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
   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 "opt_inet.h"
  50
  51 #include <sys/param.h>
  52 #include <sys/kernel.h>
  53 #include <sys/bus.h>
  54 #include <sys/malloc.h>
  55 #include <sys/mbuf.h>
  56 #include <sys/proc.h>
  57 #include <sys/priv.h>
  58 #include <sys/protosw.h>
  59 #include <sys/socket.h>
  60 #include <sys/sockio.h>
  61 #include <sys/sysctl.h>
  62 #include <sys/systm.h>
  63 #include <sys/thread2.h>
  64
  65 #include <net/ethernet.h>
  66 #include <net/if.h>
  67 #include <net/if_types.h>
  68 #include <net/ifq_var.h>
  69 #include <net/route.h>
  70 #include <net/if_clone.h>
  71 #include <net/netmsg2.h>
  72 #include <net/netisr2.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, caddr_t);
 105 static int      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, struct route *);
 114 static int      gre_check_route(struct gre_softc *sc);
 115
 116 static void     greattach(void);
 117
 118 #ifdef INET
 119
 120 extern struct domain inetdomain;
 121
 122 static const struct protosw in_gre_protosw =
 123     {
 124         .pr_type = SOCK_RAW,
 125         .pr_domain = &inetdomain,
 126         .pr_protocol = IPPROTO_GRE,
 127         .pr_flags = PR_ATOMIC|PR_ADDR,
 128
 129         .pr_input = gre_input,
 130         .pr_output = rip_output,
 131         .pr_ctlinput = rip_ctlinput,
 132         .pr_ctloutput = rip_ctloutput,
 133
 134         .pr_ctlport = cpu0_ctlport,
 135         .pr_usrreqs = &rip_usrreqs
 136     };
 137
 138 static const struct protosw in_mobile_protosw =
 139     {
 140         .pr_type = SOCK_RAW,
 141         .pr_domain = &inetdomain,
 142         .pr_protocol = IPPROTO_MOBILE,
 143         .pr_flags = PR_ATOMIC|PR_ADDR,
 144
 145         .pr_input = gre_mobile_input,
 146         .pr_output = rip_output,
 147         .pr_ctlinput = rip_ctlinput,
 148         .pr_ctloutput = rip_ctloutput,
 149
 150         .pr_ctlport = cpu0_ctlport,
 151         .pr_usrreqs = &rip_usrreqs
 152     };
 153
 154 #endif
 155
 156 SYSCTL_DECL(_net_link);
 157 SYSCTL_NODE(_net_link, IFT_OTHER, gre, CTLFLAG_RW, 0,
 158     "Generic Routing Encapsulation");
 159 #ifndef MAX_GRE_NEST
 160 /*
 161  * This macro controls the default upper limitation on nesting of gre tunnels.
 162  * Since, setting a large value to this macro with a careless configuration
 163  * may introduce system crash, we don't allow any nestings by default.
 164  * If you need to configure nested gre tunnels, you can define this macro
 165  * in your kernel configuration file.  However, if you do so, please be
 166  * careful to configure the tunnels so that it won't make a loop.
