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 #include <net/inet_dscp.h> 97 #define CREATE_TRACE_POINTS 98 #include <trace/events/icmp.h> 99 100 /* 101 * Build xmit assembly blocks 102 */ 103 104 struct icmp_bxm { 105 struct sk_buff *skb; 106 int offset; 107 int data_len; 108 109 struct { 110 struct icmphdr icmph; 111 __be32 times[3]; 112 } data; 113 int head_len; 114 struct ip_options_data replyopts; 115 }; 116 117 /* An array of errno for error messages from dest unreach. */ 118 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 119 120 const struct icmp_err icmp_err_convert[] = { 121 { 122 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 123 .fatal = 0, 124 }, 125 { 126 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 127 .fatal = 0, 128 }, 129 { 130 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 131 .fatal = 1, 132 }, 133 { 134 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 135 .fatal = 1, 136 }, 137 { 138 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 139 .fatal = 0, 140 }, 141 { 142 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 143 .fatal = 0, 144 }, 145 { 146 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 147 .fatal = 1, 148 }, 149 { 150 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 151 .fatal = 1, 152 }, 153 { 154 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 155 .fatal = 1, 156 }, 157 { 158 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 159 .fatal = 1, 160 }, 161 { 162 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 163 .fatal = 1, 164 }, 165 { 166 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 167 .fatal = 0, 168 }, 169 { 170 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 171 .fatal = 0, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 175 .fatal = 1, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 179 .fatal = 1, 180 }, 181 { 182 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 183 .fatal = 1, 184 }, 185 }; 186 EXPORT_SYMBOL(icmp_err_convert); 187 188 /* 189 * ICMP control array. This specifies what to do with each ICMP. 190 */ 191 192 struct icmp_control { 193 enum skb_drop_reason (*handler)(struct sk_buff *skb); 194 short error; /* This ICMP is classed as an error message */ 195 }; 196 197 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 198 199 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 200 201 /* Called with BH disabled */ 202 static inline struct sock *icmp_xmit_lock(struct net *net) 203 { 204 struct sock *sk; 205 206 sk = this_cpu_read(ipv4_icmp_sk); 207 208 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 209 /* This can happen if the output path signals a 210 * dst_link_failure() for an outgoing ICMP packet. 211 */ 212 return NULL; 213 } 214 sock_net_set(sk, net); 215 return sk; 216 } 217 218 static inline void icmp_xmit_unlock(struct sock *sk) 219 { 220 sock_net_set(sk, &init_net); 221 spin_unlock(&sk->sk_lock.slock); 222 } 223 224 /** 225 * icmp_global_allow - Are we allowed to send one more ICMP message ? 226 * @net: network namespace 227 * 228 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 229 * Returns false if we reached the limit and can not send another packet. 230 * Works in tandem with icmp_global_consume(). 231 */ 232 bool icmp_global_allow(struct net *net) 233 { 234 u32 delta, now, oldstamp; 235 int incr, new, old; 236 237 /* Note: many cpus could find this condition true. 238 * Then later icmp_global_consume() could consume more credits, 239 * this is an acceptable race. 240 */ 241 if (atomic_read(&net->ipv4.icmp_global_credit) > 0) 242 return true; 243 244 now = jiffies; 245 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); 246 delta = min_t(u32, now - oldstamp, HZ); 247 if (delta < HZ / 50) 248 return false; 249 250 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ; 251 if (!incr) 252 return false; 253 254 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 255 old = atomic_read(&net->ipv4.icmp_global_credit); 256 do { 257 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 258 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 259 } 260 return true; 261 } 262 EXPORT_SYMBOL(icmp_global_allow); 263 264 void icmp_global_consume(struct net *net) 265 { 266 int credits = get_random_u32_below(3); 267 268 /* Note: this might make icmp_global.credit negative. */ 269 if (credits) 270 atomic_sub(credits, &net->ipv4.icmp_global_credit); 271 } 272 EXPORT_SYMBOL(icmp_global_consume); 273 274 static bool icmpv4_mask_allow(struct net *net, int type, int code) 275 { 276 if (type > NR_ICMP_TYPES) 277 return true; 278 279 /* Don't limit PMTU discovery. */ 280 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 