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 1.22 2008/10/27 02:56:30 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/priv.h>
  61 #include <sys/protosw.h>
  62 #include <sys/socket.h>
  63 #include <sys/sockio.h>
  64 #include <sys/sysctl.h>
  65 #include <sys/systm.h>
  66 #include <sys/thread2.h>
  67
  68 #include <net/ethernet.h>
  69 #include <net/if.h>
  70 #include <net/if_types.h>
  71 #include <net/route.h>
  72 #include <net/if_clone.h>
  73
  74 #ifdef INET
  75 #include <netinet/in.h>
  76 #include <netinet/in_systm.h>
  77 #include <netinet/in_var.h>
  78 #include <netinet/ip.h>
  79 #include <netinet/ip_gre.h>
  80 #include <netinet/ip_var.h>
  81 #include <netinet/ip_encap.h>
  82 #else
  83 #error "Huh? if_gre without inet?"
  84 #endif
  85
  86 #include <net/bpf.h>
  87
  88 #include <net/net_osdep.h>
  89 #include "if_gre.h"
  90
  91 /*
  92  * It is not easy to calculate the right value for a GRE MTU.
  93  * We leave this task to the admin and use the same default that
  94  * other vendors use.
  95  */
  96 #define GREMTU  1476
  97
  98 #define GRENAME "gre"
  99
 100 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
 101
 102 struct gre_softc_head gre_softc_list;
 103
 104 static int      gre_clone_create(struct if_clone *, int);
 105 static void     gre_clone_destroy(struct ifnet *);
 106 static int      gre_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
 107 static int      gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
 108                     struct rtentry *rt);
 109
 110 static struct if_clone gre_cloner = IF_CLONE_INITIALIZER("gre",
 111     gre_clone_create, gre_clone_destroy, 0, IF_MAXUNIT);
 112
 113 static int gre_compute_route(struct gre_softc *sc);
 114
 115 static void     greattach(void);
 116
 117 #ifdef INET
 118 extern struct domain inetdomain;
 119 static const struct protosw in_gre_protosw =
 120 { SOCK_RAW,     &inetdomain,    IPPROTO_GRE,    PR_ATOMIC|PR_ADDR,
 121   gre_input,    rip_output,     rip_ctlinput,   rip_ctloutput,
 122   cpu0_soport,  cpu0_ctlport,
 123   0,            0,              0,              0,
 124   &rip_usrreqs
 125 };
 126 static const struct protosw in_mobile_protosw =
 127 { SOCK_RAW,     &inetdomain,    IPPROTO_MOBILE, PR_ATOMIC|PR_ADDR,
 128   gre_mobile_input, rip_output, rip_ctlinput,   rip_ctloutput,
 129   cpu0_soport,  cpu0_ctlport,
 130   0,            0,              0,              0,
 131   &rip_usrreqs
 132 };
 133 #endif
 134
 135 SYSCTL_DECL(_net_link);
 136 SYSCTL_NODE(_net_link, IFT_OTHER, gre, CTLFLAG_RW, 0,
 137     "Generic Routing Encapsulation");
 138 #ifndef MAX_GRE_NEST
 139 /*
 140  * This macro controls the default upper limitation on nesting of gre tunnels.
 141  * Since, setting a large value to this macro with a careless configuration
 142  * may introduce system crash, we don't allow any nestings by default.
 143  * If you need to configure nested gre tunnels, you can define this macro
 144  * in your kernel configuration file.  However, if you do so, please be
 145  * careful to configure the tunnels so that it won't make a loop.
