The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*      $FreeBSD: releng/5.2/sys/net/pfil.c 120386 2003-09-23 17:54:04Z sam $ */
    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), 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         mtx_unlock(&ph->ph_mtx);
  105         cv_signal(&ph->ph_cv);
  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)
  117 {
  118         struct packet_filter_hook *pfh;
  119         struct mbuf *m = *mp;
  120         int rv = 0;
  121 
  122         if (ph->ph_busy_count == -1 || ph->ph_want_write)
  123                 return (0);
  124 
  125         PFIL_RLOCK(ph);
  126         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
  127              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  128                 if (pfh->pfil_func != NULL) {
  129                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir);
  130                         if (rv != 0 || m == NULL)
  131                                 break;
  132                 }
  133         }
  134         PFIL_RUNLOCK(ph);
  135         
  136         *mp = m;
  137         return (rv);
  138 }
  139 
  140 /*
  141  * pfil_head_register() registers a pfil_head with the packet filter
  142  * hook mechanism.
  143  */
  144 int
  145 pfil_head_register(struct pfil_head *ph)
  146 {
  147         struct pfil_head *lph;
  148 
  149         PFIL_LIST_LOCK();
  150         LIST_FOREACH(lph, &pfil_head_list, ph_list)
  151                 if (ph->ph_type == lph->ph_type &&
  152                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  153                         PFIL_LIST_UNLOCK();
  154                         return EEXIST;
  155                 }
  156         PFIL_LIST_UNLOCK();
  157 
  158         if (mtx_initialized(&ph->ph_mtx)) {     /* should not happen */
  159                 KASSERT((0), ("%s: allready initialized!", __func__));
  160                 return EBUSY;
  161         } else {
  162                 ph->ph_busy_count = -1;
  163                 ph->ph_want_write = 1;
  164                 mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF);
  165                 cv_init(&ph->ph_cv, "pfil_head_cv");
  166                 mtx_lock(&ph->ph_mtx);                  /* XXX: race? */
  167         }
  168 
  169         TAILQ_INIT(&ph->ph_in);
  170         TAILQ_INIT(&ph->ph_out);
  171 
  172         PFIL_LIST_LOCK();
  173         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  174         PFIL_LIST_UNLOCK();
  175         
  176         PFIL_WUNLOCK(ph);
  177         
  178         return (0);
  179 }
  180 
  181 /*
  182  * pfil_head_unregister() removes a pfil_head from the packet filter
  183  * hook mechanism.
  184  */
  185 int
  186 pfil_head_unregister(struct pfil_head *ph)
  187 {
  188         struct packet_filter_hook *pfh, *pfnext;
  189                 
  190         PFIL_LIST_LOCK();
  191         /* 
  192          * LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
  193          * No need to WLOCK all of them.
  194          */
  195         LIST_REMOVE(ph, ph_list);
  196         PFIL_LIST_UNLOCK();
  197 
  198         PFIL_WLOCK(ph);                 /* XXX: may sleep (cv_wait)! */
  199         
  200         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
  201                 free(pfh, M_IFADDR);
  202         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
  203                 free(pfh, M_IFADDR);
  204         cv_destroy(&ph->ph_cv);
  205         mtx_destroy(&ph->ph_mtx);
  206         
  207         return (0);
  208 }
  209 
  210 /*
  211  * pfil_head_get() returns the pfil_head for a given key/dlt.
