pfil.c

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    1 /*      $NetBSD: pfil.c,v 1.27 2008/06/23 03:13:12 dyoung 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  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __KERNEL_RCSID(0, "$NetBSD: pfil.c,v 1.27 2008/06/23 03:13:12 dyoung Exp $");
   31 
   32 #include <sys/param.h>
   33 #include <sys/errno.h>
   34 #include <sys/malloc.h>
   35 #include <sys/socket.h>
   36 #include <sys/socketvar.h>
   37 #include <sys/systm.h>
   38 #include <sys/proc.h>
   39 #include <sys/queue.h>
   40 
   41 #include <net/if.h>
   42 #include <net/pfil.h>
   43 
   44 static int pfil_list_add(pfil_list_t *,
   45     int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int);
   46 
   47 static int pfil_list_remove(pfil_list_t *,
   48     int (*)(void *, struct mbuf **, struct ifnet *, int), void *);
   49 
   50 LIST_HEAD(, pfil_head) pfil_head_list =
   51     LIST_HEAD_INITIALIZER(&pfil_head_list);
   52 
   53 /*
   54  * pfil_run_hooks() runs the specified packet filter hooks.
   55  */
   56 int
   57 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   58     int dir)
   59 {
   60         struct packet_filter_hook *pfh;
   61         struct mbuf *m = NULL;
   62         int rv = 0;
   63 
   64         if ((dir & PFIL_ALL) && mp)
   65                 m = *mp;
   66         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
   67              pfh = TAILQ_NEXT(pfh, pfil_link)) {
   68                 if (pfh->pfil_func != NULL) {
   69                         if (pfh->pfil_flags & PFIL_ALL) {
   70                                 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp,
   71                                     dir);
   72                                 if (rv != 0 || m == NULL)
   73                                         break;
   74                         } else {
   75                                 rv = (*pfh->pfil_func)(pfh->pfil_arg, mp, ifp,
   76                                     dir);
   77                                 if (rv != 0)
   78                                         break;
   79                         }
   80                 }
   81         }
   82 
   83         if ((dir & PFIL_ALL) && mp)
   84                 *mp = m;
   85         return (rv);
   86 }
   87 
   88 /*
   89  * pfil_head_register() registers a pfil_head with the packet filter
   90  * hook mechanism.
   91  */
   92 int
   93 pfil_head_register(struct pfil_head *ph)
   94 {
   95         struct pfil_head *lph;
   96 
   97         LIST_FOREACH(lph, &pfil_head_list, ph_list) {
   98                 if (ph->ph_type == lph->ph_type &&
   99                     ph->ph_un.phu_val == lph->ph_un.phu_val)
  100                         return EEXIST;
  101         }
  102 
  103         TAILQ_INIT(&ph->ph_in);
  104         TAILQ_INIT(&ph->ph_out);
  105         TAILQ_INIT(&ph->ph_ifaddr);
  106         TAILQ_INIT(&ph->ph_ifnetevent);
  107 
  108         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  109 
  110         return (0);
  111 }
  112 
  113 /*
  114  * pfil_head_unregister() removes a pfil_head from the packet filter
  115  * hook mechanism.
  116  */
  117 int
  118 pfil_head_unregister(struct pfil_head *pfh)
  119 {
  120 
  121         LIST_REMOVE(pfh, ph_list);
  122         return (0);
  123 }
  124 
  125 /*
  126  * pfil_head_get() returns the pfil_head for a given key/dlt.
  127  */
  128 struct pfil_head *
  129 pfil_head_get(int type, u_long val)
  130 {
  131         struct pfil_head *ph;
  132 
  133         LIST_FOREACH(ph, &pfil_head_list, ph_list) {
  134                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  135                         break;
  136         }
  137 
  138         return (ph);
  139 }
  140 
  141 /*
  142  * pfil_add_hook() adds a function to the packet filter hook.  the
  143  * flags are:
  144  *      PFIL_IN         call me on incoming packets
  145  *      PFIL_OUT        call me on outgoing packets
  146  *      PFIL_ALL        call me on all of the above
  147  *      PFIL_IFADDR     call me on interface reconfig (mbuf ** is ioctl #)
  148  *      PFIL_IFNET      call me on interface attach/detach
  149  *                      (mbuf ** is PFIL_IFNET_*)
  150  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  151  */
  152 int
  153 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  154     void *arg, int flags, struct pfil_head *ph)
  155 {
  156         int err = 0;
  157 
  158         if (flags & PFIL_IN) {
