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 1.14 2008/09/20 06:08:13 sephe 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 #include <sys/sysctl.h>
  41
  42 #include <net/if.h>
  43 #include <net/pfil.h>
  44 #include <net/netmsg2.h>
  45 #include <net/netisr2.h>
  46 #include <sys/mplock2.h>
  47
  48 #define PFIL_CFGPORT    netisr_cpuport(0)
  49
  50 #define PFIL_GETMPLOCK(pfh) \
  51 do { \
  52         if (((pfh)->pfil_flags & PFIL_MPSAFE) == 0) \
  53                 get_mplock(); \
  54 } while (0)
  55
  56 #define PFIL_RELMPLOCK(pfh) \
  57 do { \
  58         if (((pfh)->pfil_flags & PFIL_MPSAFE) == 0) \
  59                 rel_mplock(); \
  60 } while (0)
  61
  62 /*
  63  * The packet filter hooks are designed for anything to call them to
  64  * possibly intercept the packet.
  65  */
  66 struct packet_filter_hook {
  67         TAILQ_ENTRY(packet_filter_hook) pfil_link;
  68         pfil_func_t     pfil_func;
  69         void            *pfil_arg;
  70         int             pfil_flags;
  71 };
  72
  73 struct netmsg_pfil {
  74         struct netmsg_base      base;
  75         pfil_func_t             pfil_func;
  76         void                    *pfil_arg;
  77         int                     pfil_flags;
  78         struct pfil_head        *pfil_ph;
  79 };
  80
  81 static LIST_HEAD(, pfil_head) pfil_head_list =
  82         LIST_HEAD_INITIALIZER(&pfil_head_list);
  83
  84 static pfil_list_t      *pfil_list_alloc(void);
  85 static void             pfil_list_free(pfil_list_t *);
  86 static void             pfil_list_dup(const pfil_list_t *, pfil_list_t *,
  87                                       const struct packet_filter_hook *);
  88 static void             pfil_list_add(pfil_list_t *, pfil_func_t, void *, int);
  89 static struct packet_filter_hook *
  90                         pfil_list_find(const pfil_list_t *, pfil_func_t,
  91                                        const void *);
  92
  93 static void             pfil_remove_hook_dispatch(netmsg_t);
  94 static void             pfil_add_hook_dispatch(netmsg_t);
  95
  96 int filters_default_to_accept = 0;
  97 SYSCTL_INT(_net, OID_AUTO, filters_default_to_accept, CTLFLAG_RW,
  98     &filters_default_to_accept, 0,
  99     "cause ipfw* modules to not block by default");
 100 TUNABLE_INT("net.filters_default_to_accept", &filters_default_to_accept);
 101
 102 /*
 103  * pfil_run_hooks() runs the specified packet filter hooks.
 104  */
 105 int
 106 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
 107     int dir)
 108 {
 109         struct packet_filter_hook *pfh;
 110         struct mbuf *m = *mp;
 111         pfil_list_t *list;
 112         int rv = 0;
 113
 114         if (dir == PFIL_IN)
 115                 list = ph->ph_in;
 116         else if (dir == PFIL_OUT)
 117                 list = ph->ph_out;
 118         else
 119                 return 0; /* XXX panic? */
 120
 121         TAILQ_FOREACH(pfh, list, pfil_link) {
 122                 if (pfh->pfil_func != NULL) {
 123                         PFIL_GETMPLOCK(pfh);
 124                         rv = pfh->pfil_func(pfh->pfil_arg, &m, ifp, dir);
 125                         PFIL_RELMPLOCK(pfh);
 126
 127                         if (rv != 0 || m == NULL)
 128                                 break;
 129                 }
 130         }
 131
 132         *mp = m;
 133         return (rv);
 134 }
 135
 136 /*
 137  * pfil_head_register() registers a pfil_head with the packet filter
 138  * hook mechanism.
