in6_src.c revision 1.87
1/* $OpenBSD: in6_src.c,v 1.87 2023/11/28 13:23:20 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(struct sockaddr_in6 *, 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(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 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(dstsock, 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 if (!rtisvalid(ro->ro_rt) || (ro->ro_tableid != rtableid) || 183 !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst)) { 184 rtfree(ro->ro_rt); 185 ro->ro_rt = NULL; 186 } 187 if (ro->ro_rt == NULL) { 188 struct sockaddr_in6 *sa6; 189 190 /* No route yet, so try to acquire one */ 191 bzero(&ro->ro_dst, sizeof(struct sockaddr_in6)); 192 ro->ro_tableid = rtableid; 193 sa6 = &ro->ro_dst; 194 sa6->sin6_family = AF_INET6; 195 sa6->sin6_len = sizeof(struct sockaddr_in6); 196 sa6->sin6_addr = *dst; 197 sa6->sin6_scope_id = dstsock->sin6_scope_id; 198 ro->ro_rt = rtalloc(sin6tosa(&ro->ro_dst), 199 RT_RESOLVE, ro->ro_tableid); 200 } 201 202 /* 203 * in_pcbconnect() checks out IFF_LOOPBACK to skip using 204 * the address. But we don't know why it does so. 205 * It is necessary to ensure the scope even for lo0 206 * so doesn't check out IFF_LOOPBACK. 207 */ 208 209 if (ro->ro_rt) { 210 ifp = if_get(ro->ro_rt->rt_ifidx); 211 if (ifp != NULL) { 212 ia6 = in6_ifawithscope(ifp, dst, rtableid); 213 if_put(ifp); 214 } 215 if (ia6 == NULL) /* xxx scope error ?*/ 216 ia6 = ifatoia6(ro->ro_rt->rt_ifa); 217 } 218 219 /* 220 * Use preferred source address if : 221 * - destination is not onlink 222 * - preferred source address is set 223 * - output interface is UP 224 */ 225 if (ro->ro_rt && !(ro->ro_rt->rt_flags & RTF_LLINFO) && 226 !(ro->ro_rt->rt_flags & RTF_HOST)) { 227 ip6_source = rtable_getsource(rtableid, AF_INET6); 228 if (ip6_source != NULL) { 229 struct ifaddr *ifa; 230 if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) != 231 NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) { 232 *in6src = &satosin6(ip6_source)->sin6_addr; 233 return (0); 234 } 235 } 236 } 237 238 if (ia6 == NULL) 239 return (EHOSTUNREACH); /* no route */ 240 241 *in6src = &ia6->ia_addr.sin6_addr; 242 return (0); 243} 244 245/* 246 * Return an IPv6 address, which is the most appropriate for a given 247 * destination and multicast options. 248 * If necessary, this function lookups the routing table and returns 249 * an entry to the caller for later use. 250 */ 251int 252in6_selectsrc(struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 253 struct ip6_moptions *mopts, unsigned int rtableid) 254{ 255 struct ifnet *ifp = NULL; 256 struct in6_addr *dst; 257 struct in6_ifaddr *ia6 = NULL; 258 259 dst = &dstsock->sin6_addr; 260 261 /* 262 * If the destination address is a link-local unicast address or 263 * a link/interface-local multicast address, and if the outgoing 264 * interface is specified by the sin6_scope_id filed, use an address 265 * associated with the interface. 266 * XXX: We're now trying to define more specific semantics of 267 * sin6_scope_id field, so this part will be rewritten in 268 * the near future. 269 */ 270 if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) || 271 IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) { 272 ifp = if_get(dstsock->sin6_scope_id); 273 if (ifp == NULL) 274 return (ENXIO); /* XXX: better error? */ 275 276 ia6 = in6_ifawithscope(ifp, dst, rtableid); 277 if_put(ifp); 278 279 if (ia6 == NULL) 280 return (EADDRNOTAVAIL); 281 282 *in6src = &ia6->ia_addr.sin6_addr; 283 return (0); 284 } 285 286 /* 287 * If the destination address is a multicast address and 288 * the outgoing interface for the address is specified 289 * by the caller, use an address associated with the interface. 