sys/net/gre/if_gre.c

   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 1.21 2008/05/14 11:59:23 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_serialized(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_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 393            struct rtentry *rt)
 394 {
 395         int error;
 396
 397         lwkt_serialize_enter(ifp->if_serializer);
 398         error = gre_output_serialized(ifp, m, dst, rt);
 399         lwkt_serialize_exit(ifp->if_serializer);
 400
 401         return error;
 402 }
 403
 404 static int
 405 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 406 {
 407         struct ifreq *ifr = (struct ifreq *)data;
 408         struct if_laddrreq *lifr = (struct if_laddrreq *)data;
 409         struct in_aliasreq *aifr = (struct in_aliasreq *)data;
 410         struct gre_softc *sc = ifp->if_softc;
 411         struct sockaddr_in si;
 412         struct sockaddr *sa = NULL;
 413         int error;
 414         struct sockaddr_in sp, sm, dp, dm;
 415
 416         error = 0;
 417
 418         crit_enter();
 419         switch (cmd) {
 420         case SIOCSIFADDR:
 421                 ifp->if_flags |= IFF_UP;
 422                 break;
 423         case SIOCSIFDSTADDR:
 424                 break;
 425         case SIOCSIFFLAGS:
 426                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 427                         break;
 428                 if ((ifr->ifr_flags & IFF_LINK0) != 0)
 429                         sc->g_proto = IPPROTO_GRE;
 430                 else
 431                         sc->g_proto = IPPROTO_MOBILE;
 432                 goto recompute;
 433         case SIOCSIFMTU:
 434                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 435                         break;
 436                 if (ifr->ifr_mtu < 576) {
 437                         error = EINVAL;
 438                         break;
 439                 }
 440                 ifp->if_mtu = ifr->ifr_mtu;
 441                 break;
 442         case SIOCGIFMTU:
 443                 ifr->ifr_mtu = sc->sc_if.if_mtu;
 444                 break;
 445         case SIOCADDMULTI:
 446         case SIOCDELMULTI:
 447                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 448                         break;
 449                 if (ifr == 0) {
 450                         error = EAFNOSUPPORT;
 451                         break;
 452                 }
 453                 switch (ifr->ifr_addr.sa_family) {
 454 #ifdef INET
 455                 case AF_INET:
 456                         break;
 457 #endif
 458                 default:
 459                         error = EAFNOSUPPORT;
 460                         break;
 461                 }
 462                 break;
 463         case GRESPROTO:
 464                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 465                         break;
 466                 sc->g_proto = ifr->ifr_flags;
 467                 switch (sc->g_proto) {
 468                 case IPPROTO_GRE:
 469                         ifp->if_flags |= IFF_LINK0;
 470                         break;
 471                 case IPPROTO_MOBILE:
 472                         ifp->if_flags &= ~IFF_LINK0;
 473                         break;
 474                 default:
 475                         error = EPROTONOSUPPORT;
 476                         break;
 477                 }
 478                 goto recompute;
 479         case GREGPROTO:
 480                 ifr->ifr_flags = sc->g_proto;
 481                 break;
 482         case GRESADDRS:
 483         case GRESADDRD:
 484                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 485                         break;
 486                 /*
 487                  * set tunnel endpoints, compute a less specific route
 488                  * to the remote end and mark if as up
 489                  */
 490                 sa = &ifr->ifr_addr;
 491                 if (cmd == GRESADDRS)
 492                         sc->g_src = (satosin(sa))->sin_addr;
 493                 if (cmd == GRESADDRD)
 494                         sc->g_dst = (satosin(sa))->sin_addr;
 495         recompute:
 496 #ifdef INET
 497                 if (sc->encap != NULL) {
 498                         encap_detach(sc->encap);
 499                         sc->encap = NULL;
 500                 }
 501 #endif
 502                 if ((sc->g_src.s_addr != INADDR_ANY) &&
 503                     (sc->g_dst.s_addr != INADDR_ANY)) {
 504                         bzero(&sp, sizeof(sp));
 505                         bzero(&sm, sizeof(sm));
 506                         bzero(&dp, sizeof(dp));
 507                         bzero(&dm, sizeof(dm));
 508                         sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
 509                             sizeof(struct sockaddr_in);
 510                         sp.sin_family = sm.sin_family = dp.sin_family =
 511                             dm.sin_family = AF_INET;
 512                         sp.sin_addr = sc->g_src;
 513                         dp.sin_addr = sc->g_dst;
 514                         sm.sin_addr.s_addr = dm.sin_addr.s_addr =
 515                             INADDR_BROADCAST;
 516 #ifdef INET
