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[FreeBSD/FreeBSD.git] / sys / net / bpf.c

/*-
 * 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.
 * 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       8.4 (Berkeley) 1/9/95
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_bpf.h"
#include "opt_netgraph.h"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/time.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/filio.h>
#include <sys/sockio.h>
#include <sys/ttycom.h>
#include <sys/uio.h>

#include <sys/event.h>
#include <sys/file.h>
#include <sys/poll.h>
#include <sys/proc.h>

#include <sys/socket.h>

#include <net/if.h>
#include <net/bpf.h>
#include <net/bpf_buffer.h>
#ifdef BPF_JITTER
#include <net/bpf_jitter.h>
#endif
#include <net/bpf_zerocopy.h>
#include <net/bpfdesc.h>
#include <net/vnet.h>

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

#include <net80211/ieee80211_freebsd.h>

#include <security/mac/mac_framework.h>

MALLOC_DEFINE(M_BPF, "BPF", "BPF data");

#if defined(DEV_BPF) || defined(NETGRAPH_BPF)

#define PRINET  26                      /* interruptible */

/*
 * bpf_iflist is a list of BPF interface structures, each corresponding to a
 * specific DLT.  The same network interface might have several BPF interface
 * structures registered by different layers in the stack (i.e., 802.11
 * frames, ethernet frames, etc).
 */
static LIST_HEAD(, bpf_if)      bpf_iflist;
static struct mtx       bpf_mtx;                /* bpf global lock */
static int              bpf_bpfd_cnt;

static void     bpf_attachd(struct bpf_d *, struct bpf_if *);
static void     bpf_detachd(struct bpf_d *);
static void     bpf_freed(struct bpf_d *);
static int      bpf_movein(struct uio *, int, struct ifnet *, struct mbuf **,
                    struct sockaddr *, int *, struct bpf_insn *);
static int      bpf_setif(struct bpf_d *, struct ifreq *);
static void     bpf_timed_out(void *);
static __inline void
                bpf_wakeup(struct bpf_d *);
static void     catchpacket(struct bpf_d *, u_char *, u_int, u_int,
                    void (*)(struct bpf_d *, caddr_t, u_int, void *, u_int),
                    struct timeval *);
static void     reset_d(struct bpf_d *);
static int       bpf_setf(struct bpf_d *, struct bpf_program *, u_long cmd);
static int      bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
static int      bpf_setdlt(struct bpf_d *, u_int);
static void     filt_bpfdetach(struct knote *);
static int      filt_bpfread(struct knote *, long);
static void     bpf_drvinit(void *);
static int      bpf_stats_sysctl(SYSCTL_HANDLER_ARGS);

SYSCTL_NODE(_net, OID_AUTO, bpf, CTLFLAG_RW, 0, "bpf sysctl");
int bpf_maxinsns = BPF_MAXINSNS;
SYSCTL_INT(_net_bpf, OID_AUTO, maxinsns, CTLFLAG_RW,
    &bpf_maxinsns, 0, "Maximum bpf program instructions");
static int bpf_zerocopy_enable = 0;
SYSCTL_INT(_net_bpf, OID_AUTO, zerocopy_enable, CTLFLAG_RW,
    &bpf_zerocopy_enable, 0, "Enable new zero-copy BPF buffer sessions");
SYSCTL_NODE(_net_bpf, OID_AUTO, stats, CTLFLAG_MPSAFE | CTLFLAG_RW,
    bpf_stats_sysctl, "bpf statistics portal");

static  d_open_t        bpfopen;
static  d_read_t        bpfread;
static  d_write_t       bpfwrite;
static  d_ioctl_t       bpfioctl;
static  d_poll_t        bpfpoll;
static  d_kqfilter_t    bpfkqfilter;

static struct cdevsw bpf_cdevsw = {
        .d_version =    D_VERSION,
        .d_open =       bpfopen,
        .d_read =       bpfread,
        .d_write =      bpfwrite,
        .d_ioctl =      bpfioctl,
        .d_poll =       bpfpoll,
        .d_name =       "bpf",
        .d_kqfilter =   bpfkqfilter,
};

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

/*
 * Wrapper functions for various buffering methods.  If the set of buffer
 * modes expands, we will probably want to introduce a switch data structure
 * similar to protosw, et.
 */
static void
bpf_append_bytes(struct bpf_d *d, caddr_t buf, u_int offset, void *src,
    u_int len)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
                return (bpf_buffer_append_bytes(d, buf, offset, src, len));

        case BPF_BUFMODE_ZBUF:
                d->bd_zcopy++;
                return (bpf_zerocopy_append_bytes(d, buf, offset, src, len));

        default:
                panic("bpf_buf_append_bytes");
        }
}

static void
bpf_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset, void *src,
    u_int len)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
                return (bpf_buffer_append_mbuf(d, buf, offset, src, len));

        case BPF_BUFMODE_ZBUF:
                d->bd_zcopy++;
                return (bpf_zerocopy_append_mbuf(d, buf, offset, src, len));

        default:
                panic("bpf_buf_append_mbuf");
        }
}

/*
 * This function gets called when the free buffer is re-assigned.
 */
static void
bpf_buf_reclaimed(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
                return;

        case BPF_BUFMODE_ZBUF:
                bpf_zerocopy_buf_reclaimed(d);
                return;

        default:
                panic("bpf_buf_reclaimed");
        }
}

/*
 * If the buffer mechanism has a way to decide that a held buffer can be made
 * free, then it is exposed via the bpf_canfreebuf() interface.  (1) is
 * returned if the buffer can be discarded, (0) is returned if it cannot.
 */
static int
bpf_canfreebuf(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
                return (bpf_zerocopy_canfreebuf(d));
        }
        return (0);
}

/*
 * Allow the buffer model to indicate that the current store buffer is
 * immutable, regardless of the appearance of space.  Return (1) if the
 * buffer is writable, and (0) if not.
 */
static int
bpf_canwritebuf(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
                return (bpf_zerocopy_canwritebuf(d));
        }
        return (1);
}

/*
 * Notify buffer model that an attempt to write to the store buffer has
 * resulted in a dropped packet, in which case the buffer may be considered
 * full.
 */
static void
bpf_buffull(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
                bpf_zerocopy_buffull(d);
                break;
        }
}

