1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * NET3: Implementation of the ICMP protocol layer. 4 * 5 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 6 * 7 * Some of the function names and the icmp unreach table for this 8 * module were derived from [icmp.c 1.0.11 06/02/93] by 9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 10 * Other than that this module is a complete rewrite. 11 * 12 * Fixes: 13 * Clemens Fruhwirth : introduce global icmp rate limiting 14 * with icmp type masking ability instead 15 * of broken per type icmp timeouts. 16 * Mike Shaver : RFC1122 checks. 17 * Alan Cox : Multicast ping reply as self. 18 * Alan Cox : Fix atomicity lockup in ip_build_xmit 19 * call. 20 * Alan Cox : Added 216,128 byte paths to the MTU 21 * code. 22 * Martin Mares : RFC1812 checks. 23 * Martin Mares : Can be configured to follow redirects 24 * if acting as a router _without_ a 25 * routing protocol (RFC 1812). 26 * Martin Mares : Echo requests may be configured to 27 * be ignored (RFC 1812). 28 * Martin Mares : Limitation of ICMP error message 29 * transmit rate (RFC 1812). 30 * Martin Mares : TOS and Precedence set correctly 31 * (RFC 1812). 32 * Martin Mares : Now copying as much data from the 33 * original packet as we can without 34 * exceeding 576 bytes (RFC 1812). 35 * Willy Konynenberg : Transparent proxying support. 36 * Keith Owens : RFC1191 correction for 4.2BSD based 37 * path MTU bug. 38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 39 * valid (RFC 1812). 40 * Andi Kleen : Check all packet lengths properly 41 * and moved all kfree_skb() up to 42 * icmp_rcv. 43 * Andi Kleen : Move the rate limit bookkeeping 44 * into the dest entry and use a token 45 * bucket filter (thanks to ANK). Make 46 * the rates sysctl configurable. 47 * Yu Tianli : Fixed two ugly bugs in icmp_send 48 * - IP option length was accounted wrongly 49 * - ICMP header length was not accounted 50 * at all. 51 * Tristan Greaves : Added sysctl option to ignore bogus 52 * broadcast responses from broken routers. 53 * 54 * To Fix: 55 * 56 * - Should use skb_pull() instead of all the manual checking. 57 * This would also greatly simply some upper layer error handlers. --AK 58 */ 59 60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 61 62 #include <linux/module.h> 63 #include <linux/types.h> 64 #include <linux/jiffies.h> 65 #include <linux/kernel.h> 66 #include <linux/fcntl.h> 67 #include <linux/socket.h> 68 #include <linux/in.h> 69 #include <linux/inet.h> 70 #include <linux/inetdevice.h> 71 #include <linux/netdevice.h> 72 #include <linux/string.h> 73 #include <linux/netfilter_ipv4.h> 74 #include <linux/slab.h> 75 #include <net/snmp.h> 76 #include <net/ip.h> 77 #include <net/route.h> 78 #include <net/protocol.h> 79 #include <net/icmp.h> 80 #include <net/tcp.h> 81 #include <net/udp.h> 82 #include <net/raw.h> 83 #include <net/ping.h> 84 #include <linux/skbuff.h> 85 #include <net/sock.h> 86 #include <linux/errno.h> 87 #include <linux/timer.h> 88 #include <linux/init.h> 89 #include <linux/uaccess.h> 90 #include <net/checksum.h> 91 #include <net/xfrm.h> 92 #include <net/inet_common.h> 93 #include <net/ip_fib.h> 94 #include <net/l3mdev.h> 95 96 /* 97 * Build xmit assembly blocks 98 */ 99 100 struct icmp_bxm { 101 struct sk_buff *skb; 102 int offset; 103 int data_len; 104 105 struct { 106 struct icmphdr icmph; 107 __be32 times[3]; 108 } data; 109 int head_len; 110 struct ip_options_data replyopts; 111 }; 112 113 /* An array of errno for error messages from dest unreach. */ 114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 115 116 const struct icmp_err icmp_err_convert[] = { 117 { 118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 119 .fatal = 0, 120 }, 121 { 122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 123 .fatal = 0, 124 }, 125 { 126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 127 .fatal = 1, 128 }, 129 { 130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 131 .fatal = 1, 132 }, 133 { 134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 135 .fatal = 0, 136 }, 137 { 138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 139 .fatal = 0, 140 }, 141 { 142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 143 .fatal = 1, 144 }, 145 { 146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 147 .fatal = 1, 148 }, 149 { 150 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 151 .fatal = 1, 152 }, 153 { 154 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 155 .fatal = 1, 156 }, 157 { 158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 159 .fatal = 1, 160 }, 161 { 162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 163 .fatal = 0, 164 }, 165 { 166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 167 .fatal = 0, 168 }, 169 { 170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 171 .fatal = 1, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 175 .fatal = 1, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 179 .fatal = 1, 180 }, 181 }; 182 EXPORT_SYMBOL(icmp_err_convert); 183 184 /* 185 * ICMP control array. This specifies what to do with each ICMP. 186 */ 187 188 struct icmp_control { 189 enum skb_drop_reason (*handler)(struct sk_buff *skb); 190 short error; /* This ICMP is classed as an error message */ 191 }; 192 193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 194 195 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 196 197 /* Called with BH disabled */ 198 static inline struct sock *icmp_xmit_lock(struct net *net) 199 { 200 struct sock *sk; 201 202 sk = this_cpu_read(ipv4_icmp_sk); 203 204 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 205 /* This can happen if the output path signals a 206 * dst_link_failure() for an outgoing ICMP packet. 