pfil.c revision 254769
1/* $FreeBSD: head/sys/net/pfil.c 254769 2013-08-24 10:13:59Z andre $ */ 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 50static struct mtx pfil_global_lock; 51 52MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", 53 MTX_DEF); 54 55static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int); 56 57static int pfil_list_remove(pfil_list_t *, 58 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 59 void *); 60 61LIST_HEAD(pfilheadhead, pfil_head); 62VNET_DEFINE(struct pfilheadhead, pfil_head_list); 63#define V_pfil_head_list VNET(pfil_head_list) 64VNET_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 */ 70int 71pfil_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 */ 99int 100pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker) 101{ 102 103 return (PFIL_TRY_RLOCK(ph, tracker)); 104} 105 106/* 107 * pfil_rlock() acquires rm reader lock for specified head. 108 */ 109void 110pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker) 111{ 112 113 PFIL_RLOCK(ph, tracker); 114} 115 116/* 117 * pfil_runlock() releases reader lock for specified head. 118 */ 119void 120pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker) 121{ 122 123 PFIL_RUNLOCK(ph, tracker); 124} 125 126/* 127 * pfil_wlock() acquires writer lock for specified head. 128 */ 129void 130pfil_wlock(struct pfil_head *ph) 131{ 132 133 PFIL_WLOCK(ph); 134} 135 136/* 137 * pfil_wunlock() releases writer lock for specified head. 138 */ 139void 140pfil_wunlock(struct pfil_head *ph) 141{ 142 143 PFIL_WUNLOCK(ph); 144} 145 146/* 147 * pfil_wowned() returns a non-zero value if the current thread owns 148 * an exclusive lock. 149 */ 150int 151pfil_wowned(struct pfil_head *ph) 152{ 153 154 return (PFIL_WOWNED(ph)); 155} 156/* 157 * pfil_head_register() registers a pfil_head with the packet filter hook 158 * mechanism. 159 */ 160int 161pfil_head_register(struct pfil_head *ph) 162{ 163 struct pfil_head *lph; 164 165 PFIL_LIST_LOCK(); 166 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) { 167 if (ph->ph_type == lph->ph_type && 168 ph->ph_un.phu_val == lph->ph_un.phu_val) { 169 PFIL_LIST_UNLOCK(); 170 return (EEXIST); 171 } 172 } 173 PFIL_LOCK_INIT(ph); 174 ph->ph_nhooks = 0; 175 TAILQ_INIT(&ph->ph_in); 176 TAILQ_INIT(&ph->ph_out); 177 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list); 178 PFIL_LIST_UNLOCK(); 179 return (0); 180} 181 182/* 183 * pfil_head_unregister() removes a pfil_head from the packet filter hook 184 * mechanism. The producer of the hook promises that all outstanding 185 * invocations of the hook have completed before it unregisters the hook. 186 */ 187int 188pfil_head_unregister(struct pfil_head *ph) 189{ 190 struct packet_filter_hook *pfh, *pfnext; 191 192 PFIL_LIST_LOCK(); 193 LIST_REMOVE(ph, ph_list); 194 PFIL_LIST_UNLOCK(); 195 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 196 free(pfh, M_IFADDR); 197 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 198 free(pfh, M_IFADDR); 199 PFIL_LOCK_DESTROY(ph); 200 return (0); 201} 202 203/* 204 * pfil_head_get() returns the pfil_head for a given key/dlt. 205 */ 206struct pfil_head * 207pfil_head_get(int type, u_long val) 208{ 209 struct pfil_head *ph; 210 211 PFIL_LIST_LOCK(); 212 LIST_FOREACH(ph, &V_pfil_head_list, ph_list) 213 if (ph->ph_type == type && ph->ph_un.phu_val == val) 214 break; 215 PFIL_LIST_UNLOCK(); 216 return (ph); 217} 218 219/* 220 * pfil_add_hook() adds a function to the packet filter hook. the 221 * flags are: 222 * PFIL_IN call me on incoming packets 223 * PFIL_OUT call me on outgoing packets 224 * PFIL_ALL call me on all of the above 225 * PFIL_WAITOK OK to call malloc with M_WAITOK. 