xref: /dragonfly/sys/net/bpf.c (revision e3543cd5)
1 /*
2  * Copyright (c) 1990, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from the Stanford/CMU enet packet filter,
6  * (net/enet.c) distributed as part of 4.3BSD, and code contributed
7  * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
8  * Berkeley Laboratory.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *      @(#)bpf.c	8.2 (Berkeley) 3/28/94
39  *
40  * $FreeBSD: src/sys/net/bpf.c,v 1.59.2.12 2002/04/14 21:41:48 luigi Exp $
41  * $DragonFly: src/sys/net/bpf.c,v 1.50 2008/09/23 11:28:49 sephe Exp $
42  */
43 
44 #include "use_bpf.h"
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/conf.h>
49 #include <sys/device.h>
50 #include <sys/malloc.h>
51 #include <sys/mbuf.h>
52 #include <sys/time.h>
53 #include <sys/proc.h>
54 #include <sys/signalvar.h>
55 #include <sys/filio.h>
56 #include <sys/sockio.h>
57 #include <sys/ttycom.h>
58 #include <sys/filedesc.h>
59 
60 #include <sys/poll.h>
61 
62 #include <sys/socket.h>
63 #include <sys/vnode.h>
64 
65 #include <sys/thread2.h>
66 
67 #include <net/if.h>
68 #include <net/bpf.h>
69 #include <net/bpfdesc.h>
70 #include <net/netmsg2.h>
71 
72 #include <netinet/in.h>
73 #include <netinet/if_ether.h>
74 #include <sys/kernel.h>
75 #include <sys/sysctl.h>
76 
77 #include <sys/devfs.h>
78 
79 struct netmsg_bpf_output {
80 	struct netmsg	nm_netmsg;
81 	struct mbuf	*nm_mbuf;
82 	struct ifnet	*nm_ifp;
83 	struct sockaddr	*nm_dst;
84 };
85 
86 MALLOC_DEFINE(M_BPF, "BPF", "BPF data");
87 DEVFS_DECLARE_CLONE_BITMAP(bpf);
88 #define BPF_PREALLOCATED_UNITS	4
89 
90 #if NBPF > 0
91 
92 /*
93  * The default read buffer size is patchable.
94  */
95 static int bpf_bufsize = BPF_DEFAULTBUFSIZE;
96 SYSCTL_INT(_debug, OID_AUTO, bpf_bufsize, CTLFLAG_RW,
97 	   &bpf_bufsize, 0, "");
98 int bpf_maxbufsize = BPF_MAXBUFSIZE;
99 SYSCTL_INT(_debug, OID_AUTO, bpf_maxbufsize, CTLFLAG_RW,
100 	   &bpf_maxbufsize, 0, "");
101 
102 /*
103  *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
104  */
105 static struct bpf_if	*bpf_iflist;
106 
107 static int	bpf_allocbufs(struct bpf_d *);
108 static void	bpf_attachd(struct bpf_d *d, struct bpf_if *bp);
109 static void	bpf_detachd(struct bpf_d *d);
110 static void	bpf_resetd(struct bpf_d *);
111 static void	bpf_freed(struct bpf_d *);
112 static void	bpf_mcopy(const void *, void *, size_t);
113 static int	bpf_movein(struct uio *, int, struct mbuf **,
114 			   struct sockaddr *, int *, struct bpf_insn *);
115 static int	bpf_setif(struct bpf_d *, struct ifreq *);
116 static void	bpf_timed_out(void *);
117 static void	bpf_wakeup(struct bpf_d *);
118 static void	catchpacket(struct bpf_d *, u_char *, u_int, u_int,
119 			    void (*)(const void *, void *, size_t),
120 			    const struct timeval *);
121 static int	bpf_setf(struct bpf_d *, struct bpf_program *, u_long cmd);
122 static int	bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
123 static int	bpf_setdlt(struct bpf_d *, u_int);
124 static void	bpf_drvinit(void *unused);
125 
126 static d_open_t		bpfopen;
127 static d_clone_t	bpfclone;
128 static d_close_t	bpfclose;
129 static d_read_t		bpfread;
130 static d_write_t	bpfwrite;
131 static d_ioctl_t	bpfioctl;
132 static d_poll_t		bpfpoll;
133 
134 #define CDEV_MAJOR 23
135 static struct dev_ops bpf_ops = {
136 	{ "bpf", CDEV_MAJOR, 0 },
137 	.d_open =	bpfopen,
138 	.d_close =	bpfclose,
139 	.d_read =	bpfread,
140 	.d_write =	bpfwrite,
141 	.d_ioctl =	bpfioctl,
142 	.d_poll =	bpfpoll,
143 };
144 
145 
146 static int
147 bpf_movein(struct uio *uio, int linktype, struct mbuf **mp,
148 	   struct sockaddr *sockp, int *datlen, struct bpf_insn *wfilter)
149 {
150 	struct mbuf *m;
151 	int error;
152 	int len;
153 	int hlen;
154 	int slen;
155 
156 	*datlen = 0;
157 	*mp = NULL;
158 
159 	/*
160 	 * Build a sockaddr based on the data link layer type.
161 	 * We do this at this level because the ethernet header
162 	 * is copied directly into the data field of the sockaddr.
163 	 * In the case of SLIP, there is no header and the packet
164 	 * is forwarded as is.
165 	 * Also, we are careful to leave room at the front of the mbuf
166 	 * for the link level header.
167 	 */
168 	switch (linktype) {
169 	case DLT_SLIP:
170 		sockp->sa_family = AF_INET;
171 		hlen = 0;
172 		break;
173 
174 	case DLT_EN10MB:
175 		sockp->sa_family = AF_UNSPEC;
176 		/* XXX Would MAXLINKHDR be better? */
177 		hlen = sizeof(struct ether_header);
178 		break;
179 
180 	case DLT_RAW:
181 	case DLT_NULL:
182 		sockp->sa_family = AF_UNSPEC;
183 		hlen = 0;
184 		break;
185 
186 	case DLT_ATM_RFC1483:
187 		/*
188 		 * en atm driver requires 4-byte atm pseudo header.
189 		 * though it isn't standard, vpi:vci needs to be
190 		 * specified anyway.
