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 bool (*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 /* 196 * The ICMP socket(s). This is the most convenient way to flow control 197 * our ICMP output as well as maintain a clean interface throughout 198 * all layers. All Socketless IP sends will soon be gone. 199 * 200 * On SMP we have one ICMP socket per-cpu. 201 */ 202 static struct sock *icmp_sk(struct net *net) 203 { 204 return this_cpu_read(*net->ipv4.icmp_sk); 205 } 206 207 /* Called with BH disabled */ 208 static inline struct sock *icmp_xmit_lock(struct net *net) 209 { 210 struct sock *sk; 211 212 sk = icmp_sk(net); 213 214 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 215 /* This can happen if the output path signals a 216 * dst_link_failure() for an outgoing ICMP packet. 217 */ 218 return NULL; 219 } 220 return sk; 221 } 222 223 static inline void icmp_xmit_unlock(struct sock *sk) 224 { 225 spin_unlock(&sk->sk_lock.slock); 226 } 227 228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 229 int sysctl_icmp_msgs_burst __read_mostly = 50; 230 231 static struct { 232 spinlock_t lock; 233 u32 credit; 234 u32 stamp; 235 } icmp_global = { 236 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 237 }; 238 239 /** 240 * icmp_global_allow - Are we allowed to send one more ICMP message ? 241 * 242 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec. 243 * Returns false if we reached the limit and can not send another packet. 244 * Note: called with BH disabled 245 */ 246 bool icmp_global_allow(void) 247 { 248 u32 credit, delta, incr = 0, now = (u32)jiffies; 249 bool rc = false; 250 251 /* Check if token bucket is empty and cannot be refilled 252 * without taking the spinlock. 253 */ 254 if (!icmp_global.credit) { 255 delta = min_t(u32, now - icmp_global.stamp, HZ); 256 if (delta < HZ / 50) 257 return false; 258 } 259 260 spin_lock(&icmp_global.lock); 261 delta = min_t(u32, now - icmp_global.stamp, HZ); 262 if (delta >= HZ / 50) { 263 incr = sysctl_icmp_msgs_per_sec * delta / HZ ; 264 if (incr) 265 icmp_global.stamp = now; 266 } 267 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst); 268 if (credit) { 269 credit--; 270 rc = true; 271 } 272 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) & 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 return false; 303 } 304 305 /* 306 * Send an ICMP frame. 307 */ 308 309 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 310 struct flowi4 *fl4, int type, int code) 311 { 312 struct dst_entry *dst = &rt->dst; 313 struct inet_peer *peer; 314 bool rc = true; 315 int vif; 316 317 if (icmpv4_mask_allow(net, type, code)) 318 goto out; 319 320 /* No rate limit on loopback */ 321 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 322 goto out; 323 324 vif = l3mdev_master_ifindex(dst->dev); 325 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 326 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit); 327 if (peer) 328 inet_putpeer(peer); 329 out: 330 return rc; 331 } 332 333 /* 334 * Maintain the counters used in the SNMP statistics for outgoing ICMP 335 */ 336 void icmp_out_count(struct net *net, unsigned char type) 337 { 338 ICMPMSGOUT_INC_STATS(net, type); 339 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 340 } 341 342 /* 343 * Checksum each fragment, and on the first include the headers and final 344 * checksum. 