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 #define CREATE_TRACE_POINTS 97 #include <trace/events/icmp.h> 98 99 /* 100 * Build xmit assembly blocks 101 */ 102 103 struct icmp_bxm { 104 struct sk_buff *skb; 105 int offset; 106 int data_len; 107 108 struct { 109 struct icmphdr icmph; 110 __be32 times[3]; 111 } data; 112 int head_len; 113 struct ip_options_data replyopts; 114 }; 115 116 /* An array of errno for error messages from dest unreach. */ 117 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 118 119 const struct icmp_err icmp_err_convert[] = { 120 { 121 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 122 .fatal = 0, 123 }, 124 { 125 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 126 .fatal = 0, 127 }, 128 { 129 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 130 .fatal = 1, 131 }, 132 { 133 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 134 .fatal = 1, 135 }, 136 { 137 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 138 .fatal = 0, 139 }, 140 { 141 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 142 .fatal = 0, 143 }, 144 { 145 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 146 .fatal = 1, 147 }, 148 { 149 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 150 .fatal = 1, 151 }, 152 { 153 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 154 .fatal = 1, 155 }, 156 { 157 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 158 .fatal = 1, 159 }, 160 { 161 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 162 .fatal = 1, 163 }, 164 { 165 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 166 .fatal = 0, 167 }, 168 { 169 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 170 .fatal = 0, 171 }, 172 { 173 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 174 .fatal = 1, 175 }, 176 { 177 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 178 .fatal = 1, 179 }, 180 { 181 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 182 .fatal = 1, 183 }, 184 }; 185 EXPORT_SYMBOL(icmp_err_convert); 186 187 /* 188 * ICMP control array. This specifies what to do with each ICMP. 189 */ 190 191 struct icmp_control { 192 enum skb_drop_reason (*handler)(struct sk_buff *skb); 193 short error; /* This ICMP is classed as an error message */ 194 }; 195 196 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 197 198 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 199 200 /* Called with BH disabled */ 201 static inline struct sock *icmp_xmit_lock(struct net *net) 202 { 203 struct sock *sk; 204 205 sk = this_cpu_read(ipv4_icmp_sk); 206 207 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 208 /* This can happen if the output path signals a 209 * dst_link_failure() for an outgoing ICMP packet. 210 */ 211 return NULL; 212 } 213 sock_net_set(sk, net); 214 return sk; 215 } 216 217 static inline void icmp_xmit_unlock(struct sock *sk) 218 { 219 sock_net_set(sk, &init_net); 220 spin_unlock(&sk->sk_lock.slock); 221 } 222 223 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 224 int sysctl_icmp_msgs_burst __read_mostly = 50; 225 226 static struct { 227 spinlock_t lock; 228 u32 credit; 229 u32 stamp; 230 } icmp_global = { 231 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 232 }; 233 234 /** 235 * icmp_global_allow - Are we allowed to send one more ICMP message ? 236 * 237 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 238 * Returns false if we reached the limit and can not send another packet. 239 * Note: called with BH disabled 240 */ 241 bool icmp_global_allow(void) 242 { 243 u32 credit, delta, incr = 0, now = (u32)jiffies; 244 bool rc = false; 245 246 /* Check if token bucket is empty and cannot be refilled 247 * without taking the spinlock. The READ_ONCE() are paired 248 * with the following WRITE_ONCE() in this same function. 249 */ 250 if (!READ_ONCE(icmp_global.credit)) { 251 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 252 if (delta < HZ / 50) 253 return false; 254 } 255 256 spin_lock(&icmp_global.lock); 257 delta = min_t(u32, now - icmp_global.stamp, HZ); 258 if (delta >= HZ / 50) { 259 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ; 260 if (incr) 261 WRITE_ONCE(icmp_global.stamp, now); 262 } 263 credit = min_t(u32, icmp_global.credit + incr, 264 READ_ONCE(sysctl_icmp_msgs_burst)); 265 if (credit) { 266 /* We want to use a credit of one in average, but need to randomize 267 * it for security reasons. 268 */ 269 credit = max_t(int, credit - get_random_u32_below(3), 0); 270 rc = true; 271 } 272 WRITE_ONCE(icmp_global.credit, credit); 273 spin_unlock(&icmp_global.lock); 274 return rc; 275 } 276 EXPORT_SYMBOL(icmp_global_allow); 277 278 static bool icmpv4_mask_allow(struct net *net, int type, int code) 279 { 280 if (type > NR_ICMP_TYPES) 281 return true; 282 283 /* Don't limit PMTU discovery. */ 284 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 285 return true; 286 287 /* Limit if icmp type is enabled in ratemask. */ 288 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 289 return true; 290 291 return false; 292 } 293 294 static bool icmpv4_global_allow(struct net *net, int type, int code) 295 { 296 if (icmpv4_mask_allow(net, type, code)) 297 return true; 298 299 if (icmp_global_allow()) 300 return true; 301 302 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 303 return false; 304 } 305 306 /* 307 * Send an ICMP frame. 