281 return true; 282 283 /* Limit if icmp type is enabled in ratemask. */ 284 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 285 return true; 286 287 return false; 288 } 289 290 static bool icmpv4_global_allow(struct net *net, int type, int code, 291 bool *apply_ratelimit) 292 { 293 if (icmpv4_mask_allow(net, type, code)) 294 return true; 295 296 if (icmp_global_allow(net)) { 297 *apply_ratelimit = true; 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 bool apply_ratelimit) 311 { 312 struct dst_entry *dst = &rt->dst; 313 struct inet_peer *peer; 314 bool rc = true; 315 316 if (!apply_ratelimit) 317 return true; 318 319 /* No rate limit on loopback */ 320 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 321 goto out; 322 323 rcu_read_lock(); 324 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 325 l3mdev_master_ifindex_rcu(dst->dev)); 326 rc = inet_peer_xrlim_allow(peer, 327 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 328 rcu_read_unlock(); 329 out: 330 if (!rc) 331 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 332 else 333 icmp_global_consume(net); 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 rtable *rt = skb_rtable(skb); 403 struct net *net = dev_net_rcu(rt->dst.dev); 404 bool apply_ratelimit = false; 405 struct ipcm_cookie ipc; 406 struct flowi4 fl4; 407 struct sock *sk; 408 struct inet_sock *inet; 409 __be32 daddr, saddr; 410 u32 mark = IP4_REPLY_MARK(net, skb->mark); 411 int type = icmp_param->data.icmph.type; 412 int code = icmp_param->data.icmph.code; 413 414 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 415 return; 416 417 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 418 local_bh_disable(); 419 420 /* is global icmp_msgs_per_sec exhausted ? */ 421 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 422 goto out_bh_enable; 423 424 sk = icmp_xmit_lock(net); 425 if (!sk) 426 goto out_bh_enable; 427 inet = inet_sk(sk); 428 429 icmp_param->data.icmph.checksum = 0; 430 431 ipcm_init(&ipc); 432 inet->tos = ip_hdr(skb)->tos; 433 ipc.sockc.mark = mark; 434 daddr = ipc.addr = ip_hdr(skb)->saddr; 435 saddr = fib_compute_spec_dst(skb); 436 437 if (icmp_param->replyopts.opt.opt.optlen) { 438 ipc.opt = &icmp_param->replyopts.opt; 439 if (ipc.opt->opt.srr) 440 daddr = icmp_param->replyopts.opt.opt.faddr; 441 } 442 memset(&fl4, 0, sizeof(fl4)); 443 fl4.daddr = daddr; 444 fl4.saddr = saddr; 445 fl4.flowi4_mark = mark; 446 fl4.flowi4_uid = sock_net_uid(net, NULL); 447 fl4.flowi4_tos = inet_dscp_to_dsfield(ip4h_dscp(ip_hdr(skb))); 448 fl4.flowi4_proto = IPPROTO_ICMP; 449 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 450 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 451 rt = ip_route_output_key(net, &fl4); 452 if (IS_ERR(rt)) 453 goto out_unlock; 454 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 455 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 456 ip_rt_put(rt); 457 out_unlock: 458 icmp_xmit_unlock(sk); 459 out_bh_enable: 460 local_bh_enable(); 461 } 462 463 /* 464 * The device used for looking up which routing table to use for sending an ICMP 465 * error is preferably the source whenever it is set, which should ensure the 466 * icmp error can be sent to the source host, else lookup using the routing 467 * table of the destination device, else use the main routing table (index 0). 468 */ 469 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 470 { 471 struct net_device *route_lookup_dev = NULL; 472 473 if (skb->dev) 474 route_lookup_dev = skb->dev; 475 else if (skb_dst(skb)) 476 route_lookup_dev = skb_dst(skb)->dev; 477 return route_lookup_dev; 478 } 479 480 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 481 struct sk_buff *skb_in, 482 const struct iphdr *iph, __be32 saddr, 483 dscp_t dscp, u32 mark, int type, 484 int code, struct icmp_bxm *param) 485 { 486 struct net_device *route_lookup_dev; 487 struct dst_entry *dst, *dst2; 488 struct rtable *rt, *rt2; 489 struct flowi4 fl4_dec; 490 int err; 491 492 memset(fl4, 0, sizeof(*fl4)); 493 fl4->daddr = (param->replyopts.opt.opt.srr ? 