ip6_forward.c revision 1.17
1 /* $NetBSD: ip6_forward.c,v 1.17 2000/09/22 05:50:23 itojun 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 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/malloc.h> 38 #include <sys/mbuf.h> 39 #include <sys/domain.h> 40 #include <sys/protosw.h> 41 #include <sys/socket.h> 42 #include <sys/errno.h> 43 #include <sys/time.h> 44 #include <sys/kernel.h> 45 #include <sys/syslog.h> 46 47 #include <net/if.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_var.h> 52 #include <netinet/ip_var.h> 53 #include <netinet/ip6.h> 54 #include <netinet6/ip6_var.h> 55 #include <netinet/icmp6.h> 56 #include <netinet6/nd6.h> 57 58 #ifdef IPSEC 59 #include <netinet6/ipsec.h> 60 #include <netkey/key.h> 61 #endif /* IPSEC */ 62 63 #ifdef IPV6FIREWALL 64 #include <netinet6/ip6_fw.h> 65 #endif 66 67 #include <net/net_osdep.h> 68 69 struct route_in6 ip6_forward_rt; 70 71 /* 72 * Forward a packet. If some error occurs return the sender 73 * an icmp packet. Note we can't always generate a meaningful 74 * icmp message because icmp doesn't have a large enough repertoire 75 * of codes and types. 76 * 77 * If not forwarding, just drop the packet. This could be confusing 78 * if ipforwarding was zero but some routing protocol was advancing 79 * us as a gateway to somewhere. However, we must let the routing 80 * protocol deal with that. 81 * 82 */ 83 84 void 85 ip6_forward(m, srcrt) 86 struct mbuf *m; 87 int srcrt; 88 { 89 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 90 register struct sockaddr_in6 *dst; 91 register struct rtentry *rt; 92 int error, type = 0, code = 0; 93 struct mbuf *mcopy = NULL; 94 struct ifnet *origifp; /* maybe unnecessary */ 95 #ifdef IPSEC 96 struct secpolicy *sp = NULL; 97 #endif 98 long time_second = time.tv_sec; 99 100 #ifdef IPSEC 101 /* 102 * Check AH/ESP integrity. 103 */ 104 /* 105 * Don't increment ip6s_cantforward because this is the check 106 * before forwarding packet actually. 107 */ 108 if (ipsec6_in_reject(m, NULL)) { 109 ipsec6stat.in_polvio++; 110 m_freem(m); 111 return; 112 } 113 #endif /*IPSEC*/ 114 115 /* 116 * Do not forward packets to multicast destination (should be handled 117 * by ip6_mforward(). 118 * Do not forward packets with unspecified source. It was discussed 119 * in July 2000, on ipngwg mailing list. 120 */ 121 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 122 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 123 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 124 ip6stat.ip6s_cantforward++; 125 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 126 if (ip6_log_time + ip6_log_interval < time_second) { 127 ip6_log_time = time_second; 128 log(LOG_DEBUG, 129 "cannot forward " 130 "from %s to %s nxt %d received on %s\n", 131 ip6_sprintf(&ip6->ip6_src), 132 ip6_sprintf(&ip6->ip6_dst), 133 ip6->ip6_nxt, 134 if_name(m->m_pkthdr.rcvif)); 135 } 136 m_freem(m); 137 return; 138 } 139 140 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 141 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 142 icmp6_error(m, ICMP6_TIME_EXCEEDED, 143 ICMP6_TIME_EXCEED_TRANSIT, 0); 144 return; 145 } 146 ip6->ip6_hlim -= IPV6_HLIMDEC; 147 148 /* 149 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 150 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 151 * we need to generate an ICMP6 message to the src. 152 * Thanks to M_EXT, in most cases copy will not occur. 153 * 154 * It is important to save it before IPsec processing as IPsec 155 * processing may modify the mbuf. 156 */ 157 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 158 159 #ifdef IPSEC 160 /* get a security policy for this packet */ 161 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING, 162 &error); 163 if (sp == NULL) { 164 ipsec6stat.out_inval++; 165 ip6stat.ip6s_cantforward++; 166 if (mcopy) { 167 #if 0 168 /* XXX: what icmp ? */ 169 #else 170 m_freem(mcopy); 171 #endif 172 } 173 m_freem(m); 174 return; 175 } 176 177 error = 0; 178 179 /* check policy */ 180 switch (sp->policy) { 181 case IPSEC_POLICY_DISCARD: 182 /* 183 * This packet is just discarded. 184 */ 185 ipsec6stat.out_polvio++; 186 ip6stat.ip6s_cantforward++; 187 key_freesp(sp); 188 if (mcopy) { 189 #if 0 190 /* XXX: what icmp ? */ 191 #else 192 m_freem(mcopy); 193 #endif 194 } 195 m_freem(m); 196 return; 197 198 case IPSEC_POLICY_BYPASS: 199 case IPSEC_POLICY_NONE: 200 /* no need to do IPsec. */ 201 key_freesp(sp); 202 goto skip_ipsec; 203 204 case IPSEC_POLICY_IPSEC: 205 if (sp->req == NULL) { 206 /* XXX should be panic ? */ 207 printf("ip6_forward: No IPsec request specified.