xnu-1486.2.11.tar.gz

[apple/xnu.git] / bsd / net / bpf.c

/*
 * Copyright (c) 2000-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1990, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
 * Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)bpf.c       8.2 (Berkeley) 3/28/94
 *
 * $FreeBSD: src/sys/net/bpf.c,v 1.59.2.5 2001/01/05 04:49:09 jdp Exp $
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include "bpf.h"

#ifndef __GNUC__
#define inline
#else
#define inline __inline
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/filio.h>
#include <sys/sockio.h>
#include <sys/ttycom.h>
#include <sys/filedesc.h>
#include <sys/uio_internal.h>
#include <sys/file_internal.h>
#include <sys/event.h>

#if defined(sparc) && BSD < 199103
#include <sys/stream.h>
#endif
#include <sys/poll.h>

#include <sys/socket.h>
#include <sys/vnode.h>

#include <net/if.h>
#include <net/bpf.h>
#include <net/bpfdesc.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/firewire.h>

#include <miscfs/devfs/devfs.h>
#include <net/dlil.h>

#include <kern/locks.h>

#if CONFIG_MACF_NET
#include <security/mac_framework.h>
#endif /* MAC_NET */

extern int tvtohz(struct timeval *);

/*
 * Older BSDs don't have kernel malloc.
 */
#if BSD < 199103
extern bcopy();
static caddr_t bpf_alloc();
#include <net/bpf_compat.h>
#define BPF_BUFSIZE (MCLBYTES-8)
#define UIOMOVE(cp, len, code, uio) uiomove(cp, len, code, uio)
#else
#define BPF_BUFSIZE 4096
#define UIOMOVE(cp, len, code, uio) uiomove(cp, len, uio)
#endif


#define PRINET  26                      /* interruptible */

/*
 * The default read buffer size is patchable.
 */
static unsigned int bpf_bufsize = BPF_BUFSIZE;
SYSCTL_INT(_debug, OID_AUTO, bpf_bufsize, CTLFLAG_RW, 
        &bpf_bufsize, 0, "");
static unsigned int bpf_maxbufsize = BPF_MAXBUFSIZE;
SYSCTL_INT(_debug, OID_AUTO, bpf_maxbufsize, CTLFLAG_RW, 
        &bpf_maxbufsize, 0, "");
static unsigned int bpf_maxdevices = 256;
SYSCTL_UINT(_debug, OID_AUTO, bpf_maxdevices, CTLFLAG_RW, 
        &bpf_maxdevices, 0, "");

/*
 *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
 *  bpf_dtab holds pointer to the descriptors, indexed by minor device #
 */
static struct bpf_if    *bpf_iflist;
#ifdef __APPLE__
/*
 * BSD now stores the bpf_d in the dev_t which is a struct
 * on their system. Our dev_t is an int, so we still store
 * the bpf_d in a separate table indexed by minor device #.
 *
 * The value stored in bpf_dtab[n] represent three states:
 *  0: device not opened
 *  1: device opening or closing
 *  other: device <n> opened with pointer to storage
 */
static struct bpf_d     **bpf_dtab = NULL;
static unsigned int bpf_dtab_size = 0;
static unsigned int     nbpfilter = 0;

static lck_mtx_t                *bpf_mlock;
static lck_grp_t                *bpf_mlock_grp;
static lck_grp_attr_t   *bpf_mlock_grp_attr;
static lck_attr_t               *bpf_mlock_attr;

/*
 * Mark a descriptor free by making it point to itself.
 * This is probably cheaper than marking with a constant since
 * the address should be in a register anyway.
 */
#endif /* __APPLE__ */

static int      bpf_allocbufs(struct bpf_d *);
static errno_t  bpf_attachd(struct bpf_d *d, struct bpf_if *bp);
static void     bpf_detachd(struct bpf_d *d);
static void     bpf_freed(struct bpf_d *);
static void     bpf_mcopy(const void *, void *, size_t);
static int      bpf_movein(struct uio *, int,
                    struct mbuf **, struct sockaddr *, int *);
static int      bpf_setif(struct bpf_d *, ifnet_t ifp, u_int32_t dlt);
static void bpf_wakeup(struct bpf_d *);
static void     catchpacket(struct bpf_d *, u_char *, u_int,
                    u_int, void (*)(const void *, void *, size_t));
static void     reset_d(struct bpf_d *);
static int bpf_setf(struct bpf_d *, u_int bf_len, user_addr_t bf_insns);
static int      bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *,
    struct proc *);
static int      bpf_setdlt(struct bpf_d *, u_int);

/*static  void *bpf_devfs_token[MAXBPFILTER];*/

static  int bpf_devsw_installed;

void bpf_init(void *unused);
static int bpf_tap_callback(struct ifnet *ifp, struct mbuf *m);

/*
 * Darwin differs from BSD here, the following are static
 * on BSD and not static on Darwin.
 */
        d_open_t        bpfopen;
        d_close_t       bpfclose;
        d_read_t        bpfread;
        d_write_t       bpfwrite;
         ioctl_fcn_t    bpfioctl;
        select_fcn_t    bpfpoll;


/* Darwin's cdevsw struct differs slightly from BSDs */
#define CDEV_MAJOR 23
static struct cdevsw bpf_cdevsw = {
        /* open */      bpfopen,
        /* close */     bpfclose,
        /* read */      bpfread,
        /* write */     bpfwrite,
        /* ioctl */     bpfioctl,
        /* stop */              eno_stop,
        /* reset */             eno_reset,
        /* tty */               NULL,
        /* select */    bpfpoll,
        /* mmap */              eno_mmap,
        /* strategy*/   eno_strat,
        /* getc */              eno_getc,
        /* putc */              eno_putc,
        /* type */              0
};

#define SOCKADDR_HDR_LEN           offsetof(struct sockaddr, sa_data)

static int
bpf_movein(struct uio *uio, int linktype, struct mbuf **mp, struct sockaddr *sockp, int *datlen)
{
        struct mbuf *m;
        int error;
        int len;
        uint8_t sa_family;
        int hlen;

        switch (linktype) {
        
#if SLIP
        case DLT_SLIP:
                sa_family = AF_INET;
                hlen = 0;
                break;
#endif /* SLIP */
        
        case DLT_EN10MB:
                sa_family = AF_UNSPEC;
                /* XXX Would MAXLINKHDR be better? */
                hlen = sizeof(struct ether_header);
                break;
        
#if FDDI
        case DLT_FDDI:
        #if defined(__FreeBSD__) || defined(__bsdi__)
                sa_family = AF_IMPLINK;
                hlen = 0;
        #else
                sa_family = AF_UNSPEC;
                /* XXX 4(FORMAC)+6(dst)+6(src)+3(LLC)+5(SNAP) */
                hlen = 24;
        #endif
                break;
#endif /* FDDI */
        
        case DLT_RAW:
        case DLT_NULL:
                sa_family = AF_UNSPEC;
                hlen = 0;
                break;
        
