pfil.c revision 111119 
1/*	$FreeBSD: head/sys/net/pfil.c 111119 2003-02-19 05:47:46Z imp $	*/
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/queue.h>
38
39#include <net/if.h>
40#include <net/pfil.h>
41
42static void pfil_init(struct pfil_head *);
43static int pfil_list_add(pfil_list_t *,
44    int (*)(void *, int, struct ifnet *, int, struct mbuf **), int);
45static int pfil_list_remove(pfil_list_t *,
46    int (*)(void *, int, struct ifnet *, int, struct mbuf **));
47
48static void
49pfil_init(ph)
50	 struct pfil_head *ph;
51{
52
53	TAILQ_INIT(&ph->ph_in);
54	TAILQ_INIT(&ph->ph_out);
55	ph->ph_init = 1;
56}
57
58/*
59 * pfil_add_hook() adds a function to the packet filter hook.  the
60 * flags are:
61 *	PFIL_IN		call me on incoming packets
62 *	PFIL_OUT	call me on outgoing packets
63 *	PFIL_ALL	call me on all of the above
64 *	PFIL_WAITOK	OK to call malloc with M_WAITOK.
65 */
66int
67pfil_add_hook(func, flags, ph)
68	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
69	int	flags;
70	struct	pfil_head	*ph;
71{
72	int err = 0;
73
74	if (ph->ph_init == 0)
75		pfil_init(ph);
76
77	if (flags & PFIL_IN)
78		err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
79	if (err)
80		return err;
81	if (flags & PFIL_OUT)
82		err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
83	if (err) {
84		if (flags & PFIL_IN)
85			pfil_list_remove(&ph->ph_in, func);
86		return err;
87	}
88	return 0;
89}
90
91static int
92pfil_list_add(list, func, flags)
93	pfil_list_t *list;
94	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
95	int flags;
96{
97	struct packet_filter_hook *pfh;
98
99	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
100	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
101	if (pfh == NULL)
102		return ENOMEM;
103	pfh->pfil_func = func;
104	/*
105	 * insert the input list in reverse order of the output list
106	 * so that the same path is followed in or out of the kernel.
107	 */
108
109	if (flags & PFIL_IN)
110		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
111	else
112		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
113	return 0;
114}
115
116/*
117 * pfil_remove_hook removes a specific function from the packet filter
118 * hook list.
119 */
120int
121pfil_remove_hook(func, flags, ph)
122	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
123	int	flags;
124	struct	pfil_head	*ph;
125{
126	int err = 0;
127
128	if (ph->ph_init == 0)
129		pfil_init(ph);
130
131	if (flags & PFIL_IN)
132		err = pfil_list_remove(&ph->ph_in, func);
133	if ((err == 0) && (flags & PFIL_OUT))
134		err = pfil_list_remove(&ph->ph_out, func);
135	return err;
136}
137
138/*
139 * pfil_list_remove is an internal function that takes a function off the
140 * specified list.
141 */
142static int
143pfil_list_remove(list, func)
144	pfil_list_t *list;
145	int	(*func)(void *, int, struct ifnet *, int, struct mbuf **);
146{
147	struct packet_filter_hook *pfh;
148
149	TAILQ_FOREACH(pfh, list, pfil_link)
150		if (pfh->pfil_func == func) {
151			TAILQ_REMOVE(list, pfh, pfil_link);
152			free(pfh, M_IFADDR);
153			return 0;
154		}
155	return ENOENT;
156}
157
158struct packet_filter_hook *
159pfil_hook_get(flag, ph)
160	int flag;
161	struct	pfil_head	*ph;
162{
163	if (ph->ph_init != 0)
164		switch (flag) {
165		case PFIL_IN:
166			return (TAILQ_FIRST(&ph->ph_in));
167		case PFIL_OUT:
168			return (TAILQ_FIRST(&ph->ph_out));
169		}
170	return NULL;
171}
172