191 		 */
192 		sockp->sa_family = AF_UNSPEC;
193 		hlen = 12;	/* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
194 		break;
195 
196 	case DLT_PPP:
197 		sockp->sa_family = AF_UNSPEC;
198 		hlen = 4;	/* This should match PPP_HDRLEN */
199 		break;
200 
201 	default:
202 		return(EIO);
203 	}
204 
205 	len = uio->uio_resid;
206 	*datlen = len - hlen;
207 	if ((unsigned)len > MCLBYTES)
208 		return(EIO);
209 
210 	m = m_getl(len, MB_WAIT, MT_DATA, M_PKTHDR, NULL);
211 	if (m == NULL)
212 		return(ENOBUFS);
213 	m->m_pkthdr.len = m->m_len = len;
214 	m->m_pkthdr.rcvif = NULL;
215 	*mp = m;
216 
217 	if (m->m_len < hlen) {
218 		error = EPERM;
219 		goto bad;
220 	}
221 
222 	error = uiomove(mtod(m, u_char *), len, uio);
223 	if (error)
224 		goto bad;
225 
226 	slen = bpf_filter(wfilter, mtod(m, u_char *), len, len);
227 	if (slen == 0) {
228 		error = EPERM;
229 		goto bad;
230 	}
231 
232 	/*
233 	 * Make room for link header, and copy it to sockaddr.
234 	 */
235 	if (hlen != 0) {
236 		bcopy(m->m_data, sockp->sa_data, hlen);
237 		m->m_pkthdr.len -= hlen;
238 		m->m_len -= hlen;
239 		m->m_data += hlen; /* XXX */
240 	}
241 	return (0);
242 bad:
243 	m_freem(m);
244 	return(error);
245 }
246 
247 /*
248  * Attach file to the bpf interface, i.e. make d listen on bp.
249  * Must be called at splimp.
250  */
251 static void
252 bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
253 {
254 	/*
255 	 * Point d at bp, and add d to the interface's list of listeners.
256 	 * Finally, point the driver's bpf cookie at the interface so
257 	 * it will divert packets to bpf.
258 	 */
259 	d->bd_bif = bp;
260 	SLIST_INSERT_HEAD(&bp->bif_dlist, d, bd_next);
261 	*bp->bif_driverp = bp;
262 }
263 
264 /*
265  * Detach a file from its interface.
266  */
267 static void
268 bpf_detachd(struct bpf_d *d)
269 {
270 	int error;
271 	struct bpf_if *bp;
272 	struct ifnet *ifp;
273 
274 	bp = d->bd_bif;
275 	ifp = bp->bif_ifp;
276 
277 	/* Remove d from the interface's descriptor list. */
278 	SLIST_REMOVE(&bp->bif_dlist, d, bpf_d, bd_next);
279 
280 	if (SLIST_EMPTY(&bp->bif_dlist)) {
281 		/*
282 		 * Let the driver know that there are no more listeners.
283 		 */
284 		*bp->bif_driverp = NULL;
285 	}
286 	d->bd_bif = NULL;
287 	/*
288 	 * Check if this descriptor had requested promiscuous mode.
289 	 * If so, turn it off.
290 	 */
291 	if (d->bd_promisc) {
292 		d->bd_promisc = 0;
293 		error = ifpromisc(ifp, 0);
294 		if (error != 0 && error != ENXIO) {
295 			/*
296 			 * ENXIO can happen if a pccard is unplugged,
297 			 * Something is really wrong if we were able to put
298 			 * the driver into promiscuous mode, but can't
299 			 * take it out.
300 			 */
301 			if_printf(ifp, "bpf_detach: ifpromisc failed(%d)\n",
302 				  error);
303 		}
304 	}
305 }
306 
307 /*
308  * Open ethernet device.  Returns ENXIO for illegal minor device number,
309  * EBUSY if file is open by another process.
310  */
311 /* ARGSUSED */
312 static int
313 bpfopen(struct dev_open_args *ap)
314 {
315 	cdev_t dev = ap->a_head.a_dev;
316 	struct bpf_d *d;
317 
318 	if (ap->a_cred->cr_prison)
319 		return(EPERM);
320 
321 	d = dev->si_drv1;
322 	/*
323 	 * Each minor can be opened by only one process.  If the requested
324 	 * minor is in use, return EBUSY.
325 	 */
326 	if (d != NULL)
327 		return(EBUSY);
328 
329 	MALLOC(d, struct bpf_d *, sizeof *d, M_BPF, M_WAITOK | M_ZERO);
330 	dev->si_drv1 = d;
331 	d->bd_bufsize = bpf_bufsize;
332 	d->bd_sig = SIGIO;
333 	d->bd_seesent = 1;
334 	callout_init(&d->bd_callout);
335 	return(0);
336 }
337 
338 static int
339 bpfclone(struct dev_clone_args *ap)
340 {
341 	int unit;
342 
343 	unit = devfs_clone_bitmap_get(&DEVFS_CLONE_BITMAP(bpf), 0);
344 	ap->a_dev = make_only_dev(&bpf_ops, unit, 0, 0, 0600, "bpf%d", unit);
345 
346 	return 0;
347 }
348 
349 /*
350  * Close the descriptor by detaching it from its interface,
351  * deallocating its buffers, and marking it free.
352  */
353 /* ARGSUSED */
354 static int
355 bpfclose(struct dev_close_args *ap)
356 {
357 	cdev_t dev = ap->a_head.a_dev;
358 	struct bpf_d *d = dev->si_drv1;
359 
360 	funsetown(d->bd_sigio);
361 	crit_enter();
362 	if (d->bd_state == BPF_WAITING)
363 		callout_stop(&d->bd_callout);
364 	d->bd_state = BPF_IDLE;
365 	if (d->bd_bif != NULL)
366 		bpf_detachd(d);
367 	crit_exit();
368 	bpf_freed(d);
369 	dev->si_drv1 = NULL;
370 	if (dev->si_uminor >= BPF_PREALLOCATED_UNITS) {
371 		devfs_clone_bitmap_put(&DEVFS_CLONE_BITMAP(bpf), dev->si_uminor);
372 		destroy_dev(dev);
373 	}
374 	kfree(d, M_BPF);
375 	return(0);
376 }
377 
378 /*
379  * Rotate the packet buffers in descriptor d.  Move the store buffer
380  * into the hold slot, and the free buffer into the store slot.
381  * Zero the length of the new store buffer.
382  */
383 #define ROTATE_BUFFERS(d) \
384 	(d)->bd_hbuf = (d)->bd_sbuf; \
385 	(d)->bd_hlen = (d)->bd_slen; \
386 	(d)->bd_sbuf = (d)->bd_fbuf; \
387 	(d)->bd_slen = 0; \
388 	(d)->bd_fbuf = NULL;
389 /*
390  *  bpfread - read next chunk of packets from buffers
391  */
392 static int
393 bpfread(struct dev_read_args *ap)
394 {
395 	cdev_t dev = ap->a_head.a_dev;
396 	struct bpf_d *d = dev->si_drv1;
397 	int timed_out;
398 	int error;
399 
400 	/*
401 	 * Restrict application to use a buffer the same size as
402 	 * as kernel buffers.
