1 /*
2 * Filtering ARP tables module.
3 *
4 * Copyright (C) 2002 David S. Miller (davem@redhat.com)
5 *
6 */
7
8 #include <linux/module.h>
9 #include <linux/netfilter/x_tables.h>
10 #include <linux/netfilter_arp/arp_tables.h>
11 #include <linux/slab.h>
12
13 MODULE_LICENSE("GPL");
14 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
15 MODULE_DESCRIPTION("arptables filter table");
16
17 #define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
18 (1 << NF_ARP_FORWARD))
19
20 static const struct xt_table packet_filter = {
21 .name = "filter",
22 .valid_hooks = FILTER_VALID_HOOKS,
23 .me = THIS_MODULE,
24 .af = NFPROTO_ARP,
25 .priority = NF_IP_PRI_FILTER,
26 };
27
28 /* The work comes in here from netfilter.c */
29 static unsigned int
arptable_filter_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)30 arptable_filter_hook(void *priv, struct sk_buff *skb,
31 const struct nf_hook_state *state)
32 {
33 return arpt_do_table(skb, state, state->net->ipv4.arptable_filter);
34 }
35
36 static struct nf_hook_ops *arpfilter_ops __read_mostly;
37
arptable_filter_net_init(struct net * net)38 static int __net_init arptable_filter_net_init(struct net *net)
39 {
40 struct arpt_replace *repl;
41
42 repl = arpt_alloc_initial_table(&packet_filter);
43 if (repl == NULL)
44 return -ENOMEM;
45 net->ipv4.arptable_filter =
46 arpt_register_table(net, &packet_filter, repl);
47 kfree(repl);
48 return PTR_ERR_OR_ZERO(net->ipv4.arptable_filter);
49 }
50
arptable_filter_net_exit(struct net * net)51 static void __net_exit arptable_filter_net_exit(struct net *net)
52 {
53 arpt_unregister_table(net->ipv4.arptable_filter);
54 }
55
56 static struct pernet_operations arptable_filter_net_ops = {
57 .init = arptable_filter_net_init,
58 .exit = arptable_filter_net_exit,
59 };
60
arptable_filter_init(void)61 static int __init arptable_filter_init(void)
62 {
63 int ret;
64
65 ret = register_pernet_subsys(&arptable_filter_net_ops);
66 if (ret < 0)
67 return ret;
68
69 arpfilter_ops = xt_hook_link(&packet_filter, arptable_filter_hook);
70 if (IS_ERR(arpfilter_ops)) {
71 ret = PTR_ERR(arpfilter_ops);
72 goto cleanup_table;
73 }
74 return ret;
75
76 cleanup_table:
77 unregister_pernet_subsys(&arptable_filter_net_ops);
78 return ret;
79 }
80
arptable_filter_fini(void)81 static void __exit arptable_filter_fini(void)
82 {
83 xt_hook_unlink(&packet_filter, arpfilter_ops);
84 unregister_pernet_subsys(&arptable_filter_net_ops);
85 }
86
87 module_init(arptable_filter_init);
88 module_exit(arptable_filter_fini);
89