308 */ 309 310 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 311 struct flowi4 *fl4, int type, int code) 312 { 313 struct dst_entry *dst = &rt->dst; 314 struct inet_peer *peer; 315 bool rc = true; 316 int vif; 317 318 if (icmpv4_mask_allow(net, type, code)) 319 goto out; 320 321 /* No rate limit on loopback */ 322 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 323 goto out; 324 325 vif = l3mdev_master_ifindex(dst->dev); 326 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 327 rc = inet_peer_xrlim_allow(peer, 328 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 329 if (peer) 330 inet_putpeer(peer); 331 out: 332 if (!rc) 333 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 334 return rc; 335 } 336 337 /* 338 * Maintain the counters used in the SNMP statistics for outgoing ICMP 339 */ 340 void icmp_out_count(struct net *net, unsigned char type) 341 { 342 ICMPMSGOUT_INC_STATS(net, type); 343 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 344 } 345 346 /* 347 * Checksum each fragment, and on the first include the headers and final 348 * checksum. 349 */ 350 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 351 struct sk_buff *skb) 352 { 353 struct icmp_bxm *icmp_param = from; 354 __wsum csum; 355 356 csum = skb_copy_and_csum_bits(icmp_param->skb, 357 icmp_param->offset + offset, 358 to, len); 359 360 skb->csum = csum_block_add(skb->csum, csum, odd); 361 if (icmp_pointers[icmp_param->data.icmph.type].error) 362 nf_ct_attach(skb, icmp_param->skb); 363 return 0; 364 } 365 366 static void icmp_push_reply(struct sock *sk, 367 struct icmp_bxm *icmp_param, 368 struct flowi4 *fl4, 369 struct ipcm_cookie *ipc, struct rtable **rt) 370 { 371 struct sk_buff *skb; 372 373 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 374 icmp_param->data_len+icmp_param->head_len, 375 icmp_param->head_len, 376 ipc, rt, MSG_DONTWAIT) < 0) { 377 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 378 ip_flush_pending_frames(sk); 379 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 380 struct icmphdr *icmph = icmp_hdr(skb); 381 __wsum csum; 382 struct sk_buff *skb1; 383 384 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 385 (char *)icmph, 386 icmp_param->head_len); 387 skb_queue_walk(&sk->sk_write_queue, skb1) { 388 csum = csum_add(csum, skb1->csum); 389 } 390 icmph->checksum = csum_fold(csum); 391 skb->ip_summed = CHECKSUM_NONE; 392 ip_push_pending_frames(sk, fl4); 393 } 394 } 395 396 /* 397 * Driving logic for building and sending ICMP messages. 398 */ 399 400 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 401 { 402 struct ipcm_cookie ipc; 403 struct rtable *rt = skb_rtable(skb); 404 struct net *net = dev_net(rt->dst.dev); 405 struct flowi4 fl4; 406 struct sock *sk; 407 struct inet_sock *inet; 408 __be32 daddr, saddr; 409 u32 mark = IP4_REPLY_MARK(net, skb->mark); 410 int type = icmp_param->data.icmph.type; 411 int code = icmp_param->data.icmph.code; 412 413 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 414 return; 415 416 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 417 local_bh_disable(); 418 419 /* global icmp_msgs_per_sec */ 420 if (!icmpv4_global_allow(net, type, code)) 421 goto out_bh_enable; 422 423 sk = icmp_xmit_lock(net); 424 if (!sk) 425 goto out_bh_enable; 426 inet = inet_sk(sk); 427 428 icmp_param->data.icmph.checksum = 0; 429 430 ipcm_init(&ipc); 431 inet->tos = ip_hdr(skb)->tos; 432 ipc.sockc.mark = mark; 433 daddr = ipc.addr = ip_hdr(skb)->saddr; 434 saddr = fib_compute_spec_dst(skb); 435 436 if (icmp_param->replyopts.opt.opt.optlen) { 437 ipc.opt = &icmp_param->replyopts.opt; 438 if (ipc.opt->opt.srr) 439 daddr = icmp_param->replyopts.opt.opt.faddr; 440 } 441 memset(&fl4, 0, sizeof(fl4)); 442 fl4.daddr = daddr; 443 fl4.saddr = saddr; 444 fl4.flowi4_mark = mark; 445 fl4.flowi4_uid = sock_net_uid(net, NULL); 446 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 447 fl4.flowi4_proto = IPPROTO_ICMP; 448 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 449 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 450 rt = ip_route_output_key(net, &fl4); 451 if (IS_ERR(rt)) 452 goto out_unlock; 453 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 454 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 455 ip_rt_put(rt); 456 out_unlock: 457 icmp_xmit_unlock(sk); 458 out_bh_enable: 459 local_bh_enable(); 460 } 461 462 /* 463 * The device used for looking up which routing table to use for sending an ICMP 464 * error is preferably the source whenever it is set, which should ensure the 465 * icmp error can be sent to the source host, else lookup using the routing 466 * table of the destination device, else use the main routing table (index 0). 