xref: /dragonfly/sys/net/tap/if_tap.c (revision 8e9b4bd4) 
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 1.37 2007/09/16 17:02:49 pavalos 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 
95 /* character device */
96 static d_open_t		tapopen;
97 static d_close_t	tapclose;
98 static d_read_t		tapread;
99 static d_write_t	tapwrite;
100 static d_ioctl_t	tapioctl;
101 static d_poll_t		tappoll;
102 static d_kqfilter_t	tapkqfilter;
103 
104 static struct dev_ops	tap_ops = {
105 	{ CDEV_NAME, CDEV_MAJOR, 0 },
106 	.d_open =	tapopen,
107 	.d_close =	tapclose,
108 	.d_read =	tapread,
109 	.d_write =	tapwrite,
110 	.d_ioctl =	tapioctl,
111 	.d_poll =	tappoll,
112 	.d_kqfilter =	tapkqfilter
113 };
114 
115 static int		taprefcnt = 0;		/* module ref. counter   */
116 static int		taplastunit = -1;	/* max. open unit number */
117 static int		tapdebug = 0;		/* debug flag            */
118 
119 MALLOC_DECLARE(M_TAP);
120 MALLOC_DEFINE(M_TAP, CDEV_NAME, "Ethernet tunnel interface");
121 SYSCTL_INT(_debug, OID_AUTO, if_tap_debug, CTLFLAG_RW, &tapdebug, 0, "");
122 DEV_MODULE(if_tap, tapmodevent, NULL);
123 
124 /*
125  * tapmodevent
126  *
127  * module event handler
128  */
129 static int
130 tapmodevent(module_t mod, int type, void *data)
131 {
132 	static int		 attached = 0;
133 	struct ifnet		*ifp = NULL;
134 	int			 unit;
135 
136 	switch (type) {
137 	case MOD_LOAD:
138 		if (attached)
139 			return (EEXIST);
140 
141 		dev_ops_add(&tap_ops, 0, 0);
142 		attached = 1;
143 	break;
144 
145 	case MOD_UNLOAD:
146 		if (taprefcnt > 0)
147 			return (EBUSY);
148 
149 		dev_ops_remove(&tap_ops, 0, 0);
150 
151 		/* XXX: maintain tap ifs in a local list */
152 		unit = 0;
153 		while (unit <= taplastunit) {
154 			TAILQ_FOREACH(ifp, &ifnet, if_link) {
155 				if ((strcmp(ifp->if_dname, TAP) == 0) ||
156 				    (strcmp(ifp->if_dname, VMNET) == 0)) {
157 					if (ifp->if_dunit == unit)
158 						break;
159 				}
160 			}
161 
162 			if (ifp != NULL) {
163 				struct tap_softc	*tp = ifp->if_softc;
164 
165 				TAPDEBUG(ifp, "detached. minor = %#x, " \
166 					"taplastunit = %d\n",
167 					minor(tp->tap_dev), taplastunit);
168 
169 				ether_ifdetach(ifp);
170 				destroy_dev(tp->tap_dev);
171 				kfree(tp, M_TAP);
172 			}
173 			else
174 				unit ++;
175 		}
176 
177 		attached = 0;
178 	break;
179 
180 	default:
181 		return (EOPNOTSUPP);
182 	}
183 
184 	return (0);
185 } /* tapmodevent */
186 
187 
188 /*
189  * tapcreate
190  *
191  * to create interface
192  */
193 static void
194 tapcreate(cdev_t dev)
195 {
196 	struct ifnet		*ifp = NULL;
197 	struct tap_softc	*tp = NULL;
198 	uint8_t			ether_addr[ETHER_ADDR_LEN];
199 	int			 unit;
200 	char			*name = NULL;
201 
202 	/* allocate driver storage and create device */
203 	MALLOC(tp, struct tap_softc *, sizeof(*tp), M_TAP, M_WAITOK | M_ZERO);
204 
205 	/* select device: tap or vmnet */
206 	if (minor(dev) & VMNET_DEV_MASK) {
207 		name = VMNET;
208 		unit = lminor(dev) & 0xff;
