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/nospec.h> 68 #include <linux/socket.h> 69 #include <linux/in.h> 70 #include <linux/inet.h> 71 #include <linux/inetdevice.h> 72 #include <linux/netdevice.h> 73 #include <linux/string.h> 74 #include <linux/netfilter_ipv4.h> 75 #include <linux/slab.h> 76 #include <net/flow.h> 77 #include <net/snmp.h> 78 #include <net/ip.h> 79 #include <net/route.h> 80 #include <net/protocol.h> 81 #include <net/icmp.h> 82 #include <net/tcp.h> 83 #include <net/udp.h> 84 #include <net/raw.h> 85 #include <net/ping.h> 86 #include <linux/skbuff.h> 87 #include <net/sock.h> 88 #include <linux/errno.h> 89 #include <linux/timer.h> 90 #include <linux/init.h> 91 #include <linux/uaccess.h> 92 #include <net/checksum.h> 93 #include <net/xfrm.h> 94 #include <net/inet_common.h> 95 #include <net/ip_fib.h> 96 #include <net/l3mdev.h> 97 #include <net/addrconf.h> 98 #include <net/inet_dscp.h> 99 #define CREATE_TRACE_POINTS 100 #include <trace/events/icmp.h> 101 102 /* 103 * Build xmit assembly blocks 104 */ 105 106 struct icmp_bxm { 107 struct sk_buff *skb; 108 int offset; 109 int data_len; 110 111 struct { 112 struct icmphdr icmph; 113 __be32 times[3]; 114 } data; 115 int head_len; 116 117 /* Must be last as it ends in a flexible-array member. */ 118 struct ip_options_rcu replyopts; 119 }; 120 121 /* An array of errno for error messages from dest unreach. */ 122 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 123 124 const struct icmp_err icmp_err_convert[] = { 125 { 126 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 127 .fatal = 0, 128 }, 129 { 130 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 131 .fatal = 0, 132 }, 133 { 134 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 135 .fatal = 1, 136 }, 137 { 138 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 139 .fatal = 1, 140 }, 141 { 142 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 143 .fatal = 0, 144 }, 145 { 146 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 147 .fatal = 0, 148 }, 149 { 150 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 151 .fatal = 1, 152 }, 153 { 154 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 155 .fatal = 1, 156 }, 157 { 158 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 159 .fatal = 1, 160 }, 161 { 162 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 163 .fatal = 1, 164 }, 165 { 166 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 167 .fatal = 1, 168 }, 169 { 170 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 171 .fatal = 0, 172 }, 173 { 174 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 175 .fatal = 0, 176 }, 177 { 178 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 179 .fatal = 1, 180 }, 181 { 182 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 183 .fatal = 1, 184 }, 185 { 186 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 187 .fatal = 1, 188 }, 189 }; 190 EXPORT_SYMBOL(icmp_err_convert); 191 192 /* 193 * ICMP control array. This specifies what to do with each ICMP. 194 */ 195 196 struct icmp_control { 197 enum skb_drop_reason (*handler)(struct sk_buff *skb); 198 short error; /* This ICMP is classed as an error message */ 199 }; 200 201 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 202 203 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 204 205 /* Called with BH disabled */ 206 static inline struct sock *icmp_xmit_lock(struct net *net) 207 { 208 struct sock *sk; 209 210 sk = this_cpu_read(ipv4_icmp_sk); 211 212 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 213 /* This can happen if the output path signals a 214 * dst_link_failure() for an outgoing ICMP packet. 215 */ 216 return NULL; 217 } 218 sock_net_set(sk, net); 219 return sk; 220 } 221 222 static inline void icmp_xmit_unlock(struct sock *sk) 223 { 224 sock_net_set(sk, &init_net); 225 spin_unlock(&sk->sk_lock.slock); 226 } 227 228 /** 229 * icmp_global_allow - Are we allowed to send one more ICMP message ? 230 * @net: network namespace 231 * 232 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 233 * Returns false if we reached the limit and can not send another packet. 234 * Works in tandem with icmp_global_consume(). 235 */ 236 bool icmp_global_allow(struct net *net) 237 { 238 u32 delta, now, oldstamp; 239 int incr, new, old; 240 241 /* Note: many cpus could find this condition true. 242 * Then later icmp_global_consume() could consume more credits, 243 * this is an acceptable race. 244 */ 245 if (atomic_read(&net->ipv4.icmp_global_credit) > 0) 246 return true; 247 248 now = jiffies; 249 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); 250 delta = min_t(u32, now - oldstamp, HZ); 251 if (delta < HZ / 50) 252 return false; 253 254 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec); 255 incr = div_u64((u64)incr * delta, HZ); 256 if (!incr) 257 return false; 258 259 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 260 old = atomic_read(&net->ipv4.icmp_global_credit); 261 do { 262 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 263 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 264 } 265 return true; 266 } 267 268 void icmp_global_consume(struct net *net) 269 { 270 int credits = get_random_u32_below(3); 271 272 /* Note: this might make icmp_global.credit negative. */ 273 if (credits) 274 atomic_sub(credits, &net->ipv4.icmp_global_credit); 275 } 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 int peer_timeout; 319 bool rc = true; 320 321 if (!apply_ratelimit) 322 return true; 323 324 peer_timeout = READ_ONCE(net->ipv4.sysctl_icmp_ratelimit); 325 if (!peer_timeout) 326 goto out; 327 328 /* No rate limit on loopback */ 329 rcu_read_lock(); 330 dev = dst_dev_rcu(dst); 331 if (dev && (dev->flags & IFF_LOOPBACK)) 332 goto out_unlock; 333 334 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 335 l3mdev_master_ifindex_rcu(dev)); 336 rc = inet_peer_xrlim_allow(peer, peer_timeout); 337 338 out_unlock: 339 rcu_read_unlock(); 340 out: 341 if (!rc) 342 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 343 else 344 icmp_global_consume(net); 345 return rc; 346 } 347 348 /* 349 * Maintain the counters used in the SNMP statistics for outgoing ICMP 350 */ 351 void icmp_out_count(struct net *net, unsigned char type) 352 { 353 ICMPMSGOUT_INC_STATS(net, type); 354 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 355 } 356 357 /* 358 * Checksum each fragment, and on the first include the headers and final 359 * checksum. 