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#include <net/addrconf.h> 96 97/* 98 * Build xmit assembly blocks 99 */ 100 101struct icmp_bxm { 102 struct sk_buff *skb; 103 int offset; 104 int data_len; 105 106 struct { 107 struct icmphdr icmph; 108 __be32 times[3]; 109 } data; 110 int head_len; 111 struct ip_options_data replyopts; 112}; 113 114/* An array of errno for error messages from dest unreach. */ 115/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 116 117const struct icmp_err icmp_err_convert[] = { 118 { 119 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 120 .fatal = 0, 121 }, 122 { 123 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 124 .fatal = 0, 125 }, 126 { 127 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 128 .fatal = 1, 129 }, 130 { 131 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 132 .fatal = 1, 133 }, 134 { 135 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 136 .fatal = 0, 137 }, 138 { 139 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 140 .fatal = 0, 141 }, 142 { 143 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 144 .fatal = 1, 145 }, 146 { 147 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 148 .fatal = 1, 149 }, 150 { 151 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 152 .fatal = 1, 153 }, 154 { 155 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 156 .fatal = 1, 157 }, 158 { 159 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 160 .fatal = 1, 161 }, 162 { 163 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 164 .fatal = 0, 165 }, 166 { 167 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 168 .fatal = 0, 169 }, 170 { 171 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 172 .fatal = 1, 173 }, 174 { 175 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 176 .fatal = 1, 177 }, 178 { 179 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 180 .fatal = 1, 181 }, 182}; 183EXPORT_SYMBOL(icmp_err_convert); 184 185/* 186 * ICMP control array. This specifies what to do with each ICMP. 187 */ 188 189struct icmp_control { 190 enum skb_drop_reason (*handler)(struct sk_buff *skb); 191 short error; /* This ICMP is classed as an error message */ 192}; 193 194static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 195 196static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 197 198/* Called with BH disabled */ 199static inline struct sock *icmp_xmit_lock(struct net *net) 200{ 201 struct sock *sk; 202 203 sk = this_cpu_read(ipv4_icmp_sk); 204 205 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 206 /* This can happen if the output path signals a 207 * dst_link_failure() for an outgoing ICMP packet. 208 */ 209 return NULL; 210 } 211 sock_net_set(sk, net); 212 return sk; 213} 214 215static inline void icmp_xmit_unlock(struct sock *sk) 216{ 217 sock_net_set(sk, &init_net); 218 spin_unlock(&sk->sk_lock.slock); 219} 220 221int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 222int sysctl_icmp_msgs_burst __read_mostly = 50; 223 224static struct { 225 spinlock_t lock; 226 u32 credit; 227 u32 stamp; 228} icmp_global = { 229 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 230}; 231 232/** 233 * icmp_global_allow - Are we allowed to send one more ICMP message ? 234 * 235 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 236 * Returns false if we reached the limit and can not send another packet. 237 * Note: called with BH disabled 238 */ 239bool icmp_global_allow(void) 240{ 241 u32 credit, delta, incr = 0, now = (u32)jiffies; 242 bool rc = false; 243 244 /* Check if token bucket is empty and cannot be refilled 245 * without taking the spinlock. The READ_ONCE() are paired 246 * with the following WRITE_ONCE() in this same function. 247 */ 248 if (!READ_ONCE(icmp_global.credit)) { 249 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 250 if (delta < HZ / 50) 251 return false; 252 } 253 254 spin_lock(&icmp_global.lock); 255 delta = min_t(u32, now - icmp_global.stamp, HZ); 256 if (delta >= HZ / 50) { 257 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ; 258 if (incr) 259 WRITE_ONCE(icmp_global.stamp, now); 260 } 261 credit = min_t(u32, icmp_global.credit + incr, 262 READ_ONCE(sysctl_icmp_msgs_burst)); 263 if (credit) { 264 /* We want to use a credit of one in average, but need to randomize 265 * it for security reasons. 266 */ 267 credit = max_t(int, credit - get_random_u32_below(3), 0); 268 rc = true; 269 } 270 WRITE_ONCE(icmp_global.credit, credit); 271 spin_unlock(&icmp_global.lock); 272 return rc; 273} 274EXPORT_SYMBOL(icmp_global_allow); 275 276static bool icmpv4_mask_allow(struct net *net, int type, int code) 277{ 278 if (type > NR_ICMP_TYPES) 279 return true; 280 281 /* Don't limit PMTU discovery. */ 282 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 283 return true; 284 285 /* Limit if icmp type is enabled in ratemask. */ 286 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 287 return true; 288 289 return false; 290} 291 292static bool icmpv4_global_allow(struct net *net, int type, int code) 293{ 294 if (icmpv4_mask_allow(net, type, code)) 295 return true; 296 297 if (icmp_global_allow()) 298 return true; 299 300 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 301 return false; 302} 303 304/* 305 * Send an ICMP frame. 