\n"); 208 ip6stat.ip6s_cantforward++; 209 key_freesp(sp); 210 if (mcopy) { 211 #if 0 212 /* XXX: what icmp ? */ 213 #else 214 m_freem(mcopy); 215 #endif 216 } 217 m_freem(m); 218 return; 219 } 220 /* do IPsec */ 221 break; 222 223 case IPSEC_POLICY_ENTRUST: 224 default: 225 /* should be panic ?? */ 226 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 227 key_freesp(sp); 228 goto skip_ipsec; 229 } 230 231 { 232 struct ipsec_output_state state; 233 234 /* 235 * All the extension headers will become inaccessible 236 * (since they can be encrypted). 237 * Don't panic, we need no more updates to extension headers 238 * on inner IPv6 packet (since they are now encapsulated). 239 * 240 * IPv6 [ESP|AH] IPv6 [extension headers] payload 241 */ 242 bzero(&state, sizeof(state)); 243 state.m = m; 244 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 245 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 246 247 error = ipsec6_output_tunnel(&state, sp, 0); 248 249 m = state.m; 250 #if 0 /* XXX allocate a route (ro, dst) again later */ 251 ro = (struct route_in6 *)state.ro; 252 dst = (struct sockaddr_in6 *)state.dst; 253 #endif 254 key_freesp(sp); 255 256 if (error) { 257 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 258 switch (error) { 259 case EHOSTUNREACH: 260 case ENETUNREACH: 261 case EMSGSIZE: 262 case ENOBUFS: 263 case ENOMEM: 264 break; 265 default: 266 printf("ip6_output (ipsec): error code %d\n", error); 267 /*fall through*/ 268 case ENOENT: 269 /* don't show these error codes to the user */ 270 break; 271 } 272 ip6stat.ip6s_cantforward++; 273 if (mcopy) { 274 #if 0 275 /* XXX: what icmp ? */ 276 #else 277 m_freem(mcopy); 278 #endif 279 } 280 m_freem(m); 281 return; 282 } 283 } 284 skip_ipsec: 285 #endif /* IPSEC */ 286 287 dst = &ip6_forward_rt.ro_dst; 288 if (!srcrt) { 289 /* 290 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 291 */ 292 if (ip6_forward_rt.ro_rt == 0 || 293 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 294 if (ip6_forward_rt.ro_rt) { 295 RTFREE(ip6_forward_rt.ro_rt); 296 ip6_forward_rt.ro_rt = 0; 297 } 298 /* this probably fails but give it a try again */ 299 rtalloc((struct route *)&ip6_forward_rt); 300 } 301 302 if (ip6_forward_rt.ro_rt == 0) { 303 ip6stat.ip6s_noroute++; 304 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 305 if (mcopy) { 306 icmp6_error(mcopy, ICMP6_DST_UNREACH, 307 ICMP6_DST_UNREACH_NOROUTE, 0); 308 } 309 m_freem(m); 310 return; 311 } 312 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 313 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 314 if (ip6_forward_rt.ro_rt) { 315 RTFREE(ip6_forward_rt.ro_rt); 316 ip6_forward_rt.ro_rt = 0; 317 } 318 bzero(dst, sizeof(*dst)); 319 dst->sin6_len = sizeof(struct sockaddr_in6); 320 dst->sin6_family = AF_INET6; 321 dst->sin6_addr = ip6->ip6_dst; 322 323 rtalloc((struct route *)&ip6_forward_rt); 324 if (ip6_forward_rt.ro_rt == 0) { 325 ip6stat.ip6s_noroute++; 326 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 327 if (mcopy) { 328 icmp6_error(mcopy, ICMP6_DST_UNREACH, 329 ICMP6_DST_UNREACH_NOROUTE, 0); 330 } 331 m_freem(m); 332 return; 333 } 334 } 335 rt = ip6_forward_rt.ro_rt; 336 337 /* 338 * Scope check: if a packet can't be delivered to its destination 339 * for the reason that the destination is beyond the scope of the 340 * source address, discard the packet and return an icmp6 destination 341 * unreachable error with Code 2 (beyond scope of source address). 342 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 343 */ 344 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 345 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 346 ip6stat.ip6s_cantforward++; 347 ip6stat.ip6s_badscope++; 348 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 349 350 if (ip6_log_time + ip6_log_interval < time_second) { 351 ip6_log_time = time_second; 352 log(LOG_DEBUG, 353 "cannot forward " 354 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 355 ip6_sprintf(&ip6->ip6_src), 356 ip6_sprintf(&ip6->ip6_dst), 357 ip6->ip6_nxt, 358 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 359 } 360 if (mcopy) 361 icmp6_error(mcopy, ICMP6_DST_UNREACH, 362 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 363 m_freem(m); 364 return; 365 } 366 367 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 368 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 369 if (mcopy) { 370 u_long mtu; 371 #ifdef IPSEC 372 struct secpolicy *sp; 373 int ipsecerror; 374 size_t ipsechdrsiz; 375 #endif 376 377 mtu = rt->rt_ifp->if_mtu; 378 #ifdef IPSEC 379 /* 380 * When we do IPsec tunnel ingress, we need to play 381 * with if_mtu value (decrement IPsec header size 382 * from mtu value). The code is much simpler than v4 383 * case, as we have the outgoing interface for 384 * encapsulated packet as "rt->rt_ifp". 