pfil.c

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    1 /*      $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $  */
    2 
    3 /*
    4  * Copyright (c) 1996 Matthew R. Green
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. The name of the author may not be used to endorse or promote products
   16  *    derived from this software without specific prior written permission.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __KERNEL_RCSID(0, "$NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $");
   33 
   34 #include <sys/param.h>
   35 #include <sys/errno.h>
   36 #include <sys/malloc.h>
   37 #include <sys/socket.h>
   38 #include <sys/socketvar.h>
   39 #include <sys/systm.h>
   40 #include <sys/proc.h>
   41 #include <sys/queue.h>
   42 
   43 #include <net/if.h>
   44 #include <net/pfil.h>
   45 
   46 static int pfil_list_add(pfil_list_t *,
   47     int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int);
   48 
   49 static int pfil_list_remove(pfil_list_t *,
   50     int (*)(void *, struct mbuf **, struct ifnet *, int), void *);
   51 
   52 LIST_HEAD(, pfil_head) pfil_head_list =
   53     LIST_HEAD_INITIALIZER(&pfil_head_list);
   54 
   55 /*
   56  * pfil_run_hooks() runs the specified packet filter hooks.
   57  */
   58 int
   59 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   60     int dir)
   61 {
   62         struct packet_filter_hook *pfh;
   63         struct mbuf *m = *mp;
   64         int rv = 0;
   65 
   66         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
   67              pfh = TAILQ_NEXT(pfh, pfil_link)) {
   68                 if (pfh->pfil_func != NULL) {
   69                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir);
   70                         if (rv != 0 || m == NULL)
   71                                 break;
   72                 }
   73         }
   74 
   75         *mp = m;
   76         return (rv);
   77 }
   78 
   79 /*
   80  * pfil_head_register() registers a pfil_head with the packet filter
   81  * hook mechanism.
   82  */
   83 int
   84 pfil_head_register(struct pfil_head *ph)
   85 {
   86         struct pfil_head *lph;
   87 
   88         for (lph = LIST_FIRST(&pfil_head_list); lph != NULL;
   89              lph = LIST_NEXT(lph, ph_list)) {
   90                 if (ph->ph_type == lph->ph_type &&
   91                     ph->ph_un.phu_val == lph->ph_un.phu_val)
   92                         return EEXIST;
   93         }
   94 
   95         TAILQ_INIT(&ph->ph_in);
   96         TAILQ_INIT(&ph->ph_out);
   97 
   98         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
   99 
  100         return (0);
  101 }
  102 
  103 /*
  104  * pfil_head_unregister() removes a pfil_head from the packet filter
  105  * hook mechanism.
  106  */
  107 int
  108 pfil_head_unregister(struct pfil_head *pfh)
  109 {
  110 
  111         LIST_REMOVE(pfh, ph_list);
  112         return (0);
  113 }
  114 
  115 /*
  116  * pfil_head_get() returns the pfil_head for a given key/dlt.
  117  */
  118 struct pfil_head *
  119 pfil_head_get(int type, u_long val)
  120 {
  121         struct pfil_head *ph;
  122 
  123         for (ph = LIST_FIRST(&pfil_head_list); ph != NULL;
  124              ph = LIST_NEXT(ph, ph_list)) {
  125                 if (ph->ph_type == type &&
  126                     ph->ph_un.phu_val == val)
  127                         break;
  128         }
  129 
  130         return (ph);
  131 }
  132 
  133 /*
  134  * pfil_add_hook() adds a function to the packet filter hook.  the
  135  * flags are:
  136  *      PFIL_IN         call me on incoming packets
  137  *      PFIL_OUT        call me on outgoing packets
  138  *      PFIL_ALL        call me on all of the above
  139  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  140  */
  141 int
  142 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  143     void *arg, int flags, struct pfil_head *ph)
  144 {
  145         int err = 0;
  146 
  147         if (flags & PFIL_IN) {
  148                 err = pfil_list_add(&ph->ph_in, func, arg, flags & ~PFIL_OUT);
  149                 if (err)
  150                         return err;
  151         }
  152         if (flags & PFIL_OUT) {
  153                 err = pfil_list_add(&ph->ph_out, func, arg, flags & ~PFIL_IN);
  154                 if (err) {
  155                         if (flags & PFIL_IN)
  156                                 pfil_list_remove(&ph->ph_in, func, arg);
  157                         return err;
  158                 }
  159         }
  160         return 0;
  161 }
  162 
  163 static int
  164 pfil_list_add(pfil_list_t *list,
  165     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
  166     int flags)
  167 {
  168         struct packet_filter_hook *pfh;
  169 
  170         /*
  171          * First make sure the hook is not already there.
  172          */
  173         for (pfh = TAILQ_FIRST(list); pfh != NULL;
  174              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  175                 if (pfh->pfil_func == func &&
  176                     pfh->pfil_arg == arg)
  177                         return EEXIST;
  178         }
  179 
  180         pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
  181             (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  182         if (pfh == NULL)
  183                 return ENOMEM;
  184 
  185         pfh->pfil_func = func;
  186         pfh->pfil_arg  = arg;
  187 
  188         /*
  189          * insert the input list in reverse order of the output list
  190          * so that the same path is followed in or out of the kernel.
  191          */
  192         if (flags & PFIL_IN)
  193                 TAILQ_INSERT_HEAD(list, pfh, pfil_link);
  194         else
  195                 TAILQ_INSERT_TAIL(list, pfh, pfil_link);
  196 
  197         return 0;
  198 }
  199 
  200 /*
  201  * pfil_remove_hook removes a specific function from the packet filter
  202  * hook list.
  203  */
  204 int
  205 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  206     void *arg, int flags, struct pfil_head *ph)
  207 {
  208         int err = 0;
  209 
  210         if (flags & PFIL_IN)
  211                 err = pfil_list_remove(&ph->ph_in, func, arg);
  212         if ((err == 0) && (flags & PFIL_OUT))
  213                 err = pfil_list_remove(&ph->ph_out, func, arg);
  214         return err;
  215 }
  216 
  217 /*
  218  * pfil_list_remove is an internal function that takes a function off the
  219  * specified list.
  220  */
  221 static int
  222 pfil_list_remove(pfil_list_t *list,
  223     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
  224 {
  225         struct packet_filter_hook *pfh;
  226 
  227         for (pfh = TAILQ_FIRST(list); pfh != NULL;
  228              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  229                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  230                         TAILQ_REMOVE(list, pfh, pfil_link);
  231                         free(pfh, M_IFADDR);
  232                         return 0;
  233                 }
  234         }
  235         return ENOENT;
  236 }

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

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sys/net/pfil.c