Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_forward.c
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1 /* $FreeBSD$ */ 2 /* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 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_ip6fw.h" 34 #include "opt_inet.h" 35 #include "opt_inet6.h" 36 #include "opt_ipsec.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/malloc.h> 41 #include <sys/mbuf.h> 42 #include <sys/domain.h> 43 #include <sys/protosw.h> 44 #include <sys/socket.h> 45 #include <sys/errno.h> 46 #include <sys/time.h> 47 #include <sys/kernel.h> 48 #include <sys/syslog.h> 49 50 #include <net/if.h> 51 #include <net/route.h> 52 53 #include <netinet/in.h> 54 #include <netinet/in_var.h> 55 #include <netinet/in_systm.h> 56 #include <netinet/ip.h> 57 #include <netinet/ip_var.h> 58 #include <netinet6/in6_var.h> 59 #include <netinet/ip6.h> 60 #include <netinet6/ip6_var.h> 61 #include <netinet/icmp6.h> 62 #include <netinet6/nd6.h> 63 64 #include <netinet/in_pcb.h> 65 66 #ifdef IPSEC 67 #include <netinet6/ipsec.h> 68 #ifdef INET6 69 #include <netinet6/ipsec6.h> 70 #endif 71 #include <netkey/key.h> 72 #endif /* IPSEC */ 73 74 #ifdef FAST_IPSEC 75 #include <netipsec/ipsec.h> 76 #include <netipsec/ipsec6.h> 77 #include <netipsec/key.h> 78 #define IPSEC 79 #endif /* FAST_IPSEC */ 80 81 #include <netinet6/ip6_fw.h> 82 83 #include <net/net_osdep.h> 84 85 extern int (*fr_checkp) __P((struct ip *, int, struct ifnet *, int, struct mbuf **)); 86 87 struct route_in6 ip6_forward_rt; 88 89 /* 90 * Forward a packet. If some error occurs return the sender 91 * an icmp packet. Note we can't always generate a meaningful 92 * icmp message because icmp doesn't have a large enough repertoire 93 * of codes and types. 94 * 95 * If not forwarding, just drop the packet. This could be confusing 96 * if ipforwarding was zero but some routing protocol was advancing 97 * us as a gateway to somewhere. However, we must let the routing 98 * protocol deal with that. 99 * 100 */ 101 102 void 103 ip6_forward(m, srcrt) 104 struct mbuf *m; 105 int srcrt; 106 { 107 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 108 struct sockaddr_in6 *dst; 109 struct rtentry *rt; 110 int error, type = 0, code = 0; 111 struct mbuf *mcopy = NULL; 112 struct ifnet *origifp; /* maybe unnecessary */ 113 #ifdef IPSEC 114 struct secpolicy *sp = NULL; 115 #endif 116 117 #ifdef IPSEC 118 /* 119 * Check AH/ESP integrity. 120 */ 121 /* 122 * Don't increment ip6s_cantforward because this is the check 123 * before forwarding packet actually. 124 */ 125 if (ipsec6_in_reject(m, NULL)) { 126 #if !defined(FAST_IPSEC) 127 ipsec6stat.in_polvio++; 128 #endif 129 m_freem(m); 130 return; 131 } 132 #endif /* IPSEC */ 133 134 /* 135 * Do not forward packets to multicast destination (should be handled 136 * by ip6_mforward(). 137 * Do not forward packets with unspecified source. It was discussed 138 * in July 2000, on ipngwg mailing list. 139 */ 140 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 141 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 142 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 143 ip6stat.ip6s_cantforward++; 144 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 145 if (ip6_log_time + ip6_log_interval < time_second) { 146 ip6_log_time = time_second; 147 log(LOG_DEBUG, 148 "cannot forward " 149 "from %s to %s nxt %d received on %s\n", 150 ip6_sprintf(&ip6->ip6_src), 151 ip6_sprintf(&ip6->ip6_dst), 152 ip6->ip6_nxt, 153 if_name(m->m_pkthdr.rcvif)); 154 } 155 m_freem(m); 156 return; 157 } 158 159 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 160 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 161 icmp6_error(m, ICMP6_TIME_EXCEEDED, 162 ICMP6_TIME_EXCEED_TRANSIT, 0); 163 return; 164 } 165 ip6->ip6_hlim -= IPV6_HLIMDEC; 166 167 /* 168 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 169 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 170 * we need to generate an ICMP6 message to the src. 171 * Thanks to M_EXT, in most cases copy will not occur. 