pfil.c revision 197952
1/* $FreeBSD: head/sys/net/pfil.c 197952 2009-10-11 05:59:43Z julian $ */ 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", MTX_DEF); 53 54static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int); 55 56static int pfil_list_remove(pfil_list_t *, 57 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *); 58 59LIST_HEAD(pfilheadhead, pfil_head); 60VNET_DEFINE(struct pfilheadhead, pfil_head_list); 61#define V_pfil_head_list VNET(pfil_head_list) 62 63/* 64 * pfil_run_hooks() runs the specified packet filter hooks. 65 */ 66int 67pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 68 int dir, struct inpcb *inp) 69{ 70 struct rm_priotracker rmpt; 71 struct packet_filter_hook *pfh; 72 struct mbuf *m = *mp; 73 int rv = 0; 74 75 PFIL_RLOCK(ph, &rmpt); 76 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0")); 77 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 78 pfh = TAILQ_NEXT(pfh, pfil_link)) { 79 if (pfh->pfil_func != NULL) { 80 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp); 81 if (rv != 0 || m == NULL) 82 break; 83 } 84 } 85 PFIL_RUNLOCK(ph, &rmpt); 86 87 *mp = m; 88 return (rv); 89} 90 91/* 92 * pfil_head_register() registers a pfil_head with the packet filter 93 * hook mechanism. 94 */ 95int 96pfil_head_register(struct pfil_head *ph) 97{ 98 struct pfil_head *lph; 99 100 PFIL_LIST_LOCK(); 101 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) { 102 if (ph->ph_type == lph->ph_type && 103 ph->ph_un.phu_val == lph->ph_un.phu_val) { 104 PFIL_LIST_UNLOCK(); 105 return EEXIST; 106 } 107 } 108 PFIL_LOCK_INIT(ph); 109 ph->ph_nhooks = 0; 110 TAILQ_INIT(&ph->ph_in); 111 TAILQ_INIT(&ph->ph_out); 112 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list); 113 PFIL_LIST_UNLOCK(); 114 return (0); 115} 116 117/* 118 * pfil_head_unregister() removes a pfil_head from the packet filter hook 119 * mechanism. The producer of the hook promises that all outstanding 120 * invocations of the hook have completed before it unregisters the hook. 121 */ 122int 123pfil_head_unregister(struct pfil_head *ph) 124{ 125 struct packet_filter_hook *pfh, *pfnext; 126 127 PFIL_LIST_LOCK(); 128 LIST_REMOVE(ph, ph_list); 129 PFIL_LIST_UNLOCK(); 130 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 131 free(pfh, M_IFADDR); 132 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 133 free(pfh, M_IFADDR); 134 PFIL_LOCK_DESTROY(ph); 135 return (0); 136} 137 138/* 139 * pfil_head_get() returns the pfil_head for a given key/dlt. 140 */ 141struct pfil_head * 142pfil_head_get(int type, u_long val) 143{ 144 struct pfil_head *ph; 145 146 PFIL_LIST_LOCK(); 147 LIST_FOREACH(ph, &V_pfil_head_list, ph_list) 148 if (ph->ph_type == type && ph->ph_un.phu_val == val) 149 break; 150 PFIL_LIST_UNLOCK(); 151 152 return (ph); 153} 154 155/* 156 * pfil_add_hook() adds a function to the packet filter hook. the 157 * flags are: 158 * PFIL_IN call me on incoming packets 159 * PFIL_OUT call me on outgoing packets 160 * PFIL_ALL call me on all of the above 161 * PFIL_WAITOK OK to call malloc with M_WAITOK. 162 */ 163int 164pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, 165 struct inpcb *), void *arg, int flags, struct pfil_head *ph) 166{ 167 struct packet_filter_hook *pfh1 = NULL; 168 struct packet_filter_hook *pfh2 = NULL; 169 int err; 170 171 if (flags & PFIL_IN) { 172 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 173 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 174 if (pfh1 == NULL) { 175 err = ENOMEM; 176 goto error; 177 } 178 } 179 if (flags & PFIL_OUT) { 180 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 181 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 