467 */ 468 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 469 { 470 struct net_device *route_lookup_dev = NULL; 471 472 if (skb->dev) 473 route_lookup_dev = skb->dev; 474 else if (skb_dst(skb)) 475 route_lookup_dev = skb_dst(skb)->dev; 476 return route_lookup_dev; 477 } 478 479 static struct rtable *icmp_route_lookup(struct net *net, 480 struct flowi4 *fl4, 481 struct sk_buff *skb_in, 482 const struct iphdr *iph, 483 __be32 saddr, u8 tos, u32 mark, 484 int type, int code, 485 struct icmp_bxm *param) 486 { 487 struct net_device *route_lookup_dev; 488 struct dst_entry *dst, *dst2; 489 struct rtable *rt, *rt2; 490 struct flowi4 fl4_dec; 491 int err; 492 493 memset(fl4, 0, sizeof(*fl4)); 494 fl4->daddr = (param->replyopts.opt.opt.srr ? 495 param->replyopts.opt.opt.faddr : iph->saddr); 496 fl4->saddr = saddr; 497 fl4->flowi4_mark = mark; 498 fl4->flowi4_uid = sock_net_uid(net, NULL); 499 fl4->flowi4_tos = RT_TOS(tos); 500 fl4->flowi4_proto = IPPROTO_ICMP; 501 fl4->fl4_icmp_type = type; 502 fl4->fl4_icmp_code = code; 503 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 504 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 505 506 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 507 rt = ip_route_output_key_hash(net, fl4, skb_in); 508 if (IS_ERR(rt)) 509 return rt; 510 511 /* No need to clone since we're just using its address. */ 512 rt2 = rt; 513 514 dst = xfrm_lookup(net, &rt->dst, 515 flowi4_to_flowi(fl4), NULL, 0); 516 rt = dst_rtable(dst); 517 if (!IS_ERR(dst)) { 518 if (rt != rt2) 519 return rt; 520 } else if (PTR_ERR(dst) == -EPERM) { 521 rt = NULL; 522 } else { 523 return rt; 524 } 525 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 526 if (err) 527 goto relookup_failed; 528 529 if (inet_addr_type_dev_table(net, route_lookup_dev, 530 fl4_dec.saddr) == RTN_LOCAL) { 531 rt2 = __ip_route_output_key(net, &fl4_dec); 532 if (IS_ERR(rt2)) 533 err = PTR_ERR(rt2); 534 } else { 535 struct flowi4 fl4_2 = {}; 536 unsigned long orefdst; 537 538 fl4_2.daddr = fl4_dec.saddr; 539 rt2 = ip_route_output_key(net, &fl4_2); 540 if (IS_ERR(rt2)) { 541 err = PTR_ERR(rt2); 542 goto relookup_failed; 543 } 544 /* Ugh! */ 545 orefdst = skb_in->_skb_refdst; /* save old refdst */ 546 skb_dst_set(skb_in, NULL); 547 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 548 RT_TOS(tos), rt2->dst.dev); 549 550 dst_release(&rt2->dst); 551 rt2 = skb_rtable(skb_in); 552 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 553 } 554 555 if (err) 556 goto relookup_failed; 557 558 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 559 XFRM_LOOKUP_ICMP); 560 rt2 = dst_rtable(dst2); 561 if (!IS_ERR(dst2)) { 562 dst_release(&rt->dst); 563 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 564 rt = rt2; 565 } else if (PTR_ERR(dst2) == -EPERM) { 566 if (rt) 567 dst_release(&rt->dst); 568 return rt2; 569 } else { 570 err = PTR_ERR(dst2); 571 goto relookup_failed; 572 } 573 return rt; 574 575 relookup_failed: 576 if (rt) 577 return rt; 578 return ERR_PTR(err); 579 } 580 581 /* 582 * Send an ICMP message in response to a situation 583 * 584 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 585 * MAY send more (we do). 586 * MUST NOT change this header information. 587 * MUST NOT reply to a multicast/broadcast IP address. 588 * MUST NOT reply to a multicast/broadcast MAC address. 589 * MUST reply to only the first fragment. 590 */ 591 592 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 593 const struct ip_options *opt) 594 { 595 struct iphdr *iph; 596 int room; 597 struct icmp_bxm icmp_param; 598 struct rtable *rt = skb_rtable(skb_in); 599 struct ipcm_cookie ipc; 600 struct flowi4 fl4; 601 __be32 saddr; 602 u8 tos; 603 u32 mark; 604 struct net *net; 605 struct sock *sk; 606 607 if (!rt) 608 goto out; 609 610 if (rt->dst.dev) 611 net = dev_net(rt->dst.dev); 612 else if (skb_in->dev) 613 net = dev_net(skb_in->dev); 614 else 615 goto out; 616 617 /* 618 * Find the original header. It is expected to be valid, of course. 619 * Check this, icmp_send is called from the most obscure devices 620 * sometimes. 621 */ 622 iph = ip_hdr(skb_in); 623 624 if ((u8 *)iph < skb_in->head || 625 (skb_network_header(skb_in) + sizeof(*iph)) > 626 skb_tail_pointer(skb_in)) 627 goto out; 628 629 /* 630 * No replies to physical multicast/broadcast 631 */ 632 if (skb_in->pkt_type != PACKET_HOST) 633 goto out; 634 635 /* 636 * Now check at the protocol level 637 */ 638 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 639 goto out; 640 641 /* 642 * Only reply to fragment 0. We byte re-order the constant 643 * mask for efficiency. 