in6_src.c revision 1.92
1/* $OpenBSD: in6_src.c,v 1.92 2024/02/07 23:40:40 bluhm Exp $ */ 2/* $KAME: in6_src.c,v 1.36 2001/02/06 04:08:17 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/* 34 * Copyright (c) 1982, 1986, 1991, 1993 35 * The Regents of the University of California. All rights reserved. 36 * 37 * Redistribution and use in source and binary forms, with or without 38 * modification, are permitted provided that the following conditions 39 * are met: 40 * 1. Redistributions of source code must retain the above copyright 41 * notice, this list of conditions and the following disclaimer. 42 * 2. Redistributions in binary form must reproduce the above copyright 43 * notice, this list of conditions and the following disclaimer in the 44 * documentation and/or other materials provided with the distribution. 45 * 3. Neither the name of the University nor the names of its contributors 46 * may be used to endorse or promote products derived from this software 47 * without specific prior written permission. 48 * 49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 59 * SUCH DAMAGE. 60 * 61 * @(#)in_pcb.c 8.2 (Berkeley) 1/4/94 62 */ 63 64#include <sys/param.h> 65#include <sys/systm.h> 66#include <sys/mbuf.h> 67#include <sys/socket.h> 68#include <sys/socketvar.h> 69#include <sys/ioctl.h> 70#include <sys/errno.h> 71#include <sys/time.h> 72 73#include <net/if.h> 74#include <net/if_var.h> 75#include <net/route.h> 76 77#include <netinet/in.h> 78#include <netinet/ip.h> 79#include <netinet/in_pcb.h> 80#include <netinet6/in6_var.h> 81#include <netinet/ip6.h> 82#include <netinet6/ip6_var.h> 83#include <netinet6/nd6.h> 84 85int in6_selectif(const struct in6_addr *, struct ip6_pktopts *, 86 struct ip6_moptions *, struct route_in6 *, struct ifnet **, u_int); 87 88/* 89 * Return an IPv6 address, which is the most appropriate for a given 90 * destination and pcb. We need the additional opt parameter because 91 * the values set at pcb level can be overridden via cmsg. 92 */ 93int 94in6_pcbselsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 95 struct inpcb *inp, struct ip6_pktopts *opts) 96{ 97 struct ip6_moptions *mopts = inp->inp_moptions6; 98 struct route_in6 *ro = &inp->inp_route6; 99 const struct in6_addr *laddr = &inp->inp_laddr6; 100 u_int rtableid = inp->inp_rtableid; 101 struct ifnet *ifp = NULL; 102 struct sockaddr *ip6_source = NULL; 103 struct in6_addr *dst; 104 struct in6_ifaddr *ia6 = NULL; 105 struct in6_pktinfo *pi = NULL; 106 int error; 107 108 dst = &dstsock->sin6_addr; 109 110 /* 111 * If the source address is explicitly specified by the caller, 112 * check if the requested source address is indeed a unicast address 113 * assigned to the node, and can be used as the packet's source 114 * address. If everything is okay, use the address as source. 115 */ 116 if (opts && (pi = opts->ip6po_pktinfo) && 117 !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) { 118 struct sockaddr_in6 sa6; 119 120 /* get the outgoing interface */ 121 error = in6_selectif(dst, opts, mopts, ro, &ifp, rtableid); 122 if (error) 123 return (error); 124 125 bzero(&sa6, sizeof(sa6)); 126 sa6.sin6_family = AF_INET6; 127 sa6.sin6_len = sizeof(sa6); 128 sa6.sin6_addr = pi->ipi6_addr; 129 130 if (ifp && IN6_IS_SCOPE_EMBED(&sa6.sin6_addr)) 131 sa6.sin6_addr.s6_addr16[1] = htons(ifp->if_index); 132 if_put(ifp); /* put reference from in6_selectif */ 133 134 ia6 = ifatoia6(ifa_ifwithaddr(sin6tosa(&sa6), rtableid)); 135 if (ia6 == NULL || (ia6->ia6_flags & 136 (IN6_IFF_ANYCAST|IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED))) 137 return (EADDRNOTAVAIL); 138 139 pi->ipi6_addr = sa6.sin6_addr; /* XXX: this overrides pi */ 140 141 *in6src = &pi->ipi6_addr; 142 return (0); 143 } 144 145 /* 146 * If the source address is not specified but the socket(if any) 147 * is already bound, use the bound address. 