if_gre.c revision 1.45.2.3
1 /* $NetBSD: if_gre.c,v 1.45.2.3 2004/09/18 14:54:16 skrll 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 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Encapsulate L3 protocols into IP 41 * See RFC 1701 and 1702 for more details. 42 * If_gre is compatible with Cisco GRE tunnels, so you can 43 * have a NetBSD box as the other end of a tunnel interface of a Cisco 44 * router. See gre(4) for more details. 45 * Also supported: IP in IP encaps (proto 55) as of RFC 2004 46 */ 47 48 #include <sys/cdefs.h> 49 __KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.45.2.3 2004/09/18 14:54:16 skrll Exp $"); 50 51 #include "opt_inet.h" 52 #include "opt_ns.h" 53 #include "bpfilter.h" 54 55 #include <sys/param.h> 56 #include <sys/malloc.h> 57 #include <sys/mbuf.h> 58 #include <sys/proc.h> 59 #include <sys/protosw.h> 60 #include <sys/socket.h> 61 #include <sys/ioctl.h> 62 #include <sys/queue.h> 63 #if __NetBSD__ 64 #include <sys/systm.h> 65 #endif 66 67 #include <machine/cpu.h> 68 69 #include <net/ethertypes.h> 70 #include <net/if.h> 71 #include <net/if_types.h> 72 #include <net/netisr.h> 73 #include <net/route.h> 74 75 #ifdef INET 76 #include <netinet/in.h> 77 #include <netinet/in_systm.h> 78 #include <netinet/in_var.h> 79 #include <netinet/ip.h> 80 #include <netinet/ip_var.h> 81 #else 82 #error "Huh? if_gre without inet?" 83 #endif 84 85 #ifdef NS 86 #include <netns/ns.h> 87 #include <netns/ns_if.h> 88 #endif 89 90 #ifdef NETATALK 91 #include <netatalk/at.h> 92 #include <netatalk/at_var.h> 93 #include <netatalk/at_extern.h> 94 #endif 95 96 #if NBPFILTER > 0 97 #include <sys/time.h> 98 #include <net/bpf.h> 99 #endif 100 101 #include <net/if_gre.h> 102 103 /* 104 * It is not easy to calculate the right value for a GRE MTU. 105 * We leave this task to the admin and use the same default that 106 * other vendors use. 107 */ 108 #define GREMTU 1476 109 110 struct gre_softc_head gre_softc_list; 111 int ip_gre_ttl = GRE_TTL; 112 113 int gre_clone_create __P((struct if_clone *, int)); 114 void gre_clone_destroy __P((struct ifnet *)); 115 116 struct if_clone gre_cloner = 117 IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy); 118 119 int gre_compute_route(struct gre_softc *sc); 120 121 void greattach __P((int)); 122 123 /* ARGSUSED */ 124 void 125 greattach(count) 126 int count; 127 { 128 129 LIST_INIT(&gre_softc_list); 130 if_clone_attach(&gre_cloner); 131 } 132 133 int 134 gre_clone_create(ifc, unit) 135 struct if_clone *ifc; 136 int unit; 137 { 138 struct gre_softc *sc; 139 140 sc = malloc(sizeof(struct gre_softc), M_DEVBUF, M_WAITOK); 141 memset(sc, 0, sizeof(struct gre_softc)); 142 143 snprintf(sc->sc_if.if_xname, sizeof(sc->sc_if.if_xname), "%s%d", 144 ifc->ifc_name, unit); 145 sc->sc_if.if_softc = sc; 146 sc->sc_if.if_type = IFT_TUNNEL; 147 sc->sc_if.if_addrlen = 0; 148 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 149 sc->sc_if.if_dlt = DLT_NULL; 150 sc->sc_if.if_mtu = GREMTU; 151 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 152 sc->sc_if.if_output = gre_output; 153 sc->sc_if.if_ioctl = gre_ioctl; 154 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 155 sc->g_proto = IPPROTO_GRE; 156 sc->sc_if.if_flags |= IFF_LINK0; 157 if_attach(&sc->sc_if); 158 if_alloc_sadl(&sc->sc_if); 159 #if NBPFILTER > 0 160 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 161 #endif 162 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 163 return (0); 164 } 165 166 void 167 gre_clone_destroy(ifp) 168 struct ifnet *ifp; 169 { 170 struct gre_softc *sc = ifp->if_softc; 171 172 LIST_REMOVE(sc, sc_list); 173 #if NBPFILTER > 0 174 bpfdetach(ifp); 175 #endif 176 if_detach(ifp); 177 free(sc, M_DEVBUF); 178 } 179 180 /* 181 * The output routine. Takes a packet and encapsulates it in the protocol 182 * given by sc->g_proto. See also RFC 1701 and RFC 2004 183 */ 184 int 185 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 186 struct rtentry *rt) 187 { 188 int error = 0; 189 struct gre_softc *sc = ifp->if_softc; 190 struct greip *gh; 191 struct ip *ip; 192 u_int16_t etype = 0; 193 struct mobile_h mob_h; 194 195 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 196 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 197 m_freem(m); 198 error = ENETDOWN; 199 goto end; 200 } 201 202 gh = NULL; 203 ip = NULL; 204 205 #if NBPFILTER >0 206 if (ifp->if_bpf) 207 bpf_mtap_af(ifp->if_bpf, dst->sa_family, m); 208 #endif 209 210 m->m_flags &= ~(M_BCAST|M_MCAST); 211 212 if (sc->g_proto == IPPROTO_MOBILE) { 213 if (dst->sa_family == AF_INET) { 214 struct mbuf *m0; 215 int msiz; 216 217 ip = mtod(m, struct ip *); 218 219 memset(&mob_h, 0, MOB_H_SIZ_L); 220 mob_h.proto = (ip->ip_p) << 8; 221 mob_h.odst = ip->ip_dst.s_addr; 222 ip->ip_dst.s_addr = sc->g_dst.s_addr; 223 224 /* 225 * If the packet comes from our host, we only change 226 * the destination address in the IP header. 227 * Else we also need to save and change the source 228 */ 229 if (in_hosteq(ip->ip_src, sc->g_src)) { 230 msiz = MOB_H_SIZ_S; 231 } else { 232 mob_h.proto |= MOB_H_SBIT; 233 mob_h.osrc = ip->ip_src.s_addr; 234 ip->ip_src.s_addr = sc->g_src.s_addr; 235 msiz = MOB_H_SIZ_L; 236 } 237 HTONS(mob_h.proto); 238 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz); 239 240 if ((m->m_data - msiz) < m->m_pktdat) { 241 /* need new mbuf */ 242 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 243 if (m0 == NULL) { 244 IF_DROP(&ifp->if_snd); 245 m_freem(m); 246 error = ENOBUFS; 247 goto end; 248 } 249 m0->m_next = m; 250 m->m_data += sizeof(struct ip); 251 m->m_len -= sizeof(struct ip); 252 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 253 m0->m_len = msiz + sizeof(struct ip); 254 m0->m_data += max_linkhdr; 255 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 256 sizeof(struct ip)); 257 m = m0; 258 } else { /* we have some space left in the old one */ 259 m->m_data -= msiz; 260 m->m_len += msiz; 261 m->m_pkthdr.len += msiz; 262 memmove(mtod(m, caddr_t), ip, 263 sizeof(struct ip)); 264 } 265 ip = mtod(m, struct ip *); 266 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 267 ip->ip_len = htons(ntohs(ip->ip_len) + msiz); 268 } else { /* AF_INET */ 269 IF_DROP(&ifp->if_snd); 270 m_freem(m); 271 error = EINVAL; 272 goto end; 273 } 274 } else if (sc->g_proto == IPPROTO_GRE) { 275 switch (dst->sa_family) { 276 case AF_INET: 277 ip = mtod(m, struct ip *); 278 etype = ETHERTYPE_IP; 279 break; 280 #ifdef NETATALK 281 case AF_APPLETALK: 282 etype = ETHERTYPE_ATALK; 283 break; 284 #endif 285 #ifdef NS 286 case AF_NS: 287 etype = ETHERTYPE_NS; 288 break; 289 #endif 290 default: 291 IF_DROP(&ifp->if_snd); 292 m_freem(m); 293 error = EAFNOSUPPORT; 294 goto end; 295 } 296 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 297 } else { 298 IF_DROP(&ifp->if_snd); 299 m_freem(m); 300 error = EINVAL; 301 goto end; 302 } 303 304 if (m == NULL) { /* impossible */ 305 IF_DROP(&ifp->if_snd); 306 error = ENOBUFS; 307 goto end; 308 } 309 310 gh = mtod(m, struct greip *); 311 if (sc->g_proto == IPPROTO_GRE) { 312 /* we don't have any GRE flags for now */ 313 314 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 315 gh->gi_ptype = htons(etype); 316 } 317 318 gh->gi_pr = sc->g_proto; 319 if (sc->g_proto != IPPROTO_MOBILE) { 320 gh->gi_src = sc->g_src; 321 gh->gi_dst = sc->g_dst; 322 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 323 ((struct ip*)gh)->ip_ttl = ip_gre_ttl; 324 ((struct ip*)gh)->ip_tos = ip->ip_tos; 325 gh->gi_len = htons(m->m_pkthdr.len); 326 } 327 328 ifp->if_opackets++; 329 ifp->if_obytes += m->m_pkthdr.len; 330 /* send it off */ 331 error = ip_output(m, NULL, &sc->route, 0, 332 (struct ip_moptions *)NULL, (struct socket *)NULL); 333 end: 334 if (error) 335 ifp->if_oerrors++; 336 return (error); 337 } 338 339 int 340 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 341 { 342 struct proc *p = curproc; /* XXX */ 343 struct ifreq *ifr = (struct ifreq *)data; 344 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 345 struct gre_softc *sc = ifp->if_softc; 346 int s; 347 struct sockaddr_in si; 348 struct sockaddr *sa = NULL; 349 int error; 350 351 error = 0; 352 353 s = splnet(); 354 switch (cmd) { 355 case SIOCSIFADDR: 356 ifp->if_flags |= IFF_UP; 357 break; 358 case SIOCSIFDSTADDR: 359 break; 360 case SIOCSIFFLAGS: 361 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 362 break; 363 if ((ifr->ifr_flags & IFF_LINK0) != 0) 364 sc->g_proto = IPPROTO_GRE; 365 else 366 sc->g_proto = IPPROTO_MOBILE; 367 break; 368 case SIOCSIFMTU: 369 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 370 break; 371 if (ifr->ifr_mtu < 576) { 372 error = EINVAL; 373 break; 374 } 375 ifp->if_mtu = ifr->ifr_mtu; 376 break; 377 case SIOCGIFMTU: 378 ifr->ifr_mtu = sc->sc_if.if_mtu; 379 break; 380 case SIOCADDMULTI: 381 case SIOCDELMULTI: 382 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 383 break; 384 if (ifr == 0) { 385 error = EAFNOSUPPORT; 386 break; 387 } 388 switch (ifr->ifr_addr.sa_family) { 389 #ifdef INET 390 case AF_INET: 391 break; 392 #endif 393 default: 394 error = EAFNOSUPPORT; 395 break; 396 } 397 break; 398 case GRESPROTO: 399 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 400 break; 401 sc->g_proto = ifr->ifr_flags; 402 switch (sc->g_proto) { 403 case IPPROTO_GRE: 404 ifp->if_flags |= IFF_LINK0; 405 break; 406 case IPPROTO_MOBILE: 407 ifp->if_flags &= ~IFF_LINK0; 408 break; 409 default: 410 error = EPROTONOSUPPORT; 411 break; 412 } 413 break; 414 case GREGPROTO: 415 ifr->ifr_flags = sc->g_proto; 416 break; 417 case GRESADDRS: 418 case GRESADDRD: 419 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 420 break; 421 /* 422 * set tunnel endpoints, compute a less specific route 423 * to the remote end and mark if as up 424 */ 425 sa = &ifr->ifr_addr; 426 if (cmd == GRESADDRS) 427 sc->g_src = (satosin(sa))->sin_addr; 428 if (cmd == GRESADDRD) 429 sc->g_dst = (satosin(sa))->sin_addr; 430 recompute: 431 if ((sc->g_src.s_addr != INADDR_ANY) && 432 (sc->g_dst.s_addr != INADDR_ANY)) { 433 if (sc->route.ro_rt != 0) /* free old route */ 434 RTFREE(sc->route.ro_rt); 435 if (gre_compute_route(sc) == 0) 436 ifp->if_flags |= IFF_RUNNING; 437 else 438 ifp->if_flags &= ~IFF_RUNNING; 439 } 440 break; 441 case GREGADDRS: 442 memset(&si, 0, sizeof(si)); 443 si.sin_family = AF_INET; 444 si.sin_len = sizeof(struct sockaddr_in); 445 si.sin_addr.s_addr = sc->g_src.s_addr; 446 sa = sintosa(&si); 447 ifr->ifr_addr = *sa; 448 break; 449 case GREGADDRD: 450 memset(&si, 0, sizeof(si)); 451 si.sin_family = AF_INET; 452 si.sin_len = sizeof(struct sockaddr_in); 453 si.sin_addr.s_addr = sc->g_dst.s_addr; 454 sa = sintosa(&si); 455 ifr->ifr_addr = *sa; 456 break; 457 case SIOCSLIFPHYADDR: 458 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 459 break; 460 if (lifr->addr.ss_family != AF_INET || 461 lifr->dstaddr.ss_family != AF_INET) { 462 error = EAFNOSUPPORT; 463 break; 464 } 465 if (lifr->addr.ss_len != sizeof(si) || 466 lifr->dstaddr.ss_len != sizeof(si)) { 467 error = EINVAL; 468 break; 469 } 470 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 471 sc->g_dst = 472 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 