ip6_forward.c revision 1.12.2.13
1 /* $NetBSD: ip6_forward.c,v 1.12.2.13 2004/04/07 22:33:37 jmc Exp $ */ 2 /* $KAME: ip6_forward.c,v 1.56 2000/09/22 04:01:37 itojun Exp $ */ 3 4 /* 5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include "opt_ipsec.h" 34 #include "opt_pfil_hooks.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/malloc.h> 39 #include <sys/mbuf.h> 40 #include <sys/domain.h> 41 #include <sys/protosw.h> 42 #include <sys/socket.h> 43 #include <sys/errno.h> 44 #include <sys/time.h> 45 #include <sys/kernel.h> 46 #include <sys/syslog.h> 47 48 #include <net/if.h> 49 #include <net/route.h> 50 #ifdef PFIL_HOOKS 51 #include <net/pfil.h> 52 #endif 53 54 #include <netinet/in.h> 55 #include <netinet/in_var.h> 56 #include <netinet/ip_var.h> 57 #include <netinet/ip6.h> 58 #include <netinet6/ip6_var.h> 59 #include <netinet/icmp6.h> 60 #include <netinet6/nd6.h> 61 #include <netinet6/ip6protosw.h> 62 63 #ifdef IPSEC 64 #include <netinet6/ipsec.h> 65 #include <netkey/key.h> 66 #endif /* IPSEC */ 67 68 #ifdef IPV6FIREWALL 69 #include <netinet6/ip6_fw.h> 70 #endif 71 72 #include <net/net_osdep.h> 73 74 struct route_in6 ip6_forward_rt; 75 76 /* 77 * Forward a packet. If some error occurs return the sender 78 * an icmp packet. Note we can't always generate a meaningful 79 * icmp message because icmp doesn't have a large enough repertoire 80 * of codes and types. 81 * 82 * If not forwarding, just drop the packet. This could be confusing 83 * if ipforwarding was zero but some routing protocol was advancing 84 * us as a gateway to somewhere. However, we must let the routing 85 * protocol deal with that. 86 * 87 */ 88 89 void 90 ip6_forward(m, srcrt) 91 struct mbuf *m; 92 int srcrt; 93 { 94 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 95 register struct sockaddr_in6 *dst; 96 register struct rtentry *rt; 97 int error, type = 0, code = 0; 98 struct mbuf *mcopy = NULL; 99 struct ifnet *origifp; /* maybe unnecessary */ 100 #ifdef PFIL_HOOKS 101 struct packet_filter_hook *pfh; 102 struct mbuf *m1; 103 int rv; 104 #endif /* PFIL_HOOKS */ 105 #ifdef IPSEC 106 struct secpolicy *sp = NULL; 107 int ipsecrt = 0; 108 #endif 109 long time_second = time.tv_sec; 110 111 #ifdef IPSEC 112 /* 113 * Check AH/ESP integrity. 114 */ 115 /* 116 * Don't increment ip6s_cantforward because this is the check 117 * before forwarding packet actually. 118 */ 119 if (ipsec6_in_reject(m, NULL)) { 120 ipsec6stat.in_polvio++; 121 m_freem(m); 122 return; 123 } 124 #endif /*IPSEC*/ 125 126 /* 127 * Do not forward packets to multicast destination (should be handled 128 * by ip6_mforward(). 129 * Do not forward packets with unspecified source. It was discussed 130 * in July 2000, on ipngwg mailing list. 131 */ 132 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 133 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 134 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 135 ip6stat.ip6s_cantforward++; 136 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 137 if (ip6_log_time + ip6_log_interval < time_second) { 138 ip6_log_time = time_second; 139 log(LOG_DEBUG, 140 "cannot forward " 141 "from %s to %s nxt %d received on %s\n", 142 ip6_sprintf(&ip6->ip6_src), 143 ip6_sprintf(&ip6->ip6_dst), 144 ip6->ip6_nxt, 145 if_name(m->m_pkthdr.rcvif)); 146 } 147 m_freem(m); 148 return; 149 } 150 151 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 152 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 153 icmp6_error(m, ICMP6_TIME_EXCEEDED, 154 ICMP6_TIME_EXCEED_TRANSIT, 0); 155 return; 156 } 157 ip6->ip6_hlim -= IPV6_HLIMDEC; 158 159 /* 160 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 161 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 162 * we need to generate an ICMP6 message to the src. 163 * Thanks to M_EXT, in most cases copy will not occur. 