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 */ 100 101 struct 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'. */ 116 117 const 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 }; 183 EXPORT_SYMBOL(icmp_err_convert); 184 185 /* 186 * ICMP control array. This specifies what to do with each ICMP. 187 */ 188 189 struct icmp_control { 190 enum skb_drop_reason (*handler)(struct sk_buff *skb); 191 short error; /* This ICMP is classed as an error message */ 192 }; 193 194 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 195 196 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 197 198 /* Called with BH disabled */ 199 static 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 } 214 215 static inline void icmp_xmit_unlock(struct sock *sk) 216 { 217 sock_net_set(sk, &init_net); 218 spin_unlock(&sk->sk_lock.slock); 219 } 220 221 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 222 int sysctl_icmp_msgs_burst __read_mostly = 50; 223 224 static 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 */ 239 bool 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 } 274 EXPORT_SYMBOL(icmp_global_allow); 275 276 static 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 } 291 292 static 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 */ 307 308 static 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); 329 out: 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 */ 338 void 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 */ 348 static 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 } 363 364 static 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 */ 397 398 static 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); 454 out_unlock: 455 icmp_xmit_unlock(sk); 456 out_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 */ 466 static 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 } 476 477 static 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 dst_entry *dst, *dst2; 487 struct rtable *rt, *rt2; 488 struct flowi4 fl4_dec; 489 int err; 490 491 memset(fl4, 0, sizeof(*fl4)); 492 fl4->daddr = (param->replyopts.opt.opt.srr ? 493 param->replyopts.opt.opt.faddr : iph->saddr); 494 fl4->saddr = saddr; 495 fl4->flowi4_mark = mark; 496 fl4->flowi4_uid = sock_net_uid(net, NULL); 497 fl4->flowi4_tos = RT_TOS(tos); 498 fl4->flowi4_proto = IPPROTO_ICMP; 499 fl4->fl4_icmp_type = type; 500 fl4->fl4_icmp_code = code; 501 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 502 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 503 504 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 505 rt = ip_route_output_key_hash(net, fl4, skb_in); 506 if (IS_ERR(rt)) 507 return rt; 508 509 /* No need to clone since we're just using its address. */ 510 rt2 = rt; 511 512 dst = xfrm_lookup(net, &rt->dst, 513 flowi4_to_flowi(fl4), NULL, 0); 514 rt = dst_rtable(dst); 515 if (!IS_ERR(dst)) { 516 if (rt != rt2) 517 return rt; 518 } else if (PTR_ERR(dst) == -EPERM) { 519 rt = NULL; 520 } else { 521 return rt; 522 } 523 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 524 if (err) 525 goto relookup_failed; 526 527 if (inet_addr_type_dev_table(net, route_lookup_dev, 528 fl4_dec.saddr) == RTN_LOCAL) { 529 rt2 = __ip_route_output_key(net, &fl4_dec); 530 if (IS_ERR(rt2)) 531 err = PTR_ERR(rt2); 532 } else { 533 struct flowi4 fl4_2 = {}; 534 unsigned long orefdst; 535 536 fl4_2.daddr = fl4_dec.saddr; 537 rt2 = ip_route_output_key(net, &fl4_2); 538 if (IS_ERR(rt2)) { 539 err = PTR_ERR(rt2); 540 goto relookup_failed; 541 } 542 /* Ugh! */ 543 orefdst = skb_in->_skb_refdst; /* save old refdst */ 544 skb_dst_set(skb_in, NULL); 545 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 546 RT_TOS(tos), rt2->dst.dev); 547 548 dst_release(&rt2->dst); 549 rt2 = skb_rtable(skb_in); 550 