/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1990, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
 *
 * 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. 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.
 */

#include <sys/cdefs.h>
#include "opt_bpf.h"
#include "opt_netgraph.h"

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.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/sysent.h>
#include <sys/systm.h>

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

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_vlan_var.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 <sys/kernel.h>
#include <sys/sysctl.h>

#include <security/mac/mac_framework.h>

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

struct bpf_if {
        struct bpfd_list        bif_dlist;      /* list of all interfaces */
        LIST_ENTRY(bpf_if)      bif_next;       /* descriptor list */
        u_int           bif_dlt;        /* link layer type */
        u_int           bif_hdrlen;     /* length of link header */
        volatile u_int  bif_refcnt;
        struct bpfd_list bif_wlist;     /* writer-only list */
        const struct bif_methods        *bif_methods;
        void            *bif_softc;
        const char      *bif_name;
        struct epoch_context epoch_ctx;
};

/* See bpf_peers_present() in bpf.h. */
_Static_assert(offsetof(struct bpf_if, bif_dlist) == 0,
    "bpf_if shall start with bif_dlist");

static inline void
bif_attachd(struct bpf_if *bp)
{
        if (bp->bif_methods->bif_attachd != NULL)
                bp->bif_methods->bif_attachd(bp->bif_softc);
}

static inline void
bif_detachd(struct bpf_if *bp)
{
        if (bp->bif_methods->bif_detachd != NULL)
                bp->bif_methods->bif_detachd(bp->bif_softc);
}

static inline uint32_t
bif_wrsize(struct bpf_if *bp)
{
        if (bp->bif_methods->bif_wrsize != NULL)
                return (bp->bif_methods->bif_wrsize(bp->bif_softc));
        else
                return (0);
}

static inline int
bif_promisc(struct bpf_if *bp, bool on)
{
        if (bp->bif_methods->bif_promisc != NULL)
                return (bp->bif_methods->bif_promisc(bp->bif_softc, on));
        else
                return (0);
}

#ifdef MAC
static inline int
bif_mac_check_receive(struct bpf_if *bp, struct bpf_d *d)
{
        if (bp->bif_methods->bif_mac_check_receive != NULL)
                return (bp->bif_methods->bif_mac_check_receive(bp->bif_softc,
                    d));
        else
                return (0);
}
#endif

/*
 * XXXGL: Once we migrate to tapping KPI that would specify packet direction
 * we no longer need bif_chkdir method.
 */
static inline bool
bpf_chkdir(struct bpf_d *d, struct mbuf *m)
{
        return (d->bd_bif->bif_methods->bif_chkdir(d->bd_bif->bif_softc, m,
            d->bd_direction));
}

struct bpf_program_buffer {
        struct epoch_context    epoch_ctx;
#ifdef BPF_JITTER
        bpf_jit_filter          *func;
#endif
        void                    *buffer[0];
};

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

#define PRINET  26                      /* interruptible */
#define BPF_PRIO_MAX    7

#define SIZEOF_BPF_HDR(type)    \
    (offsetof(type, bh_hdrlen) + sizeof(((type *)0)->bh_hdrlen))

#ifdef COMPAT_FREEBSD32
#include <sys/mount.h>
#include <compat/freebsd32/freebsd32.h>
#define BPF_ALIGNMENT32 sizeof(int32_t)
#define BPF_WORDALIGN32(x) roundup2(x, BPF_ALIGNMENT32)

#ifndef BURN_BRIDGES
/*
 * 32-bit version of structure prepended to each packet.  We use this header
 * instead of the standard one for 32-bit streams.  We mark the a stream as
 * 32-bit the first time we see a 32-bit compat ioctl request.
 */
struct bpf_hdr32 {
        struct timeval32 bh_tstamp;     /* time stamp */
        uint32_t        bh_caplen;      /* length of captured portion */
        uint32_t        bh_datalen;     /* original length of packet */
        uint16_t        bh_hdrlen;      /* length of bpf header (this struct
                                           plus alignment padding) */
};
#endif

struct bpf_program32 {
        u_int bf_len;
        uint32_t bf_insns;
};

struct bpf_dltlist32 {
        u_int   bfl_len;
        u_int   bfl_list;
};

#define BIOCSETF32      _IOW('B', 103, struct bpf_program32)
#define BIOCSRTIMEOUT32 _IOW('B', 109, struct timeval32)
#define BIOCGRTIMEOUT32 _IOR('B', 110, struct timeval32)
#define BIOCGDLTLIST32  _IOWR('B', 121, struct bpf_dltlist32)
#define BIOCSETWF32     _IOW('B', 123, struct bpf_program32)
#define BIOCSETFNR32    _IOW('B', 130, struct bpf_program32)
#endif

#define BPF_LOCK()              sx_xlock(&bpf_sx)
#define BPF_UNLOCK()            sx_xunlock(&bpf_sx)
#define BPF_LOCK_ASSERT()       sx_assert(&bpf_sx, SA_XLOCKED)
/*
 * 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).
 */
VNET_DEFINE_STATIC(LIST_HEAD(, bpf_if), bpf_iflist) = LIST_HEAD_INITIALIZER();
#define V_bpf_iflist    VNET(bpf_iflist)
static struct sx        bpf_sx;         /* bpf global lock */

static void     bpfif_ref(struct bpf_if *);
static void     bpfif_rele(struct bpf_if *);

static void     bpfd_ref(struct bpf_d *);
static void     bpfd_rele(struct bpf_d *);
static int      bpf_attachd(struct bpf_d *d, struct bpf_if *);
static void     bpf_detachd(struct bpf_d *, bool);
static void     bpfd_free(epoch_context_t);
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 bintime *);
static void     reset_d(struct bpf_d *);
static int      bpf_getiflist(struct bpf_iflist *);
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 int      filt_bpfwrite(struct knote *, long);
static void     bpf_drvinit(void *);
static int      bpf_stats_sysctl(SYSCTL_HANDLER_ARGS);

SYSCTL_NODE(_net, OID_AUTO, bpf, CTLFLAG_RW | CTLFLAG_MPSAFE, 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");
static SYSCTL_NODE(_net_bpf, OID_AUTO, stats,
    CTLFLAG_VNET | CTLFLAG_MPSAFE | CTLFLAG_RW,
    bpf_stats_sysctl, "bpf statistics portal");

VNET_DEFINE_STATIC(int, bpf_optimize_writers) = 0;
#define V_bpf_optimize_writers VNET(bpf_optimize_writers)
SYSCTL_INT(_net_bpf, OID_AUTO, optimize_writers, CTLFLAG_VNET | CTLFLAG_RWTUN,
    &VNET_NAME(bpf_optimize_writers), 0,
    "Do not send packets until BPF program is set");

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 const struct filterops bpfread_filtops = {
        .f_isfd = 1,
        .f_detach = filt_bpfdetach,
        .f_event = filt_bpfread,
        .f_copy = knote_triv_copy,
};

static const struct filterops bpfwrite_filtops = {
        .f_isfd = 1,
        .f_detach = filt_bpfdetach,
        .f_event = filt_bpfwrite,
        .f_copy = knote_triv_copy,
};

