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 1.20 2008/01/11 11:59:41 sephe 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/bus.h> 57 #include <sys/malloc.h> 58 #include <sys/mbuf.h> 59 #include <sys/proc.h> 60 #include <sys/protosw.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 #include <net/if_clone.h> 72 73 #ifdef INET 74 #include <netinet/in.h> 75 #include <netinet/in_systm.h> 76 #include <netinet/in_var.h> 77 #include <netinet/ip.h> 78 #include <netinet/ip_gre.h> 79 #include <netinet/ip_var.h> 80 #include <netinet/ip_encap.h> 81 #else 82 #error "Huh? if_gre without inet?" 83 #endif 84 85 #include <net/bpf.h> 86 87 #include <net/net_osdep.h> 88 #include "if_gre.h" 89 90 /* 91 * It is not easy to calculate the right value for a GRE MTU. 92 * We leave this task to the admin and use the same default that 93 * other vendors use. 94 */ 95 #define GREMTU 1476 96 97 #define GRENAME "gre" 98 99 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation"); 100 101 struct gre_softc_head gre_softc_list; 102 103 static int gre_clone_create(struct if_clone *, int); 104 static void gre_clone_destroy(struct ifnet *); 105 static int gre_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *); 106 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 107 struct rtentry *rt); 108 109 static struct if_clone gre_cloner = IF_CLONE_INITIALIZER("gre", 110 gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT); 111 112 static int gre_compute_route(struct gre_softc *sc); 113 114 static void greattach(void); 115 116 #ifdef INET 117 extern struct domain inetdomain; 118 static const struct protosw in_gre_protosw = 119 { SOCK_RAW, &inetdomain, IPPROTO_GRE, PR_ATOMIC|PR_ADDR, 120 gre_input, rip_output, rip_ctlinput, rip_ctloutput, 121 cpu0_soport, 122 0, 0, 0, 0, 123 &rip_usrreqs 124 }; 125 static const struct protosw in_mobile_protosw = 126 { SOCK_RAW, &inetdomain, IPPROTO_MOBILE, PR_ATOMIC|PR_ADDR, 127 gre_mobile_input, rip_output, rip_ctlinput, rip_ctloutput, 128 cpu0_soport, 129 0, 0, 0, 0, 130 &rip_usrreqs 131 }; 132 #endif 133 134 SYSCTL_DECL(_net_link); 135 SYSCTL_NODE(_net_link, IFT_OTHER, gre, CTLFLAG_RW, 0, 136 "Generic Routing Encapsulation"); 137 #ifndef MAX_GRE_NEST 138 /* 139 * This macro controls the default upper limitation on nesting of gre tunnels. 140 * Since, setting a large value to this macro with a careless configuration 141 * may introduce system crash, we don't allow any nestings by default. 142 * If you need to configure nested gre tunnels, you can define this macro 143 * in your kernel configuration file. However, if you do so, please be 144 * careful to configure the tunnels so that it won't make a loop. 145 */ 146 #define MAX_GRE_NEST 1 147 #endif 148 static int max_gre_nesting = MAX_GRE_NEST; 149 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW, 150 &max_gre_nesting, 0, "Max nested tunnels"); 151 152 /* ARGSUSED */ 153 static void 154 greattach(void) 155 { 156 157 LIST_INIT(&gre_softc_list); 158 if_clone_attach(&gre_cloner); 159 } 160 161 static int 162 gre_clone_create(struct if_clone *ifc, int unit) 163 { 164 struct gre_softc *sc; 165 166 sc = kmalloc(sizeof(struct gre_softc), M_GRE, M_WAITOK); 167 memset(sc, 0, sizeof(struct gre_softc)); 168 169 sc->sc_if.if_softc = sc; 170 if_initname(&(sc->sc_if), GRENAME, unit); 171 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 172 sc->sc_if.if_type = IFT_OTHER; 173 sc->sc_if.if_addrlen = 0; 174 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 175 sc->sc_if.if_mtu = GREMTU; 176 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 177 sc->sc_if.if_output = gre_output; 178 sc->sc_if.if_ioctl = gre_ioctl; 179 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 180 sc->g_proto = IPPROTO_GRE; 181 sc->sc_if.if_flags |= IFF_LINK0; 182 sc->encap = NULL; 183 sc->called = 0; 184 if_attach(&sc->sc_if, NULL); 185 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 186 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 187 return (0); 188 } 189 190 static void 191 gre_clone_destroy(struct ifnet *ifp) 192 { 193 struct gre_softc *sc = ifp->if_softc; 194 195 #ifdef INET 196 if (sc->encap != NULL) 197 encap_detach(sc->encap); 198 #endif 199 LIST_REMOVE(sc, sc_list); 200 bpfdetach(ifp); 201 if_detach(ifp); 202 203 kfree(sc, M_GRE); 204 } 205 206 /* 207 * The output routine. Takes a packet and encapsulates it in the protocol 208 * given by sc->g_proto. See also RFC 1701 and RFC 2004 209 */ 210 static int 211 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 212 struct rtentry *rt) 213 { 214 int error = 0; 215 struct gre_softc *sc = ifp->if_softc; 216 struct greip *gh; 217 struct ip *ip; 218 u_char osrc; 219 u_short etype = 0; 220 struct mobile_h mob_h; 221 222 /* 223 * gre may cause infinite recursion calls when misconfigured. 224 * We'll prevent this by introducing upper limit. 225 */ 226 if (++(sc->called) > max_gre_nesting) { 227 kprintf("%s: gre_output: recursively called too many " 228 "times(%d)\n", if_name(&sc->sc_if), sc->called); 229 m_freem(m); 230 error = EIO; /* is there better errno? */ 231 goto end; 232 } 233 234 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 235 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 236 m_freem(m); 237 error = ENETDOWN; 238 goto end; 239 } 240 241 gh = NULL; 242 ip = NULL; 243 osrc = 0; 244 245 if (ifp->if_bpf) { 246 uint32_t af = dst->sa_family; 247 248 bpf_ptap(ifp->if_bpf, m, &af, sizeof(af)); 249 } 250 251 m->m_flags &= ~(M_BCAST|M_MCAST); 252 253 if (sc->g_proto == IPPROTO_MOBILE) { 254 if (dst->sa_family == AF_INET) { 255 struct mbuf *m0; 256 int msiz; 257 258 ip = mtod(m, struct ip *); 259 260 /* 261 * RFC2004 specifies that fragmented datagrams shouldn't 262 * be encapsulated. 263 */ 264 if (ip->ip_off & (IP_MF | IP_OFFMASK)) { 265 IF_DROP(&ifp->if_snd); 266 m_freem(m); 267 error = EINVAL; /* is there better errno? */ 268 goto end; 269 } 270 memset(&mob_h, 0, MOB_H_SIZ_L); 271 mob_h.proto = (ip->ip_p) << 8; 272 mob_h.odst = ip->ip_dst.s_addr; 273 ip->ip_dst.s_addr = sc->g_dst.s_addr; 274 275 /* 276 * If the packet comes from our host, we only change 277 * the destination address in the IP header. 278 * Else we also need to save and change the source 279 */ 280 if (in_hosteq(ip->ip_src, sc->g_src)) { 281 msiz = MOB_H_SIZ_S; 282 } else { 283 mob_h.proto |= MOB_H_SBIT; 284 mob_h.osrc = ip->ip_src.s_addr; 285 ip->ip_src.s_addr = sc->g_src.s_addr; 286 msiz = MOB_H_SIZ_L; 287 } 288 mob_h.proto = htons(mob_h.proto); 289 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 290 291 if ((m->m_data - msiz) < m->m_pktdat) { 292 /* need new mbuf */ 293 MGETHDR(m0, MB_DONTWAIT, MT_HEADER); 294 if (m0 == NULL) { 295 IF_DROP(&ifp->if_snd); 296 m_freem(m); 297 error = ENOBUFS; 298 goto end; 299 } 300 m0->m_next = m; 301 m->m_data += sizeof(struct ip); 302 m->m_len -= sizeof(struct ip); 303 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 304 m0->m_len = msiz + sizeof(struct ip); 305 m0->m_data += max_linkhdr; 306 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 307 sizeof(struct ip)); 308 m = m0; 309 } else { /* we have some space left in the old one */ 310 m->m_data -= msiz; 311 m->m_len += msiz; 312 m->m_pkthdr.len += msiz; 313 bcopy(ip, mtod(m, caddr_t), 314 sizeof(struct ip)); 315 } 316 ip = mtod(m, struct ip *); 317 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 318 ip->ip_len = ntohs(ip->ip_len) + msiz; 319 } else { /* AF_INET */ 320 IF_DROP(&ifp->if_snd); 321 