360 */ 361 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 362 struct sk_buff *skb) 363 { 364 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 365 IP_OPTIONS_DATA_FIXED_SIZE); 366 __wsum csum; 367 368 icmp_param = from; 369 370 csum = skb_copy_and_csum_bits(icmp_param->skb, 371 icmp_param->offset + offset, 372 to, len); 373 374 skb->csum = csum_block_add(skb->csum, csum, odd); 375 if (icmp_param->data.icmph.type <= NR_ICMP_TYPES && 376 icmp_pointers[array_index_nospec(icmp_param->data.icmph.type, 377 NR_ICMP_TYPES + 1)].error) 378 nf_ct_attach(skb, icmp_param->skb); 379 return 0; 380 } 381 382 static void icmp_push_reply(struct sock *sk, 383 struct icmp_bxm *icmp_param, 384 struct flowi4 *fl4, 385 struct ipcm_cookie *ipc, struct rtable **rt) 386 { 387 struct sk_buff *skb; 388 389 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 390 icmp_param->data_len+icmp_param->head_len, 391 icmp_param->head_len, 392 ipc, rt, MSG_DONTWAIT) < 0) { 393 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 394 ip_flush_pending_frames(sk); 395 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 396 struct icmphdr *icmph = icmp_hdr(skb); 397 __wsum csum; 398 struct sk_buff *skb1; 399 400 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 401 (char *)icmph, 402 icmp_param->head_len); 403 skb_queue_walk(&sk->sk_write_queue, skb1) { 404 csum = csum_add(csum, skb1->csum); 405 } 406 icmph->checksum = csum_fold(csum); 407 skb->ip_summed = CHECKSUM_NONE; 408 ip_push_pending_frames(sk, fl4); 409 } 410 } 411 412 /* 413 * Driving logic for building and sending ICMP messages. 414 */ 415 416 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 417 { 418 struct rtable *rt = skb_rtable(skb); 419 struct net *net = dev_net_rcu(rt->dst.dev); 420 bool apply_ratelimit = false; 421 struct ipcm_cookie ipc; 422 struct flowi4 fl4; 423 struct sock *sk; 424 __be32 daddr, saddr; 425 u32 mark = IP4_REPLY_MARK(net, skb->mark); 426 int type = icmp_param->data.icmph.type; 427 int code = icmp_param->data.icmph.code; 428 429 if (ip_options_echo(net, &icmp_param->replyopts.opt, skb)) 430 return; 431 432 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 433 local_bh_disable(); 434 435 /* is global icmp_msgs_per_sec exhausted ? */ 436 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 437 goto out_bh_enable; 438 439 sk = icmp_xmit_lock(net); 440 if (!sk) 441 goto out_bh_enable; 442 443 icmp_param->data.icmph.checksum = 0; 444 445 ipcm_init(&ipc); 446 ipc.tos = ip_hdr(skb)->tos; 447 ipc.sockc.mark = mark; 448 daddr = ipc.addr = ip_hdr(skb)->saddr; 449 saddr = fib_compute_spec_dst(skb); 450 451 if (icmp_param->replyopts.opt.optlen) { 452 ipc.opt = &icmp_param->replyopts; 453 if (ipc.opt->opt.srr) 454 daddr = icmp_param->replyopts.opt.faddr; 455 } 456 memset(&fl4, 0, sizeof(fl4)); 457 fl4.daddr = daddr; 458 fl4.saddr = saddr; 459 fl4.flowi4_mark = mark; 460 fl4.flowi4_uid = sock_net_uid(net, NULL); 461 fl4.flowi4_dscp = ip4h_dscp(ip_hdr(skb)); 462 fl4.flowi4_proto = IPPROTO_ICMP; 463 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 464 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 465 rt = ip_route_output_key(net, &fl4); 466 if (IS_ERR(rt)) 467 goto out_unlock; 468 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 469 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 470 ip_rt_put(rt); 471 out_unlock: 472 icmp_xmit_unlock(sk); 473 out_bh_enable: 474 local_bh_enable(); 475 } 476 477 /* 478 * The device used for looking up which routing table to use for sending an ICMP 479 * error is preferably the source whenever it is set, which should ensure the 480 * icmp error can be sent to the source host, else lookup using the routing 481 * table of the destination device, else use the main routing table (index 0). 482 */ 483 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 484 { 485 struct net_device *dev = skb->dev; 486 const struct dst_entry *dst; 487 488 if (dev) 489 return dev; 490 dst = skb_dst(skb); 491 return dst ? dst_dev(dst) : NULL; 492 } 493 494 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 495 struct sk_buff *skb_in, 496 const struct iphdr *iph, __be32 saddr, 497 dscp_t dscp, u32 mark, int type, 498 int code, struct icmp_bxm *param) 499 { 500 struct net_device *route_lookup_dev; 501 struct dst_entry *dst, *dst2; 502 struct rtable *rt, *rt2; 503 struct flowi4 fl4_dec; 504 int err; 505 506 memset(fl4, 0, sizeof(*fl4)); 507 fl4->daddr = (param->replyopts.opt.srr ? 