FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c
1 /* $FreeBSD: releng/5.3/sys/net/pfil.c 136588 2004-10-16 08:43:07Z cvs2svn $ */
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/malloc.h>
36 #include <sys/socket.h>
37 #include <sys/socketvar.h>
38 #include <sys/systm.h>
39 #include <sys/condvar.h>
40 #include <sys/lock.h>
41 #include <sys/mutex.h>
42 #include <sys/proc.h>
43 #include <sys/queue.h>
44
45 #include <net/if.h>
46 #include <net/pfil.h>
47
48 static struct mtx pfil_global_lock;
49
50 MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", MTX_DEF);
51
52 static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
53
54 static int pfil_list_remove(pfil_list_t *,
55 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *);
56
57 LIST_HEAD(, pfil_head) pfil_head_list =
58 LIST_HEAD_INITIALIZER(&pfil_head_list);
59
60 static __inline void
61 PFIL_RLOCK(struct pfil_head *ph)
62 {
63 mtx_lock(&ph->ph_mtx);
64 ph->ph_busy_count++;
65 mtx_unlock(&ph->ph_mtx);
66 }
67
68 static __inline void
69 PFIL_RUNLOCK(struct pfil_head *ph)
70 {
71 mtx_lock(&ph->ph_mtx);
72 ph->ph_busy_count--;
73 if (ph->ph_busy_count == 0 && ph->ph_want_write)
74 cv_signal(&ph->ph_cv);
75 mtx_unlock(&ph->ph_mtx);
76 }
77
78 static __inline void
79 PFIL_WLOCK(struct pfil_head *ph)
80 {
81 mtx_lock(&ph->ph_mtx);
82 ph->ph_want_write = 1;
83 while (ph->ph_busy_count > 0)
84 cv_wait(&ph->ph_cv, &ph->ph_mtx);
85 }
86
87 static __inline int
88 PFIL_TRY_WLOCK(struct pfil_head *ph)
89 {
90 mtx_lock(&ph->ph_mtx);
91 ph->ph_want_write = 1;
92 if (ph->ph_busy_count > 0) {
93 ph->ph_want_write = 0;
94 mtx_unlock(&ph->ph_mtx);
95 return EBUSY;
96 }
97 return 0;
98 }
99
100 static __inline void
101 PFIL_WUNLOCK(struct pfil_head *ph)
102 {
103 ph->ph_want_write = 0;
104 cv_signal(&ph->ph_cv);
105 mtx_unlock(&ph->ph_mtx);
106 }
107
108 #define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock)
109 #define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock)
110
111 /*
112 * pfil_run_hooks() runs the specified packet filter hooks.
113 */
114 int
115 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
116 int dir, struct inpcb *inp)
117 {
118 struct packet_filter_hook *pfh;
119 struct mbuf *m = *mp;
120 int rv = 0;
121
122 /*
123 * Prevent packet filtering from starving the modification of
124 * the packet filters. We would prefer a reader/writer locking
125 * mechanism with guaranteed ordering, though.
126 */
127 if (ph->ph_busy_count == -1 || ph->ph_want_write) {
128 m_freem(*mp);
129 *mp = NULL;
130 return (ENOBUFS);
131 }
132
133 PFIL_RLOCK(ph);
134 for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
135 pfh = TAILQ_NEXT(pfh, pfil_link)) {
136 if (pfh->pfil_func != NULL) {
137 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp);
138 if (rv != 0 || m == NULL)
139 break;
140 }
141 }
142 PFIL_RUNLOCK(ph);
143
144 *mp = m;
145 return (rv);
146 }
147
148 /*
149 * pfil_head_register() registers a pfil_head with the packet filter
150 * hook mechanism.
151 */
152 int
153 pfil_head_register(struct pfil_head *ph)
154 {
155 struct pfil_head *lph;
156
157 PFIL_LIST_LOCK();
158 LIST_FOREACH(lph, &pfil_head_list, ph_list)
159 if (ph->ph_type == lph->ph_type &&
160 ph->ph_un.phu_val == lph->ph_un.phu_val) {
161 PFIL_LIST_UNLOCK();
162 return EEXIST;
163 }
164 PFIL_LIST_UNLOCK();
165
166 if (mtx_initialized(&ph->ph_mtx)) { /* should not happen */
167 KASSERT((0), ("%s: allready initialized!", __func__));
168 return EBUSY;
169 } else {
170 ph->ph_busy_count = -1;
171 ph->ph_want_write = 1;
172 mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF);
173 cv_init(&ph->ph_cv, "pfil_head_cv");
174 mtx_lock(&ph->ph_mtx); /* XXX: race? */
175 }
176
177 TAILQ_INIT(&ph->ph_in);
178 TAILQ_INIT(&ph->ph_out);
179
180 PFIL_LIST_LOCK();
181 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
182 PFIL_LIST_UNLOCK();
183
184 PFIL_WUNLOCK(ph);
185
186 return (0);
187 }
188
189 /*
190 * pfil_head_unregister() removes a pfil_head from the packet filter
191 * hook mechanism.
