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/flow.h> 76 #include <net/snmp.h> 77 #include <net/ip.h> 78 #include <net/route.h> 79 #include <net/protocol.h> 80 #include <net/icmp.h> 81 #include <net/tcp.h> 82 #include <net/udp.h> 83 #include <net/raw.h> 84 #include <net/ping.h> 85 #include <linux/skbuff.h> 86 #include <net/sock.h> 87 #include <linux/errno.h> 88 #include <linux/timer.h> 89 #include <linux/init.h> 90 #include <linux/uaccess.h> 91 #include <net/checksum.h> 92 #include <net/xfrm.h> 93 #include <net/inet_common.h> 94 #include <net/ip_fib.h> 95 #include <net/l3mdev.h> 96 #include <net/addrconf.h> 97 #include <net/inet_dscp.h> 98 #define CREATE_TRACE_POINTS 99 #include <trace/events/icmp.h> 100 101 /* 102 * Build xmit assembly blocks 103 */ 104 105 struct icmp_bxm { 106 struct sk_buff *skb; 107 int offset; 108 int data_len; 109 110 struct { 111 struct icmphdr icmph; 112 __be32 times[3]; 113 } data; 114 int head_len; 115 struct ip_options_data replyopts; 116 }; 117 118 /* An array of errno for error messages from dest unreach. */ 119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 120 121 const struct icmp_err icmp_err_convert[] = { 122 { 123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 124 .fatal = 0, 125 }, 126 { 127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 128 .fatal = 0, 129 }, 130 { 131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 132 .fatal = 1, 133 }, 134 { 135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 136 .fatal = 1, 137 }, 138 { 139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 140 .fatal = 0, 141 }, 142 { 143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 144 .fatal = 0, 145 }, 146 { 147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 148 .fatal = 1, 149 }, 150 { 151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 152 .fatal = 1, 153 }, 154 { 155 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 156 .fatal = 1, 157 }, 158 { 159 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 160 .fatal = 1, 161 }, 162 { 163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 164 .fatal = 1, 165 }, 166 { 167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 168 .fatal = 0, 169 }, 170 { 171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 172 .fatal = 0, 173 }, 174 { 175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 176 .fatal = 1, 177 }, 178 { 179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 180 .fatal = 1, 181 }, 182 { 183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 184 .fatal = 1, 185 }, 186 }; 187 EXPORT_SYMBOL(icmp_err_convert); 188 189 /* 190 * ICMP control array. This specifies what to do with each ICMP. 191 */ 192 193 struct icmp_control { 194 enum skb_drop_reason (*handler)(struct sk_buff *skb); 195 short error; /* This ICMP is classed as an error message */ 196 }; 197 198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 199 200 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 201 202 /* Called with BH disabled */ 203 static inline struct sock *icmp_xmit_lock(struct net *net) 204 { 205 struct sock *sk; 206 207 sk = this_cpu_read(ipv4_icmp_sk); 208 209 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 210 /* This can happen if the output path signals a 211 * dst_link_failure() for an outgoing ICMP packet. 212 */ 213 return NULL; 214 } 215 sock_net_set(sk, net); 216 return sk; 217 } 218 219 static inline void icmp_xmit_unlock(struct sock *sk) 220 { 221 sock_net_set(sk, &init_net); 222 spin_unlock(&sk->sk_lock.slock); 223 } 224 225 /** 226 * icmp_global_allow - Are we allowed to send one more ICMP message ? 227 * @net: network namespace 228 * 229 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 230 * Returns false if we reached the limit and can not send another packet. 231 * Works in tandem with icmp_global_consume(). 232 */ 233 bool icmp_global_allow(struct net *net) 234 { 235 u32 delta, now, oldstamp; 236 int incr, new, old; 237 238 /* Note: many cpus could find this condition true. 239 * Then later icmp_global_consume() could consume more credits, 240 * this is an acceptable race. 241 */ 242 if (atomic_read(&net->ipv4.icmp_global_credit) > 0) 243 return true; 244 245 now = jiffies; 246 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); 247 delta = min_t(u32, now - oldstamp, HZ); 248 if (delta < HZ / 50) 249 return false; 250 251 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ; 252 if (!incr) 253 return false; 254 255 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 256 old = atomic_read(&net->ipv4.icmp_global_credit); 257 do { 258 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 259 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 260 } 261 return true; 262 } 263 EXPORT_SYMBOL(icmp_global_allow); 264 265 void icmp_global_consume(struct net *net) 266 { 267 int credits = get_random_u32_below(3); 268 269 /* Note: this might make icmp_global.credit negative. */ 270 if (credits) 271 atomic_sub(credits, &net->ipv4.icmp_global_credit); 272 } 273 EXPORT_SYMBOL(icmp_global_consume); 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 bool *apply_ratelimit) 293 { 294 if (icmpv4_mask_allow(net, type, code)) 295 return true; 296 297 if (icmp_global_allow(net)) { 298 *apply_ratelimit = true; 299 return true; 300 } 301 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 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 bool apply_ratelimit) 312 { 313 struct dst_entry *dst = &rt->dst; 314 struct inet_peer *peer; 315 struct net_device *dev; 316 bool rc = true; 317 318 if (!apply_ratelimit) 319 return true; 320 321 /* No rate limit on loopback */ 322 rcu_read_lock(); 323 dev = dst_dev_rcu(dst); 324 if (dev && (dev->flags & IFF_LOOPBACK)) 325 goto out; 326 327 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 328 l3mdev_master_ifindex_rcu(dev)); 329 rc = inet_peer_xrlim_allow(peer, 330 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 331 out: 332 rcu_read_unlock(); 333 if (!rc) 334 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 335 else 336 icmp_global_consume(net); 337 return rc; 338 } 339 340 /* 341 * Maintain the counters used in the SNMP statistics for outgoing ICMP 342 */ 343 void icmp_out_count(struct net *net, unsigned char type) 344 { 345 ICMPMSGOUT_INC_STATS(net, type); 346 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 347 } 348 349 /* 350 * Checksum each fragment, and on the first include the headers and final 351 * checksum. 