306 */ 307 308static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 309 struct flowi4 *fl4, int type, int code) 310{ 311 struct dst_entry *dst = &rt->dst; 312 struct inet_peer *peer; 313 bool rc = true; 314 int vif; 315 316 if (icmpv4_mask_allow(net, type, code)) 317 goto out; 318 319 /* No rate limit on loopback */ 320 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 321 goto out; 322 323 vif = l3mdev_master_ifindex(dst->dev); 324 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 325 rc = inet_peer_xrlim_allow(peer, 326 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 327 if (peer) 328 inet_putpeer(peer); 329out: 330 if (!rc) 331 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 332 return rc; 333} 334 335/* 336 * Maintain the counters used in the SNMP statistics for outgoing ICMP 337 */ 338void icmp_out_count(struct net *net, unsigned char type) 339{ 340 ICMPMSGOUT_INC_STATS(net, type); 341 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 342} 343 344/* 345 * Checksum each fragment, and on the first include the headers and final 346 * checksum. 347 */ 348static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 349 struct sk_buff *skb) 350{ 351 struct icmp_bxm *icmp_param = from; 352 __wsum csum; 353 354 csum = skb_copy_and_csum_bits(icmp_param->skb, 355 icmp_param->offset + offset, 356 to, len); 357 358 skb->csum = csum_block_add(skb->csum, csum, odd); 359 if (icmp_pointers[icmp_param->data.icmph.type].error) 360 nf_ct_attach(skb, icmp_param->skb); 361 return 0; 362} 363 364static void icmp_push_reply(struct sock *sk, 365 struct icmp_bxm *icmp_param, 366 struct flowi4 *fl4, 367 struct ipcm_cookie *ipc, struct rtable **rt) 368{ 369 struct sk_buff *skb; 370 371 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 372 icmp_param->data_len+icmp_param->head_len, 373 icmp_param->head_len, 374 ipc, rt, MSG_DONTWAIT) < 0) { 375 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 376 ip_flush_pending_frames(sk); 377 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 378 struct icmphdr *icmph = icmp_hdr(skb); 379 __wsum csum; 380 struct sk_buff *skb1; 381 382 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 383 (char *)icmph, 384 icmp_param->head_len); 385 skb_queue_walk(&sk->sk_write_queue, skb1) { 386 csum = csum_add(csum, skb1->csum); 387 } 388 icmph->checksum = csum_fold(csum); 389 skb->ip_summed = CHECKSUM_NONE; 390 ip_push_pending_frames(sk, fl4); 391 } 392} 393 394/* 395 * Driving logic for building and sending ICMP messages. 396 */ 397 398static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 399{ 400 struct ipcm_cookie ipc; 401 struct rtable *rt = skb_rtable(skb); 402 struct net *net = dev_net(rt->dst.dev); 403 struct flowi4 fl4; 404 struct sock *sk; 405 struct inet_sock *inet; 406 __be32 daddr, saddr; 407 u32 mark = IP4_REPLY_MARK(net, skb->mark); 408 int type = icmp_param->data.icmph.type; 409 int code = icmp_param->data.icmph.code; 410 411 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 412 return; 413 414 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 415 local_bh_disable(); 416 417 /* global icmp_msgs_per_sec */ 418 if (!icmpv4_global_allow(net, type, code)) 419 goto out_bh_enable; 420 421 sk = icmp_xmit_lock(net); 422 if (!sk) 423 goto out_bh_enable; 424 inet = inet_sk(sk); 425 426 icmp_param->data.icmph.checksum = 0; 427 428 ipcm_init(&ipc); 429 inet->tos = ip_hdr(skb)->tos; 430 ipc.sockc.mark = mark; 431 daddr = ipc.addr = ip_hdr(skb)->saddr; 432 saddr = fib_compute_spec_dst(skb); 433 434 if (icmp_param->replyopts.opt.opt.optlen) { 435 ipc.opt = &icmp_param->replyopts.opt; 436 if (ipc.opt->opt.srr) 437 daddr = icmp_param->replyopts.opt.opt.faddr; 438 } 439 memset(&fl4, 0, sizeof(fl4)); 440 fl4.daddr = daddr; 441 fl4.saddr = saddr; 442 fl4.flowi4_mark = mark; 443 fl4.flowi4_uid = sock_net_uid(net, NULL); 444 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 445 fl4.flowi4_proto = IPPROTO_ICMP; 446 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 447 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 448 rt = ip_route_output_key(net, &fl4); 449 if (IS_ERR(rt)) 450 goto out_unlock; 451 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 452 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 453 ip_rt_put(rt); 454out_unlock: 455 icmp_xmit_unlock(sk); 456out_bh_enable: 457 local_bh_enable(); 458} 459 460/* 461 * The device used for looking up which routing table to use for sending an ICMP 462 * error is preferably the source whenever it is set, which should ensure the 463 * icmp error can be sent to the source host, else lookup using the routing 464 * table of the destination device, else use the main routing table (index 0). 