192 */
193 int
194 pfil_head_unregister(struct pfil_head *ph)
195 {
196 struct packet_filter_hook *pfh, *pfnext;
197
198 PFIL_LIST_LOCK();
199 /*
200 * LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
201 * No need to WLOCK all of them.
202 */
203 LIST_REMOVE(ph, ph_list);
204 PFIL_LIST_UNLOCK();
205
206 PFIL_WLOCK(ph); /* XXX: may sleep (cv_wait)! */
207
208 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
209 free(pfh, M_IFADDR);
210 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
211 free(pfh, M_IFADDR);
212 cv_destroy(&ph->ph_cv);
213 mtx_destroy(&ph->ph_mtx);
214
215 return (0);
216 }
217
218 /*
219 * pfil_head_get() returns the pfil_head for a given key/dlt.
220 */
221 struct pfil_head *
222 pfil_head_get(int type, u_long val)
223 {
224 struct pfil_head *ph;
225
226 PFIL_LIST_LOCK();
227 LIST_FOREACH(ph, &pfil_head_list, ph_list)
228 if (ph->ph_type == type && ph->ph_un.phu_val == val)
229 break;
230 PFIL_LIST_UNLOCK();
231
232 return (ph);
233 }
234
235 /*
236 * pfil_add_hook() adds a function to the packet filter hook. the
237 * flags are:
238 * PFIL_IN call me on incoming packets
239 * PFIL_OUT call me on outgoing packets
240 * PFIL_ALL call me on all of the above
241 * PFIL_WAITOK OK to call malloc with M_WAITOK.
242 */
243 int
244 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
245 void *arg, int flags, struct pfil_head *ph)
246 {
247 struct packet_filter_hook *pfh1 = NULL;
248 struct packet_filter_hook *pfh2 = NULL;
249 int err;
250
251 /* Get memory */
252 if (flags & PFIL_IN) {
253 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
254 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
255 if (pfh1 == NULL) {
256 err = ENOMEM;
257 goto error;
258 }
259 }
260 if (flags & PFIL_OUT) {
261 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
262 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
263 if (pfh2 == NULL) {
264 err = ENOMEM;
265 goto error;
266 }
267 }
268
269 /* Lock */
270 if (flags & PFIL_WAITOK)
271 PFIL_WLOCK(ph);
272 else {
273 err = PFIL_TRY_WLOCK(ph);
274 if (err)
275 goto error;
276 }
277
278 /* Add */
279 if (flags & PFIL_IN) {
280 pfh1->pfil_func = func;
281 pfh1->pfil_arg = arg;
282 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
283 if (err)
284 goto done;
285 }
286 if (flags & PFIL_OUT) {
287 pfh2->pfil_func = func;
288 pfh2->pfil_arg = arg;
289 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
290 if (err) {
291 if (flags & PFIL_IN)
292 pfil_list_remove(&ph->ph_in, func, arg);
293 goto done;
294 }
295 }
296
297 ph->ph_busy_count = 0;
298 PFIL_WUNLOCK(ph);
299
300 return 0;
301 done:
302 PFIL_WUNLOCK(ph);
303 error:
304 if (pfh1 != NULL)
305 free(pfh1, M_IFADDR);
306 if (pfh2 != NULL)
307 free(pfh2, M_IFADDR);
308 return err;
309 }
310
311 /*
312 * pfil_remove_hook removes a specific function from the packet filter
313 * hook list.
314 */
315 int
316 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
317 void *arg, int flags, struct pfil_head *ph)
318 {
319 int err = 0;
320
321 if (flags & PFIL_WAITOK)
322 PFIL_WLOCK(ph);
323 else {
324 err = PFIL_TRY_WLOCK(ph);
325 if (err)
326 return err;
327 }
328
329 if (flags & PFIL_IN)
330 err = pfil_list_remove(&ph->ph_in, func, arg);
331 if ((err == 0) && (flags & PFIL_OUT))
332 err = pfil_list_remove(&ph->ph_out, func, arg);
333
334 if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
335 ph->ph_busy_count = -1;
336
337 PFIL_WUNLOCK(ph);
338
339 return err;
340 }
341
342 static int
343 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
344 {
345 struct packet_filter_hook *pfh;
346
347 /*
348 * First make sure the hook is not already there.
349 */
350 TAILQ_FOREACH(pfh, list, pfil_link)
351 if (pfh->pfil_func == pfh1->pfil_func &&
352 pfh->pfil_arg == pfh1->pfil_arg)
353 return EEXIST;
354 /*
355 * insert the input list in reverse order of the output list
356 * so that the same path is followed in or out of the kernel.
357 */
358 if (flags & PFIL_IN)
359 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
360 else
361 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
362
363 return 0;
364 }
365
366 /*
367 * pfil_list_remove is an internal function that takes a function off the
368 * specified list.
369 */
370 static int
371 pfil_list_remove(pfil_list_t *list,
372 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg)
373 {
374 struct packet_filter_hook *pfh;
375
376 TAILQ_FOREACH(pfh, list, pfil_link)
377 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
378 TAILQ_REMOVE(list, pfh, pfil_link);
379 free(pfh, M_IFADDR);
380 return 0;
381 }
382 return ENOENT;
383 }
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