/*
 * Notify the buffer model that a buffer has moved into the hold position.
 */
void
bpf_bufheld(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
                bpf_zerocopy_bufheld(d);
                break;
        }
}

static void
bpf_free(struct bpf_d *d)
{

        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
                return (bpf_buffer_free(d));

        case BPF_BUFMODE_ZBUF:
                return (bpf_zerocopy_free(d));

        default:
                panic("bpf_buf_free");
        }
}

static int
bpf_uiomove(struct bpf_d *d, caddr_t buf, u_int len, struct uio *uio)
{

        if (d->bd_bufmode != BPF_BUFMODE_BUFFER)
                return (EOPNOTSUPP);
        return (bpf_buffer_uiomove(d, buf, len, uio));
}

static int
bpf_ioctl_sblen(struct bpf_d *d, u_int *i)
{

        if (d->bd_bufmode != BPF_BUFMODE_BUFFER)
                return (EOPNOTSUPP);
        return (bpf_buffer_ioctl_sblen(d, i));
}

static int
bpf_ioctl_getzmax(struct thread *td, struct bpf_d *d, size_t *i)
{

        if (d->bd_bufmode != BPF_BUFMODE_ZBUF)
                return (EOPNOTSUPP);
        return (bpf_zerocopy_ioctl_getzmax(td, d, i));
}

static int
bpf_ioctl_rotzbuf(struct thread *td, struct bpf_d *d, struct bpf_zbuf *bz)
{

        if (d->bd_bufmode != BPF_BUFMODE_ZBUF)
                return (EOPNOTSUPP);
        return (bpf_zerocopy_ioctl_rotzbuf(td, d, bz));
}

static int
bpf_ioctl_setzbuf(struct thread *td, struct bpf_d *d, struct bpf_zbuf *bz)
{

        if (d->bd_bufmode != BPF_BUFMODE_ZBUF)
                return (EOPNOTSUPP);
        return (bpf_zerocopy_ioctl_setzbuf(td, d, bz));
}

/*
 * General BPF functions.
 */
static int
bpf_movein(struct uio *uio, int linktype, struct ifnet *ifp, struct mbuf **mp,
    struct sockaddr *sockp, int *hdrlen, struct bpf_insn *wfilter)
{
        const struct ieee80211_bpf_params *p;
        struct ether_header *eh;
        struct mbuf *m;
        int error;
        int len;
        int hlen;
        int slen;

        /*
         * 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.
         */
        switch (linktype) {

        case DLT_SLIP:
                sockp->sa_family = AF_INET;
                hlen = 0;
                break;

        case DLT_EN10MB:
                sockp->sa_family = AF_UNSPEC;
                /* XXX Would MAXLINKHDR be better? */
                hlen = ETHER_HDR_LEN;
                break;

        case DLT_FDDI:
                sockp->sa_family = AF_IMPLINK;
                hlen = 0;
                break;

        case DLT_RAW:
                sockp->sa_family = AF_UNSPEC;
                hlen = 0;
                break;

        case DLT_NULL:
                /*
                 * null interface types require a 4 byte pseudo header which
                 * corresponds to the address family of the packet.
                 */
                sockp->sa_family = AF_UNSPEC;
                hlen = 4;
                break;

        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.
                 */
                sockp->sa_family = AF_UNSPEC;
                hlen = 12;      /* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
                break;

        case DLT_PPP:
                sockp->sa_family = AF_UNSPEC;
                hlen = 4;       /* This should match PPP_HDRLEN */
                break;

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

        case DLT_IEEE802_11_RADIO:      /* IEEE 802.11 wireless w/ phy params */
                sockp->sa_family = AF_IEEE80211;
                sockp->sa_len = 12;     /* XXX != 0 */
                hlen = sizeof(struct ieee80211_bpf_params);
                break;

        default:
                return (EIO);
        }

        len = uio->uio_resid;

        if (len - hlen > ifp->if_mtu)
                return (EMSGSIZE);

        if ((unsigned)len > MJUM16BYTES)
                return (EIO);

        if (len <= MHLEN)
                MGETHDR(m, M_WAIT, MT_DATA);
        else if (len <= MCLBYTES)
                m = m_getcl(M_WAIT, MT_DATA, M_PKTHDR);
        else
                m = m_getjcl(M_WAIT, MT_DATA, M_PKTHDR,
#if (MJUMPAGESIZE > MCLBYTES)
                    len <= MJUMPAGESIZE ? MJUMPAGESIZE :
#endif
                    (len <= MJUM9BYTES ? MJUM9BYTES : MJUM16BYTES));
        m->m_pkthdr.len = m->m_len = len;
        m->m_pkthdr.rcvif = NULL;
        *mp = m;

        if (m->m_len < hlen) {
                error = EPERM;
                goto bad;
        }

        error = uiomove(mtod(m, u_char *), len, uio);
        if (error)
                goto bad;

        slen = bpf_filter(wfilter, mtod(m, u_char *), len, len);
        if (slen == 0) {
                error = EPERM;
                goto bad;
        }

        /* Check for multicast destination */
        switch (linktype) {
        case DLT_EN10MB:
                eh = mtod(m, struct ether_header *);
                if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
                        if (bcmp(ifp->if_broadcastaddr, eh->ether_dhost,
                            ETHER_ADDR_LEN) == 0)
                                m->m_flags |= M_BCAST;
                        else
                                m->m_flags |= M_MCAST;
                }
                break;
        }

        /*
         * Make room for link header, and copy it to sockaddr
         */
        if (hlen != 0) {
                if (sockp->sa_family == AF_IEEE80211) {
                        /*
                         * Collect true length from the parameter header
                         * NB: sockp is known to be zero'd so if we do a
                         *     short copy unspecified parameters will be
                         *     zero.
                         * NB: packet may not be aligned after stripping
                         *     bpf params
                         * XXX check ibp_vers
                         */
                        p = mtod(m, const struct ieee80211_bpf_params *);
                        hlen = p->ibp_len;
                        if (hlen > sizeof(sockp->sa_data)) {
                                error = EINVAL;
                                goto bad;
                        }
                }
                bcopy(m->m_data, sockp->sa_data, hlen);
        }
        *hdrlen = hlen;

        return (0);
bad:
        m_freem(m);
        return (error);
}

/*
 * Attach file to the bpf interface, i.e. make d listen on bp.
 */
static void
bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
{
        /*
         * 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.
         */
        BPFIF_LOCK(bp);
        d->bd_bif = bp;
        LIST_INSERT_HEAD(&bp->bif_dlist, d, bd_next);

        bpf_bpfd_cnt++;
        BPFIF_UNLOCK(bp);

        EVENTHANDLER_INVOKE(bpf_track, bp->bif_ifp, bp->bif_dlt, 1);
}

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

        bp = d->bd_bif;
        BPFIF_LOCK(bp);
        BPFD_LOCK(d);
        ifp = d->bd_bif->bif_ifp;

