FreeBSD/Linux Kernel Cross Reference
sys/net/bpf_buffer.c

     /*-
      * Copyright (c) 2007 Seccuris Inc.
      * All rights reserved.
      *
      * This software was developed by Robert N. M. Watson under contract to
      * Seccuris Inc.
      *
      * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
     *
     * Copyright (c) 1990, 1991, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * This code is derived from the Stanford/CMU enet packet filter,
     * (net/enet.c) distributed as part of 4.3BSD, and code contributed
     * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
     * Berkeley Laboratory.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)bpf.c       8.4 (Berkeley) 1/9/95
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.4/sys/net/bpf_buffer.c 286856 2015-08-17 18:43:39Z loos $");
    
    #include "opt_bpf.h"
    
    #include <sys/param.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/uio.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    
    #include <net/if.h>
    #include <net/bpf.h>
    #include <net/bpf_buffer.h>
    #include <net/bpfdesc.h>
    
    /*
     * Implement historical kernel memory buffering model for BPF: two malloc(9)
     * kernel buffers are hung off of the descriptor.  The size is fixed prior to
     * attaching to an ifnet, ad cannot be changed after that.  read(2) simply
     * copies the data to user space using uiomove(9).
     */
    
    static int bpf_bufsize = 4096;
    SYSCTL_INT(_net_bpf, OID_AUTO, bufsize, CTLFLAG_RW,
        &bpf_bufsize, 0, "Default capture buffer size in bytes");
    static int bpf_maxbufsize = BPF_MAXBUFSIZE;
    SYSCTL_INT(_net_bpf, OID_AUTO, maxbufsize, CTLFLAG_RW,
        &bpf_maxbufsize, 0, "Maximum capture buffer in bytes");
    
    /*
     * Simple data copy to the current kernel buffer.
     */
    void
   bpf_buffer_append_bytes(struct bpf_d *d, caddr_t buf, u_int offset,
       void *src, u_int len)
   {
           u_char *src_bytes;
   
           src_bytes = (u_char *)src;
           bcopy(src_bytes, buf + offset, len);
   }
   
   /*
    * Scatter-gather data copy from an mbuf chain to the current kernel buffer.
    */
   void
   bpf_buffer_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset, void *src,
       u_int len)
   {
           const struct mbuf *m;
           u_char *dst;
           u_int count;
   
           m = (struct mbuf *)src;
           dst = (u_char *)buf + offset;
           while (len > 0) {
                   if (m == NULL)
                           panic("bpf_mcopy");
                   count = min(m->m_len, len);
                   bcopy(mtod(m, void *), dst, count);
                   m = m->m_next;
                   dst += count;
                   len -= count;
           }
   }
   
   /*
    * Free BPF kernel buffers on device close.
    */
   void
   bpf_buffer_free(struct bpf_d *d)
   {
   
           if (d->bd_sbuf != NULL)
                   free(d->bd_sbuf, M_BPF);
           if (d->bd_hbuf != NULL)
                   free(d->bd_hbuf, M_BPF);
           if (d->bd_fbuf != NULL)
                   free(d->bd_fbuf, M_BPF);
   
   #ifdef INVARIANTS
           d->bd_sbuf = d->bd_hbuf = d->bd_fbuf = (caddr_t)~0;
   #endif
   }
   
   /*
    * This is a historical initialization that occurs when the BPF descriptor is
    * first opened.  It does not imply selection of a buffer mode, so we don't
    * allocate buffers here.
    */
   void
   bpf_buffer_init(struct bpf_d *d)
   {
   
           d->bd_bufsize = bpf_bufsize;
   }
   
   /*
    * Allocate or resize buffers.
    */
   int
   bpf_buffer_ioctl_sblen(struct bpf_d *d, u_int *i)
   {
           u_int size;
           caddr_t fbuf, sbuf;
   
           size = *i;
           if (size > bpf_maxbufsize)
                   *i = size = bpf_maxbufsize;
           else if (size < BPF_MINBUFSIZE)
                   *i = size = BPF_MINBUFSIZE;
   
           /* Allocate buffers immediately */
           fbuf = (caddr_t)malloc(size, M_BPF, M_WAITOK);
           sbuf = (caddr_t)malloc(size, M_BPF, M_WAITOK);
   
           BPFD_LOCK(d);
           if (d->bd_bif != NULL) {
                   /* Interface already attached, unable to change buffers */
                   BPFD_UNLOCK(d);
                   free(fbuf, M_BPF);
                   free(sbuf, M_BPF);
                   return (EINVAL);
           }
   
           /* Free old buffers if set */
           if (d->bd_fbuf != NULL)
                   free(d->bd_fbuf, M_BPF);
           if (d->bd_sbuf != NULL)
                   free(d->bd_sbuf, M_BPF);
   
           /* Fill in new data */
           d->bd_bufsize = size;
           d->bd_fbuf = fbuf;
           d->bd_sbuf = sbuf;
   
           d->bd_hbuf = NULL;
           d->bd_slen = 0;
           d->bd_hlen = 0;
   
           BPFD_UNLOCK(d);
           return (0);
   }
   
   /*
    * Copy buffer storage to user space in read().
    */
   int
   bpf_buffer_uiomove(struct bpf_d *d, caddr_t buf, u_int len, struct uio *uio)
   {
   
           return (uiomove(buf, len, uio));
   }

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