pfil.c

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    1 /*      $FreeBSD: releng/5.4/sys/net/pfil.c 145335 2005-04-20 19:11:07Z cvs2svn $ */
    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/malloc.h>
   36 #include <sys/socket.h>
   37 #include <sys/socketvar.h>
   38 #include <sys/systm.h>
   39 #include <sys/condvar.h>
   40 #include <sys/lock.h>
   41 #include <sys/mutex.h>
   42 #include <sys/proc.h>
   43 #include <sys/queue.h>
   44 
   45 #include <net/if.h>
   46 #include <net/pfil.h>
   47 
   48 static struct mtx pfil_global_lock;
   49 
   50 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", MTX_DEF);
   51 
   52 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
   53 
   54 static int pfil_list_remove(pfil_list_t *,
   55     int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *);
   56 
   57 LIST_HEAD(, pfil_head) pfil_head_list =
   58     LIST_HEAD_INITIALIZER(&pfil_head_list);
   59 
   60 static __inline void
   61 PFIL_RLOCK(struct pfil_head *ph)
   62 {
   63         mtx_lock(&ph->ph_mtx);
   64         ph->ph_busy_count++;
   65         mtx_unlock(&ph->ph_mtx);
   66 }
   67 
   68 static __inline void
   69 PFIL_RUNLOCK(struct pfil_head *ph)
   70 {
   71         mtx_lock(&ph->ph_mtx);
   72         ph->ph_busy_count--;
   73         if (ph->ph_busy_count == 0 && ph->ph_want_write)
   74                 cv_signal(&ph->ph_cv);
   75         mtx_unlock(&ph->ph_mtx);
   76 }
   77 
   78 static __inline void
   79 PFIL_WLOCK(struct pfil_head *ph)
   80 {
   81         mtx_lock(&ph->ph_mtx);
   82         ph->ph_want_write = 1;
   83         while (ph->ph_busy_count > 0)
   84                 cv_wait(&ph->ph_cv, &ph->ph_mtx);
   85 }
   86 
   87 static __inline int
   88 PFIL_TRY_WLOCK(struct pfil_head *ph)
   89 {
   90         mtx_lock(&ph->ph_mtx);
   91         ph->ph_want_write = 1;
   92         if (ph->ph_busy_count > 0) {
   93                 ph->ph_want_write = 0;
   94                 mtx_unlock(&ph->ph_mtx);
   95                 return EBUSY;
   96         }
   97         return 0;
   98 }
   99 
  100 static __inline void
  101 PFIL_WUNLOCK(struct pfil_head *ph)
  102 {
  103         ph->ph_want_write = 0;
  104         cv_signal(&ph->ph_cv);
  105         mtx_unlock(&ph->ph_mtx);
  106 }
  107 
  108 #define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock)
  109 #define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock)
  110 
  111 /*
  112  * pfil_run_hooks() runs the specified packet filter hooks.
  113  */
  114 int
  115 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
  116     int dir, struct inpcb *inp)
  117 {
  118         struct packet_filter_hook *pfh;
  119         struct mbuf *m = *mp;
  120         int rv = 0;
  121 
  122         /*
  123          * Prevent packet filtering from starving the modification of
  124          * the packet filters. We would prefer a reader/writer locking
  125          * mechanism with guaranteed ordering, though.
  126          */
  127         if (ph->ph_busy_count == -1 || ph->ph_want_write) {
  128                 m_freem(*mp);
  129                 *mp = NULL;
  130                 return (ENOBUFS);
  131         }
  132 
  133         PFIL_RLOCK(ph);
  134         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
  135              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  136                 if (pfh->pfil_func != NULL) {
  137                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp);
  138                         if (rv != 0 || m == NULL)
  139                                 break;
  140                 }
  141         }
  142         PFIL_RUNLOCK(ph);
  143         
  144         *mp = m;
  145         return (rv);
  146 }
  147 
  148 /*
  149  * pfil_head_register() registers a pfil_head with the packet filter
  150  * hook mechanism.
  151  */
  152 int
  153 pfil_head_register(struct pfil_head *ph)
  154 {
  155         struct pfil_head *lph;
  156 
  157         PFIL_LIST_LOCK();
  158         LIST_FOREACH(lph, &pfil_head_list, ph_list)
  159                 if (ph->ph_type == lph->ph_type &&
  160                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  161                         PFIL_LIST_UNLOCK();
  162                         return EEXIST;
  163                 }
  164         PFIL_LIST_UNLOCK();
  165 
  166         if (mtx_initialized(&ph->ph_mtx)) {     /* should not happen */
  167                 KASSERT((0), ("%s: allready initialized!", __func__));
  168                 return EBUSY;
  169         } else {
  170                 ph->ph_busy_count = -1;
  171                 ph->ph_want_write = 1;
  172                 mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF);
  173                 cv_init(&ph->ph_cv, "pfil_head_cv");
  174                 mtx_lock(&ph->ph_mtx);                  /* XXX: race? */
  175         }
  176 
  177         TAILQ_INIT(&ph->ph_in);
  178         TAILQ_INIT(&ph->ph_out);
  179 
  180         PFIL_LIST_LOCK();
  181         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  182         PFIL_LIST_UNLOCK();
  183         
  184         PFIL_WUNLOCK(ph);
  185         
  186         return (0);
  187 }
  188 
  189 /*
  190  * pfil_head_unregister() removes a pfil_head from the packet filter
  191  * hook mechanism.
  192  */
  193 int
  194 pfil_head_unregister(struct pfil_head *ph)
  195 {
  196         struct packet_filter_hook *pfh, *pfnext;
  197                 
  198         PFIL_LIST_LOCK();
  199         /* 
  200          * LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
  201          * No need to WLOCK all of them.
