if_gre.c revision 103032
1/* $NetBSD: if_gre.c,v 1.42 2002/08/14 00:23:27 itojun Exp $ */ 2/* $FreeBSD: head/sys/net/if_gre.c 103032 2002-09-06 18:16:03Z sobomax $ */ 3 4/* 5 * Copyright (c) 1998 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Heiko W.Rupp <hwr@pilhuhn.de> 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40/* 41 * Encapsulate L3 protocols into IP 42 * See RFC 1701 and 1702 for more details. 43 * If_gre is compatible with Cisco GRE tunnels, so you can 44 * have a NetBSD box as the other end of a tunnel interface of a Cisco 45 * router. See gre(4) for more details. 46 * Also supported: IP in IP encaps (proto 55) as of RFC 2004 47 */ 48 49#include <sys/cdefs.h> 50__RCSID("@(#) $FreeBSD: head/sys/net/if_gre.c 103032 2002-09-06 18:16:03Z sobomax $"); 51 52#include "opt_inet.h" 53#include "opt_ns.h" 54#include "bpf.h" 55 56#include <sys/param.h> 57#include <sys/kernel.h> 58#include <sys/malloc.h> 59#include <sys/mbuf.h> 60#include <sys/proc.h> 61#include <sys/protosw.h> 62#include <sys/socket.h> 63#include <sys/sockio.h> 64#include <sys/queue.h> 65#include <sys/sysctl.h> 66 67#include <machine/cpu.h> 68 69#include <net/ethernet.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_gre.h> 81#include <netinet/ip_var.h> 82#include <netinet/ip_encap.h> 83#else 84#error "Huh? if_gre without inet?" 85#endif 86 87#ifdef NS 88#include <netns/ns.h> 89#include <netns/ns_if.h> 90#endif 91 92#ifdef NETATALK 93#include <netatalk/at.h> 94#include <netatalk/at_var.h> 95#include <netatalk/at_extern.h> 96#endif 97 98#if NBPF > 0 99#include <sys/time.h> 100#include <net/bpf.h> 101#endif 102 103#include <net/net_osdep.h> 104#include <net/if_gre.h> 105 106/* 107 * It is not easy to calculate the right value for a GRE MTU. 108 * We leave this task to the admin and use the same default that 109 * other vendors use. 110 */ 111#define GREMTU 1476 112 113#define GRENAME "gre" 114 115static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation"); 116 117struct gre_softc_head gre_softc_list; 118 119static int gre_clone_create __P((struct if_clone *, int)); 120static void gre_clone_destroy __P((struct ifnet *)); 121static int gre_ioctl(struct ifnet *, u_long, caddr_t); 122static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *, 123 struct rtentry *rt); 124 125static struct if_clone gre_cloner = 126 IF_CLONE_INITIALIZER("gre", gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT); 127 128static int gre_compute_route(struct gre_softc *sc); 129 130static void greattach __P((void)); 131 132#ifdef INET 133extern struct domain inetdomain; 134static const struct protosw in_gre_protosw = 135{ SOCK_RAW, &inetdomain, IPPROTO_GRE, PR_ATOMIC|PR_ADDR, 136 (pr_input_t*)gre_input, (pr_output_t*)rip_output, rip_ctlinput, rip_ctloutput, 137 0, 138 0, 0, 0, 0, 139 &rip_usrreqs 140}; 141static const struct protosw in_mobile_protosw = 142{ SOCK_RAW, &inetdomain, IPPROTO_MOBILE, PR_ATOMIC|PR_ADDR, 143 (pr_input_t*)gre_mobile_input, (pr_output_t*)rip_output, rip_ctlinput, rip_ctloutput, 144 0, 145 0, 0, 0, 0, 146 &rip_usrreqs 147}; 148#endif 149 150SYSCTL_DECL(_net_link); 151SYSCTL_NODE(_net_link, IFT_OTHER, gre, CTLFLAG_RW, 0, 152 "Generic Routing Encapsulation"); 153#ifndef MAX_GRE_NEST 154/* 155 * This macro controls the default upper limitation on nesting of gre tunnels. 