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

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    1 /*      $FreeBSD: head/sys/net/pfil.c 257176 2013-10-26 17:58:36Z glebius $ */
    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/if_var.h>
   49 #include <net/pfil.h>
   50 
   51 static struct mtx pfil_global_lock;
   52 
   53 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock",
   54   MTX_DEF);
   55 
   56 static struct packet_filter_hook *pfil_chain_get(int, struct pfil_head *);
   57 static int pfil_chain_add(pfil_chain_t *, struct packet_filter_hook *, int);
   58 static int pfil_chain_remove(pfil_chain_t *, pfil_func_t, void *);
   59 
   60 LIST_HEAD(pfilheadhead, pfil_head);
   61 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
   62 #define V_pfil_head_list        VNET(pfil_head_list)
   63 VNET_DEFINE(struct rmlock, pfil_lock);
   64 #define V_pfil_lock     VNET(pfil_lock)
   65 
   66 /*
   67  * pfil_run_hooks() runs the specified packet filter hook chain.
   68  */
   69 int
   70 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   71     int dir, struct inpcb *inp)
   72 {
   73         struct rm_priotracker rmpt;
   74         struct packet_filter_hook *pfh;
   75         struct mbuf *m = *mp;
   76         int rv = 0;
   77 
   78         PFIL_RLOCK(ph, &rmpt);
   79         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
   80         for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
   81              pfh = TAILQ_NEXT(pfh, pfil_chain)) {
   82                 if (pfh->pfil_func != NULL) {
   83                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
   84                             inp);
   85                         if (rv != 0 || m == NULL)
   86                                 break;
   87                 }
   88         }
   89         PFIL_RUNLOCK(ph, &rmpt);
   90         *mp = m;
   91         return (rv);
   92 }
   93 
   94 static struct packet_filter_hook *
   95 pfil_chain_get(int dir, struct pfil_head *ph)
   96 {
   97 
   98         if (dir == PFIL_IN)
   99                 return (TAILQ_FIRST(&ph->ph_in));
  100         else if (dir == PFIL_OUT)
  101                 return (TAILQ_FIRST(&ph->ph_out));
  102         else
  103                 return (NULL);
  104 }
  105 
  106 /*
  107  * pfil_try_rlock() acquires rm reader lock for specified head
  108  * if this is immediately possible.
  109  */
  110 int
  111 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  112 {
  113 
  114         return (PFIL_TRY_RLOCK(ph, tracker));
  115 }
  116 
  117 /*
  118  * pfil_rlock() acquires rm reader lock for specified head.
  119  */
  120 void
  121 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  122 {
  123 
  124         PFIL_RLOCK(ph, tracker);
  125 }
  126 
  127 /*
  128  * pfil_runlock() releases reader lock for specified head.
  129  */
  130 void
  131 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  132 {
  133 
  134         PFIL_RUNLOCK(ph, tracker);
  135 }
  136 
  137 /*
  138  * pfil_wlock() acquires writer lock for specified head.
  139  */
  140 void
  141 pfil_wlock(struct pfil_head *ph)
  142 {
  143 
  144         PFIL_WLOCK(ph);
  145 }
  146 
  147 /*
  148  * pfil_wunlock() releases writer lock for specified head.
  149  */
  150 void
  151 pfil_wunlock(struct pfil_head *ph)
  152 {
  153 
  154         PFIL_WUNLOCK(ph);
  155 }
  156 
  157 /*
  158  * pfil_wowned() returns a non-zero value if the current thread owns
  159  * an exclusive lock.
  160  */
  161 int
  162 pfil_wowned(struct pfil_head *ph)
  163 {
  164 
  165         return (PFIL_WOWNED(ph));
  166 }
  167 
  168 /*
  169  * pfil_head_register() registers a pfil_head with the packet filter hook
  170  * mechanism.
  171  */
  172 int
  173 pfil_head_register(struct pfil_head *ph)
  174 {
  175         struct pfil_head *lph;
  176 
  177         PFIL_HEADLIST_LOCK();
  178         LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
  179                 if (ph->ph_type == lph->ph_type &&
  180                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  181                         PFIL_HEADLIST_UNLOCK();
  182                         return (EEXIST);
  183                 }
  184         }
  185         PFIL_LOCK_INIT(ph);
  186         ph->ph_nhooks = 0;
  187         TAILQ_INIT(&ph->ph_in);
  188         TAILQ_INIT(&ph->ph_out);
  189         LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
  190         PFIL_HEADLIST_UNLOCK();
  191         return (0);
  192 }
  193 
  194 /*
  195  * pfil_head_unregister() removes a pfil_head from the packet filter hook
  196  * mechanism.  The producer of the hook promises that all outstanding
  197  * invocations of the hook have completed before it unregisters the hook.
  198  */
  199 int
  200 pfil_head_unregister(struct pfil_head *ph)
  201 {
  202         struct packet_filter_hook *pfh, *pfnext;
  203                 
  204         PFIL_HEADLIST_LOCK();
  205         LIST_REMOVE(ph, ph_list);
  206         PFIL_HEADLIST_UNLOCK();
  207         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
  208                 free(pfh, M_IFADDR);
  209         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
  210                 free(pfh, M_IFADDR);
  211         PFIL_LOCK_DESTROY(ph);
  212         return (0);
  213 }
  214 
  215 /*
  216  * pfil_head_get() returns the pfil_head for a given key/dlt.
  217  */
  218 struct pfil_head *
  219 pfil_head_get(int type, u_long val)
  220 {
  221         struct pfil_head *ph;
  222 
  223         PFIL_HEADLIST_LOCK();
  224         LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
  225                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  226                         break;
  227         PFIL_HEADLIST_UNLOCK();
  228         return (ph);
  229 }
  230 
  231 /*
  232  * pfil_add_hook() adds a function to the packet filter hook.  the
  233  * flags are:
  234  *      PFIL_IN         call me on incoming packets
  235  *      PFIL_OUT        call me on outgoing packets
