arptable_filter.c
/*
* Filtering ARP tables module.
*
* Copyright (C) 2002 David S. Miller (davem@redhat.com)
*
*/
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_arp/arp_tables.h>
#include <linux/slab.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
MODULE_DESCRIPTION("arptables filter table");
#define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
(1 << NF_ARP_FORWARD))
static const struct xt_table packet_filter = {
.name = "filter",
.valid_hooks = FILTER_VALID_HOOKS,
.me = THIS_MODULE,
.af = NFPROTO_ARP,
.priority = NF_IP_PRI_FILTER,
};
/* The work comes in here from netfilter.c */
static unsigned int
arptable_filter_hook(unsigned int hook, struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
const struct net *net = dev_net((in != NULL) ? in : out);
return arpt_do_table(skb, hook, in, out, net->ipv4.arptable_filter);
}
static struct nf_hook_ops *arpfilter_ops __read_mostly;
static int __net_init arptable_filter_net_init(struct net *net)
{
struct arpt_replace *repl;
repl = arpt_alloc_initial_table(&packet_filter);
if (repl == NULL)
return -ENOMEM;
net->ipv4.arptable_filter =
arpt_register_table(net, &packet_filter, repl);
kfree(repl);
if (IS_ERR(net->ipv4.arptable_filter))
return PTR_ERR(net->ipv4.arptable_filter);
return 0;
}
static void __net_exit arptable_filter_net_exit(struct net *net)
{
arpt_unregister_table(net->ipv4.arptable_filter);
}
static struct pernet_operations arptable_filter_net_ops = {
.init = arptable_filter_net_init,
.exit = arptable_filter_net_exit,
};
static int __init arptable_filter_init(void)
{
int ret;
ret = register_pernet_subsys(&arptable_filter_net_ops);
if (ret < 0)
return ret;
arpfilter_ops = xt_hook_link(&packet_filter, arptable_filter_hook);
if (IS_ERR(arpfilter_ops)) {
ret = PTR_ERR(arpfilter_ops);
goto cleanup_table;
}
return ret;
cleanup_table:
unregister_pernet_subsys(&arptable_filter_net_ops);
return ret;
}
static void __exit arptable_filter_fini(void)
{
xt_hook_unlink(&packet_filter, arpfilter_ops);
unregister_pernet_subsys(&arptable_filter_net_ops);
}
module_init(arptable_filter_init);
module_exit(arptable_filter_fini);