 517                         sc->encap = encap_attach(AF_INET, sc->g_proto,
 518                             sintosa(&sp), sintosa(&sm), sintosa(&dp),
 519                             sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
 520                                 &in_gre_protosw : &in_mobile_protosw, sc);
 521                         if (sc->encap == NULL)
 522                                 kprintf("%s: unable to attach encap\n",
 523                                     if_name(&sc->sc_if));
 524 #endif
 525                         if (sc->route.ro_rt != 0) /* free old route */
 526                                 RTFREE(sc->route.ro_rt);
 527                         if (gre_compute_route(sc) == 0)
 528                                 ifp->if_flags |= IFF_RUNNING;
 529                         else
 530                                 ifp->if_flags &= ~IFF_RUNNING;
 531                 }
 532                 break;
 533         case GREGADDRS:
 534                 memset(&si, 0, sizeof(si));
 535                 si.sin_family = AF_INET;
 536                 si.sin_len = sizeof(struct sockaddr_in);
 537                 si.sin_addr.s_addr = sc->g_src.s_addr;
 538                 sa = sintosa(&si);
 539                 ifr->ifr_addr = *sa;
 540                 break;
 541         case GREGADDRD:
 542                 memset(&si, 0, sizeof(si));
 543                 si.sin_family = AF_INET;
 544                 si.sin_len = sizeof(struct sockaddr_in);
 545                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 546                 sa = sintosa(&si);
 547                 ifr->ifr_addr = *sa;
 548                 break;
 549         case SIOCSIFPHYADDR:
 550                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 551                         break;
 552                 if (aifr->ifra_addr.sin_family != AF_INET ||
 553                     aifr->ifra_dstaddr.sin_family != AF_INET) {
 554                         error = EAFNOSUPPORT;
 555                         break;
 556                 }
 557                 if (aifr->ifra_addr.sin_len != sizeof(si) ||
 558                     aifr->ifra_dstaddr.sin_len != sizeof(si)) {
 559                         error = EINVAL;
 560                         break;
 561                 }
 562                 sc->g_src = aifr->ifra_addr.sin_addr;
 563                 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
 564                 goto recompute;
 565         case SIOCSLIFPHYADDR:
 566                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 567                         break;
 568                 if (lifr->addr.ss_family != AF_INET ||
 569                     lifr->dstaddr.ss_family != AF_INET) {
 570                         error = EAFNOSUPPORT;
 571                         break;
 572                 }
 573                 if (lifr->addr.ss_len != sizeof(si) ||
 574                     lifr->dstaddr.ss_len != sizeof(si)) {
 575                         error = EINVAL;
 576                         break;
 577                 }
 578                 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr;
 579                 sc->g_dst =
 580                     (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr;
 581                 goto recompute;
 582         case SIOCDIFPHYADDR:
 583                 if ((error = suser_cred(cr, NULL_CRED_OKAY)) != 0)
 584                         break;
 585                 sc->g_src.s_addr = INADDR_ANY;
 586                 sc->g_dst.s_addr = INADDR_ANY;
 587                 goto recompute;
 588         case SIOCGLIFPHYADDR:
 589                 if (sc->g_src.s_addr == INADDR_ANY ||
 590                     sc->g_dst.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                 memcpy(&lifr->addr, &si, sizeof(si));
 599                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 600                 memcpy(&lifr->dstaddr, &si, sizeof(si));
 601                 break;
 602         case SIOCGIFPSRCADDR:
 603                 if (sc->g_src.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_src.s_addr;
 611                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 612                 break;
 613         case SIOCGIFPDSTADDR:
 614                 if (sc->g_dst.s_addr == INADDR_ANY) {
 615                         error = EADDRNOTAVAIL;
 616                         break;
 617                 }
 618                 memset(&si, 0, sizeof(si));
 619                 si.sin_family = AF_INET;
 620                 si.sin_len = sizeof(struct sockaddr_in);
 621                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 622                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 623                 break;
 624         default:
 625                 error = EINVAL;
 626                 break;
 627         }
 628
 629         crit_exit();
 630         return (error);
 631 }
 632
 633 /*
 634  * computes a route to our destination that is not the one
 635  * which would be taken by ip_output(), as this one will loop back to
 636  * us. If the interface is p2p as  a--->b, then a routing entry exists
 637  * If we now send a packet to b (e.g. ping b), this will come down here
 638  * gets src=a, dst=b tacked on and would from ip_ouput() sent back to
 639  * if_gre.
