The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/if_tun.c

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    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: releng/7.3/sys/net/if_tun.c 202814 2010-01-22 17:02:07Z jhb $
   17  */
   18 
   19 #include "opt_atalk.h"
   20 #include "opt_inet.h"
   21 #include "opt_inet6.h"
   22 #include "opt_ipx.h"
   23 #include "opt_mac.h"
   24 
   25 #include <sys/param.h>
   26 #include <sys/priv.h>
   27 #include <sys/proc.h>
   28 #include <sys/systm.h>
   29 #include <sys/mbuf.h>
   30 #include <sys/module.h>
   31 #include <sys/socket.h>
   32 #include <sys/fcntl.h>
   33 #include <sys/filio.h>
   34 #include <sys/sockio.h>
   35 #include <sys/ttycom.h>
   36 #include <sys/poll.h>
   37 #include <sys/selinfo.h>
   38 #include <sys/signalvar.h>
   39 #include <sys/filedesc.h>
   40 #include <sys/kernel.h>
   41 #include <sys/sysctl.h>
   42 #include <sys/conf.h>
   43 #include <sys/uio.h>
   44 #include <sys/malloc.h>
   45 #include <sys/random.h>
   46 
   47 #include <net/if.h>
   48 #include <net/if_clone.h>
   49 #include <net/if_types.h>
   50 #include <net/netisr.h>
   51 #include <net/route.h>
   52 #ifdef INET
   53 #include <netinet/in.h>
   54 #endif
   55 #include <net/bpf.h>
   56 #include <net/if_tun.h>
   57 
   58 #include <sys/queue.h>
   59 
   60 #include <security/mac/mac_framework.h>
   61 
   62 /*
   63  * tun_list is protected by global tunmtx.  Other mutable fields are
   64  * protected by tun->tun_mtx, or by their owning subsystem.  tun_dev is
   65  * static for the duration of a tunnel interface.
   66  */
   67 struct tun_softc {
   68         TAILQ_ENTRY(tun_softc)  tun_list;
   69         struct cdev *tun_dev;
   70         u_short tun_flags;              /* misc flags */
   71 #define TUN_OPEN        0x0001
   72 #define TUN_INITED      0x0002
   73 #define TUN_RCOLL       0x0004
   74 #define TUN_IASET       0x0008
   75 #define TUN_DSTADDR     0x0010
   76 #define TUN_LMODE       0x0020
   77 #define TUN_RWAIT       0x0040
   78 #define TUN_ASYNC       0x0080
   79 #define TUN_IFHEAD      0x0100
   80 
   81 #define TUN_READY       (TUN_OPEN | TUN_INITED)
   82 
   83         /*
   84          * XXXRW: tun_pid is used to exclusively lock /dev/tun.  Is this
   85          * actually needed?  Can we just return EBUSY if already open?
   86          * Problem is that this involved inherent races when a tun device
   87          * is handed off from one process to another, as opposed to just
   88          * being slightly stale informationally.
   89          */
   90         pid_t   tun_pid;                /* owning pid */
   91         struct  ifnet *tun_ifp;         /* the interface */
   92         struct  sigio *tun_sigio;       /* information for async I/O */
   93         struct  selinfo tun_rsel;       /* read select */
   94         struct mtx      tun_mtx;        /* protect mutable softc fields */
   95 };
   96 #define TUN2IFP(sc)     ((sc)->tun_ifp)
   97 
   98 #define TUNDEBUG        if (tundebug) if_printf
   99 #define TUNNAME         "tun"
  100 
  101 /*
  102  * All mutable global variables in if_tun are locked using tunmtx, with
  103  * the exception of tundebug, which is used unlocked, and tunclones,
  104  * which is static after setup.
