pfil.c

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    1 /*      $FreeBSD: releng/10.1/sys/net/pfil.c 254774 2013-08-24 11:24:15Z andre $ */
    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 struct packet_filter_hook *pfil_chain_get(int, struct pfil_head *);
   56 static int pfil_chain_add(pfil_chain_t *, struct packet_filter_hook *, int);
   57 static int pfil_chain_remove(pfil_chain_t *, pfil_func_t, void *);
   58 
   59 LIST_HEAD(pfilheadhead, pfil_head);
   60 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
   61 #define V_pfil_head_list        VNET(pfil_head_list)
   62 VNET_DEFINE(struct rmlock, pfil_lock);
   63 #define V_pfil_lock     VNET(pfil_lock)
   64 
   65 /*
   66  * pfil_run_hooks() runs the specified packet filter hook chain.
   67  */
   68 int
   69 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   70     int dir, struct inpcb *inp)
   71 {
   72         struct rm_priotracker rmpt;
   73         struct packet_filter_hook *pfh;
   74         struct mbuf *m = *mp;
   75         int rv = 0;
   76 
   77         PFIL_RLOCK(ph, &rmpt);
   78         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
   79         for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
   80              pfh = TAILQ_NEXT(pfh, pfil_chain)) {
   81                 if (pfh->pfil_func != NULL) {
   82                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
   83                             inp);
   84                         if (rv != 0 || m == NULL)
   85                                 break;
   86                 }
   87         }
   88         PFIL_RUNLOCK(ph, &rmpt);
   89         *mp = m;
   90         return (rv);
   91 }
   92 
   93 static struct packet_filter_hook *
   94 pfil_chain_get(int dir, struct pfil_head *ph)
   95 {
   96 
   97         if (dir == PFIL_IN)
   98                 return (TAILQ_FIRST(&ph->ph_in));
   99         else if (dir == PFIL_OUT)
  100                 return (TAILQ_FIRST(&ph->ph_out));
  101         else
  102                 return (NULL);
  103 }
  104 
  105 /*
  106  * pfil_try_rlock() acquires rm reader lock for specified head
  107  * if this is immediately possible.
  108  */
  109 int
  110 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  111 {
  112 
  113         return (PFIL_TRY_RLOCK(ph, tracker));
  114 }
  115 
  116 /*
  117  * pfil_rlock() acquires rm reader lock for specified head.
  118  */
  119 void
  120 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  121 {
  122 
  123         PFIL_RLOCK(ph, tracker);
  124 }
  125 
  126 /*
  127  * pfil_runlock() releases reader lock for specified head.
  128  */
  129 void
  130 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  131 {
  132 
  133         PFIL_RUNLOCK(ph, tracker);
  134 }
  135 
  136 /*
  137  * pfil_wlock() acquires writer lock for specified head.
  138  */
  139 void
  140 pfil_wlock(struct pfil_head *ph)
  141 {
  142 
  143         PFIL_WLOCK(ph);
  144 }
  145 
  146 /*
  147  * pfil_wunlock() releases writer lock for specified head.
  148  */
  149 void
  150 pfil_wunlock(struct pfil_head *ph)
  151 {
  152 
  153         PFIL_WUNLOCK(ph);
  154 }
  155 
  156 /*
  157  * pfil_wowned() returns a non-zero value if the current thread owns
  158  * an exclusive lock.
  159  */
  160 int
  161 pfil_wowned(struct pfil_head *ph)
  162 {
  163 
  164         return (PFIL_WOWNED(ph));
  165 }
  166 
  167 /*
  168  * pfil_head_register() registers a pfil_head with the packet filter hook
  169  * mechanism.
  170  */
  171 int
  172 pfil_head_register(struct pfil_head *ph)
  173 {
  174         struct pfil_head *lph;
  175 
  176         PFIL_HEADLIST_LOCK();
  177         LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
  178                 if (ph->ph_type == lph->ph_type &&
  179                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  180                         PFIL_HEADLIST_UNLOCK();
  181                         return (EEXIST);
  182                 }
  183         }
  184         PFIL_LOCK_INIT(ph);
  185         ph->ph_nhooks = 0;
  186         TAILQ_INIT(&ph->ph_in);
  187         TAILQ_INIT(&ph->ph_out);
  188         LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
  189         PFIL_HEADLIST_UNLOCK();
  190         return (0);
  191 }
  192 
  193 /*
  194  * pfil_head_unregister() removes a pfil_head from the packet filter hook
  195  * mechanism.  The producer of the hook promises that all outstanding
  196  * invocations of the hook have completed before it unregisters the hook.
  197  */
  198 int
  199 pfil_head_unregister(struct pfil_head *ph)
  200 {
  201         struct packet_filter_hook *pfh, *pfnext;
  202                 
  203         PFIL_HEADLIST_LOCK();
  204         LIST_REMOVE(ph, ph_list);
  205         PFIL_HEADLIST_UNLOCK();
  206         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
  207                 free(pfh, M_IFADDR);
  208         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
  209                 free(pfh, M_IFADDR);
  210         PFIL_LOCK_DESTROY(ph);
  211         return (0);
  212 }
  213 
  214 /*
  215  * pfil_head_get() returns the pfil_head for a given key/dlt.
