sys/net/pfil.c

   1 /*      $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $  */
   2 /* $DragonFly: src/sys/net/pfil.c,v 1.5 2006/10/19 18:44:00 swildner 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/errno.h>
  34 #include <sys/malloc.h>
  35 #include <sys/socket.h>
  36 #include <sys/socketvar.h>
  37 #include <sys/systm.h>
  38 #include <sys/proc.h>
  39 #include <sys/queue.h>
  40
  41 #include <net/if.h>
  42 #include <net/pfil.h>
  43
  44 static int pfil_list_add(struct pfil_head *,
  45     int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int);
  46
  47 static int pfil_list_remove(struct pfil_head *,
  48     int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int);
  49
  50 LIST_HEAD(, pfil_head) pfil_head_list =
  51     LIST_HEAD_INITIALIZER(&pfil_head_list);
  52
  53 /*
  54  * pfil_run_hooks() runs the specified packet filter hooks.
  55  */
  56 int
  57 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
  58     int dir)
  59 {
  60         struct packet_filter_hook *pfh;
  61         struct mbuf *m = *mp;
  62         int rv = 0;
  63
  64         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
  65              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  66                 if (pfh->pfil_func != NULL) {
  67                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir);
  68                         if (rv != 0 || m == NULL)
  69                                 break;
  70                 }
  71         }
  72
  73         *mp = m;
  74         return (rv);
  75 }
  76
  77 /*
  78  * pfil_head_register() registers a pfil_head with the packet filter
  79  * hook mechanism.
  80  */
  81 int
  82 pfil_head_register(struct pfil_head *ph)
  83 {
  84         struct pfil_head *lph;
  85
  86         for (lph = LIST_FIRST(&pfil_head_list); lph != NULL;
  87              lph = LIST_NEXT(lph, ph_list)) {
  88                 if (ph->ph_type == lph->ph_type &&
  89                     ph->ph_un.phu_val == lph->ph_un.phu_val)
  90                         return EEXIST;
  91         }
  92
  93         TAILQ_INIT(&ph->ph_in);
  94         TAILQ_INIT(&ph->ph_out);
  95         ph->ph_hashooks = 0;
  96
  97         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
  98
  99         return (0);
 100 }
 101
 102 /*
 103  * pfil_head_unregister() removes a pfil_head from the packet filter
 104  * hook mechanism.
 105  */
 106 int
 107 pfil_head_unregister(struct pfil_head *pfh)
 108 {
 109
 110         LIST_REMOVE(pfh, ph_list);
 111         return (0);
 112 }
 113
 114 /*
 115  * pfil_head_get() returns the pfil_head for a given key/dlt.
 116  */
 117 struct pfil_head *
 118 pfil_head_get(int type, u_long val)
 119 {
 120         struct pfil_head *ph;
 121
 122         for (ph = LIST_FIRST(&pfil_head_list); ph != NULL;
 123              ph = LIST_NEXT(ph, ph_list)) {
 124                 if (ph->ph_type == type &&
 125                     ph->ph_un.phu_val == val)
 126                         break;
 127         }
 128
 129         return (ph);
 130 }
 131
 132 /*
 133  * pfil_add_hook() adds a function to the packet filter hook.  the
 134  * flags are:
 135  *      PFIL_IN         call me on incoming packets
 136  *      PFIL_OUT        call me on outgoing packets
 137  *      PFIL_ALL        call me on all of the above
 138  *      PFIL_WAITOK     OK to call kmalloc with M_WAITOK.
 139  */
 140 int
 141 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
 142     void *arg, int flags, struct pfil_head *ph)
 143 {
 144         int err = 0;
 145
 146         if (flags & PFIL_IN) {
 147                 err = pfil_list_add(ph, func, arg, flags & ~PFIL_OUT);
 148                 if (err)
 149                         return err;
 150         }
 151         if (flags & PFIL_OUT) {
 152                 err = pfil_list_add(ph, func, arg, flags & ~PFIL_IN);
 153                 if (err) {
 154                         if (flags & PFIL_IN)
 155                                 pfil_list_remove(ph, func, arg, PFIL_IN);
 156                         return err;
 157                 }
 158         }
 159         return 0;
 160 }
 161
 162 static int
 163 pfil_list_add(struct pfil_head *ph,
 164     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
 165     int flags)
 166 {
 167         struct packet_filter_hook *pfh;
 168         pfil_list_t *list;
 169
 170         list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out;
 171
 172         /*
 173          * First make sure the hook is not already there.
 174          */
 175         for (pfh = TAILQ_FIRST(list); pfh != NULL;
 176              pfh = TAILQ_NEXT(pfh, pfil_link)) {
 177                 if (pfh->pfil_func == func &&
 178                     pfh->pfil_arg == arg)
 179                         return EEXIST;
 180         }
 181
 182         pfh = (struct packet_filter_hook *)kmalloc(sizeof(*pfh), M_IFADDR,
 183             (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
 184         if (pfh == NULL)
 185                 return ENOMEM;
 186
 187         pfh->pfil_func = func;
 188         pfh->pfil_arg  = arg;
 189
 190         /*
 191          * insert the input list in reverse order of the output list
 192          * so that the same path is followed in or out of the kernel.
 193          */
 194         if (flags & PFIL_IN)
 195                 TAILQ_INSERT_HEAD(list, pfh, pfil_link);
 196         else
 197                 TAILQ_INSERT_TAIL(list, pfh, pfil_link);
 198         ph->ph_hashooks = 1;
 199         return (0);
 200 }
 201
 202 /*
 203  * pfil_remove_hook removes a specific function from the packet filter
 204  * hook list.
 205  */
 206 int
 207 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
 208     void *arg, int flags, struct pfil_head *ph)
 209 {
 210         int err = 0;
 211
 212         if (flags & PFIL_IN)
 213                 err = pfil_list_remove(ph, func, arg, PFIL_IN);
 214         if ((err == 0) && (flags & PFIL_OUT))
 215                 err = pfil_list_remove(ph, func, arg, PFIL_OUT);
 216         return err;
 217 }
 218
 219 /*
 220  * pfil_list_remove is an internal function that takes a function off the
 221  * specified list.  Clear ph_hashooks if no functions remain on any list.
 222  */
 223 static int
 224 pfil_list_remove(struct pfil_head *ph,
 225     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
 226     int flags)
 227 {
 228         struct packet_filter_hook *pfh;
 229         pfil_list_t *list;
 230
 231         list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out;
 232
 233         for (pfh = TAILQ_FIRST(list); pfh != NULL;
 234              pfh = TAILQ_NEXT(pfh, pfil_link)) {
 235                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
 236                         TAILQ_REMOVE(list, pfh, pfil_link);
 237                         kfree(pfh, M_IFADDR);
 238                         if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
 239                                 ph->ph_hashooks = 0;
 240                         return 0;
 241                 }
 242         }
 243         return ENOENT;
 244 }