403 	 */
404 	if (ap->a_uio->uio_resid != d->bd_bufsize)
405 		return(EINVAL);
406 
407 	crit_enter();
408 	if (d->bd_state == BPF_WAITING)
409 		callout_stop(&d->bd_callout);
410 	timed_out = (d->bd_state == BPF_TIMED_OUT);
411 	d->bd_state = BPF_IDLE;
412 	/*
413 	 * If the hold buffer is empty, then do a timed sleep, which
414 	 * ends when the timeout expires or when enough packets
415 	 * have arrived to fill the store buffer.
416 	 */
417 	while (d->bd_hbuf == NULL) {
418 		if ((d->bd_immediate || timed_out) && d->bd_slen != 0) {
419 			/*
420 			 * A packet(s) either arrived since the previous
421 			 * read or arrived while we were asleep.
422 			 * Rotate the buffers and return what's here.
423 			 */
424 			ROTATE_BUFFERS(d);
425 			break;
426 		}
427 
428 		/*
429 		 * No data is available, check to see if the bpf device
430 		 * is still pointed at a real interface.  If not, return
431 		 * ENXIO so that the userland process knows to rebind
432 		 * it before using it again.
433 		 */
434 		if (d->bd_bif == NULL) {
435 			crit_exit();
436 			return(ENXIO);
437 		}
438 
439 		if (ap->a_ioflag & IO_NDELAY) {
440 			crit_exit();
441 			return(EWOULDBLOCK);
442 		}
443 		error = tsleep(d, PCATCH, "bpf", d->bd_rtout);
444 		if (error == EINTR || error == ERESTART) {
445 			crit_exit();
446 			return(error);
447 		}
448 		if (error == EWOULDBLOCK) {
449 			/*
450 			 * On a timeout, return what's in the buffer,
451 			 * which may be nothing.  If there is something
452 			 * in the store buffer, we can rotate the buffers.
453 			 */
454 			if (d->bd_hbuf)
455 				/*
456 				 * We filled up the buffer in between
457 				 * getting the timeout and arriving
458 				 * here, so we don't need to rotate.
459 				 */
460 				break;
461 
462 			if (d->bd_slen == 0) {
463 				crit_exit();
464 				return(0);
465 			}
466 			ROTATE_BUFFERS(d);
467 			break;
468 		}
469 	}
470 	/*
471 	 * At this point, we know we have something in the hold slot.
472 	 */
473 	crit_exit();
474 
475 	/*
476 	 * Move data from hold buffer into user space.
477 	 * We know the entire buffer is transferred since
478 	 * we checked above that the read buffer is bpf_bufsize bytes.
479 	 */
480 	error = uiomove(d->bd_hbuf, d->bd_hlen, ap->a_uio);
481 
482 	crit_enter();
483 	d->bd_fbuf = d->bd_hbuf;
484 	d->bd_hbuf = NULL;
485 	d->bd_hlen = 0;
486 	crit_exit();
487 
488 	return(error);
489 }
490 
491 
492 /*
493  * If there are processes sleeping on this descriptor, wake them up.
494  */
495 static void
496 bpf_wakeup(struct bpf_d *d)
497 {
498 	if (d->bd_state == BPF_WAITING) {
499 		callout_stop(&d->bd_callout);
500 		d->bd_state = BPF_IDLE;
501 	}
502 	wakeup(d);
503 	if (d->bd_async && d->bd_sig && d->bd_sigio)
504 		pgsigio(d->bd_sigio, d->bd_sig, 0);
505 
506 	get_mplock();
507 	selwakeup(&d->bd_sel);
508 	rel_mplock();
509 	/* XXX */
510 	d->bd_sel.si_pid = 0;
511 }
512 
513 static void
514 bpf_timed_out(void *arg)
515 {
516 	struct bpf_d *d = (struct bpf_d *)arg;
517 
518 	crit_enter();
519 	if (d->bd_state == BPF_WAITING) {
520 		d->bd_state = BPF_TIMED_OUT;
521 		if (d->bd_slen != 0)
522 			bpf_wakeup(d);
523 	}
524 	crit_exit();
525 }
526 
527 static void
528 bpf_output_dispatch(struct netmsg *nmsg)
529 {
530 	struct netmsg_bpf_output *bmsg = (struct netmsg_bpf_output *)nmsg;
531 	struct ifnet *ifp = bmsg->nm_ifp;
532 	int error;
533 
534 	/*
535 	 * The driver frees the mbuf.
536 	 */
537 	error = ifp->if_output(ifp, bmsg->nm_mbuf, bmsg->nm_dst, NULL);
538 	lwkt_replymsg(&nmsg->nm_lmsg, error);
539 }
540 
541 static int
542 bpfwrite(struct dev_write_args *ap)
543 {
544 	cdev_t dev = ap->a_head.a_dev;
545 	struct bpf_d *d = dev->si_drv1;
546 	struct ifnet *ifp;
547 	struct mbuf *m;
548 	int error;
549 	struct sockaddr dst;
550 	int datlen;
551 	struct netmsg_bpf_output bmsg;
552 
553 	if (d->bd_bif == NULL)
554 		return(ENXIO);
555 
556 	ifp = d->bd_bif->bif_ifp;
557 
558 	if (ap->a_uio->uio_resid == 0)
559 		return(0);
560 
561 	error = bpf_movein(ap->a_uio, (int)d->bd_bif->bif_dlt, &m,
562 			   &dst, &datlen, d->bd_wfilter);
563 	if (error)
564 		return(error);
565 
566 	if (datlen > ifp->if_mtu) {
567 		m_freem(m);
568 		return(EMSGSIZE);
569 	}
570 
571 	if (d->bd_hdrcmplt)
572 		dst.sa_family = pseudo_AF_HDRCMPLT;
573 
574 	netmsg_init(&bmsg.nm_netmsg, &curthread->td_msgport, MSGF_MPSAFE,
575 		    bpf_output_dispatch);
576 	bmsg.nm_mbuf = m;
577 	bmsg.nm_ifp = ifp;
578 	bmsg.nm_dst = &dst;
579 
580 	return lwkt_domsg(cpu_portfn(0), &bmsg.nm_netmsg.nm_lmsg, 0);
581 }
582 
583 /*
584  * Reset a descriptor by flushing its packet buffer and clearing the
585  * receive and drop counts.  Should be called at splimp.
