1 /* $NetBSD: if_gre.c,v 1.42 2002/08/14 00:23:27 itojun Exp $ */ 2 /* $FreeBSD: src/sys/net/if_gre.c,v 1.9.2.3 2003/01/23 21:06:44 sam Exp $ */ 3 /* $DragonFly: src/sys/net/gre/if_gre.c,v 1.16 2006/05/11 00:52:03 hsu Exp $ */ 4 5 /* 6 * Copyright (c) 1998 The NetBSD Foundation, Inc. 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to The NetBSD Foundation 10 * by Heiko W.Rupp <hwr@pilhuhn.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 "opt_atalk.h" 51 #include "opt_inet.h" 52 #include "opt_ns.h" 53 54 #include <sys/param.h> 55 #include <sys/kernel.h> 56 #include <sys/malloc.h> 57 #include <sys/mbuf.h> 58 #include <sys/proc.h> 59 #include <sys/protosw.h> 60 #include <machine/bus.h> 61 #include <sys/socket.h> 62 #include <sys/sockio.h> 63 #include <sys/sysctl.h> 64 #include <sys/systm.h> 65 #include <sys/thread2.h> 66 67 #include <net/ethernet.h> 68 #include <net/if.h> 69 #include <net/if_types.h> 70 #include <net/route.h> 71 72 #ifdef INET 73 #include <netinet/in.h> 74 #include <netinet/in_systm.h> 75 #include <netinet/in_var.h> 76 #include <netinet/ip.h> 77 #include <netinet/ip_gre.h> 78 #include <netinet/ip_var.h> 79 #include <netinet/ip_encap.h> 80 #else 81 #error "Huh? if_gre without inet?" 82 #endif 83 84 #include <net/bpf.h> 85 86 #include <net/net_osdep.h> 87 #include "if_gre.h" 88 89 /* 90 * It is not easy to calculate the right value for a GRE MTU. 91 * We leave this task to the admin and use the same default that 92 * other vendors use. 93 */ 94 #define GREMTU 1476 95 96 #define GRENAME "gre" 97 98 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation"); 99 100 struct gre_softc_head gre_softc_list; 101 102 static int gre_clone_create(struct if_clone *, int); 103 static void gre_clone_destroy(struct ifnet *); 104 static int gre_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *); 105 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 106 struct rtentry *rt); 107 108 static struct if_clone gre_cloner = IF_CLONE_INITIALIZER("gre", 109 gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT); 110 111 static int gre_compute_route(struct gre_softc *sc); 112 113 static void greattach(void); 114 115 #ifdef INET 116 extern struct domain inetdomain; 117 static const struct protosw in_gre_protosw = 118 { SOCK_RAW, &inetdomain, IPPROTO_GRE, PR_ATOMIC|PR_ADDR, 119 gre_input, rip_output, rip_ctlinput, rip_ctloutput, 120 cpu0_soport, 121 0, 0, 0, 0, 122 &rip_usrreqs 123 }; 124 static const struct protosw in_mobile_protosw = 125 { SOCK_RAW, &inetdomain, IPPROTO_MOBILE, PR_ATOMIC|PR_ADDR, 126 gre_mobile_input, rip_output, rip_ctlinput, rip_ctloutput, 127 cpu0_soport, 128 0, 0, 0, 0, 129 &rip_usrreqs 130 }; 131 #endif 132 133 SYSCTL_DECL(_net_link); 134 SYSCTL_NODE(_net_link, IFT_OTHER, gre, CTLFLAG_RW, 0, 135 "Generic Routing Encapsulation"); 136 #ifndef MAX_GRE_NEST 137 /* 138 * This macro controls the default upper limitation on nesting of gre tunnels. 139 * Since, setting a large value to this macro with a careless configuration 140 * may introduce system crash, we don't allow any nestings by default. 