1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Internet Control Message Protocol (ICMPv6) 4 * Linux INET6 implementation 5 * 6 * Authors: 7 * Pedro Roque <roque@di.fc.ul.pt> 8 * 9 * Based on net/ipv4/icmp.c 10 * 11 * RFC 1885 12 */ 13 14 /* 15 * Changes: 16 * 17 * Andi Kleen : exception handling 18 * Andi Kleen add rate limits. never reply to a icmp. 19 * add more length checks and other fixes. 20 * yoshfuji : ensure to sent parameter problem for 21 * fragments. 22 * YOSHIFUJI Hideaki @USAGI: added sysctl for icmp rate limit. 23 * Randy Dunlap and 24 * YOSHIFUJI Hideaki @USAGI: Per-interface statistics support 25 * Kazunori MIYAZAWA @USAGI: change output process to use ip6_append_data 26 */ 27 28 #define pr_fmt(fmt) "IPv6: " fmt 29 30 #include <linux/module.h> 31 #include <linux/errno.h> 32 #include <linux/types.h> 33 #include <linux/socket.h> 34 #include <linux/in.h> 35 #include <linux/kernel.h> 36 #include <linux/sockios.h> 37 #include <linux/net.h> 38 #include <linux/skbuff.h> 39 #include <linux/init.h> 40 #include <linux/netfilter.h> 41 #include <linux/slab.h> 42 43 #ifdef CONFIG_SYSCTL 44 #include <linux/sysctl.h> 45 #endif 46 47 #include <linux/inet.h> 48 #include <linux/netdevice.h> 49 #include <linux/icmpv6.h> 50 51 #include <net/ip.h> 52 #include <net/sock.h> 53 54 #include <net/ipv6.h> 55 #include <net/ip6_checksum.h> 56 #include <net/ping.h> 57 #include <net/protocol.h> 58 #include <net/raw.h> 59 #include <net/rawv6.h> 60 #include <net/seg6.h> 61 #include <net/transp_v6.h> 62 #include <net/ip6_route.h> 63 #include <net/addrconf.h> 64 #include <net/icmp.h> 65 #include <net/xfrm.h> 66 #include <net/inet_common.h> 67 #include <net/dsfield.h> 68 #include <net/l3mdev.h> 69 70 #include <linux/uaccess.h> 71 72 static DEFINE_PER_CPU(struct sock *, ipv6_icmp_sk); 73 74 static int icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 75 u8 type, u8 code, int offset, __be32 info) 76 { 77 /* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */ 78 struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset); 79 struct net *net = dev_net(skb->dev); 80 81 if (type == ICMPV6_PKT_TOOBIG) 82 ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL)); 83 else if (type == NDISC_REDIRECT) 84 ip6_redirect(skb, net, skb->dev->ifindex, 0, 85 sock_net_uid(net, NULL)); 86 87 if (!(type & ICMPV6_INFOMSG_MASK)) 88 if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST) 89 ping_err(skb, offset, ntohl(info)); 90 91 return 0; 92 } 93 94 static int icmpv6_rcv(struct sk_buff *skb); 95 96 static const struct inet6_protocol icmpv6_protocol = { 97 .handler = icmpv6_rcv, 98 .err_handler = icmpv6_err, 99 .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL, 100 }; 101 102 /* Called with BH disabled */ 103 static struct sock *icmpv6_xmit_lock(struct net *net) 104 { 105 struct sock *sk; 106 107 sk = this_cpu_read(ipv6_icmp_sk); 108 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 109 /* This can happen if the output path (f.e. SIT or 110 * ip6ip6 tunnel) signals dst_link_failure() for an 111 * outgoing ICMP6 packet. 112 */ 113 return NULL; 114 } 115 sock_net_set(sk, net); 116 return sk; 117 } 118 119 static void icmpv6_xmit_unlock(struct sock *sk) 120 { 121 sock_net_set(sk, &init_net); 122 spin_unlock(&sk->sk_lock.slock); 123 } 124 125 /* 126 * Figure out, may we reply to this packet with icmp error. 127 * 128 * We do not reply, if: 129 * - it was icmp error message. 130 * - it is truncated, so that it is known, that protocol is ICMPV6 131 * (i.e. in the middle of some exthdr) 132 * 133 * --ANK (980726) 134 */ 135 136 static bool is_ineligible(const struct sk_buff *skb) 137 { 138 int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data; 139 int len = skb->len - ptr; 140 __u8 nexthdr = ipv6_hdr(skb)->nexthdr; 141 __be16 frag_off; 142 143 if (len < 0) 144 return true; 145 146 ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off); 147 if (ptr < 0) 148 return false; 149 if (nexthdr == IPPROTO_ICMPV6) { 150 u8 _type, *tp; 151 tp = skb_header_pointer(skb, 152 ptr+offsetof(struct icmp6hdr, icmp6_type), 153 sizeof(_type), &_type); 154 155 /* Based on RFC 8200, Section 