207 */ 208 return NULL; 209 } 210 sock_net_set(sk, net); 211 return sk; 212 } 213 214 static inline void icmp_xmit_unlock(struct sock *sk) 215 { 216 sock_net_set(sk, &init_net); 217 spin_unlock(&sk->sk_lock.slock); 218 } 219 220 int sysctl_icmp_msgs_per_sec __read_mostly = 1000; 221 int sysctl_icmp_msgs_burst __read_mostly = 50; 222 223 static struct { 224 spinlock_t lock; 225 u32 credit; 226 u32 stamp; 227 } icmp_global = { 228 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock), 229 }; 230 231 /** 232 * icmp_global_allow - Are we allowed to send one more ICMP message ? 233 * 234 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 235 * Returns false if we reached the limit and can not send another packet. 236 * Note: called with BH disabled 237 */ 238 bool icmp_global_allow(void) 239 { 240 u32 credit, delta, incr = 0, now = (u32)jiffies; 241 bool rc = false; 242 243 /* Check if token bucket is empty and cannot be refilled 244 * without taking the spinlock. The READ_ONCE() are paired 245 * with the following WRITE_ONCE() in this same function. 246 */ 247 if (!READ_ONCE(icmp_global.credit)) { 248 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ); 249 if (delta < HZ / 50) 250 return false; 251 } 252 253 spin_lock(&icmp_global.lock); 254 delta = min_t(u32, now - icmp_global.stamp, HZ); 255 if (delta >= HZ / 50) { 256 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ; 257 if (incr) 258 WRITE_ONCE(icmp_global.stamp, now); 259 } 260 credit = min_t(u32, icmp_global.credit + incr, 261 READ_ONCE(sysctl_icmp_msgs_burst)); 262 if (credit) { 263 /* We want to use a credit of one in average, but need to randomize 264 * it for security reasons. 265 */ 266 credit = max_t(int, credit - prandom_u32_max(3), 0); 267 rc = true; 268 } 269 WRITE_ONCE(icmp_global.credit, credit); 270 spin_unlock(&icmp_global.lock); 271 return rc; 272 } 273 EXPORT_SYMBOL(icmp_global_allow); 274 275 static bool icmpv4_mask_allow(struct net *net, int type, int code) 276 { 277 if (type > NR_ICMP_TYPES) 278 return true; 279 280 /* Don't limit PMTU discovery. */ 281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 282 return true; 283 284 /* Limit if icmp type is enabled in ratemask. */ 285 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 286 return true; 287 288 return false; 289 } 290 291 static bool icmpv4_global_allow(struct net *net, int type, int code) 292 { 293 if (icmpv4_mask_allow(net, type, code)) 294 return true; 295 296 if (icmp_global_allow()) 297 return true; 298 299 return false; 300 } 301 302 /* 303 * Send an ICMP frame. 304 */ 305 306 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 307 struct flowi4 *fl4, int type, int code) 308 { 309 struct dst_entry *dst = &rt->dst; 310 struct inet_peer *peer; 311 bool rc = true; 312 int vif; 313 314 if (icmpv4_mask_allow(net, type, code)) 315 goto out; 316 317 /* No rate limit on loopback */ 318 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 319 goto out; 320 321 vif = l3mdev_master_ifindex(dst->dev); 322 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 323 rc = inet_peer_xrlim_allow(peer, 324 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 325 if (peer) 326 inet_putpeer(peer); 327 out: 328 return rc; 329 } 330 331 /* 332 * Maintain the counters used in the SNMP statistics for outgoing ICMP 333 */ 334 void icmp_out_count(struct net *net, unsigned char type) 335 { 336 ICMPMSGOUT_INC_STATS(net, type); 337 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 338 } 339 340 /* 341 * Checksum each fragment, and on the first include the headers and final 342 * checksum. 343 */ 344 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 345 struct sk_buff *skb) 346 { 347 struct icmp_bxm *icmp_param = from; 348 __wsum csum; 349 350 csum = skb_copy_and_csum_bits(icmp_param->skb, 351 icmp_param->offset + offset, 352 to, len); 353 354 skb->csum = csum_block_add(skb->csum, csum, odd); 355 if (icmp_pointers[icmp_param->data.icmph.type].error) 356 nf_ct_attach(skb, icmp_param->skb); 357 return 0; 358 } 359 360 static void icmp_push_reply(struct sock *sk, 361 struct icmp_bxm *icmp_param, 362 struct flowi4 *fl4, 363 struct ipcm_cookie *ipc, struct rtable **rt) 364 { 365 struct sk_buff *skb; 366 367 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 368 icmp_param->data_len+icmp_param->head_len, 369 icmp_param->head_len, 370 ipc, rt, MSG_DONTWAIT) < 0) { 371 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 372 ip_flush_pending_frames(sk); 373 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 374 struct icmphdr *icmph = icmp_hdr(skb); 375 __wsum csum; 376 struct sk_buff *skb1; 377 378 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 379 (char *)icmph, 380 icmp_param->head_len); 381 skb_queue_walk(&sk->sk_write_queue, skb1) { 382 csum = csum_add(csum, skb1->csum); 383 } 384 icmph->checksum = csum_fold(csum); 385 skb->ip_summed = CHECKSUM_NONE; 386 ip_push_pending_frames(sk, fl4); 387 } 388 } 389 390 /* 391 * Driving logic for building and sending ICMP messages. 