352 */ 353 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 354 struct sk_buff *skb) 355 { 356 struct icmp_bxm *icmp_param = from; 357 __wsum csum; 358 359 csum = skb_copy_and_csum_bits(icmp_param->skb, 360 icmp_param->offset + offset, 361 to, len); 362 363 skb->csum = csum_block_add(skb->csum, csum, odd); 364 if (icmp_pointers[icmp_param->data.icmph.type].error) 365 nf_ct_attach(skb, icmp_param->skb); 366 return 0; 367 } 368 369 static void icmp_push_reply(struct sock *sk, 370 struct icmp_bxm *icmp_param, 371 struct flowi4 *fl4, 372 struct ipcm_cookie *ipc, struct rtable **rt) 373 { 374 struct sk_buff *skb; 375 376 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 377 icmp_param->data_len+icmp_param->head_len, 378 icmp_param->head_len, 379 ipc, rt, MSG_DONTWAIT) < 0) { 380 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 381 ip_flush_pending_frames(sk); 382 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 383 struct icmphdr *icmph = icmp_hdr(skb); 384 __wsum csum; 385 struct sk_buff *skb1; 386 387 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 388 (char *)icmph, 389 icmp_param->head_len); 390 skb_queue_walk(&sk->sk_write_queue, skb1) { 391 csum = csum_add(csum, skb1->csum); 392 } 393 icmph->checksum = csum_fold(csum); 394 skb->ip_summed = CHECKSUM_NONE; 395 ip_push_pending_frames(sk, fl4); 396 } 397 } 398 399 /* 400 * Driving logic for building and sending ICMP messages. 401 */ 402 403 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 404 { 405 struct rtable *rt = skb_rtable(skb); 406 struct net *net = dev_net_rcu(rt->dst.dev); 407 bool apply_ratelimit = false; 408 struct ipcm_cookie ipc; 409 struct flowi4 fl4; 410 struct sock *sk; 411 __be32 daddr, saddr; 412 u32 mark = IP4_REPLY_MARK(net, skb->mark); 413 int type = icmp_param->data.icmph.type; 414 int code = icmp_param->data.icmph.code; 415 416 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 417 return; 418 419 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 420 local_bh_disable(); 421 422 /* is global icmp_msgs_per_sec exhausted ? */ 423 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 424 goto out_bh_enable; 425 426 sk = icmp_xmit_lock(net); 427 if (!sk) 428 goto out_bh_enable; 429 430 icmp_param->data.icmph.checksum = 0; 431 432 ipcm_init(&ipc); 433 ipc.tos = ip_hdr(skb)->tos; 434 ipc.sockc.mark = mark; 435 daddr = ipc.addr = ip_hdr(skb)->saddr; 436 saddr = fib_compute_spec_dst(skb); 437 438 if (icmp_param->replyopts.opt.opt.optlen) { 439 ipc.opt = &icmp_param->replyopts.opt; 440 if (ipc.opt->opt.srr) 441 daddr = icmp_param->replyopts.opt.opt.faddr; 442 } 443 memset(&fl4, 0, sizeof(fl4)); 444 fl4.daddr = daddr; 445 fl4.saddr = saddr; 446 fl4.flowi4_mark = mark; 447 fl4.flowi4_uid = sock_net_uid(net, NULL); 448 fl4.flowi4_dscp = ip4h_dscp(ip_hdr(skb)); 449 fl4.flowi4_proto = IPPROTO_ICMP; 450 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 451 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 452 rt = ip_route_output_key(net, &fl4); 453 if (IS_ERR(rt)) 454 goto out_unlock; 455 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 456 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 457 ip_rt_put(rt); 458 out_unlock: 459 icmp_xmit_unlock(sk); 460 out_bh_enable: 461 local_bh_enable(); 462 } 463 464 /* 465 * The device used for looking up which routing table to use for sending an ICMP 466 * error is preferably the source whenever it is set, which should ensure the 467 * icmp error can be sent to the source host, else lookup using the routing 468 * table of the destination device, else use the main routing table (index 0). 469 */ 470 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 471 { 472 struct net_device *dev = skb->dev; 473 const struct dst_entry *dst; 474 475 if (dev) 476 return dev; 477 dst = skb_dst(skb); 478 return dst ? dst_dev(dst) : NULL; 479 } 480 481 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 482 struct sk_buff *skb_in, 483 const struct iphdr *iph, __be32 saddr, 484 dscp_t dscp, u32 mark, int type, 485 int code, struct icmp_bxm *param) 486 { 487 struct net_device *route_lookup_dev; 488 struct dst_entry *dst, *dst2; 489 struct rtable *rt, *rt2; 490 struct flowi4 fl4_dec; 491 int err; 492 493 memset(fl4, 0, sizeof(*fl4)); 494 fl4->daddr = (param->replyopts.opt.opt.srr ? 