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; 115 116 /* Must be last as it ends in a flexible-array member. */ 117 struct ip_options_rcu replyopts; 118 }; 119 120 /* An array of errno for error messages from dest unreach. */ 121 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 122 123 const struct icmp_err icmp_err_convert[] = { 124 { 125 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 126 .fatal = 0, 127 }, 128 { 129 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 130 .fatal = 0, 131 }, 132 { 133 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 134 .fatal = 1, 135 }, 136 { 137 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 138 .fatal = 1, 139 }, 140 { 141 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 142 .fatal = 0, 143 }, 144 { 145 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 146 .fatal = 0, 147 }, 148 { 149 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 150 .fatal = 1, 151 }, 152 { 153 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 154 .fatal = 1, 155 }, 156 { 157 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 158 .fatal = 1, 159 }, 160 { 161 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 162 .fatal = 1, 163 }, 164 { 165 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 166 .fatal = 1, 167 }, 168 { 169 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 170 .fatal = 0, 171 }, 172 { 173 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 174 .fatal = 0, 175 }, 176 { 177 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 178 .fatal = 1, 179 }, 180 { 181 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 182 .fatal = 1, 183 }, 184 { 185 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 186 .fatal = 1, 187 }, 188 }; 189 EXPORT_SYMBOL(icmp_err_convert); 190 191 /* 192 * ICMP control array. This specifies what to do with each ICMP. 193 */ 194 195 struct icmp_control { 196 enum skb_drop_reason (*handler)(struct sk_buff *skb); 197 short error; /* This ICMP is classed as an error message */ 198 }; 199 200 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 201 202 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 203 204 /* Called with BH disabled */ 205 static inline struct sock *icmp_xmit_lock(struct net *net) 206 { 207 struct sock *sk; 208 209 sk = this_cpu_read(ipv4_icmp_sk); 210 211 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 212 /* This can happen if the output path signals a 213 * dst_link_failure() for an outgoing ICMP packet. 214 */ 215 return NULL; 216 } 217 sock_net_set(sk, net); 218 return sk; 219 } 220 221 static inline void icmp_xmit_unlock(struct sock *sk) 222 { 223 sock_net_set(sk, &init_net); 224 spin_unlock(&sk->sk_lock.slock); 225 } 226 227 /** 228 * icmp_global_allow - Are we allowed to send one more ICMP message ? 229 * @net: network namespace 230 * 231 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 232 * Returns false if we reached the limit and can not send another packet. 233 * Works in tandem with icmp_global_consume(). 234 */ 235 bool icmp_global_allow(struct net *net) 236 { 237 u32 delta, now, oldstamp; 238 int incr, new, old; 239 240 /* Note: many cpus could find this condition true. 241 * Then later icmp_global_consume() could consume more credits, 242 * this is an acceptable race. 243 */ 244 if (atomic_read(&net->ipv4.icmp_global_credit) > 0) 245 return true; 246 247 now = jiffies; 248 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); 249 delta = min_t(u32, now - oldstamp, HZ); 250 if (delta < HZ / 50) 251 return false; 252 253 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec); 254 incr = div_u64((u64)incr * delta, HZ); 255 if (!incr) 256 return false; 257 258 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 259 old = atomic_read(&net->ipv4.icmp_global_credit); 260 do { 261 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 262 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 263 } 264 return true; 265 } 266 267 void icmp_global_consume(struct net *net) 268 { 269 int credits = get_random_u32_below(3); 270 271 /* Note: this might make icmp_global.credit negative. */ 272 if (credits) 273 atomic_sub(credits, &net->ipv4.icmp_global_credit); 274 } 275 276 static bool icmpv4_mask_allow(struct net *net, int type, int code) 277 { 278 if (type > NR_ICMP_TYPES) 279 return true; 280 281 /* Don't limit PMTU discovery. */ 282 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 283 return true; 284 285 /* Limit if icmp type is enabled in ratemask. */ 286 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 287 return true; 288 289 return false; 290 } 291 292 static bool icmpv4_global_allow(struct net *net, int type, int code, 293 bool *apply_ratelimit) 294 { 295 if (icmpv4_mask_allow(net, type, code)) 296 return true; 297 298 if (icmp_global_allow(net)) { 299 *apply_ratelimit = true; 300 return true; 301 } 302 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 303 return false; 304 } 305 306 /* 307 * Send an ICMP frame. 308 */ 309 310 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 311 struct flowi4 *fl4, int type, int code, 312 bool apply_ratelimit) 313 { 314 struct dst_entry *dst = &rt->dst; 315 struct inet_peer *peer; 316 struct net_device *dev; 317 int peer_timeout; 318 bool rc = true; 319 320 if (!apply_ratelimit) 321 return true; 322 323 peer_timeout = READ_ONCE(net->ipv4.sysctl_icmp_ratelimit); 324 if (!peer_timeout) 325 goto out; 326 327 /* No rate limit on loopback */ 328 rcu_read_lock(); 329 dev = dst_dev_rcu(dst); 330 if (dev && (dev->flags & IFF_LOOPBACK)) 331 goto out_unlock; 332 333 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 334 l3mdev_master_ifindex_rcu(dev)); 335 rc = inet_peer_xrlim_allow(peer, peer_timeout); 336 337 out_unlock: 338 rcu_read_unlock(); 339 out: 340 if (!rc) 341 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 342 else 343 icmp_global_consume(net); 344 return rc; 345 } 346 347 /* 348 * Maintain the counters used in the SNMP statistics for outgoing ICMP 349 */ 350 void icmp_out_count(struct net *net, unsigned char type) 351 { 352 ICMPMSGOUT_INC_STATS(net, type); 353 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 354 } 355 356 /* 357 * Checksum each fragment, and on the first include the headers and final 358 * checksum. 