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 551 } 552 553 if (err) 554 goto relookup_failed; 555 556 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 557 XFRM_LOOKUP_ICMP); 558 rt2 = dst_rtable(dst2); 559 if (!IS_ERR(dst2)) { 560 dst_release(&rt->dst); 561 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 562 rt = rt2; 563 } else if (PTR_ERR(dst2) == -EPERM) { 564 if (rt) 565 dst_release(&rt->dst); 566 return rt2; 567 } else { 568 err = PTR_ERR(dst2); 569 goto relookup_failed; 570 } 571 return rt; 572 573 relookup_failed: 574 if (rt) 575 return rt; 576 return ERR_PTR(err); 577 } 578 579 /* 580 * Send an ICMP message in response to a situation 581 * 582 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 583 * MAY send more (we do). 584 * MUST NOT change this header information. 585 * MUST NOT reply to a multicast/broadcast IP address. 586 * MUST NOT reply to a multicast/broadcast MAC address. 587 * MUST reply to only the first fragment. 588 */ 589 590 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 591 const struct ip_options *opt) 592 { 593 struct iphdr *iph; 594 int room; 595 struct icmp_bxm icmp_param; 596 struct rtable *rt = skb_rtable(skb_in); 597 struct ipcm_cookie ipc; 598 struct flowi4 fl4; 599 __be32 saddr; 600 u8 tos; 601 u32 mark; 602 struct net *net; 603 struct sock *sk; 604 605 if (!rt) 606 goto out; 607 608 if (rt->dst.dev) 609 net = dev_net(rt->dst.dev); 610 else if (skb_in->dev) 611 net = dev_net(skb_in->dev); 612 else 613 goto out; 614 615 /* 616 * Find the original header. It is expected to be valid, of course. 617 * Check this, icmp_send is called from the most obscure devices 618 * sometimes. 619 */ 620 iph = ip_hdr(skb_in); 621 622 if ((u8 *)iph < skb_in->head || 623 (skb_network_header(skb_in) + sizeof(*iph)) > 624 skb_tail_pointer(skb_in)) 625 goto out; 626 627 /* 628 * No replies to physical multicast/broadcast 629 */ 630 if (skb_in->pkt_type != PACKET_HOST) 631 goto out; 632 633 /* 634 * Now check at the protocol level 635 */ 636 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 637 goto out; 638 639 /* 640 * Only reply to fragment 0. We byte re-order the constant 641 * mask for efficiency. 642 */ 643 if (iph->frag_off & htons(IP_OFFSET)) 644 goto out; 645 646 /* 647 * If we send an ICMP error to an ICMP error a mess would result.. 648 */ 649 if (icmp_pointers[type].error) { 650 /* 651 * We are an error, check if we are replying to an 652 * ICMP error 653 */ 654 if (iph->protocol == IPPROTO_ICMP) { 655 u8 _inner_type, *itp; 656 657 itp = skb_header_pointer(skb_in, 658 skb_network_header(skb_in) + 659 (iph->ihl << 2) + 660 offsetof(struct icmphdr, 661 type) - 662 skb_in->data, 663 sizeof(_inner_type), 664 &_inner_type); 665 if (!itp) 666 goto out; 667 668 /* 669 * Assume any unknown ICMP type is an error. This 670 * isn't specified by the RFC, but think about it.. 671 */ 672 if (*itp > NR_ICMP_TYPES || 673 icmp_pointers[*itp].error) 674 goto out; 675 } 676 } 677 678 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 679 local_bh_disable(); 680 681 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 682 * incoming dev is loopback. If outgoing dev change to not be 683 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 684 */ 685 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 686 !icmpv4_global_allow(net, type, code)) 687 goto out_bh_enable; 688 689 sk = icmp_xmit_lock(net); 690 if (!sk) 691 goto out_bh_enable; 692 693 /* 694 * Construct source address and options. 695 */ 696 697 saddr = iph->daddr; 698 if (!