1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * NET3: Implementation of the ICMP protocol layer. 4 * 5 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 6 * 7 * Some of the function names and the icmp unreach table for this 8 * module were derived from [icmp.c 1.0.11 06/02/93] by 9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 10 * Other than that this module is a complete rewrite. 11 * 12 * Fixes: 13 * Clemens Fruhwirth : introduce global icmp rate limiting 14 * with icmp type masking ability instead 15 * of broken per type icmp timeouts. 16 * Mike Shaver : RFC1122 checks. 17 * Alan Cox : Multicast ping reply as self. 18 * Alan Cox : Fix atomicity lockup in ip_build_xmit 19 * call. 20 * Alan Cox : Added 216,128 byte paths to the MTU 21 * code. 22 * Martin Mares : RFC1812 checks. 23 * Martin Mares : Can be configured to follow redirects 24 * if acting as a router _without_ a 25 * routing protocol (RFC 1812). 26 * Martin Mares : Echo requests may be configured to 27 * be ignored (RFC 1812). 28 * Martin Mares : Limitation of ICMP error message 29 * transmit rate (RFC 1812). 30 * Martin Mares : TOS and Precedence set correctly 31 * (RFC 1812). 32 * Martin Mares : Now copying as much data from the 33 * original packet as we can without 34 * exceeding 576 bytes (RFC 1812). 35 * Willy Konynenberg : Transparent proxying support. 36 * Keith Owens : RFC1191 correction for 4.2BSD based 37 * path MTU bug. 38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 39 * valid (RFC 1812). 40 * Andi Kleen : Check all packet lengths properly 41 * and moved all kfree_skb() up to 42 * icmp_rcv. 43 * Andi Kleen : Move the rate limit bookkeeping 44 * into the dest entry and use a token 45 * bucket filter (thanks to ANK). Make 46 * the rates sysctl configurable. 47 * Yu Tianli : Fixed two ugly bugs in icmp_send 48 * - IP option length was accounted wrongly 49 * - ICMP header length was not accounted 50 * at all. 51 * Tristan Greaves : Added sysctl option to ignore bogus 52 * broadcast responses from broken routers. 53 * 54 * To Fix: 55 * 56 * - Should use skb_pull() instead of all the manual checking. 57 * This would also greatly simply some upper layer error handlers. --AK 58 */ 59 60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 61 62 #include <linux/module.h> 63 #include <linux/types.h> 64 #include <linux/jiffies.h> 65 #include <linux/kernel.h> 66 #include <linux/fcntl.h> 67 #include <linux/socket.h> 68 #include <linux/in.h> 69 #include <linux/inet.h> 70 #include <linux/inetdevice.h> 71 #include <linux/netdevice.h> 72 #include <linux/string.h> 73 #include <linux/netfilter_ipv4.h> 74 #include <linux/slab.h> 75 #include <net/snmp.h> 76 #include <net/ip.h> 77 #include <net/route.h> 78 #include <net/protocol.h> 79 #include <net/icmp.h> 80 #include <net/tcp.h> 81 #include <net/udp.h> 82 #include <net/raw.h> 83 #include <net/ping.h> 84 #include <linux/skbuff.h> 85 #include <net/sock.h> 86 #include <linux/errno.h> 87 #include <linux/timer.h> 88 #include <linux/init.h> 89 #include <linux/uaccess.h> 90 #include <net/checksum.h> 91 #include <net/xfrm.h> 92 #include <net/inet_common.h> 93 #include <net/ip_fib.h> 94 #include <net/l3mdev.h> 95 96 /* 97 * Build xmit assembly blocks 98 */ 99 100 struct icmp_bxm { 101 struct sk_buff *skb; 102 int offset; 103 int data_len; 104 105 struct { 106 struct icmphdr icmph; 107 __be32 times[3]; 108 } data; 109 int head_len; 110 struct ip_options_data replyopts; 111 }; 112 113 /* An array of errno for error messages from dest unreach. */ 114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 115 116 const struct icmp_err icmp_err_convert[] = { 117 { 118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 119 .fatal = 0, 120 }, 121 { 122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 123 .fatal = 0, 124 }, 125 { 126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 127 .fatal = 1, 128 }, 129 { 130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 131 .fatal = 1, 132 }, 133 { 134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 135 .fatal = 0, 136 }, 137 { 138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 139 .fatal = 0, 140 }, 141 { 142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 143 .fatal = 1, 144 }, 145 { 146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 147 .fatal = 1, 148 }, 149 { 150 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 151 .fatal = 1, 152 }, 153 { 154 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 155 .fatal = 1, 156 }, 157 { 158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 159 .fatal = 1, 160 }, 161 { 162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 163 .fatal = 0, 164 }, 165 { 166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 167 .fatal = 0, 168 }, 169 { 170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 171 .fatal = 1, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 175 .fatal = 1, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 179 .fatal = 1, 180 }, 181 }; 182 EXPORT_SYMBOL(icmp_err_convert); 183 184 /* 185 * ICMP control array. This specifies what to do with each ICMP. 186 */ 187 188 struct icmp_control { 189 enum skb_drop_reason (*handler)(struct sk_buff *skb); 190 short error; /* This ICMP is classed as an error message */ 191 }; 192 193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 194 195 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 196 197 /* Called with BH disabled */ 198 static inline struct sock *icmp_xmit_lock(struct net *net) 199 { 200 struct sock *sk; 201 202 sk = this_cpu_read(ipv4_icmp_sk); 203 204 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 205 /* This can happen if the output path signals a 206 * dst_link_failure() for an outgoing ICMP packet. 