if_gre.c revision 1.61
1 /* $NetBSD: if_gre.c,v 1.61 2006/07/23 22:06:12 ad Exp $ */ 2 3 /* 4 * Copyright (c) 1998 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Heiko W.Rupp <hwr (at) pilhuhn.de> 9 * 10 * IPv6-over-GRE contributed by Gert Doering <gert (at) greenie.muc.de> 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the NetBSD 23 * Foundation, Inc. and its contributors. 24 * 4. Neither the name of The NetBSD Foundation nor the names of its 25 * contributors may be used to endorse or promote products derived 26 * from this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 38 * POSSIBILITY OF SUCH DAMAGE. 39 */ 40 41 /* 42 * Encapsulate L3 protocols into IP 43 * See RFC 1701 and 1702 for more details. 44 * If_gre is compatible with Cisco GRE tunnels, so you can 45 * have a NetBSD box as the other end of a tunnel interface of a Cisco 46 * router. See gre(4) for more details. 47 * Also supported: IP in IP encaps (proto 55) as of RFC 2004 48 */ 49 50 #include <sys/cdefs.h> 51 __KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.61 2006/07/23 22:06:12 ad Exp $"); 52 53 #include "opt_inet.h" 54 #include "opt_ns.h" 55 #include "bpfilter.h" 56 57 #ifdef INET 58 #include <sys/param.h> 59 #include <sys/malloc.h> 60 #include <sys/mbuf.h> 61 #include <sys/proc.h> 62 #include <sys/protosw.h> 63 #include <sys/socket.h> 64 #include <sys/ioctl.h> 65 #include <sys/queue.h> 66 #if __NetBSD__ 67 #include <sys/systm.h> 68 #include <sys/kauth.h> 69 #endif 70 71 #include <machine/cpu.h> 72 73 #include <net/ethertypes.h> 74 #include <net/if.h> 75 #include <net/if_types.h> 76 #include <net/netisr.h> 77 #include <net/route.h> 78 79 #ifdef INET 80 #include <netinet/in.h> 81 #include <netinet/in_systm.h> 82 #include <netinet/in_var.h> 83 #include <netinet/ip.h> 84 #include <netinet/ip_var.h> 85 #else 86 #error "Huh? if_gre without inet?" 87 #endif 88 89 #ifdef NS 90 #include <netns/ns.h> 91 #include <netns/ns_if.h> 92 #endif 93 94 #ifdef NETATALK 95 #include <netatalk/at.h> 96 #include <netatalk/at_var.h> 97 #include <netatalk/at_extern.h> 98 #endif 99 100 #if NBPFILTER > 0 101 #include <sys/time.h> 102 #include <net/bpf.h> 103 #endif 104 105 #include <net/if_gre.h> 106 107 /* 108 * It is not easy to calculate the right value for a GRE MTU. 109 * We leave this task to the admin and use the same default that 110 * other vendors use. 111 */ 112 #define GREMTU 1476 113 114 struct gre_softc_head gre_softc_list; 115 int ip_gre_ttl = GRE_TTL; 116 117 static int gre_clone_create(struct if_clone *, int); 118 static int gre_clone_destroy(struct ifnet *); 119 120 static struct if_clone gre_cloner = 121 IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy); 122 123 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 124 struct rtentry *); 125 static int gre_ioctl(struct ifnet *, u_long, caddr_t); 126 127 static int gre_compute_route(struct gre_softc *sc); 128 129 static int 130 gre_clone_create(struct if_clone *ifc, int unit) 131 { 132 struct gre_softc *sc; 133 134 sc = malloc(sizeof(struct gre_softc), M_DEVBUF, M_WAITOK); 135 memset(sc, 0, sizeof(struct gre_softc)); 136 137 