FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c
1 /* $FreeBSD$ */
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 int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
56
57 static int pfil_list_remove(pfil_list_t *,
58 int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
59 void *);
60
61 LIST_HEAD(pfilheadhead, pfil_head);
62 VNET_DEFINE(struct pfilheadhead, pfil_head_list);
63 #define V_pfil_head_list VNET(pfil_head_list)
64
65 /*
66 * pfil_run_hooks() runs the specified packet filter hooks.
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_hook_get(dir, ph); pfh != NULL;
80 pfh = TAILQ_NEXT(pfh, pfil_link)) {
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 /*
94 * pfil_head_register() registers a pfil_head with the packet filter hook
95 * mechanism.
96 */
97 int
98 pfil_head_register(struct pfil_head *ph)
99 {
100 struct pfil_head *lph;
101
102 PFIL_LIST_LOCK();
103 LIST_FOREACH(lph, &V_pfil_head_list, ph_list) {
104 if (ph->ph_type == lph->ph_type &&
105 ph->ph_un.phu_val == lph->ph_un.phu_val) {
106 PFIL_LIST_UNLOCK();
107 return (EEXIST);
108 }
109 }
110 PFIL_LOCK_INIT(ph);
111 ph->ph_nhooks = 0;
112 TAILQ_INIT(&ph->ph_in);
113 TAILQ_INIT(&ph->ph_out);
114 LIST_INSERT_HEAD(&V_pfil_head_list, ph, ph_list);
115 PFIL_LIST_UNLOCK();
116 return (0);
117 }
118
119 /*
120 * pfil_head_unregister() removes a pfil_head from the packet filter hook
121 * mechanism. The producer of the hook promises that all outstanding
122 * invocations of the hook have completed before it unregisters the hook.
123 */
124 int
125 pfil_head_unregister(struct pfil_head *ph)
126 {
127 struct packet_filter_hook *pfh, *pfnext;
128
129 PFIL_LIST_LOCK();
130 LIST_REMOVE(ph, ph_list);
131 PFIL_LIST_UNLOCK();
132 TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
133 free(pfh, M_IFADDR);
134 TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
135 free(pfh, M_IFADDR);
136 PFIL_LOCK_DESTROY(ph);
137 return (0);
138 }
139
140 /*
141 * pfil_head_get() returns the pfil_head for a given key/dlt.
142 */
143 struct pfil_head *
144 pfil_head_get(int type, u_long val)
145 {
146 struct pfil_head *ph;
147
148 PFIL_LIST_LOCK();
149 LIST_FOREACH(ph, &V_pfil_head_list, ph_list)
150 if (ph->ph_type == type && ph->ph_un.phu_val == val)
151 break;
152 PFIL_LIST_UNLOCK();
153 return (ph);
154 }
155
156 /*
157 * pfil_add_hook() adds a function to the packet filter hook. the
158 * flags are:
159 * PFIL_IN call me on incoming packets
160 * PFIL_OUT call me on outgoing packets
161 * PFIL_ALL call me on all of the above
162 * PFIL_WAITOK OK to call malloc with M_WAITOK.
163 */
164 int
165 pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int,
166 struct inpcb *), void *arg, int flags, struct pfil_head *ph)
167 {
168 struct packet_filter_hook *pfh1 = NULL;
169 struct packet_filter_hook *pfh2 = NULL;
170 int err;
171
172 if (flags & PFIL_IN) {
173 pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
174 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
175 if (pfh1 == NULL) {
176 err = ENOMEM;
177 goto error;
178 }
179 }
180 if (flags & PFIL_OUT) {
181 pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
182 M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
183 if (pfh2 == NULL) {
184 err = ENOMEM;
185 goto error;
186 }
187 }
188 PFIL_WLOCK(ph);
189 if (flags & PFIL_IN) {
190 pfh1->pfil_func = func;
191 pfh1->pfil_arg = arg;
192 err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
193 if (err)
194 goto locked_error;
195 ph->ph_nhooks++;
196 }
197 if (flags & PFIL_OUT) {
198 pfh2->pfil_func = func;
199 pfh2->pfil_arg = arg;
200 err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
201 if (err) {
202 if (flags & PFIL_IN)
203 pfil_list_remove(&ph->ph_in, func, arg);
204 goto locked_error;
205 }
206 ph->ph_nhooks++;
207 }
208 PFIL_WUNLOCK(ph);
209 return (0);
210 locked_error:
211 PFIL_WUNLOCK(ph);
212 error:
213 if (pfh1 != NULL)
214 free(pfh1, M_IFADDR);
215 if (pfh2 != NULL)
216 free(pfh2, M_IFADDR);
217 return (err);
218 }
219
220 /*
221 * pfil_remove_hook removes a specific function from the packet filter hook
222 * list.
