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 int __net_init arptable_filter_table_init(struct net *net); 21 22 static const struct xt_table packet_filter = { 23 .name = "filter", 24 .valid_hooks = FILTER_VALID_HOOKS, 25 .me = THIS_MODULE, 26 .af = NFPROTO_ARP, 27 .priority = NF_IP_PRI_FILTER, 28 .table_init = arptable_filter_table_init, 29 }; 30 31 /* The work comes in here from netfilter.c */ 32 static unsigned int 33 arptable_filter_hook(void *priv, struct sk_buff *skb, 34 const struct nf_hook_state *state) 35 { 36 return arpt_do_table(skb, state, state->net->ipv4.arptable_filter); 37 } 38 39 static struct nf_hook_ops *arpfilter_ops __read_mostly; 40 41 static int __net_init arptable_filter_table_init(struct net *net) 42 { 43 struct arpt_replace *repl; 44 int err; 45 46 if (net->ipv4.arptable_filter) 47 return 0; 48 49 repl = arpt_alloc_initial_table(&packet_filter); 50 if (repl == NULL) 51 return -ENOMEM; 52 err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops, 53 &net->ipv4.arptable_filter); 54 kfree(repl); 55 return err; 56 } 57 58 static void __net_exit arptable_filter_net_exit(struct net *net) 59 { 60 if (!net->ipv4.arptable_filter) 61 return; 62 arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops); 63 net->ipv4.arptable_filter = NULL; 64 } 65 66 static struct pernet_operations arptable_filter_net_ops = { 67 .exit = arptable_filter_net_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 return ret; 85 } 86 87 static void __exit arptable_filter_fini(void) 88 { 89 unregister_pernet_subsys(&arptable_filter_net_ops); 90 kfree(arpfilter_ops); 91 } 92 93 module_init(arptable_filter_init); 94 module_exit(arptable_filter_fini); 95