1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Filtering ARP tables module.
4 *
5 * Copyright (C) 2002 David S. Miller (davem@redhat.com)
6 *
7 */
8
9 #include <linux/module.h>
10 #include <linux/netfilter/x_tables.h>
11 #include <linux/netfilter_arp/arp_tables.h>
12 #include <linux/slab.h>
13
14 MODULE_LICENSE("GPL");
15 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
16 MODULE_DESCRIPTION("arptables filter table");
17
18 #define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
19 (1 << NF_ARP_FORWARD))
20
21 static const struct xt_table packet_filter = {
22 .name = "filter",
23 .valid_hooks = FILTER_VALID_HOOKS,
24 .me = THIS_MODULE,
25 .af = NFPROTO_ARP,
26 .priority = NF_IP_PRI_FILTER,
27 };
28
29 /* The work comes in here from netfilter.c */
30 static unsigned int
arptable_filter_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)31 arptable_filter_hook(void *priv, struct sk_buff *skb,
32 const struct nf_hook_state *state)
33 {
34 return arpt_do_table(skb, state, priv);
35 }
36
37 static struct nf_hook_ops *arpfilter_ops __read_mostly;
38
arptable_filter_table_init(struct net * net)39 static int arptable_filter_table_init(struct net *net)
40 {
41 struct arpt_replace *repl;
42 int err;
43
44 repl = arpt_alloc_initial_table(&packet_filter);
45 if (repl == NULL)
46 return -ENOMEM;
47 err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops);
48 kfree(repl);
49 return err;
50 }
51
arptable_filter_net_pre_exit(struct net * net)52 static void __net_exit arptable_filter_net_pre_exit(struct net *net)
53 {
54 arpt_unregister_table_pre_exit(net, "filter");
55 }
56
arptable_filter_net_exit(struct net * net)57 static void __net_exit arptable_filter_net_exit(struct net *net)
58 {
59 arpt_unregister_table(net, "filter");
60 }
61
62 static struct pernet_operations arptable_filter_net_ops = {
63 .exit = arptable_filter_net_exit,
64 .pre_exit = arptable_filter_net_pre_exit,
65 };
66
arptable_filter_init(void)67 static int __init arptable_filter_init(void)
68 {
69 int ret = xt_register_template(&packet_filter,
70 arptable_filter_table_init);
71
72 if (ret < 0)
73 return ret;
74
75 arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
76 if (IS_ERR(arpfilter_ops)) {
77 xt_unregister_template(&packet_filter);
78 return PTR_ERR(arpfilter_ops);
79 }
80
81 ret = register_pernet_subsys(&arptable_filter_net_ops);
82 if (ret < 0) {
83 xt_unregister_template(&packet_filter);
84 kfree(arpfilter_ops);
85 return ret;
86 }
87
88 return ret;
89 }
90
arptable_filter_fini(void)91 static void __exit arptable_filter_fini(void)
92 {
93 unregister_pernet_subsys(&arptable_filter_net_ops);
94 xt_unregister_template(&packet_filter);
95 kfree(arpfilter_ops);
96 }
97
98 module_init(arptable_filter_init);
99 module_exit(arptable_filter_fini);
100