  105  */
  106 static struct mtx tunmtx;
  107 static MALLOC_DEFINE(M_TUN, TUNNAME, "Tunnel Interface");
  108 static int tundebug = 0;
  109 static int tundclone = 1;
  110 static struct clonedevs *tunclones;
  111 static TAILQ_HEAD(,tun_softc)   tunhead = TAILQ_HEAD_INITIALIZER(tunhead);
  112 SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0, "");
  113 
  114 SYSCTL_DECL(_net_link);
  115 SYSCTL_NODE(_net_link, OID_AUTO, tun, CTLFLAG_RW, 0,
  116     "IP tunnel software network interface.");
  117 SYSCTL_INT(_net_link_tun, OID_AUTO, devfs_cloning, CTLFLAG_RW, &tundclone, 0,
  118     "Enable legacy devfs interface creation.");
  119 
  120 TUNABLE_INT("net.link.tun.devfs_cloning", &tundclone);
  121 
  122 static void     tunclone(void *arg, struct ucred *cred, char *name,
  123                     int namelen, struct cdev **dev);
  124 static void     tuncreate(const char *name, struct cdev *dev);
  125 static int      tunifioctl(struct ifnet *, u_long, caddr_t);
  126 static int      tuninit(struct ifnet *);
  127 static int      tunmodevent(module_t, int, void *);
  128 static int      tunoutput(struct ifnet *, struct mbuf *, struct sockaddr *,
  129                     struct rtentry *rt);
  130 static void     tunstart(struct ifnet *);
  131 
  132 static int      tun_clone_create(struct if_clone *, int, caddr_t);
  133 static void     tun_clone_destroy(struct ifnet *);
  134 
  135 IFC_SIMPLE_DECLARE(tun, 0);
  136 
  137 static d_open_t         tunopen;
  138 static d_close_t        tunclose;
  139 static d_read_t         tunread;
  140 static d_write_t        tunwrite;
  141 static d_ioctl_t        tunioctl;
  142 static d_poll_t         tunpoll;
  143 static d_kqfilter_t     tunkqfilter;
  144 
  145 static int              tunkqread(struct knote *, long);
  146 static int              tunkqwrite(struct knote *, long);
  147 static void             tunkqdetach(struct knote *);
  148 
  149 static struct filterops tun_read_filterops = {
  150         .f_isfd =       1,
  151         .f_attach =     NULL,
  152         .f_detach =     tunkqdetach,
  153         .f_event =      tunkqread,
  154 };
  155 
  156 static struct filterops tun_write_filterops = {
  157         .f_isfd =       1,
  158         .f_attach =     NULL,
  159         .f_detach =     tunkqdetach,
  160         .f_event =      tunkqwrite,
  161 };
  162 
  163 static struct cdevsw tun_cdevsw = {
  164         .d_version =    D_VERSION,
  165         .d_flags =      D_PSEUDO | D_NEEDGIANT,
  166         .d_open =       tunopen,
  167         .d_close =      tunclose,
  168         .d_read =       tunread,
  169         .d_write =      tunwrite,
  170         .d_ioctl =      tunioctl,
  171         .d_poll =       tunpoll,
  172         .d_kqfilter =   tunkqfilter,
  173         .d_name =       TUNNAME,
  174 };
  175 
  176 static int
  177 tun_clone_create(struct if_clone *ifc, int unit, caddr_t params)
  178 {
  179         struct cdev *dev;
  180         int i;
  181 
  182         /* find any existing device, or allocate new unit number */
  183         i = clone_create(&tunclones, &tun_cdevsw, &unit, &dev, 0);
  184         if (i) {
  185                 /* No preexisting struct cdev *, create one */
  186                 dev = make_dev(&tun_cdevsw, unit2minor(unit),
  187                     UID_UUCP, GID_DIALER, 0600, "%s%d", ifc->ifc_name, unit);
  188                 if (dev != NULL) {
  189                         dev_ref(dev);
  190                         dev->si_flags |= SI_CHEAPCLONE;
  191                 }
  192         }
  193         tuncreate(ifc->ifc_name, dev);
  194 
  195         return (0);
  196 }
  197 
  198 static void
  199 tunclone(void *arg, struct ucred *cred, char *name, int namelen,
  200     struct cdev **dev)
  201 {
  202         char devname[SPECNAMELEN + 1];
  203         int u, i, append_unit;
  204 
  205         if (*dev != NULL)
  206                 return;
  207 
  208         /*
  209          * If tun cloning is enabled, only the superuser can create an
  210          * interface.
  211          */
  212         if (!tundclone || priv_check_cred(cred, PRIV_NET_IFCREATE, 0) != 0)
  213                 return;
  214 
  215         if (strcmp(name, TUNNAME) == 0) {
  216                 u = -1;
  217         } else if (dev_stdclone(name, NULL, TUNNAME, &u) != 1)
  218                 return; /* Don't recognise the name */
  219         if (u != -1 && u > IF_MAXUNIT)
  220                 return; /* Unit number too high */
  221 
  222         if (u == -1)
  223                 append_unit = 1;
  224         else
  225                 append_unit = 0;
  226 
  227         /* find any existing device, or allocate new unit number */
  228         i = clone_create(&tunclones, &tun_cdevsw, &u, dev, 0);
  229         if (i) {
  230                 if (append_unit) {
  231                         namelen = snprintf(devname, sizeof(devname), "%s%d", name,
  232                             u);
  233                         name = devname;
  234                 }
  235                 /* No preexisting struct cdev *, create one */
  236                 *dev = make_dev(&tun_cdevsw, unit2minor(u),
  237                     UID_UUCP, GID_DIALER, 0600, "%s", name);
  238                 if (*dev != NULL) {
  239                         dev_ref(*dev);
  240                         (*dev)->si_flags |= SI_CHEAPCLONE;
  241                 }
  242         }
  243 
  244         if_clone_create(name, namelen, NULL);
  245 }
  246 