  216  */
  217 struct pfil_head *
  218 pfil_head_get(int type, u_long val)
  219 {
  220         struct pfil_head *ph;
  221 
  222         PFIL_HEADLIST_LOCK();
  223         LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
  224                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  225                         break;
  226         PFIL_HEADLIST_UNLOCK();
  227         return (ph);
  228 }
  229 
  230 /*
  231  * pfil_add_hook() adds a function to the packet filter hook.  the
  232  * flags are:
  233  *      PFIL_IN         call me on incoming packets
  234  *      PFIL_OUT        call me on outgoing packets
  235  *      PFIL_ALL        call me on all of the above
  236  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  237  */
  238 int
  239 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  240 {
  241         struct packet_filter_hook *pfh1 = NULL;
  242         struct packet_filter_hook *pfh2 = NULL;
  243         int err;
  244 
  245         if (flags & PFIL_IN) {
  246                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  247                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  248                 if (pfh1 == NULL) {
  249                         err = ENOMEM;
  250                         goto error;
  251                 }
  252         }
  253         if (flags & PFIL_OUT) {
  254                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  255                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  256                 if (pfh2 == NULL) {
  257                         err = ENOMEM;
  258                         goto error;
  259                 }
  260         }
  261         PFIL_WLOCK(ph);
  262         if (flags & PFIL_IN) {
  263                 pfh1->pfil_func = func;
  264                 pfh1->pfil_arg = arg;
  265                 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  266                 if (err)
  267                         goto locked_error;
  268                 ph->ph_nhooks++;
  269         }
  270         if (flags & PFIL_OUT) {
  271                 pfh2->pfil_func = func;
  272                 pfh2->pfil_arg = arg;
  273                 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  274                 if (err) {
  275                         if (flags & PFIL_IN)
  276                                 pfil_chain_remove(&ph->ph_in, func, arg);
  277                         goto locked_error;
  278                 }
  279                 ph->ph_nhooks++;
  280         }
  281         PFIL_WUNLOCK(ph);
  282         return (0);
  283 locked_error:
  284         PFIL_WUNLOCK(ph);
  285 error:
  286         if (pfh1 != NULL)
  287                 free(pfh1, M_IFADDR);
  288         if (pfh2 != NULL)
  289                 free(pfh2, M_IFADDR);
  290         return (err);
  291 }
  292 
  293 /*
  294  * pfil_remove_hook removes a specific function from the packet filter hook
  295  * chain.
  296  */
  297 int
  298 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  299 {
  300         int err = 0;
  301 
  302         PFIL_WLOCK(ph);
  303         if (flags & PFIL_IN) {
  304                 err = pfil_chain_remove(&ph->ph_in, func, arg);
  305                 if (err == 0)
  306                         ph->ph_nhooks--;
  307         }
  308         if ((err == 0) && (flags & PFIL_OUT)) {
  309                 err = pfil_chain_remove(&ph->ph_out, func, arg);
  310                 if (err == 0)
  311                         ph->ph_nhooks--;
  312         }
  313         PFIL_WUNLOCK(ph);
  314         return (err);
  315 }
  316 
  317 /*
  318  * Internal: Add a new pfil hook into a hook chain.
  319  */
  320 static int
  321 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
  322 {
  323         struct packet_filter_hook *pfh;
  324 
  325         /*
  326          * First make sure the hook is not already there.
  327          */
  328         TAILQ_FOREACH(pfh, chain, pfil_chain)
  329                 if (pfh->pfil_func == pfh1->pfil_func &&
  330                     pfh->pfil_arg == pfh1->pfil_arg)
  331                         return (EEXIST);
  332 
  333         /*
  334          * Insert the input list in reverse order of the output list so that
  335          * the same path is followed in or out of the kernel.
  336          */
  337         if (flags & PFIL_IN)
  338                 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
  339         else
  340                 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
  341         return (0);
  342 }
  343 
  344 /*
  345  * Internal: Remove a pfil hook from a hook chain.
  346  */
  347 static int
  348 pfil_chain_remove(pfil_chain_t *chain, pfil_func_t func, void *arg)
  349 {
  350         struct packet_filter_hook *pfh;
  351 
  352         TAILQ_FOREACH(pfh, chain, pfil_chain)
  353                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  354                         TAILQ_REMOVE(chain, pfh, pfil_chain);
  355                         free(pfh, M_IFADDR);
  356                         return (0);
  357                 }
  358         return (ENOENT);
  359 }
  360 
  361 /*
  362  * Stuff that must be initialized for every instance (including the first of
  363  * course).
  364  */
  365 static int
  366 vnet_pfil_init(const void *unused)
  367 {
  368 
  369         LIST_INIT(&V_pfil_head_list);
  370         PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
  371         return (0);
  372 }
  373 
  374 /*
  375  * Called for the removal of each instance.
  376  */
  377 static int
  378 vnet_pfil_uninit(const void *unused)
  379 {
  380 
  381         KASSERT(LIST_EMPTY(&V_pfil_head_list),
  382             ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
  383         PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
  384         return (0);
  385 }
  386 
  387 /* Define startup order. */
  388 #define PFIL_SYSINIT_ORDER      SI_SUB_PROTO_BEGIN
  389 #define PFIL_MODEVENT_ORDER     (SI_ORDER_FIRST) /* On boot slot in here. */
  390 #define PFIL_VNET_ORDER         (PFIL_MODEVENT_ORDER + 2) /* Later still. */
  391 
  392 /*
  393  * Starting up.
  394  *
  395  * VNET_SYSINIT is called for each existing vnet and each new vnet.
  396  */
  397 VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
  398     vnet_pfil_init, NULL);
  399  
  400 /*
  401  * Closing up shop.  These are done in REVERSE ORDER.  Not called on reboot.
  402  *
  403  * VNET_SYSUNINIT is called for each exiting vnet as it exits.
  404  */
  405 VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
  406     vnet_pfil_uninit, NULL);
Cache object: 136dd33cc83f5d943af84aa5401eb73f
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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