m_freem(m); 322 error = EINVAL; 323 goto end; 324 } 325 } else if (sc->g_proto == IPPROTO_GRE) { 326 switch (dst->sa_family) { 327 case AF_INET: 328 ip = mtod(m, struct ip *); 329 etype = ETHERTYPE_IP; 330 break; 331 #ifdef NETATALK 332 case AF_APPLETALK: 333 etype = ETHERTYPE_ATALK; 334 break; 335 #endif 336 #ifdef NS 337 case AF_NS: 338 etype = ETHERTYPE_NS; 339 break; 340 #endif 341 default: 342 IF_DROP(&ifp->if_snd); 343 m_freem(m); 344 error = EAFNOSUPPORT; 345 goto end; 346 } 347 M_PREPEND(m, sizeof(struct greip), MB_DONTWAIT); 348 } else { 349 IF_DROP(&ifp->if_snd); 350 m_freem(m); 351 error = EINVAL; 352 goto end; 353 } 354 355 if (m == NULL) { /* impossible */ 356 IF_DROP(&ifp->if_snd); 357 error = ENOBUFS; 358 goto end; 359 } 360 361 gh = mtod(m, struct greip *); 362 if (sc->g_proto == IPPROTO_GRE) { 363 /* we don't have any GRE flags for now */ 364 365 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 366 gh->gi_ptype = htons(etype); 367 } 368 369 gh->gi_pr = sc->g_proto; 370 if (sc->g_proto != IPPROTO_MOBILE) { 371 gh->gi_src = sc->g_src; 372 gh->gi_dst = sc->g_dst; 373 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 374 ((struct ip*)gh)->ip_ttl = GRE_TTL; 375 ((struct ip*)gh)->ip_tos = ip->ip_tos; 376 ((struct ip*)gh)->ip_id = ip->ip_id; 377 gh->gi_len = m->m_pkthdr.len; 378 } 379 380 ifp->if_opackets++; 381 ifp->if_obytes += m->m_pkthdr.len; 382 /* send it off */ 383 error = ip_output(m, NULL, &sc->route, 0, NULL, NULL); 384 end: 385 sc->called = 0; 386 if (error) 387 ifp->if_oerrors++; 388 return (error); 389 } 390 391 static int 392 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr) 393 { 394 struct ifreq *ifr = (struct ifreq *)data; 395 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 396 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 397 struct gre_softc *sc = ifp->if_softc; 398 struct sockaddr_in si; 399 struct sockaddr *sa = NULL; 400 int error; 401 struct sockaddr_in sp, sm, dp, dm; 402 403 error = 0; 404 405 crit_enter(); 406 switch (cmd) { 407 case SIOCSIFADDR: 408 ifp->if_flags |= IFF_UP; 409 break; 410 case SIOCSIFDSTADDR: 411 break; 412 case SIOCSIFFLAGS: 413 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 414 break; 415 if ((ifr->ifr_flags & IFF_LINK0) != 0) 416 sc->g_proto = IPPROTO_GRE; 417 else 418 sc->g_proto = IPPROTO_MOBILE; 419 goto recompute; 420 case SIOCSIFMTU: 421 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 422 break; 423 if (ifr->ifr_mtu < 576) { 424 error = EINVAL; 425 break; 426 } 427 ifp->if_mtu = ifr->ifr_mtu; 428 break; 429 case SIOCGIFMTU: 430 ifr->ifr_mtu = sc->sc_if.if_mtu; 431 break; 432 case SIOCADDMULTI: 433 case SIOCDELMULTI: 434 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 435 break; 436 if (ifr == 0) { 437 error = EAFNOSUPPORT; 438 break; 439 } 440 switch (ifr->ifr_addr.sa_family) { 441 #ifdef INET 442 case AF_INET: 443 break; 444 #endif 445 default: 446 error = EAFNOSUPPORT; 447 break; 448 } 449 break; 450 case GRESPROTO: 451 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 452 break; 453 sc->g_proto = ifr->ifr_flags; 454 switch (sc->g_proto) { 455 case IPPROTO_GRE: 456 ifp->if_flags |= IFF_LINK0; 457 break; 458 case IPPROTO_MOBILE: 459 ifp->if_flags &= ~IFF_LINK0; 460 break; 461 default: 462 error = EPROTONOSUPPORT; 463 break; 464 } 465 goto recompute; 466 case GREGPROTO: 467 ifr->ifr_flags = sc->g_proto; 468 break; 469 case GRESADDRS: 470 case GRESADDRD: 471 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 472 break; 473 /* 474 * set tunnel endpoints, compute a less specific route 475 * to the remote end and mark if as up 476 */ 477 sa = &ifr->ifr_addr; 478 if (cmd == GRESADDRS) 479 sc->g_src = (satosin(sa))->sin_addr; 480 if (cmd == GRESADDRD) 