  247 static void
  248 tun_destroy(struct tun_softc *tp)
  249 {
  250         struct cdev *dev;
  251 
  252         /* Unlocked read. */
  253         KASSERT((tp->tun_flags & TUN_OPEN) == 0,
  254             ("tununits is out of sync - unit %d", TUN2IFP(tp)->if_dunit));
  255 
  256         dev = tp->tun_dev;
  257         bpfdetach(TUN2IFP(tp));
  258         if_detach(TUN2IFP(tp));
  259         if_free(TUN2IFP(tp));
  260         destroy_dev(dev);
  261         knlist_destroy(&tp->tun_rsel.si_note);
  262         mtx_destroy(&tp->tun_mtx);
  263         free(tp, M_TUN);
  264 }
  265 
  266 static void
  267 tun_clone_destroy(struct ifnet *ifp)
  268 {
  269         struct tun_softc *tp = ifp->if_softc;
  270 
  271         mtx_lock(&tunmtx);
  272         TAILQ_REMOVE(&tunhead, tp, tun_list);
  273         mtx_unlock(&tunmtx);
  274         tun_destroy(tp);
  275 }
  276 
  277 static int
  278 tunmodevent(module_t mod, int type, void *data)
  279 {
  280         static eventhandler_tag tag;
  281         struct tun_softc *tp;
  282 
  283         switch (type) {
  284         case MOD_LOAD:
  285                 mtx_init(&tunmtx, "tunmtx", NULL, MTX_DEF);
  286                 clone_setup(&tunclones);
  287                 tag = EVENTHANDLER_REGISTER(dev_clone, tunclone, 0, 1000);
  288                 if (tag == NULL)
  289                         return (ENOMEM);
  290                 if_clone_attach(&tun_cloner);
  291                 break;
  292         case MOD_UNLOAD:
  293                 if_clone_detach(&tun_cloner);
  294                 EVENTHANDLER_DEREGISTER(dev_clone, tag);
  295 
  296                 mtx_lock(&tunmtx);
  297                 while ((tp = TAILQ_FIRST(&tunhead)) != NULL) {
  298                         TAILQ_REMOVE(&tunhead, tp, tun_list);
  299                         mtx_unlock(&tunmtx);
  300                         tun_destroy(tp);
  301                         mtx_lock(&tunmtx);
  302                 }
  303                 mtx_unlock(&tunmtx);
  304                 clone_cleanup(&tunclones);
  305                 mtx_destroy(&tunmtx);
  306                 break;
  307         default:
  308                 return EOPNOTSUPP;
  309         }
  310         return 0;
  311 }
  312 
  313 static moduledata_t tun_mod = {
  314         "if_tun",
  315         tunmodevent,
  316         0
  317 };
  318 
  319 DECLARE_MODULE(if_tun, tun_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  320 
  321 static void
  322 tunstart(struct ifnet *ifp)
  323 {
  324         struct tun_softc *tp = ifp->if_softc;
  325         struct mbuf *m;
  326 
  327         TUNDEBUG(ifp,"%s starting\n", ifp->if_xname);
  328         if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
  329                 IFQ_LOCK(&ifp->if_snd);
  330                 IFQ_POLL_NOLOCK(&ifp->if_snd, m);
  331                 if (m == NULL) {
  332                         IFQ_UNLOCK(&ifp->if_snd);
  333                         return;
  334                 }
  335                 IFQ_UNLOCK(&ifp->if_snd);
  336         }
  337 
  338         mtx_lock(&tp->tun_mtx);
  339         if (tp->tun_flags & TUN_RWAIT) {
  340                 tp->tun_flags &= ~TUN_RWAIT;
  341                 wakeup(tp);
  342         }
  343         if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio) {
  344                 mtx_unlock(&tp->tun_mtx);
  345                 pgsigio(&tp->tun_sigio, SIGIO, 0);
  346         } else
  347                 mtx_unlock(&tp->tun_mtx);
  348         selwakeuppri(&tp->tun_rsel, PZERO + 1);
  349         KNOTE_UNLOCKED(&tp->tun_rsel.si_note, 0);
  350 }
  351 
  352 /* XXX: should return an error code so it can fail. */
  353 static void
  354 tuncreate(const char *name, struct cdev *dev)
  355 {
  356         struct tun_softc *sc;
  357         struct ifnet *ifp;
  358 
  359         dev->si_flags &= ~SI_CHEAPCLONE;
  360 
  361         MALLOC(sc, struct tun_softc *, sizeof(*sc), M_TUN, M_WAITOK | M_ZERO);
  362         mtx_init(&sc->tun_mtx, "tun_mtx", NULL, MTX_DEF);
  363         sc->tun_flags = TUN_INITED;
  364         sc->tun_dev = dev;
  365         mtx_lock(&tunmtx);
  366         TAILQ_INSERT_TAIL(&tunhead, sc, tun_list);
  367         mtx_unlock(&tunmtx);
  368 
  369         ifp = sc->tun_ifp = if_alloc(IFT_PPP);
  370         if (ifp == NULL)
  371                 panic("%s%d: failed to if_alloc() interface.\n",
  372                     name, dev2unit(dev));
  373         if_initname(ifp, name, dev2unit(dev));
  374         ifp->if_mtu = TUNMTU;
  375         ifp->if_ioctl = tunifioctl;
  376         ifp->if_output = tunoutput;
  377         ifp->if_start = tunstart;
  378         ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
  379         ifp->if_softc = sc;
  380         IFQ_SET_MAXLEN(&ifp->if_snd, ifqmaxlen);
  381         ifp->if_snd.ifq_drv_maxlen = 0;
  382         IFQ_SET_READY(&ifp->if_snd);
  383         knlist_init_mtx(&sc->tun_rsel.si_note, NULL);
  384 
  385         if_attach(ifp);
  386         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  387         dev->si_drv1 = sc;
  388         TUNDEBUG(ifp, "interface %s is created, minor = %#x\n",
  389             ifp->if_xname, minor(dev));
  390 }
  391 
  392 static int
  393 tunopen(struct cdev *dev, int flag, int mode, struct thread *td)
  394 {
  395         struct ifnet    *ifp;
  396         struct tun_softc *tp;
  397 
  398         /*
  399          * XXXRW: Non-atomic test and set of dev->si_drv1 requires
  400          * synchronization.
