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 - get_random_u32_below(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 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 300 return false; 301 } 302 303 /* 304 * Send an ICMP frame. 305 */ 306 307 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 308 struct flowi4 *fl4, int type, int code) 309 { 310 struct dst_entry *dst = &rt->dst; 311 struct inet_peer *peer; 312 bool rc = true; 313 int vif; 314 315 if (icmpv4_mask_allow(net, type, code)) 316 goto out; 317 318 /* No rate limit on loopback */ 319 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) 320 goto out; 321 322 vif = l3mdev_master_ifindex(dst->dev); 323 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1); 324 rc = inet_peer_xrlim_allow(peer, 325 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 326 if (peer) 327 inet_putpeer(peer); 328 out: 329 if (!rc) 330 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 331 return rc; 332 } 333 334 /* 335 * Maintain the counters used in the SNMP statistics for outgoing ICMP 336 */ 337 void icmp_out_count(struct net *net, unsigned char type) 338 { 339 ICMPMSGOUT_INC_STATS(net, type); 340 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 341 } 342 343 /* 344 * Checksum each fragment, and on the first include the headers and final 345 * checksum. 346 */ 347 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 348 struct sk_buff *skb) 349 { 350 struct icmp_bxm *icmp_param = from; 351 __wsum csum; 352 353 csum = skb_copy_and_csum_bits(icmp_param->skb, 354 icmp_param->offset + offset, 355 to, len); 356 357 skb->csum = csum_block_add(skb->csum, csum, odd); 358 if (icmp_pointers[icmp_param->data.icmph.type].error) 359 nf_ct_attach(skb, icmp_param->skb); 360 return 0; 361 } 362 363 static void icmp_push_reply(struct sock *sk, 364 struct icmp_bxm *icmp_param, 365 struct flowi4 *fl4, 366 struct ipcm_cookie *ipc, struct rtable **rt) 367 { 368 struct sk_buff *skb; 369 370 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; 379 struct sk_buff *skb1; 380 381 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 382 (char *)icmph, 383 icmp_param->head_len); 384 skb_queue_walk(&sk->sk_write_queue, skb1) { 385 csum = csum_add(csum, skb1->csum); 386 } 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 ipc.sockc.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_common(&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(sk, 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 /* 460 * The device used for looking up which routing table to use for sending an ICMP 461 * error is preferably the source whenever it is set, which should ensure the 462 * icmp error can be sent to the source host, else lookup using the routing 463 * table of the destination device, else use the main routing table (index 0). 464 */ 465 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 466 { 467 struct net_device *route_lookup_dev = NULL; 468 469 if (skb->dev) 470 route_lookup_dev = skb->dev; 471 else if (skb_dst(skb)) 472 route_lookup_dev = skb_dst(skb)->dev; 473 return route_lookup_dev; 474 } 475 476 static struct rtable *icmp_route_lookup(struct net *net, 477 struct flowi4 *fl4, 478 struct sk_buff *skb_in, 479 const struct iphdr *iph, 480 __be32 saddr, u8 tos, u32 mark, 481 int type, int code, 482 struct icmp_bxm *param) 483 { 484 struct net_device *route_lookup_dev; 485 struct rtable *rt, *rt2; 486 struct flowi4 fl4_dec; 487 int err; 488 489 memset(fl4, 0, sizeof(*fl4)); 490 fl4->daddr = (param->replyopts.opt.opt.srr ? 