209 		tp->tap_flags |= TAP_VMNET;
210 	}
211 	else {
212 		name = TAP;
213 		unit = lminor(dev);
214 	}
215 
216 	tp->tap_dev = make_dev(&tap_ops, minor(dev), UID_ROOT, GID_WHEEL,
217 						0600, "%s%d", name, unit);
218 	tp->tap_dev->si_drv1 = dev->si_drv1 = tp;
219 	reference_dev(tp->tap_dev);	/* so we can destroy it later */
220 
221 	/* generate fake MAC address: 00 bd xx xx xx unit_no */
222 	ether_addr[0] = 0x00;
223 	ether_addr[1] = 0xbd;
224 	bcopy(&ticks, &ether_addr[2], 3);
225 	ether_addr[5] = (u_char)unit;
226 
227 	/* fill the rest and attach interface */
228 	ifp = &tp->tap_if;
229 	ifp->if_softc = tp;
230 
231 	if_initname(ifp, name, unit);
232 	if (unit > taplastunit)
233 		taplastunit = unit;
234 
235 	ifp->if_init = tapifinit;
236 	ifp->if_start = tapifstart;
237 	ifp->if_ioctl = tapifioctl;
238 	ifp->if_mtu = ETHERMTU;
239 	ifp->if_flags = (IFF_BROADCAST|IFF_SIMPLEX|IFF_MULTICAST);
240 	ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
241 	ifq_set_ready(&ifp->if_snd);
242 
243 	ether_ifattach(ifp, ether_addr, NULL);
244 
245 	tp->tap_flags |= TAP_INITED;
246 
247 	TAPDEBUG(ifp, "created. minor = %#x\n", minor(tp->tap_dev));
248 } /* tapcreate */
249 
250 
251 /*
252  * tapopen
253  *
254  * to open tunnel. must be superuser
255  */
256 static int
257 tapopen(struct dev_open_args *ap)
258 {
259 	cdev_t dev = ap->a_head.a_dev;
260 	struct tap_softc *tp = NULL;
261 	struct ifnet *ifp = NULL;
262 	int error;
263 
264 	if ((error = suser_cred(ap->a_cred, 0)) != 0)
265 		return (error);
266 
267 	get_mplock();
268 	tp = dev->si_drv1;
269 	if (tp == NULL) {
270 		tapcreate(dev);
271 		tp = dev->si_drv1;
272 		ifp = &tp->arpcom.ac_if;
273 	} else {
274 		ifp = &tp->arpcom.ac_if;
275 
276                 EVENTHANDLER_INVOKE(ifnet_attach_event, ifp);
277 
278 		/* Announce the return of the interface. */
279 		rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
280 	}
281 
282 	if (tp->tap_flags & TAP_OPEN) {
283 		rel_mplock();
284 		return (EBUSY);
285 	}
286 
287 	bcopy(tp->arpcom.ac_enaddr, tp->ether_addr, sizeof(tp->ether_addr));
288 
289 	tp->tap_td = curthread;
290 	tp->tap_flags |= TAP_OPEN;
291 	taprefcnt ++;
292 
293 	TAPDEBUG(ifp, "opened. minor = %#x, refcnt = %d, taplastunit = %d\n",
294 		 minor(tp->tap_dev), taprefcnt, taplastunit);
295 
296 	rel_mplock();
297 	return (0);
298 }
299 
300 
301 /*
302  * tapclose
303  *
304  * close the device - mark i/f down & delete routing info
305  */
306 static int
307 tapclose(struct dev_close_args *ap)
308 {
309 	cdev_t dev = ap->a_head.a_dev;
310 	struct tap_softc	*tp = dev->si_drv1;
311 	struct ifnet		*ifp = &tp->tap_if;
312 
313 	/* junk all pending output */
314 
315 	get_mplock();
316 	lwkt_serialize_enter(ifp->if_serializer);
317 	ifq_purge(&ifp->if_snd);
318 	lwkt_serialize_exit(ifp->if_serializer);
319 
320 	/*
321 	 * do not bring the interface down, and do not anything with
322 	 * interface, if we are in VMnet mode. just close the device.