207 */ 208 return NULL; 209 } 210 sock_net_set(sk, net); 211 return sk; 212 } 213 214 static inline void icmp_xmit_unlock(struct sock *sk) 215 { 216 sock_net_set(sk, &init_net); 217 spin_unlock(&sk->sk_lock.slock); 218 } 219 220 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 221 int sysctl_icmp_msgs_burst __read_mostly = 50; 222 223 static struct { 224 spinlock_t lock; 225 u32 credit; 226 u32 stamp; 227 } icmp_global = { 228 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 229 }; 230 231 /** 232 * icmp_global_allow - Are we allowed to send one more ICMP message ? 233 * 234 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 235 * Returns false if we reached the limit and can not send another packet. 236 * Note: called with BH disabled 237 */ 238 bool icmp_global_allow(void) 239 { 240 u32 credit, delta, incr = 0, now = (u32)jiffies; 241 bool rc = false; 242 243 /* Check if token bucket is empty and cannot be refilled 244 * without taking the spinlock. The READ_ONCE() are paired 245 * with the following WRITE_ONCE() in this same function. 246 */ 247 if (!READ_ONCE(icmp_global.credit)) { 248 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 249 if (delta < HZ / 50) 250 return false; 251 } 252 253 spin_lock(&icmp_global.lock); 254 delta = min_t(u32, now - icmp_global.stamp, HZ); 255 if (delta >= HZ / 50) { 256 incr = 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 - prandom_u32_max(3), 0); 267 rc = true; 268 } 269 WRITE_ONCE(icmp_global.credit, credit); 270 spin_unlock(&icmp_global.lock); 271 return rc; 272 } 273 EXPORT_SYMBOL(icmp_global_allow); 274 275 static 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) & net->ipv4.sysctl_icmp_ratemask)) 286 return true; 287 288 return false; 289 } 290 291 static 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 return false; 300 } 301 302 /* 303 * Send an ICMP frame. 304 */ 305 306 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 307 struct flowi4 *fl4, int type, int code) 308 { 309 struct dst_entry *dst = &rt->dst; 310 struct inet_peer *peer; 311 bool rc = true; 312 int vif; 313 314 if (icmpv4_mask_allow(net, type, code)) 315 goto out; 316 317 /* No rate limit on loopback */ 318 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 319 goto out; 320 321 vif = l3mdev_master_ifindex(dst->dev); 322 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 323 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit); 324 if (peer) 325 inet_putpeer(peer); 326 out: 327 return rc; 328 } 329 330 /* 331 * Maintain the counters used in the SNMP statistics for outgoing ICMP 332 */ 333 void icmp_out_count(struct net *net, unsigned char type) 334 { 335 ICMPMSGOUT_INC_STATS(net, type); 336 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 337 } 338 339 /* 340 * Checksum each fragment, and on the first include the headers and final 341 * checksum. 342 */ 343 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 344 struct sk_buff *skb) 345 { 346 struct icmp_bxm *icmp_param = from; 347 __wsum csum; 348 349 csum = skb_copy_and_csum_bits(icmp_param->skb, 350 icmp_param->offset + offset, 351 to, len); 352 353 skb->csum = csum_block_add(skb->csum, csum, odd); 354 if (icmp_pointers[icmp_param->data.icmph.type].error) 355 nf_ct_attach(skb, icmp_param->skb); 356 return 0; 357 } 358 359 static void icmp_push_reply(struct sock *sk, 360 struct icmp_bxm *icmp_param, 361 struct flowi4 *fl4, 362 struct ipcm_cookie *ipc, struct rtable **rt) 363 { 364 struct sk_buff *skb; 365 366 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 367 icmp_param->data_len+icmp_param->head_len, 368 icmp_param->head_len, 369 ipc, rt, MSG_DONTWAIT) < 0) { 370 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 371 ip_flush_pending_frames(sk); 372 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 373 struct icmphdr *icmph = icmp_hdr(skb); 374 __wsum csum; 375 struct sk_buff *skb1; 376 377 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 378 (char *)icmph, 379 icmp_param->head_len); 380 skb_queue_walk(&sk->sk_write_queue, skb1) { 381 csum = csum_add(csum, skb1->csum); 382 } 383 icmph->checksum = csum_fold(csum); 384 skb->ip_summed = CHECKSUM_NONE; 385 ip_push_pending_frames(sk, fl4); 386 } 387 } 388 389 /* 390 * Driving logic for building and sending ICMP messages. 