  401          */
  402         tp = dev->si_drv1;
  403         if (!tp) {
  404                 tuncreate(TUNNAME, dev);
  405                 tp = dev->si_drv1;
  406         }
  407 
  408         /*
  409          * XXXRW: This use of tun_pid is subject to error due to the
  410          * fact that a reference to the tunnel can live beyond the
  411          * death of the process that created it.  Can we replace this
  412          * with a simple busy flag?
  413          */
  414         mtx_lock(&tp->tun_mtx);
  415         if (tp->tun_pid != 0 && tp->tun_pid != td->td_proc->p_pid) {
  416                 mtx_unlock(&tp->tun_mtx);
  417                 return (EBUSY);
  418         }
  419         tp->tun_pid = td->td_proc->p_pid;
  420 
  421         tp->tun_flags |= TUN_OPEN;
  422         mtx_unlock(&tp->tun_mtx);
  423         ifp = TUN2IFP(tp);
  424         TUNDEBUG(ifp, "open\n");
  425 
  426         return (0);
  427 }
  428 
  429 /*
  430  * tunclose - close the device - mark i/f down & delete
  431  * routing info
  432  */
  433 static  int
  434 tunclose(struct cdev *dev, int foo, int bar, struct thread *td)
  435 {
  436         struct tun_softc *tp;
  437         struct ifnet *ifp;
  438         int s;
  439 
  440         tp = dev->si_drv1;
  441         ifp = TUN2IFP(tp);
  442 
  443         mtx_lock(&tp->tun_mtx);
  444         tp->tun_flags &= ~TUN_OPEN;
  445         tp->tun_pid = 0;
  446 
  447         /*
  448          * junk all pending output
  449          */
  450         s = splimp();
  451         IFQ_PURGE(&ifp->if_snd);
  452         splx(s);
  453         mtx_unlock(&tp->tun_mtx);
  454 
  455         if (ifp->if_flags & IFF_UP) {
  456                 s = splimp();
  457                 if_down(ifp);
  458                 splx(s);
  459         }
  460 
  461         /* Delete all addresses and routes which reference this interface. */
  462         if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
  463                 struct ifaddr *ifa;
  464 
  465                 s = splimp();
  466                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  467                         /* deal w/IPv4 PtP destination; unlocked read */
  468                         if (ifa->ifa_addr->sa_family == AF_INET) {
  469                                 rtinit(ifa, (int)RTM_DELETE,
  470                                     tp->tun_flags & TUN_DSTADDR ? RTF_HOST : 0);
  471                         } else {
  472                                 rtinit(ifa, (int)RTM_DELETE, 0);
  473                         }
  474                 }
  475                 if_purgeaddrs(ifp);
  476                 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
  477                 splx(s);
  478         }
  479 
  480         funsetown(&tp->tun_sigio);
  481         selwakeuppri(&tp->tun_rsel, PZERO + 1);
  482         KNOTE_UNLOCKED(&tp->tun_rsel.si_note, 0);
  483         TUNDEBUG (ifp, "closed\n");
  484         return (0);
  485 }
  486 
  487 static int
  488 tuninit(struct ifnet *ifp)
  489 {
  490         struct tun_softc *tp = ifp->if_softc;
  491         struct ifaddr *ifa;
  492         int error = 0;
  493 
  494         TUNDEBUG(ifp, "tuninit\n");
  495 
  496         ifp->if_flags |= IFF_UP;
  497         ifp->if_drv_flags |= IFF_DRV_RUNNING;
  498         getmicrotime(&ifp->if_lastchange);
  499 
  500 #ifdef INET
  501         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  502                 if (ifa->ifa_addr->sa_family == AF_INET) {
  503                         struct sockaddr_in *si;
  504 
  505                         si = (struct sockaddr_in *)ifa->ifa_addr;
  506                         mtx_lock(&tp->tun_mtx);
  507                         if (si->sin_addr.s_addr)
  508                                 tp->tun_flags |= TUN_IASET;
  509 
  510                         si = (struct sockaddr_in *)ifa->ifa_dstaddr;
  511                         if (si && si->sin_addr.s_addr)
  512                                 tp->tun_flags |= TUN_DSTADDR;
  513                         mtx_unlock(&tp->tun_mtx);
  514                 }
  515         }
  516 #endif
  517         return (error);
  518 }
  519 
  520 /*
  521  * Process an ioctl request.
