xref: /netbsd/sys/net/pfil.c (revision 6550d01e)
1 /*	$NetBSD: pfil.c,v 1.27 2008/06/23 03:13:12 dyoung Exp $	*/
2 
3 /*
4  * Copyright (c) 1996 Matthew R. Green
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: pfil.c,v 1.27 2008/06/23 03:13:12 dyoung Exp $");
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 = NULL;
62 	int rv = 0;
63 
64 	if ((dir & PFIL_ALL) && mp)
65 		m = *mp;
66 	for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
67 	     pfh = TAILQ_NEXT(pfh, pfil_link)) {
68 		if (pfh->pfil_func != NULL) {
69 			if (pfh->pfil_flags & PFIL_ALL) {
70 				rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp,
71 				    dir);
72 				if (rv != 0 || m == NULL)
73 					break;
74 			} else {
75 				rv = (*pfh->pfil_func)(pfh->pfil_arg, mp, ifp,
76 				    dir);
77 				if (rv != 0)
78 					break;
79 			}
80 		}
81 	}
82 
83 	if ((dir & PFIL_ALL) && mp)
84 		*mp = m;
85 	return (rv);
86 }
87 
88 /*
89  * pfil_head_register() registers a pfil_head with the packet filter
90  * hook mechanism.
91  */
92 int
93 pfil_head_register(struct pfil_head *ph)
94 {
95 	struct pfil_head *lph;
96 
97 	LIST_FOREACH(lph, &pfil_head_list, ph_list) {
98 		if (ph->ph_type == lph->ph_type &&
99 		    ph->ph_un.phu_val == lph->ph_un.phu_val)
100 			return EEXIST;
101 	}
102 
103 	TAILQ_INIT(&ph->ph_in);
104 	TAILQ_INIT(&ph->ph_out);
105 	TAILQ_INIT(&ph->ph_ifaddr);
106 	TAILQ_INIT(&ph->ph_ifnetevent);
107 
108 	LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
109 
110 	return (0);
111 }
112 
113 /*
114  * pfil_head_unregister() removes a pfil_head from the packet filter
115  * hook mechanism.
116  */
117 int
118 pfil_head_unregister(struct pfil_head *pfh)
119 {
120 
121 	LIST_REMOVE(pfh, ph_list);
122 	return (0);
123 }
124 
125 /*
126  * pfil_head_get() returns the pfil_head for a given key/dlt.
127  */
128 struct pfil_head *
129 pfil_head_get(int type, u_long val)
130 {
131 	struct pfil_head *ph;
132 
133 	LIST_FOREACH(ph, &pfil_head_list, ph_list) {
134 		if (ph->ph_type == type && ph->ph_un.phu_val == val)
135 			break;
136 	}
137 
138 	return (ph);
139 }
140 
141 /*
142  * pfil_add_hook() adds a function to the packet filter hook.  the
143  * flags are:
144  *	PFIL_IN		call me on incoming packets
145  *	PFIL_OUT	call me on outgoing packets
146  *	PFIL_ALL	call me on all of the above
147  *	PFIL_IFADDR  	call me on interface reconfig (mbuf ** is ioctl #)
148  *	PFIL_IFNET  	call me on interface attach/detach
149  *			(mbuf ** is PFIL_IFNET_*)
150  *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
151  */
152 int
153 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
154     void *arg, int flags, struct pfil_head *ph)
155 {
156 	int err = 0;
157 
158 	if (flags & PFIL_IN) {
159 		err = pfil_list_add(&ph->ph_in, func, arg, flags & ~PFIL_OUT);
160 		if (err)
161 			return err;
162 	}
163 	if (flags & PFIL_OUT) {
164 		err = pfil_list_add(&ph->ph_out, func, arg, flags & ~PFIL_IN);
165 		if (err) {
166 			if (flags & PFIL_IN)
167 				pfil_list_remove(&ph->ph_in, func, arg);
168 			return err;
169 		}
170 	}
171 	if (flags & PFIL_IFADDR) {
172 		err = pfil_list_add(&ph->ph_ifaddr, func, arg, flags);
173 		if (err) {
174 			if (flags & PFIL_IN)
175 				pfil_list_remove(&ph->ph_in, func, arg);
176 			if (flags & PFIL_OUT)
177 				pfil_list_remove(&ph->ph_out, func, arg);
178 			return err;
179 		}
180 	}
181 	if (flags & PFIL_IFNET) {
182 		err = pfil_list_add(&ph->ph_ifnetevent, func, arg, flags);
183 		if (err) {
184 			if (flags & PFIL_IN)
185 				pfil_list_remove(&ph->ph_in, func, arg);
186 			if (flags & PFIL_OUT)
187 				pfil_list_remove(&ph->ph_out, func, arg);
188 			if (flags & PFIL_IFADDR)
189 				pfil_list_remove(&ph->ph_ifaddr, func, arg);
190 			return err;
191 		}
192 	}
193 	return 0;
194 }
195 
196 static int
197 pfil_list_add(pfil_list_t *list,
198     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg,
199     int flags)
200 {
201 	struct packet_filter_hook *pfh;
202 
203 	/*
204 	 * First make sure the hook is not already there.
205 	 */
206 	TAILQ_FOREACH(pfh, list, pfil_link) {
207 		if (pfh->pfil_func == func && pfh->pfil_arg == arg)
208 			return EEXIST;
209 	}
210 
211 	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
212 	    (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
213 	if (pfh == NULL)
214 		return ENOMEM;
215 
216 	pfh->pfil_func = func;
217 	pfh->pfil_arg  = arg;
218 	pfh->pfil_flags = flags;
219 
220 	/*
221 	 * insert the input list in reverse order of the output list
222 	 * so that the same path is followed in or out of the kernel.
223 	 */
224 	if (flags & PFIL_IN)
225 		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
226 	else
227 		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
228 
229 	return 0;
230 }
231 
232 /*
233  * pfil_remove_hook removes a specific function from the packet filter
234  * hook list.
235  */
236 int
237 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
238     void *arg, int flags, struct pfil_head *ph)
239 {
240 	int err = 0;
241 
242 	if (flags & PFIL_IN)
243 		err = pfil_list_remove(&ph->ph_in, func, arg);
244 	if ((err == 0) && (flags & PFIL_OUT))
245 		err = pfil_list_remove(&ph->ph_out, func, arg);
246 	if ((err == 0) && (flags & PFIL_IFADDR))
247 		err = pfil_list_remove(&ph->ph_ifaddr, func, arg);
248 	if ((err == 0) && (flags & PFIL_IFNET))
249 		err = pfil_list_remove(&ph->ph_ifnetevent, func, arg);
250 	return err;
251 }
252 
253 /*
254  * pfil_list_remove is an internal function that takes a function off the
255  * specified list.
256  */
257 static int
258 pfil_list_remove(pfil_list_t *list,
259     int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
260 {
261 	struct packet_filter_hook *pfh;
262 
263 	TAILQ_FOREACH(pfh, list, pfil_link) {
264 		if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
265 			TAILQ_REMOVE(list, pfh, pfil_link);
266 			free(pfh, M_IFADDR);
267 			return 0;
268 		}
269 	}
270 	return ENOENT;
271 }
272