391 */ 392 393 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 394 { 395 struct ipcm_cookie ipc; 396 struct rtable *rt = skb_rtable(skb); 397 struct net *net = dev_net(rt->dst.dev); 398 struct flowi4 fl4; 399 struct sock *sk; 400 struct inet_sock *inet; 401 __be32 daddr, saddr; 402 u32 mark = IP4_REPLY_MARK(net, skb->mark); 403 int type = icmp_param->data.icmph.type; 404 int code = icmp_param->data.icmph.code; 405 406 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 407 return; 408 409 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 410 local_bh_disable(); 411 412 /* global icmp_msgs_per_sec */ 413 if (!icmpv4_global_allow(net, type, code)) 414 goto out_bh_enable; 415 416 sk = icmp_xmit_lock(net); 417 if (!sk) 418 goto out_bh_enable; 419 inet = inet_sk(sk); 420 421 icmp_param->data.icmph.checksum = 0; 422 423 ipcm_init(&ipc); 424 inet->tos = ip_hdr(skb)->tos; 425 ipc.sockc.mark = mark; 426 daddr = ipc.addr = ip_hdr(skb)->saddr; 427 saddr = fib_compute_spec_dst(skb); 428 429 if (icmp_param->replyopts.opt.opt.optlen) { 430 ipc.opt = &icmp_param->replyopts.opt; 431 if (ipc.opt->opt.srr) 432 daddr = icmp_param->replyopts.opt.opt.faddr; 433 } 434 memset(&fl4, 0, sizeof(fl4)); 435 fl4.daddr = daddr; 436 fl4.saddr = saddr; 437 fl4.flowi4_mark = mark; 438 fl4.flowi4_uid = sock_net_uid(net, NULL); 439 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 440 fl4.flowi4_proto = IPPROTO_ICMP; 441 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 442 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 443 rt = ip_route_output_key(net, &fl4); 444 if (IS_ERR(rt)) 445 goto out_unlock; 446 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 447 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 448 ip_rt_put(rt); 449 out_unlock: 450 icmp_xmit_unlock(sk); 451 out_bh_enable: 452 local_bh_enable(); 453 } 454 455 /* 456 * The device used for looking up which routing table to use for sending an ICMP 457 * error is preferably the source whenever it is set, which should ensure the 458 * icmp error can be sent to the source host, else lookup using the routing 459 * table of the destination device, else use the main routing table (index 0). 460 */ 461 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 462 { 463 struct net_device *route_lookup_dev = NULL; 464 465 if (skb->dev) 466 route_lookup_dev = skb->dev; 467 else if (skb_dst(skb)) 468 route_lookup_dev = skb_dst(skb)->dev; 469 return route_lookup_dev; 470 } 471 472 static struct rtable *icmp_route_lookup(struct net *net, 473 struct flowi4 *fl4, 474 struct sk_buff *skb_in, 475 const struct iphdr *iph, 476 __be32 saddr, u8 tos, u32 mark, 477 int type, int code, 478 struct icmp_bxm *param) 479 { 480 struct net_device *route_lookup_dev; 481 struct rtable *rt, *rt2; 482 struct flowi4 fl4_dec; 483 int err; 484 485 memset(fl4, 0, sizeof(*fl4)); 486 fl4->daddr = (param->replyopts.opt.opt.srr ? 487 param->replyopts.opt.opt.faddr : iph->saddr); 488 fl4->saddr = saddr; 489 fl4->flowi4_mark = mark; 490 fl4->flowi4_uid = sock_net_uid(net, NULL); 491 fl4->flowi4_tos = RT_TOS(tos); 492 fl4->flowi4_proto = IPPROTO_ICMP; 493 fl4->fl4_icmp_type = type; 494 fl4->fl4_icmp_code = code; 495 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 496 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 497 498 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 499 rt = ip_route_output_key_hash(net, fl4, skb_in); 500 if (IS_ERR(rt)) 501 return rt; 502 503 /* No need to clone since we're just using its address. */ 504 rt2 = rt; 505 506 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 507 flowi4_to_flowi(fl4), NULL, 0); 508 if (!IS_ERR(rt)) { 509 if (rt != rt2) 510 return rt; 511 } else if (PTR_ERR(rt) == -EPERM) { 512 rt = NULL; 513 } else 514 return rt; 515 516 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 517 if (err) 518 goto relookup_failed; 519 520 if (inet_addr_type_dev_table(net, route_lookup_dev, 521 fl4_dec.saddr) == RTN_LOCAL) { 522 rt2 = __ip_route_output_key(net, &fl4_dec); 523 if (IS_ERR(rt2)) 524 err = PTR_ERR(rt2); 525 } else { 526 struct flowi4 fl4_2 = {}; 527 unsigned long orefdst; 528 529 fl4_2.daddr = fl4_dec.saddr; 530 rt2 = ip_route_output_key(net, &fl4_2); 531 if (IS_ERR(rt2)) { 532 err = PTR_ERR(rt2); 533 goto relookup_failed; 534 } 535 /* Ugh! */ 536 orefdst = skb_in->_skb_refdst; /* save old refdst */ 537 skb_dst_set(skb_in, NULL); 538 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 539 RT_TOS(tos), rt2->dst.dev); 540 541 dst_release(&rt2->dst); 542 rt2 = skb_rtable(skb_in); 543 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 544 } 545 546 if (err) 547 goto relookup_failed; 548 549 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 550 flowi4_to_flowi(&fl4_dec), NULL, 551 XFRM_LOOKUP_ICMP); 552 if (!IS_ERR(rt2)) { 553 dst_release(&rt->dst); 554 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 555 rt = rt2; 556 } else if (PTR_ERR(rt2) == -EPERM) { 557 if (rt) 558 dst_release(&rt->dst); 559 return rt2; 560 } else { 561 err = PTR_ERR(rt2); 562 goto relookup_failed; 563 } 564 return rt; 565 566 relookup_failed: 567 if (rt) 568 return rt; 569 return ERR_PTR(err); 570 } 571 572 /* 573 * Send an ICMP message in response to a situation 574 * 575 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 576 * MAY send more (we do). 