipprot = rcu_dereference(inet_protos[protocol]); 833 if (ipprot && ipprot->err_handler) 834 ipprot->err_handler(skb, info); 835} 836 837static bool icmp_tag_validation(int proto) 838{ 839 bool ok; 840 841 rcu_read_lock(); 842 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 843 rcu_read_unlock(); 844 return ok; 845} 846 847/* 848 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 849 * ICMP_PARAMETERPROB. 850 */ 851 852static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 853{ 854 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 855 const struct iphdr *iph; 856 struct icmphdr *icmph; 857 struct net *net; 858 u32 info = 0; 859 860 net = dev_net(skb_dst(skb)->dev); 861 862 /* 863 * Incomplete header ? 864 * Only checks for the IP header, there should be an 865 * additional check for longer headers in upper levels. 866 */ 867 868 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 869 goto out_err; 870 871 icmph = icmp_hdr(skb); 872 iph = (const struct iphdr *)skb->data; 873 874 if (iph->ihl < 5) { /* Mangled header, drop. */ 875 reason = SKB_DROP_REASON_IP_INHDR; 876 goto out_err; 877 } 878 879 switch (icmph->type) { 880 case ICMP_DEST_UNREACH: 881 switch (icmph->code & 15) { 882 case ICMP_NET_UNREACH: 883 case ICMP_HOST_UNREACH: 884 case ICMP_PROT_UNREACH: 885 case ICMP_PORT_UNREACH: 886 break; 887 case ICMP_FRAG_NEEDED: 888 /* for documentation of the ip_no_pmtu_disc 889 * values please see 890 * Documentation/networking/ip-sysctl.rst 891 */ 892 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 893 default: 894 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 895 &iph->daddr); 896 break; 897 case 2: 898 goto out; 899 case 3: 900 if (!icmp_tag_validation(iph->protocol)) 901 goto out; 902 fallthrough; 903 case 0: 904 info = ntohs(icmph->un.frag.mtu); 905 } 906 break; 907 case ICMP_SR_FAILED: 908 net_dbg_ratelimited("%pI4: Source Route Failed\n", 909 &iph->daddr); 910 break; 911 default: 912 break; 913 } 914 if (icmph->code > NR_ICMP_UNREACH) 915 goto out; 916 break; 917 case ICMP_PARAMETERPROB: 918 info = ntohl(icmph->un.gateway) >> 24; 919 break; 920 case ICMP_TIME_EXCEEDED: 921 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 922 if (icmph->code == ICMP_EXC_FRAGTIME) 923 goto out; 924 break; 925 } 926 927 /* 928 * Throw it at our lower layers 929 * 930 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 931 * header. 932 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 933 * transport layer. 934 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 935 * transport layer. 936 */ 937 938 /* 939 * Check the other end isn't violating RFC 1122. Some routers send 940 * bogus responses to broadcast frames. If you see this message 941 * first check your netmask matches at both ends, if it does then 942 * get the other vendor to fix their kit. 943 */ 944 945 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 946 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 947 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 948 &ip_hdr(skb)->saddr, 949 icmph->type, icmph->code, 950 &iph->daddr, skb->dev->name); 951 goto out; 952 } 953 954 icmp_socket_deliver(skb, info); 955 956out: 957 return reason; 958out_err: 959 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 960 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 961} 962 963 964/* 965 * Handle ICMP_REDIRECT. 966 */ 967 968static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 969{ 970 if (skb->len < sizeof(struct iphdr)) { 971 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 972 return SKB_DROP_REASON_PKT_TOO_SMALL; 973 } 974 975 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 976 /* there aught to be a stat */ 977 return SKB_DROP_REASON_NOMEM; 978 } 979 980 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 981 return SKB_NOT_DROPPED_YET; 982} 983 984/* 985 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 986 * 987 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 988 * requests. 989 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 990 * included in the reply. 991 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 992 * echo requests, MUST have default=NOT. 993 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 994 * Extended Echo Functionality, MUST be disabled by default 995 * See also WRT handling of options once they are done and working. 