465 */ 466static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 467{ 468 struct net_device *route_lookup_dev = NULL; 469 470 if (skb->dev) 471 route_lookup_dev = skb->dev; 472 else if (skb_dst(skb)) 473 route_lookup_dev = skb_dst(skb)->dev; 474 return route_lookup_dev; 475} 476 477static struct rtable *icmp_route_lookup(struct net *net, 478 struct flowi4 *fl4, 479 struct sk_buff *skb_in, 480 const struct iphdr *iph, 481 __be32 saddr, u8 tos, u32 mark, 482 int type, int code, 483 struct icmp_bxm *param) 484{ 485 struct net_device *route_lookup_dev; 486 struct rtable *rt, *rt2; 487 struct flowi4 fl4_dec; 488 int err; 489 490 memset(fl4, 0, sizeof(*fl4)); 491 fl4->daddr = (param->replyopts.opt.opt.srr ? 492 param->replyopts.opt.opt.faddr : iph->saddr); 493 fl4->saddr = saddr; 494 fl4->flowi4_mark = mark; 495 fl4->flowi4_uid = sock_net_uid(net, NULL); 496 fl4->flowi4_tos = RT_TOS(tos); 497 fl4->flowi4_proto = IPPROTO_ICMP; 498 fl4->fl4_icmp_type = type; 499 fl4->fl4_icmp_code = code; 500 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 501 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 502 503 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 504 rt = ip_route_output_key_hash(net, fl4, skb_in); 505 if (IS_ERR(rt)) 506 return rt; 507 508 /* No need to clone since we're just using its address. */ 509 rt2 = rt; 510 511 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 512 flowi4_to_flowi(fl4), NULL, 0); 513 if (!IS_ERR(rt)) { 514 if (rt != rt2) 515 return rt; 516 } else if (PTR_ERR(rt) == -EPERM) { 517 rt = NULL; 518 } else 519 return rt; 520 521 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 522 if (err) 523 goto relookup_failed; 524 525 if (inet_addr_type_dev_table(net, route_lookup_dev, 526 fl4_dec.saddr) == RTN_LOCAL) { 527 rt2 = __ip_route_output_key(net, &fl4_dec); 528 if (IS_ERR(rt2)) 529 err = PTR_ERR(rt2); 530 } else { 531 struct flowi4 fl4_2 = {}; 532 unsigned long orefdst; 533 534 fl4_2.daddr = fl4_dec.saddr; 535 rt2 = ip_route_output_key(net, &fl4_2); 536 if (IS_ERR(rt2)) { 537 err = PTR_ERR(rt2); 538 goto relookup_failed; 539 } 540 /* Ugh! */ 541 orefdst = skb_in->_skb_refdst; /* save old refdst */ 542 skb_dst_set(skb_in, NULL); 543 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 544 RT_TOS(tos), rt2->dst.dev); 545 546 dst_release(&rt2->dst); 547 rt2 = skb_rtable(skb_in); 548 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 549 } 550 551 if (err) 552 goto relookup_failed; 553 554 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 555 flowi4_to_flowi(&fl4_dec), NULL, 556 XFRM_LOOKUP_ICMP); 557 if (!IS_ERR(rt2)) { 558 dst_release(&rt->dst); 559 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 560 rt = rt2; 561 } else if (PTR_ERR(rt2) == -EPERM) { 562 if (rt) 563 dst_release(&rt->dst); 564 return rt2; 565 } else { 566 err = PTR_ERR(rt2); 567 goto relookup_failed; 568 } 569 return rt; 570 571relookup_failed: 572 if (rt) 573 return rt; 574 return ERR_PTR(err); 575} 576 577/* 578 * Send an ICMP message in response to a situation 579 * 580 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 581 * MAY send more (we do). 582 * MUST NOT change this header information. 583 * MUST NOT reply to a multicast/broadcast IP address. 584 * MUST NOT reply to a multicast/broadcast MAC address. 585 * MUST reply to only the first fragment. 586 */ 587 588void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 589 const struct ip_options *opt) 590{ 591 struct iphdr *iph; 592 int room; 593 struct icmp_bxm icmp_param; 594 struct rtable *rt = skb_rtable(skb_in); 595 struct ipcm_cookie ipc; 596 struct flowi4 fl4; 597 __be32 saddr; 598 u8 tos; 599 u32 mark; 600 struct net *net; 601 struct sock *sk; 602 603 if (!rt) 604 goto out; 605 606 if (rt->dst.dev) 607 net = dev_net(rt->dst.dev); 608 else if (skb_in->dev) 609 net = dev_net(skb_in->dev); 610 else 611 goto out; 612 613 /* 614 * Find the original header. It is expected to be valid, of course. 615 * Check this, icmp_send is called from the most obscure devices 616 * sometimes. 617 */ 618 iph = ip_hdr(skb_in); 619 620 if ((u8 *)iph < skb_in->head || 621 (skb_network_header(skb_in) + sizeof(*iph)) > 622 skb_tail_pointer(skb_in)) 623 goto out; 624 625 /* 626 * No replies to physical multicast/broadcast 627 */ 628 if (skb_in->pkt_type != PACKET_HOST) 629 goto out; 630 631 /* 632 * Now check at the protocol level 633 */ 634 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 635 goto out; 636 637 /* 638 * Only reply to fragment 0. We byte re-order the constant 639 * mask for efficiency. 