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