4.5 Fragment Header, return 156 * false if this is a fragment packet with no icmp header info. 157 */ 158 if (!tp && frag_off != 0) 159 return false; 160 else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) 161 return true; 162 } 163 return false; 164 } 165 166 static bool icmpv6_mask_allow(struct net *net, int type) 167 { 168 if (type > ICMPV6_MSG_MAX) 169 return true; 170 171 /* Limit if icmp type is set in ratemask. */ 172 if (!test_bit(type, net->ipv6.sysctl.icmpv6_ratemask)) 173 return true; 174 175 return false; 176 } 177 178 static bool icmpv6_global_allow(struct net *net, int type) 179 { 180 if (icmpv6_mask_allow(net, type)) 181 return true; 182 183 if (icmp_global_allow()) 184 return true; 185 186 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 187 return false; 188 } 189 190 /* 191 * Check the ICMP output rate limit 192 */ 193 static bool icmpv6_xrlim_allow(struct sock *sk, u8 type, 194 struct flowi6 *fl6) 195 { 196 struct net *net = sock_net(sk); 197 struct dst_entry *dst; 198 bool res = false; 199 200 if (icmpv6_mask_allow(net, type)) 201 return true; 202 203 /* 204 * Look up the output route. 205 * XXX: perhaps the expire for routing entries cloned by 206 * this lookup should be more aggressive (not longer than timeout). 207 */ 208 dst = ip6_route_output(net, sk, fl6); 209 if (dst->error) { 210 IP6_INC_STATS(net, ip6_dst_idev(dst), 211 IPSTATS_MIB_OUTNOROUTES); 212 } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) { 213 res = true; 214 } else { 215 struct rt6_info *rt = (struct rt6_info *)dst; 216 int tmo = net->ipv6.sysctl.icmpv6_time; 217 struct inet_peer *peer; 218 219 /* Give more bandwidth to wider prefixes. */ 220 if (rt->rt6i_dst.plen < 128) 221 tmo >>= ((128 - rt->rt6i_dst.plen)>>5); 222 223 peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr, 1); 224 res = inet_peer_xrlim_allow(peer, tmo); 225 if (peer) 226 inet_putpeer(peer); 227 } 228 if (!res) 229 __ICMP6_INC_STATS(net, ip6_dst_idev(dst), 230 ICMP6_MIB_RATELIMITHOST); 231 dst_release(dst); 232 return res; 233 } 234 235 static bool icmpv6_rt_has_prefsrc(struct sock *sk, u8 type, 236 struct flowi6 *fl6) 237 { 238 struct net *net = sock_net(sk); 239 struct dst_entry *dst; 240 bool res = false; 241 242 dst = ip6_route_output(net, sk, fl6); 243 if (!dst->error) { 244 struct rt6_info *rt = (struct rt6_info *)dst; 245 struct in6_addr prefsrc; 246 247 rt6_get_prefsrc(rt, &prefsrc); 248 res = !ipv6_addr_any(&prefsrc); 249 } 250 dst_release(dst); 251 return res; 252 } 253 254 /* 255 * an inline helper for the "simple" if statement below 256 * checks if parameter problem report is caused by an 257 * unrecognized IPv6 option that has the Option Type 258 * highest-order two bits set to 10 259 */ 260 261 static bool opt_unrec(struct sk_buff *skb, __u32 offset) 262 { 263 u8 _optval, *op; 264 265 offset += skb_network_offset(skb); 266 op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval); 267 if (!op) 268 return true; 269 return (*op & 0xC0) == 0x80; 270 } 271 272 void icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6, 273 struct icmp6hdr *thdr, int len) 274 { 275 struct sk_buff *skb; 276 struct icmp6hdr *icmp6h; 277 278 skb = skb_peek(&sk->sk_write_queue); 279 if (!skb) 280 return; 281 282 icmp6h = icmp6_hdr(skb); 283 memcpy(icmp6h, thdr, sizeof(struct icmp6hdr)); 284 icmp6h->icmp6_cksum = 0; 285 286 if (skb_queue_len(&sk->sk_write_queue) == 1) { 287 skb->csum = csum_partial(icmp6h, 288 sizeof(struct icmp6hdr), skb->csum); 289 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr, 290 &fl6->daddr, 291 len, fl6->flowi6_proto, 292 skb->csum); 293 } else { 294 __wsum tmp_csum = 0; 295 296 skb_queue_walk(&sk->sk_write_queue, skb) { 297 tmp_csum = csum_add(tmp_csum, skb->csum); 298 } 299 300 tmp_csum = csum_partial(icmp6h, 301 sizeof(struct icmp6hdr), tmp_csum); 302 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr, 303 &fl6->daddr, 304 len, fl6->flowi6_proto, 305 tmp_csum); 306 } 307 ip6_push_pending_frames(sk); 308 } 309 310 struct icmpv6_msg { 311 struct sk_buff *skb; 312 int offset; 313 uint8_t type; 314 }; 315 316 static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 317 { 318 struct icmpv6_msg *msg = (struct icmpv6_msg *) from; 319 struct sk_buff *org_skb = msg->skb; 320 __wsum csum; 321 322 csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset, 323 to, len); 324 skb->csum = csum_block_add(skb->csum, csum, odd); 325 if (!