 139  */
 140 int
 141 pfil_head_register(struct pfil_head *ph)
 142 {
 143         struct pfil_head *lph;
 144
 145         LIST_FOREACH(lph, &pfil_head_list, ph_list) {
 146                 if (ph->ph_type == lph->ph_type &&
 147                     ph->ph_un.phu_val == lph->ph_un.phu_val)
 148                         return EEXIST;
 149         }
 150
 151         ph->ph_in = pfil_list_alloc();
 152         ph->ph_out = pfil_list_alloc();
 153         ph->ph_hashooks = 0;
 154
 155         LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
 156
 157         return (0);
 158 }
 159
 160 /*
 161  * pfil_head_unregister() removes a pfil_head from the packet filter
 162  * hook mechanism.
 163  */
 164 int
 165 pfil_head_unregister(struct pfil_head *pfh)
 166 {
 167         LIST_REMOVE(pfh, ph_list);
 168         return (0);
 169 }
 170
 171 /*
 172  * pfil_head_get() returns the pfil_head for a given key/dlt.
 173  */
 174 struct pfil_head *
 175 pfil_head_get(int type, u_long val)
 176 {
 177         struct pfil_head *ph;
 178
 179         LIST_FOREACH(ph, &pfil_head_list, ph_list) {
 180                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
 181                         break;
 182         }
 183         return (ph);
 184 }
 185
 186 static void
 187 pfil_add_hook_dispatch(netmsg_t nmsg)
 188 {
 189         struct netmsg_pfil *pfilmsg = (struct netmsg_pfil *)nmsg;
 190         pfil_func_t func = pfilmsg->pfil_func;
 191         void *arg = pfilmsg->pfil_arg;
 192         int flags = pfilmsg->pfil_flags;
 193         struct pfil_head *ph = pfilmsg->pfil_ph;
 194         const struct packet_filter_hook *pfh;
 195         pfil_list_t *list_in = NULL, *list_out = NULL;
 196         pfil_list_t *old_list_in = NULL, *old_list_out = NULL;
 197         int err = 0;
 198
 199         /* This probably should not happen ... */
 200         if ((flags & (PFIL_IN | PFIL_OUT)) == 0)
 201                 goto reply; /* XXX panic? */
 202
 203         /*
 204          * If pfil hooks exist on any of the requested lists,
 205          * then bail out.
 206          */
 207         if (flags & PFIL_IN) {
 208                 pfh = pfil_list_find(ph->ph_in, func, arg);
 209                 if (pfh != NULL) {
 210                         err = EEXIST;
 211                         goto reply;
 212                 }
 213         }
 214         if (flags & PFIL_OUT) {
 215                 pfh = pfil_list_find(ph->ph_out, func, arg);
 216                 if (pfh != NULL) {
 217                         err = EEXIST;
 218                         goto reply;
 219                 }
 220         }
 221
 222         /*
 223          * Duplicate the requested lists, install new hooks
 224          * on the duplication
 225          */
 226         if (flags & PFIL_IN) {
 227                 list_in = pfil_list_alloc();
 228                 pfil_list_dup(ph->ph_in, list_in, NULL);
 229                 pfil_list_add(list_in, func, arg, flags & ~PFIL_OUT);
 230         }
 231         if (flags & PFIL_OUT) {
 232                 list_out = pfil_list_alloc();
 233                 pfil_list_dup(ph->ph_out, list_out, NULL);
 234                 pfil_list_add(list_out, func, arg, flags & ~PFIL_IN);
 235         }
 236
 237         /*
 238          * Switch list pointers, but keep the old ones
 239          */
 240         if (list_in != NULL) {
 241                 old_list_in = ph->ph_in;
 242                 ph->ph_in = list_in;
 243         }
 244         if (list_out != NULL) {
 245                 old_list_out = ph->ph_out;
 246                 ph->ph_out = list_out;
 247         }
 248
 249         /*
 250          * Wait until everyone has finished the old lists iteration
 251          */
 252         netmsg_service_sync();
 253         ph->ph_hashooks = 1;
 254
 255         /*
 256          * Now it is safe to free the old lists, since no one sees it
 257          */
 258         if (old_list_in != NULL)
 259                 pfil_list_free(old_list_in);
 260         if (old_list_out != NULL)
 261                 pfil_list_free(old_list_out);
