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) * delta / HZ; 254 if (!incr) 255 return false; 256 257 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 258 old = atomic_read(&net->ipv4.icmp_global_credit); 259 do { 260 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 261 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 262 } 263 return true; 264 } 265 EXPORT_SYMBOL(icmp_global_allow); 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 EXPORT_SYMBOL(icmp_global_consume); 276 277 static bool icmpv4_mask_allow(struct net *net, int type, int code) 278 { 279 if (type > NR_ICMP_TYPES) 280 return true; 281 282 /* Don't limit PMTU discovery. */ 283 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 284 return true; 285 286 /* Limit if icmp type is enabled in ratemask. */ 287 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 288 return true; 289 290 return false; 291 } 292 293 static bool icmpv4_global_allow(struct net *net, int type, int code, 294 bool *apply_ratelimit) 295 { 296 if (icmpv4_mask_allow(net, type, code)) 297 return true; 298 299 if (icmp_global_allow(net)) { 300 *apply_ratelimit = true; 301 return true; 302 } 303 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 304 return false; 305 } 306 307 /* 308 * Send an ICMP frame. 309 */ 310 311 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 312 struct flowi4 *fl4, int type, int code, 313 bool apply_ratelimit) 314 { 315 struct dst_entry *dst = &rt->dst; 316 struct inet_peer *peer; 317 struct net_device *dev; 318 bool rc = true; 319 320 if (!apply_ratelimit) 321 return true; 322 323 /* No rate limit on loopback */ 324 rcu_read_lock(); 325 dev = dst_dev_rcu(dst); 326 if (dev && (dev->flags & IFF_LOOPBACK)) 327 goto out; 328 329 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 330 l3mdev_master_ifindex_rcu(dev)); 331 rc = inet_peer_xrlim_allow(peer, 332 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 333 out: 334 rcu_read_unlock(); 335 if (!rc) 336 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 337 else 338 icmp_global_consume(net); 339 return rc; 340 } 341 342 /* 343 * Maintain the counters used in the SNMP statistics for outgoing ICMP 344 */ 345 void icmp_out_count(struct net *net, unsigned char type) 346 { 347 ICMPMSGOUT_INC_STATS(net, type); 348 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 349 } 350 351 /* 352 * Checksum each fragment, and on the first include the headers and final 353 * checksum. 354 */ 355 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 356 struct sk_buff *skb) 357 { 358 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 359 IP_OPTIONS_DATA_FIXED_SIZE); 360 __wsum csum; 361 362 icmp_param = from; 363 364 csum = skb_copy_and_csum_bits(icmp_param->skb, 365 icmp_param->offset + offset, 366 to, len); 367 368 skb->csum = csum_block_add(skb->csum, csum, odd); 369 if (icmp_pointers[icmp_param->data.icmph.type].error) 370 nf_ct_attach(skb, icmp_param->skb); 371 return 0; 372 } 373 374 static void icmp_push_reply(struct sock *sk, 375 struct icmp_bxm *icmp_param, 376 struct flowi4 *fl4, 377 struct ipcm_cookie *ipc, struct rtable **rt) 378 { 379 struct sk_buff *skb; 380 381 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 382 icmp_param->data_len+icmp_param->head_len, 383 icmp_param->head_len, 384 ipc, rt, MSG_DONTWAIT) < 0) { 385 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 386 ip_flush_pending_frames(sk); 387 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 388 struct icmphdr *icmph = icmp_hdr(skb); 389 __wsum csum; 390 struct sk_buff *skb1; 391 392 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 393 (char *)icmph, 394 icmp_param->head_len); 395 skb_queue_walk(&sk->sk_write_queue, skb1) { 396 csum = csum_add(csum, skb1->csum); 397 } 398 icmph->checksum = csum_fold(csum); 399 skb->ip_summed = CHECKSUM_NONE; 400 ip_push_pending_frames(sk, fl4); 401 } 402 } 403 404 /* 405 * Driving logic for building and sending ICMP messages. 406 */ 407 408 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 409 { 410 struct rtable *rt = skb_rtable(skb); 411 struct net *net = dev_net_rcu(rt->dst.dev); 412 bool apply_ratelimit = false; 413 struct ipcm_cookie ipc; 414 struct flowi4 fl4; 415 struct sock *sk; 416 __be32 daddr, saddr; 417 u32 mark = IP4_REPLY_MARK(net, skb->mark); 418 int type = icmp_param->data.icmph.type; 419 int code = icmp_param->data.icmph.code; 420 421 if (ip_options_echo(net, &icmp_param->replyopts.opt, skb)) 422 return; 423 424 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 425 local_bh_disable(); 426 427 /* is global icmp_msgs_per_sec exhausted ? */ 428 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 429 goto out_bh_enable; 430 431 sk = icmp_xmit_lock(net); 432 if (!sk) 433 goto out_bh_enable; 434 435 icmp_param->data.icmph.checksum = 0; 436 437 ipcm_init(&ipc); 438 ipc.tos = ip_hdr(skb)->tos; 439 ipc.sockc.mark = mark; 440 daddr = ipc.addr = ip_hdr(skb)->saddr; 441 saddr = fib_compute_spec_dst(skb); 442 443 if (icmp_param->replyopts.opt.optlen) { 444 ipc.opt = &icmp_param->replyopts; 445 if (ipc.opt->opt.srr) 446 daddr = icmp_param->replyopts.opt.faddr; 447 } 448 memset(&fl4, 0, sizeof(fl4)); 449 fl4.daddr = daddr; 450 fl4.saddr = saddr; 451 fl4.flowi4_mark = mark; 452 fl4.flowi4_uid = sock_net_uid(net, NULL); 453 fl4.flowi4_dscp = ip4h_dscp(ip_hdr(skb)); 454 fl4.flowi4_proto = IPPROTO_ICMP; 455 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 456 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 457 rt = ip_route_output_key(net, &fl4); 458 if (IS_ERR(rt)) 459 goto out_unlock; 460 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 461 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 462 ip_rt_put(rt); 463 out_unlock: 464 icmp_xmit_unlock(sk); 465 out_bh_enable: 466 local_bh_enable(); 467 } 468 469 /* 470 * The device used for looking up which routing table to use for sending an ICMP 471 * error is preferably the source whenever it is set, which should ensure the 472 * icmp error can be sent to the source host, else lookup using the routing 473 * table of the destination device, else use the main routing table (index 0). 474 */ 475 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 476 { 477 struct net_device *dev = skb->dev; 478 const struct dst_entry *dst; 479 480 if (dev) 481 return dev; 482 dst = skb_dst(skb); 483 return dst ? dst_dev(dst) : NULL; 484 } 485 486 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 487 struct sk_buff *skb_in, 488 const struct iphdr *iph, __be32 saddr, 489 dscp_t dscp, u32 mark, int type, 490 int code, struct icmp_bxm *param) 491 { 492 struct net_device *route_lookup_dev; 493 struct dst_entry *dst, *dst2; 494 struct rtable *rt, *rt2; 495 struct flowi4 fl4_dec; 496 int err; 497 498 memset(fl4, 0, sizeof(*fl4)); 499 fl4->daddr = (param->replyopts.opt.srr ? 500 param->replyopts.opt.faddr : iph->saddr); 501 fl4->saddr = saddr; 502 fl4->flowi4_mark = mark; 503 fl4->flowi4_uid = sock_net_uid(net, NULL); 504 fl4->flowi4_dscp = dscp; 505 fl4->flowi4_proto = IPPROTO_ICMP; 506 fl4->fl4_icmp_type = type; 507 fl4->fl4_icmp_code = code; 508 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 509 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 510 511 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 512 rt = ip_route_output_key_hash(net, fl4, skb_in); 513 if (IS_ERR(rt)) 514 return rt; 515 516 /* No need to clone since we're just using its address. */ 517 rt2 = rt; 518 519 dst = xfrm_lookup(net, &rt->dst, 520 flowi4_to_flowi(fl4), NULL, 0); 521 rt = dst_rtable(dst); 522 if (!IS_ERR(dst)) { 523 if (rt != rt2) 524 return rt; 525 if (inet_addr_type_dev_table(net, route_lookup_dev, 526 fl4->daddr) == RTN_LOCAL) 527 return rt; 528 } else if (PTR_ERR(dst) == -EPERM) { 529 rt = NULL; 530 } else { 531 return rt; 532 } 533 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 534 if (err) 535 goto relookup_failed; 536 537 if (inet_addr_type_dev_table(net, route_lookup_dev, 538 fl4_dec.saddr) == RTN_LOCAL) { 539 rt2 = __ip_route_output_key(net, &fl4_dec); 540 if (IS_ERR(rt2)) 541 err = PTR_ERR(rt2); 542 } else { 543 struct flowi4 fl4_2 = {}; 544 unsigned long orefdst; 545 546 fl4_2.daddr = fl4_dec.saddr; 547 rt2 = ip_route_output_key(net, &fl4_2); 548 if (IS_ERR(rt2)) { 549 err = PTR_ERR(rt2); 550 goto relookup_failed; 551 } 552 /* Ugh! */ 553 orefdst = skb_dstref_steal(skb_in); 554 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 555 dscp, rt2->dst.dev) ? -EINVAL : 0; 556 557 dst_release(&rt2->dst); 558 rt2 = skb_rtable(skb_in); 559 /* steal dst entry from skb_in, don't drop refcnt */ 560 skb_dstref_steal(skb_in); 561 skb_dstref_restore(skb_in, orefdst); 562 563 /* 564 * At this point, fl4_dec.daddr should NOT be local (we 565 * checked fl4_dec.saddr above). However, a race condition 566 * may occur if the address is added to the interface 567 * concurrently. In that case, ip_route_input() returns a 568 * LOCAL route with dst.output=ip_rt_bug, which must not 569 * be used for output. 570 */ 571 if (!err && rt2 && rt2->rt_type == RTN_LOCAL) { 572 net_warn_ratelimited("detected local route for %pI4 during ICMP sending, src %pI4\n", 573 &fl4_dec.daddr, &fl4_dec.saddr); 574 dst_release(&rt2->dst); 575 err = -EINVAL; 576 } 577 } 578 579 if (err) 580 goto relookup_failed; 581 582 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 583 XFRM_LOOKUP_ICMP); 584 rt2 = dst_rtable(dst2); 585 if (!IS_ERR(dst2)) { 586 dst_release(&rt->dst); 587 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 588 rt = rt2; 589 } else if (PTR_ERR(dst2) == -EPERM) { 590 if (rt) 591 dst_release(&rt->dst); 592 return rt2; 593 } else { 594 err = PTR_ERR(dst2); 595 goto relookup_failed; 596 } 597 return rt; 598 599 relookup_failed: 600 if (rt) 601 return rt; 602 return ERR_PTR(err); 603 } 604 605 struct icmp_ext_iio_addr4_subobj { 606 __be16 afi; 607 __be16 reserved; 608 __be32 addr4; 609 }; 610 611 static unsigned int icmp_ext_iio_len(void) 612 { 613 return sizeof(struct icmp_extobj_hdr) + 614 /* ifIndex */ 615 sizeof(__be32) + 616 /* Interface Address Sub-Object */ 617 sizeof(struct icmp_ext_iio_addr4_subobj) + 618 /* Interface Name Sub-Object. Length must be a multiple of 4 619 * bytes. 