sys/net/pfil.c

   1 /*      $FreeBSD$ */
   2 /*      $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem 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/kernel.h>
  34 #include <sys/errno.h>
  35 #include <sys/lock.h>
  36 #include <sys/malloc.h>
  37 #include <sys/rmlock.h>
  38 #include <sys/socket.h>
  39 #include <sys/socketvar.h>
  40 #include <sys/systm.h>
  41 #include <sys/condvar.h>
  42 #include <sys/lock.h>
  43 #include <sys/mutex.h>
  44 #include <sys/proc.h>
  45 #include <sys/queue.h>
  46
  47 #include <net/if.h>
  48 #include <net/if_var.h>
  49 #include <net/pfil.h>
  50
  51 static struct mtx pfil_global_lock;
  52
  53 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock",
  54   MTX_DEF);
  55
  56 static struct packet_filter_hook *pfil_chain_get(int, struct pfil_head *);
  57 static int pfil_chain_add(pfil_chain_t *, struct packet_filter_hook *, int);
  58 static int pfil_chain_remove(pfil_chain_t *, pfil_func_t, void *);
  59
  60 LIST_HEAD(pfilheadhead, pfil_head);
  61 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
  62 #define V_pfil_head_list        VNET(pfil_head_list)
  63 VNET_DEFINE(struct rmlock, pfil_lock);
  64 #define V_pfil_lock     VNET(pfil_lock)
  65
  66 /*
  67  * pfil_run_hooks() runs the specified packet filter hook chain.
  68  */
  69 int
  70 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
  71     int dir, struct inpcb *inp)
  72 {
  73         struct rm_priotracker rmpt;
  74         struct packet_filter_hook *pfh;
  75         struct mbuf *m = *mp;
  76         int rv = 0;
  77
  78         PFIL_RLOCK(ph, &rmpt);
  79         KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
  80         for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
  81              pfh = TAILQ_NEXT(pfh, pfil_chain)) {
  82                 if (pfh->pfil_func != NULL) {
  83                         rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
  84                             inp);
  85                         if (rv != 0 || m == NULL)
  86                                 break;
  87                 }
  88         }
  89         PFIL_RUNLOCK(ph, &rmpt);
  90         *mp = m;
  91         return (rv);
  92 }
  93
  94 static struct packet_filter_hook *
  95 pfil_chain_get(int dir, struct pfil_head *ph)
  96 {
  97
  98         if (dir == PFIL_IN)
  99                 return (TAILQ_FIRST(&ph->ph_in));
 100         else if (dir == PFIL_OUT)
 101                 return (TAILQ_FIRST(&ph->ph_out));
 102         else
 103                 return (NULL);
 104 }
 105
 106 /*
 107  * pfil_try_rlock() acquires rm reader lock for specified head
 108  * if this is immediately possible.
 109  */
 110 int
 111 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
 112 {
 113
 114         return (PFIL_TRY_RLOCK(ph, tracker));
 115 }
 116
 117 /*
 118  * pfil_rlock() acquires rm reader lock for specified head.
 119  */
 120 void
 121 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
 122 {
 123
 124         PFIL_RLOCK(ph, tracker);
 125 }
 126
 127 /*
 128  * pfil_runlock() releases reader lock for specified head.
 129  */
 130 void
 131 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
 132 {
 133
 134         PFIL_RUNLOCK(ph, tracker);
 135 }
 136
 137 /*
 138  * pfil_wlock() acquires writer lock for specified head.
 139  */
 140 void
 141 pfil_wlock(struct pfil_head *ph)
 142 {
 143
 144         PFIL_WLOCK(ph);
 145 }
 146
 147 /*
 148  * pfil_wunlock() releases writer lock for specified head.
 149  */
 150 void
 151 pfil_wunlock(struct pfil_head *ph)
 152 {
 153
 154         PFIL_WUNLOCK(ph);
 155 }
 156
 157 /*
 158  * pfil_wowned() returns a non-zero value if the current thread owns
 159  * an exclusive lock.
