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/malloc.h> 36 #include <sys/socket.h> 37 #include <sys/socketvar.h> 38 #include <sys/systm.h> 39 #include <sys/condvar.h> 40 #include <sys/lock.h> 41 #include <sys/mutex.h> 42 #include <sys/proc.h> 43 #include <sys/queue.h> 44 45 #include <net/if.h> 46 #include <net/pfil.h> 47 48 static struct mtx pfil_global_lock; 49 50 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", MTX_DEF); 51 52 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int); 53 54 static int pfil_list_remove(pfil_list_t *, 55 int (*)(void *, struct mbuf **, struct ifnet *, int), void *); 56 57 LIST_HEAD(, pfil_head) pfil_head_list = 58 LIST_HEAD_INITIALIZER(&pfil_head_list); 59 60 static __inline void 61 PFIL_RLOCK(struct pfil_head *ph) 62 { 63 mtx_lock(&ph->ph_mtx); 64 ph->ph_busy_count++; 65 mtx_unlock(&ph->ph_mtx); 66 } 67 68 static __inline void 69 PFIL_RUNLOCK(struct pfil_head *ph) 70 { 71 mtx_lock(&ph->ph_mtx); 72 ph->ph_busy_count--; 73 if (ph->ph_busy_count == 0 && ph->ph_want_write) 74 cv_signal(&ph->ph_cv); 75 mtx_unlock(&ph->ph_mtx); 76 } 77 78 static __inline void 79 PFIL_WLOCK(struct pfil_head *ph) 80 { 81 mtx_lock(&ph->ph_mtx); 82 ph->ph_want_write = 1; 83 while (ph->ph_busy_count > 0) 84 cv_wait(&ph->ph_cv, &ph->ph_mtx); 85 } 86 87 static __inline int 88 PFIL_TRY_WLOCK(struct pfil_head *ph) 89 { 90 mtx_lock(&ph->ph_mtx); 91 ph->ph_want_write = 1; 92 if (ph->ph_busy_count > 0) { 93 ph->ph_want_write = 0; 94 mtx_unlock(&ph->ph_mtx); 95 return EBUSY; 96 } 97 return 0; 98 } 99 100 static __inline void 101 PFIL_WUNLOCK(struct pfil_head *ph) 102 { 103 ph->ph_want_write = 0; \ 104 mtx_unlock(&ph->ph_mtx); 105 cv_signal(&ph->ph_cv); 106 } 107 108 #define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock) 109 #define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock) 110 111 /* 112 * pfil_run_hooks() runs the specified packet filter hooks. 113 */ 114 int 115 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 116 int dir) 117 { 118 struct packet_filter_hook *pfh; 119 struct mbuf *m = *mp; 120 int rv = 0; 121 122 if (ph->ph_busy_count == -1 || ph->ph_want_write) 123 return (0); 124 125 PFIL_RLOCK(ph); 126 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 127 pfh = TAILQ_NEXT(pfh, pfil_link)) { 128 if (pfh->pfil_func != NULL) { 129 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir); 130 if (rv != 0 || m == NULL) 131 break; 132 } 133 } 134 PFIL_RUNLOCK(ph); 135 136 *mp = m; 137 return (rv); 138 } 139 140 /* 141 * pfil_head_register() registers a pfil_head with the packet filter 142 * hook mechanism. 143 */ 144 int 145 pfil_head_register(struct pfil_head *ph) 146 { 147 struct pfil_head *lph; 148 149 PFIL_LIST_LOCK(); 150 LIST_FOREACH(lph, &pfil_head_list, ph_list) 151 if (ph->ph_type == lph->ph_type && 152 ph->ph_un.phu_val == lph->ph_un.phu_val) { 153 PFIL_LIST_UNLOCK(); 154 return EEXIST; 155 } 156 PFIL_LIST_UNLOCK(); 157 158 if (mtx_initialized(&ph->ph_mtx)) { /* should not happen */ 159 KASSERT((0), ("%s: allready initialized!", __func__)); 160 return EBUSY; 161 } else { 162 ph->ph_busy_count = -1; 163 ph->ph_want_write = 1; 164 mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF); 165 cv_init(&ph->ph_cv, "pfil_head_cv"); 166 mtx_lock(&ph->ph_mtx); /* XXX: race? */ 167 } 168 169 TAILQ_INIT(&ph->ph_in); 170 TAILQ_INIT(&ph->ph_out); 171 172 PFIL_LIST_LOCK(); 173 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 174 PFIL_LIST_UNLOCK(); 175 176 PFIL_WUNLOCK(ph); 177 178 return (0); 179 } 180 181 /* 182 * pfil_head_unregister() removes a pfil_head from the packet filter 183 * hook mechanism. 