385 */ 386 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 387 IP_FORWARDING, &ipsecerror); 388 if (sp) { 389 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 390 IPSEC_DIR_OUTBOUND, NULL); 391 if (ipsechdrsiz < mtu) 392 mtu -= ipsechdrsiz; 393 } 394 395 /* 396 * if mtu becomes less than minimum MTU, 397 * tell minimum MTU (and I'll need to fragment it). 398 */ 399 if (mtu < IPV6_MMTU) 400 mtu = IPV6_MMTU; 401 #endif 402 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 403 } 404 m_freem(m); 405 return; 406 } 407 408 if (rt->rt_flags & RTF_GATEWAY) 409 dst = (struct sockaddr_in6 *)rt->rt_gateway; 410 411 /* 412 * If we are to forward the packet using the same interface 413 * as one we got the packet from, perhaps we should send a redirect 414 * to sender to shortcut a hop. 415 * Only send redirect if source is sending directly to us, 416 * and if packet was not source routed (or has any options). 417 * Also, don't send redirect if forwarding using a route 418 * modified by a redirect. 419 */ 420 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 421 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 422 type = ND_REDIRECT; 423 424 #ifdef IPV6FIREWALL 425 /* 426 * Check with the firewall... 427 */ 428 if (ip6_fw_chk_ptr) { 429 u_short port = 0; 430 /* If ipfw says divert, we have to just drop packet */ 431 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 432 m_freem(m); 433 goto freecopy; 434 } 435 if (!m) 436 goto freecopy; 437 } 438 #endif 439 440 /* 441 * Fake scoped addresses. Note that even link-local source or 442 * destinaion can appear, if the originating node just sends the 443 * packet to us (without address resolution for the destination). 444 * Since both icmp6_error and icmp6_redirect_output fill the embedded 445 * link identifiers, we can do this stuff after make a copy for 446 * returning error. 447 */ 448 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 449 /* 450 * See corresponding comments in ip6_output. 451 * XXX: but is it possible that ip6_forward() sends a packet 452 * to a loopback interface? I don't think so, and thus 453 * I bark here. (jinmei (at) kame.net) 454 * XXX: it is common to route invalid packets to loopback. 455 * also, the codepath will be visited on use of ::1 in 456 * rthdr. (itojun) 457 */ 458 #if 1 459 if (0) 460 #else 461 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 462 #endif 463 { 464 printf("ip6_forward: outgoing interface is loopback. " 465 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 466 ip6_sprintf(&ip6->ip6_src), 467 ip6_sprintf(&ip6->ip6_dst), 468 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 469 if_name(rt->rt_ifp)); 470 } 471 472 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 473 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 474 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 475 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 476 else 477 origifp = rt->rt_ifp; 478 } 479 else 480 origifp = rt->rt_ifp; 481 #ifndef FAKE_LOOPBACK_IF 482 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 483 #else 484 if (1) 485 #endif 486 { 487 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 488 ip6->ip6_src.s6_addr16[1] = 0; 489 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 490 ip6->ip6_dst.s6_addr16[1] = 0; 491 } 492 493 #ifdef OLDIP6OUTPUT 494 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 495 (struct sockaddr *)dst, 496 ip6_forward_rt.ro_rt); 497 #else 498 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 499 #endif 500 if (error) { 501 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 502 ip6stat.ip6s_cantforward++; 503 } else { 504 ip6stat.ip6s_forward++; 505 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 506 if (type) 507 ip6stat.ip6s_redirectsent++; 508 else { 509 if (mcopy) 510 goto freecopy; 511 } 512 } 513 if (mcopy == NULL) 514 return; 515 516 switch (error) { 517 case 0: 518 #if 1 519 if (type == ND_REDIRECT) { 520 icmp6_redirect_output(mcopy, rt); 521 return; 522 } 523 #endif 524 goto freecopy; 525 526 case EMSGSIZE: 527 /* xxx MTU is constant in PPP? */ 528 goto freecopy; 529 530 case ENOBUFS: 531 /* Tell source to slow down like source quench in IP? */ 532 goto freecopy; 533 534 case ENETUNREACH: /* shouldn't happen, checked above */ 535 case EHOSTUNREACH: 536 case ENETDOWN: 537 case EHOSTDOWN: 538 default: 539 type = ICMP6_DST_UNREACH; 540 code = ICMP6_DST_UNREACH_ADDR; 541 break; 542 } 543 icmp6_error(mcopy, type, code, 0); 544 return; 545 546 freecopy: 547 m_freem(mcopy); 548 return; 549 } 550
Indexes created Thu Sep 25 16:09:42 GMT 2025