345 */ 346 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 347 struct sk_buff *skb) 348 { 349 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; 350 __wsum csum; 351 352 csum = skb_copy_and_csum_bits(icmp_param->skb, 353 icmp_param->offset + offset, 354 to, len, 0); 355 356 skb->csum = csum_block_add(skb->csum, csum, odd); 357 if (icmp_pointers[icmp_param->data.icmph.type].error) 358 nf_ct_attach(skb, icmp_param->skb); 359 return 0; 360 } 361 362 static void icmp_push_reply(struct icmp_bxm *icmp_param, 363 struct flowi4 *fl4, 364 struct ipcm_cookie *ipc, struct rtable **rt) 365 { 366 struct sock *sk; 367 struct sk_buff *skb; 368 369 sk = icmp_sk(dev_net((*rt)->dst.dev)); 370 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 371 icmp_param->data_len+icmp_param->head_len, 372 icmp_param->head_len, 373 ipc, rt, MSG_DONTWAIT) < 0) { 374 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 375 ip_flush_pending_frames(sk); 376 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 377 struct icmphdr *icmph = icmp_hdr(skb); 378 __wsum csum = 0; 379 struct sk_buff *skb1; 380 381 skb_queue_walk(&sk->sk_write_queue, skb1) { 382 csum = csum_add(csum, skb1->csum); 383 } 384 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 385 (char *)icmph, 386 icmp_param->head_len, csum); 387 icmph->checksum = csum_fold(csum); 388 skb->ip_summed = CHECKSUM_NONE; 389 ip_push_pending_frames(sk, fl4); 390 } 391 } 392 393 /* 394 * Driving logic for building and sending ICMP messages. 395 */ 396 397 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 398 { 399 struct ipcm_cookie ipc; 400 struct rtable *rt = skb_rtable(skb); 401 struct net *net = dev_net(rt->dst.dev); 402 struct flowi4 fl4; 403 struct sock *sk; 404 struct inet_sock *inet; 405 __be32 daddr, saddr; 406 u32 mark = IP4_REPLY_MARK(net, skb->mark); 407 int type = icmp_param->data.icmph.type; 408 int code = icmp_param->data.icmph.code; 409 410 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 411 return; 412 413 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 414 local_bh_disable(); 415 416 /* global icmp_msgs_per_sec */ 417 if (!icmpv4_global_allow(net, type, code)) 418 goto out_bh_enable; 419 420 sk = icmp_xmit_lock(net); 421 if (!sk) 422 goto out_bh_enable; 423 inet = inet_sk(sk); 424 425 icmp_param->data.icmph.checksum = 0; 426 427 ipcm_init(&ipc); 428 inet->tos = ip_hdr(skb)->tos; 429 sk->sk_mark = mark; 430 daddr = ipc.addr = ip_hdr(skb)->saddr; 431 saddr = fib_compute_spec_dst(skb); 432 433 if (icmp_param->replyopts.opt.opt.optlen) { 434 ipc.opt = &icmp_param->replyopts.opt; 435 if (ipc.opt->opt.srr) 436 daddr = icmp_param->replyopts.opt.opt.faddr; 437 } 438 memset(&fl4, 0, sizeof(fl4)); 439 fl4.daddr = daddr; 440 fl4.saddr = saddr; 441 fl4.flowi4_mark = mark; 442 fl4.flowi4_uid = sock_net_uid(net, NULL); 443 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 444 fl4.flowi4_proto = IPPROTO_ICMP; 445 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 446 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 447 rt = ip_route_output_key(net, &fl4); 448 if (IS_ERR(rt)) 449 goto out_unlock; 450 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 451 icmp_push_reply(icmp_param, &fl4, &ipc, &rt); 452 ip_rt_put(rt); 453 out_unlock: 454 icmp_xmit_unlock(sk); 455 out_bh_enable: 456 local_bh_enable(); 457 } 458 459 static struct rtable *icmp_route_lookup(struct net *net, 460 struct flowi4 *fl4, 461 struct sk_buff *skb_in, 462 const struct iphdr *iph, 463 __be32 saddr, u8 tos, u32 mark, 464 int type, int code, 465 struct icmp_bxm *param) 466 { 467 struct rtable *rt, *rt2; 468 struct flowi4 fl4_dec; 469 int err; 470 471 memset(fl4, 0, sizeof(*fl4)); 472 fl4->daddr = (param->replyopts.opt.opt.srr ? 473 param->replyopts.opt.opt.faddr : iph->saddr); 474 fl4->saddr = saddr; 475 fl4->flowi4_mark = mark; 476 fl4->flowi4_uid = sock_net_uid(net, NULL); 477 fl4->flowi4_tos = RT_TOS(tos); 478 fl4->flowi4_proto = IPPROTO_ICMP; 479 fl4->fl4_icmp_type = type; 480 fl4->fl4_icmp_code = code; 481 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev); 482 483 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4)); 484 rt = ip_route_output_key_hash(net, fl4, skb_in); 485 if (IS_ERR(rt)) 486 return rt; 487 488 /* No need to clone since we're just using its address. */ 489 rt2 = rt; 490 491 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 492 flowi4_to_flowi(fl4), NULL, 