FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c
1 /* $FreeBSD: releng/10.3/sys/net/pfil.c 254774 2013-08-24 11:24:15Z andre $ */
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/rmlock.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",
53 MTX_DEF);
54
55 static struct packet_filter_hook *pfil_chain_get(int, struct pfil_head *);
56 static int pfil_chain_add(pfil_chain_t *, struct packet_filter_hook *, int);
57 static int pfil_chain_remove(pfil_chain_t *, pfil_func_t, void *);
58
59 LIST_HEAD(pfilheadhead, pfil_head);
60 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
61 #define V_pfil_head_list VNET(pfil_head_list)
62 VNET_DEFINE(struct rmlock, pfil_lock);
63 #define V_pfil_lock VNET(pfil_lock)
64
65 /*
66 * pfil_run_hooks() runs the specified packet filter hook chain.
67 */
68 int
69 pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
70 int dir, struct inpcb *inp)
71 {
72 struct rm_priotracker rmpt;
73 struct packet_filter_hook *pfh;
74 struct mbuf *m = *mp;
75 int rv = 0;
76
77 PFIL_RLOCK(ph, &rmpt);
78 KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
79 for (pfh = pfil_chain_get(dir, ph); pfh != NULL;
80 pfh = TAILQ_NEXT(pfh, pfil_chain)) {
81 if (pfh->pfil_func != NULL) {
82 rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir,
83 inp);
84 if (rv != 0 || m == NULL)
85 break;
86 }
87 }
88 PFIL_RUNLOCK(ph, &rmpt);
89 *mp = m;
90 return (rv);
91 }
92
93 static struct packet_filter_hook *
94 pfil_chain_get(int dir, struct pfil_head *ph)
95 {
96
97 if (dir == PFIL_IN)
98 return (TAILQ_FIRST(&ph->ph_in));
99 else if (dir == PFIL_OUT)
100 return (TAILQ_FIRST(&ph->ph_out));
101 else
102 return (NULL);
103 }
104
105 /*
106 * pfil_try_rlock() acquires rm reader lock for specified head
107 * if this is immediately possible.
108 */
109 int
110 pfil_try_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
111 {
112
113 return (PFIL_TRY_RLOCK(ph, tracker));
114 }
115
116 /*
117 * pfil_rlock() acquires rm reader lock for specified head.
118 */
119 void
120 pfil_rlock(struct pfil_head *ph, struct rm_priotracker *tracker)
121 {
122
123 PFIL_RLOCK(ph, tracker);
124 }
125
126 /*
127 * pfil_runlock() releases reader lock for specified head.
128 */
129 void
130 pfil_runlock(struct pfil_head *ph, struct rm_priotracker *tracker)
131 {
132
133 PFIL_RUNLOCK(ph, tracker);
134 }
135
136 /*
137 * pfil_wlock() acquires writer lock for specified head.
138 */
139 void
140 pfil_wlock(struct pfil_head *ph)
141 {
142
143 PFIL_WLOCK(ph);
144 }
145
146 /*
147 * pfil_wunlock() releases writer lock for specified head.
148 */
149 void
150 pfil_wunlock(struct pfil_head *ph)
151 {
152
153 PFIL_WUNLOCK(ph);
154 }
155
156 /*
157 * pfil_wowned() returns a non-zero value if the current thread owns
158 * an exclusive lock.
159 */
160 int
161 pfil_wowned(struct pfil_head *ph)
162 {
163
164 return (PFIL_WOWNED(ph));
165 }
166
167 /*
168 * pfil_head_register() registers a pfil_head with the packet filter hook
169 * mechanism.
170 */
171 int
172 pfil_head_register(struct pfil_head *ph)
173 {
174 struct pfil_head *lph;
175
176 PFIL_HEADLIST_LOCK();
177 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
178 if (ph->ph_type == lph->ph_type &&
179 ph->ph_un.phu_val == lph->ph_un.phu_val) {
180 PFIL_HEADLIST_UNLOCK();
181 return (EEXIST);
182 }
183 }
184 PFIL_LOCK_INIT(ph);
185 ph->ph_nhooks = 0;
186 TAILQ_INIT(&ph->ph_in);
187 TAILQ_INIT(&ph->ph_out);
188 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
189 PFIL_HEADLIST_UNLOCK();
190 return (0);
191 }
192
193 /*
194 * pfil_head_unregister() removes a pfil_head from the packet filter hook
195 * mechanism. The producer of the hook promises that all outstanding
196 * invocations of the hook have completed before it unregisters the hook.
197 */
198 int
199 pfil_head_unregister(struct pfil_head *ph)
200 {
201 struct packet_filter_hook *pfh, *pfnext;
202
203 PFIL_HEADLIST_LOCK();
204 LIST_REMOVE(ph, ph_list);
205 PFIL_HEADLIST_UNLOCK();
206 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_chain, pfnext)
207 free(pfh, M_IFADDR);
208 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_chain, pfnext)
209 free(pfh, M_IFADDR);
210 PFIL_LOCK_DESTROY(ph);
211 return (0);
212 }
213
214 /*
215 * pfil_head_get() returns the pfil_head for a given key/dlt.