  522  */
  523 static int
  524 tunifioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
  525 {
  526         struct ifreq *ifr = (struct ifreq *)data;
  527         struct tun_softc *tp = ifp->if_softc;
  528         struct ifstat *ifs;
  529         int             error = 0, s;
  530 
  531         s = splimp();
  532         switch(cmd) {
  533         case SIOCGIFSTATUS:
  534                 ifs = (struct ifstat *)data;
  535                 mtx_lock(&tp->tun_mtx);
  536                 if (tp->tun_pid)
  537                         sprintf(ifs->ascii + strlen(ifs->ascii),
  538                             "\tOpened by PID %d\n", tp->tun_pid);
  539                 mtx_unlock(&tp->tun_mtx);
  540                 break;
  541         case SIOCSIFADDR:
  542                 error = tuninit(ifp);
  543                 TUNDEBUG(ifp, "address set, error=%d\n", error);
  544                 break;
  545         case SIOCSIFDSTADDR:
  546                 error = tuninit(ifp);
  547                 TUNDEBUG(ifp, "destination address set, error=%d\n", error);
  548                 break;
  549         case SIOCSIFMTU:
  550                 ifp->if_mtu = ifr->ifr_mtu;
  551                 TUNDEBUG(ifp, "mtu set\n");
  552                 break;
  553         case SIOCSIFFLAGS:
  554         case SIOCADDMULTI:
  555         case SIOCDELMULTI:
  556                 break;
  557         default:
  558                 error = EINVAL;
  559         }
  560         splx(s);
  561         return (error);
  562 }
  563 
  564 /*
  565  * tunoutput - queue packets from higher level ready to put out.
  566  */
  567 static int
  568 tunoutput(
  569         struct ifnet *ifp,
  570         struct mbuf *m0,
  571         struct sockaddr *dst,
  572         struct rtentry *rt)
  573 {
  574         struct tun_softc *tp = ifp->if_softc;
  575         u_short cached_tun_flags;
  576         int error;
  577         u_int32_t af;
  578 
  579         TUNDEBUG (ifp, "tunoutput\n");
  580 
  581 #ifdef MAC
  582         error = mac_check_ifnet_transmit(ifp, m0);
  583         if (error) {
  584                 m_freem(m0);
  585                 return (error);
  586         }
  587 #endif
  588 
  589         /* Could be unlocked read? */
  590         mtx_lock(&tp->tun_mtx);
  591         cached_tun_flags = tp->tun_flags;
  592         mtx_unlock(&tp->tun_mtx);
  593         if ((cached_tun_flags & TUN_READY) != TUN_READY) {
  594                 TUNDEBUG (ifp, "not ready 0%o\n", tp->tun_flags);
  595                 m_freem (m0);
  596                 return (EHOSTDOWN);
  597         }
  598 
  599         if ((ifp->if_flags & IFF_UP) != IFF_UP) {
  600                 m_freem (m0);
  601                 return (EHOSTDOWN);
  602         }
  603 
  604         /* BPF writes need to be handled specially. */
  605         if (dst->sa_family == AF_UNSPEC) {
  606                 bcopy(dst->sa_data, &af, sizeof(af));
  607                 dst->sa_family = af; 
  608         }
  609 
  610         if (bpf_peers_present(ifp->if_bpf)) {
  611                 af = dst->sa_family;
  612                 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m0);
  613         }
  614 
  615         /* prepend sockaddr? this may abort if the mbuf allocation fails */
  616         if (cached_tun_flags & TUN_LMODE) {
  617                 /* allocate space for sockaddr */
  618                 M_PREPEND(m0, dst->sa_len, M_DONTWAIT);
  619 
  620                 /* if allocation failed drop packet */
  621                 if (m0 == NULL) {
  622                         ifp->if_iqdrops++;
  623                         ifp->if_oerrors++;
  624                         return (ENOBUFS);
  625                 } else {
  626                         bcopy(dst, m0->m_data, dst->sa_len);
  627                 }
  628         }
  629 
  630         if (cached_tun_flags & TUN_IFHEAD) {
  631                 /* Prepend the address family */
  632                 M_PREPEND(m0, 4, M_DONTWAIT);
  633 
  634                 /* if allocation failed drop packet */
  635                 if (m0 == NULL) {
  636                         ifp->if_iqdrops++;
  637                         ifp->if_oerrors++;
  638                         return (ENOBUFS);
  639                 } else
  640                         *(u_int32_t *)m0->m_data = htonl(dst->sa_family);
  641         } else {
  642 #ifdef INET
  643                 if (dst->sa_family != AF_INET)
  644 #endif
  645                 {
  646                         m_freem(m0);
  647                         return (EAFNOSUPPORT);
  648                 }
  649         }
  650 
  651         IFQ_HANDOFF(ifp, m0, error);
  652         if (error) {
  653                 ifp->if_collisions++;
  654                 return (ENOBUFS);
  655         }
  656         ifp->if_opackets++;
  657         return (0);
  658 }
  659 
  660 /*
  661  * the cdevsw interface is now pretty minimal.
