/src/SockFuzzer/third_party/xnu/bsd/net/bpf.c

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/*
 * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1990, 1991, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
 * Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  @(#)bpf.c 8.2 (Berkeley) 3/28/94
 *
 * $FreeBSD: src/sys/net/bpf.c,v 1.59.2.5 2001/01/05 04:49:09 jdp Exp $
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include "bpf.h"

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

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

#include <sys/poll.h>

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

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

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/if_ether.h>
#include <netinet/isakmp.h>
#include <netinet6/esp.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/firewire.h>

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

#include <kern/locks.h>
#include <kern/thread_call.h>
#include <libkern/section_keywords.h>

#include <os/log.h>

extern int tvtohz(struct timeval *);

#define BPF_BUFSIZE 4096
#define UIOMOVE(cp, len, code, uio) uiomove(cp, len, uio)

#define PRINET  26                      /* interruptible */

#define ISAKMP_HDR_SIZE (sizeof(struct isakmp) + sizeof(struct isakmp_gen))
#define ESP_HDR_SIZE sizeof(struct newesp)

typedef void (*pktcopyfunc_t)(const void *, void *, size_t);

/*
 * The default read buffer size is patchable.
 */
static unsigned int bpf_bufsize = BPF_BUFSIZE;
SYSCTL_INT(_debug, OID_AUTO, bpf_bufsize, CTLFLAG_RW | CTLFLAG_LOCKED,
    &bpf_bufsize, 0, "");

static int sysctl_bpf_maxbufsize SYSCTL_HANDLER_ARGS;
extern const int copysize_limit_panic;
#define BPF_MAXSIZE_CAP (copysize_limit_panic >> 1)
__private_extern__ unsigned int bpf_maxbufsize = BPF_MAXBUFSIZE;
SYSCTL_PROC(_debug, OID_AUTO, bpf_maxbufsize, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
    &bpf_maxbufsize, 0,
    sysctl_bpf_maxbufsize, "I", "Default BPF max buffer size");

static unsigned int bpf_maxdevices = 256;
SYSCTL_UINT(_debug, OID_AUTO, bpf_maxdevices, CTLFLAG_RW | CTLFLAG_LOCKED,
    &bpf_maxdevices, 0, "");
/*
 * bpf_wantpktap controls the defaul visibility of DLT_PKTAP
 * For OS X is off by default so process need to use the ioctl BPF_WANT_PKTAP
 * explicitly to be able to use DLT_PKTAP.
 */
#if !XNU_TARGET_OS_OSX
static unsigned int bpf_wantpktap = 1;
#else /* XNU_TARGET_OS_OSX */
static unsigned int bpf_wantpktap = 0;
#endif /* XNU_TARGET_OS_OSX */
SYSCTL_UINT(_debug, OID_AUTO, bpf_wantpktap, CTLFLAG_RW | CTLFLAG_LOCKED,
    &bpf_wantpktap, 0, "");

static int bpf_debug = 0;
SYSCTL_INT(_debug, OID_AUTO, bpf_debug, CTLFLAG_RW | CTLFLAG_LOCKED,
    &bpf_debug, 0, "");

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

decl_lck_mtx_data(static, bpf_mlock_data);
static lck_mtx_t                *bpf_mlock = &bpf_mlock_data;
static lck_grp_t                *bpf_mlock_grp;
static lck_grp_attr_t   *bpf_mlock_grp_attr;
static lck_attr_t               *bpf_mlock_attr;

#endif /* __APPLE__ */

static int      bpf_allocbufs(struct bpf_d *);
static errno_t  bpf_attachd(struct bpf_d *d, struct bpf_if *bp);
static int      bpf_detachd(struct bpf_d *d, int);
static void     bpf_freed(struct bpf_d *);
static int      bpf_movein(struct uio *, int,
    struct mbuf **, struct sockaddr *, int *);
static int      bpf_setif(struct bpf_d *, ifnet_t ifp, bool, bool);
static void     bpf_timed_out(void *, void *);
static void     bpf_wakeup(struct bpf_d *);
static u_int    get_pkt_trunc_len(u_char *, u_int);
static void     catchpacket(struct bpf_d *, struct bpf_packet *, u_int, int);
static void     reset_d(struct bpf_d *);
static int      bpf_setf(struct bpf_d *, u_int, user_addr_t, u_long);
static int      bpf_getdltlist(struct bpf_d *, caddr_t, struct proc *);
static int      bpf_setdlt(struct bpf_d *, u_int);
static int      bpf_set_traffic_class(struct bpf_d *, int);
static void     bpf_set_packet_service_class(struct mbuf *, int);

static void     bpf_acquire_d(struct bpf_d *);
static void     bpf_release_d(struct bpf_d *);

static  int bpf_devsw_installed;

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

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

/* Darwin's cdevsw struct differs slightly from BSDs */
#define CDEV_MAJOR 23
static const struct cdevsw bpf_cdevsw = {
  .d_open       = bpfopen,
  .d_close      = bpfclose,
  .d_read       = bpfread,
  .d_write      = bpfwrite,
  .d_ioctl      = bpfioctl,
  .d_stop       = eno_stop,
  .d_reset      = eno_reset,
  .d_ttys       = NULL,
  .d_select     = bpfselect,
  .d_mmap       = eno_mmap,
  .d_strategy   = eno_strat,
  .d_reserved_1 = eno_getc,
  .d_reserved_2 = eno_putc,
  .d_type       = 0
};

#define SOCKADDR_HDR_LEN           offsetof(struct sockaddr, sa_data)

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

  switch (linktype) {
#if SLIP
  case DLT_SLIP:
    sa_family = AF_INET;
    hlen = 0;
    break;
#endif /* SLIP */

  case DLT_EN10MB:
    sa_family = AF_UNSPEC;
    /* XXX Would MAXLINKHDR be better? */
    hlen = sizeof(struct ether_header);
    break;

#if FDDI
  case DLT_FDDI:
#if defined(__FreeBSD__) || defined(__bsdi__)
    sa_family = AF_IMPLINK;
    hlen = 0;
#else
    sa_family = AF_UNSPEC;
    /* XXX 4(FORMAC)+6(dst)+6(src)+3(LLC)+5(SNAP) */
    hlen = 24;
#endif
    break;
#endif /* FDDI */

  case DLT_RAW:
  case DLT_NULL:
    sa_family = AF_UNSPEC;
    hlen = 0;
    break;

#ifdef __FreeBSD__
  case DLT_ATM_RFC1483:
    /*
     * en atm driver requires 4-byte atm pseudo header.
     * though it isn't standard, vpi:vci needs to be
     * specified anyway.
     */
    sa_family = AF_UNSPEC;
    hlen = 12;      /* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
    break;
#endif

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

  case DLT_APPLE_IP_OVER_IEEE1394:
    sa_family = AF_UNSPEC;
    hlen = sizeof(struct firewire_header);
    break;

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

  case DLT_IEEE802_11_RADIO:
    sa_family = AF_IEEE80211;
    hlen = 0;
    break;

  default:
    return EIO;
  }

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

  if (sockp) {
    /*
     * Build a sockaddr based on the data link layer type.
     * We do this at this level because the ethernet header
     * is copied directly into the data field of the sockaddr.
     * In the case of SLIP, there is no header and the packet
     * is forwarded as is.
     * Also, we are careful to leave room at the front of the mbuf
     * for the link level header.
     */
    if ((hlen + SOCKADDR_HDR_LEN) > sockp->sa_len) {
      return EIO;
    }
    sockp->sa_family = sa_family;
  } else {
    /*
     * We're directly sending the packet data supplied by
     * the user; we don't need to make room for the link
     * header, and don't need the header length value any
     * more, so set it to 0.
     */
    hlen = 0;
  }

  MGETHDR(m, M_WAIT, MT_DATA);
  if (m == 0) {
    return ENOBUFS;
  }
  if ((unsigned)len > MHLEN) {
    MCLGET(m, M_WAIT);
    if ((m->m_flags & M_EXT) == 0) {
      error = ENOBUFS;
      goto bad;
    }
  }
  m->m_pkthdr.len = m->m_len = len;
  m->m_pkthdr.rcvif = NULL;
  *mp = m;

  /*
   * Make room for link header.
   */
  if (hlen != 0) {
    m->m_pkthdr.len -= hlen;
    m->m_len -= hlen;
    m->m_data += hlen; /* XXX */
    error = UIOMOVE((caddr_t)sockp->sa_data, hlen, UIO_WRITE, uio);
    if (error) {
      goto bad;
    }
  }
  error = UIOMOVE(mtod(m, caddr_t), len - hlen, UIO_WRITE, uio);
  if (error) {
    goto bad;
  }

  /* Check for multicast destination */
  switch (linktype) {
  case DLT_EN10MB: {
    struct ether_header *eh;

    eh = mtod(m, struct ether_header *);
    if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
      if (_ether_cmp(etherbroadcastaddr,
          eh->ether_dhost) == 0) {
        m->m_flags |= M_BCAST;
      } else {
        m->m_flags |= M_MCAST;
      }
    }
    break;
  }
  }

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

#ifdef __APPLE__

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

  if (nbpfilter >= bpf_maxdevices) {
    return;
  }

  while (bpf_growing) {
    /* Wait until new device has been created */
    (void) tsleep((caddr_t)&bpf_growing, PZERO, "bpf_growing", 0);
  }
  if (nbpfilter > cur_size) {
    /* other thread grew it already */
    return;
  }
  bpf_growing = 1;

  /* need to grow bpf_dtab first */
  if (nbpfilter == bpf_dtab_size) {
    int new_dtab_size;
    struct bpf_d **new_dtab = NULL;
    struct bpf_d **old_dtab = NULL;

    new_dtab_size = bpf_dtab_size + NBPFILTER;
    new_dtab = (struct bpf_d **)_MALLOC(
      sizeof(struct bpf_d *) * new_dtab_size, M_DEVBUF, M_WAIT);
    if (new_dtab == 0) {
      printf("bpf_make_dev_t: malloc bpf_dtab failed\n");
      goto done;
    }
    if (bpf_dtab) {
      bcopy(bpf_dtab, new_dtab,
          sizeof(struct bpf_d *) * bpf_dtab_size);
    }
    bzero(new_dtab + bpf_dtab_size,
        sizeof(struct bpf_d *) * NBPFILTER);
    old_dtab = bpf_dtab;
    bpf_dtab = new_dtab;
    bpf_dtab_size = new_dtab_size;
    if (old_dtab != NULL) {
      _FREE(old_dtab, M_DEVBUF);
    }
  }
  i = nbpfilter++;
  (void) devfs_make_node(makedev(maj, i),
      DEVFS_CHAR, UID_ROOT, GID_WHEEL, 0600,
      "bpf%d", i);
done:
  bpf_growing = 0;
  wakeup((caddr_t)&bpf_growing);
}

#endif

/*
 * Attach file to the bpf interface, i.e. make d listen on bp.
 */
static errno_t
bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
{
  int first = bp->bif_dlist == NULL;
  int     error = 0;

  /*
   * Point d at bp, and add d to the interface's list of listeners.
   * Finally, point the driver's bpf cookie at the interface so
   * it will divert packets to bpf.
   */
  d->bd_bif = bp;
  d->bd_next = bp->bif_dlist;
  bp->bif_dlist = d;

