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