0); 493 if (!IS_ERR(rt)) { 494 if (rt != rt2) 495 return rt; 496 } else if (PTR_ERR(rt) == -EPERM) { 497 rt = NULL; 498 } else 499 return rt; 500 501 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 502 if (err) 503 goto relookup_failed; 504 505 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev, 506 fl4_dec.saddr) == RTN_LOCAL) { 507 rt2 = __ip_route_output_key(net, &fl4_dec); 508 if (IS_ERR(rt2)) 509 err = PTR_ERR(rt2); 510 } else { 511 struct flowi4 fl4_2 = {}; 512 unsigned long orefdst; 513 514 fl4_2.daddr = fl4_dec.saddr; 515 rt2 = ip_route_output_key(net, &fl4_2); 516 if (IS_ERR(rt2)) { 517 err = PTR_ERR(rt2); 518 goto relookup_failed; 519 } 520 /* Ugh! */ 521 orefdst = skb_in->_skb_refdst; /* save old refdst */ 522 skb_dst_set(skb_in, NULL); 523 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 524 RT_TOS(tos), rt2->dst.dev); 525 526 dst_release(&rt2->dst); 527 rt2 = skb_rtable(skb_in); 528 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 529 } 530 531 if (err) 532 goto relookup_failed; 533 534 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 535 flowi4_to_flowi(&fl4_dec), NULL, 536 XFRM_LOOKUP_ICMP); 537 if (!IS_ERR(rt2)) { 538 dst_release(&rt->dst); 539 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 540 rt = rt2; 541 } else if (PTR_ERR(rt2) == -EPERM) { 542 if (rt) 543 dst_release(&rt->dst); 544 return rt2; 545 } else { 546 err = PTR_ERR(rt2); 547 goto relookup_failed; 548 } 549 return rt; 550 551 relookup_failed: 552 if (rt) 553 return rt; 554 return ERR_PTR(err); 555 } 556 557 /* 558 * Send an ICMP message in response to a situation 559 * 560 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 561 * MAY send more (we do). 562 * MUST NOT change this header information. 563 * MUST NOT reply to a multicast/broadcast IP address. 564 * MUST NOT reply to a multicast/broadcast MAC address. 565 * MUST reply to only the first fragment. 566 */ 567 568 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 569 const struct ip_options *opt) 570 { 571 struct iphdr *iph; 572 int room; 573 struct icmp_bxm icmp_param; 574 struct rtable *rt = skb_rtable(skb_in); 575 struct ipcm_cookie ipc; 576 struct flowi4 fl4; 577 __be32 saddr; 578 u8 tos; 579 u32 mark; 580 struct net *net; 581 struct sock *sk; 582 583 if (!rt) 584 goto out; 585 net = dev_net(rt->dst.dev); 586 587 /* 588 * Find the original header. It is expected to be valid, of course. 589 * Check this, icmp_send is called from the most obscure devices 590 * sometimes. 591 */ 592 iph = ip_hdr(skb_in); 593 594 if ((u8 *)iph < skb_in->head || 595 (skb_network_header(skb_in) + sizeof(*iph)) > 596 skb_tail_pointer(skb_in)) 597 goto out; 598 599 /* 600 * No replies to physical multicast/broadcast 601 */ 602 if (skb_in->pkt_type != PACKET_HOST) 603 goto out; 604 605 /* 606 * Now check at the protocol level 607 */ 608 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 609 goto out; 610 611 /* 612 * Only reply to fragment 0. We byte re-order the constant 613 * mask for efficiency. 614 */ 615 if (iph->frag_off & htons(IP_OFFSET)) 616 goto out; 617 618 /* 619 * If we send an ICMP error to an ICMP error a mess would result.. 620 */ 621 if (icmp_pointers[type].error) { 622 /* 623 * We are an error, check if we are replying to an 624 * ICMP error 625 */ 626 if (iph->protocol == IPPROTO_ICMP) { 627 u8 _inner_type, *itp; 628 629 itp = skb_header_pointer(skb_in, 630 skb_network_header(skb_in) + 631 (iph->ihl << 2) + 632 offsetof(struct icmphdr, 633 type) - 634 skb_in->data, 635 sizeof(_inner_type), 636 &_inner_type); 637 if (!itp) 638 goto out; 639 640 /* 641 * Assume any unknown ICMP type is an error. This 642 * isn't specified by the RFC, but think about it.. 643 */ 644 if (*itp > NR_ICMP_TYPES || 645 icmp_pointers[*itp].error) 646 goto out; 647 } 648 } 649 650 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 651 local_bh_disable(); 652 653 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 654 * incoming dev is loopback. If outgoing dev change to not be 655 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 656 */ 657 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 658 !icmpv4_global_allow(net, type, code)) 659 goto out_bh_enable; 660 661 sk = icmp_xmit_lock(net); 662 if (!sk) 663 goto out_bh_enable; 664 665 /* 666 * Construct source address and options. 