xref: /dragonfly/sys/net/tap/if_tap.c (revision e2f5ccfb)
1 /*
2  * Copyright (C) 1999-2000 by Maksim Yevmenkin <m_evmenkin@yahoo.com>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * BASED ON:
27  * -------------------------------------------------------------------------
28  *
29  * Copyright (c) 1988, Julian Onions <jpo@cs.nott.ac.uk>
30  * Nottingham University 1987.
31  */
32 
33 /*
34  * $FreeBSD: src/sys/net/if_tap.c,v 1.3.2.3 2002/04/14 21:41:48 luigi Exp $
35  * $DragonFly: src/sys/net/tap/if_tap.c,v 1.40 2008/05/18 05:12:08 sephe Exp $
36  * $Id: if_tap.c,v 0.21 2000/07/23 21:46:02 max Exp $
37  */
38 
39 #include "opt_inet.h"
40 
41 #include <sys/param.h>
42 #include <sys/conf.h>
43 #include <sys/device.h>
44 #include <sys/filedesc.h>
45 #include <sys/filio.h>
46 #include <sys/kernel.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/poll.h>
50 #include <sys/proc.h>
51 #include <sys/signalvar.h>
52 #include <sys/socket.h>
53 #include <sys/sockio.h>
54 #include <sys/sysctl.h>
55 #include <sys/systm.h>
56 #include <sys/thread2.h>
57 #include <sys/ttycom.h>
58 #include <sys/uio.h>
59 #include <sys/vnode.h>
60 #include <sys/serialize.h>
61 
62 #include <net/bpf.h>
63 #include <net/ethernet.h>
64 #include <net/if.h>
65 #include <net/ifq_var.h>
66 #include <net/if_arp.h>
67 #include <net/route.h>
68 
69 #include <netinet/in.h>
70 
71 #include "if_tapvar.h"
72 #include "if_tap.h"
73 
74 
75 #define CDEV_NAME	"tap"
76 #define CDEV_MAJOR	149
77 #define TAPDEBUG	if (tapdebug) if_printf
78 
79 #define TAP		"tap"
80 #define VMNET		"vmnet"
81 #define VMNET_DEV_MASK	0x00010000
82 
83 /* module */
84 static int 		tapmodevent	(module_t, int, void *);
85 
86 /* device */
87 static void		tapcreate	(cdev_t);
88 
89 /* network interface */
90 static void		tapifstart	(struct ifnet *);
91 static int		tapifioctl	(struct ifnet *, u_long, caddr_t,
92 					 struct ucred *);
93 static void		tapifinit	(void *);
94 static void		tapifstop(struct tap_softc *, int);
95 
96 /* character device */
97 static d_open_t		tapopen;
98 static d_close_t	tapclose;
99 static d_read_t		tapread;
100 static d_write_t	tapwrite;
101 static d_ioctl_t	tapioctl;
102 static d_poll_t		tappoll;
103 static d_kqfilter_t	tapkqfilter;
104 
105 static struct dev_ops	tap_ops = {
106 	{ CDEV_NAME, CDEV_MAJOR, 0 },
107 	.d_open =	tapopen,
108 	.d_close =	tapclose,
109 	.d_read =	tapread,
110 	.d_write =	tapwrite,
111 	.d_ioctl =	tapioctl,
112 	.d_poll =	tappoll,
113 	.d_kqfilter =	tapkqfilter
114 };
115 
116 static int		taprefcnt = 0;		/* module ref. counter   */
117 static int		taplastunit = -1;	/* max. open unit number */