  662  */
  663 static  int
  664 tunioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *td)
  665 {
  666         int             s;
  667         int             error;
  668         struct tun_softc *tp = dev->si_drv1;
  669         struct tuninfo *tunp;
  670 
  671         switch (cmd) {
  672         case TUNSIFINFO:
  673                 tunp = (struct tuninfo *)data;
  674                 if (tunp->mtu < IF_MINMTU)
  675                         return (EINVAL);
  676                 if (TUN2IFP(tp)->if_mtu != tunp->mtu) {
  677                         error = priv_check(td, PRIV_NET_SETIFMTU);
  678                         if (error)
  679                                 return (error);
  680                 }
  681                 TUN2IFP(tp)->if_mtu = tunp->mtu;
  682                 TUN2IFP(tp)->if_type = tunp->type;
  683                 TUN2IFP(tp)->if_baudrate = tunp->baudrate;
  684                 break;
  685         case TUNGIFINFO:
  686                 tunp = (struct tuninfo *)data;
  687                 tunp->mtu = TUN2IFP(tp)->if_mtu;
  688                 tunp->type = TUN2IFP(tp)->if_type;
  689                 tunp->baudrate = TUN2IFP(tp)->if_baudrate;
  690                 break;
  691         case TUNSDEBUG:
  692                 tundebug = *(int *)data;
  693                 break;
  694         case TUNGDEBUG:
  695                 *(int *)data = tundebug;
  696                 break;
  697         case TUNSLMODE:
  698                 mtx_lock(&tp->tun_mtx);
  699                 if (*(int *)data) {
  700                         tp->tun_flags |= TUN_LMODE;
  701                         tp->tun_flags &= ~TUN_IFHEAD;
  702                 } else
  703                         tp->tun_flags &= ~TUN_LMODE;
  704                 mtx_unlock(&tp->tun_mtx);
  705                 break;
  706         case TUNSIFHEAD:
  707                 mtx_lock(&tp->tun_mtx);
  708                 if (*(int *)data) {
  709                         tp->tun_flags |= TUN_IFHEAD;
  710                         tp->tun_flags &= ~TUN_LMODE;
  711                 } else
  712                         tp->tun_flags &= ~TUN_IFHEAD;
  713                 mtx_unlock(&tp->tun_mtx);
  714                 break;
  715         case TUNGIFHEAD:
  716                 /* Could be unlocked read? */
  717                 mtx_lock(&tp->tun_mtx);
  718                 *(int *)data = (tp->tun_flags & TUN_IFHEAD) ? 1 : 0;
  719                 mtx_unlock(&tp->tun_mtx);
  720                 break;
  721         case TUNSIFMODE:
  722                 /* deny this if UP */
  723                 if (TUN2IFP(tp)->if_flags & IFF_UP)
  724                         return(EBUSY);
  725 
  726                 switch (*(int *)data & ~IFF_MULTICAST) {
  727                 case IFF_POINTOPOINT:
  728                 case IFF_BROADCAST:
  729                         TUN2IFP(tp)->if_flags &=
  730                             ~(IFF_BROADCAST|IFF_POINTOPOINT|IFF_MULTICAST);
  731                         TUN2IFP(tp)->if_flags |= *(int *)data;
  732                         break;
  733                 default:
  734                         return(EINVAL);
  735                 }
  736                 break;
  737         case TUNSIFPID:
  738                 mtx_lock(&tp->tun_mtx);
  739                 tp->tun_pid = curthread->td_proc->p_pid;
  740                 mtx_unlock(&tp->tun_mtx);
  741                 break;
  742         case FIONBIO:
  743                 break;
  744         case FIOASYNC:
  745                 mtx_lock(&tp->tun_mtx);
  746                 if (*(int *)data)
  747                         tp->tun_flags |= TUN_ASYNC;
  748                 else
  749                         tp->tun_flags &= ~TUN_ASYNC;
  750                 mtx_unlock(&tp->tun_mtx);
  751                 break;
  752         case FIONREAD:
  753                 s = splimp();
  754                 if (!IFQ_IS_EMPTY(&TUN2IFP(tp)->if_snd)) {
  755                         struct mbuf *mb;
  756                         IFQ_LOCK(&TUN2IFP(tp)->if_snd);
  757                         IFQ_POLL_NOLOCK(&TUN2IFP(tp)->if_snd, mb);
  758                         for( *(int *)data = 0; mb != 0; mb = mb->m_next)
  759                                 *(int *)data += mb->m_len;
  760                         IFQ_UNLOCK(&TUN2IFP(tp)->if_snd);
  761                 } else
  762                         *(int *)data = 0;
  763                 splx(s);
  764                 break;
  765         case FIOSETOWN:
  766                 return (fsetown(*(int *)data, &tp->tun_sigio));
  767 
  768         case FIOGETOWN:
  769                 *(int *)data = fgetown(&tp->tun_sigio);
  770                 return (0);
  771 
  772         /* This is deprecated, FIOSETOWN should be used instead. */
  773         case TIOCSPGRP:
  774                 return (fsetown(-(*(int *)data), &tp->tun_sigio));
  775 
  776         /* This is deprecated, FIOGETOWN should be used instead. */
  777         case TIOCGPGRP:
  778                 *(int *)data = -fgetown(&tp->tun_sigio);
  779                 return (0);
  780 
  781         default:
  782                 return (ENOTTY);
  783         }
  784         return (0);
  785 }
  786 
  787 /*
  788  * The cdevsw read interface - reads a packet at a time, or at
  789  * least as much of a packet as can be read.