(msg->type & ICMPV6_INFOMSG_MASK)) 326 nf_ct_attach(skb, org_skb); 327 return 0; 328 } 329 330 #if IS_ENABLED(CONFIG_IPV6_MIP6) 331 static void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) 332 { 333 struct ipv6hdr *iph = ipv6_hdr(skb); 334 struct ipv6_destopt_hao *hao; 335 int off; 336 337 if (opt->dsthao) { 338 off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO); 339 if (likely(off >= 0)) { 340 hao = (struct ipv6_destopt_hao *) 341 (skb_network_header(skb) + off); 342 swap(iph->saddr, hao->addr); 343 } 344 } 345 } 346 #else 347 static inline void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) {} 348 #endif 349 350 static struct dst_entry *icmpv6_route_lookup(struct net *net, 351 struct sk_buff *skb, 352 struct sock *sk, 353 struct flowi6 *fl6) 354 { 355 struct dst_entry *dst, *dst2; 356 struct flowi6 fl2; 357 int err; 358 359 err = ip6_dst_lookup(net, sk, &dst, fl6); 360 if (err) 361 return ERR_PTR(err); 362 363 /* 364 * We won't send icmp if the destination is known 365 * anycast unless we need to treat anycast as unicast. 366 */ 367 if (!READ_ONCE(net->ipv6.sysctl.icmpv6_error_anycast_as_unicast) && 368 ipv6_anycast_destination(dst, &fl6->daddr)) { 369 net_dbg_ratelimited("icmp6_send: acast source\n"); 370 dst_release(dst); 371 return ERR_PTR(-EINVAL); 372 } 373 374 /* No need to clone since we're just using its address. */ 375 dst2 = dst; 376 377 dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0); 378 if (!IS_ERR(dst)) { 379 if (dst != dst2) 380 return dst; 381 } else { 382 if (PTR_ERR(dst) == -EPERM) 383 dst = NULL; 384 else 385 return dst; 386 } 387 388 err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6); 389 if (err) 390 goto relookup_failed; 391 392 err = ip6_dst_lookup(net, sk, &dst2, &fl2); 393 if (err) 394 goto relookup_failed; 395 396 dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP); 397 if (!IS_ERR(dst2)) { 398 dst_release(dst); 399 dst = dst2; 400 } else { 401 err = PTR_ERR(dst2); 402 if (err == -EPERM) { 403 dst_release(dst); 404 return dst2; 405 } else 406 goto relookup_failed; 407 } 408 409 relookup_failed: 410 if (dst) 411 return dst; 412 return ERR_PTR(err); 413 } 414 415 static struct net_device *icmp6_dev(const struct sk_buff *skb) 416 { 417 struct net_device *dev = skb->dev; 418 419 /* for local traffic to local address, skb dev is the loopback 420 * device. Check if there is a dst attached to the skb and if so 421 * get the real device index. Same is needed for replies to a link 422 * local address on a device enslaved to an L3 master device 423 */ 424 if (unlikely(dev->ifindex == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) { 425 const struct rt6_info *rt6 = skb_rt6_info(skb); 426 427 /* The destination could be an external IP in Ext Hdr (SRv6, RPL, etc.), 428 * and ip6_null_entry could be set to skb if no route is found. 429 */ 430 if (rt6 && rt6->rt6i_idev) 431 dev = rt6->rt6i_idev->dev; 432 } 433 434 return dev; 435 } 436 437 static int icmp6_iif(const struct sk_buff *skb) 438 { 439 return icmp6_dev(skb)->ifindex; 440 } 441 442 /* 443 * Send an ICMP message in response to a packet in error 444 */ 445 void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, 446 const struct in6_addr *force_saddr, 447 const struct inet6_skb_parm *parm) 448 { 449 struct inet6_dev *idev = NULL; 450 struct ipv6hdr *hdr = ipv6_hdr(skb); 451 struct sock *sk; 452 struct net *net; 453 struct ipv6_pinfo *np; 454 const struct in6_addr *saddr = NULL; 455 struct dst_entry *dst; 456 struct icmp6hdr tmp_hdr; 457 struct flowi6 fl6; 458 struct icmpv6_msg msg; 459 struct ipcm6_cookie ipc6; 460 int iif = 0; 461 int addr_type = 0; 462 int len; 463 u32 mark; 464 465 if ((u8 *)hdr < skb->head || 466 (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb)) 467 return; 468 469 if (!skb->dev) 470 return; 471 net = dev_net(skb->dev); 472 mark = IP6_REPLY_MARK(net, skb->mark); 473 /* 474 * Make sure we respect the rules 475 * i.e. RFC 1885 2.4(e) 476 * Rule (e.1) is enforced by not using icmp6_send 477 * in any code that processes icmp errors. 