        /*
         * Remove d from the interface's descriptor list.
         */
        LIST_REMOVE(d, bd_next);

        bpf_bpfd_cnt--;
        d->bd_bif = NULL;
        BPFD_UNLOCK(d);
        BPFIF_UNLOCK(bp);

        EVENTHANDLER_INVOKE(bpf_track, ifp, bp->bif_dlt, 0);

        /*
         * Check if this descriptor had requested promiscuous mode.
         * If so, turn it off.
         */
        if (d->bd_promisc) {
                d->bd_promisc = 0;
                CURVNET_SET(ifp->if_vnet);
                error = ifpromisc(ifp, 0);
                CURVNET_RESTORE();
                if (error != 0 && error != ENXIO) {
                        /*
                         * ENXIO can happen if a pccard is unplugged
                         * Something is really wrong if we were able to put
                         * the driver into promiscuous mode, but can't
                         * take it out.
                         */
                        if_printf(bp->bif_ifp,
                                "bpf_detach: ifpromisc failed (%d)\n", error);
                }
        }
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
static void
bpf_dtor(void *data)
{
        struct bpf_d *d = data;

        BPFD_LOCK(d);
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
        BPFD_UNLOCK(d);
        funsetown(&d->bd_sigio);
        mtx_lock(&bpf_mtx);
        if (d->bd_bif)
                bpf_detachd(d);
        mtx_unlock(&bpf_mtx);
        selwakeuppri(&d->bd_sel, PRINET);
#ifdef MAC
        mac_bpfdesc_destroy(d);
#endif /* MAC */
        knlist_destroy(&d->bd_sel.si_note);
        bpf_freed(d);
        free(d, M_BPF);
}

/*
 * Open ethernet device.  Returns ENXIO for illegal minor device number,
 * EBUSY if file is open by another process.
 */
/* ARGSUSED */
static  int
bpfopen(struct cdev *dev, int flags, int fmt, struct thread *td)
{
        struct bpf_d *d;
        int error;

        d = malloc(sizeof(*d), M_BPF, M_WAITOK | M_ZERO);
        error = devfs_set_cdevpriv(d, bpf_dtor);
        if (error != 0) {
                free(d, M_BPF);
                return (error);
        }

        /*
         * For historical reasons, perform a one-time initialization call to
         * the buffer routines, even though we're not yet committed to a
         * particular buffer method.
         */
        bpf_buffer_init(d);
        d->bd_bufmode = BPF_BUFMODE_BUFFER;
        d->bd_sig = SIGIO;
        d->bd_direction = BPF_D_INOUT;
        d->bd_pid = td->td_proc->p_pid;
#ifdef MAC
        mac_bpfdesc_init(d);
        mac_bpfdesc_create(td->td_ucred, d);
#endif
        mtx_init(&d->bd_mtx, devtoname(dev), "bpf cdev lock", MTX_DEF);
        callout_init(&d->bd_callout, CALLOUT_MPSAFE);
        knlist_init_mtx(&d->bd_sel.si_note, &d->bd_mtx);

        return (0);
}

/*
 *  bpfread - read next chunk of packets from buffers
 */
static  int
bpfread(struct cdev *dev, struct uio *uio, int ioflag)
{
        struct bpf_d *d;
        int error;
        int non_block;
        int timed_out;

        error = devfs_get_cdevpriv((void **)&d);
        if (error != 0)
                return (error);

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

        non_block = ((ioflag & O_NONBLOCK) != 0);

        BPFD_LOCK(d);
        d->bd_pid = curthread->td_proc->p_pid;
        if (d->bd_bufmode != BPF_BUFMODE_BUFFER) {
                BPFD_UNLOCK(d);
                return (EOPNOTSUPP);
        }
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        timed_out = (d->bd_state == BPF_TIMED_OUT);
        d->bd_state = BPF_IDLE;
        /*
         * 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 == NULL) {
                if (d->bd_slen != 0) {
                        /*
                         * A packet(s) either arrived since the previous
                         * read or arrived while we were asleep.
                         */
                        if (d->bd_immediate || non_block || timed_out) {
                                /*
                                 * Rotate the buffers and return what's here
                                 * if we are in immediate mode, non-blocking
                                 * flag is set, or this descriptor timed out.
                                 */
                                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) {
                        BPFD_UNLOCK(d);
                        return (ENXIO);
                }

                if (non_block) {
                        BPFD_UNLOCK(d);
                        return (EWOULDBLOCK);
                }
                error = msleep(d, &d->bd_mtx, PRINET|PCATCH,
                     "bpf", d->bd_rtout);
                if (error == EINTR || error == ERESTART) {
                        BPFD_UNLOCK(d);
                        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) {
                                BPFD_UNLOCK(d);
                                return (0);
                        }
                        ROTATE_BUFFERS(d);
                        break;
                }
        }
        /*
         * At this point, we know we have something in the hold slot.
         */
        BPFD_UNLOCK(d);

        /*
         * 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.
         *
         * XXXRW: More synchronization needed here: what if a second thread
         * issues a read on the same fd at the same time?  Don't want this
         * getting invalidated.
         */
        error = bpf_uiomove(d, d->bd_hbuf, d->bd_hlen, uio);

        BPFD_LOCK(d);
        d->bd_fbuf = d->bd_hbuf;
        d->bd_hbuf = NULL;
        d->bd_hlen = 0;
        bpf_buf_reclaimed(d);
        BPFD_UNLOCK(d);

        return (error);
}

/*
 * If there are processes sleeping on this descriptor, wake them up.
 */
static __inline void
bpf_wakeup(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);
        if (d->bd_state == BPF_WAITING) {
                callout_stop(&d->bd_callout);
                d->bd_state = BPF_IDLE;
        }
        wakeup(d);
        if (d->bd_async && d->bd_sig && d->bd_sigio)
                pgsigio(&d->bd_sigio, d->bd_sig, 0);

        selwakeuppri(&d->bd_sel, PRINET);
        KNOTE_LOCKED(&d->bd_sel.si_note, 0);
}

static void
bpf_timed_out(void *arg)
{
        struct bpf_d *d = (struct bpf_d *)arg;