  236  *      PFIL_ALL        call me on all of the above
  237  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  238  */
  239 int
  240 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  241 {
  242         struct packet_filter_hook *pfh1 = NULL;
  243         struct packet_filter_hook *pfh2 = NULL;
  244         int err;
  245 
  246         if (flags & PFIL_IN) {
  247                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  248                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  249                 if (pfh1 == NULL) {
  250                         err = ENOMEM;
  251                         goto error;
  252                 }
  253         }
  254         if (flags & PFIL_OUT) {
  255                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  256                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  257                 if (pfh2 == NULL) {
  258                         err = ENOMEM;
  259                         goto error;
  260                 }
  261         }
  262         PFIL_WLOCK(ph);
  263         if (flags & PFIL_IN) {
  264                 pfh1->pfil_func = func;
  265                 pfh1->pfil_arg = arg;
  266                 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  267                 if (err)
  268                         goto locked_error;
  269                 ph->ph_nhooks++;
  270         }
  271         if (flags & PFIL_OUT) {
  272                 pfh2->pfil_func = func;
  273                 pfh2->pfil_arg = arg;
  274                 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  275                 if (err) {
  276                         if (flags & PFIL_IN)
  277                                 pfil_chain_remove(&ph->ph_in, func, arg);
  278                         goto locked_error;
  279                 }
  280                 ph->ph_nhooks++;
  281         }
  282         PFIL_WUNLOCK(ph);
  283         return (0);
  284 locked_error:
  285         PFIL_WUNLOCK(ph);
  286 error:
  287         if (pfh1 != NULL)
  288                 free(pfh1, M_IFADDR);
  289         if (pfh2 != NULL)
  290                 free(pfh2, M_IFADDR);
  291         return (err);
  292 }
  293 
  294 /*
  295  * pfil_remove_hook removes a specific function from the packet filter hook
  296  * chain.
  297  */
  298 int
  299 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  300 {
  301         int err = 0;
  302 
  303         PFIL_WLOCK(ph);
  304         if (flags & PFIL_IN) {
  305                 err = pfil_chain_remove(&ph->ph_in, func, arg);
  306                 if (err == 0)
  307                         ph->ph_nhooks--;
  308         }
  309         if ((err == 0) && (flags & PFIL_OUT)) {
  310                 err = pfil_chain_remove(&ph->ph_out, func, arg);
  311                 if (err == 0)
  312                         ph->ph_nhooks--;
  313         }
  314         PFIL_WUNLOCK(ph);
  315         return (err);
  316 }
  317 
  318 /*
  319  * Internal: Add a new pfil hook into a hook chain.
  320  */
  321 static int
  322 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
  323 {
  324         struct packet_filter_hook *pfh;
  325 
  326         /*
  327          * First make sure the hook is not already there.
  328          */
  329         TAILQ_FOREACH(pfh, chain, pfil_chain)
  330                 if (pfh->pfil_func == pfh1->pfil_func &&
  331                     pfh->pfil_arg == pfh1->pfil_arg)
  332                         return (EEXIST);
  333 
  334         /*
  335          * Insert the input list in reverse order of the output list so that
  336          * the same path is followed in or out of the kernel.
  337          */
  338         if (flags & PFIL_IN)
  339                 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
  340         else
  341                 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
  342         return (0);
  343 }
  344 
  345 /*
  346  * Internal: Remove a pfil hook from a hook chain.
  347  */
  348 static int
  349 pfil_chain_remove(pfil_chain_t *chain, pfil_func_t func, void *arg)
  350 {
  351         struct packet_filter_hook *pfh;
  352 
  353         TAILQ_FOREACH(pfh, chain, pfil_chain)
  354                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  355                         TAILQ_REMOVE(chain, pfh, pfil_chain);
  356                         free(pfh, M_IFADDR);
  357                         return (0);
  358                 }
  359         return (ENOENT);
  360 }
  361 
  362 /*
  363  * Stuff that must be initialized for every instance (including the first of
  364  * course).
  365  */
  366 static int
  367 vnet_pfil_init(const void *unused)
  368 {
  369 
  370         LIST_INIT(&V_pfil_head_list);
  371         PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
  372         return (0);
  373 }
  374 
  375 /*
  376  * Called for the removal of each instance.
  377  */
  378 static int
  379 vnet_pfil_uninit(const void *unused)
  380 {
  381 
  382         KASSERT(LIST_EMPTY(&V_pfil_head_list),
  383             ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
  384         PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
  385         return (0);
  386 }
  387 
  388 /* Define startup order. */
  389 #define PFIL_SYSINIT_ORDER      SI_SUB_PROTO_BEGIN
  390 #define PFIL_MODEVENT_ORDER     (SI_ORDER_FIRST) /* On boot slot in here. */
  391 #define PFIL_VNET_ORDER         (PFIL_MODEVENT_ORDER + 2) /* Later still. */
  392 
  393 /*
  394  * Starting up.
  395  *
  396  * VNET_SYSINIT is called for each existing vnet and each new vnet.
  397  */
  398 VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
  399     vnet_pfil_init, NULL);
  400  
  401 /*
  402  * Closing up shop.  These are done in REVERSE ORDER.  Not called on reboot.
  403  *
  404  * VNET_SYSUNINIT is called for each exiting vnet as it exits.
  405  */
  406 VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
  407     vnet_pfil_uninit, NULL);

Cache object: 828239f8663bfd521c5f1a5e6f3ee1c3


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