kernel - Provide descriptions for lwkt.* and debug.* sysctl's
[dragonfly.git] / 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 }