586  */
587 static void
588 bpf_resetd(struct bpf_d *d)
589 {
590 	if (d->bd_hbuf) {
591 		/* Free the hold buffer. */
592 		d->bd_fbuf = d->bd_hbuf;
593 		d->bd_hbuf = NULL;
594 	}
595 	d->bd_slen = 0;
596 	d->bd_hlen = 0;
597 	d->bd_rcount = 0;
598 	d->bd_dcount = 0;
599 }
600 
601 /*
602  *  FIONREAD		Check for read packet available.
603  *  SIOCGIFADDR		Get interface address - convenient hook to driver.
604  *  BIOCGBLEN		Get buffer len [for read()].
605  *  BIOCSETF		Set ethernet read filter.
606  *  BIOCSETWF		Set ethernet write filter.
607  *  BIOCFLUSH		Flush read packet buffer.
608  *  BIOCPROMISC		Put interface into promiscuous mode.
609  *  BIOCGDLT		Get link layer type.
610  *  BIOCGETIF		Get interface name.
611  *  BIOCSETIF		Set interface.
612  *  BIOCSRTIMEOUT	Set read timeout.
613  *  BIOCGRTIMEOUT	Get read timeout.
614  *  BIOCGSTATS		Get packet stats.
615  *  BIOCIMMEDIATE	Set immediate mode.
616  *  BIOCVERSION		Get filter language version.
617  *  BIOCGHDRCMPLT	Get "header already complete" flag
618  *  BIOCSHDRCMPLT	Set "header already complete" flag
619  *  BIOCGSEESENT	Get "see packets sent" flag
620  *  BIOCSSEESENT	Set "see packets sent" flag
621  *  BIOCLOCK		Set "locked" flag
622  */
623 /* ARGSUSED */
624 static int
625 bpfioctl(struct dev_ioctl_args *ap)
626 {
627 	cdev_t dev = ap->a_head.a_dev;
628 	struct bpf_d *d = dev->si_drv1;
629 	int error = 0;
630 
631 	crit_enter();
632 	if (d->bd_state == BPF_WAITING)
633 		callout_stop(&d->bd_callout);
634 	d->bd_state = BPF_IDLE;
635 	crit_exit();
636 
637 	if (d->bd_locked == 1) {
638 		switch (ap->a_cmd) {
639 		case BIOCGBLEN:
640 		case BIOCFLUSH:
641 		case BIOCGDLT:
642 		case BIOCGDLTLIST:
643 		case BIOCGETIF:
644 		case BIOCGRTIMEOUT:
645 		case BIOCGSTATS:
646 		case BIOCVERSION:
647 		case BIOCGRSIG:
648 		case BIOCGHDRCMPLT:
649 		case FIONREAD:
650 		case BIOCLOCK:
651 		case BIOCSRTIMEOUT:
652 		case BIOCIMMEDIATE:
653 		case TIOCGPGRP:
654 			break;
655 		default:
656 			return (EPERM);
657 		}
658 	}
659 	switch (ap->a_cmd) {
660 	default:
661 		error = EINVAL;
662 		break;
663 
664 	/*
665 	 * Check for read packet available.
666 	 */
667 	case FIONREAD:
668 		{
669 			int n;
670 
671 			crit_enter();
672 			n = d->bd_slen;
673 			if (d->bd_hbuf)
674 				n += d->bd_hlen;
675 			crit_exit();
676 
677 			*(int *)ap->a_data = n;
678 			break;
679 		}
680 
681 	case SIOCGIFADDR:
682 		{
683 			struct ifnet *ifp;
684 
685 			if (d->bd_bif == NULL) {
686 				error = EINVAL;
687 			} else {
688 				ifp = d->bd_bif->bif_ifp;
689 				ifnet_serialize_all(ifp);
690 				error = ifp->if_ioctl(ifp, ap->a_cmd,
691 						      ap->a_data, ap->a_cred);
692 				ifnet_deserialize_all(ifp);
693 			}
694 			break;
695 		}
696 
697 	/*
698 	 * Get buffer len [for read()].
699 	 */
700 	case BIOCGBLEN:
701 		*(u_int *)ap->a_data = d->bd_bufsize;
702 		break;
703 
704 	/*
705 	 * Set buffer length.
706 	 */
707 	case BIOCSBLEN:
708 		if (d->bd_bif != NULL) {
709 			error = EINVAL;
710 		} else {
711 			u_int size = *(u_int *)ap->a_data;
712 
713 			if (size > bpf_maxbufsize)
714 				*(u_int *)ap->a_data = size = bpf_maxbufsize;
715 			else if (size < BPF_MINBUFSIZE)
716 				*(u_int *)ap->a_data = size = BPF_MINBUFSIZE;
717 			d->bd_bufsize = size;
718 		}
719 		break;
720 
721 	/*
722 	 * Set link layer read filter.
723 	 */
724 	case BIOCSETF:
725 	case BIOCSETWF:
726 		error = bpf_setf(d, (struct bpf_program *)ap->a_data,
727 			ap->a_cmd);
728 		break;
729 
730 	/*
731 	 * Flush read packet buffer.
732 	 */
733 	case BIOCFLUSH:
734 		crit_enter();
735 		bpf_resetd(d);
736 		crit_exit();
737 		break;
738 
739 	/*
740 	 * Put interface into promiscuous mode.
741 	 */
742 	case BIOCPROMISC:
743 		if (d->bd_bif == NULL) {
744 			/*
745 			 * No interface attached yet.
746 			 */
747 			error = EINVAL;
748 			break;
749 		}
750 		crit_enter();
751 		if (d->bd_promisc == 0) {
752 			error = ifpromisc(d->bd_bif->bif_ifp, 1);
753 			if (error == 0)
754 				d->bd_promisc = 1;
755 		}
756 		crit_exit();
757 		break;
758 
759 	/*
760 	 * Get device parameters.
761 	 */
762 	case BIOCGDLT:
763 		if (d->bd_bif == NULL)
764 			error = EINVAL;
765 		else
766 			*(u_int *)ap->a_data = d->bd_bif->bif_dlt;
767 		break;
768 
769 	/*
770 	 * Get a list of supported data link types.
771 	 */
772 	case BIOCGDLTLIST:
773 		if (d->bd_bif == NULL) {
774 			error = EINVAL;
775 		} else {
776 			error = bpf_getdltlist(d,
777 				(struct bpf_dltlist *)ap->a_data);
778 		}
779 		break;
780 
781 	/*
782 	 * Set data link type.
783 	 */
784 	case BIOCSDLT:
785 		if (d->bd_bif == NULL)
786 			error = EINVAL;
787 		else
788 			error = bpf_setdlt(d, *(u_int *)ap->a_data);
789 		break;
790 
791 	/*
792 	 * Get interface name.