156 * Since, setting a large value to this macro with a careless configuration 157 * may introduce system crash, we don't allow any nestings by default. 158 * If you need to configure nested gre tunnels, you can define this macro 159 * in your kernel configuration file. However, if you do so, please be 160 * careful to configure the tunnels so that it won't make a loop. 161 */ 162#define MAX_GRE_NEST 1 163#endif 164static int max_gre_nesting = MAX_GRE_NEST; 165SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW, 166 &max_gre_nesting, 0, "Max nested tunnels"); 167 168/* ARGSUSED */ 169static void 170greattach(void) 171{ 172 173 LIST_INIT(&gre_softc_list); 174 if_clone_attach(&gre_cloner); 175} 176 177static int 178gre_clone_create(ifc, unit) 179 struct if_clone *ifc; 180 int unit; 181{ 182 struct gre_softc *sc; 183 184 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK); 185 memset(sc, 0, sizeof(struct gre_softc)); 186 187 sc->sc_if.if_name = GRENAME; 188 sc->sc_if.if_softc = sc; 189 sc->sc_if.if_unit = unit; 190 sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN; 191 sc->sc_if.if_type = IFT_OTHER; 192 sc->sc_if.if_addrlen = 0; 193 sc->sc_if.if_hdrlen = 24; /* IP + GRE */ 194 sc->sc_if.if_mtu = GREMTU; 195 sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST; 196 sc->sc_if.if_output = gre_output; 197 sc->sc_if.if_ioctl = gre_ioctl; 198 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY; 199 sc->g_proto = IPPROTO_GRE; 200 sc->sc_if.if_flags |= IFF_LINK0; 201 sc->encap = NULL; 202 sc->called = 0; 203 if_attach(&sc->sc_if); 204#if NBPF 205 bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t)); 206#endif 207 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list); 208 return (0); 209} 210 211static void 212gre_clone_destroy(ifp) 213 struct ifnet *ifp; 214{ 215 struct gre_softc *sc = ifp->if_softc; 216 217#ifdef INET 218 if (sc->encap != NULL) 219 encap_detach(sc->encap); 220#endif 221 LIST_REMOVE(sc, sc_list); 222#if NBPF 223 bpfdetach(ifp); 224#endif 225 if_detach(ifp); 226 free(sc, M_GRE); 227} 228 229/* 230 * The output routine. Takes a packet and encapsulates it in the protocol 231 * given by sc->g_proto. See also RFC 1701 and RFC 2004 232 */ 233static int 234gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, 235 struct rtentry *rt) 236{ 237 int error = 0; 238 struct gre_softc *sc = ifp->if_softc; 239 struct greip *gh; 240 struct ip *ip; 241 u_char osrc; 242 u_short etype = 0; 243 struct mobile_h mob_h; 244 245 /* 246 * gre may cause infinite recursion calls when misconfigured. 247 * We'll prevent this by introducing upper limit. 248 */ 249 if (++(sc->called) > max_gre_nesting) { 250 printf("%s: gre_output: recursively called too many " 251 "times(%d)\n", if_name(&sc->sc_if), sc->called); 252 m_freem(m); 253 error = EIO; /* is there better errno? */ 254 goto end; 255 } 256 257 if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 || 258 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) { 259 m_freem(m); 260 error = ENETDOWN; 261 goto end; 262 } 263 264 gh = NULL; 265 ip = NULL; 266 osrc = 0; 267 268#if NBPF 269 if (ifp->if_bpf) { 270 /* see comment of other if_foo.c files */ 271 struct mbuf m0; 272 u_int32_t af = dst->sa_family; 273 274 m0.m_next = m; 275 m0.m_len = 4; 276 m0.m_data = (char *)⁡ 277 278 bpf_mtap(ifp, &m0); 279 } 280#endif 281 282 m->m_flags &= ~(M_BCAST|M_MCAST); 283 284 if (sc->g_proto == IPPROTO_MOBILE) { 285 if (dst->sa_family == AF_INET) { 286 struct mbuf *m0; 287 int msiz; 288 289 ip = mtod(m, struct ip *); 290 291 /* 292 * RFC2004 specifies that fragmented diagrams shouldn't 293 * be encapsulated. 