172 * 173 * It is important to save it before IPsec processing as IPsec 174 * processing may modify the mbuf. 175 */ 176 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 177 178 #ifdef IPSEC 179 /* get a security policy for this packet */ 180 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, IP_FORWARDING, 181 &error); 182 if (sp == NULL) { 183 ipsec6stat.out_inval++; 184 ip6stat.ip6s_cantforward++; 185 if (mcopy) { 186 #if 0 187 /* XXX: what icmp ? */ 188 #else 189 m_freem(mcopy); 190 #endif 191 } 192 m_freem(m); 193 return; 194 } 195 196 error = 0; 197 198 /* check policy */ 199 switch (sp->policy) { 200 case IPSEC_POLICY_DISCARD: 201 /* 202 * This packet is just discarded. 203 */ 204 ipsec6stat.out_polvio++; 205 ip6stat.ip6s_cantforward++; 206 key_freesp(sp); 207 if (mcopy) { 208 #if 0 209 /* XXX: what icmp ? */ 210 #else 211 m_freem(mcopy); 212 #endif 213 } 214 m_freem(m); 215 return; 216 217 case IPSEC_POLICY_BYPASS: 218 case IPSEC_POLICY_NONE: 219 /* no need to do IPsec. */ 220 key_freesp(sp); 221 goto skip_ipsec; 222 223 case IPSEC_POLICY_IPSEC: 224 if (sp->req == NULL) { 225 /* XXX should be panic ? */ 226 printf("ip6_forward: No IPsec request specified.\n"); 227 ip6stat.ip6s_cantforward++; 228 key_freesp(sp); 229 if (mcopy) { 230 #if 0 231 /* XXX: what icmp ? */ 232 #else 233 m_freem(mcopy); 234 #endif 235 } 236 m_freem(m); 237 return; 238 } 239 /* do IPsec */ 240 break; 241 242 case IPSEC_POLICY_ENTRUST: 243 default: 244 /* should be panic ?? */ 245 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 246 key_freesp(sp); 247 goto skip_ipsec; 248 } 249 250 { 251 struct ipsec_output_state state; 252 253 /* 254 * All the extension headers will become inaccessible 255 * (since they can be encrypted). 256 * Don't panic, we need no more updates to extension headers 257 * on inner IPv6 packet (since they are now encapsulated). 258 * 259 * IPv6 [ESP|AH] IPv6 [extension headers] payload 260 */ 261 bzero(&state, sizeof(state)); 262 state.m = m; 263 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 264 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 265 266 error = ipsec6_output_tunnel(&state, sp, 0); 267 268 m = state.m; 269 key_freesp(sp); 270 271 if (error) { 272 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 273 switch (error) { 274 case EHOSTUNREACH: 275 case ENETUNREACH: 276 case EMSGSIZE: 277 case ENOBUFS: 278 case ENOMEM: 279 break; 280 default: 281 printf("ip6_output (ipsec): error code %d\n", error); 282 /* fall through */ 283 case ENOENT: 284 /* don't show these error codes to the user */ 285 break; 286 } 287 ip6stat.ip6s_cantforward++; 288 if (mcopy) { 289 #if 0 290 /* XXX: what icmp ? */ 291 #else 292 m_freem(mcopy); 293 #endif 294 } 295 m_freem(m); 296 return; 297 } 298 } 299 skip_ipsec: 300 #endif /* IPSEC */ 301 302 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst; 303 if (!srcrt) { 304 /* 305 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 306 */ 307 if (ip6_forward_rt.ro_rt == 0 || 308 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 309 if (ip6_forward_rt.ro_rt) { 310 RTFREE(ip6_forward_rt.ro_rt); 311 ip6_forward_rt.ro_rt = 0; 312 } 313 /* this probably fails but give it a try again */ 314 rtalloc_ign((struct route *)&ip6_forward_rt, 315 RTF_PRCLONING); 316 } 317 318 if (ip6_forward_rt.ro_rt == 0) { 319 ip6stat.ip6s_noroute++; 320 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); 321 if (mcopy) { 322 icmp6_error(mcopy, ICMP6_DST_UNREACH, 323 ICMP6_DST_UNREACH_NOROUTE, 0); 