(rt->rt_flags & RTCF_LOCAL)) { 699 struct net_device *dev = NULL; 700 701 rcu_read_lock(); 702 if (rt_is_input_route(rt) && 703 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 704 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 705 706 if (dev) 707 saddr = inet_select_addr(dev, iph->saddr, 708 RT_SCOPE_LINK); 709 else 710 saddr = 0; 711 rcu_read_unlock(); 712 } 713 714 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 715 IPTOS_PREC_INTERNETCONTROL) : 716 iph->tos; 717 mark = IP4_REPLY_MARK(net, skb_in->mark); 718 719 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 720 goto out_unlock; 721 722 723 /* 724 * Prepare data for ICMP header. 725 */ 726 727 icmp_param.data.icmph.type = type; 728 icmp_param.data.icmph.code = code; 729 icmp_param.data.icmph.un.gateway = info; 730 icmp_param.data.icmph.checksum = 0; 731 icmp_param.skb = skb_in; 732 icmp_param.offset = skb_network_offset(skb_in); 733 inet_sk(sk)->tos = tos; 734 ipcm_init(&ipc); 735 ipc.addr = iph->saddr; 736 ipc.opt = &icmp_param.replyopts.opt; 737 ipc.sockc.mark = mark; 738 739 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 740 type, code, &icmp_param); 741 if (IS_ERR(rt)) 742 goto out_unlock; 743 744 /* peer icmp_ratelimit */ 745 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 746 goto ende; 747 748 /* RFC says return as much as we can without exceeding 576 bytes. */ 749 750 room = dst_mtu(&rt->dst); 751 if (room > 576) 752 room = 576; 753 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 754 room -= sizeof(struct icmphdr); 755 /* Guard against tiny mtu. We need to include at least one 756 * IP network header for this message to make any sense. 757 */ 758 if (room <= (int)sizeof(struct iphdr)) 759 goto ende; 760 761 icmp_param.data_len = skb_in->len - icmp_param.offset; 762 if (icmp_param.data_len > room) 763 icmp_param.data_len = room; 764 icmp_param.head_len = sizeof(struct icmphdr); 765 766 /* if we don't have a source address at this point, fall back to the 767 * dummy address instead of sending out a packet with a source address 768 * of 0.0.0.0 769 */ 770 if (!fl4.saddr) 771 fl4.saddr = htonl(INADDR_DUMMY); 772 773 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 774 ende: 775 ip_rt_put(rt); 776 out_unlock: 777 icmp_xmit_unlock(sk); 778 out_bh_enable: 779 local_bh_enable(); 780 out:; 781 } 782 EXPORT_SYMBOL(__icmp_send); 783 784 #if IS_ENABLED(CONFIG_NF_NAT) 785 #include <net/netfilter/nf_conntrack.h> 786 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 787 { 788 struct sk_buff *cloned_skb = NULL; 789 struct ip_options opts = { 0 }; 790 enum ip_conntrack_info ctinfo; 791 struct nf_conn *ct; 792 __be32 orig_ip; 793 794 ct = nf_ct_get(skb_in, &ctinfo); 795 if (!ct || !(ct->status & IPS_SRC_NAT)) { 796 __icmp_send(skb_in, type, code, info, &opts); 797 return; 798 } 799 800 if (skb_shared(skb_in)) 801 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 802 803 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 804 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 805 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 806 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 807 goto out; 808 809 orig_ip = ip_hdr(skb_in)->saddr; 810 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 811 __icmp_send(skb_in, type, code, info, &opts); 812 ip_hdr(skb_in)->saddr = orig_ip; 813 out: 814 consume_skb(cloned_skb); 815 } 816 EXPORT_SYMBOL(icmp_ndo_send); 817 #endif 818 819 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 820 { 821 const struct iphdr *iph = (const struct iphdr *)skb->data; 822 const struct net_protocol *ipprot; 823 int protocol = iph->protocol; 824 825 /* Checkin full IP header plus 8 bytes of protocol to 826 * avoid additional coding at protocol handlers. 