1 /* $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $ */ 2 /* $DragonFly: src/sys/net/pfil.c,v 1.1 2003/12/02 09:18:17 asmodai 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/errno.h> 34 #include <sys/malloc.h> 35 #include <sys/socket.h> 36 #include <sys/socketvar.h> 37 #include <sys/systm.h> 38 #include <sys/proc.h> 39 #include <sys/queue.h> 40 41 #include <net/if.h> 42 #include <net/pfil.h> 43 44 static int pfil_list_add(pfil_list_t *, 45 int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int); 46 47 static int pfil_list_remove(pfil_list_t *, 48 int (*)(void *, struct mbuf **, struct ifnet *, int), void *); 49 50 LIST_HEAD(, pfil_head) pfil_head_list = 51 LIST_HEAD_INITIALIZER(&pfil_head_list); 52 53 /* 54 * pfil_run_hooks() runs the specified packet filter hooks. 55 */ 56 int 57 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp, 58 int dir) 59 { 60 struct packet_filter_hook *pfh; 61 struct mbuf *m = *mp; 62 int rv = 0; 63 64 for (pfh = pfil_hook_get(dir, ph); pfh != NULL; 65 pfh = TAILQ_NEXT(pfh, pfil_link)) { 66 if (pfh->pfil_func != NULL) { 67 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir); 68 if (rv != 0 || m == NULL) 69 break; 70 } 71 } 72 73 *mp = m; 74 return (rv); 75 } 76 77 /* 78 * pfil_head_register() registers a pfil_head with the packet filter 79 * hook mechanism. 80 */ 81 int 82 pfil_head_register(struct pfil_head *ph) 83 { 84 struct pfil_head *lph; 85 86 for (lph = LIST_FIRST(&pfil_head_list); lph != NULL; 87 lph = LIST_NEXT(lph, ph_list)) { 88 if (ph->ph_type == lph->ph_type && 89 ph->ph_un.phu_val == lph->ph_un.phu_val) 90 return EEXIST; 91 } 92 93 TAILQ_INIT(&ph->ph_in); 94 TAILQ_INIT(&ph->ph_out); 95 96 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 97 98 return (0); 99 } 100 101 /* 102 * pfil_head_unregister() removes a pfil_head from the packet filter 103 * hook mechanism. 104 */ 105 int 106 pfil_head_unregister(struct pfil_head *pfh) 107 { 108 109 LIST_REMOVE(pfh, ph_list); 110 return (0); 111 } 112 113 /* 114 * pfil_head_get() returns the pfil_head for a given key/dlt. 115 */ 116 struct pfil_head * 117 pfil_head_get(int type, u_long val) 118 { 119 struct pfil_head *ph; 120 121 for (ph = LIST_FIRST(&pfil_head_list); ph != NULL; 122 ph = LIST_NEXT(ph, ph_list)) { 123 if (ph->ph_type == type && 124 ph->ph_un.phu_val == val) 125 break; 126 } 127 128 return (ph); 129 } 130 131 /* 132 * pfil_add_hook() adds a function to the packet filter hook. the 133 * flags are: 134 * PFIL_IN call me on incoming packets 135 * PFIL_OUT call me on outgoing packets 136 * PFIL_ALL call me on all of the above 137 * PFIL_WAITOK OK to call malloc with M_WAITOK. 138 */ 139 int 140 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 141 void *arg, int flags, struct pfil_head *ph) 142 { 143 int err = 0; 144 145 if (flags & PFIL_IN) { 146 err = pfil_list_add(&ph->ph_in, func, arg, flags & ~PFIL_OUT); 147 if (err) 148 return err; 149 } 150 if (flags & PFIL_OUT) { 151 err = pfil_list_add(&ph->ph_out, func, arg, flags & ~PFIL_IN); 152 if (err) { 153 if (flags & PFIL_IN) 154 pfil_list_remove(&ph->ph_in, func, arg); 155 return err; 156 } 157 } 158 return 0; 159 } 160 161 static int 162 pfil_list_add(pfil_list_t *list, 163 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg, 164 int flags) 165 { 166 struct packet_filter_hook *pfh; 167 168 /* 169 * First make sure the hook is not already there. 170 */ 171 for (pfh = TAILQ_FIRST(list); pfh != NULL; 172 pfh = TAILQ_NEXT(pfh, pfil_link)) { 173 if (pfh->pfil_func == func && 174 pfh->pfil_arg == arg) 175 return EEXIST; 176 } 177 178 pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR, 179 (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 180 if (pfh == NULL) 181 return ENOMEM; 182 183 pfh->pfil_func = func; 184 pfh->pfil_arg = arg; 185 186 /* 187 * insert the input list in reverse order of the output list 188 * so that the same path is followed in or out of the kernel. 189 */ 190 if (flags & PFIL_IN) 191 TAILQ_INSERT_HEAD(list, pfh, pfil_link); 192 else 193 TAILQ_INSERT_TAIL(list, pfh, pfil_link); 194 195 return 0; 196 } 197 198 /* 199 * pfil_remove_hook removes a specific function from the packet filter 200 * hook list. 201 */ 202 int 203 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 204 void *arg, int flags, struct pfil_head *ph) 205 { 206 int err = 0; 207 208 if (flags & PFIL_IN) 209 err = pfil_list_remove(&ph->ph_in, func, arg); 210 if ((err == 0) && (flags & PFIL_OUT)) 211 err = pfil_list_remove(&ph->ph_out, func, arg); 212 return err; 213 } 214 215 /* 216 * pfil_list_remove is an internal function that takes a function off the 217 * specified list. 218 */ 219 static int 220 pfil_list_remove(pfil_list_t *list, 221 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg) 222 { 223 struct packet_filter_hook *pfh; 224 225 for (pfh = TAILQ_FIRST(list); pfh != NULL; 226 pfh = TAILQ_NEXT(pfh, pfil_link)) { 227 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 228 TAILQ_REMOVE(list, pfh, pfil_link); 229 free(pfh, M_IFADDR); 230 return 0; 231 } 232 } 233 return ENOENT; 234 } 235