164 * 165 * It is important to save it before IPsec processing as IPsec 166 * processing may modify the mbuf. 167 */ 168 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 169 170 #ifdef IPSEC 171 /* get a security policy for this packet */ 172 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING, 173 &error); 174 if (sp == NULL) { 175 ipsec6stat.out_inval++; 176 ip6stat.ip6s_cantforward++; 177 if (mcopy) { 178 #if 0 179 /* XXX: what icmp ? */ 180 #else 181 m_freem(mcopy); 182 #endif 183 } 184 m_freem(m); 185 return; 186 } 187 188 error = 0; 189 190 /* check policy */ 191 switch (sp->policy) { 192 case IPSEC_POLICY_DISCARD: 193 /* 194 * This packet is just discarded. 195 */ 196 ipsec6stat.out_polvio++; 197 ip6stat.ip6s_cantforward++; 198 key_freesp(sp); 199 if (mcopy) { 200 #if 0 201 /* XXX: what icmp ? */ 202 #else 203 m_freem(mcopy); 204 #endif 205 } 206 m_freem(m); 207 return; 208 209 case IPSEC_POLICY_BYPASS: 210 case IPSEC_POLICY_NONE: 211 /* no need to do IPsec. */ 212 key_freesp(sp); 213 goto skip_ipsec; 214 215 case IPSEC_POLICY_IPSEC: 216 if (sp->req == NULL) { 217 /* XXX should be panic ? */ 218 printf("ip6_forward: No IPsec request specified.\n"); 219 ip6stat.ip6s_cantforward++; 220 key_freesp(sp); 221 if (mcopy) { 222 #if 0 223 /* XXX: what icmp ? */ 224 #else 225 m_freem(mcopy); 226 #endif 227 } 228 m_freem(m); 229 return; 230 } 231 /* do IPsec */ 232 break; 233 234 case IPSEC_POLICY_ENTRUST: 235 default: 236 /* should be panic ?? */ 237 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 238 key_freesp(sp); 239 goto skip_ipsec; 240 } 241 242 { 243 struct ipsec_output_state state; 244 245 /* 246 * All the extension headers will become inaccessible 247 * (since they can be encrypted). 248 * Don't panic, we need no more updates to extension headers 249 * on inner IPv6 packet (since they are now encapsulated). 250 * 251 * IPv6 [ESP|AH] IPv6 [extension headers] payload 252 */ 253 bzero(&state, sizeof(state)); 254 state.m = m; 255 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 256 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 257 258 error = ipsec6_output_tunnel(&state, sp, 0); 259 260 m = state.m; 261 key_freesp(sp); 262 263 if (error) { 264 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 265 switch (error) { 266 case EHOSTUNREACH: 267 case ENETUNREACH: 268 case EMSGSIZE: 269 case ENOBUFS: 270 case ENOMEM: 271 break; 272 default: 273 printf("ip6_output (ipsec): error code %d\n", error); 274 /*fall through*/ 275 case ENOENT: 276 /* don't show these error codes to the user */ 277 break; 278 } 279 ip6stat.ip6s_cantforward++; 280 if (mcopy) { 281 #if 0 282 /* XXX: what icmp ? */ 283 #else 284 m_freem(mcopy); 285 #endif 286 } 287 m_freem(m); 288 return; 289 } 290 291 /* adjust pointer */ 292 ip6 = mtod(m, struct ip6_hdr *); 293 rt = state.ro ? state.ro->ro_rt : NULL; 294 dst = (struct sockaddr_in6 *)state.dst; 295 if (dst != NULL && rt != NULL) 296 ipsecrt = 1; 297 } 298 skip_ipsec: 299 300 if (ipsecrt) 301 goto skip_routing; 302 #endif /* IPSEC */ 303 304 dst = &ip6_forward_rt.ro_dst; 305 if (!srcrt) { 306 /* 307 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 308 */ 309 if (ip6_forward_rt.ro_rt == 0 || 310 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 311 if (ip6_forward_rt.ro_rt) { 312 RTFREE(ip6_forward_rt.ro_rt); 313 ip6_forward_rt.ro_rt = 0; 314 } 315 /* this probably fails but give it a try again */ 316 rtalloc((struct route *)&ip6_forward_rt); 317 } 318 319 if (ip6_forward_rt.ro_rt == 0) { 320 ip6stat.ip6s_noroute++; 321 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 322 if (mcopy) { 323 icmp6_error(mcopy, ICMP6_DST_UNREACH, 324 ICMP6_DST_UNREACH_NOROUTE, 0); 325 } 326 m_freem(m); 327 return; 328 } 329 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 330 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 331 if (ip6_forward_rt.ro_rt) { 332 RTFREE(ip6_forward_rt.ro_rt); 333 ip6_forward_rt.ro_rt = 0; 334 } 335 bzero(dst, sizeof(*dst)); 336 dst->sin6_len = sizeof(struct sockaddr_in6); 337 dst->sin6_family = AF_INET6; 338 dst->sin6_addr = ip6->ip6_dst; 339 340 rtalloc((struct route *)&ip6_forward_rt); 341 if (ip6_forward_rt.ro_rt == 0) { 342 ip6stat.ip6s_noroute++; 343 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 344 if (mcopy) { 345 icmp6_error(mcopy, ICMP6_DST_UNREACH, 346 ICMP6_DST_UNREACH_NOROUTE, 0); 347 } 348 m_freem(m); 349 return; 350 } 351 } 352 rt = ip6_forward_rt.ro_rt; 353 #ifdef IPSEC 354 skip_routing:; 355 #endif /* IPSEC */ 356 357 /* 358 * Scope check: if a packet can't be delivered to its destination 359 * for the reason that the destination is beyond the scope of the 360 * source address, discard the packet and return an icmp6 destination 361 * unreachable error with Code 2 (beyond scope of source address). 362 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 363 */ 364 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 365 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src) 366 #ifdef IPSEC 367 && !ipsecrt 368 #endif 369 ) { 370 ip6stat.ip6s_cantforward++; 371 ip6stat.ip6s_badscope++; 372 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 373 374 if (ip6_log_time + ip6_log_interval < time_second) { 375 ip6_log_time = time_second; 376 log(LOG_DEBUG, 377 "cannot forward " 378 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 379 ip6_sprintf(&ip6->ip6_src), 380 ip6_sprintf(&ip6->ip6_dst), 381 ip6->ip6_nxt, 382 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 383 } 384 if (mcopy) 385 icmp6_error(mcopy, ICMP6_DST_UNREACH, 386 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 387 m_freem(m); 388 return; 389 } 390 391 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 392 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 393 if (mcopy) { 394 u_long mtu; 395 #ifdef IPSEC 396 struct secpolicy *sp; 397 int ipsecerror; 398 size_t ipsechdrsiz; 399 #endif 400 401 mtu = rt->rt_ifp->if_mtu; 402 #ifdef IPSEC 403 /* 404 * When we do IPsec tunnel ingress, we need to play 405 * with if_mtu value (decrement IPsec header size 406 * from mtu value). The code is much simpler than v4 407 * case, as we have the outgoing interface for 408 * encapsulated packet as "rt->rt_ifp". 409 */ 410 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 411 IP_FORWARDING, &ipsecerror); 412 if (sp) { 413 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 414 IPSEC_DIR_OUTBOUND, NULL); 415 if (ipsechdrsiz < mtu) 416 mtu -= ipsechdrsiz; 417 } 418 419 /* 420 * if mtu becomes less than minimum MTU, 421 * tell minimum MTU (and I'll need to fragment it). 422 */ 423 if (mtu < IPV6_MMTU) 424 mtu = IPV6_MMTU; 425 #endif 426 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 427 } 428 m_freem(m); 429 return; 430 } 431 432 if (rt->rt_flags & RTF_GATEWAY) 433 dst = (struct sockaddr_in6 *)rt->rt_gateway; 434 435 /* 436 * If we are to forward the packet using the same interface 437 * as one we got the packet from, perhaps we should send a redirect 438 * to sender to shortcut a hop. 439 * Only send redirect if source is sending directly to us, 440 * and if packet was not source routed (or has any options). 441 * Also, don't send redirect if forwarding using a route 442 * modified by a redirect. 443 */ 444 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 445 #ifdef IPSEC 446 !ipsecrt && 447 #endif 448 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { 449 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { 450 /* 451 * If the incoming interface is equal to the outgoing 452 * one, and the link attached to the interface is 453 * point-to-point, then it will be highly probable 454 * that a routing loop occurs. Thus, we immediately 455 * drop the packet and send an ICMPv6 error message. 456 * 457 * type/code is based on suggestion by Rich Draves. 458 * not sure if it is the best pick. 459 */ 460 icmp6_error(mcopy, ICMP6_DST_UNREACH, 461 ICMP6_DST_UNREACH_ADDR, 0); 462 m_freem(m); 463 return; 464 } 465 type = ND_REDIRECT; 466 } 467 468 #ifdef IPV6FIREWALL 469 /* 470 * Check with the firewall... 