827 */ 828 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 829 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 830 return; 831 } 832 833 raw_icmp_error(skb, protocol, info); 834 835 ipprot = rcu_dereference(inet_protos[protocol]); 836 if (ipprot && ipprot->err_handler) 837 ipprot->err_handler(skb, info); 838 } 839 840 static bool icmp_tag_validation(int proto) 841 { 842 bool ok; 843 844 rcu_read_lock(); 845 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 846 rcu_read_unlock(); 847 return ok; 848 } 849 850 /* 851 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 852 * ICMP_PARAMETERPROB. 853 */ 854 855 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 856 { 857 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 858 const struct iphdr *iph; 859 struct icmphdr *icmph; 860 struct net *net; 861 u32 info = 0; 862 863 net = dev_net(skb_dst(skb)->dev); 864 865 /* 866 * Incomplete header ? 867 * Only checks for the IP header, there should be an 868 * additional check for longer headers in upper levels. 869 */ 870 871 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 872 goto out_err; 873 874 icmph = icmp_hdr(skb); 875 iph = (const struct iphdr *)skb->data; 876 877 if (iph->ihl < 5) { /* Mangled header, drop. */ 878 reason = SKB_DROP_REASON_IP_INHDR; 879 goto out_err; 880 } 881 882 switch (icmph->type) { 883 case ICMP_DEST_UNREACH: 884 switch (icmph->code & 15) { 885 case ICMP_NET_UNREACH: 886 case ICMP_HOST_UNREACH: 887 case ICMP_PROT_UNREACH: 888 case ICMP_PORT_UNREACH: 889 break; 890 case ICMP_FRAG_NEEDED: 891 /* for documentation of the ip_no_pmtu_disc 892 * values please see 893 * Documentation/networking/ip-sysctl.rst 894 */ 895 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 896 default: 897 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 898 &iph->daddr); 899 break; 900 case 2: 901 goto out; 902 case 3: 903 if (!icmp_tag_validation(iph->protocol)) 904 goto out; 905 fallthrough; 906 case 0: 907 info = ntohs(icmph->un.frag.mtu); 908 } 909 break; 910 case ICMP_SR_FAILED: 911 net_dbg_ratelimited("%pI4: Source Route Failed\n", 912 &iph->daddr); 913 break; 914 default: 915 break; 916 } 917 if (icmph->code > NR_ICMP_UNREACH) 918 goto out; 919 break; 920 case ICMP_PARAMETERPROB: 921 info = ntohl(icmph->un.gateway) >> 24; 922 break; 923 case ICMP_TIME_EXCEEDED: 924 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 925 if (icmph->code == ICMP_EXC_FRAGTIME) 926 goto out; 927 break; 928 } 929 930 /* 931 * Throw it at our lower layers 932 * 933 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 934 * header. 935 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 936 * transport layer. 937 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 938 * transport layer. 939 */ 940 941 /* 942 * Check the other end isn't violating RFC 1122. Some routers send 943 * bogus responses to broadcast frames. If you see this message 944 * first check your netmask matches at both ends, if it does then 945 * get the other vendor to fix their kit. 946 */ 947 948 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 949 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 950 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 951 &ip_hdr(skb)->saddr, 952 icmph->type, icmph->code, 953 &iph->daddr, skb->dev->name); 954 goto out; 955 } 956 957 icmp_socket_deliver(skb, info); 958 959 out: 960 return reason; 961 out_err: 962 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 963 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 964 } 965 966 967 /* 968 * Handle ICMP_REDIRECT. 969 */ 970 971 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 972 { 973 if (skb->len < sizeof(struct iphdr)) { 974 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 975 return SKB_DROP_REASON_PKT_TOO_SMALL; 976 } 977 978 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 979 /* there aught to be a stat */ 980 return SKB_DROP_REASON_NOMEM; 981 } 982 983 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 984 return SKB_NOT_DROPPED_YET; 985 } 986 987 /* 988 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 989 * 990 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 991 * requests. 