644 */ 645 if (iph->frag_off & htons(IP_OFFSET)) 646 goto out; 647 648 /* 649 * If we send an ICMP error to an ICMP error a mess would result.. 650 */ 651 if (icmp_pointers[type].error) { 652 /* 653 * We are an error, check if we are replying to an 654 * ICMP error 655 */ 656 if (iph->protocol == IPPROTO_ICMP) { 657 u8 _inner_type, *itp; 658 659 itp = skb_header_pointer(skb_in, 660 skb_network_header(skb_in) + 661 (iph->ihl << 2) + 662 offsetof(struct icmphdr, 663 type) - 664 skb_in->data, 665 sizeof(_inner_type), 666 &_inner_type); 667 if (!itp) 668 goto out; 669 670 /* 671 * Assume any unknown ICMP type is an error. This 672 * isn't specified by the RFC, but think about it.. 673 */ 674 if (*itp > NR_ICMP_TYPES || 675 icmp_pointers[*itp].error) 676 goto out; 677 } 678 } 679 680 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 681 local_bh_disable(); 682 683 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 684 * incoming dev is loopback. If outgoing dev change to not be 685 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 686 */ 687 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 688 !icmpv4_global_allow(net, type, code)) 689 goto out_bh_enable; 690 691 sk = icmp_xmit_lock(net); 692 if (!sk) 693 goto out_bh_enable; 694 695 /* 696 * Construct source address and options. 697 */ 698 699 saddr = iph->daddr; 700 if (!(rt->rt_flags & RTCF_LOCAL)) { 701 struct net_device *dev = NULL; 702 703 rcu_read_lock(); 704 if (rt_is_input_route(rt) && 705 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 706 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 707 708 if (dev) 709 saddr = inet_select_addr(dev, iph->saddr, 710 RT_SCOPE_LINK); 711 else 712 saddr = 0; 713 rcu_read_unlock(); 714 } 715 716 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 717 IPTOS_PREC_INTERNETCONTROL) : 718 iph->tos; 719 mark = IP4_REPLY_MARK(net, skb_in->mark); 720 721 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 722 goto out_unlock; 723 724 725 /* 726 * Prepare data for ICMP header. 727 */ 728 729 icmp_param.data.icmph.type = type; 730 icmp_param.data.icmph.code = code; 731 icmp_param.data.icmph.un.gateway = info; 732 icmp_param.data.icmph.checksum = 0; 733 icmp_param.skb = skb_in; 734 icmp_param.offset = skb_network_offset(skb_in); 735 inet_sk(sk)->tos = tos; 736 ipcm_init(&ipc); 737 ipc.addr = iph->saddr; 738 ipc.opt = &icmp_param.replyopts.opt; 739 ipc.sockc.mark = mark; 740 741 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 742 type, code, &icmp_param); 743 if (IS_ERR(rt)) 744 goto out_unlock; 745 746 /* peer icmp_ratelimit */ 747 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 748 goto ende; 749 750 /* RFC says return as much as we can without exceeding 576 bytes. */ 751 752 room = dst_mtu(&rt->dst); 753 if (room > 576) 754 room = 576; 755 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 756 room -= sizeof(struct icmphdr); 757 /* Guard against tiny mtu. We need to include at least one 758 * IP network header for this message to make any sense. 759 */ 760 if (room <= (int)sizeof(struct iphdr)) 761 goto ende; 762 763 icmp_param.data_len = skb_in->len - icmp_param.offset; 764 if (icmp_param.data_len > room) 765 icmp_param.data_len = room; 766 icmp_param.head_len = sizeof(struct icmphdr); 767 768 /* if we don't have a source address at this point, fall back to the 769 * dummy address instead of sending out a packet with a source address 770 * of 0.0.0.0 771 */ 772 if (!fl4.saddr) 773 fl4.saddr = htonl(INADDR_DUMMY); 774 775 trace_icmp_send(skb_in, type, code); 776 777 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 778 ende: 779 ip_rt_put(rt); 780 out_unlock: 781 icmp_xmit_unlock(sk); 782 out_bh_enable: 783 local_bh_enable(); 784 out:; 785 } 786 EXPORT_SYMBOL(__icmp_send); 787 788 #if IS_ENABLED(CONFIG_NF_NAT) 789 #include <net/netfilter/nf_conntrack.h> 790 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 791 { 792 struct sk_buff *cloned_skb = NULL; 793 struct ip_options opts = { 0 }; 794 enum ip_conntrack_info ctinfo; 795 struct nf_conn *ct; 796 __be32 orig_ip; 797 798 ct = nf_ct_get(skb_in, &ctinfo); 799 if (!ct || !(ct->status & IPS_SRC_NAT)) { 800 __icmp_send(skb_in, type, code, info, &opts); 801 return; 802 } 803 804 if (skb_shared(skb_in)) 805 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 806 807 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 808 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 809 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 810 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 811 goto out; 812 813 orig_ip = ip_hdr(skb_in)->saddr; 814 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 815 __icmp_send(skb_in, type, code, info, &opts); 816 ip_hdr(skb_in)->saddr = orig_ip; 817 out: 818 consume_skb(cloned_skb); 819 } 820 EXPORT_SYMBOL(icmp_ndo_send); 821 #endif 822 823 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 824 { 825 const struct iphdr *iph = (const struct iphdr *)skb->data; 826 const struct net_protocol *ipprot; 827 int protocol = iph->protocol; 828 829 /* Checkin full IP header plus 8 bytes of protocol to 830 * avoid additional coding at protocol handlers. 