216 */
217 struct pfil_head *
218 pfil_head_get(int type, u_long val)
219 {
220 struct pfil_head *ph;
221
222 PFIL_HEADLIST_LOCK();
223 LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
224 if (ph->ph_type == type && ph->ph_un.phu_val == val)
225 break;
226 PFIL_HEADLIST_UNLOCK();
227 return (ph);
228 }
229
230 /*
231 * pfil_add_hook() adds a function to the packet filter hook. the
232 * flags are:
233 * PFIL_IN call me on incoming packets
234 * PFIL_OUT call me on outgoing packets
235 * PFIL_ALL call me on all of the above
236 * PFIL_WAITOK OK to call malloc with M_WAITOK.
237 */
238 int
239 pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
240 {
241 struct packet_filter_hook *pfh1 = NULL;
242 struct packet_filter_hook *pfh2 = NULL;
243 int err;
244
245 if (flags & PFIL_IN) {
246 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
247 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
248 if (pfh1 == NULL) {
249 err = ENOMEM;
250 goto error;
251 }
252 }
253 if (flags & PFIL_OUT) {
254 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
255 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
256 if (pfh2 == NULL) {
257 err = ENOMEM;
258 goto error;
259 }
260 }
261 PFIL_WLOCK(ph);
262 if (flags & PFIL_IN) {
263 pfh1->pfil_func = func;
264 pfh1->pfil_arg = arg;
265 err = pfil_chain_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
266 if (err)
267 goto locked_error;
268 ph->ph_nhooks++;
269 }
270 if (flags & PFIL_OUT) {
271 pfh2->pfil_func = func;
272 pfh2->pfil_arg = arg;
273 err = pfil_chain_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
274 if (err) {
275 if (flags & PFIL_IN)
276 pfil_chain_remove(&ph->ph_in, func, arg);
277 goto locked_error;
278 }
279 ph->ph_nhooks++;
280 }
281 PFIL_WUNLOCK(ph);
282 return (0);
283 locked_error:
284 PFIL_WUNLOCK(ph);
285 error:
286 if (pfh1 != NULL)
287 free(pfh1, M_IFADDR);
288 if (pfh2 != NULL)
289 free(pfh2, M_IFADDR);
290 return (err);
291 }
292
293 /*
294 * pfil_remove_hook removes a specific function from the packet filter hook
295 * chain.
296 */
297 int
298 pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
299 {
300 int err = 0;
301
302 PFIL_WLOCK(ph);
303 if (flags & PFIL_IN) {
304 err = pfil_chain_remove(&ph->ph_in, func, arg);
305 if (err == 0)
306 ph->ph_nhooks--;
307 }
308 if ((err == 0) && (flags & PFIL_OUT)) {
309 err = pfil_chain_remove(&ph->ph_out, func, arg);
310 if (err == 0)
311 ph->ph_nhooks--;
312 }
313 PFIL_WUNLOCK(ph);
314 return (err);
315 }
316
317 /*
318 * Internal: Add a new pfil hook into a hook chain.
319 */
320 static int
321 pfil_chain_add(pfil_chain_t *chain, struct packet_filter_hook *pfh1, int flags)
322 {
323 struct packet_filter_hook *pfh;
324
325 /*
326 * First make sure the hook is not already there.
327 */
328 TAILQ_FOREACH(pfh, chain, pfil_chain)
329 if (pfh->pfil_func == pfh1->pfil_func &&
330 pfh->pfil_arg == pfh1->pfil_arg)
331 return (EEXIST);
332
333 /*
334 * Insert the input list in reverse order of the output list so that
335 * the same path is followed in or out of the kernel.
336 */
337 if (flags & PFIL_IN)
338 TAILQ_INSERT_HEAD(chain, pfh1, pfil_chain);
339 else
340 TAILQ_INSERT_TAIL(chain, pfh1, pfil_chain);
341 return (0);
342 }
343
344 /*
345 * Internal: Remove a pfil hook from a hook chain.
346 */
347 static int
348 pfil_chain_remove(pfil_chain_t *chain, pfil_func_t func, void *arg)
349 {
350 struct packet_filter_hook *pfh;
351
352 TAILQ_FOREACH(pfh, chain, pfil_chain)
353 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
354 TAILQ_REMOVE(chain, pfh, pfil_chain);
355 free(pfh, M_IFADDR);
356 return (0);
357 }
358 return (ENOENT);
359 }
360
361 /*
362 * Stuff that must be initialized for every instance (including the first of
363 * course).
364 */
365 static int
366 vnet_pfil_init(const void *unused)
367 {
368
369 LIST_INIT(&V_pfil_head_list);
370 PFIL_LOCK_INIT_REAL(&V_pfil_lock, "shared");
371 return (0);
372 }
373
374 /*
375 * Called for the removal of each instance.
376 */
377 static int
378 vnet_pfil_uninit(const void *unused)
379 {
380
381 KASSERT(LIST_EMPTY(&V_pfil_head_list),
382 ("%s: pfil_head_list %p not empty", __func__, &V_pfil_head_list));
383 PFIL_LOCK_DESTROY_REAL(&V_pfil_lock);
384 return (0);
385 }
386
387 /* Define startup order. */
388 #define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN
389 #define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */
390 #define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */
391
392 /*
393 * Starting up.
394 *
395 * VNET_SYSINIT is called for each existing vnet and each new vnet.
396 */
397 VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
398 vnet_pfil_init, NULL);
399
400 /*
401 * Closing up shop. These are done in REVERSE ORDER. Not called on reboot.
402 *
403 * VNET_SYSUNINIT is called for each exiting vnet as it exits.
404 */
405 VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
406 vnet_pfil_uninit, NULL);
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