ip6_forward.c revision 1.16
1 /* $NetBSD: ip6_forward.c,v 1.16 2000/07/27 15:53:51 itojun Exp $ */ 2 /* $KAME: ip6_forward.c,v 1.44 2000/07/27 13:43:21 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, 0, &error); 162 if (sp == NULL) { 163 ipsec6stat.out_inval++; 164 ip6stat.ip6s_cantforward++; 165 if (mcopy) { 166 #if 0 167 /* XXX: what icmp ? */ 168 #else 169 m_freem(mcopy); 170 #endif 171 } 172 m_freem(m); 173 return; 174 } 175 176 error = 0; 177 178 /* check policy */ 179 switch (sp->policy) { 180 case IPSEC_POLICY_DISCARD: 181 /* 182 * This packet is just discarded. 183 */ 184 ipsec6stat.out_polvio++; 185 ip6stat.ip6s_cantforward++; 186 key_freesp(sp); 187 if (mcopy) { 188 #if 0 189 /* XXX: what icmp ? */ 190 #else 191 m_freem(mcopy); 192 #endif 193 } 194 m_freem(m); 195 return; 196 197 case IPSEC_POLICY_BYPASS: 198 case IPSEC_POLICY_NONE: 199 /* no need to do IPsec. */ 200 key_freesp(sp); 201 goto skip_ipsec; 202 203 case IPSEC_POLICY_IPSEC: 204 if (sp->req == NULL) { 205 /* XXX should be panic ? */ 206 printf("ip6_forward: No IPsec request specified.\n"); 207 ip6stat.ip6s_cantforward++; 208 key_freesp(sp); 209 if (mcopy) { 210 #if 0 211 /* XXX: what icmp ? */ 212 #else 213 m_freem(mcopy); 214 #endif 215 } 216 m_freem(m); 217 return; 218 } 219 /* do IPsec */ 220 break; 221 222 case IPSEC_POLICY_ENTRUST: 223 default: 224 /* should be panic ?? */ 225 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 226 key_freesp(sp); 227 goto skip_ipsec; 228 } 229 230 { 231 struct ipsec_output_state state; 232 233 /* 234 * All the extension headers will become inaccessible 235 * (since they can be encrypted). 236 * Don't panic, we need no more updates to extension headers 237 * on inner IPv6 packet (since they are now encapsulated). 238 * 239 * IPv6 [ESP|AH] IPv6 [extension headers] payload 240 */ 241 bzero(&state, sizeof(state)); 242 state.m = m; 243 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 244 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 245 246 error = ipsec6_output_tunnel(&state, sp, 0); 247 248 m = state.m; 249 #if 0 /* XXX allocate a route (ro, dst) again later */ 250 ro = (struct route_in6 *)state.ro; 251 dst = (struct sockaddr_in6 *)state.dst; 252 #endif 253 key_freesp(sp); 254 255 if (error) { 256 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 257 switch (error) { 258 case EHOSTUNREACH: 259 case ENETUNREACH: 260 case EMSGSIZE: 261 case ENOBUFS: 262 case ENOMEM: 263 break; 264 default: 265 printf("ip6_output (ipsec): error code %d\n", error); 266 /*fall through*/ 267 case ENOENT: 268 /* don't show these error codes to the user */ 269 break; 270 } 271 ip6stat.ip6s_cantforward++; 272 if (mcopy) { 273 #if 0 274 /* XXX: what icmp ? */ 275 #else 276 m_freem(mcopy); 277 #endif 278 } 279 m_freem(m); 280 return; 281 } 282 } 283 skip_ipsec: 284 #endif /* IPSEC */ 285 286 dst = &ip6_forward_rt.ro_dst; 287 if (!srcrt) { 288 /* 289 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 290 */ 291 if (ip6_forward_rt.ro_rt == 0 || 292 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 293 if (ip6_forward_rt.ro_rt) { 294 RTFREE(ip6_forward_rt.ro_rt); 295 ip6_forward_rt.ro_rt = 0; 296 } 297 /* this probably fails but give it a try again */ 298 rtalloc((struct route *)&ip6_forward_rt); 299 } 300 301 if (ip6_forward_rt.ro_rt == 0) { 302 ip6stat.ip6s_noroute++; 303 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 304 if (mcopy) { 305 icmp6_error(mcopy, ICMP6_DST_UNREACH, 306 ICMP6_DST_UNREACH_NOROUTE, 0); 307 } 308 m_freem(m); 309 return; 310 } 311 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 312 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 313 if (ip6_forward_rt.ro_rt) { 314 RTFREE(ip6_forward_rt.ro_rt); 315 ip6_forward_rt.ro_rt = 0; 316 } 317 bzero(dst, sizeof(*dst)); 318 dst->sin6_len = sizeof(struct sockaddr_in6); 319 dst->sin6_family = AF_INET6; 320 dst->sin6_addr = ip6->ip6_dst; 321 322 rtalloc((struct route *)&ip6_forward_rt); 323 if (ip6_forward_rt.ro_rt == 0) { 324 ip6stat.ip6s_noroute++; 325 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 326 if (mcopy) { 327 icmp6_error(mcopy, ICMP6_DST_UNREACH, 328 ICMP6_DST_UNREACH_NOROUTE, 0); 329 } 330 m_freem(m); 331 return; 332 } 333 } 334 rt = ip6_forward_rt.ro_rt; 335 336 /* 337 * Scope check: if a packet can't be delivered to its destination 338 * for the reason that the destination is beyond the scope of the 339 * source address, discard the packet and return an icmp6 destination 340 * unreachable error with Code 2 (beyond scope of source address). 341 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 342 */ 343 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 344 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 345 ip6stat.ip6s_cantforward++; 346 ip6stat.ip6s_badscope++; 347 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 348 349 if (ip6_log_time + ip6_log_interval < time_second) { 350 ip6_log_time = time_second; 351 log(LOG_DEBUG, 352 "cannot forward " 353 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 354 ip6_sprintf(&ip6->ip6_src), 355 ip6_sprintf(&ip6->ip6_dst), 356 ip6->ip6_nxt, 357 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 358 } 359 if (mcopy) 360 icmp6_error(mcopy, ICMP6_DST_UNREACH, 361 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 362 m_freem(m); 363 return; 364 } 365 366 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 367 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 368 if (mcopy) { 369 u_long mtu; 370 #ifdef IPSEC 371 struct secpolicy *sp; 372 int ipsecerror; 373 size_t ipsechdrsiz; 374 #endif 375 376 mtu = rt->rt_ifp->if_mtu; 377 #ifdef IPSEC 378 /* 379 * When we do IPsec tunnel ingress, we need to play 380 * with if_mtu value (decrement IPsec header size 381 * from mtu value). The code is much simpler than v4 382 * case, as we have the outgoing interface for 383 * encapsulated packet as "rt->rt_ifp". 