  790  */
  791 static  int
  792 tunread(struct cdev *dev, struct uio *uio, int flag)
  793 {
  794         struct tun_softc *tp = dev->si_drv1;
  795         struct ifnet    *ifp = TUN2IFP(tp);
  796         struct mbuf     *m;
  797         int             error=0, len, s;
  798 
  799         TUNDEBUG (ifp, "read\n");
  800         mtx_lock(&tp->tun_mtx);
  801         if ((tp->tun_flags & TUN_READY) != TUN_READY) {
  802                 mtx_unlock(&tp->tun_mtx);
  803                 TUNDEBUG (ifp, "not ready 0%o\n", tp->tun_flags);
  804                 return (EHOSTDOWN);
  805         }
  806 
  807         tp->tun_flags &= ~TUN_RWAIT;
  808         mtx_unlock(&tp->tun_mtx);
  809 
  810         s = splimp();
  811         do {
  812                 IFQ_DEQUEUE(&ifp->if_snd, m);
  813                 if (m == NULL) {
  814                         if (flag & O_NONBLOCK) {
  815                                 splx(s);
  816                                 return (EWOULDBLOCK);
  817                         }
  818                         mtx_lock(&tp->tun_mtx);
  819                         tp->tun_flags |= TUN_RWAIT;
  820                         mtx_unlock(&tp->tun_mtx);
  821                         if ((error = tsleep(tp, PCATCH | (PZERO + 1),
  822                                         "tunread", 0)) != 0) {
  823                                 splx(s);
  824                                 return (error);
  825                         }
  826                 }
  827         } while (m == NULL);
  828         splx(s);
  829 
  830         while (m && uio->uio_resid > 0 && error == 0) {
  831                 len = min(uio->uio_resid, m->m_len);
  832                 if (len != 0)
  833                         error = uiomove(mtod(m, void *), len, uio);
  834                 m = m_free(m);
  835         }
  836 
  837         if (m) {
  838                 TUNDEBUG(ifp, "Dropping mbuf\n");
  839                 m_freem(m);
  840         }
  841         return (error);
  842 }
  843 
  844 /*
  845  * the cdevsw write interface - an atomic write is a packet - or else!
  846  */
  847 static  int
  848 tunwrite(struct cdev *dev, struct uio *uio, int flag)
  849 {
  850         struct tun_softc *tp = dev->si_drv1;
  851         struct ifnet    *ifp = TUN2IFP(tp);
  852         struct mbuf     *m;
  853         int             error = 0;
  854         uint32_t        family;
  855         int             isr;
  856 
  857         TUNDEBUG(ifp, "tunwrite\n");
  858 
  859         if ((ifp->if_flags & IFF_UP) != IFF_UP)
  860                 /* ignore silently */
  861                 return (0);
  862 
  863         if (uio->uio_resid == 0)
  864                 return (0);
  865 
  866         if (uio->uio_resid < 0 || uio->uio_resid > TUNMRU) {
  867                 TUNDEBUG(ifp, "len=%d!\n", uio->uio_resid);
  868                 return (EIO);
  869         }
  870 
  871         if ((m = m_uiotombuf(uio, M_DONTWAIT, 0, 0, M_PKTHDR)) == NULL) {
  872                 ifp->if_ierrors++;
  873                 return (error);
  874         }
  875 
  876         m->m_pkthdr.rcvif = ifp;
  877 #ifdef MAC
  878         mac_create_mbuf_from_ifnet(ifp, m);
  879 #endif
  880 
  881         /* Could be unlocked read? */
  882         mtx_lock(&tp->tun_mtx);
  883         if (tp->tun_flags & TUN_IFHEAD) {
  884                 mtx_unlock(&tp->tun_mtx);
  885                 if (m->m_len < sizeof(family) &&
  886                     (m = m_pullup(m, sizeof(family))) == NULL)
  887                         return (ENOBUFS);
  888                 family = ntohl(*mtod(m, u_int32_t *));
  889                 m_adj(m, sizeof(family));
  890         } else {
  891                 mtx_unlock(&tp->tun_mtx);
  892                 family = AF_INET;
  893         }
  894 
  895         BPF_MTAP2(ifp, &family, sizeof(family), m);
  896 
  897         switch (family) {
  898 #ifdef INET
  899         case AF_INET:
  900                 isr = NETISR_IP;
  901                 break;
  902 #endif
  903 #ifdef INET6
  904         case AF_INET6:
  905                 isr = NETISR_IPV6;
  906                 break;
  907 #endif
  908 #ifdef IPX
  909         case AF_IPX:
  910                 isr = NETISR_IPX;
  911                 break;
  912 #endif
  913 #ifdef NETATALK
  914         case AF_APPLETALK:
  915                 isr = NETISR_ATALK2;
  916                 break;
  917 #endif
  918         default:
  919                 m_freem(m);
  920                 return (EAFNOSUPPORT);
  921         }
  922         /* First chunk of an mbuf contains good junk */
  923         if (harvest.point_to_point)
  924                 random_harvest(m, 16, 3, 0, RANDOM_NET);
  925         ifp->if_ibytes += m->m_pkthdr.len;
  926         ifp->if_ipackets++;
  927         netisr_dispatch(isr, m);
  928         return (0);
  929 }
  930 
  931 /*
  932  * tunpoll - the poll interface, this is only useful on reads
  933  * really. The write detect always returns true, write never blocks
  934  * anyway, it either accepts the packet or drops it.