577 * MUST NOT change this header information. 578 * MUST NOT reply to a multicast/broadcast IP address. 579 * MUST NOT reply to a multicast/broadcast MAC address. 580 * MUST reply to only the first fragment. 581 */ 582 583 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 584 const struct ip_options *opt) 585 { 586 struct iphdr *iph; 587 int room; 588 struct icmp_bxm icmp_param; 589 struct rtable *rt = skb_rtable(skb_in); 590 struct ipcm_cookie ipc; 591 struct flowi4 fl4; 592 __be32 saddr; 593 u8 tos; 594 u32 mark; 595 struct net *net; 596 struct sock *sk; 597 598 if (!rt) 599 goto out; 600 601 if (rt->dst.dev) 602 net = dev_net(rt->dst.dev); 603 else if (skb_in->dev) 604 net = dev_net(skb_in->dev); 605 else 606 goto out; 607 608 /* 609 * Find the original header. It is expected to be valid, of course. 610 * Check this, icmp_send is called from the most obscure devices 611 * sometimes. 612 */ 613 iph = ip_hdr(skb_in); 614 615 if ((u8 *)iph < skb_in->head || 616 (skb_network_header(skb_in) + sizeof(*iph)) > 617 skb_tail_pointer(skb_in)) 618 goto out; 619 620 /* 621 * No replies to physical multicast/broadcast 622 */ 623 if (skb_in->pkt_type != PACKET_HOST) 624 goto out; 625 626 /* 627 * Now check at the protocol level 628 */ 629 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 630 goto out; 631 632 /* 633 * Only reply to fragment 0. We byte re-order the constant 634 * mask for efficiency. 635 */ 636 if (iph->frag_off & htons(IP_OFFSET)) 637 goto out; 638 639 /* 640 * If we send an ICMP error to an ICMP error a mess would result.. 641 */ 642 if (icmp_pointers[type].error) { 643 /* 644 * We are an error, check if we are replying to an 645 * ICMP error 646 */ 647 if (iph->protocol == IPPROTO_ICMP) { 648 u8 _inner_type, *itp; 649 650 itp = skb_header_pointer(skb_in, 651 skb_network_header(skb_in) + 652 (iph->ihl << 2) + 653 offsetof(struct icmphdr, 654 type) - 655 skb_in->data, 656 sizeof(_inner_type), 657 &_inner_type); 658 if (!itp) 659 goto out; 660 661 /* 662 * Assume any unknown ICMP type is an error. This 663 * isn't specified by the RFC, but think about it.. 664 */ 665 if (*itp > NR_ICMP_TYPES || 666 icmp_pointers[*itp].error) 667 goto out; 668 } 669 } 670 671 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 672 local_bh_disable(); 673 674 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 675 * incoming dev is loopback. If outgoing dev change to not be 676 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 677 */ 678 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 679 !icmpv4_global_allow(net, type, code)) 680 goto out_bh_enable; 681 682 sk = icmp_xmit_lock(net); 683 if (!sk) 684 goto out_bh_enable; 685 686 /* 687 * Construct source address and options. 688 */ 689 690 saddr = iph->daddr; 691 if (!(rt->rt_flags & RTCF_LOCAL)) { 692 struct net_device *dev = NULL; 693 694 rcu_read_lock(); 695 if (rt_is_input_route(rt) && 696 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 697 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 698 699 if (dev) 700 saddr = inet_select_addr(dev, iph->saddr, 701 RT_SCOPE_LINK); 702 else 703 saddr = 0; 704 rcu_read_unlock(); 705 } 706 707 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 708 IPTOS_PREC_INTERNETCONTROL) : 709 iph->tos; 710 mark = IP4_REPLY_MARK(net, skb_in->mark); 711 712 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 713 goto out_unlock; 714 715 716 /* 717 * Prepare data for ICMP header. 718 */ 719 720 icmp_param.data.icmph.type = type; 721 icmp_param.data.icmph.code = code; 722 icmp_param.data.icmph.un.gateway = info; 723 icmp_param.data.icmph.checksum = 0; 724 icmp_param.skb = skb_in; 725 icmp_param.offset = skb_network_offset(skb_in); 726 inet_sk(sk)->tos = tos; 727 ipcm_init(&ipc); 728 ipc.addr = iph->saddr; 729 ipc.opt = &icmp_param.replyopts.opt; 730 ipc.sockc.mark = mark; 731 732 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 733 type, code, &icmp_param); 734 if (IS_ERR(rt)) 735 goto out_unlock; 736 737 /* peer icmp_ratelimit */ 738 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 739 goto ende; 740 741 /* RFC says return as much as we can without exceeding 576 bytes. */ 742 743 room = dst_mtu(&rt->dst); 744 if (room > 576) 745 room = 576; 746 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 747 room -= sizeof(struct icmphdr); 748 749 icmp_param.data_len = skb_in->len - icmp_param.offset; 750 if (icmp_param.data_len > room) 751 icmp_param.data_len = room; 752 icmp_param.head_len = sizeof(struct icmphdr); 753 754 /* if we don't have a source address at this point, fall back to the 755 * dummy address instead of sending out a packet with a source address 756 * of 0.0.0.0 757 */ 758 if (!fl4.saddr) 759 fl4.saddr = htonl(INADDR_DUMMY); 760 761 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 762 ende: 763 ip_rt_put(rt); 764 out_unlock: 765 icmp_xmit_unlock(sk); 766 out_bh_enable: 767 local_bh_enable(); 768 out:; 769 } 770 EXPORT_SYMBOL(__icmp_send); 771 772 #if IS_ENABLED(CONFIG_NF_NAT) 773 #include <net/netfilter/nf_conntrack.h> 774 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 775 { 776 struct sk_buff *cloned_skb = NULL; 777 struct ip_options opts = { 0 }; 778 enum ip_conntrack_info ctinfo; 779 struct nf_conn *ct; 780 __be32 orig_ip; 781 782 ct = nf_ct_get(skb_in, &ctinfo); 783 if (!ct || !