996 */ 997 998static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 999{ 1000 struct icmp_bxm icmp_param; 1001 struct net *net; 1002 1003 net = dev_net(skb_dst(skb)->dev); 1004 /* should there be an ICMP stat for ignored echos? */ 1005 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1006 return SKB_NOT_DROPPED_YET; 1007 1008 icmp_param.data.icmph = *icmp_hdr(skb); 1009 icmp_param.skb = skb; 1010 icmp_param.offset = 0; 1011 icmp_param.data_len = skb->len; 1012 icmp_param.head_len = sizeof(struct icmphdr); 1013 1014 if (icmp_param.data.icmph.type == ICMP_ECHO) 1015 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1016 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1017 return SKB_NOT_DROPPED_YET; 1018 1019 icmp_reply(&icmp_param, skb); 1020 return SKB_NOT_DROPPED_YET; 1021} 1022 1023/* Helper for icmp_echo and icmpv6_echo_reply. 1024 * Searches for net_device that matches PROBE interface identifier 1025 * and builds PROBE reply message in icmphdr. 1026 * 1027 * Returns false if PROBE responses are disabled via sysctl 1028 */ 1029 1030bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1031{ 1032 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1033 struct icmp_ext_echo_iio *iio, _iio; 1034 struct net *net = dev_net(skb->dev); 1035 struct net_device *dev; 1036 char buff[IFNAMSIZ]; 1037 u16 ident_len; 1038 u8 status; 1039 1040 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1041 return false; 1042 1043 /* We currently only support probing interfaces on the proxy node 1044 * Check to ensure L-bit is set 1045 */ 1046 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1047 return false; 1048 /* Clear status bits in reply message */ 1049 icmphdr->un.echo.sequence &= htons(0xFF00); 1050 if (icmphdr->type == ICMP_EXT_ECHO) 1051 icmphdr->type = ICMP_EXT_ECHOREPLY; 1052 else 1053 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1054 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1055 /* Size of iio is class_type dependent. 1056 * Only check header here and assign length based on ctype in the switch statement 1057 */ 1058 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1059 if (!ext_hdr || !iio) 1060 goto send_mal_query; 1061 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1062 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1063 goto send_mal_query; 1064 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1065 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1066 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1067 if (!iio) 1068 goto send_mal_query; 1069 1070 status = 0; 1071 dev = NULL; 1072 switch (iio->extobj_hdr.class_type) { 1073 case ICMP_EXT_ECHO_CTYPE_NAME: 1074 if (ident_len >= IFNAMSIZ) 1075 goto send_mal_query; 1076 memset(buff, 0, sizeof(buff)); 1077 memcpy(buff, &iio->ident.name, ident_len); 1078 dev = dev_get_by_name(net, buff); 1079 break; 1080 case ICMP_EXT_ECHO_CTYPE_INDEX: 1081 if (ident_len != sizeof(iio->ident.ifindex)) 1082 goto send_mal_query; 1083 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1084 break; 1085 case ICMP_EXT_ECHO_CTYPE_ADDR: 1086 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1087 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1088 iio->ident.addr.ctype3_hdr.addrlen) 1089 goto send_mal_query; 1090 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1091 case ICMP_AFI_IP: 1092 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1093 goto send_mal_query; 1094 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1095 break; 1096#if IS_ENABLED(CONFIG_IPV6) 1097 case ICMP_AFI_IP6: 1098 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1099 goto send_mal_query; 1100 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1101 dev_hold(dev); 1102 break; 1103#endif 1104 default: 1105 goto send_mal_query; 1106 } 1107 break; 1108 default: 1109 goto send_mal_query; 1110 } 1111 if (!dev) { 1112 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1113 return true; 1114 } 1115 /* Fill bits in reply message */ 1116 if (dev->flags & IFF_UP) 1117 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1118 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1119 status |= ICMP_EXT_ECHOREPLY_IPV4; 1120 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1121 status |= ICMP_EXT_ECHOREPLY_IPV6; 1122 dev_put(dev); 1123 icmphdr->un.echo.sequence |= htons(status); 1124 return true; 1125send_mal_query: 1126 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1127 return true; 1128} 1129EXPORT_SYMBOL_GPL(icmp_build_probe); 1130 1131/* 1132 * Handle ICMP Timestamp requests. 1133 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1134 * SHOULD be in the kernel for minimum random latency. 1135 * MUST be accurate to a few minutes. 1136 * MUST be updated at least at 15Hz. 1137 */ 1138static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1139{ 1140 struct icmp_bxm icmp_param; 1141 /* 1142 * Too short. 