  /*
   * Take a reference on the device even if an error is returned
   * because we keep the device in the interface's list of listeners
   */
  bpf_acquire_d(d);

  if (first) {
    /* Find the default bpf entry for this ifp */
    if (bp->bif_ifp->if_bpf == NULL) {
      struct bpf_if   *tmp, *primary = NULL;

      for (tmp = bpf_iflist; tmp; tmp = tmp->bif_next) {
        if (tmp->bif_ifp == bp->bif_ifp) {
          primary = tmp;
          break;
        }
      }
      bp->bif_ifp->if_bpf = primary;
    }
    /* Only call dlil_set_bpf_tap for primary dlt */
    if (bp->bif_ifp->if_bpf == bp) {
      dlil_set_bpf_tap(bp->bif_ifp, BPF_TAP_INPUT_OUTPUT,
          bpf_tap_callback);
    }

    if (bp->bif_tap != NULL) {
      error = bp->bif_tap(bp->bif_ifp, bp->bif_dlt,
          BPF_TAP_INPUT_OUTPUT);
    }
  }

  /*
   * Reset the detach flags in case we previously detached an interface
   */
  d->bd_flags &= ~(BPF_DETACHING | BPF_DETACHED);

  if (bp->bif_dlt == DLT_PKTAP) {
    d->bd_flags |= BPF_FINALIZE_PKTAP;
  } else {
    d->bd_flags &= ~BPF_FINALIZE_PKTAP;
  }
  return error;
}

/*
 * Detach a file from its interface.
 *
 * Return 1 if was closed by some thread, 0 otherwise
 */
static int
bpf_detachd(struct bpf_d *d, int closing)
{
  struct bpf_d **p;
  struct bpf_if *bp;
  struct ifnet  *ifp;

  int bpf_closed = d->bd_flags & BPF_CLOSING;
  /*
   * Some other thread already detached
   */
  if ((d->bd_flags & (BPF_DETACHED | BPF_DETACHING)) != 0) {
    goto done;
  }
  /*
   * This thread is doing the detach
   */
  d->bd_flags |= BPF_DETACHING;

  ifp = d->bd_bif->bif_ifp;
  bp = d->bd_bif;

  if (bpf_debug != 0) {
    printf("%s: %llx %s%s\n",
        __func__, (uint64_t)VM_KERNEL_ADDRPERM(d),
        if_name(ifp), closing ? " closing" : "");
  }

  /* Remove d from the interface's descriptor list. */
  p = &bp->bif_dlist;
  while (*p != d) {
    p = &(*p)->bd_next;
    if (*p == 0) {
      panic("bpf_detachd: descriptor not in list");
    }
  }
  *p = (*p)->bd_next;
  if (bp->bif_dlist == 0) {
    /*
     * Let the driver know that there are no more listeners.
     */
    /* Only call dlil_set_bpf_tap for primary dlt */
    if (bp->bif_ifp->if_bpf == bp) {
      dlil_set_bpf_tap(ifp, BPF_TAP_DISABLE, NULL);
    }
    if (bp->bif_tap) {
      bp->bif_tap(ifp, bp->bif_dlt, BPF_TAP_DISABLE);
    }

    for (bp = bpf_iflist; bp; bp = bp->bif_next) {
      if (bp->bif_ifp == ifp && bp->bif_dlist != 0) {
        break;
      }
    }
    if (bp == NULL) {
      ifp->if_bpf = NULL;
    }
  }
  d->bd_bif = NULL;
  /*
   * Check if this descriptor had requested promiscuous mode.
   * If so, turn it off.
   */
  if (d->bd_promisc) {
    d->bd_promisc = 0;
    lck_mtx_unlock(bpf_mlock);
    if (ifnet_set_promiscuous(ifp, 0)) {
      /*
       * Something is really wrong if we were able to put
       * the driver into promiscuous mode, but can't
       * take it out.
       * Most likely the network interface is gone.
       */
      printf("%s: ifnet_set_promiscuous failed\n", __func__);
    }
    lck_mtx_lock(bpf_mlock);
  }

  /*
   * Wake up other thread that are waiting for this thread to finish
   * detaching
   */
  d->bd_flags &= ~BPF_DETACHING;
  d->bd_flags |= BPF_DETACHED;

  /* Refresh the local variable as d could have been modified */
  bpf_closed = d->bd_flags & BPF_CLOSING;
  /*
   * Note that We've kept the reference because we may have dropped
   * the lock when turning off promiscuous mode
   */
  bpf_release_d(d);

done:
  /*
   * When closing makes sure no other thread refer to the bpf_d
   */
  if (bpf_debug != 0) {
    printf("%s: %llx done\n",
        __func__, (uint64_t)VM_KERNEL_ADDRPERM(d));
  }
  /*
   * Let the caller know the bpf_d is closed
   */
  if (bpf_closed) {
    return 1;
  } else {
    return 0;
  }
}

/*
 * Start asynchronous timer, if necessary.
 * Must be called with bpf_mlock held.
 */
static void
bpf_start_timer(struct bpf_d *d)
{
  uint64_t deadline;
  struct timeval tv;

  if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
    tv.tv_sec = d->bd_rtout / hz;
    tv.tv_usec = (d->bd_rtout % hz) * tick;

    clock_interval_to_deadline(
      (uint64_t)tv.tv_sec * USEC_PER_SEC + tv.tv_usec,
      NSEC_PER_USEC, &deadline);
    /*
     * The state is BPF_IDLE, so the timer hasn't
     * been started yet, and hasn't gone off yet;
     * there is no thread call scheduled, so this
     * won't change the schedule.
     *
     * XXX - what if, by the time it gets entered,
     * the deadline has already passed?
     */
    thread_call_enter_delayed(d->bd_thread_call, deadline);
    d->bd_state = BPF_WAITING;
  }
}

/*
 * Cancel asynchronous timer.
 * Must be called with bpf_mlock held.
 */
static boolean_t
bpf_stop_timer(struct bpf_d *d)
{
  /*
   * If the timer has already gone off, this does nothing.
   * Our caller is expected to set d->bd_state to BPF_IDLE,
   * with the bpf_mlock, after we are called. bpf_timed_out()
   * also grabs bpf_mlock, so, if the timer has gone off and
   * bpf_timed_out() hasn't finished, it's waiting for the
   * lock; when this thread releases the lock, it will
   * find the state is BPF_IDLE, and just release the
   * lock and return.
   */
  return thread_call_cancel(d->bd_thread_call);
}

void
bpf_acquire_d(struct bpf_d *d)
{
  void *lr_saved =  __builtin_return_address(0);

  LCK_MTX_ASSERT(bpf_mlock, LCK_MTX_ASSERT_OWNED);

  d->bd_refcnt += 1;

  d->bd_ref_lr[d->bd_next_ref_lr] = lr_saved;
  d->bd_next_ref_lr = (d->bd_next_ref_lr + 1) % BPF_REF_HIST;
}

void
bpf_release_d(struct bpf_d *d)
{
  void *lr_saved =  __builtin_return_address(0);

  LCK_MTX_ASSERT(bpf_mlock, LCK_MTX_ASSERT_OWNED);

  if (d->bd_refcnt <= 0) {
    panic("%s: %p refcnt <= 0", __func__, d);
  }

  d->bd_refcnt -= 1;

  d->bd_unref_lr[d->bd_next_unref_lr] = lr_saved;
  d->bd_next_unref_lr = (d->bd_next_unref_lr + 1) % BPF_REF_HIST;

  if (d->bd_refcnt == 0) {
    /* Assert the device is detached */
    if ((d->bd_flags & BPF_DETACHED) == 0) {
      panic("%s: %p BPF_DETACHED not set", __func__, d);
    }

    _FREE(d, M_DEVBUF);
  }
}

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

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

  /*
   * Each minor can be opened by only one process.  If the requested
   * minor is in use, return EBUSY.
   *
   * Important: bpfopen() and bpfclose() have to check and set the status
   * of a device in the same lockin context otherwise the device may be
   * leaked because the vnode use count will be unpextectly greater than 1
   * when close() is called.
   */
  if (bpf_dtab[minor(dev)] == NULL) {
    /* Reserve while opening */
    bpf_dtab[minor(dev)] = BPF_DEV_RESERVED;
  } else {
    lck_mtx_unlock(bpf_mlock);
    return EBUSY;
  }
  d = (struct bpf_d *)_MALLOC(sizeof(struct bpf_d), M_DEVBUF,
      M_WAIT | M_ZERO);
  if (d == NULL) {
    /* this really is a catastrophic failure */
    printf("bpfopen: malloc bpf_d failed\n");
    bpf_dtab[minor(dev)] = NULL;
    lck_mtx_unlock(bpf_mlock);
    return ENOMEM;
  }

  /* Mark "in use" and do most initialization. */
  bpf_acquire_d(d);
  d->bd_bufsize = bpf_bufsize;
  d->bd_sig = SIGIO;
  d->bd_seesent = 1;
  d->bd_oflags = flags;
  d->bd_state = BPF_IDLE;
  d->bd_traffic_class = SO_TC_BE;
  d->bd_flags |= BPF_DETACHED;
  if (bpf_wantpktap) {
    d->bd_flags |= BPF_WANT_PKTAP;
  } else {
    d->bd_flags &= ~BPF_WANT_PKTAP;
  }
  d->bd_thread_call = thread_call_allocate(bpf_timed_out, d);
  if (d->bd_thread_call == NULL) {
    printf("bpfopen: malloc thread call failed\n");
    bpf_dtab[minor(dev)] = NULL;
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);

    return ENOMEM;
  }
  d->bd_opened_by = p;
  uuid_generate(d->bd_uuid);

  bpf_dtab[minor(dev)] = d; /* Mark opened */
  lck_mtx_unlock(bpf_mlock);

  return 0;
}

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

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

  d = bpf_dtab[minor(dev)];
  if (d == NULL || d == BPF_DEV_RESERVED) {
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  /*
   * Other threads may call bpd_detachd() if we drop the bpf_mlock
   */
  d->bd_flags |= BPF_CLOSING;

  if (bpf_debug != 0) {
    printf("%s: %llx\n",
        __func__, (uint64_t)VM_KERNEL_ADDRPERM(d));
  }

  bpf_dtab[minor(dev)] = BPF_DEV_RESERVED; /* Reserve while closing */

  /*
   * Deal with any in-progress timeouts.
   */
  switch (d->bd_state) {
  case BPF_IDLE:
    /*
     * Not waiting for a timeout, and no timeout happened.
     */
    break;

  case BPF_WAITING:
    /*
     * Waiting for a timeout.
     * Cancel any timer that has yet to go off,
     * and mark the state as "closing".
     * Then drop the lock to allow any timers that
     * *have* gone off to run to completion, and wait
     * for them to finish.
     */
    if (!bpf_stop_timer(d)) {
      /*
       * There was no pending call, so the call must
       * have been in progress. Wait for the call to
       * complete; we have to drop the lock while
       * waiting. to let the in-progrss call complete
       */
      d->bd_state = BPF_DRAINING;
      while (d->bd_state == BPF_DRAINING) {
        msleep((caddr_t)d, bpf_mlock, PRINET,
            "bpfdraining", NULL);
      }
    }
    d->bd_state = BPF_IDLE;
    break;

  case BPF_TIMED_OUT:
    /*
     * Timer went off, and the timeout routine finished.
     */
    d->bd_state = BPF_IDLE;
    break;

  case BPF_DRAINING:
    /*
     * Another thread is blocked on a close waiting for
     * a timeout to finish.
     * This "shouldn't happen", as the first thread to enter
     * bpfclose() will set bpf_dtab[minor(dev)] to 1, and
     * all subsequent threads should see that and fail with
     * ENXIO.
     */
    panic("Two threads blocked in a BPF close");
    break;
  }

  if (d->bd_bif) {
    bpf_detachd(d, 1);
  }
  selthreadclear(&d->bd_sel);
  thread_call_free(d->bd_thread_call);

  while (d->bd_hbuf_read != 0) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  bpf_freed(d);

