ip6_forward.c revision 1.12
1 /* $NetBSD: ip6_forward.c,v 1.12 2000/06/03 14:36:36 itojun Exp $ */ 2 /* $KAME: ip6_forward.c,v 1.37 2000/05/28 12:17:19 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 <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/malloc.h> 36 #include <sys/mbuf.h> 37 #include <sys/domain.h> 38 #include <sys/protosw.h> 39 #include <sys/socket.h> 40 #include <sys/errno.h> 41 #include <sys/time.h> 42 #include <sys/kernel.h> 43 #include <sys/syslog.h> 44 45 #include <net/if.h> 46 #include <net/route.h> 47 48 #include <netinet/in.h> 49 #include <netinet/in_var.h> 50 #include <netinet/ip_var.h> 51 #include <netinet/ip6.h> 52 #include <netinet6/ip6_var.h> 53 #include <netinet/icmp6.h> 54 #include <netinet6/nd6.h> 55 56 #ifdef IPSEC_IPV6FWD 57 #include <netinet6/ipsec.h> 58 #include <netkey/key.h> 59 #include <netkey/key_debug.h> 60 #endif /* IPSEC_IPV6FWD */ 61 62 #ifdef IPV6FIREWALL 63 #include <netinet6/ip6_fw.h> 64 #endif 65 66 #include <net/net_osdep.h> 67 68 struct route_in6 ip6_forward_rt; 69 70 /* 71 * Forward a packet. If some error occurs return the sender 72 * an icmp packet. Note we can't always generate a meaningful 73 * icmp message because icmp doesn't have a large enough repertoire 74 * of codes and types. 75 * 76 * If not forwarding, just drop the packet. This could be confusing 77 * if ipforwarding was zero but some routing protocol was advancing 78 * us as a gateway to somewhere. However, we must let the routing 79 * protocol deal with that. 80 * 81 */ 82 83 void 84 ip6_forward(m, srcrt) 85 struct mbuf *m; 86 int srcrt; 87 { 88 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 89 register struct sockaddr_in6 *dst; 90 register struct rtentry *rt; 91 int error, type = 0, code = 0; 92 struct mbuf *mcopy = NULL; 93 struct ifnet *origifp; /* maybe unnecessary */ 94 #ifdef IPSEC_IPV6FWD 95 struct secpolicy *sp = NULL; 96 #endif 97 long time_second = time.tv_sec; 98 99 #ifdef IPSEC_IPV6FWD 100 /* 101 * Check AH/ESP integrity. 102 */ 103 /* 104 * Don't increment ip6s_cantforward because this is the check 105 * before forwarding packet actually. 106 */ 107 if (ipsec6_in_reject(m, NULL)) { 108 ipsec6stat.in_polvio++; 109 m_freem(m); 110 return; 111 } 112 #endif /*IPSEC_IPV6FWD*/ 113 114 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 115 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 116 ip6stat.ip6s_cantforward++; 117 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 118 if (ip6_log_time + ip6_log_interval < time_second) { 119 ip6_log_time = time_second; 120 log(LOG_DEBUG, 121 "cannot forward " 122 "from %s to %s nxt %d received on %s\n", 123 ip6_sprintf(&ip6->ip6_src), 124 ip6_sprintf(&ip6->ip6_dst), 125 ip6->ip6_nxt, 126 if_name(m->m_pkthdr.rcvif)); 127 } 128 m_freem(m); 129 return; 130 } 131 132 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 133 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 134 icmp6_error(m, ICMP6_TIME_EXCEEDED, 135 ICMP6_TIME_EXCEED_TRANSIT, 0); 136 return; 137 } 138 ip6->ip6_hlim -= IPV6_HLIMDEC; 139 140 /* 141 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 142 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 143 * we need to generate an ICMP6 message to the src. 144 * Thanks to M_EXT, in most cases copy will not occur. 145 * 146 * It is important to save it before IPsec processing as IPsec 147 * processing may modify the mbuf. 148 */ 149 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 150 151 #ifdef IPSEC_IPV6FWD 152 /* get a security policy for this packet */ 153 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error); 154 if (sp == NULL) { 155 ipsec6stat.out_inval++; 156 ip6stat.ip6s_cantforward++; 157 if (mcopy) { 158 #if 0 159 /* XXX: what icmp ? */ 160 #else 161 m_freem(mcopy); 162 #endif 163 } 164 m_freem(m); 165 return; 166 } 167 168 error = 0; 169 170 /* check policy */ 171 switch (sp->policy) { 172 case IPSEC_POLICY_DISCARD: 173 /* 174 * This packet is just discarded. 175 */ 176 ipsec6stat.out_polvio++; 177 ip6stat.ip6s_cantforward++; 178 key_freesp(sp); 179 if (mcopy) { 180 #if 0 181 /* XXX: what icmp ? */ 182 #else 183 m_freem(mcopy); 184 #endif 185 } 186 m_freem(m); 187 return; 188 189 case IPSEC_POLICY_BYPASS: 190 case IPSEC_POLICY_NONE: 191 /* no need to do IPsec. */ 192 key_freesp(sp); 193 goto skip_ipsec; 194 195 case IPSEC_POLICY_IPSEC: 196 if (sp->req == NULL) { 197 /* XXX should be panic ? */ 198 printf("ip6_forward: No IPsec request specified.