290 * Even if the outgoing interface is not specified, we also 291 * choose a loopback interface as the outgoing interface. 292 */ 293 if (IN6_IS_ADDR_MULTICAST(dst)) { 294 ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL; 295 296 if (!ifp && dstsock->sin6_scope_id) 297 ifp = if_get(htons(dstsock->sin6_scope_id)); 298 299 if (ifp) { 300 ia6 = in6_ifawithscope(ifp, dst, rtableid); 301 if_put(ifp); 302 303 if (ia6 == NULL) 304 return (EADDRNOTAVAIL); 305 306 *in6src = &ia6->ia_addr.sin6_addr; 307 return (0); 308 } 309 } 310 311 return (EADDRNOTAVAIL); 312} 313 314struct rtentry * 315in6_selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 316 struct route_in6 *ro, unsigned int rtableid) 317{ 318 struct in6_addr *dst; 319 320 dst = &dstsock->sin6_addr; 321 322 /* 323 * Use a cached route if it exists and is valid, else try to allocate 324 * a new one. 325 */ 326 if (ro) { 327 if (rtisvalid(ro->ro_rt)) 328 KASSERT(sin6tosa(&ro->ro_dst)->sa_family == AF_INET6); 329 if (!rtisvalid(ro->ro_rt) || 330 !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst)) { 331 rtfree(ro->ro_rt); 332 ro->ro_rt = NULL; 333 } 334 if (ro->ro_rt == NULL) { 335 struct sockaddr_in6 *sa6; 336 337 /* No route yet, so try to acquire one */ 338 bzero(&ro->ro_dst, sizeof(struct sockaddr_in6)); 339 ro->ro_tableid = rtableid; 340 sa6 = &ro->ro_dst; 341 *sa6 = *dstsock; 342 sa6->sin6_scope_id = 0; 343 ro->ro_tableid = rtableid; 344 ro->ro_rt = rtalloc_mpath(sin6tosa(&ro->ro_dst), 345 NULL, ro->ro_tableid); 346 } 347 348 /* 349 * Check if the outgoing interface conflicts with 350 * the interface specified by ipi6_ifindex (if specified). 351 * Note that loopback interface is always okay. 352 * (this may happen when we are sending a packet to one of 353 * our own addresses.) 354 */ 355 if (opts && opts->ip6po_pktinfo && 356 opts->ip6po_pktinfo->ipi6_ifindex) { 357 if (ro->ro_rt != NULL && 358 !ISSET(ro->ro_rt->rt_flags, RTF_LOCAL) && 359 ro->ro_rt->rt_ifidx != 360 opts->ip6po_pktinfo->ipi6_ifindex) { 361 return (NULL); 362 } 363 } 364 365 return (ro->ro_rt); 366 } 367 368 return (NULL); 369} 370 371int 372in6_selectif(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 373 struct ip6_moptions *mopts, struct route_in6 *ro, struct ifnet **retifp, 374 u_int rtableid) 375{ 376 struct rtentry *rt = NULL; 377 struct in6_pktinfo *pi = NULL; 378 379 /* If the caller specify the outgoing interface explicitly, use it. */ 380 if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) { 381 *retifp = if_get(pi->ipi6_ifindex); 382 if (*retifp != NULL) 383 return (0); 384 } 385 386 /* 387 * If the destination address is a multicast address and the outgoing 388 * interface for the address is specified by the caller, use it. 389 */ 390 if (IN6_IS_ADDR_MULTICAST(&dstsock->sin6_addr) && 391 mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL) 392 return (0); 393 394 rt = in6_selectroute(dstsock, opts, ro, rtableid); 395 if (rt == NULL) 396 return (EHOSTUNREACH); 397 398 /* 399 * do not use a rejected or black hole route. 400 * XXX: this check should be done in the L2 output routine. 401 * However, if we skipped this check here, we'd see the following 402 * scenario: 403 * - install a rejected route for a scoped address prefix 404 * (like fe80::/10) 405 * - send a packet to a destination that matches the scoped prefix, 406 * with ambiguity about the scope zone. 407 * - pick the outgoing interface from the route, and disambiguate the 408 * scope zone with the interface. 