 167  */
 168 #define MAX_GRE_NEST 1
 169 #endif
 170 static int max_gre_nesting = MAX_GRE_NEST;
 171 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
 172     &max_gre_nesting, 0, "Max nested tunnels");
 173
 174 /* ARGSUSED */
 175 static void
 176 greattach(void)
 177 {
 178
 179         LIST_INIT(&gre_softc_list);
 180         if_clone_attach(&gre_cloner);
 181 }
 182
 183 static int
 184 gre_clone_create(struct if_clone *ifc, int unit, caddr_t param __unused)
 185 {
 186         struct gre_softc *sc;
 187
 188         sc = kmalloc(sizeof(struct gre_softc), M_GRE, M_WAITOK);
 189         memset(sc, 0, sizeof(struct gre_softc));
 190
 191         sc->sc_if.if_softc = sc;
 192         if_initname(&(sc->sc_if), GRENAME, unit);
 193         ifq_set_maxlen(&sc->sc_if.if_snd, IFQ_MAXLEN);
 194         sc->sc_if.if_type = IFT_OTHER;
 195         sc->sc_if.if_addrlen = 0;
 196         sc->sc_if.if_hdrlen = 24; /* IP + GRE */
 197         sc->sc_if.if_mtu = GREMTU;
 198         sc->sc_if.if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
 199         sc->sc_if.if_output = gre_output;
 200         sc->sc_if.if_ioctl = gre_ioctl;
 201         sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
 202         sc->g_proto = IPPROTO_GRE;
 203         sc->sc_if.if_flags |= IFF_LINK0;
 204         sc->encap = NULL;
 205         sc->called = 0;
 206         sc->route_pcpu = kmalloc(netisr_ncpus * sizeof(struct route), M_GRE,
 207             M_WAITOK | M_ZERO);
 208         if_attach(&sc->sc_if, NULL);
 209         bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t));
 210         LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
 211         return (0);
 212 }
 213
 214 static int
 215 gre_clone_destroy(struct ifnet *ifp)
 216 {
 217         struct gre_softc *sc = ifp->if_softc;
 218         int cpu;
 219
 220 #ifdef INET
 221         if (sc->encap != NULL)
 222                 encap_detach(sc->encap);
 223 #endif
 224         LIST_REMOVE(sc, sc_list);
 225         bpfdetach(ifp);
 226         if_detach(ifp);
 227
 228         for (cpu = 0; cpu < netisr_ncpus; ++cpu) {
 229                 if (sc->route_pcpu[cpu].ro_rt != NULL) {
 230                         rtfree_async(sc->route_pcpu[cpu].ro_rt);
 231                         sc->route_pcpu[cpu].ro_rt = NULL;
 232                 }
 233         }
 234         kfree(sc->route_pcpu, M_GRE);
 235         kfree(sc, M_GRE);
 236
 237         return 0;
 238 }
 239
 240 /*
 241  * The output routine. Takes a packet and encapsulates it in the protocol
 242  * given by sc->g_proto. See also RFC 1701 and RFC 2004
 243  */
 244 static int
 245 gre_output_serialized(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 246                       struct rtentry *rt)
 247 {
 248         int error = 0;
 249         struct gre_softc *sc = ifp->if_softc;
 250         struct greip *gh;
 251         struct ip *ip;
 252         u_short etype = 0;
 253         struct mobile_h mob_h;
 254         struct route *ro;
 255         struct sockaddr_in *ro_dst;
 256
 257         ASSERT_NETISR_NCPUS(mycpuid);
 258
 259         /*
 260          * gre may cause infinite recursion calls when misconfigured.
 261          * We'll prevent this by introducing upper limit.
 262          */
 263         if (++(sc->called) > max_gre_nesting) {
 264                 kprintf("%s: gre_output: recursively called too many "
 265                        "times(%d)\n", if_name(&sc->sc_if), sc->called);
 266                 m_freem(m);
 267                 error = EIO;    /* is there better errno? */
 268                 goto end;
 269         }
 270
 271         if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) == 0 ||
 272             sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
 273                 m_freem(m);
 274                 error = ENETDOWN;
 275                 goto end;
 276         }
 277
 278         ro = &sc->route_pcpu[mycpuid];
 279         ro_dst = (struct sockaddr_in *)&ro->ro_dst;
 280         if (ro->ro_rt != NULL &&
 281             ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
 282              ro_dst->sin_addr.s_addr != sc->g_dst.s_addr)) {
 283                 RTFREE(ro->ro_rt);
 284                 ro->ro_rt = NULL;
 285         }
 286         if (ro->ro_rt == NULL) {
 287                 error = gre_compute_route(sc, ro);
 288                 if (error) {
 289                         m_freem(m);
 290                         goto end;
 291                 }
 292         }
 293
 294         gh = NULL;
 295         ip = NULL;
 296
 297         if (ifp->if_bpf) {
 298                 bpf_gettoken();
 299                 if (ifp->if_bpf) {
 300                         uint32_t af = dst->sa_family;
 301
 302                         bpf_ptap(ifp->if_bpf, m, &af, sizeof(af));
 303                 }
 304                 bpf_reltoken();
 305         }
 306
 307         m->m_flags &= ~(M_BCAST|M_MCAST);
 308
 309         if (sc->g_proto == IPPROTO_MOBILE) {
 310                 if (dst->sa_family == AF_INET) {
 311                         struct mbuf *m0;
 312                         int msiz;
 313
 314                         ip = mtod(m, struct ip *);
 315
 316                         /*
 317                          * RFC2004 specifies that fragmented datagrams shouldn't
 318                          * be encapsulated.