491 param->replyopts.opt.opt.faddr : iph->saddr); 492 fl4->saddr = saddr; 493 fl4->flowi4_mark = mark; 494 fl4->flowi4_uid = sock_net_uid(net, NULL); 495 fl4->flowi4_tos = RT_TOS(tos); 496 fl4->flowi4_proto = IPPROTO_ICMP; 497 fl4->fl4_icmp_type = type; 498 fl4->fl4_icmp_code = code; 499 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 500 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 501 502 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 503 rt = ip_route_output_key_hash(net, fl4, skb_in); 504 if (IS_ERR(rt)) 505 return rt; 506 507 /* No need to clone since we're just using its address. */ 508 rt2 = rt; 509 510 rt = (struct rtable *) xfrm_lookup(net, &rt->dst, 511 flowi4_to_flowi(fl4), NULL, 0); 512 if (!IS_ERR(rt)) { 513 if (rt != rt2) 514 return rt; 515 } else if (PTR_ERR(rt) == -EPERM) { 516 rt = NULL; 517 } else 518 return rt; 519 520 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 521 if (err) 522 goto relookup_failed; 523 524 if (inet_addr_type_dev_table(net, route_lookup_dev, 525 fl4_dec.saddr) == RTN_LOCAL) { 526 rt2 = __ip_route_output_key(net, &fl4_dec); 527 if (IS_ERR(rt2)) 528 err = PTR_ERR(rt2); 529 } else { 530 struct flowi4 fl4_2 = {}; 531 unsigned long orefdst; 532 533 fl4_2.daddr = fl4_dec.saddr; 534 rt2 = ip_route_output_key(net, &fl4_2); 535 if (IS_ERR(rt2)) { 536 err = PTR_ERR(rt2); 537 goto relookup_failed; 538 } 539 /* Ugh! */ 540 orefdst = skb_in->_skb_refdst; /* save old refdst */ 541 skb_dst_set(skb_in, NULL); 542 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 543 RT_TOS(tos), rt2->dst.dev); 544 545 dst_release(&rt2->dst); 546 rt2 = skb_rtable(skb_in); 547 skb_in->_skb_refdst = orefdst; /* restore old refdst */ 548 } 549 550 if (err) 551 goto relookup_failed; 552 553 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, 554 flowi4_to_flowi(&fl4_dec), NULL, 555 XFRM_LOOKUP_ICMP); 556 if (!IS_ERR(rt2)) { 557 dst_release(&rt->dst); 558 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 559 rt = rt2; 560 } else if (PTR_ERR(rt2) == -EPERM) { 561 if (rt) 562 dst_release(&rt->dst); 563 return rt2; 564 } else { 565 err = PTR_ERR(rt2); 566 goto relookup_failed; 567 } 568 return rt; 569 570 relookup_failed: 571 if (rt) 572 return rt; 573 return ERR_PTR(err); 574 } 575 576 /* 577 * Send an ICMP message in response to a situation 578 * 579 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 580 * MAY send more (we do). 581 * MUST NOT change this header information. 582 * MUST NOT reply to a multicast/broadcast IP address. 583 * MUST NOT reply to a multicast/broadcast MAC address. 584 * MUST reply to only the first fragment. 585 */ 586 587 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 588 const struct ip_options *opt) 589 { 590 struct iphdr *iph; 591 int room; 592 struct icmp_bxm icmp_param; 593 struct rtable *rt = skb_rtable(skb_in); 594 struct ipcm_cookie ipc; 595 struct flowi4 fl4; 596 __be32 saddr; 597 u8 tos; 598 u32 mark; 599 struct net *net; 600 struct sock *sk; 601 602 if (!rt) 603 goto out; 604 605 if (rt->dst.dev) 606 net = dev_net(rt->dst.dev); 607 else if (skb_in->dev) 608 net = dev_net(skb_in->dev); 609 else 610 goto out; 611 612 /* 613 * Find the original header. It is expected to be valid, of course. 614 * Check this, icmp_send is called from the most obscure devices 615 * sometimes. 616 */ 617 iph = ip_hdr(skb_in); 618 619 if ((u8 *)iph < skb_in->head || 620 (skb_network_header(skb_in) + sizeof(*iph)) > 621 skb_tail_pointer(skb_in)) 622 goto out; 623 624 /* 625 * No replies to physical multicast/broadcast 626 */ 627 if (skb_in->pkt_type != PACKET_HOST) 628 goto out; 629 630 /* 631 * Now check at the protocol level 632 */ 633 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 634 goto out; 635 636 /* 637 * Only reply to fragment 0. We byte re-order the constant 638 * mask for efficiency. 639 */ 640 if (iph->frag_off & htons(IP_OFFSET)) 641 goto out; 642 643 /* 644 * If we send an ICMP error to an ICMP error a mess would result.. 