667 */ 668 669 saddr = iph->daddr; 670 if (!(rt->rt_flags & RTCF_LOCAL)) { 671 struct net_device *dev = NULL; 672 673 rcu_read_lock(); 674 if (rt_is_input_route(rt) && 675 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) 676 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 677 678 if (dev) 679 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); 680 else 681 saddr = 0; 682 rcu_read_unlock(); 683 } 684 685 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | 686 IPTOS_PREC_INTERNETCONTROL) : 687 iph->tos; 688 mark = IP4_REPLY_MARK(net, skb_in->mark); 689 690 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 691 goto out_unlock; 692 693 694 /* 695 * Prepare data for ICMP header. 696 */ 697 698 icmp_param.data.icmph.type = type; 699 icmp_param.data.icmph.code = code; 700 icmp_param.data.icmph.un.gateway = info; 701 icmp_param.data.icmph.checksum = 0; 702 icmp_param.skb = skb_in; 703 icmp_param.offset = skb_network_offset(skb_in); 704 inet_sk(sk)->tos = tos; 705 sk->sk_mark = mark; 706 ipcm_init(&ipc); 707 ipc.addr = iph->saddr; 708 ipc.opt = &icmp_param.replyopts.opt; 709 710 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 711 type, code, &icmp_param); 712 if (IS_ERR(rt)) 713 goto out_unlock; 714 715 /* peer icmp_ratelimit */ 716 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 717 goto ende; 718 719 /* RFC says return as much as we can without exceeding 576 bytes. */ 720 721 room = dst_mtu(&rt->dst); 722 if (room > 576) 723 room = 576; 724 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 725 room -= sizeof(struct icmphdr); 726 727 icmp_param.data_len = skb_in->len - icmp_param.offset; 728 if (icmp_param.data_len > room) 729 icmp_param.data_len = room; 730 icmp_param.head_len = sizeof(struct icmphdr); 731 732 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt); 733 ende: 734 ip_rt_put(rt); 735 out_unlock: 736 icmp_xmit_unlock(sk); 737 out_bh_enable: 738 local_bh_enable(); 739 out:; 740 } 741 EXPORT_SYMBOL(__icmp_send); 742 743 744 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 745 { 746 const struct iphdr *iph = (const struct iphdr *) skb->data; 747 const struct net_protocol *ipprot; 748 int protocol = iph->protocol; 749 750 /* Checkin full IP header plus 8 bytes of protocol to 751 * avoid additional coding at protocol handlers. 752 */ 753 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 754 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 755 return; 756 } 757 758 raw_icmp_error(skb, protocol, info); 759 760 ipprot = rcu_dereference(inet_protos[protocol]); 761 if (ipprot && ipprot->err_handler) 762 ipprot->err_handler(skb, info); 763 } 764 765 static bool icmp_tag_validation(int proto) 766 { 767 bool ok; 768 769 rcu_read_lock(); 770 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 771 rcu_read_unlock(); 772 return ok; 773 } 774 775 /* 776 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 777 * ICMP_PARAMETERPROB. 778 */ 779 780 static bool icmp_unreach(struct sk_buff *skb) 781 { 782 const struct iphdr *iph; 783 struct icmphdr *icmph; 784 struct net *net; 785 u32 info = 0; 786 787 net = dev_net(skb_dst(skb)->dev); 788 789 /* 790 * Incomplete header ? 791 * Only checks for the IP header, there should be an 792 * additional check for longer headers in upper levels. 