992 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 993 * included in the reply. 994 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 995 * echo requests, MUST have default=NOT. 996 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 997 * Extended Echo Functionality, MUST be disabled by default 998 * See also WRT handling of options once they are done and working. 999 */ 1000 1001 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1002 { 1003 struct icmp_bxm icmp_param; 1004 struct net *net; 1005 1006 net = dev_net(skb_dst(skb)->dev); 1007 /* should there be an ICMP stat for ignored echos? */ 1008 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1009 return SKB_NOT_DROPPED_YET; 1010 1011 icmp_param.data.icmph = *icmp_hdr(skb); 1012 icmp_param.skb = skb; 1013 icmp_param.offset = 0; 1014 icmp_param.data_len = skb->len; 1015 icmp_param.head_len = sizeof(struct icmphdr); 1016 1017 if (icmp_param.data.icmph.type == ICMP_ECHO) 1018 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1019 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1020 return SKB_NOT_DROPPED_YET; 1021 1022 icmp_reply(&icmp_param, skb); 1023 return SKB_NOT_DROPPED_YET; 1024 } 1025 1026 /* Helper for icmp_echo and icmpv6_echo_reply. 1027 * Searches for net_device that matches PROBE interface identifier 1028 * and builds PROBE reply message in icmphdr. 1029 * 1030 * Returns false if PROBE responses are disabled via sysctl 1031 */ 1032 1033 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1034 { 1035 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1036 struct icmp_ext_echo_iio *iio, _iio; 1037 struct net *net = dev_net(skb->dev); 1038 struct inet6_dev *in6_dev; 1039 struct in_device *in_dev; 1040 struct net_device *dev; 1041 char buff[IFNAMSIZ]; 1042 u16 ident_len; 1043 u8 status; 1044 1045 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1046 return false; 1047 1048 /* We currently only support probing interfaces on the proxy node 1049 * Check to ensure L-bit is set 1050 */ 1051 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1052 return false; 1053 /* Clear status bits in reply message */ 1054 icmphdr->un.echo.sequence &= htons(0xFF00); 1055 if (icmphdr->type == ICMP_EXT_ECHO) 1056 icmphdr->type = ICMP_EXT_ECHOREPLY; 1057 else 1058 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1059 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1060 /* Size of iio is class_type dependent. 1061 * Only check header here and assign length based on ctype in the switch statement 1062 */ 1063 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1064 if (!ext_hdr || !iio) 1065 goto send_mal_query; 1066 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1067 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1068 goto send_mal_query; 1069 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1070 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1071 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1072 if (!iio) 1073 goto send_mal_query; 1074 1075 status = 0; 1076 dev = NULL; 1077 switch (iio->extobj_hdr.class_type) { 1078 case ICMP_EXT_ECHO_CTYPE_NAME: 1079 if (ident_len >= IFNAMSIZ) 1080 goto send_mal_query; 1081 memset(buff, 0, sizeof(buff)); 1082 memcpy(buff, &iio->ident.name, ident_len); 1083 dev = dev_get_by_name(net, buff); 1084 break; 1085 case ICMP_EXT_ECHO_CTYPE_INDEX: 1086 if (ident_len != sizeof(iio->ident.ifindex)) 1087 goto send_mal_query; 1088 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1089 break; 1090 case ICMP_EXT_ECHO_CTYPE_ADDR: 1091 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1092 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1093 iio->ident.addr.ctype3_hdr.addrlen) 1094 goto send_mal_query; 