/*
 * LOCKING MODEL USED BY BPF
 *
 * Locks:
 * 1) global lock (BPF_LOCK). Sx, used to protect some global counters,
 * every bpf_iflist changes, serializes ioctl access to bpf descriptors.
 * 2) Descriptor lock. Mutex, used to protect BPF buffers and various
 * structure fields used by bpf_*tap* code.
 *
 * Lock order: global lock, then descriptor lock.
 *
 * There are several possible consumers:
 *
 * 1. The kernel registers interface pointer with bpfattach().
 * Each call allocates new bpf_if structure, references ifnet pointer
 * and links bpf_if into bpf_iflist chain. This is protected with global
 * lock.
 *
 * 2. An userland application uses ioctl() call to bpf_d descriptor.
 * All such call are serialized with global lock. BPF filters can be
 * changed, but pointer to old filter will be freed using NET_EPOCH_CALL().
 * Thus it should be safe for bpf_tap/bpf_mtap* code to do access to
 * filter pointers, even if change will happen during bpf_tap execution.
 * Destroying of bpf_d descriptor also is doing using NET_EPOCH_CALL().
 *
 * 3. An userland application can write packets into bpf_d descriptor.
 * There we need to be sure, that ifnet won't disappear during bpfwrite().
 *
 * 4. The kernel invokes bpf_tap/bpf_mtap* functions. The access to
 * bif_dlist is protected with net_epoch_preempt section. So, it should
 * be safe to make access to bpf_d descriptor inside the section.
 *
 * 5. The kernel invokes bpfdetach() on interface destroying. All lists
 * are modified with global lock held and actual free() is done using
 * NET_EPOCH_CALL().
 */

static void
bpfif_free(epoch_context_t ctx)
{
        struct bpf_if *bp;

        bp = __containerof(ctx, struct bpf_if, epoch_ctx);
        free(bp, M_BPF);
}

static void
bpfif_ref(struct bpf_if *bp)
{

        refcount_acquire(&bp->bif_refcnt);
}

static void
bpfif_rele(struct bpf_if *bp)
{

        if (!refcount_release(&bp->bif_refcnt))
                return;
        NET_EPOCH_CALL(bpfif_free, &bp->epoch_ctx);
}

static void
bpfd_ref(struct bpf_d *d)
{

        refcount_acquire(&d->bd_refcnt);
}

static void
bpfd_rele(struct bpf_d *d)
{

        if (!refcount_release(&d->bd_refcnt))
                return;
        NET_EPOCH_CALL(bpfd_free, &d->epoch_ctx);
}

static struct bpf_program_buffer*
bpf_program_buffer_alloc(size_t size, int flags)
{

        return (malloc(sizeof(struct bpf_program_buffer) + size,
            M_BPF, flags));
}

static void
bpf_program_buffer_free(epoch_context_t ctx)
{
        struct bpf_program_buffer *ptr;

        ptr = __containerof(ctx, struct bpf_program_buffer, epoch_ctx);
#ifdef BPF_JITTER
        if (ptr->func != NULL)
                bpf_destroy_jit_filter(ptr->func);
#endif
        free(ptr, M_BPF);
}

/*
 * 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:
                counter_u64_add(d->bd_zcopy, 1);
                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:
                counter_u64_add(d->bd_zcopy, 1);
                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));
}

/*
 * Check if we need to upgrade our descriptor @d from write-only mode.
 */
static int
bpf_check_upgrade(u_long cmd, struct bpf_d *d, struct bpf_insn *fcode,
    int flen)
{
        int is_snap, need_upgrade;

        /*
         * Check if we've already upgraded or new filter is empty.
         */
        if (d->bd_writer == 0 || fcode == NULL)
                return (0);

        need_upgrade = 0;

        /*
         * Check if cmd looks like snaplen setting from
         * pcap_bpf.c:pcap_open_live().
         * Note we're not checking .k value here:
         * while pcap_open_live() definitely sets to non-zero value,
         * we'd prefer to treat k=0 (deny ALL) case the same way: e.g.
         * do not consider upgrading immediately
         */
        if (cmd == BIOCSETF && flen == 1 &&
            fcode[0].code == (BPF_RET | BPF_K))
                is_snap = 1;
        else
                is_snap = 0;

        if (is_snap == 0) {
                /*
                 * We're setting first filter and it doesn't look like
                 * setting snaplen.  We're probably using bpf directly.
                 * Upgrade immediately.
                 */
                need_upgrade = 1;
        } else {
                /*
                 * Do not require upgrade by first BIOCSETF
                 * (used to set snaplen) by pcap_open_live().
                 */

                if (--d->bd_writer == 0) {
                        /*
                         * First snaplen filter has already
                         * been set. This is probably catch-all
                         * filter
                         */
                        need_upgrade = 1;
                }
        }

        CTR5(KTR_NET,
            "%s: filter function set by pid %d, "
            "bd_writer counter %d, snap %d upgrade %d",
            __func__, d->bd_pid, d->bd_writer,
            is_snap, need_upgrade);

        return (need_upgrade);
}

/*
 * Detach a file from its interface.
 */
static void
bpf_detachd(struct bpf_d *d, bool detached_ifp)
{
        struct bpf_if *bp;
        bool writer;

        BPF_LOCK_ASSERT();
        CTR2(KTR_NET, "%s: detach required by pid %d", __func__, d->bd_pid);

        /* Check if descriptor is attached */
        if ((bp = d->bd_bif) == NULL)
                return;

        BPFD_LOCK(d);
        CK_LIST_REMOVE(d, bd_next);
        writer = (d->bd_writer > 0);
        if (detached_ifp) {
                d->bd_bif = NULL;
                /*
                 * Notify descriptor as it's detached, so that any
                 * sleepers wake up and get ENXIO.
                 */
                bpf_wakeup(d);
        }
        BPFD_UNLOCK(d);

        if (!writer)
                bif_detachd(bp);

        if (d->bd_promisc && !detached_ifp) {
                d->bd_promisc = 0;
                (void)bif_promisc(bp, false);
        }

        bpfif_rele(bp);
}

/*
 * 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);
        BPF_LOCK();
        bpf_detachd(d, false);
        BPF_UNLOCK();
#ifdef MAC
        mac_bpfdesc_destroy(d);
#endif /* MAC */
        seldrain(&d->bd_sel);
        knlist_destroy(&d->bd_sel.si_note);
        callout_drain(&d->bd_callout);
        bpfd_rele(d);
}

/*
 * 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);
        }

        /* Setup counters */
        d->bd_rcount = counter_u64_alloc(M_WAITOK);
        d->bd_dcount = counter_u64_alloc(M_WAITOK);
        d->bd_fcount = counter_u64_alloc(M_WAITOK);
        d->bd_wcount = counter_u64_alloc(M_WAITOK);
        d->bd_wfcount = counter_u64_alloc(M_WAITOK);
        d->bd_wdcount = counter_u64_alloc(M_WAITOK);
        d->bd_zcopy = counter_u64_alloc(M_WAITOK);

        /*
         * 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);
        if ((flags & FREAD) == 0)
                d->bd_writer = 2;
        d->bd_bufmode = BPF_BUFMODE_BUFFER;
        d->bd_sig = SIGIO;
        d->bd_direction = BPF_D_INOUT;
        refcount_init(&d->bd_refcnt, 1);
        BPF_PID_REFRESH(d, td);
#ifdef MAC
        mac_bpfdesc_init(d);
        mac_bpfdesc_create(td->td_ucred, d);
#endif
        mtx_init(&d->bd_lock, devtoname(dev), "bpf cdev lock", MTX_DEF);
        callout_init_mtx(&d->bd_callout, &d->bd_lock, 0);
        knlist_init_mtx(&d->bd_sel.si_note, &d->bd_lock);

        /* Disable VLAN pcp tagging. */
        d->bd_pcp = 0;

        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);
        BPF_PID_REFRESH_CUR(d);
        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;
        while (d->bd_flags & BPFD_HBUF_INUSE) {
                error = mtx_sleep(&d->bd_hbuf, &d->bd_lock, PRINET | PCATCH,
                    "bd_hbuf", 0);
                if (error != 0) {
                        BPFD_UNLOCK(d);
                        return (error);
                }
        }
        /*
         * 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_flags & BPFD_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_lock, 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.
         */
        d->bd_flags |= BPFD_HBUF_INUSE;
        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.
         *
         * We do not have to worry about simultaneous reads because
         * we waited for sole access to the hold buffer above.
         */
        error = bpf_uiomove(d, d->bd_hbuf, d->bd_hlen, uio);