 319                          */
 320                         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 321                                 m_freem(m);
 322                                 error = EINVAL;    /* is there better errno? */
 323                                 goto end;
 324                         }
 325                         memset(&mob_h, 0, MOB_H_SIZ_L);
 326                         mob_h.proto = (ip->ip_p) << 8;
 327                         mob_h.odst = ip->ip_dst.s_addr;
 328                         ip->ip_dst.s_addr = sc->g_dst.s_addr;
 329
 330                         /*
 331                          * If the packet comes from our host, we only change
 332                          * the destination address in the IP header.
 333                          * Else we also need to save and change the source
 334                          */
 335                         if (in_hosteq(ip->ip_src, sc->g_src)) {
 336                                 msiz = MOB_H_SIZ_S;
 337                         } else {
 338                                 mob_h.proto |= MOB_H_SBIT;
 339                                 mob_h.osrc = ip->ip_src.s_addr;
 340                                 ip->ip_src.s_addr = sc->g_src.s_addr;
 341                                 msiz = MOB_H_SIZ_L;
 342                         }
 343                         mob_h.proto = htons(mob_h.proto);
 344                         mob_h.hcrc = gre_in_cksum((u_short *)&mob_h, msiz);
 345
 346                         if ((m->m_data - msiz) < m->m_pktdat) {
 347                                 /* need new mbuf */
 348                                 MGETHDR(m0, M_NOWAIT, MT_HEADER);
 349                                 if (m0 == NULL) {
 350                                         m_freem(m);
 351                                         error = ENOBUFS;
 352                                         goto end;
 353                                 }
 354                                 m0->m_next = m;
 355                                 m->m_data += sizeof(struct ip);
 356                                 m->m_len -= sizeof(struct ip);
 357                                 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
 358                                 m0->m_len = msiz + sizeof(struct ip);
 359                                 m0->m_data += max_linkhdr;
 360                                 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
 361                                        sizeof(struct ip));
 362                                 m = m0;
 363                         } else {  /* we have some space left in the old one */
 364                                 m->m_data -= msiz;
 365                                 m->m_len += msiz;
 366                                 m->m_pkthdr.len += msiz;
 367                                 bcopy(ip, mtod(m, caddr_t),
 368                                         sizeof(struct ip));
 369                         }
 370                         ip = mtod(m, struct ip *);
 371                         memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
 372                         ip->ip_len = ntohs(ip->ip_len) + msiz;
 373                 } else {  /* AF_INET */
 374                         m_freem(m);
 375                         error = EINVAL;
 376                         goto end;
 377                 }
 378         } else if (sc->g_proto == IPPROTO_GRE) {
 379                 switch (dst->sa_family) {
 380                 case AF_INET:
 381                         ip = mtod(m, struct ip *);
 382                         etype = ETHERTYPE_IP;
 383                         break;
 384                 default:
 385                         m_freem(m);
 386                         error = EAFNOSUPPORT;
 387                         goto end;
 388                 }
 389                 M_PREPEND(m, sizeof(struct greip), M_NOWAIT);
 390         } else {
 391                 m_freem(m);
 392                 error = EINVAL;
 393                 goto end;
 394         }
 395
 396         if (m == NULL) {        /* impossible */
 397                 error = ENOBUFS;
 398                 goto end;
 399         }
 400
 401         gh = mtod(m, struct greip *);
 402         if (sc->g_proto == IPPROTO_GRE) {
 403                 /* we don't have any GRE flags for now */
 404
