pfil.c revision 242079
1/* $FreeBSD: head/sys/net/pfil.c 242079 2012-10-25 09:39:14Z ae $ */ 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/sysctl.h> 41#include <sys/systm.h> 42#include <sys/condvar.h> 43#include <sys/lock.h> 44#include <sys/mutex.h> 45#include <sys/proc.h> 46#include <sys/queue.h> 47 48#include <net/if.h> 49#include <net/pfil.h> 50 51static struct mtx pfil_global_lock; 52 53MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", 54 MTX_DEF); 55 56static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int); 57 58static int pfil_list_remove(pfil_list_t *, 59 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 60 void *); 61 62LIST_HEAD(pfilheadhead, pfil_head); 63VNET_DEFINE(struct pfilheadhead, pfil_head_list); 64#define V_pfil_head_list VNET(pfil_head_list) 65VNET_DEFINE(struct rmlock, pfil_lock); 66#define V_pfil_lock VNET(pfil_lock) 67 68VNET_DEFINE(int, pfilforward) = 0; 69SYSCTL_NODE(_net, OID_AUTO, pfil, CTLFLAG_RW, 0, "Packer filter interface"); 70SYSCTL_VNET_INT(_net_pfil, OID_AUTO, forward, CTLFLAG_RW, 71 &VNET_NAME(pfilforward), 0, 72 "Enable forwarding performed by packet filters"); 73/* 74 * pfil_run_hooks() runs the specified packet filter hooks. 75 */ 76int 77pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 78 int dir, struct inpcb *inp) 79{ 80 struct rm_priotracker rmpt; 81 struct packet_filter_hook *pfh; 82 struct mbuf *m = *mp; 83 int rv = 0; 84 85 PFIL_RLOCK(ph, &rmpt); 86 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0")); 87 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 88 pfh = TAILQ_NEXT(pfh, pfil_link)) { 89 if (pfh->pfil_func != NULL) { 90 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, 91 inp); 92 if (rv != 0 || m == NULL) 93 break; 94 } 95 } 96 PFIL_RUNLOCK(ph, &rmpt); 97 *mp = m; 98 return (rv); 99} 100 101/* 102 * pfil_try_rlock() acquires rm reader lock for specified head 103 * if this is immediately possible, 104 */ 105int 106pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker) 107{ 108 return PFIL_TRY_RLOCK(ph, tracker); 109} 110 111/* 112 * pfil_rlock() acquires rm reader lock for specified head. 113 */ 114void 115pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker) 116{ 117 PFIL_RLOCK(ph, tracker); 118} 119 120/* 121 * pfil_runlock() releases reader lock for specified head. 122 */ 123void 124pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker) 125{ 126 PFIL_RUNLOCK(ph, tracker); 127} 128 129/* 130 * pfil_wlock() acquires writer lock for specified head. 131 */ 132void 133pfil_wlock(struct pfil_head *ph) 134{ 135 PFIL_WLOCK(ph); 136} 137 138/* 139 * pfil_wunlock() releases writer lock for specified head. 140 */ 141void 142pfil_wunlock(struct pfil_head *ph) 143{ 144 PFIL_WUNLOCK(ph); 145} 146 147/* 148 * pfil_wowned() releases writer lock for specified head. 149 */ 150int 151pfil_wowned(struct pfil_head *ph) 152{ 153 return PFIL_WOWNED(ph); 154} 155/* 156 * pfil_head_register() registers a pfil_head with the packet filter hook 157 * mechanism. 158 */ 159int 160pfil_head_register(struct pfil_head *ph) 161{ 162 struct pfil_head *lph; 163 164 PFIL_LIST_LOCK(); 165 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) { 166 if (ph->ph_type == lph->ph_type && 167 ph->ph_un.phu_val == lph->ph_un.phu_val) { 168 PFIL_LIST_UNLOCK(); 169 return (EEXIST); 170 } 171 } 172 PFIL_LOCK_INIT(ph); 173 ph->ph_nhooks = 0; 174 TAILQ_INIT(&ph->ph_in); 175 TAILQ_INIT(&ph->ph_out); 176 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list); 177 PFIL_LIST_UNLOCK(); 178 return (0); 179} 180 181/* 182 * pfil_head_unregister() removes a pfil_head from the packet filter hook 183 * mechanism. The producer of the hook promises that all outstanding 184 * invocations of the hook have completed before it unregisters the hook. 185 */ 186int 187pfil_head_unregister(struct pfil_head *ph) 188{ 189 struct packet_filter_hook *pfh, *pfnext; 190 191 PFIL_LIST_LOCK(); 