118 static int		tapdebug = 0;		/* debug flag            */
119 
120 MALLOC_DECLARE(M_TAP);
121 MALLOC_DEFINE(M_TAP, CDEV_NAME, "Ethernet tunnel interface");
122 SYSCTL_INT(_debug, OID_AUTO, if_tap_debug, CTLFLAG_RW, &tapdebug, 0, "");
123 DEV_MODULE(if_tap, tapmodevent, NULL);
124 
125 /*
126  * tapmodevent
127  *
128  * module event handler
129  */
130 static int
131 tapmodevent(module_t mod, int type, void *data)
132 {
133 	static int		 attached = 0;
134 	struct ifnet		*ifp = NULL;
135 	int			 unit;
136 
137 	switch (type) {
138 	case MOD_LOAD:
139 		if (attached)
140 			return (EEXIST);
141 
142 		dev_ops_add(&tap_ops, 0, 0);
143 		attached = 1;
144 		break;
145 
146 	case MOD_UNLOAD:
147 		if (taprefcnt > 0)
148 			return (EBUSY);
149 
150 		dev_ops_remove(&tap_ops, 0, 0);
151 
152 		/* XXX: maintain tap ifs in a local list */
153 		unit = 0;
154 		while (unit <= taplastunit) {
155 			TAILQ_FOREACH(ifp, &ifnet, if_link) {
156 				if ((strcmp(ifp->if_dname, TAP) == 0) ||
157 				    (strcmp(ifp->if_dname, VMNET) == 0)) {
158 					if (ifp->if_dunit == unit)
159 						break;
160 				}
161 			}
162 
163 			if (ifp != NULL) {
164 				struct tap_softc	*tp = ifp->if_softc;
165 
166 				TAPDEBUG(ifp, "detached. minor = %#x, " \
167 					"taplastunit = %d\n",
168 					minor(tp->tap_dev), taplastunit);
169 
170 				lwkt_serialize_enter(ifp->if_serializer);
171 				tapifstop(tp, 1);
172 				lwkt_serialize_exit(ifp->if_serializer);
173 
174 				ether_ifdetach(ifp);
175 				destroy_dev(tp->tap_dev);
176 				kfree(tp, M_TAP);
177 			} else {
178 				unit++;
179 			}
180 		}
181 		attached = 0;
182 		break;
183 
184 	default:
185 		return (EOPNOTSUPP);
186 	}
187 
188 	return (0);
189 } /* tapmodevent */
190 
191 
192 /*
193  * tapcreate
194  *
195  * to create interface
196  */
197 static void
198 tapcreate(cdev_t dev)
199 {
200 	struct ifnet		*ifp = NULL;
201 	struct tap_softc	*tp = NULL;
202 	uint8_t			ether_addr[ETHER_ADDR_LEN];
203 	int			 unit;
204 	char			*name = NULL;
205 
206 	/* allocate driver storage and create device */
207 	MALLOC(tp, struct tap_softc *, sizeof(*tp), M_TAP, M_WAITOK | M_ZERO);
208 
209 	/* select device: tap or vmnet */
210 	if (minor(dev) & VMNET_DEV_MASK) {
211 		name = VMNET;
212 		unit = lminor(dev) & 0xff;
213 		tp->tap_flags |= TAP_VMNET;
214 	}
215 	else {
216 		name = TAP;
217 		unit = lminor(dev);
218 	}
219 
220 	tp->tap_dev = make_dev(&tap_ops, minor(dev), UID_ROOT, GID_WHEEL,
221 						0600, "%s%d", name, unit);
222 	tp->tap_dev->si_drv1 = dev->si_drv1 = tp;
223 	reference_dev(tp->tap_dev);	/* so we can destroy it later */
224 
