pfil.c

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    1 /*      $FreeBSD: releng/11.1/sys/net/pfil.c 317042 2017-04-17 09:34:09Z ae $ */
    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 
   65 #define PFIL_LOCK_INIT_REAL(l, t)       \
   66         rm_init_flags(l, "PFil " t " rmlock", RM_RECURSE)
   67 #define PFIL_LOCK_DESTROY_REAL(l)       \
   68         rm_destroy(l)
   69 #define PFIL_LOCK_INIT(p)       do {                    \
   70         if ((p)->flags & PFIL_FLAG_PRIVATE_LOCK) {      \
   71                 PFIL_LOCK_INIT_REAL(&(p)->ph_lock, "private");  \
   72                 (p)->ph_plock = &(p)->ph_lock;          \
   73         } else                                          \
   74                 (p)->ph_plock = &V_pfil_lock;           \
   75 } while (0)
   76 #define PFIL_LOCK_DESTROY(p)    do {                    \
   77         if ((p)->flags & PFIL_FLAG_PRIVATE_LOCK)        \
   78                 PFIL_LOCK_DESTROY_REAL((p)->ph_plock);  \
   79 } while (0)
   80 
   81 #define PFIL_TRY_RLOCK(p, t)    rm_try_rlock((p)->ph_plock, (t))
   82 #define PFIL_RLOCK(p, t)        rm_rlock((p)->ph_plock, (t))
   83 #define PFIL_WLOCK(p)           rm_wlock((p)->ph_plock)
   84 #define PFIL_RUNLOCK(p, t)      rm_runlock((p)->ph_plock, (t))
   85 #define PFIL_WUNLOCK(p)         rm_wunlock((p)->ph_plock)
   86 #define PFIL_WOWNED(p)          rm_wowned((p)->ph_plock)
   87 
   88 #define PFIL_HEADLIST_LOCK()    mtx_lock(&pfil_global_lock)
   89 #define PFIL_HEADLIST_UNLOCK()  mtx_unlock(&pfil_global_lock)
   90 
   91 /*
   92  * pfil_run_hooks() runs the specified packet filter hook chain.
   93  */
   94 int
   95 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   96     int dir, struct inpcb *inp)
   97 {
   98         struct rm_priotracker rmpt;
   99         struct packet_filter_hook *pfh;
  100         struct mbuf *m = *mp;
  101         int rv = 0;
  102 
  103         PFIL_RLOCK(ph, &rmpt);
  104         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
  105         for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
  106              pfh = TAILQ_NEXT(pfh, pfil_chain)) {
  107                 if (pfh->pfil_func != NULL) {
  108                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
  109                             inp);
  110                         if (rv != 0 || m == NULL)
  111                                 break;
  112                 }
  113         }
  114         PFIL_RUNLOCK(ph, &rmpt);
  115         *mp = m;
  116         return (rv);
  117 }
  118 
  119 static struct packet_filter_hook *
  120 pfil_chain_get(int dir, struct pfil_head *ph)
  121 {
  122 
  123         if (dir == PFIL_IN)
  124                 return (TAILQ_FIRST(&ph->ph_in));
  125         else if (dir == PFIL_OUT)
  126                 return (TAILQ_FIRST(&ph->ph_out));
  127         else
  128                 return (NULL);
  129 }
  130 
  131 /*
  132  * pfil_try_rlock() acquires rm reader lock for specified head
  133  * if this is immediately possible.
  134  */
  135 int
  136 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  137 {
  138 
  139         return (PFIL_TRY_RLOCK(ph, tracker));
  140 }
  141 
  142 /*
  143  * pfil_rlock() acquires rm reader lock for specified head.
  144  */
  145 void
  146 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  147 {
  148 
  149         PFIL_RLOCK(ph, tracker);
  150 }
  151 
  152 /*
  153  * pfil_runlock() releases reader lock for specified head.
  154  */
  155 void
  156 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  157 {
  158 
  159         PFIL_RUNLOCK(ph, tracker);
  160 }
  161 
  162 /*
  163  * pfil_wlock() acquires writer lock for specified head.