323 	 */
324 
325 	if (((tp->tap_flags & TAP_VMNET) == 0) && (ifp->if_flags & IFF_UP)) {
326 		EVENTHANDLER_INVOKE(ifnet_detach_event, ifp);
327 
328 		/* Announce the departure of the interface. */
329 		rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
330 
331 		if_down(ifp);
332 		lwkt_serialize_enter(ifp->if_serializer);
333 		if (ifp->if_flags & IFF_RUNNING) {
334 			/* find internet addresses and delete routes */
335 			struct ifaddr	*ifa = NULL;
336 
337 			TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
338 				if (ifa->ifa_addr->sa_family == AF_INET) {
339 					rtinit(ifa, (int)RTM_DELETE, 0);
340 
341 					/* remove address from interface */
342 					bzero(ifa->ifa_addr,
343 						   sizeof(*(ifa->ifa_addr)));
344 					bzero(ifa->ifa_dstaddr,
345 						   sizeof(*(ifa->ifa_dstaddr)));
346 					bzero(ifa->ifa_netmask,
347 						   sizeof(*(ifa->ifa_netmask)));
348 				}
349 			}
350 
351 			ifp->if_flags &= ~IFF_RUNNING;
352 		}
353 		lwkt_serialize_exit(ifp->if_serializer);
354 	}
355 
356 	funsetown(tp->tap_sigio);
357 	selwakeup(&tp->tap_rsel);
358 
359 	tp->tap_flags &= ~TAP_OPEN;
360 	tp->tap_td = NULL;
361 
362 	taprefcnt --;
363 	if (taprefcnt < 0) {
364 		taprefcnt = 0;
365 		if_printf(ifp, "minor = %#x, refcnt = %d is out of sync. "
366 			"set refcnt to 0\n", minor(tp->tap_dev), taprefcnt);
367 	}
368 
369 	TAPDEBUG(ifp, "closed. minor = %#x, refcnt = %d, taplastunit = %d\n",
370 		 minor(tp->tap_dev), taprefcnt, taplastunit);
371 
372 	rel_mplock();
373 	return (0);
374 }
375 
376 
377 /*
378  * tapifinit
379  *
380  * Network interface initialization function (called with if serializer held)
381  *
382  * MPSAFE
383  */
384 static void
385 tapifinit(void *xtp)
386 {
387 	struct tap_softc	*tp = (struct tap_softc *)xtp;
388 	struct ifnet		*ifp = &tp->tap_if;
389 
390 	TAPDEBUG(ifp, "initializing, minor = %#x\n", minor(tp->tap_dev));
391 
392 	ifp->if_flags |= IFF_RUNNING;
393 	ifp->if_flags &= ~IFF_OACTIVE;
394 
395 	/* attempt to start output */
396 	tapifstart(ifp);
397 }
398 
399 
400 /*
401  * tapifioctl
402  *
403  * Process an ioctl request on network interface (called with if serializer
404  * held).