225 	/* generate fake MAC address: 00 bd xx xx xx unit_no */
226 	ether_addr[0] = 0x00;
227 	ether_addr[1] = 0xbd;
228 	bcopy(&ticks, &ether_addr[2], 3);
229 	ether_addr[5] = (u_char)unit;
230 
231 	/* fill the rest and attach interface */
232 	ifp = &tp->tap_if;
233 	ifp->if_softc = tp;
234 
235 	if_initname(ifp, name, unit);
236 	if (unit > taplastunit)
237 		taplastunit = unit;
238 
239 	ifp->if_init = tapifinit;
240 	ifp->if_start = tapifstart;
241 	ifp->if_ioctl = tapifioctl;
242 	ifp->if_mtu = ETHERMTU;
243 	ifp->if_flags = (IFF_BROADCAST|IFF_SIMPLEX|IFF_MULTICAST);
244 	ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
245 	ifq_set_ready(&ifp->if_snd);
246 
247 	ether_ifattach(ifp, ether_addr, NULL);
248 
249 	tp->tap_flags |= TAP_INITED;
250 	tp->tap_devq.ifq_maxlen = ifqmaxlen;
251 
252 	TAPDEBUG(ifp, "created. minor = %#x\n", minor(tp->tap_dev));
253 } /* tapcreate */
254 
255 
256 /*
257  * tapopen
258  *
259  * to open tunnel. must be superuser
260  */
261 static int
262 tapopen(struct dev_open_args *ap)
263 {
264 	cdev_t dev = ap->a_head.a_dev;
265 	struct tap_softc *tp = NULL;
266 	struct ifnet *ifp = NULL;
267 	int error;
268 
269 	if ((error = suser_cred(ap->a_cred, 0)) != 0)
270 		return (error);
271 
272 	get_mplock();
273 	tp = dev->si_drv1;
274 	if (tp == NULL) {
275 		tapcreate(dev);
276 		tp = dev->si_drv1;
277 		ifp = &tp->arpcom.ac_if;
278 	} else {
279 		if (tp->tap_flags & TAP_OPEN) {
280 			rel_mplock();
281 			return (EBUSY);
282 		}
283 
284 		ifp = &tp->arpcom.ac_if;
285 
286                 EVENTHANDLER_INVOKE(ifnet_attach_event, ifp);
287 
288 		/* Announce the return of the interface. */
289 		rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
290 	}
291 
292 	bcopy(tp->arpcom.ac_enaddr, tp->ether_addr, sizeof(tp->ether_addr));
293 
294 	tp->tap_td = curthread;
295 	tp->tap_flags |= TAP_OPEN;
296 	taprefcnt ++;
297 
298 	TAPDEBUG(ifp, "opened. minor = %#x, refcnt = %d, taplastunit = %d\n",
299 		 minor(tp->tap_dev), taprefcnt, taplastunit);
300 
301 	rel_mplock();
302 	return (0);
303 }
304 
305 
306 /*
307  * tapclose
308  *
309  * close the device - mark i/f down & delete routing info
310  */
311 static int
312 tapclose(struct dev_close_args *ap)
313 {
314 	cdev_t dev = ap->a_head.a_dev;
315 	struct tap_softc	*tp = dev->si_drv1;
316 	struct ifnet		*ifp = &tp->tap_if;
317 	int clear_flags = 1;
318 
319 	/* junk all pending output */
320 
321 	get_mplock();
322 	ifq_purge(&ifp->if_snd);
323 
324 	/*
325 	 * do not bring the interface down, and do not anything with
326 	 * interface, if we are in VMnet mode. just close the device.