148 */ 149 if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr)) { 150 *in6src = laddr; 151 return (0); 152 } 153 154 /* 155 * If the caller doesn't specify the source address but 156 * the outgoing interface, use an address associated with 157 * the interface. 158 */ 159 if (pi && pi->ipi6_ifindex) { 160 ifp = if_get(pi->ipi6_ifindex); 161 if (ifp == NULL) 162 return (ENXIO); /* XXX: better error? */ 163 164 ia6 = in6_ifawithscope(ifp, dst, rtableid); 165 if_put(ifp); 166 167 if (ia6 == NULL) 168 return (EADDRNOTAVAIL); 169 170 *in6src = &ia6->ia_addr.sin6_addr; 171 return (0); 172 } 173 174 error = in6_selectsrc(in6src, dstsock, mopts, rtableid); 175 if (error != EADDRNOTAVAIL) 176 return (error); 177 178 /* 179 * If route is known or can be allocated now, 180 * our src addr is taken from the i/f, else punt. 181 */ 182 route6_cache(ro, dst, rtableid); 183 if (ro->ro_rt == NULL) { 184 ro->ro_rt = rtalloc(sin6tosa(&ro->ro_dst), 185 RT_RESOLVE, ro->ro_tableid); 186 } 187 188 /* 189 * in_pcbconnect() checks out IFF_LOOPBACK to skip using 190 * the address. But we don't know why it does so. 191 * It is necessary to ensure the scope even for lo0 192 * so doesn't check out IFF_LOOPBACK. 193 */ 194 195 if (ro->ro_rt) { 196 ifp = if_get(ro->ro_rt->rt_ifidx); 197 if (ifp != NULL) { 198 ia6 = in6_ifawithscope(ifp, dst, rtableid); 199 if_put(ifp); 200 } 201 if (ia6 == NULL) /* xxx scope error ?*/ 202 ia6 = ifatoia6(ro->ro_rt->rt_ifa); 203 } 204 205 /* 206 * Use preferred source address if : 207 * - destination is not onlink 208 * - preferred source address is set 209 * - output interface is UP 210 */ 211 if (ro->ro_rt && !(ro->ro_rt->rt_flags & RTF_LLINFO) && 212 !(ro->ro_rt->rt_flags & RTF_HOST)) { 213 ip6_source = rtable_getsource(rtableid, AF_INET6); 214 if (ip6_source != NULL) { 215 struct ifaddr *ifa; 216 if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) != 217 NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) { 218 *in6src = &satosin6(ip6_source)->sin6_addr; 219 return (0); 220 } 221 } 222 } 223 224 if (ia6 == NULL) 225 return (EHOSTUNREACH); /* no route */ 226 227 *in6src = &ia6->ia_addr.sin6_addr; 228 return (0); 229} 230 231/* 232 * Return an IPv6 address, which is the most appropriate for a given 233 * destination and multicast options. 234 * If necessary, this function lookups the routing table and returns 235 * an entry to the caller for later use. 236 */ 237int 238in6_selectsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 239 struct ip6_moptions *mopts, unsigned int rtableid) 240{ 241 struct ifnet *ifp = NULL; 242 struct in6_addr *dst; 243 struct in6_ifaddr *ia6 = NULL; 244 245 dst = &dstsock->sin6_addr; 246 247 /* 248 * If the destination address is a link-local unicast address or 249 * a link/interface-local multicast address, and if the outgoing 250 * interface is specified by the sin6_scope_id filed, use an address 251 * associated with the interface. 252 * XXX: We're now trying to define more specific semantics of 253 * sin6_scope_id field, so this part will be rewritten in 254 * the near future. 