392 */ 393 394 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 395 { 396 struct ipcm_cookie ipc; 397 struct rtable *rt = skb_rtable(skb); 398 struct net *net = dev_net(rt->dst.dev); 399 struct flowi4 fl4; 400 struct sock *sk; 401 struct inet_sock *inet; 402 __be32 daddr, saddr; 403 u32 mark = IP4_REPLY_MARK(net, skb->mark); 404 int type = icmp_param->data.icmph.type; 405 int code = icmp_param->data.icmph.code; 406 407 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 408 return; 409 410 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 411 local_bh_disable(); 412 413 /* global icmp_msgs_per_sec */ 414 if (!icmpv4_global_allow(net, type, code)) 415 goto out_bh_enable; 416 417 sk = icmp_xmit_lock(net); 418 if (!sk) 419 goto out_bh_enable; 420 inet = inet_sk(sk); 421 422 icmp_param->data.icmph.checksum = 0; 423 424 ipcm_init(&ipc); 425 inet->tos = ip_hdr(skb)->tos; 426 ipc.sockc.mark = mark; 427 daddr = ipc.addr = ip_hdr(skb)->saddr; 428 saddr = fib_compute_spec_dst(skb); 429 430 if (icmp_param->replyopts.opt.opt.optlen) { 431 ipc.opt = &icmp_param->replyopts.opt; 432 if (ipc.opt->opt.srr) 433 daddr = icmp_param->replyopts.opt.opt.faddr; 434 } 435 memset(&fl4, 0, sizeof(fl4)); 436 fl4.daddr = daddr; 437 fl4.saddr = saddr; 438 fl4.flowi4_mark = mark; 439 fl4.flowi4_uid = sock_net_uid(net, NULL); 440 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); 441 fl4.flowi4_proto = IPPROTO_ICMP; 442 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 443 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 444 rt = ip_route_output_key(net, &fl4); 445 if (IS_ERR(rt)) 446 goto out_unlock; 447 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 448 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 449 ip_rt_put(rt); 450 out_unlock: 451 icmp_xmit_unlock(sk); 452 out_bh_enable: 453 local_bh_enable(); 454 } 455 456 /* 457 * The device used for looking up which routing table to use for sending an ICMP 458 * error is preferably the source whenever it is set, which should ensure the 459 * icmp error can be sent to the source host, else lookup using the routing 460 * table of the destination device, else use the main routing table (index 0). 461 */ 462 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 463 { 464 struct net_device *route_lookup_dev = NULL; 465 466 if (skb->dev) 467 route_lookup_dev = skb->dev; 468 else if (skb_dst(skb)) 469 route_lookup_dev = skb_dst(skb)->dev; 470 return route_lookup_dev; 471 } 472 473 static struct rtable *icmp_route_lookup(struct net *net, 474 struct flowi4 *fl4, 475 struct sk_buff *skb_in, 476 const struct iphdr *iph, 477 __be32 saddr, u8 tos, u32 mark, 478 int type, int code, 479 struct icmp_bxm *param) 480 { 481 struct net_device *route_lookup_dev; 482 struct rtable *rt, *rt2; 483 struct flowi4 fl4_dec; 484 int err; 485 486 memset(fl4, 0, sizeof(*fl4)); 487 fl4->daddr = (param->replyopts.opt.opt.srr ? 488 param->replyopts.opt.opt.faddr : iph->saddr); 489 fl4->saddr = saddr; 490 fl4->flowi4_mark = mark; 491 fl4->flowi4_uid = sock_net_uid(net, NULL); 492 fl4->flowi4_tos = RT_TOS(tos); 493 fl4->flowi4_proto = IPPROTO_ICMP; 494 fl4->fl4_icmp_type = type; 495 fl4->fl4_icmp_code = code; 496 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 497 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 498 499 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 500 rt = ip_route_output_key_hash(net, fl4, skb_in); 501 if (IS_ERR(rt)) 502 return rt; 503 504 /* No need to clone since we're just using its address. */ 505 rt2 = rt; 506 507 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 508 flowi4_to_flowi(fl4), NULL, 0); 509 if (!IS_ERR(rt)) { 510 if (rt != rt2) 511 return rt; 512 } else if (PTR_ERR(rt) == -EPERM) { 513 rt = NULL; 514 } else 515 return rt; 516 517 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 518 if (err) 519 goto relookup_failed; 520 521 if (inet_addr_type_dev_table(net, route_lookup_dev, 522 fl4_dec.saddr) == RTN_LOCAL) { 523 rt2 = __ip_route_output_key(net, &fl4_dec); 524 if (IS_ERR(rt2)) 525 err = PTR_ERR(rt2); 526 } else { 527 struct flowi4 fl4_2 = {}; 528 unsigned long orefdst; 529 530 fl4_2.daddr = fl4_dec.saddr; 531 rt2 = ip_route_output_key(net, &fl4_2); 532 if (IS_ERR(rt2)) { 533 err = PTR_ERR(rt2); 534 goto relookup_failed; 535 } 536 /* Ugh! */ 537 orefdst = skb_in->_skb_refdst; /* save old refdst */ 538 skb_dst_set(skb_in, NULL); 539 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 540 RT_TOS(tos), rt2->dst.dev); 541 542 dst_release(&rt2->dst); 543 rt2 = skb_rtable(skb_in); 544 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 545 } 546 547 if (err) 548 goto relookup_failed; 549 550 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 551 flowi4_to_flowi(&fl4_dec), NULL, 552 XFRM_LOOKUP_ICMP); 553 if (!IS_ERR(rt2)) { 554 dst_release(&rt->dst); 555 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 556 rt = rt2; 557 } else if (PTR_ERR(rt2) == -EPERM) { 558 if (rt) 559 dst_release(&rt->dst); 560 return rt2; 561 } else { 562 err = PTR_ERR(rt2); 563 goto relookup_failed; 564 } 565 return rt; 566 567 relookup_failed: 568 if (rt) 569 return rt; 570 return ERR_PTR(err); 571 } 572 573 /* 574 * Send an ICMP message in response to a situation 575 * 576 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 577 * MAY send more (we do). 