root/net/ipv4/netfilter/arptable_filter.c

DEFINITIONS

1. arpt_in_hook
2. arpt_out_hook
3. arpt_forward_hook
4. arptable_filter_net_init
5. arptable_filter_net_exit
6. arptable_filter_init
7. arptable_filter_fini

/*
 * Filtering ARP tables module.
 *
 * Copyright (C) 2002 David S. Miller (davem@redhat.com)
 *
 */

#include <linux/module.h>
#include <linux/netfilter_arp/arp_tables.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 struct
{
        struct arpt_replace repl;
        struct arpt_standard entries[3];
        struct arpt_error term;
} initial_table __net_initdata = {
        .repl = {
                .name = "filter",
                .valid_hooks = FILTER_VALID_HOOKS,
                .num_entries = 4,
                .size = sizeof(struct arpt_standard) * 3 + sizeof(struct arpt_error),
                .hook_entry = {
                        [NF_ARP_IN] = 0,
                        [NF_ARP_OUT] = sizeof(struct arpt_standard),
                        [NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard),
                },
                .underflow = {
                        [NF_ARP_IN] = 0,
                        [NF_ARP_OUT] = sizeof(struct arpt_standard),
                        [NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard),
                },
        },
        .entries = {
                ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_IN */
                ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_OUT */
                ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_FORWARD */
        },
        .term = ARPT_ERROR_INIT,
};

static struct xt_table packet_filter = {
        .name           = "filter",
        .valid_hooks    = FILTER_VALID_HOOKS,
        .lock           = __RW_LOCK_UNLOCKED(packet_filter.lock),
        .private        = NULL,
        .me             = THIS_MODULE,
        .af             = NFPROTO_ARP,
};

/* The work comes in here from netfilter.c */
static unsigned int arpt_in_hook(unsigned int hook,
                                 struct sk_buff *skb,
                                 const struct net_device *in,
                                 const struct net_device *out,
                                 int (*okfn)(struct sk_buff *))
{
        return arpt_do_table(skb, hook, in, out,
                             dev_net(in)->ipv4.arptable_filter);
}

static unsigned int arpt_out_hook(unsigned int hook,
                                  struct sk_buff *skb,
                                  const struct net_device *in,
                                  const struct net_device *out,
                                  int (*okfn)(struct sk_buff *))
{
        return arpt_do_table(skb, hook, in, out,
                             dev_net(out)->ipv4.arptable_filter);
}

static unsigned int arpt_forward_hook(unsigned int hook,
                                      struct sk_buff *skb,
                                      const struct net_device *in,
                                      const struct net_device *out,
                                      int (*okfn)(struct sk_buff *))
{
        return arpt_do_table(skb, hook, in, out,
                             dev_net(in)->ipv4.arptable_filter);
}

static struct nf_hook_ops arpt_ops[] __read_mostly = {
        {
                .hook           = arpt_in_hook,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_ARP,
                .hooknum        = NF_ARP_IN,
                .priority       = NF_IP_PRI_FILTER,
        },
        {
                .hook           = arpt_out_hook,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_ARP,
                .hooknum        = NF_ARP_OUT,
                .priority       = NF_IP_PRI_FILTER,
        },
        {
                .hook           = arpt_forward_hook,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_ARP,
                .hooknum        = NF_ARP_FORWARD,
                .priority       = NF_IP_PRI_FILTER,
        },
};

static int __net_init arptable_filter_net_init(struct net *net)
{
        /* Register table */
        net->ipv4.arptable_filter =
                arpt_register_table(net, &packet_filter, &initial_table.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;

        ret = nf_register_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
        if (ret < 0)
                goto cleanup_table;
        return ret;

cleanup_table:
        unregister_pernet_subsys(&arptable_filter_net_ops);
        return ret;
}

static void __exit arptable_filter_fini(void)
{
        nf_unregister_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
        unregister_pernet_subsys(&arptable_filter_net_ops);
}

module_init(arptable_filter_init);
module_exit(arptable_filter_fini);