495 param->replyopts.opt.opt.faddr : iph->saddr); 496 fl4->saddr = saddr; 497 fl4->flowi4_mark = mark; 498 fl4->flowi4_uid = sock_net_uid(net, NULL); 499 fl4->flowi4_dscp = dscp; 500 fl4->flowi4_proto = IPPROTO_ICMP; 501 fl4->fl4_icmp_type = type; 502 fl4->fl4_icmp_code = code; 503 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 504 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 505 506 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 507 rt = ip_route_output_key_hash(net, fl4, skb_in); 508 if (IS_ERR(rt)) 509 return rt; 510 511 /* No need to clone since we're just using its address. */ 512 rt2 = rt; 513 514 dst = xfrm_lookup(net, &rt->dst, 515 flowi4_to_flowi(fl4), NULL, 0); 516 rt = dst_rtable(dst); 517 if (!IS_ERR(dst)) { 518 if (rt != rt2) 519 return rt; 520 if (inet_addr_type_dev_table(net, route_lookup_dev, 521 fl4->daddr) == RTN_LOCAL) 522 return rt; 523 } else if (PTR_ERR(dst) == -EPERM) { 524 rt = NULL; 525 } else { 526 return rt; 527 } 528 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 529 if (err) 530 goto relookup_failed; 531 532 if (inet_addr_type_dev_table(net, route_lookup_dev, 533 fl4_dec.saddr) == RTN_LOCAL) { 534 rt2 = __ip_route_output_key(net, &fl4_dec); 535 if (IS_ERR(rt2)) 536 err = PTR_ERR(rt2); 537 } else { 538 struct flowi4 fl4_2 = {}; 539 unsigned long orefdst; 540 541 fl4_2.daddr = fl4_dec.saddr; 542 rt2 = ip_route_output_key(net, &fl4_2); 543 if (IS_ERR(rt2)) { 544 err = PTR_ERR(rt2); 545 goto relookup_failed; 546 } 547 /* Ugh! */ 548 orefdst = skb_dstref_steal(skb_in); 549 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 550 dscp, rt2->dst.dev) ? -EINVAL : 0; 551 552 dst_release(&rt2->dst); 553 rt2 = skb_rtable(skb_in); 554 /* steal dst entry from skb_in, don't drop refcnt */ 555 skb_dstref_steal(skb_in); 556 skb_dstref_restore(skb_in, orefdst); 557 } 558 559 if (err) 560 goto relookup_failed; 561 562 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 563 XFRM_LOOKUP_ICMP); 564 rt2 = dst_rtable(dst2); 565 if (!IS_ERR(dst2)) { 566 dst_release(&rt->dst); 567 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 568 rt = rt2; 569 } else if (PTR_ERR(dst2) == -EPERM) { 570 if (rt) 571 dst_release(&rt->dst); 572 return rt2; 573 } else { 574 err = PTR_ERR(dst2); 575 goto relookup_failed; 576 } 577 return rt; 578 579 relookup_failed: 580 if (rt) 581 return rt; 582 return ERR_PTR(err); 583 } 584 585 struct icmp_ext_iio_addr4_subobj { 586 __be16 afi; 587 __be16 reserved; 588 __be32 addr4; 589 }; 590 591 static unsigned int icmp_ext_iio_len(void) 592 { 593 return sizeof(struct icmp_extobj_hdr) + 594 /* ifIndex */ 595 sizeof(__be32) + 596 /* Interface Address Sub-Object */ 597 sizeof(struct icmp_ext_iio_addr4_subobj) + 598 /* Interface Name Sub-Object. Length must be a multiple of 4 599 * bytes. 600 */ 601 ALIGN(sizeof(struct icmp_ext_iio_name_subobj), 4) + 602 /* MTU */ 603 sizeof(__be32); 604 } 605 606 static unsigned int icmp_ext_max_len(u8 ext_objs) 607 { 608 unsigned int ext_max_len; 609 610 ext_max_len = sizeof(struct icmp_ext_hdr); 611 612 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 613 ext_max_len += icmp_ext_iio_len(); 614 615 return ext_max_len; 616 } 617 618 static __be32 icmp_ext_iio_addr4_find(const struct net_device *dev) 619 { 620 struct in_device *in_dev; 621 struct in_ifaddr *ifa; 622 623 in_dev = __in_dev_get_rcu(dev); 624 if (!in_dev) 625 return 0; 626 627 /* It is unclear from RFC 5837 which IP address should be chosen, but 628 * it makes sense to choose a global unicast address. 629 */ 630 in_dev_for_each_ifa_rcu(ifa, in_dev) { 631 if (READ_ONCE(ifa->ifa_flags) & IFA_F_SECONDARY) 632 continue; 633 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || 634 ipv4_is_multicast(ifa->ifa_address)) 635 continue; 636 return ifa->ifa_address; 637 } 638 639 return 0; 640 } 641 642 static void icmp_ext_iio_iif_append(struct net *net, struct sk_buff *skb, 643 int iif) 644 { 645 struct icmp_ext_iio_name_subobj *name_subobj; 646 struct icmp_extobj_hdr *objh; 647 struct net_device *dev; 648 __be32 data; 649 650 if (!iif) 651 return; 652 653 /* Add the fields in the order specified by RFC 5837. */ 654 objh = skb_put(skb, sizeof(*objh)); 655 objh->class_num = ICMP_EXT_OBJ_CLASS_IIO; 656 objh->class_type = ICMP_EXT_CTYPE_IIO_ROLE(ICMP_EXT_CTYPE_IIO_ROLE_IIF); 657 658 data = htonl(iif); 659 skb_put_data(skb, &data, sizeof(__be32)); 660 objh->class_type |= ICMP_EXT_CTYPE_IIO_IFINDEX; 661 662 rcu_read_lock(); 663 664 dev = dev_get_by_index_rcu(net, iif); 665 if (!dev) 666 goto out; 667 668 data = icmp_ext_iio_addr4_find(dev); 669 if (data) { 670 struct icmp_ext_iio_addr4_subobj *addr4_subobj; 671 672 addr4_subobj = skb_put_zero(skb, sizeof(*addr4_subobj)); 673 addr4_subobj->afi = htons(ICMP_AFI_IP); 674 addr4_subobj->addr4 = data; 675 objh->class_type |= ICMP_EXT_CTYPE_IIO_IPADDR; 676 } 677 678 name_subobj = skb_put_zero(skb, ALIGN(sizeof(*name_subobj), 4)); 679 name_subobj->len = ALIGN(sizeof(*name_subobj), 4); 680 netdev_copy_name(dev, name_subobj->name); 681 objh->class_type |= ICMP_EXT_CTYPE_IIO_NAME; 682 683 data = htonl(READ_ONCE(dev->mtu)); 684 skb_put_data(skb, &data, sizeof(__be32)); 685 objh->class_type |= ICMP_EXT_CTYPE_IIO_MTU; 686 687 out: 688 rcu_read_unlock(); 689 objh->length = htons(skb_tail_pointer(skb) - (unsigned char *)objh); 690 } 691 692 static void icmp_ext_objs_append(struct net *net, struct sk_buff *skb, 693 u8 ext_objs, int iif) 694 { 695 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 696 icmp_ext_iio_iif_append(net, skb, iif); 697 } 698 699 static struct sk_buff * 700 icmp_ext_append(struct net *net, struct sk_buff *skb_in, struct icmphdr *icmph, 701 unsigned int room, int iif) 702 { 703 unsigned int payload_len, ext_max_len, ext_len; 704 struct icmp_ext_hdr *ext_hdr; 705 struct sk_buff *skb; 706 u8 ext_objs; 707 int nhoff; 708 709 switch (icmph->type) { 710 case ICMP_DEST_UNREACH: 711 case ICMP_TIME_EXCEEDED: 712 case ICMP_PARAMETERPROB: 713 break; 714 default: 715 return NULL; 716 } 717 718 ext_objs = READ_ONCE(net->ipv4.sysctl_icmp_errors_extension_mask); 719 if (!ext_objs) 720 return NULL; 721 722 ext_max_len = icmp_ext_max_len(ext_objs); 