  159                 err = pfil_list_add(&ph->ph_in, func, arg, flags & ~PFIL_OUT);
  160                 if (err)
  161                         return err;
  162         }
  163         if (flags & PFIL_OUT) {
  164                 err = pfil_list_add(&ph->ph_out, func, arg, flags & ~PFIL_IN);
  165                 if (err) {
  166                         if (flags & PFIL_IN)
  167                                 pfil_list_remove(&ph->ph_in, func, arg);
  168                         return err;
  169                 }
  170         }
  171         if (flags & PFIL_IFADDR) {
  172                 err = pfil_list_add(&ph->ph_ifaddr, func, arg, flags);
  173                 if (err) {
  174                         if (flags & PFIL_IN)
  175                                 pfil_list_remove(&ph->ph_in, func, arg);
  176                         if (flags & PFIL_OUT)
  177                                 pfil_list_remove(&ph->ph_out, func, arg);
  178                         return err;
  179                 }
  180         }
  181         if (flags & PFIL_IFNET) {
  182                 err = pfil_list_add(&ph->ph_ifnetevent, func, arg, flags);
  183                 if (err) {
  184                         if (flags & PFIL_IN)
  185                                 pfil_list_remove(&ph->ph_in, func, arg);
  186                         if (flags & PFIL_OUT)
  187                                 pfil_list_remove(&ph->ph_out, func, arg);
  188                         if (flags & PFIL_IFADDR)
  189                                 pfil_list_remove(&ph->ph_ifaddr, func, arg);
  190                         return err;
  191                 }
  192         }
  193         return 0;
  194 }
  195 
  196 static int
  197 pfil_list_add(pfil_list_t *list,
  198     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
  199     int flags)
  200 {
  201         struct packet_filter_hook *pfh;
  202 
  203         /*
  204          * First make sure the hook is not already there.
  205          */
  206         TAILQ_FOREACH(pfh, list, pfil_link) {
  207                 if (pfh->pfil_func == func && pfh->pfil_arg == arg)
  208                         return EEXIST;
  209         }
  210 
  211         pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
  212             (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  213         if (pfh == NULL)
  214                 return ENOMEM;
  215 
  216         pfh->pfil_func = func;
  217         pfh->pfil_arg  = arg;
  218         pfh->pfil_flags = flags;
  219 
  220         /*
  221          * insert the input list in reverse order of the output list
  222          * so that the same path is followed in or out of the kernel.
  223          */
  224         if (flags & PFIL_IN)
  225                 TAILQ_INSERT_HEAD(list, pfh, pfil_link);
  226         else
  227                 TAILQ_INSERT_TAIL(list, pfh, pfil_link);
  228 
  229         return 0;
  230 }
  231 
  232 /*
  233  * pfil_remove_hook removes a specific function from the packet filter
  234  * hook list.
  235  */
  236 int
  237 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  238     void *arg, int flags, struct pfil_head *ph)
  239 {
  240         int err = 0;
  241 
  242         if (flags & PFIL_IN)
  243                 err = pfil_list_remove(&ph->ph_in, func, arg);
  244         if ((err == 0) && (flags & PFIL_OUT))
  245                 err = pfil_list_remove(&ph->ph_out, func, arg);
  246         if ((err == 0) && (flags & PFIL_IFADDR))
  247                 err = pfil_list_remove(&ph->ph_ifaddr, func, arg);
  248         if ((err == 0) && (flags & PFIL_IFNET))
  249                 err = pfil_list_remove(&ph->ph_ifnetevent, func, arg);
  250         return err;
  251 }
  252 
  253 /*
  254  * pfil_list_remove is an internal function that takes a function off the
  255  * specified list.
  256  */
  257 static int
  258 pfil_list_remove(pfil_list_t *list,
  259     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
  260 {
  261         struct packet_filter_hook *pfh;
  262 
  263         TAILQ_FOREACH(pfh, list, pfil_link) {
  264                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  265                         TAILQ_REMOVE(list, pfh, pfil_link);
  266                         free(pfh, M_IFADDR);
  267                         return 0;
  268                 }
  269         }
  270         return ENOENT;
  271 }

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

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