        BPFD_LOCK(d);
        if (d->bd_flags & BPFD_HBUF_INUSE) {
                KASSERT(d->bd_hbuf != NULL, ("bpfread: lost bd_hbuf"));
                d->bd_fbuf = d->bd_hbuf;
                d->bd_hbuf = NULL;
                d->bd_hlen = 0;
                bpf_buf_reclaimed(d);
                d->bd_flags &= ~BPFD_HBUF_INUSE;
                wakeup(&d->bd_hbuf);
        }
        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_flags & BPFD_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_ASSERT(d);

        if (callout_pending(&d->bd_callout) ||
            !callout_active(&d->bd_callout))
                return;
        if (d->bd_state == BPF_WAITING) {
                d->bd_state = BPF_TIMED_OUT;
                if (d->bd_slen != 0)
                        bpf_wakeup(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_flags & BPFD_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 epoch_tracker et;
        struct bpf_if *bp;
        struct bpf_d *d;
        struct mbuf *m, *mc;
        ssize_t len;
        int error;

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

        if (uio->uio_resid == 0)
                return (0);

        BPFD_LOCK(d);
        if ((bp = d->bd_bif) == NULL)
                error = ENXIO;
        else if (bp->bif_methods->bif_write == NULL)
                error = EOPNOTSUPP;
        if (error) {
                BPFD_UNLOCK(d);
                counter_u64_add(d->bd_wdcount, 1);
                return (error);
        }
        bpfd_ref(d);
        BPFD_UNLOCK(d);

        len = uio->uio_resid;
        /* Allocate a mbuf, up to MJUM16BYTES bytes, for our write. */
        m = m_get3(len, M_WAITOK, MT_DATA, M_PKTHDR);
        if (m == NULL) {
                error = ENOMEM;
                goto fail_wref;
        }
        m->m_pkthdr.len = m->m_len = len;

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

        if (bpf_filter(d->bd_wfilter, mtod(m, u_char *), len, len) == 0) {
                error = EPERM;
                goto fail_wref;
        }

        if (d->bd_flags & BPFD_FEEDBACK) {
                mc = m_dup(m, M_WAITOK);
                /* Set M_PROMISC for outgoing packets to be discarded. */
                if (d->bd_direction == BPF_D_INOUT)
                        m->m_flags |= M_PROMISC;
        } else
                mc = NULL;

        /* XXXGL: should belong to bpf_ifnet.c */
        if (d->bd_pcp != 0)
                (void)vlan_set_pcp(m, d->bd_pcp);

        BPFD_LOCK(d);
#ifdef MAC
        mac_bpfdesc_create_mbuf(d, m);
        if (mc != NULL)
                mac_bpfdesc_create_mbuf(d, mc);
#endif
        /*
         * Check that descriptor is still attached to the interface.
         * This can happen on bpfdetach() or if other thread did BIOCSDLT.
         */
        if (__predict_false(d->bd_bif != bp)) {
                BPFD_UNLOCK(d);
                m_freem(mc);
                error = ENXIO;
                goto fail_wref;
        }
        BPFD_UNLOCK(d);

        NET_EPOCH_ENTER(et);
        error = bp->bif_methods->bif_write(bp->bif_softc, m, mc, d->bd_flags);
        NET_EPOCH_EXIT(et);
        if (error)
                counter_u64_add(d->bd_wdcount, 1);
        else
                counter_u64_add(d->bd_wfcount, 1);
        bpfd_rele(d);

        return (error);

fail_wref:
        counter_u64_add(d->bd_wdcount, 1);
        bpfd_rele(d);
        m_freem(m);
        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)
{

        BPFD_LOCK_ASSERT(d);

        while (d->bd_flags & BPFD_HBUF_INUSE)
                mtx_sleep(&d->bd_hbuf, &d->bd_lock, PRINET, "bd_hbuf", 0);
        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;
        counter_u64_zero(d->bd_rcount);
        counter_u64_zero(d->bd_dcount);
        counter_u64_zero(d->bd_fcount);
        counter_u64_zero(d->bd_wcount);
        counter_u64_zero(d->bd_wfcount);
        counter_u64_zero(d->bd_wdcount);
        counter_u64_zero(d->bd_zcopy);
}

/*
 *  FIONREAD            Check for read packet available.
 *  BIOCGETIFLIST       Get list of all tap points.
 *  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
 *  BIOCGTSTAMP         Get time stamp format and resolution.
 *  BIOCSTSTAMP         Set time stamp format and resolution.
 *  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.
 *  BIOCSETVLANPCP      Set VLAN PCP tag.
 */
/* 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);
        BPF_PID_REFRESH(d, td);
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
        BPFD_UNLOCK(d);

        if (d->bd_flags & BPFD_LOCKED) {
                switch (cmd) {
                case BIOCGETIFLIST:
                case BIOCGBLEN:
                case BIOCFLUSH:
                case BIOCGDLT:
                case BIOCGDLTLIST:
#ifdef COMPAT_FREEBSD32
                case BIOCGDLTLIST32:
#endif
                case BIOCGETIF:
                case BIOCGRTIMEOUT:
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
                case BIOCGRTIMEOUT32:
#endif
                case BIOCGSTATS:
                case BIOCVERSION:
                case BIOCGRSIG:
                case BIOCGHDRCMPLT:
                case BIOCSTSTAMP:
                case BIOCFEEDBACK:
                case FIONREAD:
                case BIOCLOCK:
                case BIOCSRTIMEOUT:
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
                case BIOCSRTIMEOUT32:
#endif
                case BIOCIMMEDIATE:
                case TIOCGPGRP:
                case BIOCROTZBUF:
                        break;
                default:
                        return (EPERM);
                }
        }
#ifdef COMPAT_FREEBSD32
        /*
         * If we see a 32-bit compat ioctl, mark the stream as 32-bit so
         * that it will get 32-bit packet headers.
         */
        switch (cmd) {
        case BIOCSETF32:
        case BIOCSETFNR32:
        case BIOCSETWF32:
        case BIOCGDLTLIST32:
        case BIOCGRTIMEOUT32:
        case BIOCSRTIMEOUT32:
                if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
                        BPFD_LOCK(d);
                        d->bd_compat32 = 1;
                        BPFD_UNLOCK(d);
                }
        }
#endif

        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;
                        while (d->bd_flags & BPFD_HBUF_INUSE)
                                mtx_sleep(&d->bd_hbuf, &d->bd_lock,
                                    PRINET, "bd_hbuf", 0);
                        if (d->bd_hbuf)
                                n += d->bd_hlen;
                        BPFD_UNLOCK(d);

                        *(int *)addr = n;
                        break;
                }
        /*
         * Get list of all tap points.
         */
        case BIOCGETIFLIST:
                error = bpf_getiflist((struct bpf_iflist *)addr);
                break;

        /*
         * Get buffer len [for read()].
         */
        case BIOCGBLEN:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_bufsize;
                BPFD_UNLOCK(d);
                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:
#ifdef COMPAT_FREEBSD32
        case BIOCSETF32:
        case BIOCSETFNR32:
        case BIOCSETWF32:
#endif
                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:
                BPF_LOCK();
                if (d->bd_bif == NULL) {
                        /*
                         * No interface attached yet.
                         */
                        error = EINVAL;
                } else if (d->bd_promisc == 0) {
                        struct bpf_if *bp = d->bd_bif;

                        if ((error = bif_promisc(bp, true)) == 0)
                                d->bd_promisc = 1;
                }
                BPF_UNLOCK();
                break;

        /*
         * Get current data link type.
         */
        case BIOCGDLT:
                BPF_LOCK();
                if (d->bd_bif == NULL)
                        error = EINVAL;
                else
                        *(u_int *)addr = d->bd_bif->bif_dlt;
                BPF_UNLOCK();
                break;

        /*
         * Get a list of supported data link types.
         */
#ifdef COMPAT_FREEBSD32
        case BIOCGDLTLIST32:
                {
                        struct bpf_dltlist32 *list32;
                        struct bpf_dltlist dltlist;