294 */ 295 if ((ip->ip_off & IP_MF) != 0) { 296 _IF_DROP(&ifp->if_snd); 297 m_freem(m); 298 error = EINVAL; /* is there better errno? */ 299 goto end; 300 } 301 memset(&mob_h, 0, MOB_H_SIZ_L); 302 mob_h.proto = (ip->ip_p) << 8; 303 mob_h.odst = ip->ip_dst.s_addr; 304 ip->ip_dst.s_addr = sc->g_dst.s_addr; 305 306 /* 307 * If the packet comes from our host, we only change 308 * the destination address in the IP header. 309 * Else we also need to save and change the source 310 */ 311 if (in_hosteq(ip->ip_src, sc->g_src)) { 312 msiz = MOB_H_SIZ_S; 313 } else { 314 mob_h.proto |= MOB_H_SBIT; 315 mob_h.osrc = ip->ip_src.s_addr; 316 ip->ip_src.s_addr = sc->g_src.s_addr; 317 msiz = MOB_H_SIZ_L; 318 } 319 mob_h.proto = htons(mob_h.proto); 320 mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz); 321 322 if ((m->m_data - msiz) < m->m_pktdat) { 323 /* need new mbuf */ 324 MGETHDR(m0, M_DONTWAIT, MT_HEADER); 325 if (m0 == NULL) { 326 _IF_DROP(&ifp->if_snd); 327 m_freem(m); 328 error = ENOBUFS; 329 goto end; 330 } 331 m0->m_next = m; 332 m->m_data += sizeof(struct ip); 333 m->m_len -= sizeof(struct ip); 334 m0->m_pkthdr.len = m->m_pkthdr.len + msiz; 335 m0->m_len = msiz + sizeof(struct ip); 336 m0->m_data += max_linkhdr; 337 memcpy(mtod(m0, caddr_t), (caddr_t)ip, 338 sizeof(struct ip)); 339 m = m0; 340 } else { /* we have some space left in the old one */ 341 m->m_data -= msiz; 342 m->m_len += msiz; 343 m->m_pkthdr.len += msiz; 344 bcopy(ip, mtod(m, caddr_t), 345 sizeof(struct ip)); 346 } 347 ip = mtod(m, struct ip *); 348 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz); 349 ip->ip_len = ntohs(ip->ip_len) + msiz; 350 } else { /* AF_INET */ 351 _IF_DROP(&ifp->if_snd); 352 m_freem(m); 353 error = EINVAL; 354 goto end; 355 } 356 } else if (sc->g_proto == IPPROTO_GRE) { 357 switch (dst->sa_family) { 358 case AF_INET: 359 ip = mtod(m, struct ip *); 360 etype = ETHERTYPE_IP; 361 break; 362#ifdef NETATALK 363 case AF_APPLETALK: 364 etype = ETHERTYPE_ATALK; 365 break; 366#endif 367#ifdef NS 368 case AF_NS: 369 etype = ETHERTYPE_NS; 370 break; 371#endif 372 default: 373 _IF_DROP(&ifp->if_snd); 374 m_freem(m); 375 error = EAFNOSUPPORT; 376 goto end; 377 } 378 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT); 379 } else { 380 _IF_DROP(&ifp->if_snd); 381 m_freem(m); 382 error = EINVAL; 383 goto end; 384 } 385 386 if (m == NULL) { /* impossible */ 387 _IF_DROP(&ifp->if_snd); 388 error = ENOBUFS; 389 goto end; 390 } 391 392 gh = mtod(m, struct greip *); 393 if (sc->g_proto == IPPROTO_GRE) { 394 /* we don't have any GRE flags for now */ 395 396 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h)); 397 gh->gi_ptype = htons(etype); 398 } 399 400 gh->gi_pr = sc->g_proto; 401 if (sc->g_proto != IPPROTO_MOBILE) { 402 gh->gi_src = sc->g_src; 403 gh->gi_dst = sc->g_dst; 404 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2; 405 ((struct