723 if (ICMP_EXT_ORIG_DGRAM_MIN_LEN + ext_max_len > room) 724 return NULL; 725 726 skb = skb_clone(skb_in, GFP_ATOMIC); 727 if (!skb) 728 return NULL; 729 730 nhoff = skb_network_offset(skb); 731 payload_len = min(skb->len - nhoff, ICMP_EXT_ORIG_DGRAM_MIN_LEN); 732 733 if (!pskb_network_may_pull(skb, payload_len)) 734 goto free_skb; 735 736 if (pskb_trim(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN) || 737 __skb_put_padto(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN, false)) 738 goto free_skb; 739 740 if (pskb_expand_head(skb, 0, ext_max_len, GFP_ATOMIC)) 741 goto free_skb; 742 743 ext_hdr = skb_put_zero(skb, sizeof(*ext_hdr)); 744 ext_hdr->version = ICMP_EXT_VERSION_2; 745 746 icmp_ext_objs_append(net, skb, ext_objs, iif); 747 748 /* Do not send an empty extension structure. */ 749 ext_len = skb_tail_pointer(skb) - (unsigned char *)ext_hdr; 750 if (ext_len == sizeof(*ext_hdr)) 751 goto free_skb; 752 753 ext_hdr->checksum = ip_compute_csum(ext_hdr, ext_len); 754 /* The length of the original datagram in 32-bit words (RFC 4884). */ 755 icmph->un.reserved[1] = ICMP_EXT_ORIG_DGRAM_MIN_LEN / sizeof(u32); 756 757 return skb; 758 759 free_skb: 760 consume_skb(skb); 761 return NULL; 762 } 763 764 /* 765 * Send an ICMP message in response to a situation 766 * 767 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 768 * MAY send more (we do). 769 * MUST NOT change this header information. 770 * MUST NOT reply to a multicast/broadcast IP address. 771 * MUST NOT reply to a multicast/broadcast MAC address. 772 * MUST reply to only the first fragment. 773 */ 774 775 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 776 const struct inet_skb_parm *parm) 777 { 778 struct iphdr *iph; 779 int room; 780 struct icmp_bxm icmp_param; 781 struct rtable *rt = skb_rtable(skb_in); 782 bool apply_ratelimit = false; 783 struct sk_buff *ext_skb; 784 struct ipcm_cookie ipc; 785 struct flowi4 fl4; 786 __be32 saddr; 787 u8 tos; 788 u32 mark; 789 struct net *net; 790 struct sock *sk; 791 792 if (!rt) 793 return; 794 795 rcu_read_lock(); 796 797 if (rt->dst.dev) 798 net = dev_net_rcu(rt->dst.dev); 799 else if (skb_in->dev) 800 net = dev_net_rcu(skb_in->dev); 801 else 802 goto out; 803 804 /* 805 * Find the original header. It is expected to be valid, of course. 806 * Check this, icmp_send is called from the most obscure devices 807 * sometimes. 808 */ 809 iph = ip_hdr(skb_in); 810 811 if ((u8 *)iph < skb_in->head || 812 (skb_network_header(skb_in) + sizeof(*iph)) > 813 skb_tail_pointer(skb_in)) 814 goto out; 815 816 /* 817 * No replies to physical multicast/broadcast 818 */ 819 if (skb_in->pkt_type != PACKET_HOST) 820 goto out; 821 822 /* 823 * Now check at the protocol level 824 */ 825 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 826 goto out; 827 828 /* 829 * Only reply to fragment 0. We byte re-order the constant 830 * mask for efficiency. 831 */ 832 if (iph->frag_off & htons(IP_OFFSET)) 833 goto out; 834 835 /* 836 * If we send an ICMP error to an ICMP error a mess would result.. 837 */ 838 if (icmp_pointers[type].error) { 839 /* 840 * We are an error, check if we are replying to an 841 * ICMP error 842 */ 843 if (iph->protocol == IPPROTO_ICMP) { 844 u8 _inner_type, *itp; 845 846 itp = skb_header_pointer(skb_in, 847 skb_network_header(skb_in) + 848 (iph->ihl << 2) + 849 offsetof(struct icmphdr, 850 type) - 851 skb_in->data, 852 sizeof(_inner_type), 853 &_inner_type); 854 if (!itp) 855 goto out; 856 857 /* 858 * Assume any unknown ICMP type is an error. This 859 * isn't specified by the RFC, but think about it.. 860 */ 861 if (*itp > NR_ICMP_TYPES || 862 icmp_pointers[*itp].error) 863 goto out; 864 } 865 } 866 867 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 868 local_bh_disable(); 869 870 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 871 * incoming dev is loopback. If outgoing dev change to not be 872 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 873 */ 874 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 875 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 876 goto out_bh_enable; 877 878 sk = icmp_xmit_lock(net); 879 if (!sk) 880 goto out_bh_enable; 881 882 /* 883 * Construct source address and options. 884 */ 885 886 saddr = iph->daddr; 887 if (!(rt->rt_flags & RTCF_LOCAL)) { 888 struct net_device *dev = NULL; 889 890 rcu_read_lock(); 891 if (rt_is_input_route(rt) && 892 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 893 dev = dev_get_by_index_rcu(net, parm->iif ? parm->iif : 894 inet_iif(skb_in)); 895 896 if (dev) 897 saddr = inet_select_addr(dev, iph->saddr, 898 RT_SCOPE_LINK); 899 else 900 saddr = 0; 901 rcu_read_unlock(); 902 } 903 904 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 905 IPTOS_PREC_INTERNETCONTROL) : 906 iph->tos; 907 mark = IP4_REPLY_MARK(net, skb_in->mark); 908 909 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, 910 &parm->opt)) 911 goto out_unlock; 912 913 914 /* 915 * Prepare data for ICMP header. 916 */ 917 918 icmp_param.data.icmph.type = type; 919 icmp_param.data.icmph.code = code; 920 icmp_param.data.icmph.un.gateway = info; 921 icmp_param.data.icmph.checksum = 0; 922 icmp_param.skb = skb_in; 923 icmp_param.offset = skb_network_offset(skb_in); 924 ipcm_init(&ipc); 925 ipc.tos = tos; 926 ipc.addr = iph->saddr; 927 ipc.opt = &icmp_param.replyopts.opt; 928 ipc.sockc.mark = mark; 929 930 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 931 inet_dsfield_to_dscp(tos), mark, type, code, 932 &icmp_param); 933 if (IS_ERR(rt)) 934 goto out_unlock; 935 936 /* peer icmp_ratelimit */ 937 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 938 goto ende; 939 940 /* RFC says return as much as we can without exceeding 576 bytes. */ 941 942 room = dst_mtu(&rt->dst); 943 if (room > 576) 944 room = 576; 945 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 946 room -= sizeof(struct icmphdr); 947 /* Guard against tiny mtu. We need to include at least one 948 * IP network header for this message to make any sense. 