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: releng/5.2/sys/netinet6/ip6_forward.c 122921 2003-11-20 19:47:31Z andre $ */ 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 #include "opt_pfil_hooks.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/malloc.h> 42 #include <sys/mbuf.h> 43 #include <sys/domain.h> 44 #include <sys/protosw.h> 45 #include <sys/socket.h> 46 #include <sys/errno.h> 47 #include <sys/time.h> 48 #include <sys/kernel.h> 49 #include <sys/syslog.h> 50 51 #include <net/if.h> 52 #include <net/route.h> 53 #ifdef PFIL_HOOKS 54 #include <net/pfil.h> 55 #endif 56 57 #include <netinet/in.h> 58 #include <netinet/in_var.h> 59 #include <netinet/in_systm.h> 60 #include <netinet/ip.h> 61 #include <netinet/ip_var.h> 62 #include <netinet6/in6_var.h> 63 #include <netinet/ip6.h> 64 #include <netinet6/ip6_var.h> 65 #include <netinet/icmp6.h> 66 #include <netinet6/nd6.h> 67 68 #include <netinet/in_pcb.h> 69 70 #ifdef IPSEC 71 #include <netinet6/ipsec.h> 72 #ifdef INET6 73 #include <netinet6/ipsec6.h> 74 #endif 75 #include <netkey/key.h> 76 #endif /* IPSEC */ 77 78 #ifdef FAST_IPSEC 79 #include <netipsec/ipsec.h> 80 #include <netipsec/ipsec6.h> 81 #include <netipsec/key.h> 82 #define IPSEC 83 #endif /* FAST_IPSEC */ 84 85 #include <netinet6/ip6_fw.h> 86 87 #include <net/net_osdep.h> 88 89 #include <netinet6/ip6protosw.h> 90 91 struct route_in6 ip6_forward_rt; 92 93 /* 94 * Forward a packet. If some error occurs return the sender 95 * an icmp packet. Note we can't always generate a meaningful 96 * icmp message because icmp doesn't have a large enough repertoire 97 * of codes and types. 98 * 99 * If not forwarding, just drop the packet. This could be confusing 100 * if ipforwarding was zero but some routing protocol was advancing 101 * us as a gateway to somewhere. However, we must let the routing 102 * protocol deal with that. 103 * 104 */ 105 106 void 107 ip6_forward(m, srcrt) 108 struct mbuf *m; 109 int srcrt; 110 { 111 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 112 struct sockaddr_in6 *dst = NULL; 113 struct rtentry *rt = NULL; 114 int error, type = 0, code = 0; 115 struct mbuf *mcopy = NULL; 116 struct ifnet *origifp; /* maybe unnecessary */ 117 u_int32_t srczone, dstzone; 118 #ifdef IPSEC 119 struct secpolicy *sp = NULL; 120 int ipsecrt = 0; 121 #endif 122 123 #ifdef IPSEC 124 /* 125 * Check AH/ESP integrity. 126 */ 127 /* 128 * Don't increment ip6s_cantforward because this is the check 129 * before forwarding packet actually. 130 */ 131 if (ipsec6_in_reject(m, NULL)) { 132 #if !defined(FAST_IPSEC) 133 ipsec6stat.in_polvio++; 134 #endif 135 m_freem(m); 136 return; 137 } 138 #endif /* IPSEC */ 139 140 /* 141 * Do not forward packets to multicast destination (should be handled 142 * by ip6_mforward(). 143 * Do not forward packets with unspecified source. It was discussed 144 * in July 2000, on the ipngwg mailing list. 145 */ 146 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 147 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 148 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 149 ip6stat.ip6s_cantforward++; 150 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 151 if (ip6_log_time + ip6_log_interval < time_second) { 152 ip6_log_time = time_second; 153 log(LOG_DEBUG, 154 "cannot forward " 155 "from %s to %s nxt %d received on %s\n", 156 ip6_sprintf(&ip6->ip6_src), 157 ip6_sprintf(&ip6->ip6_dst), 158 ip6->ip6_nxt, 159 if_name(m->m_pkthdr.rcvif)); 160 } 161 m_freem(m); 162 return; 163 } 164 165 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 166 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 167 icmp6_error(m, ICMP6_TIME_EXCEEDED, 168 ICMP6_TIME_EXCEED_TRANSIT, 0); 169 return; 170 } 171 ip6->ip6_hlim -= IPV6_HLIMDEC; 172 173 /* 174 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 175 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 176 * we need to generate an ICMP6 message to the src. 177 * Thanks to M_EXT, in most cases copy will not occur. 