640 */ 641 if (iph->frag_off & htons(IP_OFFSET)) 642 goto out; 643 644 /* 645 * If we send an ICMP error to an ICMP error a mess would result.. 646 */ 647 if (icmp_pointers[type].error) { 648 /* 649 * We are an error, check if we are replying to an 650 * ICMP error 651 */ 652 if (iph->protocol == IPPROTO_ICMP) { 653 u8 _inner_type, *itp; 654 655 itp = skb_header_pointer(skb_in, 656 skb_network_header(skb_in) + 657 (iph->ihl << 2) + 658 offsetof(struct icmphdr, 659 type) - 660 skb_in->data, 661 sizeof(_inner_type), 662 &_inner_type); 663 if (!itp) 664 goto out; 665 666 /* 667 * Assume any unknown ICMP type is an error. This 668 * isn't specified by the RFC, but think about it.. 669 */ 670 if (*itp > NR_ICMP_TYPES || 671 icmp_pointers[*itp].error) 672 goto out; 673 } 674 } 675 676 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 677 local_bh_disable(); 678 679 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 680 * incoming dev is loopback. If outgoing dev change to not be 681 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 682 */ 683 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 684 !icmpv4_global_allow(net, type, code)) 685 goto out_bh_enable; 686 687 sk = icmp_xmit_lock(net); 688 if (!sk) 689 goto out_bh_enable; 690 691 /* 692 * Construct source address and options. 693 */ 694 695 saddr = iph->daddr; 696 if (!(rt->rt_flags & RTCF_LOCAL)) { 697 struct net_device *dev = NULL; 698 699 rcu_read_lock(); 700 if (rt_is_input_route(rt) && 701 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 702 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 703 704 if (dev) 705 saddr = inet_select_addr(dev, iph->saddr, 706 RT_SCOPE_LINK); 707 else 708 saddr = 0; 709 rcu_read_unlock(); 710 } 711 712 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 713 IPTOS_PREC_INTERNETCONTROL) : 714 iph->tos; 715 mark = IP4_REPLY_MARK(net, skb_in->mark); 716 717 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 718 goto out_unlock; 719 720 721 /* 722 * Prepare data for ICMP header. 723 */ 724 725 icmp_param.data.icmph.type = type; 726 icmp_param.data.icmph.code = code; 727 icmp_param.data.icmph.un.gateway = info; 728 icmp_param.data.icmph.checksum = 0; 729 icmp_param.skb = skb_in; 730 icmp_param.offset = skb_network_offset(skb_in); 731 inet_sk(sk)->tos = tos; 732 ipcm_init(&ipc); 733 ipc.addr = iph->saddr; 734 ipc.opt = &icmp_param.replyopts.opt; 735 ipc.sockc.mark = mark; 736 737 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 738 type, code, &icmp_param); 739 if (IS_ERR(rt)) 740 goto out_unlock; 741 742 /* peer icmp_ratelimit */ 743 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 744 goto ende; 745 746 /* RFC says return as much as we can without exceeding 576 bytes. */ 747 748 room = dst_mtu(&rt->dst); 749 if (room > 576) 750 room = 576; 751 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 752 room -= sizeof(struct icmphdr); 753 /* Guard against tiny mtu. We need to include at least one 754 * IP network header for this message to make any sense. 755 */ 756 if (room <= (int)sizeof(struct iphdr)) 757 goto ende; 758 759 icmp_param.data_len = skb_in->len - icmp_param.offset; 760 if (icmp_param.data_len > room) 761 icmp_param.data_len = room; 762 icmp_param.head_len = sizeof(struct icmphdr); 763 764 /* if we don't have a source address at this point, fall back to the 765 * dummy address instead of sending out a packet with a source address 766 * of 0.0.0.0 767 */ 768 if (!fl4.saddr) 769 fl4.saddr = htonl(INADDR_DUMMY); 770 771 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 772ende: 773 ip_rt_put(rt); 774out_unlock: 775 icmp_xmit_unlock(sk); 776out_bh_enable: 777 local_bh_enable(); 778out:; 779} 780EXPORT_SYMBOL(__icmp_send); 781 782#if IS_ENABLED(CONFIG_NF_NAT) 783#include <net/netfilter/nf_conntrack.h> 784void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 785{ 786 struct sk_buff *cloned_skb = NULL; 787 struct ip_options opts = { 0 }; 788 enum ip_conntrack_info ctinfo; 789 struct nf_conn *ct; 790 __be32 orig_ip; 791 792 ct = nf_ct_get(skb_in, &ctinfo); 793 if (!ct || !(ct->status & IPS_SRC_NAT)) { 794 __icmp_send(skb_in, type, code, info, &opts); 795 return; 796 } 797 798 if (skb_shared(skb_in)) 799 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 800 801 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 802 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 803 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 804 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 805 goto out; 806 807 orig_ip = ip_hdr(skb_in)->saddr; 808 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 809 __icmp_send(skb_in, type, code, info, &opts); 810 ip_hdr(skb_in)->saddr = orig_ip; 811out: 812 consume_skb(cloned_skb); 813} 814EXPORT_SYMBOL(icmp_ndo_send); 815#endif 816 817static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 818{ 819 const struct iphdr *iph = (const struct iphdr *)skb->data; 820 const struct net_protocol *ipprot; 821 int protocol = iph->protocol; 822 823 /* Checkin full IP header plus 8 bytes of protocol to 824 * avoid additional coding at protocol handlers. 