ip6_forward.c revision 1.15
1 /* $NetBSD: ip6_forward.c,v 1.15 2000/07/16 07:57:55 itojun Exp $ */ 2 /* $KAME: ip6_forward.c,v 1.43 2000/07/16 07:50:49 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 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 116 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 117 ip6stat.ip6s_cantforward++; 118 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 119 if (ip6_log_time + ip6_log_interval < time_second) { 120 ip6_log_time = time_second; 121 log(LOG_DEBUG, 122 "cannot forward " 123 "from %s to %s nxt %d received on %s\n", 124 ip6_sprintf(&ip6->ip6_src), 125 ip6_sprintf(&ip6->ip6_dst), 126 ip6->ip6_nxt, 127 if_name(m->m_pkthdr.rcvif)); 128 } 129 m_freem(m); 130 return; 131 } 132 133 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 134 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 135 icmp6_error(m, ICMP6_TIME_EXCEEDED, 136 ICMP6_TIME_EXCEED_TRANSIT, 0); 137 return; 138 } 139 ip6->ip6_hlim -= IPV6_HLIMDEC; 140 141 /* 142 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 143 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 144 * we need to generate an ICMP6 message to the src. 145 * Thanks to M_EXT, in most cases copy will not occur. 146 * 147 * It is important to save it before IPsec processing as IPsec 148 * processing may modify the mbuf. 149 */ 150 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 151 152 #ifdef IPSEC 153 /* get a security policy for this packet */ 154 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error); 155 if (sp == NULL) { 156 ipsec6stat.out_inval++; 157 ip6stat.ip6s_cantforward++; 158 if (mcopy) { 159 #if 0 160 /* XXX: what icmp ? */ 161 #else 162 m_freem(mcopy); 163 #endif 164 } 165 m_freem(m); 166 return; 167 } 168 169 error = 0; 170 171 /* check policy */ 172 switch (sp->policy) { 173 case IPSEC_POLICY_DISCARD: 174 /* 175 * This packet is just discarded. 176 */ 177 ipsec6stat.out_polvio++; 178 ip6stat.ip6s_cantforward++; 179 key_freesp(sp); 180 if (mcopy) { 181 #if 0 182 /* XXX: what icmp ? */ 183 #else 184 m_freem(mcopy); 185 #endif 186 } 187 m_freem(m); 188 return; 189 190 case IPSEC_POLICY_BYPASS: 191 case IPSEC_POLICY_NONE: 192 /* no need to do IPsec. */ 193 key_freesp(sp); 194 goto skip_ipsec; 195 196 case IPSEC_POLICY_IPSEC: 197 if (sp->req == NULL) { 198 /* XXX should be panic ? */ 199 printf("ip6_forward: No IPsec request specified.\n"); 200 ip6stat.ip6s_cantforward++; 201 key_freesp(sp); 202 if (mcopy) { 203 #if 0 204 /* XXX: what icmp ? */ 205 #else 206 m_freem(mcopy); 207 #endif 208 } 209 m_freem(m); 210 return; 211 } 212 /* do IPsec */ 213 break; 214 215 case IPSEC_POLICY_ENTRUST: 216 default: 217 /* should be panic ?? */ 218 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 219 key_freesp(sp); 220 goto skip_ipsec; 221 } 222 223 { 224 struct ipsec_output_state state; 225 226 /* 227 * All the extension headers will become inaccessible 228 * (since they can be encrypted). 229 * Don't panic, we need no more updates to extension headers 230 * on inner IPv6 packet (since they are now encapsulated). 231 * 232 * IPv6 [ESP|AH] IPv6 [extension headers] payload 233 */ 234 bzero(&state, sizeof(state)); 235 state.m = m; 236 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 237 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 238 239 error = ipsec6_output_tunnel(&state, sp, 0); 240 241 m = state.m; 242 #if 0 /* XXX allocate a route (ro, dst) again later */ 243 ro = (struct route_in6 *)state.ro; 244 dst = (struct sockaddr_in6 *)state.dst; 245 #endif 246 key_freesp(sp); 247 248 if (error) { 249 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 250 switch (error) { 251 case EHOSTUNREACH: 252 case ENETUNREACH: 253 case EMSGSIZE: 254 case ENOBUFS: 255 case ENOMEM: 256 break; 257 default: 258 printf("ip6_output (ipsec): error code %d\n", error); 259 /*fall through*/ 260 case ENOENT: 261 /* don't show these error codes to the user */ 262 break; 