ip*)gh)->ip_ttl = GRE_TTL; 406 ((struct ip*)gh)->ip_tos = ip->ip_tos; 407 ((struct ip*)gh)->ip_id = ip->ip_id; 408 gh->gi_len = m->m_pkthdr.len; 409 } 410 411 ifp->if_opackets++; 412 ifp->if_obytes += m->m_pkthdr.len; 413 /* send it off */ 414 error = ip_output(m, NULL, &sc->route, 0, NULL); 415 end: 416 sc->called = 0; 417 if (error) 418 ifp->if_oerrors++; 419 return (error); 420} 421 422static int 423gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) 424{ 425 struct ifreq *ifr = (struct ifreq *)data; 426 struct if_laddrreq *lifr = (struct if_laddrreq *)data; 427 struct in_aliasreq *aifr = (struct in_aliasreq *)data; 428 struct gre_softc *sc = ifp->if_softc; 429 int s; 430 struct sockaddr_in si; 431 struct sockaddr *sa = NULL; 432 int error; 433 struct sockaddr_in sp, sm, dp, dm; 434 435 error = 0; 436 437 s = splnet(); 438 switch (cmd) { 439 case SIOCSIFADDR: 440 ifp->if_flags |= IFF_UP; 441 break; 442 case SIOCSIFDSTADDR: 443 break; 444 case SIOCSIFFLAGS: 445 if ((error = suser(curthread)) != 0) 446 break; 447 if ((ifr->ifr_flags & IFF_LINK0) != 0) 448 sc->g_proto = IPPROTO_GRE; 449 else 450 sc->g_proto = IPPROTO_MOBILE; 451 goto recompute; 452 case SIOCSIFMTU: 453 if ((error = suser(curthread)) != 0) 454 break; 455 if (ifr->ifr_mtu < 576) { 456 error = EINVAL; 457 break; 458 } 459 ifp->if_mtu = ifr->ifr_mtu; 460 break; 461 case SIOCGIFMTU: 462 ifr->ifr_mtu = sc->sc_if.if_mtu; 463 break; 464 case SIOCADDMULTI: 465 case SIOCDELMULTI: 466 if ((error = suser(curthread)) != 0) 467 break; 468 if (ifr == 0) { 469 error = EAFNOSUPPORT; 470 break; 471 } 472 switch (ifr->ifr_addr.sa_family) { 473#ifdef INET 474 case AF_INET: 475 break; 476#endif 477 default: 478 error = EAFNOSUPPORT; 479 break; 480 } 481 break; 482 case GRESPROTO: 483 if ((error = suser(curthread)) != 0) 484 break; 485 sc->g_proto = ifr->ifr_flags; 486 switch (sc->g_proto) { 487 case IPPROTO_GRE: 488 ifp->if_flags |= IFF_LINK0; 489 break; 490 case IPPROTO_MOBILE: 491 ifp->if_flags &= ~IFF_LINK0; 492 break; 493 default: 494 error = EPROTONOSUPPORT; 495 break; 496 } 497 goto recompute; 498 case GREGPROTO: 499 ifr->ifr_flags = sc->g_proto; 500 break; 501 case GRESADDRS: 502 case GRESADDRD: 503 if ((error = suser(curthread)) != 0) 504 break; 505 /* 506 * set tunnel endpoints, compute a less specific route 507 * to the remote end and mark if as up 508 */ 509 sa = &ifr->ifr_addr; 510 if (cmd == GRESADDRS) 511 sc->g_src = (satosin(sa))->sin_addr; 512 if (cmd == GRESADDRD) 513 sc->g_dst = (satosin(sa))->sin_addr; 514 recompute: 515#ifdef INET 516 if (sc->encap != NULL) { 517 encap_detach(sc->encap); 518 sc->encap = NULL; 519 } 520#endif 521 if ((sc->g_src.s_addr != INADDR_ANY) && 522 (sc->g_dst.s_addr != INADDR_ANY)) { 523 bzero(&sp, sizeof(sp)); 524 bzero(&sm, sizeof(sm)); 525 bzero(&dp, sizeof(dp)); 526 bzero(&dm, sizeof(dm)); 527 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len = 528 sizeof(struct sockaddr_in); 529 sp.sin_family = sm.sin_family = dp.sin_family = 530 dm.sin_family = AF_INET; 531 sp.sin_addr = sc->g_src; 532 dp.sin_addr = sc->g_dst; 533 sm.sin_addr.s_addr = dm.sin_addr.s_addr = 534 INADDR_BROADCAST; 535#ifdef INET 536 sc->encap = encap_attach(AF_INET, sc->g_proto, 537 sintosa(&sp), sintosa(&sm), sintosa(&dp), 538 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ? 