snprintf(sc->sc_if.if_xname, sizeof(sc->sc_if.if_xname), "%s%d", 138 ifc->ifc_name, unit); 139 sc->sc_if.if_softc = sc; 140 sc->sc_if.if_type = IFT_TUNNEL; 141 sc->sc_if.if_addrlen = 0; 142 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 143 sc->sc_if.if_dlt = DLT_NULL; 144 sc->sc_if.if_mtu = GREMTU; 145 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 146 sc->sc_if.if_output = gre_output; 147 sc->sc_if.if_ioctl = gre_ioctl; 148 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 149 sc->g_proto = IPPROTO_GRE; 150 sc->sc_if.if_flags |= IFF_LINK0; 151 if_attach(&sc->sc_if); 152 if_alloc_sadl(&sc->sc_if); 153 #if NBPFILTER > 0 154 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 155 #endif 156 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 157 return (0); 158 } 159 160 static int 161 gre_clone_destroy(struct ifnet *ifp) 162 { 163 struct gre_softc *sc = ifp->if_softc; 164 165 LIST_REMOVE(sc, sc_list); 166 #if NBPFILTER > 0 167 bpfdetach(ifp); 168 #endif 169 if_detach(ifp); 170 free(sc, M_DEVBUF); 171 172 return (0); 173 } 174 175 /* 176 * The output routine. Takes a packet and encapsulates it in the protocol 177 * given by sc->g_proto. See also RFC 1701 and RFC 2004 178 */ 179 static int 180 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 181 struct rtentry *rt) 182 { 183 int error = 0; 184 struct gre_softc *sc = ifp->if_softc; 185 struct greip *gh; 186 struct ip *ip; 187 u_int8_t ip_tos = 0; 188 u_int16_t etype = 0; 189 struct mobile_h mob_h; 190 191 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 192 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 193 m_freem(m); 194 error = ENETDOWN; 195 goto end; 196 } 197 198 gh = NULL; 199 ip = NULL; 200 201 #if NBPFILTER >0 202 if (ifp->if_bpf) 203 bpf_mtap_af(ifp->if_bpf, dst->sa_family, m); 204 #endif 205 206 m->m_flags &= ~(M_BCAST|M_MCAST); 207 208 if (sc->g_proto == IPPROTO_MOBILE) { 209 if (dst->sa_family == AF_INET) { 210 struct mbuf *m0; 211 int msiz; 212 213 ip = mtod(m, struct ip *); 214 215 memset(&mob_h, 0, MOB_H_SIZ_L); 216 mob_h.proto = (ip->ip_p) << 8; 217 mob_h.odst = ip->ip_dst.s_addr; 218 ip->ip_dst.s_addr = sc->g_dst.s_addr; 219 220 /* 221 * If the packet comes from our host, we only change 222 * the destination address in the IP header. 223 * Else we also need to save and change the source 224 */ 225 if (in_hosteq(ip->ip_src, sc->g_src)) { 226 msiz = MOB_H_SIZ_S; 227 } else { 228 mob_h.proto |= MOB_H_SBIT; 229 mob_h.osrc = ip->ip_src.s_addr; 230 ip->ip_src.s_addr = sc->g_src.s_addr; 231 msiz = MOB_H_SIZ_L; 232 } 233 HTONS(mob_h.proto); 234 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz); 235 236 if ((m->m_data - msiz) < m->m_pktdat) { 237 /* need new mbuf */ 238 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 239 if (m0 == NULL) { 240 IF_DROP(&ifp->if_snd); 241 m_freem(m); 242 error = ENOBUFS; 243 goto end; 244 } 245 m0->m_next = m; 246 m->m_data += sizeof(struct ip); 247 m->m_len -= sizeof(struct ip); 248 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 249 m0->m_len = msiz + sizeof(struct ip); 250 m0->m_data += max_linkhdr; 251 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 