578 * MUST NOT change this header information. 579 * MUST NOT reply to a multicast/broadcast IP address. 580 * MUST NOT reply to a multicast/broadcast MAC address. 581 * MUST reply to only the first fragment. 582 */ 583 584 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 585 const struct ip_options *opt) 586 { 587 struct iphdr *iph; 588 int room; 589 struct icmp_bxm icmp_param; 590 struct rtable *rt = skb_rtable(skb_in); 591 struct ipcm_cookie ipc; 592 struct flowi4 fl4; 593 __be32 saddr; 594 u8 tos; 595 u32 mark; 596 struct net *net; 597 struct sock *sk; 598 599 if (!rt) 600 goto out; 601 602 if (rt->dst.dev) 603 net = dev_net(rt->dst.dev); 604 else if (skb_in->dev) 605 net = dev_net(skb_in->dev); 606 else 607 goto out; 608 609 /* 610 * Find the original header. It is expected to be valid, of course. 611 * Check this, icmp_send is called from the most obscure devices 612 * sometimes. 613 */ 614 iph = ip_hdr(skb_in); 615 616 if ((u8 *)iph < skb_in->head || 617 (skb_network_header(skb_in) + sizeof(*iph)) > 618 skb_tail_pointer(skb_in)) 619 goto out; 620 621 /* 622 * No replies to physical multicast/broadcast 623 */ 624 if (skb_in->pkt_type != PACKET_HOST) 625 goto out; 626 627 /* 628 * Now check at the protocol level 629 */ 630 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 631 goto out; 632 633 /* 634 * Only reply to fragment 0. We byte re-order the constant 635 * mask for efficiency. 636 */ 637 if (iph->frag_off & htons(IP_OFFSET)) 638 goto out; 639 640 /* 641 * If we send an ICMP error to an ICMP error a mess would result.. 642 */ 643 if (icmp_pointers[type].error) { 644 /* 645 * We are an error, check if we are replying to an 646 * ICMP error 647 */ 648 if (iph->protocol == IPPROTO_ICMP) { 649 u8 _inner_type, *itp; 650 651 itp = skb_header_pointer(skb_in, 652 skb_network_header(skb_in) + 653 (iph->ihl << 2) + 654 offsetof(struct icmphdr, 655 type) - 656 skb_in->data, 657 sizeof(_inner_type), 658 &_inner_type); 659 if (!itp) 660 goto out; 661 662 /* 663 * Assume any unknown ICMP type is an error. This 664 * isn't specified by the RFC, but think about it.. 665 */ 666 if (*itp > NR_ICMP_TYPES || 667 icmp_pointers[*itp].error) 668 goto out; 669 } 670 } 671 672 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 673 local_bh_disable(); 674 675 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 676 * incoming dev is loopback. If outgoing dev change to not be 677 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 678 */ 679 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 680 !icmpv4_global_allow(net, type, code)) 681 goto out_bh_enable; 682 683 sk = icmp_xmit_lock(net); 684 if (!sk) 685 goto out_bh_enable; 686 687 /* 688 * Construct source address and options. 689 */ 690 691 saddr = iph->daddr; 692 if (!(rt->rt_flags & RTCF_LOCAL)) { 693 struct net_device *dev = NULL; 694 695 rcu_read_lock(); 696 if (rt_is_input_route(rt) && 697 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 698 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 699 700 if (dev) 701 saddr = inet_select_addr(dev, iph->saddr, 702 RT_SCOPE_LINK); 703 else 704 saddr = 0; 705 rcu_read_unlock(); 706 } 707 708 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 709 IPTOS_PREC_INTERNETCONTROL) : 710 iph->tos; 711 mark = IP4_REPLY_MARK(net, skb_in->mark); 712 713 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 714 goto out_unlock; 715 716 717 /* 718 * Prepare data for ICMP header. 719 */ 720 721 icmp_param.data.icmph.type = type; 722 icmp_param.data.icmph.code = code; 723 icmp_param.data.icmph.un.gateway = info; 724 icmp_param.data.icmph.checksum = 0; 725 icmp_param.skb = skb_in; 726 icmp_param.offset = skb_network_offset(skb_in); 727 inet_sk(sk)->tos = tos; 728 ipcm_init(&ipc); 729 ipc.addr = iph->saddr; 730 ipc.opt = &icmp_param.replyopts.opt; 731 ipc.sockc.mark = mark; 732 733 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 734 type, code, &icmp_param); 735 if (IS_ERR(rt)) 736 goto out_unlock; 737 738 /* peer icmp_ratelimit */ 739 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 740 goto ende; 741 742 /* RFC says return as much as we can without exceeding 576 bytes. */ 743 744 room = dst_mtu(&rt->dst); 745 if (room > 576) 746 room = 576; 747 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 748 room -= sizeof(struct icmphdr); 749 750 icmp_param.data_len = skb_in->len - icmp_param.offset; 751 if (icmp_param.data_len > room) 752 icmp_param.data_len = room; 753 icmp_param.head_len = sizeof(struct icmphdr); 754 755 /* if we don't have a source address at this point, fall back to the 756 * dummy address instead of sending out a packet with a source address 757 * of 0.0.0.0 758 */ 759 if (!fl4.saddr) 760 fl4.saddr = htonl(INADDR_DUMMY); 761 762 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 763 ende: 764 ip_rt_put(rt); 765 out_unlock: 766 icmp_xmit_unlock(sk); 767 out_bh_enable: 768 local_bh_enable(); 769 out:; 770 } 771 EXPORT_SYMBOL(__icmp_send); 772 773 #if IS_ENABLED(CONFIG_NF_NAT) 774 #include <net/netfilter/nf_conntrack.h> 775 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 776 { 777 struct sk_buff *cloned_skb = NULL; 778 struct ip_options opts = { 0 }; 779 enum ip_conntrack_info ctinfo; 780 struct nf_conn *ct; 781 __be32 orig_ip; 782 783 ct = nf_ct_get(skb_in, &ctinfo); 784 if (!ct || !