  212  */
  213 struct pfil_head *
  214 pfil_head_get(int type, u_long val)
  215 {
  216         struct pfil_head *ph;
  217 
  218         PFIL_LIST_LOCK();
  219         LIST_FOREACH(ph, &pfil_head_list, ph_list)
  220                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  221                         break;
  222         PFIL_LIST_UNLOCK();
  223         
  224         return (ph);
  225 }
  226 
  227 /*
  228  * pfil_add_hook() adds a function to the packet filter hook.  the
  229  * flags are:
  230  *      PFIL_IN         call me on incoming packets
  231  *      PFIL_OUT        call me on outgoing packets
  232  *      PFIL_ALL        call me on all of the above
  233  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  234  */
  235 int
  236 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  237     void *arg, int flags, struct pfil_head *ph)
  238 {
  239         struct packet_filter_hook *pfh1 = NULL;
  240         struct packet_filter_hook *pfh2 = NULL;
  241         int err;
  242 
  243         /* Get memory */
  244         if (flags & PFIL_IN) {
  245                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  246                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  247                 if (pfh1 == NULL) {
  248                         err = ENOMEM;
  249                         goto error;
  250                 }
  251         }
  252         if (flags & PFIL_OUT) {
  253                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  254                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  255                 if (pfh2 == NULL) {
  256                         err = ENOMEM;
  257                         goto error;
  258                 }
  259         }
  260 
  261         /* Lock */
  262         if (flags & PFIL_WAITOK)
  263                 PFIL_WLOCK(ph);
  264         else {
  265                 err = PFIL_TRY_WLOCK(ph);
  266                 if (err)
  267                         goto error;
  268         }
  269 
  270         /* Add */
  271         if (flags & PFIL_IN) {
  272                 pfh1->pfil_func = func;
  273                 pfh1->pfil_arg = arg;
  274                 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  275                 if (err)
  276                         goto done;
  277         }
  278         if (flags & PFIL_OUT) {
  279                 pfh2->pfil_func = func;
  280                 pfh2->pfil_arg = arg;
  281                 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  282                 if (err) {
  283                         if (flags & PFIL_IN)
  284                                 pfil_list_remove(&ph->ph_in, func, arg);
  285                         goto done;
  286                 }
  287         }
  288 
  289         ph->ph_busy_count = 0;
  290         PFIL_WUNLOCK(ph);
  291 
  292         return 0;
  293 done:
  294         PFIL_WUNLOCK(ph);
  295 error:
  296         if (pfh1 != NULL)
  297                 free(pfh1, M_IFADDR);
  298         if (pfh2 != NULL)
  299                 free(pfh2, M_IFADDR);
  300         return err;
  301 }
  302 
  303 /*
  304  * pfil_remove_hook removes a specific function from the packet filter
  305  * hook list.
  306  */
  307 int
  308 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
  309     void *arg, int flags, struct pfil_head *ph)
  310 {
  311         int err = 0;
  312 
  313         if (flags & PFIL_WAITOK)
  314                 PFIL_WLOCK(ph);
  315         else {
  316                 err = PFIL_TRY_WLOCK(ph);
  317                 if (err)
  318                         return err;
  319         }
  320 
  321         if (flags & PFIL_IN)
  322                 err = pfil_list_remove(&ph->ph_in, func, arg);
  323         if ((err == 0) && (flags & PFIL_OUT))
  324                 err = pfil_list_remove(&ph->ph_out, func, arg);
  325 
  326         if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
  327                 ph->ph_busy_count = -1;
  328 
  329         PFIL_WUNLOCK(ph);
  330         
  331         return err;
  332 }
  333 
  334 static int
  335 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
  336 {
  337         struct packet_filter_hook *pfh;
  338 
  339         /*
  340          * First make sure the hook is not already there.
  341          */
  342         TAILQ_FOREACH(pfh, list, pfil_link)
  343                 if (pfh->pfil_func == pfh1->pfil_func &&
  344                     pfh->pfil_arg == pfh1->pfil_arg)
  345                         return EEXIST;
  346         /*
  347          * insert the input list in reverse order of the output list
  348          * so that the same path is followed in or out of the kernel.
  349          */
  350         if (flags & PFIL_IN)
  351                 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
  352         else
  353                 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
  354 
  355         return 0;
  356 }
  357 
  358 /*
  359  * pfil_list_remove is an internal function that takes a function off the
  360  * specified list.
  361  */
  362 static int
  363 pfil_list_remove(pfil_list_t *list,
  364     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
  365 {
  366         struct packet_filter_hook *pfh;
  367 
  368         TAILQ_FOREACH(pfh, list, pfil_link)
  369                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  370                         TAILQ_REMOVE(list, pfh, pfil_link);
  371                         free(pfh, M_IFADDR);
  372                         return 0;
  373                 }
  374         return ENOENT;
  375 }

Cache object: 460e8f1cc39d80293d3724cd642b1fd3


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