1095 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1096 case ICMP_AFI_IP: 1097 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1098 goto send_mal_query; 1099 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1100 break; 1101 #if IS_ENABLED(CONFIG_IPV6) 1102 case ICMP_AFI_IP6: 1103 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1104 goto send_mal_query; 1105 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1106 dev_hold(dev); 1107 break; 1108 #endif 1109 default: 1110 goto send_mal_query; 1111 } 1112 break; 1113 default: 1114 goto send_mal_query; 1115 } 1116 if (!dev) { 1117 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1118 return true; 1119 } 1120 /* Fill bits in reply message */ 1121 if (dev->flags & IFF_UP) 1122 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1123 1124 in_dev = __in_dev_get_rcu(dev); 1125 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1126 status |= ICMP_EXT_ECHOREPLY_IPV4; 1127 1128 in6_dev = __in6_dev_get(dev); 1129 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1130 status |= ICMP_EXT_ECHOREPLY_IPV6; 1131 1132 dev_put(dev); 1133 icmphdr->un.echo.sequence |= htons(status); 1134 return true; 1135 send_mal_query: 1136 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1137 return true; 1138 } 1139 EXPORT_SYMBOL_GPL(icmp_build_probe); 1140 1141 /* 1142 * Handle ICMP Timestamp requests. 1143 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1144 * SHOULD be in the kernel for minimum random latency. 1145 * MUST be accurate to a few minutes. 1146 * MUST be updated at least at 15Hz. 1147 */ 1148 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1149 { 1150 struct icmp_bxm icmp_param; 1151 /* 1152 * Too short. 1153 */ 1154 if (skb->len < 4) 1155 goto out_err; 1156 1157 /* 1158 * Fill in the current time as ms since midnight UT: 1159 */ 1160 icmp_param.data.times[1] = inet_current_timestamp(); 1161 icmp_param.data.times[2] = icmp_param.data.times[1]; 1162 1163 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1164 1165 icmp_param.data.icmph = *icmp_hdr(skb); 1166 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1167 icmp_param.data.icmph.code = 0; 1168 icmp_param.skb = skb; 1169 icmp_param.offset = 0; 1170 icmp_param.data_len = 0; 1171 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1172 icmp_reply(&icmp_param, skb); 1173 return SKB_NOT_DROPPED_YET; 1174 1175 out_err: 1176 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1177 return SKB_DROP_REASON_PKT_TOO_SMALL; 1178 } 1179 1180 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1181 { 1182 /* pretend it was a success */ 1183 return SKB_NOT_DROPPED_YET; 1184 } 1185 1186 /* 1187 * Deal with incoming ICMP packets. 1188 */ 1189 int icmp_rcv(struct sk_buff *skb) 1190 { 1191 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1192 struct rtable *rt = skb_rtable(skb); 1193 struct net *net = dev_net(rt->dst.dev); 1194 struct icmphdr *icmph; 1195 1196 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1197 struct sec_path *sp = skb_sec_path(skb); 1198 int nh; 1199 1200 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1201 XFRM_STATE_ICMP)) { 1202 reason = SKB_DROP_REASON_XFRM_POLICY; 1203 goto drop; 1204 } 1205 1206 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1207 goto drop; 1208 1209 nh = skb_network_offset(skb); 1210 skb_set_network_header(skb, sizeof(*icmph)); 1211 1212 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1213 skb)) { 1214 reason = SKB_DROP_REASON_XFRM_POLICY; 1215 goto drop; 1216 } 1217 1218 skb_set_network_header(skb, nh); 1219 } 1220 1221 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1222 1223 if (skb_checksum_simple_validate(skb)) 1224 goto csum_error; 1225 1226 if (!pskb_pull(skb, sizeof(*icmph))) 1227 goto error; 1228 1229 icmph = icmp_hdr(skb); 