pfil.c

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    1 /*      $FreeBSD$ */
    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 *, void *, void *);
   59 static int pfil_add_hook_priv(void *, void *, int, struct pfil_head *, bool);
   60 
   61 LIST_HEAD(pfilheadhead, pfil_head);
   62 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
   63 #define V_pfil_head_list        VNET(pfil_head_list)
   64 VNET_DEFINE(struct rmlock, pfil_lock);
   65 
   66 #define PFIL_LOCK_INIT_REAL(l, t)       \
   67         rm_init_flags(l, "PFil " t " rmlock", RM_RECURSE)
   68 #define PFIL_LOCK_DESTROY_REAL(l)       \
   69         rm_destroy(l)
   70 #define PFIL_LOCK_INIT(p)       do {                    \
   71         if ((p)->flags & PFIL_FLAG_PRIVATE_LOCK) {      \
   72                 PFIL_LOCK_INIT_REAL(&(p)->ph_lock, "private");  \
   73                 (p)->ph_plock = &(p)->ph_lock;          \
   74         } else                                          \
   75                 (p)->ph_plock = &V_pfil_lock;           \
   76 } while (0)
   77 #define PFIL_LOCK_DESTROY(p)    do {                    \
   78         if ((p)->flags & PFIL_FLAG_PRIVATE_LOCK)        \
   79                 PFIL_LOCK_DESTROY_REAL((p)->ph_plock);  \
   80 } while (0)
   81 
   82 #define PFIL_TRY_RLOCK(p, t)    rm_try_rlock((p)->ph_plock, (t))
   83 #define PFIL_RLOCK(p, t)        rm_rlock((p)->ph_plock, (t))
   84 #define PFIL_WLOCK(p)           rm_wlock((p)->ph_plock)
   85 #define PFIL_RUNLOCK(p, t)      rm_runlock((p)->ph_plock, (t))
   86 #define PFIL_WUNLOCK(p)         rm_wunlock((p)->ph_plock)
   87 #define PFIL_WOWNED(p)          rm_wowned((p)->ph_plock)
   88 
   89 #define PFIL_HEADLIST_LOCK()    mtx_lock(&pfil_global_lock)
   90 #define PFIL_HEADLIST_UNLOCK()  mtx_unlock(&pfil_global_lock)
   91 
   92 /*
   93  * pfil_run_hooks() runs the specified packet filter hook chain.
   94  */
   95 int
   96 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
   97     int dir, int flags, struct inpcb *inp)
   98 {
   99         struct rm_priotracker rmpt;
  100         struct packet_filter_hook *pfh;
  101         struct mbuf *m = *mp;
  102         int rv = 0;
  103 
  104         PFIL_RLOCK(ph, &rmpt);
  105         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
  106         for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
  107              pfh = TAILQ_NEXT(pfh, pfil_chain)) {
  108                 if (pfh->pfil_func_flags != NULL) {
  109                         rv = (*pfh->pfil_func_flags)(pfh->pfil_arg, &m, ifp,
  110                             dir, flags, inp);
  111                         if (rv != 0 || m == NULL)
  112                                 break;
  113                 }
  114                 if (pfh->pfil_func != NULL) {
  115                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
  116                             inp);
  117                         if (rv != 0 || m == NULL)
  118                                 break;
  119                 }
  120         }
  121         PFIL_RUNLOCK(ph, &rmpt);
  122         *mp = m;
  123         return (rv);
  124 }
  125 
  126 static struct packet_filter_hook *
  127 pfil_chain_get(int dir, struct pfil_head *ph)
  128 {
  129 
  130         if (dir == PFIL_IN)
  131                 return (TAILQ_FIRST(&ph->ph_in));
  132         else if (dir == PFIL_OUT)
  133                 return (TAILQ_FIRST(&ph->ph_out));
  134         else
  135                 return (NULL);
  136 }
  137 
  138 /*
  139  * pfil_try_rlock() acquires rm reader lock for specified head
  140  * if this is immediately possible.
  141  */
  142 int
  143 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  144 {
  145 
  146         return (PFIL_TRY_RLOCK(ph, tracker));
  147 }
  148 
  149 /*
  150  * pfil_rlock() acquires rm reader lock for specified head.
  151  */
  152 void
  153 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  154 {
  155 
  156         PFIL_RLOCK(ph, tracker);
  157 }
  158 
  159 /*
  160  * pfil_runlock() releases reader lock for specified head.
  161  */
  162 void
  163 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
  164 {
  165 
  166         PFIL_RUNLOCK(ph, tracker);
  167 }
  168 
  169 /*
  170  * pfil_wlock() acquires writer lock for specified head.
  171  */
  172 void
  173 pfil_wlock(struct pfil_head *ph)
  174 {
  175 
  176         PFIL_WLOCK(ph);
  177 }
  178 
  179 /*
  180  * pfil_wunlock() releases writer lock for specified head.