(ct->status & IPS_SRC_NAT)) { 785 __icmp_send(skb_in, type, code, info, &opts); 786 return; 787 } 788 789 if (skb_shared(skb_in)) 790 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 791 792 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 793 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 794 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 795 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 796 goto out; 797 798 orig_ip = ip_hdr(skb_in)->saddr; 799 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 800 __icmp_send(skb_in, type, code, info, &opts); 801 ip_hdr(skb_in)->saddr = orig_ip; 802 out: 803 consume_skb(cloned_skb); 804 } 805 EXPORT_SYMBOL(icmp_ndo_send); 806 #endif 807 808 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 809 { 810 const struct iphdr *iph = (const struct iphdr *)skb->data; 811 const struct net_protocol *ipprot; 812 int protocol = iph->protocol; 813 814 /* Checkin full IP header plus 8 bytes of protocol to 815 * avoid additional coding at protocol handlers. 816 */ 817 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 818 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 819 return; 820 } 821 822 raw_icmp_error(skb, protocol, info); 823 824 ipprot = rcu_dereference(inet_protos[protocol]); 825 if (ipprot && ipprot->err_handler) 826 ipprot->err_handler(skb, info); 827 } 828 829 static bool icmp_tag_validation(int proto) 830 { 831 bool ok; 832 833 rcu_read_lock(); 834 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 835 rcu_read_unlock(); 836 return ok; 837 } 838 839 /* 840 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 841 * ICMP_PARAMETERPROB. 842 */ 843 844 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 845 { 846 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 847 const struct iphdr *iph; 848 struct icmphdr *icmph; 849 struct net *net; 850 u32 info = 0; 851 852 net = dev_net(skb_dst(skb)->dev); 853 854 /* 855 * Incomplete header ? 856 * Only checks for the IP header, there should be an 857 * additional check for longer headers in upper levels. 858 */ 859 860 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 861 goto out_err; 862 863 icmph = icmp_hdr(skb); 864 iph = (const struct iphdr *)skb->data; 865 866 if (iph->ihl < 5) { /* Mangled header, drop. */ 867 reason = SKB_DROP_REASON_IP_INHDR; 868 goto out_err; 869 } 870 871 switch (icmph->type) { 872 case ICMP_DEST_UNREACH: 873 switch (icmph->code & 15) { 874 case ICMP_NET_UNREACH: 875 case ICMP_HOST_UNREACH: 876 case ICMP_PROT_UNREACH: 877 case ICMP_PORT_UNREACH: 878 break; 879 case ICMP_FRAG_NEEDED: 880 /* for documentation of the ip_no_pmtu_disc 881 * values please see 882 * Documentation/networking/ip-sysctl.rst 883 */ 884 switch (net->ipv4.sysctl_ip_no_pmtu_disc) { 885 default: 886 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 887 &iph->daddr); 888 break; 889 case 2: 890 goto out; 891 case 3: 892 if (!icmp_tag_validation(iph->protocol)) 893 goto out; 894 fallthrough; 895 case 0: 896 info = ntohs(icmph->un.frag.mtu); 897 } 898 break; 899 case ICMP_SR_FAILED: 900 net_dbg_ratelimited("%pI4: Source Route Failed\n", 901 &iph->daddr); 902 break; 903 default: 904 break; 905 } 906 if (icmph->code > NR_ICMP_UNREACH) 907 goto out; 908 break; 909 case ICMP_PARAMETERPROB: 910 info = ntohl(icmph->un.gateway) >> 24; 911 break; 912 case ICMP_TIME_EXCEEDED: 913 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 914 if (icmph->code == ICMP_EXC_FRAGTIME) 915 goto out; 916 break; 917 } 918 919 /* 920 * Throw it at our lower layers 921 * 922 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 923 * header. 924 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 925 * transport layer. 926 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 927 * transport layer. 928 */ 929 930 /* 931 * Check the other end isn't violating RFC 1122. Some routers send 932 * bogus responses to broadcast frames. If you see this message 933 * first check your netmask matches at both ends, if it does then 934 * get the other vendor to fix their kit. 935 */ 936 937 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 938 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 939 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 940 &ip_hdr(skb)->saddr, 941 icmph->type, icmph->code, 942 &iph->daddr, skb->dev->name); 943 goto out; 944 } 945 946 icmp_socket_deliver(skb, info); 947 948 out: 949 return reason; 950 out_err: 951 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 952 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 953 } 954 955 956 /* 957 * Handle ICMP_REDIRECT. 