793 	 */
794 	case BIOCGETIF:
795 		if (d->bd_bif == NULL) {
796 			error = EINVAL;
797 		} else {
798 			struct ifnet *const ifp = d->bd_bif->bif_ifp;
799 			struct ifreq *const ifr = (struct ifreq *)ap->a_data;
800 
801 			strlcpy(ifr->ifr_name, ifp->if_xname,
802 				sizeof ifr->ifr_name);
803 		}
804 		break;
805 
806 	/*
807 	 * Set interface.
808 	 */
809 	case BIOCSETIF:
810 		error = bpf_setif(d, (struct ifreq *)ap->a_data);
811 		break;
812 
813 	/*
814 	 * Set read timeout.
815 	 */
816 	case BIOCSRTIMEOUT:
817 		{
818 			struct timeval *tv = (struct timeval *)ap->a_data;
819 
820 			/*
821 			 * Subtract 1 tick from tvtohz() since this isn't
822 			 * a one-shot timer.
823 			 */
824 			if ((error = itimerfix(tv)) == 0)
825 				d->bd_rtout = tvtohz_low(tv);
826 			break;
827 		}
828 
829 	/*
830 	 * Get read timeout.
831 	 */
832 	case BIOCGRTIMEOUT:
833 		{
834 			struct timeval *tv = (struct timeval *)ap->a_data;
835 
836 			tv->tv_sec = d->bd_rtout / hz;
837 			tv->tv_usec = (d->bd_rtout % hz) * tick;
838 			break;
839 		}
840 
841 	/*
842 	 * Get packet stats.
843 	 */
844 	case BIOCGSTATS:
845 		{
846 			struct bpf_stat *bs = (struct bpf_stat *)ap->a_data;
847 
848 			bs->bs_recv = d->bd_rcount;
849 			bs->bs_drop = d->bd_dcount;
850 			break;
851 		}
852 
853 	/*
854 	 * Set immediate mode.
855 	 */
856 	case BIOCIMMEDIATE:
857 		d->bd_immediate = *(u_int *)ap->a_data;
858 		break;
859 
860 	case BIOCVERSION:
861 		{
862 			struct bpf_version *bv = (struct bpf_version *)ap->a_data;
863 
864 			bv->bv_major = BPF_MAJOR_VERSION;
865 			bv->bv_minor = BPF_MINOR_VERSION;
866 			break;
867 		}
868 
869 	/*
870 	 * Get "header already complete" flag
871 	 */
872 	case BIOCGHDRCMPLT:
873 		*(u_int *)ap->a_data = d->bd_hdrcmplt;
874 		break;
875 
876 	/*
877 	 * Set "header already complete" flag
878 	 */
879 	case BIOCSHDRCMPLT:
880 		d->bd_hdrcmplt = *(u_int *)ap->a_data ? 1 : 0;
881 		break;
882 
883 	/*
884 	 * Get "see sent packets" flag
885 	 */
886 	case BIOCGSEESENT:
887 		*(u_int *)ap->a_data = d->bd_seesent;
888 		break;
889 
890 	/*
891 	 * Set "see sent packets" flag
892 	 */
893 	case BIOCSSEESENT:
894 		d->bd_seesent = *(u_int *)ap->a_data;
895 		break;
896 
897 	case FIOASYNC:		/* Send signal on receive packets */
898 		d->bd_async = *(int *)ap->a_data;
899 		break;
900 
901 	case FIOSETOWN:
902 		error = fsetown(*(int *)ap->a_data, &d->bd_sigio);
903 		break;
904 
905 	case FIOGETOWN:
906 		*(int *)ap->a_data = fgetown(d->bd_sigio);
907 		break;
908 
909 	/* This is deprecated, FIOSETOWN should be used instead. */
910 	case TIOCSPGRP:
911 		error = fsetown(-(*(int *)ap->a_data), &d->bd_sigio);
912 		break;
913 
914 	/* This is deprecated, FIOGETOWN should be used instead. */
915 	case TIOCGPGRP:
916 		*(int *)ap->a_data = -fgetown(d->bd_sigio);
917 		break;
918 
919 	case BIOCSRSIG:		/* Set receive signal */
920 		{
921 			u_int sig;
922 
923 			sig = *(u_int *)ap->a_data;
924 
925 			if (sig >= NSIG)
926 				error = EINVAL;
927 			else
928 				d->bd_sig = sig;
929 			break;
930 		}
931 	case BIOCGRSIG:
932 		*(u_int *)ap->a_data = d->bd_sig;
933 		break;
934 	case BIOCLOCK:
935 		d->bd_locked = 1;
936 		break;
937 	}
938 	return(error);
939 }
940 
941 /*
942  * Set d's packet filter program to fp.  If this file already has a filter,
943  * free it and replace it.  Returns EINVAL for bogus requests.
944  */
945 static int
946 bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
947 {
948 	struct bpf_insn *fcode, *old;
949 	u_int wfilter, flen, size;
950 
951 	if (cmd == BIOCSETWF) {
952 		old = d->bd_wfilter;
953 		wfilter = 1;
954 	} else {
955 		wfilter = 0;
956 		old = d->bd_rfilter;
957 	}
958 	if (fp->bf_insns == NULL) {
959 		if (fp->bf_len != 0)
960 			return(EINVAL);
961 		crit_enter();
962 		if (wfilter)
963 			d->bd_wfilter = NULL;
964 		else
965 			d->bd_rfilter = NULL;
966 		bpf_resetd(d);
967 		crit_exit();
968 		if (old != NULL)
969 			kfree(old, M_BPF);
970 		return(0);
971 	}
972 	flen = fp->bf_len;
973 	if (flen > BPF_MAXINSNS)
974 		return(EINVAL);
975 
976 	size = flen * sizeof *fp->bf_insns;
977 	fcode = (struct bpf_insn *)kmalloc(size, M_BPF, M_WAITOK);
978 	if (copyin(fp->bf_insns, fcode, size) == 0 &&
979 	    bpf_validate(fcode, (int)flen)) {
980 		crit_enter();
981 		if (wfilter)
982 			d->bd_wfilter = fcode;
983 		else
984 			d->bd_rfilter = fcode;
985 		bpf_resetd(d);
986 		crit_exit();
987 		if (old != NULL)
988 			kfree(old, M_BPF);
989 
990 		return(0);
991 	}
992 	kfree(fcode, M_BPF);
993 	return(EINVAL);
994 }
995 
996 /*
997  * Detach a file from its current interface (if attached at all) and attach
998  * to the interface indicated by the name stored in ifr.