949 */ 950 if (room <= (int)sizeof(struct iphdr)) 951 goto ende; 952 953 ext_skb = icmp_ext_append(net, skb_in, &icmp_param.data.icmph, room, 954 parm->iif); 955 if (ext_skb) 956 icmp_param.skb = ext_skb; 957 958 icmp_param.data_len = icmp_param.skb->len - icmp_param.offset; 959 if (icmp_param.data_len > room) 960 icmp_param.data_len = room; 961 icmp_param.head_len = sizeof(struct icmphdr); 962 963 /* if we don't have a source address at this point, fall back to the 964 * dummy address instead of sending out a packet with a source address 965 * of 0.0.0.0 966 */ 967 if (!fl4.saddr) 968 fl4.saddr = htonl(INADDR_DUMMY); 969 970 trace_icmp_send(skb_in, type, code); 971 972 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 973 974 if (ext_skb) 975 consume_skb(ext_skb); 976 ende: 977 ip_rt_put(rt); 978 out_unlock: 979 icmp_xmit_unlock(sk); 980 out_bh_enable: 981 local_bh_enable(); 982 out: 983 rcu_read_unlock(); 984 } 985 EXPORT_SYMBOL(__icmp_send); 986 987 #if IS_ENABLED(CONFIG_NF_NAT) 988 #include <net/netfilter/nf_conntrack.h> 989 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 990 { 991 struct sk_buff *cloned_skb = NULL; 992 enum ip_conntrack_info ctinfo; 993 enum ip_conntrack_dir dir; 994 struct inet_skb_parm parm; 995 struct nf_conn *ct; 996 __be32 orig_ip; 997 998 memset(&parm, 0, sizeof(parm)); 999 ct = nf_ct_get(skb_in, &ctinfo); 1000 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { 1001 __icmp_send(skb_in, type, code, info, &parm); 1002 return; 1003 } 1004 1005 if (skb_shared(skb_in)) 1006 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 1007 1008 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 1009 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 1010 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 1011 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 1012 goto out; 1013 1014 orig_ip = ip_hdr(skb_in)->saddr; 1015 dir = CTINFO2DIR(ctinfo); 1016 ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; 1017 __icmp_send(skb_in, type, code, info, &parm); 1018 ip_hdr(skb_in)->saddr = orig_ip; 1019 out: 1020 consume_skb(cloned_skb); 1021 } 1022 EXPORT_SYMBOL(icmp_ndo_send); 1023 #endif 1024 1025 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 1026 { 1027 const struct iphdr *iph = (const struct iphdr *)skb->data; 1028 const struct net_protocol *ipprot; 1029 int protocol = iph->protocol; 1030 1031 /* Checkin full IP header plus 8 bytes of protocol to 1032 * avoid additional coding at protocol handlers. 1033 */ 1034 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 1035 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1036 return; 1037 } 1038 1039 raw_icmp_error(skb, protocol, info); 1040 1041 ipprot = rcu_dereference(inet_protos[protocol]); 1042 if (ipprot && ipprot->err_handler) 1043 ipprot->err_handler(skb, info); 1044 } 1045 1046 static bool icmp_tag_validation(int proto) 1047 { 1048 bool ok; 1049 1050 rcu_read_lock(); 1051 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 1052 rcu_read_unlock(); 1053 return ok; 1054 } 1055 1056 /* 1057 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 1058 * ICMP_PARAMETERPROB. 1059 */ 1060 1061 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 1062 { 1063 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 1064 const struct iphdr *iph; 1065 struct icmphdr *icmph; 1066 struct net *net; 1067 u32 info = 0; 1068 1069 net = skb_dst_dev_net_rcu(skb); 1070 1071 /* 1072 * Incomplete header ? 1073 * Only checks for the IP header, there should be an 1074 * additional check for longer headers in upper levels. 1075 */ 1076 1077 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 1078 goto out_err; 1079 1080 icmph = icmp_hdr(skb); 1081 iph = (const struct iphdr *)skb->data; 1082 1083 if (iph->ihl < 5) { /* Mangled header, drop. */ 1084 reason = SKB_DROP_REASON_IP_INHDR; 1085 goto out_err; 1086 } 1087 1088 switch (icmph->type) { 1089 case ICMP_DEST_UNREACH: 1090 switch (icmph->code & 15) { 1091 case ICMP_NET_UNREACH: 1092 case ICMP_HOST_UNREACH: 1093 case ICMP_PROT_UNREACH: 1094 case ICMP_PORT_UNREACH: 1095 break; 1096 case ICMP_FRAG_NEEDED: 1097 /* for documentation of the ip_no_pmtu_disc 1098 * values please see 1099 * Documentation/networking/ip-sysctl.rst 1100 */ 1101 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 1102 default: 1103 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 1104 &iph->daddr); 1105 break; 1106 case 2: 1107 goto out; 1108 case 3: 1109 if (!icmp_tag_validation(iph->protocol)) 1110 goto out; 1111 fallthrough; 1112 case 0: 1113 info = ntohs(icmph->un.frag.mtu); 1114 } 1115 break; 1116 case ICMP_SR_FAILED: 1117 net_dbg_ratelimited("%pI4: Source Route Failed\n", 1118 &iph->daddr); 1119 break; 1120 default: 1121 break; 1122 } 1123 if (icmph->code > NR_ICMP_UNREACH) 1124 goto out; 1125 break; 1126 case ICMP_PARAMETERPROB: 1127 info = ntohl(icmph->un.gateway) >> 24; 1128 break; 1129 case ICMP_TIME_EXCEEDED: 1130 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 1131 if (icmph->code == ICMP_EXC_FRAGTIME) 1132 goto out; 1133 break; 1134 } 1135 1136 /* 1137 * Throw it at our lower layers 1138 * 1139 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 1140 * header. 1141 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 1142 * transport layer. 