  202          */
  203         LIST_REMOVE(ph, ph_list);
  204         PFIL_LIST_UNLOCK();
  205 
  206         PFIL_WLOCK(ph);                 /* XXX: may sleep (cv_wait)! */
  207         
  208         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
  209                 free(pfh, M_IFADDR);
  210         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
  211                 free(pfh, M_IFADDR);
  212         cv_destroy(&ph->ph_cv);
  213         mtx_destroy(&ph->ph_mtx);
  214         
  215         return (0);
  216 }
  217 
  218 /*
  219  * pfil_head_get() returns the pfil_head for a given key/dlt.
  220  */
  221 struct pfil_head *
  222 pfil_head_get(int type, u_long val)
  223 {
  224         struct pfil_head *ph;
  225 
  226         PFIL_LIST_LOCK();
  227         LIST_FOREACH(ph, &pfil_head_list, ph_list)
  228                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  229                         break;
  230         PFIL_LIST_UNLOCK();
  231         
  232         return (ph);
  233 }
  234 
  235 /*
  236  * pfil_add_hook() adds a function to the packet filter hook.  the
  237  * flags are:
  238  *      PFIL_IN         call me on incoming packets
  239  *      PFIL_OUT        call me on outgoing packets
  240  *      PFIL_ALL        call me on all of the above
  241  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  242  */
  243 int
  244 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
  245     void *arg, int flags, struct pfil_head *ph)
  246 {
  247         struct packet_filter_hook *pfh1 = NULL;
  248         struct packet_filter_hook *pfh2 = NULL;
  249         int err;
  250 
  251         /* Get memory */
  252         if (flags & PFIL_IN) {
  253                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  254                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  255                 if (pfh1 == NULL) {
  256                         err = ENOMEM;
  257                         goto error;
  258                 }
  259         }
  260         if (flags & PFIL_OUT) {
  261                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  262                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  263                 if (pfh2 == NULL) {
  264                         err = ENOMEM;
  265                         goto error;
  266                 }
  267         }
  268 
  269         /* Lock */
  270         if (flags & PFIL_WAITOK)
  271                 PFIL_WLOCK(ph);
  272         else {
  273                 err = PFIL_TRY_WLOCK(ph);
  274                 if (err)
  275                         goto error;
  276         }
  277 
  278         /* Add */
  279         if (flags & PFIL_IN) {
  280                 pfh1->pfil_func = func;
  281                 pfh1->pfil_arg = arg;
  282                 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  283                 if (err)
  284                         goto done;
  285         }
  286         if (flags & PFIL_OUT) {
  287                 pfh2->pfil_func = func;
  288                 pfh2->pfil_arg = arg;
  289                 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  290                 if (err) {
  291                         if (flags & PFIL_IN)
  292                                 pfil_list_remove(&ph->ph_in, func, arg);
  293                         goto done;
  294                 }
  295         }
  296 
  297         ph->ph_busy_count = 0;
  298         PFIL_WUNLOCK(ph);
  299 
  300         return 0;
  301 done:
  302         PFIL_WUNLOCK(ph);
  303 error:
  304         if (pfh1 != NULL)
  305                 free(pfh1, M_IFADDR);
  306         if (pfh2 != NULL)
  307                 free(pfh2, M_IFADDR);
  308         return err;
  309 }
  310 
  311 /*
  312  * pfil_remove_hook removes a specific function from the packet filter
  313  * hook list.
  314  */
  315 int
  316 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
  317     void *arg, int flags, struct pfil_head *ph)
  318 {
  319         int err = 0;
  320 
  321         if (flags & PFIL_WAITOK)
  322                 PFIL_WLOCK(ph);
  323         else {
  324                 err = PFIL_TRY_WLOCK(ph);
  325                 if (err)
  326                         return err;
  327         }
  328 
  329         if (flags & PFIL_IN)
  330                 err = pfil_list_remove(&ph->ph_in, func, arg);
  331         if ((err == 0) && (flags & PFIL_OUT))
  332                 err = pfil_list_remove(&ph->ph_out, func, arg);
  333 
  334         if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
  335                 ph->ph_busy_count = -1;
  336 
  337         PFIL_WUNLOCK(ph);
  338         
  339         return err;
  340 }
  341 
  342 static int
  343 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
  344 {
  345         struct packet_filter_hook *pfh;
  346 
  347         /*
  348          * First make sure the hook is not already there.
  349          */
  350         TAILQ_FOREACH(pfh, list, pfil_link)
  351                 if (pfh->pfil_func == pfh1->pfil_func &&
  352                     pfh->pfil_arg == pfh1->pfil_arg)
  353                         return EEXIST;
  354         /*
  355          * insert the input list in reverse order of the output list
  356          * so that the same path is followed in or out of the kernel.
  357          */
  358         if (flags & PFIL_IN)
  359                 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
  360         else
  361                 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
  362 
  363         return 0;
  364 }
  365 
  366 /*
  367  * pfil_list_remove is an internal function that takes a function off the
  368  * specified list.
  369  */
  370 static int
  371 pfil_list_remove(pfil_list_t *list,
  372     int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg)
  373 {
  374         struct packet_filter_hook *pfh;
  375 
  376         TAILQ_FOREACH(pfh, list, pfil_link)
  377                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  378                         TAILQ_REMOVE(list, pfh, pfil_link);
  379                         free(pfh, M_IFADDR);
  380                         return 0;
  381                 }
  382         return ENOENT;
  383 }
Cache object: a71909b2963b1abe0d75a5da78706ae3
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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