405  *
406  * MPSAFE
407  */
408 static int
409 tapifioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
410 {
411 	struct tap_softc 	*tp = (struct tap_softc *)(ifp->if_softc);
412 	struct ifstat		*ifs = NULL;
413 	int			 dummy;
414 
415 	switch (cmd) {
416 		case SIOCSIFADDR:
417 		case SIOCGIFADDR:
418 		case SIOCSIFMTU:
419 			dummy = ether_ioctl(ifp, cmd, data);
420 			return (dummy);
421 
422 		case SIOCSIFFLAGS:
423 			if ((tp->tap_flags & TAP_VMNET) == 0) {
424 				/*
425 				 * Only for non-vmnet tap(4)
426 				 */
427 				if (ifp->if_flags & IFF_UP) {
428 					if ((ifp->if_flags & IFF_RUNNING) == 0)
429 						tapifinit(tp);
430 				}
431 			}
432 			break;
433 		case SIOCADDMULTI: /* XXX -- just like vmnet does */
434 		case SIOCDELMULTI:
435 			break;
436 
437 		case SIOCGIFSTATUS:
438 			ifs = (struct ifstat *)data;
439 			dummy = strlen(ifs->ascii);
440 			if (tp->tap_td != NULL && dummy < sizeof(ifs->ascii)) {
441 				if (tp->tap_td->td_proc) {
442 				    ksnprintf(ifs->ascii + dummy,
443 					sizeof(ifs->ascii) - dummy,
444 					"\tOpened by pid %d\n",
445 					(int)tp->tap_td->td_proc->p_pid);
446 				} else {
447 				    ksnprintf(ifs->ascii + dummy,
448 					sizeof(ifs->ascii) - dummy,
449 					"\tOpened by td %p\n", tp->tap_td);
450 				}
451 			}
452 			break;
453 
454 		default:
455 			return (EINVAL);
456 	}
457 
458 	return (0);
459 }
460 
461 
462 /*
463  * tapifstart
464  *
465  * Queue packets from higher level ready to put out (called with if serializer
466  * held)
467  *
468  * MPSAFE
469  */
470 static void
471 tapifstart(struct ifnet *ifp)
472 {
473 	struct tap_softc	*tp = ifp->if_softc;
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 
487 		ifq_purge(&ifp->if_snd);
488 		return;
489 	}
490 
491 	ifp->if_flags |= IFF_OACTIVE;
492 
493 	if (!ifq_is_empty(&ifp->if_snd)) {
494 		if (tp->tap_flags & TAP_RWAIT) {
495 			tp->tap_flags &= ~TAP_RWAIT;
496 			wakeup((caddr_t)tp);
497 		}
498 		KNOTE(&tp->tap_rsel.si_note, 0);
499 
500 		if ((tp->tap_flags & TAP_ASYNC) && (tp->tap_sigio != NULL)) {
501 			get_mplock();
502 			pgsigio(tp->tap_sigio, SIGIO, 0);
503 			rel_mplock();
504 		}
505 
506 		/*
507 		 * selwakeup is not MPSAFE.  tapifstart is.
508 		 */
509 		get_mplock();
510 		selwakeup(&tp->tap_rsel);
511 		rel_mplock();
512 		ifp->if_opackets ++; /* obytes are counted in ether_output */
513 	}
514 
515 	ifp->if_flags &= ~IFF_OACTIVE;
516 }
517 
518 
519 /*
520  * tapioctl
521  *
522  * The ops interface is now pretty minimal.  Called via fileops with nothing
523  * held.
524  *
525  * MPSAFE
526  */
527 static int
528 tapioctl(struct dev_ioctl_args *ap)
529 {
530 	cdev_t dev = ap->a_head.a_dev;
531 	caddr_t data = ap->a_data;
532 	struct tap_softc	*tp = dev->si_drv1;
533 	struct ifnet		*ifp = &tp->tap_if;
534  	struct tapinfo		*tapp = NULL;
535 	struct mbuf *mb;
536 	short f;
537 	int error;
538 
539 	lwkt_serialize_enter(ifp->if_serializer);
540 	error = 0;
541 
542 	switch (ap->a_cmd) {
543 	case TAPSIFINFO:
544 		tapp = (struct tapinfo *)data;
545 		ifp->if_mtu = tapp->mtu;
546 		ifp->if_type = tapp->type;