223 */
224 int
225 pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int,
226 struct inpcb *), void *arg, int flags, struct pfil_head *ph)
227 {
228 int err = 0;
229
230 PFIL_WLOCK(ph);
231 if (flags & PFIL_IN) {
232 err = pfil_list_remove(&ph->ph_in, func, arg);
233 if (err == 0)
234 ph->ph_nhooks--;
235 }
236 if ((err == 0) && (flags & PFIL_OUT)) {
237 err = pfil_list_remove(&ph->ph_out, func, arg);
238 if (err == 0)
239 ph->ph_nhooks--;
240 }
241 PFIL_WUNLOCK(ph);
242 return (err);
243 }
244
245 static int
246 pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
247 {
248 struct packet_filter_hook *pfh;
249
250 /*
251 * First make sure the hook is not already there.
252 */
253 TAILQ_FOREACH(pfh, list, pfil_link)
254 if (pfh->pfil_func == pfh1->pfil_func &&
255 pfh->pfil_arg == pfh1->pfil_arg)
256 return (EEXIST);
257
258 /*
259 * Insert the input list in reverse order of the output list so that
260 * the same path is followed in or out of the kernel.
261 */
262 if (flags & PFIL_IN)
263 TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
264 else
265 TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
266 return (0);
267 }
268
269 /*
270 * pfil_list_remove is an internal function that takes a function off the
271 * specified list.
272 */
273 static int
274 pfil_list_remove(pfil_list_t *list,
275 int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
276 void *arg)
277 {
278 struct packet_filter_hook *pfh;
279
280 TAILQ_FOREACH(pfh, list, pfil_link)
281 if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
282 TAILQ_REMOVE(list, pfh, pfil_link);
283 free(pfh, M_IFADDR);
284 return (0);
285 }
286 return (ENOENT);
287 }
288
289 /****************
290 * Stuff that must be initialized for every instance
291 * (including the first of course).
292 */
293 static int
294 vnet_pfil_init(const void *unused)
295 {
296 LIST_INIT(&V_pfil_head_list);
297 return (0);
298 }
299
300 /***********************
301 * Called for the removal of each instance.
302 */
303 static int
304 vnet_pfil_uninit(const void *unused)
305 {
306 /* XXX should panic if list is not empty */
307 return 0;
308 }
309
310 /* Define startup order. */
311 #define PFIL_SYSINIT_ORDER SI_SUB_PROTO_BEGIN
312 #define PFIL_MODEVENT_ORDER (SI_ORDER_FIRST) /* On boot slot in here. */
313 #define PFIL_VNET_ORDER (PFIL_MODEVENT_ORDER + 2) /* Later still. */
314
315 /*
316 * Starting up.
317 * VNET_SYSINIT is called for each existing vnet and each new vnet.
318 */
319 VNET_SYSINIT(vnet_pfil_init, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
320 vnet_pfil_init, NULL);
321
322 /*
323 * Closing up shop. These are done in REVERSE ORDER,
324 * Not called on reboot.
325 * VNET_SYSUNINIT is called for each exiting vnet as it exits.
326 */
327 VNET_SYSUNINIT(vnet_pfil_uninit, PFIL_SYSINIT_ORDER, PFIL_VNET_ORDER,
328 vnet_pfil_uninit, NULL);
329
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