324 } 325 m_freem(m); 326 return; 327 } 328 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 329 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 330 if (ip6_forward_rt.ro_rt) { 331 RTFREE(ip6_forward_rt.ro_rt); 332 ip6_forward_rt.ro_rt = 0; 333 } 334 bzero(dst, sizeof(*dst)); 335 dst->sin6_len = sizeof(struct sockaddr_in6); 336 dst->sin6_family = AF_INET6; 337 dst->sin6_addr = ip6->ip6_dst; 338 339 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); 340 if (ip6_forward_rt.ro_rt == 0) { 341 ip6stat.ip6s_noroute++; 342 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); 343 if (mcopy) { 344 icmp6_error(mcopy, ICMP6_DST_UNREACH, 345 ICMP6_DST_UNREACH_NOROUTE, 0); 346 } 347 m_freem(m); 348 return; 349 } 350 } 351 rt = ip6_forward_rt.ro_rt; 352 353 /* 354 * Scope check: if a packet can't be delivered to its destination 355 * for the reason that the destination is beyond the scope of the 356 * source address, discard the packet and return an icmp6 destination 357 * unreachable error with Code 2 (beyond scope of source address). 358 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1] 359 */ 360 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 361 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 362 ip6stat.ip6s_cantforward++; 363 ip6stat.ip6s_badscope++; 364 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 365 366 if (ip6_log_time + ip6_log_interval < time_second) { 367 ip6_log_time = time_second; 368 log(LOG_DEBUG, 369 "cannot forward " 370 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 371 ip6_sprintf(&ip6->ip6_src), 372 ip6_sprintf(&ip6->ip6_dst), 373 ip6->ip6_nxt, 374 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 375 } 376 if (mcopy) 377 icmp6_error(mcopy, ICMP6_DST_UNREACH, 378 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 379 m_freem(m); 380 return; 381 } 382 383 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 384 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 385 if (mcopy) { 386 u_long mtu; 387 #ifdef IPSEC 388 struct secpolicy *sp; 389 int ipsecerror; 390 size_t ipsechdrsiz; 391 #endif 392 393 mtu = rt->rt_ifp->if_mtu; 394 #ifdef IPSEC 395 /* 396 * When we do IPsec tunnel ingress, we need to play 397 * with if_mtu value (decrement IPsec header size 398 * from mtu value). The code is much simpler than v4 399 * case, as we have the outgoing interface for 400 * encapsulated packet as "rt->rt_ifp". 401 */ 402 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 403 IP_FORWARDING, &ipsecerror); 404 if (sp) { 405 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 406 IPSEC_DIR_OUTBOUND, NULL); 407 if (ipsechdrsiz < mtu) 408 mtu -= ipsechdrsiz; 409 } 410 411 /* 412 * if mtu becomes less than minimum MTU, 413 * tell minimum MTU (and I'll need to fragment it). 414 */ 415 if (mtu < IPV6_MMTU) 416 mtu = IPV6_MMTU; 417 #endif 418 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 419 } 420 m_freem(m); 421 return; 422 } 423 424 if (rt->rt_flags & RTF_GATEWAY) 425 dst = (struct sockaddr_in6 *)rt->rt_gateway; 426 427 /* 428 * If we are to forward the packet using the same interface 429 * as one we got the packet from, perhaps we should send a redirect 430 * to sender to shortcut a hop. 431 * Only send redirect if source is sending directly to us, 432 * and if packet was not source routed (or has any options). 433 * Also, don't send redirect if forwarding using a route 434 * modified by a redirect. 435 */ 436 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 437 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { 438 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { 439 /* 440 * If the incoming interface is equal to the outgoing 441 * one, and the link attached to the interface is 442 * point-to-point, then it will be highly probable 443 * that a routing loop occurs. Thus, we immediately 444 * drop the packet and send an ICMPv6 error message. 