 146  */
 147 #define MAX_GRE_NEST 1
 148 #endif
 149 static int max_gre_nesting = MAX_GRE_NEST;
 150 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
 151     &max_gre_nesting, 0, "Max nested tunnels");
 152
 153 /* ARGSUSED */
 154 static void
 155 greattach(void)
 156 {
 157
 158         LIST_INIT(&gre_softc_list);
 159         if_clone_attach(&gre_cloner);
 160 }
 161
 162 static int
 163 gre_clone_create(struct if_clone *ifc, int unit)
 164 {
 165         struct gre_softc *sc;
 166
 167         sc = kmalloc(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, NULL);
 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(struct ifnet *ifp)
 193 {
 194         struct gre_softc *sc = ifp->if_softc;
 195
 196 #ifdef INET
 197         if (sc->encap != NULL)
 198                 encap_detach(sc->encap);
 199 #endif
 200         LIST_REMOVE(sc, sc_list);
 201         bpfdetach(ifp);
 202         if_detach(ifp);
 203
 204         kfree(sc, M_GRE);
 205 }
 206
 207 /*
 208  * The output routine. Takes a packet and encapsulates it in the protocol
 209  * given by sc->g_proto. See also RFC 1701 and RFC 2004
 210  */
 211 static int
 212 gre_output_serialized(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 213                       struct rtentry *rt)
 214 {
 215         int error = 0;
 216         struct gre_softc *sc = ifp->if_softc;
 217         struct greip *gh;
 218         struct ip *ip;
 219         u_char osrc;
 220         u_short etype = 0;
 221         struct mobile_h mob_h;
 222
 223         /*
 224          * gre may cause infinite recursion calls when misconfigured.
 225          * We'll prevent this by introducing upper limit.
 226          */
 227         if (++(sc->called) > max_gre_nesting) {
 228                 kprintf("%s: gre_output: recursively called too many "
 229                        "times(%d)\n", if_name(&sc->sc_if), sc->called);
 230                 m_freem(m);
 231                 error = EIO;    /* is there better errno? */
 232                 goto end;
 233         }
 234
 235         if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 ||
 236             sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
 237                 m_freem(m);
 238                 error = ENETDOWN;
 239                 goto end;
 240         }
 241
 242         gh = NULL;
 243         ip = NULL;
 244         osrc = 0;
 245
 246         if (ifp->if_bpf) {
 247                 uint32_t af = dst->sa_family;
 248
 249                 bpf_ptap(ifp->if_bpf, m, &af, sizeof(af));
 250         }
 251
 252         m->m_flags &= ~(M_BCAST|M_MCAST);
 253
 254         if (sc->g_proto == IPPROTO_MOBILE) {
 255                 if (dst->sa_family == AF_INET) {
 256                         struct mbuf *m0;
 257                         int msiz;
 258
 259                         ip = mtod(m, struct ip *);
 260
 261                         /*
 262                          * RFC2004 specifies that fragmented datagrams shouldn't
 263                          * be encapsulated.
 264                          */
 265                         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 266                                 IF_DROP(&ifp->if_snd);
 267                                 m_freem(m);
 268                                 error = EINVAL;    /* is there better errno? */
 269                                 goto end;
 270                         }
 271                         memset(&mob_h, 0, MOB_H_SIZ_L);
 272                         mob_h.proto = (ip->ip_p) << 8;
 273                         mob_h.odst = ip->ip_dst.s_addr;
 274                         ip->ip_dst.s_addr = sc->g_dst.s_addr;
 275
 276                         /*
 277                          * If the packet comes from our host, we only change
 278                          * the destination address in the IP header.