182 if (pfh2 == NULL) { 183 err = ENOMEM; 184 goto error; 185 } 186 } 187 PFIL_WLOCK(ph); 188 if (flags & PFIL_IN) { 189 pfh1->pfil_func = func; 190 pfh1->pfil_arg = arg; 191 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 192 if (err) 193 goto locked_error; 194 ph->ph_nhooks++; 195 } 196 if (flags & PFIL_OUT) { 197 pfh2->pfil_func = func; 198 pfh2->pfil_arg = arg; 199 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 200 if (err) { 201 if (flags & PFIL_IN) 202 pfil_list_remove(&ph->ph_in, func, arg); 203 goto locked_error; 204 } 205 ph->ph_nhooks++; 206 } 207 PFIL_WUNLOCK(ph); 208 return 0; 209locked_error: 210 PFIL_WUNLOCK(ph); 211error: 212 if (pfh1 != NULL) 213 free(pfh1, M_IFADDR); 214 if (pfh2 != NULL) 215 free(pfh2, M_IFADDR); 216 return err; 217} 218 219/* 220 * pfil_remove_hook removes a specific function from the packet filter 221 * hook list. 222 */ 223int 224pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 225 void *arg, int flags, struct pfil_head *ph) 226{ 227 int err = 0; 228 229 PFIL_WLOCK(ph); 230 231 if (flags & PFIL_IN) { 232 err = pfil_list_remove(&ph->ph_in, func, arg); 233 if (err == 0) 234 ph->ph_nhooks--; 235 } 236 if ((err == 0) && (flags & PFIL_OUT)) { 237 err = pfil_list_remove(&ph->ph_out, func, arg); 238 if (err == 0) 239 ph->ph_nhooks--; 240 } 241 PFIL_WUNLOCK(ph); 242 243 return err; 244} 245 246static int 247pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 248{ 249 struct packet_filter_hook *pfh; 250 251 /* 252 * First make sure the hook is not already there. 253 */ 254 TAILQ_FOREACH(pfh, list, pfil_link) 255 if (pfh->pfil_func == pfh1->pfil_func && 256 pfh->pfil_arg == pfh1->pfil_arg) 257 return EEXIST; 258 /* 259 * insert the input list in reverse order of the output list 260 * so that the same path is followed in or out of the kernel. 261 */ 262 if (flags & PFIL_IN) 263 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 264 else 265 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 266 267 return 0; 268} 269 270/* 271 * pfil_list_remove is an internal function that takes a function off the 272 * specified list. 273 */ 274static int 275pfil_list_remove(pfil_list_t *list, 276 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg) 277{ 278 struct packet_filter_hook *pfh; 279 280 TAILQ_FOREACH(pfh, list, pfil_link) 281 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 282 TAILQ_REMOVE(list, pfh, pfil_link); 283 free(pfh, M_IFADDR); 284 return 0; 285 } 286 return ENOENT; 287} 288 289/**************** 290 * Stuff that must be initialized for every instance 291 * (including the first of course). 292 */ 293static int 294vnet_pfil_init(const void *unused) 295{ 296 LIST_INIT(&V_pfil_head_list); 297 return (0); 298} 299 300/*********************** 301 * Called for the removal of each instance. 302 */ 303static int 304vnet_pfil_uninit(const void *unused) 305{ 306 /* XXX should panic if list is not empty */ 307 return 0; 308} 309 310/* Define startup order. */ 311#define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN 312#define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */ 313#define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */ 314 315/* 316 * Starting up. 317 * VNET_SYSINIT is called for each existing vnet and each new vnet. 318 */ 319VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 320 vnet_pfil_init, NULL); 321 322/* 323 * Closing up shop. These are done in REVERSE ORDER, 324 * Not called on reboot. 325 * VNET_SYSUNINIT is called for each exiting vnet as it exits. 326 */ 327VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 328 vnet_pfil_uninit, NULL); 329 330