 405                 memset((void *)&gh->gi_g, 0, sizeof(struct gre_h));
 406                 gh->gi_ptype = htons(etype);
 407         }
 408
 409         gh->gi_pr = sc->g_proto;
 410         if (sc->g_proto != IPPROTO_MOBILE) {
 411                 gh->gi_src = sc->g_src;
 412                 gh->gi_dst = sc->g_dst;
 413                 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
 414                 ((struct ip*)gh)->ip_ttl = GRE_TTL;
 415                 ((struct ip*)gh)->ip_tos = ip->ip_tos;
 416                 ((struct ip*)gh)->ip_id = ip->ip_id;
 417                 gh->gi_len = m->m_pkthdr.len;
 418         }
 419
 420         IFNET_STAT_INC(ifp, opackets, 1);
 421         IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
 422         /* send it off */
 423         error = ip_output(m, NULL, ro, IP_DEBUGROUTE, NULL, NULL);
 424   end:
 425         sc->called = 0;
 426         if (error)
 427                 IFNET_STAT_INC(ifp, oerrors, 1);
 428         return (error);
 429 }
 430
 431 static int
 432 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 433            struct rtentry *rt)
 434 {
 435         struct ifaltq_subque *ifsq = ifq_get_subq_default(&ifp->if_snd);
 436         int error;
 437
 438         ifsq_serialize_hw(ifsq);
 439         error = gre_output_serialized(ifp, m, dst, rt);
 440         ifsq_deserialize_hw(ifsq);
 441
 442         return error;
 443 }
 444
 445 static int
 446 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 447 {
 448         struct ifreq *ifr = (struct ifreq *)data;
 449         struct if_laddrreq *lifr = (struct if_laddrreq *)data;
 450         struct in_aliasreq *aifr = (struct in_aliasreq *)data;
 451         struct gre_softc *sc = ifp->if_softc;
 452         struct sockaddr_in si;
 453         struct sockaddr *sa = NULL;
 454         int error;
 455         struct sockaddr_in sp, sm, dp, dm;
 456
 457         error = 0;
 458
 459         crit_enter();
 460         switch (cmd) {
 461         case SIOCSIFADDR:
 462                 ifp->if_flags |= IFF_UP;
 463                 break;
 464         case SIOCSIFDSTADDR:
 465                 break;
 466         case SIOCSIFFLAGS:
 467                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 468                         break;
 469                 if ((ifr->ifr_flags & IFF_LINK0) != 0)
 470                         sc->g_proto = IPPROTO_GRE;
 471                 else
 472                         sc->g_proto = IPPROTO_MOBILE;
 473                 goto recompute;
 474         case SIOCSIFMTU:
 475                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 476                         break;
 477                 if (ifr->ifr_mtu < 576) {
 478                         error = EINVAL;
 479                         break;
 480                 }
 481                 ifp->if_mtu = ifr->ifr_mtu;
 482                 break;
 483         case SIOCGIFMTU:
 484                 ifr->ifr_mtu = sc->sc_if.if_mtu;
 485                 break;
 486         case SIOCADDMULTI:
 487         case SIOCDELMULTI:
 488                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 489                         break;
 490                 if (ifr == NULL) {
 491                         error = EAFNOSUPPORT;
 492                         break;
 493                 }
 494                 switch (ifr->ifr_addr.sa_family) {
 495 #ifdef INET
 496                 case AF_INET:
 497                         break;
 498 #endif
 499                 default:
 500                         error = EAFNOSUPPORT;
 501                         break;
 502                 }
 503                 break;
 504         case GRESPROTO:
 505                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 506                         break;
 507                 sc->g_proto = ifr->ifr_flags;
 508                 switch (sc->g_proto) {
 509                 case IPPROTO_GRE:
 510                         ifp->if_flags |= IFF_LINK0;
 511                         break;
 512                 case IPPROTO_MOBILE:
 513                         ifp->if_flags &= ~IFF_LINK0;
 514                         break;
 515                 default:
 516                         error = EPROTONOSUPPORT;
 517                         break;
 518                 }
 519                 goto recompute;
 520         case GREGPROTO:
 521                 ifr->ifr_flags = sc->g_proto;
 522                 break;
 523         case GRESADDRS:
 524         case GRESADDRD:
 525                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 526                         break;
 527                 /*
 528                  * set tunnel endpoints, compute a less specific route
 529                  * to the remote end and mark if as up
 530                  */
 531                 sa = &ifr->ifr_addr;
 532                 if (cmd == GRESADDRS)
 533                         sc->g_src = (satosin(sa))->sin_addr;
 534                 if (cmd == GRESADDRD)
 535                         sc->g_dst = (satosin(sa))->sin_addr;
 536         recompute:
 537 #ifdef INET
 538                 if (sc->encap != NULL) {
 539                         encap_detach(sc->encap);
 540                         sc->encap = NULL;
 541                 }
 542 #endif
 543                 if ((sc->g_src.s_addr != INADDR_ANY) &&
 544                     (sc->g_dst.s_addr != INADDR_ANY)) {
 545                         bzero(&sp, sizeof(sp));
 546                         bzero(&sm, sizeof(sm));
 547                         bzero(&dp, sizeof(dp));
 548                         bzero(&dm, sizeof(dm));
 549                         sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
 550                             sizeof(struct sockaddr_in);
 551                         sp.sin_family = sm.sin_family = dp.sin_family =
 552                             dm.sin_family = AF_INET;
 553                         sp.sin_addr = sc->g_src;
 554                         dp.sin_addr = sc->g_dst;
 555                         sm.sin_addr.s_addr = dm.sin_addr.s_addr =
 556                             INADDR_BROADCAST;
 557 #ifdef INET
 558                         sc->encap = encap_attach(AF_INET, sc->g_proto,
 559                             sintosa(&sp), sintosa(&sm), sintosa(&dp),
 560                             sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
 561                                 &in_gre_protosw : &in_mobile_protosw, sc);
 562                         if (sc->encap == NULL)
 563                                 kprintf("%s: unable to attach encap\n",
 564                                     if_name(&sc->sc_if));
 565 #endif
 566                         ifnet_deserialize_all(ifp);
 567                         error = gre_check_route(sc);
 568                         ifnet_serialize_all(ifp);
 569                         if (!error)
 570                                 ifp->if_flags |= IFF_RUNNING;
 571                         else
 572                                 ifp->if_flags &= ~IFF_RUNNING;
 573                 }
 574                 break;
 575         case GREGADDRS:
 576                 memset(&si, 0, sizeof(si));
 577                 si.sin_family = AF_INET;
 578                 si.sin_len = sizeof(struct sockaddr_in);
 579                 si.sin_addr.s_addr = sc->g_src.s_addr;
 580                 sa = sintosa(&si);
 581                 ifr->ifr_addr = *sa;
 582                 break;
 583         case GREGADDRD:
 584                 memset(&si, 0, sizeof(si));
 585                 si.sin_family = AF_INET;
 586                 si.sin_len = sizeof(struct sockaddr_in);
 587                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 588                 sa = sintosa(&si);
 589                 ifr->ifr_addr = *sa;
 590                 break;
 591         case SIOCSIFPHYADDR:
 592                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 593                         break;
 594                 if (aifr->ifra_addr.sin_family != AF_INET ||
 595                     aifr->ifra_dstaddr.sin_family != AF_INET) {
 596                         error = EAFNOSUPPORT;
 597                         break;
 598                 }
 599                 if (aifr->ifra_addr.sin_len != sizeof(si) ||
 600                     aifr->ifra_dstaddr.sin_len != sizeof(si)) {
 601                         error = EINVAL;
 602                         break;
 603                 }
 604                 sc->g_src = aifr->ifra_addr.sin_addr;
 605                 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
 606                 goto recompute;
 607         case SIOCSLIFPHYADDR:
 608                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 609                         break;