645 */ 646 if (icmp_pointers[type].error) { 647 /* 648 * We are an error, check if we are replying to an 649 * ICMP error 650 */ 651 if (iph->protocol == IPPROTO_ICMP) { 652 u8 _inner_type, *itp; 653 654 itp = skb_header_pointer(skb_in, 655 skb_network_header(skb_in) + 656 (iph->ihl << 2) + 657 offsetof(struct icmphdr, 658 type) - 659 skb_in->data, 660 sizeof(_inner_type), 661 &_inner_type); 662 if (!itp) 663 goto out; 664 665 /* 666 * Assume any unknown ICMP type is an error. This 667 * isn't specified by the RFC, but think about it.. 668 */ 669 if (*itp > NR_ICMP_TYPES || 670 icmp_pointers[*itp].error) 671 goto out; 672 } 673 } 674 675 /* Needed by both icmp_global_allow and icmp_xmit_lock */ 676 local_bh_disable(); 677 678 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 679 * incoming dev is loopback. If outgoing dev change to not be 680 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 681 */ 682 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 683 !icmpv4_global_allow(net, type, code)) 684 goto out_bh_enable; 685 686 sk = icmp_xmit_lock(net); 687 if (!sk) 688 goto out_bh_enable; 689 690 /* 691 * Construct source address and options. 692 */ 693 694 saddr = iph->daddr; 695 if (!(rt->rt_flags & RTCF_LOCAL)) { 696 struct net_device *dev = NULL; 697 698 rcu_read_lock(); 699 if (rt_is_input_route(rt) && 700 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 701 dev = dev_get_by_index_rcu(net, inet_iif(skb_in)); 702 703 if (dev) 704 saddr = inet_select_addr(dev, iph->saddr, 705 RT_SCOPE_LINK); 706 else 707 saddr = 0; 708 rcu_read_unlock(); 709 } 710 711 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 712 IPTOS_PREC_INTERNETCONTROL) : 713 iph->tos; 714 mark = IP4_REPLY_MARK(net, skb_in->mark); 715 716 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt)) 717 goto out_unlock; 718 719 720 /* 721 * Prepare data for ICMP header. 722 */ 723 724 icmp_param.data.icmph.type = type; 725 icmp_param.data.icmph.code = code; 726 icmp_param.data.icmph.un.gateway = info; 727 icmp_param.data.icmph.checksum = 0; 728 icmp_param.skb = skb_in; 729 icmp_param.offset = skb_network_offset(skb_in); 730 inet_sk(sk)->tos = tos; 731 ipcm_init(&ipc); 732 ipc.addr = iph->saddr; 733 ipc.opt = &icmp_param.replyopts.opt; 734 ipc.sockc.mark = mark; 735 736 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, 737 type, code, &icmp_param); 738 if (IS_ERR(rt)) 739 goto out_unlock; 740 741 /* peer icmp_ratelimit */ 742 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code)) 743 goto ende; 744 745 /* RFC says return as much as we can without exceeding 576 bytes. */ 746 747 room = dst_mtu(&rt->dst); 748 if (room > 576) 749 room = 576; 750 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 751 room -= sizeof(struct icmphdr); 752 753 icmp_param.data_len = skb_in->len - icmp_param.offset; 754 if (icmp_param.data_len > room) 755 icmp_param.data_len = room; 756 icmp_param.head_len = sizeof(struct icmphdr); 757 758 /* if we don't have a source address at this point, fall back to the 759 * dummy address instead of sending out a packet with a source address 760 * of 0.0.0.0 761 */ 762 if (!fl4.saddr) 763 fl4.saddr = htonl(INADDR_DUMMY); 764 765 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 766 ende: 767 ip_rt_put(rt); 768 out_unlock: 769 icmp_xmit_unlock(sk); 770 out_bh_enable: 771 local_bh_enable(); 772 out:; 773 } 774 EXPORT_SYMBOL(__icmp_send); 775 776 #if IS_ENABLED(CONFIG_NF_NAT) 777 #include <net/netfilter/nf_conntrack.h> 778 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 779 { 780 struct sk_buff *cloned_skb = NULL; 781 struct ip_options opts = { 0 }; 782 enum ip_conntrack_info ctinfo; 783 struct nf_conn *ct; 784 __be32 orig_ip; 785 786 ct = nf_ct_get(skb_in, &ctinfo); 787 if (!ct || !