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 1.13 2005/06/03 18:20:37 swildner 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(ifc, unit) 162 struct if_clone *ifc; 163 int unit; 164 { 165 struct gre_softc *sc; 166 167 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK); 168 memset(sc, 0, sizeof(struct gre_softc)); 169 170 sc->sc_if.if_softc = sc; 171 if_initname(&(sc->sc_if), GRENAME, unit); 172 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 173 sc->sc_if.if_type = IFT_OTHER; 174 sc->sc_if.if_addrlen = 0; 175 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 176 sc->sc_if.if_mtu = GREMTU; 177 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 178 sc->sc_if.if_output = gre_output; 179 sc->sc_if.if_ioctl = gre_ioctl; 180 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 181 sc->g_proto = IPPROTO_GRE; 182 sc->sc_if.if_flags |= IFF_LINK0; 183 sc->encap = NULL; 184 sc->called = 0; 185 if_attach(&sc->sc_if); 186 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 187 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 188 return (0); 189 } 190 191 static void 192 gre_clone_destroy(ifp) 193 struct ifnet *ifp; 194 { 195 struct gre_softc *sc = ifp->if_softc; 196 197 #ifdef INET 198 if (sc->encap != NULL) 199 encap_detach(sc->encap); 200 #endif 201 LIST_REMOVE(sc, sc_list); 202 bpfdetach(ifp); 203 if_detach(ifp); 204 205 free(sc, M_GRE); 206 } 207 208 /* 209 * The output routine. Takes a packet and encapsulates it in the protocol 210 * given by sc->g_proto. See also RFC 1701 and RFC 2004 211 */ 212 static int 213 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 214 struct rtentry *rt) 215 { 216 int error = 0; 217 struct gre_softc *sc = ifp->if_softc; 218 struct greip *gh; 219 struct ip *ip; 220 u_char osrc; 221 u_short etype = 0; 222 struct mobile_h mob_h; 223 224 /* 225 * gre may cause infinite recursion calls when misconfigured. 226 * We'll prevent this by introducing upper limit. 227 */ 228 if (++(sc->called) > max_gre_nesting) { 229 printf("%s: gre_output: recursively called too many " 230 "times(%d)\n", if_name(&sc->sc_if), sc->called); 231 m_freem(m); 232 error = EIO; /* is there better errno? */ 233 goto end; 234 } 235 236 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 237 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 238 m_freem(m); 239 error = ENETDOWN; 240 goto end; 241 } 242 243 gh = NULL; 244 ip = NULL; 245 osrc = 0; 246 247 if (ifp->if_bpf) { 248 uint32_t af = dst->sa_family; 249 250 bpf_ptap(ifp->if_bpf, m, &af, sizeof(af)); 251 } 252 253 m->m_flags &= ~(M_BCAST|M_MCAST); 254 255 if (sc->g_proto == IPPROTO_MOBILE) { 256 if (dst->sa_family == AF_INET) { 257 struct mbuf *m0; 258 int msiz; 259 260 ip = mtod(m, struct ip *); 261 262 /* 263 * RFC2004 specifies that fragmented diagrams shouldn't 264 * be encapsulated. 265 */ 266 if ((ip->ip_off & IP_MF) != 0) { 267 IF_DROP(&ifp->if_snd); 268 m_freem(m); 269 error = EINVAL; /* is there better errno? */ 270 goto end; 271 } 272 memset(&mob_h, 0, MOB_H_SIZ_L); 273 mob_h.proto = (ip->ip_p) << 8; 274 mob_h.odst = ip->ip_dst.s_addr; 275 ip->ip_dst.s_addr = sc->g_dst.s_addr; 276 277 /* 278 * If the packet comes from our host, we only change 279 * the destination address in the IP header. 280 * Else we also need to save and change the source 281 */ 282 if (in_hosteq(ip->ip_src, sc->g_src)) { 283 msiz = MOB_H_SIZ_S; 284 } else { 285 mob_h.proto |= MOB_H_SBIT; 286 mob_h.osrc = ip->ip_src.s_addr; 287 ip->ip_src.s_addr = sc->g_src.s_addr; 288 msiz = MOB_H_SIZ_L; 289 } 290 mob_h.proto = htons(mob_h.proto); 291 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 292 293 if ((m->m_data - msiz) < m->m_pktdat) { 294 /* need new mbuf */ 295 MGETHDR(m0, MB_DONTWAIT, MT_HEADER); 296 if (m0 == NULL) { 297 IF_DROP(&ifp->if_snd); 298 m_freem(m); 299 error = ENOBUFS; 300 goto end; 301 } 302 m0->m_next = m; 303 m->m_data += sizeof(struct ip); 304 m->m_len -= sizeof(struct