 610                 if (lifr->addr.ss_family != AF_INET ||
 611                     lifr->dstaddr.ss_family != AF_INET) {
 612                         error = EAFNOSUPPORT;
 613                         break;
 614                 }
 615                 if (lifr->addr.ss_len != sizeof(si) ||
 616                     lifr->dstaddr.ss_len != sizeof(si)) {
 617                         error = EINVAL;
 618                         break;
 619                 }
 620                 sc->g_src = (satosin((struct sockadrr *)&lifr->addr))->sin_addr;
 621                 sc->g_dst =
 622                     (satosin((struct sockadrr *)&lifr->dstaddr))->sin_addr;
 623                 goto recompute;
 624         case SIOCDIFPHYADDR:
 625                 if ((error = priv_check_cred(cr, PRIV_ROOT, NULL_CRED_OKAY)) != 0)
 626                         break;
 627                 sc->g_src.s_addr = INADDR_ANY;
 628                 sc->g_dst.s_addr = INADDR_ANY;
 629                 goto recompute;
 630         case SIOCGLIFPHYADDR:
 631                 if (sc->g_src.s_addr == INADDR_ANY ||
 632                     sc->g_dst.s_addr == INADDR_ANY) {
 633                         error = EADDRNOTAVAIL;
 634                         break;
 635                 }
 636                 memset(&si, 0, sizeof(si));
 637                 si.sin_family = AF_INET;
 638                 si.sin_len = sizeof(struct sockaddr_in);
 639                 si.sin_addr.s_addr = sc->g_src.s_addr;
 640                 memcpy(&lifr->addr, &si, sizeof(si));
 641                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 642                 memcpy(&lifr->dstaddr, &si, sizeof(si));
 643                 break;
 644         case SIOCGIFPSRCADDR:
 645                 if (sc->g_src.s_addr == INADDR_ANY) {
 646                         error = EADDRNOTAVAIL;
 647                         break;
 648                 }
 649                 memset(&si, 0, sizeof(si));
 650                 si.sin_family = AF_INET;
 651                 si.sin_len = sizeof(struct sockaddr_in);
 652                 si.sin_addr.s_addr = sc->g_src.s_addr;
 653                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 654                 break;
 655         case SIOCGIFPDSTADDR:
 656                 if (sc->g_dst.s_addr == INADDR_ANY) {
 657                         error = EADDRNOTAVAIL;
 658                         break;
 659                 }
 660                 memset(&si, 0, sizeof(si));
 661                 si.sin_family = AF_INET;
 662                 si.sin_len = sizeof(struct sockaddr_in);
 663                 si.sin_addr.s_addr = sc->g_dst.s_addr;
 664                 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
 665                 break;
 666         default:
 667                 error = EINVAL;
 668                 break;
 669         }
 670
 671         crit_exit();
 672         return (error);
 673 }
 674
 675 /*
 676  * computes a route to our destination that is not the one
 677  * which would be taken by ip_output(), as this one will loop back to
 678  * us. If the interface is p2p as  a--->b, then a routing entry exists
 679  * If we now send a packet to b (e.g. ping b), this will come down here
 680  * gets src=a, dst=b tacked on and would from ip_ouput() sent back to
 681  * if_gre.
 682  * Goal here is to compute a route to b that is less specific than
 683  * a-->b. We know that this one exists as in normal operation we have
 684  * at least a default route which matches.
 685  */
 686 static int
 687 gre_compute_route(struct gre_softc *sc, struct route *ro)
 688 {
 689 #ifdef DIAGNOSTIC
 690         char abuf[INET_ADDRSTRLEN];
 691 #endif
 692         u_int32_t a, b, c;
 693
 694         ASSERT_NETISR_NCPUS(mycpuid);
 695         KASSERT(ro == &sc->route_pcpu[mycpuid], ("route mismatch"));
 696         KASSERT(ro->ro_rt == NULL, ("rtentry not freed"));
 697
 698         memset(ro, 0, sizeof(struct route));
 699         ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 700         ro->ro_dst.sa_family = AF_INET;
 701         ro->ro_dst.sa_len = sizeof(ro->ro_dst);
 702
 703         /*
 704          * toggle last bit, so our interface is not found, but a less
 705          * specific route. I'd rather like to specify a shorter mask,
 706          * but this is not possible. Should work though. XXX
 707          * there is a simpler way ...
