ip6_forward.c revision 1.8
1 /* $NetBSD: ip6_forward.c,v 1.8 2000/02/06 12:49:45 itojun Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/malloc.h> 35 #include <sys/mbuf.h> 36 #include <sys/domain.h> 37 #include <sys/protosw.h> 38 #include <sys/socket.h> 39 #include <sys/errno.h> 40 #include <sys/time.h> 41 #include <sys/kernel.h> 42 #include <sys/syslog.h> 43 44 #include <net/if.h> 45 #include <net/route.h> 46 47 #include <netinet/in.h> 48 #include <netinet/in_var.h> 49 #include <netinet/ip_var.h> 50 #include <netinet/ip6.h> 51 #include <netinet6/ip6_var.h> 52 #include <netinet/icmp6.h> 53 #include <netinet6/nd6.h> 54 55 #ifdef IPSEC_IPV6FWD 56 #include <netinet6/ipsec.h> 57 #include <netkey/key.h> 58 #include <netkey/key_debug.h> 59 #endif /* IPSEC_IPV6FWD */ 60 61 #ifdef IPV6FIREWALL 62 #include <netinet6/ip6_fw.h> 63 #endif 64 65 #include <net/net_osdep.h> 66 67 struct route_in6 ip6_forward_rt; 68 69 /* 70 * Forward a packet. If some error occurs return the sender 71 * an icmp packet. Note we can't always generate a meaningful 72 * icmp message because icmp doesn't have a large enough repertoire 73 * of codes and types. 74 * 75 * If not forwarding, just drop the packet. This could be confusing 76 * if ipforwarding was zero but some routing protocol was advancing 77 * us as a gateway to somewhere. However, we must let the routing 78 * protocol deal with that. 79 * 80 */ 81 82 void 83 ip6_forward(m, srcrt) 84 struct mbuf *m; 85 int srcrt; 86 { 87 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 88 register struct sockaddr_in6 *dst; 89 register struct rtentry *rt; 90 int error, type = 0, code = 0; 91 struct mbuf *mcopy = NULL; 92 #ifdef IPSEC_IPV6FWD 93 struct secpolicy *sp = NULL; 94 #endif 95 long time_second = time.tv_sec; 96 97 #ifdef IPSEC_IPV6FWD 98 /* 99 * Check AH/ESP integrity. 100 */ 101 /* 102 * Don't increment ip6s_cantforward because this is the check 103 * before forwarding packet actually. 104 */ 105 if (ipsec6_in_reject(m, NULL)) { 106 ipsec6stat.in_polvio++; 107 m_freem(m); 108 return; 109 } 110 #endif /*IPSEC_IPV6FWD*/ 111 112 if (m->m_flags & (M_BCAST|M_MCAST) || 113 in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) { 114 ip6stat.ip6s_cantforward++; 115 ip6stat.ip6s_badscope++; 116 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 117 if (ip6_log_time + ip6_log_interval < time_second) { 118 char addr[INET6_ADDRSTRLEN]; 119 ip6_log_time = time_second; 120 strncpy(addr, ip6_sprintf(&ip6->ip6_src), sizeof(addr)); 121 log(LOG_DEBUG, 122 "cannot forward " 123 "from %s to %s nxt %d received on %s\n", 124 addr, 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 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 328 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 329 if (mcopy) { 330 u_long mtu; 331 #ifdef IPSEC_IPV6FWD 332 struct secpolicy *sp; 333 int ipsecerror; 334 size_t ipsechdrsiz; 335 #endif 336 337 mtu = rt->rt_ifp->if_mtu; 338 #ifdef IPSEC_IPV6FWD 339 /* 340 * When we do IPsec tunnel ingress, we need to play 341 * with if_mtu value (decrement IPsec header size 342 * from mtu value). The code is much simpler than v4 343 * case, as we have the outgoing interface for 344 * encapsulated packet as "rt->rt_ifp". 345 */ 346 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 347 IP_FORWARDING, &ipsecerror); 348 if (sp) { 349 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 350 IPSEC_DIR_OUTBOUND, NULL); 351 if (ipsechdrsiz < mtu) 352 mtu -= ipsechdrsiz; 353 } 354 355 /* 356 * if mtu becomes less than minimum MTU, 357 * tell minimum MTU (and I'll need to fragment it). 358 */ 359 if (mtu < IPV6_MMTU) 360 mtu = IPV6_MMTU; 361 #endif 362 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 363 } 364 m_freem(m); 365 return; 366 } 367 368 if (rt->rt_flags & RTF_GATEWAY) 369 dst = (struct sockaddr_in6 *)rt->rt_gateway; 370 371 /* 372 * If we are to forward the packet using the same interface 373 * as one we got the packet from, perhaps we should send a redirect 374 * to sender to shortcut a hop. 375 * Only send redirect if source is sending directly to us, 376 * and if packet was not source routed (or has any options). 377 * Also, don't send redirect if forwarding using a route 378 * modified by a redirect. 379 */ 380 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 381 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 382 type = ND_REDIRECT; 383 384 #ifdef IPV6FIREWALL 385 /* 386 * Check with the firewall... 387 */ 388 if (ip6_fw_chk_ptr) { 389 u_short port = 0; 390 /* If ipfw says divert, we have to just drop packet */ 391 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 392 m_freem(m); 393 goto freecopy; 394 } 395 if (!m) 396 goto freecopy; 397 } 398 #endif 399 400 #ifdef OLDIP6OUTPUT 401 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 402 (struct sockaddr *)dst, 403 ip6_forward_rt.ro_rt); 404 #else 405 error = nd6_output(rt->rt_ifp, m, dst, rt); 406 #endif 407 if (error) { 408 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 409 ip6stat.ip6s_cantforward++; 410 } else { 411 ip6stat.ip6s_forward++; 412 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 413 if (type) 414 ip6stat.ip6s_redirectsent++; 415 else { 416 if (mcopy) 417 goto freecopy; 418 } 419 } 420 if (mcopy == NULL) 421 return; 422 423 switch (error) { 424 case 0: 425 #if 1 426 if (type == ND_REDIRECT) { 427 icmp6_redirect_output(mcopy, rt); 428 return; 429 } 430 #endif 431 goto freecopy; 432 433 case EMSGSIZE: 434 /* xxx MTU is constant in PPP? */ 435 goto freecopy; 436 437 case ENOBUFS: 438 /* Tell source to slow down like source quench in IP? */ 439 goto freecopy; 440 441 case ENETUNREACH: /* shouldn't happen, checked above */ 442 case EHOSTUNREACH: 443 case ENETDOWN: 444 case EHOSTDOWN: 445 default: 446 type = ICMP6_DST_UNREACH; 447 code = ICMP6_DST_UNREACH_ADDR; 448 break; 449 } 450 icmp6_error(mcopy, type, code, 0); 451 return; 452 453 freecopy: 454 m_freem(mcopy); 455 return; 456 } 457
Indexes created Thu Sep 25 08:09:54 GMT 2025