831 */ 832 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 833 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 834 return; 835 } 836 837 raw_icmp_error(skb, protocol, info); 838 839 ipprot = rcu_dereference(inet_protos[protocol]); 840 if (ipprot && ipprot->err_handler) 841 ipprot->err_handler(skb, info); 842 } 843 844 static bool icmp_tag_validation(int proto) 845 { 846 bool ok; 847 848 rcu_read_lock(); 849 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 850 rcu_read_unlock(); 851 return ok; 852 } 853 854 /* 855 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 856 * ICMP_PARAMETERPROB. 857 */ 858 859 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 860 { 861 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 862 const struct iphdr *iph; 863 struct icmphdr *icmph; 864 struct net *net; 865 u32 info = 0; 866 867 net = dev_net(skb_dst(skb)->dev); 868 869 /* 870 * Incomplete header ? 871 * Only checks for the IP header, there should be an 872 * additional check for longer headers in upper levels. 873 */ 874 875 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 876 goto out_err; 877 878 icmph = icmp_hdr(skb); 879 iph = (const struct iphdr *)skb->data; 880 881 if (iph->ihl < 5) { /* Mangled header, drop. */ 882 reason = SKB_DROP_REASON_IP_INHDR; 883 goto out_err; 884 } 885 886 switch (icmph->type) { 887 case ICMP_DEST_UNREACH: 888 switch (icmph->code & 15) { 889 case ICMP_NET_UNREACH: 890 case ICMP_HOST_UNREACH: 891 case ICMP_PROT_UNREACH: 892 case ICMP_PORT_UNREACH: 893 break; 894 case ICMP_FRAG_NEEDED: 895 /* for documentation of the ip_no_pmtu_disc 896 * values please see 897 * Documentation/networking/ip-sysctl.rst 898 */ 899 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 900 default: 901 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 902 &iph->daddr); 903 break; 904 case 2: 905 goto out; 906 case 3: 907 if (!icmp_tag_validation(iph->protocol)) 908 goto out; 909 fallthrough; 910 case 0: 911 info = ntohs(icmph->un.frag.mtu); 912 } 913 break; 914 case ICMP_SR_FAILED: 915 net_dbg_ratelimited("%pI4: Source Route Failed\n", 916 &iph->daddr); 917 break; 918 default: 919 break; 920 } 921 if (icmph->code > NR_ICMP_UNREACH) 922 goto out; 923 break; 924 case ICMP_PARAMETERPROB: 925 info = ntohl(icmph->un.gateway) >> 24; 926 break; 927 case ICMP_TIME_EXCEEDED: 928 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 929 if (icmph->code == ICMP_EXC_FRAGTIME) 930 goto out; 931 break; 932 } 933 934 /* 935 * Throw it at our lower layers 936 * 937 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 938 * header. 939 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 940 * transport layer. 941 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 942 * transport layer. 943 */ 944 945 /* 946 * Check the other end isn't violating RFC 1122. Some routers send 947 * bogus responses to broadcast frames. If you see this message 948 * first check your netmask matches at both ends, if it does then 949 * get the other vendor to fix their kit. 950 */ 951 952 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 953 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 954 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 955 &ip_hdr(skb)->saddr, 956 icmph->type, icmph->code, 957 &iph->daddr, skb->dev->name); 958 goto out; 959 } 960 961 icmp_socket_deliver(skb, info); 962 963 out: 964 return reason; 965 out_err: 966 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 967 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 968 } 969 970 971 /* 972 * Handle ICMP_REDIRECT. 973 */ 974 975 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 976 { 977 if (skb->len < sizeof(struct iphdr)) { 978 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 979 return SKB_DROP_REASON_PKT_TOO_SMALL; 980 } 981 982 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 983 /* there aught to be a stat */ 984 return SKB_DROP_REASON_NOMEM; 985 } 986 987 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 988 return SKB_NOT_DROPPED_YET; 989 } 990 991 /* 992 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 993 * 994 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 995 * requests. 996 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 997 * included in the reply. 998 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 999 * echo requests, MUST have default=NOT. 1000 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1001 * Extended Echo Functionality, MUST be disabled by default 1002 * See also WRT handling of options once they are done and working. 