\n"); 199 ip6stat.ip6s_cantforward++; 200 key_freesp(sp); 201 if (mcopy) { 202 #if 0 203 /* XXX: what icmp ? */ 204 #else 205 m_freem(mcopy); 206 #endif 207 } 208 m_freem(m); 209 return; 210 } 211 /* do IPsec */ 212 break; 213 214 case IPSEC_POLICY_ENTRUST: 215 default: 216 /* should be panic ?? */ 217 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 218 key_freesp(sp); 219 goto skip_ipsec; 220 } 221 222 { 223 struct ipsec_output_state state; 224 225 /* 226 * All the extension headers will become inaccessible 227 * (since they can be encrypted). 228 * Don't panic, we need no more updates to extension headers 229 * on inner IPv6 packet (since they are now encapsulated). 230 * 231 * IPv6 [ESP|AH] IPv6 [extension headers] payload 232 */ 233 bzero(&state, sizeof(state)); 234 state.m = m; 235 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 236 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 237 238 error = ipsec6_output_tunnel(&state, sp, 0); 239 240 m = state.m; 241 #if 0 /* XXX allocate a route (ro, dst) again later */ 242 ro = (struct route_in6 *)state.ro; 243 dst = (struct sockaddr_in6 *)state.dst; 244 #endif 245 key_freesp(sp); 246 247 if (error) { 248 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 249 switch (error) { 250 case EHOSTUNREACH: 251 case ENETUNREACH: 252 case EMSGSIZE: 253 case ENOBUFS: 254 case ENOMEM: 255 break; 256 default: 257 printf("ip6_output (ipsec): error code %d\n", error); 258 /*fall through*/ 259 case ENOENT: 260 /* don't show these error codes to the user */ 261 break; 262 } 263 ip6stat.ip6s_cantforward++; 264 if (mcopy) { 265 #if 0 266 /* XXX: what icmp ? */ 267 #else 268 m_freem(mcopy); 269 #endif 270 } 271 m_freem(m); 272 return; 273 } 274 } 275 skip_ipsec: 276 #endif /* IPSEC_IPV6FWD */ 277 278 dst = &ip6_forward_rt.ro_dst; 279 if (!srcrt) { 280 /* 281 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 282 */ 283 if (ip6_forward_rt.ro_rt == 0 || 284 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 285 if (ip6_forward_rt.ro_rt) { 286 RTFREE(ip6_forward_rt.ro_rt); 287 ip6_forward_rt.ro_rt = 0; 288 } 289 /* this probably fails but give it a try again */ 290 rtalloc((struct route *)&ip6_forward_rt); 291 } 292 293 if (ip6_forward_rt.ro_rt == 0) { 294 ip6stat.ip6s_noroute++; 295 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 296 if (mcopy) { 297 icmp6_error(mcopy, ICMP6_DST_UNREACH, 298 ICMP6_DST_UNREACH_NOROUTE, 0); 299 } 300 m_freem(m); 301 return; 302 } 303 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 304 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 305 if (ip6_forward_rt.ro_rt) { 306 RTFREE(ip6_forward_rt.ro_rt); 307 ip6_forward_rt.ro_rt = 0; 308 } 309 bzero(dst, sizeof(*dst)); 310 dst->sin6_len = sizeof(struct sockaddr_in6); 311 dst->sin6_family = AF_INET6; 312 dst->sin6_addr = ip6->ip6_dst; 313 314 rtalloc((struct route *)&ip6_forward_rt); 315 if (ip6_forward_rt.ro_rt == 0) { 316 ip6stat.ip6s_noroute++; 317 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 318 if (mcopy) { 319 icmp6_error(mcopy, ICMP6_DST_UNREACH, 320 ICMP6_DST_UNREACH_NOROUTE, 0); 321 } 322 m_freem(m); 323 return; 324 } 325 } 326 rt = ip6_forward_rt.ro_rt; 327 328 /* 329 * Scope check: if a packet can't be delivered to its destination 330 * for the reason that the destination is beyond the scope of the 331 * source address, discard the packet and return an icmp6 destination 332 * unreachable error with Code 2 (beyond scope of source address). 333 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 334 */ 335 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 336 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 337 ip6stat.ip6s_cantforward++; 338 ip6stat.ip6s_badscope++; 339 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 340 341 if (ip6_log_time + ip6_log_interval < time_second) { 342 ip6_log_time = time_second; 343 log(LOG_DEBUG, 344 "cannot forward " 345 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 346 ip6_sprintf(&ip6->ip6_src), 347 ip6_sprintf(&ip6->ip6_dst), 348 ip6->ip6_nxt, 349 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 350 } 351 if (mcopy) 352 icmp6_error(mcopy, ICMP6_DST_UNREACH, 353 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 354 m_freem(m); 355 return; 356 } 357 358 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 359 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 360 if (mcopy) { 361 u_long mtu; 362 #ifdef IPSEC_IPV6FWD 363 struct secpolicy *sp; 364 int ipsecerror; 365 size_t ipsechdrsiz; 366 #endif 367 368 mtu = rt->rt_ifp->if_mtu; 369 #ifdef IPSEC_IPV6FWD 370 /* 371 * When we do IPsec tunnel ingress, we need to play 372 * with if_mtu value (decrement IPsec header size 373 * from mtu value). The code is much simpler than v4 374 * case, as we have the outgoing interface for 375 * encapsulated packet as "rt->rt_ifp". 