pfil.c revision 71999 
1/*	$FreeBSD: head/sys/net/pfil.c 71999 2001-02-04 13:13:25Z phk $	*/
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 __P((struct pfil_head *));
43static int pfil_list_add(pfil_list_t *,
44    int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
45static int pfil_list_remove(pfil_list_t *,
46    int (*) __P((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) __P((void *, int, struct ifnet *, int,
69			     struct mbuf **));
70	int	flags;
71	struct	pfil_head	*ph;
72{
73	int err = 0;
74
75	if (ph->ph_init == 0)
76		pfil_init(ph);
77
78	if (flags & PFIL_IN)
79		err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
80	if (err)
81		return err;
82	if (flags & PFIL_OUT)
83		err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
84	if (err) {
85		if (flags & PFIL_IN)
86			pfil_list_remove(&ph->ph_in, func);
87		return err;
88	}
89	return 0;
90}
91
92static int
93pfil_list_add(list, func, flags)
94	pfil_list_t *list;
95	int	(*func) __P((void *, int, struct ifnet *, int,
96			     struct mbuf **));
97	int flags;
98{
99	struct packet_filter_hook *pfh;
100
101	pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
102	    flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
103	if (pfh == NULL)
104		return ENOMEM;
105	pfh->pfil_func = func;
106	/*
107	 * insert the input list in reverse order of the output list
108	 * so that the same path is followed in or out of the kernel.
109	 */
110
111	if (flags & PFIL_IN)
112		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
113	else
114		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
115	return 0;
116}
117
118/*
119 * pfil_remove_hook removes a specific function from the packet filter
120 * hook list.
121 */
122int
123pfil_remove_hook(func, flags, ph)
124	int	(*func) __P((void *, int, struct ifnet *, int,
125			     struct mbuf **));
126	int	flags;
127	struct	pfil_head	*ph;
128{
129	int err = 0;
130
131	if (ph->ph_init == 0)
132		pfil_init(ph);
133
134	if (flags & PFIL_IN)
135		err = pfil_list_remove(&ph->ph_in, func);
136	if ((err == 0) && (flags & PFIL_OUT))
137		err = pfil_list_remove(&ph->ph_out, func);
138	return err;
139}
140
141/*
142 * pfil_list_remove is an internal function that takes a function off the
143 * specified list.
144 */
145static int
146pfil_list_remove(list, func)
147	pfil_list_t *list;
148	int	(*func) __P((void *, int, struct ifnet *, int,
149			     struct mbuf **));
150{
151	struct packet_filter_hook *pfh;
152
153	TAILQ_FOREACH(pfh, list, pfil_link)
154		if (pfh->pfil_func == func) {
155			TAILQ_REMOVE(list, pfh, pfil_link);
156			free(pfh, M_IFADDR);
157			return 0;
158		}
159	return ENOENT;
160}
161
162struct packet_filter_hook *
163pfil_hook_get(flag, ph)
164	int flag;
165	struct	pfil_head	*ph;
166{
167	if (ph->ph_init != 0)
168		switch (flag) {
169		case PFIL_IN:
170			return (TAILQ_FIRST(&ph->ph_in));
171		case PFIL_OUT:
172			return (TAILQ_FIRST(&ph->ph_out));
173		}
174	return NULL;
175}
176