                        list32 = (struct bpf_dltlist32 *)addr;
                        dltlist.bfl_len = list32->bfl_len;
                        dltlist.bfl_list = PTRIN(list32->bfl_list);
                        BPF_LOCK();
                        if (d->bd_bif == NULL)
                                error = EINVAL;
                        else {
                                error = bpf_getdltlist(d, &dltlist);
                                if (error == 0)
                                        list32->bfl_len = dltlist.bfl_len;
                        }
                        BPF_UNLOCK();
                        break;
                }
#endif

        case BIOCGDLTLIST:
                BPF_LOCK();
                if (d->bd_bif == NULL)
                        error = EINVAL;
                else
                        error = bpf_getdltlist(d, (struct bpf_dltlist *)addr);
                BPF_UNLOCK();
                break;

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

        /*
         * Get interface name.
         */
        case BIOCGETIF:
                BPF_LOCK();
                if (d->bd_bif == NULL)
                        error = EINVAL;
                else {
                        struct bpf_if *const bp = d->bd_bif;
                        struct ifreq *const ifr = (struct ifreq *)addr;

                        strlcpy(ifr->ifr_name, bp->bif_name,
                            sizeof(ifr->ifr_name));
                }
                BPF_UNLOCK();
                break;

        /*
         * Set interface.
         */
        case BIOCSETIF: {
                struct ifreq *const ifr = (struct ifreq *)addr;
                struct bpf_if *bp;

                /*
                 * 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.
                 */
                BPFD_LOCK(d);
                if (d->bd_bufmode == BPF_BUFMODE_BUFFER &&
                    d->bd_sbuf == NULL) {
                        u_int size;

                        size = d->bd_bufsize;
                        BPFD_UNLOCK(d);
                        error = bpf_buffer_ioctl_sblen(d, &size);
                        if (error != 0)
                                break;
                } else
                        BPFD_UNLOCK(d);
                BPF_LOCK();
                /*
                 * Look through attached interfaces for the named one.
                 */
                LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                        if (strncmp(ifr->ifr_name, bp->bif_name,
                            sizeof(ifr->ifr_name)) == 0)
                                break;
                }
                if (bp != NULL)
                        error = bpf_attachd(d, bp);
                else
                        error = ENXIO;
                BPF_UNLOCK();
                break;
        }
        /*
         * Set read timeout.
         */
        case BIOCSRTIMEOUT:
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
        case BIOCSRTIMEOUT32:
#endif
                {
                        struct timeval *tv = (struct timeval *)addr;
#if defined(COMPAT_FREEBSD32)
                        struct timeval32 *tv32;
                        struct timeval tv64;

                        if (cmd == BIOCSRTIMEOUT32) {
                                tv32 = (struct timeval32 *)addr;
                                tv = &tv64;
                                tv->tv_sec = tv32->tv_sec;
                                tv->tv_usec = tv32->tv_usec;
                        } else
#endif
                                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:
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
        case BIOCGRTIMEOUT32:
#endif
                {
                        struct timeval *tv;
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
                        struct timeval32 *tv32;
                        struct timeval tv64;

                        if (cmd == BIOCGRTIMEOUT32)
                                tv = &tv64;
                        else
#endif
                                tv = (struct timeval *)addr;

                        tv->tv_sec = d->bd_rtout / hz;
                        tv->tv_usec = (d->bd_rtout % hz) * tick;
#if defined(COMPAT_FREEBSD32) && defined(__amd64__)
                        if (cmd == BIOCGRTIMEOUT32) {
                                tv32 = (struct timeval32 *)addr;
                                tv32->tv_sec = tv->tv_sec;
                                tv32->tv_usec = tv->tv_usec;
                        }
#endif

                        break;
                }

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

                        /* XXXCSJP overflow */
                        bs->bs_recv = (u_int)counter_u64_fetch(d->bd_rcount);
                        bs->bs_drop = (u_int)counter_u64_fetch(d->bd_dcount);
                        break;
                }

        /*
         * Set immediate mode.
         */
        case BIOCIMMEDIATE:
                BPFD_LOCK(d);
                d->bd_flags |= *(u_int *)addr ? BPFD_IMMEDIATE : 0;
                BPFD_UNLOCK(d);
                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:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_flags & BPFD_HDRCMPLT ? 1 : 0;
                BPFD_UNLOCK(d);
                break;

        /*
         * Set "header already complete" flag
         */
        case BIOCSHDRCMPLT:
                BPFD_LOCK(d);
                d->bd_flags |= *(u_int *)addr ? BPFD_HDRCMPLT : 0;
                BPFD_UNLOCK(d);
                break;

        /*
         * Get packet direction flag
         */
        case BIOCGDIRECTION:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_direction;
                BPFD_UNLOCK(d);
                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:
                                BPFD_LOCK(d);
                                d->bd_direction = direction;
                                BPFD_UNLOCK(d);
                                break;
                        default:
                                error = EINVAL;
                        }
                }
                break;

        /*
         * Get packet timestamp format and resolution.
         */
        case BIOCGTSTAMP:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_tstamp;
                BPFD_UNLOCK(d);
                break;

        /*
         * Set packet timestamp format and resolution.
         */
        case BIOCSTSTAMP:
                {
                        u_int   func;

                        func = *(u_int *)addr;
                        if (BPF_T_VALID(func))
                                d->bd_tstamp = func;
                        else
                                error = EINVAL;
                }
                break;

        case BIOCFEEDBACK:
                BPFD_LOCK(d);
                d->bd_flags |= *(u_int *)addr ? BPFD_FEEDBACK : 0;
                BPFD_UNLOCK(d);
                break;

        case BIOCLOCK:
                BPFD_LOCK(d);
                d->bd_flags |= BPFD_LOCKED;
                BPFD_UNLOCK(d);
                break;

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

        case FIOASYNC:          /* Send signal on receive packets */
                BPFD_LOCK(d);
                d->bd_flags |= *(u_int *)addr ? BPFD_ASYNC : 0;
                BPFD_UNLOCK(d);
                break;

        case FIOSETOWN:
                /*
                 * XXX: Add some sort of locking here?
                 * fsetown() can sleep.
                 */
                error = fsetown(*(int *)addr, &d->bd_sigio);
                break;

        case FIOGETOWN:
                BPFD_LOCK(d);
                *(int *)addr = fgetown(&d->bd_sigio);
                BPFD_UNLOCK(d);
                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 {
                                BPFD_LOCK(d);
                                d->bd_sig = sig;
                                BPFD_UNLOCK(d);
                        }
                        break;
                }
        case BIOCGRSIG:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_sig;
                BPFD_UNLOCK(d);
                break;

        case BIOCGETBUFMODE:
                BPFD_LOCK(d);
                *(u_int *)addr = d->bd_bufmode;
                BPFD_UNLOCK(d);
                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:
                        CURVNET_RESTORE();
                        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);
                        CURVNET_RESTORE();
                        return (EBUSY);
                }
                d->bd_bufmode = *(u_int *)addr;
                BPFD_UNLOCK(d);
                break;

        case BIOCGETZMAX:
                error = bpf_ioctl_getzmax(td, d, (size_t *)addr);
                break;

        case BIOCSETZBUF:
                error = bpf_ioctl_setzbuf(td, d, (struct bpf_zbuf *)addr);
                break;

        case BIOCROTZBUF:
                error = bpf_ioctl_rotzbuf(td, d, (struct bpf_zbuf *)addr);
                break;

        case BIOCSETVLANPCP:
                {
                        u_int pcp;

                        pcp = *(u_int *)addr;
                        if (pcp > BPF_PRIO_MAX || pcp < 0) {
                                error = EINVAL;
                                break;
                        }
                        d->bd_pcp = pcp;
                        break;
                }
        }
        CURVNET_RESTORE();
        return (error);
}