 279                          * Else we also need to save and change the source
 280                          */
 281                         if (in_hosteq(ip->ip_src, sc->g_src)) {
 282                                 msiz = MOB_H_SIZ_S;
 283                         } else {
 284                                 mob_h.proto |= MOB_H_SBIT;
 285                                 mob_h.osrc = ip->ip_src.s_addr;
 286                                 ip->ip_src.s_addr = sc->g_src.s_addr;
 287                                 msiz = MOB_H_SIZ_L;
 288                         }
 289                         mob_h.proto = htons(mob_h.proto);
 290                         mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz);
 291
 292                         if ((m->m_data - msiz) < m->m_pktdat) {
 293                                 /* need new mbuf */
 294                                 MGETHDR(m0, MB_DONTWAIT, MT_HEADER);
 295                                 if (m0 == NULL) {
 296                                         IF_DROP(&ifp->if_snd);
 297                                         m_freem(m);
 298                                         error = ENOBUFS;
 299                                         goto end;
 300                                 }
 301                                 m0->m_next = m;
 302                                 m->m_data += sizeof(struct ip);
 303                                 m->m_len -= sizeof(struct ip);
 304                                 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
 305                                 m0->m_len = msiz + sizeof(struct ip);
 306                                 m0->m_data += max_linkhdr;
 307                                 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
 308                                        sizeof(struct ip));
 309                                 m = m0;
 310                         } else {  /* we have some space left in the old one */
 311                                 m->m_data -= msiz;
 312                                 m->m_len += msiz;
 313                                 m->m_pkthdr.len += msiz;
 314                                 bcopy(ip, mtod(m, caddr_t),
 315                                         sizeof(struct ip));
 316                         }
 317                         ip = mtod(m, struct ip *);
 318                         memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
 319                         ip->ip_len = ntohs(ip->ip_len) + msiz;
 320                 } else {  /* AF_INET */
 321                         IF_DROP(&ifp->if_snd);
 322                         m_freem(m);
 323                         error = EINVAL;
 324                         goto end;
 325                 }
 326         } else if (sc->g_proto == IPPROTO_GRE) {
 327                 switch (dst->sa_family) {
 328                 case AF_INET:
 329                         ip = mtod(m, struct ip *);
 330                         etype = ETHERTYPE_IP;
 331                         break;
 332 #ifdef NETATALK
 333                 case AF_APPLETALK:
 334                         etype = ETHERTYPE_ATALK;
 335                         break;
 336 #endif
 337 #ifdef NS
 338                 case AF_NS:
 339                         etype = ETHERTYPE_NS;
 340                         break;
 341 #endif
 342                 default:
 343                         IF_DROP(&ifp->if_snd);
 344                         m_freem(m);
 345                         error = EAFNOSUPPORT;
 346                         goto end;
 347                 }
 348                 M_PREPEND(m, sizeof(struct greip), MB_DONTWAIT);
 349         } else {
 350                 IF_DROP(&ifp->if_snd);
 351                 m_freem(m);
 352                 error = EINVAL;
 353                 goto end;
 354         }
 355
 356         if (m == NULL) {        /* impossible */
 357                 IF_DROP(&ifp->if_snd);
 358                 error = ENOBUFS;
 359                 goto end;
 360         }
 361
 362         gh = mtod(m, struct greip *);
 363         if (sc->g_proto == IPPROTO_GRE) {
 364                 /* we don't have any GRE flags for now */
 365
 366                 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h));
 367                 gh->gi_ptype = htons(etype);
 368         }
 369
 370         gh->gi_pr = sc->g_proto;
 371         if (sc->g_proto != IPPROTO_MOBILE) {
 372                 gh->gi_src = sc->g_src;
 373                 gh->gi_dst = sc->g_dst;
 374                 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
 375                 ((struct ip*)gh)->ip_ttl = GRE_TTL;
 376                 ((struct ip*)gh)->ip_tos = ip->ip_tos;
 377                 ((struct ip*)gh)->ip_id = ip->ip_id;
 378                 gh->gi_len = m->m_pkthdr.len;
 379         }
 380
 381         ifp->if_opackets++;
 382         ifp->if_obytes += m->m_pkthdr.len;
 383         /* send it off */
 384         error = ip_output(m, NULL, &sc->route, 0, NULL, NULL);
 385   end:
 386         sc->called = 0;
 387         if (error)
 388                 ifp->if_oerrors++;
 389         return (error);
 390 }
 391
 392 static int
 393 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 394            struct rtentry *rt)
 395 {
 396         int error;
 397
 398         ifnet_serialize_tx(ifp);