        #ifdef __FreeBSD__
        case DLT_ATM_RFC1483:
                /*
                 * en atm driver requires 4-byte atm pseudo header.
                 * though it isn't standard, vpi:vci needs to be
                 * specified anyway.
                 */
                sa_family = AF_UNSPEC;
                hlen = 12;      /* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
                break;
        #endif

        case DLT_PPP:
                sa_family = AF_UNSPEC;
                hlen = 4;       /* This should match PPP_HDRLEN */
                break;
        
        case DLT_APPLE_IP_OVER_IEEE1394:
                sa_family = AF_UNSPEC;
                hlen = sizeof(struct firewire_header);
                break;

        case DLT_IEEE802_11:            /* IEEE 802.11 wireless */
                sa_family = AF_IEEE80211;
                hlen = 0;
                break;

        default:
                return (EIO);
        }

        // LP64todo - fix this!
        len = uio_resid(uio);
        *datlen = len - hlen;
        if ((unsigned)len > MCLBYTES)
                return (EIO);

        if (sockp) {
                /*
                 * Build a sockaddr based on the data link layer type.
                 * We do this at this level because the ethernet header
                 * is copied directly into the data field of the sockaddr.
                 * In the case of SLIP, there is no header and the packet
                 * is forwarded as is.
                 * Also, we are careful to leave room at the front of the mbuf
                 * for the link level header.
                 */
                if ((hlen + SOCKADDR_HDR_LEN) > sockp->sa_len) {
                        return (EIO);
                }
                sockp->sa_family = sa_family;
        } else {
                /*
                 * We're directly sending the packet data supplied by
                 * the user; we don't need to make room for the link
                 * header, and don't need the header length value any
                 * more, so set it to 0.
                 */
                hlen = 0;
        }
        
        MGETHDR(m, M_WAIT, MT_DATA);
        if (m == 0)
                return (ENOBUFS);
        if ((unsigned)len > MHLEN) {
#if BSD >= 199103
                MCLGET(m, M_WAIT);
                if ((m->m_flags & M_EXT) == 0) {
#else
                MCLGET(m);
                if (m->m_len != MCLBYTES) {
#endif
                        error = ENOBUFS;
                        goto bad;
                }
        }
        m->m_pkthdr.len = m->m_len = len;
        m->m_pkthdr.rcvif = NULL;
        *mp = m;
        /*
         * Make room for link header.
         */
        if (hlen != 0) {
                m->m_pkthdr.len -= hlen;
                m->m_len -= hlen;
#if BSD >= 199103
                m->m_data += hlen; /* XXX */
#else
                m->m_off += hlen;
#endif
                error = UIOMOVE((caddr_t)sockp->sa_data, hlen, UIO_WRITE, uio);
                if (error)
                        goto bad;
        }
        error = UIOMOVE(mtod(m, caddr_t), len - hlen, UIO_WRITE, uio);
        if (!error)
                return (0);
 bad:
        m_freem(m);
        return (error);
}

#ifdef __APPLE__

/*
 * The dynamic addition of a new device node must block all processes that are opening 
 * the last device so that no process will get an unexpected ENOENT 
 */
static void
bpf_make_dev_t(int maj)
{
        static int              bpf_growing = 0;
        unsigned int    cur_size = nbpfilter, i;

        if (nbpfilter >= bpf_maxdevices)
                return;

        while (bpf_growing) {
                /* Wait until new device has been created */
                (void)tsleep((caddr_t)&bpf_growing, PZERO, "bpf_growing", 0);
        }
        if (nbpfilter > cur_size) {
                /* other thread grew it already */
                return;
        }
        bpf_growing = 1;
        
        /* need to grow bpf_dtab first */
        if (nbpfilter == bpf_dtab_size) {
                int new_dtab_size;
                struct bpf_d **new_dtab = NULL;
                struct bpf_d **old_dtab = NULL;
                
                new_dtab_size = bpf_dtab_size + NBPFILTER;      
                new_dtab = (struct bpf_d **)_MALLOC(sizeof(struct bpf_d *) * new_dtab_size, M_DEVBUF, M_WAIT);
                if (new_dtab == 0) {
                        printf("bpf_make_dev_t: malloc bpf_dtab failed\n");
                        goto done;
                }
                if (bpf_dtab) {
                        bcopy(bpf_dtab, new_dtab, 
                                  sizeof(struct bpf_d *) * bpf_dtab_size);
                }
                bzero(new_dtab + bpf_dtab_size, 
                          sizeof(struct bpf_d *) * NBPFILTER);
                old_dtab = bpf_dtab;
                bpf_dtab = new_dtab;
                bpf_dtab_size = new_dtab_size;
                if (old_dtab != NULL)
                        _FREE(old_dtab, M_DEVBUF);
        }
        i = nbpfilter++;
        (void) devfs_make_node(makedev(maj, i),
                                DEVFS_CHAR, UID_ROOT, GID_WHEEL, 0600,
                                "bpf%d", i);
done:
        bpf_growing = 0;
        wakeup((caddr_t)&bpf_growing);
}

#endif

/*
 * Attach file to the bpf interface, i.e. make d listen on bp.
 */
static errno_t
bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
{
        int first = bp->bif_dlist == NULL;
        int     error = 0;
        
        /*
         * Point d at bp, and add d to the interface's list of listeners.
         * Finally, point the driver's bpf cookie at the interface so
         * it will divert packets to bpf.
         */
        d->bd_bif = bp;
        d->bd_next = bp->bif_dlist;
        bp->bif_dlist = d;
        
        if (first) {
                /* Find the default bpf entry for this ifp */
                if (bp->bif_ifp->if_bpf == NULL) {
                        struct bpf_if   *primary;
                        
                        for (primary = bpf_iflist; primary && primary->bif_ifp != bp->bif_ifp;
                                 primary = primary->bif_next)
                                ;
                
                        bp->bif_ifp->if_bpf = primary;
                }
                
                /* Only call dlil_set_bpf_tap for primary dlt */
                if (bp->bif_ifp->if_bpf == bp)
                        dlil_set_bpf_tap(bp->bif_ifp, BPF_TAP_INPUT_OUTPUT, bpf_tap_callback);
                
                if (bp->bif_tap)
                        error = bp->bif_tap(bp->bif_ifp, bp->bif_dlt, BPF_TAP_INPUT_OUTPUT);
        }

        return error;
}

/*
 * Detach a file from its interface.
 */
static void
bpf_detachd(struct bpf_d *d)
{
        struct bpf_d **p;
        struct bpf_if *bp;
        struct ifnet  *ifp;

        ifp = d->bd_bif->bif_ifp;
        bp = d->bd_bif;
        