327 	 */
328 
329 	if ((tp->tap_flags & TAP_VMNET) == 0) {
330 		if (ifp->if_flags & IFF_UP)
331 			if_down(ifp);
332 		clear_flags = 0;
333 	}
334 	lwkt_serialize_enter(ifp->if_serializer);
335 	tapifstop(tp, clear_flags);
336 	lwkt_serialize_exit(ifp->if_serializer);
337 
338 	if_purgeaddrs_nolink(ifp);
339 
340 	EVENTHANDLER_INVOKE(ifnet_detach_event, ifp);
341 
342 	/* Announce the departure of the interface. */
343 	rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
344 
345 	funsetown(tp->tap_sigio);
346 	selwakeup(&tp->tap_rsel);
347 
348 	tp->tap_flags &= ~TAP_OPEN;
349 	tp->tap_td = NULL;
350 
351 	taprefcnt --;
352 	if (taprefcnt < 0) {
353 		taprefcnt = 0;
354 		if_printf(ifp, "minor = %#x, refcnt = %d is out of sync. "
355 			"set refcnt to 0\n", minor(tp->tap_dev), taprefcnt);
356 	}
357 
358 	TAPDEBUG(ifp, "closed. minor = %#x, refcnt = %d, taplastunit = %d\n",
359 		 minor(tp->tap_dev), taprefcnt, taplastunit);
360 
361 	rel_mplock();
362 	return (0);
363 }
364 
365 
366 /*
367  * tapifinit
368  *
369  * Network interface initialization function (called with if serializer held)
370  *
371  * MPSAFE
372  */
373 static void
374 tapifinit(void *xtp)
375 {
376 	struct tap_softc *tp = xtp;
377 	struct ifnet *ifp = &tp->tap_if;
378 
379 	TAPDEBUG(ifp, "initializing, minor = %#x\n", minor(tp->tap_dev));
380 
381 	ASSERT_SERIALIZED(ifp->if_serializer);
382 
383 	tapifstop(tp, 1);
384 
385 	ifp->if_flags |= IFF_RUNNING;
386 	ifp->if_flags &= ~IFF_OACTIVE;
387 
388 	/* attempt to start output */
389 	tapifstart(ifp);
390 }
391 
392 
393 /*
394  * tapifioctl
395  *
396  * Process an ioctl request on network interface (called with if serializer
397  * held).
398  *
399  * MPSAFE
400  */
401 static int
402 tapifioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
403 {
404 	struct tap_softc 	*tp = (struct tap_softc *)(ifp->if_softc);
405 	struct ifstat		*ifs = NULL;
406 	int			 dummy;
407 
408 	switch (cmd) {
409 		case SIOCSIFADDR:
410 		case SIOCGIFADDR:
411 		case SIOCSIFMTU:
412 			dummy = ether_ioctl(ifp, cmd, data);
413 			return (dummy);
414 
415 		case SIOCSIFFLAGS:
416 			if ((tp->tap_flags & TAP_VMNET) == 0) {
417 				/*
418 				 * Only for non-vmnet tap(4)
419 				 */
420 				if (ifp->if_flags & IFF_UP) {
421 					if ((ifp->if_flags & IFF_RUNNING) == 0)
422 						tapifinit(tp);
423 				} else {
424 					tapifstop(tp, 1);
425 				}
426 			} else {
427 				/* XXX */
428 			}
429 			break;
430 		case SIOCADDMULTI: /* XXX -- just like vmnet does */
431 		case SIOCDELMULTI:
432 			break;
433 
434 		case SIOCGIFSTATUS:
435 			ifs = (struct ifstat *)data;
436 			dummy = strlen(ifs->ascii);
437 			if (tp->tap_td != NULL && dummy < sizeof(ifs->ascii)) {
438 				if (tp->tap_td->td_proc) {
439 				    ksnprintf(ifs->ascii + dummy,
440 					sizeof(ifs->ascii) - dummy,
441 					"\tOpened by pid %d\n",
442 					(int)tp->tap_td->td_proc->p_pid);
443 				} else {
444 				    ksnprintf(ifs->ascii + dummy,
445 					sizeof(ifs->ascii) - dummy,
446 					"\tOpened by td %p\n", tp->tap_td);
447 				}
448 			}
449 			break;
450 
451 		default:
452 			return (EINVAL);
453 	}
454 
455 	return (0);
456 }
457 
458 
459 /*
460  * tapifstart
461  *
462  * Queue packets from higher level ready to put out (called with if serializer
463  * held)
464  *
465  * MPSAFE
466  */
467 static void
468 tapifstart(struct ifnet *ifp)
469 {
470 	struct tap_softc *tp = ifp->if_softc;
471 	struct ifqueue *ifq;
472 	struct mbuf *m;
473 	int has_data = 0;
474 
475 	TAPDEBUG(ifp, "starting, minor = %#x\n", minor(tp->tap_dev));
476 
477 	/*
478 	 * do not junk pending output if we are in VMnet mode.