547 		ifp->if_baudrate = tapp->baudrate;
548 		break;
549 
550 	case TAPGIFINFO:
551 		tapp = (struct tapinfo *)data;
552 		tapp->mtu = ifp->if_mtu;
553 		tapp->type = ifp->if_type;
554 		tapp->baudrate = ifp->if_baudrate;
555 		break;
556 
557 	case TAPSDEBUG:
558 		tapdebug = *(int *)data;
559 		break;
560 
561 	case TAPGDEBUG:
562 		*(int *)data = tapdebug;
563 		break;
564 
565 	case FIOASYNC:
566 		if (*(int *)data)
567 			tp->tap_flags |= TAP_ASYNC;
568 		else
569 			tp->tap_flags &= ~TAP_ASYNC;
570 		break;
571 
572 	case FIONREAD:
573 		*(int *)data = 0;
574 		if ((mb = ifq_poll(&ifp->if_snd)) != NULL) {
575 			for(; mb != NULL; mb = mb->m_next)
576 				*(int *)data += mb->m_len;
577 		}
578 		break;
579 
580 	case FIOSETOWN:
581 		error = fsetown(*(int *)data, &tp->tap_sigio);
582 		break;
583 
584 	case FIOGETOWN:
585 		*(int *)data = fgetown(tp->tap_sigio);
586 		break;
587 
588 	/* this is deprecated, FIOSETOWN should be used instead */
589 	case TIOCSPGRP:
590 		error = fsetown(-(*(int *)data), &tp->tap_sigio);
591 		break;
592 
593 	/* this is deprecated, FIOGETOWN should be used instead */
594 	case TIOCGPGRP:
595 		*(int *)data = -fgetown(tp->tap_sigio);
596 		break;
597 
598 	/* VMware/VMnet port ioctl's */
599 
600 	case SIOCGIFFLAGS:	/* get ifnet flags */
601 		bcopy(&ifp->if_flags, data, sizeof(ifp->if_flags));
602 		break;
603 
604 	case VMIO_SIOCSIFFLAGS: /* VMware/VMnet SIOCSIFFLAGS */
605 		f = *(short *)data;
606 		f &= 0x0fff;
607 		f &= ~IFF_CANTCHANGE;
608 		f |= IFF_UP;
609 		ifp->if_flags = f | (ifp->if_flags & IFF_CANTCHANGE);
610 		break;
611 
612 	case OSIOCGIFADDR:	/* get MAC address of the remote side */
613 	case SIOCGIFADDR:
614 		bcopy(tp->ether_addr, data, sizeof(tp->ether_addr));
615 		break;
616 
617 	case SIOCSIFADDR:	/* set MAC address of the remote side */
618 		bcopy(data, tp->ether_addr, sizeof(tp->ether_addr));
619 		break;
620 
621 	default:
622 		error = ENOTTY;
623 		break;
624 	}
625 	lwkt_serialize_exit(ifp->if_serializer);
626 	return (error);
627 }
628 
629 
630 /*
631  * tapread
632  *
633  * The ops read interface - reads a packet at a time, or at
634  * least as much of a packet as can be read.
635  *
636  * Called from the fileops interface with nothing held.
637  *
638  * MPSAFE
639  */
640 static int
641 tapread(struct dev_read_args *ap)
642 {
643 	cdev_t dev = ap->a_head.a_dev;
644 	struct uio *uio = ap->a_uio;
645 	struct tap_softc	*tp = dev->si_drv1;
646 	struct ifnet		*ifp = &tp->tap_if;
647 	struct mbuf		*m0 = NULL;
648 	int			 error = 0, len;
649 
650 	TAPDEBUG(ifp, "reading, minor = %#x\n", minor(tp->tap_dev));
651 
652 	if ((tp->tap_flags & TAP_READY) != TAP_READY) {
653 		TAPDEBUG(ifp, "not ready. minor = %#x, tap_flags = 0x%x\n",
654 			 minor(tp->tap_dev), tp->tap_flags);
655 
656 		return (EHOSTDOWN);
657 	}
658 
659 	tp->tap_flags &= ~TAP_RWAIT;
660 
661 	/* sleep until we get a packet */
662 	do {
663 		lwkt_serialize_enter(ifp->if_serializer);
664 		m0 = ifq_dequeue(&ifp->if_snd, NULL);
665 		if (m0 == NULL) {
666 			if (ap->a_ioflag & IO_NDELAY) {