        BPFD_LOCK(d);
        if (d->bd_state == BPF_WAITING) {
                d->bd_state = BPF_TIMED_OUT;
                if (d->bd_slen != 0)
                        bpf_wakeup(d);
        }
        BPFD_UNLOCK(d);
}

static int
bpf_ready(struct bpf_d *d)
{

        BPFD_LOCK_ASSERT(d);

        if (!bpf_canfreebuf(d) && d->bd_hlen != 0)
                return (1);
        if ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
            d->bd_slen != 0)
                return (1);
        return (0);
}

static int
bpfwrite(struct cdev *dev, struct uio *uio, int ioflag)
{
        struct bpf_d *d;
        struct ifnet *ifp;
        struct mbuf *m, *mc;
        struct sockaddr dst;
        int error, hlen;

        error = devfs_get_cdevpriv((void **)&d);
        if (error != 0)
                return (error);

        d->bd_pid = curthread->td_proc->p_pid;
        d->bd_wcount++;
        if (d->bd_bif == NULL) {
                d->bd_wdcount++;
                return (ENXIO);
        }

        ifp = d->bd_bif->bif_ifp;

        if ((ifp->if_flags & IFF_UP) == 0) {
                d->bd_wdcount++;
                return (ENETDOWN);
        }

        if (uio->uio_resid == 0) {
                d->bd_wdcount++;
                return (0);
        }

        bzero(&dst, sizeof(dst));
        m = NULL;
        hlen = 0;
        error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, ifp,
            &m, &dst, &hlen, d->bd_wfilter);
        if (error) {
                d->bd_wdcount++;
                return (error);
        }
        d->bd_wfcount++;
        if (d->bd_hdrcmplt)
                dst.sa_family = pseudo_AF_HDRCMPLT;

        if (d->bd_feedback) {
                mc = m_dup(m, M_DONTWAIT);
                if (mc != NULL)
                        mc->m_pkthdr.rcvif = ifp;
                /* Set M_PROMISC for outgoing packets to be discarded. */
                if (d->bd_direction == BPF_D_INOUT)
                        m->m_flags |= M_PROMISC;
        } else
                mc = NULL;

        m->m_pkthdr.len -= hlen;
        m->m_len -= hlen;
        m->m_data += hlen;      /* XXX */

        CURVNET_SET(ifp->if_vnet);
#ifdef MAC
        BPFD_LOCK(d);
        mac_bpfdesc_create_mbuf(d, m);
        if (mc != NULL)
                mac_bpfdesc_create_mbuf(d, mc);
        BPFD_UNLOCK(d);
#endif

        error = (*ifp->if_output)(ifp, m, &dst, NULL);
        if (error)
                d->bd_wdcount++;

        if (mc != NULL) {
                if (error == 0)
                        (*ifp->if_input)(ifp, mc);
                else
                        m_freem(mc);
        }
        CURVNET_RESTORE();

        return (error);
}

/*
 * Reset a descriptor by flushing its packet buffer and clearing the receive
 * and drop counts.  This is doable for kernel-only buffers, but with
 * zero-copy buffers, we can't write to (or rotate) buffers that are
 * currently owned by userspace.  It would be nice if we could encapsulate
 * this logic in the buffer code rather than here.
 */
static void
reset_d(struct bpf_d *d)
{

        mtx_assert(&d->bd_mtx, MA_OWNED);

        if ((d->bd_hbuf != NULL) &&
            (d->bd_bufmode != BPF_BUFMODE_ZBUF || bpf_canfreebuf(d))) {
                /* Free the hold buffer. */
                d->bd_fbuf = d->bd_hbuf;
                d->bd_hbuf = NULL;
                d->bd_hlen = 0;
                bpf_buf_reclaimed(d);
        }
        if (bpf_canwritebuf(d))
                d->bd_slen = 0;
        d->bd_rcount = 0;
        d->bd_dcount = 0;
        d->bd_fcount = 0;
        d->bd_wcount = 0;
        d->bd_wfcount = 0;
        d->bd_wdcount = 0;
        d->bd_zcopy = 0;
}

/*
 *  FIONREAD            Check for read packet available.
 *  SIOCGIFADDR         Get interface address - convenient hook to driver.
 *  BIOCGBLEN           Get buffer len [for read()].
 *  BIOCSETF            Set read filter.
 *  BIOCSETFNR          Set read filter without resetting descriptor.
 *  BIOCSETWF           Set write 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
 *  BIOCGDIRECTION      Get packet direction flag
 *  BIOCSDIRECTION      Set packet direction flag
 *  BIOCLOCK            Set "locked" flag
 *  BIOCFEEDBACK        Set packet feedback mode.
 *  BIOCSETZBUF         Set current zero-copy buffer locations.
 *  BIOCGETZMAX         Get maximum zero-copy buffer size.
 *  BIOCROTZBUF         Force rotation of zero-copy buffer
 *  BIOCSETBUFMODE      Set buffer mode.
 *  BIOCGETBUFMODE      Get current buffer mode.
 */
/* ARGSUSED */
static  int
bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
    struct thread *td)
{
        struct bpf_d *d;
        int error;

        error = devfs_get_cdevpriv((void **)&d);
        if (error != 0)
                return (error);

        /*
         * Refresh PID associated with this descriptor.
         */
        BPFD_LOCK(d);
        d->bd_pid = td->td_proc->p_pid;
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
        BPFD_UNLOCK(d);

        if (d->bd_locked == 1) {
                switch (cmd) {
                case BIOCGBLEN:
                case BIOCFLUSH:
                case BIOCGDLT:
                case BIOCGDLTLIST:
                case BIOCGETIF:
                case BIOCGRTIMEOUT:
                case BIOCGSTATS:
                case BIOCVERSION:
                case BIOCGRSIG:
                case BIOCGHDRCMPLT:
                case BIOCFEEDBACK:
                case FIONREAD:
                case BIOCLOCK:
                case BIOCSRTIMEOUT:
                case BIOCIMMEDIATE:
                case TIOCGPGRP:
                case BIOCROTZBUF:
                        break;
                default:
                        return (EPERM);
                }
        }
        CURVNET_SET(TD_TO_VNET(td));
        switch (cmd) {

        default:
                error = EINVAL;
                break;

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

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

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

        case SIOCGIFADDR:
                {
                        struct ifnet *ifp;

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

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

        /*
         * Set buffer length.
         */
        case BIOCSBLEN:
                error = bpf_ioctl_sblen(d, (u_int *)addr);
                break;

        /*
         * Set link layer read filter.
         */
        case BIOCSETF:
        case BIOCSETFNR:
        case BIOCSETWF:
                error = bpf_setf(d, (struct bpf_program *)addr, cmd);
                break;

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

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

        /*
         * Get current data link type.
         */
        case BIOCGDLT:
                if (d->bd_bif == NULL)
                        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);
                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 == NULL)
                        error = EINVAL;
                else {
                        struct ifnet *const ifp = d->bd_bif->bif_ifp;
                        struct ifreq *const ifr = (struct ifreq *)addr;

                        strlcpy(ifr->ifr_name, ifp->if_xname,
                            sizeof(ifr->ifr_name));
                }
                break;