1143 */ 1144 if (skb->len < 4) 1145 goto out_err; 1146 1147 /* 1148 * Fill in the current time as ms since midnight UT: 1149 */ 1150 icmp_param.data.times[1] = inet_current_timestamp(); 1151 icmp_param.data.times[2] = icmp_param.data.times[1]; 1152 1153 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1154 1155 icmp_param.data.icmph = *icmp_hdr(skb); 1156 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1157 icmp_param.data.icmph.code = 0; 1158 icmp_param.skb = skb; 1159 icmp_param.offset = 0; 1160 icmp_param.data_len = 0; 1161 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1162 icmp_reply(&icmp_param, skb); 1163 return SKB_NOT_DROPPED_YET; 1164 1165out_err: 1166 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1167 return SKB_DROP_REASON_PKT_TOO_SMALL; 1168} 1169 1170static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1171{ 1172 /* pretend it was a success */ 1173 return SKB_NOT_DROPPED_YET; 1174} 1175 1176/* 1177 * Deal with incoming ICMP packets. 1178 */ 1179int icmp_rcv(struct sk_buff *skb) 1180{ 1181 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1182 struct rtable *rt = skb_rtable(skb); 1183 struct net *net = dev_net(rt->dst.dev); 1184 struct icmphdr *icmph; 1185 1186 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1187 struct sec_path *sp = skb_sec_path(skb); 1188 int nh; 1189 1190 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1191 XFRM_STATE_ICMP)) { 1192 reason = SKB_DROP_REASON_XFRM_POLICY; 1193 goto drop; 1194 } 1195 1196 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1197 goto drop; 1198 1199 nh = skb_network_offset(skb); 1200 skb_set_network_header(skb, sizeof(*icmph)); 1201 1202 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1203 skb)) { 1204 reason = SKB_DROP_REASON_XFRM_POLICY; 1205 goto drop; 1206 } 1207 1208 skb_set_network_header(skb, nh); 1209 } 1210 1211 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1212 1213 if (skb_checksum_simple_validate(skb)) 1214 goto csum_error; 1215 1216 if (!pskb_pull(skb, sizeof(*icmph))) 1217 goto error; 1218 1219 icmph = icmp_hdr(skb); 1220 1221 ICMPMSGIN_INC_STATS(net, icmph->type); 1222 1223 /* Check for ICMP Extended Echo (PROBE) messages */ 1224 if (icmph->type == ICMP_EXT_ECHO) { 1225 /* We can't use icmp_pointers[].handler() because it is an array of 1226 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1227 */ 1228 reason = icmp_echo(skb); 1229 goto reason_check; 1230 } 1231 1232 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1233 reason = ping_rcv(skb); 1234 goto reason_check; 1235 } 1236 1237 /* 1238 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1239 * 1240 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1241 * discarded. 1242 */ 1243 if (icmph->type > NR_ICMP_TYPES) { 1244 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1245 goto error; 1246 } 1247 1248 /* 1249 * Parse the ICMP message 1250 */ 1251 1252 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1253 /* 1254 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1255 * silently ignored (we let user decide with a sysctl). 1256 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1257 * discarded if to broadcast/multicast. 1258 */ 1259 if ((icmph->type == ICMP_ECHO || 1260 icmph->type == ICMP_TIMESTAMP) && 1261 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1262 reason = SKB_DROP_REASON_INVALID_PROTO; 1263 goto error; 1264 } 1265 if (icmph->type != ICMP_ECHO && 1266 icmph->type != ICMP_TIMESTAMP && 1267 icmph->type != ICMP_ADDRESS && 1268 icmph->type != ICMP_ADDRESSREPLY) { 1269 reason = SKB_DROP_REASON_INVALID_PROTO; 1270 goto error; 1271 } 1272 } 1273 1274 reason = icmp_pointers[icmph->type].handler(skb); 1275reason_check: 1276 if (!reason) { 1277 consume_skb(skb); 1278 return NET_RX_SUCCESS; 1279 } 1280 1281drop: 1282 kfree_skb_reason(skb, reason); 1283 return NET_RX_DROP; 1284csum_error: 1285 reason = SKB_DROP_REASON_ICMP_CSUM; 1286 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1287error: 1288 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1289 goto drop; 1290} 1291 1292static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1293{ 1294 struct icmp_extobj_hdr *objh, _objh; 1295 struct icmp_ext_hdr *exth, _exth; 1296 u16 olen; 1297 1298 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1299 if (!exth) 1300 return false; 1301 if (exth->version != 2) 1302 return true; 1303 1304 if (exth->checksum && 1305 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1306 return false; 1307 1308 off += sizeof(_exth); 1309 while (off < skb->len) { 1310 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1311 if (!objh) 1312 return false; 1313 1314 olen = ntohs(objh->length); 1315 if (olen < sizeof(_objh)) 1316 return false; 1317 1318 off += olen; 1319 if (off > skb->len) 1320 return false; 1321 } 1322 1323 return true; 1324} 1325 1326void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1327 struct sock_ee_data_rfc4884 *out, 