539 &in_gre_protosw : &in_mobile_protosw, sc); 540 if (sc->encap == NULL) 541 printf("%s: unable to attach encap\n", 542 if_name(&sc->sc_if)); 543#endif 544 if (sc->route.ro_rt != 0) /* free old route */ 545 RTFREE(sc->route.ro_rt); 546 if (gre_compute_route(sc) == 0) 547 ifp->if_flags |= IFF_RUNNING; 548 else 549 ifp->if_flags &= ~IFF_RUNNING; 550 } 551 break; 552 case GREGADDRS: 553 memset(&si, 0, sizeof(si)); 554 si.sin_family = AF_INET; 555 si.sin_len = sizeof(struct sockaddr_in); 556 si.sin_addr.s_addr = sc->g_src.s_addr; 557 sa = sintosa(&si); 558 ifr->ifr_addr = *sa; 559 break; 560 case GREGADDRD: 561 memset(&si, 0, sizeof(si)); 562 si.sin_family = AF_INET; 563 si.sin_len = sizeof(struct sockaddr_in); 564 si.sin_addr.s_addr = sc->g_dst.s_addr; 565 sa = sintosa(&si); 566 ifr->ifr_addr = *sa; 567 break; 568 case SIOCSIFPHYADDR: 569 if ((error = suser(curthread)) != 0) 570 break; 571 if (aifr->ifra_addr.sin_family != AF_INET || 572 aifr->ifra_dstaddr.sin_family != AF_INET) { 573 error = EAFNOSUPPORT; 574 break; 575 } 576 if (aifr->ifra_addr.sin_len != sizeof(si) || 577 aifr->ifra_dstaddr.sin_len != sizeof(si)) { 578 error = EINVAL; 579 break; 580 } 581 sc->g_src = aifr->ifra_addr.sin_addr; 582 sc->g_dst = aifr->ifra_dstaddr.sin_addr; 583 goto recompute; 584 case SIOCSLIFPHYADDR: 585 if ((error = suser(curthread)) != 0) 586 break; 587 if (lifr->addr.ss_family != AF_INET || 588 lifr->dstaddr.ss_family != AF_INET) { 589 error = EAFNOSUPPORT; 590 break; 591 } 592 if (lifr->addr.ss_len != sizeof(si) || 593 lifr->dstaddr.ss_len != sizeof(si)) { 594 error = EINVAL; 595 break; 596 } 597 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr; 598 sc->g_dst = 599 (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr; 600 goto recompute; 601 case SIOCDIFPHYADDR: 602 if ((error = suser(curthread)) != 0) 603 break; 604 sc->g_src.s_addr = INADDR_ANY; 605 sc->g_dst.s_addr = INADDR_ANY; 606 goto recompute; 607 case SIOCGLIFPHYADDR: 608 if (sc->g_src.s_addr == INADDR_ANY || 609 sc->g_dst.s_addr == INADDR_ANY) { 610 error = EADDRNOTAVAIL; 611 break; 612 } 613 memset(&si, 0, sizeof(si)); 614 si.sin_family = AF_INET; 615 si.sin_len = sizeof(struct sockaddr_in); 616 si.sin_addr.s_addr = sc->g_src.s_addr; 617 memcpy(&lifr->addr, &si, sizeof(si)); 618 si.sin_addr.s_addr = sc->g_dst.s_addr; 619 memcpy(&lifr->dstaddr, &si, sizeof(si)); 620 break; 621 case SIOCGIFPSRCADDR: 622 if (sc->g_src.s_addr == INADDR_ANY) { 623 error = EADDRNOTAVAIL; 624 break; 625 } 626 memset(&si, 0, sizeof(si)); 627 si.sin_family = AF_INET; 628 si.sin_len = sizeof(struct sockaddr_in); 629 si.sin_addr.s_addr = sc->g_src.s_addr; 630 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 631 break; 632 case SIOCGIFPDSTADDR: 633 if (sc->g_dst.s_addr == INADDR_ANY) { 634 error = EADDRNOTAVAIL; 635 break; 636 } 637 memset(&si, 0, sizeof(si)); 638 si.sin_family = AF_INET; 639 si.sin_len = sizeof(struct sockaddr_in); 640 si.sin_addr.s_addr = sc->g_dst.s_addr; 641 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr)); 642 break; 643 default: 644 error = EINVAL; 645 break; 646 } 647 648 splx(s); 649 return (error); 650} 651 652/* 653 * computes a route to our destination that is not the one 654 * which would be taken by ip_output(), as this one will loop back to 655 * us. If the interface is p2p as a--->b, then a routing entry exists 656 * If we now send a packet to b (e.g. ping b), this will come down here 657 * gets src=a, dst=b tacked on and would from ip_ouput() sent back to 658 * if_gre. 659 * Goal here is to compute a route to b that is less specific than 660 * a-->b. We know that this one exists as in normal operation we have 661 * at least a default route which matches. 