The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/bpf.c

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    1 /*
    2  * Copyright (c) 1990, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from the Stanford/CMU enet packet filter,
    6  * (net/enet.c) distributed as part of 4.3BSD, and code contributed
    7  * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
    8  * Berkeley Laboratory.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by the University of
   21  *      California, Berkeley and its contributors.
   22  * 4. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      @(#)bpf.c       8.4 (Berkeley) 1/9/95
   39  *
   40  * $FreeBSD: releng/5.1/sys/net/bpf.c 112463 2003-03-21 15:13:29Z mdodd $
   41  */
   42 
   43 #include "opt_bpf.h"
   44 #include "opt_mac.h"
   45 #include "opt_netgraph.h"
   46 
   47 #include <sys/param.h>
   48 #include <sys/systm.h>
   49 #include <sys/conf.h>
   50 #include <sys/mac.h>
   51 #include <sys/malloc.h>
   52 #include <sys/mbuf.h>
   53 #include <sys/time.h>
   54 #include <sys/proc.h>
   55 #include <sys/signalvar.h>
   56 #include <sys/filio.h>
   57 #include <sys/sockio.h>
   58 #include <sys/ttycom.h>
   59 #include <sys/filedesc.h>
   60 
   61 #include <sys/poll.h>
   62 
   63 #include <sys/socket.h>
   64 #include <sys/vnode.h>
   65 
   66 #include <net/if.h>
   67 #include <net/bpf.h>
   68 #include <net/bpfdesc.h>
   69 
   70 #include <netinet/in.h>
   71 #include <netinet/if_ether.h>
   72 #include <sys/kernel.h>
   73 #include <sys/sysctl.h>
   74 
   75 static MALLOC_DEFINE(M_BPF, "BPF", "BPF data");
   76 
   77 #if defined(DEV_BPF) || defined(NETGRAPH_BPF)
   78 
   79 #define PRINET  26                      /* interruptible */
   80 
   81 /*
   82  * The default read buffer size is patchable.
   83  */
   84 static int bpf_bufsize = 4096;
   85 SYSCTL_INT(_debug, OID_AUTO, bpf_bufsize, CTLFLAG_RW,
   86         &bpf_bufsize, 0, "");
   87 static int bpf_maxbufsize = BPF_MAXBUFSIZE;
   88 SYSCTL_INT(_debug, OID_AUTO, bpf_maxbufsize, CTLFLAG_RW,
   89         &bpf_maxbufsize, 0, "");
   90 
   91 /*
   92  *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
   93  */
   94 static struct bpf_if    *bpf_iflist;
   95 static struct mtx       bpf_mtx;                /* bpf global lock */
   96 
   97 static int      bpf_allocbufs(struct bpf_d *);
   98 static void     bpf_attachd(struct bpf_d *d, struct bpf_if *bp);
   99 static void     bpf_detachd(struct bpf_d *d);
  100 static void     bpf_freed(struct bpf_d *);
  101 static void     bpf_mcopy(const void *, void *, size_t);
  102 static int      bpf_movein(struct uio *, int,
  103                     struct mbuf **, struct sockaddr *, int *);
  104 static int      bpf_setif(struct bpf_d *, struct ifreq *);
  105 static void     bpf_timed_out(void *);
  106 static __inline void
  107                 bpf_wakeup(struct bpf_d *);
  108 static void     catchpacket(struct bpf_d *, u_char *, u_int,
  109                     u_int, void (*)(const void *, void *, size_t));
  110 static void     reset_d(struct bpf_d *);
  111 static int       bpf_setf(struct bpf_d *, struct bpf_program *);
  112 static int      bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
  113 static int      bpf_setdlt(struct bpf_d *, u_int);
  114 
  115 static  d_open_t        bpfopen;
  116 static  d_close_t       bpfclose;
  117 static  d_read_t        bpfread;
  118 static  d_write_t       bpfwrite;
  119 static  d_ioctl_t       bpfioctl;
  120 static  d_poll_t        bpfpoll;
  121 
  122 #define CDEV_MAJOR 23
  123 static struct cdevsw bpf_cdevsw = {
  124         .d_open =       bpfopen,
  125         .d_close =      bpfclose,
  126         .d_read =       bpfread,
  127         .d_write =      bpfwrite,
  128         .d_ioctl =      bpfioctl,
  129         .d_poll =       bpfpoll,
  130         .d_name =       "bpf",
  131         .d_maj =        CDEV_MAJOR,
  132 };
  133 
  134 
  135 static int
  136 bpf_movein(uio, linktype, mp, sockp, datlen)
  137         struct uio *uio;
  138         int linktype, *datlen;
  139         struct mbuf **mp;
  140         struct sockaddr *sockp;
  141 {
  142         struct mbuf *m;
  143         int error;
  144         int len;
  145         int hlen;
  146 
  147         /*
  148          * Build a sockaddr based on the data link layer type.
  149          * We do this at this level because the ethernet header
  150          * is copied directly into the data field of the sockaddr.
  151          * In the case of SLIP, there is no header and the packet
  152          * is forwarded as is.
  153          * Also, we are careful to leave room at the front of the mbuf
  154          * for the link level header.
  155          */
  156         switch (linktype) {
  157 
  158         case DLT_SLIP:
  159                 sockp->sa_family = AF_INET;
  160                 hlen = 0;
  161                 break;
  162 
  163         case DLT_EN10MB:
  164                 sockp->sa_family = AF_UNSPEC;
  165                 /* XXX Would MAXLINKHDR be better? */
  166                 hlen = ETHER_HDR_LEN;
  167                 break;
  168 
  169         case DLT_FDDI:
  170                 sockp->sa_family = AF_IMPLINK;
  171                 hlen = 0;
  172                 break;
  173 
  174         case DLT_RAW:
  175         case DLT_NULL:
  176                 sockp->sa_family = AF_UNSPEC;
  177                 hlen = 0;
  178                 break;
  179 
  180         case DLT_ATM_RFC1483:
  181                 /*
  182                  * en atm driver requires 4-byte atm pseudo header.
  183                  * though it isn't standard, vpi:vci needs to be
  184                  * specified anyway.
  185                  */
  186                 sockp->sa_family = AF_UNSPEC;
  187                 hlen = 12;      /* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
  188                 break;
  189 
  190         case DLT_PPP:
  191                 sockp->sa_family = AF_UNSPEC;
  192                 hlen = 4;       /* This should match PPP_HDRLEN */
  193                 break;
  194 
  195         default:
  196                 return (EIO);
  197         }
  198 
  199         len = uio->uio_resid;
  200         *datlen = len - hlen;
  201         if ((unsigned)len > MCLBYTES)
  202                 return (EIO);
  203 
  204         if (len > MHLEN) {
  205                 m = m_getcl(M_TRYWAIT, MT_DATA, M_PKTHDR);
  206         } else {
  207                 MGETHDR(m, M_TRYWAIT, MT_DATA);
  208         }
  209         if (m == NULL)
  210                 return (ENOBUFS);
  211         m->m_pkthdr.len = m->m_len = len;
  212         m->m_pkthdr.rcvif = NULL;
  213         *mp = m;
  214 
  215         /*
  216          * Make room for link header.