141 * If you need to configure nested gre tunnels, you can define this macro 142 * in your kernel configuration file. However, if you do so, please be 143 * careful to configure the tunnels so that it won't make a loop. 144 */ 145 #define MAX_GRE_NEST 1 146 #endif 147 static int max_gre_nesting = MAX_GRE_NEST; 148 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW, 149 &max_gre_nesting, 0, "Max nested tunnels"); 150 151 /* ARGSUSED */ 152 static void 153 greattach(void) 154 { 155 156 LIST_INIT(&gre_softc_list); 157 if_clone_attach(&gre_cloner); 158 } 159 160 static int 161 gre_clone_create(struct if_clone *ifc, int unit) 162 { 163 struct gre_softc *sc; 164 165 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK); 166 memset(sc, 0, sizeof(struct gre_softc)); 167 168 sc->sc_if.if_softc = sc; 169 if_initname(&(sc->sc_if), GRENAME, unit); 170 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 171 sc->sc_if.if_type = IFT_OTHER; 172 sc->sc_if.if_addrlen = 0; 173 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 174 sc->sc_if.if_mtu = GREMTU; 175 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 176 sc->sc_if.if_output = gre_output; 177 sc->sc_if.if_ioctl = gre_ioctl; 178 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 179 sc->g_proto = IPPROTO_GRE; 180 sc->sc_if.if_flags |= IFF_LINK0; 181 sc->encap = NULL; 182 sc->called = 0; 183 if_attach(&sc->sc_if, NULL); 184 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 185 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 186 return (0); 187 } 188 189 static void 190 gre_clone_destroy(struct ifnet *ifp) 191 { 192 struct gre_softc *sc = ifp->if_softc; 193 194 #ifdef INET 195 if (sc->encap != NULL) 196 encap_detach(sc->encap); 197 #endif 198 LIST_REMOVE(sc, sc_list); 199 bpfdetach(ifp); 200 if_detach(ifp); 201 202 free(sc, M_GRE); 203 } 204 205 /* 206 * The output routine. Takes a packet and encapsulates it in the protocol 207 * given by sc->g_proto. See also RFC 1701 and RFC 2004 208 */ 209 static int 210 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 211 struct rtentry *rt) 212 { 213 int error = 0; 214 struct gre_softc *sc = ifp->if_softc; 215 struct greip *gh; 216 struct ip *ip; 217 u_char osrc; 218 u_short etype = 0; 219 struct mobile_h mob_h; 220 221 /* 222 * gre may cause infinite recursion calls when misconfigured. 223 * We'll prevent this by introducing upper limit. 224 */ 225 if (++(sc->called) > max_gre_nesting) { 226 printf("%s: gre_output: recursively called too many " 227 "times(%d)\n", if_name(&sc->sc_if), sc->called); 228 m_freem(m); 229 error = EIO; /* is there better errno? */ 230 goto end; 231 } 232 233 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 234 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 235 m_freem(m); 236 error = ENETDOWN; 237 goto end; 238 } 239 240 gh = NULL; 241 ip = NULL; 242 osrc = 0; 243 244 if (ifp->if_bpf) { 245 uint32_t af = dst->sa_family; 246 247 bpf_ptap(ifp->if_bpf, m, &af, sizeof(af)); 248 } 249 250 m->m_flags &= ~(M_BCAST|M_MCAST); 251 252 if (sc->g_proto == IPPROTO_MOBILE) { 253 if (dst->sa_family == AF_INET) { 254 struct mbuf *m0; 255 int msiz; 256 257 ip = mtod(m, struct ip *); 258 259 /* 260 * RFC2004 specifies that fragmented datagrams shouldn't 261 * be encapsulated. 