481 sc->g_dst = (satosin(sa))->sin_addr; 482 recompute: 483 #ifdef INET 484 if (sc->encap != NULL) { 485 encap_detach(sc->encap); 486 sc->encap = NULL; 487 } 488 #endif 489 if ((sc->g_src.s_addr != INADDR_ANY) && 490 (sc->g_dst.s_addr != INADDR_ANY)) { 491 bzero(&sp, sizeof(sp)); 492 bzero(&sm, sizeof(sm)); 493 bzero(&dp, sizeof(dp)); 494 bzero(&dm, sizeof(dm)); 495 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 496 sizeof(struct sockaddr_in); 497 sp.sin_family = sm.sin_family = dp.sin_family = 498 dm.sin_family = AF_INET; 499 sp.sin_addr = sc->g_src; 500 dp.sin_addr = sc->g_dst; 501 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 502 INADDR_BROADCAST; 503 #ifdef INET 504 sc->encap = encap_attach(AF_INET, sc->g_proto, 505 sintosa(&sp), sintosa(&sm), sintosa(&dp), 506 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 507 &in_gre_protosw : &in_mobile_protosw, sc); 508 if (sc->encap == NULL) 509 kprintf("%s: unable to attach encap\n", 510 if_name(&sc->sc_if)); 511 #endif 512 if (sc->route.ro_rt != 0) /* free old route */ 513 RTFREE(sc->route.ro_rt); 514 if (gre_compute_route(sc) == 0) 515 ifp->if_flags |= IFF_RUNNING; 516 else 517 ifp->if_flags &= ~IFF_RUNNING; 518 } 519 break; 520 case GREGADDRS: 521 memset(&si, 0, sizeof(si)); 522 si.sin_family = AF_INET; 523 si.sin_len = sizeof(struct sockaddr_in); 524 si.sin_addr.s_addr = sc->g_src.s_addr; 525 sa = sintosa(&si); 526 ifr->ifr_addr = *sa; 527 break; 528 case GREGADDRD: 529 memset(&si, 0, sizeof(si)); 530 si.sin_family = AF_INET; 531 si.sin_len = sizeof(struct sockaddr_in); 532 si.sin_addr.s_addr = sc->g_dst.s_addr; 533 sa = sintosa(&si); 534 ifr->ifr_addr = *sa; 535 break; 536 case SIOCSIFPHYADDR: 537 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 538 break; 539 if (aifr->ifra_addr.sin_family != AF_INET || 540 aifr->ifra_dstaddr.sin_family != AF_INET) { 541 error = EAFNOSUPPORT; 542 break; 543 } 544 if (aifr->ifra_addr.sin_len != sizeof(si) || 545 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 546 error = EINVAL; 547 break; 548 } 549 sc->g_src = aifr->ifra_addr.sin_addr; 550 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 551 goto recompute; 552 case SIOCSLIFPHYADDR: 553 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 554 break; 555 if (lifr->addr.ss_family != AF_INET || 556 lifr->dstaddr.ss_family != AF_INET) { 557 error = EAFNOSUPPORT; 558 break; 559 } 560 if (lifr->addr.ss_len != sizeof(si) || 561 lifr->dstaddr.ss_len != sizeof(si)) { 562 error = EINVAL; 563 break; 564 } 565 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 566 sc->g_dst = 567 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 568 goto recompute; 569 case SIOCDIFPHYADDR: 570 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0) 571 break; 572 sc->g_src.s_addr = INADDR_ANY; 573 sc->g_dst.s_addr = INADDR_ANY; 574 goto recompute; 575 case SIOCGLIFPHYADDR: 576 if (sc->g_src.s_addr == INADDR_ANY || 577 sc->g_dst.s_addr == INADDR_ANY) { 578 error = EADDRNOTAVAIL; 579 break; 580 } 581 memset(&si, 0, sizeof(si)); 582 si.sin_family = AF_INET; 583 si.sin_len = sizeof(struct sockaddr_in); 584 si.sin_addr.s_addr = sc->g_src.s_addr; 585 memcpy(&lifr->addr, &si, sizeof(si)); 586 si.sin_addr.s_addr = sc->g_dst.s_addr; 587 memcpy(&lifr->dstaddr, &si, sizeof(si)); 588 break; 589 case SIOCGIFPSRCADDR: 590 if (sc->g_src.s_addr == INADDR_ANY) { 591 error = EADDRNOTAVAIL; 592 break; 593 } 594 memset(&si, 0, sizeof(si)); 595 si.sin_family = AF_INET; 596 si.sin_len = sizeof(struct sockaddr_in); 597 si.sin_addr.s_addr = sc->g_src.s_addr; 598 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 599 break; 600 case SIOCGIFPDSTADDR: 601 if (sc->g_dst.s_addr == INADDR_ANY) { 602 error = EADDRNOTAVAIL; 603 break; 