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, state->net->ipv4.arptable_filter); 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 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 59 static void __net_exit arptable_filter_net_exit(struct net *net) 60 { 61 if (!net->ipv4.arptable_filter) 62 return; 63 arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops); 64 net->ipv4.arptable_filter = NULL; 65 } 66 67 static struct pernet_operations arptable_filter_net_ops = { 68 .exit = arptable_filter_net_exit, 69 }; 70 71 static int __init arptable_filter_init(void) 72 { 73 int ret; 74 75 arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook); 76 if (IS_ERR(arpfilter_ops)) 77 return PTR_ERR(arpfilter_ops); 78 79 ret = register_pernet_subsys(&arptable_filter_net_ops); 80 if (ret < 0) { 81 kfree(arpfilter_ops); 82 return ret; 83 } 84 85 ret = arptable_filter_table_init(&init_net); 86 if (ret) { 87 unregister_pernet_subsys(&arptable_filter_net_ops); 88 kfree(arpfilter_ops); 89 } 90 91 return ret; 92 } 93 94 static void __exit arptable_filter_fini(void) 95 { 96 unregister_pernet_subsys(&arptable_filter_net_ops); 97 kfree(arpfilter_ops); 98 } 99 100 module_init(arptable_filter_init); 101 module_exit(arptable_filter_fini); 102