 399         error = gre_output_serialized(ifp, m, dst, rt);
 400         ifnet_deserialize_tx(ifp);
 401
 402         return error;
 403 }
 404
 405 static int
 406 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 407 {
 408         struct ifreq *ifr = (struct ifreq *)data;
 409         struct if_laddrreq *lifr = (struct if_laddrreq *)data;
 410         struct in_aliasreq *aifr = (struct in_aliasreq *)data;
 411         struct gre_softc *sc = ifp->if_softc;
 412         struct sockaddr_in si;
 413         struct sockaddr *sa = NULL;
 414         int error;
 415         struct sockaddr_in sp, sm, dp, dm;
 416
 417         error = 0;
 418
 419         crit_enter();
 420         switch (cmd) {
 421         case SIOCSIFADDR:
 422                 ifp->if_flags |= IFF_UP;
 423                 break;
 424         case SIOCSIFDSTADDR:
 425                 break;
 426         case SIOCSIFFLAGS:
 427                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 428                         break;
 429                 if ((ifr->ifr_flags & IFF_LINK0) != 0)
 430                         sc->g_proto = IPPROTO_GRE;
 431                 else
 432                         sc->g_proto = IPPROTO_MOBILE;
 433                 goto recompute;
 434         case SIOCSIFMTU:
 435                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 436                         break;
 437                 if (ifr->ifr_mtu < 576) {
 438                         error = EINVAL;
 439                         break;
 440                 }
 441                 ifp->if_mtu = ifr->ifr_mtu;
 442                 break;
 443         case SIOCGIFMTU:
 444                 ifr->ifr_mtu = sc->sc_if.if_mtu;
 445                 break;
 446         case SIOCADDMULTI:
 447         case SIOCDELMULTI:
 448                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 449                         break;
 450                 if (ifr == 0) {
 451                         error = EAFNOSUPPORT;
 452                         break;
 453                 }
 454                 switch (ifr->ifr_addr.sa_family) {
 455 #ifdef INET
 456                 case AF_INET:
 457                         break;
 458 #endif
 459                 default:
 460                         error = EAFNOSUPPORT;
 461                         break;
 462                 }
 463                 break;
 464         case GRESPROTO:
 465                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 466                         break;
 467                 sc->g_proto = ifr->ifr_flags;
 468                 switch (sc->g_proto) {
 469                 case IPPROTO_GRE:
 470                         ifp->if_flags |= IFF_LINK0;
 471                         break;
 472                 case IPPROTO_MOBILE:
 473                         ifp->if_flags &= ~IFF_LINK0;
 474                         break;
 475                 default:
 476                         error = EPROTONOSUPPORT;
 477                         break;
 478                 }
 479                 goto recompute;
 480         case GREGPROTO:
 481                 ifr->ifr_flags = sc->g_proto;
 482                 break;
 483         case GRESADDRS:
 484         case GRESADDRD:
 485                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 486                         break;
 487                 /*
 488                  * set tunnel endpoints, compute a less specific route
 489                  * to the remote end and mark if as up
 490                  */
 491                 sa = &ifr->ifr_addr;
 492                 if (cmd == GRESADDRS)
 493                         sc->g_src = (satosin(sa))->sin_addr;
 494                 if (cmd == GRESADDRD)
 495                         sc->g_dst = (satosin(sa))->sin_addr;
 496         recompute:
 497 #ifdef INET
 498                 if (sc->encap != NULL) {
 499                         encap_detach(sc->encap);
 500                         sc->encap = NULL;
 501                 }
 502 #endif
 503                 if ((sc->g_src.s_addr != INADDR_ANY) &&
 504                     (sc->g_dst.s_addr != INADDR_ANY)) {
 505                         bzero(&sp, sizeof(sp));
 506                         bzero(&sm, sizeof(sm));
 507                         bzero(&dp, sizeof(dp));
 508                         bzero(&dm, sizeof(dm));
 509                         sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
 510                             sizeof(struct sockaddr_in);
 511                         sp.sin_family = sm.sin_family = dp.sin_family =
 512                             dm.sin_family = AF_INET;
 513                         sp.sin_addr = sc->g_src;
 514                         dp.sin_addr = sc->g_dst;
 515                         sm.sin_addr.s_addr = dm.sin_addr.s_addr =
 516                             INADDR_BROADCAST;
 517 #ifdef INET
 518                         sc->encap = encap_attach(AF_INET, sc->g_proto,
 519                             sintosa(&sp), sintosa(&sm), sintosa(&dp),
 520                             sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
 521                                 &in_gre_protosw : &in_mobile_protosw, sc);
 522                         if (sc->encap == NULL)
 523                                 kprintf("%s: unable to attach encap\n",
 524                                     if_name(&sc->sc_if));
 525 #endif