  935  */
  936 static  int
  937 tunpoll(struct cdev *dev, int events, struct thread *td)
  938 {
  939         int             s;
  940         struct tun_softc *tp = dev->si_drv1;
  941         struct ifnet    *ifp = TUN2IFP(tp);
  942         int             revents = 0;
  943         struct mbuf     *m;
  944 
  945         s = splimp();
  946         TUNDEBUG(ifp, "tunpoll\n");
  947 
  948         if (events & (POLLIN | POLLRDNORM)) {
  949                 IFQ_LOCK(&ifp->if_snd);
  950                 IFQ_POLL_NOLOCK(&ifp->if_snd, m);
  951                 if (m != NULL) {
  952                         TUNDEBUG(ifp, "tunpoll q=%d\n", ifp->if_snd.ifq_len);
  953                         revents |= events & (POLLIN | POLLRDNORM);
  954                 } else {
  955                         TUNDEBUG(ifp, "tunpoll waiting\n");
  956                         selrecord(td, &tp->tun_rsel);
  957                 }
  958                 IFQ_UNLOCK(&ifp->if_snd);
  959         }
  960         if (events & (POLLOUT | POLLWRNORM))
  961                 revents |= events & (POLLOUT | POLLWRNORM);
  962 
  963         splx(s);
  964         return (revents);
  965 }
  966 
  967 /*
  968  * tunkqfilter - support for the kevent() system call.
  969  */
  970 static int
  971 tunkqfilter(struct cdev *dev, struct knote *kn)
  972 {
  973         int                     s;
  974         struct tun_softc        *tp = dev->si_drv1;
  975         struct ifnet    *ifp = TUN2IFP(tp);
  976 
  977         s = splimp();
  978         switch(kn->kn_filter) {
  979         case EVFILT_READ:
  980                 TUNDEBUG(ifp, "%s kqfilter: EVFILT_READ, minor = %#x\n",
  981                     ifp->if_xname, minor(dev));
  982                 kn->kn_fop = &tun_read_filterops;
  983                 break;
  984 
  985         case EVFILT_WRITE:
  986                 TUNDEBUG(ifp, "%s kqfilter: EVFILT_WRITE, minor = %#x\n",
  987                     ifp->if_xname, minor(dev));
  988                 kn->kn_fop = &tun_write_filterops;
  989                 break;
  990         
  991         default:
  992                 TUNDEBUG(ifp, "%s kqfilter: invalid filter, minor = %#x\n",
  993                     ifp->if_xname, minor(dev));
  994                 splx(s);
  995                 return(EINVAL);
  996         }
  997         splx(s);
  998 
  999         kn->kn_hook = (caddr_t) dev;
 1000         knlist_add(&tp->tun_rsel.si_note, kn, 0);
 1001 
 1002         return (0);
 1003 }
 1004 
 1005 /*
 1006  * Return true of there is data in the interface queue.
 1007  */
 1008 static int
 1009 tunkqread(struct knote *kn, long hint)
 1010 {
 1011         int                     ret, s;
 1012         struct cdev             *dev = (struct cdev *)(kn->kn_hook);
 1013         struct tun_softc        *tp = dev->si_drv1;
 1014         struct ifnet    *ifp = TUN2IFP(tp);
 1015 
 1016         s = splimp();
 1017         if ((kn->kn_data = ifp->if_snd.ifq_len) > 0) {
 1018                 TUNDEBUG(ifp,
 1019                     "%s have data in the queue.  Len = %d, minor = %#x\n",
 1020                     ifp->if_xname, ifp->if_snd.ifq_len, minor(dev));
 1021                 ret = 1;
 1022         } else {
 1023                 TUNDEBUG(ifp,
 1024                     "%s waiting for data, minor = %#x\n", ifp->if_xname,
 1025                     minor(dev));
 1026                 ret = 0;
 1027         }
 1028         splx(s);
 1029 
 1030         return (ret);
 1031 }
 1032 
 1033 /*
 1034  * Always can write, always return MTU in kn->data.
 1035  */
 1036 static int
 1037 tunkqwrite(struct knote *kn, long hint)
 1038 {
 1039         int                     s;
 1040         struct tun_softc        *tp = ((struct cdev *)kn->kn_hook)->si_drv1;
 1041         struct ifnet    *ifp = TUN2IFP(tp);
 1042 
 1043         s = splimp();
 1044         kn->kn_data = ifp->if_mtu;
 1045         splx(s);
 1046 
 1047         return (1);
 1048 }
 1049 
 1050 static void
 1051 tunkqdetach(struct knote *kn)
 1052 {
 1053         struct tun_softc        *tp = ((struct cdev *)kn->kn_hook)->si_drv1;
 1054 
 1055         knlist_remove(&tp->tun_rsel.si_note, kn, 0);
 1056 }

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