255 */ 256 if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) || 257 IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) { 258 ifp = if_get(dstsock->sin6_scope_id); 259 if (ifp == NULL) 260 return (ENXIO); /* XXX: better error? */ 261 262 ia6 = in6_ifawithscope(ifp, dst, rtableid); 263 if_put(ifp); 264 265 if (ia6 == NULL) 266 return (EADDRNOTAVAIL); 267 268 *in6src = &ia6->ia_addr.sin6_addr; 269 return (0); 270 } 271 272 /* 273 * If the destination address is a multicast address and 274 * the outgoing interface for the address is specified 275 * by the caller, use an address associated with the interface. 276 * Even if the outgoing interface is not specified, we also 277 * choose a loopback interface as the outgoing interface. 278 */ 279 if (IN6_IS_ADDR_MULTICAST(dst)) { 280 ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL; 281 282 if (!ifp && dstsock->sin6_scope_id) 283 ifp = if_get(htons(dstsock->sin6_scope_id)); 284 285 if (ifp) { 286 ia6 = in6_ifawithscope(ifp, dst, rtableid); 287 if_put(ifp); 288 289 if (ia6 == NULL) 290 return (EADDRNOTAVAIL); 291 292 *in6src = &ia6->ia_addr.sin6_addr; 293 return (0); 294 } 295 } 296 297 return (EADDRNOTAVAIL); 298} 299 300struct rtentry * 301in6_selectroute(const struct in6_addr *dst, struct ip6_pktopts *opts, 302 struct route_in6 *ro, unsigned int rtableid) 303{ 304 /* 305 * Use a cached route if it exists and is valid, else try to allocate 306 * a new one. 307 */ 308 if (ro) { 309 route6_cache(ro, dst, rtableid); 310 if (ro->ro_rt == NULL) { 311 /* No route yet, so try to acquire one */ 312 ro->ro_rt = rtalloc_mpath(sin6tosa(&ro->ro_dst), 313 NULL, ro->ro_tableid); 314 } 315 316 /* 317 * Check if the outgoing interface conflicts with 318 * the interface specified by ipi6_ifindex (if specified). 319 * Note that loopback interface is always okay. 320 * (this may happen when we are sending a packet to one of 321 * our own addresses.) 322 */ 323 if (opts && opts->ip6po_pktinfo && 324 opts->ip6po_pktinfo->ipi6_ifindex) { 325 if (ro->ro_rt != NULL && 326 !ISSET(ro->ro_rt->rt_flags, RTF_LOCAL) && 327 ro->ro_rt->rt_ifidx != 328 opts->ip6po_pktinfo->ipi6_ifindex) { 329 return (NULL); 330 } 331 } 332 333 return (ro->ro_rt); 334 } 335 336 return (NULL); 337} 338 339int 340in6_selectif(const struct in6_addr *dst, struct ip6_pktopts *opts, 341 struct ip6_moptions *mopts, struct route_in6 *ro, struct ifnet **retifp, 342 u_int rtableid) 343{ 344 struct rtentry *rt = NULL; 345 struct in6_pktinfo *pi = NULL; 346 347 /* If the caller specify the outgoing interface explicitly, use it. */ 348 if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) { 349 *retifp = if_get(pi->ipi6_ifindex); 350 if (*retifp != NULL) 351 return (0); 352 } 353 354 /* 355 * If the destination address is a multicast address and the outgoing 356 * interface for the address is specified by the caller, use it. 357 */ 358 if (IN6_IS_ADDR_MULTICAST(dst) && 359 mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL) 360 return (0); 361 362 rt = in6_selectroute(dst, opts, ro, rtableid); 363 if (rt == NULL) 364 return (EHOSTUNREACH); 365 366 /* 367 * do not use a rejected or black hole route. 368 * XXX: this check should be done in the L2 output routine. 369 * However, if we skipped this check here, we'd see the following 370 * scenario: 371 * - install a rejected route for a scoped address prefix 372 * (like fe80::/10) 373 * - send a packet to a destination that matches the scoped prefix, 374 * with ambiguity about the scope zone. 375 * - pick the outgoing interface from the route, and disambiguate the 376 * scope zone with the interface. 