494 param->replyopts.opt.opt.faddr : iph->saddr); 495 fl4->saddr = saddr; 496 fl4->flowi4_mark = mark; 497 fl4->flowi4_uid = sock_net_uid(net, NULL); 498 fl4->flowi4_tos = inet_dscp_to_dsfield(dscp); 499 fl4->flowi4_proto = IPPROTO_ICMP; 500 fl4->fl4_icmp_type = type; 501 fl4->fl4_icmp_code = code; 502 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 503 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 504 505 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 506 rt = ip_route_output_key_hash(net, fl4, skb_in); 507 if (IS_ERR(rt)) 508 return rt; 509 510 /* No need to clone since we're just using its address. */ 511 rt2 = rt; 512 513 dst = xfrm_lookup(net, &rt->dst, 514 flowi4_to_flowi(fl4), NULL, 0); 515 rt = dst_rtable(dst); 516 if (!IS_ERR(dst)) { 517 if (rt != rt2) 518 return rt; 519 if (inet_addr_type_dev_table(net, route_lookup_dev, 520 fl4->daddr) == RTN_LOCAL) 521 return rt; 522 } else if (PTR_ERR(dst) == -EPERM) { 523 rt = NULL; 524 } else { 525 return rt; 526 } 527 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 528 if (err) 529 goto relookup_failed; 530 531 if (inet_addr_type_dev_table(net, route_lookup_dev, 532 fl4_dec.saddr) == RTN_LOCAL) { 533 rt2 = __ip_route_output_key(net, &fl4_dec); 534 if (IS_ERR(rt2)) 535 err = PTR_ERR(rt2); 536 } else { 537 struct flowi4 fl4_2 = {}; 538 unsigned long orefdst; 539 540 fl4_2.daddr = fl4_dec.saddr; 541 rt2 = ip_route_output_key(net, &fl4_2); 542 if (IS_ERR(rt2)) { 543 err = PTR_ERR(rt2); 544 goto relookup_failed; 545 } 546 /* Ugh! */ 547 orefdst = skb_in->_skb_refdst; /* save old refdst */ 548 skb_dst_set(skb_in, NULL); 549 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 550 dscp, rt2->dst.dev) ? -EINVAL : 0; 551 552 dst_release(&rt2->dst); 553 rt2 = skb_rtable(skb_in); 554 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 555 } 556 557 if (err) 558 goto relookup_failed; 559 560 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 561 XFRM_LOOKUP_ICMP); 562 rt2 = dst_rtable(dst2); 563 if (!IS_ERR(dst2)) { 564 dst_release(&rt->dst); 565 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 566 rt = rt2; 567 } else if (PTR_ERR(dst2) == -EPERM) { 568 if (rt) 569 dst_release(&rt->dst); 570 return rt2; 571 } else { 572 err = PTR_ERR(dst2); 573 goto relookup_failed; 574 } 575 return rt; 576 577 relookup_failed: 578 if (rt) 579 return rt; 580 return ERR_PTR(err); 581 } 582 583 /* 584 * Send an ICMP message in response to a situation 585 * 586 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 587 * MAY send more (we do). 588 * MUST NOT change this header information. 589 * MUST NOT reply to a multicast/broadcast IP address. 590 * MUST NOT reply to a multicast/broadcast MAC address. 591 * MUST reply to only the first fragment. 592 */ 593 594 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 595 const struct ip_options *opt) 596 { 597 struct iphdr *iph; 598 int room; 599 struct icmp_bxm icmp_param; 600 struct rtable *rt = skb_rtable(skb_in); 601 bool apply_ratelimit = false; 602 struct ipcm_cookie ipc; 603 struct flowi4 fl4; 604 __be32 saddr; 605 u8 tos; 606 u32 mark; 607 struct net *net; 608 struct sock *sk; 609 610 if (!rt) 611 return; 612 613 rcu_read_lock(); 614 615 if (rt->dst.dev) 616 net = dev_net_rcu(rt->dst.dev); 617 else if (skb_in->dev) 618 net = dev_net_rcu(skb_in->dev); 619 else 620 goto out; 621 622 /* 623 * Find the original header. It is expected to be valid, of course. 624 * Check this, icmp_send is called from the most obscure devices 625 * sometimes. 626 */ 627 iph = ip_hdr(skb_in); 628 629 if ((u8 *)iph < skb_in->head || 630 (skb_network_header(skb_in) + sizeof(*iph)) > 631 skb_tail_pointer(skb_in)) 632 goto out; 633 634 /* 635 * No replies to physical multicast/broadcast 636 */ 637 if (skb_in->pkt_type != PACKET_HOST) 638 goto out; 639 640 /* 641 * Now check at the protocol level 642 */ 643 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 644 goto out; 645 646 /* 647 * Only reply to fragment 0. We byte re-order the constant 648 * mask for efficiency. 649 */ 650 if (iph->frag_off & htons(IP_OFFSET)) 651 goto out; 652 653 /* 654 * If we send an ICMP error to an ICMP error a mess would result.. 655 */ 656 if (icmp_pointers[type].error) { 657 /* 658 * We are an error, check if we are replying to an 659 * ICMP error 660 */ 661 if (iph->protocol == IPPROTO_ICMP) { 662 u8 _inner_type, *itp; 663 664 itp = skb_header_pointer(skb_in, 665 skb_network_header(skb_in) + 666 (iph->ihl << 2) + 667 offsetof(struct icmphdr, 668 type) - 669 skb_in->data, 670 sizeof(_inner_type), 671 &_inner_type); 672 if (!itp) 673 goto out; 674 675 /* 676 * Assume any unknown ICMP type is an error. This 677 * isn't specified by the RFC, but think about it.. 678 */ 679 if (*itp > NR_ICMP_TYPES || 680 icmp_pointers[*itp].error) 681 goto out; 682 } 683 } 684 685 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 686 local_bh_disable(); 687 688 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 689 * incoming dev is loopback. If outgoing dev change to not be 690 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 691 */ 692 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 693 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 694 goto out_bh_enable; 695 696 sk = icmp_xmit_lock(net); 697 if (!sk) 698 goto out_bh_enable; 699 700 /* 701 * Construct source address and options. 