 160  */
 161 int
 162 pfil_wowned(struct pfil_head *ph)
 163 {
 164
 165         return (PFIL_WOWNED(ph));
 166 }
 167
 168 /*
 169  * pfil_head_register() registers a pfil_head with the packet filter hook
 170  * mechanism.
 171  */
 172 int
 173 pfil_head_register(struct pfil_head *ph)
 174 {
 175         struct pfil_head *lph;
 176
 177         PFIL_HEADLIST_LOCK();
 178         LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
 179                 if (ph->ph_type == lph->ph_type &&
 180                     ph->ph_un.phu_val == lph->ph_un.phu_val) {
 181                         PFIL_HEADLIST_UNLOCK();
 182                         return (EEXIST);
 183                 }
 184         }
 185         PFIL_LOCK_INIT(ph);
 186         ph->ph_nhooks = 0;
 187         TAILQ_INIT(&ph->ph_in);
 188         TAILQ_INIT(&ph->ph_out);
 189         LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
 190         PFIL_HEADLIST_UNLOCK();
 191         return (0);
 192 }
 193
 194 /*
 195  * pfil_head_unregister() removes a pfil_head from the packet filter hook
 196  * mechanism.  The producer of the hook promises that all outstanding
 197  * invocations of the hook have completed before it unregisters the hook.
 198  */
 199 int
 200 pfil_head_unregister(struct pfil_head *ph)
 201 {
 202         struct packet_filter_hook *pfh, *pfnext;
 203
 204         PFIL_HEADLIST_LOCK();
 205         LIST_REMOVE(ph, ph_list);
 206         PFIL_HEADLIST_UNLOCK();
 207         TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
 208                 free(pfh, M_IFADDR);
 209         TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
 210                 free(pfh, M_IFADDR);
 211         PFIL_LOCK_DESTROY(ph);
 212         return (0);
 213 }
 214
 215 /*
 216  * pfil_head_get() returns the pfil_head for a given key/dlt.
 217  */
 218 struct pfil_head *
 219 pfil_head_get(int type, u_long val)
 220 {
 221         struct pfil_head *ph;
 222
 223         PFIL_HEADLIST_LOCK();
 224         LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
 225                 if (ph->ph_type == type && ph->ph_un.phu_val == val)
 226                         break;
 227         PFIL_HEADLIST_UNLOCK();
 228         return (ph);
 229 }
 230
 231 /*
 232  * pfil_add_hook() adds a function to the packet filter hook.  the
 233  * flags are:
 234  *      PFIL_IN         call me on incoming packets
 235  *      PFIL_OUT        call me on outgoing packets
 236  *      PFIL_ALL        call me on all of the above
 237  *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
 238  */
 239 int
 240 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
 241 {
 242         struct packet_filter_hook *pfh1 = NULL;
 243         struct packet_filter_hook *pfh2 = NULL;
 244         int err;
 245
 246         if (flags & PFIL_IN) {
 247                 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
 248                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
 249                 if (pfh1 == NULL) {
 250                         err = ENOMEM;
 251                         goto error;
 252                 }
 253         }
 254         if (flags & PFIL_OUT) {
 255                 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
 256                     M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
 257                 if (pfh2 == NULL) {
 258                         err = ENOMEM;
 259                         goto error;
 260                 }
 261         }
 262         PFIL_WLOCK(ph);
 263         if (flags & PFIL_IN) {
 264                 pfh1->pfil_func = func;
 265                 pfh1->pfil_arg = arg;
 266                 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
 267                 if (err)
 268                         goto locked_error;
 269                 ph->ph_nhooks++;
 270         }
 271         if (flags & PFIL_OUT) {
 272                 pfh2->pfil_func = func;
 273                 pfh2->pfil_arg = arg;
 274                 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
 275                 if (err) {
 276                         if (flags & PFIL_IN)
 277                                 pfil_chain_remove(&ph->ph_in, func, arg);
 278                         goto locked_error;
 279                 }
 280                 ph->ph_nhooks++;
 281         }
 282         PFIL_WUNLOCK(ph);
 283         return (0);
 284 locked_error:
 285         PFIL_WUNLOCK(ph);
 286 error:
 287         if (pfh1 != NULL)
 288                 free(pfh1, M_IFADDR);
 289         if (pfh2 != NULL)
 290                 free(pfh2, M_IFADDR);
 291         return (err);
 292 }
 293
 294 /*
 295  * pfil_remove_hook removes a specific function from the packet filter hook
 296  * chain.