        /* Remove d from the interface's descriptor list. */
        p = &bp->bif_dlist;
        while (*p != d) {
                p = &(*p)->bd_next;
                if (*p == 0)
                        panic("bpf_detachd: descriptor not in list");
        }
        *p = (*p)->bd_next;
        if (bp->bif_dlist == 0) {
                /*
                 * Let the driver know that there are no more listeners.
                 */
                /* Only call dlil_set_bpf_tap for primary dlt */
                if (bp->bif_ifp->if_bpf == bp)
                        dlil_set_bpf_tap(ifp, BPF_TAP_DISABLE, NULL);
                if (bp->bif_tap)
                        bp->bif_tap(ifp, bp->bif_dlt, BPF_TAP_DISABLE);
                
                for (bp = bpf_iflist; bp; bp = bp->bif_next)
                        if (bp->bif_ifp == ifp && bp->bif_dlist != 0)
                                break;
                if (bp == NULL)
                        ifp->if_bpf = NULL;
        }
        d->bd_bif = NULL;
        /*
         * Check if this descriptor had requested promiscuous mode.
         * If so, turn it off.
         */
        if (d->bd_promisc) {
                d->bd_promisc = 0;
                lck_mtx_unlock(bpf_mlock);
                if (ifnet_set_promiscuous(ifp, 0)) {
                        /*
                         * Something is really wrong if we were able to put
                         * the driver into promiscuous mode, but can't
                         * take it out.
                         * Most likely the network interface is gone.
                         */
                        printf("bpf: ifnet_set_promiscuous failed");
                }
                lck_mtx_lock(bpf_mlock);
        }
}


/*
 * Open ethernet device.  Returns ENXIO for illegal minor device number,
 * EBUSY if file is open by another process.
 */
/* ARGSUSED */
int
bpfopen(dev_t dev, int flags, __unused int fmt,
        __unused struct proc *p)
{
        struct bpf_d *d;

        lck_mtx_lock(bpf_mlock);
        if ((unsigned int) minor(dev) >= nbpfilter) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }
        /* 
         * New device nodes are created on demand when opening the last one. 
         * The programming model is for processes to loop on the minor starting at 0 
         * as long as EBUSY is returned. The loop stops when either the open succeeds or 
         * an error other that EBUSY is returned. That means that bpf_make_dev_t() must 
         * block all processes that are opening the last  node. If not all 
         * processes are blocked, they could unexpectedly get ENOENT and abort their 
         * opening loop.
         */
        if ((unsigned int) minor(dev) == (nbpfilter - 1))
                bpf_make_dev_t(major(dev));

        /*
         * Each minor can be opened by only one process.  If the requested 
         * minor is in use, return EBUSY.
         *
         * Important: bpfopen() and bpfclose() have to check and set the status of a device
         * in the same lockin context otherwise the device may be leaked because the vnode use count 
         * will be unpextectly greater than 1 when close() is called.
         */
        if (bpf_dtab[minor(dev)] == 0) {
                bpf_dtab[minor(dev)] = (void *)1;       /* Mark opening */
        } else {
                lck_mtx_unlock(bpf_mlock);
                return (EBUSY);
        }
        d = (struct bpf_d *)_MALLOC(sizeof(struct bpf_d), M_DEVBUF, M_WAIT);
        if (d == NULL) {
                /* this really is a catastrophic failure */
                printf("bpfopen: malloc bpf_d failed\n");
                bpf_dtab[minor(dev)] = NULL;
                lck_mtx_unlock(bpf_mlock);
                return ENOMEM;
        }
        bzero(d, sizeof(struct bpf_d));
        
        /*
         * It is not necessary to take the BPF lock here because no other 
         * thread can access the device until it is marked opened...
         */
        
        /* Mark "in use" and do most initialization. */
        d->bd_bufsize = bpf_bufsize;
        d->bd_sig = SIGIO;
        d->bd_seesent = 1;
        d->bd_oflags = flags;
#if CONFIG_MACF_NET
        mac_bpfdesc_label_init(d);
        mac_bpfdesc_label_associate(kauth_cred_get(), d);
#endif
        bpf_dtab[minor(dev)] = d;                               /* Mark opened */
        lck_mtx_unlock(bpf_mlock);

        return (0);
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
/* ARGSUSED */
int
bpfclose(dev_t dev, __unused int flags, __unused int fmt,
         __unused struct proc *p)
{
        struct bpf_d *d;

        /* Take BPF lock to ensure no other thread is using the device */
        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }       
        bpf_dtab[minor(dev)] = (void *)1;               /* Mark closing */

        if (d->bd_bif)
                bpf_detachd(d);
        selthreadclear(&d->bd_sel);
#if CONFIG_MACF_NET
        mac_bpfdesc_label_destroy(d);
#endif
        bpf_freed(d);

        /* Mark free in same context as bpfopen comes to check */
        bpf_dtab[minor(dev)] = NULL;                    /* Mark closed */
        lck_mtx_unlock(bpf_mlock);
        
        _FREE(d, M_DEVBUF);
        
        return (0);
}


#define BPF_SLEEP bpf_sleep

static int
bpf_sleep(struct bpf_d *d, int pri, const char *wmesg, int timo)
{
        int st;

        lck_mtx_unlock(bpf_mlock);
        
        st = tsleep((caddr_t)d, pri, wmesg, timo);
        
        lck_mtx_lock(bpf_mlock);
        
        return st;
}

/*
 * Rotate the packet buffers in descriptor d.  Move the store buffer
 * into the hold slot, and the free buffer into the store slot.
 * Zero the length of the new store buffer.
 */
#define ROTATE_BUFFERS(d) \
        (d)->bd_hbuf = (d)->bd_sbuf; \
        (d)->bd_hlen = (d)->bd_slen; \
        (d)->bd_sbuf = (d)->bd_fbuf; \
        (d)->bd_slen = 0; \
        (d)->bd_fbuf = NULL;
/*
 *  bpfread - read next chunk of packets from buffers
 */
int
bpfread(dev_t dev, struct uio *uio, int ioflag)
{
        struct bpf_d *d;
        int error;

        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }


        /*
         * Restrict application to use a buffer the same size as
         * as kernel buffers.
         */
        if (uio_resid(uio) != d->bd_bufsize) {
                lck_mtx_unlock(bpf_mlock);
                return (EINVAL);
        }

        /*
         * If the hold buffer is empty, then do a timed sleep, which
         * ends when the timeout expires or when enough packets
         * have arrived to fill the store buffer.
         */
        while (d->bd_hbuf == 0) {
                if (d->bd_immediate && d->bd_slen != 0) {
                        /*
                         * A packet(s) either arrived since the previous
                         * read or arrived while we were asleep.
                         * Rotate the buffers and return what's here.
                         */
                        ROTATE_BUFFERS(d);
                        break;
                }

                /*
                 * No data is available, check to see if the bpf device
                 * is still pointed at a real interface.  If not, return
                 * ENXIO so that the userland process knows to rebind
                 * it before using it again.
                 */
                if (d->bd_bif == NULL) {
                        lck_mtx_unlock(bpf_mlock);
                        return (ENXIO);
                }
                if (ioflag & IO_NDELAY) {
                        lck_mtx_unlock(bpf_mlock);
                        return (EWOULDBLOCK);
                }
                error = BPF_SLEEP(d, PRINET|PCATCH, "bpf",
                                  d->bd_rtout);
                /*
                 * Make sure device is still opened
                 */
                d = bpf_dtab[minor(dev)];
                if (d == 0 || d == (void *)1) {
                        lck_mtx_unlock(bpf_mlock);
                        return (ENXIO);
                }
                if (error == EINTR || error == ERESTART) {
                        lck_mtx_unlock(bpf_mlock);
                        return (error);
                }
                if (error == EWOULDBLOCK) {
                        /*
                         * On a timeout, return what's in the buffer,
                         * which may be nothing.  If there is something
                         * in the store buffer, we can rotate the buffers.
                         */
                        if (d->bd_hbuf)
                                /*
                                 * We filled up the buffer in between
                                 * getting the timeout and arriving
                                 * here, so we don't need to rotate.
                                 */
                                break;