263 } 264 ip6stat.ip6s_cantforward++; 265 if (mcopy) { 266 #if 0 267 /* XXX: what icmp ? */ 268 #else 269 m_freem(mcopy); 270 #endif 271 } 272 m_freem(m); 273 return; 274 } 275 } 276 skip_ipsec: 277 #endif /* IPSEC */ 278 279 dst = &ip6_forward_rt.ro_dst; 280 if (!srcrt) { 281 /* 282 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 283 */ 284 if (ip6_forward_rt.ro_rt == 0 || 285 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 286 if (ip6_forward_rt.ro_rt) { 287 RTFREE(ip6_forward_rt.ro_rt); 288 ip6_forward_rt.ro_rt = 0; 289 } 290 /* this probably fails but give it a try again */ 291 rtalloc((struct route *)&ip6_forward_rt); 292 } 293 294 if (ip6_forward_rt.ro_rt == 0) { 295 ip6stat.ip6s_noroute++; 296 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 297 if (mcopy) { 298 icmp6_error(mcopy, ICMP6_DST_UNREACH, 299 ICMP6_DST_UNREACH_NOROUTE, 0); 300 } 301 m_freem(m); 302 return; 303 } 304 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 305 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 306 if (ip6_forward_rt.ro_rt) { 307 RTFREE(ip6_forward_rt.ro_rt); 308 ip6_forward_rt.ro_rt = 0; 309 } 310 bzero(dst, sizeof(*dst)); 311 dst->sin6_len = sizeof(struct sockaddr_in6); 312 dst->sin6_family = AF_INET6; 313 dst->sin6_addr = ip6->ip6_dst; 314 315 rtalloc((struct route *)&ip6_forward_rt); 316 if (ip6_forward_rt.ro_rt == 0) { 317 ip6stat.ip6s_noroute++; 318 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 319 if (mcopy) { 320 icmp6_error(mcopy, ICMP6_DST_UNREACH, 321 ICMP6_DST_UNREACH_NOROUTE, 0); 322 } 323 m_freem(m); 324 return; 325 } 326 } 327 rt = ip6_forward_rt.ro_rt; 328 329 /* 330 * Scope check: if a packet can't be delivered to its destination 331 * for the reason that the destination is beyond the scope of the 332 * source address, discard the packet and return an icmp6 destination 333 * unreachable error with Code 2 (beyond scope of source address). 334 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 335 */ 336 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 337 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 338 ip6stat.ip6s_cantforward++; 339 ip6stat.ip6s_badscope++; 340 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 341 342 if (ip6_log_time + ip6_log_interval < time_second) { 343 ip6_log_time = time_second; 344 log(LOG_DEBUG, 345 "cannot forward " 346 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 347 ip6_sprintf(&ip6->ip6_src), 348 ip6_sprintf(&ip6->ip6_dst), 349 ip6->ip6_nxt, 350 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 351 } 352 if (mcopy) 353 icmp6_error(mcopy, ICMP6_DST_UNREACH, 354 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 355 m_freem(m); 356 return; 357 } 358 359 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 360 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 361 if (mcopy) { 362 u_long mtu; 363 #ifdef IPSEC 364 struct secpolicy *sp; 365 int ipsecerror; 366 size_t ipsechdrsiz; 367 #endif 368 369 mtu = rt->rt_ifp->if_mtu; 370 #ifdef IPSEC 371 /* 372 * When we do IPsec tunnel ingress, we need to play 373 * with if_mtu value (decrement IPsec header size 374 * from mtu value). The code is much simpler than v4 375 * case, as we have the outgoing interface for 376 * encapsulated packet as "rt->rt_ifp". 377 */ 378 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 379 IP_FORWARDING, &ipsecerror); 380 if (sp) { 381 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 382 IPSEC_DIR_OUTBOUND, NULL); 383 if (ipsechdrsiz < mtu) 384 mtu -= ipsechdrsiz; 385 } 386 387 /* 388 * if mtu becomes less than minimum MTU, 389 * tell minimum MTU (and I'll need to fragment it). 390 */ 391 if (mtu < IPV6_MMTU) 392 mtu = IPV6_MMTU; 393 #endif 394 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 395 } 396 m_freem(m); 397 return; 398 } 399 400 if (rt->rt_flags & RTF_GATEWAY) 401 dst = (struct sockaddr_in6 *)rt->rt_gateway; 402 403 /* 404 * If we are to forward the packet using the same interface 405 * as one we got the packet from, perhaps we should send a redirect 406 * to sender to shortcut a hop. 407 * Only send redirect if source is sending directly to us, 408 * and if packet was not source routed (or has any options). 