sys/net/tun/if_tun.c

   1 /*      $NetBSD: if_tun.c,v 1.14 1994/06/29 06:36:25 cgd Exp $  */
   2
   3 /*
   4  * Copyright (c) 1988, Julian Onions <jpo@cs.nott.ac.uk>
   5  * Nottingham University 1987.
   6  *
   7  * This source may be freely distributed, however I would be interested
   8  * in any changes that are made.
   9  *
  10  * This driver takes packets off the IP i/f and hands them up to a
  11  * user process to have its wicked way with. This driver has it's
  12  * roots in a similar driver written by Phil Cockcroft (formerly) at
  13  * UCL. This driver is based much more on read/write/poll mode of
  14  * operation though.
  15  *
  16  * $FreeBSD: src/sys/net/if_tun.c,v 1.74.2.8 2002/02/13 00:43:11 dillon Exp $
  17  */
  18
  19 #include "use_tun.h"
  20 #include "opt_atalk.h"
  21 #include "opt_inet.h"
  22 #include "opt_inet6.h"
  23 #include "opt_ipx.h"
  24
  25 #include <sys/param.h>
  26 #include <sys/proc.h>
  27 #include <sys/priv.h>
  28 #include <sys/systm.h>
  29 #include <sys/mbuf.h>
  30 #include <sys/socket.h>
  31 #include <sys/conf.h>
  32 #include <sys/device.h>
  33 #include <sys/filio.h>
  34 #include <sys/sockio.h>
  35 #include <sys/thread2.h>
  36 #include <sys/ttycom.h>
  37 #include <sys/signalvar.h>
  38 #include <sys/filedesc.h>
  39 #include <sys/kernel.h>
  40 #include <sys/sysctl.h>
  41 #include <sys/uio.h>
  42 #include <sys/vnode.h>
  43 #include <sys/malloc.h>
  44
  45 #include <sys/mplock2.h>
  46
  47 #include <net/if.h>
  48 #include <net/if_types.h>
  49 #include <net/ifq_var.h>
  50 #include <net/netisr.h>
  51 #include <net/route.h>
  52 #include <sys/devfs.h>
  53
  54 #ifdef INET
  55 #include <netinet/in.h>
  56 #endif
  57
  58 #include <net/bpf.h>
  59
  60 #include "if_tunvar.h"
  61 #include "if_tun.h"
  62
  63 static MALLOC_DEFINE(M_TUN, "tun", "Tunnel Interface");
  64
  65 static void tunattach (void *);
  66 PSEUDO_SET(tunattach, if_tun);
  67
  68 static void tuncreate (cdev_t dev);
  69
  70 #define TUNDEBUG        if (tundebug) if_printf
  71 static int tundebug = 0;
  72 SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0,
  73     "Enable debug output");
  74
  75 static int tunoutput (struct ifnet *, struct mbuf *, struct sockaddr *,
  76             struct rtentry *rt);
  77 static int tunifioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
  78 static int tuninit (struct ifnet *);
  79 static void tunstart(struct ifnet *);
  80 static void tun_filter_detach(struct knote *);
  81 static int tun_filter_read(struct knote *, long);
  82 static int tun_filter_write(struct knote *, long);
  83
  84 static  d_open_t        tunopen;
  85 static  d_close_t       tunclose;
  86 static  d_read_t        tunread;
  87 static  d_write_t       tunwrite;
  88 static  d_ioctl_t       tunioctl;
  89 static  d_kqfilter_t    tunkqfilter;
  90
  91 static d_clone_t tunclone;
  92 DEVFS_DECLARE_CLONE_BITMAP(tun);
  93
  94 #if NTUN <= 1
  95 #define TUN_PREALLOCATED_UNITS  4
  96 #else
  97 #define TUN_PREALLOCATED_UNITS  NTUN
  98 #endif
  99
 100 static struct dev_ops tun_ops = {
 101         { "tun", 0, 0 },
 102         .d_open =       tunopen,
 103         .d_close =      tunclose,
 104         .d_read =       tunread,
 105         .d_write =      tunwrite,
 106         .d_ioctl =      tunioctl,
 107         .d_kqfilter =   tunkqfilter
 108 };
 109
 110 static void
 111 tunattach(void *dummy)
 112 {
 113         int i;
 114         make_autoclone_dev(&tun_ops, &DEVFS_CLONE_BITMAP(tun),
 115                 tunclone, UID_UUCP, GID_DIALER, 0600, "tun");
 116         for (i = 0; i < TUN_PREALLOCATED_UNITS; i++) {
 117                 make_dev(&tun_ops, i, UID_UUCP, GID_DIALER, 0600, "tun%d", i);