702 */ 703 704 saddr = iph->daddr; 705 if (!(rt->rt_flags & RTCF_LOCAL)) { 706 struct net_device *dev = NULL; 707 708 rcu_read_lock(); 709 if (rt_is_input_route(rt) && 710 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 711 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 712 713 if (dev) 714 saddr = inet_select_addr(dev, iph->saddr, 715 RT_SCOPE_LINK); 716 else 717 saddr = 0; 718 rcu_read_unlock(); 719 } 720 721 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 722 IPTOS_PREC_INTERNETCONTROL) : 723 iph->tos; 724 mark = IP4_REPLY_MARK(net, skb_in->mark); 725 726 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 727 goto out_unlock; 728 729 730 /* 731 * Prepare data for ICMP header. 732 */ 733 734 icmp_param.data.icmph.type = type; 735 icmp_param.data.icmph.code = code; 736 icmp_param.data.icmph.un.gateway = info; 737 icmp_param.data.icmph.checksum = 0; 738 icmp_param.skb = skb_in; 739 icmp_param.offset = skb_network_offset(skb_in); 740 inet_sk(sk)->tos = tos; 741 ipcm_init(&ipc); 742 ipc.addr = iph->saddr; 743 ipc.opt = &icmp_param.replyopts.opt; 744 ipc.sockc.mark = mark; 745 746 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 747 inet_dsfield_to_dscp(tos), mark, type, code, 748 &icmp_param); 749 if (IS_ERR(rt)) 750 goto out_unlock; 751 752 /* peer icmp_ratelimit */ 753 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 754 goto ende; 755 756 /* RFC says return as much as we can without exceeding 576 bytes. */ 757 758 room = dst_mtu(&rt->dst); 759 if (room > 576) 760 room = 576; 761 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 762 room -= sizeof(struct icmphdr); 763 /* Guard against tiny mtu. We need to include at least one 764 * IP network header for this message to make any sense. 765 */ 766 if (room <= (int)sizeof(struct iphdr)) 767 goto ende; 768 769 icmp_param.data_len = skb_in->len - icmp_param.offset; 770 if (icmp_param.data_len > room) 771 icmp_param.data_len = room; 772 icmp_param.head_len = sizeof(struct icmphdr); 773 774 /* if we don't have a source address at this point, fall back to the 775 * dummy address instead of sending out a packet with a source address 776 * of 0.0.0.0 777 */ 778 if (!fl4.saddr) 779 fl4.saddr = htonl(INADDR_DUMMY); 780 781 trace_icmp_send(skb_in, type, code); 782 783 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 784 ende: 785 ip_rt_put(rt); 786 out_unlock: 787 icmp_xmit_unlock(sk); 788 out_bh_enable: 789 local_bh_enable(); 790 out: 791 rcu_read_unlock(); 792 } 793 EXPORT_SYMBOL(__icmp_send); 794 795 #if IS_ENABLED(CONFIG_NF_NAT) 796 #include <net/netfilter/nf_conntrack.h> 797 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 798 { 799 struct sk_buff *cloned_skb = NULL; 800 struct ip_options opts = { 0 }; 801 enum ip_conntrack_info ctinfo; 802 struct nf_conn *ct; 803 __be32 orig_ip; 804 805 ct = nf_ct_get(skb_in, &ctinfo); 806 if (!ct || !(ct->status & IPS_SRC_NAT)) { 807 __icmp_send(skb_in, type, code, info, &opts); 808 return; 809 } 810 811 if (skb_shared(skb_in)) 812 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 813 814 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 815 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 816 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 817 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 818 goto out; 819 820 orig_ip = ip_hdr(skb_in)->saddr; 821 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 822 __icmp_send(skb_in, type, code, info, &opts); 823 ip_hdr(skb_in)->saddr = orig_ip; 824 out: 825 consume_skb(cloned_skb); 826 } 827 EXPORT_SYMBOL(icmp_ndo_send); 828 #endif 829 830 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 831 { 832 const struct iphdr *iph = (const struct iphdr *)skb->data; 833 const struct net_protocol *ipprot; 834 int protocol = iph->protocol; 835 836 /* Checkin full IP header plus 8 bytes of protocol to 837 * avoid additional coding at protocol handlers. 838 */ 839 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 840 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 841 return; 842 } 843 844 raw_icmp_error(skb, protocol, info); 845 846 ipprot = rcu_dereference(inet_protos[protocol]); 847 if (ipprot && ipprot->err_handler) 848 ipprot->err_handler(skb, info); 849 } 850 851 static bool icmp_tag_validation(int proto) 852 { 853 bool ok; 854 855 rcu_read_lock(); 856 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 857 rcu_read_unlock(); 858 return ok; 859 } 860 861 /* 862 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 863 * ICMP_PARAMETERPROB. 