958 */ 959 960 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 961 { 962 if (skb->len < sizeof(struct iphdr)) { 963 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 964 return SKB_DROP_REASON_PKT_TOO_SMALL; 965 } 966 967 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 968 /* there aught to be a stat */ 969 return SKB_DROP_REASON_NOMEM; 970 } 971 972 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 973 return SKB_NOT_DROPPED_YET; 974 } 975 976 /* 977 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 978 * 979 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 980 * requests. 981 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 982 * included in the reply. 983 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 984 * echo requests, MUST have default=NOT. 985 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 986 * Extended Echo Functionality, MUST be disabled by default 987 * See also WRT handling of options once they are done and working. 988 */ 989 990 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 991 { 992 struct icmp_bxm icmp_param; 993 struct net *net; 994 995 net = dev_net(skb_dst(skb)->dev); 996 /* should there be an ICMP stat for ignored echos? */ 997 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 998 return SKB_NOT_DROPPED_YET; 999 1000 icmp_param.data.icmph = *icmp_hdr(skb); 1001 icmp_param.skb = skb; 1002 icmp_param.offset = 0; 1003 icmp_param.data_len = skb->len; 1004 icmp_param.head_len = sizeof(struct icmphdr); 1005 1006 if (icmp_param.data.icmph.type == ICMP_ECHO) 1007 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1008 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1009 return SKB_NOT_DROPPED_YET; 1010 1011 icmp_reply(&icmp_param, skb); 1012 return SKB_NOT_DROPPED_YET; 1013 } 1014 1015 /* Helper for icmp_echo and icmpv6_echo_reply. 1016 * Searches for net_device that matches PROBE interface identifier 1017 * and builds PROBE reply message in icmphdr. 1018 * 1019 * Returns false if PROBE responses are disabled via sysctl 1020 */ 1021 1022 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1023 { 1024 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1025 struct icmp_ext_echo_iio *iio, _iio; 1026 struct net *net = dev_net(skb->dev); 1027 struct net_device *dev; 1028 char buff[IFNAMSIZ]; 1029 u16 ident_len; 1030 u8 status; 1031 1032 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1033 return false; 1034 1035 /* We currently only support probing interfaces on the proxy node 1036 * Check to ensure L-bit is set 1037 */ 1038 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1039 return false; 1040 /* Clear status bits in reply message */ 1041 icmphdr->un.echo.sequence &= htons(0xFF00); 1042 if (icmphdr->type == ICMP_EXT_ECHO) 1043 icmphdr->type = ICMP_EXT_ECHOREPLY; 1044 else 1045 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1046 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1047 /* Size of iio is class_type dependent. 1048 * Only check header here and assign length based on ctype in the switch statement 1049 */ 1050 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1051 if (!ext_hdr || !iio) 1052 goto send_mal_query; 1053 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1054 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1055 goto send_mal_query; 1056 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1057 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1058 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1059 if (!iio) 1060 goto send_mal_query; 1061 1062 status = 0; 1063 dev = NULL; 1064 switch (iio->extobj_hdr.class_type) { 1065 case ICMP_EXT_ECHO_CTYPE_NAME: 1066 if (ident_len >= IFNAMSIZ) 1067 goto send_mal_query; 1068 memset(buff, 0, sizeof(buff)); 1069 memcpy(buff, &iio->ident.name, ident_len); 1070 dev = dev_get_by_name(net, buff); 1071 break; 1072 case ICMP_EXT_ECHO_CTYPE_INDEX: 1073 if (ident_len != sizeof(iio->ident.ifindex)) 1074 goto send_mal_query; 1075 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1076 break; 1077 case ICMP_EXT_ECHO_CTYPE_ADDR: 1078 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1079 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1080 iio->ident.addr.ctype3_hdr.addrlen) 1081 goto send_mal_query; 1082 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1083 case ICMP_AFI_IP: 1084 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1085 goto send_mal_query; 1086 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1087 break; 1088 #if IS_ENABLED(CONFIG_IPV6) 1089 case ICMP_AFI_IP6: 1090 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1091 goto send_mal_query; 1092 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1093 dev_hold(dev); 1094 break; 1095 #endif 1096 default: 1097 goto send_mal_query; 1098 } 1099 break; 1100 default: 1101 goto send_mal_query; 1102 } 1103 if (!dev) { 1104 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1105 return true; 1106 } 1107 /* Fill bits in reply message */ 1108 if (dev->flags & IFF_UP) 1109 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1110 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1111 status |= ICMP_EXT_ECHOREPLY_IPV4; 1112 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1113 status |= ICMP_EXT_ECHOREPLY_IPV6; 1114 dev_put(dev); 1115 icmphdr->un.echo.sequence |= htons(status); 1116 return true; 1117 send_mal_query: 1118 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1119 return true; 1120 } 1121 EXPORT_SYMBOL_GPL(icmp_build_probe); 1122 1123 /* 1124 * Handle ICMP Timestamp requests. 