620 */ 621 ALIGN(sizeof(struct icmp_ext_iio_name_subobj), 4) + 622 /* MTU */ 623 sizeof(__be32); 624 } 625 626 static unsigned int icmp_ext_max_len(u8 ext_objs) 627 { 628 unsigned int ext_max_len; 629 630 ext_max_len = sizeof(struct icmp_ext_hdr); 631 632 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 633 ext_max_len += icmp_ext_iio_len(); 634 635 return ext_max_len; 636 } 637 638 static __be32 icmp_ext_iio_addr4_find(const struct net_device *dev) 639 { 640 struct in_device *in_dev; 641 struct in_ifaddr *ifa; 642 643 in_dev = __in_dev_get_rcu(dev); 644 if (!in_dev) 645 return 0; 646 647 /* It is unclear from RFC 5837 which IP address should be chosen, but 648 * it makes sense to choose a global unicast address. 649 */ 650 in_dev_for_each_ifa_rcu(ifa, in_dev) { 651 if (READ_ONCE(ifa->ifa_flags) & IFA_F_SECONDARY) 652 continue; 653 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || 654 ipv4_is_multicast(ifa->ifa_address)) 655 continue; 656 return ifa->ifa_address; 657 } 658 659 return 0; 660 } 661 662 static void icmp_ext_iio_iif_append(struct net *net, struct sk_buff *skb, 663 int iif) 664 { 665 struct icmp_ext_iio_name_subobj *name_subobj; 666 struct icmp_extobj_hdr *objh; 667 struct net_device *dev; 668 __be32 data; 669 670 if (!iif) 671 return; 672 673 /* Add the fields in the order specified by RFC 5837. */ 674 objh = skb_put(skb, sizeof(*objh)); 675 objh->class_num = ICMP_EXT_OBJ_CLASS_IIO; 676 objh->class_type = ICMP_EXT_CTYPE_IIO_ROLE(ICMP_EXT_CTYPE_IIO_ROLE_IIF); 677 678 data = htonl(iif); 679 skb_put_data(skb, &data, sizeof(__be32)); 680 objh->class_type |= ICMP_EXT_CTYPE_IIO_IFINDEX; 681 682 rcu_read_lock(); 683 684 dev = dev_get_by_index_rcu(net, iif); 685 if (!dev) 686 goto out; 687 688 data = icmp_ext_iio_addr4_find(dev); 689 if (data) { 690 struct icmp_ext_iio_addr4_subobj *addr4_subobj; 691 692 addr4_subobj = skb_put_zero(skb, sizeof(*addr4_subobj)); 693 addr4_subobj->afi = htons(ICMP_AFI_IP); 694 addr4_subobj->addr4 = data; 695 objh->class_type |= ICMP_EXT_CTYPE_IIO_IPADDR; 696 } 697 698 name_subobj = skb_put_zero(skb, ALIGN(sizeof(*name_subobj), 4)); 699 name_subobj->len = ALIGN(sizeof(*name_subobj), 4); 700 netdev_copy_name(dev, name_subobj->name); 701 objh->class_type |= ICMP_EXT_CTYPE_IIO_NAME; 702 703 data = htonl(READ_ONCE(dev->mtu)); 704 skb_put_data(skb, &data, sizeof(__be32)); 705 objh->class_type |= ICMP_EXT_CTYPE_IIO_MTU; 706 707 out: 708 rcu_read_unlock(); 709 objh->length = htons(skb_tail_pointer(skb) - (unsigned char *)objh); 710 } 711 712 static void icmp_ext_objs_append(struct net *net, struct sk_buff *skb, 713 u8 ext_objs, int iif) 714 { 715 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 716 icmp_ext_iio_iif_append(net, skb, iif); 717 } 718 719 static struct sk_buff * 720 icmp_ext_append(struct net *net, struct sk_buff *skb_in, struct icmphdr *icmph, 721 unsigned int room, int iif) 722 { 723 unsigned int payload_len, ext_max_len, ext_len; 724 struct icmp_ext_hdr *ext_hdr; 725 struct sk_buff *skb; 726 u8 ext_objs; 727 int nhoff; 728 729 switch (icmph->type) { 730 case ICMP_DEST_UNREACH: 731 case ICMP_TIME_EXCEEDED: 732 case ICMP_PARAMETERPROB: 733 break; 734 default: 735 return NULL; 736 } 737 738 ext_objs = READ_ONCE(net->ipv4.sysctl_icmp_errors_extension_mask); 739 if (!ext_objs) 740 return NULL; 741 742 ext_max_len = icmp_ext_max_len(ext_objs); 743 if (ICMP_EXT_ORIG_DGRAM_MIN_LEN + ext_max_len > room) 744 return NULL; 745 746 skb = skb_clone(skb_in, GFP_ATOMIC); 747 if (!skb) 748 return NULL; 749 750 nhoff = skb_network_offset(skb); 751 payload_len = min(skb->len - nhoff, ICMP_EXT_ORIG_DGRAM_MIN_LEN); 752 753 if (!pskb_network_may_pull(skb, payload_len)) 754 goto free_skb; 755 756 if (pskb_trim(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN) || 757 __skb_put_padto(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN, false)) 758 goto free_skb; 759 760 if (pskb_expand_head(skb, 0, ext_max_len, GFP_ATOMIC)) 761 goto free_skb; 762 763 ext_hdr = skb_put_zero(skb, sizeof(*ext_hdr)); 764 ext_hdr->version = ICMP_EXT_VERSION_2; 765 766 icmp_ext_objs_append(net, skb, ext_objs, iif); 767 768 /* Do not send an empty extension structure. */ 769 ext_len = skb_tail_pointer(skb) - (unsigned char *)ext_hdr; 770 if (ext_len == sizeof(*ext_hdr)) 771 goto free_skb; 772 773 ext_hdr->checksum = ip_compute_csum(ext_hdr, ext_len); 774 /* The length of the original datagram in 32-bit words (RFC 4884). */ 775 icmph->un.reserved[1] = ICMP_EXT_ORIG_DGRAM_MIN_LEN / sizeof(u32); 776 777 return skb; 778 779 free_skb: 780 consume_skb(skb); 781 return NULL; 782 } 783 784 /* 785 * Send an ICMP message in response to a situation 786 * 787 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 788 * MAY send more (we do). 789 * MUST NOT change this header information. 790 * MUST NOT reply to a multicast/broadcast IP address. 791 * MUST NOT reply to a multicast/broadcast MAC address. 792 * MUST reply to only the first fragment. 793 */ 794 795 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 796 const struct inet_skb_parm *parm) 797 { 798 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 799 IP_OPTIONS_DATA_FIXED_SIZE); 800 struct iphdr *iph; 801 int room; 802 struct rtable *rt = skb_rtable(skb_in); 803 bool apply_ratelimit = false; 804 struct sk_buff *ext_skb; 805 struct ipcm_cookie ipc; 806 struct flowi4 fl4; 807 __be32 saddr; 808 u8 tos; 809 u32 mark; 810 struct net *net; 811 struct sock *sk; 812 813 if (!rt) 814 return; 815 816 rcu_read_lock(); 817 818 if (rt->dst.dev) 819 net = dev_net_rcu(rt->dst.dev); 820 else if (skb_in->dev) 821 net = dev_net_rcu(skb_in->dev); 822 else 823 goto out; 824 825 /* 826 * Find the original header. It is expected to be valid, of course. 