(ct->status & IPS_SRC_NAT)) { 788 __icmp_send(skb_in, type, code, info, &opts); 789 return; 790 } 791 792 if (skb_shared(skb_in)) 793 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 794 795 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 796 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 797 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 798 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 799 goto out; 800 801 orig_ip = ip_hdr(skb_in)->saddr; 802 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; 803 __icmp_send(skb_in, type, code, info, &opts); 804 ip_hdr(skb_in)->saddr = orig_ip; 805 out: 806 consume_skb(cloned_skb); 807 } 808 EXPORT_SYMBOL(icmp_ndo_send); 809 #endif 810 811 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 812 { 813 const struct iphdr *iph = (const struct iphdr *)skb->data; 814 const struct net_protocol *ipprot; 815 int protocol = iph->protocol; 816 817 /* Checkin full IP header plus 8 bytes of protocol to 818 * avoid additional coding at protocol handlers. 819 */ 820 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 821 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 822 return; 823 } 824 825 raw_icmp_error(skb, protocol, info); 826 827 ipprot = rcu_dereference(inet_protos[protocol]); 828 if (ipprot && ipprot->err_handler) 829 ipprot->err_handler(skb, info); 830 } 831 832 static bool icmp_tag_validation(int proto) 833 { 834 bool ok; 835 836 rcu_read_lock(); 837 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 838 rcu_read_unlock(); 839 return ok; 840 } 841 842 /* 843 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 844 * ICMP_PARAMETERPROB. 845 */ 846 847 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 848 { 849 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 850 const struct iphdr *iph; 851 struct icmphdr *icmph; 852 struct net *net; 853 u32 info = 0; 854 855 net = dev_net(skb_dst(skb)->dev); 856 857 /* 858 * Incomplete header ? 859 * Only checks for the IP header, there should be an 860 * additional check for longer headers in upper levels. 861 */ 862 863 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 864 goto out_err; 865 866 icmph = icmp_hdr(skb); 867 iph = (const struct iphdr *)skb->data; 868 869 if (iph->ihl < 5) { /* Mangled header, drop. */ 870 reason = SKB_DROP_REASON_IP_INHDR; 871 goto out_err; 872 } 873 874 switch (icmph->type) { 875 case ICMP_DEST_UNREACH: 876 switch (icmph->code & 15) { 877 case ICMP_NET_UNREACH: 878 case ICMP_HOST_UNREACH: 879 case ICMP_PROT_UNREACH: 880 case ICMP_PORT_UNREACH: 881 break; 882 case ICMP_FRAG_NEEDED: 883 /* for documentation of the ip_no_pmtu_disc 884 * values please see 885 * Documentation/networking/ip-sysctl.rst 886 */ 887 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 888 default: 889 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 890 &iph->daddr); 891 break; 892 case 2: 893 goto out; 894 case 3: 895 if (!icmp_tag_validation(iph->protocol)) 896 goto out; 897 fallthrough; 898 case 0: 899 info = ntohs(icmph->un.frag.mtu); 900 } 901 break; 902 case ICMP_SR_FAILED: 903 net_dbg_ratelimited("%pI4: Source Route Failed\n", 904 &iph->daddr); 905 break; 906 default: 907 break; 908 } 909 if (icmph->code > NR_ICMP_UNREACH) 910 goto out; 911 break; 912 case ICMP_PARAMETERPROB: 913 info = ntohl(icmph->un.gateway) >> 24; 914 break; 915 case ICMP_TIME_EXCEEDED: 916 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 917 if (icmph->code == ICMP_EXC_FRAGTIME) 918 goto out; 919 break; 920 } 921 922 /* 923 * Throw it at our lower layers 924 * 925 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 926 * header. 927 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 928 * transport layer. 929 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 930 * transport layer. 931 */ 932 933 /* 934 * Check the other end isn't violating RFC 1122. Some routers send 935 * bogus responses to broadcast frames. If you see this message 936 * first check your netmask matches at both ends, if it does then 937 * get the other vendor to fix their kit. 938 */ 939 940 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 941 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 942 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 943 &ip_hdr(skb)->saddr, 944 icmph->type, icmph->code, 945 &iph->daddr, skb->dev->name); 946 goto out; 947 } 948 949 icmp_socket_deliver(skb, info); 950 951 out: 952 return reason; 953 out_err: 954 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 955 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 956 } 957 958 959 /* 960 * Handle ICMP_REDIRECT. 