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9#include <linux/module.h>
10#include <linux/moduleparam.h>
11#include <linux/netfilter_ipv4/ip_tables.h>
12#include <linux/slab.h>
13#include <net/ip.h>
14
15MODULE_LICENSE("GPL");
16MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
17MODULE_DESCRIPTION("iptables filter table");
18
19#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
20 (1 << NF_INET_FORWARD) | \
21 (1 << NF_INET_LOCAL_OUT))
22
23static const struct xt_table packet_filter = {
24 .name = "filter",
25 .valid_hooks = FILTER_VALID_HOOKS,
26 .me = THIS_MODULE,
27 .af = NFPROTO_IPV4,
28 .priority = NF_IP_PRI_FILTER,
29};
30
31static unsigned int
32iptable_filter_hook(void *priv, struct sk_buff *skb,
33 const struct nf_hook_state *state)
34{
35 return ipt_do_table(skb, state, priv);
36}
37
38static struct nf_hook_ops *filter_ops __read_mostly;
39
40
41static bool forward __read_mostly = true;
42module_param(forward, bool, 0000);
43
44static int iptable_filter_table_init(struct net *net)
45{
46 struct ipt_replace *repl;
47 int err;
48
49 repl = ipt_alloc_initial_table(&packet_filter);
50 if (repl == NULL)
51 return -ENOMEM;
52
53 ((struct ipt_standard *)repl->entries)[1].target.verdict =
54 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
55
56 err = ipt_register_table(net, &packet_filter, repl, filter_ops);
57 kfree(repl);
58 return err;
59}
60
61static int __net_init iptable_filter_net_init(struct net *net)
62{
63 if (!forward)
64 return iptable_filter_table_init(net);
65
66 return 0;
67}
68
69static void __net_exit iptable_filter_net_pre_exit(struct net *net)
70{
71 ipt_unregister_table_pre_exit(net, "filter");
72}
73
74static void __net_exit iptable_filter_net_exit(struct net *net)
75{
76 ipt_unregister_table_exit(net, "filter");
77}
78
79static struct pernet_operations iptable_filter_net_ops = {
80 .init = iptable_filter_net_init,
81 .pre_exit = iptable_filter_net_pre_exit,
82 .exit = iptable_filter_net_exit,
83};
84
85static int __init iptable_filter_init(void)
86{
87 int ret = xt_register_template(&packet_filter,
88 iptable_filter_table_init);
89
90 if (ret < 0)
91 return ret;
92
93 filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook);
94 if (IS_ERR(filter_ops)) {
95 xt_unregister_template(&packet_filter);
96 return PTR_ERR(filter_ops);
97 }
98
99 ret = register_pernet_subsys(&iptable_filter_net_ops);
100 if (ret < 0) {
101 xt_unregister_template(&packet_filter);
102 kfree(filter_ops);
103 return ret;
104 }
105
106 return 0;
107}
108
109static void __exit iptable_filter_fini(void)
110{
111 unregister_pernet_subsys(&iptable_filter_net_ops);
112 xt_unregister_template(&packet_filter);
113 kfree(filter_ops);
114}
115
116module_init(iptable_filter_init);
117module_exit(iptable_filter_fini);
118