                        if (d->bd_slen == 0) {
                                lck_mtx_unlock(bpf_mlock);
                                return (0);
                        }
                        ROTATE_BUFFERS(d);
                        break;
                }
        }
        /*
         * At this point, we know we have something in the hold slot.
         */

        /*
         * Move data from hold buffer into user space.
         * We know the entire buffer is transferred since
         * we checked above that the read buffer is bpf_bufsize bytes.
         */
        error = UIOMOVE(d->bd_hbuf, d->bd_hlen, UIO_READ, uio);

        d->bd_fbuf = d->bd_hbuf;
        d->bd_hbuf = NULL;
        d->bd_hlen = 0;
        lck_mtx_unlock(bpf_mlock);
        return (error);
}


/*
 * If there are processes sleeping on this descriptor, wake them up.
 */
static void
bpf_wakeup(struct bpf_d *d)
{
        wakeup((caddr_t)d);
        if (d->bd_async && d->bd_sig && d->bd_sigio)
                pgsigio(d->bd_sigio, d->bd_sig);

#if BSD >= 199103
        selwakeup(&d->bd_sel);
        KNOTE(&d->bd_sel.si_note, 1);
#ifndef __APPLE__
        /* XXX */
        d->bd_sel.si_pid = 0;
#endif
#else
        if (d->bd_selproc) {
                selwakeup(d->bd_selproc, (int)d->bd_selcoll);
                d->bd_selcoll = 0;
                d->bd_selproc = 0;
        }
#endif
}

/* keep in sync with bpf_movein above: */
#define MAX_DATALINK_HDR_LEN    (sizeof(struct firewire_header))

int
bpfwrite(dev_t dev, struct uio *uio, __unused int ioflag)
{
        struct bpf_d *d;
        struct ifnet *ifp;
        struct mbuf *m = NULL;
        int error;
        char              dst_buf[SOCKADDR_HDR_LEN + MAX_DATALINK_HDR_LEN];
        int datlen = 0;

        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }
        if (d->bd_bif == 0) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        ifp = d->bd_bif->bif_ifp;

        if (uio_resid(uio) == 0) {
                lck_mtx_unlock(bpf_mlock);
                return (0);
        }
        ((struct sockaddr *)dst_buf)->sa_len = sizeof(dst_buf);
        error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, &m, 
                           d->bd_hdrcmplt ? NULL : (struct sockaddr *)dst_buf,
                           &datlen);
        if (error) {
                lck_mtx_unlock(bpf_mlock);
                return (error);
        }

        if ((unsigned)datlen > ifp->if_mtu) {
                lck_mtx_unlock(bpf_mlock);
                m_freem(m);
                return (EMSGSIZE);
        }
        
        if ((error = ifp_use(ifp, kIfNetUseCount_MustNotBeZero)) != 0) {
                lck_mtx_unlock(bpf_mlock);
                m_freem(m);
                return (error);
        }

#if CONFIG_MACF_NET
        mac_mbuf_label_associate_bpfdesc(d, m);
#endif
        lck_mtx_unlock(bpf_mlock);

        if (d->bd_hdrcmplt) {
                if (d->bd_bif->bif_send)
                        error = d->bd_bif->bif_send(ifp, d->bd_bif->bif_dlt, m);
                else
                        error = dlil_output(ifp, 0, m, NULL, NULL, 1);
        }
        else {
                error = dlil_output(ifp, PF_INET, m, NULL, (struct sockaddr *)dst_buf, 0);
        }
        
        if (ifp_unuse(ifp) != 0)
                ifp_use_reached_zero(ifp);
        
        /*
         * The driver frees the mbuf.
         */
        return (error);
}

/*
 * Reset a descriptor by flushing its packet buffer and clearing the
 * receive and drop counts.
 */
static void
reset_d(struct bpf_d *d)
{
        if (d->bd_hbuf) {
                /* Free the hold buffer. */
                d->bd_fbuf = d->bd_hbuf;
                d->bd_hbuf = NULL;
        }
        d->bd_slen = 0;
        d->bd_hlen = 0;
        d->bd_rcount = 0;
        d->bd_dcount = 0;
}

/*
 *  FIONREAD            Check for read packet available.
 *  SIOCGIFADDR         Get interface address - convenient hook to driver.
 *  BIOCGBLEN           Get buffer len [for read()].
 *  BIOCSETF            Set ethernet read filter.
 *  BIOCFLUSH           Flush read packet buffer.
 *  BIOCPROMISC         Put interface into promiscuous mode.
 *  BIOCGDLT            Get link layer type.
 *  BIOCGETIF           Get interface name.
 *  BIOCSETIF           Set interface.
 *  BIOCSRTIMEOUT       Set read timeout.
 *  BIOCGRTIMEOUT       Get read timeout.
 *  BIOCGSTATS          Get packet stats.
 *  BIOCIMMEDIATE       Set immediate mode.
 *  BIOCVERSION         Get filter language version.
 *  BIOCGHDRCMPLT       Get "header already complete" flag
 *  BIOCSHDRCMPLT       Set "header already complete" flag
 *  BIOCGSEESENT        Get "see packets sent" flag
 *  BIOCSSEESENT        Set "see packets sent" flag
 */
/* ARGSUSED */
int
bpfioctl(dev_t dev, u_long cmd, caddr_t addr, __unused int flags,
    struct proc *p)
{
        struct bpf_d *d;
        int error = 0;

        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        switch (cmd) {

        default:
                error = EINVAL;
                break;

        /*
         * Check for read packet available.
         */
        case FIONREAD:
                {
                        int n;

                        n = d->bd_slen;
                        if (d->bd_hbuf)
                                n += d->bd_hlen;

                        *(int *)addr = n;
                        break;
                }

        case SIOCGIFADDR:
                {
                        struct ifnet *ifp;

                        if (d->bd_bif == 0)
                                error = EINVAL;
                        else {
                                ifp = d->bd_bif->bif_ifp;
                                error = ifnet_ioctl(ifp, 0, cmd, addr);
                        }
                        break;
                }

        /*
         * Get buffer len [for read()].
         */
        case BIOCGBLEN:
                *(u_int *)addr = d->bd_bufsize;
                break;

        /*
         * Set buffer length.
         */
        case BIOCSBLEN:
#if BSD < 199103
                error = EINVAL;
#else
                if (d->bd_bif != 0)
                        error = EINVAL;
                else {
                        u_int size = *(u_int *)addr;

                        if (size > bpf_maxbufsize)
                                *(u_int *)addr = size = bpf_maxbufsize;
                        else if (size < BPF_MINBUFSIZE)
                                *(u_int *)addr = size = BPF_MINBUFSIZE;
                        d->bd_bufsize = size;
                }
#endif
                break;