827 * Check this, icmp_send is called from the most obscure devices 828 * sometimes. 829 */ 830 iph = ip_hdr(skb_in); 831 832 if ((u8 *)iph < skb_in->head || 833 (skb_network_header(skb_in) + sizeof(*iph)) > 834 skb_tail_pointer(skb_in)) 835 goto out; 836 837 /* 838 * No replies to physical multicast/broadcast 839 */ 840 if (skb_in->pkt_type != PACKET_HOST) 841 goto out; 842 843 /* 844 * Now check at the protocol level 845 */ 846 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 847 goto out; 848 849 /* 850 * Only reply to fragment 0. We byte re-order the constant 851 * mask for efficiency. 852 */ 853 if (iph->frag_off & htons(IP_OFFSET)) 854 goto out; 855 856 /* 857 * If we send an ICMP error to an ICMP error a mess would result.. 858 */ 859 if (icmp_pointers[type].error) { 860 /* 861 * We are an error, check if we are replying to an 862 * ICMP error 863 */ 864 if (iph->protocol == IPPROTO_ICMP) { 865 u8 _inner_type, *itp; 866 867 itp = skb_header_pointer(skb_in, 868 skb_network_header(skb_in) + 869 (iph->ihl << 2) + 870 offsetof(struct icmphdr, 871 type) - 872 skb_in->data, 873 sizeof(_inner_type), 874 &_inner_type); 875 if (!itp) 876 goto out; 877 878 /* 879 * Assume any unknown ICMP type is an error. This 880 * isn't specified by the RFC, but think about it.. 881 */ 882 if (*itp > NR_ICMP_TYPES || 883 icmp_pointers[*itp].error) 884 goto out; 885 } 886 } 887 888 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 889 local_bh_disable(); 890 891 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 892 * incoming dev is loopback. If outgoing dev change to not be 893 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 894 */ 895 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 896 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 897 goto out_bh_enable; 898 899 sk = icmp_xmit_lock(net); 900 if (!sk) 901 goto out_bh_enable; 902 903 /* 904 * Construct source address and options. 905 */ 906 907 saddr = iph->daddr; 908 if (!(rt->rt_flags & RTCF_LOCAL)) { 909 struct net_device *dev = NULL; 910 911 rcu_read_lock(); 912 if (rt_is_input_route(rt) && 913 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 914 dev = dev_get_by_index_rcu(net, parm->iif ? parm->iif : 915 inet_iif(skb_in)); 916 917 if (dev) 918 saddr = inet_select_addr(dev, iph->saddr, 919 RT_SCOPE_LINK); 920 else 921 saddr = 0; 922 rcu_read_unlock(); 923 } 924 925 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 926 IPTOS_PREC_INTERNETCONTROL) : 927 iph->tos; 928 mark = IP4_REPLY_MARK(net, skb_in->mark); 929 930 if (__ip_options_echo(net, &icmp_param->replyopts.opt, skb_in, 931 &parm->opt)) 932 goto out_unlock; 933 934 935 /* 936 * Prepare data for ICMP header. 937 */ 938 939 icmp_param->data.icmph.type = type; 940 icmp_param->data.icmph.code = code; 941 icmp_param->data.icmph.un.gateway = info; 942 icmp_param->data.icmph.checksum = 0; 943 icmp_param->skb = skb_in; 944 icmp_param->offset = skb_network_offset(skb_in); 945 ipcm_init(&ipc); 946 ipc.tos = tos; 947 ipc.addr = iph->saddr; 948 ipc.opt = &icmp_param->replyopts; 949 ipc.sockc.mark = mark; 950 951 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 952 inet_dsfield_to_dscp(tos), mark, type, code, 953 icmp_param); 954 if (IS_ERR(rt)) 955 goto out_unlock; 956 957 /* peer icmp_ratelimit */ 958 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 959 goto ende; 960 961 /* RFC says return as much as we can without exceeding 576 bytes. */ 962 963 room = dst4_mtu(&rt->dst); 964 if (room > 576) 965 room = 576; 966 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.optlen; 967 room -= sizeof(struct icmphdr); 968 /* Guard against tiny mtu. We need to include at least one 969 * IP network header for this message to make any sense. 970 */ 971 if (room <= (int)sizeof(struct iphdr)) 972 goto ende; 973 974 ext_skb = icmp_ext_append(net, skb_in, &icmp_param->data.icmph, room, 975 parm->iif); 976 if (ext_skb) 977 icmp_param->skb = ext_skb; 978 979 icmp_param->data_len = icmp_param->skb->len - icmp_param->offset; 980 if (icmp_param->data_len > room) 981 icmp_param->data_len = room; 982 icmp_param->head_len = sizeof(struct icmphdr); 983 984 /* if we don't have a source address at this point, fall back to the 985 * dummy address instead of sending out a packet with a source address 986 * of 0.0.0.0 987 */ 988 if (!fl4.saddr) 989 fl4.saddr = htonl(INADDR_DUMMY); 990 991 trace_icmp_send(skb_in, type, code); 992 993 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 994 995 if (ext_skb) 996 consume_skb(ext_skb); 997 ende: 998 ip_rt_put(rt); 999 out_unlock: 1000 icmp_xmit_unlock(sk); 1001 out_bh_enable: 1002 local_bh_enable(); 1003 out: 1004 rcu_read_unlock(); 1005 } 1006 EXPORT_SYMBOL(__icmp_send); 1007 1008 #if IS_ENABLED(CONFIG_NF_NAT) 1009 #include <net/netfilter/nf_conntrack.h> 1010 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 1011 { 1012 struct sk_buff *cloned_skb = NULL; 1013 enum ip_conntrack_info ctinfo; 1014 enum ip_conntrack_dir dir; 1015 struct inet_skb_parm parm; 1016 struct nf_conn *ct; 1017 __be32 orig_ip; 1018 1019 memset(&parm, 0, sizeof(parm)); 1020 ct = nf_ct_get(skb_in, &ctinfo); 1021 