825 */ 826 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 827 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 828 return; 829 } 830 831 raw_icmp_error(skb, protocol, info); 832 833 ipprot = rcu_dereference(inet_protos[protocol]); 834 if (ipprot && ipprot->err_handler) 835 ipprot->err_handler(skb, info); 836} 837 838static bool icmp_tag_validation(int proto) 839{ 840 bool ok; 841 842 rcu_read_lock(); 843 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 844 rcu_read_unlock(); 845 return ok; 846} 847 848/* 849 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 850 * ICMP_PARAMETERPROB. 851 */ 852 853static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 854{ 855 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 856 const struct iphdr *iph; 857 struct icmphdr *icmph; 858 struct net *net; 859 u32 info = 0; 860 861 net = dev_net(skb_dst(skb)->dev); 862 863 /* 864 * Incomplete header ? 865 * Only checks for the IP header, there should be an 866 * additional check for longer headers in upper levels. 867 */ 868 869 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 870 goto out_err; 871 872 icmph = icmp_hdr(skb); 873 iph = (const struct iphdr *)skb->data; 874 875 if (iph->ihl < 5) { /* Mangled header, drop. */ 876 reason = SKB_DROP_REASON_IP_INHDR; 877 goto out_err; 878 } 879 880 switch (icmph->type) { 881 case ICMP_DEST_UNREACH: 882 switch (icmph->code & 15) { 883 case ICMP_NET_UNREACH: 884 case ICMP_HOST_UNREACH: 885 case ICMP_PROT_UNREACH: 886 case ICMP_PORT_UNREACH: 887 break; 888 case ICMP_FRAG_NEEDED: 889 /* for documentation of the ip_no_pmtu_disc 890 * values please see 891 * Documentation/networking/ip-sysctl.rst 892 */ 893 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 894 default: 895 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 896 &iph->daddr); 897 break; 898 case 2: 899 goto out; 900 case 3: 901 if (!icmp_tag_validation(iph->protocol)) 902 goto out; 903 fallthrough; 904 case 0: 905 info = ntohs(icmph->un.frag.mtu); 906 } 907 break; 908 case ICMP_SR_FAILED: 909 net_dbg_ratelimited("%pI4: Source Route Failed\n", 910 &iph->daddr); 911 break; 912 default: 913 break; 914 } 915 if (icmph->code > NR_ICMP_UNREACH) 916 goto out; 917 break; 918 case ICMP_PARAMETERPROB: 919 info = ntohl(icmph->un.gateway) >> 24; 920 break; 921 case ICMP_TIME_EXCEEDED: 922 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 923 if (icmph->code == ICMP_EXC_FRAGTIME) 924 goto out; 925 break; 926 } 927 928 /* 929 * Throw it at our lower layers 930 * 931 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 932 * header. 933 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 934 * transport layer. 935 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 936 * transport layer. 937 */ 938 939 /* 940 * Check the other end isn't violating RFC 1122. Some routers send 941 * bogus responses to broadcast frames. If you see this message 942 * first check your netmask matches at both ends, if it does then 943 * get the other vendor to fix their kit. 944 */ 945 946 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 947 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 948 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 949 &ip_hdr(skb)->saddr, 950 icmph->type, icmph->code, 951 &iph->daddr, skb->dev->name); 952 goto out; 953 } 954 955 icmp_socket_deliver(skb, info); 956 957out: 958 return reason; 959out_err: 960 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 961 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 962} 963 964 965/* 966 * Handle ICMP_REDIRECT. 967 */ 968 969static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 970{ 971 if (skb->len < sizeof(struct iphdr)) { 972 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 973 return SKB_DROP_REASON_PKT_TOO_SMALL; 974 } 975 976 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 977 /* there aught to be a stat */ 978 return SKB_DROP_REASON_NOMEM; 979 } 980 981 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 982 return SKB_NOT_DROPPED_YET; 983} 984 985/* 986 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 987 * 988 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 989 * requests. 990 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 991 * included in the reply. 992 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 993 * echo requests, MUST have default=NOT. 994 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 995 * Extended Echo Functionality, MUST be disabled by default 996 * See also WRT handling of options once they are done and working. 