  /* Mark free in same context as bpfopen comes to check */
  bpf_dtab[minor(dev)] = NULL;                    /* Mark closed */

  bpf_release_d(d);

  lck_mtx_unlock(bpf_mlock);

  return 0;
}

#define BPF_SLEEP bpf_sleep

static int
bpf_sleep(struct bpf_d *d, int pri, const char *wmesg, int timo)
{
  u_int64_t abstime = 0;

  if (timo != 0) {
    clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
  }

  return msleep1((caddr_t)d, bpf_mlock, pri, wmesg, abstime);
}

static void
bpf_finalize_pktap(struct bpf_hdr *hp, struct pktap_header *pktaphdr)
{
  if (pktaphdr->pth_flags & PTH_FLAG_V2_HDR) {
    struct pktap_v2_hdr *pktap_v2_hdr;

    pktap_v2_hdr = (struct pktap_v2_hdr *)pktaphdr;

    if (pktap_v2_hdr->pth_flags & PTH_FLAG_DELAY_PKTAP) {
      pktap_v2_finalize_proc_info(pktap_v2_hdr);
    }
  } else {
    if (pktaphdr->pth_flags & PTH_FLAG_DELAY_PKTAP) {
      pktap_finalize_proc_info(pktaphdr);
    }

    if (pktaphdr->pth_flags & PTH_FLAG_TSTAMP) {
      hp->bh_tstamp.tv_sec = pktaphdr->pth_tstamp.tv_sec;
      hp->bh_tstamp.tv_usec = pktaphdr->pth_tstamp.tv_usec;
    }
  }
}

/*
 * Rotate the packet buffers in descriptor d.  Move the store buffer
 * into the hold slot, and the free buffer into the store slot.
 * Zero the length of the new store buffer.
 */
#define ROTATE_BUFFERS(d) \
  if (d->bd_hbuf_read != 0) \
          panic("rotating bpf buffers during read"); \
  (d)->bd_hbuf = (d)->bd_sbuf; \
  (d)->bd_hlen = (d)->bd_slen; \
  (d)->bd_hcnt = (d)->bd_scnt; \
  (d)->bd_sbuf = (d)->bd_fbuf; \
  (d)->bd_slen = 0; \
  (d)->bd_scnt = 0; \
  (d)->bd_fbuf = NULL;
/*
 *  bpfread - read next chunk of packets from buffers
 */
int
bpfread(dev_t dev, struct uio *uio, int ioflag)
{
  struct bpf_d *d;
  caddr_t hbuf;
  int timed_out, hbuf_len;
  int error;
  int flags;

  lck_mtx_lock(bpf_mlock);

  d = bpf_dtab[minor(dev)];
  if (d == NULL || d == BPF_DEV_RESERVED ||
      (d->bd_flags & BPF_CLOSING) != 0) {
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  bpf_acquire_d(d);

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

  if (d->bd_state == BPF_WAITING) {
    bpf_stop_timer(d);
  }

  timed_out = (d->bd_state == BPF_TIMED_OUT);
  d->bd_state = BPF_IDLE;

  while (d->bd_hbuf_read != 0) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  if ((d->bd_flags & BPF_CLOSING) != 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }
  /*
   * If the hold buffer is empty, then do a timed sleep, which
   * ends when the timeout expires or when enough packets
   * have arrived to fill the store buffer.
   */
  while (d->bd_hbuf == 0) {
    if ((d->bd_immediate || timed_out || (ioflag & IO_NDELAY)) &&
        d->bd_slen != 0) {
      /*
       * We're in immediate mode, or are reading
       * in non-blocking mode, or a timer was
       * started before the read (e.g., by select()
       * or poll()) and has expired and a packet(s)
       * either arrived since the previous
       * read or arrived while we were asleep.
       * Rotate the buffers and return what's here.
       */
      ROTATE_BUFFERS(d);
      break;
    }

    /*
     * No data is available, check to see if the bpf device
     * is still pointed at a real interface.  If not, return
     * ENXIO so that the userland process knows to rebind
     * it before using it again.
     */
    if (d->bd_bif == NULL) {
      bpf_release_d(d);
      lck_mtx_unlock(bpf_mlock);
      return ENXIO;
    }
    if (ioflag & IO_NDELAY) {
      bpf_release_d(d);
      lck_mtx_unlock(bpf_mlock);
      return EWOULDBLOCK;
    }
    error = BPF_SLEEP(d, PRINET | PCATCH, "bpf", d->bd_rtout);
    /*
     * Make sure device is still opened
     */
    if ((d->bd_flags & BPF_CLOSING) != 0) {
      bpf_release_d(d);
      lck_mtx_unlock(bpf_mlock);
      return ENXIO;
    }

    while (d->bd_hbuf_read != 0) {
      msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading",
          NULL);
    }

    if ((d->bd_flags & BPF_CLOSING) != 0) {
      bpf_release_d(d);
      lck_mtx_unlock(bpf_mlock);
      return ENXIO;
    }

    if (error == EINTR || error == ERESTART) {
      if (d->bd_hbuf != NULL) {
        /*
         * Because we msleep, the hold buffer might
         * be filled when we wake up.  Avoid rotating
         * in this case.
         */
        break;
      }
      if (d->bd_slen != 0) {
        /*
         * Sometimes we may be interrupted often and
         * the sleep above will not timeout.
         * Regardless, we should rotate the buffers
         * if there's any new data pending and
         * return it.
         */
        ROTATE_BUFFERS(d);
        break;
      }
      bpf_release_d(d);
      lck_mtx_unlock(bpf_mlock);
      if (error == ERESTART) {
        printf("%s: %llx ERESTART to EINTR\n",
            __func__, (uint64_t)VM_KERNEL_ADDRPERM(d));
        error = EINTR;
      }
      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) {
        bpf_release_d(d);
        lck_mtx_unlock(bpf_mlock);
        return 0;
      }
      ROTATE_BUFFERS(d);
      break;
    }
  }
  /*
   * At this point, we know we have something in the hold slot.
   */

  /*
   * Set the hold buffer read. So we do not
   * rotate the buffers until the hold buffer
   * read is complete. Also to avoid issues resulting
   * from page faults during disk sleep (<rdar://problem/13436396>).
   */
  d->bd_hbuf_read = 1;
  hbuf = d->bd_hbuf;
  hbuf_len = d->bd_hlen;
  flags = d->bd_flags;
  lck_mtx_unlock(bpf_mlock);

#ifdef __APPLE__
  /*
   * Before we move data to userland, we fill out the extended
   * header fields.
   */
  if (flags & BPF_EXTENDED_HDR) {
    char *p;

    p = hbuf;
    while (p < hbuf + hbuf_len) {
      struct bpf_hdr_ext *ehp;
      uint32_t flowid;
      struct so_procinfo soprocinfo;
      int found = 0;

      ehp = (struct bpf_hdr_ext *)(void *)p;
      if ((flowid = ehp->bh_flowid) != 0) {
        if (ehp->bh_proto == IPPROTO_TCP) {
          found = inp_findinpcb_procinfo(&tcbinfo,
              flowid, &soprocinfo);
        } else if (ehp->bh_proto == IPPROTO_UDP) {
          found = inp_findinpcb_procinfo(&udbinfo,
              flowid, &soprocinfo);
        }
        if (found == 1) {
          ehp->bh_pid = soprocinfo.spi_pid;
          strlcpy(&ehp->bh_comm[0], &soprocinfo.spi_proc_name[0], sizeof(ehp->bh_comm));
        }
        ehp->bh_flowid = 0;
      }

      if (flags & BPF_FINALIZE_PKTAP) {
        struct pktap_header *pktaphdr;

        pktaphdr = (struct pktap_header *)(void *)
            (p + BPF_WORDALIGN(ehp->bh_hdrlen));

        bpf_finalize_pktap((struct bpf_hdr *) ehp,
            pktaphdr);
      }
      p += BPF_WORDALIGN(ehp->bh_hdrlen + ehp->bh_caplen);
    }
  } else if (flags & BPF_FINALIZE_PKTAP) {
    char *p;

    p = hbuf;
    while (p < hbuf + hbuf_len) {
      struct bpf_hdr *hp;
      struct pktap_header *pktaphdr;

      hp = (struct bpf_hdr *)(void *)p;
      pktaphdr = (struct pktap_header *)(void *)
          (p + BPF_WORDALIGN(hp->bh_hdrlen));

      bpf_finalize_pktap(hp, pktaphdr);

      p += BPF_WORDALIGN(hp->bh_hdrlen + hp->bh_caplen);
    }
  }
#endif

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

  lck_mtx_lock(bpf_mlock);
  /*
   * Make sure device is still opened
   */
  if ((d->bd_flags & BPF_CLOSING) != 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  d->bd_hbuf_read = 0;
  d->bd_fbuf = d->bd_hbuf;
  d->bd_hbuf = NULL;
  d->bd_hlen = 0;
  d->bd_hcnt = 0;
  wakeup((caddr_t)d);

  bpf_release_d(d);
  lck_mtx_unlock(bpf_mlock);
  return error;
}

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

  selwakeup(&d->bd_sel);
  if ((d->bd_flags & BPF_KNOTE)) {
    KNOTE(&d->bd_sel.si_note, 1);
  }
}

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

  lck_mtx_lock(bpf_mlock);
  if (d->bd_state == BPF_WAITING) {
    /*
     * There's a select or kqueue waiting for this; if there's
     * now stuff to read, wake it up.
     */
    d->bd_state = BPF_TIMED_OUT;
    if (d->bd_slen != 0) {
      bpf_wakeup(d);
    }
  } else if (d->bd_state == BPF_DRAINING) {
    /*
     * A close is waiting for this to finish.
     * Mark it as finished, and wake the close up.
     */
    d->bd_state = BPF_IDLE;
    bpf_wakeup(d);
  }
  lck_mtx_unlock(bpf_mlock);
}

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

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

  lck_mtx_lock(bpf_mlock);

  d = bpf_dtab[minor(dev)];
  if (d == NULL || d == BPF_DEV_RESERVED ||
      (d->bd_flags & BPF_CLOSING) != 0) {
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  bpf_acquire_d(d);

  if (d->bd_bif == 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  ifp = d->bd_bif->bif_ifp;

  if ((ifp->if_flags & IFF_UP) == 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENETDOWN;
  }
  if (uio_resid(uio) == 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return 0;
  }
  ((struct sockaddr *)dst_buf)->sa_len = sizeof(dst_buf);

  /*
   * fix for PR-6849527
   * geting variables onto stack before dropping lock for bpf_movein()
   */
  bif_dlt = (int)d->bd_bif->bif_dlt;
  bd_hdrcmplt  = d->bd_hdrcmplt;

  /* bpf_movein allocating mbufs; drop lock */
  lck_mtx_unlock(bpf_mlock);

  error = bpf_movein(uio, bif_dlt, &m,
      bd_hdrcmplt ? NULL : (struct sockaddr *)dst_buf,
      &datlen);

  /* take the lock again */
  lck_mtx_lock(bpf_mlock);
  if (error) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return error;
  }

  /* verify the device is still open */
  if ((d->bd_flags & BPF_CLOSING) != 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    m_freem(m);
    return ENXIO;
  }

  if (d->bd_bif == NULL) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    m_free(m);
    return ENXIO;
  }

  if ((unsigned)datlen > ifp->if_mtu) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    m_freem(m);
    return EMSGSIZE;
  }

  bpf_set_packet_service_class(m, d->bd_traffic_class);

  lck_mtx_unlock(bpf_mlock);