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { 1022 __icmp_send(skb_in, type, code, info, &parm); 1023 return; 1024 } 1025 1026 if (skb_shared(skb_in)) 1027 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 1028 1029 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 1030 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 1031 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 1032 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 1033 goto out; 1034 1035 orig_ip = ip_hdr(skb_in)->saddr; 1036 dir = CTINFO2DIR(ctinfo); 1037 ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; 1038 __icmp_send(skb_in, type, code, info, &parm); 1039 ip_hdr(skb_in)->saddr = orig_ip; 1040 out: 1041 consume_skb(cloned_skb); 1042 } 1043 EXPORT_SYMBOL(icmp_ndo_send); 1044 #endif 1045 1046 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 1047 { 1048 const struct iphdr *iph = (const struct iphdr *)skb->data; 1049 const struct net_protocol *ipprot; 1050 int protocol = iph->protocol; 1051 1052 /* Checkin full IP header plus 8 bytes of protocol to 1053 * avoid additional coding at protocol handlers. 1054 */ 1055 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 1056 goto out; 1057 1058 /* IPPROTO_RAW sockets are not supposed to receive anything. */ 1059 if (protocol == IPPROTO_RAW) 1060 goto out; 1061 1062 raw_icmp_error(skb, protocol, info); 1063 1064 ipprot = rcu_dereference(inet_protos[protocol]); 1065 if (ipprot && ipprot->err_handler) 1066 ipprot->err_handler(skb, info); 1067 return; 1068 1069 out: 1070 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1071 } 1072 1073 static bool icmp_tag_validation(int proto) 1074 { 1075 bool ok; 1076 1077 rcu_read_lock(); 1078 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 1079 rcu_read_unlock(); 1080 return ok; 1081 } 1082 1083 /* 1084 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 1085 * ICMP_PARAMETERPROB. 1086 */ 1087 1088 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 1089 { 1090 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 1091 const struct iphdr *iph; 1092 struct icmphdr *icmph; 1093 struct net *net; 1094 u32 info = 0; 1095 1096 net = skb_dst_dev_net_rcu(skb); 1097 1098 /* 1099 * Incomplete header ? 1100 * Only checks for the IP header, there should be an 1101 * additional check for longer headers in upper levels. 1102 */ 1103 1104 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 1105 goto out_err; 1106 1107 icmph = icmp_hdr(skb); 1108 iph = (const struct iphdr *)skb->data; 1109 1110 if (iph->ihl < 5) { /* Mangled header, drop. */ 1111 reason = SKB_DROP_REASON_IP_INHDR; 1112 goto out_err; 1113 } 1114 1115 switch (icmph->type) { 1116 case ICMP_DEST_UNREACH: 1117 switch (icmph->code & 15) { 1118 case ICMP_NET_UNREACH: 1119 case ICMP_HOST_UNREACH: 1120 case ICMP_PROT_UNREACH: 1121 case ICMP_PORT_UNREACH: 1122 break; 1123 case ICMP_FRAG_NEEDED: 1124 /* for documentation of the ip_no_pmtu_disc 1125 * values please see 1126 * Documentation/networking/ip-sysctl.rst 1127 */ 1128 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 1129 default: 1130 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 1131 &iph->daddr); 1132 break; 1133 case 2: 1134 goto out; 1135 case 3: 1136 if (!icmp_tag_validation(iph->protocol)) 1137 goto out; 1138 fallthrough; 1139 case 0: 1140 info = ntohs(icmph->un.frag.mtu); 1141 } 1142 break; 1143 case ICMP_SR_FAILED: 1144 net_dbg_ratelimited("%pI4: Source Route Failed\n", 1145 &iph->daddr); 1146 break; 1147 default: 1148 break; 1149 } 1150 if (icmph->code > NR_ICMP_UNREACH) 1151 goto out; 1152 break; 1153 case ICMP_PARAMETERPROB: 1154 info = ntohl(icmph->un.gateway) >> 24; 1155 break; 1156 case ICMP_TIME_EXCEEDED: 1157 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 1158 if (icmph->code == ICMP_EXC_FRAGTIME) 1159 goto out; 1160 break; 1161 } 1162 1163 /* 1164 * Throw it at our lower layers 1165 * 1166 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 1167 * header. 1168 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 1169 * transport layer. 1170 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 1171 * transport layer. 1172 */ 1173 1174 /* 1175 * Check the other end isn't violating RFC 1122. Some routers send 1176 * bogus responses to broadcast frames. If you see this message 1177 * first check your netmask matches at both ends, if it does then 1178 * get the other vendor to fix their kit. 1179 */ 1180 1181 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 1182 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 1183 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 1184 &ip_hdr(skb)->saddr, 1185 icmph->type, icmph->code, 1186 &iph->daddr, skb->dev->name); 1187 goto out; 1188 } 1189 1190 icmp_socket_deliver(skb, info); 1191 1192 out: 1193 return reason; 1194 out_err: 1195 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1196 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 1197 } 1198 1199 1200 /* 1201 * Handle ICMP_REDIRECT. 