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
arptable_filter_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)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, state->net->ipv4.arptable_filter);
38 }
39
40 static struct nf_hook_ops *arpfilter_ops __read_mostly;
41
arptable_filter_table_init(struct net * net)42 static int __net_init arptable_filter_table_init(struct net *net)
43 {
44 struct arpt_replace *repl;
45 int err;
46
47 if (net->ipv4.arptable_filter)
48 return 0;
49
50 repl = arpt_alloc_initial_table(&packet_filter);
51 if (repl == NULL)
52 return -ENOMEM;
53 err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops,
54 &net->ipv4.arptable_filter);
55 kfree(repl);
56 return err;
57 }
58
arptable_filter_net_pre_exit(struct net * net)59 static void __net_exit arptable_filter_net_pre_exit(struct net *net)
60 {
61 if (net->ipv4.arptable_filter)
62 arpt_unregister_table_pre_exit(net, net->ipv4.arptable_filter,
63 arpfilter_ops);
64 }
65
arptable_filter_net_exit(struct net * net)66 static void __net_exit arptable_filter_net_exit(struct net *net)
67 {
68 if (!net->ipv4.arptable_filter)
69 return;
70 arpt_unregister_table(net, net->ipv4.arptable_filter);
71 net->ipv4.arptable_filter = NULL;
72 }
73
74 static struct pernet_operations arptable_filter_net_ops = {
75 .exit = arptable_filter_net_exit,
76 .pre_exit = arptable_filter_net_pre_exit,
77 };
78
arptable_filter_init(void)79 static int __init arptable_filter_init(void)
80 {
81 int ret;
82
83 arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
84 if (IS_ERR(arpfilter_ops))
85 return PTR_ERR(arpfilter_ops);
86
87 ret = register_pernet_subsys(&arptable_filter_net_ops);
88 if (ret < 0) {
89 kfree(arpfilter_ops);
90 return ret;
91 }
92
93 ret = arptable_filter_table_init(&init_net);
94 if (ret) {
95 unregister_pernet_subsys(&arptable_filter_net_ops);
96 kfree(arpfilter_ops);
97 }
98
99 return ret;
100 }
101
arptable_filter_fini(void)102 static void __exit arptable_filter_fini(void)
103 {
104 unregister_pernet_subsys(&arptable_filter_net_ops);
105 kfree(arpfilter_ops);
106 }
107
108 module_init(arptable_filter_init);
109 module_exit(arptable_filter_fini);
110