ip6_forward.c revision 1.5
1 /* $NetBSD: ip6_forward.c,v 1.5 1999/12/13 15:17:22 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 #if (defined(__FreeBSD__) && __FreeBSD__ >= 3) 33 #include "opt_ip6fw.h" 34 #include "opt_inet.h" 35 #endif 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/malloc.h> 40 #include <sys/mbuf.h> 41 #include <sys/domain.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/errno.h> 45 #include <sys/time.h> 46 #include <sys/kernel.h> 47 #include <sys/syslog.h> 48 49 #include <net/if.h> 50 #include <net/route.h> 51 52 #include <netinet/in.h> 53 #include <netinet/in_var.h> 54 #include <netinet6/ip6.h> 55 #include <netinet6/ip6_var.h> 56 #include <netinet6/icmp6.h> 57 #include <netinet6/nd6.h> 58 59 #ifdef __OpenBSD__ /*KAME IPSEC*/ 60 #undef IPSEC 61 #endif 62 63 #ifdef IPSEC_IPV6FWD 64 #include <netinet6/ipsec.h> 65 #include <netkey/key.h> 66 #include <netkey/key_debug.h> 67 #endif /* IPSEC_IPV6FWD */ 68 69 #ifdef IPV6FIREWALL 70 #include <netinet6/ip6_fw.h> 71 #endif 72 73 #include <net/net_osdep.h> 74 75 struct route_in6 ip6_forward_rt; 76 77 /* 78 * Forward a packet. If some error occurs return the sender 79 * an icmp packet. Note we can't always generate a meaningful 80 * icmp message because icmp doesn't have a large enough repertoire 81 * of codes and types. 82 * 83 * If not forwarding, just drop the packet. This could be confusing 84 * if ipforwarding was zero but some routing protocol was advancing 85 * us as a gateway to somewhere. However, we must let the routing 86 * protocol deal with that. 87 * 88 */ 89 90 void 91 ip6_forward(m, srcrt) 92 struct mbuf *m; 93 int srcrt; 94 { 95 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 96 register struct sockaddr_in6 *dst; 97 register struct rtentry *rt; 98 int error, type = 0, code = 0; 99 struct mbuf *mcopy = NULL; 100 #ifdef IPSEC_IPV6FWD 101 struct secpolicy *sp = NULL; 102 #endif 103 #if !(defined(__FreeBSD__) && __FreeBSD__ >= 3) 104 long time_second = time.tv_sec; 105 #endif 106 107 #ifdef IPSEC_IPV6FWD 108 /* 109 * Check AH/ESP integrity. 110 */ 111 /* 112 * Don't increment ip6s_cantforward because this is the check 113 * before forwarding packet actually. 114 */ 115 if (ipsec6_in_reject(m, NULL)) { 116 ipsec6stat.in_polvio++; 117 m_freem(m); 118 return; 119 } 120 #endif /*IPSEC_IPV6FWD*/ 121 122 if (m->m_flags & (M_BCAST|M_MCAST) || 123 in6_canforward(&ip6->ip6_src, &ip6->ip6_dst) == 0) { 124 ip6stat.ip6s_cantforward++; 125 ip6stat.ip6s_badscope++; 126 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 127 if (ip6_log_time + ip6_log_interval < time_second) { 128 char addr[INET6_ADDRSTRLEN]; 129 ip6_log_time = time_second; 130 strncpy(addr, ip6_sprintf(&ip6->ip6_src), sizeof(addr)); 131 log(LOG_DEBUG, 132 "cannot forward " 133 "from %s to %s nxt %d received on %s\n", 134 addr, ip6_sprintf(&ip6->ip6_dst), 135 ip6->ip6_nxt, 136 if_name(m->m_pkthdr.rcvif)); 137 } 138 m_freem(m); 139 return; 140 } 141 142 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 143 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 144 icmp6_error(m, ICMP6_TIME_EXCEEDED, 145 ICMP6_TIME_EXCEED_TRANSIT, 0); 146 return; 147 } 148 ip6->ip6_hlim -= IPV6_HLIMDEC; 149 150 /* 151 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 152 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 153 * we need to generate an ICMP6 message to the src. 154 * Thanks to M_EXT, in most cases copy will not occur. 