508 param->replyopts.opt.faddr : iph->saddr); 509 fl4->saddr = saddr; 510 fl4->flowi4_mark = mark; 511 fl4->flowi4_uid = sock_net_uid(net, NULL); 512 fl4->flowi4_dscp = dscp; 513 fl4->flowi4_proto = IPPROTO_ICMP; 514 fl4->fl4_icmp_type = type; 515 fl4->fl4_icmp_code = code; 516 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 517 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 518 519 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 520 rt = ip_route_output_key_hash(net, fl4, skb_in); 521 if (IS_ERR(rt)) 522 return rt; 523 524 /* No need to clone since we're just using its address. */ 525 rt2 = rt; 526 527 dst = xfrm_lookup(net, &rt->dst, 528 flowi4_to_flowi(fl4), NULL, 0); 529 rt = dst_rtable(dst); 530 if (!IS_ERR(dst)) { 531 if (rt != rt2) 532 return rt; 533 if (inet_addr_type_dev_table(net, route_lookup_dev, 534 fl4->daddr) == RTN_LOCAL) 535 return rt; 536 } else if (PTR_ERR(dst) == -EPERM) { 537 rt = NULL; 538 } else { 539 return rt; 540 } 541 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 542 if (err) 543 goto relookup_failed; 544 545 if (inet_addr_type_dev_table(net, route_lookup_dev, 546 fl4_dec.saddr) == RTN_LOCAL) { 547 rt2 = __ip_route_output_key(net, &fl4_dec); 548 if (IS_ERR(rt2)) 549 err = PTR_ERR(rt2); 550 } else { 551 struct flowi4 fl4_2 = fl4_dec; 552 unsigned long orefdst; 553 554 swap(fl4_2.daddr, fl4_2.saddr); 555 switch (fl4_2.flowi4_proto) { 556 case IPPROTO_TCP: 557 case IPPROTO_UDP: 558 case IPPROTO_SCTP: 559 case IPPROTO_DCCP: 560 swap(fl4_2.fl4_sport, fl4_2.fl4_dport); 561 break; 562 } 563 564 fl4_2.flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 565 fl4_2.flowi4_flags |= FLOWI_FLAG_ANYSRC; 566 567 rt2 = __ip_route_output_key(net, &fl4_2); 568 if (IS_ERR(rt2)) { 569 err = PTR_ERR(rt2); 570 goto relookup_failed; 571 } 572 /* Ugh! */ 573 orefdst = skb_dstref_steal(skb_in); 574 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 575 dscp, rt2->dst.dev) ? -EINVAL : 0; 576 577 dst_release(&rt2->dst); 578 rt2 = skb_rtable(skb_in); 579 /* steal dst entry from skb_in, don't drop refcnt */ 580 skb_dstref_steal(skb_in); 581 skb_dstref_restore(skb_in, orefdst); 582 583 /* 584 * fl4_dec.daddr is not expected to be local here, but it can be 585 * added to an interface concurrently, in which case 586 * ip_route_input() returns a LOCAL route. It can also fail to 587 * build a forwarding route towards fl4_dec.daddr, for example, 588 * when forwarding is disabled, and return an UNREACHABLE route. 589 * Both cases will result in a route with dst.output=ip_rt_bug, 590 * which must not be used for output. 591 */ 592 if (!err && rt2 && rt2->rt_type == RTN_LOCAL) 593 net_warn_ratelimited("detected local route for %pI4 during ICMP sending, src %pI4\n", 594 &fl4_dec.daddr, &fl4_dec.saddr); 595 if (!err && rt2 && 596 (rt2->rt_type == RTN_LOCAL || rt2->rt_type == RTN_UNREACHABLE)) { 597 dst_release(&rt2->dst); 598 err = -EINVAL; 599 } 600 } 601 602 if (err) 603 goto relookup_failed; 604 605 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 606 XFRM_LOOKUP_ICMP); 607 rt2 = dst_rtable(dst2); 608 if (!IS_ERR(dst2)) { 609 dst_release(&rt->dst); 610 rt = rt2; 611 } else if (PTR_ERR(dst2) == -EPERM) { 612 if (rt) 613 dst_release(&rt->dst); 614 return rt2; 615 } else { 616 err = PTR_ERR(dst2); 617 goto relookup_failed; 618 } 619 return rt; 620 621 relookup_failed: 622 if (rt) 623 return rt; 624 return ERR_PTR(err); 625 } 626 627 struct icmp_ext_iio_addr4_subobj { 628 __be16 afi; 629 __be16 reserved; 630 __be32 addr4; 631 }; 632 633 static unsigned int icmp_ext_iio_len(void) 634 { 635 return sizeof(struct icmp_extobj_hdr) + 636 /* ifIndex */ 637 sizeof(__be32) + 638 /* Interface Address Sub-Object */ 639 sizeof(struct icmp_ext_iio_addr4_subobj) + 640 /* Interface Name Sub-Object. Length must be a multiple of 4 641 * bytes. 642 */ 643 ALIGN(sizeof(struct icmp_ext_iio_name_subobj), 4) + 644 /* MTU */ 645 sizeof(__be32); 646 } 647 648 static unsigned int icmp_ext_max_len(u8 ext_objs) 649 { 650 unsigned int ext_max_len; 651 652 ext_max_len = sizeof(struct icmp_ext_hdr); 653 654 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 655 ext_max_len += icmp_ext_iio_len(); 656 657 return ext_max_len; 658 } 659 660 static __be32 icmp_ext_iio_addr4_find(const struct net_device *dev) 661 { 662 struct in_device *in_dev; 663 struct in_ifaddr *ifa; 664 665 in_dev = __in_dev_get_rcu(dev); 666 if (!in_dev) 667 return 0; 668 669 /* It is unclear from RFC 5837 which IP address should be chosen, but 670 * it makes sense to choose a global unicast address. 671 */ 672 in_dev_for_each_ifa_rcu(ifa, in_dev) { 673 if (READ_ONCE(ifa->ifa_flags) & IFA_F_SECONDARY) 674 continue; 675 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || 676 ipv4_is_multicast(ifa->ifa_address)) 677 continue; 678 return ifa->ifa_address; 679 } 680 681 return 0; 682 } 683 684 static void icmp_ext_iio_iif_append(struct net *net, struct sk_buff *skb, 685 int iif) 686 { 687 struct icmp_ext_iio_name_subobj *name_subobj; 688 struct icmp_extobj_hdr *objh; 689 struct net_device *dev; 690 __be32 data; 691 692 if (!iif) 693 return; 694 695 /* Add the fields in the order specified by RFC 5837. */ 696 objh = skb_put(skb, sizeof(*objh)); 697 objh->class_num = ICMP_EXT_OBJ_CLASS_IIO; 698 objh->class_type = ICMP_EXT_CTYPE_IIO_ROLE(ICMP_EXT_CTYPE_IIO_ROLE_IIF); 699 700 data = htonl(iif); 701 skb_put_data(skb, &data, sizeof(__be32)); 702 objh->class_type |= ICMP_EXT_CTYPE_IIO_IFINDEX; 703 704 rcu_read_lock(); 705 706 dev = dev_get_by_index_rcu(net, iif); 707 if (!dev) 708 goto out; 709 710 data = icmp_ext_iio_addr4_find(dev); 711 if (data) { 712 struct icmp_ext_iio_addr4_subobj *addr4_subobj; 713 714 addr4_subobj = skb_put_zero(skb, sizeof(*addr4_subobj)); 715 addr4_subobj->afi = htons(ICMP_AFI_IP); 716 addr4_subobj->addr4 = data; 717 objh->class_type |= ICMP_EXT_CTYPE_IIO_IPADDR; 718 } 719 720 name_subobj = skb_put_zero(skb, ALIGN(sizeof(*name_subobj), 4)); 721 name_subobj->len = ALIGN(sizeof(*name_subobj), 4); 722 netdev_copy_name(dev, name_subobj->name); 723 objh->class_type |= ICMP_EXT_CTYPE_IIO_NAME; 724 725 data = htonl(READ_ONCE(dev->mtu)); 726 skb_put_data(skb, &data, sizeof(__be32)); 727 objh->class_type |= ICMP_EXT_CTYPE_IIO_MTU; 728 729 out: 730 rcu_read_unlock(); 731 objh->length = htons(skb_tail_pointer(skb) - (unsigned char *)objh); 732 } 733 734 static void icmp_ext_objs_append(struct net *net, struct sk_buff *skb, 735 u8 ext_objs, int iif) 736 { 737 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF)) 738 icmp_ext_iio_iif_append(net, skb, iif); 739 } 740 741 static struct sk_buff * 742 icmp_ext_append(struct net *net, struct sk_buff *skb_in, struct icmphdr *icmph, 743 unsigned int room, int iif) 744 { 745 unsigned int payload_len, ext_max_len, ext_len; 746 struct icmp_ext_hdr *ext_hdr; 747 struct sk_buff *skb; 748 u8 ext_objs; 749 int nhoff; 750 751 switch (icmph->type) { 752 case ICMP_DEST_UNREACH: 753 case ICMP_TIME_EXCEEDED: 754 case ICMP_PARAMETERPROB: 755 break; 756 default: 757 return NULL; 758 } 759 760 ext_objs = READ_ONCE(net->ipv4.sysctl_icmp_errors_extension_mask); 761 if (!ext_objs) 762 return NULL; 763 764 ext_max_len = icmp_ext_max_len(ext_objs); 765 if (ICMP_EXT_ORIG_DGRAM_MIN_LEN + ext_max_len > room) 766 return NULL; 767 768 skb = skb_clone(skb_in, GFP_ATOMIC); 769 if (!skb) 770 return NULL; 771 772 nhoff = skb_network_offset(skb); 773 payload_len = min(skb->len - nhoff, ICMP_EXT_ORIG_DGRAM_MIN_LEN); 774 775 if (!pskb_network_may_pull(skb, payload_len)) 776 goto free_skb; 777 778 if (pskb_trim(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN) || 779 __skb_put_padto(skb, nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN, false)) 780 goto free_skb; 781 782 if (pskb_expand_head(skb, 0, ext_max_len, GFP_ATOMIC)) 783 goto free_skb; 784 785 ext_hdr = skb_put_zero(skb, sizeof(*ext_hdr)); 786 ext_hdr->version = ICMP_EXT_VERSION_2; 787 788 icmp_ext_objs_append(net, skb, ext_objs, iif); 789 790 /* Do not send an empty extension structure. */ 791 ext_len = skb_tail_pointer(skb) - (unsigned char *)ext_hdr; 792 if (ext_len == sizeof(*ext_hdr)) 793 goto free_skb; 794 795 ext_hdr->checksum = ip_compute_csum(ext_hdr, ext_len); 796 /* The length of the original datagram in 32-bit words (RFC 4884). */ 797 icmph->un.reserved[1] = ICMP_EXT_ORIG_DGRAM_MIN_LEN / sizeof(u32); 798 799 return skb; 800 801 free_skb: 802 consume_skb(skb); 803 return NULL; 804 } 805 806 /* 807 * Send an ICMP message in response to a situation 808 * 809 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 810 * MAY send more (we do). 811 * MUST NOT change this header information. 812 * MUST NOT reply to a multicast/broadcast IP address. 813 * MUST NOT reply to a multicast/broadcast MAC address. 814 * MUST reply to only the first fragment. 815 */ 816 817 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 818 const struct inet_skb_parm *parm) 819 { 820 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 821 IP_OPTIONS_DATA_FIXED_SIZE); 822 struct iphdr *iph; 823 int room; 824 struct rtable *rt = skb_rtable(skb_in); 825 bool apply_ratelimit = false; 826 struct sk_buff *ext_skb; 827 struct ipcm_cookie ipc; 828 struct flowi4 fl4; 829 __be32 saddr; 830 u8 tos; 831 u32 mark; 832 struct net *net; 833 struct sock *sk; 834 835 if (!rt) 836 return; 837 838 rcu_read_lock(); 839 840 if (rt->dst.dev) 841 net = dev_net_rcu(rt->dst.dev); 842 else if (skb_in->dev) 843 net = dev_net_rcu(skb_in->dev); 844 else 845 goto out; 846 847 /* 848 * Find the original header. It is expected to be valid, of course. 849 * Check this, icmp_send is called from the most obscure devices 850 * sometimes. 851 */ 852 iph = ip_hdr(skb_in); 853 854 if ((u8 *)iph < skb_in->head || 855 (skb_network_header(skb_in) + sizeof(*iph)) > 856 skb_tail_pointer(skb_in)) 857 goto out; 858 859 /* 860 * No replies to physical multicast/broadcast 861 */ 862 if (skb_in->pkt_type != PACKET_HOST) 863 goto out; 864 865 /* 866 * Now check at the protocol level 867 */ 868 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 869 goto out; 870 871 /* 872 * Only reply to fragment 0. We byte re-order the constant 873 * mask for efficiency. 874 */ 875 if (iph->frag_off & htons(IP_OFFSET)) 876 goto out; 877 878 /* 879 * If we send an ICMP error to an ICMP error a mess would result.. 880 */ 881 if (icmp_pointers[type].error) { 882 /* 883 * We are an error, check if we are replying to an 884 * ICMP error 885 */ 886 if (iph->protocol == IPPROTO_ICMP) { 887 u8 _inner_type, *itp; 888 889 itp = skb_header_pointer(skb_in, 890 skb_network_header(skb_in) + 891 (iph->ihl << 2) + 892 offsetof(struct icmphdr, 893 type) - 894 skb_in->data, 895 sizeof(_inner_type), 896 &_inner_type); 897 if (!itp) 898 goto out; 899 900 /* 901 * Assume any unknown ICMP type is an error. This 902 * isn't specified by the RFC, but think about it.. 903 */ 904 if (*itp > NR_ICMP_TYPES || 905 icmp_pointers[*itp].error) 906 goto out; 907 } 908 } 909 910 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 911 local_bh_disable(); 912 913 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 914 * incoming dev is loopback. If outgoing dev change to not be 915 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 916 */ 917 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 918 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 919 goto out_bh_enable; 920 921 sk = icmp_xmit_lock(net); 922 if (!sk) 923 goto out_bh_enable; 924 925 /* 926 * Construct source address and options. 927 */ 928 929 saddr = iph->daddr; 930 if (!(rt->rt_flags & RTCF_LOCAL)) { 931 struct net_device *dev = NULL; 932 933 rcu_read_lock(); 934 if (rt_is_input_route(rt) && 935 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 936 dev = dev_get_by_index_rcu(net, parm->iif ? parm->iif : 937 inet_iif(skb_in)); 938 939 if (dev) 940 saddr = inet_select_addr(dev, iph->saddr, 941 RT_SCOPE_LINK); 942 else 943 saddr = 0; 944 rcu_read_unlock(); 945 } 946 947 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 948 IPTOS_PREC_INTERNETCONTROL) : 949 iph->tos; 950 mark = IP4_REPLY_MARK(net, skb_in->mark); 951 952 if (__ip_options_echo(net, &icmp_param->replyopts.opt, skb_in, 953 &parm->opt)) 954 goto out_unlock; 955 956 957 /* 958 * Prepare data for ICMP header. 