(ct->status & IPS_SRC_NAT)) { 784 __icmp_send(skb_in, type, code, info, &opts); 785 return; 786 } 787 788 if (skb_shared(skb_in)) 789 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 790 791 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 792 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 793 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 794 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 795 goto out; 796 797 orig_ip = ip_hdr(skb_in)->saddr; 798 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 799 __icmp_send(skb_in, type, code, info, &opts); 800 ip_hdr(skb_in)->saddr = orig_ip; 801 out: 802 consume_skb(cloned_skb); 803 } 804 EXPORT_SYMBOL(icmp_ndo_send); 805 #endif 806 807 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 808 { 809 const struct iphdr *iph = (const struct iphdr *)skb->data; 810 const struct net_protocol *ipprot; 811 int protocol = iph->protocol; 812 813 /* Checkin full IP header plus 8 bytes of protocol to 814 * avoid additional coding at protocol handlers. 815 */ 816 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 817 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 818 return; 819 } 820 821 raw_icmp_error(skb, protocol, info); 822 823 ipprot = rcu_dereference(inet_protos[protocol]); 824 if (ipprot && ipprot->err_handler) 825 ipprot->err_handler(skb, info); 826 } 827 828 static bool icmp_tag_validation(int proto) 829 { 830 bool ok; 831 832 rcu_read_lock(); 833 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 834 rcu_read_unlock(); 835 return ok; 836 } 837 838 /* 839 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 840 * ICMP_PARAMETERPROB. 841 */ 842 843 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 844 { 845 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 846 const struct iphdr *iph; 847 struct icmphdr *icmph; 848 struct net *net; 849 u32 info = 0; 850 851 net = dev_net(skb_dst(skb)->dev); 852 853 /* 854 * Incomplete header ? 855 * Only checks for the IP header, there should be an 856 * additional check for longer headers in upper levels. 857 */ 858 859 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 860 goto out_err; 861 862 icmph = icmp_hdr(skb); 863 iph = (const struct iphdr *)skb->data; 864 865 if (iph->ihl < 5) { /* Mangled header, drop. */ 866 reason = SKB_DROP_REASON_IP_INHDR; 867 goto out_err; 868 } 869 870 switch (icmph->type) { 871 case ICMP_DEST_UNREACH: 872 switch (icmph->code & 15) { 873 case ICMP_NET_UNREACH: 874 case ICMP_HOST_UNREACH: 875 case ICMP_PROT_UNREACH: 876 case ICMP_PORT_UNREACH: 877 break; 878 case ICMP_FRAG_NEEDED: 879 /* for documentation of the ip_no_pmtu_disc 880 * values please see 881 * Documentation/networking/ip-sysctl.rst 882 */ 883 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 884 default: 885 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 886 &iph->daddr); 887 break; 888 case 2: 889 goto out; 890 case 3: 891 if (!icmp_tag_validation(iph->protocol)) 892 goto out; 893 fallthrough; 894 case 0: 895 info = ntohs(icmph->un.frag.mtu); 896 } 897 break; 898 case ICMP_SR_FAILED: 899 net_dbg_ratelimited("%pI4: Source Route Failed\n", 900 &iph->daddr); 901 break; 902 default: 903 break; 904 } 905 if (icmph->code > NR_ICMP_UNREACH) 906 goto out; 907 break; 908 case ICMP_PARAMETERPROB: 909 info = ntohl(icmph->un.gateway) >> 24; 910 break; 911 case ICMP_TIME_EXCEEDED: 912 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 913 if (icmph->code == ICMP_EXC_FRAGTIME) 914 goto out; 915 break; 916 } 917 918 /* 919 * Throw it at our lower layers 920 * 921 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 922 * header. 923 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 924 * transport layer. 925 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 926 * transport layer. 927 */ 928 929 /* 930 * Check the other end isn't violating RFC 1122. Some routers send 931 * bogus responses to broadcast frames. If you see this message 932 * first check your netmask matches at both ends, if it does then 933 * get the other vendor to fix their kit. 934 */ 935 936 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 937 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 938 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 939 &ip_hdr(skb)->saddr, 940 icmph->type, icmph->code, 941 &iph->daddr, skb->dev->name); 942 goto out; 943 } 944 945 icmp_socket_deliver(skb, info); 946 947 out: 948 return reason; 949 out_err: 950 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 951 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 952 } 953 954 955 /* 956 * Handle ICMP_REDIRECT. 