  164  */
  165 void
  166 pfil_wlock(struct pfil_head *ph)
  167 {
  168 
  169         PFIL_WLOCK(ph);
  170 }
  171 
  172 /*
  173  * pfil_wunlock() releases writer lock for specified head.
  174  */
  175 void
  176 pfil_wunlock(struct pfil_head *ph)
  177 {
  178 
  179         PFIL_WUNLOCK(ph);
  180 }
  181 
  182 /*
  183  * pfil_wowned() returns a non-zero value if the current thread owns
  184  * an exclusive lock.
  185  */
  186 int
  187 pfil_wowned(struct pfil_head *ph)
  188 {
  189 
  190         return (PFIL_WOWNED(ph));
  191 }
  192 
  193 /*
  194  * pfil_head_register() registers a pfil_head with the packet filter hook
  195  * mechanism.
  196  */
  197 int
  198 pfil_head_register(struct pfil_head *ph)
  199 {
  200         struct pfil_head *lph;
  201 
  202         PFIL_HEADLIST_LOCK();
  203         LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
  204                 if (ph->ph_type == lph->ph_type &&
  205                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  206                         PFIL_HEADLIST_UNLOCK();
  207                         return (EEXIST);
  208                 }
  209         }
  210         PFIL_LOCK_INIT(ph);
  211         ph->ph_nhooks = 0;
  212         TAILQ_INIT(&ph->ph_in);
  213         TAILQ_INIT(&ph->ph_out);
  214         LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
  215         PFIL_HEADLIST_UNLOCK();
  216         return (0);
  217 }
  218 
  219 /*
  220  * pfil_head_unregister() removes a pfil_head from the packet filter hook
  221  * mechanism.  The producer of the hook promises that all outstanding
  222  * invocations of the hook have completed before it unregisters the hook.
  223  */
  224 int
  225 pfil_head_unregister(struct pfil_head *ph)
  226 {
  227         struct packet_filter_hook *pfh, *pfnext;
  228                 
  229         PFIL_HEADLIST_LOCK();
  230         LIST_REMOVE(ph, ph_list);
  231         PFIL_HEADLIST_UNLOCK();
  232         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
  233                 free(pfh, M_IFADDR);
  234         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
  235                 free(pfh, M_IFADDR);
  236         PFIL_LOCK_DESTROY(ph);
  237         return (0);
  238 }
  239 
  240 /*
  241  * pfil_head_get() returns the pfil_head for a given key/dlt.
  242  */
  243 struct pfil_head *
  244 pfil_head_get(int type, u_long val)
  245 {
  246         struct pfil_head *ph;
  247 
  248         PFIL_HEADLIST_LOCK();
  249         LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
  250                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  251                         break;
  252         PFIL_HEADLIST_UNLOCK();
  253         return (ph);
  254 }
  255 
  256 /*
  257  * pfil_add_hook() adds a function to the packet filter hook.  the
  258  * flags are:
  259  *      PFIL_IN         call me on incoming packets
  260  *      PFIL_OUT        call me on outgoing packets
  261  *      PFIL_ALL        call me on all of the above
  262  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  263  */
  264 int
  265 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  266 {
  267         struct packet_filter_hook *pfh1 = NULL;
  268         struct packet_filter_hook *pfh2 = NULL;
  269         int err;
  270 
  271         if (flags & PFIL_IN) {
  272                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  273                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  274                 if (pfh1 == NULL) {
  275                         err = ENOMEM;
  276                         goto error;
  277                 }
  278         }
  279         if (flags & PFIL_OUT) {
  280                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  281                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  282                 if (pfh2 == NULL) {
  283                         err = ENOMEM;
  284                         goto error;
  285                 }
  286         }
  287         PFIL_WLOCK(ph);
  288         if (flags & PFIL_IN) {
  289                 pfh1->pfil_func = func;
  290                 pfh1->pfil_arg = arg;
  291                 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  292                 if (err)
  293                         goto locked_error;
  294                 ph->ph_nhooks++;
  295         }
  296         if (flags & PFIL_OUT) {
  297                 pfh2->pfil_func = func;
  298                 pfh2->pfil_arg = arg;
  299                 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  300                 if (err) {
  301                         if (flags & PFIL_IN)
  302                                 pfil_chain_remove(&ph->ph_in, func, arg);
  303                         goto locked_error;
  304                 }
  305                 ph->ph_nhooks++;
  306         }
  307         PFIL_WUNLOCK(ph);
  308         return (0);
  309 locked_error:
  310         PFIL_WUNLOCK(ph);
  311 error:
  312         if (pfh1 != NULL)
  313                 free(pfh1, M_IFADDR);
  314         if (pfh2 != NULL)
  315                 free(pfh2, M_IFADDR);
  316         return (err);
  317 }
  318 
  319 /*
  320  * pfil_remove_hook removes a specific function from the packet filter hook
  321  * chain.