1125 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1126 * SHOULD be in the kernel for minimum random latency. 1127 * MUST be accurate to a few minutes. 1128 * MUST be updated at least at 15Hz. 1129 */ 1130 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1131 { 1132 struct icmp_bxm icmp_param; 1133 /* 1134 * Too short. 1135 */ 1136 if (skb->len < 4) 1137 goto out_err; 1138 1139 /* 1140 * Fill in the current time as ms since midnight UT: 1141 */ 1142 icmp_param.data.times[1] = inet_current_timestamp(); 1143 icmp_param.data.times[2] = icmp_param.data.times[1]; 1144 1145 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1146 1147 icmp_param.data.icmph = *icmp_hdr(skb); 1148 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1149 icmp_param.data.icmph.code = 0; 1150 icmp_param.skb = skb; 1151 icmp_param.offset = 0; 1152 icmp_param.data_len = 0; 1153 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1154 icmp_reply(&icmp_param, skb); 1155 return SKB_NOT_DROPPED_YET; 1156 1157 out_err: 1158 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1159 return SKB_DROP_REASON_PKT_TOO_SMALL; 1160 } 1161 1162 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1163 { 1164 /* pretend it was a success */ 1165 return SKB_NOT_DROPPED_YET; 1166 } 1167 1168 /* 1169 * Deal with incoming ICMP packets. 1170 */ 1171 int icmp_rcv(struct sk_buff *skb) 1172 { 1173 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1174 struct rtable *rt = skb_rtable(skb); 1175 struct net *net = dev_net(rt->dst.dev); 1176 struct icmphdr *icmph; 1177 1178 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1179 struct sec_path *sp = skb_sec_path(skb); 1180 int nh; 1181 1182 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1183 XFRM_STATE_ICMP)) { 1184 reason = SKB_DROP_REASON_XFRM_POLICY; 1185 goto drop; 1186 } 1187 1188 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1189 goto drop; 1190 1191 nh = skb_network_offset(skb); 1192 skb_set_network_header(skb, sizeof(*icmph)); 1193 1194 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1195 skb)) { 1196 reason = SKB_DROP_REASON_XFRM_POLICY; 1197 goto drop; 1198 } 1199 1200 skb_set_network_header(skb, nh); 1201 } 1202 1203 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1204 1205 if (skb_checksum_simple_validate(skb)) 1206 goto csum_error; 1207 1208 if (!pskb_pull(skb, sizeof(*icmph))) 1209 goto error; 1210 1211 icmph = icmp_hdr(skb); 1212 1213 ICMPMSGIN_INC_STATS(net, icmph->type); 1214 1215 /* Check for ICMP Extended Echo (PROBE) messages */ 1216 if (icmph->type == ICMP_EXT_ECHO) { 1217 /* We can't use icmp_pointers[].handler() because it is an array of 1218 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1219 */ 1220 reason = icmp_echo(skb); 1221 goto reason_check; 1222 } 1223 1224 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1225 reason = ping_rcv(skb); 1226 goto reason_check; 1227 } 1228 1229 /* 1230 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1231 * 1232 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1233 * discarded. 1234 */ 1235 if (icmph->type > NR_ICMP_TYPES) { 1236 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1237 goto error; 1238 } 1239 1240 /* 1241 * Parse the ICMP message 1242 */ 1243 1244 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1245 /* 1246 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1247 * silently ignored (we let user decide with a sysctl). 1248 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1249 * discarded if to broadcast/multicast. 1250 */ 1251 if ((icmph->type == ICMP_ECHO || 1252 icmph->type == ICMP_TIMESTAMP) && 1253 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1254 reason = SKB_DROP_REASON_INVALID_PROTO; 1255 goto error; 1256 } 1257 if (icmph->type != ICMP_ECHO && 1258 icmph->type != ICMP_TIMESTAMP && 1259 icmph->type != ICMP_ADDRESS && 1260 icmph->type != ICMP_ADDRESSREPLY) { 1261 reason = SKB_DROP_REASON_INVALID_PROTO; 1262 goto error; 1263 } 1264 } 1265 1266 reason = icmp_pointers[icmph->type].handler(skb); 1267 reason_check: 1268 if (!reason) { 1269 consume_skb(skb); 1270 return NET_RX_SUCCESS; 1271 } 1272 1273 drop: 1274 kfree_skb_reason(skb, reason); 1275 return NET_RX_DROP; 1276 csum_error: 1277 reason = SKB_DROP_REASON_ICMP_CSUM; 1278 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1279 error: 1280 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1281 goto drop; 1282 } 1283 1284 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1285 { 1286 struct icmp_extobj_hdr *objh, _objh; 1287 struct icmp_ext_hdr *exth, _exth; 1288 u16 olen; 1289 1290 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1291 if (!exth) 1292 return false; 1293 if (exth->version != 2) 1294 return true; 1295 1296 if (exth->checksum && 1297 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1298 return