999  * Return an errno or 0.
1000  */
1001 static int
1002 bpf_setif(struct bpf_d *d, struct ifreq *ifr)
1003 {
1004 	struct bpf_if *bp;
1005 	int error;
1006 	struct ifnet *theywant;
1007 
1008 	theywant = ifunit(ifr->ifr_name);
1009 	if (theywant == NULL)
1010 		return(ENXIO);
1011 
1012 	/*
1013 	 * Look through attached interfaces for the named one.
1014 	 */
1015 	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
1016 		struct ifnet *ifp = bp->bif_ifp;
1017 
1018 		if (ifp == NULL || ifp != theywant)
1019 			continue;
1020 		/* skip additional entry */
1021 		if (bp->bif_driverp != &ifp->if_bpf)
1022 			continue;
1023 		/*
1024 		 * We found the requested interface.
1025 		 * If it's not up, return an error.
1026 		 * Allocate the packet buffers if we need to.
1027 		 * If we're already attached to requested interface,
1028 		 * just flush the buffer.
1029 		 */
1030 		if (!(ifp->if_flags & IFF_UP))
1031 			return(ENETDOWN);
1032 
1033 		if (d->bd_sbuf == NULL) {
1034 			error = bpf_allocbufs(d);
1035 			if (error != 0)
1036 				return(error);
1037 		}
1038 		crit_enter();
1039 		if (bp != d->bd_bif) {
1040 			if (d->bd_bif != NULL) {
1041 				/*
1042 				 * Detach if attached to something else.
1043 				 */
1044 				bpf_detachd(d);
1045 			}
1046 
1047 			bpf_attachd(d, bp);
1048 		}
1049 		bpf_resetd(d);
1050 		crit_exit();
1051 		return(0);
1052 	}
1053 
1054 	/* Not found. */
1055 	return(ENXIO);
1056 }
1057 
1058 /*
1059  * Support for select() and poll() system calls
1060  *
1061  * Return true iff the specific operation will not block indefinitely.
1062  * Otherwise, return false but make a note that a selwakeup() must be done.
1063  */
1064 static int
1065 bpfpoll(struct dev_poll_args *ap)
1066 {
1067 	cdev_t dev = ap->a_head.a_dev;
1068 	struct bpf_d *d;
1069 	int revents;
1070 
1071 	d = dev->si_drv1;
1072 	if (d->bd_bif == NULL)
1073 		return(ENXIO);
1074 
1075 	revents = ap->a_events & (POLLOUT | POLLWRNORM);
1076 	crit_enter();
1077 	if (ap->a_events & (POLLIN | POLLRDNORM)) {
1078 		/*
1079 		 * An imitation of the FIONREAD ioctl code.
1080 		 * XXX not quite.  An exact imitation:
1081 		 *	if (d->b_slen != 0 ||
1082 		 *	    (d->bd_hbuf != NULL && d->bd_hlen != 0)
1083 		 */
1084 		if (d->bd_hlen != 0 ||
1085 		    ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
1086 		    d->bd_slen != 0)) {
1087 			revents |= ap->a_events & (POLLIN | POLLRDNORM);
1088 		} else {
1089 			selrecord(curthread, &d->bd_sel);
1090 			/* Start the read timeout if necessary. */
1091 			if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
1092 				callout_reset(&d->bd_callout, d->bd_rtout,
1093 				    bpf_timed_out, d);
1094 				d->bd_state = BPF_WAITING;
1095 			}
1096 		}
1097 	}
1098 	crit_exit();
1099 	ap->a_events = revents;
1100 	return(0);
1101 }
1102 
1103 /*
1104  * Process the packet pkt of length pktlen.  The packet is parsed
1105  * by each listener's filter, and if accepted, stashed into the
1106  * corresponding buffer.
1107  */
1108 void
1109 bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
1110 {
1111 	struct bpf_d *d;
1112 	struct timeval tv;
1113 	int gottime = 0;
1114 	u_int slen;
1115 
1116 	get_mplock();
1117 
1118 	/* Re-check */
1119 	if (bp == NULL) {
1120 		rel_mplock();
1121 		return;
1122 	}
1123 
1124 	/*
1125 	 * Note that the ipl does not have to be raised at this point.
1126 	 * The only problem that could arise here is that if two different
1127 	 * interfaces shared any data.  This is not the case.
1128 	 */
1129 	SLIST_FOREACH(d, &bp->bif_dlist, bd_next) {
1130 		++d->bd_rcount;
1131 		slen = bpf_filter(d->bd_rfilter, pkt, pktlen, pktlen);
1132 		if (slen != 0) {
1133 			if (!gottime) {
1134 				microtime(&tv);
1135 				gottime = 1;
1136 			}
1137 			catchpacket(d, pkt, pktlen, slen, ovbcopy, &tv);
1138 		}
1139 	}
1140 
1141 	rel_mplock();
1142 }
1143 
1144 /*
1145  * Copy data from an mbuf chain into a buffer.  This code is derived
1146  * from m_copydata in sys/uipc_mbuf.c.
1147  */
1148 static void
1149 bpf_mcopy(const void *src_arg, void *dst_arg, size_t len)
1150 {
1151 	const struct mbuf *m;
1152 	u_int count;
1153 	u_char *dst;
1154 
1155 	m = src_arg;
1156 	dst = dst_arg;
1157 	while (len > 0) {
1158 		if (m == NULL)
1159 			panic("bpf_mcopy");
1160 		count = min(m->m_len, len);
1161 		bcopy(mtod(m, void *), dst, count);
1162 		m = m->m_next;
1163 		dst += count;
1164 		len -= count;
1165 	}
1166 }
1167 
1168 /*
1169  * Process the packet in the mbuf chain m.  The packet is parsed by each
1170  * listener's filter, and if accepted, stashed into the corresponding
1171  * buffer.
