pfil.c

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    1 /*      $FreeBSD: releng/8.0/sys/net/pfil.c 198326 2009-10-21 14:05:51Z rwatson $ */
    2 /*      $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $  */
    3 
    4 /*-
    5  * Copyright (c) 1996 Matthew R. Green
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. The name of the author may not be used to endorse or promote products
   17  *    derived from this software without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   27  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/param.h>
   33 #include <sys/kernel.h>
   34 #include <sys/errno.h>
   35 #include <sys/lock.h>
   36 #include <sys/malloc.h>
   37 #include <sys/rmlock.h>
   38 #include <sys/socket.h>
   39 #include <sys/socketvar.h>
   40 #include <sys/systm.h>
   41 #include <sys/condvar.h>
   42 #include <sys/lock.h>
   43 #include <sys/mutex.h>
   44 #include <sys/proc.h>
   45 #include <sys/queue.h>
   46 
   47 #include <net/if.h>
   48 #include <net/pfil.h>
   49 
   50 static struct mtx pfil_global_lock;
   51 
   52 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock",
   53   MTX_DEF);
   54 
   55 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
   56 
   57 static int pfil_list_remove(pfil_list_t *,
   58     int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
   59     void *);
   60 
   61 LIST_HEAD(, pfil_head) pfil_head_list =
   62     LIST_HEAD_INITIALIZER(&pfil_head_list);
   63 
   64 /*
   65  * pfil_run_hooks() runs the specified packet filter hooks.
   66  */
   67 int
   68 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   69     int dir, struct inpcb *inp)
   70 {
   71         struct rm_priotracker rmpt;
   72         struct packet_filter_hook *pfh;
   73         struct mbuf *m = *mp;
   74         int rv = 0;
   75 
   76         PFIL_RLOCK(ph, &rmpt);
   77         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
   78         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
   79              pfh = TAILQ_NEXT(pfh, pfil_link)) {
   80                 if (pfh->pfil_func != NULL) {
   81                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
   82                             inp);
   83                         if (rv != 0 || m == NULL)
   84                                 break;
   85                 }
   86         }
   87         PFIL_RUNLOCK(ph, &rmpt);
   88         *mp = m;
   89         return (rv);
   90 }
   91 
   92 /*
   93  * pfil_head_register() registers a pfil_head with the packet filter hook
   94  * mechanism.
   95  */
   96 int
   97 pfil_head_register(struct pfil_head *ph)
   98 {
   99         struct pfil_head *lph;
  100 
  101         PFIL_LIST_LOCK();
  102         LIST_FOREACH(lph, &pfil_head_list, ph_list) {
  103                 if (ph->ph_type == lph->ph_type &&
  104                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  105                         PFIL_LIST_UNLOCK();
  106                         return (EEXIST);
  107                 }
  108         }
  109         PFIL_LOCK_INIT(ph);
  110         ph->ph_nhooks = 0;
  111         TAILQ_INIT(&ph->ph_in);
  112         TAILQ_INIT(&ph->ph_out);
  113         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  114         PFIL_LIST_UNLOCK();
  115         return (0);
  116 }
  117 
  118 /*
  119  * pfil_head_unregister() removes a pfil_head from the packet filter hook
  120  * mechanism.  The producer of the hook promises that all outstanding
  121  * invocations of the hook have completed before it unregisters the hook.
  122  */
  123 int
  124 pfil_head_unregister(struct pfil_head *ph)
  125 {
  126         struct packet_filter_hook *pfh, *pfnext;
  127                 
  128         PFIL_LIST_LOCK();
  129         LIST_REMOVE(ph, ph_list);
  130         PFIL_LIST_UNLOCK();
  131         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
  132                 free(pfh, M_IFADDR);
  133         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
  134                 free(pfh, M_IFADDR);
  135         PFIL_LOCK_DESTROY(ph);
  136         return (0);
  137 }
  138 
  139 /*
  140  * pfil_head_get() returns the pfil_head for a given key/dlt.