793 */ 794 795 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 796 goto out_err; 797 798 icmph = icmp_hdr(skb); 799 iph = (const struct iphdr *)skb->data; 800 801 if (iph->ihl < 5) /* Mangled header, drop. */ 802 goto out_err; 803 804 switch (icmph->type) { 805 case ICMP_DEST_UNREACH: 806 switch (icmph->code & 15) { 807 case ICMP_NET_UNREACH: 808 case ICMP_HOST_UNREACH: 809 case ICMP_PROT_UNREACH: 810 case ICMP_PORT_UNREACH: 811 break; 812 case ICMP_FRAG_NEEDED: 813 /* for documentation of the ip_no_pmtu_disc 814 * values please see 815 * Documentation/networking/ip-sysctl.txt 816 */ 817 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 818 default: 819 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 820 &iph->daddr); 821 break; 822 case 2: 823 goto out; 824 case 3: 825 if (!icmp_tag_validation(iph->protocol)) 826 goto out; 827 /* fall through */ 828 case 0: 829 info = ntohs(icmph->un.frag.mtu); 830 } 831 break; 832 case ICMP_SR_FAILED: 833 net_dbg_ratelimited("%pI4: Source Route Failed\n", 834 &iph->daddr); 835 break; 836 default: 837 break; 838 } 839 if (icmph->code > NR_ICMP_UNREACH) 840 goto out; 841 break; 842 case ICMP_PARAMETERPROB: 843 info = ntohl(icmph->un.gateway) >> 24; 844 break; 845 case ICMP_TIME_EXCEEDED: 846 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 847 if (icmph->code == ICMP_EXC_FRAGTIME) 848 goto out; 849 break; 850 } 851 852 /* 853 * Throw it at our lower layers 854 * 855 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 856 * header. 857 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 858 * transport layer. 859 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 860 * transport layer. 861 */ 862 863 /* 864 * Check the other end isn't violating RFC 1122. Some routers send 865 * bogus responses to broadcast frames. If you see this message 866 * first check your netmask matches at both ends, if it does then 867 * get the other vendor to fix their kit. 868 */ 869 870 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && 871 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 872 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 873 &ip_hdr(skb)->saddr, 874 icmph->type, icmph->code, 875 &iph->daddr, skb->dev->name); 876 goto out; 877 } 878 879 icmp_socket_deliver(skb, info); 880 881 out: 882 return true; 883 out_err: 884 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 885 return false; 886 } 887 888 889 /* 890 * Handle ICMP_REDIRECT. 891 */ 892 893 static bool icmp_redirect(struct sk_buff *skb) 894 { 895 if (skb->len < sizeof(struct iphdr)) { 896 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 897 return false; 898 } 899 900 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 901 /* there aught to be a stat */ 902 return false; 903 } 904 905 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway); 906 return true; 907 } 908 909 /* 910 * Handle ICMP_ECHO ("ping") requests. 911 * 912 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 913 * requests. 914 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 915 * included in the reply. 916 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 917 * echo requests, MUST have default=NOT. 918 * See also WRT handling of options once they are done and working. 919 */ 920 921 static bool icmp_echo(struct sk_buff *skb) 922 { 923 struct net *net; 924 925 net = dev_net(skb_dst(skb)->dev); 926 if (!net->ipv4.sysctl_icmp_echo_ignore_all) { 927 struct icmp_bxm icmp_param; 928 929 icmp_param.data.icmph = *icmp_hdr(skb); 930 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 931 icmp_param.skb = skb; 932 icmp_param.offset = 0; 933 icmp_param.data_len = skb->len; 934 icmp_param.head_len = sizeof(struct icmphdr); 935 icmp_reply(&icmp_param, skb); 936 } 937 /* should there be an ICMP stat for ignored echos? */ 938 return true; 939 } 940 941 /* 942 * Handle ICMP Timestamp requests. 943 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 944 * SHOULD be in the kernel for minimum random latency. 945 * MUST be accurate to a few minutes. 