ip6_forward.c revision 1.12.2.12
1 /* $NetBSD: ip6_forward.c,v 1.12.2.12 2004/04/07 22:07:34 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 ip6stat.ip6s_cantforward++; 367 ip6stat.ip6s_badscope++; 368 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 369 370 if (ip6_log_time + ip6_log_interval < time_second) { 371 ip6_log_time = time_second; 372 log(LOG_DEBUG, 373 "cannot forward " 374 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 375 ip6_sprintf(&ip6->ip6_src), 376 ip6_sprintf(&ip6->ip6_dst), 377 ip6->ip6_nxt, 378 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 379 } 380 if (mcopy) 381 icmp6_error(mcopy, ICMP6_DST_UNREACH, 382 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 383 m_freem(m); 384 return; 385 } 386 387 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 388 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 389 if (mcopy) { 390 u_long mtu; 391 #ifdef IPSEC 392 struct secpolicy *sp; 393 int ipsecerror; 394 size_t ipsechdrsiz; 395 #endif 396 397 mtu = rt->rt_ifp->if_mtu; 398 #ifdef IPSEC 399 /* 400 * When we do IPsec tunnel ingress, we need to play 401 * with if_mtu value (decrement IPsec header size 402 * from mtu value). The code is much simpler than v4 403 * case, as we have the outgoing interface for 404 * encapsulated packet as "rt->rt_ifp". 405 */ 406 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 407 IP_FORWARDING, &ipsecerror); 408 if (sp) { 409 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 410 IPSEC_DIR_OUTBOUND, NULL); 411 if (ipsechdrsiz < mtu) 412 mtu -= ipsechdrsiz; 413 } 414 415 /* 416 * if mtu becomes less than minimum MTU, 417 * tell minimum MTU (and I'll need to fragment it). 418 */ 419 if (mtu < IPV6_MMTU) 420 mtu = IPV6_MMTU; 421 #endif 422 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 423 } 424 m_freem(m); 425 return; 426 } 427 428 if (rt->rt_flags & RTF_GATEWAY) 429 dst = (struct sockaddr_in6 *)rt->rt_gateway; 430 431 /* 432 * If we are to forward the packet using the same interface 433 * as one we got the packet from, perhaps we should send a redirect 434 * to sender to shortcut a hop. 435 * Only send redirect if source is sending directly to us, 436 * and if packet was not source routed (or has any options). 437 * Also, don't send redirect if forwarding using a route 438 * modified by a redirect. 439 */ 440 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 441 #ifdef IPSEC 442 !ipsecrt && 443 #endif 444 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { 445 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { 446 /* 447 * If the incoming interface is equal to the outgoing 448 * one, and the link attached to the interface is 449 * point-to-point, then it will be highly probable 450 * that a routing loop occurs. Thus, we immediately 451 * drop the packet and send an ICMPv6 error message. 452 * 453 * type/code is based on suggestion by Rich Draves. 454 * not sure if it is the best pick. 455 */ 456 icmp6_error(mcopy, ICMP6_DST_UNREACH, 457 ICMP6_DST_UNREACH_ADDR, 0); 458 m_freem(m); 459 return; 460 } 461 type = ND_REDIRECT; 462 } 463 464 #ifdef IPV6FIREWALL 465 /* 466 * Check with the firewall... 467 */ 468 if (ip6_fw_chk_ptr) { 469 u_short port = 0; 470 /* If ipfw says divert, we have to just drop packet */ 471 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 472 m_freem(m); 473 goto freecopy; 474 } 475 if (!m) 476 goto freecopy; 477 } 478 #endif 479 480 /* 481 * Fake scoped addresses. Note that even link-local source or 482 * destinaion can appear, if the originating node just sends the 483 * packet to us (without address resolution for the destination). 484 * Since both icmp6_error and icmp6_redirect_output fill the embedded 485 * link identifiers, we can do this stuff after make a copy for 486 * returning error. 487 */ 488 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 489 /* 490 * See corresponding comments in ip6_output. 491 * XXX: but is it possible that ip6_forward() sends a packet 492 * to a loopback interface? I don't think so, and thus 493 * I bark here. (jinmei (at) kame.net) 494 * XXX: it is common to route invalid packets to loopback. 495 * also, the codepath will be visited on use of ::1 in 496 * rthdr. (itojun) 497 */ 498 #if 1 499 if (0) 500 #else 501 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 502 #endif 503 { 504 printf("ip6_forward: outgoing interface is loopback. " 505 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 506 ip6_sprintf(&ip6->ip6_src), 507 ip6_sprintf(&ip6->ip6_dst), 508 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 509 if_name(rt->rt_ifp)); 510 } 511 512 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 513 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 514 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 515 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 516 else 517 origifp = rt->rt_ifp; 518 } 519 else 520 origifp = rt->rt_ifp; 521 #ifndef FAKE_LOOPBACK_IF 522 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 523 #else 524 if (1) 525 #endif 526 { 527 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 528 ip6->ip6_src.s6_addr16[1] = 0; 529 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 530 ip6->ip6_dst.s6_addr16[1] = 0; 531 } 532 533 #ifdef PFIL_HOOKS 534 /* 535 * Run through list of hooks for output packets. 536 */ 537 m1 = m; 538 pfh = pfil_hook_get(PFIL_OUT, 539 &inet6sw[ip6_protox[IPPROTO_IPV6]].pr_pfh); 540 for (; pfh; pfh = pfh->pfil_link.tqe_next) 541 if (pfh->pfil_func) { 542 rv = pfh->pfil_func(ip6, sizeof(*ip6), 543 rt->rt_ifp, 1, &m1); 544 m = m1; 545 if (m == NULL) 546 goto freecopy; 547 if (rv) { 548 error = EHOSTUNREACH; 549 goto senderr; 550 } 551 ip6 = mtod(m, struct ip6_hdr *); 552 } 553 #endif /* PFIL_HOOKS */ 554 555 #ifdef OLDIP6OUTPUT 556 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 557 (struct sockaddr *)dst, 558 ip6_forward_rt.ro_rt); 559 #else 560 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 561 #endif 562 if (error) { 563 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 564 ip6stat.ip6s_cantforward++; 565 } else { 566 ip6stat.ip6s_forward++; 567 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 568 if (type) 569 ip6stat.ip6s_redirectsent++; 570 else { 571 if (mcopy) 572 goto freecopy; 573 } 574 } 575 576 #ifdef PFIL_HOOKS 577 senderr: 578 #endif 579 if (mcopy == NULL) 580 return; 581 582 switch (error) { 583 case 0: 584 #if 1 585 if (type == ND_REDIRECT) { 586 icmp6_redirect_output(mcopy, rt); 587 return; 588 } 589 #endif 590 goto freecopy; 591 592 case EMSGSIZE: 593 /* xxx MTU is constant in PPP? */ 594 goto freecopy; 595 596 case ENOBUFS: 597 /* Tell source to slow down like source quench in IP? */ 598 goto freecopy; 599 600 case ENETUNREACH: /* shouldn't happen, checked above */ 601 case EHOSTUNREACH: 602 case ENETDOWN: 603 case EHOSTDOWN: 604 default: 605 type = ICMP6_DST_UNREACH; 606 code = ICMP6_DST_UNREACH_ADDR; 607 break; 608 } 609 icmp6_error(mcopy, type, code, 0); 610 return; 611 612 freecopy: 613 m_freem(mcopy); 614 return; 615 } 616
Indexes created Thu Oct 16 14:10:15 GMT 2025