479 	 * XXX: can this do any harm because of queue overflow?
480 	 */
481 
482 	if (((tp->tap_flags & TAP_VMNET) == 0) &&
483 	    ((tp->tap_flags & TAP_READY) != TAP_READY)) {
484 		TAPDEBUG(ifp, "not ready. minor = %#x, tap_flags = 0x%x\n",
485 			 minor(tp->tap_dev), tp->tap_flags);
486 		ifq_purge(&ifp->if_snd);
487 		return;
488 	}
489 
490 	ifp->if_flags |= IFF_OACTIVE;
491 
492 	ifq = &tp->tap_devq;
493 	while ((m = ifq_dequeue(&ifp->if_snd, NULL)) != NULL) {
494 		if (IF_QFULL(ifq)) {
495 			IF_DROP(ifq);
496 			ifp->if_oerrors++;
497 			m_freem(m);
498 		} else {
499 			IF_ENQUEUE(ifq, m);
500 			ifp->if_opackets++;
501 			has_data = 1;
502 		}
503 	}
504 
505 	if (has_data) {
506 		if (tp->tap_flags & TAP_RWAIT) {
507 			tp->tap_flags &= ~TAP_RWAIT;
508 			wakeup((caddr_t)tp);
509 		}
510 
511 		get_mplock();
512 		KNOTE(&tp->tap_rsel.si_note, 0);
513 		rel_mplock();
514 
515 		if ((tp->tap_flags & TAP_ASYNC) && (tp->tap_sigio != NULL)) {
516 			get_mplock();
517 			pgsigio(tp->tap_sigio, SIGIO, 0);
518 			rel_mplock();
519 		}
520 
521 		/*
522 		 * selwakeup is not MPSAFE.  tapifstart is.
523 		 */
524 		get_mplock();
525 		selwakeup(&tp->tap_rsel);
526 		rel_mplock();
527 	}
528 
529 	ifp->if_flags &= ~IFF_OACTIVE;
530 }
531 
532 
533 /*
534  * tapioctl
535  *
536  * The ops interface is now pretty minimal.  Called via fileops with nothing
537  * held.
538  *
539  * MPSAFE
540  */
541 static int
542 tapioctl(struct dev_ioctl_args *ap)
543 {
544 	cdev_t dev = ap->a_head.a_dev;
545 	caddr_t data = ap->a_data;
546 	struct tap_softc	*tp = dev->si_drv1;
547 	struct ifnet		*ifp = &tp->tap_if;
548  	struct tapinfo		*tapp = NULL;
549 	struct mbuf *mb;
550 	short f;
551 	int error;
552 
553 	lwkt_serialize_enter(ifp->if_serializer);
554 	error = 0;
555 
556 	switch (ap->a_cmd) {
557 	case TAPSIFINFO:
558 		tapp = (struct tapinfo *)data;
559 		ifp->if_mtu = tapp->mtu;
560 		ifp->if_type = tapp->type;
561 		ifp->if_baudrate = tapp->baudrate;
562 		break;
563 
564 	case TAPGIFINFO:
565 		tapp = (struct tapinfo *)data;
566 		tapp->mtu = ifp->if_mtu;
567 		tapp->type = ifp->if_type;
568 		tapp->baudrate = ifp->if_baudrate;
569 		break;
570 
571 	case TAPSDEBUG:
572 		tapdebug = *(int *)data;
573 		break;
574 
575 	case TAPGDEBUG:
576 		*(int *)data = tapdebug;
577 		break;
578 
579 	case FIOASYNC:
580 		if (*(int *)data)
581 			tp->tap_flags |= TAP_ASYNC;
582 		else
583 			tp->tap_flags &= ~TAP_ASYNC;
584 		break;
585 
586 	case FIONREAD:
587 		*(int *)data = 0;
588 
589 		/* Take a look at devq first */
590 		IF_POLL(&tp->tap_devq, mb);
591 		if (mb == NULL)
592 			mb = ifq_poll(&ifp->if_snd);
593 
594 		if (mb != NULL) {
595 			for(; mb != NULL; mb = mb->m_next)
596 				*(int *)data += mb->m_len;