946 * MUST be updated at least at 15Hz. 947 */ 948 static bool icmp_timestamp(struct sk_buff *skb) 949 { 950 struct icmp_bxm icmp_param; 951 /* 952 * Too short. 953 */ 954 if (skb->len < 4) 955 goto out_err; 956 957 /* 958 * Fill in the current time as ms since midnight UT: 959 */ 960 icmp_param.data.times[1] = inet_current_timestamp(); 961 icmp_param.data.times[2] = icmp_param.data.times[1]; 962 963 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 964 965 icmp_param.data.icmph = *icmp_hdr(skb); 966 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 967 icmp_param.data.icmph.code = 0; 968 icmp_param.skb = skb; 969 icmp_param.offset = 0; 970 icmp_param.data_len = 0; 971 icmp_param.head_len = sizeof(struct icmphdr) + 12; 972 icmp_reply(&icmp_param, skb); 973 return true; 974 975 out_err: 976 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 977 return false; 978 } 979 980 static bool icmp_discard(struct sk_buff *skb) 981 { 982 /* pretend it was a success */ 983 return true; 984 } 985 986 /* 987 * Deal with incoming ICMP packets. 988 */ 989 int icmp_rcv(struct sk_buff *skb) 990 { 991 struct icmphdr *icmph; 992 struct rtable *rt = skb_rtable(skb); 993 struct net *net = dev_net(rt->dst.dev); 994 bool success; 995 996 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 997 struct sec_path *sp = skb_sec_path(skb); 998 int nh; 999 1000 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1001 XFRM_STATE_ICMP)) 1002 goto drop; 1003 1004 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1005 goto drop; 1006 1007 nh = skb_network_offset(skb); 1008 skb_set_network_header(skb, sizeof(*icmph)); 1009 1010 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) 1011 goto drop; 1012 1013 skb_set_network_header(skb, nh); 1014 } 1015 1016 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1017 1018 if (skb_checksum_simple_validate(skb)) 1019 goto csum_error; 1020 1021 if (!pskb_pull(skb, sizeof(*icmph))) 1022 goto error; 1023 1024 icmph = icmp_hdr(skb); 1025 1026 ICMPMSGIN_INC_STATS(net, icmph->type); 1027 /* 1028 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1029 * 1030 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1031 * discarded. 1032 */ 1033 if (icmph->type > NR_ICMP_TYPES) 1034 goto error; 1035 1036 1037 /* 1038 * Parse the ICMP message 1039 */ 1040 1041 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1042 /* 1043 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1044 * silently ignored (we let user decide with a sysctl). 1045 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1046 * discarded if to broadcast/multicast. 1047 */ 1048 if ((icmph->type == ICMP_ECHO || 1049 icmph->type == ICMP_TIMESTAMP) && 1050 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { 1051 goto error; 1052 } 1053 if (icmph->type != ICMP_ECHO && 1054 icmph->type != ICMP_TIMESTAMP && 1055 icmph->type != ICMP_ADDRESS && 1056 icmph->type != ICMP_ADDRESSREPLY) { 1057 goto error; 1058 } 1059 } 1060 1061 success = icmp_pointers[icmph->type].handler(skb); 1062 1063 if (success) { 1064 consume_skb(skb); 1065 return NET_RX_SUCCESS; 1066 } 1067 1068 drop: 1069 kfree_skb(skb); 1070 return NET_RX_DROP; 1071 csum_error: 1072 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1073 error: 1074 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1075 goto drop; 1076 } 1077 1078 int icmp_err(struct sk_buff *skb, u32 info) 1079 { 1080 struct iphdr *iph = (struct iphdr *)skb->data; 1081 int offset = iph->ihl<<2; 1082 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1083 int type = icmp_hdr(skb)->type; 1084 int code = icmp_hdr(skb)->code; 1085 struct net *net = dev_net(skb->dev); 1086 1087 /* 1088 * Use ping_err to handle all icmp errors except those 1089 * triggered by ICMP_ECHOREPLY which sent from kernel. 