667 				lwkt_serialize_exit(ifp->if_serializer);
668 				return (EWOULDBLOCK);
669 			}
670 			tp->tap_flags |= TAP_RWAIT;
671 			crit_enter();
672 			tsleep_interlock(tp);
673 			lwkt_serialize_exit(ifp->if_serializer);
674 			error = tsleep(tp, PCATCH, "taprd", 0);
675 			crit_exit();
676 			if (error)
677 				return (error);
678 		} else {
679 			lwkt_serialize_exit(ifp->if_serializer);
680 		}
681 	} while (m0 == NULL);
682 
683 	BPF_MTAP(ifp, m0);
684 
685 	/* xfer packet to user space */
686 	while ((m0 != NULL) && (uio->uio_resid > 0) && (error == 0)) {
687 		len = min(uio->uio_resid, m0->m_len);
688 		if (len == 0)
689 			break;
690 
691 		error = uiomove(mtod(m0, caddr_t), len, uio);
692 		m0 = m_free(m0);
693 	}
694 
695 	if (m0 != NULL) {
696 		TAPDEBUG(ifp, "dropping mbuf, minor = %#x\n",
697 			 minor(tp->tap_dev));
698 		m_freem(m0);
699 	}
700 
701 	return (error);
702 }
703 
704 /*
705  * tapwrite
706  *
707  * The ops write interface - an atomic write is a packet - or else!
708  *
709  * Called from the fileops interface with nothing held.
710  *
711  * MPSAFE
712  */
713 static int
714 tapwrite(struct dev_write_args *ap)
715 {
716 	cdev_t dev = ap->a_head.a_dev;
717 	struct uio *uio = ap->a_uio;
718 	struct tap_softc	*tp = dev->si_drv1;
719 	struct ifnet		*ifp = &tp->tap_if;
720 	struct mbuf		*top = NULL, **mp = NULL, *m = NULL;
721 	int		 	 error = 0, tlen, mlen;
722 
723 	TAPDEBUG(ifp, "writing, minor = %#x\n", minor(tp->tap_dev));
724 
725 	if (uio->uio_resid == 0)
726 		return (0);
727 
728 	if ((uio->uio_resid < 0) || (uio->uio_resid > TAPMRU)) {
729 		TAPDEBUG(ifp, "invalid packet len = %d, minor = %#x\n",
730 			 uio->uio_resid, minor(tp->tap_dev));
731 
732 		return (EIO);
733 	}
734 	tlen = uio->uio_resid;
735 
736 	/* get a header mbuf */
737 	MGETHDR(m, MB_DONTWAIT, MT_DATA);
738 	if (m == NULL)
739 		return (ENOBUFS);
740 	mlen = MHLEN;
741 
742 	top = 0;
743 	mp = &top;
744 	while ((error == 0) && (uio->uio_resid > 0)) {
745 		m->m_len = min(mlen, uio->uio_resid);
746 		error = uiomove(mtod(m, caddr_t), m->m_len, uio);
747 		*mp = m;
748 		mp = &m->m_next;
749 		if (uio->uio_resid > 0) {
750 			MGET(m, MB_DONTWAIT, MT_DATA);
751 			if (m == NULL) {
752 				error = ENOBUFS;
753 				break;
754 			}
755 			mlen = MLEN;
756 		}
757 	}
758 	if (error) {
759 		ifp->if_ierrors ++;
760 		if (top)
761 			m_freem(top);
762 		return (error);
763 	}
764 
765 	top->m_pkthdr.len = tlen;
766 	top->m_pkthdr.rcvif = ifp;
767 
768 	/*
769 	 * Ethernet bridge and bpf are handled in ether_input
770 	 *
771 	 * adjust mbuf and give packet to the ether_input
772 	 */
773 	lwkt_serialize_enter(ifp->if_serializer);
774 	ifp->if_input(ifp, top);
775 	ifp->if_ipackets ++; /* ibytes are counted in ether_input */
776 	lwkt_serialize_exit(ifp->if_serializer);
777 
778 	return (0);
779 }
780 
781 /*
782  * tappoll
783  *
784  * The poll interface, this is only useful on reads really. The write
785  * detect always returns true, write never blocks anyway, it either
786  * accepts the packet or drops it
787  *
788  * Called from the fileops interface with nothing held.