/*
 * Return list of available tapping points, or report how much space is
 * required for a successful return.
 */
static int
bpf_getiflist(struct bpf_iflist *bi)
{
        struct bpf_if *bp;
        u_int allsize, size, cnt;
        char *uaddr;

        BPF_LOCK();

        cnt = allsize = size = 0;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                allsize += strlen(bp->bif_name) + 1;
                if (++cnt == bi->bi_count)
                        size = allsize;
        }
        if (size == 0)
                size = allsize;

        if (bi->bi_size == 0) {
                BPF_UNLOCK();
                bi->bi_size = size;
                bi->bi_count = cnt;
                return (0);
        } else if (bi->bi_size < size) {
                BPF_UNLOCK();
                return (ENOSPC);
        }

        uaddr = bi->bi_ubuf;
        cnt = 0;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                u_int len;
                int error;

                len = strlen(bp->bif_name) + 1;
                if ((error = copyout(bp->bif_name, uaddr, len)) != 0) {
                        BPF_UNLOCK();
                        return (error);
                }
                if (++cnt == bi->bi_count)
                        break;
                uaddr += len;
        }
        BPF_UNLOCK();
        bi->bi_count = cnt;

        return (0);
}

/*
 * 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.
 *
 * Note we use global lock here to serialize bpf_setf() and bpf_setif()
 * calls.
 */
static int
bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
{
#ifdef COMPAT_FREEBSD32
        struct bpf_program fp_swab;
        struct bpf_program32 *fp32;
#endif
        struct bpf_program_buffer *fcode;
        struct bpf_insn *filter;
#ifdef BPF_JITTER
        bpf_jit_filter *jfunc;
#endif
        size_t size;
        u_int flen;
        bool track_event;

#ifdef COMPAT_FREEBSD32
        switch (cmd) {
        case BIOCSETF32:
        case BIOCSETWF32:
        case BIOCSETFNR32:
                fp32 = (struct bpf_program32 *)fp;
                fp_swab.bf_len = fp32->bf_len;
                fp_swab.bf_insns =
                    (struct bpf_insn *)(uintptr_t)fp32->bf_insns;
                fp = &fp_swab;
                switch (cmd) {
                case BIOCSETF32:
                        cmd = BIOCSETF;
                        break;
                case BIOCSETWF32:
                        cmd = BIOCSETWF;
                        break;
                }
                break;
        }
#endif

        filter = NULL;
#ifdef BPF_JITTER
        jfunc = NULL;
#endif
        /*
         * Check new filter validness before acquiring any locks.
         * Allocate memory for new filter, if needed.
         */
        flen = fp->bf_len;
        if (flen > bpf_maxinsns || (fp->bf_insns == NULL && flen != 0))
                return (EINVAL);
        size = flen * sizeof(*fp->bf_insns);
        if (size > 0) {
                /* We're setting up new filter. Copy and check actual data. */
                fcode = bpf_program_buffer_alloc(size, M_WAITOK);
                filter = (struct bpf_insn *)fcode->buffer;
                if (copyin(fp->bf_insns, filter, size) != 0 ||
                    !bpf_validate(filter, flen)) {
                        free(fcode, M_BPF);
                        return (EINVAL);
                }
#ifdef BPF_JITTER
                if (cmd != BIOCSETWF) {
                        /*
                         * Filter is copied inside fcode and is
                         * perfectly valid.
                         */
                        jfunc = bpf_jitter(filter, flen);
                }
#endif
        }

        track_event = false;
        fcode = NULL;

        BPF_LOCK();
        BPFD_LOCK(d);
        /* Set up new filter. */
        if (cmd == BIOCSETWF) {
                if (d->bd_wfilter != NULL) {
                        fcode = __containerof((void *)d->bd_wfilter,
                            struct bpf_program_buffer, buffer);
#ifdef BPF_JITTER
                        fcode->func = NULL;
#endif
                }
                d->bd_wfilter = filter;
        } else {
                if (d->bd_rfilter != NULL) {
                        fcode = __containerof((void *)d->bd_rfilter,
                            struct bpf_program_buffer, buffer);
#ifdef BPF_JITTER
                        fcode->func = d->bd_bfilter;
#endif
                }
                d->bd_rfilter = filter;
#ifdef BPF_JITTER
                d->bd_bfilter = jfunc;
#endif
                if (cmd == BIOCSETF)
                        reset_d(d);

                if (bpf_check_upgrade(cmd, d, filter, flen) != 0) {
                        /*
                         * Filter can be set several times without
                         * specifying interface. In this case just mark d
                         * as reader.
                         */
                        d->bd_writer = 0;
                        if (d->bd_bif != NULL) {
                                /*
                                 * Remove descriptor from writers-only list
                                 * and add it to active readers list.
                                 */
                                CK_LIST_REMOVE(d, bd_next);
                                CK_LIST_INSERT_HEAD(&d->bd_bif->bif_dlist,
                                    d, bd_next);
                                CTR2(KTR_NET,
                                    "%s: upgrade required by pid %d",
                                    __func__, d->bd_pid);
                                track_event = true;
                        }
                }
        }
        BPFD_UNLOCK(d);

        if (fcode != NULL)
                NET_EPOCH_CALL(bpf_program_buffer_free, &fcode->epoch_ctx);

        if (track_event)
                bif_attachd(d->bd_bif);

        BPF_UNLOCK();
        return (0);
}

/*
 * Attach descriptor to a tap point, possibly detaching from the old one,
 * reset the counters.
 * XXXGL: this KPI is subject to change
 */
static int
bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
{
        bool writer;

        BPF_LOCK_ASSERT();

        /*
         * At this point, we expect the buffer is already allocated.  If not,
         * return an error.
         */
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
        case BPF_BUFMODE_ZBUF:
                if (d->bd_sbuf == NULL)
                        return (EINVAL);
                break;

        default:
                panic("%s: bufmode %d", __func__, d->bd_bufmode);
        }

        if (bp == d->bd_bif) {
                BPFD_LOCK(d);
                reset_d(d);
                BPFD_UNLOCK(d);
                return (0);
        } else if (d->bd_bif != NULL)
                bpf_detachd(d, false);

        /*
         * Save sysctl value to protect from sysctl change between reads.
         */
        writer = V_bpf_optimize_writers || (d->bd_writer > 0);

        /*
         * Point d at bp, and add d to the interface's list.
         * Since there are many applications using BPF for
         * sending raw packets only (dhcpd, cdpd are good examples)
         * we can delay adding d to the list of active listeners until
         * some filter is configured.
         */
        BPFD_LOCK(d);
        /*
         * Hold reference to bpif while descriptor uses this interface.
         */
        bpfif_ref(bp);
        d->bd_bif = bp;
        if (writer) {
                /* Add to writers-only list */
                CK_LIST_INSERT_HEAD(&bp->bif_wlist, d, bd_next);
                /*
                 * We decrement bd_writer on every filter set operation.
                 * First BIOCSETF is done by pcap_open_live() to set up
                 * snap length. After that application usually sets its own
                 * filter.
                 */
                d->bd_writer = 2;
        } else
                CK_LIST_INSERT_HEAD(&bp->bif_dlist, d, bd_next);

        reset_d(d);

        /* Trigger EVFILT_WRITE events. */
        bpf_wakeup(d);

        BPFD_UNLOCK(d);

        CTR3(KTR_NET, "%s: called by pid %d, adding to %s list",
            __func__, d->bd_pid, d->bd_writer ? "writer" : "active");

        if (!writer)
                bif_attachd(bp);

        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);
        BPF_PID_REFRESH(d, td);
        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)
                return (1);

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &bpfread_filtops;
                break;

        case EVFILT_WRITE:
                kn->kn_fop = &bpfwrite_filtops;
                break;

        default:
                return (1);
        }

        /*
         * Refresh PID associated with this descriptor.
         */
        BPFD_LOCK(d);
        BPF_PID_REFRESH_CUR(d);
        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;
                /*
                 * Ignore the hold buffer if it is being copied to user space.
                 */
                if (!(d->bd_flags & BPFD_HBUF_INUSE) && 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);
}

