sys/net/pfil.c

   1 /*      $NetBSD: pfil.c,v 1.26 2008/06/23 00:56:08 dyoung Exp $ */
   2
   3 /*
   4  * Copyright (c) 1996 Matthew R. Green
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __KERNEL_RCSID(0, "$NetBSD: pfil.c,v 1.26 2008/06/23 00:56:08 dyoung Exp $");
  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(pfil_list_t *,
  45     int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int);
  46
  47 static int pfil_list_remove(pfil_list_t *,
  48     int (*)(void *, struct mbuf **, struct ifnet *, int), void *);
  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 = NULL;
  62         int rv = 0;
  63
  64         if ((dir & PFIL_ALL) && mp)
  65                 m = *mp;
  66         for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
  67              pfh = TAILQ_NEXT(pfh, pfil_link)) {
  68                 if (pfh->pfil_func != NULL) {
  69                         if (pfh->pfil_flags & PFIL_ALL) {
  70                                 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp,
  71                                     dir);
  72                                 if (rv != 0 || m == NULL)
  73                                         break;
  74                         } else {
  75                                 rv = (*pfh->pfil_func)(pfh->pfil_arg, mp, ifp,
  76                                     dir);
  77                                 if (rv != 0)
  78                                         break;
  79                         }
  80                 }
  81         }
  82
  83         if ((dir & PFIL_ALL) && mp)
  84                 *mp = m;
  85         return (rv);
  86 }
  87
  88 /*
  89  * pfil_head_register() registers a pfil_head with the packet filter
  90  * hook mechanism.
  91  */
  92 int
  93 pfil_head_register(struct pfil_head *ph)
  94 {
  95         struct pfil_head *lph;
  96
  97         LIST_FOREACH(lph, &pfil_head_list, ph_list) {
  98                 if (ph->ph_type == lph->ph_type &&
  99                     ph->ph_un.phu_val == lph->ph_un.phu_val)
 100                         return EEXIST;
 101         }
 102
 103         TAILQ_INIT(&ph->ph_in);
 104         TAILQ_INIT(&ph->ph_out);
 105         TAILQ_INIT(&ph->ph_ifaddr);
 106         TAILQ_INIT(&ph->ph_ifnetevent);
 107
 108         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
 109
 110         return (0);
 111 }
 112
 113 /*
 114  * pfil_head_unregister() removes a pfil_head from the packet filter
 115  * hook mechanism.
 116  */
 117 int
 118 pfil_head_unregister(struct pfil_head *pfh)
 119 {
 120
 121         LIST_REMOVE(pfh, ph_list);
 122         return (0);
 123 }
 124
 125 /*
 126  * pfil_head_get() returns the pfil_head for a given key/dlt.
 127  */
 128 struct pfil_head *
 129 pfil_head_get(int type, u_long val)
 130 {
 131         struct pfil_head *ph;
 132
 133         LIST_FOREACH(ph, &pfil_head_list, ph_list) {
 134                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
 135                         break;
 136         }
 137
 138         return (ph);
 139 }
 140
 141 /*
 142  * pfil_add_hook() adds a function to the packet filter hook.  the
 143  * flags are:
 144  *      PFIL_IN         call me on incoming packets
 145  *      PFIL_OUT        call me on outgoing packets
 146  *      PFIL_ALL        call me on all of the above
 147  *      PFIL_IFADDR     call me on interface reconfig (mbuf ** is ioctl #)
 148  *      PFIL_IFNET      call me on interface attach/detach
 149  *                      (mbuf ** is PFIL_IFNET_*)
 150  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
 151  */
 152 int
 153 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
 154     void *arg, int flags, struct pfil_head *ph)
 155 {
 156         int err = 0;
 157
 158         if (flags & PFIL_IN) {
 159                 err = pfil_list_add(&ph->ph_in, func, arg, flags & ~PFIL_OUT);
 160                 if (err)
 161                         return err;
 162         }
 163         if (flags & PFIL_OUT) {