 526                         if (sc->route.ro_rt != 0) /* free old route */
 527                                 RTFREE(sc->route.ro_rt);
 528                         if (gre_compute_route(sc) == 0)
 529                                 ifp->if_flags |= IFF_RUNNING;
 530                         else
 531                                 ifp->if_flags &= ~IFF_RUNNING;
 532                 }
 533                 break;
 534         case GREGADDRS:
 535                 memset(&si, 0, sizeof(si));
 536                 si.sin_family = AF_INET;
 537                 si.sin_len = sizeof(struct sockaddr_in);
 538                 si.sin_addr.s_addr = sc->g_src.s_addr;
 539                 sa = sintosa(&si);
 540                 ifr->ifr_addr = *sa;
 541                 break;
 542         case GREGADDRD:
 543                 memset(&si, 0, sizeof(si));
 544                 si.sin_family = AF_INET;
 545                 si.sin_len = sizeof(struct sockaddr_in);
 546                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 547                 sa = sintosa(&si);
 548                 ifr->ifr_addr = *sa;
 549                 break;
 550         case SIOCSIFPHYADDR:
 551                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 552                         break;
 553                 if (aifr->ifra_addr.sin_family != AF_INET ||
 554                     aifr->ifra_dstaddr.sin_family != AF_INET) {
 555                         error = EAFNOSUPPORT;
 556                         break;
 557                 }
 558                 if (aifr->ifra_addr.sin_len != sizeof(si) ||
 559                     aifr->ifra_dstaddr.sin_len != sizeof(si)) {
 560                         error = EINVAL;
 561                         break;
 562                 }
 563                 sc->g_src = aifr->ifra_addr.sin_addr;
 564                 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
 565                 goto recompute;
 566         case SIOCSLIFPHYADDR:
 567                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 568                         break;
 569                 if (lifr->addr.ss_family != AF_INET ||
 570                     lifr->dstaddr.ss_family != AF_INET) {
 571                         error = EAFNOSUPPORT;
 572                         break;
 573                 }
 574                 if (lifr->addr.ss_len != sizeof(si) ||
 575                     lifr->dstaddr.ss_len != sizeof(si)) {
 576                         error = EINVAL;
 577                         break;
 578                 }
 579                 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr;
 580                 sc->g_dst =
 581                     (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr;
 582                 goto recompute;
 583         case SIOCDIFPHYADDR:
 584                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 585                         break;
 586                 sc->g_src.s_addr = INADDR_ANY;
 587                 sc->g_dst.s_addr = INADDR_ANY;
 588                 goto recompute;
 589         case SIOCGLIFPHYADDR:
 590                 if (sc->g_src.s_addr == INADDR_ANY ||
 591                     sc->g_dst.s_addr == INADDR_ANY) {
 592                         error = EADDRNOTAVAIL;
 593                         break;
 594                 }
 595                 memset(&si, 0, sizeof(si));
 596                 si.sin_family = AF_INET;
 597                 si.sin_len = sizeof(struct sockaddr_in);
 598                 si.sin_addr.s_addr = sc->g_src.s_addr;
 599                 memcpy(&lifr->addr, &si, sizeof(si));
 600                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 601                 memcpy(&lifr->dstaddr, &si, sizeof(si));
 602                 break;
 603         case SIOCGIFPSRCADDR:
 604                 if (sc->g_src.s_addr == INADDR_ANY) {
 605                         error = EADDRNOTAVAIL;
 606                         break;
 607                 }
 608                 memset(&si, 0, sizeof(si));
 609                 si.sin_family = AF_INET;
 610                 si.sin_len = sizeof(struct sockaddr_in);
 611                 si.sin_addr.s_addr = sc->g_src.s_addr;
 612                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 613                 break;
 614         case SIOCGIFPDSTADDR:
 615                 if (sc->g_dst.s_addr == INADDR_ANY) {
 616                         error = EADDRNOTAVAIL;
 617                         break;
 618                 }
 619                 memset(&si, 0, sizeof(si));
 620                 si.sin_family = AF_INET;
 621                 si.sin_len = sizeof(struct sockaddr_in);
 622                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 623                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 624                 break;
 625         default:
 626                 error = EINVAL;
 627                 break;
 628         }
 629
 630         crit_exit();
 631         return (error);
 632 }
 633
 634 /*
 635  * computes a route to our destination that is not the one
 636  * which would be taken by ip_output(), as this one will loop back to
 637  * us. If the interface is p2p as  a--->b, then a routing entry exists
 638  * If we now send a packet to b (e.g. ping b), this will come down here
 639  * gets src=a, dst=b tacked on and would from ip_ouput() sent back to
 640  * if_gre.