957 */ 958 959 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 960 { 961 if (skb->len < sizeof(struct iphdr)) { 962 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 963 return SKB_DROP_REASON_PKT_TOO_SMALL; 964 } 965 966 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 967 /* there aught to be a stat */ 968 return SKB_DROP_REASON_NOMEM; 969 } 970 971 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 972 return SKB_NOT_DROPPED_YET; 973 } 974 975 /* 976 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 977 * 978 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 979 * requests. 980 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 981 * included in the reply. 982 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 983 * echo requests, MUST have default=NOT. 984 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 985 * Extended Echo Functionality, MUST be disabled by default 986 * See also WRT handling of options once they are done and working. 987 */ 988 989 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 990 { 991 struct icmp_bxm icmp_param; 992 struct net *net; 993 994 net = dev_net(skb_dst(skb)->dev); 995 /* should there be an ICMP stat for ignored echos? */ 996 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 997 return SKB_NOT_DROPPED_YET; 998 999 icmp_param.data.icmph = *icmp_hdr(skb); 1000 icmp_param.skb = skb; 1001 icmp_param.offset = 0; 1002 icmp_param.data_len = skb->len; 1003 icmp_param.head_len = sizeof(struct icmphdr); 1004 1005 if (icmp_param.data.icmph.type == ICMP_ECHO) 1006 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1007 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1008 return SKB_NOT_DROPPED_YET; 1009 1010 icmp_reply(&icmp_param, skb); 1011 return SKB_NOT_DROPPED_YET; 1012 } 1013 1014 /* Helper for icmp_echo and icmpv6_echo_reply. 1015 * Searches for net_device that matches PROBE interface identifier 1016 * and builds PROBE reply message in icmphdr. 1017 * 1018 * Returns false if PROBE responses are disabled via sysctl 1019 */ 1020 1021 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1022 { 1023 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1024 struct icmp_ext_echo_iio *iio, _iio; 1025 struct net *net = dev_net(skb->dev); 1026 struct net_device *dev; 1027 char buff[IFNAMSIZ]; 1028 u16 ident_len; 1029 u8 status; 1030 1031 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1032 return false; 1033 1034 /* We currently only support probing interfaces on the proxy node 1035 * Check to ensure L-bit is set 1036 */ 1037 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1038 return false; 1039 /* Clear status bits in reply message */ 1040 icmphdr->un.echo.sequence &= htons(0xFF00); 1041 if (icmphdr->type == ICMP_EXT_ECHO) 1042 icmphdr->type = ICMP_EXT_ECHOREPLY; 1043 else 1044 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1045 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1046 /* Size of iio is class_type dependent. 1047 * Only check header here and assign length based on ctype in the switch statement 1048 */ 1049 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1050 if (!ext_hdr || !iio) 1051 goto send_mal_query; 1052 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1053 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1054 goto send_mal_query; 1055 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1056 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1057 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1058 if (!iio) 1059 goto send_mal_query; 1060 1061 status = 0; 1062 dev = NULL; 1063 switch (iio->extobj_hdr.class_type) { 1064 case ICMP_EXT_ECHO_CTYPE_NAME: 1065 if (ident_len >= IFNAMSIZ) 1066 goto send_mal_query; 1067 memset(buff, 0, sizeof(buff)); 1068 memcpy(buff, &iio->ident.name, ident_len); 1069 dev = dev_get_by_name(net, buff); 1070 break; 1071 case ICMP_EXT_ECHO_CTYPE_INDEX: 1072 if (ident_len != sizeof(iio->ident.ifindex)) 1073 goto send_mal_query; 1074 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1075 break; 1076 case ICMP_EXT_ECHO_CTYPE_ADDR: 1077 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1078 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1079 iio->ident.addr.ctype3_hdr.addrlen) 1080 goto send_mal_query; 1081 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1082 case ICMP_AFI_IP: 1083 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1084 goto send_mal_query; 1085 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1086 break; 1087 #if IS_ENABLED(CONFIG_IPV6) 1088 case ICMP_AFI_IP6: 1089 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1090 goto send_mal_query; 1091 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1092 dev_hold(dev); 1093 break; 1094 #endif 1095 default: 1096 goto send_mal_query; 1097 } 1098 break; 1099 default: 1100 goto send_mal_query; 1101 } 1102 if (!dev) { 1103 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1104 return true; 1105 } 1106 /* Fill bits in reply message */ 1107 if (dev->flags & IFF_UP) 1108 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1109 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1110 status |= ICMP_EXT_ECHOREPLY_IPV4; 1111 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1112 status |= ICMP_EXT_ECHOREPLY_IPV6; 1113 dev_put(dev); 1114 icmphdr->un.echo.sequence |= htons(status); 1115 return true; 1116 send_mal_query: 1117 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1118 return true; 1119 } 1120 EXPORT_SYMBOL_GPL(icmp_build_probe); 1121 1122 /* 1123 * Handle ICMP Timestamp requests. 