        /*
         * Set link layer read filter.
         */
        case BIOCSETF32: {
                struct bpf_program32 *prg32 = (struct bpf_program32 *)addr;
                error = bpf_setf(d, prg32->bf_len,
                    CAST_USER_ADDR_T(prg32->bf_insns));
                break;
        }

        case BIOCSETF64: {
                struct bpf_program64 *prg64 = (struct bpf_program64 *)addr;
                error = bpf_setf(d, prg64->bf_len, prg64->bf_insns);
                break;
        }

        /*
         * Flush read packet buffer.
         */
        case BIOCFLUSH:
                reset_d(d);
                break;

        /*
         * Put interface into promiscuous mode.
         */
        case BIOCPROMISC:
                if (d->bd_bif == 0) {
                        /*
                         * No interface attached yet.
                         */
                        error = EINVAL;
                        break;
                }
                if (d->bd_promisc == 0) {
                        lck_mtx_unlock(bpf_mlock);
                        error = ifnet_set_promiscuous(d->bd_bif->bif_ifp, 1);
                        lck_mtx_lock(bpf_mlock);
                        if (error == 0)
                                d->bd_promisc = 1;
                }
                break;

        /*
         * Get device parameters.
         */
        case BIOCGDLT:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else
                        *(u_int *)addr = d->bd_bif->bif_dlt;
                break;

        /*
         * Get a list of supported data link types.
         */
        case BIOCGDLTLIST:
                if (d->bd_bif == NULL) {
                        error = EINVAL;
                } else {
                        error = bpf_getdltlist(d,
                            (struct bpf_dltlist *)addr, p);
                }
                break;

        /*
         * Set data link type.
         */
        case BIOCSDLT:
                        if (d->bd_bif == NULL)
                                        error = EINVAL;
                        else
                                        error = bpf_setdlt(d, *(u_int *)addr);
                        break;

        /*
         * Get interface name.
         */
        case BIOCGETIF:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else {
                        struct ifnet *const ifp = d->bd_bif->bif_ifp;
                        struct ifreq *const ifr = (struct ifreq *)addr;

                        snprintf(ifr->ifr_name, sizeof(ifr->ifr_name),
                            "%s%d", ifp->if_name, ifp->if_unit);
                }
                break;

        /*
         * Set interface.
         */
        case BIOCSETIF: {
                ifnet_t ifp;
                ifp = ifunit(((struct ifreq *)addr)->ifr_name);
                if (ifp == NULL)
                        error = ENXIO;
                else
                        error = bpf_setif(d, ifp, 0);
                break;
        }

        /*
         * Set read timeout.
         */
        case BIOCSRTIMEOUT:
                {
                        struct BPF_TIMEVAL *_tv = (struct BPF_TIMEVAL *)addr;
                        struct timeval tv;

                        tv.tv_sec  = _tv->tv_sec;
                        tv.tv_usec = _tv->tv_usec;

                        /*
                         * Subtract 1 tick from tvtohz() since this isn't
                         * a one-shot timer.
                         */
                        if ((error = itimerfix(&tv)) == 0)
                                d->bd_rtout = tvtohz(&tv) - 1;
                        break;
                }

        /*
         * Get read timeout.
         */
        case BIOCGRTIMEOUT:
                {
                        struct BPF_TIMEVAL *tv = (struct BPF_TIMEVAL *)addr;

                        tv->tv_sec = d->bd_rtout / hz;
                        tv->tv_usec = (d->bd_rtout % hz) * tick;
                        break;
                }

        /*
         * Get packet stats.
         */
        case BIOCGSTATS:
                {
                        struct bpf_stat *bs = (struct bpf_stat *)addr;

                        bs->bs_recv = d->bd_rcount;
                        bs->bs_drop = d->bd_dcount;
                        break;
                }

        /*
         * Set immediate mode.
         */
        case BIOCIMMEDIATE:
                d->bd_immediate = *(u_int *)addr;
                break;

        case BIOCVERSION:
                {
                        struct bpf_version *bv = (struct bpf_version *)addr;

                        bv->bv_major = BPF_MAJOR_VERSION;
                        bv->bv_minor = BPF_MINOR_VERSION;
                        break;
                }

        /*
         * Get "header already complete" flag
         */
        case BIOCGHDRCMPLT:
                *(u_int *)addr = d->bd_hdrcmplt;
                break;

        /*
         * Set "header already complete" flag
         */
        case BIOCSHDRCMPLT:
                d->bd_hdrcmplt = *(u_int *)addr ? 1 : 0;
                break;

        /*
         * Get "see sent packets" flag
         */
        case BIOCGSEESENT:
                *(u_int *)addr = d->bd_seesent;
                break;

        /*
         * Set "see sent packets" flag
         */
        case BIOCSSEESENT:
                d->bd_seesent = *(u_int *)addr;
                break;

        case FIONBIO:           /* Non-blocking I/O */
                break;

        case FIOASYNC:          /* Send signal on receive packets */
                d->bd_async = *(int *)addr;
                break;
#ifndef __APPLE__
        case FIOSETOWN:
                error = fsetown(*(int *)addr, &d->bd_sigio);
                break;

        case FIOGETOWN:
                *(int *)addr = fgetown(d->bd_sigio);
                break;

        /* This is deprecated, FIOSETOWN should be used instead. */
        case TIOCSPGRP:
                error = fsetown(-(*(int *)addr), &d->bd_sigio);
                break;

        /* This is deprecated, FIOGETOWN should be used instead. */
        case TIOCGPGRP:
                *(int *)addr = -fgetown(d->bd_sigio);
                break;
#endif
        case BIOCSRSIG:         /* Set receive signal */
                {
                        u_int sig;

                        sig = *(u_int *)addr;

                        if (sig >= NSIG)
                                error = EINVAL;
                        else
                                d->bd_sig = sig;
                        break;
                }
        case BIOCGRSIG:
                *(u_int *)addr = d->bd_sig;
                break;
        }
        
        lck_mtx_unlock(bpf_mlock);

        return (error);
}

/*
 * Set d's packet filter program to fp.  If this file already has a filter,
 * free it and replace it.  Returns EINVAL for bogus requests.
 */
static int
bpf_setf(struct bpf_d *d, u_int bf_len, user_addr_t bf_insns)
{
        struct bpf_insn *fcode, *old;
        u_int flen, size;

        old = d->bd_filter;
        if (bf_insns == USER_ADDR_NULL) {
                if (bf_len != 0)
                        return (EINVAL);
                d->bd_filter = NULL;
                reset_d(d);
                if (old != 0)
                        FREE((caddr_t)old, M_DEVBUF);
                return (0);
        }
        flen = bf_len;
        if (flen > BPF_MAXINSNS)
                return (EINVAL);

        size = flen * sizeof(struct bpf_insn);
        fcode = (struct bpf_insn *) _MALLOC(size, M_DEVBUF, M_WAIT);
#ifdef __APPLE__
        if (fcode == NULL)
                return (ENOBUFS);
#endif
        if (copyin(bf_insns, (caddr_t)fcode, size) == 0 &&
            bpf_validate(fcode, (int)flen)) {
                d->bd_filter = fcode;
                reset_d(d);
                if (old != 0)
                        FREE((caddr_t)old, M_DEVBUF);

                return (0);
        }
        FREE((caddr_t)fcode, M_DEVBUF);
        return (EINVAL);
}