false; 1299 1300 off += sizeof(_exth); 1301 while (off < skb->len) { 1302 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1303 if (!objh) 1304 return false; 1305 1306 olen = ntohs(objh->length); 1307 if (olen < sizeof(_objh)) 1308 return false; 1309 1310 off += olen; 1311 if (off > skb->len) 1312 return false; 1313 } 1314 1315 return true; 1316 } 1317 1318 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1319 struct sock_ee_data_rfc4884 *out, 1320 int thlen, int off) 1321 { 1322 int hlen; 1323 1324 /* original datagram headers: end of icmph to payload (skb->data) */ 1325 hlen = -skb_transport_offset(skb) - thlen; 1326 1327 /* per rfc 4884: minimal datagram length of 128 bytes */ 1328 if (off < 128 || off < hlen) 1329 return; 1330 1331 /* kernel has stripped headers: return payload offset in bytes */ 1332 off -= hlen; 1333 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1334 return; 1335 1336 out->len = off; 1337 1338 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1339 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1340 } 1341 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1342 1343 int icmp_err(struct sk_buff *skb, u32 info) 1344 { 1345 struct iphdr *iph = (struct iphdr *)skb->data; 1346 int offset = iph->ihl<<2; 1347 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1348 int type = icmp_hdr(skb)->type; 1349 int code = icmp_hdr(skb)->code; 1350 struct net *net = dev_net(skb->dev); 1351 1352 /* 1353 * Use ping_err to handle all icmp errors except those 1354 * triggered by ICMP_ECHOREPLY which sent from kernel. 1355 */ 1356 if (icmph->type != ICMP_ECHOREPLY) { 1357 ping_err(skb, offset, info); 1358 return 0; 1359 } 1360 1361 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1362 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1363 else if (type == ICMP_REDIRECT) 1364 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1365 1366 return 0; 1367 } 1368 1369 /* 1370 * This table is the definition of how we handle ICMP. 1371 */ 1372 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1373 [ICMP_ECHOREPLY] = { 1374 .handler = ping_rcv, 1375 }, 1376 [1] = { 1377 .handler = icmp_discard, 1378 .error = 1, 1379 }, 1380 [2] = { 1381 .handler = icmp_discard, 1382 .error = 1, 1383 }, 1384 [ICMP_DEST_UNREACH] = { 1385 .handler = icmp_unreach, 1386 .error = 1, 1387 }, 1388 [ICMP_SOURCE_QUENCH] = { 1389 .handler = icmp_unreach, 1390 .error = 1, 1391 }, 1392 [ICMP_REDIRECT] = { 1393 .handler = icmp_redirect, 1394 .error = 1, 1395 }, 1396 [6] = { 1397 .handler = icmp_discard, 1398 .error = 1, 1399 }, 1400 [7] = { 1401 .handler = icmp_discard, 1402 .error = 1, 1403 }, 1404 [ICMP_ECHO] = { 1405 .handler = icmp_echo, 1406 }, 1407 [9] = { 1408 .handler = icmp_discard, 1409 .error = 1, 1410 }, 1411 [10] = { 1412 .handler = icmp_discard, 1413 .error = 1, 1414 }, 1415 [ICMP_TIME_EXCEEDED] = { 1416 .handler = icmp_unreach, 1417 .error = 1, 1418 }, 1419 [ICMP_PARAMETERPROB] = { 1420 .handler = icmp_unreach, 1421 .error = 1, 1422 }, 1423 [ICMP_TIMESTAMP] = { 1424 .handler = icmp_timestamp, 1425 }, 1426 [ICMP_TIMESTAMPREPLY] = { 1427 .handler = icmp_discard, 1428 }, 1429 [ICMP_INFO_REQUEST] = { 1430 .handler = icmp_discard, 1431 }, 1432 [ICMP_INFO_REPLY] = { 1433 .handler = icmp_discard, 1434 }, 1435 [ICMP_ADDRESS] = { 1436 .handler = icmp_discard, 1437 }, 1438 [ICMP_ADDRESSREPLY] = { 1439 .handler = icmp_discard, 1440 }, 1441 }; 1442 1443 static int __net_init icmp_sk_init(struct net *net) 1444 { 1445 /* Control parameters for ECHO replies. */ 1446 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1447 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1448 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1449 1450 /* Control parameter - ignore bogus broadcast responses? */ 1451 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1452 1453 /* 1454 * Configurable global rate limit. 1455 * 1456 * ratelimit defines tokens/packet consumed for dst->rate_token 1457 * bucket ratemask defines which icmp types are ratelimited by 1458 * setting it's bit position. 1459 * 1460 * default: 1461 * dest unreachable (3), source quench (4), 1462 * time exceeded (11), parameter problem (12) 1463 */ 1464 1465 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1466 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1467 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1468 1469 return 0; 1470 } 1471 1472 static struct pernet_operations __net_initdata icmp_sk_ops = { 1473 .init = icmp_sk_init, 1474 }; 1475 1476 int __init icmp_init(void) 1477 { 1478 int err, i; 1479 1480 for_each_possible_cpu(i) { 1481 struct sock *sk; 1482 1483 err = inet_ctl_sock_create(&sk, PF_INET, 1484 SOCK_RAW, IPPROTO_ICMP, &init_net); 1485 if (err < 0) 1486 return err; 1487 1488 per_cpu(ipv4_icmp_sk, i) = sk; 1489 1490 /* Enough space for 2 64K ICMP packets, including 1491 * sk_buff/skb_shared_info struct overhead. 1492 */ 1493 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1494 1495 /* 1496 * Speedup sock_wfree() 1497 */ 1498 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1499 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1500 } 1501 return register_pernet_subsys(&icmp_sk_ops); 1502 } 1503