  217          */
  218         if (hlen != 0) {
  219                 m->m_pkthdr.len -= hlen;
  220                 m->m_len -= hlen;
  221 #if BSD >= 199103
  222                 m->m_data += hlen; /* XXX */
  223 #else
  224                 m->m_off += hlen;
  225 #endif
  226                 error = uiomove(sockp->sa_data, hlen, uio);
  227                 if (error)
  228                         goto bad;
  229         }
  230         error = uiomove(mtod(m, void *), len - hlen, uio);
  231         if (!error)
  232                 return (0);
  233 bad:
  234         m_freem(m);
  235         return (error);
  236 }
  237 
  238 /*
  239  * Attach file to the bpf interface, i.e. make d listen on bp.
  240  */
  241 static void
  242 bpf_attachd(d, bp)
  243         struct bpf_d *d;
  244         struct bpf_if *bp;
  245 {
  246         /*
  247          * Point d at bp, and add d to the interface's list of listeners.
  248          * Finally, point the driver's bpf cookie at the interface so
  249          * it will divert packets to bpf.
  250          */
  251         BPFIF_LOCK(bp);
  252         d->bd_bif = bp;
  253         d->bd_next = bp->bif_dlist;
  254         bp->bif_dlist = d;
  255 
  256         *bp->bif_driverp = bp;
  257         BPFIF_UNLOCK(bp);
  258 }
  259 
  260 /*
  261  * Detach a file from its interface.
  262  */
  263 static void
  264 bpf_detachd(d)
  265         struct bpf_d *d;
  266 {
  267         int error;
  268         struct bpf_d **p;
  269         struct bpf_if *bp;
  270 
  271         bp = d->bd_bif;
  272         /*
  273          * Check if this descriptor had requested promiscuous mode.
  274          * If so, turn it off.
  275          */
  276         if (d->bd_promisc) {
  277                 d->bd_promisc = 0;
  278                 error = ifpromisc(bp->bif_ifp, 0);
  279                 if (error != 0 && error != ENXIO) {
  280                         /*
  281                          * ENXIO can happen if a pccard is unplugged
  282                          * Something is really wrong if we were able to put
  283                          * the driver into promiscuous mode, but can't
  284                          * take it out.
  285                          */
  286                         if_printf(bp->bif_ifp,
  287                                 "bpf_detach: ifpromisc failed (%d)\n", error);
  288                 }
  289         }
  290         /* Remove d from the interface's descriptor list. */
  291         BPFIF_LOCK(bp);
  292         p = &bp->bif_dlist;
  293         while (*p != d) {
  294                 p = &(*p)->bd_next;
  295                 if (*p == 0)
  296                         panic("bpf_detachd: descriptor not in list");
  297         }
  298         *p = (*p)->bd_next;
  299         if (bp->bif_dlist == 0)
  300                 /*
  301                  * Let the driver know that there are no more listeners.
  302                  */
  303                 *d->bd_bif->bif_driverp = 0;
  304         BPFIF_UNLOCK(bp);
  305         d->bd_bif = 0;
  306 }
  307 
  308 /*
  309  * Open ethernet device.  Returns ENXIO for illegal minor device number,
  310  * EBUSY if file is open by another process.
  311  */
  312 /* ARGSUSED */
  313 static  int
  314 bpfopen(dev, flags, fmt, td)
  315         dev_t dev;
  316         int flags;
  317         int fmt;
  318         struct thread *td;
  319 {
  320         struct bpf_d *d;
  321 
  322         mtx_lock(&bpf_mtx);
  323         d = dev->si_drv1;
  324         /*
  325          * Each minor can be opened by only one process.  If the requested
  326          * minor is in use, return EBUSY.
  327          */
  328         if (d) {
  329                 mtx_unlock(&bpf_mtx);
  330                 return (EBUSY);
  331         }
  332         dev->si_drv1 = (struct bpf_d *)~0;      /* mark device in use */
  333         mtx_unlock(&bpf_mtx);
  334 
  335         if ((dev->si_flags & SI_NAMED) == 0)
  336                 make_dev(&bpf_cdevsw, minor(dev), UID_ROOT, GID_WHEEL, 0600,
  337                     "bpf%d", dev2unit(dev));
  338         MALLOC(d, struct bpf_d *, sizeof(*d), M_BPF, M_WAITOK | M_ZERO);
  339         dev->si_drv1 = d;
  340         d->bd_bufsize = bpf_bufsize;
  341         d->bd_sig = SIGIO;
  342         d->bd_seesent = 1;
  343 #ifdef MAC
  344         mac_init_bpfdesc(d);
  345         mac_create_bpfdesc(td->td_ucred, d);
  346 #endif
  347         mtx_init(&d->bd_mtx, devtoname(dev), "bpf cdev lock", MTX_DEF);
  348         callout_init(&d->bd_callout, 1);
  349 
  350         return (0);
  351 }
  352 
  353 /*
  354  * Close the descriptor by detaching it from its interface,
  355  * deallocating its buffers, and marking it free.
  356  */
  357 /* ARGSUSED */
  358 static  int
  359 bpfclose(dev, flags, fmt, td)
  360         dev_t dev;
  361         int flags;
  362         int fmt;
  363         struct thread *td;
  364 {
  365         struct bpf_d *d = dev->si_drv1;
  366 
  367         BPFD_LOCK(d);
  368         if (d->bd_state == BPF_WAITING)
  369                 callout_stop(&d->bd_callout);
  370         d->bd_state = BPF_IDLE;
  371         BPFD_UNLOCK(d);
  372         funsetown(&d->bd_sigio);
  373         mtx_lock(&bpf_mtx);
  374         if (d->bd_bif)
  375                 bpf_detachd(d);
  376         mtx_unlock(&bpf_mtx);
  377 #ifdef MAC
  378         mac_destroy_bpfdesc(d);
  379 #endif /* MAC */
  380         bpf_freed(d);
  381         dev->si_drv1 = 0;
  382         free(d, M_BPF);
  383 
  384         return (0);
  385 }
  386 
  387 
  388 /*
  389  * Rotate the packet buffers in descriptor d.  Move the store buffer
  390  * into the hold slot, and the free buffer into the store slot.
  391  * Zero the length of the new store buffer.