864 */ 865 866 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 867 { 868 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 869 const struct iphdr *iph; 870 struct icmphdr *icmph; 871 struct net *net; 872 u32 info = 0; 873 874 net = dev_net_rcu(skb_dst(skb)->dev); 875 876 /* 877 * Incomplete header ? 878 * Only checks for the IP header, there should be an 879 * additional check for longer headers in upper levels. 880 */ 881 882 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 883 goto out_err; 884 885 icmph = icmp_hdr(skb); 886 iph = (const struct iphdr *)skb->data; 887 888 if (iph->ihl < 5) { /* Mangled header, drop. */ 889 reason = SKB_DROP_REASON_IP_INHDR; 890 goto out_err; 891 } 892 893 switch (icmph->type) { 894 case ICMP_DEST_UNREACH: 895 switch (icmph->code & 15) { 896 case ICMP_NET_UNREACH: 897 case ICMP_HOST_UNREACH: 898 case ICMP_PROT_UNREACH: 899 case ICMP_PORT_UNREACH: 900 break; 901 case ICMP_FRAG_NEEDED: 902 /* for documentation of the ip_no_pmtu_disc 903 * values please see 904 * Documentation/networking/ip-sysctl.rst 905 */ 906 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 907 default: 908 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 909 &iph->daddr); 910 break; 911 case 2: 912 goto out; 913 case 3: 914 if (!icmp_tag_validation(iph->protocol)) 915 goto out; 916 fallthrough; 917 case 0: 918 info = ntohs(icmph->un.frag.mtu); 919 } 920 break; 921 case ICMP_SR_FAILED: 922 net_dbg_ratelimited("%pI4: Source Route Failed\n", 923 &iph->daddr); 924 break; 925 default: 926 break; 927 } 928 if (icmph->code > NR_ICMP_UNREACH) 929 goto out; 930 break; 931 case ICMP_PARAMETERPROB: 932 info = ntohl(icmph->un.gateway) >> 24; 933 break; 934 case ICMP_TIME_EXCEEDED: 935 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 936 if (icmph->code == ICMP_EXC_FRAGTIME) 937 goto out; 938 break; 939 } 940 941 /* 942 * Throw it at our lower layers 943 * 944 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 945 * header. 946 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 947 * transport layer. 948 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 949 * transport layer. 950 */ 951 952 /* 953 * Check the other end isn't violating RFC 1122. Some routers send 954 * bogus responses to broadcast frames. If you see this message 955 * first check your netmask matches at both ends, if it does then 956 * get the other vendor to fix their kit. 957 */ 958 959 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 960 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 961 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 962 &ip_hdr(skb)->saddr, 963 icmph->type, icmph->code, 964 &iph->daddr, skb->dev->name); 965 goto out; 966 } 967 968 icmp_socket_deliver(skb, info); 969 970 out: 971 return reason; 972 out_err: 973 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 974 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 975 } 976 977 978 /* 979 * Handle ICMP_REDIRECT. 980 */ 981 982 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 983 { 984 if (skb->len < sizeof(struct iphdr)) { 985 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 986 return SKB_DROP_REASON_PKT_TOO_SMALL; 987 } 988 989 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 990 /* there aught to be a stat */ 991 return SKB_DROP_REASON_NOMEM; 992 } 993 994 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 995 return SKB_NOT_DROPPED_YET; 996 } 997 998 /* 999 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1000 * 1001 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1002 * requests. 1003 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1004 * included in the reply. 1005 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1006 * echo requests, MUST have default=NOT. 1007 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1008 * Extended Echo Functionality, MUST be disabled by default 1009 * See also WRT handling of options once they are done and working. 1010 */ 1011 1012 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1013 { 1014 struct icmp_bxm icmp_param; 1015 struct net *net; 1016 1017 net = dev_net_rcu(skb_dst(skb)->dev); 1018 /* should there be an ICMP stat for ignored echos? */ 1019 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1020 return SKB_NOT_DROPPED_YET; 1021 1022 icmp_param.data.icmph = *icmp_hdr(skb); 1023 icmp_param.skb = skb; 1024 icmp_param.offset = 0; 1025 icmp_param.data_len = skb->len; 1026 icmp_param.head_len = sizeof(struct icmphdr); 1027 1028 if (icmp_param.data.icmph.type == ICMP_ECHO) 1029 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1030 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1031 return SKB_NOT_DROPPED_YET; 1032 1033 icmp_reply(&icmp_param, skb); 1034 return SKB_NOT_DROPPED_YET; 1035 } 1036 1037 /* Helper for icmp_echo and icmpv6_echo_reply. 