/*
 * Detach a file from its current interface (if attached at all) and attach
 * to the interface indicated by the name stored in ifr.
 * Return an errno or 0.
 */
static int
bpf_setif(struct bpf_d *d, ifnet_t theywant, u_int32_t dlt)
{
        struct bpf_if *bp;
        int error;
        
        /*
         * Look through attached interfaces for the named one.
         */
        for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
                struct ifnet *ifp = bp->bif_ifp;

                if (ifp == 0 || ifp != theywant || (dlt != 0 && dlt != bp->bif_dlt))
                        continue;
                /*
                 * We found the requested interface.
                 * If it's not up, return an error.
                 * Allocate the packet buffers if we need to.
                 * If we're already attached to requested interface,
                 * just flush the buffer.
                 */
                if ((ifp->if_flags & IFF_UP) == 0)
                        return (ENETDOWN);

                if (d->bd_sbuf == 0) {
                        error = bpf_allocbufs(d);
                        if (error != 0)
                                return (error);
                }
                if (bp != d->bd_bif) {
                        if (d->bd_bif)
                                /*
                                 * Detach if attached to something else.
                                 */
                                bpf_detachd(d);

                        if (bpf_attachd(d, bp) != 0) {
                                return ENXIO;
                        }
                }
                reset_d(d);
                return (0);
        }
        /* Not found. */
        return (ENXIO);
}



/*
 * Get a list of available data link type of the interface.
 */
static int
bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl, struct proc *p)
{
        u_int           n;
        int             error;
        struct ifnet    *ifp;
        struct bpf_if   *bp;
        user_addr_t     dlist;

        if (proc_is64bit(p)) {
                dlist = (user_addr_t)bfl->bfl_u.bflu_pad;
        } else {
                dlist = CAST_USER_ADDR_T(bfl->bfl_u.bflu_list);
        }

        ifp = d->bd_bif->bif_ifp;
        n = 0;
        error = 0;
        for (bp = bpf_iflist; bp; bp = bp->bif_next) {
                if (bp->bif_ifp != ifp)
                        continue;
                if (dlist != USER_ADDR_NULL) {
                        if (n >= bfl->bfl_len) {
                                return (ENOMEM);
                        }
                        error = copyout(&bp->bif_dlt, dlist,
                            sizeof (bp->bif_dlt));
                        dlist += sizeof (bp->bif_dlt);
                }
                n++;
        }
        bfl->bfl_len = n;
        return (error);
}

/*
 * Set the data link type of a BPF instance.
 */
static int
bpf_setdlt(struct bpf_d *d, uint32_t dlt)
        

{
        int error, opromisc;
        struct ifnet *ifp;
        struct bpf_if *bp;
        
        if (d->bd_bif->bif_dlt == dlt)
                return (0);
        ifp = d->bd_bif->bif_ifp;
        for (bp = bpf_iflist; bp; bp = bp->bif_next) {
                if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
                        break;
        }
        if (bp != NULL) {
                opromisc = d->bd_promisc;
                bpf_detachd(d);
                error = bpf_attachd(d, bp);
                if (error) {
                        printf("bpf_setdlt: bpf_attachd %s%d failed (%d)\n",
                                ifnet_name(bp->bif_ifp), ifnet_unit(bp->bif_ifp), error);
                        return error;
                }
                reset_d(d);
                if (opromisc) {
                        lck_mtx_unlock(bpf_mlock);
                        error = ifnet_set_promiscuous(bp->bif_ifp, 1);
                        lck_mtx_lock(bpf_mlock);
                        if (error)
                                printf("bpf_setdlt: ifpromisc %s%d failed (%d)\n",
                                           ifnet_name(bp->bif_ifp), ifnet_unit(bp->bif_ifp), error);
                        else
                                d->bd_promisc = 1;
                }
        }
        return (bp == NULL ? EINVAL : 0);
}

/*
 * Support for select()
 *
 * Return true iff the specific operation will not block indefinitely.
 * Otherwise, return false but make a note that a selwakeup() must be done.
 */
int
bpfpoll(dev_t dev, int events, void * wql, struct proc *p)
{
        struct bpf_d *d;
        int revents = 0;

        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        /*
         * An imitation of the FIONREAD ioctl code.
         */
        if (d->bd_bif == NULL) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        if (events & (POLLIN | POLLRDNORM)) {
                if (d->bd_hlen != 0 || (d->bd_immediate && d->bd_slen != 0))
                        revents |= events & (POLLIN | POLLRDNORM);
                else
                        selrecord(p, &d->bd_sel, wql);
        }

        lck_mtx_unlock(bpf_mlock);
        return (revents);
}

/*
 * Support for kevent() system call.  Register EVFILT_READ filters and
 * reject all others.
 */
int bpfkqfilter(dev_t dev, struct knote *kn);
static void filt_bpfdetach(struct knote *);
static int filt_bpfread(struct knote *, long);

static struct filterops bpfread_filtops = {
        .f_isfd = 1, 
        .f_detach = filt_bpfdetach,
        .f_event = filt_bpfread,
};

int
bpfkqfilter(dev_t dev, struct knote *kn)
{
        struct bpf_d *d;

        /*
         * Is this device a bpf?
         */
        if (major(dev) != CDEV_MAJOR) {
                return (EINVAL);
        }

        if (kn->kn_filter != EVFILT_READ) {
                return (EINVAL);
        }

        lck_mtx_lock(bpf_mlock);

        d = bpf_dtab[minor(dev)];
        if (d == 0 || d == (void *)1) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        /*
         * An imitation of the FIONREAD ioctl code.
         */
        if (d->bd_bif == NULL) {
                lck_mtx_unlock(bpf_mlock);
                return (ENXIO);
        }

        kn->kn_hook = d;
        kn->kn_fop = &bpfread_filtops;
        KNOTE_ATTACH(&d->bd_sel.si_note, kn);
        lck_mtx_unlock(bpf_mlock);
        return 0;
}

static void
filt_bpfdetach(struct knote *kn)
{
        struct bpf_d *d = (struct bpf_d *)kn->kn_hook;

        lck_mtx_lock(bpf_mlock);
        KNOTE_DETACH(&d->bd_sel.si_note, kn);
        lck_mtx_unlock(bpf_mlock);
}

static int
filt_bpfread(struct knote *kn, long hint)
{
        struct bpf_d *d = (struct bpf_d *)kn->kn_hook;
        int ready = 0;

        if (hint == 0)
                lck_mtx_lock(bpf_mlock);

        if (d->bd_immediate) {
                kn->kn_data = (d->bd_hlen == 0 ? d->bd_slen : d->bd_hlen);
                ready = (kn->kn_data >= ((kn->kn_sfflags & NOTE_LOWAT) ? 
                                        kn->kn_sdata : 1));
        } else {
                kn->kn_data = d->bd_hlen;
                ready = (kn->kn_data > 0);
        }

        if (hint == 0)
                lck_mtx_unlock(bpf_mlock);
        return (ready);
}

static inline void*
_cast_non_const(const void * ptr) {
        union {
                const void*             cval;
                void*                   val;
        } ret;
        
        ret.cval = ptr;
        return (ret.val);
}

/*
 * Copy data from an mbuf chain into a buffer.  This code is derived
 * from m_copydata in sys/uipc_mbuf.c.
 */
static void
bpf_mcopy(const void *src_arg, void *dst_arg, size_t len)
{
        struct mbuf *m = _cast_non_const(src_arg);
        u_int count;
        u_char *dst;

        dst = dst_arg;
        while (len > 0) {
                if (m == 0)
                        panic("bpf_mcopy");
                count = min(m->m_len, len);
                bcopy(mbuf_data(m), dst, count);
                m = m->m_next;
                dst += count;
                len -= count;
        }
}

static inline void
bpf_tap_imp(
        ifnet_t         ifp,
        u_int32_t       dlt,
        mbuf_t          m,
        void*           hdr,
        size_t          hlen,
        int                     outbound)
{
        struct bpf_if *bp;