604 } 605 memset(&si, 0, sizeof(si)); 606 si.sin_family = AF_INET; 607 si.sin_len = sizeof(struct sockaddr_in); 608 si.sin_addr.s_addr = sc->g_dst.s_addr; 609 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 610 break; 611 default: 612 error = EINVAL; 613 break; 614 } 615 616 crit_exit(); 617 return (error); 618 } 619 620 /* 621 * computes a route to our destination that is not the one 622 * which would be taken by ip_output(), as this one will loop back to 623 * us. If the interface is p2p as a--->b, then a routing entry exists 624 * If we now send a packet to b (e.g. ping b), this will come down here 625 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 626 * if_gre. 627 * Goal here is to compute a route to b that is less specific than 628 * a-->b. We know that this one exists as in normal operation we have 629 * at least a default route which matches. 630 */ 631 static int 632 gre_compute_route(struct gre_softc *sc) 633 { 634 struct route *ro; 635 u_int32_t a, b, c; 636 637 ro = &sc->route; 638 639 memset(ro, 0, sizeof(struct route)); 640 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 641 ro->ro_dst.sa_family = AF_INET; 642 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 643 644 /* 645 * toggle last bit, so our interface is not found, but a less 646 * specific route. I'd rather like to specify a shorter mask, 647 * but this is not possible. Should work though. XXX 648 * there is a simpler way ... 649 */ 650 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 651 a = ntohl(sc->g_dst.s_addr); 652 b = a & 0x01; 653 c = a & 0xfffffffe; 654 b = b ^ 0x01; 655 a = b | c; 656 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 657 = htonl(a); 658 } 659 660 #ifdef DIAGNOSTIC 661 kprintf("%s: searching a route to %s", if_name(&sc->sc_if), 662 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 663 #endif 664 665 rtalloc(ro); 666 667 /* 668 * check if this returned a route at all and this route is no 669 * recursion to ourself 670 */ 671 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 672 #ifdef DIAGNOSTIC 673 if (ro->ro_rt == NULL) 674 kprintf(" - no route found!\n"); 675 else 676 kprintf(" - route loops back to ourself!\n"); 677 #endif 678 return EADDRNOTAVAIL; 679 } 680 681 /* 682 * now change it back - else ip_output will just drop 683 * the route and search one to this interface ... 684 */ 685 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 686 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 687 688 #ifdef DIAGNOSTIC 689 kprintf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 690 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 691 kprintf("\n"); 692 #endif 693 694 return 0; 695 } 696 697 /* 698 * do a checksum of a buffer - much like in_cksum, which operates on 699 * mbufs. 700 */ 701 u_short 702 gre_in_cksum(u_short *p, u_int len) 703 { 704 u_int sum = 0; 705 int nwords = len >> 1; 706 707 while (nwords-- != 0) 708 sum += *p++; 709 710 if (len & 1) { 711 union { 712 u_short w; 713 u_char c[2]; 714 } u; 715 u.c[0] = *(u_char *)p; 716 u.c[1] = 0; 717 sum += u.w; 718 } 719 720 /* end-around-carry */ 721 sum = (sum >> 16) + (sum & 0xffff); 722 sum += (sum >> 16); 723 return (~sum); 724 } 725 726 static int 727 gremodevent(module_t mod, int type, void *data) 728 { 729 730 switch (type) { 731 case MOD_LOAD: 732 greattach(); 733 break; 734 case MOD_UNLOAD: 735 if_clone_detach(&gre_cloner); 736 737 while (!LIST_EMPTY(&gre_softc_list)) 738 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 739 740 break; 741 } 742 return 0; 743 } 744 745 static moduledata_t gre_mod = { 746 "if_gre", 747 gremodevent, 748 0 749 }; 750 751 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 752 MODULE_VERSION(if_gre, 1); 753