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

        BPFD_LOCK_ASSERT(d);

        if (d->bd_bif == NULL) {
                kn->kn_data = 0;
                return (0);
        } else {
                kn->kn_data = bif_wrsize(d->bd_bif);
                return (1);
        }
}

#define BPF_TSTAMP_NONE         0
#define BPF_TSTAMP_FAST         1
#define BPF_TSTAMP_NORMAL       2
#define BPF_TSTAMP_EXTERN       3

static int
bpf_ts_quality(int tstype)
{

        if (tstype == BPF_T_NONE)
                return (BPF_TSTAMP_NONE);
        if ((tstype & BPF_T_FAST) != 0)
                return (BPF_TSTAMP_FAST);

        return (BPF_TSTAMP_NORMAL);
}

static int
bpf_gettime(struct bintime *bt, int tstype, struct mbuf *m)
{
        struct timespec ts;
        struct m_tag *tag;
        int quality;

        quality = bpf_ts_quality(tstype);
        if (quality == BPF_TSTAMP_NONE)
                return (quality);

        if (m != NULL) {
                if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR | M_TSTMP)) {
                        mbuf_tstmp2timespec(m, &ts);
                        timespec2bintime(&ts, bt);
                        return (BPF_TSTAMP_EXTERN);
                }
                tag = m_tag_locate(m, MTAG_BPF, MTAG_BPF_TIMESTAMP, NULL);
                if (tag != NULL) {
                        *bt = *(struct bintime *)(tag + 1);
                        return (BPF_TSTAMP_EXTERN);
                }
        }
        if (quality == BPF_TSTAMP_NORMAL)
                binuptime(bt);
        else
                getbinuptime(bt);

        return (quality);
}

/*
 * 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 epoch_tracker et;
        struct bintime bt;
        struct bpf_d *d;
#ifdef BPF_JITTER
        bpf_jit_filter *bf;
#endif
        u_int slen;
        int gottime;

        gottime = BPF_TSTAMP_NONE;
        NET_EPOCH_ENTER(et);
        CK_LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                counter_u64_add(d->bd_rcount, 1);
                /*
                 * NB: We don't check the 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) {
                        /*
                         * Filter matches. Let's to acquire write lock.
                         */
                        BPFD_LOCK(d);
                        counter_u64_add(d->bd_fcount, 1);
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp,
                                    NULL);
#ifdef MAC
                        if (bif_mac_check_receive(bp, d) == 0)
#endif
                                catchpacket(d, pkt, pktlen, slen,
                                    bpf_append_bytes, &bt);
                        BPFD_UNLOCK(d);
                }
        }
        NET_EPOCH_EXIT(et);
}

void
bpf_tap_if(if_t ifp, u_char *pkt, u_int pktlen)
{
        if (bpf_peers_present(ifp->if_bpf))
                bpf_tap(ifp->if_bpf, pkt, pktlen);
}

/*
 * Incoming linkage from device drivers, when packet is in an mbuf chain.
 * Locking model is explained in bpf_tap().
 */
void
bpf_mtap(struct bpf_if *bp, struct mbuf *m)
{
        struct epoch_tracker et;
        struct bintime bt;
        struct bpf_d *d;
#ifdef BPF_JITTER
        bpf_jit_filter *bf;
#endif
        u_int pktlen, slen;
        int gottime;

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

        pktlen = m_length(m, NULL);
        gottime = BPF_TSTAMP_NONE;

        NET_EPOCH_ENTER(et);
        CK_LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (bpf_chkdir(d, m))
                        continue;
                counter_u64_add(d->bd_rcount, 1);
#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) {
                        BPFD_LOCK(d);

                        counter_u64_add(d->bd_fcount, 1);
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp, m);
#ifdef MAC
                        if (bif_mac_check_receive(bp, d) == 0)
#endif
                                catchpacket(d, (u_char *)m, pktlen, slen,
                                    bpf_append_mbuf, &bt);
                        BPFD_UNLOCK(d);
                }
        }
        NET_EPOCH_EXIT(et);
}

void
bpf_mtap_if(if_t ifp, struct mbuf *m)
{
        if (bpf_peers_present(ifp->if_bpf)) {
                M_ASSERTVALID(m);
                bpf_mtap(ifp->if_bpf, m);
        }
}

/*
 * 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 epoch_tracker et;
        struct bintime bt;
        struct mbuf mb;
        struct bpf_d *d;
        u_int pktlen, slen;
        int gottime;

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

        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_flags = 0;
        mb.m_next = m;
        mb.m_data = data;
        mb.m_len = dlen;
        pktlen += dlen;

        gottime = BPF_TSTAMP_NONE;

        NET_EPOCH_ENTER(et);
        CK_LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (bpf_chkdir(d, m))
                        continue;
                counter_u64_add(d->bd_rcount, 1);
                slen = bpf_filter(d->bd_rfilter, (u_char *)&mb, pktlen, 0);
                if (slen != 0) {
                        BPFD_LOCK(d);

                        counter_u64_add(d->bd_fcount, 1);
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp, m);
#ifdef MAC
                        if (bif_mac_check_receive(bp, d) == 0)
#endif
                                catchpacket(d, (u_char *)&mb, pktlen, slen,
                                    bpf_append_mbuf, &bt);
                        BPFD_UNLOCK(d);
                }
        }
        NET_EPOCH_EXIT(et);
}

void
bpf_mtap2_if(if_t ifp, void *data, u_int dlen, struct mbuf *m)
{
        if (bpf_peers_present(ifp->if_bpf)) {
                M_ASSERTVALID(m);
                bpf_mtap2(ifp->if_bpf, data, dlen, m);
        }
}

#undef  BPF_TSTAMP_NONE
#undef  BPF_TSTAMP_FAST
#undef  BPF_TSTAMP_NORMAL
#undef  BPF_TSTAMP_EXTERN

static int
bpf_hdrlen(struct bpf_d *d)
{
        int hdrlen;

        hdrlen = d->bd_bif->bif_hdrlen;
#ifndef BURN_BRIDGES
        if (d->bd_tstamp == BPF_T_NONE ||
            BPF_T_FORMAT(d->bd_tstamp) == BPF_T_MICROTIME)
#ifdef COMPAT_FREEBSD32
                if (d->bd_compat32)
                        hdrlen += SIZEOF_BPF_HDR(struct bpf_hdr32);
                else
#endif
                        hdrlen += SIZEOF_BPF_HDR(struct bpf_hdr);
        else
#endif
                hdrlen += SIZEOF_BPF_HDR(struct bpf_xhdr);
#ifdef COMPAT_FREEBSD32
        if (d->bd_compat32)
                hdrlen = BPF_WORDALIGN32(hdrlen);
        else
#endif
                hdrlen = BPF_WORDALIGN(hdrlen);

        return (hdrlen - d->bd_bif->bif_hdrlen);
}

static void
bpf_bintime2ts(struct bintime *bt, struct bpf_ts *ts, int tstype)
{
        struct bintime bt2, boottimebin;
        struct timeval tsm;
        struct timespec tsn;

        if ((tstype & BPF_T_MONOTONIC) == 0) {
                bt2 = *bt;
                getboottimebin(&boottimebin);
                bintime_add(&bt2, &boottimebin);
                bt = &bt2;
        }
        switch (BPF_T_FORMAT(tstype)) {
        case BPF_T_MICROTIME:
                bintime2timeval(bt, &tsm);
                ts->bt_sec = tsm.tv_sec;
                ts->bt_frac = tsm.tv_usec;
                break;
        case BPF_T_NANOTIME:
                bintime2timespec(bt, &tsn);
                ts->bt_sec = tsn.tv_sec;
                ts->bt_frac = tsn.tv_nsec;
                break;
        case BPF_T_BINTIME:
                ts->bt_sec = bt->sec;
                ts->bt_frac = bt->frac;
                break;
        }
}