1124 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1125 * SHOULD be in the kernel for minimum random latency. 1126 * MUST be accurate to a few minutes. 1127 * MUST be updated at least at 15Hz. 1128 */ 1129 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1130 { 1131 struct icmp_bxm icmp_param; 1132 /* 1133 * Too short. 1134 */ 1135 if (skb->len < 4) 1136 goto out_err; 1137 1138 /* 1139 * Fill in the current time as ms since midnight UT: 1140 */ 1141 icmp_param.data.times[1] = inet_current_timestamp(); 1142 icmp_param.data.times[2] = icmp_param.data.times[1]; 1143 1144 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1145 1146 icmp_param.data.icmph = *icmp_hdr(skb); 1147 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1148 icmp_param.data.icmph.code = 0; 1149 icmp_param.skb = skb; 1150 icmp_param.offset = 0; 1151 icmp_param.data_len = 0; 1152 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1153 icmp_reply(&icmp_param, skb); 1154 return SKB_NOT_DROPPED_YET; 1155 1156 out_err: 1157 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1158 return SKB_DROP_REASON_PKT_TOO_SMALL; 1159 } 1160 1161 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1162 { 1163 /* pretend it was a success */ 1164 return SKB_NOT_DROPPED_YET; 1165 } 1166 1167 /* 1168 * Deal with incoming ICMP packets. 1169 */ 1170 int icmp_rcv(struct sk_buff *skb) 1171 { 1172 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1173 struct rtable *rt = skb_rtable(skb); 1174 struct net *net = dev_net(rt->dst.dev); 1175 struct icmphdr *icmph; 1176 1177 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1178 struct sec_path *sp = skb_sec_path(skb); 1179 int nh; 1180 1181 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1182 XFRM_STATE_ICMP)) { 1183 reason = SKB_DROP_REASON_XFRM_POLICY; 1184 goto drop; 1185 } 1186 1187 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1188 goto drop; 1189 1190 nh = skb_network_offset(skb); 1191 skb_set_network_header(skb, sizeof(*icmph)); 1192 1193 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1194 skb)) { 1195 reason = SKB_DROP_REASON_XFRM_POLICY; 1196 goto drop; 1197 } 1198 1199 skb_set_network_header(skb, nh); 1200 } 1201 1202 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1203 1204 if (skb_checksum_simple_validate(skb)) 1205 goto csum_error; 1206 1207 if (!pskb_pull(skb, sizeof(*icmph))) 1208 goto error; 1209 1210 icmph = icmp_hdr(skb); 1211 1212 ICMPMSGIN_INC_STATS(net, icmph->type); 1213 1214 /* Check for ICMP Extended Echo (PROBE) messages */ 1215 if (icmph->type == ICMP_EXT_ECHO) { 1216 /* We can't use icmp_pointers[].handler() because it is an array of 1217 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1218 */ 1219 reason = icmp_echo(skb); 1220 goto reason_check; 1221 } 1222 1223 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1224 reason = ping_rcv(skb); 1225 goto reason_check; 1226 } 1227 1228 /* 1229 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1230 * 1231 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1232 * discarded. 1233 */ 1234 if (icmph->type > NR_ICMP_TYPES) { 1235 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1236 goto error; 1237 } 1238 1239 /* 1240 * Parse the ICMP message 1241 */ 1242 1243 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1244 /* 1245 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1246 * silently ignored (we let user decide with a sysctl). 1247 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1248 * discarded if to broadcast/multicast. 1249 */ 1250 if ((icmph->type == ICMP_ECHO || 1251 icmph->type == ICMP_TIMESTAMP) && 1252 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1253 reason = SKB_DROP_REASON_INVALID_PROTO; 1254 goto error; 1255 } 1256 if (icmph->type != ICMP_ECHO && 1257 icmph->type != ICMP_TIMESTAMP && 1258 icmph->type != ICMP_ADDRESS && 1259 icmph->type != ICMP_ADDRESSREPLY) { 1260 reason = SKB_DROP_REASON_INVALID_PROTO; 1261 goto error; 1262 } 1263 } 1264 1265 reason = icmp_pointers[icmph->type].handler(skb); 1266 reason_check: 1267 if (!reason) { 1268 consume_skb(skb); 1269 return NET_RX_SUCCESS; 1270 } 1271 1272 drop: 1273 kfree_skb_reason(skb, reason); 1274 return NET_RX_DROP; 1275 csum_error: 1276 reason = SKB_DROP_REASON_ICMP_CSUM; 1277 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1278 error: 1279 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1280 goto drop; 1281 } 1282 1283 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1284 { 1285 struct icmp_extobj_hdr *objh, _objh; 1286 struct icmp_ext_hdr *exth, _exth; 1287 u16 olen; 1288 1289 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1290 if (!exth) 1291 return false; 1292 if (exth->version != 2) 1293 return true; 1294 1295 if (exth->checksum && 1296 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1297 return false; 1298 1299 off += sizeof(_exth); 1300 while (off < skb->len) { 1301 