359 */ 360 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 361 struct sk_buff *skb) 362 { 363 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 364 IP_OPTIONS_DATA_FIXED_SIZE); 365 __wsum csum; 366 367 icmp_param = from; 368 369 csum = skb_copy_and_csum_bits(icmp_param->skb, 370 icmp_param->offset + offset, 371 to, len); 372 373 skb->csum = csum_block_add(skb->csum, csum, odd); 374 if (icmp_pointers[icmp_param->data.icmph.type].error) 375 nf_ct_attach(skb, icmp_param->skb); 376 return 0; 377 } 378 379 static void icmp_push_reply(struct sock *sk, 380 struct icmp_bxm *icmp_param, 381 struct flowi4 *fl4, 382 struct ipcm_cookie *ipc, struct rtable **rt) 383 { 384 struct sk_buff *skb; 385 386 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 387 icmp_param->data_len+icmp_param->head_len, 388 icmp_param->head_len, 389 ipc, rt, MSG_DONTWAIT) < 0) { 390 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 391 ip_flush_pending_frames(sk); 392 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 393 struct icmphdr *icmph = icmp_hdr(skb); 394 __wsum csum; 395 struct sk_buff *skb1; 396 397 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 398 (char *)icmph, 399 icmp_param->head_len); 400 skb_queue_walk(&sk->sk_write_queue, skb1) { 401 csum = csum_add(csum, skb1->csum); 402 } 403 icmph->checksum = csum_fold(csum); 404 skb->ip_summed = CHECKSUM_NONE; 405 ip_push_pending_frames(sk, fl4); 406 } 407 } 408 409 /* 410 * Driving logic for building and sending ICMP messages. 411 */ 412 413 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 414 { 415 struct rtable *rt = skb_rtable(skb); 416 struct net *net = dev_net_rcu(rt->dst.dev); 417 bool apply_ratelimit = false; 418 struct ipcm_cookie ipc; 419 struct flowi4 fl4; 420 struct sock *sk; 421 __be32 daddr, saddr; 422 u32 mark = IP4_REPLY_MARK(net, skb->mark); 423 int type = icmp_param->data.icmph.type; 424 int code = icmp_param->data.icmph.code; 425 426 if (ip_options_echo(net, &icmp_param->replyopts.opt, skb)) 427 return; 428 429 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 430 local_bh_disable(); 431 432 /* is global icmp_msgs_per_sec exhausted ? */ 433 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 434 goto out_bh_enable; 435 436 sk = icmp_xmit_lock(net); 437 if (!sk) 438 goto out_bh_enable; 439 440 icmp_param->data.icmph.checksum = 0; 441 442 ipcm_init(&ipc); 443 ipc.tos = ip_hdr(skb)->tos; 444 ipc.sockc.mark = mark; 445 daddr = ipc.addr = ip_hdr(skb)->saddr; 446 saddr = fib_compute_spec_dst(skb); 447 448 if (icmp_param->replyopts.opt.optlen) { 449 ipc.opt = &icmp_param->replyopts; 450 if (ipc.opt->opt.srr) 451 daddr = icmp_param->replyopts.opt.faddr; 452 } 453 memset(&fl4, 0, sizeof(fl4)); 454 fl4.daddr = daddr; 455 fl4.saddr = saddr; 456 fl4.flowi4_mark = mark; 457 fl4.flowi4_uid = sock_net_uid(net, NULL); 458 fl4.flowi4_dscp = ip4h_dscp(ip_hdr(skb)); 459 fl4.flowi4_proto = IPPROTO_ICMP; 460 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 461 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 462 rt = ip_route_output_key(net, &fl4); 463 if (IS_ERR(rt)) 464 goto out_unlock; 465 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 466 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 467 ip_rt_put(rt); 468 out_unlock: 469 icmp_xmit_unlock(sk); 470 out_bh_enable: 471 local_bh_enable(); 472 } 473 474 /* 475 * The device used for looking up which routing table to use for sending an ICMP 476 * error is preferably the source whenever it is set, which should ensure the 477 * icmp error can be sent to the source host, else lookup using the routing 478 * table of the destination device, else use the main routing table (index 0). 479 */ 480 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 481 { 482 struct net_device *dev = skb->dev; 483 const struct dst_entry *dst; 484 485 if (dev) 486 return dev; 487 dst = skb_dst(skb); 488 return dst ? dst_dev(dst) : NULL; 489 } 490 491 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 492 struct sk_buff *skb_in, 493 const struct iphdr *iph, __be32 saddr, 494 dscp_t dscp, u32 mark, int type, 495 int code, struct icmp_bxm *param) 496 { 497 struct net_device *route_lookup_dev; 498 struct dst_entry *dst, *dst2; 499 struct rtable *rt, *rt2; 500 struct flowi4 fl4_dec; 501 int err; 502 503 memset(fl4, 0, sizeof(*fl4)); 504 fl4->daddr = (param->replyopts.opt.srr ? 