1003 */ 1004 1005 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1006 { 1007 struct icmp_bxm icmp_param; 1008 struct net *net; 1009 1010 net = dev_net(skb_dst(skb)->dev); 1011 /* should there be an ICMP stat for ignored echos? */ 1012 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1013 return SKB_NOT_DROPPED_YET; 1014 1015 icmp_param.data.icmph = *icmp_hdr(skb); 1016 icmp_param.skb = skb; 1017 icmp_param.offset = 0; 1018 icmp_param.data_len = skb->len; 1019 icmp_param.head_len = sizeof(struct icmphdr); 1020 1021 if (icmp_param.data.icmph.type == ICMP_ECHO) 1022 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1023 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1024 return SKB_NOT_DROPPED_YET; 1025 1026 icmp_reply(&icmp_param, skb); 1027 return SKB_NOT_DROPPED_YET; 1028 } 1029 1030 /* Helper for icmp_echo and icmpv6_echo_reply. 1031 * Searches for net_device that matches PROBE interface identifier 1032 * and builds PROBE reply message in icmphdr. 1033 * 1034 * Returns false if PROBE responses are disabled via sysctl 1035 */ 1036 1037 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1038 { 1039 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1040 struct icmp_ext_echo_iio *iio, _iio; 1041 struct net *net = dev_net(skb->dev); 1042 struct inet6_dev *in6_dev; 1043 struct in_device *in_dev; 1044 struct net_device *dev; 1045 char buff[IFNAMSIZ]; 1046 u16 ident_len; 1047 u8 status; 1048 1049 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1050 return false; 1051 1052 /* We currently only support probing interfaces on the proxy node 1053 * Check to ensure L-bit is set 1054 */ 1055 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1056 return false; 1057 /* Clear status bits in reply message */ 1058 icmphdr->un.echo.sequence &= htons(0xFF00); 1059 if (icmphdr->type == ICMP_EXT_ECHO) 1060 icmphdr->type = ICMP_EXT_ECHOREPLY; 1061 else 1062 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1063 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1064 /* Size of iio is class_type dependent. 1065 * Only check header here and assign length based on ctype in the switch statement 1066 */ 1067 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1068 if (!ext_hdr || !iio) 1069 goto send_mal_query; 1070 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1071 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1072 goto send_mal_query; 1073 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1074 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1075 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1076 if (!iio) 1077 goto send_mal_query; 1078 1079 status = 0; 1080 dev = NULL; 1081 switch (iio->extobj_hdr.class_type) { 1082 case ICMP_EXT_ECHO_CTYPE_NAME: 1083 if (ident_len >= IFNAMSIZ) 1084 goto send_mal_query; 1085 memset(buff, 0, sizeof(buff)); 1086 memcpy(buff, &iio->ident.name, ident_len); 1087 dev = dev_get_by_name(net, buff); 1088 break; 1089 case ICMP_EXT_ECHO_CTYPE_INDEX: 1090 if (ident_len != sizeof(iio->ident.ifindex)) 1091 goto send_mal_query; 1092 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1093 break; 1094 case ICMP_EXT_ECHO_CTYPE_ADDR: 1095 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1096 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1097 iio->ident.addr.ctype3_hdr.addrlen) 1098 goto send_mal_query; 1099 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1100 case ICMP_AFI_IP: 1101 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1102 goto send_mal_query; 1103 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1104 break; 1105 #if IS_ENABLED(CONFIG_IPV6) 1106 case ICMP_AFI_IP6: 1107 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1108 goto send_mal_query; 1109 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1110 dev_hold(dev); 1111 break; 1112 #endif 1113 default: 1114 goto send_mal_query; 1115 } 1116 break; 1117 default: 1118 goto send_mal_query; 1119 } 1120 if (!dev) { 1121 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1122 return true; 1123 } 1124 /* Fill bits in reply message */ 1125 if (dev->flags & IFF_UP) 1126 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1127 1128 in_dev = __in_dev_get_rcu(dev); 1129 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1130 status |= ICMP_EXT_ECHOREPLY_IPV4; 1131 1132 in6_dev = __in6_dev_get(dev); 1133 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1134 status |= ICMP_EXT_ECHOREPLY_IPV6; 1135 1136 dev_put(dev); 1137 icmphdr->un.echo.sequence |= htons(status); 1138 return true; 1139 send_mal_query: 1140 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1141 return true; 1142 } 1143 EXPORT_SYMBOL_GPL(icmp_build_probe); 1144 1145 /* 1146 * Handle ICMP Timestamp requests. 1147 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1148 * SHOULD be in the kernel for minimum random latency. 1149 * MUST be accurate to a few minutes. 