959 */ 960 961 icmp_param->data.icmph.type = type; 962 icmp_param->data.icmph.code = code; 963 icmp_param->data.icmph.un.gateway = info; 964 icmp_param->data.icmph.checksum = 0; 965 icmp_param->skb = skb_in; 966 icmp_param->offset = skb_network_offset(skb_in); 967 ipcm_init(&ipc); 968 ipc.tos = tos; 969 ipc.addr = iph->saddr; 970 ipc.opt = &icmp_param->replyopts; 971 ipc.sockc.mark = mark; 972 973 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 974 inet_dsfield_to_dscp(tos), mark, type, code, 975 icmp_param); 976 if (IS_ERR(rt)) 977 goto out_unlock; 978 979 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 980 goto ende; 981 982 /* peer icmp_ratelimit */ 983 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 984 goto ende; 985 986 /* RFC says return as much as we can without exceeding 576 bytes. */ 987 988 room = dst4_mtu(&rt->dst); 989 if (room > 576) 990 room = 576; 991 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.optlen; 992 room -= sizeof(struct icmphdr); 993 /* Guard against tiny mtu. We need to include at least one 994 * IP network header for this message to make any sense. 995 */ 996 if (room <= (int)sizeof(struct iphdr)) 997 goto ende; 998 999 ext_skb = icmp_ext_append(net, skb_in, &icmp_param->data.icmph, room, 1000 parm->iif); 1001 if (ext_skb) 1002 icmp_param->skb = ext_skb; 1003 1004 icmp_param->data_len = icmp_param->skb->len - icmp_param->offset; 1005 if (icmp_param->data_len > room) 1006 icmp_param->data_len = room; 1007 icmp_param->head_len = sizeof(struct icmphdr); 1008 1009 /* if we don't have a source address at this point, fall back to the 1010 * dummy address instead of sending out a packet with a source address 1011 * of 0.0.0.0 1012 */ 1013 if (!fl4.saddr) 1014 fl4.saddr = htonl(INADDR_DUMMY); 1015 1016 trace_icmp_send(skb_in, type, code); 1017 1018 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 1019 1020 if (ext_skb) 1021 consume_skb(ext_skb); 1022 ende: 1023 ip_rt_put(rt); 1024 out_unlock: 1025 icmp_xmit_unlock(sk); 1026 out_bh_enable: 1027 local_bh_enable(); 1028 out: 1029 rcu_read_unlock(); 1030 } 1031 EXPORT_SYMBOL(__icmp_send); 1032 1033 #if IS_ENABLED(CONFIG_NF_NAT) 1034 #include <net/netfilter/nf_conntrack.h> 1035 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 1036 { 1037 struct sk_buff *cloned_skb = NULL; 1038 enum ip_conntrack_info ctinfo; 1039 enum ip_conntrack_dir dir; 1040 struct inet_skb_parm parm; 1041 struct nf_conn *ct; 1042 __be32 orig_ip; 1043 1044 memset(&parm, 0, sizeof(parm)); 1045 ct = nf_ct_get(skb_in, &ctinfo); 1046 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { 1047 __icmp_send(skb_in, type, code, info, &parm); 1048 return; 1049 } 1050 1051 if (skb_shared(skb_in)) 1052 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 1053 1054 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 1055 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 1056 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 1057 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 1058 goto out; 1059 1060 orig_ip = ip_hdr(skb_in)->saddr; 1061 dir = CTINFO2DIR(ctinfo); 1062 ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; 1063 __icmp_send(skb_in, type, code, info, &parm); 1064 ip_hdr(skb_in)->saddr = orig_ip; 1065 out: 1066 consume_skb(cloned_skb); 1067 } 1068 EXPORT_SYMBOL(icmp_ndo_send); 1069 #endif 1070 1071 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 1072 { 1073 const struct iphdr *iph = (const struct iphdr *)skb->data; 1074 const struct net_protocol *ipprot; 1075 int protocol = iph->protocol; 1076 1077 /* Checkin full IP header plus 8 bytes of protocol to 1078 * avoid additional coding at protocol handlers. 1079 */ 1080 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) 1081 goto out; 1082 1083 /* IPPROTO_RAW sockets are not supposed to receive anything. */ 1084 if (protocol == IPPROTO_RAW) 1085 goto out; 1086 1087 raw_icmp_error(skb, protocol, info); 1088 1089 ipprot = rcu_dereference(inet_protos[protocol]); 1090 if (ipprot && ipprot->err_handler) 1091 ipprot->err_handler(skb, info); 1092 return; 1093 1094 out: 1095 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1096 } 1097 1098 static bool icmp_tag_validation(int proto) 1099 { 1100 const struct net_protocol *ipprot; 1101 bool ok; 1102 1103 rcu_read_lock(); 1104 ipprot = rcu_dereference(inet_protos[proto]); 1105 ok = ipprot ? ipprot->icmp_strict_tag_validation : false; 1106 rcu_read_unlock(); 1107 return ok; 1108 } 1109 1110 /* 1111 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 1112 * ICMP_PARAMETERPROB. 1113 */ 1114 1115 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 1116 { 1117 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 1118 const struct iphdr *iph; 1119 struct icmphdr *icmph; 1120 struct net *net; 1121 u32 info = 0; 1122 1123 net = skb_dst_dev_net_rcu(skb); 1124 1125 /* 1126 * Incomplete header ? 1127 * Only checks for the IP header, there should be an 1128 * additional check for longer headers in upper levels. 1129 */ 1130 1131 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 1132 goto out_err; 1133 1134 icmph = icmp_hdr(skb); 1135 iph = (const struct iphdr *)skb->data; 1136 1137 if (iph->ihl < 5) { /* Mangled header, drop. */ 1138 reason = SKB_DROP_REASON_IP_INHDR; 1139 goto out_err; 1140 } 1141 1142 switch (icmph->type) { 1143 case ICMP_DEST_UNREACH: 1144 switch (icmph->code & 15) { 1145 case ICMP_NET_UNREACH: 1146 case ICMP_HOST_UNREACH: 1147 case ICMP_PROT_UNREACH: 1148 case ICMP_PORT_UNREACH: 1149 break; 1150 case ICMP_FRAG_NEEDED: 1151 /* for documentation of the ip_no_pmtu_disc 1152 * values please see 1153 * Documentation/networking/ip-sysctl.rst 1154 */ 1155 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 1156 default: 1157 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 1158 &iph->daddr); 1159 break; 1160 case 2: 1161 goto out; 1162 case 3: 1163 if (!icmp_tag_validation(iph->protocol)) 1164 goto out; 1165 fallthrough; 1166 case 0: 1167 info = ntohs(icmph->un.frag.mtu); 1168 } 1169 break; 1170 case ICMP_SR_FAILED: 1171 net_dbg_ratelimited("%pI4: Source Route Failed\n", 1172 &iph->daddr); 1173 break; 1174 default: 1175 break; 1176 } 1177 if (icmph->code > NR_ICMP_UNREACH) 1178 goto out; 1179 break; 1180 case ICMP_PARAMETERPROB: 1181 info = ntohl(icmph->un.gateway) >> 24; 1182 break; 1183 case ICMP_TIME_EXCEEDED: 1184 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 1185 if (icmph->code == ICMP_EXC_FRAGTIME) 1186 goto out; 1187 break; 1188 } 1189 1190 /* 1191 * Throw it at our lower layers 1192 * 1193 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 1194 * header. 