478 */ 479 addr_type = ipv6_addr_type(&hdr->daddr); 480 481 if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0) || 482 ipv6_chk_acast_addr_src(net, skb->dev, &hdr->daddr)) 483 saddr = &hdr->daddr; 484 485 /* 486 * Dest addr check 487 */ 488 489 if (addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST) { 490 if (type != ICMPV6_PKT_TOOBIG && 491 !(type == ICMPV6_PARAMPROB && 492 code == ICMPV6_UNK_OPTION && 493 (opt_unrec(skb, info)))) 494 return; 495 496 saddr = NULL; 497 } 498 499 addr_type = ipv6_addr_type(&hdr->saddr); 500 501 /* 502 * Source addr check 503 */ 504 505 if (__ipv6_addr_needs_scope_id(addr_type)) { 506 iif = icmp6_iif(skb); 507 } else { 508 /* 509 * The source device is used for looking up which routing table 510 * to use for sending an ICMP error. 511 */ 512 iif = l3mdev_master_ifindex(skb->dev); 513 } 514 515 /* 516 * Must not send error if the source does not uniquely 517 * identify a single node (RFC2463 Section 2.4). 518 * We check unspecified / multicast addresses here, 519 * and anycast addresses will be checked later. 520 */ 521 if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) { 522 net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n", 523 &hdr->saddr, &hdr->daddr); 524 return; 525 } 526 527 /* 528 * Never answer to a ICMP packet. 529 */ 530 if (is_ineligible(skb)) { 531 net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n", 532 &hdr->saddr, &hdr->daddr); 533 return; 534 } 535 536 /* Needed by both icmp_global_allow and icmpv6_xmit_lock */ 537 local_bh_disable(); 538 539 /* Check global sysctl_icmp_msgs_per_sec ratelimit */ 540 if (!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, type)) 541 goto out_bh_enable; 542 543 mip6_addr_swap(skb, parm); 544 545 sk = icmpv6_xmit_lock(net); 546 if (!sk) 547 goto out_bh_enable; 548 549 memset(&fl6, 0, sizeof(fl6)); 550 fl6.flowi6_proto = IPPROTO_ICMPV6; 551 fl6.daddr = hdr->saddr; 552 if (force_saddr) 553 saddr = force_saddr; 554 if (saddr) { 555 fl6.saddr = *saddr; 556 } else if (!icmpv6_rt_has_prefsrc(sk, type, &fl6)) { 557 /* select a more meaningful saddr from input if */ 558 struct net_device *in_netdev; 559 560 in_netdev = dev_get_by_index(net, parm->iif); 561 if (in_netdev) { 562 ipv6_dev_get_saddr(net, in_netdev, &fl6.daddr, 563 inet6_sk(sk)->srcprefs, 564 &fl6.saddr); 565 dev_put(in_netdev); 566 } 567 } 568 fl6.flowi6_mark = mark; 569 fl6.flowi6_oif = iif; 570 fl6.fl6_icmp_type = type; 571 fl6.fl6_icmp_code = code; 572 fl6.flowi6_uid = sock_net_uid(net, NULL); 573 fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, NULL); 574 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6)); 575 576 np = inet6_sk(sk); 577 578 if (!icmpv6_xrlim_allow(sk, type, &fl6)) 579 goto out; 580 581 tmp_hdr.icmp6_type = type; 582 tmp_hdr.icmp6_code = code; 583 tmp_hdr.icmp6_cksum = 0; 584 tmp_hdr.icmp6_pointer = htonl(info); 585 586 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) 587 fl6.flowi6_oif = np->mcast_oif; 588 else if (!fl6.flowi6_oif) 589 fl6.flowi6_oif = np->ucast_oif; 590 591 ipcm6_init_sk(&ipc6, np); 592 ipc6.sockc.mark = mark; 593 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel); 594 595 dst = icmpv6_route_lookup(net, skb, sk, &fl6); 596 if (IS_ERR(dst)) 597 goto out; 598 599 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst); 600 601 msg.skb = skb; 602 msg.offset = skb_network_offset(skb); 603 msg.type = type; 604 605 len = skb->len - msg.offset; 606 len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(struct icmp6hdr)); 607 if (len < 0) { 608 net_dbg_ratelimited("icmp: len problem [%pI6c > %pI6c]\n", 609 &hdr->saddr, &hdr->daddr); 610 goto out_dst_release; 611 } 612 613 rcu_read_lock(); 614 idev = __in6_dev_get(skb->dev); 615 616 if (ip6_append_data(sk, icmpv6_getfrag, &msg, 617 len + sizeof(struct icmp6hdr), 618 sizeof(struct icmp6hdr), 619 &ipc6, &fl6, (struct rt6_info *)dst, 620 MSG_DONTWAIT)) { 621 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS); 622 ip6_flush_pending_frames(sk); 623 } else { 624 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, 625 len + sizeof(struct icmp6hdr)); 626 } 627 rcu_read_unlock(); 628 out_dst_release: 629 dst_release(dst); 630 out: 631 icmpv6_xmit_unlock(sk); 632 out_bh_enable: 633 local_bh_enable(); 634 } 635 EXPORT_SYMBOL(icmp6_send); 636 637 /* Slightly more convenient version of icmp6_send with drop reasons. 