/*
 * 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 bintime *bt)
{
        static char zeroes[BPF_ALIGNMENT];
        struct bpf_xhdr hdr;
#ifndef BURN_BRIDGES
        struct bpf_hdr hdr_old;
#ifdef COMPAT_FREEBSD32
        struct bpf_hdr32 hdr32_old;
#endif
#endif
        int caplen, curlen, hdrlen, pad, totlen;
        int do_wakeup = 0;
        int do_timestamp;
        int tstype;

        BPFD_LOCK_ASSERT(d);
        if (d->bd_bif == NULL) {
                /* Descriptor was detached in concurrent thread */
                counter_u64_add(d->bd_dcount, 1);
                return;
        }

        /*
         * 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).
         */
        hdrlen = bpf_hdrlen(d);
        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.
         */
#ifdef COMPAT_FREEBSD32
        if (d->bd_compat32)
                curlen = BPF_WORDALIGN32(d->bd_slen);
        else
#endif
                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);
                        counter_u64_add(d->bd_dcount, 1);
                        return;
                }
                KASSERT(!(d->bd_flags & BPFD_HBUF_INUSE),
                    ("hold buffer is in use"));
                ROTATE_BUFFERS(d);
                do_wakeup = 1;
                curlen = 0;
        } else {
                if ((d->bd_flags & BPFD_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;
                }
                pad = curlen - d->bd_slen;
                KASSERT(pad >= 0 && pad <= sizeof(zeroes),
                    ("%s: invalid pad byte count %d", __func__, pad));
                if (pad > 0) {
                        /* Zero pad bytes. */
                        bpf_append_bytes(d, d->bd_sbuf, d->bd_slen, zeroes,
                            pad);
                }
        }

        caplen = totlen - hdrlen;
        tstype = d->bd_tstamp;
        do_timestamp = tstype != BPF_T_NONE;
#ifndef BURN_BRIDGES
        if (tstype == BPF_T_NONE || BPF_T_FORMAT(tstype) == BPF_T_MICROTIME) {
                struct bpf_ts ts;
                if (do_timestamp)
                        bpf_bintime2ts(bt, &ts, tstype);
#ifdef COMPAT_FREEBSD32
                if (d->bd_compat32) {
                        bzero(&hdr32_old, sizeof(hdr32_old));
                        if (do_timestamp) {
                                hdr32_old.bh_tstamp.tv_sec = ts.bt_sec;
                                hdr32_old.bh_tstamp.tv_usec = ts.bt_frac;
                        }
                        hdr32_old.bh_datalen = pktlen;
                        hdr32_old.bh_hdrlen = hdrlen;
                        hdr32_old.bh_caplen = caplen;
                        bpf_append_bytes(d, d->bd_sbuf, curlen, &hdr32_old,
                            sizeof(hdr32_old));
                        goto copy;
                }
#endif
                bzero(&hdr_old, sizeof(hdr_old));
                if (do_timestamp) {
                        hdr_old.bh_tstamp.tv_sec = ts.bt_sec;
                        hdr_old.bh_tstamp.tv_usec = ts.bt_frac;
                }
                hdr_old.bh_datalen = pktlen;
                hdr_old.bh_hdrlen = hdrlen;
                hdr_old.bh_caplen = caplen;
                bpf_append_bytes(d, d->bd_sbuf, curlen, &hdr_old,
                    sizeof(hdr_old));
                goto copy;
        }
#endif

        /*
         * 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));
        if (do_timestamp)
                bpf_bintime2ts(bt, &hdr.bh_tstamp, tstype);
        hdr.bh_datalen = pktlen;
        hdr.bh_hdrlen = hdrlen;
        hdr.bh_caplen = caplen;
        bpf_append_bytes(d, d->bd_sbuf, curlen, &hdr, sizeof(hdr));

        /*
         * Copy the packet data into the store buffer and update its length.
         */
#ifndef BURN_BRIDGES
copy:
#endif
        (*cpfn)(d, d->bd_sbuf, curlen + hdrlen, pkt, 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
bpfd_free(epoch_context_t ctx)
{
        struct bpf_d *d;
        struct bpf_program_buffer *p;

        /*
         * 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.
         */
        d = __containerof(ctx, struct bpf_d, epoch_ctx);
        bpf_free(d);
        if (d->bd_rfilter != NULL) {
                p = __containerof((void *)d->bd_rfilter,
                    struct bpf_program_buffer, buffer);
#ifdef BPF_JITTER
                p->func = d->bd_bfilter;
#endif
                bpf_program_buffer_free(&p->epoch_ctx);
        }
        if (d->bd_wfilter != NULL) {
                p = __containerof((void *)d->bd_wfilter,
                    struct bpf_program_buffer, buffer);
#ifdef BPF_JITTER
                p->func = NULL;
#endif
                bpf_program_buffer_free(&p->epoch_ctx);
        }

        mtx_destroy(&d->bd_lock);
        counter_u64_free(d->bd_rcount);
        counter_u64_free(d->bd_dcount);
        counter_u64_free(d->bd_fcount);
        counter_u64_free(d->bd_wcount);
        counter_u64_free(d->bd_wfcount);
        counter_u64_free(d->bd_wdcount);
        counter_u64_free(d->bd_zcopy);
        free(d, M_BPF);
}

/*
 * Attach a tap point to bpf.
 * XXX: with current KPI it is consumer's responsibility to avoid duplicates.
 */
struct bpf_if *
bpf_attach(const char *name, u_int dlt, u_int hdrlen,
    const struct bif_methods *methods, void *sc)
{
        struct bpf_if *bp;

        bp = malloc(sizeof(*bp), M_BPF, M_WAITOK | M_ZERO);

        CK_LIST_INIT(&bp->bif_dlist);
        CK_LIST_INIT(&bp->bif_wlist);
        bp->bif_dlt = dlt;
        bp->bif_hdrlen = hdrlen;
        bp->bif_softc = sc;
        bp->bif_name = name;
        bp->bif_methods = methods;
        refcount_init(&bp->bif_refcnt, 1);
        BPF_LOCK();
        LIST_INSERT_HEAD(&V_bpf_iflist, bp, bif_next);
        BPF_UNLOCK();

        return (bp);
}

#ifdef VIMAGE
/*
 * Detach descriptors on interface's vmove event.
 * XXXGL: shouldn't be a special case, but a full detach.
 */
void
bpf_ifdetach(struct ifnet *ifp)
{
        struct bpf_if *bp;
        struct bpf_d *d;

        BPF_LOCK();
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                /* XXXGL: assuming softc is ifnet here */
                if (bp->bif_softc != ifp)
                        continue;

                /* Detach common descriptors */
                while ((d = CK_LIST_FIRST(&bp->bif_dlist)) != NULL) {
                        bpf_detachd(d, true);
                }

                /* Detach writer-only descriptors */
                while ((d = CK_LIST_FIRST(&bp->bif_wlist)) != NULL) {
                        bpf_detachd(d, true);
                }
        }
        BPF_UNLOCK();
}
#endif

/*
 * Detach bpf tap point.  This involves detaching each descriptor associated
 * with the interface.  Notify each descriptor as it's detached so that any
 * sleepers wake up and get ENXIO.
 */
void
bpf_detach(struct bpf_if *bp)
{
        struct bpf_d *d;

        BPF_LOCK();
        LIST_REMOVE(bp, bif_next);

        CTR3(KTR_NET, "%s: sheduling free for encap %d for bp %p",
            __func__, bp->bif_dlt, bp);

        /* Detach common descriptors */
        while ((d = CK_LIST_FIRST(&bp->bif_dlist)) != NULL) {
                bpf_detachd(d, true);
        }

        /* Detach writer-only descriptors */
        while ((d = CK_LIST_FIRST(&bp->bif_wlist)) != NULL) {
                bpf_detachd(d, true);
        }
        bpfif_rele(bp);
        BPF_UNLOCK();
}