597 		}
598 		break;
599 
600 	case FIOSETOWN:
601 		error = fsetown(*(int *)data, &tp->tap_sigio);
602 		break;
603 
604 	case FIOGETOWN:
605 		*(int *)data = fgetown(tp->tap_sigio);
606 		break;
607 
608 	/* this is deprecated, FIOSETOWN should be used instead */
609 	case TIOCSPGRP:
610 		error = fsetown(-(*(int *)data), &tp->tap_sigio);
611 		break;
612 
613 	/* this is deprecated, FIOGETOWN should be used instead */
614 	case TIOCGPGRP:
615 		*(int *)data = -fgetown(tp->tap_sigio);
616 		break;
617 
618 	/* VMware/VMnet port ioctl's */
619 
620 	case SIOCGIFFLAGS:	/* get ifnet flags */
621 		bcopy(&ifp->if_flags, data, sizeof(ifp->if_flags));
622 		break;
623 
624 	case VMIO_SIOCSIFFLAGS: /* VMware/VMnet SIOCSIFFLAGS */
625 		f = *(short *)data;
626 		f &= 0x0fff;
627 		f &= ~IFF_CANTCHANGE;
628 		f |= IFF_UP;
629 		ifp->if_flags = f | (ifp->if_flags & IFF_CANTCHANGE);
630 		break;
631 
632 	case OSIOCGIFADDR:	/* get MAC address of the remote side */
633 	case SIOCGIFADDR:
634 		bcopy(tp->ether_addr, data, sizeof(tp->ether_addr));
635 		break;
636 
637 	case SIOCSIFADDR:	/* set MAC address of the remote side */
638 		bcopy(data, tp->ether_addr, sizeof(tp->ether_addr));
639 		break;
640 
641 	default:
642 		error = ENOTTY;
643 		break;
644 	}
645 	lwkt_serialize_exit(ifp->if_serializer);
646 	return (error);
647 }
648 
649 
650 /*
651  * tapread
652  *
653  * The ops read interface - reads a packet at a time, or at
654  * least as much of a packet as can be read.
655  *
656  * Called from the fileops interface with nothing held.
657  *
658  * MPSAFE
659  */
660 static int
661 tapread(struct dev_read_args *ap)
662 {
663 	cdev_t dev = ap->a_head.a_dev;
664 	struct uio *uio = ap->a_uio;
665 	struct tap_softc	*tp = dev->si_drv1;
666 	struct ifnet		*ifp = &tp->tap_if;
667 	struct mbuf		*m0 = NULL;
668 	int			 error = 0, len;
669 
670 	TAPDEBUG(ifp, "reading, minor = %#x\n", minor(tp->tap_dev));
671 
672 	if ((tp->tap_flags & TAP_READY) != TAP_READY) {
673 		TAPDEBUG(ifp, "not ready. minor = %#x, tap_flags = 0x%x\n",
674 			 minor(tp->tap_dev), tp->tap_flags);
675 
676 		return (EHOSTDOWN);
677 	}
678 
679 	tp->tap_flags &= ~TAP_RWAIT;
680 
681 	/* sleep until we get a packet */
682 	do {
683 		lwkt_serialize_enter(ifp->if_serializer);
684 		IF_DEQUEUE(&tp->tap_devq, m0);
685 		if (m0 == NULL) {
686 			if (ap->a_ioflag & IO_NDELAY) {
687 				lwkt_serialize_exit(ifp->if_serializer);
688 				return (EWOULDBLOCK);
689 			}
690 			tp->tap_flags |= TAP_RWAIT;
691 			crit_enter();
692 			tsleep_interlock(tp);
693 			lwkt_serialize_exit(ifp->if_serializer);
694 			error = tsleep(tp, PCATCH, "taprd", 0);
695 			crit_exit();
696 			if (error)
697 				return (error);
698 		} else {
699 			lwkt_serialize_exit(ifp->if_serializer);