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1302 if (!objh) 1303 return false; 1304 1305 olen = ntohs(objh->length); 1306 if (olen < sizeof(_objh)) 1307 return false; 1308 1309 off += olen; 1310 if (off > skb->len) 1311 return false; 1312 } 1313 1314 return true; 1315 } 1316 1317 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1318 struct sock_ee_data_rfc4884 *out, 1319 int thlen, int off) 1320 { 1321 int hlen; 1322 1323 /* original datagram headers: end of icmph to payload (skb->data) */ 1324 hlen = -skb_transport_offset(skb) - thlen; 1325 1326 /* per rfc 4884: minimal datagram length of 128 bytes */ 1327 if (off < 128 || off < hlen) 1328 return; 1329 1330 /* kernel has stripped headers: return payload offset in bytes */ 1331 off -= hlen; 1332 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1333 return; 1334 1335 out->len = off; 1336 1337 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1338 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1339 } 1340 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1341 1342 int icmp_err(struct sk_buff *skb, u32 info) 1343 { 1344 struct iphdr *iph = (struct iphdr *)skb->data; 1345 int offset = iph->ihl<<2; 1346 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1347 int type = icmp_hdr(skb)->type; 1348 int code = icmp_hdr(skb)->code; 1349 struct net *net = dev_net(skb->dev); 1350 1351 /* 1352 * Use ping_err to handle all icmp errors except those 1353 * triggered by ICMP_ECHOREPLY which sent from kernel. 1354 */ 1355 if (icmph->type != ICMP_ECHOREPLY) { 1356 ping_err(skb, offset, info); 1357 return 0; 1358 } 1359 1360 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1361 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1362 else if (type == ICMP_REDIRECT) 1363 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1364 1365 return 0; 1366 } 1367 1368 /* 1369 * This table is the definition of how we handle ICMP. 1370 */ 1371 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1372 [ICMP_ECHOREPLY] = { 1373 .handler = ping_rcv, 1374 }, 1375 [1] = { 1376 .handler = icmp_discard, 1377 .error = 1, 1378 }, 1379 [2] = { 1380 .handler = icmp_discard, 1381 .error = 1, 1382 }, 1383 [ICMP_DEST_UNREACH] = { 1384 .handler = icmp_unreach, 1385 .error = 1, 1386 }, 1387 [ICMP_SOURCE_QUENCH] = { 1388 .handler = icmp_unreach, 1389 .error = 1, 1390 }, 1391 [ICMP_REDIRECT] = { 1392 .handler = icmp_redirect, 1393 .error = 1, 1394 }, 1395 [6] = { 1396 .handler = icmp_discard, 1397 .error = 1, 1398 }, 1399 [7] = { 1400 .handler = icmp_discard, 1401 .error = 1, 1402 }, 1403 [ICMP_ECHO] = { 1404 .handler = icmp_echo, 1405 }, 1406 [9] = { 1407 .handler = icmp_discard, 1408 .error = 1, 1409 }, 1410 [10] = { 1411 .handler = icmp_discard, 1412 .error = 1, 1413 }, 1414 [ICMP_TIME_EXCEEDED] = { 1415 .handler = icmp_unreach, 1416 .error = 1, 1417 }, 1418 [ICMP_PARAMETERPROB] = { 1419 .handler = icmp_unreach, 1420 .error = 1, 1421 }, 1422 [ICMP_TIMESTAMP] = { 1423 .handler = icmp_timestamp, 1424 }, 1425 [ICMP_TIMESTAMPREPLY] = { 1426 .handler = icmp_discard, 1427 }, 1428 [ICMP_INFO_REQUEST] = { 1429 .handler = icmp_discard, 1430 }, 1431 [ICMP_INFO_REPLY] = { 1432 .handler = icmp_discard, 1433 }, 1434 [ICMP_ADDRESS] = { 1435 .handler = icmp_discard, 1436 }, 1437 [ICMP_ADDRESSREPLY] = { 1438 .handler = icmp_discard, 1439 }, 1440 }; 1441 1442 static int __net_init icmp_sk_init(struct net *net) 1443 { 1444 /* Control parameters for ECHO replies. */ 1445 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1446 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1447 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1448 1449 /* Control parameter - ignore bogus broadcast responses? */ 1450 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1451 1452 /* 1453 * Configurable global rate limit. 1454 * 1455 * ratelimit defines tokens/packet consumed for dst->rate_token 1456 * bucket ratemask defines which icmp types are ratelimited by 1457 * setting it's bit position. 1458 * 1459 * default: 1460 * dest unreachable (3), source quench (4), 1461 * time exceeded (11), parameter problem (12) 1462 */ 1463 1464 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1465 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1466 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1467 1468 return 0; 1469 } 1470 1471 static struct pernet_operations __net_initdata icmp_sk_ops = { 1472 .init = icmp_sk_init, 1473 }; 1474 1475 int __init icmp_init(void) 1476 { 1477 int err, i; 1478 1479 for_each_possible_cpu(i) { 1480 struct sock *sk; 1481 1482 err = inet_ctl_sock_create(&sk, PF_INET, 1483 SOCK_RAW, IPPROTO_ICMP, &init_net); 1484 if (err < 0) 1485 return err; 1486 1487 per_cpu(ipv4_icmp_sk, i) = sk; 1488 1489 /* Enough space for 2 64K ICMP packets, including 1490 * sk_buff/skb_shared_info struct overhead. 1491 */ 1492 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1493 1494 /* 1495 * Speedup sock_wfree() 1496 */ 1497 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1498 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1499 } 1500 return register_pernet_subsys(&icmp_sk_ops); 1501 } 1502