1172  */
1173 void
1174 bpf_mtap(struct bpf_if *bp, struct mbuf *m)
1175 {
1176 	struct bpf_d *d;
1177 	u_int pktlen, slen;
1178 	struct timeval tv;
1179 	int gottime = 0;
1180 
1181 	get_mplock();
1182 
1183 	/* Re-check */
1184 	if (bp == NULL) {
1185 		rel_mplock();
1186 		return;
1187 	}
1188 
1189 	/* Don't compute pktlen, if no descriptor is attached. */
1190 	if (SLIST_EMPTY(&bp->bif_dlist)) {
1191 		rel_mplock();
1192 		return;
1193 	}
1194 
1195 	pktlen = m_lengthm(m, NULL);
1196 
1197 	SLIST_FOREACH(d, &bp->bif_dlist, bd_next) {
1198 		if (!d->bd_seesent && (m->m_pkthdr.rcvif == NULL))
1199 			continue;
1200 		++d->bd_rcount;
1201 		slen = bpf_filter(d->bd_rfilter, (u_char *)m, pktlen, 0);
1202 		if (slen != 0) {
1203 			if (!gottime) {
1204 				microtime(&tv);
1205 				gottime = 1;
1206 			}
1207 			catchpacket(d, (u_char *)m, pktlen, slen, bpf_mcopy,
1208 				    &tv);
1209 		}
1210 	}
1211 
1212 	rel_mplock();
1213 }
1214 
1215 void
1216 bpf_mtap_family(struct bpf_if *bp, struct mbuf *m, sa_family_t family)
1217 {
1218 	u_int family4;
1219 
1220 	KKASSERT(family != AF_UNSPEC);
1221 
1222 	family4 = (u_int)family;
1223 	bpf_ptap(bp, m, &family4, sizeof(family4));
1224 }
1225 
1226 /*
1227  * Process the packet in the mbuf chain m with the header in m prepended.
1228  * The packet is parsed by each listener's filter, and if accepted,
1229  * stashed into the corresponding buffer.
1230  */
1231 void
1232 bpf_ptap(struct bpf_if *bp, struct mbuf *m, const void *data, u_int dlen)
1233 {
1234 	struct mbuf mb;
1235 
1236 	/*
1237 	 * Craft on-stack mbuf suitable for passing to bpf_mtap.
1238 	 * Note that we cut corners here; we only setup what's
1239 	 * absolutely needed--this mbuf should never go anywhere else.
1240 	 */
1241 	mb.m_next = m;
1242 	mb.m_data = __DECONST(void *, data); /* LINTED */
1243 	mb.m_len = dlen;
1244 	mb.m_pkthdr.rcvif = m->m_pkthdr.rcvif;
1245 
1246 	bpf_mtap(bp, &mb);
1247 }
1248 
1249 /*
1250  * Move the packet data from interface memory (pkt) into the
1251  * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
1252  * otherwise 0.  "copy" is the routine called to do the actual data
1253  * transfer.  bcopy is passed in to copy contiguous chunks, while
1254  * bpf_mcopy is passed in to copy mbuf chains.  In the latter case,
1255  * pkt is really an mbuf.
1256  */
1257 static void
1258 catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
1259 	    void (*cpfn)(const void *, void *, size_t),
1260 	    const struct timeval *tv)
1261 {
1262 	struct bpf_hdr *hp;
1263 	int totlen, curlen;
1264 	int hdrlen = d->bd_bif->bif_hdrlen;
1265 	/*
1266 	 * Figure out how many bytes to move.  If the packet is
1267 	 * greater or equal to the snapshot length, transfer that
1268 	 * much.  Otherwise, transfer the whole packet (unless
1269 	 * we hit the buffer size limit).
1270 	 */
1271 	totlen = hdrlen + min(snaplen, pktlen);
1272 	if (totlen > d->bd_bufsize)
1273 		totlen = d->bd_bufsize;
1274 
1275 	/*
1276 	 * Round up the end of the previous packet to the next longword.
1277 	 */
1278 	curlen = BPF_WORDALIGN(d->bd_slen);
1279 	if (curlen + totlen > d->bd_bufsize) {
1280 		/*
1281 		 * This packet will overflow the storage buffer.
1282 		 * Rotate the buffers if we can, then wakeup any
1283 		 * pending reads.
1284 		 */
1285 		if (d->bd_fbuf == NULL) {
1286 			/*
1287 			 * We haven't completed the previous read yet,
1288 			 * so drop the packet.
1289 			 */
1290 			++d->bd_dcount;
1291 			return;
1292 		}
1293 		ROTATE_BUFFERS(d);
1294 		bpf_wakeup(d);
1295 		curlen = 0;
1296 	} else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT) {
1297 		/*
1298 		 * Immediate mode is set, or the read timeout has
1299 		 * already expired during a select call.  A packet
1300 		 * arrived, so the reader should be woken up.
1301 		 */
1302 		bpf_wakeup(d);
1303 	}
1304 
1305 	/*
1306 	 * Append the bpf header.
1307 	 */
1308 	hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
1309 	hp->bh_tstamp = *tv;
1310 	hp->bh_datalen = pktlen;
1311 	hp->bh_hdrlen = hdrlen;
1312 	/*
1313 	 * Copy the packet data into the store buffer and update its length.
1314 	 */
1315 	(*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = totlen - hdrlen));
1316 	d->bd_slen = curlen + totlen;
1317 }
1318 
1319 /*
1320  * Initialize all nonzero fields of a descriptor.
1321  */
1322 static int
1323 bpf_allocbufs(struct bpf_d *d)
1324 {
1325 	d->bd_fbuf = kmalloc(d->bd_bufsize, M_BPF, M_WAITOK);
1326 	d->bd_sbuf = kmalloc(d->bd_bufsize, M_BPF, M_WAITOK);
1327 	d->bd_slen = 0;
1328 	d->bd_hlen = 0;
1329 	return(0);
1330 }
1331 
1332 /*
1333  * Free buffers and packet filter program currently in use by a descriptor.
1334  * Called on close.
1335  */
1336 static void
1337 bpf_freed(struct bpf_d *d)
1338 {
1339 	/*
1340 	 * We don't need to lock out interrupts since this descriptor has
1341 	 * been detached from its interface and it yet hasn't been marked
1342 	 * free.
1343 	 */
1344 	if (d->bd_sbuf != NULL) {
1345 		kfree(d->bd_sbuf, M_BPF);
1346 		if (d->bd_hbuf != NULL)
1347 			kfree(d->bd_hbuf, M_BPF);
1348 		if (d->bd_fbuf != NULL)
1349 			kfree(d->bd_fbuf, M_BPF);
1350 	}
1351 	if (d->bd_rfilter)
1352 		kfree(d->bd_rfilter, M_BPF);
1353 	if (d->bd_wfilter)
1354 		kfree(d->bd_wfilter, M_BPF);
1355 }
1356 
1357 /*
1358  * Attach an interface to bpf.  ifp is a pointer to the structure
1359  * defining the interface to be attached, dlt is the link layer type,
1360  * and hdrlen is the fixed size of the link header (variable length
1361  * headers are not yet supported).