505 param->replyopts.opt.faddr : iph->saddr); 506 fl4->saddr = saddr; 507 fl4->flowi4_mark = mark; 508 fl4->flowi4_uid = sock_net_uid(net, NULL); 509 fl4->flowi4_dscp = dscp; 510 fl4->flowi4_proto = IPPROTO_ICMP; 511 fl4->fl4_icmp_type = type; 512 fl4->fl4_icmp_code = code; 513 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 514 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 515 516 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 517 rt = ip_route_output_key_hash(net, fl4, skb_in); 518 if (IS_ERR(rt)) 519 return rt; 520 521 /* No need to clone since we're just using its address. */ 522 rt2 = rt; 523 524 dst = xfrm_lookup(net, &rt->dst, 525 flowi4_to_flowi(fl4), NULL, 0); 526 rt = dst_rtable(dst); 527 if (!IS_ERR(dst)) { 528 if (rt != rt2) 529 return rt; 530 if (inet_addr_type_dev_table(net, route_lookup_dev, 531 fl4->daddr) == RTN_LOCAL) 532 return rt; 533 } else if (PTR_ERR(dst) == -EPERM) { 534 rt = NULL; 535 } else { 536 return rt; 537 } 538 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 539 if (err) 540 goto relookup_failed; 541 542 if (inet_addr_type_dev_table(net, route_lookup_dev, 543 fl4_dec.saddr) == RTN_LOCAL) { 544 rt2 = __ip_route_output_key(net, &fl4_dec); 545 if (IS_ERR(rt2)) 546 err = PTR_ERR(rt2); 547 } else { 548 struct flowi4 fl4_2 = {}; 549 unsigned long orefdst; 550 551 fl4_2.daddr = fl4_dec.saddr; 552 rt2 = ip_route_output_key(net, &fl4_2); 553 if (IS_ERR(rt2)) { 554 err = PTR_ERR(rt2); 555 goto relookup_failed; 556 } 557 /* Ugh! */ 558 orefdst = skb_dstref_steal(skb_in); 559 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 560 dscp, rt2->dst.dev) ? -EINVAL : 0; 561 562 dst_release(&rt2->dst); 563 rt2 = skb_rtable(skb_in); 564 /* steal dst entry from skb_in, don't drop refcnt */ 565 skb_dstref_steal(skb_in); 566 skb_dstref_restore(skb_in, orefdst); 567 568 /* 569 * At this point, fl4_dec.daddr should NOT be local (we 570 * checked fl4_dec.saddr above). However, a race condition 571 * may occur if the address is added to the interface 572 * concurrently. In that case, ip_route_input() returns a 573 * LOCAL route with dst.output=ip_rt_bug, which must not 574 * be used for output. 575 */ 576 if (!err && rt2 && rt2->rt_type == RTN_LOCAL) { 577 net_warn_ratelimited("detected local route for %pI4 during ICMP sending, src %pI4\n", 578 &fl4_dec.daddr, &fl4_dec.saddr); 579 dst_release(&rt2->dst); 580 err = -EINVAL; 581 } 582 } 583 584 if (err) 585 goto relookup_failed; 586 587 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 588 XFRM_LOOKUP_ICMP); 589 rt2 = dst_rtable(dst2); 590 if (!IS_ERR(dst2)) { 591 dst_release(&rt->dst); 592 rt = rt2; 593 } else if (PTR_ERR(dst2) == -EPERM) { 594 if (rt) 595 dst_release(&rt->dst); 596 return rt2; 597 } else { 598 err = PTR_ERR(dst2); 599 goto relookup_failed; 600 } 601 return rt; 602 603 relookup_failed: 604 if (rt) 605 return rt; 606 return ERR_PTR(err); 607 } 608 609 struct icmp_ext_iio_addr4_subobj { 610 __be16 afi; 611 __be16 reserved; 612 __be32 addr4; 613 }; 614 615 static unsigned int icmp_ext_iio_len(void) 616 { 617 return sizeof(struct icmp_extobj_hdr) + 618 /* ifIndex */ 619 sizeof(__be32) + 620 /* Interface Address Sub-Object */ 621 sizeof(struct icmp_ext_iio_addr4_subobj) + 622 /* Interface Name Sub-Object. Length must be a multiple of 4 623 * bytes. 624 */ 625 ALIGN(sizeof(struct icmp_ext_iio_name_subobj), 4) + 626 /* MTU */ 627 sizeof(__be32); 628 } 629 630 static unsigned int icmp_ext_max_len(u8 ext_objs) 631 { 632 unsigned int ext_max_len; 633 634 ext_max_len = sizeof(struct icmp_ext_hdr); 635 636 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 637 ext_max_len += icmp_ext_iio_len(); 638 639 return ext_max_len; 640 } 641 642 static __be32 icmp_ext_iio_addr4_find(const struct net_device *dev) 643 { 644 struct in_device *in_dev; 645 struct in_ifaddr *ifa; 646 647 in_dev = __in_dev_get_rcu(dev); 648 if (!in_dev) 649 return 0; 650 651 /* It is unclear from RFC 5837 which IP address should be chosen, but 652 * it makes sense to choose a global unicast address. 653 */ 654 in_dev_for_each_ifa_rcu(ifa, in_dev) { 655 if (READ_ONCE(ifa->ifa_flags) & IFA_F_SECONDARY) 656 continue; 657 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || 658 ipv4_is_multicast(ifa->ifa_address)) 659 continue; 660 return ifa->ifa_address; 661 } 662 663 return 0; 664 } 665 666 static void icmp_ext_iio_iif_append(struct net *net, struct sk_buff *skb, 667 int iif) 668 { 669 struct icmp_ext_iio_name_subobj *name_subobj; 670 struct icmp_extobj_hdr *objh; 671 struct net_device *dev; 672 __be32 data; 673 674 if (!iif) 675 return; 676 677 /* Add the fields in the order specified by RFC 5837. */ 678 objh = skb_put(skb, sizeof(*objh)); 679 objh->class_num = ICMP_EXT_OBJ_CLASS_IIO; 680 objh->class_type = ICMP_EXT_CTYPE_IIO_ROLE(ICMP_EXT_CTYPE_IIO_ROLE_IIF); 681 682 data = htonl(iif); 683 skb_put_data(skb, &data, sizeof(__be32)); 684 objh->class_type |= ICMP_EXT_CTYPE_IIO_IFINDEX; 685 686 rcu_read_lock(); 687 688 dev = dev_get_by_index_rcu(net, iif); 689 if (!dev) 690 goto out; 691 692 data = icmp_ext_iio_addr4_find(dev); 693 if (data) { 694 struct icmp_ext_iio_addr4_subobj *addr4_subobj; 695 696 addr4_subobj = skb_put_zero(skb, sizeof(*addr4_subobj)); 697 addr4_subobj->afi = htons(ICMP_AFI_IP); 698 addr4_subobj->addr4 = data; 699 objh->class_type |= ICMP_EXT_CTYPE_IIO_IPADDR; 700 } 701 702 name_subobj = skb_put_zero(skb, ALIGN(sizeof(*name_subobj), 4)); 703 name_subobj->len = ALIGN(sizeof(*name_subobj), 4); 704 netdev_copy_name(dev, name_subobj->name); 705 objh->class_type |= ICMP_EXT_CTYPE_IIO_NAME; 706 707 data = htonl(READ_ONCE(dev->mtu)); 708 skb_put_data(skb, &data, sizeof(__be32)); 709 objh->class_type |= ICMP_EXT_CTYPE_IIO_MTU; 710 711 out: 712 rcu_read_unlock(); 713 objh->length = htons(skb_tail_pointer(skb) - (unsigned char *)objh); 714 } 715 716 static void icmp_ext_objs_append(struct net *net, struct sk_buff *skb, 717 u8 ext_objs, int iif) 718 { 719 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 720 icmp_ext_iio_iif_append(net, skb, iif); 721 } 722 723 static struct sk_buff * 724 icmp_ext_append(struct net *net, struct sk_buff *skb_in, struct icmphdr *icmph, 725 unsigned int room, int iif) 726 { 727 unsigned int payload_len, ext_max_len, ext_len; 728 struct icmp_ext_hdr *ext_hdr; 729 struct sk_buff *skb; 730 u8 ext_objs; 731 int nhoff; 732 733 switch (icmph->type) { 734 case ICMP_DEST_UNREACH: 735 case ICMP_TIME_EXCEEDED: 736 case ICMP_PARAMETERPROB: 737 break; 738 default: 739 return NULL; 740 } 741 742 ext_objs = READ_ONCE(net->ipv4.sysctl_icmp_errors_extension_mask); 