  392  */
  393 #define ROTATE_BUFFERS(d) \
  394         (d)->bd_hbuf = (d)->bd_sbuf; \
  395         (d)->bd_hlen = (d)->bd_slen; \
  396         (d)->bd_sbuf = (d)->bd_fbuf; \
  397         (d)->bd_slen = 0; \
  398         (d)->bd_fbuf = 0;
  399 /*
  400  *  bpfread - read next chunk of packets from buffers
  401  */
  402 static  int
  403 bpfread(dev, uio, ioflag)
  404         dev_t dev;
  405         struct uio *uio;
  406         int ioflag;
  407 {
  408         struct bpf_d *d = dev->si_drv1;
  409         int timed_out;
  410         int error;
  411 
  412         /*
  413          * Restrict application to use a buffer the same size as
  414          * as kernel buffers.
  415          */
  416         if (uio->uio_resid != d->bd_bufsize)
  417                 return (EINVAL);
  418 
  419         BPFD_LOCK(d);
  420         if (d->bd_state == BPF_WAITING)
  421                 callout_stop(&d->bd_callout);
  422         timed_out = (d->bd_state == BPF_TIMED_OUT);
  423         d->bd_state = BPF_IDLE;
  424         /*
  425          * If the hold buffer is empty, then do a timed sleep, which
  426          * ends when the timeout expires or when enough packets
  427          * have arrived to fill the store buffer.
  428          */
  429         while (d->bd_hbuf == 0) {
  430                 if ((d->bd_immediate || timed_out) && d->bd_slen != 0) {
  431                         /*
  432                          * A packet(s) either arrived since the previous
  433                          * read or arrived while we were asleep.
  434                          * Rotate the buffers and return what's here.
  435                          */
  436                         ROTATE_BUFFERS(d);
  437                         break;
  438                 }
  439 
  440                 /*
  441                  * No data is available, check to see if the bpf device
  442                  * is still pointed at a real interface.  If not, return
  443                  * ENXIO so that the userland process knows to rebind
  444                  * it before using it again.
  445                  */
  446                 if (d->bd_bif == NULL) {
  447                         BPFD_UNLOCK(d);
  448                         return (ENXIO);
  449                 }
  450 
  451                 if (ioflag & IO_NDELAY) {
  452                         BPFD_UNLOCK(d);
  453                         return (EWOULDBLOCK);
  454                 }
  455                 error = msleep(d, &d->bd_mtx, PRINET|PCATCH,
  456                      "bpf", d->bd_rtout);
  457                 if (error == EINTR || error == ERESTART) {
  458                         BPFD_UNLOCK(d);
  459                         return (error);
  460                 }
  461                 if (error == EWOULDBLOCK) {
  462                         /*
  463                          * On a timeout, return what's in the buffer,
  464                          * which may be nothing.  If there is something
  465                          * in the store buffer, we can rotate the buffers.
  466                          */
  467                         if (d->bd_hbuf)
  468                                 /*
  469                                  * We filled up the buffer in between
  470                                  * getting the timeout and arriving
  471                                  * here, so we don't need to rotate.
  472                                  */
  473                                 break;
  474 
  475                         if (d->bd_slen == 0) {
  476                                 BPFD_UNLOCK(d);
  477                                 return (0);
  478                         }
  479                         ROTATE_BUFFERS(d);
  480                         break;
  481                 }
  482         }
  483         /*
  484          * At this point, we know we have something in the hold slot.
  485          */
  486         BPFD_UNLOCK(d);
  487 
  488         /*
  489          * Move data from hold buffer into user space.
  490          * We know the entire buffer is transferred since
  491          * we checked above that the read buffer is bpf_bufsize bytes.
  492          */
  493         error = uiomove(d->bd_hbuf, d->bd_hlen, uio);
  494 
  495         BPFD_LOCK(d);
  496         d->bd_fbuf = d->bd_hbuf;
  497         d->bd_hbuf = 0;
  498         d->bd_hlen = 0;
  499         BPFD_UNLOCK(d);
  500 
  501         return (error);
  502 }
  503 
  504 
  505 /*
  506  * If there are processes sleeping on this descriptor, wake them up.
  507  */
  508 static __inline void
  509 bpf_wakeup(d)
  510         struct bpf_d *d;
  511 {
  512         if (d->bd_state == BPF_WAITING) {
  513                 callout_stop(&d->bd_callout);
  514                 d->bd_state = BPF_IDLE;
  515         }
  516         wakeup(d);
  517         if (d->bd_async && d->bd_sig && d->bd_sigio)
  518                 pgsigio(&d->bd_sigio, d->bd_sig, 0);
  519 
  520         selwakeup(&d->bd_sel);
  521 }
  522 
  523 static void
  524 bpf_timed_out(arg)
  525         void *arg;
  526 {
  527         struct bpf_d *d = (struct bpf_d *)arg;
  528 
  529         BPFD_LOCK(d);
  530         if (d->bd_state == BPF_WAITING) {
  531                 d->bd_state = BPF_TIMED_OUT;
  532                 if (d->bd_slen != 0)
  533                         bpf_wakeup(d);
  534         }
  535         BPFD_UNLOCK(d);
  536 }
  537 
  538 static  int
  539 bpfwrite(dev, uio, ioflag)
  540         dev_t dev;
  541         struct uio *uio;
  542         int ioflag;
  543 {
  544         struct bpf_d *d = dev->si_drv1;
  545         struct ifnet *ifp;
  546         struct mbuf *m;
  547         int error;
  548         static struct sockaddr dst;
  549         int datlen;
  550 
  551         if (d->bd_bif == 0)
  552                 return (ENXIO);
  553 
  554         ifp = d->bd_bif->bif_ifp;
  555 
  556         if (uio->uio_resid == 0)
  557                 return (0);
  558 
  559         error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, &m, &dst, &datlen);
  560         if (error)
  561                 return (error);
  562 
  563         if (datlen > ifp->if_mtu)
  564                 return (EMSGSIZE);
  565 
  566         if (d->bd_hdrcmplt)
  567                 dst.sa_family = pseudo_AF_HDRCMPLT;
  568 
  569         mtx_lock(&Giant);
  570 #ifdef MAC
  571         mac_create_mbuf_from_bpfdesc(d, m);
  572 #endif
  573         error = (*ifp->if_output)(ifp, m, &dst, (struct rtentry *)0);
  574         mtx_unlock(&Giant);
  575         /*
  576          * The driver frees the mbuf.
  577          */
  578         return (error);
  579 }
  580 
  581 /*
  582  * Reset a descriptor by flushing its packet buffer and clearing the
  583  * receive and drop counts.
