pfil.c revision 60317 
1/*	$FreeBSD: head/sys/net/pfil.c 60317 2000-05-10 13:37:51Z darrenr $	*/
2
3/*
4 * Copyright (c) 1996 Matthew R. Green
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
25 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/param.h>
32#include <sys/errno.h>
33#include <sys/malloc.h>
34#include <sys/socket.h>
35#include <sys/socketvar.h>
36#include <sys/systm.h>
37#include <sys/proc.h>
38#include <sys/queue.h>
39
40#include <net/if.h>
41#include <net/pfil.h>
42
43static void pfil_init __P((struct pfil_head *));
44static int pfil_list_add(pfil_list_t *,
45    int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
46static int pfil_list_remove(pfil_list_t *,
47    int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
48
49static void
50pfil_init(ph)
51	 struct pfil_head *ph;
52{
53
54	TAILQ_INIT(&ph->ph_in);
55	TAILQ_INIT(&ph->ph_out);
56	ph->ph_init = 1;
57}
58
59/*
60 * pfil_add_hook() adds a function to the packet filter hook.  the
61 * flags are:
62 *	PFIL_IN		call me on incoming packets
63 *	PFIL_OUT	call me on outgoing packets
64 *	PFIL_ALL	call me on all of the above
65 *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
66 */
67int
68pfil_add_hook(func, flags, ph)
69	int	(*func) __P((void *, int, struct ifnet *, int,
70			     struct mbuf **));
71	int	flags;
72	struct	pfil_head	*ph;
73{
74	int err = 0;
75
76	if (ph->ph_init == 0)
77		pfil_init(ph);
78
79	if (flags & PFIL_IN)
80		err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
81	if (err)
82		return err;
83	if (flags & PFIL_OUT)
84		err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
85	if (err) {
86		if (flags & PFIL_IN)
87			pfil_list_remove(&ph->ph_in, func);
88		return err;
89	}
90	return 0;
91}
92
93static int
94pfil_list_add(list, func, flags)
95	pfil_list_t *list;
96	int	(*func) __P((void *, int, struct ifnet *, int,
97			     struct mbuf **));
98	int flags;
99{
100	struct packet_filter_hook *pfh;
101
102	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
103	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
104	if (pfh == NULL)
105		return ENOMEM;
106	pfh->pfil_func = func;
107	/*
108	 * insert the input list in reverse order of the output list
109	 * so that the same path is followed in or out of the kernel.
110	 */
111
112	if (flags & PFIL_IN)
113		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
114	else
115		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
116	return 0;
117}
118
119/*
120 * pfil_remove_hook removes a specific function from the packet filter
121 * hook list.
122 */
123int
124pfil_remove_hook(func, flags, ph)
125	int	(*func) __P((void *, int, struct ifnet *, int,
126			     struct mbuf **));
127	int	flags;
128	struct	pfil_head	*ph;
129{
130	int err = 0;
131
132	if (ph->ph_init == 0)
133		pfil_init(ph);
134
135	if (flags & PFIL_IN)
136		err = pfil_list_remove(&ph->ph_in, func);
137	if ((err == 0) && (flags & PFIL_OUT))
138		err = pfil_list_remove(&ph->ph_out, func);
139	return err;
140}
141
142/*
143 * pfil_list_remove is an internal function that takes a function off the
144 * specified list.
145 */
146static int
147pfil_list_remove(list, func)
148	pfil_list_t *list;
149	int	(*func) __P((void *, int, struct ifnet *, int,
150			     struct mbuf **));
151{
152	struct packet_filter_hook *pfh;
153
154	for (pfh = list->tqh_first; pfh; pfh = pfh->pfil_link.tqe_next)
155		if (pfh->pfil_func == func) {
156			TAILQ_REMOVE(list, pfh, pfil_link);
157			free(pfh, M_IFADDR);
158			return 0;
159		}
160	return ENOENT;
161}
162
163struct packet_filter_hook *
164pfil_hook_get(flag, ph)
165	int flag;
166	struct	pfil_head	*ph;
167{
168	if (ph->ph_init != 0)
169		switch (flag) {
170		case PFIL_IN:
171			return (ph->ph_in.tqh_first);
172		case PFIL_OUT:
173			return (ph->ph_out.tqh_first);
174		}
175	return NULL;
176}
177