 262 reply:
 263         lwkt_replymsg(&nmsg->base.lmsg, err);
 264 }
 265
 266 /*
 267  * pfil_add_hook() adds a function to the packet filter hook.  the
 268  * flags are:
 269  *      PFIL_IN         call me on incoming packets
 270  *      PFIL_OUT        call me on outgoing packets
 271  *      PFIL_ALL        call me on all of the above
 272  *      PFIL_MPSAFE     call me without BGL
 273  */
 274 int
 275 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
 276 {
 277         struct netmsg_pfil pfilmsg;
 278         netmsg_base_t nmsg;
 279         int error;
 280
 281         nmsg = &pfilmsg.base;
 282         netmsg_init(nmsg, NULL, &curthread->td_msgport,
 283                     0, pfil_add_hook_dispatch);
 284         pfilmsg.pfil_func = func;
 285         pfilmsg.pfil_arg = arg;
 286         pfilmsg.pfil_flags = flags;
 287         pfilmsg.pfil_ph = ph;
 288
 289         error = lwkt_domsg(PFIL_CFGPORT, &nmsg->lmsg, 0);
 290         return error;
 291 }
 292
 293 static void
 294 pfil_remove_hook_dispatch(netmsg_t nmsg)
 295 {
 296         struct netmsg_pfil *pfilmsg = (struct netmsg_pfil *)nmsg;
 297         pfil_func_t func = pfilmsg->pfil_func;
 298         void *arg = pfilmsg->pfil_arg;
 299         int flags = pfilmsg->pfil_flags;
 300         struct pfil_head *ph = pfilmsg->pfil_ph;
 301         struct packet_filter_hook *skip_in = NULL, *skip_out = NULL;
 302         pfil_list_t *list_in = NULL, *list_out = NULL;
 303         pfil_list_t *old_list_in = NULL, *old_list_out = NULL;
 304         int err = 0;
 305
 306         /* This probably should not happen ... */
 307         if ((flags & (PFIL_IN | PFIL_OUT)) == 0)
 308                 goto reply; /* XXX panic? */
 309
 310         /*
 311          * The pfil hook should exist on all requested lists,
 312          * if not just bail out
 313          */
 314         if (flags & PFIL_IN) {
 315                 skip_in = pfil_list_find(ph->ph_in, func, arg);
 316                 if (!skip_in) {
 317                         err = ENOENT;
 318                         goto reply;
 319                 }
 320         }
 321         if (flags & PFIL_OUT) {
 322                 skip_out = pfil_list_find(ph->ph_out, func, arg);
 323                 if (!skip_out) {
 324                         err = ENOENT;
 325                         goto reply;
 326                 }
 327         }
 328
 329         /*
 330          * Duplicate the requested lists, but the pfil hook to
 331          * be deleted is not copied
 332          */
 333         if (flags & PFIL_IN) {
 334                 KKASSERT(skip_in != NULL);
 335                 list_in = pfil_list_alloc();
 336                 pfil_list_dup(ph->ph_in, list_in, skip_in);
 337         }
 338         if (flags & PFIL_OUT) {
 339                 KKASSERT(skip_out != NULL);
 340                 list_out = pfil_list_alloc();
 341                 pfil_list_dup(ph->ph_out, list_out, skip_out);
 342         }
 343
 344         /*
 345          * Switch list pointers, but keep the old ones
 346          */
 347         if (list_in != NULL) {
 348                 old_list_in = ph->ph_in;
 349                 ph->ph_in = list_in;
 350         }
 351         if (list_out != NULL) {
 352                 old_list_out = ph->ph_out;
 353                 ph->ph_out = list_out;
 354         }
 355
 356         /*
 357          * Wait until everyone has finished the old lists iteration
 358          */
 359         if (TAILQ_EMPTY(ph->ph_in) && TAILQ_EMPTY(ph->ph_out))
 360                 ph->ph_hashooks = 0;
 361         netmsg_service_sync();
 362
 363         /*
 364          * Now it is safe to free the old lists, since no one sees it
 365          */
 366         if (old_list_in != NULL)
 367                 pfil_list_free(old_list_in);
 368         if (old_list_out != NULL)
 369                 pfil_list_free(old_list_out);
 370 reply:
 371         lwkt_replymsg(&nmsg->base.lmsg, err);
 372 }
 373
 374 /*
 375  * pfil_remove_hook removes a specific function from the packet filter
 376  * hook list.