961 */ 962 963 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 964 { 965 if (skb->len < sizeof(struct iphdr)) { 966 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); 967 return SKB_DROP_REASON_PKT_TOO_SMALL; 968 } 969 970 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 971 /* there aught to be a stat */ 972 return SKB_DROP_REASON_NOMEM; 973 } 974 975 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 976 return SKB_NOT_DROPPED_YET; 977 } 978 979 /* 980 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 981 * 982 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 983 * requests. 984 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 985 * included in the reply. 986 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 987 * echo requests, MUST have default=NOT. 988 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 989 * Extended Echo Functionality, MUST be disabled by default 990 * See also WRT handling of options once they are done and working. 991 */ 992 993 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 994 { 995 struct icmp_bxm icmp_param; 996 struct net *net; 997 998 net = dev_net(skb_dst(skb)->dev); 999 /* should there be an ICMP stat for ignored echos? */ 1000 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1001 return SKB_NOT_DROPPED_YET; 1002 1003 icmp_param.data.icmph = *icmp_hdr(skb); 1004 icmp_param.skb = skb; 1005 icmp_param.offset = 0; 1006 icmp_param.data_len = skb->len; 1007 icmp_param.head_len = sizeof(struct icmphdr); 1008 1009 if (icmp_param.data.icmph.type == ICMP_ECHO) 1010 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1011 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1012 return SKB_NOT_DROPPED_YET; 1013 1014 icmp_reply(&icmp_param, skb); 1015 return SKB_NOT_DROPPED_YET; 1016 } 1017 1018 /* Helper for icmp_echo and icmpv6_echo_reply. 1019 * Searches for net_device that matches PROBE interface identifier 1020 * and builds PROBE reply message in icmphdr. 1021 * 1022 * Returns false if PROBE responses are disabled via sysctl 1023 */ 1024 1025 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1026 { 1027 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1028 struct icmp_ext_echo_iio *iio, _iio; 1029 struct net *net = dev_net(skb->dev); 1030 struct net_device *dev; 1031 char buff[IFNAMSIZ]; 1032 u16 ident_len; 1033 u8 status; 1034 1035 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1036 return false; 1037 1038 /* We currently only support probing interfaces on the proxy node 1039 * Check to ensure L-bit is set 1040 */ 1041 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1042 return false; 1043 /* Clear status bits in reply message */ 1044 icmphdr->un.echo.sequence &= htons(0xFF00); 1045 if (icmphdr->type == ICMP_EXT_ECHO) 1046 icmphdr->type = ICMP_EXT_ECHOREPLY; 1047 else 1048 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1049 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1050 /* Size of iio is class_type dependent. 1051 * Only check header here and assign length based on ctype in the switch statement 1052 */ 1053 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1054 if (!ext_hdr || !iio) 1055 goto send_mal_query; 1056 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1057 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1058 goto send_mal_query; 1059 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1060 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1061 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1062 if (!iio) 1063 goto send_mal_query; 1064 1065 status = 0; 1066 dev = NULL; 1067 switch (iio->extobj_hdr.class_type) { 1068 case ICMP_EXT_ECHO_CTYPE_NAME: 1069 if (ident_len >= IFNAMSIZ) 1070 goto send_mal_query; 1071 memset(buff, 0, sizeof(buff)); 1072 