471 */ 472 if (ip6_fw_chk_ptr) { 473 u_short port = 0; 474 /* If ipfw says divert, we have to just drop packet */ 475 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 476 m_freem(m); 477 goto freecopy; 478 } 479 if (!m) 480 goto freecopy; 481 } 482 #endif 483 484 /* 485 * Fake scoped addresses. Note that even link-local source or 486 * destinaion can appear, if the originating node just sends the 487 * packet to us (without address resolution for the destination). 488 * Since both icmp6_error and icmp6_redirect_output fill the embedded 489 * link identifiers, we can do this stuff after make a copy for 490 * returning error. 491 */ 492 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 493 /* 494 * See corresponding comments in ip6_output. 495 * XXX: but is it possible that ip6_forward() sends a packet 496 * to a loopback interface? I don't think so, and thus 497 * I bark here. (jinmei (at) kame.net) 498 * XXX: it is common to route invalid packets to loopback. 499 * also, the codepath will be visited on use of ::1 in 500 * rthdr. (itojun) 501 */ 502 #if 1 503 if (0) 504 #else 505 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 506 #endif 507 { 508 printf("ip6_forward: outgoing interface is loopback. " 509 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 510 ip6_sprintf(&ip6->ip6_src), 511 ip6_sprintf(&ip6->ip6_dst), 512 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 513 if_name(rt->rt_ifp)); 514 } 515 516 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 517 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 518 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 519 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 520 else 521 origifp = rt->rt_ifp; 522 } 523 else 524 origifp = rt->rt_ifp; 525 #ifndef FAKE_LOOPBACK_IF 526 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 527 #else 528 if (1) 529 #endif 530 { 531 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 532 ip6->ip6_src.s6_addr16[1] = 0; 533 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 534 ip6->ip6_dst.s6_addr16[1] = 0; 535 } 536 537 #ifdef PFIL_HOOKS 538 /* 539 * Run through list of hooks for output packets. 540 */ 541 m1 = m; 542 pfh = pfil_hook_get(PFIL_OUT, 543 &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh); 544 for (; pfh; pfh = pfh->pfil_link.tqe_next) 545 if (pfh->pfil_func) { 546 rv = pfh->pfil_func(ip6, sizeof(*ip6), 547 rt->rt_ifp, 1, &m1); 548 m = m1; 549 if (m == NULL) 550 goto freecopy; 551 if (rv) { 552 error = EHOSTUNREACH; 553 goto senderr; 554 } 555 ip6 = mtod(m, struct ip6_hdr *); 556 } 557 #endif /* PFIL_HOOKS */ 558 559 #ifdef OLDIP6OUTPUT 560 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 561 (struct sockaddr *)dst, 562 ip6_forward_rt.ro_rt); 563 #else 564 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 565 #endif 566 if (error) { 567 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 568 ip6stat.ip6s_cantforward++; 569 } else { 570 ip6stat.ip6s_forward++; 571 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 572 if (type) 573 ip6stat.ip6s_redirectsent++; 574 else { 575 if (mcopy) 576 goto freecopy; 577 } 578 } 579 580 #ifdef PFIL_HOOKS 581 senderr: 582 #endif 583 if (mcopy == NULL) 584 return; 585 586 switch (error) { 587 case 0: 588 #if 1 589 if (type == ND_REDIRECT) { 590 icmp6_redirect_output(mcopy, rt); 591 return; 592 } 593 #endif 594 goto freecopy; 595 596 case EMSGSIZE: 597 /* xxx MTU is constant in PPP? */ 598 goto freecopy; 599 600 case ENOBUFS: 601 /* Tell source to slow down like source quench in IP? */ 602 goto freecopy; 603 604 case ENETUNREACH: /* shouldn't happen, checked above */ 605 case EHOSTUNREACH: 606 case ENETDOWN: 607 case EHOSTDOWN: 608 default: 609 type = ICMP6_DST_UNREACH; 610 code = ICMP6_DST_UNREACH_ADDR; 611 break; 612 } 613 icmp6_error(mcopy, type, code, 0); 614 return; 615 616 freecopy: 617 m_freem(mcopy); 618 return; 619 } 620
Indexes created Wed Oct 15 03:09:54 GMT 2025