473 goto recompute; 474 case SIOCDIFPHYADDR: 475 if ((error = suser(p->p_ucred, &p->p_acflag)) != 0) 476 break; 477 sc->g_src.s_addr = INADDR_ANY; 478 sc->g_dst.s_addr = INADDR_ANY; 479 break; 480 case SIOCGLIFPHYADDR: 481 if (sc->g_src.s_addr == INADDR_ANY || 482 sc->g_dst.s_addr == INADDR_ANY) { 483 error = EADDRNOTAVAIL; 484 break; 485 } 486 memset(&si, 0, sizeof(si)); 487 si.sin_family = AF_INET; 488 si.sin_len = sizeof(struct sockaddr_in); 489 si.sin_addr.s_addr = sc->g_src.s_addr; 490 memcpy(&lifr->addr, &si, sizeof(si)); 491 si.sin_addr.s_addr = sc->g_dst.s_addr; 492 memcpy(&lifr->dstaddr, &si, sizeof(si)); 493 break; 494 default: 495 error = EINVAL; 496 break; 497 } 498 499 splx(s); 500 return (error); 501 } 502 503 /* 504 * computes a route to our destination that is not the one 505 * which would be taken by ip_output(), as this one will loop back to 506 * us. If the interface is p2p as a--->b, then a routing entry exists 507 * If we now send a packet to b (e.g. ping b), this will come down here 508 * gets src=a, dst=b tacked on and would from ip_output() sent back to 509 * if_gre. 510 * Goal here is to compute a route to b that is less specific than 511 * a-->b. We know that this one exists as in normal operation we have 512 * at least a default route which matches. 513 */ 514 int 515 gre_compute_route(struct gre_softc *sc) 516 { 517 struct route *ro; 518 u_int32_t a, b, c; 519 520 ro = &sc->route; 521 522 memset(ro, 0, sizeof(struct route)); 523 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 524 ro->ro_dst.sa_family = AF_INET; 525 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 526 527 /* 528 * toggle last bit, so our interface is not found, but a less 529 * specific route. I'd rather like to specify a shorter mask, 530 * but this is not possible. Should work though. XXX 531 * there is a simpler way ... 532 */ 533 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 534 a = ntohl(sc->g_dst.s_addr); 535 b = a & 0x01; 536 c = a & 0xfffffffe; 537 b = b ^ 0x01; 538 a = b | c; 539 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 540 = htonl(a); 541 } 542 543 #ifdef DIAGNOSTIC 544 printf("%s: searching for a route to %s", sc->sc_if.if_xname, 545 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 546 #endif 547 548 rtalloc(ro); 549 550 /* 551 * check if this returned a route at all and this route is no 552 * recursion to ourself 553 */ 554 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 555 #ifdef DIAGNOSTIC 556 if (ro->ro_rt == NULL) 557 printf(" - no route found!\n"); 558 else 559 printf(" - route loops back to ourself!\n"); 560 #endif 561 return EADDRNOTAVAIL; 562 } 563 564 /* 565 * now change it back - else ip_output will just drop 566 * the route and search one to this interface ... 567 */ 568 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 569 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 570 571 #ifdef DIAGNOSTIC 572 printf(", choosing %s with gateway %s", ro->ro_rt->rt_ifp->if_xname, 573 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 574 printf("\n"); 575 #endif 576 577 return 0; 578 } 579 580 /* 581 * do a checksum of a buffer - much like in_cksum, which operates on 582 * mbufs. 583 */ 584 u_int16_t 585 gre_in_cksum(u_int16_t *p, u_int len) 586 { 587 u_int32_t sum = 0; 588 int nwords = len >> 1; 589 590 while (nwords-- != 0) 591 sum += *p++; 592 593 if (len & 1) { 594 union { 595 u_short w; 596 u_char c[2]; 597 } u; 598 u.c[0] = *(u_char *)p; 599 u.c[1] = 0; 600 sum += u.w; 601 } 602 603 /* end-around-carry */ 604 sum = (sum >> 16) + (sum & 0xffff); 605 sum += (sum >> 16); 606 return (~sum); 607 } 608
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