743 if (!ext_objs) 744 return NULL; 745 746 ext_max_len = icmp_ext_max_len(ext_objs); 747 if (ICMP_EXT_ORIG_DGRAM_MIN_LEN + ext_max_len > room) 748 return NULL; 749 750 skb = skb_clone(skb_in, GFP_ATOMIC); 751 if (!skb) 752 return NULL; 753 754 nhoff = skb_network_offset(skb); 755 payload_len = min(skb->len - nhoff, ICMP_EXT_ORIG_DGRAM_MIN_LEN); 756 757 if (!pskb_network_may_pull(skb, payload_len)) 758 goto free_skb; 759 760 if (pskb_trim(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN) || 761 __skb_put_padto(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN, false)) 762 goto free_skb; 763 764 if (pskb_expand_head(skb, 0, ext_max_len, GFP_ATOMIC)) 765 goto free_skb; 766 767 ext_hdr = skb_put_zero(skb, sizeof(*ext_hdr)); 768 ext_hdr->version = ICMP_EXT_VERSION_2; 769 770 icmp_ext_objs_append(net, skb, ext_objs, iif); 771 772 /* Do not send an empty extension structure. */ 773 ext_len = skb_tail_pointer(skb) - (unsigned char *)ext_hdr; 774 if (ext_len == sizeof(*ext_hdr)) 775 goto free_skb; 776 777 ext_hdr->checksum = ip_compute_csum(ext_hdr, ext_len); 778 /* The length of the original datagram in 32-bit words (RFC 4884). */ 779 icmph->un.reserved[1] = ICMP_EXT_ORIG_DGRAM_MIN_LEN / sizeof(u32); 780 781 return skb; 782 783 free_skb: 784 consume_skb(skb); 785 return NULL; 786 } 787 788 /* 789 * Send an ICMP message in response to a situation 790 * 791 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 792 * MAY send more (we do). 793 * MUST NOT change this header information. 794 * MUST NOT reply to a multicast/broadcast IP address. 795 * MUST NOT reply to a multicast/broadcast MAC address. 796 * MUST reply to only the first fragment. 797 */ 798 799 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 800 const struct inet_skb_parm *parm) 801 { 802 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 803 IP_OPTIONS_DATA_FIXED_SIZE); 804 struct iphdr *iph; 805 int room; 806 struct rtable *rt = skb_rtable(skb_in); 807 bool apply_ratelimit = false; 808 struct sk_buff *ext_skb; 809 struct ipcm_cookie ipc; 810 struct flowi4 fl4; 811 __be32 saddr; 812 u8 tos; 813 u32 mark; 814 struct net *net; 815 struct sock *sk; 816 817 if (!rt) 818 return; 819 820 rcu_read_lock(); 821 822 if (rt->dst.dev) 823 net = dev_net_rcu(rt->dst.dev); 824 else if (skb_in->dev) 825 net = dev_net_rcu(skb_in->dev); 826 else 827 goto out; 828 829 /* 830 * Find the original header. It is expected to be valid, of course. 831 * Check this, icmp_send is called from the most obscure devices 832 * sometimes. 833 */ 834 iph = ip_hdr(skb_in); 835 836 if ((u8 *)iph < skb_in->head || 837 (skb_network_header(skb_in) + sizeof(*iph)) > 838 skb_tail_pointer(skb_in)) 839 goto out; 840 841 /* 842 * No replies to physical multicast/broadcast 843 */ 844 if (skb_in->pkt_type != PACKET_HOST) 845 goto out; 846 847 /* 848 * Now check at the protocol level 849 */ 850 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 851 goto out; 852 853 /* 854 * Only reply to fragment 0. We byte re-order the constant 855 * mask for efficiency. 856 */ 857 if (iph->frag_off & htons(IP_OFFSET)) 858 goto out; 859 860 /* 861 * If we send an ICMP error to an ICMP error a mess would result.. 862 */ 863 if (icmp_pointers[type].error) { 864 /* 865 * We are an error, check if we are replying to an 866 * ICMP error 867 */ 868 if (iph->protocol == IPPROTO_ICMP) { 869 u8 _inner_type, *itp; 870 871 itp = skb_header_pointer(skb_in, 872 skb_network_header(skb_in) + 873 (iph->ihl << 2) + 874 offsetof(struct icmphdr, 875 type) - 876 skb_in->data, 877 sizeof(_inner_type), 878 &_inner_type); 879 if (!itp) 880 goto out; 881 882 /* 883 * Assume any unknown ICMP type is an error. This 884 * isn't specified by the RFC, but think about it.. 885 */ 886 if (*itp > NR_ICMP_TYPES || 887 icmp_pointers[*itp].error) 888 goto out; 889 } 890 } 891 892 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 893 local_bh_disable(); 894 895 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 896 * incoming dev is loopback. If outgoing dev change to not be 897 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 898 */ 899 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 900 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 901 goto out_bh_enable; 902 903 sk = icmp_xmit_lock(net); 904 if (!sk) 905 goto out_bh_enable; 906 907 /* 908 * Construct source address and options. 909 */ 910 911 saddr = iph->daddr; 912 if (!(rt->rt_flags & RTCF_LOCAL)) { 913 struct net_device *dev = NULL; 914 915 rcu_read_lock(); 916 if (rt_is_input_route(rt) && 917 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 918 dev = dev_get_by_index_rcu(net, parm->iif ? parm->iif : 919 inet_iif(skb_in)); 920 921 if (dev) 922 saddr = inet_select_addr(dev, iph->saddr, 923 RT_SCOPE_LINK); 924 else 925 saddr = 0; 926 rcu_read_unlock(); 927 } 928 929 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 930 IPTOS_PREC_INTERNETCONTROL) : 931 iph->tos; 932 mark = IP4_REPLY_MARK(net, skb_in->mark); 933 934 if (__ip_options_echo(net, &icmp_param->replyopts.opt, skb_in, 935 &parm->opt)) 936 goto out_unlock; 937 938 939 /* 940 * Prepare data for ICMP header. 941 */ 942 943 icmp_param->data.icmph.type = type; 944 icmp_param->data.icmph.code = code; 945 icmp_param->data.icmph.un.gateway = info; 946 icmp_param->data.icmph.checksum = 0; 947 icmp_param->skb = skb_in; 948 icmp_param->offset = skb_network_offset(skb_in); 949 ipcm_init(&ipc); 950 ipc.tos = tos; 951 ipc.addr = iph->saddr; 952 ipc.opt = &icmp_param->replyopts; 953 ipc.sockc.mark = mark; 954 955 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 956 inet_dsfield_to_dscp(tos), mark, type, code, 957 icmp_param); 958 if (IS_ERR(rt)) 959 goto out_unlock; 960 961 /* peer icmp_ratelimit */ 962 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 963 goto ende; 964 965 /* RFC says return as much as we can without exceeding 576 bytes. */ 966 967 room = dst4_mtu(&rt->dst); 968 if (room > 576) 969 room = 576; 970 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.optlen; 971 room -= sizeof(struct icmphdr); 972 /* Guard against tiny mtu. We need to include at least one 973 * IP network header for this message to make any sense. 