  584  */
  585 static void
  586 reset_d(d)
  587         struct bpf_d *d;
  588 {
  589 
  590         mtx_assert(&d->bd_mtx, MA_OWNED);
  591         if (d->bd_hbuf) {
  592                 /* Free the hold buffer. */
  593                 d->bd_fbuf = d->bd_hbuf;
  594                 d->bd_hbuf = 0;
  595         }
  596         d->bd_slen = 0;
  597         d->bd_hlen = 0;
  598         d->bd_rcount = 0;
  599         d->bd_dcount = 0;
  600 }
  601 
  602 /*
  603  *  FIONREAD            Check for read packet available.
  604  *  SIOCGIFADDR         Get interface address - convenient hook to driver.
  605  *  BIOCGBLEN           Get buffer len [for read()].
  606  *  BIOCSETF            Set ethernet read filter.
  607  *  BIOCFLUSH           Flush read packet buffer.
  608  *  BIOCPROMISC         Put interface into promiscuous mode.
  609  *  BIOCGDLT            Get link layer type.
  610  *  BIOCGETIF           Get interface name.
  611  *  BIOCSETIF           Set interface.
  612  *  BIOCSRTIMEOUT       Set read timeout.
  613  *  BIOCGRTIMEOUT       Get read timeout.
  614  *  BIOCGSTATS          Get packet stats.
  615  *  BIOCIMMEDIATE       Set immediate mode.
  616  *  BIOCVERSION         Get filter language version.
  617  *  BIOCGHDRCMPLT       Get "header already complete" flag
  618  *  BIOCSHDRCMPLT       Set "header already complete" flag
  619  *  BIOCGSEESENT        Get "see packets sent" flag
  620  *  BIOCSSEESENT        Set "see packets sent" flag
  621  */
  622 /* ARGSUSED */
  623 static  int
  624 bpfioctl(dev, cmd, addr, flags, td)
  625         dev_t dev;
  626         u_long cmd;
  627         caddr_t addr;
  628         int flags;
  629         struct thread *td;
  630 {
  631         struct bpf_d *d = dev->si_drv1;
  632         int error = 0;
  633 
  634         BPFD_LOCK(d);
  635         if (d->bd_state == BPF_WAITING)
  636                 callout_stop(&d->bd_callout);
  637         d->bd_state = BPF_IDLE;
  638         BPFD_UNLOCK(d);
  639 
  640         switch (cmd) {
  641 
  642         default:
  643                 error = EINVAL;
  644                 break;
  645 
  646         /*
  647          * Check for read packet available.
  648          */
  649         case FIONREAD:
  650                 {
  651                         int n;
  652 
  653                         BPFD_LOCK(d);
  654                         n = d->bd_slen;
  655                         if (d->bd_hbuf)
  656                                 n += d->bd_hlen;
  657                         BPFD_UNLOCK(d);
  658 
  659                         *(int *)addr = n;
  660                         break;
  661                 }
  662 
  663         case SIOCGIFADDR:
  664                 {
  665                         struct ifnet *ifp;
  666 
  667                         if (d->bd_bif == 0)
  668                                 error = EINVAL;
  669                         else {
  670                                 ifp = d->bd_bif->bif_ifp;
  671                                 error = (*ifp->if_ioctl)(ifp, cmd, addr);
  672                         }
  673                         break;
  674                 }
  675 
  676         /*
  677          * Get buffer len [for read()].
  678          */
  679         case BIOCGBLEN:
  680                 *(u_int *)addr = d->bd_bufsize;
  681                 break;
  682 
  683         /*
  684          * Set buffer length.
  685          */
  686         case BIOCSBLEN:
  687                 if (d->bd_bif != 0)
  688                         error = EINVAL;
  689                 else {
  690                         u_int size = *(u_int *)addr;
  691 
  692                         if (size > bpf_maxbufsize)
  693                                 *(u_int *)addr = size = bpf_maxbufsize;
  694                         else if (size < BPF_MINBUFSIZE)
  695                                 *(u_int *)addr = size = BPF_MINBUFSIZE;
  696                         d->bd_bufsize = size;
  697                 }
  698                 break;
  699 
  700         /*
  701          * Set link layer read filter.
  702          */
  703         case BIOCSETF:
  704                 error = bpf_setf(d, (struct bpf_program *)addr);
  705                 break;
  706 
  707         /*
  708          * Flush read packet buffer.
  709          */
  710         case BIOCFLUSH:
  711                 BPFD_LOCK(d);
  712                 reset_d(d);
  713                 BPFD_UNLOCK(d);
  714                 break;
  715 
  716         /*
  717          * Put interface into promiscuous mode.
  718          */
  719         case BIOCPROMISC:
  720                 if (d->bd_bif == 0) {
  721                         /*
  722                          * No interface attached yet.
  723                          */
  724                         error = EINVAL;
  725                         break;
  726                 }
  727                 if (d->bd_promisc == 0) {
  728                         mtx_lock(&Giant);
  729                         error = ifpromisc(d->bd_bif->bif_ifp, 1);
  730                         mtx_unlock(&Giant);
  731                         if (error == 0)
  732                                 d->bd_promisc = 1;
  733                 }
  734                 break;
  735 
  736         /*
  737          * Get current data link type.
  738          */
  739         case BIOCGDLT:
  740                 if (d->bd_bif == 0)
  741                         error = EINVAL;
  742                 else
  743                         *(u_int *)addr = d->bd_bif->bif_dlt;
  744                 break;
  745 
  746         /*
  747          * Get a list of supported data link types.
  748          */
  749         case BIOCGDLTLIST:
  750                 if (d->bd_bif == 0)
  751                         error = EINVAL;
  752                 else
  753                         error = bpf_getdltlist(d, (struct bpf_dltlist *)addr);
  754                 break;
  755 
  756         /*
  757          * Set data link type.
  758          */
  759         case BIOCSDLT:
  760                 if (d->bd_bif == 0)
  761                         error = EINVAL;
  762                 else
  763                         error = bpf_setdlt(d, *(u_int *)addr);
  764                 break;
  765 
  766         /*
  767          * Get interface name.
  768          */
  769         case BIOCGETIF:
  770                 if (d->bd_bif == 0)
  771                         error = EINVAL;
  772                 else {
  773                         struct ifnet *const ifp = d->bd_bif->bif_ifp;
  774                         struct ifreq *const ifr = (struct ifreq *)addr;
  775 
  776                         snprintf(ifr->ifr_name, sizeof(ifr->ifr_name),
  777                             "%s%d", ifp->if_name, ifp->if_unit);
  778                 }
  779                 break;
  780 
  781         /*
  782          * Set interface.
  783          */
  784         case BIOCSETIF:
  785                 error = bpf_setif(d, (struct ifreq *)addr);
  786                 break;
  787 
  788         /*
  789          * Set read timeout.