ip); 305 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 306 m0->m_len = msiz + sizeof(struct ip); 307 m0->m_data += max_linkhdr; 308 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 309 sizeof(struct ip)); 310 m = m0; 311 } else { /* we have some space left in the old one */ 312 m->m_data -= msiz; 313 m->m_len += msiz; 314 m->m_pkthdr.len += msiz; 315 bcopy(ip, mtod(m, caddr_t), 316 sizeof(struct ip)); 317 } 318 ip = mtod(m, struct ip *); 319 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 320 ip->ip_len = ntohs(ip->ip_len) + msiz; 321 } else { /* AF_INET */ 322 IF_DROP(&ifp->if_snd); 323 m_freem(m); 324 error = EINVAL; 325 goto end; 326 } 327 } else if (sc->g_proto == IPPROTO_GRE) { 328 switch (dst->sa_family) { 329 case AF_INET: 330 ip = mtod(m, struct ip *); 331 etype = ETHERTYPE_IP; 332 break; 333 #ifdef NETATALK 334 case AF_APPLETALK: 335 etype = ETHERTYPE_ATALK; 336 break; 337 #endif 338 #ifdef NS 339 case AF_NS: 340 etype = ETHERTYPE_NS; 341 break; 342 #endif 343 default: 344 IF_DROP(&ifp->if_snd); 345 m_freem(m); 346 error = EAFNOSUPPORT; 347 goto end; 348 } 349 M_PREPEND(m, sizeof(struct greip), MB_DONTWAIT); 350 } else { 351 IF_DROP(&ifp->if_snd); 352 m_freem(m); 353 error = EINVAL; 354 goto end; 355 } 356 357 if (m == NULL) { /* impossible */ 358 IF_DROP(&ifp->if_snd); 359 error = ENOBUFS; 360 goto end; 361 } 362 363 gh = mtod(m, struct greip *); 364 if (sc->g_proto == IPPROTO_GRE) { 365 /* we don't have any GRE flags for now */ 366 367 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 368 gh->gi_ptype = htons(etype); 369 } 370 371 gh->gi_pr = sc->g_proto; 372 if (sc->g_proto != IPPROTO_MOBILE) { 373 gh->gi_src = sc->g_src; 374 gh->gi_dst = sc->g_dst; 375 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 376 ((struct ip*)gh)->ip_ttl = GRE_TTL; 377 ((struct ip*)gh)->ip_tos = ip->ip_tos; 378 ((struct ip*)gh)->ip_id = ip->ip_id; 379 gh->gi_len = m->m_pkthdr.len; 380 } 381 382 ifp->if_opackets++; 383 ifp->if_obytes += m->m_pkthdr.len; 384 /* send it off */ 385 error = ip_output(m, NULL, &sc->route, 0, NULL, NULL); 386 end: 387 sc->called = 0; 388 if (error) 389 ifp->if_oerrors++; 390 return (error); 391 } 392 393 static int 394 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr) 395 { 396 struct ifreq *ifr = (struct ifreq *)data; 397 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 398 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 399 struct gre_softc *sc = ifp->if_softc; 400 struct sockaddr_in si; 401 struct sockaddr *sa = NULL; 402 int error; 403 struct sockaddr_in sp, sm, dp, dm; 404 405 error = 0; 406 407 crit_enter(); 408 switch (cmd) { 409 case SIOCSIFADDR: 410 ifp->if_flags |= IFF_UP; 411 break; 412 case SIOCSIFDSTADDR: 413 break; 414 case SIOCSIFFLAGS: 415 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 416 break; 417 if ((ifr->ifr_flags & IFF_LINK0) != 0) 418 sc->g_proto = IPPROTO_GRE; 419 else 420 sc->g_proto = IPPROTO_MOBILE; 421 goto recompute; 422 case SIOCSIFMTU: 423 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 424 break; 425 if (ifr->ifr_mtu < 576) { 426 error = EINVAL; 427 break; 428 } 429 ifp->if_mtu = ifr->ifr_mtu; 430 break; 431 case SIOCGIFMTU: 432 ifr->ifr_mtu = sc->sc_if.if_mtu; 433 break; 434 case SIOCADDMULTI: 435 case SIOCDELMULTI: 436 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 437 break; 438 if (ifr == 0) { 439 error = EAFNOSUPPORT; 440 break; 441 } 442 switch (ifr->ifr_addr.sa_family) { 443 #ifdef INET 444 case AF_INET: 445 break; 446 #endif 447 default: 448 error = EAFNOSUPPORT; 449 break; 450 } 451 break; 452 case GRESPROTO: 453 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 454 break; 455 sc->g_proto = ifr->ifr_flags; 456 switch (sc->g_proto) { 457 case IPPROTO_GRE: 458 ifp->if_flags |= IFF_LINK0; 459 break; 460 case IPPROTO_MOBILE: 461 ifp->if_flags &= ~IFF_LINK0; 462 break; 463 default: 464 error = EPROTONOSUPPORT; 465 break; 466 } 467 