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 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 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 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 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 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