 708          */
 709         if ((sc->sc_if.if_flags & IFF_LINK1) == 0) {
 710                 a = ntohl(sc->g_dst.s_addr);
 711                 b = a & 0x01;
 712                 c = a & 0xfffffffe;
 713                 b = b ^ 0x01;
 714                 a = b | c;
 715                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr
 716                     = htonl(a);
 717         }
 718
 719 #ifdef DIAGNOSTIC
 720         kprintf("%s: searching a route to %s", if_name(&sc->sc_if),
 721             kinet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr, abuf));
 722 #endif
 723
 724         rtalloc(ro);
 725
 726         /*
 727          * check if this returned a route at all and this route is no
 728          * recursion to ourself
 729          */
 730         if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
 731 #ifdef DIAGNOSTIC
 732                 if (ro->ro_rt == NULL)
 733                         kprintf(" - no route found!\n");
 734                 else
 735                         kprintf(" - route loops back to ourself!\n");
 736 #endif
 737                 return EADDRNOTAVAIL;
 738         }
 739
 740         /*
 741          * now change it back - else ip_output will just drop
 742          * the route and search one to this interface ...
 743          */
 744         if ((sc->sc_if.if_flags & IFF_LINK1) == 0)
 745                 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
 746
 747 #ifdef DIAGNOSTIC
 748         kprintf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
 749             kinet_ntoa(
 750                 ((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr, abuf));
 751         kprintf("\n");
 752 #endif
 753
 754         return 0;
 755 }
 756
 757 static void
 758 gre_check_route_handler(netmsg_t msg)
 759 {
 760         struct gre_softc *sc = msg->base.lmsg.u.ms_resultp;
 761         struct route *ro;
 762         int error;
 763
 764         ASSERT_NETISR0;
 765
 766         ro = &sc->route_pcpu[mycpuid];
 767         if (ro->ro_rt != NULL) {
 768                 RTFREE(ro->ro_rt);
 769                 ro->ro_rt = NULL;
 770         }
 771         error = gre_compute_route(sc, ro);
 772
 773         netisr_replymsg(&msg->base, error);
 774 }
 775
 776 static int
 777 gre_check_route(struct gre_softc *sc)
 778 {
 779         struct netmsg_base msg;
 780
 781         netmsg_init(&msg, NULL, &curthread->td_msgport, MSGF_PRIORITY,
 782             gre_check_route_handler);
 783         msg.lmsg.u.ms_resultp = sc;
 784
 785         return (netisr_domsg(&msg, 0));
 786 }
 787
 788 /*
 789  * do a checksum of a buffer - much like in_cksum, which operates on
 790  * mbufs.
 791  */
 792 u_short
 793 gre_in_cksum(u_short *p, u_int len)
 794 {
 795         u_int sum = 0;
 796         int nwords = len >> 1;
 797
 798         while (nwords-- != 0)
 799                 sum += *p++;
 800
 801         if (len & 1) {
 802                 union {
 803                         u_short w;
 804                         u_char c[2];
 805                 } u;
 806                 u.c[0] = *(u_char *)p;
 807                 u.c[1] = 0;
 808                 sum += u.w;
 809         }
 810
 811         /* end-around-carry */
 812         sum = (sum >> 16) + (sum & 0xffff);
 813         sum += (sum >> 16);
 814         return (~sum);
 815 }
 816
 817 static int
 818 gremodevent(module_t mod, int type, void *data)
 819 {
 820
 821         switch (type) {
 822         case MOD_LOAD:
 823                 greattach();
 824                 break;
 825         case MOD_UNLOAD:
 826                 if_clone_detach(&gre_cloner);
 827
 828                 while (!LIST_EMPTY(&gre_softc_list))
 829                         gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if);
 830
 831                 break;
 832         }
 833         return 0;
 834 }
 835
 836 static moduledata_t gre_mod = {
 837         "if_gre",
 838         gremodevent,
 839         0
 840 };
 841
 842 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
 843 MODULE_VERSION(if_gre, 1);