 118                 devfs_clone_bitmap_set(&DEVFS_CLONE_BITMAP(tun), i);
 119         }
 120         /* Doesn't need uninit because unloading is not possible, see PSEUDO_SET */
 121 }
 122
 123 static int
 124 tunclone(struct dev_clone_args *ap)
 125 {
 126         int unit;
 127
 128         unit = devfs_clone_bitmap_get(&DEVFS_CLONE_BITMAP(tun), 0);
 129         ap->a_dev = make_only_dev(&tun_ops, unit, UID_UUCP, GID_DIALER, 0600,
 130                                                                 "tun%d", unit);
 131
 132         return 0;
 133 }
 134
 135 static void
 136 tuncreate(cdev_t dev)
 137 {
 138         struct tun_softc *sc;
 139         struct ifnet *ifp;
 140
 141 #if 0
 142         dev = make_dev(&tun_ops, minor(dev),
 143             UID_UUCP, GID_DIALER, 0600, "tun%d", lminor(dev));
 144 #endif
 145
 146         MALLOC(sc, struct tun_softc *, sizeof(*sc), M_TUN, M_WAITOK | M_ZERO);
 147         sc->tun_flags = TUN_INITED;
 148
 149         ifp = &sc->tun_if;
 150         if_initname(ifp, "tun", lminor(dev));
 151         ifp->if_mtu = TUNMTU;
 152         ifp->if_ioctl = tunifioctl;
 153         ifp->if_output = tunoutput;
 154         ifp->if_start = tunstart;
 155         ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
 156         ifp->if_type = IFT_PPP;
 157         ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
 158         ifq_set_ready(&ifp->if_snd);
 159         ifp->if_softc = sc;
 160         if_attach(ifp, NULL);
 161         bpfattach(ifp, DLT_NULL, sizeof(u_int));
 162         dev->si_drv1 = sc;
 163 }
 164
 165 /*
 166  * tunnel open - must be superuser & the device must be
 167  * configured in
 168  */
 169 static  int
 170 tunopen(struct dev_open_args *ap)
 171 {
 172         cdev_t dev = ap->a_head.a_dev;
 173         struct ifnet    *ifp;
 174         struct tun_softc *tp;
 175         int     error;
 176
 177         if ((error = priv_check_cred(ap->a_cred, PRIV_ROOT, 0)) != 0)
 178                 return (error);
 179
 180         tp = dev->si_drv1;
 181         if (!tp) {
 182                 tuncreate(dev);
 183                 tp = dev->si_drv1;
 184         }
 185         if (tp->tun_flags & TUN_OPEN)
 186                 return EBUSY;
 187         tp->tun_pid = curproc->p_pid;
 188         ifp = &tp->tun_if;
 189         tp->tun_flags |= TUN_OPEN;
 190         TUNDEBUG(ifp, "open\n");
 191         return (0);
 192 }
 193
 194 /*
 195  * tunclose - close the device - mark i/f down & delete
 196  * routing info
 197  */
 198 static  int
 199 tunclose(struct dev_close_args *ap)
 200 {
 201         cdev_t dev = ap->a_head.a_dev;
 202         struct tun_softc *tp;
 203         struct ifnet    *ifp;
 204
 205         tp = dev->si_drv1;
 206         ifp = &tp->tun_if;
 207
 208         tp->tun_flags &= ~TUN_OPEN;
 209         tp->tun_pid = 0;
 210
 211         /* Junk all pending output. */
 212         ifq_purge(&ifp->if_snd);
 213
 214         if (ifp->if_flags & IFF_UP)
 215                 if_down(ifp);
 216         ifp->if_flags &= ~IFF_RUNNING;
 217         if_purgeaddrs_nolink(ifp);
 218
 219         funsetown(tp->tun_sigio);
 220         KNOTE(&tp->tun_rkq.ki_note, 0);
 221
 222         TUNDEBUG(ifp, "closed\n");
 223 #if 0
 224         if (dev->si_uminor >= TUN_PREALLOCATED_UNITS) {
 225                 devfs_clone_bitmap_put(&DEVFS_CLONE_BITMAP(tun), dev->si_uminor);
 226         }
 227 #endif
 228         return (0);
 229 }
 230
 231 static int
 232 tuninit(struct ifnet *ifp)
 233 {
 234         struct tun_softc *tp = ifp->if_softc;
 235         struct ifaddr_container *ifac;
 236         int error = 0;
 237
 238         TUNDEBUG(ifp, "tuninit\n");