        /*
         * Set interface.
         */
        case BIOCSETIF:
                error = bpf_setif(d, (struct ifreq *)addr);
                break;

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

                        /*
                         * 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 timeval *tv = (struct 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;

                        /* XXXCSJP overflow */
                        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 packet direction flag
         */
        case BIOCGDIRECTION:
                *(u_int *)addr = d->bd_direction;
                break;

        /*
         * Set packet direction flag
         */
        case BIOCSDIRECTION:
                {
                        u_int   direction;

                        direction = *(u_int *)addr;
                        switch (direction) {
                        case BPF_D_IN:
                        case BPF_D_INOUT:
                        case BPF_D_OUT:
                                d->bd_direction = direction;
                                break;
                        default:
                                error = EINVAL;
                        }
                }
                break;

        case BIOCFEEDBACK:
                d->bd_feedback = *(u_int *)addr;
                break;

        case BIOCLOCK:
                d->bd_locked = 1;
                break;

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

        case FIOASYNC:          /* Send signal on receive packets */
                d->bd_async = *(int *)addr;
                break;

        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;

        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;

        case BIOCGETBUFMODE:
                *(u_int *)addr = d->bd_bufmode;
                break;

        case BIOCSETBUFMODE:
                /*
                 * Allow the buffering mode to be changed as long as we
                 * haven't yet committed to a particular mode.  Our
                 * definition of commitment, for now, is whether or not a
                 * buffer has been allocated or an interface attached, since
                 * that's the point where things get tricky.
                 */
                switch (*(u_int *)addr) {
                case BPF_BUFMODE_BUFFER:
                        break;

                case BPF_BUFMODE_ZBUF:
                        if (bpf_zerocopy_enable)
                                break;
                        /* FALLSTHROUGH */

                default:
                        return (EINVAL);
                }

                BPFD_LOCK(d);
                if (d->bd_sbuf != NULL || d->bd_hbuf != NULL ||
                    d->bd_fbuf != NULL || d->bd_bif != NULL) {
                        BPFD_UNLOCK(d);
                        return (EBUSY);
                }
                d->bd_bufmode = *(u_int *)addr;
                BPFD_UNLOCK(d);
                break;

        case BIOCGETZMAX:
                return (bpf_ioctl_getzmax(td, d, (size_t *)addr));

        case BIOCSETZBUF:
                return (bpf_ioctl_setzbuf(td, d, (struct bpf_zbuf *)addr));

        case BIOCROTZBUF:
                return (bpf_ioctl_rotzbuf(td, d, (struct bpf_zbuf *)addr));
        }
        CURVNET_RESTORE();
        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, struct bpf_program *fp, u_long cmd)
{
        struct bpf_insn *fcode, *old;
        u_int wfilter, flen, size;
#ifdef BPF_JITTER
        bpf_jit_filter *ofunc;
#endif

        if (cmd == BIOCSETWF) {
                old = d->bd_wfilter;
                wfilter = 1;
#ifdef BPF_JITTER
                ofunc = NULL;
#endif
        } else {
                wfilter = 0;
                old = d->bd_rfilter;
#ifdef BPF_JITTER
                ofunc = d->bd_bfilter;
#endif
        }
        if (fp->bf_insns == NULL) {
                if (fp->bf_len != 0)
                        return (EINVAL);
                BPFD_LOCK(d);
                if (wfilter)
                        d->bd_wfilter = NULL;
                else {
                        d->bd_rfilter = NULL;
#ifdef BPF_JITTER
                        d->bd_bfilter = NULL;
#endif
                        if (cmd == BIOCSETF)
                                reset_d(d);
                }
                BPFD_UNLOCK(d);
                if (old != NULL)
                        free((caddr_t)old, M_BPF);
#ifdef BPF_JITTER
                if (ofunc != NULL)
                        bpf_destroy_jit_filter(ofunc);
#endif
                return (0);
        }
        flen = fp->bf_len;
        if (flen > bpf_maxinsns)
                return (EINVAL);

        size = flen * sizeof(*fp->bf_insns);
        fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
        if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
            bpf_validate(fcode, (int)flen)) {
                BPFD_LOCK(d);
                if (wfilter)
                        d->bd_wfilter = fcode;
                else {
                        d->bd_rfilter = fcode;
#ifdef BPF_JITTER
                        d->bd_bfilter = bpf_jitter(fcode, flen);
#endif
                        if (cmd == BIOCSETF)
                                reset_d(d);
                }
                BPFD_UNLOCK(d);
                if (old != NULL)
                        free((caddr_t)old, M_BPF);
#ifdef BPF_JITTER
                if (ofunc != NULL)
                        bpf_destroy_jit_filter(ofunc);
#endif

                return (0);
        }
        free((caddr_t)fcode, M_BPF);
        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, struct ifreq *ifr)
{
        struct bpf_if *bp;
        struct ifnet *theywant;

        theywant = ifunit(ifr->ifr_name);
        if (theywant == NULL || theywant->if_bpf == NULL)
                return (ENXIO);

        bp = theywant->if_bpf;

        /*
         * Behavior here depends on the buffering model.  If we're using
         * kernel memory buffers, then we can allocate them here.  If we're
         * using zero-copy, then the user process must have registered
         * buffers by the time we get here.  If not, return an error.
         *
         * XXXRW: There are locking issues here with multi-threaded use: what
         * if two threads try to set the interface at once?
         */
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
                if (d->bd_sbuf == NULL)
                        bpf_buffer_alloc(d);
                KASSERT(d->bd_sbuf != NULL, ("bpf_setif: bd_sbuf NULL"));
                break;

        case BPF_BUFMODE_ZBUF:
                if (d->bd_sbuf == NULL)
                        return (EINVAL);
                break;

        default:
                panic("bpf_setif: bufmode %d", d->bd_bufmode);
        }
        if (bp != d->bd_bif) {
                if (d->bd_bif)
                        /*
                         * Detach if attached to something else.
                         */
                        bpf_detachd(d);

                bpf_attachd(d, bp);
        }
        BPFD_LOCK(d);
        reset_d(d);
        BPFD_UNLOCK(d);
        return (0);
}

/*
 * Support for select() and poll() system calls
 *
 * Return true iff the specific operation will not block indefinitely.
 * Otherwise, return false but make a note that a selwakeup() must be done.
 */
static int
bpfpoll(struct cdev *dev, int events, struct thread *td)
{
        struct bpf_d *d;
        int revents;

        if (devfs_get_cdevpriv((void **)&d) != 0 || d->bd_bif == NULL)
                return (events &
                    (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM));

