FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c
1 /* $FreeBSD: releng/5.2/sys/net/pfil.c 120386 2003-09-23 17:54:04Z sam $ */
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), 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 mtx_unlock(&ph->ph_mtx);
105 cv_signal(&ph->ph_cv);
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)
117 {
118 struct packet_filter_hook *pfh;
119 struct mbuf *m = *mp;
120 int rv = 0;
121
122 if (ph->ph_busy_count == -1 || ph->ph_want_write)
123 return (0);
124
125 PFIL_RLOCK(ph);
126 for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
127 pfh = TAILQ_NEXT(pfh, pfil_link)) {
128 if (pfh->pfil_func != NULL) {
129 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir);
130 if (rv != 0 || m == NULL)
131 break;
132 }
133 }
134 PFIL_RUNLOCK(ph);
135
136 *mp = m;
137 return (rv);
138 }
139
140 /*
141 * pfil_head_register() registers a pfil_head with the packet filter
142 * hook mechanism.
143 */
144 int
145 pfil_head_register(struct pfil_head *ph)
146 {
147 struct pfil_head *lph;
148
149 PFIL_LIST_LOCK();
150 LIST_FOREACH(lph, &pfil_head_list, ph_list)
151 if (ph->ph_type == lph->ph_type &&
152 ph->ph_un.phu_val == lph->ph_un.phu_val) {
153 PFIL_LIST_UNLOCK();
154 return EEXIST;
155 }
156 PFIL_LIST_UNLOCK();
157
158 if (mtx_initialized(&ph->ph_mtx)) { /* should not happen */
159 KASSERT((0), ("%s: allready initialized!", __func__));
160 return EBUSY;
161 } else {
162 ph->ph_busy_count = -1;
163 ph->ph_want_write = 1;
164 mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF);
165 cv_init(&ph->ph_cv, "pfil_head_cv");
166 mtx_lock(&ph->ph_mtx); /* XXX: race? */
167 }
168
169 TAILQ_INIT(&ph->ph_in);
170 TAILQ_INIT(&ph->ph_out);
171
172 PFIL_LIST_LOCK();
173 LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
174 PFIL_LIST_UNLOCK();
175
176 PFIL_WUNLOCK(ph);
177
178 return (0);
179 }
180
181 /*
182 * pfil_head_unregister() removes a pfil_head from the packet filter
183 * hook mechanism.
184 */
185 int
186 pfil_head_unregister(struct pfil_head *ph)
187 {
188 struct packet_filter_hook *pfh, *pfnext;
189
190 PFIL_LIST_LOCK();
191 /*
192 * LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
193 * No need to WLOCK all of them.
194 */
195 LIST_REMOVE(ph, ph_list);
196 PFIL_LIST_UNLOCK();
197
198 PFIL_WLOCK(ph); /* XXX: may sleep (cv_wait)! */
199
200 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
201 free(pfh, M_IFADDR);
202 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
203 free(pfh, M_IFADDR);
204 cv_destroy(&ph->ph_cv);
205 mtx_destroy(&ph->ph_mtx);
206
207 return (0);
208 }
209
210 /*
211 * pfil_head_get() returns the pfil_head for a given key/dlt.
212 */
213 struct pfil_head *
214 pfil_head_get(int type, u_long val)
215 {
216 struct pfil_head *ph;
217
218 PFIL_LIST_LOCK();
219 LIST_FOREACH(ph, &pfil_head_list, ph_list)
220 if (ph->ph_type == type && ph->ph_un.phu_val == val)
221 break;
222 PFIL_LIST_UNLOCK();
223
224 return (ph);
225 }
226
227 /*
228 * pfil_add_hook() adds a function to the packet filter hook. the
229 * flags are:
230 * PFIL_IN call me on incoming packets
231 * PFIL_OUT call me on outgoing packets
232 * PFIL_ALL call me on all of the above
233 * PFIL_WAITOK OK to call malloc with M_WAITOK.
234 */
235 int
236 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
237 void *arg, int flags, struct pfil_head *ph)
238 {
239 struct packet_filter_hook *pfh1 = NULL;
240 struct packet_filter_hook *pfh2 = NULL;
241 int err;
242
243 /* Get memory */
244 if (flags & PFIL_IN) {
245 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
246 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
247 if (pfh1 == NULL) {
248 err = ENOMEM;
249 goto error;
250 }
251 }
252 if (flags & PFIL_OUT) {
253 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
254 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
255 if (pfh2 == NULL) {
256 err = ENOMEM;
257 goto error;
258 }
259 }
260
261 /* Lock */
262 if (flags & PFIL_WAITOK)
263 PFIL_WLOCK(ph);
264 else {
265 err = PFIL_TRY_WLOCK(ph);
266 if (err)
267 goto error;
268 }
269
270 /* Add */
271 if (flags & PFIL_IN) {
272 pfh1->pfil_func = func;
273 pfh1->pfil_arg = arg;
274 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
275 if (err)
276 goto done;
277 }
278 if (flags & PFIL_OUT) {
279 pfh2->pfil_func = func;
280 pfh2->pfil_arg = arg;
281 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
282 if (err) {
283 if (flags & PFIL_IN)
284 pfil_list_remove(&ph->ph_in, func, arg);
285 goto done;
286 }
287 }
288
289 ph->ph_busy_count = 0;
290 PFIL_WUNLOCK(ph);
291
292 return 0;
293 done:
294 PFIL_WUNLOCK(ph);
295 error:
296 if (pfh1 != NULL)
297 free(pfh1, M_IFADDR);
298 if (pfh2 != NULL)
299 free(pfh2, M_IFADDR);
300 return err;
301 }
302
303 /*
304 * pfil_remove_hook removes a specific function from the packet filter
305 * hook list.
306 */
307 int
308 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int),
309 void *arg, int flags, struct pfil_head *ph)
310 {
311 int err = 0;
312
313 if (flags & PFIL_WAITOK)
314 PFIL_WLOCK(ph);
315 else {
316 err = PFIL_TRY_WLOCK(ph);
317 if (err)
318 return err;
319 }
320
321 if (flags & PFIL_IN)
322 err = pfil_list_remove(&ph->ph_in, func, arg);
323 if ((err == 0) && (flags & PFIL_OUT))
324 err = pfil_list_remove(&ph->ph_out, func, arg);
325
326 if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
327 ph->ph_busy_count = -1;
328
329 PFIL_WUNLOCK(ph);
330
331 return err;
332 }
333
334 static int
335 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
336 {
337 struct packet_filter_hook *pfh;
338
339 /*
340 * First make sure the hook is not already there.
341 */
342 TAILQ_FOREACH(pfh, list, pfil_link)
343 if (pfh->pfil_func == pfh1->pfil_func &&
344 pfh->pfil_arg == pfh1->pfil_arg)
345 return EEXIST;
346 /*
347 * insert the input list in reverse order of the output list
348 * so that the same path is followed in or out of the kernel.
349 */
350 if (flags & PFIL_IN)
351 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
352 else
353 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
354
355 return 0;
356 }
357
358 /*
359 * pfil_list_remove is an internal function that takes a function off the
360 * specified list.
361 */
362 static int
363 pfil_list_remove(pfil_list_t *list,
364 int (*func)(void *, struct mbuf **, struct ifnet *, int), void *arg)
365 {
366 struct packet_filter_hook *pfh;
367
368 TAILQ_FOREACH(pfh, list, pfil_link)
369 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
370 TAILQ_REMOVE(list, pfh, pfil_link);
371 free(pfh, M_IFADDR);
372 return 0;
373 }
374 return ENOENT;
375 }
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