184 */ 185 int 186 pfil_head_unregister(struct pfil_head *ph) 187 { 188 struct packet_filter_hook *pfh, *pfnext; 189 190 PFIL_LIST_LOCK(); 191 /* 192 * LIST_REMOVE is safe for unlocked pfil_heads in ph_list. 193 * No need to WLOCK all of them. 194 */ 195 LIST_REMOVE(ph, ph_list); 196 PFIL_LIST_UNLOCK(); 197 198 PFIL_WLOCK(ph); /* XXX: may sleep (cv_wait)! */ 199 200 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 201 free(pfh, M_IFADDR); 202 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 203 free(pfh, M_IFADDR); 204 cv_destroy(&ph->ph_cv); 205 mtx_destroy(&ph->ph_mtx); 206 207 return (0); 208 } 209 210 /* 211 * pfil_head_get() returns the pfil_head for a given key/dlt. 212 */ 213 struct pfil_head * 214 pfil_head_get(int type, u_long val) 215 { 216 struct pfil_head *ph; 217 218 PFIL_LIST_LOCK(); 219 LIST_FOREACH(ph, &pfil_head_list, ph_list) 220 if (ph->ph_type == type && ph->ph_un.phu_val == val) 221 break; 222 PFIL_LIST_UNLOCK(); 223 224 return (ph); 225 } 226 227 /* 228 * pfil_add_hook() adds a function to the packet filter hook. the 229 * flags are: 230 * PFIL_IN call me on incoming packets 231 * PFIL_OUT call me on outgoing packets 232 * PFIL_ALL call me on all of the above 233 * PFIL_WAITOK OK to call malloc with M_WAITOK. 234 */ 235 int 236 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 237 void *arg, int flags, struct pfil_head *ph) 238 { 239 struct packet_filter_hook *pfh1 = NULL; 240 struct packet_filter_hook *pfh2 = NULL; 241 int err; 242 243 /* Get memory */ 244 if (flags & PFIL_IN) { 245 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 246 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 247 if (pfh1 == NULL) { 248 err = ENOMEM; 249 goto error; 250 } 251 } 252 if (flags & PFIL_OUT) { 253 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 254 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 255 if (pfh2 == NULL) { 256 err = ENOMEM; 257 goto error; 258 } 259 } 260 261 /* Lock */ 262 if (flags & PFIL_WAITOK) 263 PFIL_WLOCK(ph); 264 else { 265 err = PFIL_TRY_WLOCK(ph); 266 if (err) 267 goto error; 268 } 269 270 /* Add */ 271 if (flags & PFIL_IN) { 272 pfh1->pfil_func = func; 273 pfh1->pfil_arg = arg; 274 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 275 if (err) 276 goto done; 277 } 278 if (flags & PFIL_OUT) { 279 pfh2->pfil_func = func; 280 pfh2->pfil_arg = arg; 281 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 282 if (err) { 283 if (flags & PFIL_IN) 284 pfil_list_remove(&ph->ph_in, func, arg); 285 goto done; 286 } 287 } 288 289 ph->ph_busy_count = 0; 290 PFIL_WUNLOCK(ph); 291 292 return 0; 293 done: 294 PFIL_WUNLOCK(ph); 295 error: 296 if (pfh1 != NULL) 297 free(pfh1, M_IFADDR); 298 if (pfh2 != NULL) 299 free(pfh2, M_IFADDR); 300 return err; 301 } 302 303 /* 304 * pfil_remove_hook removes a specific function from the packet filter 305 * hook list. 306 */ 307 int 308 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 309 void *arg, int flags, struct pfil_head *ph) 310 { 311 int err = 0; 312 313 if (flags & PFIL_WAITOK) 314 PFIL_WLOCK(ph); 315 else { 316 err = PFIL_TRY_WLOCK(ph); 317 if (err) 318 return err; 319 } 320 321 if (flags & PFIL_IN) 322 err = pfil_list_remove(&ph->ph_in, func, arg); 323 if ((err == 0) && (flags & PFIL_OUT)) 324 err = pfil_list_remove(&ph->ph_out, func, arg); 325 326 if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out)) 327 ph->ph_busy_count = -1; 328 329 PFIL_WUNLOCK(ph); 330 331 return err; 332 } 333 334 static int 335 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 336 { 337 struct packet_filter_hook *pfh; 338 339 /* 340 * First make sure the hook is not already there. 341 */ 342 TAILQ_FOREACH(pfh, list, pfil_link) 343 if (pfh->pfil_func == pfh1->pfil_func && 344 pfh->pfil_arg == pfh1->pfil_arg) 345 return EEXIST; 346 /* 347 * insert the input list in reverse order of the output list 348 * so that the same path is followed in or out of the kernel. 349 */ 350 if (flags & PFIL_IN) 351 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 352 else 353 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 354 355 return 0; 356 } 357 358 /* 359 * pfil_list_remove is an internal function that takes a function off the 360 * specified list. 361 */ 362 static int 363 pfil_list_remove(pfil_list_t *list, 364 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg) 365 { 366 struct packet_filter_hook *pfh; 367 368 TAILQ_FOREACH(pfh, list, pfil_link) 369 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 370 TAILQ_REMOVE(list, pfh, pfil_link); 371 free(pfh, M_IFADDR); 372 return 0; 373 } 374 return ENOENT; 375 } 376