 377  */
 378 int
 379 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
 380 {
 381         struct netmsg_pfil pfilmsg;
 382         netmsg_base_t nmsg;
 383
 384         nmsg = &pfilmsg.base;
 385         netmsg_init(nmsg, NULL, &curthread->td_msgport,
 386                     0, pfil_remove_hook_dispatch);
 387         pfilmsg.pfil_func = func;
 388         pfilmsg.pfil_arg = arg;
 389         pfilmsg.pfil_flags = flags;
 390         pfilmsg.pfil_ph = ph;
 391
 392         return lwkt_domsg(PFIL_CFGPORT, &nmsg->lmsg, 0);
 393 }
 394
 395 static void
 396 pfil_list_add(pfil_list_t *list, pfil_func_t func, void *arg, int flags)
 397 {
 398         struct packet_filter_hook *pfh;
 399
 400         KKASSERT(&curthread->td_msgport == PFIL_CFGPORT);
 401
 402         pfh = kmalloc(sizeof(*pfh), M_IFADDR, M_WAITOK);
 403
 404         pfh->pfil_func = func;
 405         pfh->pfil_arg  = arg;
 406         pfh->pfil_flags = flags;
 407
 408         /*
 409          * Insert the input list in reverse order of the output list
 410          * so that the same path is followed in or out of the kernel.
 411          */
 412         if (flags & PFIL_IN)
 413                 TAILQ_INSERT_HEAD(list, pfh, pfil_link);
 414         else
 415                 TAILQ_INSERT_TAIL(list, pfh, pfil_link);
 416 }
 417
 418 static void
 419 pfil_list_dup(const pfil_list_t *from, pfil_list_t *to,
 420               const struct packet_filter_hook *skip)
 421 {
 422         struct packet_filter_hook *pfh_to, *pfh_from;
 423
 424         KKASSERT(&curthread->td_msgport == PFIL_CFGPORT);
 425         KKASSERT(TAILQ_EMPTY(to));
 426
 427         TAILQ_FOREACH(pfh_from, from, pfil_link) {
 428                 if (pfh_from == skip)
 429                         continue;
 430
 431                 pfh_to = kmalloc(sizeof(*pfh_to), M_IFADDR, M_WAITOK);
 432                 bcopy(pfh_from, pfh_to, sizeof(*pfh_to));
 433
 434                 TAILQ_INSERT_TAIL(to, pfh_to, pfil_link);
 435         }
 436 }
 437
 438 static pfil_list_t *
 439 pfil_list_alloc(void)
 440 {
 441         pfil_list_t *list;
 442
 443         list = kmalloc(sizeof(*list), M_IFADDR, M_WAITOK);
 444         TAILQ_INIT(list);
 445         return list;
 446 }
 447
 448 static void
 449 pfil_list_free(pfil_list_t *list)
 450 {
 451         struct packet_filter_hook *pfh;
 452
 453         while ((pfh = TAILQ_FIRST(list)) != NULL) {
 454                 TAILQ_REMOVE(list, pfh, pfil_link);
 455                 kfree(pfh, M_IFADDR);
 456         }
 457         kfree(list, M_IFADDR);
 458 }
 459
 460 static struct packet_filter_hook *
 461 pfil_list_find(const pfil_list_t *list, pfil_func_t func, const void *arg)
 462 {
 463         struct packet_filter_hook *pfh;
 464
 465         KKASSERT(&curthread->td_msgport == PFIL_CFGPORT);
 466
 467         TAILQ_FOREACH(pfh, list, pfil_link) {
 468                 if (pfh->pfil_func == func && pfh->pfil_arg == arg)
 469                         return pfh;
 470         }
 471         return NULL;
 472 }