1143 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 1144 * transport layer. 1145 */ 1146 1147 /* 1148 * Check the other end isn't violating RFC 1122. Some routers send 1149 * bogus responses to broadcast frames. If you see this message 1150 * first check your netmask matches at both ends, if it does then 1151 * get the other vendor to fix their kit. 1152 */ 1153 1154 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 1155 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 1156 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 1157 &ip_hdr(skb)->saddr, 1158 icmph->type, icmph->code, 1159 &iph->daddr, skb->dev->name); 1160 goto out; 1161 } 1162 1163 icmp_socket_deliver(skb, info); 1164 1165 out: 1166 return reason; 1167 out_err: 1168 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1169 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 1170 } 1171 1172 1173 /* 1174 * Handle ICMP_REDIRECT. 1175 */ 1176 1177 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 1178 { 1179 if (skb->len < sizeof(struct iphdr)) { 1180 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1181 return SKB_DROP_REASON_PKT_TOO_SMALL; 1182 } 1183 1184 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 1185 /* there aught to be a stat */ 1186 return SKB_DROP_REASON_NOMEM; 1187 } 1188 1189 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 1190 return SKB_NOT_DROPPED_YET; 1191 } 1192 1193 /* 1194 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1195 * 1196 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1197 * requests. 1198 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1199 * included in the reply. 1200 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1201 * echo requests, MUST have default=NOT. 1202 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1203 * Extended Echo Functionality, MUST be disabled by default 1204 * See also WRT handling of options once they are done and working. 1205 */ 1206 1207 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1208 { 1209 struct icmp_bxm icmp_param; 1210 struct net *net; 1211 1212 net = skb_dst_dev_net_rcu(skb); 1213 /* should there be an ICMP stat for ignored echos? */ 1214 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1215 return SKB_NOT_DROPPED_YET; 1216 1217 icmp_param.data.icmph = *icmp_hdr(skb); 1218 icmp_param.skb = skb; 1219 icmp_param.offset = 0; 1220 icmp_param.data_len = skb->len; 1221 icmp_param.head_len = sizeof(struct icmphdr); 1222 1223 if (icmp_param.data.icmph.type == ICMP_ECHO) 1224 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1225 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1226 return SKB_NOT_DROPPED_YET; 1227 1228 icmp_reply(&icmp_param, skb); 1229 return SKB_NOT_DROPPED_YET; 1230 } 1231 1232 /* Helper for icmp_echo and icmpv6_echo_reply. 1233 * Searches for net_device that matches PROBE interface identifier 1234 * and builds PROBE reply message in icmphdr. 1235 * 1236 * Returns false if PROBE responses are disabled via sysctl 1237 */ 1238 1239 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1240 { 1241 struct net *net = dev_net_rcu(skb->dev); 1242 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1243 struct icmp_ext_echo_iio *iio, _iio; 1244 struct inet6_dev *in6_dev; 1245 struct in_device *in_dev; 1246 struct net_device *dev; 1247 char buff[IFNAMSIZ]; 1248 u16 ident_len; 1249 u8 status; 1250 1251 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1252 return false; 1253 1254 /* We currently only support probing interfaces on the proxy node 1255 * Check to ensure L-bit is set 1256 */ 1257 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1258 return false; 1259 /* Clear status bits in reply message */ 1260 icmphdr->un.echo.sequence &= htons(0xFF00); 1261 if (icmphdr->type == ICMP_EXT_ECHO) 1262 icmphdr->type = ICMP_EXT_ECHOREPLY; 1263 else 1264 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1265 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1266 /* Size of iio is class_type dependent. 1267 * Only check header here and assign length based on ctype in the switch statement 1268 */ 1269 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1270 if (!ext_hdr || !iio) 1271 goto send_mal_query; 1272 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1273 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1274 goto send_mal_query; 1275 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1276 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1277 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1278 if (!iio) 1279 goto send_mal_query; 1280 1281 status = 0; 1282 dev = NULL; 1283 switch (iio->extobj_hdr.class_type) { 1284 case ICMP_EXT_ECHO_CTYPE_NAME: 1285 if (ident_len >= IFNAMSIZ) 1286 goto send_mal_query; 1287 memset(buff, 0, sizeof(buff)); 1288 memcpy(buff, &iio->ident.name, ident_len); 1289 dev = dev_get_by_name(net, buff); 1290 break; 1291 case ICMP_EXT_ECHO_CTYPE_INDEX: 1292 if (ident_len != sizeof(iio->ident.ifindex)) 1293 goto send_mal_query; 1294 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1295 break; 1296 case ICMP_EXT_ECHO_CTYPE_ADDR: 1297 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1298 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1299 iio->ident.addr.ctype3_hdr.addrlen) 1300 goto send_mal_query; 1301 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1302 case ICMP_AFI_IP: 1303 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1304 goto send_mal_query; 1305 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1306 break; 1307 #if IS_ENABLED(CONFIG_IPV6) 1308 case ICMP_AFI_IP6: 1309 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1310 