974 */ 975 if (room <= (int)sizeof(struct iphdr)) 976 goto ende; 977 978 ext_skb = icmp_ext_append(net, skb_in, &icmp_param->data.icmph, room, 979 parm->iif); 980 if (ext_skb) 981 icmp_param->skb = ext_skb; 982 983 icmp_param->data_len = icmp_param->skb->len - icmp_param->offset; 984 if (icmp_param->data_len > room) 985 icmp_param->data_len = room; 986 icmp_param->head_len = sizeof(struct icmphdr); 987 988 /* if we don't have a source address at this point, fall back to the 989 * dummy address instead of sending out a packet with a source address 990 * of 0.0.0.0 991 */ 992 if (!fl4.saddr) 993 fl4.saddr = htonl(INADDR_DUMMY); 994 995 trace_icmp_send(skb_in, type, code); 996 997 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 998 999 if (ext_skb) 1000 consume_skb(ext_skb); 1001 ende: 1002 ip_rt_put(rt); 1003 out_unlock: 1004 icmp_xmit_unlock(sk); 1005 out_bh_enable: 1006 local_bh_enable(); 1007 out: 1008 rcu_read_unlock(); 1009 } 1010 EXPORT_SYMBOL(__icmp_send); 1011 1012 #if IS_ENABLED(CONFIG_NF_NAT) 1013 #include <net/netfilter/nf_conntrack.h> 1014 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 1015 { 1016 struct sk_buff *cloned_skb = NULL; 1017 enum ip_conntrack_info ctinfo; 1018 enum ip_conntrack_dir dir; 1019 struct inet_skb_parm parm; 1020 struct nf_conn *ct; 1021 __be32 orig_ip; 1022 1023 memset(&parm, 0, sizeof(parm)); 1024 ct = nf_ct_get(skb_in, &ctinfo); 1025 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { 1026 __icmp_send(skb_in, type, code, info, &parm); 1027 return; 1028 } 1029 1030 if (skb_shared(skb_in)) 1031 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 1032 1033 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 1034 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 1035 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 1036 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 1037 goto out; 1038 1039 orig_ip = ip_hdr(skb_in)->saddr; 1040 dir = CTINFO2DIR(ctinfo); 1041 ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; 1042 __icmp_send(skb_in, type, code, info, &parm); 1043 ip_hdr(skb_in)->saddr = orig_ip; 1044 out: 1045 consume_skb(cloned_skb); 1046 } 1047 EXPORT_SYMBOL(icmp_ndo_send); 1048 #endif 1049 1050 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 1051 { 1052 const struct iphdr *iph = (const struct iphdr *)skb->data; 1053 const struct net_protocol *ipprot; 1054 int protocol = iph->protocol; 1055 1056 /* Checkin full IP header plus 8 bytes of protocol to 1057 * avoid additional coding at protocol handlers. 1058 */ 1059 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 1060 goto out; 1061 1062 /* IPPROTO_RAW sockets are not supposed to receive anything. */ 1063 if (protocol == IPPROTO_RAW) 1064 goto out; 1065 1066 raw_icmp_error(skb, protocol, info); 1067 1068 ipprot = rcu_dereference(inet_protos[protocol]); 1069 if (ipprot && ipprot->err_handler) 1070 ipprot->err_handler(skb, info); 1071 return; 1072 1073 out: 1074 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1075 } 1076 1077 static bool icmp_tag_validation(int proto) 1078 { 1079 const struct net_protocol *ipprot; 1080 bool ok; 1081 1082 rcu_read_lock(); 1083 ipprot = rcu_dereference(inet_protos[proto]); 1084 ok = ipprot ? ipprot->icmp_strict_tag_validation : false; 1085 rcu_read_unlock(); 1086 return ok; 1087 } 1088 1089 /* 1090 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 1091 * ICMP_PARAMETERPROB. 1092 */ 1093 1094 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 1095 { 1096 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 1097 const struct iphdr *iph; 1098 struct icmphdr *icmph; 1099 struct net *net; 1100 u32 info = 0; 1101 1102 net = skb_dst_dev_net_rcu(skb); 1103 1104 /* 1105 * Incomplete header ? 1106 * Only checks for the IP header, there should be an 1107 * additional check for longer headers in upper levels. 1108 */ 1109 1110 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 1111 goto out_err; 1112 1113 icmph = icmp_hdr(skb); 1114 iph = (const struct iphdr *)skb->data; 1115 1116 if (iph->ihl < 5) { /* Mangled header, drop. */ 1117 reason = SKB_DROP_REASON_IP_INHDR; 1118 goto out_err; 1119 } 1120 1121 switch (icmph->type) { 1122 case ICMP_DEST_UNREACH: 1123 switch (icmph->code & 15) { 1124 case ICMP_NET_UNREACH: 1125 case ICMP_HOST_UNREACH: 1126 case ICMP_PROT_UNREACH: 1127 case ICMP_PORT_UNREACH: 1128 break; 1129 case ICMP_FRAG_NEEDED: 1130 /* for documentation of the ip_no_pmtu_disc 1131 * values please see 1132 * Documentation/networking/ip-sysctl.rst 1133 */ 1134 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 1135 default: 1136 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 1137 &iph->daddr); 1138 break; 1139 case 2: 1140 goto out; 1141 case 3: 1142 if (!icmp_tag_validation(iph->protocol)) 1143 goto out; 1144 fallthrough; 1145 case 0: 1146 info = ntohs(icmph->un.frag.mtu); 1147 } 1148 break; 1149 case ICMP_SR_FAILED: 1150 net_dbg_ratelimited("%pI4: Source Route Failed\n", 1151 &iph->daddr); 1152 break; 1153 default: 1154 break; 1155 } 1156 if (icmph->code > NR_ICMP_UNREACH) 1157 goto out; 1158 break; 1159 case ICMP_PARAMETERPROB: 1160 info = ntohl(icmph->un.gateway) >> 24; 1161 break; 1162 case ICMP_TIME_EXCEEDED: 1163 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 1164 if (icmph->code == ICMP_EXC_FRAGTIME) 1165 goto out; 1166 break; 1167 } 1168 1169 /* 1170 * Throw it at our lower layers 1171 * 1172 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 1173 * header. 