409 * - ip6_output() would try to get another route with the "new" 410 * destination, which may be valid. 411 * - we'd see no error on output. 412 * Although this may not be very harmful, it should still be confusing. 413 * We thus reject the case here. 414 */ 415 if (rt && (rt->rt_flags & (RTF_REJECT | RTF_BLACKHOLE))) 416 return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH); 417 418 if (rt != NULL) 419 *retifp = if_get(rt->rt_ifidx); 420 421 return (0); 422} 423 424int 425in6_selecthlim(struct inpcb *in6p) 426{ 427 if (in6p && in6p->inp_hops >= 0) 428 return (in6p->inp_hops); 429 430 return (ip6_defhlim); 431} 432 433/* 434 * generate kernel-internal form (scopeid embedded into s6_addr16[1]). 435 * If the address scope of is link-local, embed the interface index in the 436 * address. The routine determines our precedence 437 * between advanced API scope/interface specification and basic API 438 * specification. 439 * 440 * this function should be nuked in the future, when we get rid of 441 * embedded scopeid thing. 442 * 443 * XXX actually, it is over-specification to return ifp against sin6_scope_id. 444 * there can be multiple interfaces that belong to a particular scope zone 445 * (in specification, we have 1:N mapping between a scope zone and interfaces). 446 * we may want to change the function to return something other than ifp. 447 */ 448int 449in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6, 450 const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6) 451{ 452 u_int32_t scopeid; 453 454 *in6 = sin6->sin6_addr; 455 456 /* 457 * don't try to read sin6->sin6_addr beyond here, since the caller may 458 * ask us to overwrite existing sockaddr_in6 459 */ 460 461 if (IN6_IS_SCOPE_EMBED(in6)) { 462 struct in6_pktinfo *pi; 463 464 /* 465 * KAME assumption: link id == interface id 466 */ 467 468 if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) && 469 pi->ipi6_ifindex) 470 scopeid = pi->ipi6_ifindex; 471 else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) && 472 moptions6->im6o_ifidx) 473 scopeid = moptions6->im6o_ifidx; 474 else 475 scopeid = sin6->sin6_scope_id; 476 477 if (scopeid) { 478 struct ifnet *ifp; 479 480 ifp = if_get(scopeid); 481 if (ifp == NULL) 482 return ENXIO; /* XXX EINVAL? */ 483 /*XXX assignment to 16bit from 32bit variable */ 484 in6->s6_addr16[1] = htons(scopeid & 0xffff); 485 if_put(ifp); 486 } 487 } 488 489 return 0; 490} 491 492/* 493 * generate standard sockaddr_in6 from embedded form. 494 * touches sin6_addr and sin6_scope_id only. 495 * 496 * this function should be nuked in the future, when we get rid of 497 * embedded scopeid thing. 498 */ 499void 500in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6) 501{ 502 u_int32_t scopeid; 503 504 sin6->sin6_addr = *in6; 505 506 /* 507 * don't try to read *in6 beyond here, since the caller may 508 * ask us to overwrite existing sockaddr_in6 509 */ 510 511 sin6->sin6_scope_id = 0; 512 if (IN6_IS_SCOPE_EMBED(in6)) { 513 /* 514 * KAME assumption: link id == interface id 515 */ 516 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]); 517 if (scopeid) { 518 sin6->sin6_addr.s6_addr16[1] = 0; 519 sin6->sin6_scope_id = scopeid; 520 } 521 } 522} 523 524/* 525 * just clear the embedded scope identifier. 526 */ 527void 528in6_clearscope(struct in6_addr *addr) 529{ 530 if (IN6_IS_SCOPE_EMBED(addr)) 531 addr->s6_addr16[1] = 0; 532} 533