252 sizeof(struct ip)); 253 m = m0; 254 } else { /* we have some space left in the old one */ 255 m->m_data -= msiz; 256 m->m_len += msiz; 257 m->m_pkthdr.len += msiz; 258 memmove(mtod(m, caddr_t), ip, 259 sizeof(struct ip)); 260 } 261 ip = mtod(m, struct ip *); 262 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 263 ip->ip_len = htons(ntohs(ip->ip_len) + msiz); 264 } else { /* AF_INET */ 265 IF_DROP(&ifp->if_snd); 266 m_freem(m); 267 error = EINVAL; 268 goto end; 269 } 270 } else if (sc->g_proto == IPPROTO_GRE) { 271 #ifdef GRE_DEBUG 272 printf( "start gre_output/GRE, dst->sa_family=%d\n", 273 dst->sa_family ); 274 #endif 275 switch (dst->sa_family) { 276 case AF_INET: 277 ip = mtod(m, struct ip *); 278 ip_tos = ip->ip_tos; 279 etype = ETHERTYPE_IP; 280 break; 281 #ifdef NETATALK 282 case AF_APPLETALK: 283 etype = ETHERTYPE_ATALK; 284 break; 285 #endif 286 #ifdef NS 287 case AF_NS: 288 etype = ETHERTYPE_NS; 289 break; 290 #endif 291 #ifdef INET6 292 case AF_INET6: 293 etype = ETHERTYPE_IPV6; 294 break; 295 #endif 296 default: 297 IF_DROP(&ifp->if_snd); 298 m_freem(m); 299 error = EAFNOSUPPORT; 300 goto end; 301 } 302 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 303 } else { 304 IF_DROP(&ifp->if_snd); 305 m_freem(m); 306 error = EINVAL; 307 goto end; 308 } 309 310 if (m == NULL) { /* impossible */ 311 IF_DROP(&ifp->if_snd); 312 error = ENOBUFS; 313 goto end; 314 } 315 316 gh = mtod(m, struct greip *); 317 if (sc->g_proto == IPPROTO_GRE) { 318 /* we don't have any GRE flags for now */ 319 320 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 321 gh->gi_ptype = htons(etype); 322 } 323 324 gh->gi_pr = sc->g_proto; 325 if (sc->g_proto != IPPROTO_MOBILE) { 326 gh->gi_src = sc->g_src; 327 gh->gi_dst = sc->g_dst; 328 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 329 ((struct ip*)gh)->ip_ttl = ip_gre_ttl; 330 ((struct ip*)gh)->ip_tos = ip_tos; 331 gh->gi_len = htons(m->m_pkthdr.len); 332 } 333 334 ifp->if_opackets++; 335 ifp->if_obytes += m->m_pkthdr.len; 336 /* send it off */ 337 error = ip_output(m, NULL, &sc->route, 0, 338 (struct ip_moptions *)NULL, (struct socket *)NULL); 339 end: 340 if (error) 341 ifp->if_oerrors++; 342 return (error); 343 } 344 345 static int 346 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 347 { 348 struct lwp *l = curlwp; /* XXX */ 349 struct ifreq *ifr = (struct ifreq *)data; 350 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 351 struct gre_softc *sc = ifp->if_softc; 352 int s; 353 struct sockaddr_in si; 354 struct sockaddr *sa = NULL; 355 int error; 356 357 switch (cmd) { 358 case SIOCSIFFLAGS: 359 case SIOCSIFMTU: 360 case GRESPROTO: 361 case GRESADDRD: 362 case GRESADDRS: 363 case SIOCSLIFPHYADDR: 364 case SIOCDIFPHYADDR: 365 if ((error = kauth_authorize_generic(l->l_cred, 366 KAUTH_GENERIC_ISSUSER, &l->l_acflag)) != 0) 367 return (error); 368 break; 369 default: 370 error = 0; 371 break; 372 } 373 374 s = splnet(); 375 switch (cmd) { 376 case SIOCSIFADDR: 377 ifp->if_flags |= IFF_UP; 378 break; 379 case SIOCSIFDSTADDR: 380 break; 381 case SIOCSIFFLAGS: 382 if ((ifr->ifr_flags & IFF_LINK0) != 0) 383 