1202 */ 1203 1204 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 1205 { 1206 if (skb->len < sizeof(struct iphdr)) { 1207 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1208 return SKB_DROP_REASON_PKT_TOO_SMALL; 1209 } 1210 1211 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 1212 /* there aught to be a stat */ 1213 return SKB_DROP_REASON_NOMEM; 1214 } 1215 1216 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 1217 return SKB_NOT_DROPPED_YET; 1218 } 1219 1220 /* 1221 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1222 * 1223 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1224 * requests. 1225 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1226 * included in the reply. 1227 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1228 * echo requests, MUST have default=NOT. 1229 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1230 * Extended Echo Functionality, MUST be disabled by default 1231 * See also WRT handling of options once they are done and working. 1232 */ 1233 1234 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1235 { 1236 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1237 IP_OPTIONS_DATA_FIXED_SIZE); 1238 struct net *net; 1239 1240 net = skb_dst_dev_net_rcu(skb); 1241 /* should there be an ICMP stat for ignored echos? */ 1242 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1243 return SKB_NOT_DROPPED_YET; 1244 1245 icmp_param->data.icmph = *icmp_hdr(skb); 1246 icmp_param->skb = skb; 1247 icmp_param->offset = 0; 1248 icmp_param->data_len = skb->len; 1249 icmp_param->head_len = sizeof(struct icmphdr); 1250 1251 if (icmp_param->data.icmph.type == ICMP_ECHO) 1252 icmp_param->data.icmph.type = ICMP_ECHOREPLY; 1253 else if (!icmp_build_probe(skb, &icmp_param->data.icmph)) 1254 return SKB_NOT_DROPPED_YET; 1255 1256 icmp_reply(icmp_param, skb); 1257 return SKB_NOT_DROPPED_YET; 1258 } 1259 1260 /* Helper for icmp_echo and icmpv6_echo_reply. 1261 * Searches for net_device that matches PROBE interface identifier 1262 * and builds PROBE reply message in icmphdr. 1263 * 1264 * Returns false if PROBE responses are disabled via sysctl 1265 */ 1266 1267 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1268 { 1269 struct net *net = dev_net_rcu(skb->dev); 1270 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1271 struct icmp_ext_echo_iio *iio, _iio; 1272 struct inet6_dev *in6_dev; 1273 struct in_device *in_dev; 1274 struct net_device *dev; 1275 char buff[IFNAMSIZ]; 1276 u16 ident_len; 1277 u8 status; 1278 1279 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1280 return false; 1281 1282 /* We currently only support probing interfaces on the proxy node 1283 * Check to ensure L-bit is set 1284 */ 1285 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1286 return false; 1287 /* Clear status bits in reply message */ 1288 icmphdr->un.echo.sequence &= htons(0xFF00); 1289 if (icmphdr->type == ICMP_EXT_ECHO) 1290 icmphdr->type = ICMP_EXT_ECHOREPLY; 1291 else 1292 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1293 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1294 /* Size of iio is class_type dependent. 1295 * Only check header here and assign length based on ctype in the switch statement 1296 */ 1297 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1298 if (!ext_hdr || !iio) 1299 goto send_mal_query; 1300 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1301 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1302 goto send_mal_query; 1303 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1304 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1305 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1306 if (!iio) 1307 goto send_mal_query; 1308 1309 status = 0; 1310 dev = NULL; 1311 switch (iio->extobj_hdr.class_type) { 1312 case ICMP_EXT_ECHO_CTYPE_NAME: 1313 if (ident_len >= IFNAMSIZ) 1314 goto send_mal_query; 1315 memset(buff, 0, sizeof(buff)); 1316 memcpy(buff, &iio->ident.name, ident_len); 1317 dev = dev_get_by_name(net, buff); 1318 break; 1319 case ICMP_EXT_ECHO_CTYPE_INDEX: 1320 if (ident_len != sizeof(iio->ident.ifindex)) 1321 goto send_mal_query; 1322 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1323 break; 1324 case ICMP_EXT_ECHO_CTYPE_ADDR: 1325 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1326 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1327 iio->ident.addr.ctype3_hdr.addrlen) 1328 goto send_mal_query; 1329 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1330 case ICMP_AFI_IP: 1331 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1332 goto send_mal_query; 1333 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1334 break; 1335 #if IS_ENABLED(CONFIG_IPV6) 1336 case ICMP_AFI_IP6: 1337 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1338 goto send_mal_query; 1339 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1340 dev_hold(dev); 1341 break; 1342 #endif 1343 default: 1344 goto send_mal_query; 1345 } 1346 break; 1347 default: 1348 goto send_mal_query; 1349 } 1350 if (!dev) { 1351 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1352 return true; 1353 } 1354 /* Fill bits in reply message */ 1355 if (dev->flags & IFF_UP) 1356 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1357 1358 in_dev = __in_dev_get_rcu(dev); 1359 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1360 status |= ICMP_EXT_ECHOREPLY_IPV4; 1361 1362 in6_dev = __in6_dev_get(dev); 1363 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1364 status |= ICMP_EXT_ECHOREPLY_IPV6; 1365 1366 dev_put(dev); 1367 icmphdr->un.echo.sequence |= htons(status); 1368 return true; 1369 send_mal_query: 1370 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1371 return true; 1372 } 1373 EXPORT_SYMBOL_GPL(icmp_build_probe); 1374 1375 /* 1376 * Handle ICMP Timestamp requests. 