376 */ 377 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 378 IP_FORWARDING, &ipsecerror); 379 if (sp) { 380 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 381 IPSEC_DIR_OUTBOUND, NULL); 382 if (ipsechdrsiz < mtu) 383 mtu -= ipsechdrsiz; 384 } 385 386 /* 387 * if mtu becomes less than minimum MTU, 388 * tell minimum MTU (and I'll need to fragment it). 389 */ 390 if (mtu < IPV6_MMTU) 391 mtu = IPV6_MMTU; 392 #endif 393 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 394 } 395 m_freem(m); 396 return; 397 } 398 399 if (rt->rt_flags & RTF_GATEWAY) 400 dst = (struct sockaddr_in6 *)rt->rt_gateway; 401 402 /* 403 * If we are to forward the packet using the same interface 404 * as one we got the packet from, perhaps we should send a redirect 405 * to sender to shortcut a hop. 406 * Only send redirect if source is sending directly to us, 407 * and if packet was not source routed (or has any options). 408 * Also, don't send redirect if forwarding using a route 409 * modified by a redirect. 410 */ 411 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 412 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 413 type = ND_REDIRECT; 414 415 #ifdef IPV6FIREWALL 416 /* 417 * Check with the firewall... 418 */ 419 if (ip6_fw_chk_ptr) { 420 u_short port = 0; 421 /* If ipfw says divert, we have to just drop packet */ 422 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 423 m_freem(m); 424 goto freecopy; 425 } 426 if (!m) 427 goto freecopy; 428 } 429 #endif 430 431 /* 432 * Fake scoped addresses. Note that even link-local source or 433 * destinaion can appear, if the originating node just sends the 434 * packet to us (without address resolution for the destination). 435 * Since both icmp6_error and icmp6_redirect_output fill the embedded 436 * link identifiers, we can do this stuff after make a copy for 437 * returning error. 438 */ 439 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 440 /* 441 * See corresponding comments in ip6_output. 442 * XXX: but is it possible that ip6_forward() sends a packet 443 * to a loopback interface? I don't think so, and thus 444 * I bark here. (jinmei (at) kame.net) 445 * XXX: it is common to route invalid packets to loopback. 446 * (itojun) 447 */ 448 449 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) { 450 printf("ip6_forward: outgoing interface is loopback. " 451 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 452 ip6_sprintf(&ip6->ip6_src), 453 ip6_sprintf(&ip6->ip6_dst), 454 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 455 if_name(rt->rt_ifp)); 456 } 457 458 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 459 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 460 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 461 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 462 else 463 origifp = rt->rt_ifp; 464 } 465 else 466 origifp = rt->rt_ifp; 467 #ifndef FAKE_LOOPBACK_IF 468 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 469 #else 470 if (1) 471 #endif 472 { 473 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 474 ip6->ip6_src.s6_addr16[1] = 0; 475 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 476 ip6->ip6_dst.s6_addr16[1] = 0; 477 } 478 479 #ifdef OLDIP6OUTPUT 480 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 481 (struct sockaddr *)dst, 482 ip6_forward_rt.ro_rt); 483 #else 484 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 485 #endif 486 if (error) { 487 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 488 ip6stat.ip6s_cantforward++; 489 } else { 490 ip6stat.ip6s_forward++; 491 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 492 if (type) 493 ip6stat.ip6s_redirectsent++; 494 else { 495 if (mcopy) 496 goto freecopy; 497 } 498 } 499 if (mcopy == NULL) 500 return; 501 502 switch (error) { 503 case 0: 504 #if 1 505 if (type == ND_REDIRECT) { 506 icmp6_redirect_output(mcopy, rt); 507 return; 508 } 509 #endif 510 goto freecopy; 511 512 case EMSGSIZE: 513 /* xxx MTU is constant in PPP? */ 514 goto freecopy; 515 516 case ENOBUFS: 517 /* Tell source to slow down like source quench in IP? */ 518 goto freecopy; 519 520 case ENETUNREACH: /* shouldn't happen, checked above */ 521 case EHOSTUNREACH: 522 case ENETDOWN: 523 case EHOSTDOWN: 524 default: 525 type = ICMP6_DST_UNREACH; 526 code = ICMP6_DST_UNREACH_ADDR; 527 break; 528 } 529 icmp6_error(mcopy, type, code, 0); 530 return; 531 532 freecopy: 533 m_freem(mcopy); 534 return; 535 } 536
Indexes created Thu Sep 25 16:09:42 GMT 2025