goto recompute; 468 case GREGPROTO: 469 ifr->ifr_flags = sc->g_proto; 470 break; 471 case GRESADDRS: 472 case GRESADDRD: 473 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 474 break; 475 /* 476 * set tunnel endpoints, compute a less specific route 477 * to the remote end and mark if as up 478 */ 479 sa = &ifr->ifr_addr; 480 if (cmd == GRESADDRS) 481 sc->g_src = (satosin(sa))->sin_addr; 482 if (cmd == GRESADDRD) 483 sc->g_dst = (satosin(sa))->sin_addr; 484 recompute: 485 #ifdef INET 486 if (sc->encap != NULL) { 487 encap_detach(sc->encap); 488 sc->encap = NULL; 489 } 490 #endif 491 if ((sc->g_src.s_addr != INADDR_ANY) && 492 (sc->g_dst.s_addr != INADDR_ANY)) { 493 bzero(&sp, sizeof(sp)); 494 bzero(&sm, sizeof(sm)); 495 bzero(&dp, sizeof(dp)); 496 bzero(&dm, sizeof(dm)); 497 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 498 sizeof(struct sockaddr_in); 499 sp.sin_family = sm.sin_family = dp.sin_family = 500 dm.sin_family = AF_INET; 501 sp.sin_addr = sc->g_src; 502 dp.sin_addr = sc->g_dst; 503 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 504 INADDR_BROADCAST; 505 #ifdef INET 506 sc->encap = encap_attach(AF_INET, sc->g_proto, 507 sintosa(&sp), sintosa(&sm), sintosa(&dp), 508 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 509 &in_gre_protosw : &in_mobile_protosw, sc); 510 if (sc->encap == NULL) 511 printf("%s: unable to attach encap\n", 512 if_name(&sc->sc_if)); 513 #endif 514 if (sc->route.ro_rt != 0) /* free old route */ 515 RTFREE(sc->route.ro_rt); 516 if (gre_compute_route(sc) == 0) 517 ifp->if_flags |= IFF_RUNNING; 518 else 519 ifp->if_flags &= ~IFF_RUNNING; 520 } 521 break; 522 case GREGADDRS: 523 memset(&si, 0, sizeof(si)); 524 si.sin_family = AF_INET; 525 si.sin_len = sizeof(struct sockaddr_in); 526 si.sin_addr.s_addr = sc->g_src.s_addr; 527 sa = sintosa(&si); 528 ifr->ifr_addr = *sa; 529 break; 530 case GREGADDRD: 531 memset(&si, 0, sizeof(si)); 532 si.sin_family = AF_INET; 533 si.sin_len = sizeof(struct sockaddr_in); 534 si.sin_addr.s_addr = sc->g_dst.s_addr; 535 sa = sintosa(&si); 536 ifr->ifr_addr = *sa; 537 break; 538 case SIOCSIFPHYADDR: 539 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 540 break; 541 if (aifr->ifra_addr.sin_family != AF_INET || 542 aifr->ifra_dstaddr.sin_family != AF_INET) { 543 error = EAFNOSUPPORT; 544 break; 545 } 546 if (aifr->ifra_addr.sin_len != sizeof(si) || 547 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 548 error = EINVAL; 549 break; 550 } 551 sc->g_src = aifr->ifra_addr.sin_addr; 552 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 553 goto recompute; 554 case SIOCSLIFPHYADDR: 555 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 556 break; 557 if (lifr->addr.ss_family != AF_INET || 558 lifr->dstaddr.ss_family != AF_INET) { 559 error = EAFNOSUPPORT; 560 break; 561 } 562 if (lifr->addr.ss_len != sizeof(si) || 563 lifr->dstaddr.ss_len != sizeof(si)) { 564 error = EINVAL; 565 break; 566 } 567 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 568 sc->g_dst = 569 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 570 goto recompute; 571 case SIOCDIFPHYADDR: 572 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 573 break; 574 sc->g_src.s_addr = INADDR_ANY; 575 sc->g_dst.s_addr = INADDR_ANY; 576 goto recompute; 577 case SIOCGLIFPHYADDR: 578 if (sc->g_src.s_addr == INADDR_ANY || 579 sc->g_dst.s_addr == INADDR_ANY) { 580 error = EADDRNOTAVAIL; 581 break; 582 } 583 memset(&si, 0, sizeof(si)); 584 si.sin_family = AF_INET; 585 si.sin_len = sizeof(struct sockaddr_in); 586 si.sin_addr.s_addr = sc->g_src.s_addr; 587 memcpy(&lifr->addr, &si, sizeof(si)); 588 si.sin_addr.s_addr = sc->g_dst.s_addr; 589 memcpy(&lifr->dstaddr, &si, sizeof(si)); 590 break; 591 case SIOCGIFPSRCADDR: 592 if (sc->g_src.s_addr == INADDR_ANY) { 593 error = EADDRNOTAVAIL; 594 break; 595 } 596 memset(&si, 0, sizeof(si)); 597 si.sin_family = AF_INET; 598 si.sin_len = sizeof(struct sockaddr_in); 599 