pfil.c

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    1 /*      $FreeBSD: releng/7.4/sys/net/pfil.c 155201 2006-02-02 03:13:16Z csjp $ */
    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/rwlock.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", MTX_DEF);
   53 
   54 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
   55 
   56 static int pfil_list_remove(pfil_list_t *,
   57     int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *);
   58 
   59 LIST_HEAD(, pfil_head) pfil_head_list =
   60     LIST_HEAD_INITIALIZER(&pfil_head_list);
   61 
   62 /*
   63  * pfil_run_hooks() runs the specified packet filter hooks.
   64  */
   65 int
   66 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   67     int dir, struct inpcb *inp)
   68 {
   69         struct packet_filter_hook *pfh;
   70         struct mbuf *m = *mp;
   71         int rv = 0;
   72 
   73         PFIL_RLOCK(ph);
   74         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
   75         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
   76              pfh = TAILQ_NEXT(pfh, pfil_link)) {
   77                 if (pfh->pfil_func != NULL) {
   78                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp);
   79                         if (rv != 0 || m == NULL)
   80                                 break;
   81                 }
   82         }
   83         PFIL_RUNLOCK(ph);
   84         
   85         *mp = m;
   86         return (rv);
   87 }
   88 
   89 /*
   90  * pfil_head_register() registers a pfil_head with the packet filter
   91  * hook mechanism.
   92  */
   93 int
   94 pfil_head_register(struct pfil_head *ph)
   95 {
   96         struct pfil_head *lph;
   97 
   98         PFIL_LIST_LOCK();
   99         LIST_FOREACH(lph, &pfil_head_list, ph_list)
  100                 if (ph->ph_type == lph->ph_type &&
  101                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  102                         PFIL_LIST_UNLOCK();
  103                         return EEXIST;
  104                 }
  105         PFIL_LIST_UNLOCK();
  106 
  107         rw_init(&ph->ph_mtx, "PFil hook read/write mutex");
  108         PFIL_WLOCK(ph);
  109         ph->ph_nhooks = 0;
  110 
  111         TAILQ_INIT(&ph->ph_in);
  112         TAILQ_INIT(&ph->ph_out);
  113 
  114         PFIL_LIST_LOCK();
  115         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  116         PFIL_LIST_UNLOCK();
  117 
  118         PFIL_WUNLOCK(ph);
  119 
  120         return (0);
  121 }
  122 
  123 /*
  124  * pfil_head_unregister() removes a pfil_head from the packet filter
  125  * hook mechanism.
  126  */
  127 int
  128 pfil_head_unregister(struct pfil_head *ph)
  129 {
  130         struct packet_filter_hook *pfh, *pfnext;
  131                 
  132         PFIL_LIST_LOCK();
  133         /* 
  134          * LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
  135          * No need to WLOCK all of them.
  136          */
  137         LIST_REMOVE(ph, ph_list);
  138         PFIL_LIST_UNLOCK();
  139 
  140         PFIL_WLOCK(ph);
  141         
  142         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
  143                 free(pfh, M_IFADDR);
  144         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
  145                 free(pfh, M_IFADDR);
  146         rw_destroy(&ph->ph_mtx);
  147         
  148         return (0);
  149 }
  150 
  151 /*
  152  * pfil_head_get() returns the pfil_head for a given key/dlt.