        /*
         * Refresh PID associated with this descriptor.
         */
        revents = events & (POLLOUT | POLLWRNORM);
        BPFD_LOCK(d);
        d->bd_pid = td->td_proc->p_pid;
        if (events & (POLLIN | POLLRDNORM)) {
                if (bpf_ready(d))
                        revents |= events & (POLLIN | POLLRDNORM);
                else {
                        selrecord(td, &d->bd_sel);
                        /* Start the read timeout if necessary. */
                        if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
                                callout_reset(&d->bd_callout, d->bd_rtout,
                                    bpf_timed_out, d);
                                d->bd_state = BPF_WAITING;
                        }
                }
        }
        BPFD_UNLOCK(d);
        return (revents);
}

/*
 * Support for kevent() system call.  Register EVFILT_READ filters and
 * reject all others.
 */
int
bpfkqfilter(struct cdev *dev, struct knote *kn)
{
        struct bpf_d *d;

        if (devfs_get_cdevpriv((void **)&d) != 0 ||
            kn->kn_filter != EVFILT_READ)
                return (1);

        /*
         * Refresh PID associated with this descriptor.
         */
        BPFD_LOCK(d);
        d->bd_pid = curthread->td_proc->p_pid;
        kn->kn_fop = &bpfread_filtops;
        kn->kn_hook = d;
        knlist_add(&d->bd_sel.si_note, kn, 1);
        BPFD_UNLOCK(d);

        return (0);
}

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

        knlist_remove(&d->bd_sel.si_note, kn, 0);
}

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

        BPFD_LOCK_ASSERT(d);
        ready = bpf_ready(d);
        if (ready) {
                kn->kn_data = d->bd_slen;
                if (d->bd_hbuf)
                        kn->kn_data += d->bd_hlen;
        }
        else if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
                callout_reset(&d->bd_callout, d->bd_rtout,
                    bpf_timed_out, d);
                d->bd_state = BPF_WAITING;
        }

        return (ready);
}

/*
 * Incoming linkage from device drivers.  Process the packet pkt, of length
 * pktlen, which is stored in a contiguous buffer.  The packet is parsed
 * by each process' filter, and if accepted, stashed into the corresponding
 * buffer.
 */
void
bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
{
        struct bpf_d *d;
#ifdef BPF_JITTER
        bpf_jit_filter *bf;
#endif
        u_int slen;
        int gottime;
        struct timeval tv;

        gottime = 0;
        BPFIF_LOCK(bp);
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                BPFD_LOCK(d);
                ++d->bd_rcount;
                /*
                 * NB: We dont call BPF_CHECK_DIRECTION() here since there is no
                 * way for the caller to indiciate to us whether this packet
                 * is inbound or outbound.  In the bpf_mtap() routines, we use
                 * the interface pointers on the mbuf to figure it out.
                 */
#ifdef BPF_JITTER
                bf = bpf_jitter_enable != 0 ? d->bd_bfilter : NULL;
                if (bf != NULL)
                        slen = (*(bf->func))(pkt, pktlen, pktlen);
                else
#endif
                slen = bpf_filter(d->bd_rfilter, pkt, pktlen, pktlen);
                if (slen != 0) {
                        d->bd_fcount++;
                        if (!gottime) {
                                microtime(&tv);
                                gottime = 1;
                        }
#ifdef MAC
                        if (mac_bpfdesc_check_receive(d, bp->bif_ifp) == 0)
#endif
                                catchpacket(d, pkt, pktlen, slen,
                                    bpf_append_bytes, &tv);
                }
                BPFD_UNLOCK(d);
        }
        BPFIF_UNLOCK(bp);
}

#define BPF_CHECK_DIRECTION(d, r, i)                            \
            (((d)->bd_direction == BPF_D_IN && (r) != (i)) ||   \
            ((d)->bd_direction == BPF_D_OUT && (r) == (i)))

/*
 * Incoming linkage from device drivers, when packet is in an mbuf chain.
 */
void
bpf_mtap(struct bpf_if *bp, struct mbuf *m)
{
        struct bpf_d *d;
#ifdef BPF_JITTER
        bpf_jit_filter *bf;
#endif
        u_int pktlen, slen;
        int gottime;
        struct timeval tv;

        /* Skip outgoing duplicate packets. */
        if ((m->m_flags & M_PROMISC) != 0 && m->m_pkthdr.rcvif == NULL) {
                m->m_flags &= ~M_PROMISC;
                return;
        }

        gottime = 0;

        pktlen = m_length(m, NULL);

        BPFIF_LOCK(bp);
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (BPF_CHECK_DIRECTION(d, m->m_pkthdr.rcvif, bp->bif_ifp))
                        continue;
                BPFD_LOCK(d);
                ++d->bd_rcount;
#ifdef BPF_JITTER
                bf = bpf_jitter_enable != 0 ? d->bd_bfilter : NULL;
                /* XXX We cannot handle multiple mbufs. */
                if (bf != NULL && m->m_next == NULL)
                        slen = (*(bf->func))(mtod(m, u_char *), pktlen, pktlen);
                else
#endif
                slen = bpf_filter(d->bd_rfilter, (u_char *)m, pktlen, 0);
                if (slen != 0) {
                        d->bd_fcount++;
                        if (!gottime) {
                                microtime(&tv);
                                gottime = 1;
                        }
#ifdef MAC
                        if (mac_bpfdesc_check_receive(d, bp->bif_ifp) == 0)
#endif
                                catchpacket(d, (u_char *)m, pktlen, slen,
                                    bpf_append_mbuf, &tv);
                }
                BPFD_UNLOCK(d);
        }
        BPFIF_UNLOCK(bp);
}

/*
 * Incoming linkage from device drivers, when packet is in
 * an mbuf chain and to be prepended by a contiguous header.
 */
void
bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m)
{
        struct mbuf mb;
        struct bpf_d *d;
        u_int pktlen, slen;
        int gottime;
        struct timeval tv;

        /* Skip outgoing duplicate packets. */
        if ((m->m_flags & M_PROMISC) != 0 && m->m_pkthdr.rcvif == NULL) {
                m->m_flags &= ~M_PROMISC;
                return;
        }

        gottime = 0;

        pktlen = m_length(m, NULL);
        /*
         * Craft on-stack mbuf suitable for passing to bpf_filter.
         * Note that we cut corners here; we only setup what's
         * absolutely needed--this mbuf should never go anywhere else.
         */
        mb.m_next = m;
        mb.m_data = data;
        mb.m_len = dlen;
        pktlen += dlen;