  790          */
  791         case BIOCSRTIMEOUT:
  792                 {
  793                         struct timeval *tv = (struct timeval *)addr;
  794 
  795                         /*
  796                          * Subtract 1 tick from tvtohz() since this isn't
  797                          * a one-shot timer.
  798                          */
  799                         if ((error = itimerfix(tv)) == 0)
  800                                 d->bd_rtout = tvtohz(tv) - 1;
  801                         break;
  802                 }
  803 
  804         /*
  805          * Get read timeout.
  806          */
  807         case BIOCGRTIMEOUT:
  808                 {
  809                         struct timeval *tv = (struct timeval *)addr;
  810 
  811                         tv->tv_sec = d->bd_rtout / hz;
  812                         tv->tv_usec = (d->bd_rtout % hz) * tick;
  813                         break;
  814                 }
  815 
  816         /*
  817          * Get packet stats.
  818          */
  819         case BIOCGSTATS:
  820                 {
  821                         struct bpf_stat *bs = (struct bpf_stat *)addr;
  822 
  823                         bs->bs_recv = d->bd_rcount;
  824                         bs->bs_drop = d->bd_dcount;
  825                         break;
  826                 }
  827 
  828         /*
  829          * Set immediate mode.
  830          */
  831         case BIOCIMMEDIATE:
  832                 d->bd_immediate = *(u_int *)addr;
  833                 break;
  834 
  835         case BIOCVERSION:
  836                 {
  837                         struct bpf_version *bv = (struct bpf_version *)addr;
  838 
  839                         bv->bv_major = BPF_MAJOR_VERSION;
  840                         bv->bv_minor = BPF_MINOR_VERSION;
  841                         break;
  842                 }
  843 
  844         /*
  845          * Get "header already complete" flag
  846          */
  847         case BIOCGHDRCMPLT:
  848                 *(u_int *)addr = d->bd_hdrcmplt;
  849                 break;
  850 
  851         /*
  852          * Set "header already complete" flag
  853          */
  854         case BIOCSHDRCMPLT:
  855                 d->bd_hdrcmplt = *(u_int *)addr ? 1 : 0;
  856                 break;
  857 
  858         /*
  859          * Get "see sent packets" flag
  860          */
  861         case BIOCGSEESENT:
  862                 *(u_int *)addr = d->bd_seesent;
  863                 break;
  864 
  865         /*
  866          * Set "see sent packets" flag
  867          */
  868         case BIOCSSEESENT:
  869                 d->bd_seesent = *(u_int *)addr;
  870                 break;
  871 
  872         case FIONBIO:           /* Non-blocking I/O */
  873                 break;
  874 
  875         case FIOASYNC:          /* Send signal on receive packets */
  876                 d->bd_async = *(int *)addr;
  877                 break;
  878 
  879         case FIOSETOWN:
  880                 error = fsetown(*(int *)addr, &d->bd_sigio);
  881                 break;
  882 
  883         case FIOGETOWN:
  884                 *(int *)addr = fgetown(&d->bd_sigio);
  885                 break;
  886 
  887         /* This is deprecated, FIOSETOWN should be used instead. */
  888         case TIOCSPGRP:
  889                 error = fsetown(-(*(int *)addr), &d->bd_sigio);
  890                 break;
  891 
  892         /* This is deprecated, FIOGETOWN should be used instead. */
  893         case TIOCGPGRP:
  894                 *(int *)addr = -fgetown(&d->bd_sigio);
  895                 break;
  896 
  897         case BIOCSRSIG:         /* Set receive signal */
  898                 {
  899                         u_int sig;
  900 
  901                         sig = *(u_int *)addr;
  902 
  903                         if (sig >= NSIG)
  904                                 error = EINVAL;
  905                         else
  906                                 d->bd_sig = sig;
  907                         break;
  908                 }
  909         case BIOCGRSIG:
  910                 *(u_int *)addr = d->bd_sig;
  911                 break;
  912         }
  913         return (error);
  914 }
  915 
  916 /*
  917  * Set d's packet filter program to fp.  If this file already has a filter,
  918  * free it and replace it.  Returns EINVAL for bogus requests.
  919  */
  920 static int
  921 bpf_setf(d, fp)
  922         struct bpf_d *d;
  923         struct bpf_program *fp;
  924 {
  925         struct bpf_insn *fcode, *old;
  926         u_int flen, size;
  927 
  928         old = d->bd_filter;
  929         if (fp->bf_insns == 0) {
  930                 if (fp->bf_len != 0)
  931                         return (EINVAL);
  932                 BPFD_LOCK(d);
  933                 d->bd_filter = 0;
  934                 reset_d(d);
  935                 BPFD_UNLOCK(d);
  936                 if (old != 0)
  937                         free((caddr_t)old, M_BPF);
  938                 return (0);
  939         }
  940         flen = fp->bf_len;
  941         if (flen > BPF_MAXINSNS)
  942                 return (EINVAL);
  943 
  944         size = flen * sizeof(*fp->bf_insns);
  945         fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
  946         if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
  947             bpf_validate(fcode, (int)flen)) {
  948                 BPFD_LOCK(d);
  949                 d->bd_filter = fcode;
  950                 reset_d(d);
  951                 BPFD_UNLOCK(d);
  952                 if (old != 0)
  953                         free((caddr_t)old, M_BPF);
  954 
  955                 return (0);
  956         }
  957         free((caddr_t)fcode, M_BPF);
  958         return (EINVAL);
  959 }
  960 
  961 /*
  962  * Detach a file from its current interface (if attached at all) and attach
  963  * to the interface indicated by the name stored in ifr.
  964  * Return an errno or 0.
  965  */
  966 static int
  967 bpf_setif(d, ifr)
  968         struct bpf_d *d;
  969         struct ifreq *ifr;
  970 {
  971         struct bpf_if *bp;
  972         int error;
  973         struct ifnet *theywant;
  974 
  975         theywant = ifunit(ifr->ifr_name);
  976         if (theywant == 0)
  977                 return ENXIO;
  978 
  979         /*
  980          * Look through attached interfaces for the named one.
  981          */
  982         mtx_lock(&bpf_mtx);
  983         for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
  984                 struct ifnet *ifp = bp->bif_ifp;
  985 
  986                 if (ifp == 0 || ifp != theywant)
  987                         continue;
  988                 /* skip additional entry */
  989                 if (bp->bif_driverp != (struct bpf_if **)&ifp->if_bpf)
  990                         continue;
  991 
  992                 mtx_unlock(&bpf_mtx);
  993                 /*
  994                  * We found the requested interface.
  995                  * If it's not up, return an error.
  996                  * Allocate the packet buffers if we need to.
  997                  * If we're already attached to requested interface,
  998                  * just flush the buffer.