 239
 240         ifp->if_flags |= IFF_UP | IFF_RUNNING;
 241         getmicrotime(&ifp->if_lastchange);
 242
 243         TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 244                 struct ifaddr *ifa = ifac->ifa;
 245
 246                 if (ifa->ifa_addr == NULL) {
 247                         error = EFAULT;
 248                         /* XXX: Should maybe return straight off? */
 249                 } else {
 250 #ifdef INET
 251                         if (ifa->ifa_addr->sa_family == AF_INET) {
 252                             struct sockaddr_in *si;
 253
 254                             si = (struct sockaddr_in *)ifa->ifa_addr;
 255                             if (si->sin_addr.s_addr)
 256                                     tp->tun_flags |= TUN_IASET;
 257                         }
 258 #endif
 259                 }
 260         }
 261         return (error);
 262 }
 263
 264 /*
 265  * Process an ioctl request.
 266  *
 267  * MPSAFE
 268  */
 269 int
 270 tunifioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 271 {
 272         struct ifreq *ifr = (struct ifreq *)data;
 273         struct tun_softc *tp = ifp->if_softc;
 274         struct ifstat *ifs;
 275         int error = 0;
 276
 277         switch(cmd) {
 278         case SIOCGIFSTATUS:
 279                 ifs = (struct ifstat *)data;
 280                 if (tp->tun_pid)
 281                         ksprintf(ifs->ascii + strlen(ifs->ascii),
 282                             "\tOpened by PID %d\n", tp->tun_pid);
 283                 break;
 284         case SIOCSIFADDR:
 285                 error = tuninit(ifp);
 286                 TUNDEBUG(ifp, "address set, error=%d\n", error);
 287                 break;
 288         case SIOCSIFDSTADDR:
 289                 error = tuninit(ifp);
 290                 TUNDEBUG(ifp, "destination address set, error=%d\n", error);
 291                 break;
 292         case SIOCSIFMTU:
 293                 ifp->if_mtu = ifr->ifr_mtu;
 294                 TUNDEBUG(ifp, "mtu set\n");
 295                 break;
 296         case SIOCSIFFLAGS:
 297         case SIOCADDMULTI:
 298         case SIOCDELMULTI:
 299                 break;
 300         default:
 301                 error = EINVAL;
 302         }
 303         return (error);
 304 }
 305
 306 /*
 307  * tunoutput - queue packets from higher level ready to put out.
 308  *
 309  * MPSAFE
 310  */
 311 static int
 312 tunoutput_serialized(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 313                      struct rtentry *rt)
 314 {
 315         struct tun_softc *tp = ifp->if_softc;
 316         int error;
 317         struct altq_pktattr pktattr;
 318
 319         TUNDEBUG(ifp, "tunoutput\n");
 320
 321         if ((tp->tun_flags & TUN_READY) != TUN_READY) {
 322                 TUNDEBUG(ifp, "not ready 0%o\n", tp->tun_flags);
 323                 m_freem (m0);
 324                 return EHOSTDOWN;
 325         }
 326
 327         /*
 328          * if the queueing discipline needs packet classification,
 329          * do it before prepending link headers.
 330          */
 331         ifq_classify(&ifp->if_snd, m0, dst->sa_family, &pktattr);
 332
 333         /* BPF write needs to be handled specially */
 334         if (dst->sa_family == AF_UNSPEC) {
 335                 dst->sa_family = *(mtod(m0, int *));
 336                 m0->m_len -= sizeof(int);
 337                 m0->m_pkthdr.len -= sizeof(int);
 338                 m0->m_data += sizeof(int);
 339         }
 340
 341         if (ifp->if_bpf) {
 342                 /*
 343                  * We need to prepend the address family as
 344                  * a four byte field.