        BPFIF_LOCK(bp);
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (BPF_CHECK_DIRECTION(d, m->m_pkthdr.rcvif, bp->bif_ifp))
                        continue;
                BPFD_LOCK(d);
                ++d->bd_rcount;
                slen = bpf_filter(d->bd_rfilter, (u_char *)&mb, pktlen, 0);
                if (slen != 0) {
                        d->bd_fcount++;
                        if (!gottime) {
                                microtime(&tv);
                                gottime = 1;
                        }
#ifdef MAC
                        if (mac_bpfdesc_check_receive(d, bp->bif_ifp) == 0)
#endif
                                catchpacket(d, (u_char *)&mb, pktlen, slen,
                                    bpf_append_mbuf, &tv);
                }
                BPFD_UNLOCK(d);
        }
        BPFIF_UNLOCK(bp);
}

#undef  BPF_CHECK_DIRECTION

/*
 * Move the packet data from interface memory (pkt) into the
 * store buffer.  "cpfn" is the routine called to do the actual data
 * transfer.  bcopy is passed in to copy contiguous chunks, while
 * bpf_append_mbuf 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)(struct bpf_d *, caddr_t, u_int, void *, u_int),
    struct timeval *tv)
{
        struct bpf_hdr hdr;
        int totlen, curlen;
        int hdrlen = d->bd_bif->bif_hdrlen;
        int do_wakeup = 0;

        BPFD_LOCK_ASSERT(d);

        /*
         * Detect whether user space has released a buffer back to us, and if
         * so, move it from being a hold buffer to a free buffer.  This may
         * not be the best place to do it (for example, we might only want to
         * run this check if we need the space), but for now it's a reliable
         * spot to do it.
         */
        if (d->bd_fbuf == NULL && bpf_canfreebuf(d)) {
                d->bd_fbuf = d->bd_hbuf;
                d->bd_hbuf = NULL;
                d->bd_hlen = 0;
                bpf_buf_reclaimed(d);
        }

        /*
         * 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.
         *
         * Drop the packet if there's no room and no hope of room
         * If the packet would overflow the storage buffer or the storage
         * buffer is considered immutable by the buffer model, try to rotate
         * the buffer and wakeup pending processes.
         */
        curlen = BPF_WORDALIGN(d->bd_slen);
        if (curlen + totlen > d->bd_bufsize || !bpf_canwritebuf(d)) {
                if (d->bd_fbuf == NULL) {
                        /*
                         * There's no room in the store buffer, and no
                         * prospect of room, so drop the packet.  Notify the
                         * buffer model.
                         */
                        bpf_buffull(d);
                        ++d->bd_dcount;
                        return;
                }
                ROTATE_BUFFERS(d);
                do_wakeup = 1;
                curlen = 0;
        } else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT)
                /*
                 * Immediate mode is set, or the read timeout has already
                 * expired during a select call.  A packet arrived, so the
                 * reader should be woken up.
                 */
                do_wakeup = 1;

        /*
         * Append the bpf header.  Note we append the actual header size, but
         * move forward the length of the header plus padding.
         */
        bzero(&hdr, sizeof(hdr));
        hdr.bh_tstamp = *tv;
        hdr.bh_datalen = pktlen;
        hdr.bh_hdrlen = hdrlen;
        hdr.bh_caplen = totlen - hdrlen;
        bpf_append_bytes(d, d->bd_sbuf, curlen, &hdr, sizeof(hdr));

        /*
         * Copy the packet data into the store buffer and update its length.
         */
        (*cpfn)(d, d->bd_sbuf, curlen + hdrlen, pkt, hdr.bh_caplen);
        d->bd_slen = curlen + totlen;

        if (do_wakeup)
                bpf_wakeup(d);
}

/*
 * 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.
         */
        bpf_free(d);
        if (d->bd_rfilter) {
                free((caddr_t)d->bd_rfilter, M_BPF);
#ifdef BPF_JITTER
                bpf_destroy_jit_filter(d->bd_bfilter);
#endif
        }
        if (d->bd_wfilter)
                free((caddr_t)d->bd_wfilter, M_BPF);
        mtx_destroy(&d->bd_mtx);
}

/*
 * Attach an interface to bpf.  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)
{

        bpfattach2(ifp, dlt, hdrlen, &ifp->if_bpf);
}

/*
 * Attach an interface to bpf.  ifp is a pointer to the structure
 * defining the interface to be attached, dlt is the link layer type,
 * and hdrlen is the fixed size of the link header (variable length
 * headers are not yet supporrted).
 */
void
bpfattach2(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
{
        struct bpf_if *bp;

        bp = malloc(sizeof(*bp), M_BPF, M_NOWAIT | M_ZERO);
        if (bp == NULL)
                panic("bpfattach");

        LIST_INIT(&bp->bif_dlist);
        bp->bif_ifp = ifp;
        bp->bif_dlt = dlt;
        mtx_init(&bp->bif_mtx, "bpf interface lock", NULL, MTX_DEF);
        KASSERT(*driverp == NULL, ("bpfattach2: driverp already initialized"));
        *driverp = bp;

        mtx_lock(&bpf_mtx);
        LIST_INSERT_HEAD(&bpf_iflist, bp, bif_next);
        mtx_unlock(&bpf_mtx);

        /*
         * 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->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;

        if (bootverbose)
                if_printf(ifp, "bpf attached\n");
}

/*
 * 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;
        struct bpf_d    *d;

        /* Locate BPF interface information */
        mtx_lock(&bpf_mtx);
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                if (ifp == bp->bif_ifp)
                        break;
        }

        /* Interface wasn't attached */
        if ((bp == NULL) || (bp->bif_ifp == NULL)) {
                mtx_unlock(&bpf_mtx);
                printf("bpfdetach: %s was not attached\n", ifp->if_xname);
                return;
        }

        LIST_REMOVE(bp, bif_next);
        mtx_unlock(&bpf_mtx);

        while ((d = LIST_FIRST(&bp->bif_dlist)) != NULL) {
                bpf_detachd(d);
                BPFD_LOCK(d);
                bpf_wakeup(d);
                BPFD_UNLOCK(d);
        }

        mtx_destroy(&bp->bif_mtx);
        free(bp, M_BPF);
}

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

        ifp = d->bd_bif->bif_ifp;
        n = 0;
        error = 0;
        mtx_lock(&bpf_mtx);
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                if (bp->bif_ifp != ifp)
                        continue;
                if (bfl->bfl_list != NULL) {
                        if (n >= bfl->bfl_len) {
                                mtx_unlock(&bpf_mtx);
                                return (ENOMEM);
                        }
                        error = copyout(&bp->bif_dlt,
                            bfl->bfl_list + n, sizeof(u_int));
                }
                n++;
        }
        mtx_unlock(&bpf_mtx);
        bfl->bfl_len = n;
        return (error);
}