638 */ 639 void icmpv6_param_prob_reason(struct sk_buff *skb, u8 code, int pos, 640 enum skb_drop_reason reason) 641 { 642 icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL, IP6CB(skb)); 643 kfree_skb_reason(skb, reason); 644 } 645 646 /* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH 647 * if sufficient data bytes are available 648 * @nhs is the size of the tunnel header(s) : 649 * Either an IPv4 header for SIT encap 650 * an IPv4 header + GRE header for GRE encap 651 */ 652 int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type, 653 unsigned int data_len) 654 { 655 struct in6_addr temp_saddr; 656 struct rt6_info *rt; 657 struct sk_buff *skb2; 658 u32 info = 0; 659 660 if (!pskb_may_pull(skb, nhs + sizeof(struct ipv6hdr) + 8)) 661 return 1; 662 663 /* RFC 4884 (partial) support for ICMP extensions */ 664 if (data_len < 128 || (data_len & 7) || skb->len < data_len) 665 data_len = 0; 666 667 skb2 = data_len ? skb_copy(skb, GFP_ATOMIC) : skb_clone(skb, GFP_ATOMIC); 668 669 if (!skb2) 670 return 1; 671 672 skb_dst_drop(skb2); 673 skb_pull(skb2, nhs); 674 skb_reset_network_header(skb2); 675 676 rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0, 677 skb, 0); 678 679 if (rt && rt->dst.dev) 680 skb2->dev = rt->dst.dev; 681 682 ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr); 683 684 if (data_len) { 685 /* RFC 4884 (partial) support : 686 * insert 0 padding at the end, before the extensions 687 */ 688 __skb_push(skb2, nhs); 689 skb_reset_network_header(skb2); 690 memmove(skb2->data, skb2->data + nhs, data_len - nhs); 691 memset(skb2->data + data_len - nhs, 0, nhs); 692 /* RFC 4884 4.5 : Length is measured in 64-bit words, 693 * and stored in reserved[0] 694 */ 695 info = (data_len/8) << 24; 696 } 697 if (type == ICMP_TIME_EXCEEDED) 698 icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 699 info, &temp_saddr, IP6CB(skb2)); 700 else 701 icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 702 info, &temp_saddr, IP6CB(skb2)); 703 if (rt) 704 ip6_rt_put(rt); 705 706 kfree_skb(skb2); 707 708 return 0; 709 } 710 EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach); 711 712 static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb) 713 { 714 struct net *net = dev_net(skb->dev); 715 struct sock *sk; 716 struct inet6_dev *idev; 717 struct ipv6_pinfo *np; 718 const struct in6_addr *saddr = NULL; 719 struct icmp6hdr *icmph = icmp6_hdr(skb); 720 struct icmp6hdr tmp_hdr; 721 struct flowi6 fl6; 722 struct icmpv6_msg msg; 723 struct dst_entry *dst; 724 struct ipcm6_cookie ipc6; 725 u32 mark = IP6_REPLY_MARK(net, skb->mark); 726 SKB_DR(reason); 727 bool acast; 728 u8 type; 729 730 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) && 731 net->ipv6.sysctl.icmpv6_echo_ignore_multicast) 732 return reason; 733 734 saddr = &ipv6_hdr(skb)->daddr; 735 736 acast = ipv6_anycast_destination(skb_dst(skb), saddr); 737 if (acast && net->ipv6.sysctl.icmpv6_echo_ignore_anycast) 738 return reason; 739 740 if (!ipv6_unicast_destination(skb) && 741 !(net->ipv6.sysctl.anycast_src_echo_reply && acast)) 742 saddr = NULL; 743 744 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST) 745 type = ICMPV6_EXT_ECHO_REPLY; 746 else 747 type = ICMPV6_ECHO_REPLY; 748 749 memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr)); 750 tmp_hdr.icmp6_type = type; 751 752 memset(&fl6, 0, sizeof(fl6)); 753 if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ICMPV6_ECHO_REPLIES) 754 fl6.flowlabel = ip6_flowlabel(ipv6_hdr(skb)); 755 756 fl6.flowi6_proto = IPPROTO_ICMPV6; 757 fl6.daddr = ipv6_hdr(skb)->saddr; 758 if (saddr) 759 fl6.saddr = *saddr; 760 fl6.flowi6_oif = icmp6_iif(skb); 761 fl6.fl6_icmp_type = type; 762 fl6.flowi6_mark = mark; 763 fl6.flowi6_uid = sock_net_uid(net, NULL); 764 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6)); 765 766 local_bh_disable(); 767 sk = icmpv6_xmit_lock(net); 768 if (!sk) 769 goto out_bh_enable; 770 np = inet6_sk(sk); 771 772 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) 773 fl6.flowi6_oif = np->mcast_oif; 774 else if (!fl6.flowi6_oif) 775 fl6.flowi6_oif = np->ucast_oif; 776 777 if (ip6_dst_lookup(net, sk, &dst, &fl6)) 778 goto out; 779 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 780 if (IS_ERR(dst)) 781 goto out; 782 783 /* Check the ratelimit */ 784 if ((!