  181  */
  182 void
  183 pfil_wunlock(struct pfil_head *ph)
  184 {
  185 
  186         PFIL_WUNLOCK(ph);
  187 }
  188 
  189 /*
  190  * pfil_wowned() returns a non-zero value if the current thread owns
  191  * an exclusive lock.
  192  */
  193 int
  194 pfil_wowned(struct pfil_head *ph)
  195 {
  196 
  197         return (PFIL_WOWNED(ph));
  198 }
  199 
  200 /*
  201  * pfil_head_register() registers a pfil_head with the packet filter hook
  202  * mechanism.
  203  */
  204 int
  205 pfil_head_register(struct pfil_head *ph)
  206 {
  207         struct pfil_head *lph;
  208 
  209         PFIL_HEADLIST_LOCK();
  210         LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
  211                 if (ph->ph_type == lph->ph_type &&
  212                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
  213                         PFIL_HEADLIST_UNLOCK();
  214                         return (EEXIST);
  215                 }
  216         }
  217         PFIL_LOCK_INIT(ph);
  218         ph->ph_nhooks = 0;
  219         TAILQ_INIT(&ph->ph_in);
  220         TAILQ_INIT(&ph->ph_out);
  221         LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
  222         PFIL_HEADLIST_UNLOCK();
  223         return (0);
  224 }
  225 
  226 /*
  227  * pfil_head_unregister() removes a pfil_head from the packet filter hook
  228  * mechanism.  The producer of the hook promises that all outstanding
  229  * invocations of the hook have completed before it unregisters the hook.
  230  */
  231 int
  232 pfil_head_unregister(struct pfil_head *ph)
  233 {
  234         struct packet_filter_hook *pfh, *pfnext;
  235                 
  236         PFIL_HEADLIST_LOCK();
  237         LIST_REMOVE(ph, ph_list);
  238         PFIL_HEADLIST_UNLOCK();
  239         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
  240                 free(pfh, M_IFADDR);
  241         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
  242                 free(pfh, M_IFADDR);
  243         PFIL_LOCK_DESTROY(ph);
  244         return (0);
  245 }
  246 
  247 /*
  248  * pfil_head_get() returns the pfil_head for a given key/dlt.
  249  */
  250 struct pfil_head *
  251 pfil_head_get(int type, u_long val)
  252 {
  253         struct pfil_head *ph;
  254 
  255         PFIL_HEADLIST_LOCK();
  256         LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
  257                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
  258                         break;
  259         PFIL_HEADLIST_UNLOCK();
  260         return (ph);
  261 }
  262 
  263 /*
  264  * pfil_add_hook_flags() adds a function to the packet filter hook.  the
  265  * flags are:
  266  *      PFIL_IN         call me on incoming packets
  267  *      PFIL_OUT        call me on outgoing packets
  268  *      PFIL_ALL        call me on all of the above
  269  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  270  */
  271 int
  272 pfil_add_hook_flags(pfil_func_flags_t func, void *arg, int flags,
  273     struct pfil_head *ph)
  274 {
  275         return (pfil_add_hook_priv(func, arg, flags, ph, true));
  276 }
  277 
  278 /*
  279  * pfil_add_hook() adds a function to the packet filter hook.  the
  280  * flags are:
  281  *      PFIL_IN         call me on incoming packets
  282  *      PFIL_OUT        call me on outgoing packets
  283  *      PFIL_ALL        call me on all of the above
  284  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
  285  */
  286 int
  287 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  288 {
  289         return (pfil_add_hook_priv(func, arg, flags, ph, false));
  290 }
  291 
  292 static int
  293 pfil_add_hook_priv(void *func, void *arg, int flags,
  294     struct pfil_head *ph, bool hasflags)
  295 {
  296         struct packet_filter_hook *pfh1 = NULL;
  297         struct packet_filter_hook *pfh2 = NULL;
  298         int err;
  299 
  300         if (flags & PFIL_IN) {
  301                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 
  302                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  303                 if (pfh1 == NULL) {
  304                         err = ENOMEM;
  305                         goto error;
  306                 }
  307         }
  308         if (flags & PFIL_OUT) {
  309                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
  310                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
  311                 if (pfh2 == NULL) {
  312                         err = ENOMEM;
  313                         goto error;
  314                 }
  315         }
  316         PFIL_WLOCK(ph);
  317         if (flags & PFIL_IN) {
  318                 pfh1->pfil_func_flags = hasflags ? func : NULL;
  319                 pfh1->pfil_func = hasflags ? NULL : func;
  320                 pfh1->pfil_arg = arg;
  321                 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
  322                 if (err)
  323                         goto locked_error;
  324                 ph->ph_nhooks++;
  325         }
  326         if (flags & PFIL_OUT) {
  327                 pfh2->pfil_func_flags = hasflags ? func : NULL;
  328                 pfh2->pfil_func = hasflags ? NULL : func;
  329                 pfh2->pfil_arg = arg;
  330                 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
  331                 if (err) {
  332                         if (flags & PFIL_IN)
  333                                 pfil_chain_remove(&ph->ph_in, func, arg);
  334                         goto locked_error;
  335                 }
  336                 ph->ph_nhooks++;
  337         }
  338         PFIL_WUNLOCK(ph);
  339         return (0);
  340 locked_error:
  341         PFIL_WUNLOCK(ph);
  342 error:
  343         if (pfh1 != NULL)
  344                 free(pfh1, M_IFADDR);
  345         if (pfh2 != NULL)
  346                 free(pfh2, M_IFADDR);
  347         return (err);
  348 }
  349 
  350 /*
  351  * pfil_remove_hook_flags removes a specific function from the packet filter hook
  352  * chain.