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

  lck_mtx_lock(bpf_mlock);
  bpf_release_d(d);
  lck_mtx_unlock(bpf_mlock);

  return error;
}

/*
 * Reset a descriptor by flushing its packet buffer and clearing the
 * receive and drop counts.
 */
static void
reset_d(struct bpf_d *d)
{
  if (d->bd_hbuf_read != 0) {
    panic("resetting buffers during read");
  }

  if (d->bd_hbuf) {
    /* Free the hold buffer. */
    d->bd_fbuf = d->bd_hbuf;
    d->bd_hbuf = NULL;
  }
  d->bd_slen = 0;
  d->bd_hlen = 0;
  d->bd_scnt = 0;
  d->bd_hcnt = 0;
  d->bd_rcount = 0;
  d->bd_dcount = 0;
}

static struct bpf_d *
bpf_get_device_from_uuid(uuid_t uuid)
{
  unsigned int i;

  for (i = 0; i < nbpfilter; i++) {
    struct bpf_d *d = bpf_dtab[i];

    if (d == NULL || d == BPF_DEV_RESERVED ||
        (d->bd_flags & BPF_CLOSING) != 0) {
      continue;
    }
    if (uuid_compare(uuid, d->bd_uuid) == 0) {
      return d;
    }
  }

  return NULL;
}

/*
 * The BIOCSETUP command "atomically" attach to the interface and
 * copy the buffer from another interface. This minimizes the risk
 * of missing packet because this is done while holding
 * the BPF global lock
 */
static int
bpf_setup(struct bpf_d *d_to, uuid_t uuid_from, ifnet_t ifp)
{
  struct bpf_d *d_from;
  int error = 0;

  LCK_MTX_ASSERT(bpf_mlock, LCK_MTX_ASSERT_OWNED);

  /*
   * Sanity checks
   */
  d_from = bpf_get_device_from_uuid(uuid_from);
  if (d_from == NULL) {
    error = ENOENT;
    os_log_info(OS_LOG_DEFAULT,
        "%s: uuids not found error %d",
        __func__, error);
    return error;
  }
  if (d_from->bd_opened_by != d_to->bd_opened_by) {
    error = EACCES;
    os_log_info(OS_LOG_DEFAULT,
        "%s: processes not matching error %d",
        __func__, error);
    return error;
  }

  /*
   * Prevent any read while copying
   */
  while (d_to->bd_hbuf_read != 0) {
    msleep((caddr_t)d_to, bpf_mlock, PRINET, __func__, NULL);
  }
  d_to->bd_hbuf_read = 1;

  while (d_from->bd_hbuf_read != 0) {
    msleep((caddr_t)d_from, bpf_mlock, PRINET, __func__, NULL);
  }
  d_from->bd_hbuf_read = 1;

  /*
   * Verify the devices have not been closed
   */
  if (d_to->bd_flags & BPF_CLOSING) {
    error = ENXIO;
    os_log_info(OS_LOG_DEFAULT,
        "%s: d_to is closing error %d",
        __func__, error);
    goto done;
  }
  if (d_from->bd_flags & BPF_CLOSING) {
    error = ENXIO;
    os_log_info(OS_LOG_DEFAULT,
        "%s: d_from is closing error %d",
        __func__, error);
    goto done;
  }

  /*
   * For now require the same buffer size
   */
  if (d_from->bd_bufsize != d_to->bd_bufsize) {
    error = EINVAL;
    os_log_info(OS_LOG_DEFAULT,
        "%s: bufsizes not matching error %d",
        __func__, error);
    goto done;
  }

  /*
   * Attach to the interface
   */
  error = bpf_setif(d_to, ifp, false, true);
  if (error != 0) {
    os_log_info(OS_LOG_DEFAULT,
        "%s: bpf_setif() failed error %d",
        __func__, error);
    goto done;
  }

  /*
   * Make sure the buffers are setup as expected by bpf_setif()
   */
  ASSERT(d_to->bd_hbuf == NULL);
  ASSERT(d_to->bd_sbuf != NULL);
  ASSERT(d_to->bd_fbuf != NULL);

  /*
   * Copy the buffers and update the pointers and counts
   */
  memcpy(d_to->bd_sbuf, d_from->bd_sbuf, d_from->bd_slen);
  d_to->bd_slen = d_from->bd_slen;
  d_to->bd_scnt = d_from->bd_scnt;

  if (d_from->bd_hbuf != NULL) {
    d_to->bd_hbuf = d_to->bd_fbuf;
    d_to->bd_fbuf = NULL;
    memcpy(d_to->bd_hbuf, d_from->bd_hbuf, d_from->bd_hlen);
  }
  d_to->bd_hlen = d_from->bd_hlen;
  d_to->bd_hcnt = d_from->bd_hcnt;

  if (bpf_debug > 0) {
    os_log_info(OS_LOG_DEFAULT,
        "%s: done slen %u scnt %u hlen %u hcnt %u",
        __func__, d_to->bd_slen, d_to->bd_scnt,
        d_to->bd_hlen, d_to->bd_hcnt);
  }
done:
  d_from->bd_hbuf_read = 0;
  wakeup((caddr_t)d_from);

  d_to->bd_hbuf_read = 0;
  wakeup((caddr_t)d_to);

  return error;
}

/*
 *  FIONREAD    Check for read packet available.
 *  SIOCGIFADDR   Get interface address - convenient hook to driver.
 *  BIOCGBLEN   Get buffer len [for read()].
 *  BIOCSETF    Set ethernet read filter.
 *  BIOCFLUSH   Flush read packet buffer.
 *  BIOCPROMISC   Put interface into promiscuous mode.
 *  BIOCGDLT    Get link layer type.
 *  BIOCGETIF   Get interface name.
 *  BIOCSETIF   Set interface.
 *  BIOCSRTIMEOUT Set read timeout.
 *  BIOCGRTIMEOUT Get read timeout.
 *  BIOCGSTATS    Get packet stats.
 *  BIOCIMMEDIATE Set immediate mode.
 *  BIOCVERSION   Get filter language version.
 *  BIOCGHDRCMPLT Get "header already complete" flag
 *  BIOCSHDRCMPLT Set "header already complete" flag
 *  BIOCGSEESENT  Get "see packets sent" flag
 *  BIOCSSEESENT  Set "see packets sent" flag
 *  BIOCSETTC   Set traffic class.
 *  BIOCGETTC   Get traffic class.
 *  BIOCSEXTHDR   Set "extended header" flag
 *  BIOCSHEADDROP Drop head of the buffer if user is not reading
 *  BIOCGHEADDROP Get "head-drop" flag
 */
/* ARGSUSED */
int
bpfioctl(dev_t dev, u_long cmd, caddr_t addr, __unused int flags,
    struct proc *p)
{
  struct bpf_d *d;
  int error = 0;
  u_int int_arg;
  struct ifreq ifr;

  lck_mtx_lock(bpf_mlock);

  d = bpf_dtab[minor(dev)];
  if (d == NULL || d == BPF_DEV_RESERVED ||
      (d->bd_flags & BPF_CLOSING) != 0) {
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  bpf_acquire_d(d);

  if (d->bd_state == BPF_WAITING) {
    bpf_stop_timer(d);
  }
  d->bd_state = BPF_IDLE;

  switch (cmd) {
  default:
    error = EINVAL;
    break;

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

    n = d->bd_slen;
    if (d->bd_hbuf && d->bd_hbuf_read == 0) {
      n += d->bd_hlen;
    }

    bcopy(&n, addr, sizeof(n));
    break;
  }

  case SIOCGIFADDR:               /* struct ifreq */
  {
    struct ifnet *ifp;

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

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

  /*
   * Set buffer length.
   */
  case BIOCSBLEN: {               /* u_int */
    u_int size;
    unsigned int maxbufsize = bpf_maxbufsize;

    /*
     * Allow larger buffer in head drop mode to with the
     * assumption the reading process may be low priority but
     * is interested in the most recent traffic
     */
    if (d->bd_headdrop != 0) {
      maxbufsize = 2 * bpf_maxbufsize;
    }

    if (d->bd_bif != 0 || (d->bd_flags & BPF_DETACHING)) {
      /*
       * Interface already attached, unable to change buffers
       */
      error = EINVAL;
      break;
    }
    bcopy(addr, &size, sizeof(size));

    if (size > maxbufsize) {
      d->bd_bufsize = maxbufsize;

      os_log_info(OS_LOG_DEFAULT,
          "%s bufsize capped to %u from %u",
          __func__, d->bd_bufsize, size);
    } else if (size < BPF_MINBUFSIZE) {
      d->bd_bufsize = BPF_MINBUFSIZE;

      os_log_info(OS_LOG_DEFAULT,
          "%s bufsize bumped to %u from %u",
          __func__, d->bd_bufsize, size);
    } else {
      d->bd_bufsize = size;
    }

    /* It's a read/write ioctl */
    bcopy(&d->bd_bufsize, addr, sizeof(u_int));
    break;
  }
  /*
   * Set link layer read filter.
   */
  case BIOCSETF32:
  case BIOCSETFNR32: {            /* struct bpf_program32 */
    struct bpf_program32 prg32;

    bcopy(addr, &prg32, sizeof(prg32));
    error = bpf_setf(d, prg32.bf_len,
        CAST_USER_ADDR_T(prg32.bf_insns), cmd);
    break;
  }

  case BIOCSETF64:
  case BIOCSETFNR64: {            /* struct bpf_program64 */
    struct bpf_program64 prg64;

    bcopy(addr, &prg64, sizeof(prg64));
    error = bpf_setf(d, prg64.bf_len, prg64.bf_insns, cmd);
    break;
  }

  /*
   * Flush read packet buffer.
   */
  case BIOCFLUSH:
    while (d->bd_hbuf_read != 0) {
      msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading",
          NULL);
    }
    if ((d->bd_flags & BPF_CLOSING) != 0) {
      error = ENXIO;
      break;
    }
    reset_d(d);
    break;

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

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

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

  /*
   * Set data link type.
   */
  case BIOCSDLT:                  /* u_int */
    if (d->bd_bif == NULL) {
      error = EINVAL;
    } else {
      u_int dlt;

      bcopy(addr, &dlt, sizeof(dlt));

      if (dlt == DLT_PKTAP &&
          !(d->bd_flags & BPF_WANT_PKTAP)) {
        dlt = DLT_RAW;
      }
      error = bpf_setdlt(d, dlt);
    }
    break;

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

      snprintf(((struct ifreq *)(void *)addr)->ifr_name,
          sizeof(ifr.ifr_name), "%s", if_name(ifp));
    }
    break;

  /*
   * Set interface.
   */
  case BIOCSETIF: {               /* struct ifreq */
    ifnet_t ifp;

    bcopy(addr, &ifr, sizeof(ifr));
    ifr.ifr_name[IFNAMSIZ - 1] = '\0';
    ifp = ifunit(ifr.ifr_name);
    if (ifp == NULL) {
      error = ENXIO;
    } else {
      error = bpf_setif(d, ifp, true, false);
    }
    break;
  }

  /*
   * Set read timeout.
   */
  case BIOCSRTIMEOUT32: {         /* struct user32_timeval */
    struct user32_timeval _tv;
    struct timeval tv;

    bcopy(addr, &_tv, sizeof(_tv));
    tv.tv_sec  = _tv.tv_sec;
    tv.tv_usec = _tv.tv_usec;

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

  case BIOCSRTIMEOUT64: {         /* struct user64_timeval */
    struct user64_timeval _tv;
    struct timeval tv;

    bcopy(addr, &_tv, sizeof(_tv));
    tv.tv_sec  = _tv.tv_sec;
    tv.tv_usec = _tv.tv_usec;