si.sin_addr.s_addr = sc->g_src.s_addr; 600 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 601 break; 602 case SIOCGIFPDSTADDR: 603 if (sc->g_dst.s_addr == INADDR_ANY) { 604 error = EADDRNOTAVAIL; 605 break; 606 } 607 memset(&si, 0, sizeof(si)); 608 si.sin_family = AF_INET; 609 si.sin_len = sizeof(struct sockaddr_in); 610 si.sin_addr.s_addr = sc->g_dst.s_addr; 611 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 612 break; 613 default: 614 error = EINVAL; 615 break; 616 } 617 618 crit_exit(); 619 return (error); 620 } 621 622 /* 623 * computes a route to our destination that is not the one 624 * which would be taken by ip_output(), as this one will loop back to 625 * us. If the interface is p2p as a--->b, then a routing entry exists 626 * If we now send a packet to b (e.g. ping b), this will come down here 627 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 628 * if_gre. 629 * Goal here is to compute a route to b that is less specific than 630 * a-->b. We know that this one exists as in normal operation we have 631 * at least a default route which matches. 632 */ 633 static int 634 gre_compute_route(struct gre_softc *sc) 635 { 636 struct route *ro; 637 u_int32_t a, b, c; 638 639 ro = &sc->route; 640 641 memset(ro, 0, sizeof(struct route)); 642 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 643 ro->ro_dst.sa_family = AF_INET; 644 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 645 646 /* 647 * toggle last bit, so our interface is not found, but a less 648 * specific route. I'd rather like to specify a shorter mask, 649 * but this is not possible. Should work though. XXX 650 * there is a simpler way ... 651 */ 652 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 653 a = ntohl(sc->g_dst.s_addr); 654 b = a & 0x01; 655 c = a & 0xfffffffe; 656 b = b ^ 0x01; 657 a = b | c; 658 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 659 = htonl(a); 660 } 661 662 #ifdef DIAGNOSTIC 663 printf("%s: searching a route to %s", if_name(&sc->sc_if), 664 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 665 #endif 666 667 rtalloc(ro); 668 669 /* 670 * check if this returned a route at all and this route is no 671 * recursion to ourself 672 */ 673 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 674 #ifdef DIAGNOSTIC 675 if (ro->ro_rt == NULL) 676 printf(" - no route found!\n"); 677 else 678 printf(" - route loops back to ourself!\n"); 679 #endif 680 return EADDRNOTAVAIL; 681 } 682 683 /* 684 * now change it back - else ip_output will just drop 685 * the route and search one to this interface ... 686 */ 687 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 688 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 689 690 #ifdef DIAGNOSTIC 691 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 692 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 693 printf("\n"); 694 #endif 695 696 return 0; 697 } 698 699 /* 700 * do a checksum of a buffer - much like in_cksum, which operates on 701 * mbufs. 702 */ 703 u_short 704 gre_in_cksum(u_short *p, u_int len) 705 { 706 u_int sum = 0; 707 int nwords = len >> 1; 708 709 while (nwords-- != 0) 710 sum += *p++; 711 712 if (len & 1) { 713 union { 714 u_short w; 715 u_char c[2]; 716 } u; 717 u.c[0] = *(u_char *)p; 718 u.c[1] = 0; 719 sum += u.w; 720 } 721 722 /* end-around-carry */ 723 sum = (sum >> 16) + (sum & 0xffff); 724 sum += (sum >> 16); 725 return (~sum); 726 } 727 728 static int 729 gremodevent(module_t mod, int type, void *data) 730 { 731 732 switch (type) { 733 case MOD_LOAD: 734 greattach(); 735 break; 736 case MOD_UNLOAD: 737 if_clone_detach(&gre_cloner); 738 739 while (!LIST_EMPTY(&gre_softc_list)) 740 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 741 742 break; 743 } 744 return 0; 745 } 746 747 static moduledata_t gre_mod = { 748 "if_gre", 749 gremodevent, 750 0 751 }; 752 753 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 754 MODULE_VERSION(if_gre, 1); 755