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 int __net_init arptable_filter_table_init(struct net *net);
22 
23 static const struct xt_table packet_filter = {
24 	.name		= "filter",
25 	.valid_hooks	= FILTER_VALID_HOOKS,
26 	.me		= THIS_MODULE,
27 	.af		= NFPROTO_ARP,
28 	.priority	= NF_IP_PRI_FILTER,
29 	.table_init	= arptable_filter_table_init,
30 };
31 
32 /* The work comes in here from netfilter.c */
33 static unsigned int
34 arptable_filter_hook(void *priv, struct sk_buff *skb,
35 		     const struct nf_hook_state *state)
36 {
37 	return arpt_do_table(skb, state, priv);
38 }
39 
40 static struct nf_hook_ops *arpfilter_ops __read_mostly;
41 
42 static int __net_init arptable_filter_table_init(struct net *net)
43 {
44 	struct arpt_replace *repl;
45 	int err;
46 
47 	repl = arpt_alloc_initial_table(&packet_filter);
48 	if (repl == NULL)
49 		return -ENOMEM;
50 	err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops);
51 	kfree(repl);
52 	return err;
53 }
54 
55 static void __net_exit arptable_filter_net_pre_exit(struct net *net)
56 {
57 	arpt_unregister_table_pre_exit(net, "filter");
58 }
59 
60 static void __net_exit arptable_filter_net_exit(struct net *net)
61 {
62 	arpt_unregister_table(net, "filter");
63 }
64 
65 static struct pernet_operations arptable_filter_net_ops = {
66 	.exit = arptable_filter_net_exit,
67 	.pre_exit = arptable_filter_net_pre_exit,
68 };
69 
70 static int __init arptable_filter_init(void)
71 {
72 	int ret;
73 
74 	arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
75 	if (IS_ERR(arpfilter_ops))
76 		return PTR_ERR(arpfilter_ops);
77 
78 	ret = register_pernet_subsys(&arptable_filter_net_ops);
79 	if (ret < 0) {
80 		kfree(arpfilter_ops);
81 		return ret;
82 	}
83 
84 	ret = arptable_filter_table_init(&init_net);
85 	if (ret) {
86 		unregister_pernet_subsys(&arptable_filter_net_ops);
87 		kfree(arpfilter_ops);
88 	}
89 
90 	return ret;
91 }
92 
93 static void __exit arptable_filter_fini(void)
94 {
95 	unregister_pernet_subsys(&arptable_filter_net_ops);
96 	kfree(arpfilter_ops);
97 }
98 
99 module_init(arptable_filter_init);
100 module_exit(arptable_filter_fini);
101