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 PFIL_LIST_UNLOCK(); 107 108 PFIL_LOCK_INIT(ph); 109 PFIL_WLOCK(ph); 110 ph->ph_nhooks = 0; 111 112 TAILQ_INIT(&ph->ph_in); 113 TAILQ_INIT(&ph->ph_out); 114 115 PFIL_LIST_LOCK(); 116 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 117 PFIL_LIST_UNLOCK(); 118 119 PFIL_WUNLOCK(ph); 120 121 return (0); 122 } 123 124 /* 125 * pfil_head_unregister() removes a pfil_head from the packet filter 126 * hook mechanism. 127 */ 128 int 129 pfil_head_unregister(struct pfil_head *ph) 130 { 131 struct packet_filter_hook *pfh, *pfnext; 132 133 PFIL_LIST_LOCK(); 134 /* 135 * LIST_REMOVE is safe for unlocked pfil_heads in ph_list. 136 * No need to WLOCK all of them. 137 */ 138 LIST_REMOVE(ph, ph_list); 139 PFIL_LIST_UNLOCK(); 140 141 PFIL_WLOCK(ph); 142 143 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext) 144 free(pfh, M_IFADDR); 145 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext) 146 free(pfh, M_IFADDR); 147 PFIL_LOCK_DESTROY(ph); 148 149 return (0); 150 } 151 152 /* 153 * pfil_head_get() returns the pfil_head for a given key/dlt. 154 */ 155 struct pfil_head * 156 pfil_head_get(int type, u_long val) 157 { 158 struct pfil_head *ph; 159 160 PFIL_LIST_LOCK(); 161 LIST_FOREACH(ph, &pfil_head_list, ph_list) 162 if (ph->ph_type == type && ph->ph_un.phu_val == val) 163 break; 164 PFIL_LIST_UNLOCK(); 165 166 return (ph); 167 } 168 169 /* 170 * pfil_add_hook() adds a function to the packet filter hook. the 171 * flags are: 172 * PFIL_IN call me on incoming packets 173 * PFIL_OUT call me on outgoing packets 174 * PFIL_ALL call me on all of the above 175 * PFIL_WAITOK OK to call malloc with M_WAITOK. 176 */ 177 int 178 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 179 void *arg, int flags, struct pfil_head *ph) 180 { 181 struct packet_filter_hook *pfh1 = NULL; 182 struct packet_filter_hook *pfh2 = NULL; 183 int err; 184 185 /* Get memory */ 186 if (flags & PFIL_IN) { 187 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 188 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 189 if (pfh1 == NULL) { 190 err = ENOMEM; 191 goto error; 192 } 193 } 194 if (flags & PFIL_OUT) { 195 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1), 196 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 197 if (pfh2 == NULL) { 198 err = ENOMEM; 199 goto error; 200 } 201 } 202 203 /* Lock */ 204 PFIL_WLOCK(ph); 205 206 /* Add */ 207 if (flags & PFIL_IN) { 208 pfh1->pfil_func = func; 209 pfh1->pfil_arg = arg; 210 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT); 211 if (err) 212 goto done; 213 ph->ph_nhooks++; 214 } 215 if (flags & PFIL_OUT) { 216 pfh2->pfil_func = func; 217 pfh2->pfil_arg = arg; 218 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN); 219 if (err) { 220 if (flags & PFIL_IN) 221 pfil_list_remove(&ph->ph_in, func, arg); 222 goto done; 223 } 224 ph->ph_nhooks++; 225 } 226 227 PFIL_WUNLOCK(ph); 228 229 return 0; 230 done: 231 PFIL_WUNLOCK(ph); 232 error: 233 if (pfh1 != NULL) 234 free(pfh1, M_IFADDR); 235 if (pfh2 != NULL) 236 free(pfh2, M_IFADDR); 237 return err; 238 } 239 240 /* 241 * pfil_remove_hook removes a specific function from the packet filter 242 * hook list. 243 */ 244 int 245 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), 246 void *arg, int flags, struct pfil_head *ph) 247 { 248 int err = 0; 249 250 PFIL_WLOCK(ph); 251 252 if (flags & PFIL_IN) { 253 err = pfil_list_remove(&ph->ph_in, func, arg); 254 if (err == 0) 255 ph->ph_nhooks--; 256 } 257 if ((err == 0) && (flags & PFIL_OUT)) { 258 err = pfil_list_remove(&ph->ph_out, func, arg); 259 if (err == 0) 260 ph->ph_nhooks--; 261 } 262 PFIL_WUNLOCK(ph); 263 264 return err; 265 } 266 267 static int 268 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags) 269 { 270 struct packet_filter_hook *pfh; 271 272 /* 273 * First make sure the hook is not already there. 274 */ 275 TAILQ_FOREACH(pfh, list, pfil_link) 276 if (pfh->pfil_func == pfh1->pfil_func && 277 pfh->pfil_arg == pfh1->pfil_arg) 278 return EEXIST; 279 /* 280 * insert the input list in reverse order of the output list 281 * so that the same path is followed in or out of the kernel. 282 */ 283 if (flags & PFIL_IN) 284 TAILQ_INSERT_HEAD(list, pfh1, pfil_link); 285 else 286 TAILQ_INSERT_TAIL(list, pfh1, pfil_link); 287 288 return 0; 289 } 290 291 /* 292 * pfil_list_remove is an internal function that takes a function off the 293 * specified list. 294 */ 295 static int 296 pfil_list_remove(pfil_list_t *list, 297 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg) 298 { 299 struct packet_filter_hook *pfh; 300 301 TAILQ_FOREACH(pfh, list, pfil_link) 302 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 303 TAILQ_REMOVE(list, pfh, pfil_link); 304 free(pfh, M_IFADDR); 305 return 0; 306 } 307 return ENOENT; 308 } 309