sc->g_proto = IPPROTO_GRE; 384 else 385 sc->g_proto = IPPROTO_MOBILE; 386 break; 387 case SIOCSIFMTU: 388 if (ifr->ifr_mtu < 576) { 389 error = EINVAL; 390 break; 391 } 392 ifp->if_mtu = ifr->ifr_mtu; 393 break; 394 case SIOCGIFMTU: 395 ifr->ifr_mtu = sc->sc_if.if_mtu; 396 break; 397 case SIOCADDMULTI: 398 case SIOCDELMULTI: 399 if (ifr == 0) { 400 error = EAFNOSUPPORT; 401 break; 402 } 403 switch (ifr->ifr_addr.sa_family) { 404 #ifdef INET 405 case AF_INET: 406 break; 407 #endif 408 #ifdef INET6 409 case AF_INET6: 410 break; 411 #endif 412 default: 413 error = EAFNOSUPPORT; 414 break; 415 } 416 break; 417 case GRESPROTO: 418 sc->g_proto = ifr->ifr_flags; 419 switch (sc->g_proto) { 420 case IPPROTO_GRE: 421 ifp->if_flags |= IFF_LINK0; 422 break; 423 case IPPROTO_MOBILE: 424 ifp->if_flags &= ~IFF_LINK0; 425 break; 426 default: 427 error = EPROTONOSUPPORT; 428 break; 429 } 430 break; 431 case GREGPROTO: 432 ifr->ifr_flags = sc->g_proto; 433 break; 434 case GRESADDRS: 435 case GRESADDRD: 436 /* 437 * set tunnel endpoints, compute a less specific route 438 * to the remote end and mark if as up 439 */ 440 sa = &ifr->ifr_addr; 441 if (cmd == GRESADDRS) 442 sc->g_src = (satosin(sa))->sin_addr; 443 if (cmd == GRESADDRD) 444 sc->g_dst = (satosin(sa))->sin_addr; 445 recompute: 446 if ((sc->g_src.s_addr != INADDR_ANY) && 447 (sc->g_dst.s_addr != INADDR_ANY)) { 448 if (sc->route.ro_rt != 0) /* free old route */ 449 RTFREE(sc->route.ro_rt); 450 if (gre_compute_route(sc) == 0) 451 ifp->if_flags |= IFF_RUNNING; 452 else 453 ifp->if_flags &= ~IFF_RUNNING; 454 } 455 break; 456 case GREGADDRS: 457 memset(&si, 0, sizeof(si)); 458 si.sin_family = AF_INET; 459 si.sin_len = sizeof(struct sockaddr_in); 460 si.sin_addr.s_addr = sc->g_src.s_addr; 461 sa = sintosa(&si); 462 ifr->ifr_addr = *sa; 463 break; 464 case GREGADDRD: 465 memset(&si, 0, sizeof(si)); 466 si.sin_family = AF_INET; 467 si.sin_len = sizeof(struct sockaddr_in); 468 si.sin_addr.s_addr = sc->g_dst.s_addr; 469 sa = sintosa(&si); 470 ifr->ifr_addr = *sa; 471 break; 472 case SIOCSLIFPHYADDR: 473 if (lifr->addr.ss_family != AF_INET || 474 lifr->dstaddr.ss_family != AF_INET) { 475 error = EAFNOSUPPORT; 476 break; 477 } 478 if (lifr->addr.ss_len != sizeof(si) || 479 lifr->dstaddr.ss_len != sizeof(si)) { 480 error = EINVAL; 481 break; 482 } 483 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 484 sc->g_dst = 485 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 486 goto recompute; 487 case SIOCDIFPHYADDR: 488 sc->g_src.s_addr = INADDR_ANY; 489 sc->g_dst.s_addr = INADDR_ANY; 490 break; 491 case SIOCGLIFPHYADDR: 492 if (sc->g_src.s_addr == INADDR_ANY || 493 sc->g_dst.s_addr == INADDR_ANY) { 494 error = EADDRNOTAVAIL; 495 break; 496 } 497 memset(&si, 0, sizeof(si)); 498 si.sin_family = AF_INET; 499 si.sin_len = sizeof(struct sockaddr_in); 500 si.sin_addr.s_addr = sc->g_src.s_addr; 501 memcpy(&lifr->addr, &si, sizeof(si)); 502 si.sin_addr.s_addr = sc->g_dst.s_addr; 503 memcpy(&lifr->dstaddr, &si, sizeof(si)); 504 break; 505 default: 506 error = EINVAL; 507 break; 508 } 509 510 splx(s); 511 return (error); 512 } 513 514 /* 515 * computes a