1195 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 1196 * transport layer. 1197 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 1198 * transport layer. 1199 */ 1200 1201 /* 1202 * Check the other end isn't violating RFC 1122. Some routers send 1203 * bogus responses to broadcast frames. If you see this message 1204 * first check your netmask matches at both ends, if it does then 1205 * get the other vendor to fix their kit. 1206 */ 1207 1208 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 1209 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 1210 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 1211 &ip_hdr(skb)->saddr, 1212 icmph->type, icmph->code, 1213 &iph->daddr, skb->dev->name); 1214 goto out; 1215 } 1216 1217 icmp_socket_deliver(skb, info); 1218 1219 out: 1220 return reason; 1221 out_err: 1222 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1223 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 1224 } 1225 1226 1227 /* 1228 * Handle ICMP_REDIRECT. 1229 */ 1230 1231 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 1232 { 1233 if (skb->len < sizeof(struct iphdr)) { 1234 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 1235 return SKB_DROP_REASON_PKT_TOO_SMALL; 1236 } 1237 1238 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 1239 /* there aught to be a stat */ 1240 return SKB_DROP_REASON_NOMEM; 1241 } 1242 1243 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 1244 return SKB_NOT_DROPPED_YET; 1245 } 1246 1247 /* 1248 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1249 * 1250 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1251 * requests. 1252 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1253 * included in the reply. 1254 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1255 * echo requests, MUST have default=NOT. 1256 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1257 * Extended Echo Functionality, MUST be disabled by default 1258 * See also WRT handling of options once they are done and working. 1259 */ 1260 1261 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1262 { 1263 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1264 IP_OPTIONS_DATA_FIXED_SIZE); 1265 struct net *net; 1266 1267 net = skb_dst_dev_net_rcu(skb); 1268 /* should there be an ICMP stat for ignored echos? */ 1269 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1270 return SKB_NOT_DROPPED_YET; 1271 1272 icmp_param->data.icmph = *icmp_hdr(skb); 1273 icmp_param->skb = skb; 1274 icmp_param->offset = 0; 1275 icmp_param->data_len = skb->len; 1276 icmp_param->head_len = sizeof(struct icmphdr); 1277 1278 if (icmp_param->data.icmph.type == ICMP_ECHO) 1279 icmp_param->data.icmph.type = ICMP_ECHOREPLY; 1280 else if (!icmp_build_probe(skb, &icmp_param->data.icmph)) 1281 return SKB_NOT_DROPPED_YET; 1282 1283 icmp_reply(icmp_param, skb); 1284 return SKB_NOT_DROPPED_YET; 1285 } 1286 1287 /* Helper for icmp_echo and icmpv6_echo_reply. 1288 * Searches for net_device that matches PROBE interface identifier 1289 * and builds PROBE reply message in icmphdr. 1290 * 1291 * Returns false if PROBE responses are disabled via sysctl 1292 */ 1293 1294 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1295 { 1296 struct net *net = dev_net_rcu(skb->dev); 1297 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1298 struct icmp_ext_echo_iio *iio, _iio; 1299 struct inet6_dev *in6_dev; 1300 struct in_device *in_dev; 1301 struct net_device *dev; 1302 char buff[IFNAMSIZ]; 1303 u16 ident_len; 1304 u8 status; 1305 1306 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1307 return false; 1308 1309 /* We currently only support probing interfaces on the proxy node 1310 * Check to ensure L-bit is set 1311 */ 1312 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1313 return false; 1314 /* Clear status bits in reply message */ 1315 icmphdr->un.echo.sequence &= htons(0xFF00); 1316 if (icmphdr->type == ICMP_EXT_ECHO) 1317 icmphdr->type = ICMP_EXT_ECHOREPLY; 1318 else 1319 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1320 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1321 /* Size of iio is class_type dependent. 1322 * Only check header here and assign length based on ctype in the switch statement 1323 */ 1324 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1325 if (!ext_hdr || !iio) 1326 goto send_mal_query; 1327 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1328 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1329 goto send_mal_query; 1330 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1331 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1332 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1333 if (!iio) 1334 goto send_mal_query; 1335 1336 status = 0; 1337 dev = NULL; 1338 switch (iio->extobj_hdr.class_type) { 1339 case ICMP_EXT_ECHO_CTYPE_NAME: 1340 if (ident_len >= IFNAMSIZ) 1341 goto send_mal_query; 1342 memset(buff, 0, sizeof(buff)); 1343 memcpy(buff, &iio->ident.name, ident_len); 1344 dev = dev_get_by_name(net, buff); 1345 break; 1346 case ICMP_EXT_ECHO_CTYPE_INDEX: 1347 if (ident_len != sizeof(iio->ident.ifindex)) 1348 goto send_mal_query; 1349 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1350 break; 1351 case ICMP_EXT_ECHO_CTYPE_ADDR: 1352 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1353 