 345                  */
 346                 uint32_t af = dst->sa_family;
 347
 348                 bpf_ptap(ifp->if_bpf, m0, &af, sizeof(af));
 349         }
 350
 351         /* prepend sockaddr? this may abort if the mbuf allocation fails */
 352         if (tp->tun_flags & TUN_LMODE) {
 353                 /* allocate space for sockaddr */
 354                 M_PREPEND(m0, dst->sa_len, MB_DONTWAIT);
 355
 356                 /* if allocation failed drop packet */
 357                 if (m0 == NULL){
 358                         IF_DROP(&ifp->if_snd);
 359                         ifp->if_oerrors++;
 360                         return (ENOBUFS);
 361                 } else {
 362                         bcopy(dst, m0->m_data, dst->sa_len);
 363                 }
 364         }
 365
 366         if (tp->tun_flags & TUN_IFHEAD) {
 367                 /* Prepend the address family */
 368                 M_PREPEND(m0, 4, MB_DONTWAIT);
 369
 370                 /* if allocation failed drop packet */
 371                 if (m0 == NULL){
 372                         IF_DROP(&ifp->if_snd);
 373                         ifp->if_oerrors++;
 374                         return ENOBUFS;
 375                 } else
 376                         *(u_int32_t *)m0->m_data = htonl(dst->sa_family);
 377         } else {
 378 #ifdef INET
 379                 if (dst->sa_family != AF_INET)
 380 #endif
 381                 {
 382                         m_freem(m0);
 383                         return EAFNOSUPPORT;
 384                 }
 385         }
 386
 387         error = ifq_handoff(ifp, m0, &pktattr);
 388         if (error) {
 389                 ifp->if_collisions++;
 390         } else {
 391                 ifp->if_opackets++;
 392                 if (tp->tun_flags & TUN_RWAIT) {
 393                         tp->tun_flags &= ~TUN_RWAIT;
 394                         wakeup((caddr_t)tp);
 395                 }
 396                 get_mplock();
 397                 if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
 398                         pgsigio(tp->tun_sigio, SIGIO, 0);
 399                 rel_mplock();
 400                 ifnet_deserialize_all(ifp);
 401                 KNOTE(&tp->tun_rkq.ki_note, 0);
 402                 ifnet_serialize_all(ifp);
 403         }
 404         return (error);
 405 }
 406
 407 static int
 408 tunoutput(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 409           struct rtentry *rt)
 410 {
 411         int error;
 412
 413         ifnet_serialize_all(ifp);
 414         error = tunoutput_serialized(ifp, m0, dst, rt);
 415         ifnet_deserialize_all(ifp);
 416
 417         return error;
 418 }
 419
 420 /*
 421  * the ops interface is now pretty minimal.
 422  */
 423 static  int
 424 tunioctl(struct dev_ioctl_args *ap)
 425 {
 426         cdev_t dev = ap->a_head.a_dev;
 427         struct tun_softc *tp = dev->si_drv1;
 428         struct tuninfo *tunp;
 429
 430         switch (ap->a_cmd) {
 431         case TUNSIFINFO:
 432                 tunp = (struct tuninfo *)ap->a_data;
 433                 if (tunp->mtu < IF_MINMTU)
 434                         return (EINVAL);
 435                 tp->tun_if.if_mtu = tunp->mtu;
 436                 tp->tun_if.if_type = tunp->type;
 437                 tp->tun_if.if_baudrate = tunp->baudrate;
 438                 break;
 439         case TUNGIFINFO:
 440                 tunp = (struct tuninfo *)ap->a_data;
 441                 tunp->mtu = tp->tun_if.if_mtu;
 442                 tunp->type = tp->tun_if.if_type;
 443                 tunp->baudrate = tp->tun_if.if_baudrate;
 444                 break;
 445         case TUNSDEBUG:
 446                 tundebug = *(int *)ap->a_data;
 447                 break;
 448         case TUNGDEBUG:
 449                 *(int *)ap->a_data = tundebug;
 450                 break;
 451         case TUNSLMODE:
 452                 if (*(int *)ap->a_data) {
 453                         tp->tun_flags |= TUN_LMODE;
 454                         tp->tun_flags &= ~TUN_IFHEAD;
 455                 } else
 456                         tp->tun_flags &= ~TUN_LMODE;
 457                 break;
 458         case TUNSIFHEAD:
 459                 if (*(int *)ap->a_data) {
 460                         tp->tun_flags |= TUN_IFHEAD;
 461                         tp->tun_flags &= ~TUN_LMODE;
 462                 } else
