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/rwlock.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 packet_filter_hook *pfh; 70 struct mbuf *m = *mp; 71 int rv = 0; 72 73 PFIL_RLOCK(ph); 74 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0")); 75 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 76 pfh = TAILQ_NEXT(pfh, pfil_link)) { 77 if (pfh->pfil_func != NULL) { 78 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp); 79 if (rv != 0 || m == NULL) 80 break; 81 } 82 } 83 PFIL_RUNLOCK(ph); 84 85 *mp = m; 86 return (rv); 87 } 88 89 /* 90 * pfil_head_register() registers a pfil_head with the packet filter 91 * hook mechanism. 92 */ 93 int 94 pfil_head_register(struct pfil_head *ph) 95 { 96 struct pfil_head *lph; 97 98 PFIL_LIST_LOCK(); 99 LIST_FOREACH(lph, &pfil_head_list, ph_list) 100 if (ph->ph_type == lph->ph_type && 101 ph->ph_un.phu_val == lph->ph_un.phu_val) { 102 PFIL_LIST_UNLOCK(); 103 return EEXIST; 104 } 105 PFIL_LIST_UNLOCK(); 106 107 rw_init(&ph->ph_mtx, "PFil hook read/write mutex"); 108 PFIL_WLOCK(ph); 109 ph->ph_nhooks = 0; 110 111 TAILQ_INIT(&ph->ph_in); 112 TAILQ_INIT(&ph->ph_out); 113 114 PFIL_LIST_LOCK(); 115 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 116 PFIL_LIST_UNLOCK(); 117 118 PFIL_WUNLOCK(ph); 119 120 return (0); 121 } 122 123 /* 124 * pfil_head_unregister() removes a pfil_head from the packet filter 125 * hook mechanism. 126 */ 127 int 128 pfil_head_unregister(struct pfil_head *ph) 129 { 130 struct packet_filter_hook *pfh, *pfnext; 131 132 PFIL_LIST_LOCK(); 133 /* 134 * LIST_REMOVE is safe for unlocked pfil_heads in ph_list. 135 * No need to WLOCK all of them. 136 */ 137 LIST_REMOVE(ph, ph_list); 138 PFIL_LIST_UNLOCK(); 139 140 PFIL_WLOCK(ph); 141 142 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 143 free(pfh, M_IFADDR); 144 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 145 free(pfh, M_IFADDR); 146 rw_destroy(&ph->ph_mtx); 147 148 return (0); 149 } 150 151 /* 152 * pfil_head_get() returns the pfil_head for a given key/dlt. 153 */ 154 struct pfil_head * 155 pfil_head_get(int type, u_long val) 156 { 157 struct pfil_head *ph; 158 159 PFIL_LIST_LOCK(); 160 LIST_FOREACH(ph, &pfil_head_list, ph_list) 161 if (ph->ph_type == type && ph->ph_un.phu_val == val) 162 break; 163 PFIL_LIST_UNLOCK(); 164 165 return (ph); 166 } 167 168 /* 169 * pfil_add_hook() adds a function to the packet filter hook. the 170 * flags are: 171 * PFIL_IN call me on incoming packets 172 * PFIL_OUT call me on outgoing packets 173 * PFIL_ALL call me on all of the above 174 * PFIL_WAITOK OK to call malloc with M_WAITOK. 175 */ 176 int 177 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 178 void *arg, int flags, struct pfil_head *ph) 179 { 180 struct packet_filter_hook *pfh1 = NULL; 181 struct packet_filter_hook *pfh2 = NULL; 182 int err; 183 184 /* Get memory */ 185 if (flags & PFIL_IN) { 186 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 187 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 188 if (pfh1 == NULL) { 189 err = ENOMEM; 190 goto error; 191 } 192 } 193 if (flags & PFIL_OUT) { 194 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 195 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 196 if (pfh2 == NULL) { 197 err = ENOMEM; 198 goto error; 199 } 200 } 201 202 /* Lock */ 203 PFIL_WLOCK(ph); 204 205 /* Add */ 206 if (flags & PFIL_IN) { 207 pfh1->pfil_func = func; 208 pfh1->pfil_arg = arg; 209 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 210 if (err) 211 goto done; 212 ph->ph_nhooks++; 213 } 214 if (flags & PFIL_OUT) { 215 pfh2->pfil_func = func; 216 pfh2->pfil_arg = arg; 217 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 218 if (err) { 219 if (flags & PFIL_IN) 220 pfil_list_remove(&ph->ph_in, func, arg); 221 goto done; 222 } 223 ph->ph_nhooks++; 224 } 225 226 PFIL_WUNLOCK(ph); 227 228 return 0; 229 done: 230 PFIL_WUNLOCK(ph); 231 error: 232 if (pfh1 != NULL) 233 free(pfh1, M_IFADDR); 234 if (pfh2 != NULL) 235 free(pfh2, M_IFADDR); 236 return err; 237 } 238 239 /* 240 * pfil_remove_hook removes a specific function from the packet filter 241 * hook list. 242 */ 243 int 244 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 245 void *arg, int flags, struct pfil_head *ph) 246 { 247 int err = 0; 248 249 PFIL_WLOCK(ph); 250 251 if (flags & PFIL_IN) { 252 err = pfil_list_remove(&ph->ph_in, func, arg); 253 if (err == 0) 254 ph->ph_nhooks--; 255 } 256 if ((err == 0) && (flags & PFIL_OUT)) { 257 err = pfil_list_remove(&ph->ph_out, func, arg); 258 if (err == 0) 259 ph->ph_nhooks--; 260 } 261 PFIL_WUNLOCK(ph); 262 263 return err; 264 } 265 266 static int 267 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 268 { 269 struct packet_filter_hook *pfh; 270 271 /* 272 * First make sure the hook is not already there. 273 */ 274 TAILQ_FOREACH(pfh, list, pfil_link) 275 if (pfh->pfil_func == pfh1->pfil_func && 276 pfh->pfil_arg == pfh1->pfil_arg) 277 return EEXIST; 278 /* 279 * insert the input list in reverse order of the output list 280 * so that the same path is followed in or out of the kernel. 281 */ 282 if (flags & PFIL_IN) 283 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 284 else 285 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 286 287 return 0; 288 } 289 290 /* 291 * pfil_list_remove is an internal function that takes a function off the 292 * specified list. 293 */ 294 static int 295 pfil_list_remove(pfil_list_t *list, 296 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg) 297 { 298 struct packet_filter_hook *pfh; 299 300 TAILQ_FOREACH(pfh, list, pfil_link) 301 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 302 TAILQ_REMOVE(list, pfh, pfil_link); 303 free(pfh, M_IFADDR); 304 return 0; 305 } 306 return ENOENT; 307 } 308