700 		}
701 	} while (m0 == NULL);
702 
703 	BPF_MTAP(ifp, m0);
704 
705 	/* xfer packet to user space */
706 	while ((m0 != NULL) && (uio->uio_resid > 0) && (error == 0)) {
707 		len = min(uio->uio_resid, m0->m_len);
708 		if (len == 0)
709 			break;
710 
711 		error = uiomove(mtod(m0, caddr_t), len, uio);
712 		m0 = m_free(m0);
713 	}
714 
715 	if (m0 != NULL) {
716 		TAPDEBUG(ifp, "dropping mbuf, minor = %#x\n",
717 			 minor(tp->tap_dev));
718 		m_freem(m0);
719 	}
720 
721 	return (error);
722 }
723 
724 /*
725  * tapwrite
726  *
727  * The ops write interface - an atomic write is a packet - or else!
728  *
729  * Called from the fileops interface with nothing held.
730  *
731  * MPSAFE
732  */
733 static int
734 tapwrite(struct dev_write_args *ap)
735 {
736 	cdev_t dev = ap->a_head.a_dev;
737 	struct uio *uio = ap->a_uio;
738 	struct tap_softc	*tp = dev->si_drv1;
739 	struct ifnet		*ifp = &tp->tap_if;
740 	struct mbuf		*top = NULL, **mp = NULL, *m = NULL;
741 	int		 	 error = 0, tlen, mlen;
742 
743 	TAPDEBUG(ifp, "writing, minor = %#x\n", minor(tp->tap_dev));
744 
745 	if (uio->uio_resid == 0)
746 		return (0);
747 
748 	if ((uio->uio_resid < 0) || (uio->uio_resid > TAPMRU)) {
749 		TAPDEBUG(ifp, "invalid packet len = %d, minor = %#x\n",
750 			 uio->uio_resid, minor(tp->tap_dev));
751 
752 		return (EIO);
753 	}
754 	tlen = uio->uio_resid;
755 
756 	/* get a header mbuf */
757 	MGETHDR(m, MB_DONTWAIT, MT_DATA);
758 	if (m == NULL)
759 		return (ENOBUFS);
760 	mlen = MHLEN;
761 
762 	top = 0;
763 	mp = &top;
764 	while ((error == 0) && (uio->uio_resid > 0)) {
765 		m->m_len = min(mlen, uio->uio_resid);
766 		error = uiomove(mtod(m, caddr_t), m->m_len, uio);
767 		*mp = m;
768 		mp = &m->m_next;
769 		if (uio->uio_resid > 0) {
770 			MGET(m, MB_DONTWAIT, MT_DATA);
771 			if (m == NULL) {
772 				error = ENOBUFS;
773 				break;
774 			}
775 			mlen = MLEN;
776 		}
777 	}
778 	if (error) {
779 		ifp->if_ierrors ++;
780 		if (top)
781 			m_freem(top);
782 		return (error);
783 	}
784 
785 	top->m_pkthdr.len = tlen;
786 	top->m_pkthdr.rcvif = ifp;
787 
788 	/*
789 	 * Ethernet bridge and bpf are handled in ether_input
790 	 *
791 	 * adjust mbuf and give packet to the ether_input
792 	 */
793 	lwkt_serialize_enter(ifp->if_serializer);
794 	ifp->if_input(ifp, top);
795 	ifp->if_ipackets ++; /* ibytes are counted in ether_input */
796 	lwkt_serialize_exit(ifp->if_serializer);
797 
798 	return (0);
799 }
800 
801 /*
802  * tappoll
803  *
804  * The poll interface, this is only useful on reads really. The write
805  * detect always returns true, write never blocks anyway, it either
806  * accepts the packet or drops it
807  *
808  * Called from the fileops interface with nothing held.