1230 1231 ICMPMSGIN_INC_STATS(net, icmph->type); 1232 1233 /* Check for ICMP Extended Echo (PROBE) messages */ 1234 if (icmph->type == ICMP_EXT_ECHO) { 1235 /* We can't use icmp_pointers[].handler() because it is an array of 1236 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1237 */ 1238 reason = icmp_echo(skb); 1239 goto reason_check; 1240 } 1241 1242 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1243 reason = ping_rcv(skb); 1244 goto reason_check; 1245 } 1246 1247 /* 1248 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1249 * 1250 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1251 * discarded. 1252 */ 1253 if (icmph->type > NR_ICMP_TYPES) { 1254 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1255 goto error; 1256 } 1257 1258 /* 1259 * Parse the ICMP message 1260 */ 1261 1262 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1263 /* 1264 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1265 * silently ignored (we let user decide with a sysctl). 1266 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1267 * discarded if to broadcast/multicast. 1268 */ 1269 if ((icmph->type == ICMP_ECHO || 1270 icmph->type == ICMP_TIMESTAMP) && 1271 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1272 reason = SKB_DROP_REASON_INVALID_PROTO; 1273 goto error; 1274 } 1275 if (icmph->type != ICMP_ECHO && 1276 icmph->type != ICMP_TIMESTAMP && 1277 icmph->type != ICMP_ADDRESS && 1278 icmph->type != ICMP_ADDRESSREPLY) { 1279 reason = SKB_DROP_REASON_INVALID_PROTO; 1280 goto error; 1281 } 1282 } 1283 1284 reason = icmp_pointers[icmph->type].handler(skb); 1285 reason_check: 1286 if (!reason) { 1287 consume_skb(skb); 1288 return NET_RX_SUCCESS; 1289 } 1290 1291 drop: 1292 kfree_skb_reason(skb, reason); 1293 return NET_RX_DROP; 1294 csum_error: 1295 reason = SKB_DROP_REASON_ICMP_CSUM; 1296 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1297 error: 1298 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1299 goto drop; 1300 } 1301 1302 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1303 { 1304 struct icmp_extobj_hdr *objh, _objh; 1305 struct icmp_ext_hdr *exth, _exth; 1306 u16 olen; 1307 1308 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1309 if (!exth) 1310 return false; 1311 if (exth->version != 2) 1312 return true; 1313 1314 if (exth->checksum && 1315 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1316 return false; 1317 1318 off += sizeof(_exth); 1319 while (off < skb->len) { 1320 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1321 if (!objh) 1322 return false; 1323 1324 olen = ntohs(objh->length); 1325 if (olen < sizeof(_objh)) 1326 return false; 1327 1328 off += olen; 1329 if (off > skb->len) 1330 return false; 1331 } 1332 1333 return true; 1334 } 1335 1336 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1337 struct sock_ee_data_rfc4884 *out, 1338 int thlen, int off) 1339 { 1340 int hlen; 1341 1342 /* original datagram headers: end of icmph to payload (skb->data) */ 1343 hlen = -skb_transport_offset(skb) - thlen; 1344 1345 /* per rfc 4884: minimal datagram length of 128 bytes */ 1346 if (off < 128 || off < hlen) 1347 return; 1348 1349 /* kernel has stripped headers: return payload offset in bytes */ 1350 off -= hlen; 1351 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1352 return; 1353 1354 out->len = off; 1355 1356 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1357 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1358 } 1359 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1360 1361 int icmp_err(struct sk_buff *skb, u32 info) 1362 { 1363 struct iphdr *iph = (struct iphdr *)skb->data; 1364 int offset = iph->ihl<<2; 1365 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1366 int type = icmp_hdr(skb)->type; 1367 int code = icmp_hdr(skb)->code; 1368 struct net *net = dev_net(skb->dev); 1369 1370 /* 1371 * Use ping_err to handle all icmp errors except those 1372 * triggered by ICMP_ECHOREPLY which sent from kernel. 