 641  * Goal here is to compute a route to b that is less specific than
 642  * a-->b. We know that this one exists as in normal operation we have
 643  * at least a default route which matches.
 644  */
 645 static int
 646 gre_compute_route(struct gre_softc *sc)
 647 {
 648         struct route *ro;
 649         u_int32_t a, b, c;
 650
 651         ro = &sc->route;
 652
 653         memset(ro, 0, sizeof(struct route));
 654         ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 655         ro->ro_dst.sa_family = AF_INET;
 656         ro->ro_dst.sa_len = sizeof(ro->ro_dst);
 657
 658         /*
 659          * toggle last bit, so our interface is not found, but a less
 660          * specific route. I'd rather like to specify a shorter mask,
 661          * but this is not possible. Should work though. XXX
 662          * there is a simpler way ...
 663          */
 664         if ((sc->sc_if.if_flags & IFF_LINK1) == 0) {
 665                 a = ntohl(sc->g_dst.s_addr);
 666                 b = a & 0x01;
 667                 c = a & 0xfffffffe;
 668                 b = b ^ 0x01;
 669                 a = b | c;
 670                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr
 671                     = htonl(a);
 672         }
 673
 674 #ifdef DIAGNOSTIC
 675         kprintf("%s: searching a route to %s", if_name(&sc->sc_if),
 676             inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
 677 #endif
 678
 679         rtalloc(ro);
 680
 681         /*
 682          * check if this returned a route at all and this route is no
 683          * recursion to ourself
 684          */
 685         if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
 686 #ifdef DIAGNOSTIC
 687                 if (ro->ro_rt == NULL)
 688                         kprintf(" - no route found!\n");
 689                 else
 690                         kprintf(" - route loops back to ourself!\n");
 691 #endif
 692                 return EADDRNOTAVAIL;
 693         }
 694
 695         /*
 696          * now change it back - else ip_output will just drop
 697          * the route and search one to this interface ...
 698          */
 699         if ((sc->sc_if.if_flags & IFF_LINK1) == 0)
 700                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 701
 702 #ifdef DIAGNOSTIC
 703         kprintf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
 704             inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
 705         kprintf("\n");
 706 #endif
 707
 708         return 0;
 709 }
 710
 711 /*
 712  * do a checksum of a buffer - much like in_cksum, which operates on
 713  * mbufs.
 714  */
 715 u_short
 716 gre_in_cksum(u_short *p, u_int len)
 717 {
 718         u_int sum = 0;
 719         int nwords = len >> 1;
 720
 721         while (nwords-- != 0)
 722                 sum += *p++;
 723
 724         if (len & 1) {
 725                 union {
 726                         u_short w;
 727                         u_char c[2];
 728                 } u;
 729                 u.c[0] = *(u_char *)p;
 730                 u.c[1] = 0;
 731                 sum += u.w;
 732         }
 733
 734         /* end-around-carry */
 735         sum = (sum >> 16) + (sum & 0xffff);
 736         sum += (sum >> 16);
 737         return (~sum);
 738 }
 739
 740 static int
 741 gremodevent(module_t mod, int type, void *data)
 742 {
 743
 744         switch (type) {
 745         case MOD_LOAD:
 746                 greattach();
 747                 break;
 748         case MOD_UNLOAD:
 749                 if_clone_detach(&gre_cloner);
 750
 751                 while (!LIST_EMPTY(&gre_softc_list))
 752                         gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if);
 753
 754                 break;
 755         }
 756         return 0;
 757 }
 758
 759 static moduledata_t gre_mod = {
 760         "if_gre",
 761         gremodevent,
 762         0
 763 };
 764
 765 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
 766 MODULE_VERSION(if_gre, 1);