1150 * MUST be updated at least at 15Hz. 1151 */ 1152 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1153 { 1154 struct icmp_bxm icmp_param; 1155 /* 1156 * Too short. 1157 */ 1158 if (skb->len < 4) 1159 goto out_err; 1160 1161 /* 1162 * Fill in the current time as ms since midnight UT: 1163 */ 1164 icmp_param.data.times[1] = inet_current_timestamp(); 1165 icmp_param.data.times[2] = icmp_param.data.times[1]; 1166 1167 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1168 1169 icmp_param.data.icmph = *icmp_hdr(skb); 1170 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1171 icmp_param.data.icmph.code = 0; 1172 icmp_param.skb = skb; 1173 icmp_param.offset = 0; 1174 icmp_param.data_len = 0; 1175 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1176 icmp_reply(&icmp_param, skb); 1177 return SKB_NOT_DROPPED_YET; 1178 1179 out_err: 1180 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1181 return SKB_DROP_REASON_PKT_TOO_SMALL; 1182 } 1183 1184 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1185 { 1186 /* pretend it was a success */ 1187 return SKB_NOT_DROPPED_YET; 1188 } 1189 1190 /* 1191 * Deal with incoming ICMP packets. 1192 */ 1193 int icmp_rcv(struct sk_buff *skb) 1194 { 1195 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1196 struct rtable *rt = skb_rtable(skb); 1197 struct net *net = dev_net(rt->dst.dev); 1198 struct icmphdr *icmph; 1199 1200 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1201 struct sec_path *sp = skb_sec_path(skb); 1202 int nh; 1203 1204 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1205 XFRM_STATE_ICMP)) { 1206 reason = SKB_DROP_REASON_XFRM_POLICY; 1207 goto drop; 1208 } 1209 1210 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1211 goto drop; 1212 1213 nh = skb_network_offset(skb); 1214 skb_set_network_header(skb, sizeof(*icmph)); 1215 1216 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1217 skb)) { 1218 reason = SKB_DROP_REASON_XFRM_POLICY; 1219 goto drop; 1220 } 1221 1222 skb_set_network_header(skb, nh); 1223 } 1224 1225 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1226 1227 if (skb_checksum_simple_validate(skb)) 1228 goto csum_error; 1229 1230 if (!pskb_pull(skb, sizeof(*icmph))) 1231 goto error; 1232 1233 icmph = icmp_hdr(skb); 1234 1235 ICMPMSGIN_INC_STATS(net, icmph->type); 1236 1237 /* Check for ICMP Extended Echo (PROBE) messages */ 1238 if (icmph->type == ICMP_EXT_ECHO) { 1239 /* We can't use icmp_pointers[].handler() because it is an array of 1240 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1241 */ 1242 reason = icmp_echo(skb); 1243 goto reason_check; 1244 } 1245 1246 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1247 reason = ping_rcv(skb); 1248 goto reason_check; 1249 } 1250 1251 /* 1252 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1253 * 1254 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1255 * discarded. 1256 */ 1257 if (icmph->type > NR_ICMP_TYPES) { 1258 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1259 goto error; 1260 } 1261 1262 /* 1263 * Parse the ICMP message 1264 */ 1265 1266 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1267 /* 1268 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1269 * silently ignored (we let user decide with a sysctl). 1270 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1271 * discarded if to broadcast/multicast. 1272 */ 1273 if ((icmph->type == ICMP_ECHO || 1274 icmph->type == ICMP_TIMESTAMP) && 1275 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1276 reason = SKB_DROP_REASON_INVALID_PROTO; 1277 goto error; 1278 } 1279 if (icmph->type != ICMP_ECHO && 1280 icmph->type != ICMP_TIMESTAMP && 1281 icmph->type != ICMP_ADDRESS && 1282 icmph->type != ICMP_ADDRESSREPLY) { 1283 reason = SKB_DROP_REASON_INVALID_PROTO; 1284 goto error; 1285 } 1286 } 1287 1288 reason = icmp_pointers[icmph->type].handler(skb); 1289 reason_check: 1290 if (!reason) { 1291 consume_skb(skb); 1292 return NET_RX_SUCCESS; 1293 } 1294 1295 drop: 1296 kfree_skb_reason(skb, reason); 1297 return NET_RX_DROP; 1298 csum_error: 1299 reason = SKB_DROP_REASON_ICMP_CSUM; 1300 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1301 error: 1302 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1303 goto drop; 1304 } 1305 1306 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1307 { 1308 struct icmp_extobj_hdr *objh, _objh; 1309 struct icmp_ext_hdr *exth, _exth; 1310 u16 olen; 1311 1312 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1313 if (!exth) 1314 return false; 1315 if (exth->version != 2) 1316 return true; 1317 1318 if (exth->checksum && 1319 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1320 return false; 1321 1322 off += sizeof(_exth); 1323 while (off < skb->len) { 1324 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1325 if (!objh) 1326 return false; 1327 1328 olen = ntohs(objh->length); 1329 if (olen < sizeof(_objh)) 1330 return false; 1331 1332 off += olen; 1333 if (off > skb->len) 1334 return