1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/*
* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
*
* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/ip.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables filter table");
#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
(1 << NF_INET_FORWARD) | \
(1 << NF_INET_LOCAL_OUT))
static struct
{
struct ipt_replace repl;
struct ipt_standard entries[3];
struct ipt_error term;
} initial_table __net_initdata = {
.repl = {
.name = "filter",
.valid_hooks = FILTER_VALID_HOOKS,
.num_entries = 4,
.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
.hook_entry = {
[NF_INET_LOCAL_IN] = 0,
[NF_INET_FORWARD] = sizeof(struct ipt_standard),
[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
},
.underflow = {
[NF_INET_LOCAL_IN] = 0,
[NF_INET_FORWARD] = sizeof(struct ipt_standard),
[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
},
},
.entries = {
IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */
IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */
IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
},
.term = IPT_ERROR_INIT, /* ERROR */
};
static struct xt_table packet_filter = {
.name = "filter",
.valid_hooks = FILTER_VALID_HOOKS,
.lock = __RW_LOCK_UNLOCKED(packet_filter.lock),
.me = THIS_MODULE,
.af = AF_INET,
};
/* The work comes in here from netfilter.c. */
static unsigned int
ipt_local_in_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(in)->ipv4.iptable_filter);
}
static unsigned int
ipt_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(skb, hook, in, out,
dev_net(in)->ipv4.iptable_filter);
}
static unsigned int
ipt_local_out_hook(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct iphdr) ||
ip_hdrlen(skb) < sizeof(struct iphdr))
return NF_ACCEPT;
return ipt_do_table(skb, hook, in, out,
dev_net(out)->ipv4.iptable_filter);
}
static struct nf_hook_ops ipt_ops[] __read_mostly = {
{
.hook = ipt_local_in_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP_PRI_FILTER,
},
{
.hook = ipt_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_FORWARD,
.priority = NF_IP_PRI_FILTER,
},
{
.hook = ipt_local_out_hook,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP_PRI_FILTER,
},
};
/* Default to forward because I got too much mail already. */
static int forward = NF_ACCEPT;
module_param(forward, bool, 0000);
static int __net_init iptable_filter_net_init(struct net *net)
{
/* Register table */
net->ipv4.iptable_filter =
ipt_register_table(net, &packet_filter, &initial_table.repl);
if (IS_ERR(net->ipv4.iptable_filter))
return PTR_ERR(net->ipv4.iptable_filter);
return 0;
}
static void __net_exit iptable_filter_net_exit(struct net *net)
{
ipt_unregister_table(net->ipv4.iptable_filter);
}
static struct pernet_operations iptable_filter_net_ops = {
.init = iptable_filter_net_init,
.exit = iptable_filter_net_exit,
};
static int __init iptable_filter_init(void)
{
int ret;
if (forward < 0 || forward > NF_MAX_VERDICT) {
printk("iptables forward must be 0 or 1\n");
return -EINVAL;
}
/* Entry 1 is the FORWARD hook */
initial_table.entries[1].target.verdict = -forward - 1;
ret = register_pernet_subsys(&iptable_filter_net_ops);
if (ret < 0)
return ret;
/* Register hooks */
ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
if (ret < 0)
goto cleanup_table;
return ret;
cleanup_table:
unregister_pernet_subsys(&iptable_filter_net_ops);
return ret;
}
static void __exit iptable_filter_fini(void)
{
nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
unregister_pernet_subsys(&iptable_filter_net_ops);
}
module_init(iptable_filter_init);
module_exit(iptable_filter_fini);
|