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

  /*
   * Get read timeout.
   */
  case BIOCGRTIMEOUT32: {         /* struct user32_timeval */
    struct user32_timeval tv;

    bzero(&tv, sizeof(tv));
    tv.tv_sec = d->bd_rtout / hz;
    tv.tv_usec = (d->bd_rtout % hz) * tick;
    bcopy(&tv, addr, sizeof(tv));
    break;
  }

  case BIOCGRTIMEOUT64: {         /* struct user64_timeval */
    struct user64_timeval tv;

    bzero(&tv, sizeof(tv));
    tv.tv_sec = d->bd_rtout / hz;
    tv.tv_usec = (d->bd_rtout % hz) * tick;
    bcopy(&tv, addr, sizeof(tv));
    break;
  }

  /*
   * Get packet stats.
   */
  case BIOCGSTATS: {              /* struct bpf_stat */
    struct bpf_stat bs;

    bzero(&bs, sizeof(bs));
    bs.bs_recv = d->bd_rcount;
    bs.bs_drop = d->bd_dcount;
    bcopy(&bs, addr, sizeof(bs));
    break;
  }

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

  case BIOCVERSION: {             /* struct bpf_version */
    struct bpf_version bv;

    bzero(&bv, sizeof(bv));
    bv.bv_major = BPF_MAJOR_VERSION;
    bv.bv_minor = BPF_MINOR_VERSION;
    bcopy(&bv, addr, sizeof(bv));
    break;
  }

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

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

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

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

  /*
   * Set traffic service class
   */
  case BIOCSETTC: {               /* int */
    int tc;

    bcopy(addr, &tc, sizeof(int));
    error = bpf_set_traffic_class(d, tc);
    break;
  }

  /*
   * Get traffic service class
   */
  case BIOCGETTC:                 /* int */
    bcopy(&d->bd_traffic_class, addr, sizeof(int));
    break;

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

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

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

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

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

    bcopy(addr, &sig, sizeof(u_int));

    if (sig >= NSIG) {
      error = EINVAL;
    } else {
      d->bd_sig = sig;
    }
    break;
  }
  case BIOCGRSIG:                 /* u_int */
    bcopy(&d->bd_sig, addr, sizeof(u_int));
    break;
#ifdef __APPLE__
  case BIOCSEXTHDR:               /* u_int */
    bcopy(addr, &int_arg, sizeof(int_arg));
    if (int_arg) {
      d->bd_flags |= BPF_EXTENDED_HDR;
    } else {
      d->bd_flags &= ~BPF_EXTENDED_HDR;
    }
    break;

  case BIOCGIFATTACHCOUNT: {              /* struct ifreq */
    ifnet_t ifp;
    struct bpf_if *bp;

    bcopy(addr, &ifr, sizeof(ifr));
    ifr.ifr_name[IFNAMSIZ - 1] = '\0';
    ifp = ifunit(ifr.ifr_name);
    if (ifp == NULL) {
      error = ENXIO;
      break;
    }
    ifr.ifr_intval = 0;
    for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
      struct bpf_d *bpf_d;

      if (bp->bif_ifp == NULL || bp->bif_ifp != ifp) {
        continue;
      }
      for (bpf_d = bp->bif_dlist; bpf_d;
          bpf_d = bpf_d->bd_next) {
        ifr.ifr_intval += 1;
      }
    }
    bcopy(&ifr, addr, sizeof(ifr));
    break;
  }
  case BIOCGWANTPKTAP:                    /* u_int */
    int_arg = d->bd_flags & BPF_WANT_PKTAP ? 1 : 0;
    bcopy(&int_arg, addr, sizeof(int_arg));
    break;

  case BIOCSWANTPKTAP:                    /* u_int */
    bcopy(addr, &int_arg, sizeof(int_arg));
    if (int_arg) {
      d->bd_flags |= BPF_WANT_PKTAP;
    } else {
      d->bd_flags &= ~BPF_WANT_PKTAP;
    }
    break;
#endif

  case BIOCSHEADDROP:
    bcopy(addr, &int_arg, sizeof(int_arg));
    d->bd_headdrop = int_arg ? 1 : 0;
    break;

  case BIOCGHEADDROP:
    bcopy(&d->bd_headdrop, addr, sizeof(int));
    break;

  case BIOCSTRUNCATE:
    bcopy(addr, &int_arg, sizeof(int_arg));
    if (int_arg) {
      d->bd_flags |=  BPF_TRUNCATE;
    } else {
      d->bd_flags &= ~BPF_TRUNCATE;
    }
    break;

  case BIOCGETUUID:
    bcopy(&d->bd_uuid, addr, sizeof(uuid_t));
    break;

  case BIOCSETUP: {
    struct bpf_setup_args bsa;
    ifnet_t ifp;

    bcopy(addr, &bsa, sizeof(struct bpf_setup_args));
    bsa.bsa_ifname[IFNAMSIZ - 1] = 0;
    ifp = ifunit(bsa.bsa_ifname);
    if (ifp == NULL) {
      error = ENXIO;
      os_log_info(OS_LOG_DEFAULT,
          "%s: ifnet not found for %s error %d",
          __func__, bsa.bsa_ifname, error);
      break;
    }

    error = bpf_setup(d, bsa.bsa_uuid, ifp);
    break;
  }
  case BIOCSPKTHDRV2:
    bcopy(addr, &int_arg, sizeof(int_arg));
    if (int_arg != 0) {
      d->bd_flags |= BPF_PKTHDRV2;
    } else {
      d->bd_flags &= ~BPF_PKTHDRV2;
    }
    break;

  case BIOCGPKTHDRV2:
    int_arg = d->bd_flags & BPF_PKTHDRV2 ? 1 : 0;
    bcopy(&int_arg, addr, sizeof(int));
    break;
  }

  bpf_release_d(d);
  lck_mtx_unlock(bpf_mlock);

  return error;
}

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

  while (d->bd_hbuf_read != 0) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  if ((d->bd_flags & BPF_CLOSING) != 0) {
    return ENXIO;
  }

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

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

    if (cmd == BIOCSETF32 || cmd == BIOCSETF64) {
      reset_d(d);
    }

    if (old != 0) {
      FREE(old, M_DEVBUF);
    }

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

/*
 * Detach a file from its current interface (if attached at all) and attach
 * to the interface indicated by the name stored in ifr.
 * Return an errno or 0.
 */
static int
bpf_setif(struct bpf_d *d, ifnet_t theywant, bool do_reset, bool has_hbuf_read)
{
  struct bpf_if *bp;
  int error;

  while (d->bd_hbuf_read != 0 && !has_hbuf_read) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  if ((d->bd_flags & BPF_CLOSING) != 0) {
    return ENXIO;
  }

  /*
   * Look through attached interfaces for the named one.
   */
  for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
    struct ifnet *ifp = bp->bif_ifp;

    if (ifp == 0 || ifp != theywant) {
      continue;
    }
    /*
     * Do not use DLT_PKTAP, unless requested explicitly
     */
    if (bp->bif_dlt == DLT_PKTAP && !(d->bd_flags & BPF_WANT_PKTAP)) {
      continue;
    }
    /*
     * Skip the coprocessor interface
     */
    if (!intcoproc_unrestricted && IFNET_IS_INTCOPROC(ifp)) {
      continue;
    }
    /*
     * We found the requested interface.
     * Allocate the packet buffers.
     */
    error = bpf_allocbufs(d);
    if (error != 0) {
      return error;
    }
    /*
     * Detach if attached to something else.
     */
    if (bp != d->bd_bif) {
      if (d->bd_bif != NULL) {
        if (bpf_detachd(d, 0) != 0) {
          return ENXIO;
        }
      }
      if (bpf_attachd(d, bp) != 0) {
        return ENXIO;
      }
    }
    if (do_reset) {
      reset_d(d);
    }
    return 0;
  }
  /* Not found. */
  return ENXIO;
}

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

  bcopy(addr, &bfl, sizeof(bfl));
  if (proc_is64bit(p)) {
    dlist = (user_addr_t)bfl.bfl_u.bflu_pad;
  } else {
    dlist = CAST_USER_ADDR_T(bfl.bfl_u.bflu_list);
  }

  ifp = d->bd_bif->bif_ifp;
  n = 0;
  error = 0;

  for (bp = bpf_iflist; bp; bp = bp->bif_next) {
    if (bp->bif_ifp != ifp) {
      continue;
    }
    /*
     * Do not use DLT_PKTAP, unless requested explicitly
     */
    if (bp->bif_dlt == DLT_PKTAP && !(d->bd_flags & BPF_WANT_PKTAP)) {
      continue;
    }
    if (dlist != USER_ADDR_NULL) {
      if (n >= bfl.bfl_len) {
        return ENOMEM;
      }
      error = copyout(&bp->bif_dlt, dlist,
          sizeof(bp->bif_dlt));
      if (error != 0) {
        break;
      }
      dlist += sizeof(bp->bif_dlt);
    }
    n++;
  }
  bfl.bfl_len = n;
  bcopy(&bfl, addr, sizeof(bfl));

  return error;
}

/*
 * Set the data link type of a BPF instance.
 */
static int
bpf_setdlt(struct bpf_d *d, uint32_t dlt)
{
  int error, opromisc;
  struct ifnet *ifp;
  struct bpf_if *bp;

  if (d->bd_bif->bif_dlt == dlt) {
    return 0;
  }

  while (d->bd_hbuf_read != 0) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  if ((d->bd_flags & BPF_CLOSING) != 0) {
    return ENXIO;
  }

  ifp = d->bd_bif->bif_ifp;
  for (bp = bpf_iflist; bp; bp = bp->bif_next) {
    if (bp->bif_ifp == ifp && bp->bif_dlt == dlt) {
      /*
       * Do not use DLT_PKTAP, unless requested explicitly
       */
      if (bp->bif_dlt == DLT_PKTAP &&
          !(d->bd_flags & BPF_WANT_PKTAP)) {
        continue;
      }
      break;
    }
  }
  if (bp != NULL) {
    opromisc = d->bd_promisc;
    if (bpf_detachd(d, 0) != 0) {
      return ENXIO;
    }
    error = bpf_attachd(d, bp);
    if (error) {
      printf("bpf_setdlt: bpf_attachd %s%d failed (%d)\n",
          ifnet_name(bp->bif_ifp), ifnet_unit(bp->bif_ifp),
          error);
      return error;
    }
    reset_d(d);
    if (opromisc) {
      lck_mtx_unlock(bpf_mlock);
      error = ifnet_set_promiscuous(bp->bif_ifp, 1);
      lck_mtx_lock(bpf_mlock);
      if (error) {
        printf("%s: ifpromisc %s%d failed (%d)\n",
            __func__, ifnet_name(bp->bif_ifp),
            ifnet_unit(bp->bif_ifp), error);
      } else {
        d->bd_promisc = 1;
      }
    }
  }
  return bp == NULL ? EINVAL : 0;
}

static int
bpf_set_traffic_class(struct bpf_d *d, int tc)
{
  int error = 0;

  if (!SO_VALID_TC(tc)) {
    error = EINVAL;
  } else {
    d->bd_traffic_class = tc;
  }

  return error;
}

static void
bpf_set_packet_service_class(struct mbuf *m, int tc)
{
  if (!(m->m_flags & M_PKTHDR)) {
    return;
  }