445 * 446 * type/code is based on suggestion by Rich Draves. 447 * not sure if it is the best pick. 448 */ 449 icmp6_error(mcopy, ICMP6_DST_UNREACH, 450 ICMP6_DST_UNREACH_ADDR, 0); 451 m_freem(m); 452 return; 453 } 454 type = ND_REDIRECT; 455 } 456 457 /* 458 * Check with the firewall... 459 */ 460 if (ip6_fw_enable && ip6_fw_chk_ptr) { 461 u_short port = 0; 462 /* If ipfw says divert, we have to just drop packet */ 463 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 464 m_freem(m); 465 goto freecopy; 466 } 467 if (!m) 468 goto freecopy; 469 } 470 471 /* 472 * Fake scoped addresses. Note that even link-local source or 473 * destinaion can appear, if the originating node just sends the 474 * packet to us (without address resolution for the destination). 475 * Since both icmp6_error and icmp6_redirect_output fill the embedded 476 * link identifiers, we can do this stuff after making a copy for 477 * returning an error. 478 */ 479 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 480 /* 481 * See corresponding comments in ip6_output. 482 * XXX: but is it possible that ip6_forward() sends a packet 483 * to a loopback interface? I don't think so, and thus 484 * I bark here. (jinmei@kame.net) 485 * XXX: it is common to route invalid packets to loopback. 486 * also, the codepath will be visited on use of ::1 in 487 * rthdr. (itojun) 488 */ 489 #if 1 490 if (0) 491 #else 492 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 493 #endif 494 { 495 printf("ip6_forward: outgoing interface is loopback. " 496 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 497 ip6_sprintf(&ip6->ip6_src), 498 ip6_sprintf(&ip6->ip6_dst), 499 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 500 if_name(rt->rt_ifp)); 501 } 502 503 /* we can just use rcvif in forwarding. */ 504 origifp = m->m_pkthdr.rcvif; 505 } 506 else 507 origifp = rt->rt_ifp; 508 #ifndef SCOPEDROUTING 509 /* 510 * clear embedded scope identifiers if necessary. 511 * in6_clearscope will touch the addresses only when necessary. 512 */ 513 in6_clearscope(&ip6->ip6_src); 514 in6_clearscope(&ip6->ip6_dst); 515 #endif 516 517 /* 518 * Check if we want to allow this packet to be processed. 519 * Consider it to be bad if not. 520 */ 521 if (fr_checkp) { 522 struct mbuf *m1 = m; 523 524 if ((*fr_checkp)((struct ip *)ip6, sizeof(*ip6), 525 rt->rt_ifp, 1, &m1) != 0) 526 goto freecopy; 527 m = m1; 528 if (m == NULL) 529 goto freecopy; 530 ip6 = mtod(m, struct ip6_hdr *); 531 } 532 533 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 534 if (error) { 535 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 536 ip6stat.ip6s_cantforward++; 537 } else { 538 ip6stat.ip6s_forward++; 539 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 540 if (type) 541 ip6stat.ip6s_redirectsent++; 542 else { 543 if (mcopy) 544 goto freecopy; 545 } 546 } 547 if (mcopy == NULL) 548 return; 549 switch (error) { 550 case 0: 551 #if 1 552 if (type == ND_REDIRECT) { 553 icmp6_redirect_output(mcopy, rt); 554 return; 555 } 556 #endif 557 goto freecopy; 558 559 case EMSGSIZE: 560 /* xxx MTU is constant in PPP? */ 561 goto freecopy; 562 563 case ENOBUFS: 564 /* Tell source to slow down like source quench in IP? */ 565 goto freecopy; 566 567 case ENETUNREACH: /* shouldn't happen, checked above */ 568 case EHOSTUNREACH: 569 case ENETDOWN: 570 case EHOSTDOWN: 571 default: 572 type = ICMP6_DST_UNREACH; 573 code = ICMP6_DST_UNREACH_ADDR; 574 break; 575 } 576 icmp6_error(mcopy, type, code, 0); 577 return; 578 579 freecopy: 580 m_freem(mcopy); 581 return; 582 }
Cache object: 0b169af0bd05b383916966d7451c2a7b
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