1038 * Searches for net_device that matches PROBE interface identifier 1039 * and builds PROBE reply message in icmphdr. 1040 * 1041 * Returns false if PROBE responses are disabled via sysctl 1042 */ 1043 1044 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1045 { 1046 struct net *net = dev_net_rcu(skb->dev); 1047 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1048 struct icmp_ext_echo_iio *iio, _iio; 1049 struct inet6_dev *in6_dev; 1050 struct in_device *in_dev; 1051 struct net_device *dev; 1052 char buff[IFNAMSIZ]; 1053 u16 ident_len; 1054 u8 status; 1055 1056 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1057 return false; 1058 1059 /* We currently only support probing interfaces on the proxy node 1060 * Check to ensure L-bit is set 1061 */ 1062 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1063 return false; 1064 /* Clear status bits in reply message */ 1065 icmphdr->un.echo.sequence &= htons(0xFF00); 1066 if (icmphdr->type == ICMP_EXT_ECHO) 1067 icmphdr->type = ICMP_EXT_ECHOREPLY; 1068 else 1069 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1070 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1071 /* Size of iio is class_type dependent. 1072 * Only check header here and assign length based on ctype in the switch statement 1073 */ 1074 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1075 if (!ext_hdr || !iio) 1076 goto send_mal_query; 1077 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1078 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1079 goto send_mal_query; 1080 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1081 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1082 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1083 if (!iio) 1084 goto send_mal_query; 1085 1086 status = 0; 1087 dev = NULL; 1088 switch (iio->extobj_hdr.class_type) { 1089 case ICMP_EXT_ECHO_CTYPE_NAME: 1090 if (ident_len >= IFNAMSIZ) 1091 goto send_mal_query; 1092 memset(buff, 0, sizeof(buff)); 1093 memcpy(buff, &iio->ident.name, ident_len); 1094 dev = dev_get_by_name(net, buff); 1095 break; 1096 case ICMP_EXT_ECHO_CTYPE_INDEX: 1097 if (ident_len != sizeof(iio->ident.ifindex)) 1098 goto send_mal_query; 1099 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1100 break; 1101 case ICMP_EXT_ECHO_CTYPE_ADDR: 1102 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1103 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1104 iio->ident.addr.ctype3_hdr.addrlen) 1105 goto send_mal_query; 1106 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1107 case ICMP_AFI_IP: 1108 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1109 goto send_mal_query; 1110 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1111 break; 1112 #if IS_ENABLED(CONFIG_IPV6) 1113 case ICMP_AFI_IP6: 1114 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1115 goto send_mal_query; 1116 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1117 dev_hold(dev); 1118 break; 1119 #endif 1120 default: 1121 goto send_mal_query; 1122 } 1123 break; 1124 default: 1125 goto send_mal_query; 1126 } 1127 if (!dev) { 1128 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1129 return true; 1130 } 1131 /* Fill bits in reply message */ 1132 if (dev->flags & IFF_UP) 1133 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1134 1135 in_dev = __in_dev_get_rcu(dev); 1136 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1137 status |= ICMP_EXT_ECHOREPLY_IPV4; 1138 1139 in6_dev = __in6_dev_get(dev); 1140 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1141 status |= ICMP_EXT_ECHOREPLY_IPV6; 1142 1143 dev_put(dev); 1144 icmphdr->un.echo.sequence |= htons(status); 1145 return true; 1146 send_mal_query: 1147 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1148 return true; 1149 } 1150 EXPORT_SYMBOL_GPL(icmp_build_probe); 1151 1152 /* 1153 * Handle ICMP Timestamp requests. 1154 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1155 * SHOULD be in the kernel for minimum random latency. 1156 * MUST be accurate to a few minutes. 1157 * MUST be updated at least at 15Hz. 1158 */ 1159 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1160 { 1161 struct icmp_bxm icmp_param; 1162 /* 1163 * Too short. 