/*
 * Set the data link type of a BPF instance.
 */
static int
bpf_setdlt(struct bpf_d *d, u_int 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;
        mtx_lock(&bpf_mtx);
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
                        break;
        }
        mtx_unlock(&bpf_mtx);
        if (bp != NULL) {
                opromisc = d->bd_promisc;
                bpf_detachd(d);
                bpf_attachd(d, bp);
                BPFD_LOCK(d);
                reset_d(d);
                BPFD_UNLOCK(d);
                if (opromisc) {
                        error = ifpromisc(bp->bif_ifp, 1);
                        if (error)
                                if_printf(bp->bif_ifp,
                                        "bpf_setdlt: ifpromisc failed (%d)\n",
                                        error);
                        else
                                d->bd_promisc = 1;
                }
        }
        return (bp == NULL ? EINVAL : 0);
}

static void
bpf_drvinit(void *unused)
{
        struct cdev *dev;

        mtx_init(&bpf_mtx, "bpf global lock", NULL, MTX_DEF);
        LIST_INIT(&bpf_iflist);

        dev = make_dev(&bpf_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "bpf");
        /* For compatibility */
        make_dev_alias(dev, "bpf0");
}

/*
 * Zero out the various packet counters associated with all of the bpf
 * descriptors.  At some point, we will probably want to get a bit more
 * granular and allow the user to specify descriptors to be zeroed.
 */
static void
bpf_zero_counters(void)
{
        struct bpf_if *bp;
        struct bpf_d *bd;

        mtx_lock(&bpf_mtx);
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                BPFIF_LOCK(bp);
                LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
                        BPFD_LOCK(bd);
                        bd->bd_rcount = 0;
                        bd->bd_dcount = 0;
                        bd->bd_fcount = 0;
                        bd->bd_wcount = 0;
                        bd->bd_wfcount = 0;
                        bd->bd_zcopy = 0;
                        BPFD_UNLOCK(bd);
                }
                BPFIF_UNLOCK(bp);
        }
        mtx_unlock(&bpf_mtx);
}

static void
bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
{

        bzero(d, sizeof(*d));
        BPFD_LOCK_ASSERT(bd);
        d->bd_structsize = sizeof(*d);
        d->bd_immediate = bd->bd_immediate;
        d->bd_promisc = bd->bd_promisc;
        d->bd_hdrcmplt = bd->bd_hdrcmplt;
        d->bd_direction = bd->bd_direction;
        d->bd_feedback = bd->bd_feedback;
        d->bd_async = bd->bd_async;
        d->bd_rcount = bd->bd_rcount;
        d->bd_dcount = bd->bd_dcount;
        d->bd_fcount = bd->bd_fcount;
        d->bd_sig = bd->bd_sig;
        d->bd_slen = bd->bd_slen;
        d->bd_hlen = bd->bd_hlen;
        d->bd_bufsize = bd->bd_bufsize;
        d->bd_pid = bd->bd_pid;
        strlcpy(d->bd_ifname,
            bd->bd_bif->bif_ifp->if_xname, IFNAMSIZ);
        d->bd_locked = bd->bd_locked;
        d->bd_wcount = bd->bd_wcount;
        d->bd_wdcount = bd->bd_wdcount;
        d->bd_wfcount = bd->bd_wfcount;
        d->bd_zcopy = bd->bd_zcopy;
        d->bd_bufmode = bd->bd_bufmode;
}

static int
bpf_stats_sysctl(SYSCTL_HANDLER_ARGS)
{
        struct xbpf_d *xbdbuf, *xbd, zerostats;
        int index, error;
        struct bpf_if *bp;
        struct bpf_d *bd;

        /*
         * XXX This is not technically correct. It is possible for non
         * privileged users to open bpf devices. It would make sense
         * if the users who opened the devices were able to retrieve
         * the statistics for them, too.
         */
        error = priv_check(req->td, PRIV_NET_BPF);
        if (error)
                return (error);
        /*
         * Check to see if the user is requesting that the counters be
         * zeroed out.  Explicitly check that the supplied data is zeroed,
         * as we aren't allowing the user to set the counters currently.
         */
        if (req->newptr != NULL) {
                if (req->newlen != sizeof(zerostats))
                        return (EINVAL);
                bzero(&zerostats, sizeof(zerostats));
                xbd = req->newptr;
                if (bcmp(xbd, &zerostats, sizeof(*xbd)) != 0)
                        return (EINVAL);
                bpf_zero_counters();
                return (0);
        }
        if (req->oldptr == NULL)
                return (SYSCTL_OUT(req, 0, bpf_bpfd_cnt * sizeof(*xbd)));
        if (bpf_bpfd_cnt == 0)
                return (SYSCTL_OUT(req, 0, 0));
        xbdbuf = malloc(req->oldlen, M_BPF, M_WAITOK);
        mtx_lock(&bpf_mtx);
        if (req->oldlen < (bpf_bpfd_cnt * sizeof(*xbd))) {
                mtx_unlock(&bpf_mtx);
                free(xbdbuf, M_BPF);
                return (ENOMEM);
        }
        index = 0;
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                BPFIF_LOCK(bp);
                LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
                        xbd = &xbdbuf[index++];
                        BPFD_LOCK(bd);
                        bpfstats_fill_xbpf(xbd, bd);
                        BPFD_UNLOCK(bd);
                }
                BPFIF_UNLOCK(bp);
        }
        mtx_unlock(&bpf_mtx);
        error = SYSCTL_OUT(req, xbdbuf, index * sizeof(*xbd));
        free(xbdbuf, M_BPF);
        return (error);
}

SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,bpf_drvinit,NULL);

#else /* !DEV_BPF && !NETGRAPH_BPF */
/*
 * NOP stubs to allow bpf-using drivers to load and function.
 *
 * A 'better' implementation would allow the core bpf functionality
 * to be loaded at runtime.
 */
static struct bpf_if bp_null;

void
bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
{
}

void
bpf_mtap(struct bpf_if *bp, struct mbuf *m)
{
}

void
bpf_mtap2(struct bpf_if *bp, void *d, u_int l, struct mbuf *m)
{
}

void
bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
{

        bpfattach2(ifp, dlt, hdrlen, &ifp->if_bpf);
}

void
bpfattach2(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
{

        *driverp = &bp_null;
}

void
bpfdetach(struct ifnet *ifp)
{
}

u_int
bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
{
        return -1;      /* "no filter" behaviour */
}

int
bpf_validate(const struct bpf_insn *f, int len)
{
        return 0;               /* false */
}

#endif /* !DEV_BPF && !NETGRAPH_BPF */