 463                         tp->tun_flags &= ~TUN_IFHEAD;
 464                 break;
 465         case TUNGIFHEAD:
 466                 *(int *)ap->a_data = (tp->tun_flags & TUN_IFHEAD) ? 1 : 0;
 467                 break;
 468         case TUNSIFMODE:
 469                 /* deny this if UP */
 470                 if (tp->tun_if.if_flags & IFF_UP)
 471                         return(EBUSY);
 472
 473                 switch (*(int *)ap->a_data & ~IFF_MULTICAST) {
 474                 case IFF_POINTOPOINT:
 475                 case IFF_BROADCAST:
 476                         tp->tun_if.if_flags &= ~(IFF_BROADCAST|IFF_POINTOPOINT);
 477                         tp->tun_if.if_flags |= *(int *)ap->a_data;
 478                         break;
 479                 default:
 480                         return(EINVAL);
 481                 }
 482                 break;
 483         case TUNSIFPID:
 484                 tp->tun_pid = curproc->p_pid;
 485                 break;
 486         case FIOASYNC:
 487                 if (*(int *)ap->a_data)
 488                         tp->tun_flags |= TUN_ASYNC;
 489                 else
 490                         tp->tun_flags &= ~TUN_ASYNC;
 491                 break;
 492         case FIONREAD:
 493                 if (!ifq_is_empty(&tp->tun_if.if_snd)) {
 494                         struct mbuf *mb;
 495
 496                         mb = ifq_poll(&tp->tun_if.if_snd);
 497                         for( *(int *)ap->a_data = 0; mb != 0; mb = mb->m_next)
 498                                 *(int *)ap->a_data += mb->m_len;
 499                 } else {
 500                         *(int *)ap->a_data = 0;
 501                 }
 502                 break;
 503         case FIOSETOWN:
 504                 return (fsetown(*(int *)ap->a_data, &tp->tun_sigio));
 505
 506         case FIOGETOWN:
 507                 *(int *)ap->a_data = fgetown(tp->tun_sigio);
 508                 return (0);
 509
 510         /* This is deprecated, FIOSETOWN should be used instead. */
 511         case TIOCSPGRP:
 512                 return (fsetown(-(*(int *)ap->a_data), &tp->tun_sigio));
 513
 514         /* This is deprecated, FIOGETOWN should be used instead. */
 515         case TIOCGPGRP:
 516                 *(int *)ap->a_data = -fgetown(tp->tun_sigio);
 517                 return (0);
 518
 519         default:
 520                 return (ENOTTY);
 521         }
 522         return (0);
 523 }
 524
 525 /*
 526  * The ops read interface - reads a packet at a time, or at
 527  * least as much of a packet as can be read.
 528  */
 529 static  int
 530 tunread(struct dev_read_args *ap)
 531 {
 532         cdev_t dev = ap->a_head.a_dev;
 533         struct uio *uio = ap->a_uio;
 534         struct tun_softc *tp = dev->si_drv1;
 535         struct ifnet    *ifp = &tp->tun_if;
 536         struct mbuf     *m0;
 537         int             error=0, len;
 538
 539         TUNDEBUG(ifp, "read\n");
 540         if ((tp->tun_flags & TUN_READY) != TUN_READY) {
 541                 TUNDEBUG(ifp, "not ready 0%o\n", tp->tun_flags);
 542                 return EHOSTDOWN;
 543         }
 544
 545         tp->tun_flags &= ~TUN_RWAIT;
 546
 547         ifnet_serialize_all(ifp);
 548
 549         while ((m0 = ifq_dequeue(&ifp->if_snd, NULL)) == NULL) {
 550                 if (ap->a_ioflag & IO_NDELAY) {
 551                         ifnet_deserialize_all(ifp);
 552                         return EWOULDBLOCK;
 553                 }
 554                 tp->tun_flags |= TUN_RWAIT;
 555                 ifnet_deserialize_all(ifp);
 556                 if ((error = tsleep(tp, PCATCH, "tunread", 0)) != 0)
 557                         return error;
 558                 ifnet_serialize_all(ifp);
 559         }
 560
 561         ifnet_deserialize_all(ifp);
 562
 563         while (m0 && uio->uio_resid > 0 && error == 0) {
 564                 len = (int)szmin(uio->uio_resid, m0->m_len);
 565                 if (len != 0)
 566                         error = uiomove(mtod(m0, caddr_t), (size_t)len, uio);
 567                 m0 = m_free(m0);
 568         }
 569
 570         if (m0) {
 571                 TUNDEBUG(ifp, "Dropping mbuf\n");
 572                 m_freem(m0);
 573         }
 574         return error;
 575 }
 576
 577 /*
 578  * the ops write interface - an atomic write is a packet - or else!