  VERIFY(SO_VALID_TC(tc));
  (void) m_set_service_class(m, so_tc2msc(tc));
}

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

  lck_mtx_lock(bpf_mlock);

  d = bpf_dtab[minor(dev)];
  if (d == NULL || d == BPF_DEV_RESERVED ||
      (d->bd_flags & BPF_CLOSING) != 0) {
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  bpf_acquire_d(d);

  if (d->bd_bif == NULL) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  while (d->bd_hbuf_read != 0) {
    msleep((caddr_t)d, bpf_mlock, PRINET, "bpf_reading", NULL);
  }

  if ((d->bd_flags & BPF_CLOSING) != 0) {
    bpf_release_d(d);
    lck_mtx_unlock(bpf_mlock);
    return ENXIO;
  }

  switch (which) {
  case FREAD:
    if (d->bd_hlen != 0 ||
        ((d->bd_immediate ||
        d->bd_state == BPF_TIMED_OUT) && d->bd_slen != 0)) {
      ret = 1;         /* read has data to return */
    } else {
      /*
       * Read has no data to return.
       * Make the select wait, and start a timer if
       * necessary.
       */
      selrecord(p, &d->bd_sel, wql);
      bpf_start_timer(d);
    }
    break;

  case FWRITE:
    /* can't determine whether a write would block */
    ret = 1;
    break;
  }

  bpf_release_d(d);
  lck_mtx_unlock(bpf_mlock);

  return ret;
}

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

SECURITY_READ_ONLY_EARLY(struct filterops) bpfread_filtops = {
  .f_isfd = 1,
  .f_detach = filt_bpfdetach,
  .f_event = filt_bpfread,
  .f_touch = filt_bpftouch,
  .f_process = filt_bpfprocess,
};

static int
filt_bpfread_common(struct knote *kn, struct kevent_qos_s *kev, struct bpf_d *d)
{
  int ready = 0;
  int64_t data = 0;

  if (d->bd_immediate) {
    /*
     * If there's data in the hold buffer, it's the
     * amount of data a read will return.
     *
     * If there's no data in the hold buffer, but
     * there's data in the store buffer, a read will
     * immediately rotate the store buffer to the
     * hold buffer, the amount of data in the store
     * buffer is the amount of data a read will
     * return.
     *
     * If there's no data in either buffer, we're not
     * ready to read.
     */
    data = (d->bd_hlen == 0 || d->bd_hbuf_read != 0 ?
        d->bd_slen : d->bd_hlen);
    int64_t lowwat = knote_low_watermark(kn);
    if (lowwat > d->bd_bufsize) {
      lowwat = d->bd_bufsize;
    }
    ready = (data >= lowwat);
  } else {
    /*
     * If there's data in the hold buffer, it's the
     * amount of data a read will return.
     *
     * If there's no data in the hold buffer, but
     * there's data in the store buffer, if the
     * timer has expired a read will immediately
     * rotate the store buffer to the hold buffer,
     * so the amount of data in the store buffer is
     * the amount of data a read will return.
     *
     * If there's no data in either buffer, or there's
     * no data in the hold buffer and the timer hasn't
     * expired, we're not ready to read.
     */
    data = ((d->bd_hlen == 0 || d->bd_hbuf_read != 0) &&
        d->bd_state == BPF_TIMED_OUT ? d->bd_slen : d->bd_hlen);
    ready = (data > 0);
  }
  if (!ready) {
    bpf_start_timer(d);
  } else if (kev) {
    knote_fill_kevent(kn, kev, data);
  }

  return ready;
}

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

  /*
   * Is this device a bpf?
   */
  if (major(dev) != CDEV_MAJOR || kn->kn_filter != EVFILT_READ) {
    knote_set_error(kn, EINVAL);
    return 0;
  }

  lck_mtx_lock(bpf_mlock);

  d = bpf_dtab[minor(dev)];

  if (d == NULL || d == BPF_DEV_RESERVED ||
      (d->bd_flags & BPF_CLOSING) != 0 ||
      d->bd_bif == NULL) {
    lck_mtx_unlock(bpf_mlock);
    knote_set_error(kn, ENXIO);
    return 0;
  }

  kn->kn_hook = d;
  kn->kn_filtid = EVFILTID_BPFREAD;
  KNOTE_ATTACH(&d->bd_sel.si_note, kn);
  d->bd_flags |= BPF_KNOTE;

  /* capture the current state */
  res = filt_bpfread_common(kn, NULL, d);

  lck_mtx_unlock(bpf_mlock);

  return res;
}

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

  lck_mtx_lock(bpf_mlock);
  if (d->bd_flags & BPF_KNOTE) {
    KNOTE_DETACH(&d->bd_sel.si_note, kn);
    d->bd_flags &= ~BPF_KNOTE;
  }
  lck_mtx_unlock(bpf_mlock);
}

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

  return filt_bpfread_common(kn, NULL, d);
}

static int
filt_bpftouch(struct knote *kn, struct kevent_qos_s *kev)
{
  struct bpf_d *d = (struct bpf_d *)kn->kn_hook;
  int res;

  lck_mtx_lock(bpf_mlock);

  /* save off the lowat threshold and flag */
  kn->kn_sdata = kev->data;
  kn->kn_sfflags = kev->fflags;

  /* output data will be re-generated here */
  res = filt_bpfread_common(kn, NULL, d);

  lck_mtx_unlock(bpf_mlock);

  return res;
}

static int
filt_bpfprocess(struct knote *kn, struct kevent_qos_s *kev)
{
  struct bpf_d *d = (struct bpf_d *)kn->kn_hook;
  int res;

  lck_mtx_lock(bpf_mlock);
  res = filt_bpfread_common(kn, kev, d);
  lck_mtx_unlock(bpf_mlock);

  return res;
}

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

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

static inline void
bpf_tap_imp(
  ifnet_t         ifp,
  u_int32_t       dlt,
  struct bpf_packet *bpf_pkt,
  int             outbound)
{
  struct bpf_d    *d;
  u_int slen;
  struct bpf_if *bp;

  /*
   * It's possible that we get here after the bpf descriptor has been
   * detached from the interface; in such a case we simply return.
   * Lock ordering is important since we can be called asynchronously
   * (from IOKit) to process an inbound packet; when that happens
   * we would have been holding its "gateLock" and will be acquiring
   * "bpf_mlock" upon entering this routine.  Due to that, we release
   * "bpf_mlock" prior to calling ifnet_set_promiscuous (which will
   * acquire "gateLock" in the IOKit), in order to avoid a deadlock
   * when a ifnet_set_promiscuous request simultaneously collides with
   * an inbound packet being passed into the tap callback.
   */
  lck_mtx_lock(bpf_mlock);
  if (ifp->if_bpf == NULL) {
    lck_mtx_unlock(bpf_mlock);
    return;
  }
  for (bp = ifp->if_bpf; bp != NULL; bp = bp->bif_next) {
    if (bp->bif_ifp != ifp) {
      /* wrong interface */
      bp = NULL;
      break;
    }
    if (dlt == 0 || bp->bif_dlt == dlt) {
      /* tapping default DLT or DLT matches */
      break;
    }
  }
  if (bp == NULL) {
    goto done;
  }
  for (d = bp->bif_dlist; d; d = d->bd_next) {
    struct bpf_packet *bpf_pkt_saved = bpf_pkt;
    struct bpf_packet bpf_pkt_tmp;
    struct pktap_header_buffer bpfp_header_tmp;

    if (outbound && !d->bd_seesent) {
      continue;
    }

    ++d->bd_rcount;
    slen = bpf_filter(d->bd_filter, (u_char *)bpf_pkt,
        bpf_pkt->bpfp_total_length, 0);
    if (bp->bif_ifp->if_type == IFT_PKTAP &&
        bp->bif_dlt == DLT_PKTAP) {
      /*
       * Need to copy the bpf_pkt because the conversion
       * to v2 pktap header modifies the content of the
       * bpfp_header
       */
      if ((d->bd_flags & BPF_PKTHDRV2) &&
          bpf_pkt->bpfp_header_length <= sizeof(bpfp_header_tmp)) {
        bpf_pkt_tmp = *bpf_pkt;

        bpf_pkt = &bpf_pkt_tmp;

        memcpy(&bpfp_header_tmp, bpf_pkt->bpfp_header,
            bpf_pkt->bpfp_header_length);

        bpf_pkt->bpfp_header = &bpfp_header_tmp;

        convert_to_pktap_header_to_v2(bpf_pkt,
            !!(d->bd_flags & BPF_TRUNCATE));
      }

      if (d->bd_flags & BPF_TRUNCATE) {
        slen = min(slen,
            get_pkt_trunc_len((u_char *)bpf_pkt,
            bpf_pkt->bpfp_total_length));
      }
    }
    if (slen != 0) {
      catchpacket(d, bpf_pkt, slen, outbound);
    }
    bpf_pkt = bpf_pkt_saved;
  }

done:
  lck_mtx_unlock(bpf_mlock);
}

static inline void
bpf_tap_mbuf(
  ifnet_t         ifp,
  u_int32_t       dlt,
  mbuf_t          m,
  void*           hdr,
  size_t          hlen,
  int             outbound)
{
  struct bpf_packet bpf_pkt;
  struct mbuf *m0;

  if (ifp->if_bpf == NULL) {
    /* quickly check without taking lock */
    return;
  }
  bpf_pkt.bpfp_type = BPF_PACKET_TYPE_MBUF;
  bpf_pkt.bpfp_mbuf = m;
  bpf_pkt.bpfp_total_length = 0;
  for (m0 = m; m0 != NULL; m0 = m0->m_next) {
    bpf_pkt.bpfp_total_length += m0->m_len;
  }
  bpf_pkt.bpfp_header = hdr;
  if (hdr != NULL) {
    bpf_pkt.bpfp_total_length += hlen;
    bpf_pkt.bpfp_header_length = hlen;
  } else {
    bpf_pkt.bpfp_header_length = 0;
  }
  bpf_tap_imp(ifp, dlt, &bpf_pkt, outbound);
}

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

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

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

  return 0;
}


static errno_t
bpf_copydata(struct bpf_packet *pkt, size_t off, size_t len, void* out_data)
{
  errno_t err = 0;
  if (pkt->bpfp_type == BPF_PACKET_TYPE_MBUF) {
    err = mbuf_copydata(pkt->bpfp_mbuf, off, len, out_data);
  } else {
    err = EINVAL;
  }

  return err;
}

static void
copy_bpf_packet(struct bpf_packet * pkt, void * dst, size_t len)
{
  /* copy the optional header */
  if (pkt->bpfp_header_length != 0) {
    size_t  count = min(len, pkt->bpfp_header_length);
    bcopy(pkt->bpfp_header, dst, count);
    len -= count;
    dst += count;
  }
  if (len == 0) {
    /* nothing past the header */
    return;
  }
  /* copy the packet */
  switch (pkt->bpfp_type) {
  case BPF_PACKET_TYPE_MBUF:
    bpf_mcopy(pkt->bpfp_mbuf, dst, len);
    break;
  default:
    break;
  }
}

static uint16_t
get_esp_trunc_len(__unused struct bpf_packet *pkt, __unused uint16_t off,
    const uint16_t remaining_caplen)
{
  /*
   * For some reason tcpdump expects to have one byte beyond the ESP header
   */
  uint16_t trunc_len = ESP_HDR_SIZE + 1;

  if (trunc_len > remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_isakmp_trunc_len(__unused struct bpf_packet *pkt, __unused uint16_t off,
    const uint16_t remaining_caplen)
{
  /*
   * Include the payload generic header
   */
  uint16_t trunc_len = ISAKMP_HDR_SIZE;

  if (trunc_len > remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_isakmp_natt_trunc_len(struct bpf_packet *pkt, uint16_t off,
    const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t trunc_len = 0;
  char payload[remaining_caplen];