809  *
810  * MPSAFE
811  */
812 static int
813 tappoll(struct dev_poll_args *ap)
814 {
815 	cdev_t dev = ap->a_head.a_dev;
816 	struct tap_softc	*tp = dev->si_drv1;
817 	struct ifnet		*ifp = &tp->tap_if;
818 	int		 	 revents = 0;
819 
820 	TAPDEBUG(ifp, "polling, minor = %#x\n", minor(tp->tap_dev));
821 
822 	if (ap->a_events & (POLLIN | POLLRDNORM)) {
823 		if (!IF_QEMPTY(&tp->tap_devq)) {
824 			TAPDEBUG(ifp,
825 				 "has data in queue. minor = %#x\n",
826 				 minor(tp->tap_dev));
827 
828 			revents |= (ap->a_events & (POLLIN | POLLRDNORM));
829 		} else {
830 			TAPDEBUG(ifp, "waiting for data, minor = %#x\n",
831 				 minor(tp->tap_dev));
832 
833 			get_mplock();
834 			selrecord(curthread, &tp->tap_rsel);
835 			rel_mplock();
836 		}
837 	}
838 
839 	if (ap->a_events & (POLLOUT | POLLWRNORM))
840 		revents |= (ap->a_events & (POLLOUT | POLLWRNORM));
841 	ap->a_events = revents;
842 	return(0);
843 }
844 
845 /*
846  * tapkqfilter - called from the fileops interface with nothing held
847  *
848  * MPSAFE
849  */
850 static int filt_tapread(struct knote *kn, long hint);
851 static void filt_tapdetach(struct knote *kn);
852 static struct filterops tapread_filtops =
853 	{ 1, NULL, filt_tapdetach, filt_tapread };
854 
855 static int
856 tapkqfilter(struct dev_kqfilter_args *ap)
857 {
858 	cdev_t dev = ap->a_head.a_dev;
859 	struct knote *kn = ap->a_kn;
860 	struct tap_softc *tp;
861 	struct klist *list;
862 	struct ifnet *ifp;
863 
864 	get_mplock();
865 	tp = dev->si_drv1;
866 	ifp = &tp->tap_if;
867 	ap->a_result =0;
868 
869 	switch(kn->kn_filter) {
870 	case EVFILT_READ:
871 		list = &tp->tap_rsel.si_note;
872 		kn->kn_fop = &tapread_filtops;
873 		kn->kn_hook = (void *)tp;
874 		break;
875 	case EVFILT_WRITE:
876 		/* fall through */
877 	default:
878 		ap->a_result = 1;
879 		rel_mplock();
880 		return(0);
881 	}
882 	crit_enter();
883 	SLIST_INSERT_HEAD(list, kn, kn_selnext);
884 	crit_exit();
885 	rel_mplock();
886 	return(0);
887 }
888 
889 static int
890 filt_tapread(struct knote *kn, long hint)
891 {
892 	struct tap_softc *tp = (void *)kn->kn_hook;
893 
894 	if (IF_QEMPTY(&tp->tap_devq) == 0)	/* XXX serializer */
895 		return(1);
896 	else
897 		return(0);
898 }
899 
900 static void
901 filt_tapdetach(struct knote *kn)
902 {
903 	struct tap_softc *tp = (void *)kn->kn_hook;
904 
905 	SLIST_REMOVE(&tp->tap_rsel.si_note, kn, knote, kn_selnext);
906 }
907 
908 static void
909 tapifstop(struct tap_softc *tp, int clear_flags)
910 {
911 	struct ifnet *ifp = &tp->tap_if;
912 
913 	ASSERT_SERIALIZED(ifp->if_serializer);
914 	IF_DRAIN(&tp->tap_devq);
915 	if (clear_flags)
916 		ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
917 }
918