goto send_mal_query; 1311 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1312 dev_hold(dev); 1313 break; 1314 #endif 1315 default: 1316 goto send_mal_query; 1317 } 1318 break; 1319 default: 1320 goto send_mal_query; 1321 } 1322 if (!dev) { 1323 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1324 return true; 1325 } 1326 /* Fill bits in reply message */ 1327 if (dev->flags & IFF_UP) 1328 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1329 1330 in_dev = __in_dev_get_rcu(dev); 1331 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1332 status |= ICMP_EXT_ECHOREPLY_IPV4; 1333 1334 in6_dev = __in6_dev_get(dev); 1335 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1336 status |= ICMP_EXT_ECHOREPLY_IPV6; 1337 1338 dev_put(dev); 1339 icmphdr->un.echo.sequence |= htons(status); 1340 return true; 1341 send_mal_query: 1342 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1343 return true; 1344 } 1345 EXPORT_SYMBOL_GPL(icmp_build_probe); 1346 1347 /* 1348 * Handle ICMP Timestamp requests. 1349 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1350 * SHOULD be in the kernel for minimum random latency. 1351 * MUST be accurate to a few minutes. 1352 * MUST be updated at least at 15Hz. 1353 */ 1354 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1355 { 1356 struct icmp_bxm icmp_param; 1357 /* 1358 * Too short. 1359 */ 1360 if (skb->len < 4) 1361 goto out_err; 1362 1363 /* 1364 * Fill in the current time as ms since midnight UT: 1365 */ 1366 icmp_param.data.times[1] = inet_current_timestamp(); 1367 icmp_param.data.times[2] = icmp_param.data.times[1]; 1368 1369 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1370 1371 icmp_param.data.icmph = *icmp_hdr(skb); 1372 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1373 icmp_param.data.icmph.code = 0; 1374 icmp_param.skb = skb; 1375 icmp_param.offset = 0; 1376 icmp_param.data_len = 0; 1377 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1378 icmp_reply(&icmp_param, skb); 1379 return SKB_NOT_DROPPED_YET; 1380 1381 out_err: 1382 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS); 1383 return SKB_DROP_REASON_PKT_TOO_SMALL; 1384 } 1385 1386 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1387 { 1388 /* pretend it was a success */ 1389 return SKB_NOT_DROPPED_YET; 1390 } 1391 1392 /* 1393 * Deal with incoming ICMP packets. 1394 */ 1395 int icmp_rcv(struct sk_buff *skb) 1396 { 1397 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1398 struct rtable *rt = skb_rtable(skb); 1399 struct net *net = dev_net_rcu(rt->dst.dev); 1400 struct icmphdr *icmph; 1401 1402 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1403 struct sec_path *sp = skb_sec_path(skb); 1404 int nh; 1405 1406 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1407 XFRM_STATE_ICMP)) { 1408 reason = SKB_DROP_REASON_XFRM_POLICY; 1409 goto drop; 1410 } 1411 1412 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1413 goto drop; 1414 1415 nh = skb_network_offset(skb); 1416 skb_set_network_header(skb, sizeof(*icmph)); 1417 1418 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1419 skb)) { 1420 reason = SKB_DROP_REASON_XFRM_POLICY; 1421 goto drop; 1422 } 1423 1424 skb_set_network_header(skb, nh); 1425 } 1426 1427 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1428 1429 if (skb_checksum_simple_validate(skb)) 1430 goto csum_error; 1431 1432 if (!pskb_pull(skb, sizeof(*icmph))) 1433 goto error; 1434 1435 icmph = icmp_hdr(skb); 1436 1437 ICMPMSGIN_INC_STATS(net, icmph->type); 1438 1439 /* Check for ICMP Extended Echo (PROBE) messages */ 1440 if (icmph->type == ICMP_EXT_ECHO) { 1441 /* We can't use icmp_pointers[].handler() because it is an array of 1442 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1443 */ 1444 reason = icmp_echo(skb); 1445 goto reason_check; 1446 } 1447 1448 /* 1449 * Parse the ICMP message 1450 */ 1451 1452 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1453 /* 1454 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1455 * silently ignored (we let user decide with a sysctl). 1456 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1457 * discarded if to broadcast/multicast. 1458 */ 1459 if ((icmph->type == ICMP_ECHO || 1460 icmph->type == ICMP_TIMESTAMP) && 1461 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1462 reason = SKB_DROP_REASON_INVALID_PROTO; 1463 goto error; 1464 } 1465 if (icmph->type != ICMP_ECHO && 1466 icmph->type != ICMP_TIMESTAMP && 1467 icmph->type != ICMP_ADDRESS && 1468 icmph->type != ICMP_ADDRESSREPLY) { 1469 reason = SKB_DROP_REASON_INVALID_PROTO; 1470 goto error; 1471 } 1472 } 1473 1474 if (icmph->type == ICMP_EXT_ECHOREPLY || 1475 icmph->type == ICMP_ECHOREPLY) { 1476 reason = ping_rcv(skb); 1477 return reason ? NET_RX_DROP : NET_RX_SUCCESS; 1478 } 1479 1480 /* 1481 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1482 * 1483 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1484 * discarded. 