  err = bpf_copydata(pkt, off, remaining_caplen, payload);
  if (err != 0) {
    return remaining_caplen;
  }
  /*
   * They are three cases:
   * - IKE: payload start with 4 bytes header set to zero before ISAKMP header
   * - keep alive: 1 byte payload
   * - otherwise it's ESP
   */
  if (remaining_caplen >= 4 &&
      payload[0] == 0 && payload[1] == 0 &&
      payload[2] == 0 && payload[3] == 0) {
    trunc_len = 4 + get_isakmp_trunc_len(pkt, off + 4, remaining_caplen - 4);
  } else if (remaining_caplen == 1) {
    trunc_len = 1;
  } else {
    trunc_len = get_esp_trunc_len(pkt, off, remaining_caplen);
  }

  if (trunc_len > remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_udp_trunc_len(struct bpf_packet *pkt, uint16_t off, const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t trunc_len = sizeof(struct udphdr); /* By default no UDP payload */

  if (trunc_len >= remaining_caplen) {
    return remaining_caplen;
  }

  struct udphdr udphdr;
  err = bpf_copydata(pkt, off, sizeof(struct udphdr), &udphdr);
  if (err != 0) {
    return remaining_caplen;
  }

  u_short sport, dport;

  sport = EXTRACT_SHORT(&udphdr.uh_sport);
  dport = EXTRACT_SHORT(&udphdr.uh_dport);

  if (dport == PORT_DNS || sport == PORT_DNS) {
    /*
     * Full UDP payload for DNS
     */
    trunc_len = remaining_caplen;
  } else if ((sport == PORT_BOOTPS && dport == PORT_BOOTPC) ||
      (sport == PORT_BOOTPC && dport == PORT_BOOTPS)) {
    /*
     * Full UDP payload for BOOTP and DHCP
     */
    trunc_len = remaining_caplen;
  } else if (dport == PORT_ISAKMP && sport == PORT_ISAKMP) {
    /*
     * Return the ISAKMP header
     */
    trunc_len += get_isakmp_trunc_len(pkt, off + sizeof(struct udphdr),
        remaining_caplen - sizeof(struct udphdr));
  } else if (dport == PORT_ISAKMP_NATT && sport == PORT_ISAKMP_NATT) {
    trunc_len += get_isakmp_natt_trunc_len(pkt, off + sizeof(struct udphdr),
        remaining_caplen - sizeof(struct udphdr));
  }
  if (trunc_len >= remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_tcp_trunc_len(struct bpf_packet *pkt, uint16_t off, const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t trunc_len = sizeof(struct tcphdr); /* By default no TCP payload */
  if (trunc_len >= remaining_caplen) {
    return remaining_caplen;
  }

  struct tcphdr tcphdr;
  err = bpf_copydata(pkt, off, sizeof(struct tcphdr), &tcphdr);
  if (err != 0) {
    return remaining_caplen;
  }

  u_short sport, dport;
  sport = EXTRACT_SHORT(&tcphdr.th_sport);
  dport = EXTRACT_SHORT(&tcphdr.th_dport);

  if (dport == PORT_DNS || sport == PORT_DNS) {
    /*
     * Full TCP payload  for DNS
     */
    trunc_len = remaining_caplen;
  } else {
    trunc_len = tcphdr.th_off << 2;
  }
  if (trunc_len >= remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_proto_trunc_len(uint8_t proto, struct bpf_packet *pkt, uint16_t off, const uint16_t remaining_caplen)
{
  uint16_t trunc_len;

  switch (proto) {
  case IPPROTO_ICMP: {
    /*
     * Full IMCP payload
     */
    trunc_len = remaining_caplen;
    break;
  }
  case IPPROTO_ICMPV6: {
    /*
     * Full IMCPV6 payload
     */
    trunc_len = remaining_caplen;
    break;
  }
  case IPPROTO_IGMP: {
    /*
     * Full IGMP payload
     */
    trunc_len = remaining_caplen;
    break;
  }
  case IPPROTO_UDP: {
    trunc_len = get_udp_trunc_len(pkt, off, remaining_caplen);
    break;
  }
  case IPPROTO_TCP: {
    trunc_len = get_tcp_trunc_len(pkt, off, remaining_caplen);
    break;
  }
  case IPPROTO_ESP: {
    trunc_len = get_esp_trunc_len(pkt, off, remaining_caplen);
    break;
  }
  default: {
    /*
     * By default we only include the IP header
     */
    trunc_len = 0;
    break;
  }
  }
  if (trunc_len >= remaining_caplen) {
    return remaining_caplen;
  }

  return trunc_len;
}

static uint16_t
get_ip_trunc_len(struct bpf_packet *pkt, uint16_t off, const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t iplen = sizeof(struct ip);
  if (iplen >= remaining_caplen) {
    return remaining_caplen;
  }

  struct ip iphdr;
  err =  bpf_copydata(pkt, off, sizeof(struct ip), &iphdr);
  if (err != 0) {
    return remaining_caplen;
  }

  uint8_t proto = 0;

  iplen = iphdr.ip_hl << 2;
  if (iplen >= remaining_caplen) {
    return remaining_caplen;
  }

  proto = iphdr.ip_p;
  iplen += get_proto_trunc_len(proto, pkt, off + iplen, remaining_caplen - iplen);

  if (iplen >= remaining_caplen) {
    return remaining_caplen;
  }

  return iplen;
}

static uint16_t
get_ip6_trunc_len(struct bpf_packet *pkt, uint16_t off, const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t iplen = sizeof(struct ip6_hdr);
  if (iplen >= remaining_caplen) {
    return remaining_caplen;
  }

  struct ip6_hdr ip6hdr;
  err = bpf_copydata(pkt, off, sizeof(struct ip6_hdr), &ip6hdr);
  if (err != 0) {
    return remaining_caplen;
  }

  uint8_t proto = 0;

  /*
   * TBD: process the extension headers
   */
  proto = ip6hdr.ip6_nxt;
  iplen += get_proto_trunc_len(proto, pkt, off + iplen, remaining_caplen - iplen);

  if (iplen >= remaining_caplen) {
    return remaining_caplen;
  }

  return iplen;
}

static uint16_t
get_ether_trunc_len(struct bpf_packet *pkt, int off, const uint16_t remaining_caplen)
{
  int err = 0;
  uint16_t ethlen = sizeof(struct ether_header);
  if (ethlen >= remaining_caplen) {
    return remaining_caplen;
  }

  struct ether_header eh;
  u_short type;
  err = bpf_copydata(pkt, off, sizeof(struct ether_header), &eh);
  if (err != 0) {
    return remaining_caplen;
  }

  type = EXTRACT_SHORT(&eh.ether_type);
  /* Include full ARP */
  if (type == ETHERTYPE_ARP) {
    ethlen = remaining_caplen;
  } else if (type != ETHERTYPE_IP && type != ETHERTYPE_IPV6) {
    ethlen = min(BPF_MIN_PKT_SIZE, remaining_caplen);
  } else {
    if (type == ETHERTYPE_IP) {
      ethlen += get_ip_trunc_len(pkt, sizeof(struct ether_header),
          remaining_caplen);
    } else if (type == ETHERTYPE_IPV6) {
      ethlen += get_ip6_trunc_len(pkt, sizeof(struct ether_header),
          remaining_caplen);
    }
  }
  return ethlen;
}

static uint32_t
get_pkt_trunc_len(u_char *p, u_int len)
{
  struct bpf_packet *pkt = (struct bpf_packet *)(void *) p;
  struct pktap_header *pktap = (struct pktap_header *) (pkt->bpfp_header);
  uint32_t out_pkt_len = 0, tlen = 0;
  /*
   * pktap->pth_frame_pre_length is L2 header length and accounts
   * for both pre and pre_adjust.
   * pktap->pth_length is sizeof(pktap_header) (excl the pre/pre_adjust)
   * pkt->bpfp_header_length is (pktap->pth_length + pre_adjust)
   * pre is the offset to the L3 header after the bpfp_header, or length
   * of L2 header after bpfp_header, if present.
   */
  int32_t pre = pktap->pth_frame_pre_length -
      (pkt->bpfp_header_length - pktap->pth_length);

  /* Length of the input packet starting from  L3 header */
  uint32_t in_pkt_len = len - pkt->bpfp_header_length - pre;
  if (pktap->pth_protocol_family == AF_INET ||
      pktap->pth_protocol_family == AF_INET6) {
    /* Contains L2 header */
    if (pre > 0) {
      if (pre < (int32_t)sizeof(struct ether_header)) {
        goto too_short;
      }

      out_pkt_len = get_ether_trunc_len(pkt, 0, in_pkt_len);
    } else if (pre == 0) {
      if (pktap->pth_protocol_family == AF_INET) {
        out_pkt_len = get_ip_trunc_len(pkt, pre, in_pkt_len);
      } else if (pktap->pth_protocol_family == AF_INET6) {
        out_pkt_len = get_ip6_trunc_len(pkt, pre, in_pkt_len);
      }
    } else {
      /* Ideally pre should be >= 0. This is an exception */
      out_pkt_len = min(BPF_MIN_PKT_SIZE, in_pkt_len);
    }
  } else {
    if (pktap->pth_iftype == IFT_ETHER) {
      if (in_pkt_len < sizeof(struct ether_header)) {
        goto too_short;
      }
      /* At most include the Ethernet header and 16 bytes */
      out_pkt_len = MIN(sizeof(struct ether_header) + 16,
          in_pkt_len);
    } else {
      /*
       * For unknown protocols include at most 16 bytes
       */
      out_pkt_len = MIN(16, in_pkt_len);
    }
  }
done:
  tlen = pkt->bpfp_header_length + out_pkt_len + pre;
  return tlen;
too_short:
  out_pkt_len = in_pkt_len;
  goto done;
}

/*
 * Move the packet data from interface memory (pkt) into the
 * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
 * otherwise 0.
 */
static void
catchpacket(struct bpf_d *d, struct bpf_packet * pkt,
    u_int snaplen, int outbound)
{
  struct bpf_hdr *hp;
  struct bpf_hdr_ext *ehp;
  int totlen, curlen;
  int hdrlen, caplen;
  int do_wakeup = 0;
  u_char *payload;
  struct timeval tv;

  hdrlen = (d->bd_flags & BPF_EXTENDED_HDR) ? d->bd_bif->bif_exthdrlen :
      d->bd_bif->bif_hdrlen;
  /*
   * Figure out how many bytes to move.  If the packet is
   * greater or equal to the snapshot length, transfer that
   * much.  Otherwise, transfer the whole packet (unless
   * we hit the buffer size limit).
   */
  totlen = hdrlen + min(snaplen, pkt->bpfp_total_length);
  if (totlen > d->bd_bufsize) {
    totlen = d->bd_bufsize;
  }

  if (hdrlen > totlen) {
    return;
  }

  /*
   * Round up the end of the previous packet to the next longword.
   */
  curlen = BPF_WORDALIGN(d->bd_slen);
  if (curlen + totlen > d->bd_bufsize) {
    /*
     * This packet will overflow the storage buffer.
     * Rotate the buffers if we can, then wakeup any
     * pending reads.
     *
     * We cannot rotate buffers if a read is in progress
     * so drop the packet
     */
    if (d->bd_hbuf_read != 0) {
      ++d->bd_dcount;
      return;
    }

    if (d->bd_fbuf == NULL) {
      if (d->bd_headdrop == 0) {
        /*
         * We haven't completed the previous read yet,
         * so drop the packet.
         */
        ++d->bd_dcount;
        return;
      }
      /*
       * Drop the hold buffer as it contains older packets
       */
      d->bd_dcount += d->bd_hcnt;
      d->bd_fbuf = d->bd_hbuf;
      ROTATE_BUFFERS(d);
    } else {
      ROTATE_BUFFERS(d);
    }
    do_wakeup = 1;
    curlen = 0;
  } else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT) {
    /*
     * Immediate mode is set, or the read timeout has
     * already expired during a select call. A packet
     * arrived, so the reader should be woken up.
     */
    do_wakeup = 1;
  }