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, ICMPV6_ECHO_REPLY)) || 785 !icmpv6_xrlim_allow(sk, ICMPV6_ECHO_REPLY, &fl6)) 786 goto out_dst_release; 787 788 idev = __in6_dev_get(skb->dev); 789 790 msg.skb = skb; 791 msg.offset = 0; 792 msg.type = type; 793 794 ipcm6_init_sk(&ipc6, np); 795 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst); 796 ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb)); 797 ipc6.sockc.mark = mark; 798 799 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST) 800 if (!icmp_build_probe(skb, (struct icmphdr *)&tmp_hdr)) 801 goto out_dst_release; 802 803 if (ip6_append_data(sk, icmpv6_getfrag, &msg, 804 skb->len + sizeof(struct icmp6hdr), 805 sizeof(struct icmp6hdr), &ipc6, &fl6, 806 (struct rt6_info *)dst, MSG_DONTWAIT)) { 807 __ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS); 808 ip6_flush_pending_frames(sk); 809 } else { 810 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, 811 skb->len + sizeof(struct icmp6hdr)); 812 reason = SKB_CONSUMED; 813 } 814 out_dst_release: 815 dst_release(dst); 816 out: 817 icmpv6_xmit_unlock(sk); 818 out_bh_enable: 819 local_bh_enable(); 820 return reason; 821 } 822 823 enum skb_drop_reason icmpv6_notify(struct sk_buff *skb, u8 type, 824 u8 code, __be32 info) 825 { 826 struct inet6_skb_parm *opt = IP6CB(skb); 827 struct net *net = dev_net(skb->dev); 828 const struct inet6_protocol *ipprot; 829 enum skb_drop_reason reason; 830 int inner_offset; 831 __be16 frag_off; 832 u8 nexthdr; 833 834 reason = pskb_may_pull_reason(skb, sizeof(struct ipv6hdr)); 835 if (reason != SKB_NOT_DROPPED_YET) 836 goto out; 837 838 seg6_icmp_srh(skb, opt); 839 840 nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr; 841 if (ipv6_ext_hdr(nexthdr)) { 842 /* now skip over extension headers */ 843 inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), 844 &nexthdr, &frag_off); 845 if (inner_offset < 0) { 846 SKB_DR_SET(reason, IPV6_BAD_EXTHDR); 847 goto out; 848 } 849 } else { 850 inner_offset = sizeof(struct ipv6hdr); 851 } 852 853 /* Checkin header including 8 bytes of inner protocol header. */ 854 reason = pskb_may_pull_reason(skb, inner_offset + 8); 855 if (reason != SKB_NOT_DROPPED_YET) 856 goto out; 857 858 /* BUGGG_FUTURE: we should try to parse exthdrs in this packet. 859 Without this we will not able f.e. to make source routed 860 pmtu discovery. 861 Corresponding argument (opt) to notifiers is already added. 862 --ANK (980726) 863 */ 864 865 ipprot = rcu_dereference(inet6_protos[nexthdr]); 866 if (ipprot && ipprot->err_handler) 867 ipprot->err_handler(skb, opt, type, code, inner_offset, info); 868 869 raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info); 870 return SKB_CONSUMED; 871 872 out: 873 __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS); 874 return reason; 875 } 876 877 /* 878 * Handle icmp messages 879 */ 880 881 static int icmpv6_rcv(struct sk_buff *skb) 882 { 883 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 884 struct net *net = dev_net(skb->dev); 885 struct net_device *dev = icmp6_dev(skb); 886 struct inet6_dev *idev = __in6_dev_get(dev); 887 const struct in6_addr *saddr, *daddr; 888 struct icmp6hdr *hdr; 889 u8 type; 890 891 if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 892 struct sec_path *sp = skb_sec_path(skb); 893 int nh; 894 895 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 896 XFRM_STATE_ICMP)) { 897 reason = SKB_DROP_REASON_XFRM_POLICY; 898 goto drop_no_count; 899 } 900 901 if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr))) 902 goto