789  *
790  * MPSAFE
791  */
792 static int
793 tappoll(struct dev_poll_args *ap)
794 {
795 	cdev_t dev = ap->a_head.a_dev;
796 	struct tap_softc	*tp = dev->si_drv1;
797 	struct ifnet		*ifp = &tp->tap_if;
798 	int		 	 revents = 0;
799 
800 	TAPDEBUG(ifp, "polling, minor = %#x\n", minor(tp->tap_dev));
801 
802 	lwkt_serialize_enter(ifp->if_serializer);
803 	if (ap->a_events & (POLLIN | POLLRDNORM)) {
804 		if (!ifq_is_empty(&ifp->if_snd)) {
805 			TAPDEBUG(ifp,
806 				 "has data in queue. minor = %#x\n",
807 				 minor(tp->tap_dev));
808 
809 			revents |= (ap->a_events & (POLLIN | POLLRDNORM));
810 		} else {
811 			TAPDEBUG(ifp, "waiting for data, minor = %#x\n",
812 				 minor(tp->tap_dev));
813 
814 			get_mplock();
815 			selrecord(curthread, &tp->tap_rsel);
816 			rel_mplock();
817 		}
818 	}
819 	lwkt_serialize_exit(ifp->if_serializer);
820 
821 	if (ap->a_events & (POLLOUT | POLLWRNORM))
822 		revents |= (ap->a_events & (POLLOUT | POLLWRNORM));
823 	ap->a_events = revents;
824 	return(0);
825 }
826 
827 /*
828  * tapkqfilter - called from the fileops interface with nothing held
829  *
830  * MPSAFE
831  */
832 static int filt_tapread(struct knote *kn, long hint);
833 static void filt_tapdetach(struct knote *kn);
834 static struct filterops tapread_filtops =
835 	{ 1, NULL, filt_tapdetach, filt_tapread };
836 
837 static int
838 tapkqfilter(struct dev_kqfilter_args *ap)
839 {
840 	cdev_t dev = ap->a_head.a_dev;
841 	struct knote *kn = ap->a_kn;
842 	struct tap_softc *tp;
843 	struct klist *list;
844 	struct ifnet *ifp;
845 
846 	get_mplock();
847 	tp = dev->si_drv1;
848 	ifp = &tp->tap_if;
849 	ap->a_result =0;
850 
851 	switch(kn->kn_filter) {
852 	case EVFILT_READ:
853 		list = &tp->tap_rsel.si_note;
854 		kn->kn_fop = &tapread_filtops;
855 		kn->kn_hook = (void *)tp;
856 		break;
857 	case EVFILT_WRITE:
858 		/* fall through */
859 	default:
860 		ap->a_result = 1;
861 		rel_mplock();
862 		return(0);
863 	}
864 	crit_enter();
865 	SLIST_INSERT_HEAD(list, kn, kn_selnext);
866 	crit_exit();
867 	rel_mplock();
868 	return(0);
869 }
870 
871 static int
872 filt_tapread(struct knote *kn, long hint)
873 {
874 	struct tap_softc *tp = (void *)kn->kn_hook;
875 	struct ifnet *ifp = &tp->tap_if;
876 
877 	if (ifq_is_empty(&ifp->if_snd) == 0) {
878 		return(1);
879 	} else {
880 		return(0);
881 	}
882 }
883 
884 static void
885 filt_tapdetach(struct knote *kn)
886 {
887 	struct tap_softc *tp = (void *)kn->kn_hook;
888 
889 	SLIST_REMOVE(&tp->tap_rsel.si_note, kn, knote, kn_selnext);
890 }
891