1174 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 1175 * transport layer. 1176 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 1177 * transport layer. 1178 */ 1179 1180 /* 1181 * Check the other end isn't violating RFC 1122. Some routers send 1182 * bogus responses to broadcast frames. If you see this message 1183 * first check your netmask matches at both ends, if it does then 1184 * get the other vendor to fix their kit. 1185 */ 1186 1187 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 1188 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 1189 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 1190 &ip_hdr(skb)->saddr, 1191 icmph->type, icmph->code, 1192 &iph->daddr, skb->dev->name); 1193 goto out; 1194 } 1195 1196 icmp_socket_deliver(skb, info); 1197 1198 out: 1199 return reason; 1200 out_err: 1201 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1202 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 1203 } 1204 1205 1206 /* 1207 * Handle ICMP_REDIRECT. 1208 */ 1209 1210 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 1211 { 1212 if (skb->len < sizeof(struct iphdr)) { 1213 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1214 return SKB_DROP_REASON_PKT_TOO_SMALL; 1215 } 1216 1217 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 1218 /* there aught to be a stat */ 1219 return SKB_DROP_REASON_NOMEM; 1220 } 1221 1222 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 1223 return SKB_NOT_DROPPED_YET; 1224 } 1225 1226 /* 1227 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1228 * 1229 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1230 * requests. 1231 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1232 * included in the reply. 1233 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1234 * echo requests, MUST have default=NOT. 1235 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1236 * Extended Echo Functionality, MUST be disabled by default 1237 * See also WRT handling of options once they are done and working. 1238 */ 1239 1240 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1241 { 1242 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1243 IP_OPTIONS_DATA_FIXED_SIZE); 1244 struct net *net; 1245 1246 net = skb_dst_dev_net_rcu(skb); 1247 /* should there be an ICMP stat for ignored echos? */ 1248 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1249 return SKB_NOT_DROPPED_YET; 1250 1251 icmp_param->data.icmph = *icmp_hdr(skb); 1252 icmp_param->skb = skb; 1253 icmp_param->offset = 0; 1254 icmp_param->data_len = skb->len; 1255 icmp_param->head_len = sizeof(struct icmphdr); 1256 1257 if (icmp_param->data.icmph.type == ICMP_ECHO) 1258 icmp_param->data.icmph.type = ICMP_ECHOREPLY; 1259 else if (!icmp_build_probe(skb, &icmp_param->data.icmph)) 1260 return SKB_NOT_DROPPED_YET; 1261 1262 icmp_reply(icmp_param, skb); 1263 return SKB_NOT_DROPPED_YET; 1264 } 1265 1266 /* Helper for icmp_echo and icmpv6_echo_reply. 1267 * Searches for net_device that matches PROBE interface identifier 1268 * and builds PROBE reply message in icmphdr. 1269 * 1270 * Returns false if PROBE responses are disabled via sysctl 1271 */ 1272 1273 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1274 { 1275 struct net *net = dev_net_rcu(skb->dev); 1276 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1277 struct icmp_ext_echo_iio *iio, _iio; 1278 struct inet6_dev *in6_dev; 1279 struct in_device *in_dev; 1280 struct net_device *dev; 1281 char buff[IFNAMSIZ]; 1282 u16 ident_len; 1283 u8 status; 1284 1285 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1286 return false; 1287 1288 /* We currently only support probing interfaces on the proxy node 1289 * Check to ensure L-bit is set 1290 */ 1291 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1292 return false; 1293 /* Clear status bits in reply message */ 1294 icmphdr->un.echo.sequence &= htons(0xFF00); 1295 if (icmphdr->type == ICMP_EXT_ECHO) 1296 icmphdr->type = ICMP_EXT_ECHOREPLY; 1297 else 1298 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1299 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1300 /* Size of iio is class_type dependent. 1301 * Only check header here and assign length based on ctype in the switch statement 1302 */ 1303 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1304 if (!ext_hdr || !iio) 1305 goto send_mal_query; 1306 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1307 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1308 goto send_mal_query; 1309 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1310 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1311 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1312 if (!iio) 1313 goto send_mal_query; 1314 1315 status = 0; 1316 dev = NULL; 1317 switch (iio->extobj_hdr.class_type) { 1318 case ICMP_EXT_ECHO_CTYPE_NAME: 1319 if (ident_len >= IFNAMSIZ) 1320 goto send_mal_query; 1321 memset(buff, 0, sizeof(buff)); 1322 memcpy(buff, &iio->ident.name, ident_len); 1323 dev = dev_get_by_name(net, buff); 1324 break; 1325 case ICMP_EXT_ECHO_CTYPE_INDEX: 1326 if (ident_len != sizeof(iio->ident.ifindex)) 1327 goto send_mal_query; 1328 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1329 break; 1330 case ICMP_EXT_ECHO_CTYPE_ADDR: 1331 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1332 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1333 iio->ident.addr.ctype3_hdr.addrlen) 1334 goto send_mal_query; 1335 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1336 case ICMP_AFI_IP: 1337 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1338 