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/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 50 static struct mtx pfil_global_lock; 51 52 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", MTX_DEF); 53 54 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int); 55 56 static int pfil_list_remove(pfil_list_t *, 57 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *); 58 59 LIST_HEAD(, pfil_head) pfil_head_list = 60 LIST_HEAD_INITIALIZER(&pfil_head_list); 61 62 /* 63 * pfil_run_hooks() runs the specified packet filter hooks. 64 */ 65 int 66 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 67 int dir, struct inpcb *inp) 68 { 69 struct rm_priotracker rmpt; 70 struct packet_filter_hook *pfh; 71 struct mbuf *m = *mp; 72 int rv = 0; 73 74 PFIL_RLOCK(ph, &rmpt); 75 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0")); 76 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 77 pfh = TAILQ_NEXT(pfh, pfil_link)) { 78 if (pfh->pfil_func != NULL) { 79 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp); 80 if (rv != 0 || m == NULL) 81 break; 82 } 83 } 84 PFIL_RUNLOCK(ph, &rmpt); 85 86 *mp = m; 87 return (rv); 88 } 89 90 /* 91 * pfil_head_register() registers a pfil_head with the packet filter 92 * hook mechanism. 93 */ 94 int 95 pfil_head_register(struct pfil_head *ph) 96 { 97 struct pfil_head *lph; 98 99 PFIL_LIST_LOCK(); 100 LIST_FOREACH(lph, &pfil_head_list, ph_list) { 101 if (ph->ph_type == lph->ph_type && 102 ph->ph_un.phu_val == lph->ph_un.phu_val) { 103 PFIL_LIST_UNLOCK(); 104 return EEXIST; 105 } 106 } 107 PFIL_LOCK_INIT(ph); 108 ph->ph_nhooks = 0; 109 TAILQ_INIT(&ph->ph_in); 110 TAILQ_INIT(&ph->ph_out); 111 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 112 PFIL_LIST_UNLOCK(); 113 return (0); 114 } 115 116 /* 117 * pfil_head_unregister() removes a pfil_head from the packet filter hook 118 * mechanism. The producer of the hook promises that all outstanding 119 * invocations of the hook have completed before it unregisters the hook. 120 */ 121 int 122 pfil_head_unregister(struct pfil_head *ph) 123 { 124 struct packet_filter_hook *pfh, *pfnext; 125 126 PFIL_LIST_LOCK(); 127 LIST_REMOVE(ph, ph_list); 128 PFIL_LIST_UNLOCK(); 129 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 130 free(pfh, M_IFADDR); 131 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 132 free(pfh, M_IFADDR); 133 PFIL_LOCK_DESTROY(ph); 134 return (0); 135 } 136 137 /* 138 * pfil_head_get() returns the pfil_head for a given key/dlt. 139 */ 140 struct pfil_head * 141 pfil_head_get(int type, u_long val) 142 { 143 struct pfil_head *ph; 144 145 PFIL_LIST_LOCK(); 146 LIST_FOREACH(ph, &pfil_head_list, ph_list) 147 if (ph->ph_type == type && ph->ph_un.phu_val == val) 148 break; 149 PFIL_LIST_UNLOCK(); 150 151 return (ph); 152 } 153 154 /* 155 * pfil_add_hook() adds a function to the packet filter hook. the 156 * flags are: 157 * PFIL_IN call me on incoming packets 158 * PFIL_OUT call me on outgoing packets 159 * PFIL_ALL call me on all of the above 160 * PFIL_WAITOK OK to call malloc with M_WAITOK. 161 */ 162 int 163 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, 164 struct inpcb *), void *arg, int flags, struct pfil_head *ph) 165 { 166 struct packet_filter_hook *pfh1 = NULL; 167 struct packet_filter_hook *pfh2 = NULL; 168 int err; 169 170 if (flags & PFIL_IN) { 171 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 172 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 173 if (pfh1 == NULL) { 174 err = ENOMEM; 175 goto error; 176 } 177 } 178 if (flags & PFIL_OUT) { 179 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 180 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 181 if (pfh2 == NULL) { 182 err = ENOMEM; 183 goto error; 184 } 185 } 186 PFIL_WLOCK(ph); 187 if (flags & PFIL_IN) { 188 pfh1->pfil_func = func; 189 pfh1->pfil_arg = arg; 190 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 191 if (err) 192 goto locked_error; 193 ph->ph_nhooks++; 194 } 195 if (flags & PFIL_OUT) { 196 pfh2->pfil_func = func; 197 pfh2->pfil_arg = arg; 198 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 199 if (err) { 200 if (flags & PFIL_IN) 201 pfil_list_remove(&ph->ph_in, func, arg); 202 goto locked_error; 203 } 204 ph->ph_nhooks++; 205 } 206 PFIL_WUNLOCK(ph); 207 return 0; 208 locked_error: 209 PFIL_WUNLOCK(ph); 210 error: 211 if (pfh1 != NULL) 212 free(pfh1, M_IFADDR); 213 if (pfh2 != NULL) 214 free(pfh2, M_IFADDR); 215 return err; 216 } 217 218 /* 219 * pfil_remove_hook removes a specific function from the packet filter 220 * hook list. 221 */ 222 int 223 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 224 void *arg, int flags, struct pfil_head *ph) 225 { 226 int err = 0; 227 228 PFIL_WLOCK(ph); 229 230 if (flags & PFIL_IN) { 231 err = pfil_list_remove(&ph->ph_in, func, arg); 232 if (err == 0) 233 ph->ph_nhooks--; 234 } 235 if ((err == 0) && (flags & PFIL_OUT)) { 236 err = pfil_list_remove(&ph->ph_out, func, arg); 237 if (err == 0) 238 ph->ph_nhooks--; 239 } 240 PFIL_WUNLOCK(ph); 241 242 return err; 243 } 244 245 static int 246 pfil_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 * insert the input list in reverse order of the output list 259 * so that the same path is followed in or out of the kernel. 260 */ 261 if (flags & PFIL_IN) 262 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 263 else 264 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 265 266 return 0; 267 } 268 269 /* 270 * pfil_list_remove is an internal function that takes a function off the 271 * specified list. 272 */ 273 static int 274 pfil_list_remove(pfil_list_t *list, 275 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg) 276 { 277 struct packet_filter_hook *pfh; 278 279 TAILQ_FOREACH(pfh, list, pfil_link) 280 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 281 TAILQ_REMOVE(list, pfh, pfil_link); 282 free(pfh, M_IFADDR); 283 return 0; 284 } 285 return ENOENT; 286 } 287