997 */ 998 999static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1000{ 1001 struct icmp_bxm icmp_param; 1002 struct net *net; 1003 1004 net = dev_net(skb_dst(skb)->dev); 1005 /* should there be an ICMP stat for ignored echos? */ 1006 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1007 return SKB_NOT_DROPPED_YET; 1008 1009 icmp_param.data.icmph = *icmp_hdr(skb); 1010 icmp_param.skb = skb; 1011 icmp_param.offset = 0; 1012 icmp_param.data_len = skb->len; 1013 icmp_param.head_len = sizeof(struct icmphdr); 1014 1015 if (icmp_param.data.icmph.type == ICMP_ECHO) 1016 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1017 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1018 return SKB_NOT_DROPPED_YET; 1019 1020 icmp_reply(&icmp_param, skb); 1021 return SKB_NOT_DROPPED_YET; 1022} 1023 1024/* Helper for icmp_echo and icmpv6_echo_reply. 1025 * Searches for net_device that matches PROBE interface identifier 1026 * and builds PROBE reply message in icmphdr. 1027 * 1028 * Returns false if PROBE responses are disabled via sysctl 1029 */ 1030 1031bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1032{ 1033 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1034 struct icmp_ext_echo_iio *iio, _iio; 1035 struct net *net = dev_net(skb->dev); 1036 struct inet6_dev *in6_dev; 1037 struct in_device *in_dev; 1038 struct net_device *dev; 1039 char buff[IFNAMSIZ]; 1040 u16 ident_len; 1041 u8 status; 1042 1043 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1044 return false; 1045 1046 /* We currently only support probing interfaces on the proxy node 1047 * Check to ensure L-bit is set 1048 */ 1049 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1050 return false; 1051 /* Clear status bits in reply message */ 1052 icmphdr->un.echo.sequence &= htons(0xFF00); 1053 if (icmphdr->type == ICMP_EXT_ECHO) 1054 icmphdr->type = ICMP_EXT_ECHOREPLY; 1055 else 1056 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1057 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1058 /* Size of iio is class_type dependent. 1059 * Only check header here and assign length based on ctype in the switch statement 1060 */ 1061 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1062 if (!ext_hdr || !iio) 1063 goto send_mal_query; 1064 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1065 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1066 goto send_mal_query; 1067 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1068 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1069 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1070 if (!iio) 1071 goto send_mal_query; 1072 1073 status = 0; 1074 dev = NULL; 1075 switch (iio->extobj_hdr.class_type) { 1076 case ICMP_EXT_ECHO_CTYPE_NAME: 1077 if (ident_len >= IFNAMSIZ) 1078 goto send_mal_query; 1079 memset(buff, 0, sizeof(buff)); 1080 memcpy(buff, &iio->ident.name, ident_len); 1081 dev = dev_get_by_name(net, buff); 1082 break; 1083 case ICMP_EXT_ECHO_CTYPE_INDEX: 1084 if (ident_len != sizeof(iio->ident.ifindex)) 1085 goto send_mal_query; 1086 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1087 break; 1088 case ICMP_EXT_ECHO_CTYPE_ADDR: 1089 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1090 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1091 iio->ident.addr.ctype3_hdr.addrlen) 1092 goto send_mal_query; 1093 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1094 case ICMP_AFI_IP: 1095 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1096 goto send_mal_query; 1097 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1098 break; 1099#if IS_ENABLED(CONFIG_IPV6) 1100 case ICMP_AFI_IP6: 1101 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1102 goto send_mal_query; 1103 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1104 dev_hold(dev); 1105 break; 1106#endif 1107 default: 1108 goto send_mal_query; 1109 } 1110 break; 1111 default: 1112 goto send_mal_query; 1113 } 1114 if (!dev) { 1115 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1116 return true; 1117 } 1118 /* Fill bits in reply message */ 1119 if (dev->flags & IFF_UP) 1120 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1121 1122 in_dev = __in_dev_get_rcu(dev); 1123 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1124 status |= ICMP_EXT_ECHOREPLY_IPV4; 1125 1126 in6_dev = __in6_dev_get(dev); 1127 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1128 status |= ICMP_EXT_ECHOREPLY_IPV6; 1129 1130 dev_put(dev); 1131 icmphdr->un.echo.sequence |= htons(status); 1132 return true; 1133send_mal_query: 1134 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1135 return true; 1136} 1137EXPORT_SYMBOL_GPL(icmp_build_probe); 1138 1139/* 1140 * Handle ICMP Timestamp requests. 1141 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1142 * SHOULD be in the kernel for minimum random latency. 1143 * MUST be accurate to a few minutes. 1144 * MUST be updated at least at 15Hz. 1145 */ 1146static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1147{ 1148 struct icmp_bxm icmp_param; 1149 /* 1150 * Too short. 