goto send_mal_query; 1339 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1340 break; 1341 #if IS_ENABLED(CONFIG_IPV6) 1342 case ICMP_AFI_IP6: 1343 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1344 goto send_mal_query; 1345 dev = ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1346 dev_hold(dev); 1347 break; 1348 #endif 1349 default: 1350 goto send_mal_query; 1351 } 1352 break; 1353 default: 1354 goto send_mal_query; 1355 } 1356 if (!dev) { 1357 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1358 return true; 1359 } 1360 /* Fill bits in reply message */ 1361 if (dev->flags & IFF_UP) 1362 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1363 1364 in_dev = __in_dev_get_rcu(dev); 1365 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1366 status |= ICMP_EXT_ECHOREPLY_IPV4; 1367 1368 in6_dev = __in6_dev_get(dev); 1369 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1370 status |= ICMP_EXT_ECHOREPLY_IPV6; 1371 1372 dev_put(dev); 1373 icmphdr->un.echo.sequence |= htons(status); 1374 return true; 1375 send_mal_query: 1376 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1377 return true; 1378 } 1379 1380 /* 1381 * Handle ICMP Timestamp requests. 1382 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1383 * SHOULD be in the kernel for minimum random latency. 1384 * MUST be accurate to a few minutes. 1385 * MUST be updated at least at 15Hz. 1386 */ 1387 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1388 { 1389 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1390 IP_OPTIONS_DATA_FIXED_SIZE); 1391 /* 1392 * Too short. 1393 */ 1394 if (skb->len < 4) 1395 goto out_err; 1396 1397 /* 1398 * Fill in the current time as ms since midnight UT: 1399 */ 1400 icmp_param->data.times[1] = inet_current_timestamp(); 1401 icmp_param->data.times[2] = icmp_param->data.times[1]; 1402 1403 BUG_ON(skb_copy_bits(skb, 0, &icmp_param->data.times[0], 4)); 1404 1405 icmp_param->data.icmph = *icmp_hdr(skb); 1406 icmp_param->data.icmph.type = ICMP_TIMESTAMPREPLY; 1407 icmp_param->data.icmph.code = 0; 1408 icmp_param->skb = skb; 1409 icmp_param->offset = 0; 1410 icmp_param->data_len = 0; 1411 icmp_param->head_len = sizeof(struct icmphdr) + 12; 1412 icmp_reply(icmp_param, skb); 1413 return SKB_NOT_DROPPED_YET; 1414 1415 out_err: 1416 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS); 1417 return SKB_DROP_REASON_PKT_TOO_SMALL; 1418 } 1419 1420 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1421 { 1422 /* pretend it was a success */ 1423 return SKB_NOT_DROPPED_YET; 1424 } 1425 1426 /* 1427 * Deal with incoming ICMP packets. 1428 */ 1429 int icmp_rcv(struct sk_buff *skb) 1430 { 1431 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1432 struct rtable *rt = skb_rtable(skb); 1433 struct net *net = dev_net_rcu(rt->dst.dev); 1434 struct icmphdr *icmph; 1435 1436 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1437 struct sec_path *sp = skb_sec_path(skb); 1438 int nh; 1439 1440 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1441 XFRM_STATE_ICMP)) { 1442 reason = SKB_DROP_REASON_XFRM_POLICY; 1443 goto drop; 1444 } 1445 1446 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1447 goto drop; 1448 1449 nh = skb_network_offset(skb); 1450 skb_set_network_header(skb, sizeof(*icmph)); 1451 1452 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1453 skb)) { 1454 reason = SKB_DROP_REASON_XFRM_POLICY; 1455 goto drop; 1456 } 1457 1458 skb_set_network_header(skb, nh); 1459 } 1460 1461 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1462 1463 if (skb_checksum_simple_validate(skb)) 1464 goto csum_error; 1465 1466 if (!pskb_pull(skb, sizeof(*icmph))) 1467 goto error; 1468 1469 icmph = icmp_hdr(skb); 1470 1471 ICMPMSGIN_INC_STATS(net, icmph->type); 1472 1473 /* Check for ICMP Extended Echo (PROBE) messages */ 1474 if (icmph->type == ICMP_EXT_ECHO) { 1475 /* We can't use icmp_pointers[].handler() because it is an array of 1476 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1477 */ 1478 reason = icmp_echo(skb); 1479 goto reason_check; 1480 } 1481 1482 /* 1483 * Parse the ICMP message 1484 */ 1485 1486 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1487 /* 1488 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1489 * silently ignored (we let user decide with a sysctl). 1490 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1491 * discarded if to broadcast/multicast. 1492 */ 1493 if ((icmph->type == ICMP_ECHO || 1494 icmph->type == ICMP_TIMESTAMP) && 1495 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1496 reason = SKB_DROP_REASON_INVALID_PROTO; 1497 goto error; 1498 } 1499 if (icmph->type != ICMP_ECHO && 1500 icmph->type != ICMP_TIMESTAMP && 1501 icmph->type != ICMP_ADDRESS && 1502 icmph->type != ICMP_ADDRESSREPLY) { 1503 reason = SKB_DROP_REASON_INVALID_PROTO; 1504 goto error; 1505 } 1506 } 1507 1508 if (icmph->type == ICMP_EXT_ECHOREPLY || 1509 icmph->type == ICMP_ECHOREPLY) { 1510 reason = ping_rcv(skb); 1511 return reason ? NET_RX_DROP : NET_RX_SUCCESS; 1512 } 1513 1514 /* 1515 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1516 * 1517 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1518 * discarded. 