 579  */
 580 static  int
 581 tunwrite(struct dev_write_args *ap)
 582 {
 583         cdev_t dev = ap->a_head.a_dev;
 584         struct uio *uio = ap->a_uio;
 585         struct tun_softc *tp = dev->si_drv1;
 586         struct ifnet    *ifp = &tp->tun_if;
 587         struct mbuf     *top, **mp, *m;
 588         int             error=0;
 589         size_t          tlen, mlen;
 590         uint32_t        family;
 591         int             isr;
 592
 593         TUNDEBUG(ifp, "tunwrite\n");
 594
 595         if (uio->uio_resid == 0)
 596                 return 0;
 597
 598         if (uio->uio_resid > TUNMRU) {
 599                 TUNDEBUG(ifp, "len=%zd!\n", uio->uio_resid);
 600                 return EIO;
 601         }
 602         tlen = uio->uio_resid;
 603
 604         /* get a header mbuf */
 605         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 606         if (m == NULL)
 607                 return ENOBUFS;
 608         mlen = MHLEN;
 609
 610         top = 0;
 611         mp = &top;
 612         while (error == 0 && uio->uio_resid > 0) {
 613                 m->m_len = (int)szmin(mlen, uio->uio_resid);
 614                 error = uiomove(mtod (m, caddr_t), (size_t)m->m_len, uio);
 615                 *mp = m;
 616                 mp = &m->m_next;
 617                 if (uio->uio_resid > 0) {
 618                         MGET (m, MB_DONTWAIT, MT_DATA);
 619                         if (m == 0) {
 620                                 error = ENOBUFS;
 621                                 break;
 622                         }
 623                         mlen = MLEN;
 624                 }
 625         }
 626         if (error) {
 627                 if (top)
 628                         m_freem (top);
 629                 ifp->if_ierrors++;
 630                 return error;
 631         }
 632
 633         top->m_pkthdr.len = (int)tlen;
 634         top->m_pkthdr.rcvif = ifp;
 635
 636         if (ifp->if_bpf) {
 637                 if (tp->tun_flags & TUN_IFHEAD) {
 638                         /*
 639                          * Conveniently, we already have a 4-byte address
 640                          * family prepended to our packet !
 641                          * Inconveniently, it's in the wrong byte order !
 642                          */
 643                         if ((top = m_pullup(top, sizeof(family))) == NULL)
 644                                 return ENOBUFS;
 645                         *mtod(top, u_int32_t *) =
 646                             ntohl(*mtod(top, u_int32_t *));
 647                         bpf_mtap(ifp->if_bpf, top);
 648                         *mtod(top, u_int32_t *) =
 649                             htonl(*mtod(top, u_int32_t *));
 650                 } else {
 651                         /*
 652                          * We need to prepend the address family as
 653                          * a four byte field.