178 * 179 * It is important to save it before IPsec processing as IPsec 180 * processing may modify the mbuf. 181 */ 182 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 183 184 #ifdef IPSEC 185 /* get a security policy for this packet */ 186 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 187 IP_FORWARDING, &error); 188 if (sp == NULL) { 189 ipsec6stat.out_inval++; 190 ip6stat.ip6s_cantforward++; 191 if (mcopy) { 192 #if 0 193 /* XXX: what icmp ? */ 194 #else 195 m_freem(mcopy); 196 #endif 197 } 198 m_freem(m); 199 return; 200 } 201 202 error = 0; 203 204 /* check policy */ 205 switch (sp->policy) { 206 case IPSEC_POLICY_DISCARD: 207 /* 208 * This packet is just discarded. 209 */ 210 ipsec6stat.out_polvio++; 211 ip6stat.ip6s_cantforward++; 212 key_freesp(sp); 213 if (mcopy) { 214 #if 0 215 /* XXX: what icmp ? */ 216 #else 217 m_freem(mcopy); 218 #endif 219 } 220 m_freem(m); 221 return; 222 223 case IPSEC_POLICY_BYPASS: 224 case IPSEC_POLICY_NONE: 225 /* no need to do IPsec. */ 226 key_freesp(sp); 227 goto skip_ipsec; 228 229 case IPSEC_POLICY_IPSEC: 230 if (sp->req == NULL) { 231 /* XXX should be panic ? */ 232 printf("ip6_forward: No IPsec request specified.\n"); 233 ip6stat.ip6s_cantforward++; 234 key_freesp(sp); 235 if (mcopy) { 236 #if 0 237 /* XXX: what icmp ? */ 238 #else 239 m_freem(mcopy); 240 #endif 241 } 242 m_freem(m); 243 return; 244 } 245 /* do IPsec */ 246 break; 247 248 case IPSEC_POLICY_ENTRUST: 249 default: 250 /* should be panic ?? */ 251 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 252 key_freesp(sp); 253 goto skip_ipsec; 254 } 255 256 { 257 struct ipsecrequest *isr = NULL; 258 struct ipsec_output_state state; 259 260 /* 261 * when the kernel forwards a packet, it is not proper to apply 262 * IPsec transport mode to the packet is not proper. this check 263 * avoid from this. 264 * at present, if there is even a transport mode SA request in the 265 * security policy, the kernel does not apply IPsec to the packet. 266 * this check is not enough because the following case is valid. 267 * ipsec esp/tunnel/xxx-xxx/require esp/transport//require; 268 */ 269 for (isr = sp->req; isr; isr = isr->next) { 270 if (isr->saidx.mode == IPSEC_MODE_TRANSPORT) 271 goto skip_ipsec; 272 } 273 274 /* 275 * All the extension headers will become inaccessible 276 * (since they can be encrypted). 277 * Don't panic, we need no more updates to extension headers 278 * on inner IPv6 packet (since they are now encapsulated). 279 * 280 * IPv6 [ESP|AH] IPv6 [extension headers] payload 281 */ 282 bzero(&state, sizeof(state)); 283 state.m = m; 284 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 285 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 286 287 error = ipsec6_output_tunnel(&state, sp, 0); 288 289 m = state.m; 290 key_freesp(sp); 291 292 if (error) { 293 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 294 switch (error) { 295 case EHOSTUNREACH: 296 case ENETUNREACH: 297 case EMSGSIZE: 298 case ENOBUFS: 299 case ENOMEM: 300 break; 301 default: 302 printf("ip6_output (ipsec): error code %d\n", error); 303 /* FALLTHROUGH */ 304 case ENOENT: 305 /* don't show these error codes to the user */ 306 break; 307 } 308 ip6stat.ip6s_cantforward++; 309 if (mcopy) { 310 #if 0 311 /* XXX: what icmp ? */ 312 #else 313 m_freem(mcopy); 314 #endif 315 } 316 m_freem(m); 317 return; 318 } 319 320 /* adjust pointer */ 321 ip6 = mtod(m, struct ip6_hdr *); 322 dst = (struct sockaddr_in6 *)state.dst; 323 rt = state.ro ? state.ro->ro_rt : NULL; 324 if (dst != NULL && rt != NULL) 325 ipsecrt = 1; 326 } 327 skip_ipsec: 328 #endif /* IPSEC */ 329 330 #ifdef IPSEC 331 if (ipsecrt) 332 goto skip_routing; 333 #endif 334 335 dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst; 336 if (!srcrt) { 337 /* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */ 338 if (ip6_forward_rt.ro_rt == 0 || 339 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 340 if (ip6_forward_rt.ro_rt) { 341 RTFREE(ip6_forward_rt.ro_rt); 342 ip6_forward_rt.ro_rt = 0; 343 } 344 345 /* this probably fails but give it a try again */ 346 