1328 int thlen, int off) 1329{ 1330 int hlen; 1331 1332 /* original datagram headers: end of icmph to payload (skb->data) */ 1333 hlen = -skb_transport_offset(skb) - thlen; 1334 1335 /* per rfc 4884: minimal datagram length of 128 bytes */ 1336 if (off < 128 || off < hlen) 1337 return; 1338 1339 /* kernel has stripped headers: return payload offset in bytes */ 1340 off -= hlen; 1341 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1342 return; 1343 1344 out->len = off; 1345 1346 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1347 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1348} 1349EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1350 1351int icmp_err(struct sk_buff *skb, u32 info) 1352{ 1353 struct iphdr *iph = (struct iphdr *)skb->data; 1354 int offset = iph->ihl<<2; 1355 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1356 int type = icmp_hdr(skb)->type; 1357 int code = icmp_hdr(skb)->code; 1358 struct net *net = dev_net(skb->dev); 1359 1360 /* 1361 * Use ping_err to handle all icmp errors except those 1362 * triggered by ICMP_ECHOREPLY which sent from kernel. 1363 */ 1364 if (icmph->type != ICMP_ECHOREPLY) { 1365 ping_err(skb, offset, info); 1366 return 0; 1367 } 1368 1369 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1370 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1371 else if (type == ICMP_REDIRECT) 1372 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1373 1374 return 0; 1375} 1376 1377/* 1378 * This table is the definition of how we handle ICMP. 1379 */ 1380static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1381 [ICMP_ECHOREPLY] = { 1382 .handler = ping_rcv, 1383 }, 1384 [1] = { 1385 .handler = icmp_discard, 1386 .error = 1, 1387 }, 1388 [2] = { 1389 .handler = icmp_discard, 1390 .error = 1, 1391 }, 1392 [ICMP_DEST_UNREACH] = { 1393 .handler = icmp_unreach, 1394 .error = 1, 1395 }, 1396 [ICMP_SOURCE_QUENCH] = { 1397 .handler = icmp_unreach, 1398 .error = 1, 1399 }, 1400 [ICMP_REDIRECT] = { 1401 .handler = icmp_redirect, 1402 .error = 1, 1403 }, 1404 [6] = { 1405 .handler = icmp_discard, 1406 .error = 1, 1407 }, 1408 [7] = { 1409 .handler = icmp_discard, 1410 .error = 1, 1411 }, 1412 [ICMP_ECHO] = { 1413 .handler = icmp_echo, 1414 }, 1415 [9] = { 1416 .handler = icmp_discard, 1417 .error = 1, 1418 }, 1419 [10] = { 1420 .handler = icmp_discard, 1421 .error = 1, 1422 }, 1423 [ICMP_TIME_EXCEEDED] = { 1424 .handler = icmp_unreach, 1425 .error = 1, 1426 }, 1427 [ICMP_PARAMETERPROB] = { 1428 .handler = icmp_unreach, 1429 .error = 1, 1430 }, 1431 [ICMP_TIMESTAMP] = { 1432 .handler = icmp_timestamp, 1433 }, 1434 [ICMP_TIMESTAMPREPLY] = { 1435 .handler = icmp_discard, 1436 }, 1437 [ICMP_INFO_REQUEST] = { 1438 .handler = icmp_discard, 1439 }, 1440 [ICMP_INFO_REPLY] = { 1441 .handler = icmp_discard, 1442 }, 1443 [ICMP_ADDRESS] = { 1444 .handler = icmp_discard, 1445 }, 1446 [ICMP_ADDRESSREPLY] = { 1447 .handler = icmp_discard, 1448 }, 1449}; 1450 1451static int __net_init icmp_sk_init(struct net *net) 1452{ 1453 /* Control parameters for ECHO replies. */ 1454 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1455 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1456 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1457 1458 /* Control parameter - ignore bogus broadcast responses? */ 1459 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1460 1461 /* 1462 * Configurable global rate limit. 1463 * 1464 * ratelimit defines tokens/packet consumed for dst->rate_token 1465 * bucket ratemask defines which icmp types are ratelimited by 1466 * setting it's bit position. 1467 * 1468 * default: 1469 * dest unreachable (3), source quench (4), 1470 * time exceeded (11), parameter problem (12) 1471 */ 1472 1473 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1474 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1475 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1476 1477 return 0; 1478} 1479 1480static struct pernet_operations __net_initdata icmp_sk_ops = { 1481 .init = icmp_sk_init, 1482}; 1483 1484int __init icmp_init(void) 1485{ 1486 int err, i; 1487 1488 for_each_possible_cpu(i) { 1489 struct sock *sk; 1490 1491 err = inet_ctl_sock_create(&sk, PF_INET, 1492 SOCK_RAW, IPPROTO_ICMP, &init_net); 1493 if (err < 0) 1494 return err; 1495 1496 per_cpu(ipv4_icmp_sk, i) = sk; 1497 1498 /* Enough space for 2 64K ICMP packets, including 1499 * sk_buff/skb_shared_info struct overhead. 1500 */ 1501 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1502 1503 /* 1504 * Speedup sock_wfree() 1505 */ 1506 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1507 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1508 } 1509 return register_pernet_subsys(&icmp_sk_ops); 1510} 1511