262 */ 263 if (ip->ip_off & (IP_MF | IP_OFFMASK)) { 264 IF_DROP(&ifp->if_snd); 265 m_freem(m); 266 error = EINVAL; /* is there better errno? */ 267 goto end; 268 } 269 memset(&mob_h, 0, MOB_H_SIZ_L); 270 mob_h.proto = (ip->ip_p) << 8; 271 mob_h.odst = ip->ip_dst.s_addr; 272 ip->ip_dst.s_addr = sc->g_dst.s_addr; 273 274 /* 275 * If the packet comes from our host, we only change 276 * the destination address in the IP header. 277 * Else we also need to save and change the source 278 */ 279 if (in_hosteq(ip->ip_src, sc->g_src)) { 280 msiz = MOB_H_SIZ_S; 281 } else { 282 mob_h.proto |= MOB_H_SBIT; 283 mob_h.osrc = ip->ip_src.s_addr; 284 ip->ip_src.s_addr = sc->g_src.s_addr; 285 msiz = MOB_H_SIZ_L; 286 } 287 mob_h.proto = htons(mob_h.proto); 288 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 289 290 if ((m->m_data - msiz) < m->m_pktdat) { 291 /* need new mbuf */ 292 MGETHDR(m0, MB_DONTWAIT, MT_HEADER); 293 if (m0 == NULL) { 294 IF_DROP(&ifp->if_snd); 295 m_freem(m); 296 error = ENOBUFS; 297 goto end; 298 } 299 m0->m_next = m; 300 m->m_data += sizeof(struct ip); 301 m->m_len -= sizeof(struct ip); 302 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 303 m0->m_len = msiz + sizeof(struct ip); 304 m0->m_data += max_linkhdr; 305 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 306 sizeof(struct ip)); 307 m = m0; 308 } else { /* we have some space left in the old one */ 309 m->m_data -= msiz; 310 m->m_len += msiz; 311 m->m_pkthdr.len += msiz; 312 bcopy(ip, mtod(m, caddr_t), 313 sizeof(struct ip)); 314 } 315 ip = mtod(m, struct ip *); 316 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 317 ip->ip_len = ntohs(ip->ip_len) + msiz; 318 } else { /* AF_INET */ 319 IF_DROP(&ifp->if_snd); 320 m_freem(m); 321 error = EINVAL; 322 goto end; 323 } 324 } else if (sc->g_proto == IPPROTO_GRE) { 325 switch (dst->sa_family) { 326 case AF_INET: 327 ip = mtod(m, struct ip *); 328 etype = ETHERTYPE_IP; 329 break; 330 #ifdef NETATALK 331 case AF_APPLETALK: 332 etype = ETHERTYPE_ATALK; 333 break; 334 #endif 335 #ifdef NS 336 case AF_NS: 337 etype = ETHERTYPE_NS; 338 break; 339 #endif 340 default: 341 IF_DROP(&ifp->if_snd); 342 m_freem(m); 343 error = EAFNOSUPPORT; 344 goto end; 345 } 346 M_PREPEND(m, sizeof(struct greip), MB_DONTWAIT); 347 } else { 348 IF_DROP(&ifp->if_snd); 349 m_freem(m); 350 error = EINVAL; 351 goto end; 352 } 353 354 if (m == NULL) { /* impossible */ 355 IF_DROP(&ifp->if_snd); 356 error = ENOBUFS; 357 goto end; 358 } 359 360 gh = mtod(m, struct greip *); 361 if (sc->g_proto == IPPROTO_GRE) { 362 /* we don't have any GRE flags for now */ 363 364 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 365 gh->gi_ptype = htons(etype); 366 } 367 368 gh->gi_pr = sc->g_proto; 369 if (sc->g_proto != IPPROTO_MOBILE) { 370 gh->gi_src = sc->g_src; 371 gh->gi_dst = sc->g_dst; 372 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 373 ((struct ip*)gh)->ip_ttl = GRE_TTL; 374 ((struct ip*)gh)->ip_tos = ip->ip_tos; 375 ((struct ip*)gh)->ip_id = ip->ip_id; 376 gh->gi_len = m->m_pkthdr.len; 377 } 378 379 ifp->if_opackets++; 380 ifp->if_obytes += m->m_pkthdr.len; 381 /* send it off */ 382 error = ip_output(m, NULL, &sc->route, 0, NULL, NULL); 383 end: 384 sc->called = 0; 385 if (error) 386 ifp->if_oerrors++; 387 return (error); 388 } 389 390 static int 391 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr) 392 { 393 struct ifreq *ifr = (struct ifreq *)data; 394 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 395 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 396 struct gre_softc *sc = ifp->if_softc; 397 struct sockaddr_in si; 398 struct sockaddr *sa = NULL; 399 int error; 400 struct sockaddr_in sp, sm, dp, dm; 401 402 error = 0; 403 404 crit_enter(); 405 switch (cmd) { 406 case SIOCSIFADDR: 407 ifp->if_flags |= IFF_UP; 408 break; 409 case SIOCSIFDSTADDR: 410 break; 411 case SIOCSIFFLAGS: 412 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 413 break; 414 if ((ifr->ifr_flags & IFF_LINK0) != 0) 415 sc->g_proto = IPPROTO_GRE; 416 else 417 sc->g_proto = IPPROTO_MOBILE; 418 goto recompute; 419 case SIOCSIFMTU: 420 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 421 break; 422 if (ifr->ifr_mtu < 576) { 423 error = EINVAL; 424 break; 425 } 426 ifp->if_mtu = ifr->ifr_mtu; 427 break; 428 case SIOCGIFMTU: 429 ifr->ifr_mtu = sc->sc_if.if_mtu; 430 break; 431 case SIOCADDMULTI: 432 case SIOCDELMULTI: 433 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 434 break; 435 if (ifr == 0) { 436 error = EAFNOSUPPORT; 437 break; 438 } 439 switch (ifr->ifr_addr.sa_family) { 440 #ifdef INET 441 case AF_INET: 442 break; 443 #endif 444 default: 445 error = EAFNOSUPPORT; 446 break; 447 } 448 break; 449 case GRESPROTO: 450 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 451 break; 452 sc->g_proto = ifr->ifr_flags; 453 switch (sc->g_proto) { 454 case IPPROTO_GRE: 455 ifp->if_flags |= IFF_LINK0; 456 break; 457 case IPPROTO_MOBILE: 458 ifp->if_flags &= ~IFF_LINK0; 459 break; 460 default: 461 error = EPROTONOSUPPORT; 462 break; 463 } 464 goto recompute; 465 case GREGPROTO: 466 ifr->ifr_flags = sc->g_proto; 467 break; 468 case GRESADDRS: 469 case GRESADDRD: 470 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 471 break; 472 /* 473 * set tunnel endpoints, compute a less specific route 474 * to the remote end and mark if as up 475 */ 476 sa = &ifr->ifr_addr; 477 if (cmd == GRESADDRS) 478 sc->g_src = (satosin(sa))->sin_addr; 479 if (cmd == GRESADDRD) 480 sc->g_dst = (satosin(sa))->sin_addr; 481 recompute: 482 #ifdef INET 483 if (sc->encap != NULL) { 484 encap_detach(sc->encap); 485 sc->encap = NULL; 486 } 487 #endif 488 if ((sc->g_src.s_addr != INADDR_ANY) && 489 (sc->g_dst.s_addr != INADDR_ANY)) { 490 bzero(&sp, sizeof(sp)); 491 bzero(&sm, sizeof(sm)); 492 bzero(&dp, sizeof(dp)); 493 bzero(&dm, sizeof(dm)); 494 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 495 sizeof(struct sockaddr_in); 496 sp.sin_family = sm.sin_family = dp.sin_family = 497 dm.sin_family = AF_INET; 498 sp.sin_addr = sc->g_src; 499 dp.sin_addr = sc->g_dst; 500 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 501 INADDR_BROADCAST; 502 #ifdef INET 503 sc->encap = encap_attach(AF_INET, sc->g_proto, 504 sintosa(&sp), sintosa(&sm), sintosa(&dp), 505 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 506 &in_gre_protosw : &in_mobile_protosw, sc); 507 if (sc->encap == NULL) 508 printf("%s: unable to attach encap\n", 509 if_name(&sc->sc_if)); 510 #endif 511 if (sc->route.ro_rt != 0) /* free old route */ 512 RTFREE(sc->route.ro_rt); 513 if (gre_compute_route(sc) == 0) 514 ifp->if_flags |= IFF_RUNNING; 515 else 516 ifp->if_flags &= ~IFF_RUNNING; 517 } 518 break; 519 case GREGADDRS: 520 memset(&si, 0, sizeof(si)); 521 si.sin_family = AF_INET; 522 si.sin_len = sizeof(struct sockaddr_in); 523 si.sin_addr.s_addr = sc->g_src.s_addr; 524 sa = sintosa(&si); 525 ifr->ifr_addr = *sa; 526 break; 527 case GREGADDRD: 528 memset(&si, 0, sizeof(si)); 529 si.sin_family = AF_INET; 530 si.sin_len = sizeof(struct sockaddr_in); 531 si.sin_addr.s_addr = sc->g_dst.s_addr; 532 sa = sintosa(&si); 533 ifr->ifr_addr = *sa; 534 break; 535 case SIOCSIFPHYADDR: 536 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 537 break; 538 if (aifr->ifra_addr.sin_family != AF_INET || 539 aifr->ifra_dstaddr.sin_family != AF_INET) { 540 error = EAFNOSUPPORT; 541 break; 542 } 543 if (aifr->ifra_addr.sin_len != sizeof(si) || 544 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 545 error = EINVAL; 546 break; 547 } 548 sc->g_src = aifr->ifra_addr.sin_addr; 549 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 550 goto recompute; 551 case SIOCSLIFPHYADDR: 552 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 553 break; 554 if (lifr->addr.ss_family != AF_INET || 555 lifr->dstaddr.ss_family != AF_INET) { 556 error = EAFNOSUPPORT; 557 break; 558 } 559 if (lifr->addr.ss_len != sizeof(si) || 560 lifr->dstaddr.ss_len != sizeof(si)) { 561 error = EINVAL; 562 break; 563 } 564 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 565 sc->g_dst = 566 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 567 goto recompute; 568 case SIOCDIFPHYADDR: 569 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 570 break; 571 sc->g_src.s_addr = INADDR_ANY; 572 sc->g_dst.s_addr = INADDR_ANY; 573 goto recompute; 574 case SIOCGLIFPHYADDR: 575 if (sc->g_src.s_addr == INADDR_ANY || 576 sc->g_dst.s_addr == INADDR_ANY) { 577 error = EADDRNOTAVAIL; 578 break; 579 } 580 memset(&si, 0, sizeof(si)); 581 si.sin_family = AF_INET; 582 si.sin_len = sizeof(struct sockaddr_in); 583 si.sin_addr.s_addr = sc->g_src.s_addr; 584 memcpy(&lifr->addr, &si, sizeof(si)); 585 si.sin_addr.s_addr = sc->g_dst.s_addr; 586 memcpy(&lifr->dstaddr, &si, sizeof(si)); 587 break; 588 case SIOCGIFPSRCADDR: 589 if (sc->g_src.s_addr == INADDR_ANY) { 590 error = EADDRNOTAVAIL; 591 break; 592 } 593 memset(&si, 0, sizeof(si)); 594 si.sin_family = AF_INET; 595 si.sin_len = sizeof(struct sockaddr_in); 596 si.sin_addr.s_addr = sc->g_src.s_addr; 597 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 598 break; 599 case SIOCGIFPDSTADDR: 600 if (sc->g_dst.s_addr == INADDR_ANY) { 601 error = EADDRNOTAVAIL; 602 break; 603 } 604 memset(&si, 0, sizeof(si)); 605 si.sin_family = AF_INET; 606 si.sin_len = sizeof(struct sockaddr_in); 607 si.sin_addr.s_addr = sc->g_dst.s_addr; 608 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 609 break; 610 default: 611 error = EINVAL; 612 break; 613 } 614 615 crit_exit(); 616 return (error); 617 } 618 619 /* 620 * computes a route to our destination that is not the one 621 * which would be taken by ip_output(), as this one will loop back to 622 * us. If the interface is p2p as a--->b, then a routing entry exists 623 * If we now send a packet to b (e.g. ping b), this will come down here 624 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 625 * if_gre. 626 * Goal here is to compute a route to b that is less specific than 627 * a-->b. We know that this one exists as in normal operation we have 628 * at least a default route which matches. 