1164 */ 1165 if (skb->len < 4) 1166 goto out_err; 1167 1168 /* 1169 * Fill in the current time as ms since midnight UT: 1170 */ 1171 icmp_param.data.times[1] = inet_current_timestamp(); 1172 icmp_param.data.times[2] = icmp_param.data.times[1]; 1173 1174 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1175 1176 icmp_param.data.icmph = *icmp_hdr(skb); 1177 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1178 icmp_param.data.icmph.code = 0; 1179 icmp_param.skb = skb; 1180 icmp_param.offset = 0; 1181 icmp_param.data_len = 0; 1182 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1183 icmp_reply(&icmp_param, skb); 1184 return SKB_NOT_DROPPED_YET; 1185 1186 out_err: 1187 __ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1188 return SKB_DROP_REASON_PKT_TOO_SMALL; 1189 } 1190 1191 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1192 { 1193 /* pretend it was a success */ 1194 return SKB_NOT_DROPPED_YET; 1195 } 1196 1197 /* 1198 * Deal with incoming ICMP packets. 1199 */ 1200 int icmp_rcv(struct sk_buff *skb) 1201 { 1202 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1203 struct rtable *rt = skb_rtable(skb); 1204 struct net *net = dev_net_rcu(rt->dst.dev); 1205 struct icmphdr *icmph; 1206 1207 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1208 struct sec_path *sp = skb_sec_path(skb); 1209 int nh; 1210 1211 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1212 XFRM_STATE_ICMP)) { 1213 reason = SKB_DROP_REASON_XFRM_POLICY; 1214 goto drop; 1215 } 1216 1217 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1218 goto drop; 1219 1220 nh = skb_network_offset(skb); 1221 skb_set_network_header(skb, sizeof(*icmph)); 1222 1223 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1224 skb)) { 1225 reason = SKB_DROP_REASON_XFRM_POLICY; 1226 goto drop; 1227 } 1228 1229 skb_set_network_header(skb, nh); 1230 } 1231 1232 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1233 1234 if (skb_checksum_simple_validate(skb)) 1235 goto csum_error; 1236 1237 if (!pskb_pull(skb, sizeof(*icmph))) 1238 goto error; 1239 1240 icmph = icmp_hdr(skb); 1241 1242 ICMPMSGIN_INC_STATS(net, icmph->type); 1243 1244 /* Check for ICMP Extended Echo (PROBE) messages */ 1245 if (icmph->type == ICMP_EXT_ECHO) { 1246 /* We can't use icmp_pointers[].handler() because it is an array of 1247 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1248 */ 1249 reason = icmp_echo(skb); 1250 goto reason_check; 1251 } 1252 1253 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1254 reason = ping_rcv(skb); 1255 goto reason_check; 1256 } 1257 1258 /* 1259 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1260 * 1261 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1262 * discarded. 1263 */ 1264 if (icmph->type > NR_ICMP_TYPES) { 1265 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1266 goto error; 1267 } 1268 1269 /* 1270 * Parse the ICMP message 1271 */ 1272 1273 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1274 /* 1275 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1276 * silently ignored (we let user decide with a sysctl). 1277 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1278 * discarded if to broadcast/multicast. 1279 */ 1280 if ((icmph->type == ICMP_ECHO || 1281 icmph->type == ICMP_TIMESTAMP) && 1282 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1283 reason = SKB_DROP_REASON_INVALID_PROTO; 1284 goto error; 1285 } 1286 if (icmph->type != ICMP_ECHO && 1287 icmph->type != ICMP_TIMESTAMP && 1288 icmph->type != ICMP_ADDRESS && 1289 icmph->type != ICMP_ADDRESSREPLY) { 1290 reason = SKB_DROP_REASON_INVALID_PROTO; 1291 goto error; 1292 } 1293 } 1294 1295 reason = icmp_pointers[icmph->type].handler(skb); 1296 reason_check: 1297 if (!reason) { 1298 consume_skb(skb); 1299 return NET_RX_SUCCESS; 1300 } 1301 1302 drop: 1303 kfree_skb_reason(skb, reason); 1304 return NET_RX_DROP; 1305 csum_error: 1306 reason = SKB_DROP_REASON_ICMP_CSUM; 1307 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1308 error: 1309 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1310 goto drop; 1311 } 1312 1313 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1314 { 1315 struct icmp_extobj_hdr *objh, _objh; 1316 struct icmp_ext_hdr *exth, _exth; 1317 u16 olen; 1318 1319 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1320 if (!exth) 1321 return false; 1322 if (exth->version != 2) 1323 return true; 1324 1325 if (exth->checksum && 1326 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1327 return false; 1328 1329 off += sizeof(_exth); 1330 while (off < skb->len) { 1331 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1332 if (!objh) 1333 return false; 1334 1335 olen = ntohs(objh->length); 1336 if (olen < sizeof(_objh)) 1337 return false; 1338 1339 off += olen; 1340 if (off > skb->len) 1341 return false; 1342 } 1343 1344 return true; 1345 } 1346 1347 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1348 struct sock_ee_data_rfc4884 *out, 1349 int thlen, int off) 1350 { 1351 int hlen; 1352 1353 /* original datagram headers: end of icmph to payload (skb->data) */ 1354 hlen = -skb_transport_offset(skb) - thlen; 