 164                 err = pfil_list_add(&ph->ph_out, func, arg, flags & ~PFIL_IN);
 165                 if (err) {
 166                         if (flags & PFIL_IN)
 167                                 pfil_list_remove(&ph->ph_in, func, arg);
 168                         return err;
 169                 }
 170         }
 171         if (flags & PFIL_IFADDR) {
 172                 err = pfil_list_add(&ph->ph_ifaddr, func, arg, flags);
 173                 if (err) {
 174                         if (flags & PFIL_IN)
 175                                 pfil_list_remove(&ph->ph_in, func, arg);
 176                         if (flags & PFIL_OUT)
 177                                 pfil_list_remove(&ph->ph_out, func, arg);
 178                         return err;
 179                 }
 180         }
 181         if (flags & PFIL_IFNET) {
 182                 err = pfil_list_add(&ph->ph_ifnetevent, func, arg, flags);
 183                 if (err) {
 184                         if (flags & PFIL_IN)
 185                                 pfil_list_remove(&ph->ph_in, func, arg);
 186                         if (flags & PFIL_OUT)
 187                                 pfil_list_remove(&ph->ph_out, func, arg);
 188                         if (flags & PFIL_IFADDR)
 189                                 pfil_list_remove(&ph->ph_ifaddr, func, arg);
 190                         return err;
 191                 }
 192         }
 193         return 0;
 194 }
 195
 196 static int
 197 pfil_list_add(pfil_list_t *list,
 198     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
 199     int flags)
 200 {
 201         struct packet_filter_hook *pfh;
 202
 203         /*
 204          * First make sure the hook is not already there.
 205          */
 206         TAILQ_FOREACH(pfh, list, pfil_link) {
 207                 if (pfh->pfil_func == func && pfh->pfil_arg == arg)
 208                         return EEXIST;
 209         }
 210
 211         pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
 212             (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
 213         if (pfh == NULL)
 214                 return ENOMEM;
 215
 216         pfh->pfil_func = func;
 217         pfh->pfil_arg  = arg;
 218         pfh->pfil_flags = flags;
 219
 220         /*
 221          * insert the input list in reverse order of the output list
 222          * so that the same path is followed in or out of the kernel.
 223          */
 224         if (flags & PFIL_IN)
 225                 TAILQ_INSERT_HEAD(list, pfh, pfil_link);
 226         else
 227                 TAILQ_INSERT_TAIL(list, pfh, pfil_link);
 228
 229         return 0;
 230 }
 231
 232 /*
 233  * pfil_remove_hook removes a specific function from the packet filter
 234  * hook list.
 235  */
 236 int
 237 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
 238     void *arg, int flags, struct pfil_head *ph)
 239 {
 240         int err = 0;
 241
 242         if (flags & PFIL_IN)
 243                 err = pfil_list_remove(&ph->ph_in, func, arg);
 244         if ((err == 0) && (flags & PFIL_OUT))
 245                 err = pfil_list_remove(&ph->ph_out, func, arg);
 246         if ((err == 0) && (flags & PFIL_IFADDR))
 247                 err = pfil_list_remove(&ph->ph_ifaddr, func, arg);
 248         if ((err == 0) && (flags & PFIL_IFNET))
 249                 err = pfil_list_remove(&ph->ph_ifnetevent, func, arg);
 250         return err;
 251 }
 252
 253 /*
 254  * pfil_list_remove is an internal function that takes a function off the
 255  * specified list.
 256  */
 257 static int
 258 pfil_list_remove(pfil_list_t *list,
 259     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
 260 {
 261         struct packet_filter_hook *pfh;
 262
 263         TAILQ_FOREACH(pfh, list, pfil_link) {
 264                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
 265                         TAILQ_REMOVE(list, pfh, pfil_link);
 266                         free(pfh, M_IFADDR);
 267                         return 0;
 268                 }
 269         }
 270         return ENOENT;
 271 }