155 * 156 * It is important to save it before IPsec processing as IPsec 157 * processing may modify the mbuf. 158 */ 159 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 160 161 #ifdef IPSEC_IPV6FWD 162 /* get a security policy for this packet */ 163 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error); 164 if (sp == NULL) { 165 ipsec6stat.out_inval++; 166 ip6stat.ip6s_cantforward++; 167 if (mcopy) { 168 #if 0 169 /* XXX: what icmp ? */ 170 #else 171 m_freem(mcopy); 172 #endif 173 } 174 m_freem(m); 175 return; 176 } 177 178 error = 0; 179 180 /* check policy */ 181 switch (sp->policy) { 182 case IPSEC_POLICY_DISCARD: 183 /* 184 * This packet is just discarded. 185 */ 186 ipsec6stat.out_polvio++; 187 ip6stat.ip6s_cantforward++; 188 key_freesp(sp); 189 if (mcopy) { 190 #if 0 191 /* XXX: what icmp ? */ 192 #else 193 m_freem(mcopy); 194 #endif 195 } 196 m_freem(m); 197 return; 198 199 case IPSEC_POLICY_BYPASS: 200 case IPSEC_POLICY_NONE: 201 /* no need to do IPsec. */ 202 key_freesp(sp); 203 goto skip_ipsec; 204 205 case IPSEC_POLICY_IPSEC: 206 if (sp->req == NULL) { 207 /* XXX should be panic ? */ 208 printf("ip6_forward: No IPsec request specified.\n"); 209 ip6stat.ip6s_cantforward++; 210 key_freesp(sp); 211 if (mcopy) { 212 #if 0 213 /* XXX: what icmp ? */ 214 #else 215 m_freem(mcopy); 216 #endif 217 } 218 m_freem(m); 219 return; 220 } 221 /* do IPsec */ 222 break; 223 224 case IPSEC_POLICY_ENTRUST: 225 default: 226 /* should be panic ?? */ 227 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 228 key_freesp(sp); 229 goto skip_ipsec; 230 } 231 232 { 233 struct ipsec_output_state state; 234 235 /* 236 * All the extension headers will become inaccessible 237 * (since they can be encrypted). 238 * Don't panic, we need no more updates to extension headers 239 * on inner IPv6 packet (since they are now encapsulated). 240 * 241 * IPv6 [ESP|AH] IPv6 [extension headers] payload 242 */ 243 bzero(&state, sizeof(state)); 244 state.m = m; 245 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 246 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 247 248 error = ipsec6_output_tunnel(&state, sp, 0); 249 250 m = state.m; 251 #if 0 /* XXX allocate a route (ro, dst) again later */ 252 ro = (struct route_in6 *)state.ro; 253 dst = (struct sockaddr_in6 *)state.dst; 254 #endif 255 key_freesp(sp); 256 257 if (error) { 258 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 259 switch (error) { 260 case EHOSTUNREACH: 261 case ENETUNREACH: 262 case EMSGSIZE: 263 case ENOBUFS: 264 case ENOMEM: 265 break; 266 default: 267 printf("ip6_output (ipsec): error code %d\n", error); 268 /*fall through*/ 269 case ENOENT: 270 /* don't show these error codes to the user */ 271 break; 272 } 273 ip6stat.ip6s_cantforward++; 274 if (mcopy) { 275 #if 0 276 /* XXX: what icmp ? */ 277 #else 278 m_freem(mcopy); 279 #endif 280 } 281 m_freem(m); 282 return; 283 } 284 } 285 skip_ipsec: 286 #endif /* IPSEC_IPV6FWD */ 287 288 dst = &ip6_forward_rt.ro_dst; 289 if (!srcrt) { 290 /* 291 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 292 */ 293 if (ip6_forward_rt.ro_rt == 0 || 294 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 295 if (ip6_forward_rt.ro_rt) { 296 RTFREE(ip6_forward_rt.ro_rt); 297 ip6_forward_rt.ro_rt = 0; 298 } 299 /* this probably fails but give it a try again */ 300 #ifdef __FreeBSD__ 301 rtalloc_ign((struct route *)&ip6_forward_rt, 302 RTF_PRCLONING); 303 #else 304 rtalloc((struct route *)&ip6_forward_rt); 305 #endif 306 } 307 308 if (ip6_forward_rt.ro_rt == 0) { 309 ip6stat.ip6s_noroute++; 310 