1355 1356 /* per rfc 4884: minimal datagram length of 128 bytes */ 1357 if (off < 128 || off < hlen) 1358 return; 1359 1360 /* kernel has stripped headers: return payload offset in bytes */ 1361 off -= hlen; 1362 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1363 return; 1364 1365 out->len = off; 1366 1367 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1368 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1369 } 1370 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1371 1372 int icmp_err(struct sk_buff *skb, u32 info) 1373 { 1374 struct iphdr *iph = (struct iphdr *)skb->data; 1375 int offset = iph->ihl<<2; 1376 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1377 struct net *net = dev_net_rcu(skb->dev); 1378 int type = icmp_hdr(skb)->type; 1379 int code = icmp_hdr(skb)->code; 1380 1381 /* 1382 * Use ping_err to handle all icmp errors except those 1383 * triggered by ICMP_ECHOREPLY which sent from kernel. 1384 */ 1385 if (icmph->type != ICMP_ECHOREPLY) { 1386 ping_err(skb, offset, info); 1387 return 0; 1388 } 1389 1390 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1391 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1392 else if (type == ICMP_REDIRECT) 1393 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1394 1395 return 0; 1396 } 1397 1398 /* 1399 * This table is the definition of how we handle ICMP. 1400 */ 1401 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1402 [ICMP_ECHOREPLY] = { 1403 .handler = ping_rcv, 1404 }, 1405 [1] = { 1406 .handler = icmp_discard, 1407 .error = 1, 1408 }, 1409 [2] = { 1410 .handler = icmp_discard, 1411 .error = 1, 1412 }, 1413 [ICMP_DEST_UNREACH] = { 1414 .handler = icmp_unreach, 1415 .error = 1, 1416 }, 1417 [ICMP_SOURCE_QUENCH] = { 1418 .handler = icmp_unreach, 1419 .error = 1, 1420 }, 1421 [ICMP_REDIRECT] = { 1422 .handler = icmp_redirect, 1423 .error = 1, 1424 }, 1425 [6] = { 1426 .handler = icmp_discard, 1427 .error = 1, 1428 }, 1429 [7] = { 1430 .handler = icmp_discard, 1431 .error = 1, 1432 }, 1433 [ICMP_ECHO] = { 1434 .handler = icmp_echo, 1435 }, 1436 [9] = { 1437 .handler = icmp_discard, 1438 .error = 1, 1439 }, 1440 [10] = { 1441 .handler = icmp_discard, 1442 .error = 1, 1443 }, 1444 [ICMP_TIME_EXCEEDED] = { 1445 .handler = icmp_unreach, 1446 .error = 1, 1447 }, 1448 [ICMP_PARAMETERPROB] = { 1449 .handler = icmp_unreach, 1450 .error = 1, 1451 }, 1452 [ICMP_TIMESTAMP] = { 1453 .handler = icmp_timestamp, 1454 }, 1455 [ICMP_TIMESTAMPREPLY] = { 1456 .handler = icmp_discard, 1457 }, 1458 [ICMP_INFO_REQUEST] = { 1459 .handler = icmp_discard, 1460 }, 1461 [ICMP_INFO_REPLY] = { 1462 .handler = icmp_discard, 1463 }, 1464 [ICMP_ADDRESS] = { 1465 .handler = icmp_discard, 1466 }, 1467 [ICMP_ADDRESSREPLY] = { 1468 .handler = icmp_discard, 1469 }, 1470 }; 1471 1472 static int __net_init icmp_sk_init(struct net *net) 1473 { 1474 /* Control parameters for ECHO replies. */ 1475 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1476 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1477 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1478 1479 /* Control parameter - ignore bogus broadcast responses? */ 1480 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1481 1482 /* 1483 * Configurable global rate limit. 1484 * 1485 * ratelimit defines tokens/packet consumed for dst->rate_token 1486 * bucket ratemask defines which icmp types are ratelimited by 1487 * setting it's bit position. 1488 * 1489 * default: 1490 * dest unreachable (3), source quench (4), 1491 * time exceeded (11), parameter problem (12) 1492 */ 1493 1494 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1495 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1496 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1497 net->ipv4.sysctl_icmp_msgs_per_sec = 1000; 1498 net->ipv4.sysctl_icmp_msgs_burst = 50; 1499 1500 return 0; 1501 } 1502 1503 static struct pernet_operations __net_initdata icmp_sk_ops = { 1504 .init = icmp_sk_init, 1505 }; 1506 1507 int __init icmp_init(void) 1508 { 1509 int err, i; 1510 1511 for_each_possible_cpu(i) { 1512 struct sock *sk; 1513 1514 err = inet_ctl_sock_create(&sk, PF_INET, 1515 SOCK_RAW, IPPROTO_ICMP, &init_net); 1516 if (err < 0) 1517 return err; 1518 1519 per_cpu(ipv4_icmp_sk, i) = sk; 1520 1521 /* Enough space for 2 64K ICMP packets, including 1522 * sk_buff/skb_shared_info struct overhead. 1523 */ 1524 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1525 1526 /* 1527 * Speedup sock_wfree() 1528 */ 1529 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1530 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1531 } 1532 return register_pernet_subsys(&icmp_sk_ops); 1533 } 1534