409 * Also, don't send redirect if forwarding using a route 410 * modified by a redirect. 411 */ 412 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 413 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 414 type = ND_REDIRECT; 415 416 #ifdef IPV6FIREWALL 417 /* 418 * Check with the firewall... 419 */ 420 if (ip6_fw_chk_ptr) { 421 u_short port = 0; 422 /* If ipfw says divert, we have to just drop packet */ 423 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 424 m_freem(m); 425 goto freecopy; 426 } 427 if (!m) 428 goto freecopy; 429 } 430 #endif 431 432 /* 433 * Fake scoped addresses. Note that even link-local source or 434 * destinaion can appear, if the originating node just sends the 435 * packet to us (without address resolution for the destination). 436 * Since both icmp6_error and icmp6_redirect_output fill the embedded 437 * link identifiers, we can do this stuff after make a copy for 438 * returning error. 439 */ 440 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 441 /* 442 * See corresponding comments in ip6_output. 443 * XXX: but is it possible that ip6_forward() sends a packet 444 * to a loopback interface? I don't think so, and thus 445 * I bark here. (jinmei (at) kame.net) 446 * XXX: it is common to route invalid packets to loopback. 447 * also, the codepath will be visited on use of ::1 in 448 * rthdr. (itojun) 449 */ 450 #if 1 451 if (0) 452 #else 453 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 454 #endif 455 { 456 printf("ip6_forward: outgoing interface is loopback. " 457 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 458 ip6_sprintf(&ip6->ip6_src), 459 ip6_sprintf(&ip6->ip6_dst), 460 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 461 if_name(rt->rt_ifp)); 462 } 463 464 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 465 origifp = ifindex2ifnet[ntohs(ip6->ip6_src.s6_addr16[1])]; 466 else if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 467 origifp = ifindex2ifnet[ntohs(ip6->ip6_dst.s6_addr16[1])]; 468 else 469 origifp = rt->rt_ifp; 470 } 471 else 472 origifp = rt->rt_ifp; 473 #ifndef FAKE_LOOPBACK_IF 474 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) == 0) 475 #else 476 if (1) 477 #endif 478 { 479 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 480 ip6->ip6_src.s6_addr16[1] = 0; 481 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 482 ip6->ip6_dst.s6_addr16[1] = 0; 483 } 484 485 #ifdef OLDIP6OUTPUT 486 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 487 (struct sockaddr *)dst, 488 ip6_forward_rt.ro_rt); 489 #else 490 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 491 #endif 492 if (error) { 493 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 494 ip6stat.ip6s_cantforward++; 495 } else { 496 ip6stat.ip6s_forward++; 497 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 498 if (type) 499 ip6stat.ip6s_redirectsent++; 500 else { 501 if (mcopy) 502 goto freecopy; 503 } 504 } 505 if (mcopy == NULL) 506 return; 507 508 switch (error) { 509 case 0: 510 #if 1 511 if (type == ND_REDIRECT) { 512 icmp6_redirect_output(mcopy, rt); 513 return; 514 } 515 #endif 516 goto freecopy; 517 518 case EMSGSIZE: 519 /* xxx MTU is constant in PPP? */ 520 goto freecopy; 521 522 case ENOBUFS: 523 /* Tell source to slow down like source quench in IP? */ 524 goto freecopy; 525 526 case ENETUNREACH: /* shouldn't happen, checked above */ 527 case EHOSTUNREACH: 528 case ENETDOWN: 529 case EHOSTDOWN: 530 default: 531 type = ICMP6_DST_UNREACH; 532 code = ICMP6_DST_UNREACH_ADDR; 533 break; 534 } 535 icmp6_error(mcopy, type, code, 0); 536 return; 537 538 freecopy: 539 m_freem(mcopy); 540 return; 541 } 542
Indexes created Thu Sep 25 16:09:42 GMT 2025