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1354 iio->ident.addr.ctype3_hdr.addrlen) 1355 goto send_mal_query; 1356 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1357 case ICMP_AFI_IP: 1358 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1359 goto send_mal_query; 1360 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1361 break; 1362 #if IS_ENABLED(CONFIG_IPV6) 1363 case ICMP_AFI_IP6: 1364 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1365 goto send_mal_query; 1366 dev = ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1367 dev_hold(dev); 1368 break; 1369 #endif 1370 default: 1371 goto send_mal_query; 1372 } 1373 break; 1374 default: 1375 goto send_mal_query; 1376 } 1377 if (!dev) { 1378 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1379 return true; 1380 } 1381 /* Fill bits in reply message */ 1382 if (dev->flags & IFF_UP) 1383 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1384 1385 in_dev = __in_dev_get_rcu(dev); 1386 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1387 status |= ICMP_EXT_ECHOREPLY_IPV4; 1388 1389 in6_dev = __in6_dev_get(dev); 1390 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1391 status |= ICMP_EXT_ECHOREPLY_IPV6; 1392 1393 dev_put(dev); 1394 icmphdr->un.echo.sequence |= htons(status); 1395 return true; 1396 send_mal_query: 1397 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1398 return true; 1399 } 1400 1401 /* 1402 * Handle ICMP Timestamp requests. 1403 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1404 * SHOULD be in the kernel for minimum random latency. 1405 * MUST be accurate to a few minutes. 1406 * MUST be updated at least at 15Hz. 1407 */ 1408 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1409 { 1410 DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data, 1411 IP_OPTIONS_DATA_FIXED_SIZE); 1412 /* 1413 * Too short. 1414 */ 1415 if (skb->len < 4) 1416 goto out_err; 1417 1418 /* 1419 * Fill in the current time as ms since midnight UT: 1420 */ 1421 icmp_param->data.times[1] = inet_current_timestamp(); 1422 icmp_param->data.times[2] = icmp_param->data.times[1]; 1423 1424 BUG_ON(skb_copy_bits(skb, 0, &icmp_param->data.times[0], 4)); 1425 1426 icmp_param->data.icmph = *icmp_hdr(skb); 1427 icmp_param->data.icmph.type = ICMP_TIMESTAMPREPLY; 1428 icmp_param->data.icmph.code = 0; 1429 icmp_param->skb = skb; 1430 icmp_param->offset = 0; 1431 icmp_param->data_len = 0; 1432 icmp_param->head_len = sizeof(struct icmphdr) + 12; 1433 icmp_reply(icmp_param, skb); 1434 return SKB_NOT_DROPPED_YET; 1435 1436 out_err: 1437 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS); 1438 return SKB_DROP_REASON_PKT_TOO_SMALL; 1439 } 1440 1441 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1442 { 1443 /* pretend it was a success */ 1444 return SKB_NOT_DROPPED_YET; 1445 } 1446 1447 /* 1448 * Deal with incoming ICMP packets. 1449 */ 1450 int icmp_rcv(struct sk_buff *skb) 1451 { 1452 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1453 struct rtable *rt = skb_rtable(skb); 1454 struct net *net = dev_net_rcu(rt->dst.dev); 1455 struct icmphdr *icmph; 1456 1457 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1458 struct sec_path *sp = skb_sec_path(skb); 1459 int nh; 1460 1461 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1462 XFRM_STATE_ICMP)) { 1463 reason = SKB_DROP_REASON_XFRM_POLICY; 1464 goto drop; 1465 } 1466 1467 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1468 goto drop; 1469 1470 nh = skb_network_offset(skb); 1471 skb_set_network_header(skb, sizeof(*icmph)); 1472 1473 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1474 skb)) { 1475 reason = SKB_DROP_REASON_XFRM_POLICY; 1476 goto drop; 1477 } 1478 1479 skb_set_network_header(skb, nh); 1480 } 1481 1482 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1483 1484 if (skb_checksum_simple_validate(skb)) 1485 goto csum_error; 1486 1487 if (!pskb_pull(skb, sizeof(*icmph))) 1488 goto error; 1489 1490 icmph = icmp_hdr(skb); 1491 1492 ICMPMSGIN_INC_STATS(net, icmph->type); 1493 1494 /* Check for ICMP Extended Echo (PROBE) messages */ 1495 if (icmph->type == ICMP_EXT_ECHO) { 1496 /* We can't use icmp_pointers[].handler() because it is an array of 1497 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1498 */ 1499 reason = icmp_echo(skb); 1500 goto reason_check; 1501 } 1502 1503 /* 1504 * Parse the ICMP message 1505 */ 1506 1507 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1508 /* 1509 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1510 * silently ignored (we let user decide with a sysctl). 1511 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1512 * discarded if to broadcast/multicast. 1513 */ 1514 if ((icmph->type == ICMP_ECHO || 1515 icmph->type == ICMP_TIMESTAMP) && 1516 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1517 reason = SKB_DROP_REASON_INVALID_PROTO; 1518 goto error; 1519 } 1520 if (icmph->type != ICMP_ECHO && 1521 icmph->type != ICMP_TIMESTAMP && 1522 icmph->type != ICMP_ADDRESS && 1523 icmph->type != ICMP_ADDRESSREPLY) { 1524 reason = SKB_DROP_REASON_INVALID_PROTO; 1525 goto error; 1526 } 1527 } 1528 1529 if (icmph->type == ICMP_EXT_ECHOREPLY || 1530 icmph->type == ICMP_ECHOREPLY) { 1531 reason = ping_rcv(skb); 1532 return reason ? NET_RX_DROP : NET_RX_SUCCESS; 1533 } 1534 1535 /* 1536 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1537 * 1538 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1539 * discarded. 