1377 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1378 * SHOULD be in the kernel for minimum random latency. 1379 * MUST be accurate to a few minutes. 1380 * MUST be updated at least at 15Hz. 1381 */ 1382 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1383 { 1384 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1385 IP_OPTIONS_DATA_FIXED_SIZE); 1386 /* 1387 * Too short. 1388 */ 1389 if (skb->len < 4) 1390 goto out_err; 1391 1392 /* 1393 * Fill in the current time as ms since midnight UT: 1394 */ 1395 icmp_param->data.times[1] = inet_current_timestamp(); 1396 icmp_param->data.times[2] = icmp_param->data.times[1]; 1397 1398 BUG_ON(skb_copy_bits(skb, 0, &icmp_param->data.times[0], 4)); 1399 1400 icmp_param->data.icmph = *icmp_hdr(skb); 1401 icmp_param->data.icmph.type = ICMP_TIMESTAMPREPLY; 1402 icmp_param->data.icmph.code = 0; 1403 icmp_param->skb = skb; 1404 icmp_param->offset = 0; 1405 icmp_param->data_len = 0; 1406 icmp_param->head_len = sizeof(struct icmphdr) + 12; 1407 icmp_reply(icmp_param, skb); 1408 return SKB_NOT_DROPPED_YET; 1409 1410 out_err: 1411 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS); 1412 return SKB_DROP_REASON_PKT_TOO_SMALL; 1413 } 1414 1415 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1416 { 1417 /* pretend it was a success */ 1418 return SKB_NOT_DROPPED_YET; 1419 } 1420 1421 /* 1422 * Deal with incoming ICMP packets. 1423 */ 1424 int icmp_rcv(struct sk_buff *skb) 1425 { 1426 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1427 struct rtable *rt = skb_rtable(skb); 1428 struct net *net = dev_net_rcu(rt->dst.dev); 1429 struct icmphdr *icmph; 1430 1431 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1432 struct sec_path *sp = skb_sec_path(skb); 1433 int nh; 1434 1435 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1436 XFRM_STATE_ICMP)) { 1437 reason = SKB_DROP_REASON_XFRM_POLICY; 1438 goto drop; 1439 } 1440 1441 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1442 goto drop; 1443 1444 nh = skb_network_offset(skb); 1445 skb_set_network_header(skb, sizeof(*icmph)); 1446 1447 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1448 skb)) { 1449 reason = SKB_DROP_REASON_XFRM_POLICY; 1450 goto drop; 1451 } 1452 1453 skb_set_network_header(skb, nh); 1454 } 1455 1456 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1457 1458 if (skb_checksum_simple_validate(skb)) 1459 goto csum_error; 1460 1461 if (!pskb_pull(skb, sizeof(*icmph))) 1462 goto error; 1463 1464 icmph = icmp_hdr(skb); 1465 1466 ICMPMSGIN_INC_STATS(net, icmph->type); 1467 1468 /* Check for ICMP Extended Echo (PROBE) messages */ 1469 if (icmph->type == ICMP_EXT_ECHO) { 1470 /* We can't use icmp_pointers[].handler() because it is an array of 1471 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1472 */ 1473 reason = icmp_echo(skb); 1474 goto reason_check; 1475 } 1476 1477 /* 1478 * Parse the ICMP message 1479 */ 1480 1481 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1482 /* 1483 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1484 * silently ignored (we let user decide with a sysctl). 1485 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1486 * discarded if to broadcast/multicast. 1487 */ 1488 if ((icmph->type == ICMP_ECHO || 1489 icmph->type == ICMP_TIMESTAMP) && 1490 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1491 reason = SKB_DROP_REASON_INVALID_PROTO; 1492 goto error; 1493 } 1494 if (icmph->type != ICMP_ECHO && 1495 icmph->type != ICMP_TIMESTAMP && 1496 icmph->type != ICMP_ADDRESS && 1497 icmph->type != ICMP_ADDRESSREPLY) { 1498 reason = SKB_DROP_REASON_INVALID_PROTO; 1499 goto error; 1500 } 1501 } 1502 1503 if (icmph->type == ICMP_EXT_ECHOREPLY || 1504 icmph->type == ICMP_ECHOREPLY) { 1505 reason = ping_rcv(skb); 1506 return reason ? NET_RX_DROP : NET_RX_SUCCESS; 1507 } 1508 1509 /* 1510 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1511 * 1512 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1513 * discarded. 1514 */ 1515 if (icmph->type > NR_ICMP_TYPES) { 1516 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1517 goto error; 1518 } 1519 1520 reason = icmp_pointers[icmph->type].handler(skb); 1521 reason_check: 1522 if (!reason) { 1523 consume_skb(skb); 1524 return NET_RX_SUCCESS; 1525 } 1526 1527 drop: 1528 kfree_skb_reason(skb, reason); 1529 return NET_RX_DROP; 1530 csum_error: 1531 reason = SKB_DROP_REASON_ICMP_CSUM; 1532 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1533 error: 1534 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1535 goto drop; 1536 } 1537 1538 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1539 { 1540 struct icmp_extobj_hdr *objh, _objh; 1541 struct icmp_ext_hdr *exth, _exth; 1542 u16 olen; 1543 1544 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1545 if (!exth) 1546 return false; 1547 if (exth->version != 2) 1548 return true; 1549 1550 if (exth->checksum && 1551 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1552 return false; 1553 1554 off += sizeof(_exth); 1555 while (off < skb->len) { 1556 