  153  */
  154 struct pfil_head *
  155 pfil_head_get(int type, u_long val)
  156 {
  157         struct pfil_head *ph;
  158 
  159         PFIL_LIST_LOCK();
  160         LIST_FOREACH(ph, &pfil_head_list, ph_list)
  161                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  162                         break;
  163         PFIL_LIST_UNLOCK();
  164         
  165         return (ph);
  166 }
  167 
  168 /*
  169  * pfil_add_hook() adds a function to the packet filter hook.  the
  170  * flags are:
  171  *      PFIL_IN         call me on incoming packets
  172  *      PFIL_OUT        call me on outgoing packets
  173  *      PFIL_ALL        call me on all of the above
  174  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  175  */
  176 int
  177 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
  178     void *arg, int flags, struct pfil_head *ph)
  179 {
  180         struct packet_filter_hook *pfh1 = NULL;
  181         struct packet_filter_hook *pfh2 = NULL;
  182         int err;
  183 
  184         /* Get memory */
  185         if (flags & PFIL_IN) {
  186                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  187                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  188                 if (pfh1 == NULL) {
  189                         err = ENOMEM;
  190                         goto error;
  191                 }
  192         }
  193         if (flags & PFIL_OUT) {
  194                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  195                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  196                 if (pfh2 == NULL) {
  197                         err = ENOMEM;
  198                         goto error;
  199                 }
  200         }
  201 
  202         /* Lock */
  203         PFIL_WLOCK(ph);
  204 
  205         /* Add */
  206         if (flags & PFIL_IN) {
  207                 pfh1->pfil_func = func;
  208                 pfh1->pfil_arg = arg;
  209                 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  210                 if (err)
  211                         goto done;
  212                 ph->ph_nhooks++;
  213         }
  214         if (flags & PFIL_OUT) {
  215                 pfh2->pfil_func = func;
  216                 pfh2->pfil_arg = arg;
  217                 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  218                 if (err) {
  219                         if (flags & PFIL_IN)
  220                                 pfil_list_remove(&ph->ph_in, func, arg);
  221                         goto done;
  222                 }
  223                 ph->ph_nhooks++;
  224         }
  225 
  226         PFIL_WUNLOCK(ph);
  227 
  228         return 0;
  229 done:
  230         PFIL_WUNLOCK(ph);
  231 error:
  232         if (pfh1 != NULL)
  233                 free(pfh1, M_IFADDR);
  234         if (pfh2 != NULL)
  235                 free(pfh2, M_IFADDR);
  236         return err;
  237 }
  238 
  239 /*
  240  * pfil_remove_hook removes a specific function from the packet filter
  241  * hook list.
  242  */
  243 int
  244 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
  245     void *arg, int flags, struct pfil_head *ph)
  246 {
  247         int err = 0;
  248 
  249         PFIL_WLOCK(ph);
  250 
  251         if (flags & PFIL_IN) {
  252                 err = pfil_list_remove(&ph->ph_in, func, arg);
  253                 if (err == 0)
  254                         ph->ph_nhooks--;
  255         }
  256         if ((err == 0) && (flags & PFIL_OUT)) {
  257                 err = pfil_list_remove(&ph->ph_out, func, arg);
  258                 if (err == 0)
  259                         ph->ph_nhooks--;
  260         }
  261         PFIL_WUNLOCK(ph);
  262         
  263         return err;
  264 }
  265 
  266 static int
  267 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
  268 {
  269         struct packet_filter_hook *pfh;
  270 
  271         /*
  272          * First make sure the hook is not already there.
  273          */
  274         TAILQ_FOREACH(pfh, list, pfil_link)
  275                 if (pfh->pfil_func == pfh1->pfil_func &&
  276                     pfh->pfil_arg == pfh1->pfil_arg)
  277                         return EEXIST;
  278         /*
  279          * insert the input list in reverse order of the output list
  280          * so that the same path is followed in or out of the kernel.
  281          */
  282         if (flags & PFIL_IN)
  283                 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
  284         else
  285                 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
  286 
  287         return 0;
  288 }
  289 
  290 /*
  291  * pfil_list_remove is an internal function that takes a function off the
  292  * specified list.
  293  */
  294 static int
  295 pfil_list_remove(pfil_list_t *list,
  296     int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg)
  297 {
  298         struct packet_filter_hook *pfh;
  299 
  300         TAILQ_FOREACH(pfh, list, pfil_link)
  301                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  302                         TAILQ_REMOVE(list, pfh, pfil_link);
  303                         free(pfh, M_IFADDR);
  304                         return 0;
  305                 }
  306         return ENOENT;
  307 }
Cache object: 2d950182660f948ee6c07f1aee53599b
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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