1373 */ 1374 if (icmph->type != ICMP_ECHOREPLY) { 1375 ping_err(skb, offset, info); 1376 return 0; 1377 } 1378 1379 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1380 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1381 else if (type == ICMP_REDIRECT) 1382 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1383 1384 return 0; 1385 } 1386 1387 /* 1388 * This table is the definition of how we handle ICMP. 1389 */ 1390 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1391 [ICMP_ECHOREPLY] = { 1392 .handler = ping_rcv, 1393 }, 1394 [1] = { 1395 .handler = icmp_discard, 1396 .error = 1, 1397 }, 1398 [2] = { 1399 .handler = icmp_discard, 1400 .error = 1, 1401 }, 1402 [ICMP_DEST_UNREACH] = { 1403 .handler = icmp_unreach, 1404 .error = 1, 1405 }, 1406 [ICMP_SOURCE_QUENCH] = { 1407 .handler = icmp_unreach, 1408 .error = 1, 1409 }, 1410 [ICMP_REDIRECT] = { 1411 .handler = icmp_redirect, 1412 .error = 1, 1413 }, 1414 [6] = { 1415 .handler = icmp_discard, 1416 .error = 1, 1417 }, 1418 [7] = { 1419 .handler = icmp_discard, 1420 .error = 1, 1421 }, 1422 [ICMP_ECHO] = { 1423 .handler = icmp_echo, 1424 }, 1425 [9] = { 1426 .handler = icmp_discard, 1427 .error = 1, 1428 }, 1429 [10] = { 1430 .handler = icmp_discard, 1431 .error = 1, 1432 }, 1433 [ICMP_TIME_EXCEEDED] = { 1434 .handler = icmp_unreach, 1435 .error = 1, 1436 }, 1437 [ICMP_PARAMETERPROB] = { 1438 .handler = icmp_unreach, 1439 .error = 1, 1440 }, 1441 [ICMP_TIMESTAMP] = { 1442 .handler = icmp_timestamp, 1443 }, 1444 [ICMP_TIMESTAMPREPLY] = { 1445 .handler = icmp_discard, 1446 }, 1447 [ICMP_INFO_REQUEST] = { 1448 .handler = icmp_discard, 1449 }, 1450 [ICMP_INFO_REPLY] = { 1451 .handler = icmp_discard, 1452 }, 1453 [ICMP_ADDRESS] = { 1454 .handler = icmp_discard, 1455 }, 1456 [ICMP_ADDRESSREPLY] = { 1457 .handler = icmp_discard, 1458 }, 1459 }; 1460 1461 static int __net_init icmp_sk_init(struct net *net) 1462 { 1463 /* Control parameters for ECHO replies. */ 1464 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1465 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1466 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1467 1468 /* Control parameter - ignore bogus broadcast responses? */ 1469 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1470 1471 /* 1472 * Configurable global rate limit. 1473 * 1474 * ratelimit defines tokens/packet consumed for dst->rate_token 1475 * bucket ratemask defines which icmp types are ratelimited by 1476 * setting it's bit position. 1477 * 1478 * default: 1479 * dest unreachable (3), source quench (4), 1480 * time exceeded (11), parameter problem (12) 1481 */ 1482 1483 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1484 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1485 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1486 1487 return 0; 1488 } 1489 1490 static struct pernet_operations __net_initdata icmp_sk_ops = { 1491 .init = icmp_sk_init, 1492 }; 1493 1494 int __init icmp_init(void) 1495 { 1496 int err, i; 1497 1498 for_each_possible_cpu(i) { 1499 struct sock *sk; 1500 1501 err = inet_ctl_sock_create(&sk, PF_INET, 1502 SOCK_RAW, IPPROTO_ICMP, &init_net); 1503 if (err < 0) 1504 return err; 1505 1506 per_cpu(ipv4_icmp_sk, i) = sk; 1507 1508 /* Enough space for 2 64K ICMP packets, including 1509 * sk_buff/skb_shared_info struct overhead. 1510 */ 1511 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1512 1513 /* 1514 * Speedup sock_wfree() 1515 */ 1516 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1517 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1518 } 1519 return register_pernet_subsys(&icmp_sk_ops); 1520 } 1521