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