 640  * Goal here is to compute a route to b that is less specific than
 641  * a-->b. We know that this one exists as in normal operation we have
 642  * at least a default route which matches.
 643  */
 644 static int
 645 gre_compute_route(struct gre_softc *sc)
 646 {
 647         struct route *ro;
 648         u_int32_t a, b, c;
 649
 650         ro = &sc->route;
 651
 652         memset(ro, 0, sizeof(struct route));
 653         ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 654         ro->ro_dst.sa_family = AF_INET;
 655         ro->ro_dst.sa_len = sizeof(ro->ro_dst);
 656
 657         /*
 658          * toggle last bit, so our interface is not found, but a less
 659          * specific route. I'd rather like to specify a shorter mask,
 660          * but this is not possible. Should work though. XXX
 661          * there is a simpler way ...
 662          */
 663         if ((sc->sc_if.if_flags & IFF_LINK1) == 0) {
 664                 a = ntohl(sc->g_dst.s_addr);
 665                 b = a & 0x01;
 666                 c = a & 0xfffffffe;
 667                 b = b ^ 0x01;
 668                 a = b | c;
 669                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr
 670                     = htonl(a);
 671         }
 672
 673 #ifdef DIAGNOSTIC
 674         kprintf("%s: searching a route to %s", if_name(&sc->sc_if),
 675             inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
 676 #endif
 677
 678         rtalloc(ro);
 679
 680         /*
 681          * check if this returned a route at all and this route is no
 682          * recursion to ourself
 683          */
 684         if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
 685 #ifdef DIAGNOSTIC
 686                 if (ro->ro_rt == NULL)
 687                         kprintf(" - no route found!\n");
 688                 else
 689                         kprintf(" - route loops back to ourself!\n");
 690 #endif
 691                 return EADDRNOTAVAIL;
 692         }
 693
 694         /*
 695          * now change it back - else ip_output will just drop
 696          * the route and search one to this interface ...
 697          */
 698         if ((sc->sc_if.if_flags & IFF_LINK1) == 0)
 699                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 700
 701 #ifdef DIAGNOSTIC
 702         kprintf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
 703             inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
 704         kprintf("\n");
 705 #endif
 706
 707         return 0;
 708 }
 709
 710 /*
 711  * do a checksum of a buffer - much like in_cksum, which operates on
 712  * mbufs.
 713  */
 714 u_short
 715 gre_in_cksum(u_short *p, u_int len)
 716 {
 717         u_int sum = 0;
 718         int nwords = len >> 1;
 719
 720         while (nwords-- != 0)
 721                 sum += *p++;
 722
 723         if (len & 1) {
 724                 union {
 725                         u_short w;
 726                         u_char c[2];
 727                 } u;
 728                 u.c[0] = *(u_char *)p;
 729                 u.c[1] = 0;
 730                 sum += u.w;
 731         }
 732
 733         /* end-around-carry */
 734         sum = (sum >> 16) + (sum & 0xffff);
 735         sum += (sum >> 16);
 736         return (~sum);
 737 }
 738
 739 static int
 740 gremodevent(module_t mod, int type, void *data)
 741 {
 742
 743         switch (type) {
 744         case MOD_LOAD:
 745                 greattach();
 746                 break;
 747         case MOD_UNLOAD:
 748                 if_clone_detach(&gre_cloner);
 749
 750                 while (!LIST_EMPTY(&gre_softc_list))
 751                         gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if);
 752
 753                 break;
 754         }
 755         return 0;
 756 }
 757
 758 static moduledata_t gre_mod = {
 759         "if_gre",
 760         gremodevent,
 761         0
 762 };
 763
 764 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
 765 MODULE_VERSION(if_gre, 1);