 297  */
 298 int
 299 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
 300 {
 301         int err = 0;
 302
 303         PFIL_WLOCK(ph);
 304         if (flags & PFIL_IN) {
 305                 err = pfil_chain_remove(&ph->ph_in, func, arg);
 306                 if (err == 0)
 307                         ph->ph_nhooks--;
 308         }
 309         if ((err == 0) && (flags & PFIL_OUT)) {
 310                 err = pfil_chain_remove(&ph->ph_out, func, arg);
 311                 if (err == 0)
 312                         ph->ph_nhooks--;
 313         }
 314         PFIL_WUNLOCK(ph);
 315         return (err);
 316 }
 317
 318 /*
 319  * Internal: Add a new pfil hook into a hook chain.
 320  */
 321 static int
 322 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
 323 {
 324         struct packet_filter_hook *pfh;
 325
 326         /*
 327          * First make sure the hook is not already there.
 328          */
 329         TAILQ_FOREACH(pfh, chain, pfil_chain)
 330                 if (pfh->pfil_func == pfh1->pfil_func &&
 331                     pfh->pfil_arg == pfh1->pfil_arg)
 332                         return (EEXIST);
 333
 334         /*
 335          * Insert the input list in reverse order of the output list so that
 336          * the same path is followed in or out of the kernel.
 337          */
 338         if (flags & PFIL_IN)
 339                 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
 340         else
 341                 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
 342         return (0);
 343 }
 344
 345 /*
 346  * Internal: Remove a pfil hook from a hook chain.
 347  */
 348 static int
 349 pfil_chain_remove(pfil_chain_t *chain, pfil_func_t func, void *arg)
 350 {
 351         struct packet_filter_hook *pfh;
 352
 353         TAILQ_FOREACH(pfh, chain, pfil_chain)
 354                 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
 355                         TAILQ_REMOVE(chain, pfh, pfil_chain);
 356                         free(pfh, M_IFADDR);
 357                         return (0);
 358                 }
 359         return (ENOENT);
 360 }
 361
 362 /*
 363  * Stuff that must be initialized for every instance (including the first of
 364  * course).
 365  */
 366 static int
 367 vnet_pfil_init(const void *unused)
 368 {
 369
 370         LIST_INIT(&V_pfil_head_list);
 371         PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
 372         return (0);
 373 }
 374
 375 /*
 376  * Called for the removal of each instance.
 377  */
 378 static int
 379 vnet_pfil_uninit(const void *unused)
 380 {
 381
 382         KASSERT(LIST_EMPTY(&V_pfil_head_list),
 383             ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
 384         PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
 385         return (0);
 386 }
 387
 388 /* Define startup order. */
 389 #define PFIL_SYSINIT_ORDER      SI_SUB_PROTO_BEGIN
 390 #define PFIL_MODEVENT_ORDER     (SI_ORDER_FIRST) /* On boot slot in here. */
 391 #define PFIL_VNET_ORDER         (PFIL_MODEVENT_ORDER + 2) /* Later still. */
 392
 393 /*
 394  * Starting up.
 395  *
 396  * VNET_SYSINIT is called for each existing vnet and each new vnet.
 397  */
 398 VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
 399     vnet_pfil_init, NULL);
 400
 401 /*
 402  * Closing up shop.  These are done in REVERSE ORDER.  Not called on reboot.
 403  *
 404  * VNET_SYSUNINIT is called for each exiting vnet as it exits.
 405  */
 406 VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
 407     vnet_pfil_uninit, NULL);