662 */ 663static int 664gre_compute_route(struct gre_softc *sc) 665{ 666 struct route *ro; 667 u_int32_t a, b, c; 668 669 ro = &sc->route; 670 671 memset(ro, 0, sizeof(struct route)); 672 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 673 ro->ro_dst.sa_family = AF_INET; 674 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 675 676 /* 677 * toggle last bit, so our interface is not found, but a less 678 * specific route. I'd rather like to specify a shorter mask, 679 * but this is not possible. Should work though. XXX 680 * there is a simpler way ... 681 */ 682 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) { 683 a = ntohl(sc->g_dst.s_addr); 684 b = a & 0x01; 685 c = a & 0xfffffffe; 686 b = b ^ 0x01; 687 a = b | c; 688 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr 689 = htonl(a); 690 } 691 692#ifdef DIAGNOSTIC 693 printf("%s: searching a route to %s", if_name(&sc->sc_if), 694 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr)); 695#endif 696 697 rtalloc(ro); 698 699 /* 700 * check if this returned a route at all and this route is no 701 * recursion to ourself 702 */ 703 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) { 704#ifdef DIAGNOSTIC 705 if (ro->ro_rt == NULL) 706 printf(" - no route found!\n"); 707 else 708 printf(" - route loops back to ourself!\n"); 709#endif 710 return EADDRNOTAVAIL; 711 } 712 713 /* 714 * now change it back - else ip_output will just drop 715 * the route and search one to this interface ... 716 */ 717 if ((sc->sc_if.if_flags & IFF_LINK1) == 0) 718 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst; 719 720#ifdef DIAGNOSTIC 721 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp), 722 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr)); 723 printf("\n"); 724#endif 725 726 return 0; 727} 728 729/* 730 * do a checksum of a buffer - much like in_cksum, which operates on 731 * mbufs. 732 */ 733u_short 734gre_in_cksum(u_short *p, u_int len) 735{ 736 u_int sum = 0; 737 int nwords = len >> 1; 738 739 while (nwords-- != 0) 740 sum += *p++; 741 742 if (len & 1) { 743 union { 744 u_short w; 745 u_char c[2]; 746 } u; 747 u.c[0] = *(u_char *)p; 748 u.c[1] = 0; 749 sum += u.w; 750 } 751 752 /* end-around-carry */ 753 sum = (sum >> 16) + (sum & 0xffff); 754 sum += (sum >> 16); 755 return (~sum); 756} 757 758static int 759gremodevent(module_t mod, int type, void *data) 760{ 761 762 switch (type) { 763 case MOD_LOAD: 764 greattach(); 765 break; 766 case MOD_UNLOAD: 767 if_clone_detach(&gre_cloner); 768 769 while (!LIST_EMPTY(&gre_softc_list)) 770 gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if); 771 break; 772 } 773 return 0; 774} 775 776static moduledata_t gre_mod = { 777 "if_gre", 778 gremodevent, 779 0 780}; 781 782DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY); 783MODULE_VERSION(if_gre, 1); 784