        /*
         * It's possible that we get here after the bpf descriptor has been
         * detached from the interface; in such a case we simply return.
         * Lock ordering is important since we can be called asynchronously
         * (from the IOKit) to process an inbound packet; when that happens
         * we would have been holding its "gateLock" and will be acquiring
         * "bpf_mlock" upon entering this routine.  Due to that, we release
         * "bpf_mlock" prior to calling ifnet_set_promiscuous (which will
         * acquire "gateLock" in the IOKit), in order to avoid a deadlock
         * when a ifnet_set_promiscuous request simultaneously collides with
         * an inbound packet being passed into the tap callback.
         */
        lck_mtx_lock(bpf_mlock);
        if (ifp->if_bpf == NULL) {
                lck_mtx_unlock(bpf_mlock);
                return;
        }
        bp = ifp->if_bpf;
        for (bp = ifp->if_bpf; bp && bp->bif_ifp == ifp &&
                 (dlt != 0 && bp->bif_dlt != dlt); bp = bp->bif_next)
                ;
        if (bp && bp->bif_ifp == ifp && bp->bif_dlist != NULL) {
                struct bpf_d    *d;
                struct m_hdr    hack_hdr;
                u_int   pktlen = 0;
                u_int   slen = 0;
                struct mbuf *m0;
                
                if (hdr) {
                        /*
                         * This is gross. We mock up an mbuf that points to the
                         * header buffer. This means we don't have to copy the
                         * header. A number of interfaces prepended headers just
                         * for bpf by allocating an mbuf on the stack. We want to
                         * give developers an easy way to prepend a header for bpf.
                         * Since a developer allocating an mbuf on the stack is bad,
                         * we do even worse here, allocating only a header to point
                         * to a buffer the developer supplied. This makes assumptions
                         * that bpf_filter and catchpacket will not look at anything
                         * in the mbuf other than the header. This was true at the
                         * time this code was written.
                         */
                        hack_hdr.mh_next = m;
                        hack_hdr.mh_nextpkt = NULL;
                        hack_hdr.mh_len = hlen;
                        hack_hdr.mh_data = hdr;
                        hack_hdr.mh_type = m->m_type;
                        hack_hdr.mh_flags = 0;
                        
                        m = (mbuf_t)&hack_hdr;
                }

                for (m0 = m; m0 != 0; m0 = m0->m_next)
                        pktlen += m0->m_len;
                
                for (d = bp->bif_dlist; d; d = d->bd_next) {
                        if (outbound && !d->bd_seesent)
                                continue;
                        ++d->bd_rcount;
                        slen = bpf_filter(d->bd_filter, (u_char *)m, pktlen, 0);
                        if (slen != 0) {
#if CONFIG_MACF_NET
                                if (mac_bpfdesc_check_receive(d, bp->bif_ifp) != 0)
                                        continue;
#endif
                                catchpacket(d, (u_char *)m, pktlen, slen, bpf_mcopy);
                        }
                }
        }
        lck_mtx_unlock(bpf_mlock);
}

void
bpf_tap_out(
        ifnet_t         ifp,
        u_int32_t       dlt,
        mbuf_t          m,
        void*           hdr,
        size_t          hlen)
{
        bpf_tap_imp(ifp, dlt, m, hdr, hlen, 1);
}

void
bpf_tap_in(
        ifnet_t         ifp,
        u_int32_t       dlt,
        mbuf_t          m,
        void*           hdr,
        size_t          hlen)
{
        bpf_tap_imp(ifp, dlt, m, hdr, hlen, 0);
}

/* Callback registered with Ethernet driver. */
static int bpf_tap_callback(struct ifnet *ifp, struct mbuf *m)
{
        bpf_tap_imp(ifp, 0, m, NULL, 0, mbuf_pkthdr_rcvif(m) == NULL);
        
        return 0;
}

/*
 * Move the packet data from interface memory (pkt) into the
 * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
 * otherwise 0.  "copy" is the routine called to do the actual data
 * transfer.  bcopy is passed in to copy contiguous chunks, while
 * bpf_mcopy is passed in to copy mbuf chains.  In the latter case,
 * pkt is really an mbuf.
 */
static void
catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen, 
        void (*cpfn)(const void *, void *, size_t))
{
        struct bpf_hdr *hp;
        int totlen, curlen;
        int hdrlen = d->bd_bif->bif_hdrlen;
        /*
         * Figure out how many bytes to move.  If the packet is
         * greater or equal to the snapshot length, transfer that
         * much.  Otherwise, transfer the whole packet (unless
         * we hit the buffer size limit).
         */
        totlen = hdrlen + min(snaplen, pktlen);
        if (totlen > d->bd_bufsize)
                totlen = d->bd_bufsize;

        /*
         * Round up the end of the previous packet to the next longword.
         */
        curlen = BPF_WORDALIGN(d->bd_slen);
        if (curlen + totlen > d->bd_bufsize) {
                /*
                 * This packet will overflow the storage buffer.
                 * Rotate the buffers if we can, then wakeup any
                 * pending reads.
                 */
                if (d->bd_fbuf == 0) {
                        /*
                         * We haven't completed the previous read yet,
                         * so drop the packet.
                         */
                        ++d->bd_dcount;
                        return;
                }
                ROTATE_BUFFERS(d);
                bpf_wakeup(d);
                curlen = 0;
        }
        else if (d->bd_immediate)
                /*
                 * Immediate mode is set.  A packet arrived so any
                 * reads should be woken up.
                 */
                bpf_wakeup(d);

        /*
         * Append the bpf header.
         */
        hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
        struct timeval tv;
        microtime(&tv);
        hp->bh_tstamp.tv_sec = tv.tv_sec;
        hp->bh_tstamp.tv_usec = tv.tv_usec;
        hp->bh_datalen = pktlen;
        hp->bh_hdrlen = hdrlen;
        /*
         * Copy the packet data into the store buffer and update its length.
         */
        (*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = totlen - hdrlen));
        d->bd_slen = curlen + totlen;
}

/*
 * Initialize all nonzero fields of a descriptor.
 */
static int
bpf_allocbufs(struct bpf_d *d)
{
        d->bd_fbuf = (caddr_t) _MALLOC(d->bd_bufsize, M_DEVBUF, M_WAIT);
        if (d->bd_fbuf == 0)
                return (ENOBUFS);

        d->bd_sbuf = (caddr_t) _MALLOC(d->bd_bufsize, M_DEVBUF, M_WAIT);
        if (d->bd_sbuf == 0) {
                FREE(d->bd_fbuf, M_DEVBUF);
                return (ENOBUFS);
        }
        d->bd_slen = 0;
        d->bd_hlen = 0;
        return (0);
}