1151 */ 1152 if (skb->len < 4) 1153 goto out_err; 1154 1155 /* 1156 * Fill in the current time as ms since midnight UT: 1157 */ 1158 icmp_param.data.times[1] = inet_current_timestamp(); 1159 icmp_param.data.times[2] = icmp_param.data.times[1]; 1160 1161 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1162 1163 icmp_param.data.icmph = *icmp_hdr(skb); 1164 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1165 icmp_param.data.icmph.code = 0; 1166 icmp_param.skb = skb; 1167 icmp_param.offset = 0; 1168 icmp_param.data_len = 0; 1169 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1170 icmp_reply(&icmp_param, skb); 1171 return SKB_NOT_DROPPED_YET; 1172 1173out_err: 1174 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1175 return SKB_DROP_REASON_PKT_TOO_SMALL; 1176} 1177 1178static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1179{ 1180 /* pretend it was a success */ 1181 return SKB_NOT_DROPPED_YET; 1182} 1183 1184/* 1185 * Deal with incoming ICMP packets. 1186 */ 1187int icmp_rcv(struct sk_buff *skb) 1188{ 1189 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1190 struct rtable *rt = skb_rtable(skb); 1191 struct net *net = dev_net(rt->dst.dev); 1192 struct icmphdr *icmph; 1193 1194 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1195 struct sec_path *sp = skb_sec_path(skb); 1196 int nh; 1197 1198 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1199 XFRM_STATE_ICMP)) { 1200 reason = SKB_DROP_REASON_XFRM_POLICY; 1201 goto drop; 1202 } 1203 1204 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1205 goto drop; 1206 1207 nh = skb_network_offset(skb); 1208 skb_set_network_header(skb, sizeof(*icmph)); 1209 1210 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1211 skb)) { 1212 reason = SKB_DROP_REASON_XFRM_POLICY; 1213 goto drop; 1214 } 1215 1216 skb_set_network_header(skb, nh); 1217 } 1218 1219 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1220 1221 if (skb_checksum_simple_validate(skb)) 1222 goto csum_error; 1223 1224 if (!pskb_pull(skb, sizeof(*icmph))) 1225 goto error; 1226 1227 icmph = icmp_hdr(skb); 1228 1229 ICMPMSGIN_INC_STATS(net, icmph->type); 1230 1231 /* Check for ICMP Extended Echo (PROBE) messages */ 1232 if (icmph->type == ICMP_EXT_ECHO) { 1233 /* We can't use icmp_pointers[].handler() because it is an array of 1234 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1235 */ 1236 reason = icmp_echo(skb); 1237 goto reason_check; 1238 } 1239 1240 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1241 reason = ping_rcv(skb); 1242 goto reason_check; 1243 } 1244 1245 /* 1246 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1247 * 1248 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1249 * discarded. 1250 */ 1251 if (icmph->type > NR_ICMP_TYPES) { 1252 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1253 goto error; 1254 } 1255 1256 /* 1257 * Parse the ICMP message 1258 */ 1259 1260 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1261 /* 1262 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1263 * silently ignored (we let user decide with a sysctl). 1264 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1265 * discarded if to broadcast/multicast. 1266 */ 1267 if ((icmph->type == ICMP_ECHO || 1268 icmph->type == ICMP_TIMESTAMP) && 1269 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1270 reason = SKB_DROP_REASON_INVALID_PROTO; 1271 goto error; 1272 } 1273 if (icmph->type != ICMP_ECHO && 1274 icmph->type != ICMP_TIMESTAMP && 1275 icmph->type != ICMP_ADDRESS && 1276 icmph->type != ICMP_ADDRESSREPLY) { 1277 reason = SKB_DROP_REASON_INVALID_PROTO; 1278 goto error; 1279 } 1280 } 1281 1282 reason = icmp_pointers[icmph->type].handler(skb); 1283reason_check: 1284 if (!reason) { 1285 consume_skb(skb); 1286 return NET_RX_SUCCESS; 1287 } 1288 1289drop: 1290 kfree_skb_reason(skb, reason); 1291 return NET_RX_DROP; 1292csum_error: 1293 reason = SKB_DROP_REASON_ICMP_CSUM; 1294 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1295error: 1296 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1297 goto drop; 1298} 1299 1300static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1301{ 1302 struct icmp_extobj_hdr *objh, _objh; 1303 struct icmp_ext_hdr *exth, _exth; 1304 u16 olen; 1305 1306 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1307 if (!exth) 1308 return false; 1309 if (exth->version != 2) 1310 return true; 1311 1312 if (exth->checksum && 1313 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1314 return false; 1315 1316 off += sizeof(_exth); 1317 while (off < skb->len) { 1318 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1319 if (!objh) 1320 return false; 1321 1322 olen = ntohs(objh->length); 1323 if (olen < sizeof(_objh)) 1324 return false; 1325 1326 off += olen; 1327 if (off > skb->len) 1328 return false; 1329 } 