pfil.c revision 198233
1/* $FreeBSD: head/sys/net/pfil.c 198233 2009-10-19 15:19:14Z rwatson $ */ 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) 64 65/* 66 * pfil_run_hooks() runs the specified packet filter hooks. 67 */ 68int 69pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 70 int dir, struct inpcb *inp) 71{ 72 struct rm_priotracker rmpt; 73 struct packet_filter_hook *pfh; 74 struct mbuf *m = *mp; 75 int rv = 0; 76 77 PFIL_RLOCK(ph, &rmpt); 78 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0")); 79 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 80 pfh = TAILQ_NEXT(pfh, pfil_link)) { 81 if (pfh->pfil_func != NULL) { 82 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, 83 inp); 84 if (rv != 0 || m == NULL) 85 break; 86 } 87 } 88 PFIL_RUNLOCK(ph, &rmpt); 89 *mp = m; 90 return (rv); 91} 92 93/* 94 * pfil_head_register() registers a pfil_head with the packet filter hook 95 * mechanism. 96 */ 97int 98pfil_head_register(struct pfil_head *ph) 99{ 100 struct pfil_head *lph; 101 102 PFIL_LIST_LOCK(); 103 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) { 104 if (ph->ph_type == lph->ph_type && 105 ph->ph_un.phu_val == lph->ph_un.phu_val) { 106 PFIL_LIST_UNLOCK(); 107 return (EEXIST); 108 } 109 } 110 PFIL_LOCK_INIT(ph); 111 ph->ph_nhooks = 0; 112 TAILQ_INIT(&ph->ph_in); 113 TAILQ_INIT(&ph->ph_out); 114 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list); 115 PFIL_LIST_UNLOCK(); 116 return (0); 117} 118 119/* 120 * pfil_head_unregister() removes a pfil_head from the packet filter hook 121 * mechanism. The producer of the hook promises that all outstanding 122 * invocations of the hook have completed before it unregisters the hook. 123 */ 124int 125pfil_head_unregister(struct pfil_head *ph) 126{ 127 struct packet_filter_hook *pfh, *pfnext; 128 129 PFIL_LIST_LOCK(); 130 LIST_REMOVE(ph, ph_list); 131 PFIL_LIST_UNLOCK(); 132 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 133 free(pfh, M_IFADDR); 134 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 135 free(pfh, M_IFADDR); 136 PFIL_LOCK_DESTROY(ph); 137 return (0); 138} 139 140/* 141 * pfil_head_get() returns the pfil_head for a given key/dlt. 142 */ 143struct pfil_head * 144pfil_head_get(int type, u_long val) 145{ 146 struct pfil_head *ph; 147 148 PFIL_LIST_LOCK(); 149 LIST_FOREACH(ph, &V_pfil_head_list, ph_list) 150 if (ph->ph_type == type && ph->ph_un.phu_val == val) 151 break; 152 PFIL_LIST_UNLOCK(); 153 return (ph); 154} 155 156/* 157 * pfil_add_hook() adds a function to the packet filter hook. the 158 * flags are: 159 * PFIL_IN call me on incoming packets 160 * PFIL_OUT call me on outgoing packets 161 * PFIL_ALL call me on all of the above 162 * PFIL_WAITOK OK to call malloc with M_WAITOK. 163 */ 164int 165pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, 166 struct inpcb *), void *arg, int flags, struct pfil_head *ph) 167{ 168 struct packet_filter_hook *pfh1 = NULL; 169 struct packet_filter_hook *pfh2 = NULL; 170 int err; 171 172 if (flags & PFIL_IN) { 173 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 174 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 175 if (pfh1 == NULL) { 176 err = ENOMEM; 177 goto error; 178 } 179 } 180 if (flags & PFIL_OUT) { 181 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 182 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 183 if (pfh2 == NULL) { 184 err = ENOMEM; 185 goto error; 186 } 187 } 188 PFIL_WLOCK(ph); 189 if (flags & PFIL_IN) { 190 pfh1->pfil_func = func; 191 pfh1->pfil_arg = arg; 192 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 193 if (err) 194 goto locked_error; 195 ph->ph_nhooks++; 196 } 197 if (flags & PFIL_OUT) { 198 pfh2->pfil_func = func; 199 pfh2->pfil_arg = arg; 200 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 201 if (err) { 202 if (flags & PFIL_IN) 203 pfil_list_remove(&ph->ph_in, func, arg); 204 goto locked_error; 205 } 206 ph->ph_nhooks++; 207 } 208 PFIL_WUNLOCK(ph); 209 return (0); 210locked_error: 211 PFIL_WUNLOCK(ph); 212error: 213 if (pfh1 != NULL) 214 free(pfh1, M_IFADDR); 215 if (pfh2 != NULL) 216 free(pfh2, M_IFADDR); 217 return (err); 218} 219 220/* 221 * pfil_remove_hook removes a specific function from the packet filter hook 222 * list. 223 */ 224int 225pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, 226 struct inpcb *), void *arg, int flags, struct pfil_head *ph) 227{ 228 int err = 0; 229 230 PFIL_WLOCK(ph); 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 return (err); 243} 244 245static int 246pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 247{ 248 struct packet_filter_hook *pfh; 249 250 /* 251 * First make sure the hook is not already there. 252 */ 253 TAILQ_FOREACH(pfh, list, pfil_link) 254 if (pfh->pfil_func == pfh1->pfil_func && 255 pfh->pfil_arg == pfh1->pfil_arg) 256 return (EEXIST); 257 258 /* 259 * Insert the input list in reverse order of the output list so that 260 * 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 return (0); 267} 268 269/* 270 * pfil_list_remove is an internal function that takes a function off the 271 * specified list. 272 */ 273static int 274pfil_list_remove(pfil_list_t *list, 275 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 276 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 (including the first of 291 * course). 292 */ 293static int 294vnet_pfil_init(const void *unused) 295{ 296 297 LIST_INIT(&V_pfil_head_list); 298 return (0); 299} 300 301/* 302 * Called for the removal of each instance. 303 */ 304static int 305vnet_pfil_uninit(const void *unused) 306{ 307 308 /* XXX should panic if list is not empty */ 309 return (0); 310} 311 312/* Define startup order. */ 313#define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN 314#define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */ 315#define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */ 316 317/* 318 * Starting up. 319 * 320 * VNET_SYSINIT is called for each existing vnet and each new vnet. 321 */ 322VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 323 vnet_pfil_init, NULL); 324 325/* 326 * Closing up shop. These are done in REVERSE ORDER. Not called on reboot. 327 * 328 * VNET_SYSUNINIT is called for each exiting vnet as it exits. 329 */ 330VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER, 331 vnet_pfil_uninit, NULL); 332