1362  */
1363 void
1364 bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
1365 {
1366 	bpfattach_dlt(ifp, dlt, hdrlen, &ifp->if_bpf);
1367 }
1368 
1369 void
1370 bpfattach_dlt(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
1371 {
1372 	struct bpf_if *bp;
1373 
1374 	bp = kmalloc(sizeof *bp, M_BPF, M_WAITOK | M_ZERO);
1375 
1376 	SLIST_INIT(&bp->bif_dlist);
1377 	bp->bif_ifp = ifp;
1378 	bp->bif_dlt = dlt;
1379 	bp->bif_driverp = driverp;
1380 	*bp->bif_driverp = NULL;
1381 
1382 	bp->bif_next = bpf_iflist;
1383 	bpf_iflist = bp;
1384 
1385 	/*
1386 	 * Compute the length of the bpf header.  This is not necessarily
1387 	 * equal to SIZEOF_BPF_HDR because we want to insert spacing such
1388 	 * that the network layer header begins on a longword boundary (for
1389 	 * performance reasons and to alleviate alignment restrictions).
1390 	 */
1391 	bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;
1392 
1393 	if (bootverbose)
1394 		if_printf(ifp, "bpf attached\n");
1395 }
1396 
1397 /*
1398  * Detach bpf from an interface.  This involves detaching each descriptor
1399  * associated with the interface, and leaving bd_bif NULL.  Notify each
1400  * descriptor as it's detached so that any sleepers wake up and get
1401  * ENXIO.
1402  */
1403 void
1404 bpfdetach(struct ifnet *ifp)
1405 {
1406 	struct bpf_if *bp, *bp_prev;
1407 	struct bpf_d *d;
1408 
1409 	crit_enter();
1410 
1411 	/* Locate BPF interface information */
1412 	bp_prev = NULL;
1413 	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
1414 		if (ifp == bp->bif_ifp)
1415 			break;
1416 		bp_prev = bp;
1417 	}
1418 
1419 	/* Interface wasn't attached */
1420 	if (bp->bif_ifp == NULL) {
1421 		crit_exit();
1422 		kprintf("bpfdetach: %s was not attached\n", ifp->if_xname);
1423 		return;
1424 	}
1425 
1426 	while ((d = SLIST_FIRST(&bp->bif_dlist)) != NULL) {
1427 		bpf_detachd(d);
1428 		bpf_wakeup(d);
1429 	}
1430 
1431 	if (bp_prev != NULL)
1432 		bp_prev->bif_next = bp->bif_next;
1433 	else
1434 		bpf_iflist = bp->bif_next;
1435 
1436 	kfree(bp, M_BPF);
1437 
1438 	crit_exit();
1439 }
1440 
1441 /*
1442  * Get a list of available data link type of the interface.
1443  */
1444 static int
1445 bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl)
1446 {
1447 	int n, error;
1448 	struct ifnet *ifp;
1449 	struct bpf_if *bp;
1450 
1451 	ifp = d->bd_bif->bif_ifp;
1452 	n = 0;
1453 	error = 0;
1454 	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
1455 		if (bp->bif_ifp != ifp)
1456 			continue;
1457 		if (bfl->bfl_list != NULL) {
1458 			if (n >= bfl->bfl_len) {
1459 				return (ENOMEM);
1460 			}
1461 			error = copyout(&bp->bif_dlt,
1462 			    bfl->bfl_list + n, sizeof(u_int));
1463 		}
1464 		n++;
1465 	}
1466 	bfl->bfl_len = n;
1467 	return(error);
1468 }
1469 
1470 /*
1471  * Set the data link type of a BPF instance.
1472  */
1473 static int
1474 bpf_setdlt(struct bpf_d *d, u_int dlt)
1475 {
1476 	int error, opromisc;
1477 	struct ifnet *ifp;
1478 	struct bpf_if *bp;
1479 
1480 	if (d->bd_bif->bif_dlt == dlt)
1481 		return (0);
1482 	ifp = d->bd_bif->bif_ifp;
1483 	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
1484 		if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
1485 			break;
1486 	}
1487 	if (bp != NULL) {
1488 		opromisc = d->bd_promisc;
1489 		crit_enter();
1490 		bpf_detachd(d);
1491 		bpf_attachd(d, bp);
1492 		bpf_resetd(d);
1493 		if (opromisc) {
1494 			error = ifpromisc(bp->bif_ifp, 1);
1495 			if (error) {
1496 				if_printf(bp->bif_ifp,
1497 					"bpf_setdlt: ifpromisc failed (%d)\n",
1498 					error);
1499 			} else {
1500 				d->bd_promisc = 1;
1501 			}
1502 		}
1503 		crit_exit();
1504 	}
1505 	return(bp == NULL ? EINVAL : 0);
1506 }
1507 
1508 static void
1509 bpf_drvinit(void *unused)
1510 {
1511 	int i;
1512 
1513 	make_autoclone_dev(&bpf_ops, &DEVFS_CLONE_BITMAP(bpf),
1514 		bpfclone, 0, 0, 0600, "bpf");
1515 	for (i = 0; i < BPF_PREALLOCATED_UNITS; i++) {
1516 		make_dev(&bpf_ops, i, 0, 0, 0600, "bpf%d", i);
1517 		devfs_clone_bitmap_set(&DEVFS_CLONE_BITMAP(bpf), i);
1518 	}
1519 }
1520 
1521 static void
1522 bpf_drvuninit(void *unused)
1523 {
1524 	devfs_clone_handler_del("bpf");
1525 	dev_ops_remove_all(&bpf_ops);
1526 	devfs_clone_bitmap_uninit(&DEVFS_CLONE_BITMAP(bpf));
1527 }
1528 
1529 SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvinit,NULL)
1530 SYSUNINIT(bpfdev, SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvuninit, NULL);
1531 
1532 #else /* !BPF */
1533 /*
1534  * NOP stubs to allow bpf-using drivers to load and function.
1535  *
1536  * A 'better' implementation would allow the core bpf functionality
1537  * to be loaded at runtime.
1538  */
1539 
1540 void
1541 bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
1542 {
1543 }
1544 
1545 void
1546 bpf_mtap(struct bpf_if *bp, struct mbuf *m)
1547 {
1548 }
1549 
1550 void
1551 bpf_ptap(struct bpf_if *bp, struct mbuf *m, const void *data, u_int dlen)
1552 {
1553 }
1554 
1555 void
1556 bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
1557 {
1558 }
1559 
1560 void
1561 bpfattach_dlt(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
1562 {
1563 }
1564 
1565 void
1566 bpfdetach(struct ifnet *ifp)
1567 {
1568 }
1569 
1570 u_int
1571 bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
1572 {
1573 	return -1;	/* "no filter" behaviour */
1574 }
1575 
1576 #endif /* !BPF */
1577