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1557 if (!objh) 1558 return false; 1559 1560 olen = ntohs(objh->length); 1561 if (olen < sizeof(_objh)) 1562 return false; 1563 1564 off += olen; 1565 if (off > skb->len) 1566 return false; 1567 } 1568 1569 return true; 1570 } 1571 1572 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1573 struct sock_ee_data_rfc4884 *out, 1574 int thlen, int off) 1575 { 1576 int hlen; 1577 1578 /* original datagram headers: end of icmph to payload (skb->data) */ 1579 hlen = -skb_transport_offset(skb) - thlen; 1580 1581 /* per rfc 4884: minimal datagram length of 128 bytes */ 1582 if (off < 128 || off < hlen) 1583 return; 1584 1585 /* kernel has stripped headers: return payload offset in bytes */ 1586 off -= hlen; 1587 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1588 return; 1589 1590 out->len = off; 1591 1592 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1593 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1594 } 1595 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1596 1597 int icmp_err(struct sk_buff *skb, u32 info) 1598 { 1599 struct iphdr *iph = (struct iphdr *)skb->data; 1600 int offset = iph->ihl<<2; 1601 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1602 struct net *net = dev_net_rcu(skb->dev); 1603 int type = icmp_hdr(skb)->type; 1604 int code = icmp_hdr(skb)->code; 1605 1606 /* 1607 * Use ping_err to handle all icmp errors except those 1608 * triggered by ICMP_ECHOREPLY which sent from kernel. 1609 */ 1610 if (icmph->type != ICMP_ECHOREPLY) { 1611 ping_err(skb, offset, info); 1612 return 0; 1613 } 1614 1615 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1616 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1617 else if (type == ICMP_REDIRECT) 1618 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1619 1620 return 0; 1621 } 1622 1623 /* 1624 * This table is the definition of how we handle ICMP. 1625 */ 1626 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1627 [ICMP_ECHOREPLY] = { 1628 .handler = ping_rcv, 1629 }, 1630 [1] = { 1631 .handler = icmp_discard, 1632 .error = 1, 1633 }, 1634 [2] = { 1635 .handler = icmp_discard, 1636 .error = 1, 1637 }, 1638 [ICMP_DEST_UNREACH] = { 1639 .handler = icmp_unreach, 1640 .error = 1, 1641 }, 1642 [ICMP_SOURCE_QUENCH] = { 1643 .handler = icmp_unreach, 1644 .error = 1, 1645 }, 1646 [ICMP_REDIRECT] = { 1647 .handler = icmp_redirect, 1648 .error = 1, 1649 }, 1650 [6] = { 1651 .handler = icmp_discard, 1652 .error = 1, 1653 }, 1654 [7] = { 1655 .handler = icmp_discard, 1656 .error = 1, 1657 }, 1658 [ICMP_ECHO] = { 1659 .handler = icmp_echo, 1660 }, 1661 [9] = { 1662 .handler = icmp_discard, 1663 .error = 1, 1664 }, 1665 [10] = { 1666 .handler = icmp_discard, 1667 .error = 1, 1668 }, 1669 [ICMP_TIME_EXCEEDED] = { 1670 .handler = icmp_unreach, 1671 .error = 1, 1672 }, 1673 [ICMP_PARAMETERPROB] = { 1674 .handler = icmp_unreach, 1675 .error = 1, 1676 }, 1677 [ICMP_TIMESTAMP] = { 1678 .handler = icmp_timestamp, 1679 }, 1680 [ICMP_TIMESTAMPREPLY] = { 1681 .handler = icmp_discard, 1682 }, 1683 [ICMP_INFO_REQUEST] = { 1684 .handler = icmp_discard, 1685 }, 1686 [ICMP_INFO_REPLY] = { 1687 .handler = icmp_discard, 1688 }, 1689 [ICMP_ADDRESS] = { 1690 .handler = icmp_discard, 1691 }, 1692 [ICMP_ADDRESSREPLY] = { 1693 .handler = icmp_discard, 1694 }, 1695 }; 1696 1697 static int __net_init icmp_sk_init(struct net *net) 1698 { 1699 /* Control parameters for ECHO replies. */ 1700 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1701 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1702 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1703 1704 /* Control parameter - ignore bogus broadcast responses? */ 1705 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1706 1707 /* 1708 * Configurable global rate limit. 1709 * 1710 * ratelimit defines tokens/packet consumed for dst->rate_token 1711 * bucket ratemask defines which icmp types are ratelimited by 1712 * setting it's bit position. 1713 * 1714 * default: 1715 * dest unreachable (3), source quench (4), 1716 * time exceeded (11), parameter problem (12) 1717 */ 1718 1719 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1720 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1721 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1722 net->ipv4.sysctl_icmp_errors_extension_mask = 0; 1723 net->ipv4.sysctl_icmp_msgs_per_sec = 1000; 1724 net->ipv4.sysctl_icmp_msgs_burst = 50; 1725 1726 return 0; 1727 } 1728 1729 static struct pernet_operations __net_initdata icmp_sk_ops = { 1730 .init = icmp_sk_init, 1731 }; 1732 1733 int __init icmp_init(void) 1734 { 1735 int err, i; 1736 1737 for_each_possible_cpu(i) { 1738 struct sock *sk; 1739 1740 err = inet_ctl_sock_create(&sk, PF_INET, 1741 SOCK_RAW, IPPROTO_ICMP, &init_net); 1742 if (err < 0) 1743 return err; 1744 1745 per_cpu(ipv4_icmp_sk, i) = sk; 1746 1747 /* Enough space for 2 64K ICMP packets, including 1748 * sk_buff/skb_shared_info struct overhead. 1749 */ 1750 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1751 1752 /* 1753 * Speedup sock_wfree() 1754 */ 1755 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1756 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1757 } 1758 return register_pernet_subsys(&icmp_sk_ops); 1759 } 1760