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 311 if (mcopy) { 312 icmp6_error(mcopy, ICMP6_DST_UNREACH, 313 ICMP6_DST_UNREACH_NOROUTE, 0); 314 } 315 m_freem(m); 316 return; 317 } 318 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 319 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 320 if (ip6_forward_rt.ro_rt) { 321 RTFREE(ip6_forward_rt.ro_rt); 322 ip6_forward_rt.ro_rt = 0; 323 } 324 bzero(dst, sizeof(*dst)); 325 dst->sin6_len = sizeof(struct sockaddr_in6); 326 dst->sin6_family = AF_INET6; 327 dst->sin6_addr = ip6->ip6_dst; 328 329 #ifdef __FreeBSD__ 330 rtalloc_ign((struct route *)&ip6_forward_rt, RTF_PRCLONING); 331 #else 332 rtalloc((struct route *)&ip6_forward_rt); 333 #endif 334 if (ip6_forward_rt.ro_rt == 0) { 335 ip6stat.ip6s_noroute++; 336 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 337 if (mcopy) { 338 icmp6_error(mcopy, ICMP6_DST_UNREACH, 339 ICMP6_DST_UNREACH_NOROUTE, 0); 340 } 341 m_freem(m); 342 return; 343 } 344 } 345 rt = ip6_forward_rt.ro_rt; 346 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 347 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 348 if (mcopy) { 349 u_long mtu; 350 351 mtu = rt->rt_ifp->if_mtu; 352 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 353 } 354 m_freem(m); 355 return; 356 } 357 358 if (rt->rt_flags & RTF_GATEWAY) 359 dst = (struct sockaddr_in6 *)rt->rt_gateway; 360 361 /* 362 * If we are to forward the packet using the same interface 363 * as one we got the packet from, perhaps we should send a redirect 364 * to sender to shortcut a hop. 365 * Only send redirect if source is sending directly to us, 366 * and if packet was not source routed (or has any options). 367 * Also, don't send redirect if forwarding using a route 368 * modified by a redirect. 369 */ 370 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 371 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 372 type = ND_REDIRECT; 373 374 #ifdef IPV6FIREWALL 375 /* 376 * Check with the firewall... 377 */ 378 if (ip6_fw_chk_ptr) { 379 u_short port = 0; 380 /* If ipfw says divert, we have to just drop packet */ 381 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 382 m_freem(m); 383 goto freecopy; 384 } 385 if (!m) 386 goto freecopy; 387 } 388 #endif 389 390 #ifdef OLDIP6OUTPUT 391 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 392 (struct sockaddr *)dst, 393 ip6_forward_rt.ro_rt); 394 #else 395 error = nd6_output(rt->rt_ifp, m, dst, rt); 396 #endif 397 if (error) { 398 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 399 ip6stat.ip6s_cantforward++; 400 } else { 401 ip6stat.ip6s_forward++; 402 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 403 if (type) 404 ip6stat.ip6s_redirectsent++; 405 else { 406 if (mcopy) 407 goto freecopy; 408 } 409 } 410 if (mcopy == NULL) 411 return; 412 413 switch (error) { 414 case 0: 415 #if 1 416 if (type == ND_REDIRECT) { 417 icmp6_redirect_output(mcopy, rt); 418 return; 419 } 420 #endif 421 goto freecopy; 422 423 case EMSGSIZE: 424 /* xxx MTU is constant in PPP? */ 425 goto freecopy; 426 427 case ENOBUFS: 428 /* Tell source to slow down like source quench in IP? */ 429 goto freecopy; 430 431 case ENETUNREACH: /* shouldn't happen, checked above */ 432 case EHOSTUNREACH: 433 case ENETDOWN: 434 case EHOSTDOWN: 435 default: 436 type = ICMP6_DST_UNREACH; 437 code = ICMP6_DST_UNREACH_ADDR; 438 break; 439 } 440 icmp6_error(mcopy, type, code, 0); 441 return; 442 443 freecopy: 444 m_freem(mcopy); 445 return; 446 } 447
Indexes created Thu Sep 25 08:09:54 GMT 2025