  /*
   * Append the bpf header.
   */
  microtime(&tv);
  if (d->bd_flags & BPF_EXTENDED_HDR) {
    struct mbuf *m;

    m = (pkt->bpfp_type == BPF_PACKET_TYPE_MBUF)
        ? pkt->bpfp_mbuf : NULL;
    ehp = (struct bpf_hdr_ext *)(void *)(d->bd_sbuf + curlen);
    memset(ehp, 0, sizeof(*ehp));
    ehp->bh_tstamp.tv_sec = tv.tv_sec;
    ehp->bh_tstamp.tv_usec = tv.tv_usec;

    ehp->bh_datalen = pkt->bpfp_total_length;
    ehp->bh_hdrlen = hdrlen;
    caplen = ehp->bh_caplen = totlen - hdrlen;
    if (m == NULL) {
      if (outbound) {
        ehp->bh_flags |= BPF_HDR_EXT_FLAGS_DIR_OUT;
      } else {
        ehp->bh_flags |= BPF_HDR_EXT_FLAGS_DIR_IN;
      }
    } else if (outbound) {
      ehp->bh_flags |= BPF_HDR_EXT_FLAGS_DIR_OUT;

      /* only do lookups on non-raw INPCB */
      if ((m->m_pkthdr.pkt_flags & (PKTF_FLOW_ID |
          PKTF_FLOW_LOCALSRC | PKTF_FLOW_RAWSOCK)) ==
          (PKTF_FLOW_ID | PKTF_FLOW_LOCALSRC) &&
          m->m_pkthdr.pkt_flowsrc == FLOWSRC_INPCB) {
        ehp->bh_flowid = m->m_pkthdr.pkt_flowid;
        ehp->bh_proto = m->m_pkthdr.pkt_proto;
      }
      ehp->bh_svc = so_svc2tc(m->m_pkthdr.pkt_svc);
      if (m->m_pkthdr.pkt_flags & PKTF_TCP_REXMT) {
        ehp->bh_pktflags |= BPF_PKTFLAGS_TCP_REXMT;
      }
      if (m->m_pkthdr.pkt_flags & PKTF_START_SEQ) {
        ehp->bh_pktflags |= BPF_PKTFLAGS_START_SEQ;
      }
      if (m->m_pkthdr.pkt_flags & PKTF_LAST_PKT) {
        ehp->bh_pktflags |= BPF_PKTFLAGS_LAST_PKT;
      }
      if (m->m_pkthdr.pkt_flags & PKTF_VALID_UNSENT_DATA) {
        ehp->bh_unsent_bytes =
            m->m_pkthdr.bufstatus_if;
        ehp->bh_unsent_snd =
            m->m_pkthdr.bufstatus_sndbuf;
      }
    } else {
      ehp->bh_flags |= BPF_HDR_EXT_FLAGS_DIR_IN;
    }
    payload = (u_char *)ehp + hdrlen;
  } else {
    hp = (struct bpf_hdr *)(void *)(d->bd_sbuf + curlen);
    hp->bh_tstamp.tv_sec = tv.tv_sec;
    hp->bh_tstamp.tv_usec = tv.tv_usec;
    hp->bh_datalen = pkt->bpfp_total_length;
    hp->bh_hdrlen = hdrlen;
    caplen = hp->bh_caplen = totlen - hdrlen;
    payload = (u_char *)hp + hdrlen;
  }
  /*
   * Copy the packet data into the store buffer and update its length.
   */
  copy_bpf_packet(pkt, payload, caplen);
  d->bd_slen = curlen + totlen;
  d->bd_scnt += 1;

  if (do_wakeup) {
    bpf_wakeup(d);
  }
}

/*
 * Initialize all nonzero fields of a descriptor.
 */
static int
bpf_allocbufs(struct bpf_d *d)
{
  if (d->bd_sbuf != NULL) {
    FREE(d->bd_sbuf, M_DEVBUF);
    d->bd_sbuf = NULL;
  }
  if (d->bd_hbuf != NULL) {
    FREE(d->bd_hbuf, M_DEVBUF);
    d->bd_hbuf = NULL;
  }
  if (d->bd_fbuf != NULL) {
    FREE(d->bd_fbuf, M_DEVBUF);
    d->bd_fbuf = NULL;
  }

  d->bd_fbuf = (caddr_t) _MALLOC(d->bd_bufsize, M_DEVBUF, M_WAIT);
  if (d->bd_fbuf == NULL) {
    return ENOBUFS;
  }

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

/*
 * Free buffers currently in use by a descriptor.
 * Called on close.
 */
static void
bpf_freed(struct bpf_d *d)
{
  /*
   * We don't need to lock out interrupts since this descriptor has
   * been detached from its interface and it yet hasn't been marked
   * free.
   */
  if (d->bd_hbuf_read != 0) {
    panic("bpf buffer freed during read");
  }

  if (d->bd_sbuf != 0) {
    FREE(d->bd_sbuf, M_DEVBUF);
    if (d->bd_hbuf != 0) {
      FREE(d->bd_hbuf, M_DEVBUF);
    }
    if (d->bd_fbuf != 0) {
      FREE(d->bd_fbuf, M_DEVBUF);
    }
  }
  if (d->bd_filter) {
    FREE(d->bd_filter, M_DEVBUF);
  }
}

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

errno_t
bpf_attach(
  ifnet_t                 ifp,
  u_int32_t               dlt,
  u_int32_t               hdrlen,
  bpf_send_func   send,
  bpf_tap_func    tap)
{
  struct bpf_if *bp;
  struct bpf_if *bp_new;
  struct bpf_if *bp_before_first = NULL;
  struct bpf_if *bp_first = NULL;
  struct bpf_if *bp_last = NULL;
  boolean_t found;

  bp_new = (struct bpf_if *) _MALLOC(sizeof(*bp_new), M_DEVBUF,
      M_WAIT | M_ZERO);
  if (bp_new == 0) {
    panic("bpfattach");
  }

  lck_mtx_lock(bpf_mlock);

  /*
   * Check if this interface/dlt is already attached. Remember the
   * first and last attachment for this interface, as well as the
   * element before the first attachment.
   */
  found = FALSE;
  for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
    if (bp->bif_ifp != ifp) {
      if (bp_first != NULL) {
        /* no more elements for this interface */
        break;
      }
      bp_before_first = bp;
    } else {
      if (bp->bif_dlt == dlt) {
        found = TRUE;
        break;
      }
      if (bp_first == NULL) {
        bp_first = bp;
      }
      bp_last = bp;
    }
  }
  if (found) {
    lck_mtx_unlock(bpf_mlock);
    printf("bpfattach - %s with dlt %d is already attached\n",
        if_name(ifp), dlt);
    FREE(bp_new, M_DEVBUF);
    return EEXIST;
  }

  bp_new->bif_ifp = ifp;
  bp_new->bif_dlt = dlt;
  bp_new->bif_send = send;
  bp_new->bif_tap = tap;

  if (bp_first == NULL) {
    /* No other entries for this ifp */
    bp_new->bif_next = bpf_iflist;
    bpf_iflist = bp_new;
  } else {
    if (ifnet_type(ifp) == IFT_ETHER && dlt == DLT_EN10MB) {
      /* Make this the first entry for this interface */
      if (bp_before_first != NULL) {
        /*  point the previous to us */
        bp_before_first->bif_next = bp_new;
      } else {
        /* we're the new head */
        bpf_iflist = bp_new;
      }
      bp_new->bif_next = bp_first;
    } else {
      /* Add this after the last entry for this interface */
      bp_new->bif_next = bp_last->bif_next;
      bp_last->bif_next = bp_new;
    }
  }

  /*
   * Compute the length of the bpf header.  This is not necessarily
   * equal to SIZEOF_BPF_HDR because we want to insert spacing such
   * that the network layer header begins on a longword boundary (for
   * performance reasons and to alleviate alignment restrictions).
   */
  bp_new->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;
  bp_new->bif_exthdrlen = BPF_WORDALIGN(hdrlen +
      sizeof(struct bpf_hdr_ext)) - hdrlen;

  /* Take a reference on the interface */
  ifnet_reference(ifp);

  lck_mtx_unlock(bpf_mlock);

#ifndef __APPLE__
  if (bootverbose) {
    printf("bpf: %s attached\n", if_name(ifp));
  }
#endif

  return 0;
}

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

  if (bpf_debug != 0) {
    printf("%s: %s\n", __func__, if_name(ifp));
  }

  lck_mtx_lock(bpf_mlock);

  /*
   * Build the list of devices attached to that interface
   * that we need to free while keeping the lock to maintain
   * the integrity of the interface list
   */
  bp_prev = NULL;
  for (bp = bpf_iflist; bp != NULL; bp = bp_next) {
    bp_next = bp->bif_next;

    if (ifp != bp->bif_ifp) {
      bp_prev = bp;
      continue;
    }
    /* Unlink from the interface list */
    if (bp_prev) {
      bp_prev->bif_next = bp->bif_next;
    } else {
      bpf_iflist = bp->bif_next;
    }

    /* Detach the devices attached to the interface */
    while ((d = bp->bif_dlist) != NULL) {
      /*
       * Take an extra reference to prevent the device
       * from being freed when bpf_detachd() releases
       * the reference for the interface list
       */
      bpf_acquire_d(d);
      bpf_detachd(d, 0);
      bpf_wakeup(d);
      bpf_release_d(d);
    }
    ifnet_release(ifp);
  }

  lck_mtx_unlock(bpf_mlock);
}

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

  if (bpf_devsw_installed == 0) {
    bpf_devsw_installed = 1;
    bpf_mlock_grp_attr = lck_grp_attr_alloc_init();
    bpf_mlock_grp = lck_grp_alloc_init("bpf", bpf_mlock_grp_attr);
    bpf_mlock_attr = lck_attr_alloc_init();
    lck_mtx_init(bpf_mlock, bpf_mlock_grp, bpf_mlock_attr);
    maj = cdevsw_add(CDEV_MAJOR, &bpf_cdevsw);
    if (maj == -1) {
      if (bpf_mlock_attr) {
        lck_attr_free(bpf_mlock_attr);
      }
      if (bpf_mlock_grp) {
        lck_grp_free(bpf_mlock_grp);
      }
      if (bpf_mlock_grp_attr) {
        lck_grp_attr_free(bpf_mlock_grp_attr);
      }

      bpf_mlock = NULL;
      bpf_mlock_attr = NULL;
      bpf_mlock_grp = NULL;
      bpf_mlock_grp_attr = NULL;
      bpf_devsw_installed = 0;
      printf("bpf_init: failed to allocate a major number\n");
      return;
    }

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

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

static int
sysctl_bpf_maxbufsize SYSCTL_HANDLER_ARGS
{
#pragma unused(arg1, arg2)
  int i, err;

  i = bpf_maxbufsize;

  err = sysctl_handle_int(oidp, &i, 0, req);
  if (err != 0 || req->newptr == USER_ADDR_NULL) {
    return err;
  }

  if (i < 0 || i > BPF_MAXSIZE_CAP) {
    i = BPF_MAXSIZE_CAP;
  }

  bpf_maxbufsize = i;
  return err;
}

Coverage Report

Created: 2024-10-03 06:24