memcpy(buff, &iio->ident.name, ident_len); 1073 dev = dev_get_by_name(net, buff); 1074 break; 1075 case ICMP_EXT_ECHO_CTYPE_INDEX: 1076 if (ident_len != sizeof(iio->ident.ifindex)) 1077 goto send_mal_query; 1078 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1079 break; 1080 case ICMP_EXT_ECHO_CTYPE_ADDR: 1081 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1082 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1083 iio->ident.addr.ctype3_hdr.addrlen) 1084 goto send_mal_query; 1085 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1086 case ICMP_AFI_IP: 1087 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1088 goto send_mal_query; 1089 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1090 break; 1091 #if IS_ENABLED(CONFIG_IPV6) 1092 case ICMP_AFI_IP6: 1093 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1094 goto send_mal_query; 1095 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1096 dev_hold(dev); 1097 break; 1098 #endif 1099 default: 1100 goto send_mal_query; 1101 } 1102 break; 1103 default: 1104 goto send_mal_query; 1105 } 1106 if (!dev) { 1107 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1108 return true; 1109 } 1110 /* Fill bits in reply message */ 1111 if (dev->flags & IFF_UP) 1112 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1113 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) 1114 status |= ICMP_EXT_ECHOREPLY_IPV4; 1115 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) 1116 status |= ICMP_EXT_ECHOREPLY_IPV6; 1117 dev_put(dev); 1118 icmphdr->un.echo.sequence |= htons(status); 1119 return true; 1120 send_mal_query: 1121 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1122 return true; 1123 } 1124 EXPORT_SYMBOL_GPL(icmp_build_probe); 1125 1126 /* 1127 * Handle ICMP Timestamp requests. 1128 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1129 * SHOULD be in the kernel for minimum random latency. 1130 * MUST be accurate to a few minutes. 1131 * MUST be updated at least at 15Hz. 1132 */ 1133 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1134 { 1135 struct icmp_bxm icmp_param; 1136 /* 1137 * Too short. 1138 */ 1139 if (skb->len < 4) 1140 goto out_err; 1141 1142 /* 1143 * Fill in the current time as ms since midnight UT: 1144 */ 1145 icmp_param.data.times[1] = inet_current_timestamp(); 1146 icmp_param.data.times[2] = icmp_param.data.times[1]; 1147 1148 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1149 1150 icmp_param.data.icmph = *icmp_hdr(skb); 1151 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1152 icmp_param.data.icmph.code = 0; 1153 icmp_param.skb = skb; 1154 icmp_param.offset = 0; 1155 icmp_param.data_len = 0; 1156 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1157 icmp_reply(&icmp_param, skb); 1158 return SKB_NOT_DROPPED_YET; 1159 1160 out_err: 1161 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); 1162 return SKB_DROP_REASON_PKT_TOO_SMALL; 1163 } 1164 1165 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1166 { 1167 /* pretend it was a success */ 1168 return SKB_NOT_DROPPED_YET; 1169 } 1170 1171 /* 1172 * Deal with incoming ICMP packets. 1173 */ 1174 int icmp_rcv(struct sk_buff *skb) 1175 { 1176 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1177 struct rtable *rt = skb_rtable(skb); 1178 struct net *net = dev_net(rt->dst.dev); 1179 struct icmphdr *icmph; 1180 1181 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1182 struct sec_path *sp = skb_sec_path(skb); 1183 int nh; 1184 1185 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1186 XFRM_STATE_ICMP)) { 1187 reason = SKB_DROP_REASON_XFRM_POLICY; 1188 goto drop; 1189 } 1190 1191 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1192 goto drop; 1193 1194 nh = skb_network_offset(skb); 1195 skb_set_network_header(skb, sizeof(*icmph)); 1196 1197 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1198 skb)) { 1199 reason = SKB_DROP_REASON_XFRM_POLICY; 1200 goto drop; 1201 } 1202 