1485 */ 1486 if (icmph->type > NR_ICMP_TYPES) { 1487 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1488 goto error; 1489 } 1490 1491 reason = icmp_pointers[icmph->type].handler(skb); 1492 reason_check: 1493 if (!reason) { 1494 consume_skb(skb); 1495 return NET_RX_SUCCESS; 1496 } 1497 1498 drop: 1499 kfree_skb_reason(skb, reason); 1500 return NET_RX_DROP; 1501 csum_error: 1502 reason = SKB_DROP_REASON_ICMP_CSUM; 1503 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1504 error: 1505 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1506 goto drop; 1507 } 1508 1509 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1510 { 1511 struct icmp_extobj_hdr *objh, _objh; 1512 struct icmp_ext_hdr *exth, _exth; 1513 u16 olen; 1514 1515 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1516 if (!exth) 1517 return false; 1518 if (exth->version != 2) 1519 return true; 1520 1521 if (exth->checksum && 1522 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1523 return false; 1524 1525 off += sizeof(_exth); 1526 while (off < skb->len) { 1527 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1528 if (!objh) 1529 return false; 1530 1531 olen = ntohs(objh->length); 1532 if (olen < sizeof(_objh)) 1533 return false; 1534 1535 off += olen; 1536 if (off > skb->len) 1537 return false; 1538 } 1539 1540 return true; 1541 } 1542 1543 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1544 struct sock_ee_data_rfc4884 *out, 1545 int thlen, int off) 1546 { 1547 int hlen; 1548 1549 /* original datagram headers: end of icmph to payload (skb->data) */ 1550 hlen = -skb_transport_offset(skb) - thlen; 1551 1552 /* per rfc 4884: minimal datagram length of 128 bytes */ 1553 if (off < 128 || off < hlen) 1554 return; 1555 1556 /* kernel has stripped headers: return payload offset in bytes */ 1557 off -= hlen; 1558 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1559 return; 1560 1561 out->len = off; 1562 1563 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1564 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1565 } 1566 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1567 1568 int icmp_err(struct sk_buff *skb, u32 info) 1569 { 1570 struct iphdr *iph = (struct iphdr *)skb->data; 1571 int offset = iph->ihl<<2; 1572 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1573 struct net *net = dev_net_rcu(skb->dev); 1574 int type = icmp_hdr(skb)->type; 1575 int code = icmp_hdr(skb)->code; 1576 1577 /* 1578 * Use ping_err to handle all icmp errors except those 1579 * triggered by ICMP_ECHOREPLY which sent from kernel. 1580 */ 1581 if (icmph->type != ICMP_ECHOREPLY) { 1582 ping_err(skb, offset, info); 1583 return 0; 1584 } 1585 1586 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1587 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1588 else if (type == ICMP_REDIRECT) 1589 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1590 1591 return 0; 1592 } 1593 1594 /* 1595 * This table is the definition of how we handle ICMP. 1596 */ 1597 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1598 [ICMP_ECHOREPLY] = { 1599 .handler = ping_rcv, 1600 }, 1601 [1] = { 1602 .handler = icmp_discard, 1603 .error = 1, 1604 }, 1605 [2] = { 1606 .handler = icmp_discard, 1607 .error = 1, 1608 }, 1609 [ICMP_DEST_UNREACH] = { 1610 .handler = icmp_unreach, 1611 .error = 1, 1612 }, 1613 [ICMP_SOURCE_QUENCH] = { 1614 .handler = icmp_unreach, 1615 .error = 1, 1616 }, 1617 [ICMP_REDIRECT] = { 1618 .handler = icmp_redirect, 1619 .error = 1, 1620 }, 1621 [6] = { 1622 .handler = icmp_discard, 1623 .error = 1, 1624 }, 1625 [7] = { 1626 .handler = icmp_discard, 1627 .error = 1, 1628 }, 1629 [ICMP_ECHO] = { 1630 .handler = icmp_echo, 1631 }, 1632 [9] = { 1633 .handler = icmp_discard, 1634 .error = 1, 1635 }, 1636 [10] = { 1637 .handler = icmp_discard, 1638 .error = 1, 1639 }, 1640 [ICMP_TIME_EXCEEDED] = { 1641 .handler = icmp_unreach, 1642 .error = 1, 1643 }, 1644 [ICMP_PARAMETERPROB] = { 1645 .handler = icmp_unreach, 1646 .error = 1, 1647 }, 1648 [ICMP_TIMESTAMP] = { 1649 .handler = icmp_timestamp, 1650 }, 1651 [ICMP_TIMESTAMPREPLY] = { 1652 .handler = icmp_discard, 1653 }, 1654 [ICMP_INFO_REQUEST] = { 1655 .handler = icmp_discard, 1656 }, 1657 [ICMP_INFO_REPLY] = { 1658 .handler = icmp_discard, 1659 }, 1660 [ICMP_ADDRESS] = { 1661 .handler = icmp_discard, 1662 }, 1663 [ICMP_ADDRESSREPLY] = { 1664 .handler = icmp_discard, 1665 }, 1666 }; 1667 1668 static int __net_init icmp_sk_init(struct net *net) 1669 { 1670 /* Control parameters for ECHO replies. */ 1671 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1672 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1673 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1674 1675 /* Control parameter - ignore bogus broadcast responses? */ 1676 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1677 1678 /* 1679 * Configurable global rate limit. 1680 * 1681 * ratelimit defines tokens/packet consumed for dst->rate_token 1682 * bucket ratemask defines which icmp types are ratelimited by 1683 * setting it's bit position. 1684 * 1685 * default: 1686 * dest unreachable (3), source quench (4), 1687 * time exceeded (11), parameter problem (12) 1688 */ 1689 1690 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1691 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1692 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1693 net->ipv4.sysctl_icmp_errors_extension_mask = 0; 1694 net->ipv4.sysctl_icmp_msgs_per_sec = 1000; 1695 net->ipv4.sysctl_icmp_msgs_burst = 50; 1696 1697 return 0; 1698 } 1699 1700 static struct pernet_operations __net_initdata icmp_sk_ops = { 1701 .init = icmp_sk_init, 1702 }; 1703 1704 int __init icmp_init(void) 1705 { 1706 int err, i; 1707 1708 for_each_possible_cpu(i) { 1709 struct sock *sk; 1710 1711 err = inet_ctl_sock_create(&sk, PF_INET, 1712 SOCK_RAW, IPPROTO_ICMP, &init_net); 1713 if (err < 0) 1714 return err; 1715 1716 per_cpu(ipv4_icmp_sk, i) = sk; 1717 1718 /* Enough space for 2 64K ICMP packets, including 1719 * sk_buff/skb_shared_info struct overhead. 1720 */ 1721 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1722 1723 /* 1724 * Speedup sock_wfree() 1725 */ 1726 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1727 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1728 } 1729 return register_pernet_subsys(&icmp_sk_ops); 1730 } 1731