1090 */ 1091 if (icmph->type != ICMP_ECHOREPLY) { 1092 ping_err(skb, offset, info); 1093 return 0; 1094 } 1095 1096 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1097 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1098 else if (type == ICMP_REDIRECT) 1099 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1100 1101 return 0; 1102 } 1103 1104 /* 1105 * This table is the definition of how we handle ICMP. 1106 */ 1107 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1108 [ICMP_ECHOREPLY] = { 1109 .handler = ping_rcv, 1110 }, 1111 [1] = { 1112 .handler = icmp_discard, 1113 .error = 1, 1114 }, 1115 [2] = { 1116 .handler = icmp_discard, 1117 .error = 1, 1118 }, 1119 [ICMP_DEST_UNREACH] = { 1120 .handler = icmp_unreach, 1121 .error = 1, 1122 }, 1123 [ICMP_SOURCE_QUENCH] = { 1124 .handler = icmp_unreach, 1125 .error = 1, 1126 }, 1127 [ICMP_REDIRECT] = { 1128 .handler = icmp_redirect, 1129 .error = 1, 1130 }, 1131 [6] = { 1132 .handler = icmp_discard, 1133 .error = 1, 1134 }, 1135 [7] = { 1136 .handler = icmp_discard, 1137 .error = 1, 1138 }, 1139 [ICMP_ECHO] = { 1140 .handler = icmp_echo, 1141 }, 1142 [9] = { 1143 .handler = icmp_discard, 1144 .error = 1, 1145 }, 1146 [10] = { 1147 .handler = icmp_discard, 1148 .error = 1, 1149 }, 1150 [ICMP_TIME_EXCEEDED] = { 1151 .handler = icmp_unreach, 1152 .error = 1, 1153 }, 1154 [ICMP_PARAMETERPROB] = { 1155 .handler = icmp_unreach, 1156 .error = 1, 1157 }, 1158 [ICMP_TIMESTAMP] = { 1159 .handler = icmp_timestamp, 1160 }, 1161 [ICMP_TIMESTAMPREPLY] = { 1162 .handler = icmp_discard, 1163 }, 1164 [ICMP_INFO_REQUEST] = { 1165 .handler = icmp_discard, 1166 }, 1167 [ICMP_INFO_REPLY] = { 1168 .handler = icmp_discard, 1169 }, 1170 [ICMP_ADDRESS] = { 1171 .handler = icmp_discard, 1172 }, 1173 [ICMP_ADDRESSREPLY] = { 1174 .handler = icmp_discard, 1175 }, 1176 }; 1177 1178 static void __net_exit icmp_sk_exit(struct net *net) 1179 { 1180 int i; 1181 1182 for_each_possible_cpu(i) 1183 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i)); 1184 free_percpu(net->ipv4.icmp_sk); 1185 net->ipv4.icmp_sk = NULL; 1186 } 1187 1188 static int __net_init icmp_sk_init(struct net *net) 1189 { 1190 int i, err; 1191 1192 net->ipv4.icmp_sk = alloc_percpu(struct sock *); 1193 if (!net->ipv4.icmp_sk) 1194 return -ENOMEM; 1195 1196 for_each_possible_cpu(i) { 1197 struct sock *sk; 1198 1199 err = inet_ctl_sock_create(&sk, PF_INET, 1200 SOCK_RAW, IPPROTO_ICMP, net); 1201 if (err < 0) 1202 goto fail; 1203 1204 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk; 1205 1206 /* Enough space for 2 64K ICMP packets, including 1207 * sk_buff/skb_shared_info struct overhead. 1208 */ 1209 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1210 1211 /* 1212 * Speedup sock_wfree() 1213 */ 1214 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1215 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1216 } 1217 1218 /* Control parameters for ECHO replies. */ 1219 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1220 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1221 1222 /* Control parameter - ignore bogus broadcast responses? */ 1223 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1224 1225 /* 1226 * Configurable global rate limit. 1227 * 1228 * ratelimit defines tokens/packet consumed for dst->rate_token 1229 * bucket ratemask defines which icmp types are ratelimited by 1230 * setting it's bit position. 1231 * 1232 * default: 1233 * dest unreachable (3), source quench (4), 1234 * time exceeded (11), parameter problem (12) 1235 */ 1236 1237 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1238 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1239 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1240 1241 return 0; 1242 1243 fail: 1244 icmp_sk_exit(net); 1245 return err; 1246 } 1247 1248 static struct pernet_operations __net_initdata icmp_sk_ops = { 1249 .init = icmp_sk_init, 1250 .exit = icmp_sk_exit, 1251 }; 1252 1253 int __init icmp_init(void) 1254 { 1255 return register_pernet_subsys(&icmp_sk_ops); 1256 } 1257