xref: /freebsd/sys/kern/uipc_accf.c (revision 6780ab54325a71e7e70112b11657973edde8655e)
1 /*
2  * Copyright (c) 2000 Paycounter, Inc.
3  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  *
27  *	$FreeBSD$
28  */
29 
30 #define ACCEPT_FILTER_MOD
31 
32 #include "opt_param.h"
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/domain.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/protosw.h>
40 #include <sys/sysctl.h>
41 #include <sys/socket.h>
42 #include <sys/socketvar.h>
43 #include <sys/queue.h>
44 
45 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
46 	SLIST_HEAD_INITIALIZER(&accept_filtlsthd);
47 
48 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
49 
50 static int unloadable = 0;
51 
52 SYSCTL_DECL(_net_inet);	/* XXX: some header should do this for me */
53 SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
54 SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
55 	"Allow unload of accept filters (not recommended)");
56 
57 /*
58  * must be passed a malloc'd structure so we don't explode if the kld
59  * is unloaded, we leak the struct on deallocation to deal with this,
60  * but if a filter is loaded with the same name as a leaked one we re-use
61  * the entry.
62  */
63 int
64 accept_filt_add(struct accept_filter *filt)
65 {
66 	struct accept_filter *p;
67 
68 	SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
69 		if (strcmp(p->accf_name, filt->accf_name) == 0)  {
70 			if (p->accf_callback != NULL) {
71 				return (EEXIST);
72 			} else {
73 				p->accf_callback = filt->accf_callback;
74 				FREE(filt, M_ACCF);
75 				return (0);
76 			}
77 		}
78 
79 	if (p == NULL)
80 		SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
81 	return (0);
82 }
83 
84 int
85 accept_filt_del(char *name)
86 {
87 	struct accept_filter *p;
88 
89 	p = accept_filt_get(name);
90 	if (p == NULL)
91 		return (ENOENT);
92 
93 	p->accf_callback = NULL;
94 	return (0);
95 }
96 
97 struct accept_filter *
98 accept_filt_get(char *name)
99 {
100 	struct accept_filter *p;
101 
102 	SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
103 		if (strcmp(p->accf_name, name) == 0)
104 			return (p);
105 
106 	return (NULL);
107 }
108 
109 int
110 accept_filt_generic_mod_event(module_t mod, int event, void *data)
111 {
112 	struct accept_filter *p;
113 	struct accept_filter *accfp = (struct accept_filter *) data;
114 	int	s, error;
115 
116 	switch (event) {
117 	case MOD_LOAD:
118 		MALLOC(p, struct accept_filter *, sizeof(*p), M_ACCF, 0);
119 		bcopy(accfp, p, sizeof(*p));
120 		s = splnet();
121 		error = accept_filt_add(p);
122 		splx(s);
123 		break;
124 
125 	case MOD_UNLOAD:
126 		/*
127 		 * Do not support unloading yet. we don't keep track of refcounts
128 		 * and unloading an accept filter callback and then having it called
129 		 * is a bad thing.  A simple fix would be to track the refcount
130 		 * in the struct accept_filter.
131 		 */
132 		if (unloadable != 0) {
133 			s = splnet();
134 			error = accept_filt_del(accfp->accf_name);
135 			splx(s);
136 		} else
137 			error = EOPNOTSUPP;
138 		break;
139 
140 	case MOD_SHUTDOWN:
141 		error = 0;
142 		break;
143 
144 	default:
145 		error = EOPNOTSUPP;
146 		break;
147 	}
148 
149 	return (error);
150 }
151