226 */ 227int 228pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph) 229{ 230 struct packet_filter_hook *pfh1 = NULL; 231 struct packet_filter_hook *pfh2 = NULL; 232 int err; 233 234 if (flags & PFIL_IN) { 235 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 236 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 237 if (pfh1 == NULL) { 238 err = ENOMEM; 239 goto error; 240 } 241 } 242 if (flags & PFIL_OUT) { 243 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 244 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 245 if (pfh2 == NULL) { 246 err = ENOMEM; 247 goto error; 248 } 249 } 250 PFIL_WLOCK(ph); 251 if (flags & PFIL_IN) { 252 pfh1->pfil_func = func; 253 pfh1->pfil_arg = arg; 254 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 255 if (err) 256 goto locked_error; 257 ph->ph_nhooks++; 258 } 259 if (flags & PFIL_OUT) { 260 pfh2->pfil_func = func; 261 pfh2->pfil_arg = arg; 262 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 263 if (err) { 264 if (flags & PFIL_IN) 265 pfil_list_remove(&ph->ph_in, func, arg); 266 goto locked_error; 267 } 268 ph->ph_nhooks++; 269 } 270 PFIL_WUNLOCK(ph); 271 return (0); 272locked_error: 273 PFIL_WUNLOCK(ph); 274error: 275 if (pfh1 != NULL) 276 free(pfh1, M_IFADDR); 277 if (pfh2 != NULL) 278 free(pfh2, M_IFADDR); 279 return (err); 280} 281 282/* 283 * pfil_remove_hook removes a specific function from the packet filter hook 284 * list. 285 */ 286int 287pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph) 288{ 289 int err = 0; 290 291 PFIL_WLOCK(ph); 292 if (flags & PFIL_IN) { 293 err = pfil_list_remove(&ph->ph_in, func, arg); 294 if (err == 0) 295 ph->ph_nhooks--; 296 } 297 if ((err == 0) && (flags & PFIL_OUT)) { 298 err = pfil_list_remove(&ph->ph_out, func, arg); 299 if (err == 0) 300 ph->ph_nhooks--; 301 } 302 PFIL_WUNLOCK(ph); 303 return (err); 304} 305 306static int 307pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 308{ 309 struct packet_filter_hook *pfh; 310 311 /* 312 * First make sure the hook is not already there. 313 */ 314 TAILQ_FOREACH(pfh, list, pfil_link) 315 if (pfh->pfil_func == pfh1->pfil_func && 316 pfh->pfil_arg == pfh1->pfil_arg) 317 return (EEXIST); 318 319 /* 320 * Insert the input list in reverse order of the output list so that 321 * the same path is followed in or out of the kernel. 322 */ 323 if (flags & PFIL_IN) 324 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 325 else 326 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 327 return (0); 328} 329 330/* 331 * pfil_list_remove is an internal function that takes a function off the 332 * specified list. 333 */ 334static int 335pfil_list_remove(pfil_list_t *list, pfil_func_t func, void *arg) 336{ 337 struct packet_filter_hook *pfh; 338 339 TAILQ_FOREACH(pfh, list, pfil_link) 340 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 341 TAILQ_REMOVE(list, pfh, pfil_link); 342 free(pfh, M_IFADDR); 343 return (0); 344 } 345 return (ENOENT); 346} 347 348/* 349 * Stuff that must be initialized for every instance (including the first of 350 * course). 351 */ 352static int 353vnet_pfil_init(const void *unused) 354{ 355 356 LIST_INIT(&V_pfil_head_list); 357 PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared"); 358 return (0); 359} 360 361/* 362 * Called for the removal of each instance. 363 */ 364static int 365vnet_pfil_uninit(const void *unused) 366{ 367 368 /* XXX should panic if list is not empty */ 369 PFIL_LOCK_DESTROY_REAL(&V_pfil_lock); 370 return (0); 371} 372 373/* Define startup order. */ 374#define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN 375#define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */ 376#define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */ 377 378/* 379 * Starting up. 380 * 381 * VNET_SYSINIT is called for each existing vnet and each new vnet. 382 */ 383VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 384 vnet_pfil_init, NULL); 385 386/* 387 * Closing up shop. These are done in REVERSE ORDER. Not called on reboot. 388 * 389 * VNET_SYSUNINIT is called for each exiting vnet as it exits. 390 */ 391VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 392 vnet_pfil_uninit, NULL); 393