192 LIST_REMOVE(ph, ph_list); 193 PFIL_LIST_UNLOCK(); 194 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 195 free(pfh, M_IFADDR); 196 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 197 free(pfh, M_IFADDR); 198 PFIL_LOCK_DESTROY(ph); 199 return (0); 200} 201 202/* 203 * pfil_head_get() returns the pfil_head for a given key/dlt. 204 */ 205struct pfil_head * 206pfil_head_get(int type, u_long val) 207{ 208 struct pfil_head *ph; 209 210 PFIL_LIST_LOCK(); 211 LIST_FOREACH(ph, &V_pfil_head_list, ph_list) 212 if (ph->ph_type == type && ph->ph_un.phu_val == val) 213 break; 214 PFIL_LIST_UNLOCK(); 215 return (ph); 216} 217 218/* 219 * pfil_add_hook() adds a function to the packet filter hook. the 220 * flags are: 221 * PFIL_IN call me on incoming packets 222 * PFIL_OUT call me on outgoing packets 223 * PFIL_ALL call me on all of the above 224 * PFIL_WAITOK OK to call malloc with M_WAITOK. 225 */ 226int 227pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, 228 struct inpcb *), 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(int (*func)(void *, struct mbuf **, struct ifnet *, int, 288 struct inpcb *), void *arg, int flags, struct pfil_head *ph) 289{ 290 int err = 0; 291 292 PFIL_WLOCK(ph); 293 if (flags & PFIL_IN) { 294 err = pfil_list_remove(&ph->ph_in, func, arg); 295 if (err == 0) 296 ph->ph_nhooks--; 297 } 298 if ((err == 0) && (flags & PFIL_OUT)) { 299 err = pfil_list_remove(&ph->ph_out, func, arg); 300 if (err == 0) 301 ph->ph_nhooks--; 302 } 303 PFIL_WUNLOCK(ph); 304 return (err); 305} 306 307static int 308pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 309{ 310 struct packet_filter_hook *pfh; 311 312 /* 313 * First make sure the hook is not already there. 314 */ 315 TAILQ_FOREACH(pfh, list, pfil_link) 316 if (pfh->pfil_func == pfh1->pfil_func && 317 pfh->pfil_arg == pfh1->pfil_arg) 318 return (EEXIST); 319 320 /* 321 * Insert the input list in reverse order of the output list so that 322 * the same path is followed in or out of the kernel. 323 */ 324 if (flags & PFIL_IN) 325 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 326 else 327 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 328 return (0); 329} 330 331/* 332 * pfil_list_remove is an internal function that takes a function off the 333 * specified list. 334 */ 335static int 336pfil_list_remove(pfil_list_t *list, 337 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 338 void *arg) 339{ 340 struct packet_filter_hook *pfh; 341 342 TAILQ_FOREACH(pfh, list, pfil_link) 343 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 344 TAILQ_REMOVE(list, pfh, pfil_link); 345 free(pfh, M_IFADDR); 346 return (0); 347 } 348 return (ENOENT); 349} 350 351/* 352 * Stuff that must be initialized for every instance (including the first of 353 * course). 354 */ 355static int 356vnet_pfil_init(const void *unused) 357{ 358 359 LIST_INIT(&V_pfil_head_list); 360 PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared"); 361 return (0); 362} 363 364/* 365 * Called for the removal of each instance. 366 */ 367static int 368vnet_pfil_uninit(const void *unused) 369{ 370 371 /* XXX should panic if list is not empty */ 372 PFIL_LOCK_DESTROY_REAL(&V_pfil_lock); 373 return (0); 374} 375 376/* Define startup order. */ 377#define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN 378#define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */ 379#define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */ 380 381/* 382 * Starting up. 383 * 384 * VNET_SYSINIT is called for each existing vnet and each new vnet. 385 */ 386VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 387 vnet_pfil_init, NULL); 388 389/* 390 * Closing up shop. These are done in REVERSE ORDER. Not called on reboot. 391 * 392 * VNET_SYSUNINIT is called for each exiting vnet as it exits. 393 */ 394VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 395 vnet_pfil_uninit, NULL); 396