drop_no_count; 903 904 nh = skb_network_offset(skb); 905 skb_set_network_header(skb, sizeof(*hdr)); 906 907 if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, 908 skb)) { 909 reason = SKB_DROP_REASON_XFRM_POLICY; 910 goto drop_no_count; 911 } 912 913 skb_set_network_header(skb, nh); 914 } 915 916 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INMSGS); 917 918 saddr = &ipv6_hdr(skb)->saddr; 919 daddr = &ipv6_hdr(skb)->daddr; 920 921 if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) { 922 net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n", 923 saddr, daddr); 924 goto csum_error; 925 } 926 927 if (!pskb_pull(skb, sizeof(*hdr))) 928 goto discard_it; 929 930 hdr = icmp6_hdr(skb); 931 932 type = hdr->icmp6_type; 933 934 ICMP6MSGIN_INC_STATS(dev_net(dev), idev, type); 935 936 switch (type) { 937 case ICMPV6_ECHO_REQUEST: 938 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all) 939 reason = icmpv6_echo_reply(skb); 940 break; 941 case ICMPV6_EXT_ECHO_REQUEST: 942 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all && 943 READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 944 reason = icmpv6_echo_reply(skb); 945 break; 946 947 case ICMPV6_ECHO_REPLY: 948 reason = ping_rcv(skb); 949 break; 950 951 case ICMPV6_EXT_ECHO_REPLY: 952 reason = ping_rcv(skb); 953 break; 954 955 case ICMPV6_PKT_TOOBIG: 956 /* BUGGG_FUTURE: if packet contains rthdr, we cannot update 957 standard destination cache. Seems, only "advanced" 958 destination cache will allow to solve this problem 959 --ANK (980726) 960 */ 961 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) 962 goto discard_it; 963 hdr = icmp6_hdr(skb); 964 965 /* to notify */ 966 fallthrough; 967 case ICMPV6_DEST_UNREACH: 968 case ICMPV6_TIME_EXCEED: 969 case ICMPV6_PARAMPROB: 970 reason = icmpv6_notify(skb, type, hdr->icmp6_code, 971 hdr->icmp6_mtu); 972 break; 973 974 case NDISC_ROUTER_SOLICITATION: 975 case NDISC_ROUTER_ADVERTISEMENT: 976 case NDISC_NEIGHBOUR_SOLICITATION: 977 case NDISC_NEIGHBOUR_ADVERTISEMENT: 978 case NDISC_REDIRECT: 979 reason = ndisc_rcv(skb); 980 break; 981 982 case ICMPV6_MGM_QUERY: 983 igmp6_event_query(skb); 984 return 0; 985 986 case ICMPV6_MGM_REPORT: 987 igmp6_event_report(skb); 988 return 0; 989 990 case ICMPV6_MGM_REDUCTION: 991 case ICMPV6_NI_QUERY: 992 case ICMPV6_NI_REPLY: 993 case ICMPV6_MLD2_REPORT: 994 case ICMPV6_DHAAD_REQUEST: 995 case ICMPV6_DHAAD_REPLY: 996 case ICMPV6_MOBILE_PREFIX_SOL: 997 case ICMPV6_MOBILE_PREFIX_ADV: 998 break; 999 1000 default: 1001 /* informational */ 1002 if (type & ICMPV6_INFOMSG_MASK) 1003 break; 1004 1005 net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n", 1006 saddr, daddr); 1007 1008 /* 1009 * error of unknown type. 1010 * must pass to upper level 1011 */ 1012 1013 reason = icmpv6_notify(skb, type, hdr->icmp6_code, 1014 hdr->icmp6_mtu); 1015 } 1016 1017 /* until the v6 path can be better sorted assume failure and 1018 * preserve the status quo behaviour for the rest of the paths to here 1019 */ 1020 if (reason) 1021 kfree_skb_reason(skb, reason); 1022 else 1023 consume_skb(skb); 1024 1025 return 0; 1026 1027 csum_error: 1028 reason = SKB_DROP_REASON_ICMP_CSUM; 1029 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS); 1030 discard_it: 1031 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS); 1032 drop_no_count: 1033 kfree_skb_reason(skb, reason); 1034 return 0; 1035 } 1036 1037 void icmpv6_flow_init(struct sock *sk, struct flowi6 *fl6, 1038 u8 type, 1039 const struct in6_addr *saddr, 1040 const struct in6_addr *daddr, 1041 int oif) 1042 { 1043 memset(fl6, 0, sizeof(*fl6)); 1044 fl6->saddr = *saddr; 1045 fl6->daddr = *daddr; 1046 fl6->flowi6_proto = IPPROTO_ICMPV6; 1047 fl6->fl6_icmp_type = type; 1048 fl6->fl6_icmp_code = 0; 1049 fl6->flowi6_oif = oif; 1050 security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6)); 1051 } 1052 1053 int __init icmpv6_init(void) 1054 { 1055 struct sock *sk; 1056 int err, i; 1057 1058 for_each_possible_cpu(i) { 1059 err = inet_ctl_sock_create(&sk, PF_INET6, 1060 SOCK_RAW, IPPROTO_ICMPV6, &init_net); 1061 if (err < 0) { 1062 pr_err("Failed to initialize the ICMP6 control socket (err %d)\n", 1063 err); 1064 return err; 1065 } 1066 1067 per_cpu(ipv6_icmp_sk, i) = sk; 1068 1069 /* Enough space for 2 64K ICMP packets, including 1070 * sk_buff struct overhead. 