  141  */
  142 struct pfil_head *
  143 pfil_head_get(int type, u_long val)
  144 {
  145         struct pfil_head *ph;
  146 
  147         PFIL_LIST_LOCK();
  148         LIST_FOREACH(ph, &pfil_head_list, ph_list)
  149                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  150                         break;
  151         PFIL_LIST_UNLOCK();
  152         return (ph);
  153 }
  154 
  155 /*
  156  * pfil_add_hook() adds a function to the packet filter hook.  the
  157  * flags are:
  158  *      PFIL_IN         call me on incoming packets
  159  *      PFIL_OUT        call me on outgoing packets
  160  *      PFIL_ALL        call me on all of the above
  161  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  162  */
  163 int
  164 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int,
  165   struct inpcb *), void *arg, int flags, struct pfil_head *ph)
  166 {
  167         struct packet_filter_hook *pfh1 = NULL;
  168         struct packet_filter_hook *pfh2 = NULL;
  169         int err;
  170 
  171         if (flags & PFIL_IN) {
  172                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  173                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  174                 if (pfh1 == NULL) {
  175                         err = ENOMEM;
  176                         goto error;
  177                 }
  178         }
  179         if (flags & PFIL_OUT) {
  180                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  181                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  182                 if (pfh2 == NULL) {
  183                         err = ENOMEM;
  184                         goto error;
  185                 }
  186         }
  187         PFIL_WLOCK(ph);
  188         if (flags & PFIL_IN) {
  189                 pfh1->pfil_func = func;
  190                 pfh1->pfil_arg = arg;
  191                 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  192                 if (err)
  193                         goto locked_error;
  194                 ph->ph_nhooks++;
  195         }
  196         if (flags & PFIL_OUT) {
  197                 pfh2->pfil_func = func;
  198                 pfh2->pfil_arg = arg;
  199                 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  200                 if (err) {
  201                         if (flags & PFIL_IN)
  202                                 pfil_list_remove(&ph->ph_in, func, arg);
  203                         goto locked_error;
  204                 }
  205                 ph->ph_nhooks++;
  206         }
  207         PFIL_WUNLOCK(ph);
  208         return (0);
  209 locked_error:
  210         PFIL_WUNLOCK(ph);
  211 error:
  212         if (pfh1 != NULL)
  213                 free(pfh1, M_IFADDR);
  214         if (pfh2 != NULL)
  215                 free(pfh2, M_IFADDR);
  216         return (err);
  217 }
  218 
  219 /*
  220  * pfil_remove_hook removes a specific function from the packet filter hook
  221  * list.
  222  */
  223 int
  224 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int,
  225     struct inpcb *), void *arg, int flags, struct pfil_head *ph)
  226 {
  227         int err = 0;
  228 
  229         PFIL_WLOCK(ph);
  230         if (flags & PFIL_IN) {
  231                 err = pfil_list_remove(&ph->ph_in, func, arg);
  232                 if (err == 0)
  233                         ph->ph_nhooks--;
  234         }
  235         if ((err == 0) && (flags & PFIL_OUT)) {
  236                 err = pfil_list_remove(&ph->ph_out, func, arg);
  237                 if (err == 0)
  238                         ph->ph_nhooks--;
  239         }
  240         PFIL_WUNLOCK(ph);
  241         return (err);
  242 }
  243 
  244 static int
  245 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
  246 {
  247         struct packet_filter_hook *pfh;
  248 
  249         /*
  250          * First make sure the hook is not already there.
  251          */
  252         TAILQ_FOREACH(pfh, list, pfil_link)
  253                 if (pfh->pfil_func == pfh1->pfil_func &&
  254                     pfh->pfil_arg == pfh1->pfil_arg)
  255                         return (EEXIST);
  256 
  257         /*
  258          * Insert the input list in reverse order of the output list so that
  259          * the same path is followed in or out of the kernel.
  260          */
  261         if (flags & PFIL_IN)
  262                 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
  263         else
  264                 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
  265         return (0);
  266 }
  267 
  268 /*
  269  * pfil_list_remove is an internal function that takes a function off the
  270  * specified list.
  271  */
  272 static int
  273 pfil_list_remove(pfil_list_t *list,
  274     int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
  275     void *arg)
  276 {
  277         struct packet_filter_hook *pfh;
  278 
  279         TAILQ_FOREACH(pfh, list, pfil_link)
  280                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  281                         TAILQ_REMOVE(list, pfh, pfil_link);
  282                         free(pfh, M_IFADDR);
  283                         return (0);
  284                 }
  285         return (ENOENT);
  286 }
Cache object: ac3f51b8f82c8ab3308e2800c4cf5c5d
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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