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