  999                  */
 1000                 if ((ifp->if_flags & IFF_UP) == 0)
 1001                         return (ENETDOWN);
 1002 
 1003                 if (d->bd_sbuf == 0) {
 1004                         error = bpf_allocbufs(d);
 1005                         if (error != 0)
 1006                                 return (error);
 1007                 }
 1008                 if (bp != d->bd_bif) {
 1009                         if (d->bd_bif)
 1010                                 /*
 1011                                  * Detach if attached to something else.
 1012                                  */
 1013                                 bpf_detachd(d);
 1014 
 1015                         bpf_attachd(d, bp);
 1016                 }
 1017                 BPFD_LOCK(d);
 1018                 reset_d(d);
 1019                 BPFD_UNLOCK(d);
 1020                 return (0);
 1021         }
 1022         mtx_unlock(&bpf_mtx);
 1023         /* Not found. */
 1024         return (ENXIO);
 1025 }
 1026 
 1027 /*
 1028  * Support for select() and poll() system calls
 1029  *
 1030  * Return true iff the specific operation will not block indefinitely.
 1031  * Otherwise, return false but make a note that a selwakeup() must be done.
 1032  */
 1033 static int
 1034 bpfpoll(dev, events, td)
 1035         dev_t dev;
 1036         int events;
 1037         struct thread *td;
 1038 {
 1039         struct bpf_d *d;
 1040         int revents;
 1041 
 1042         d = dev->si_drv1;
 1043         if (d->bd_bif == NULL)
 1044                 return (ENXIO);
 1045 
 1046         revents = events & (POLLOUT | POLLWRNORM);
 1047         BPFD_LOCK(d);
 1048         if (events & (POLLIN | POLLRDNORM)) {
 1049                 /*
 1050                  * An imitation of the FIONREAD ioctl code.
 1051                  * XXX not quite.  An exact imitation:
 1052                  *      if (d->b_slen != 0 ||
 1053                  *          (d->bd_hbuf != NULL && d->bd_hlen != 0)
 1054                  */
 1055                 if (d->bd_hlen != 0 ||
 1056                     ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
 1057                     d->bd_slen != 0))
 1058                         revents |= events & (POLLIN | POLLRDNORM);
 1059                 else {
 1060                         selrecord(td, &d->bd_sel);
 1061                         /* Start the read timeout if necessary. */
 1062                         if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
 1063                                 callout_reset(&d->bd_callout, d->bd_rtout,
 1064                                     bpf_timed_out, d);
 1065                                 d->bd_state = BPF_WAITING;
 1066                         }
 1067                 }
 1068         }
 1069         BPFD_UNLOCK(d);
 1070         return (revents);
 1071 }
 1072 
 1073 /*
 1074  * Incoming linkage from device drivers.  Process the packet pkt, of length
 1075  * pktlen, which is stored in a contiguous buffer.  The packet is parsed
 1076  * by each process' filter, and if accepted, stashed into the corresponding
 1077  * buffer.
 1078  */
 1079 void
 1080 bpf_tap(bp, pkt, pktlen)
 1081         struct bpf_if *bp;
 1082         u_char *pkt;
 1083         u_int pktlen;
 1084 {
 1085         struct bpf_d *d;
 1086         u_int slen;
 1087 
 1088         BPFIF_LOCK(bp);
 1089         for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
 1090                 BPFD_LOCK(d);
 1091                 ++d->bd_rcount;
 1092                 slen = bpf_filter(d->bd_filter, pkt, pktlen, pktlen);
 1093                 if (slen != 0) {
 1094 #ifdef MAC
 1095                         if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
 1096 #endif
 1097                                 catchpacket(d, pkt, pktlen, slen, bcopy);
 1098                 }
 1099                 BPFD_UNLOCK(d);
 1100         }
 1101         BPFIF_UNLOCK(bp);
 1102 }
 1103 
 1104 /*
 1105  * Copy data from an mbuf chain into a buffer.  This code is derived
 1106  * from m_copydata in sys/uipc_mbuf.c.
 1107  */
 1108 static void
 1109 bpf_mcopy(src_arg, dst_arg, len)
 1110         const void *src_arg;
 1111         void *dst_arg;
 1112         size_t len;
 1113 {
 1114         const struct mbuf *m;
 1115         u_int count;
 1116         u_char *dst;
 1117 
 1118         m = src_arg;
 1119         dst = dst_arg;
 1120         while (len > 0) {
 1121                 if (m == 0)
 1122                         panic("bpf_mcopy");
 1123                 count = min(m->m_len, len);
 1124                 bcopy(mtod(m, void *), dst, count);
 1125                 m = m->m_next;
 1126                 dst += count;
 1127                 len -= count;
 1128         }
 1129 }
 1130 
 1131 /*
 1132  * Incoming linkage from device drivers, when packet is in an mbuf chain.
 1133  */
 1134 void
 1135 bpf_mtap(bp, m)
 1136         struct bpf_if *bp;
 1137         struct mbuf *m;
 1138 {
 1139         struct bpf_d *d;
 1140         u_int pktlen, slen;
 1141 
 1142         pktlen = m_length(m, NULL);
 1143         if (pktlen == m->m_len) {
 1144                 bpf_tap(bp, mtod(m, u_char *), pktlen);
 1145                 return;
 1146         }
 1147 
 1148         BPFIF_LOCK(bp);
 1149         for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
 1150                 if (!d->bd_seesent && (m->m_pkthdr.rcvif == NULL))
 1151                         continue;
 1152                 BPFD_LOCK(d);
 1153                 ++d->bd_rcount;
 1154                 slen = bpf_filter(d->bd_filter, (u_char *)m, pktlen, 0);
 1155                 if (slen != 0)
 1156 #ifdef MAC
 1157                         if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
 1158 #endif
 1159                                 catchpacket(d, (u_char *)m, pktlen, slen,
 1160                                     bpf_mcopy);
 1161                 BPFD_UNLOCK(d);
 1162         }
 1163         BPFIF_UNLOCK(bp);
 1164 }
 1165 
 1166 /*
 1167  * Move the packet data from interface memory (pkt) into the
 1168  * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
 1169  * otherwise 0.  "copy" is the routine called to do the actual data
 1170  * transfer.  bcopy is passed in to copy contiguous chunks, while
 1171  * bpf_mcopy is passed in to copy mbuf chains.  In the latter case,
 1172  * pkt is really an mbuf.
 1173  */
 1174 static void
 1175 catchpacket(d, pkt, pktlen, snaplen, cpfn)
 1176         struct bpf_d *d;
 1177         u_char *pkt;
 1178         u_int pktlen, snaplen;
 1179         void (*cpfn)(const void *, void *, size_t);
 1180 {
 1181         struct bpf_hdr *hp;
 1182         int totlen, curlen;
 1183         int hdrlen = d->bd_bif->bif_hdrlen;
 1184         /*
 1185          * Figure out how many bytes to move.  If the packet is
 1186          * greater or equal to the snapshot length, transfer that
 1187          * much.  Otherwise, transfer the whole packet (unless
 1188          * we hit the buffer size limit).
