1 /* $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $ */ 2 /* $DragonFly: src/sys/net/pfil.c,v 1.3 2004/07/14 08:01:16 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(struct pfil_head *, 45 int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int); 46 47 static int pfil_list_remove(struct pfil_head *, 48 int (*)(void *, struct mbuf **, struct ifnet *, int), void *, int); 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 ph->ph_hashooks = 0; 96 97 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); 98 99 return (0); 100 } 101 102 /* 103 * pfil_head_unregister() removes a pfil_head from the packet filter 104 * hook mechanism. 105 */ 106 int 107 pfil_head_unregister(struct pfil_head *pfh) 108 { 109 110 LIST_REMOVE(pfh, ph_list); 111 return (0); 112 } 113 114 /* 115 * pfil_head_get() returns the pfil_head for a given key/dlt. 116 */ 117 struct pfil_head * 118 pfil_head_get(int type, u_long val) 119 { 120 struct pfil_head *ph; 121 122 for (ph = LIST_FIRST(&pfil_head_list); ph != NULL; 123 ph = LIST_NEXT(ph, ph_list)) { 124 if (ph->ph_type == type && 125 ph->ph_un.phu_val == val) 126 break; 127 } 128 129 return (ph); 130 } 131 132 /* 133 * pfil_add_hook() adds a function to the packet filter hook. the 134 * flags are: 135 * PFIL_IN call me on incoming packets 136 * PFIL_OUT call me on outgoing packets 137 * PFIL_ALL call me on all of the above 138 * PFIL_WAITOK OK to call malloc with M_WAITOK. 139 */ 140 int 141 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 142 void *arg, int flags, struct pfil_head *ph) 143 { 144 int err = 0; 145 146 if (flags & PFIL_IN) { 147 err = pfil_list_add(ph, func, arg, flags & ~PFIL_OUT); 148 if (err) 149 return err; 150 } 151 if (flags & PFIL_OUT) { 152 err = pfil_list_add(ph, func, arg, flags & ~PFIL_IN); 153 if (err) { 154 if (flags & PFIL_IN) 155 pfil_list_remove(ph, func, arg, PFIL_IN); 156 return err; 157 } 158 } 159 return 0; 160 } 161 162 static int 163 pfil_list_add(struct pfil_head *ph, 164 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg, 165 int flags) 166 { 167 struct packet_filter_hook *pfh; 168 pfil_list_t *list; 169 170 list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out; 171 172 /* 173 * First make sure the hook is not already there. 174 */ 175 for (pfh = TAILQ_FIRST(list); pfh != NULL; 176 pfh = TAILQ_NEXT(pfh, pfil_link)) { 177 if (pfh->pfil_func == func && 178 pfh->pfil_arg == arg) 179 return EEXIST; 180 } 181 182 pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR, 183 (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT); 184 if (pfh == NULL) 185 return ENOMEM; 186 187 pfh->pfil_func = func; 188 pfh->pfil_arg = arg; 189 190 /* 191 * insert the input list in reverse order of the output list 192 * so that the same path is followed in or out of the kernel. 193 */ 194 if (flags & PFIL_IN) 195 TAILQ_INSERT_HEAD(list, pfh, pfil_link); 196 else 197 TAILQ_INSERT_TAIL(list, pfh, pfil_link); 198 ph->ph_hashooks = 1; 199 return (0); 200 } 201 202 /* 203 * pfil_remove_hook removes a specific function from the packet filter 204 * hook list. 205 */ 206 int 207 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int), 208 void *arg, int flags, struct pfil_head *ph) 209 { 210 int err = 0; 211 212 if (flags & PFIL_IN) 213 err = pfil_list_remove(ph, func, arg, PFIL_IN); 214 if ((err == 0) && (flags & PFIL_OUT)) 215 err = pfil_list_remove(ph, func, arg, PFIL_OUT); 216 return err; 217 } 218 219 /* 220 * pfil_list_remove is an internal function that takes a function off the 221 * specified list. Clear ph_hashooks if no functions remain on any list. 222 */ 223 static int 224 pfil_list_remove(struct pfil_head *ph, 225 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg, 226 int flags) 227 { 228 struct packet_filter_hook *pfh; 229 pfil_list_t *list; 230 231 list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out; 232 233 for (pfh = TAILQ_FIRST(list); pfh != NULL; 234 pfh = TAILQ_NEXT(pfh, pfil_link)) { 235 if (pfh->pfil_func == func && pfh->pfil_arg == arg) { 236 TAILQ_REMOVE(list, pfh, pfil_link); 237 free(pfh, M_IFADDR); 238 if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out)) 239 ph->ph_hashooks = 0; 240 return 0; 241 } 242 } 243 return ENOENT; 244 } 245