false; 1335 } 1336 1337 return true; 1338 } 1339 1340 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1341 struct sock_ee_data_rfc4884 *out, 1342 int thlen, int off) 1343 { 1344 int hlen; 1345 1346 /* original datagram headers: end of icmph to payload (skb->data) */ 1347 hlen = -skb_transport_offset(skb) - thlen; 1348 1349 /* per rfc 4884: minimal datagram length of 128 bytes */ 1350 if (off < 128 || off < hlen) 1351 return; 1352 1353 /* kernel has stripped headers: return payload offset in bytes */ 1354 off -= hlen; 1355 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1356 return; 1357 1358 out->len = off; 1359 1360 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1361 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1362 } 1363 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1364 1365 int icmp_err(struct sk_buff *skb, u32 info) 1366 { 1367 struct iphdr *iph = (struct iphdr *)skb->data; 1368 int offset = iph->ihl<<2; 1369 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1370 int type = icmp_hdr(skb)->type; 1371 int code = icmp_hdr(skb)->code; 1372 struct net *net = dev_net(skb->dev); 1373 1374 /* 1375 * Use ping_err to handle all icmp errors except those 1376 * triggered by ICMP_ECHOREPLY which sent from kernel. 1377 */ 1378 if (icmph->type != ICMP_ECHOREPLY) { 1379 ping_err(skb, offset, info); 1380 return 0; 1381 } 1382 1383 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1384 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1385 else if (type == ICMP_REDIRECT) 1386 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1387 1388 return 0; 1389 } 1390 1391 /* 1392 * This table is the definition of how we handle ICMP. 1393 */ 1394 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1395 [ICMP_ECHOREPLY] = { 1396 .handler = ping_rcv, 1397 }, 1398 [1] = { 1399 .handler = icmp_discard, 1400 .error = 1, 1401 }, 1402 [2] = { 1403 .handler = icmp_discard, 1404 .error = 1, 1405 }, 1406 [ICMP_DEST_UNREACH] = { 1407 .handler = icmp_unreach, 1408 .error = 1, 1409 }, 1410 [ICMP_SOURCE_QUENCH] = { 1411 .handler = icmp_unreach, 1412 .error = 1, 1413 }, 1414 [ICMP_REDIRECT] = { 1415 .handler = icmp_redirect, 1416 .error = 1, 1417 }, 1418 [6] = { 1419 .handler = icmp_discard, 1420 .error = 1, 1421 }, 1422 [7] = { 1423 .handler = icmp_discard, 1424 .error = 1, 1425 }, 1426 [ICMP_ECHO] = { 1427 .handler = icmp_echo, 1428 }, 1429 [9] = { 1430 .handler = icmp_discard, 1431 .error = 1, 1432 }, 1433 [10] = { 1434 .handler = icmp_discard, 1435 .error = 1, 1436 }, 1437 [ICMP_TIME_EXCEEDED] = { 1438 .handler = icmp_unreach, 1439 .error = 1, 1440 }, 1441 [ICMP_PARAMETERPROB] = { 1442 .handler = icmp_unreach, 1443 .error = 1, 1444 }, 1445 [ICMP_TIMESTAMP] = { 1446 .handler = icmp_timestamp, 1447 }, 1448 [ICMP_TIMESTAMPREPLY] = { 1449 .handler = icmp_discard, 1450 }, 1451 [ICMP_INFO_REQUEST] = { 1452 .handler = icmp_discard, 1453 }, 1454 [ICMP_INFO_REPLY] = { 1455 .handler = icmp_discard, 1456 }, 1457 [ICMP_ADDRESS] = { 1458 .handler = icmp_discard, 1459 }, 1460 [ICMP_ADDRESSREPLY] = { 1461 .handler = icmp_discard, 1462 }, 1463 }; 1464 1465 static int __net_init icmp_sk_init(struct net *net) 1466 { 1467 /* Control parameters for ECHO replies. */ 1468 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1469 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1470 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1471 1472 /* Control parameter - ignore bogus broadcast responses? */ 1473 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1474 1475 /* 1476 * Configurable global rate limit. 1477 * 1478 * ratelimit defines tokens/packet consumed for dst->rate_token 1479 * bucket ratemask defines which icmp types are ratelimited by 1480 * setting it's bit position. 1481 * 1482 * default: 1483 * dest unreachable (3), source quench (4), 1484 * time exceeded (11), parameter problem (12) 1485 */ 1486 1487 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1488 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1489 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1490 1491 return 0; 1492 } 1493 1494 static struct pernet_operations __net_initdata icmp_sk_ops = { 1495 .init = icmp_sk_init, 1496 }; 1497 1498 int __init icmp_init(void) 1499 { 1500 int err, i; 1501 1502 for_each_possible_cpu(i) { 1503 struct sock *sk; 1504 1505 err = inet_ctl_sock_create(&sk, PF_INET, 1506 SOCK_RAW, IPPROTO_ICMP, &init_net); 1507 if (err < 0) 1508 return err; 1509 1510 per_cpu(ipv4_icmp_sk, i) = sk; 1511 1512 /* Enough space for 2 64K ICMP packets, including 1513 * sk_buff/skb_shared_info struct overhead. 1514 */ 1515 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1516 1517 /* 1518 * Speedup sock_wfree() 1519 */ 1520 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1521 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1522 } 1523 return register_pernet_subsys(&icmp_sk_ops); 1524 } 1525