/*
 * Free buffers currently in use by a descriptor.
 * Called on close.
 */
static void
bpf_freed(struct bpf_d *d)
{
        /*
         * We don't need to lock out interrupts since this descriptor has
         * been detached from its interface and it yet hasn't been marked
         * free.
         */
        if (d->bd_sbuf != 0) {
                FREE(d->bd_sbuf, M_DEVBUF);
                if (d->bd_hbuf != 0)
                        FREE(d->bd_hbuf, M_DEVBUF);
                if (d->bd_fbuf != 0)
                        FREE(d->bd_fbuf, M_DEVBUF);
        }
        if (d->bd_filter)
                FREE((caddr_t)d->bd_filter, M_DEVBUF);
}

/*
 * Attach an interface to bpf.  driverp is a pointer to a (struct bpf_if *)
 * in the driver's softc; dlt is the link layer type; hdrlen is the fixed
 * size of the link header (variable length headers not yet supported).
 */
void
bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
{
        bpf_attach(ifp, dlt, hdrlen, NULL, NULL);
}

errno_t
bpf_attach(
        ifnet_t                 ifp,
        u_int32_t               dlt,
        u_int32_t               hdrlen,
        bpf_send_func   send,
        bpf_tap_func    tap)
{
        struct bpf_if *bp_new;
        struct bpf_if *bp_temp;
        struct bpf_if *bp_first = NULL;
        
        bp_new = (struct bpf_if *) _MALLOC(sizeof(*bp_new), M_DEVBUF, M_WAIT);
        if (bp_new == 0)
                panic("bpfattach");

        lck_mtx_lock(bpf_mlock);

        /*
         * Check if this interface/dlt is already attached, record first
         * attachment for this interface.
         */
        for (bp_temp = bpf_iflist; bp_temp && (bp_temp->bif_ifp != ifp ||
                 bp_temp->bif_dlt != dlt); bp_temp = bp_temp->bif_next) {
                 if (bp_temp->bif_ifp == ifp && bp_first == NULL)
                        bp_first = bp_temp;
        }
        
        if (bp_temp != NULL) {
                printf("bpfattach - %s%d with dlt %d is already attached\n",
                        ifp->if_name, ifp->if_unit, dlt);
                FREE(bp_new, M_DEVBUF);
                lck_mtx_unlock(bpf_mlock);
                return EEXIST;
        }
        
        bzero(bp_new, sizeof(*bp_new));
        bp_new->bif_ifp = ifp;
        bp_new->bif_dlt = dlt;
        bp_new->bif_send = send;
        bp_new->bif_tap = tap;
        
        if (bp_first == NULL) {
                /* No other entries for this ifp */
                bp_new->bif_next = bpf_iflist;
                bpf_iflist = bp_new;
        }
        else {
                /* Add this after the first entry for this interface */
                bp_new->bif_next = bp_first->bif_next;
                bp_first->bif_next = bp_new;
        }
        
        /*
         * Compute the length of the bpf header.  This is not necessarily
         * equal to SIZEOF_BPF_HDR because we want to insert spacing such
         * that the network layer header begins on a longword boundary (for
         * performance reasons and to alleviate alignment restrictions).
         */
        bp_new->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;
        
        /* Take a reference on the interface */
        ifnet_reference(ifp);

        lck_mtx_unlock(bpf_mlock);

#ifndef __APPLE__
        if (bootverbose)
                printf("bpf: %s%d attached\n", ifp->if_name, ifp->if_unit);
#endif

        return 0;
}

/*
 * Detach bpf from an interface.  This involves detaching each descriptor
 * associated with the interface, and leaving bd_bif NULL.  Notify each
 * descriptor as it's detached so that any sleepers wake up and get
 * ENXIO.
 */
void
bpfdetach(struct ifnet *ifp)
{
        struct bpf_if   *bp, *bp_prev, *bp_next;
        struct bpf_if   *bp_free = NULL;
        struct bpf_d    *d;

        
        lck_mtx_lock(bpf_mlock);

        /* Locate BPF interface information */
        bp_prev = NULL;
        for (bp = bpf_iflist; bp != NULL; bp = bp_next) {
                bp_next = bp->bif_next;
                if (ifp != bp->bif_ifp) {
                        bp_prev = bp;
                        continue;
                }
                
                while ((d = bp->bif_dlist) != NULL) {
                        bpf_detachd(d);
                        bpf_wakeup(d);
                }
        
                if (bp_prev) {
                        bp_prev->bif_next = bp->bif_next;
                } else {
                        bpf_iflist = bp->bif_next;
                }
                
                bp->bif_next = bp_free;
                bp_free = bp;
                
                ifnet_release(ifp);
        }

        lck_mtx_unlock(bpf_mlock);

        FREE(bp, M_DEVBUF);

}

void
bpf_init(__unused void *unused)
{
#ifdef __APPLE__
        int     i;
        int     maj;

        if (bpf_devsw_installed == 0) {
                bpf_devsw_installed = 1;

        bpf_mlock_grp_attr = lck_grp_attr_alloc_init();

        bpf_mlock_grp = lck_grp_alloc_init("bpf", bpf_mlock_grp_attr);

        bpf_mlock_attr = lck_attr_alloc_init();

        bpf_mlock = lck_mtx_alloc_init(bpf_mlock_grp, bpf_mlock_attr);

                if (bpf_mlock == 0) {
                        printf("bpf_init: failed to allocate bpf_mlock\n");
                        bpf_devsw_installed = 0;
                        return;
                }
                
                maj = cdevsw_add(CDEV_MAJOR, &bpf_cdevsw);
                if (maj == -1) {
                        if (bpf_mlock)
                                lck_mtx_free(bpf_mlock, bpf_mlock_grp);
                        if (bpf_mlock_attr)
                                lck_attr_free(bpf_mlock_attr);
                        if (bpf_mlock_grp)
                                lck_grp_free(bpf_mlock_grp);
                        if (bpf_mlock_grp_attr)
                                lck_grp_attr_free(bpf_mlock_grp_attr);
                        
                        bpf_mlock = NULL;
                        bpf_mlock_attr = NULL;
                        bpf_mlock_grp = NULL;
                        bpf_mlock_grp_attr = NULL;
                        bpf_devsw_installed = 0;
                        printf("bpf_init: failed to allocate a major number!\n");
                        return;
                }

                for (i = 0 ; i < NBPFILTER; i++)
                        bpf_make_dev_t(maj);
        }
#else
        cdevsw_add(&bpf_cdevsw);
#endif
}

#ifndef __APPLE__
SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvinit,NULL)
#endif

#if CONFIG_MACF_NET
struct label *
mac_bpfdesc_label_get(struct bpf_d *d)
{

        return (d->bd_label);
}

void
mac_bpfdesc_label_set(struct bpf_d *d, struct label *label)
{

        d->bd_label = label;
}
#endif