  353  */
  354 int
  355 pfil_remove_hook_flags(pfil_func_flags_t func, void *arg, int flags,
  356     struct pfil_head *ph)
  357 {
  358         return (pfil_remove_hook((pfil_func_t)func, arg, flags, ph));
  359 }
  360 
  361 /*
  362  * pfil_remove_hook removes a specific function from the packet filter hook
  363  * chain.
  364  */
  365 int
  366 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
  367 {
  368         int err = 0;
  369 
  370         PFIL_WLOCK(ph);
  371         if (flags & PFIL_IN) {
  372                 err = pfil_chain_remove(&ph->ph_in, func, arg);
  373                 if (err == 0)
  374                         ph->ph_nhooks--;
  375         }
  376         if ((err == 0) && (flags & PFIL_OUT)) {
  377                 err = pfil_chain_remove(&ph->ph_out, func, arg);
  378                 if (err == 0)
  379                         ph->ph_nhooks--;
  380         }
  381         PFIL_WUNLOCK(ph);
  382         return (err);
  383 }
  384 
  385 /*
  386  * Internal: Add a new pfil hook into a hook chain.
  387  */
  388 static int
  389 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
  390 {
  391         struct packet_filter_hook *pfh;
  392 
  393         /*
  394          * First make sure the hook is not already there.
  395          */
  396         TAILQ_FOREACH(pfh, chain, pfil_chain)
  397                 if (((pfh->pfil_func != NULL && pfh->pfil_func == pfh1->pfil_func) ||
  398                     (pfh->pfil_func_flags != NULL &&
  399                      pfh->pfil_func_flags == pfh1->pfil_func_flags)) &&
  400                     pfh->pfil_arg == pfh1->pfil_arg)
  401                         return (EEXIST);
  402 
  403         /*
  404          * Insert the input list in reverse order of the output list so that
  405          * the same path is followed in or out of the kernel.
  406          */
  407         if (flags & PFIL_IN)
  408                 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
  409         else
  410                 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
  411         return (0);
  412 }
  413 
  414 /*
  415  * Internal: Remove a pfil hook from a hook chain.
  416  */
  417 static int
  418 pfil_chain_remove(pfil_chain_t *chain, void *func, void *arg)
  419 {
  420         struct packet_filter_hook *pfh;
  421 
  422         TAILQ_FOREACH(pfh, chain, pfil_chain)
  423                 if ((pfh->pfil_func == func || pfh->pfil_func_flags == func) &&
  424                     pfh->pfil_arg == arg) {
  425                         TAILQ_REMOVE(chain, pfh, pfil_chain);
  426                         free(pfh, M_IFADDR);
  427                         return (0);
  428                 }
  429         return (ENOENT);
  430 }
  431 
  432 /*
  433  * Stuff that must be initialized for every instance (including the first of
  434  * course).
  435  */
  436 static void
  437 vnet_pfil_init(const void *unused __unused)
  438 {
  439 
  440         LIST_INIT(&V_pfil_head_list);
  441         PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
  442 }
  443 
  444 /*
  445  * Called for the removal of each instance.
  446  */
  447 static void
  448 vnet_pfil_uninit(const void *unused __unused)
  449 {
  450 
  451         KASSERT(LIST_EMPTY(&V_pfil_head_list),
  452             ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
  453         PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
  454 }
  455 
  456 /*
  457  * Starting up.
  458  *
  459  * VNET_SYSINIT is called for each existing vnet and each new vnet.
  460  * Make sure the pfil bits are first before any possible subsystem which
  461  * might piggyback on the SI_SUB_PROTO_PFIL.
  462  */
  463 VNET_SYSINIT(vnet_pfil_init, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST,
  464     vnet_pfil_init, NULL);
  465  
  466 /*
  467  * Closing up shop.  These are done in REVERSE ORDER.  Not called on reboot.
  468  *
  469  * VNET_SYSUNINIT is called for each exiting vnet as it exits.
  470  */
  471 VNET_SYSUNINIT(vnet_pfil_uninit, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST,
  472     vnet_pfil_uninit, NULL);
Cache object: ab50b06f599ec03949158acc8121ba4a
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FreeBSD/Linux Kernel Cross Reference sys/net/pfil.c

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