384 */ 385 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 386 IP_FORWARDING, &ipsecerror); 387 if (sp) { 388 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 389 IPSEC_DIR_OUTBOUND, NULL); 390 if (ipsechdrsiz < mtu) 391 mtu -= ipsechdrsiz; 392 } 393 394 /* 395 * if mtu becomes less than minimum MTU, 396 * tell minimum MTU (and I'll need to fragment it). 397 */ 398 if (mtu < IPV6_MMTU) 399 mtu = IPV6_MMTU; 400 #endif 401 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 402 } 403 m_freem(m); 404 return; 405 } 406 407 if (rt->rt_flags & RTF_GATEWAY) 408 dst = (struct sockaddr_in6 *)rt->rt_gateway; 409 410 /* 411 * If we are to forward the packet using the same interface 412 * as one we got the packet from, perhaps we should send a redirect 413 * to sender to shortcut a hop. 414 * Only send redirect if source is sending directly to us, 415 * and if packet was not source routed (or has any options). 416 * Also, don't send redirect if forwarding using a route 417 * modified by a redirect. 418 */ 419 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 420 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 421 type = ND_REDIRECT; 422 423 #ifdef IPV6FIREWALL 424 /* 425 * Check with the firewall... 426 */ 427 if (ip6_fw_chk_ptr) { 428 u_short port = 0; 429 /* If ipfw says divert, we have to just drop packet */ 430 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 431 m_freem(m); 432 goto freecopy; 433 } 434 if (!m) 435 goto freecopy; 436 } 437 #endif 438 439 /* 440 * Fake scoped addresses. Note that even link-local source or 441 * destinaion can appear, if the originating node just sends the 442 * packet to us (without address resolution for the destination). 443 * Since both icmp6_error and icmp6_redirect_output fill the embedded 444 * link identifiers, we can do this stuff after make a copy for 445 * returning error. 446 */ 447 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 448 /* 449 * See corresponding comments in ip6_output. 450 * XXX: but is it possible that ip6_forward() sends a packet 451 * to a loopback interface? I don't think so, and thus 452 * I bark here. (jinmei (at) kame.net) 453 * XXX: it is common to route invalid packets to loopback. 454 * also, the codepath will be visited on use of ::1 in 455 * rthdr. (itojun) 456 */ 457 #if 1 458 if (0) 459 #else 460 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 461 #endif 462 { 463 printf("ip6_forward: outgoing interface is loopback. " 464 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 465 ip6_sprintf(&ip6->ip6_src), 466 ip6_sprintf(&ip6->ip6_dst), 467 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 468 if_name(rt->rt_ifp)); 469 } 470 471 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 472 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 473 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 474 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 475 else 476 origifp = rt->rt_ifp; 477 } 478 else 479 origifp = rt->rt_ifp; 480 #ifndef FAKE_LOOPBACK_IF 481 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 482 #else 483 if (1) 484 #endif 485 { 486 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 487 ip6->ip6_src.s6_addr16[1] = 0; 488 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 489 ip6->ip6_dst.s6_addr16[1] = 0; 490 } 491 492 #ifdef OLDIP6OUTPUT 493 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 494 (struct sockaddr *)dst, 495 ip6_forward_rt.ro_rt); 496 #else 497 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 498 #endif 499 if (error) { 500 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 501 ip6stat.ip6s_cantforward++; 502 } else { 503 ip6stat.ip6s_forward++; 504 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 505 if (type) 506 ip6stat.ip6s_redirectsent++; 507 else { 508 if (mcopy) 509 goto freecopy; 510 } 511 } 512 if (mcopy == NULL) 513 return; 514 515 switch (error) { 516 case 0: 517 #if 1 518 if (type == ND_REDIRECT) { 519 icmp6_redirect_output(mcopy, rt); 520 return; 521 } 522 #endif 523 goto freecopy; 524 525 case EMSGSIZE: 526 /* xxx MTU is constant in PPP? */ 527 goto freecopy; 528 529 case ENOBUFS: 530 /* Tell source to slow down like source quench in IP? */ 531 goto freecopy; 532 533 case ENETUNREACH: /* shouldn't happen, checked above */ 534 case EHOSTUNREACH: 535 case ENETDOWN: 536 case EHOSTDOWN: 537 default: 538 type = ICMP6_DST_UNREACH; 539 code = ICMP6_DST_UNREACH_ADDR; 540 break; 541 } 542 icmp6_error(mcopy, type, code, 0); 543 return; 544 545 freecopy: 546 m_freem(mcopy); 547 return; 548 } 549
Indexes created Thu Sep 25 16:09:42 GMT 2025