377 * - ip6_output() would try to get another route with the "new" 378 * destination, which may be valid. 379 * - we'd see no error on output. 380 * Although this may not be very harmful, it should still be confusing. 381 * We thus reject the case here. 382 */ 383 if (rt && (rt->rt_flags & (RTF_REJECT | RTF_BLACKHOLE))) 384 return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH); 385 386 if (rt != NULL) 387 *retifp = if_get(rt->rt_ifidx); 388 389 return (0); 390} 391 392int 393in6_selecthlim(const struct inpcb *inp) 394{ 395 if (inp && inp->inp_hops >= 0) 396 return (inp->inp_hops); 397 398 return (ip6_defhlim); 399} 400 401/* 402 * generate kernel-internal form (scopeid embedded into s6_addr16[1]). 403 * If the address scope of is link-local, embed the interface index in the 404 * address. The routine determines our precedence 405 * between advanced API scope/interface specification and basic API 406 * specification. 407 * 408 * this function should be nuked in the future, when we get rid of 409 * embedded scopeid thing. 410 * 411 * XXX actually, it is over-specification to return ifp against sin6_scope_id. 412 * there can be multiple interfaces that belong to a particular scope zone 413 * (in specification, we have 1:N mapping between a scope zone and interfaces). 414 * we may want to change the function to return something other than ifp. 415 */ 416int 417in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6, 418 const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6) 419{ 420 u_int32_t scopeid; 421 422 *in6 = sin6->sin6_addr; 423 424 /* 425 * don't try to read sin6->sin6_addr beyond here, since the caller may 426 * ask us to overwrite existing sockaddr_in6 427 */ 428 429 if (IN6_IS_SCOPE_EMBED(in6)) { 430 struct in6_pktinfo *pi; 431 432 /* 433 * KAME assumption: link id == interface id 434 */ 435 436 if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) && 437 pi->ipi6_ifindex) 438 scopeid = pi->ipi6_ifindex; 439 else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) && 440 moptions6->im6o_ifidx) 441 scopeid = moptions6->im6o_ifidx; 442 else 443 scopeid = sin6->sin6_scope_id; 444 445 if (scopeid) { 446 struct ifnet *ifp; 447 448 ifp = if_get(scopeid); 449 if (ifp == NULL) 450 return ENXIO; /* XXX EINVAL? */ 451 /*XXX assignment to 16bit from 32bit variable */ 452 in6->s6_addr16[1] = htons(scopeid & 0xffff); 453 if_put(ifp); 454 } 455 } 456 457 return 0; 458} 459 460/* 461 * generate standard sockaddr_in6 from embedded form. 462 * touches sin6_addr and sin6_scope_id only. 463 * 464 * this function should be nuked in the future, when we get rid of 465 * embedded scopeid thing. 466 */ 467void 468in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6) 469{ 470 u_int32_t scopeid; 471 472 sin6->sin6_addr = *in6; 473 474 /* 475 * don't try to read *in6 beyond here, since the caller may 476 * ask us to overwrite existing sockaddr_in6 477 */ 478 479 sin6->sin6_scope_id = 0; 480 if (IN6_IS_SCOPE_EMBED(in6)) { 481 /* 482 * KAME assumption: link id == interface id 483 */ 484 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]); 485 if (scopeid) { 486 sin6->sin6_addr.s6_addr16[1] = 0; 487 sin6->sin6_scope_id = scopeid; 488 } 489 } 490} 491 492/* 493 * just clear the embedded scope identifier. 494 */ 495void 496in6_clearscope(struct in6_addr *addr) 497{ 498 if (IN6_IS_SCOPE_EMBED(addr)) 499 addr->s6_addr16[1] = 0; 500} 501