1203 skb_set_network_header(skb, nh); 1204 } 1205 1206 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1207 1208 if (skb_checksum_simple_validate(skb)) 1209 goto csum_error; 1210 1211 if (!pskb_pull(skb, sizeof(*icmph))) 1212 goto error; 1213 1214 icmph = icmp_hdr(skb); 1215 1216 ICMPMSGIN_INC_STATS(net, icmph->type); 1217 1218 /* Check for ICMP Extended Echo (PROBE) messages */ 1219 if (icmph->type == ICMP_EXT_ECHO) { 1220 /* We can't use icmp_pointers[].handler() because it is an array of 1221 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1222 */ 1223 reason = icmp_echo(skb); 1224 goto reason_check; 1225 } 1226 1227 if (icmph->type == ICMP_EXT_ECHOREPLY) { 1228 reason = ping_rcv(skb); 1229 goto reason_check; 1230 } 1231 1232 /* 1233 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1234 * 1235 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1236 * discarded. 1237 */ 1238 if (icmph->type > NR_ICMP_TYPES) { 1239 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1240 goto error; 1241 } 1242 1243 /* 1244 * Parse the ICMP message 1245 */ 1246 1247 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1248 /* 1249 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1250 * silently ignored (we let user decide with a sysctl). 1251 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1252 * discarded if to broadcast/multicast. 1253 */ 1254 if ((icmph->type == ICMP_ECHO || 1255 icmph->type == ICMP_TIMESTAMP) && 1256 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1257 reason = SKB_DROP_REASON_INVALID_PROTO; 1258 goto error; 1259 } 1260 if (icmph->type != ICMP_ECHO && 1261 icmph->type != ICMP_TIMESTAMP && 1262 icmph->type != ICMP_ADDRESS && 1263 icmph->type != ICMP_ADDRESSREPLY) { 1264 reason = SKB_DROP_REASON_INVALID_PROTO; 1265 goto error; 1266 } 1267 } 1268 1269 reason = icmp_pointers[icmph->type].handler(skb); 1270 reason_check: 1271 if (!reason) { 1272 consume_skb(skb); 1273 return NET_RX_SUCCESS; 1274 } 1275 1276 drop: 1277 kfree_skb_reason(skb, reason); 1278 return NET_RX_DROP; 1279 csum_error: 1280 reason = SKB_DROP_REASON_ICMP_CSUM; 1281 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1282 error: 1283 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1284 goto drop; 1285 } 1286 1287 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1288 { 1289 struct icmp_extobj_hdr *objh, _objh; 1290 struct icmp_ext_hdr *exth, _exth; 1291 u16 olen; 1292 1293 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1294 if (!exth) 1295 return false; 1296 if (exth->version != 2) 1297 return true; 1298 1299 if (exth->checksum && 1300 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1301 return false; 1302 1303 off += sizeof(_exth); 1304 while (off < skb->len) { 1305 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1306 if (!objh) 1307 return false; 1308 1309 olen = ntohs(objh->length); 1310 if (olen < sizeof(_objh)) 1311 return false; 1312 1313 off += olen; 1314 if (off > skb->len) 1315 return false; 1316 } 1317 1318 return true; 1319 } 1320 1321 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1322 struct sock_ee_data_rfc4884 *out, 1323 int thlen, int off) 1324 { 1325 int hlen; 1326 1327 /* original datagram headers: end of icmph to payload (skb->data) */ 1328 hlen = -skb_transport_offset(skb) - thlen; 1329 1330 /* per rfc 4884: minimal datagram length of 128 bytes */ 1331 if (off < 128 || off < hlen) 1332 return; 1333 1334 /* kernel has stripped headers: return payload offset in bytes */ 1335 off -= hlen; 1336 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1337 return; 1338 1339 out->len = off; 1340 1341 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1342 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1343 } 1344 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1345 1346 int icmp_err(struct sk_buff *skb, u32 info) 1347 { 1348 struct iphdr *iph = (struct iphdr *)skb->data; 1349 int offset = iph->ihl<<2; 1350 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1351 int type = icmp_hdr(skb)->type; 1352 int code = icmp_hdr(skb)->code; 1353 struct net *net = dev_net(skb->dev); 1354 1355 /* 1356 * Use ping_err to handle all icmp errors except those 1357 * triggered by ICMP_ECHOREPLY which sent from kernel. 