#ifdef VIMAGE
/*
 * Move bpf to a different VNET.  This KPI is a crutch to support if_vmove
 * and is not supposed to be used anywhere else.
 */
void
bpf_vmove(struct bpf_if *bp)
{

        BPF_LOCK();
        LIST_REMOVE(bp, bif_next);
        LIST_INSERT_HEAD(&V_bpf_iflist, bp, bif_next);
        BPF_UNLOCK();
}
#endif

bool
bpf_peers_present_if(struct ifnet *ifp)
{
        return (bpf_peers_present(ifp->if_bpf));
}

/*
 * Get a list of available data link type of the tap point.  If a tap point
 * attaches more than one time, it is supposed to attach with different DLTs
 * but with the same name pointer.
 */
static int
bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl)
{
        const char *name;
        struct bpf_if *bp;
        u_int *lst;
        int error, n, n1;

        BPF_LOCK_ASSERT();

        name = d->bd_bif->bif_name;
        n1 = 0;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                if (bp->bif_name == name)
                        n1++;
        }
        if (bfl->bfl_list == NULL) {
                bfl->bfl_len = n1;
                return (0);
        }
        if (n1 > bfl->bfl_len)
                return (ENOMEM);

        lst = malloc(n1 * sizeof(u_int), M_TEMP, M_WAITOK);
        n = 0;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                if (bp->bif_name != name)
                        continue;
                lst[n++] = bp->bif_dlt;
        }
        error = copyout(lst, bfl->bfl_list, sizeof(u_int) * n);
        free(lst, M_TEMP);
        bfl->bfl_len = n;
        return (error);
}

/*
 * Set the data link type of a BPF descriptor.  The convention is that
 * application first do BIOCSETIF and then BIOCSETDLT, thus the descriptor
 * is supposed to be already attached.  Only one kernel facility provides
 * tapping points with same name but different DLT - ieee80211_radiotap.
 *
 * XXXGL: this function definitely looks suspicious, e.g. it clearly doesn't
 * clear promisc on the old bpf_if.  The convention about reference counting
 * is also unclear.
 */
static int
bpf_setdlt(struct bpf_d *d, u_int dlt)
{
        int error, opromisc;
        const char *name;
        struct bpf_if *bp;

        BPF_LOCK_ASSERT();
        MPASS(d->bd_bif != NULL);

        /*
         * It is safe to check bd_bif without BPFD_LOCK, it can not be
         * changed while we hold global lock.
         */
        if (d->bd_bif->bif_dlt == dlt)
                return (0);

        name = d->bd_bif->bif_name;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                if (bp->bif_name == name && bp->bif_dlt == dlt)
                        break;
        }
        if (bp == NULL)
                return (EINVAL);

        opromisc = d->bd_promisc;
        bpf_attachd(d, bp);
        if (opromisc) {
                error = bp->bif_methods->bif_promisc(bp->bif_softc, true);
                if (error)
                        printf("%s: bif_promisc on %s failed (%d)\n",
                            __func__, bp->bif_name, error);
                else
                        d->bd_promisc = 1;
        }
        return (0);
}

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

        sx_init(&bpf_sx, "bpf global lock");
        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;

        BPF_LOCK();
        /*
         * We are protected by global lock here, interfaces and
         * descriptors can not be deleted while we hold it.
         */
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                CK_LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
                        counter_u64_zero(bd->bd_rcount);
                        counter_u64_zero(bd->bd_dcount);
                        counter_u64_zero(bd->bd_fcount);
                        counter_u64_zero(bd->bd_wcount);
                        counter_u64_zero(bd->bd_wfcount);
                        counter_u64_zero(bd->bd_zcopy);
                }
        }
        BPF_UNLOCK();
}

/*
 * Fill filter statistics
 */
static void
bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
{

        BPF_LOCK_ASSERT();
        bzero(d, sizeof(*d));
        d->bd_structsize = sizeof(*d);
        d->bd_immediate = bd->bd_flags & BPFD_IMMEDIATE ? 1 : 0;
        d->bd_promisc = bd->bd_promisc;
        d->bd_hdrcmplt = bd->bd_flags & BPFD_HDRCMPLT ? 1 : 0;
        d->bd_direction = bd->bd_direction;
        d->bd_feedback = bd->bd_flags & BPFD_FEEDBACK ? 1 : 0;
        d->bd_async = bd->bd_flags & BPFD_ASYNC ? 1 : 0;
        d->bd_rcount = counter_u64_fetch(bd->bd_rcount);
        d->bd_dcount = counter_u64_fetch(bd->bd_dcount);
        d->bd_fcount = counter_u64_fetch(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_name, sizeof(d->bd_ifname));
        d->bd_locked = bd->bd_flags & BPFD_LOCKED ? 1 : 0;
        d->bd_wcount = counter_u64_fetch(bd->bd_wcount);
        d->bd_wdcount = counter_u64_fetch(bd->bd_wdcount);
        d->bd_wfcount = counter_u64_fetch(bd->bd_wfcount);
        d->bd_zcopy = counter_u64_fetch(bd->bd_zcopy);
        d->bd_bufmode = bd->bd_bufmode;
}

/*
 * Handle `netstat -B' stats request
 */
static int
bpf_stats_sysctl(SYSCTL_HANDLER_ARGS)
{
        static const struct xbpf_d zerostats;
        struct xbpf_d *xbdbuf, *xbd, tempstats;
        u_int bpfd_cnt, index;
        int 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(tempstats))
                        return (EINVAL);
                memset(&tempstats, 0, sizeof(tempstats));
                error = SYSCTL_IN(req, &tempstats, sizeof(tempstats));
                if (error)
                        return (error);
                if (bcmp(&tempstats, &zerostats, sizeof(tempstats)) != 0)
                        return (EINVAL);
                bpf_zero_counters();
                return (0);
        }
        bpfd_cnt = 0;
        BPF_LOCK();
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                CK_LIST_FOREACH(bd, &bp->bif_wlist, bd_next)
                        bpfd_cnt++;
                CK_LIST_FOREACH(bd, &bp->bif_dlist, bd_next)
                        bpfd_cnt++;
        }
        if (bpfd_cnt == 0 || req->oldptr == NULL) {
                BPF_UNLOCK();
                return (SYSCTL_OUT(req, 0, bpfd_cnt * sizeof(*xbd)));
        }
        if (req->oldlen < bpfd_cnt * sizeof(*xbd)) {
                BPF_UNLOCK();
                return (ENOMEM);
        }
        xbdbuf = malloc(bpfd_cnt * sizeof(*xbd), M_BPF, M_WAITOK);
        index = 0;
        LIST_FOREACH(bp, &V_bpf_iflist, bif_next) {
                /* Send writers-only first */
                CK_LIST_FOREACH(bd, &bp->bif_wlist, bd_next) {
                        MPASS(index <= bpfd_cnt);
                        xbd = &xbdbuf[index++];
                        bpfstats_fill_xbpf(xbd, bd);
                }
                CK_LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
                        MPASS(index <= bpfd_cnt);
                        xbd = &xbdbuf[index++];
                        bpfstats_fill_xbpf(xbd, bd);
                }
        }
        BPF_UNLOCK();
        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.
 */

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

void
bpf_tap_if(if_t ifp, u_char *pkt, u_int pktlen)
{
}

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

void
bpf_mtap_if(if_t ifp, struct mbuf *m)
{
}

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

void
bpf_mtap2_if(if_t ifp, void *data, u_int dlen, struct mbuf *m)
{
}

void
bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
{
        static const struct bpfd_list dead_bpf_if = CK_LIST_HEAD_INITIALIZER();

        ifp->if_bpf = __DECONST(struct bpf_if *, &dead_bpf_if);
}

void
bpfdetach(struct ifnet *ifp)
{
}

bool
bpf_peers_present_if(struct ifnet *ifp)
{
        return (false);
}

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 */