1071 */ 1072 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1073 } 1074 1075 err = -EAGAIN; 1076 if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0) 1077 goto fail; 1078 1079 err = inet6_register_icmp_sender(icmp6_send); 1080 if (err) 1081 goto sender_reg_err; 1082 return 0; 1083 1084 sender_reg_err: 1085 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6); 1086 fail: 1087 pr_err("Failed to register ICMP6 protocol\n"); 1088 return err; 1089 } 1090 1091 void icmpv6_cleanup(void) 1092 { 1093 inet6_unregister_icmp_sender(icmp6_send); 1094 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6); 1095 } 1096 1097 1098 static const struct icmp6_err { 1099 int err; 1100 int fatal; 1101 } tab_unreach[] = { 1102 { /* NOROUTE */ 1103 .err = ENETUNREACH, 1104 .fatal = 0, 1105 }, 1106 { /* ADM_PROHIBITED */ 1107 .err = EACCES, 1108 .fatal = 1, 1109 }, 1110 { /* Was NOT_NEIGHBOUR, now reserved */ 1111 .err = EHOSTUNREACH, 1112 .fatal = 0, 1113 }, 1114 { /* ADDR_UNREACH */ 1115 .err = EHOSTUNREACH, 1116 .fatal = 0, 1117 }, 1118 { /* PORT_UNREACH */ 1119 .err = ECONNREFUSED, 1120 .fatal = 1, 1121 }, 1122 { /* POLICY_FAIL */ 1123 .err = EACCES, 1124 .fatal = 1, 1125 }, 1126 { /* REJECT_ROUTE */ 1127 .err = EACCES, 1128 .fatal = 1, 1129 }, 1130 }; 1131 1132 int icmpv6_err_convert(u8 type, u8 code, int *err) 1133 { 1134 int fatal = 0; 1135 1136 *err = EPROTO; 1137 1138 switch (type) { 1139 case ICMPV6_DEST_UNREACH: 1140 fatal = 1; 1141 if (code < ARRAY_SIZE(tab_unreach)) { 1142 *err = tab_unreach[code].err; 1143 fatal = tab_unreach[code].fatal; 1144 } 1145 break; 1146 1147 case ICMPV6_PKT_TOOBIG: 1148 *err = EMSGSIZE; 1149 break; 1150 1151 case ICMPV6_PARAMPROB: 1152 *err = EPROTO; 1153 fatal = 1; 1154 break; 1155 1156 case ICMPV6_TIME_EXCEED: 1157 *err = EHOSTUNREACH; 1158 break; 1159 } 1160 1161 return fatal; 1162 } 1163 EXPORT_SYMBOL(icmpv6_err_convert); 1164 1165 #ifdef CONFIG_SYSCTL 1166 static struct ctl_table ipv6_icmp_table_template[] = { 1167 { 1168 .procname = "ratelimit", 1169 .data = &init_net.ipv6.sysctl.icmpv6_time, 1170 .maxlen = sizeof(int), 1171 .mode = 0644, 1172 .proc_handler = proc_dointvec_ms_jiffies, 1173 }, 1174 { 1175 .procname = "echo_ignore_all", 1176 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_all, 1177 .maxlen = sizeof(u8), 1178 .mode = 0644, 1179 .proc_handler = proc_dou8vec_minmax, 1180 }, 1181 { 1182 .procname = "echo_ignore_multicast", 1183 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_multicast, 1184 .maxlen = sizeof(u8), 1185 .mode = 0644, 1186 .proc_handler = proc_dou8vec_minmax, 1187 }, 1188 { 1189 .procname = "echo_ignore_anycast", 1190 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_anycast, 1191 .maxlen = sizeof(u8), 1192 .mode = 0644, 1193 .proc_handler = proc_dou8vec_minmax, 1194 }, 1195 { 1196 .procname = "ratemask", 1197 .data = &init_net.ipv6.sysctl.icmpv6_ratemask_ptr, 1198 .maxlen = ICMPV6_MSG_MAX + 1, 1199 .mode = 0644, 1200 .proc_handler = proc_do_large_bitmap, 1201 }, 1202 { 1203 .procname = "error_anycast_as_unicast", 1204 .data = &init_net.ipv6.sysctl.icmpv6_error_anycast_as_unicast, 1205 .maxlen = sizeof(u8), 1206 .mode = 0644, 1207 .proc_handler = proc_dou8vec_minmax, 1208 .extra1 = SYSCTL_ZERO, 1209 .extra2 = SYSCTL_ONE, 1210 }, 1211 { }, 1212 }; 1213 1214 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net) 1215 { 1216 struct ctl_table *table; 1217 1218 table = kmemdup(ipv6_icmp_table_template, 1219 sizeof(ipv6_icmp_table_template), 1220 GFP_KERNEL); 1221 1222 if (table) { 1223 table[0].data = &net->ipv6.sysctl.icmpv6_time; 1224 table[1].data = &net->ipv6.sysctl.icmpv6_echo_ignore_all; 1225 table[2].data = &net->ipv6.sysctl.icmpv6_echo_ignore_multicast; 1226 table[3].data = &net->ipv6.sysctl.icmpv6_echo_ignore_anycast; 1227 table[4].data = &net->ipv6.sysctl.icmpv6_ratemask_ptr; 1228 table[5].data = &net->ipv6.sysctl.icmpv6_error_anycast_as_unicast; 1229 } 1230 return table; 1231 } 1232 #endif 1233