 1189          */
 1190         totlen = hdrlen + min(snaplen, pktlen);
 1191         if (totlen > d->bd_bufsize)
 1192                 totlen = d->bd_bufsize;
 1193 
 1194         /*
 1195          * Round up the end of the previous packet to the next longword.
 1196          */
 1197         curlen = BPF_WORDALIGN(d->bd_slen);
 1198         if (curlen + totlen > d->bd_bufsize) {
 1199                 /*
 1200                  * This packet will overflow the storage buffer.
 1201                  * Rotate the buffers if we can, then wakeup any
 1202                  * pending reads.
 1203                  */
 1204                 if (d->bd_fbuf == 0) {
 1205                         /*
 1206                          * We haven't completed the previous read yet,
 1207                          * so drop the packet.
 1208                          */
 1209                         ++d->bd_dcount;
 1210                         return;
 1211                 }
 1212                 ROTATE_BUFFERS(d);
 1213                 bpf_wakeup(d);
 1214                 curlen = 0;
 1215         }
 1216         else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT)
 1217                 /*
 1218                  * Immediate mode is set, or the read timeout has
 1219                  * already expired during a select call.  A packet
 1220                  * arrived, so the reader should be woken up.
 1221                  */
 1222                 bpf_wakeup(d);
 1223 
 1224         /*
 1225          * Append the bpf header.
 1226          */
 1227         hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
 1228         microtime(&hp->bh_tstamp);
 1229         hp->bh_datalen = pktlen;
 1230         hp->bh_hdrlen = hdrlen;
 1231         /*
 1232          * Copy the packet data into the store buffer and update its length.
 1233          */
 1234         (*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = totlen - hdrlen));
 1235         d->bd_slen = curlen + totlen;
 1236 }
 1237 
 1238 /*
 1239  * Initialize all nonzero fields of a descriptor.
 1240  */
 1241 static int
 1242 bpf_allocbufs(d)
 1243         struct bpf_d *d;
 1244 {
 1245         d->bd_fbuf = (caddr_t)malloc(d->bd_bufsize, M_BPF, M_WAITOK);
 1246         if (d->bd_fbuf == 0)
 1247                 return (ENOBUFS);
 1248 
 1249         d->bd_sbuf = (caddr_t)malloc(d->bd_bufsize, M_BPF, M_WAITOK);
 1250         if (d->bd_sbuf == 0) {
 1251                 free(d->bd_fbuf, M_BPF);
 1252                 return (ENOBUFS);
 1253         }
 1254         d->bd_slen = 0;
 1255         d->bd_hlen = 0;
 1256         return (0);
 1257 }
 1258 
 1259 /*
 1260  * Free buffers currently in use by a descriptor.
 1261  * Called on close.
 1262  */
 1263 static void
 1264 bpf_freed(d)
 1265         struct bpf_d *d;
 1266 {
 1267         /*
 1268          * We don't need to lock out interrupts since this descriptor has
 1269          * been detached from its interface and it yet hasn't been marked
 1270          * free.
 1271          */
 1272         if (d->bd_sbuf != 0) {
 1273                 free(d->bd_sbuf, M_BPF);
 1274                 if (d->bd_hbuf != 0)
 1275                         free(d->bd_hbuf, M_BPF);
 1276                 if (d->bd_fbuf != 0)
 1277                         free(d->bd_fbuf, M_BPF);
 1278         }
 1279         if (d->bd_filter)
 1280                 free((caddr_t)d->bd_filter, M_BPF);
 1281         mtx_destroy(&d->bd_mtx);
 1282 }
 1283 
 1284 /*
 1285  * Attach an interface to bpf.  dlt is the link layer type; hdrlen is the
 1286  * fixed size of the link header (variable length headers not yet supported).
 1287  */
 1288 void
 1289 bpfattach(ifp, dlt, hdrlen)
 1290         struct ifnet *ifp;
 1291         u_int dlt, hdrlen;
 1292 {
 1293 
 1294         bpfattach2(ifp, dlt, hdrlen, &ifp->if_bpf);
 1295 }
 1296 
 1297 /*
 1298  * Attach an interface to bpf.  ifp is a pointer to the structure
 1299  * defining the interface to be attached, dlt is the link layer type,
 1300  * and hdrlen is the fixed size of the link header (variable length
 1301  * headers are not yet supporrted).
 1302  */
 1303 void
 1304 bpfattach2(ifp, dlt, hdrlen, driverp)
 1305         struct ifnet *ifp;
 1306         u_int dlt, hdrlen;
 1307         struct bpf_if **driverp;
 1308 {
 1309         struct bpf_if *bp;
 1310         bp = (struct bpf_if *)malloc(sizeof(*bp), M_BPF, M_NOWAIT | M_ZERO);
 1311         if (bp == 0)
 1312                 panic("bpfattach");
 1313 
 1314         bp->bif_dlist = 0;
 1315         bp->bif_driverp = driverp;
 1316         bp->bif_ifp = ifp;
 1317         bp->bif_dlt = dlt;
 1318         mtx_init(&bp->bif_mtx, "bpf interface lock", NULL, MTX_DEF);
 1319 
 1320         mtx_lock(&bpf_mtx);
 1321         bp->bif_next = bpf_iflist;
 1322         bpf_iflist = bp;
 1323         mtx_unlock(&bpf_mtx);
 1324 
 1325         *bp->bif_driverp = 0;
 1326 
 1327         /*
 1328          * Compute the length of the bpf header.  This is not necessarily
 1329          * equal to SIZEOF_BPF_HDR because we want to insert spacing such
 1330          * that the network layer header begins on a longword boundary (for
 1331          * performance reasons and to alleviate alignment restrictions).
 1332          */
 1333         bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;
 1334 
 1335         if (bootverbose)
 1336                 if_printf(ifp, "bpf attached\n");
 1337 }
 1338 
 1339 /*
 1340  * Detach bpf from an interface.  This involves detaching each descriptor
 1341  * associated with the interface, and leaving bd_bif NULL.  Notify each
 1342  * descriptor as it's detached so that any sleepers wake up and get
 1343  * ENXIO.