1358 */ 1359 if (icmph->type != ICMP_ECHOREPLY) { 1360 ping_err(skb, offset, info); 1361 return 0; 1362 } 1363 1364 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1365 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1366 else if (type == ICMP_REDIRECT) 1367 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1368 1369 return 0; 1370 } 1371 1372 /* 1373 * This table is the definition of how we handle ICMP. 1374 */ 1375 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1376 [ICMP_ECHOREPLY] = { 1377 .handler = ping_rcv, 1378 }, 1379 [1] = { 1380 .handler = icmp_discard, 1381 .error = 1, 1382 }, 1383 [2] = { 1384 .handler = icmp_discard, 1385 .error = 1, 1386 }, 1387 [ICMP_DEST_UNREACH] = { 1388 .handler = icmp_unreach, 1389 .error = 1, 1390 }, 1391 [ICMP_SOURCE_QUENCH] = { 1392 .handler = icmp_unreach, 1393 .error = 1, 1394 }, 1395 [ICMP_REDIRECT] = { 1396 .handler = icmp_redirect, 1397 .error = 1, 1398 }, 1399 [6] = { 1400 .handler = icmp_discard, 1401 .error = 1, 1402 }, 1403 [7] = { 1404 .handler = icmp_discard, 1405 .error = 1, 1406 }, 1407 [ICMP_ECHO] = { 1408 .handler = icmp_echo, 1409 }, 1410 [9] = { 1411 .handler = icmp_discard, 1412 .error = 1, 1413 }, 1414 [10] = { 1415 .handler = icmp_discard, 1416 .error = 1, 1417 }, 1418 [ICMP_TIME_EXCEEDED] = { 1419 .handler = icmp_unreach, 1420 .error = 1, 1421 }, 1422 [ICMP_PARAMETERPROB] = { 1423 .handler = icmp_unreach, 1424 .error = 1, 1425 }, 1426 [ICMP_TIMESTAMP] = { 1427 .handler = icmp_timestamp, 1428 }, 1429 [ICMP_TIMESTAMPREPLY] = { 1430 .handler = icmp_discard, 1431 }, 1432 [ICMP_INFO_REQUEST] = { 1433 .handler = icmp_discard, 1434 }, 1435 [ICMP_INFO_REPLY] = { 1436 .handler = icmp_discard, 1437 }, 1438 [ICMP_ADDRESS] = { 1439 .handler = icmp_discard, 1440 }, 1441 [ICMP_ADDRESSREPLY] = { 1442 .handler = icmp_discard, 1443 }, 1444 }; 1445 1446 static int __net_init icmp_sk_init(struct net *net) 1447 { 1448 /* Control parameters for ECHO replies. */ 1449 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1450 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1451 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1452 1453 /* Control parameter - ignore bogus broadcast responses? */ 1454 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1455 1456 /* 1457 * Configurable global rate limit. 1458 * 1459 * ratelimit defines tokens/packet consumed for dst->rate_token 1460 * bucket ratemask defines which icmp types are ratelimited by 1461 * setting it's bit position. 1462 * 1463 * default: 1464 * dest unreachable (3), source quench (4), 1465 * time exceeded (11), parameter problem (12) 1466 */ 1467 1468 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1469 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1470 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1471 1472 return 0; 1473 } 1474 1475 static struct pernet_operations __net_initdata icmp_sk_ops = { 1476 .init = icmp_sk_init, 1477 }; 1478 1479 int __init icmp_init(void) 1480 { 1481 int err, i; 1482 1483 for_each_possible_cpu(i) { 1484 struct sock *sk; 1485 1486 err = inet_ctl_sock_create(&sk, PF_INET, 1487 SOCK_RAW, IPPROTO_ICMP, &init_net); 1488 if (err < 0) 1489 return err; 1490 1491 per_cpu(ipv4_icmp_sk, i) = sk; 1492 1493 /* Enough space for 2 64K ICMP packets, including 1494 * sk_buff/skb_shared_info struct overhead. 1495 */ 1496 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1497 1498 /* 1499 * Speedup sock_wfree() 1500 */ 1501 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1502 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1503 } 1504 return register_pernet_subsys(&icmp_sk_ops); 1505 } 1506