  322  */
  323 int
  324 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  325 {
  326         int err = 0;
  327 
  328         PFIL_WLOCK(ph);
  329         if (flags & PFIL_IN) {
  330                 err = pfil_chain_remove(&ph->ph_in, func, arg);
  331                 if (err == 0)
  332                         ph->ph_nhooks--;
  333         }
  334         if ((err == 0) && (flags & PFIL_OUT)) {
  335                 err = pfil_chain_remove(&ph->ph_out, func, arg);
  336                 if (err == 0)
  337                         ph->ph_nhooks--;
  338         }
  339         PFIL_WUNLOCK(ph);
  340         return (err);
  341 }
  342 
  343 /*
  344  * Internal: Add a new pfil hook into a hook chain.
  345  */
  346 static int
  347 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
  348 {
  349         struct packet_filter_hook *pfh;
  350 
  351         /*
  352          * First make sure the hook is not already there.
  353          */
  354         TAILQ_FOREACH(pfh, chain, pfil_chain)
  355                 if (pfh->pfil_func == pfh1->pfil_func &&
  356                     pfh->pfil_arg == pfh1->pfil_arg)
  357                         return (EEXIST);
  358 
  359         /*
  360          * Insert the input list in reverse order of the output list so that
  361          * the same path is followed in or out of the kernel.
  362          */
  363         if (flags & PFIL_IN)
  364                 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
  365         else
  366                 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
  367         return (0);
  368 }
  369 
  370 /*
  371  * Internal: Remove a pfil hook from a hook chain.
  372  */
  373 static int
  374 pfil_chain_remove(pfil_chain_t *chain, pfil_func_t func, void *arg)
  375 {
  376         struct packet_filter_hook *pfh;
  377 
  378         TAILQ_FOREACH(pfh, chain, pfil_chain)
  379                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
  380                         TAILQ_REMOVE(chain, pfh, pfil_chain);
  381                         free(pfh, M_IFADDR);
  382                         return (0);
  383                 }
  384         return (ENOENT);
  385 }
  386 
  387 /*
  388  * Stuff that must be initialized for every instance (including the first of
  389  * course).
  390  */
  391 static void
  392 vnet_pfil_init(const void *unused __unused)
  393 {
  394 
  395         LIST_INIT(&V_pfil_head_list);
  396         PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
  397 }
  398 
  399 /*
  400  * Called for the removal of each instance.
  401  */
  402 static void
  403 vnet_pfil_uninit(const void *unused __unused)
  404 {
  405 
  406         KASSERT(LIST_EMPTY(&V_pfil_head_list),
  407             ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
  408         PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
  409 }
  410 
  411 /*
  412  * Starting up.
  413  *
  414  * VNET_SYSINIT is called for each existing vnet and each new vnet.
  415  * Make sure the pfil bits are first before any possible subsystem which
  416  * might piggyback on the SI_SUB_PROTO_PFIL.
  417  */
  418 VNET_SYSINIT(vnet_pfil_init, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST,
  419     vnet_pfil_init, NULL);
  420  
  421 /*
  422  * Closing up shop.  These are done in REVERSE ORDER.  Not called on reboot.
  423  *
  424  * VNET_SYSUNINIT is called for each exiting vnet as it exits.
  425  */
  426 VNET_SYSUNINIT(vnet_pfil_uninit, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST,
  427     vnet_pfil_uninit, NULL);
Cache object: 5cf3e31d50b8c1440c55f0b3c57c498e
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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