FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c
1 /* $FreeBSD: releng/7.4/sys/net/pfil.c 155201 2006-02-02 03:13:16Z csjp $ */
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 }
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