route to our destination that is not the one 516 * which would be taken by ip_output(), as this one will loop back to 517 * us. If the interface is p2p as a--->b, then a routing entry exists 518 * If we now send a packet to b (e.g. ping b), this will come down here 519 * gets src=a, dst=b tacked on and would from ip_output() sent back to 520 * if_gre. 521 * Goal here is to compute a route to b that is less specific than 522 * a-->b. We know that this one exists as in normal operation we have 523 * at least a default route which matches. 524 */ 525 static int 526 gre_compute_route(struct gre_softc *sc) 527 { 528 struct route *ro; 529 u_int32_t a, b, c; 530 531 ro = &sc->route; 532 533 memset(ro, 0, sizeof(struct route)); 534 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 535 ro->ro_dst.sa_family = AF_INET; 536 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 537 538 /* 539 * toggle last bit, so our interface is not found, but a less 540 * specific route. I'd rather like to specify a shorter mask, 541 * but this is not possible. Should work though. XXX 542 * there is a simpler way ... 543 */ 544 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 545 a = ntohl(sc->g_dst.s_addr); 546 b = a & 0x01; 547 c = a & 0xfffffffe; 548 b = b ^ 0x01; 549 a = b | c; 550 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 551 = htonl(a); 552 } 553 554 #ifdef DIAGNOSTIC 555 printf("%s: searching for a route to %s", sc->sc_if.if_xname, 556 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 557 #endif 558 559 rtalloc(ro); 560 561 /* 562 * check if this returned a route at all and this route is no 563 * recursion to ourself 564 */ 565 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 566 #ifdef DIAGNOSTIC 567 if (ro->ro_rt == NULL) 568 printf(" - no route found!\n"); 569 else 570 printf(" - route loops back to ourself!\n"); 571 #endif 572 return EADDRNOTAVAIL; 573 } 574 575 /* 576 * now change it back - else ip_output will just drop 577 * the route and search one to this interface ... 578 */ 579 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 580 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 581 582 #ifdef DIAGNOSTIC 583 printf(", choosing %s with gateway %s", ro->ro_rt->rt_ifp->if_xname, 584 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 585 printf("\n"); 586 #endif 587 588 return 0; 589 } 590 591 /* 592 * do a checksum of a buffer - much like in_cksum, which operates on 593 * mbufs. 594 */ 595 u_int16_t 596 gre_in_cksum(u_int16_t *p, u_int len) 597 { 598 u_int32_t sum = 0; 599 int nwords = len >> 1; 600 601 while (nwords-- != 0) 602 sum += *p++; 603 604 if (len & 1) { 605 union { 606 u_short w; 607 u_char c[2]; 608 } u; 609 u.c[0] = *(u_char *)p; 610 u.c[1] = 0; 611 sum += u.w; 612 } 613 614 /* end-around-carry */ 615 sum = (sum >> 16) + (sum & 0xffff); 616 sum += (sum >> 16); 617 return (~sum); 618 } 619 #endif 620 621 void greattach(int); 622 623 /* ARGSUSED */ 624 void 625 greattach(int count) 626 { 627 #ifdef INET 628 LIST_INIT(&gre_softc_list); 629 if_clone_attach(&gre_cloner); 630 #endif 631 } 632
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