1330 1331 return true; 1332} 1333 1334void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1335 struct sock_ee_data_rfc4884 *out, 1336 int thlen, int off) 1337{ 1338 int hlen; 1339 1340 /* original datagram headers: end of icmph to payload (skb->data) */ 1341 hlen = -skb_transport_offset(skb) - thlen; 1342 1343 /* per rfc 4884: minimal datagram length of 128 bytes */ 1344 if (off < 128 || off < hlen) 1345 return; 1346 1347 /* kernel has stripped headers: return payload offset in bytes */ 1348 off -= hlen; 1349 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1350 return; 1351 1352 out->len = off; 1353 1354 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1355 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1356} 1357EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1358 1359int icmp_err(struct sk_buff *skb, u32 info) 1360{ 1361 struct iphdr *iph = (struct iphdr *)skb->data; 1362 int offset = iph->ihl<<2; 1363 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1364 int type = icmp_hdr(skb)->type; 1365 int code = icmp_hdr(skb)->code; 1366 struct net *net = dev_net(skb->dev); 1367 1368 /* 1369 * Use ping_err to handle all icmp errors except those 1370 * triggered by ICMP_ECHOREPLY which sent from kernel. 1371 */ 1372 if (icmph->type != ICMP_ECHOREPLY) { 1373 ping_err(skb, offset, info); 1374 return 0; 1375 } 1376 1377 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1378 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1379 else if (type == ICMP_REDIRECT) 1380 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1381 1382 return 0; 1383} 1384 1385/* 1386 * This table is the definition of how we handle ICMP. 1387 */ 1388static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1389 [ICMP_ECHOREPLY] = { 1390 .handler = ping_rcv, 1391 }, 1392 [1] = { 1393 .handler = icmp_discard, 1394 .error = 1, 1395 }, 1396 [2] = { 1397 .handler = icmp_discard, 1398 .error = 1, 1399 }, 1400 [ICMP_DEST_UNREACH] = { 1401 .handler = icmp_unreach, 1402 .error = 1, 1403 }, 1404 [ICMP_SOURCE_QUENCH] = { 1405 .handler = icmp_unreach, 1406 .error = 1, 1407 }, 1408 [ICMP_REDIRECT] = { 1409 .handler = icmp_redirect, 1410 .error = 1, 1411 }, 1412 [6] = { 1413 .handler = icmp_discard, 1414 .error = 1, 1415 }, 1416 [7] = { 1417 .handler = icmp_discard, 1418 .error = 1, 1419 }, 1420 [ICMP_ECHO] = { 1421 .handler = icmp_echo, 1422 }, 1423 [9] = { 1424 .handler = icmp_discard, 1425 .error = 1, 1426 }, 1427 [10] = { 1428 .handler = icmp_discard, 1429 .error = 1, 1430 }, 1431 [ICMP_TIME_EXCEEDED] = { 1432 .handler = icmp_unreach, 1433 .error = 1, 1434 }, 1435 [ICMP_PARAMETERPROB] = { 1436 .handler = icmp_unreach, 1437 .error = 1, 1438 }, 1439 [ICMP_TIMESTAMP] = { 1440 .handler = icmp_timestamp, 1441 }, 1442 [ICMP_TIMESTAMPREPLY] = { 1443 .handler = icmp_discard, 1444 }, 1445 [ICMP_INFO_REQUEST] = { 1446 .handler = icmp_discard, 1447 }, 1448 [ICMP_INFO_REPLY] = { 1449 .handler = icmp_discard, 1450 }, 1451 [ICMP_ADDRESS] = { 1452 .handler = icmp_discard, 1453 }, 1454 [ICMP_ADDRESSREPLY] = { 1455 .handler = icmp_discard, 1456 }, 1457}; 1458 1459static int __net_init icmp_sk_init(struct net *net) 1460{ 1461 /* Control parameters for ECHO replies. */ 1462 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1463 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1464 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1465 1466 /* Control parameter - ignore bogus broadcast responses? */ 1467 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1468 1469 /* 1470 * Configurable global rate limit. 1471 * 1472 * ratelimit defines tokens/packet consumed for dst->rate_token 1473 * bucket ratemask defines which icmp types are ratelimited by 1474 * setting it's bit position. 1475 * 1476 * default: 1477 * dest unreachable (3), source quench (4), 1478 * time exceeded (11), parameter problem (12) 1479 */ 1480 1481 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1482 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1483 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1484 1485 return 0; 1486} 1487 1488static struct pernet_operations __net_initdata icmp_sk_ops = { 1489 .init = icmp_sk_init, 1490}; 1491 1492int __init icmp_init(void) 1493{ 1494 int err, i; 1495 1496 for_each_possible_cpu(i) { 1497 struct sock *sk; 1498 1499 err = inet_ctl_sock_create(&sk, PF_INET, 1500 SOCK_RAW, IPPROTO_ICMP, &init_net); 1501 if (err < 0) 1502 return err; 1503 1504 per_cpu(ipv4_icmp_sk, i) = sk; 1505 1506 /* Enough space for 2 64K ICMP packets, including 1507 * sk_buff/skb_shared_info struct overhead. 1508 */ 1509 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1510 1511 /* 1512 * Speedup sock_wfree() 1513 */ 1514 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1515 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1516 } 1517 return register_pernet_subsys(&icmp_sk_ops); 1518} 1519