1519 */ 1520 if (icmph->type > NR_ICMP_TYPES) { 1521 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1522 goto error; 1523 } 1524 1525 reason = icmp_pointers[icmph->type].handler(skb); 1526 reason_check: 1527 if (!reason) { 1528 consume_skb(skb); 1529 return NET_RX_SUCCESS; 1530 } 1531 1532 drop: 1533 kfree_skb_reason(skb, reason); 1534 return NET_RX_DROP; 1535 csum_error: 1536 reason = SKB_DROP_REASON_ICMP_CSUM; 1537 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1538 error: 1539 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1540 goto drop; 1541 } 1542 1543 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1544 { 1545 struct icmp_extobj_hdr *objh, _objh; 1546 struct icmp_ext_hdr *exth, _exth; 1547 u16 olen; 1548 1549 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1550 if (!exth) 1551 return false; 1552 if (exth->version != 2) 1553 return true; 1554 1555 if (exth->checksum && 1556 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1557 return false; 1558 1559 off += sizeof(_exth); 1560 while (off < skb->len) { 1561 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1562 if (!objh) 1563 return false; 1564 1565 olen = ntohs(objh->length); 1566 if (olen < sizeof(_objh)) 1567 return false; 1568 1569 off += olen; 1570 if (off > skb->len) 1571 return false; 1572 } 1573 1574 return true; 1575 } 1576 1577 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1578 struct sock_ee_data_rfc4884 *out, 1579 int thlen, int off) 1580 { 1581 int hlen; 1582 1583 /* original datagram headers: end of icmph to payload (skb->data) */ 1584 hlen = -skb_transport_offset(skb) - thlen; 1585 1586 /* per rfc 4884: minimal datagram length of 128 bytes */ 1587 if (off < 128 || off < hlen) 1588 return; 1589 1590 /* kernel has stripped headers: return payload offset in bytes */ 1591 off -= hlen; 1592 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1593 return; 1594 1595 out->len = off; 1596 1597 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1598 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1599 } 1600 1601 int icmp_err(struct sk_buff *skb, u32 info) 1602 { 1603 struct iphdr *iph = (struct iphdr *)skb->data; 1604 int offset = iph->ihl<<2; 1605 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1606 struct net *net = dev_net_rcu(skb->dev); 1607 int type = icmp_hdr(skb)->type; 1608 int code = icmp_hdr(skb)->code; 1609 1610 /* 1611 * Use ping_err to handle all icmp errors except those 1612 * triggered by ICMP_ECHOREPLY which sent from kernel. 1613 */ 1614 if (icmph->type != ICMP_ECHOREPLY) { 1615 ping_err(skb, offset, info); 1616 return 0; 1617 } 1618 1619 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1620 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1621 else if (type == ICMP_REDIRECT) 1622 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1623 1624 return 0; 1625 } 1626 1627 /* 1628 * This table is the definition of how we handle ICMP. 1629 */ 1630 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1631 [ICMP_ECHOREPLY] = { 1632 .handler = ping_rcv, 1633 }, 1634 [1] = { 1635 .handler = icmp_discard, 1636 .error = 1, 1637 }, 1638 [2] = { 1639 .handler = icmp_discard, 1640 .error = 1, 1641 }, 1642 [ICMP_DEST_UNREACH] = { 1643 .handler = icmp_unreach, 1644 .error = 1, 1645 }, 1646 [ICMP_SOURCE_QUENCH] = { 1647 .handler = icmp_unreach, 1648 .error = 1, 1649 }, 1650 [ICMP_REDIRECT] = { 1651 .handler = icmp_redirect, 1652 .error = 1, 1653 }, 1654 [6] = { 1655 .handler = icmp_discard, 1656 .error = 1, 1657 }, 1658 [7] = { 1659 .handler = icmp_discard, 1660 .error = 1, 1661 }, 1662 [ICMP_ECHO] = { 1663 .handler = icmp_echo, 1664 }, 1665 [9] = { 1666 .handler = icmp_discard, 1667 .error = 1, 1668 }, 1669 [10] = { 1670 .handler = icmp_discard, 1671 .error = 1, 1672 }, 1673 [ICMP_TIME_EXCEEDED] = { 1674 .handler = icmp_unreach, 1675 .error = 1, 1676 }, 1677 [ICMP_PARAMETERPROB] = { 1678 .handler = icmp_unreach, 1679 .error = 1, 1680 }, 1681 [ICMP_TIMESTAMP] = { 1682 .handler = icmp_timestamp, 1683 }, 1684 [ICMP_TIMESTAMPREPLY] = { 1685 .handler = icmp_discard, 1686 }, 1687 [ICMP_INFO_REQUEST] = { 1688 .handler = icmp_discard, 1689 }, 1690 [ICMP_INFO_REPLY] = { 1691 .handler = icmp_discard, 1692 }, 1693 [ICMP_ADDRESS] = { 1694 .handler = icmp_discard, 1695 }, 1696 [ICMP_ADDRESSREPLY] = { 1697 .handler = icmp_discard, 1698 }, 1699 }; 1700 1701 static int __net_init icmp_sk_init(struct net *net) 1702 { 1703 /* Control parameters for ECHO replies. */ 1704 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1705 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1706 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1707 1708 /* Control parameter - ignore bogus broadcast responses? */ 1709 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1710 1711 /* 1712 * Configurable global rate limit. 1713 * 1714 * ratelimit defines tokens/packet consumed for dst->rate_token 1715 * bucket ratemask defines which icmp types are ratelimited by 1716 * setting it's bit position. 1717 * 1718 * default: 1719 * dest unreachable (3), source quench (4), 1720 * time exceeded (11), parameter problem (12) 1721 */ 1722 1723 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1724 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1725 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1726 net->ipv4.sysctl_icmp_errors_extension_mask = 0; 1727 net->ipv4.sysctl_icmp_msgs_per_sec = 10000; 1728 net->ipv4.sysctl_icmp_msgs_burst = 10000; 1729 1730 return 0; 1731 } 1732 1733 static struct pernet_operations __net_initdata icmp_sk_ops = { 1734 .init = icmp_sk_init, 1735 }; 1736 1737 int __init icmp_init(void) 1738 { 1739 int err, i; 1740 1741 for_each_possible_cpu(i) { 1742 struct sock *sk; 1743 1744 err = inet_ctl_sock_create(&sk, PF_INET, 1745 SOCK_RAW, IPPROTO_ICMP, &init_net); 1746 if (err < 0) 1747 return err; 1748 1749 per_cpu(ipv4_icmp_sk, i) = sk; 1750 1751 /* Enough space for 2 64K ICMP packets, including 1752 * sk_buff/skb_shared_info struct overhead. 1753 */ 1754 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1755 1756 /* 1757 * Speedup sock_wfree() 1758 */ 1759 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1760 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1761 } 1762 return register_pernet_subsys(&icmp_sk_ops); 1763 } 1764