629 */ 630 static int 631 gre_compute_route(struct gre_softc *sc) 632 { 633 struct route *ro; 634 u_int32_t a, b, c; 635 636 ro = &sc->route; 637 638 memset(ro, 0, sizeof(struct route)); 639 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 640 ro->ro_dst.sa_family = AF_INET; 641 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 642 643 /* 644 * toggle last bit, so our interface is not found, but a less 645 * specific route. I'd rather like to specify a shorter mask, 646 * but this is not possible. Should work though. XXX 647 * there is a simpler way ... 648 */ 649 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 650 a = ntohl(sc->g_dst.s_addr); 651 b = a & 0x01; 652 c = a & 0xfffffffe; 653 b = b ^ 0x01; 654 a = b | c; 655 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 656 = htonl(a); 657 } 658 659 #ifdef DIAGNOSTIC 660 printf("%s: searching a route to %s", if_name(&sc->sc_if), 661 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 662 #endif 663 664 rtalloc(ro); 665 666 /* 667 * check if this returned a route at all and this route is no 668 * recursion to ourself 669 */ 670 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 671 #ifdef DIAGNOSTIC 672 if (ro->ro_rt == NULL) 673 printf(" - no route found!\n"); 674 else 675 printf(" - route loops back to ourself!\n"); 676 #endif 677 return EADDRNOTAVAIL; 678 } 679 680 /* 681 * now change it back - else ip_output will just drop 682 * the route and search one to this interface ... 683 */ 684 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 685 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 686 687 #ifdef DIAGNOSTIC 688 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 689 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 690 printf("\n"); 691 #endif 692 693 return 0; 694 } 695 696 /* 697 * do a checksum of a buffer - much like in_cksum, which operates on 698 * mbufs. 699 */ 700 u_short 701 gre_in_cksum(u_short *p, u_int len) 702 { 703 u_int sum = 0; 704 int nwords = len >> 1; 705 706 while (nwords-- != 0) 707 sum += *p++; 708 709 if (len & 1) { 710 union { 711 u_short w; 712 u_char c[2]; 713 } u; 714 u.c[0] = *(u_char *)p; 715 u.c[1] = 0; 716 sum += u.w; 717 } 718 719 /* end-around-carry */ 720 sum = (sum >> 16) + (sum & 0xffff); 721 sum += (sum >> 16); 722 return (~sum); 723 } 724 725 static int 726 gremodevent(module_t mod, int type, void *data) 727 { 728 729 switch (type) { 730 case MOD_LOAD: 731 greattach(); 732 break; 733 case MOD_UNLOAD: 734 if_clone_detach(&gre_cloner); 735 736 while (!LIST_EMPTY(&gre_softc_list)) 737 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 738 739 break; 740 } 741 return 0; 742 } 743 744 static moduledata_t gre_mod = { 745 "if_gre", 746 gremodevent, 747 0 748 }; 749 750 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 751 MODULE_VERSION(if_gre, 1); 752