rtalloc((struct route *)&ip6_forward_rt); 347 } 348 349 if (ip6_forward_rt.ro_rt == 0) { 350 ip6stat.ip6s_noroute++; 351 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); 352 if (mcopy) { 353 icmp6_error(mcopy, ICMP6_DST_UNREACH, 354 ICMP6_DST_UNREACH_NOROUTE, 0); 355 } 356 m_freem(m); 357 return; 358 } 359 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 360 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 361 if (ip6_forward_rt.ro_rt) { 362 RTFREE(ip6_forward_rt.ro_rt); 363 ip6_forward_rt.ro_rt = 0; 364 } 365 bzero(dst, sizeof(*dst)); 366 dst->sin6_len = sizeof(struct sockaddr_in6); 367 dst->sin6_family = AF_INET6; 368 dst->sin6_addr = ip6->ip6_dst; 369 370 rtalloc((struct route *)&ip6_forward_rt); 371 if (ip6_forward_rt.ro_rt == 0) { 372 ip6stat.ip6s_noroute++; 373 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute); 374 if (mcopy) { 375 icmp6_error(mcopy, ICMP6_DST_UNREACH, 376 ICMP6_DST_UNREACH_NOROUTE, 0); 377 } 378 m_freem(m); 379 return; 380 } 381 } 382 rt = ip6_forward_rt.ro_rt; 383 #ifdef IPSEC 384 skip_routing:; 385 #endif 386 387 /* 388 * Scope check: if a packet can't be delivered to its destination 389 * for the reason that the destination is beyond the scope of the 390 * source address, discard the packet and return an icmp6 destination 391 * unreachable error with Code 2 (beyond scope of source address). 392 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1] 393 */ 394 if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) || 395 in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone)) { 396 /* XXX: this should not happen */ 397 ip6stat.ip6s_cantforward++; 398 ip6stat.ip6s_badscope++; 399 m_freem(m); 400 return; 401 } 402 if (srczone != dstzone 403 #ifdef IPSEC 404 && !ipsecrt 405 #endif 406 ) { 407 ip6stat.ip6s_cantforward++; 408 ip6stat.ip6s_badscope++; 409 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 410 411 if (ip6_log_time + ip6_log_interval < time_second) { 412 ip6_log_time = time_second; 413 log(LOG_DEBUG, 414 "cannot forward " 415 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 416 ip6_sprintf(&ip6->ip6_src), 417 ip6_sprintf(&ip6->ip6_dst), 418 ip6->ip6_nxt, 419 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 420 } 421 if (mcopy) 422 icmp6_error(mcopy, ICMP6_DST_UNREACH, 423 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 424 m_freem(m); 425 return; 426 } 427 428 if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) { 429 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 430 if (mcopy) { 431 u_long mtu; 432 #ifdef IPSEC 433 struct secpolicy *sp; 434 int ipsecerror; 435 size_t ipsechdrsiz; 436 #endif 437 438 mtu = IN6_LINKMTU(rt->rt_ifp); 439 #ifdef IPSEC 440 /* 441 * When we do IPsec tunnel ingress, we need to play 442 * with the link value (decrement IPsec header size 443 * from mtu value). The code is much simpler than v4 444 * case, as we have the outgoing interface for 445 * encapsulated packet as "rt->rt_ifp". 446 */ 447 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 448 IP_FORWARDING, &ipsecerror); 449 if (sp) { 450 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 451 IPSEC_DIR_OUTBOUND, NULL); 452 if (ipsechdrsiz < mtu) 453 mtu -= ipsechdrsiz; 454 } 455 456 /* 457 * if mtu becomes less than minimum MTU, 458 * tell minimum MTU (and I'll need to fragment it). 459 */ 460 if (mtu < IPV6_MMTU) 461 mtu = IPV6_MMTU; 462 #endif 463 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 464 } 465 m_freem(m); 466 return; 467 } 468 469 if (rt->rt_flags & RTF_GATEWAY) 470 dst = (struct sockaddr_in6 *)rt->rt_gateway; 471 472 /* 473 * If we are to forward the packet using the same interface 474 * as one we got the packet from, perhaps we should send a redirect 475 * to sender to shortcut a hop. 476 * Only send redirect if source is sending directly to us, 477 * and if packet was not source routed (or has any options). 478 * Also, don't send redirect if forwarding using a route 479 * modified by a redirect. 