1540 */ 1541 if (icmph->type > NR_ICMP_TYPES) { 1542 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1543 goto error; 1544 } 1545 1546 reason = icmp_pointers[icmph->type].handler(skb); 1547 reason_check: 1548 if (!reason) { 1549 consume_skb(skb); 1550 return NET_RX_SUCCESS; 1551 } 1552 1553 drop: 1554 kfree_skb_reason(skb, reason); 1555 return NET_RX_DROP; 1556 csum_error: 1557 reason = SKB_DROP_REASON_ICMP_CSUM; 1558 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1559 error: 1560 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1561 goto drop; 1562 } 1563 1564 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1565 { 1566 struct icmp_extobj_hdr *objh, _objh; 1567 struct icmp_ext_hdr *exth, _exth; 1568 u16 olen; 1569 1570 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1571 if (!exth) 1572 return false; 1573 if (exth->version != 2) 1574 return true; 1575 1576 if (exth->checksum && 1577 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1578 return false; 1579 1580 off += sizeof(_exth); 1581 while (off < skb->len) { 1582 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1583 if (!objh) 1584 return false; 1585 1586 olen = ntohs(objh->length); 1587 if (olen < sizeof(_objh)) 1588 return false; 1589 1590 off += olen; 1591 if (off > skb->len) 1592 return false; 1593 } 1594 1595 return true; 1596 } 1597 1598 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1599 struct sock_ee_data_rfc4884 *out, 1600 int thlen, int off) 1601 { 1602 int hlen; 1603 1604 /* original datagram headers: end of icmph to payload (skb->data) */ 1605 hlen = -skb_transport_offset(skb) - thlen; 1606 1607 /* per rfc 4884: minimal datagram length of 128 bytes */ 1608 if (off < 128 || off < hlen) 1609 return; 1610 1611 /* kernel has stripped headers: return payload offset in bytes */ 1612 off -= hlen; 1613 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1614 return; 1615 1616 out->len = off; 1617 1618 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1619 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1620 } 1621 1622 int icmp_err(struct sk_buff *skb, u32 info) 1623 { 1624 struct iphdr *iph = (struct iphdr *)skb->data; 1625 int offset = iph->ihl<<2; 1626 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1627 struct net *net = dev_net_rcu(skb->dev); 1628 int type = icmp_hdr(skb)->type; 1629 int code = icmp_hdr(skb)->code; 1630 1631 /* 1632 * Use ping_err to handle all icmp errors except those 1633 * triggered by ICMP_ECHOREPLY which sent from kernel. 1634 */ 1635 if (icmph->type != ICMP_ECHOREPLY) { 1636 ping_err(skb, offset, info); 1637 return 0; 1638 } 1639 1640 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1641 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1642 else if (type == ICMP_REDIRECT) 1643 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1644 1645 return 0; 1646 } 1647 1648 /* 1649 * This table is the definition of how we handle ICMP. 1650 */ 1651 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1652 [ICMP_ECHOREPLY] = { 1653 .handler = ping_rcv, 1654 }, 1655 [1] = { 1656 .handler = icmp_discard, 1657 .error = 1, 1658 }, 1659 [2] = { 1660 .handler = icmp_discard, 1661 .error = 1, 1662 }, 1663 [ICMP_DEST_UNREACH] = { 1664 .handler = icmp_unreach, 1665 .error = 1, 1666 }, 1667 [ICMP_SOURCE_QUENCH] = { 1668 .handler = icmp_unreach, 1669 .error = 1, 1670 }, 1671 [ICMP_REDIRECT] = { 1672 .handler = icmp_redirect, 1673 .error = 1, 1674 }, 1675 [6] = { 1676 .handler = icmp_discard, 1677 .error = 1, 1678 }, 1679 [7] = { 1680 .handler = icmp_discard, 1681 .error = 1, 1682 }, 1683 [ICMP_ECHO] = { 1684 .handler = icmp_echo, 1685 }, 1686 [9] = { 1687 .handler = icmp_discard, 1688 .error = 1, 1689 }, 1690 [10] = { 1691 .handler = icmp_discard, 1692 .error = 1, 1693 }, 1694 [ICMP_TIME_EXCEEDED] = { 1695 .handler = icmp_unreach, 1696 .error = 1, 1697 }, 1698 [ICMP_PARAMETERPROB] = { 1699 .handler = icmp_unreach, 1700 .error = 1, 1701 }, 1702 [ICMP_TIMESTAMP] = { 1703 .handler = icmp_timestamp, 1704 }, 1705 [ICMP_TIMESTAMPREPLY] = { 1706 .handler = icmp_discard, 1707 }, 1708 [ICMP_INFO_REQUEST] = { 1709 .handler = icmp_discard, 1710 }, 1711 [ICMP_INFO_REPLY] = { 1712 .handler = icmp_discard, 1713 }, 1714 [ICMP_ADDRESS] = { 1715 .handler = icmp_discard, 1716 }, 1717 [ICMP_ADDRESSREPLY] = { 1718 .handler = icmp_discard, 1719 }, 1720 }; 1721 1722 static int __net_init icmp_sk_init(struct net *net) 1723 { 1724 /* Control parameters for ECHO replies. */ 1725 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1726 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1727 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1728 1729 /* Control parameter - ignore bogus broadcast responses? */ 1730 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1731 1732 /* 1733 * Configurable global rate limit. 1734 * 1735 * ratelimit defines tokens/packet consumed for dst->rate_token 1736 * bucket ratemask defines which icmp types are ratelimited by 1737 * setting it's bit position. 1738 * 1739 * default: 1740 * dest unreachable (3), source quench (4), 1741 * time exceeded (11), parameter problem (12) 1742 */ 1743 1744 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1745 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1746 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1747 net->ipv4.sysctl_icmp_errors_extension_mask = 0; 1748 net->ipv4.sysctl_icmp_msgs_per_sec = 10000; 1749 net->ipv4.sysctl_icmp_msgs_burst = 10000; 1750 1751 return 0; 1752 } 1753 1754 static struct pernet_operations __net_initdata icmp_sk_ops = { 1755 .init = icmp_sk_init, 1756 }; 1757 1758 int __init icmp_init(void) 1759 { 1760 int err, i; 1761 1762 for_each_possible_cpu(i) { 1763 struct sock *sk; 1764 1765 err = inet_ctl_sock_create(&sk, PF_INET, 1766 SOCK_RAW, IPPROTO_ICMP, &init_net); 1767 if (err < 0) 1768 return err; 1769 1770 per_cpu(ipv4_icmp_sk, i) = sk; 1771 1772 /* Enough space for 2 64K ICMP packets, including 1773 * sk_buff/skb_shared_info struct overhead. 1774 */ 1775 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1776 1777 /* 1778 * Speedup sock_wfree() 1779 */ 1780 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1781 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1782 } 1783 return register_pernet_subsys(&icmp_sk_ops); 1784 } 1785