 654                          */
 655                         static const uint32_t af = AF_INET;
 656
 657                         bpf_ptap(ifp->if_bpf, top, &af, sizeof(af));
 658                 }
 659         }
 660
 661         if (tp->tun_flags & TUN_IFHEAD) {
 662                 if (top->m_len < sizeof(family) &&
 663                     (top = m_pullup(top, sizeof(family))) == NULL)
 664                                 return ENOBUFS;
 665                 family = ntohl(*mtod(top, u_int32_t *));
 666                 m_adj(top, sizeof(family));
 667         } else
 668                 family = AF_INET;
 669
 670         ifp->if_ibytes += top->m_pkthdr.len;
 671         ifp->if_ipackets++;
 672
 673         switch (family) {
 674 #ifdef INET
 675         case AF_INET:
 676                 isr = NETISR_IP;
 677                 break;
 678 #endif
 679 #ifdef INET6
 680         case AF_INET6:
 681                 isr = NETISR_IPV6;
 682                 break;
 683 #endif
 684 #ifdef IPX
 685         case AF_IPX:
 686                 isr = NETISR_IPX;
 687                 break;
 688 #endif
 689 #ifdef NETATALK
 690         case AF_APPLETALK:
 691                 isr = NETISR_ATALK2;
 692                 break;
 693 #endif
 694         default:
 695                 m_freem(m);
 696                 return (EAFNOSUPPORT);
 697         }
 698
 699         netisr_queue(isr, top);
 700         return (0);
 701 }
 702
 703 static struct filterops tun_read_filtops =
 704         { FILTEROP_ISFD, NULL, tun_filter_detach, tun_filter_read };
 705 static struct filterops tun_write_filtops =
 706         { FILTEROP_ISFD, NULL, tun_filter_detach, tun_filter_write };
 707
 708 static int
 709 tunkqfilter(struct dev_kqfilter_args *ap)
 710 {
 711         cdev_t dev = ap->a_head.a_dev;
 712         struct tun_softc *tp = dev->si_drv1;
 713         struct knote *kn = ap->a_kn;
 714         struct klist *klist;
 715
 716         ap->a_result = 0;
 717         ifnet_serialize_all(&tp->tun_if);
 718
 719         switch (kn->kn_filter) {
 720         case EVFILT_READ:
 721                 kn->kn_fop = &tun_read_filtops;
 722                 kn->kn_hook = (caddr_t)tp;
 723                 break;
 724         case EVFILT_WRITE:
 725                 kn->kn_fop = &tun_write_filtops;
 726                 kn->kn_hook = (caddr_t)tp;
 727                 break;
 728         default:
 729                 ifnet_deserialize_all(&tp->tun_if);
 730                 ap->a_result = EOPNOTSUPP;
 731                 return (0);
 732         }
 733
 734         klist = &tp->tun_rkq.ki_note;
 735         knote_insert(klist, kn);
 736         ifnet_deserialize_all(&tp->tun_if);
 737
 738         return (0);
 739 }
 740
 741 static void
 742 tun_filter_detach(struct knote *kn)
 743 {
 744         struct tun_softc *tp = (struct tun_softc *)kn->kn_hook;
 745         struct klist *klist = &tp->tun_rkq.ki_note;
 746
 747         knote_remove(klist, kn);
 748 }
 749
 750 static int
 751 tun_filter_write(struct knote *kn, long hint)
 752 {
 753         /* Always ready for a write */
 754         return (1);
 755 }
 756
 757 static int
 758 tun_filter_read(struct knote *kn, long hint)
 759 {
 760         struct tun_softc *tp = (struct tun_softc *)kn->kn_hook;
 761         int ready = 0;
 762
 763         ifnet_serialize_all(&tp->tun_if);
 764         if (!ifq_is_empty(&tp->tun_if.if_snd))
 765                 ready = 1;
 766         ifnet_deserialize_all(&tp->tun_if);
 767
 768         return (ready);
 769 }
 770
 771 /*
 772  * Start packet transmission on the interface.
 773  * when the interface queue is rate-limited by ALTQ,
 774  * if_start is needed to drain packets from the queue in order
 775  * to notify readers when outgoing packets become ready.
 776  */
 777 static void
 778 tunstart(struct ifnet *ifp)
 779 {
 780         struct tun_softc *tp = ifp->if_softc;
 781         struct mbuf *m;
 782
 783         if (!ifq_is_enabled(&ifp->if_snd))
 784                 return;
 785
 786         m = ifq_poll(&ifp->if_snd);
 787         if (m != NULL) {
 788                 if (tp->tun_flags & TUN_RWAIT) {
 789                         tp->tun_flags &= ~TUN_RWAIT;
 790                         wakeup((caddr_t)tp);
 791                 }
 792                 if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
 793                         pgsigio(tp->tun_sigio, SIGIO, 0);
 794                 ifnet_deserialize_tx(ifp);
 795                 KNOTE(&tp->tun_rkq.ki_note, 0);
 796                 ifnet_serialize_tx(ifp);
 797         }
 798 }