480 */ 481 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 482 #ifdef IPSEC 483 !ipsecrt && 484 #endif 485 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) { 486 if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) { 487 /* 488 * If the incoming interface is equal to the outgoing 489 * one, and the link attached to the interface is 490 * point-to-point, then it will be highly probable 491 * that a routing loop occurs. Thus, we immediately 492 * drop the packet and send an ICMPv6 error message. 493 * 494 * type/code is based on suggestion by Rich Draves. 495 * not sure if it is the best pick. 496 */ 497 icmp6_error(mcopy, ICMP6_DST_UNREACH, 498 ICMP6_DST_UNREACH_ADDR, 0); 499 m_freem(m); 500 return; 501 } 502 type = ND_REDIRECT; 503 } 504 505 /* 506 * Check with the firewall... 507 */ 508 if (ip6_fw_enable && ip6_fw_chk_ptr) { 509 u_short port = 0; 510 /* If ipfw says divert, we have to just drop packet */ 511 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 512 m_freem(m); 513 goto freecopy; 514 } 515 if (!m) 516 goto freecopy; 517 } 518 519 /* 520 * Fake scoped addresses. Note that even link-local source or 521 * destinaion can appear, if the originating node just sends the 522 * packet to us (without address resolution for the destination). 523 * Since both icmp6_error and icmp6_redirect_output fill the embedded 524 * link identifiers, we can do this stuff after making a copy for 525 * returning an error. 526 */ 527 if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) { 528 /* 529 * See corresponding comments in ip6_output. 530 * XXX: but is it possible that ip6_forward() sends a packet 531 * to a loopback interface? I don't think so, and thus 532 * I bark here. (jinmei@kame.net) 533 * XXX: it is common to route invalid packets to loopback. 534 * also, the codepath will be visited on use of ::1 in 535 * rthdr. (itojun) 536 */ 537 #if 1 538 if (0) 539 #else 540 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0) 541 #endif 542 { 543 printf("ip6_forward: outgoing interface is loopback. " 544 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 545 ip6_sprintf(&ip6->ip6_src), 546 ip6_sprintf(&ip6->ip6_dst), 547 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif), 548 if_name(rt->rt_ifp)); 549 } 550 551 /* we can just use rcvif in forwarding. */ 552 origifp = m->m_pkthdr.rcvif; 553 } 554 else 555 origifp = rt->rt_ifp; 556 /* 557 * clear embedded scope identifiers if necessary. 558 * in6_clearscope will touch the addresses only when necessary. 559 */ 560 in6_clearscope(&ip6->ip6_src); 561 in6_clearscope(&ip6->ip6_dst); 562 563 #ifdef PFIL_HOOKS 564 /* 565 * Run through list of hooks for output packets. 566 */ 567 error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT); 568 if (error != 0) 569 goto senderr; 570 if (m == NULL) 571 goto freecopy; 572 ip6 = mtod(m, struct ip6_hdr *); 573 #endif /* PFIL_HOOKS */ 574 575 error = nd6_output(rt->rt_ifp, origifp, m, dst, rt); 576 if (error) { 577 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 578 ip6stat.ip6s_cantforward++; 579 } else { 580 ip6stat.ip6s_forward++; 581 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 582 if (type) 583 ip6stat.ip6s_redirectsent++; 584 else { 585 if (mcopy) 586 goto freecopy; 587 } 588 } 589 590 #ifdef PFIL_HOOKS 591 senderr: 592 #endif 593 if (mcopy == NULL) 594 return; 595 switch (error) { 596 case 0: 597 if (type == ND_REDIRECT) { 598 icmp6_redirect_output(mcopy, rt); 599 return; 600 } 601 goto freecopy; 602 603 case EMSGSIZE: 604 /* xxx MTU is constant in PPP? */ 605 goto freecopy; 606 607 case ENOBUFS: 608 /* Tell source to slow down like source quench in IP? */ 609 goto freecopy; 610 611 case ENETUNREACH: /* shouldn't happen, checked above */ 612 case EHOSTUNREACH: 613 case ENETDOWN: 614 case EHOSTDOWN: 615 default: 616 type = ICMP6_DST_UNREACH; 617 code = ICMP6_DST_UNREACH_ADDR; 618 break; 619 } 620 icmp6_error(mcopy, type, code, 0); 621 return; 622 623 freecopy: 624 m_freem(mcopy); 625 return; 626 }
Cache object: 39f41e3ea8cffbd9728df72796823535
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