 1344  */
 1345 void
 1346 bpfdetach(ifp)
 1347         struct ifnet *ifp;
 1348 {
 1349         struct bpf_if   *bp, *bp_prev;
 1350         struct bpf_d    *d;
 1351 
 1352         /* Locate BPF interface information */
 1353         bp_prev = NULL;
 1354 
 1355         mtx_lock(&bpf_mtx);
 1356         for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
 1357                 if (ifp == bp->bif_ifp)
 1358                         break;
 1359                 bp_prev = bp;
 1360         }
 1361 
 1362         /* Interface wasn't attached */
 1363         if ((bp == NULL) || (bp->bif_ifp == NULL)) {
 1364                 mtx_unlock(&bpf_mtx);
 1365                 printf("bpfdetach: %s%d was not attached\n", ifp->if_name,
 1366                     ifp->if_unit);
 1367                 return;
 1368         }
 1369 
 1370         if (bp_prev) {
 1371                 bp_prev->bif_next = bp->bif_next;
 1372         } else {
 1373                 bpf_iflist = bp->bif_next;
 1374         }
 1375         mtx_unlock(&bpf_mtx);
 1376 
 1377         while ((d = bp->bif_dlist) != NULL) {
 1378                 bpf_detachd(d);
 1379                 BPFD_LOCK(d);
 1380                 bpf_wakeup(d);
 1381                 BPFD_UNLOCK(d);
 1382         }
 1383 
 1384         mtx_destroy(&bp->bif_mtx);
 1385         free(bp, M_BPF);
 1386 }
 1387 
 1388 /*
 1389  * Get a list of available data link type of the interface.
 1390  */
 1391 static int
 1392 bpf_getdltlist(d, bfl)
 1393         struct bpf_d *d;
 1394         struct bpf_dltlist *bfl;
 1395 {
 1396         int n, error;
 1397         struct ifnet *ifp;
 1398         struct bpf_if *bp;
 1399 
 1400         ifp = d->bd_bif->bif_ifp;
 1401         n = 0;
 1402         error = 0;
 1403         mtx_lock(&bpf_mtx);
 1404         for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
 1405                 if (bp->bif_ifp != ifp)
 1406                         continue;
 1407                 if (bfl->bfl_list != NULL) {
 1408                         if (n >= bfl->bfl_len) {
 1409                                 mtx_unlock(&bpf_mtx);
 1410                                 return (ENOMEM);
 1411                         }
 1412                         error = copyout(&bp->bif_dlt,
 1413                             bfl->bfl_list + n, sizeof(u_int));
 1414                 }
 1415                 n++;
 1416         }
 1417         mtx_unlock(&bpf_mtx);
 1418         bfl->bfl_len = n;
 1419         return (error);
 1420 }
 1421 
 1422 /*
 1423  * Set the data link type of a BPF instance.
 1424  */
 1425 static int
 1426 bpf_setdlt(d, dlt)
 1427         struct bpf_d *d;
 1428         u_int dlt;
 1429 {
 1430         int error, opromisc;
 1431         struct ifnet *ifp;
 1432         struct bpf_if *bp;
 1433 
 1434         if (d->bd_bif->bif_dlt == dlt)
 1435                 return (0);
 1436         ifp = d->bd_bif->bif_ifp;
 1437         mtx_lock(&bpf_mtx);
 1438         for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
 1439                 if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
 1440                         break;
 1441         }
 1442         mtx_unlock(&bpf_mtx);
 1443         if (bp != NULL) {
 1444                 BPFD_LOCK(d);
 1445                 opromisc = d->bd_promisc;
 1446                 bpf_detachd(d);
 1447                 bpf_attachd(d, bp);
 1448                 reset_d(d);
 1449                 BPFD_UNLOCK(d);
 1450                 if (opromisc) {
 1451                         error = ifpromisc(bp->bif_ifp, 1);
 1452                         if (error)
 1453                                 if_printf(bp->bif_ifp,
 1454                                         "bpf_setdlt: ifpromisc failed (%d)\n",
 1455                                         error);
 1456                         else
 1457                                 d->bd_promisc = 1;
 1458                 }
 1459         }
 1460         return (bp == NULL ? EINVAL : 0);
 1461 }
 1462 
 1463 static void bpf_drvinit(void *unused);
 1464 
 1465 static void bpf_clone(void *arg, char *name, int namelen, dev_t *dev);
 1466 
 1467 static void
 1468 bpf_clone(arg, name, namelen, dev)
 1469         void *arg;
 1470         char *name;
 1471         int namelen;
 1472         dev_t *dev;
 1473 {
 1474         int u;
 1475 
 1476         if (*dev != NODEV)
 1477                 return;
 1478         if (dev_stdclone(name, NULL, "bpf", &u) != 1)
 1479                 return;
 1480         *dev = make_dev(&bpf_cdevsw, unit2minor(u), UID_ROOT, GID_WHEEL, 0600,
 1481             "bpf%d", u);
 1482         (*dev)->si_flags |= SI_CHEAPCLONE;
 1483         return;
 1484 }
 1485 
 1486 static void
 1487 bpf_drvinit(unused)
 1488         void *unused;
 1489 {
 1490 
 1491         mtx_init(&bpf_mtx, "bpf global lock", NULL, MTX_DEF);
 1492         EVENTHANDLER_REGISTER(dev_clone, bpf_clone, 0, 1000);
 1493 }
 1494 
 1495 SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvinit,NULL)
 1496 
 1497 #else /* !DEV_BPF && !NETGRAPH_BPF */
 1498 /*
 1499  * NOP stubs to allow bpf-using drivers to load and function.
 1500  *
 1501  * A 'better' implementation would allow the core bpf functionality
 1502  * to be loaded at runtime.
 1503  */
 1504 
 1505 void
 1506 bpf_tap(bp, pkt, pktlen)
 1507         struct bpf_if *bp;
 1508         u_char *pkt;
 1509         u_int pktlen;
 1510 {
 1511 }
 1512 
 1513 void
 1514 bpf_mtap(bp, m)
 1515         struct bpf_if *bp;
 1516         struct mbuf *m;
 1517 {
 1518 }
 1519 
 1520 void
 1521 bpfattach(ifp, dlt, hdrlen)
 1522         struct ifnet *ifp;
 1523         u_int dlt, hdrlen;
 1524 {
 1525 }
 1526 
 1527 void
 1528 bpfdetach(ifp)
 1529         struct ifnet *ifp;
 1530 {
 1531 }
 1532 
 1533 u_int
 1534 bpf_filter(pc, p, wirelen, buflen)
 1535         const struct bpf_insn *pc;
 1536         u_char *p;
 1537         u_int wirelen;
 1538         u_int buflen;
 1539 {
 1540         return -1;      /* "no filter" behaviour */
 1541 }
 1542 
 1543 int
 1544 bpf_validate(f, len)
 1545         const struct bpf_insn *f;
 1546         int len;
 1547 {
 1548         return 0;               /* false */
 1549 }
 1550 
 1551 #endif /* !DEV_BPF && !NETGRAPH_BPF */

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