net/ipv4/netfilter/arptable_filter.c

/*
 * 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))

/* Standard entry. */
struct arpt_standard
{
	struct arpt_entry entry;
	struct arpt_standard_target target;
};

struct arpt_error_target
{
	struct arpt_entry_target target;
	char errorname[ARPT_FUNCTION_MAXNAMELEN];
};

struct arpt_error
{
	struct arpt_entry entry;
	struct arpt_error_target target;
};

static struct
{
	struct arpt_replace repl;
	struct arpt_standard entries[3];
	struct arpt_error term;
} initial_table __initdata
= { { "filter", FILTER_VALID_HOOKS, 4,
      sizeof(struct arpt_standard) * 3 + sizeof(struct arpt_error),
      { [NF_ARP_IN] = 0,
	[NF_ARP_OUT] = sizeof(struct arpt_standard),
	[NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard), },
      { [NF_ARP_IN] = 0,
	[NF_ARP_OUT] = sizeof(struct arpt_standard),
	[NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard), },
      0, NULL, { } },
    {
	    /* ARP_IN */
	    {
		    {
			    {
				    { 0 }, { 0 }, { 0 }, { 0 },
				    0, 0,
				    { { 0, }, { 0, } },
				    { { 0, }, { 0, } },
				    0, 0,
				    0, 0,
				    0, 0,
				    "", "", { 0 }, { 0 },
				    0, 0
			    },
			    sizeof(struct arpt_entry),
			    sizeof(struct arpt_standard),
			    0,
			    { 0, 0 }, { } },
		    { { { { ARPT_ALIGN(sizeof(struct arpt_standard_target)), "" } }, { } },
		      -NF_ACCEPT - 1 }
	    },
	    /* ARP_OUT */
	    {
		    {
			    {
				    { 0 }, { 0 }, { 0 }, { 0 },
				    0, 0,
				    { { 0, }, { 0, } },
				    { { 0, }, { 0, } },
				    0, 0,
				    0, 0,
				    0, 0,
				    "", "", { 0 }, { 0 },
				    0, 0
			    },
			    sizeof(struct arpt_entry),
			    sizeof(struct arpt_standard),
			    0,
			    { 0, 0 }, { } },
		    { { { { ARPT_ALIGN(sizeof(struct arpt_standard_target)), "" } }, { } },
		      -NF_ACCEPT - 1 }
	    },
	    /* ARP_FORWARD */
	    {
		    {
			    {
				    { 0 }, { 0 }, { 0 }, { 0 },
				    0, 0,
				    { { 0, }, { 0, } },
				    { { 0, }, { 0, } },
				    0, 0,
				    0, 0,
				    0, 0,
				    "", "", { 0 }, { 0 },
				    0, 0
			    },
			    sizeof(struct arpt_entry),
			    sizeof(struct arpt_standard),
			    0,
			    { 0, 0 }, { } },
		    { { { { ARPT_ALIGN(sizeof(struct arpt_standard_target)), "" } }, { } },
		      -NF_ACCEPT - 1 }
	    }
    },
    /* ERROR */
    {
	    {
		    {
			    { 0 }, { 0 }, { 0 }, { 0 },
			    0, 0,
			    { { 0, }, { 0, } },
			    { { 0, }, { 0, } },
			    0, 0,
			    0, 0,
			    0, 0,
			    "", "", { 0 }, { 0 },
			    0, 0
		    },
		    sizeof(struct arpt_entry),
		    sizeof(struct arpt_error),
		    0,
		    { 0, 0 }, { } },
	    { { { { ARPT_ALIGN(sizeof(struct arpt_error_target)), ARPT_ERROR_TARGET } },
		{ } },
	      "ERROR"
	    }
    }
};

static struct arpt_table packet_filter = {
	.name		= "filter",
	.valid_hooks	= FILTER_VALID_HOOKS,
	.lock		= RW_LOCK_UNLOCKED,
	.private	= NULL,
	.me		= THIS_MODULE,
};

/* The work comes in here from netfilter.c */
static unsigned int arpt_hook(unsigned int hook,
			      struct sk_buff **pskb,
			      const struct net_device *in,
			      const struct net_device *out,
			      int (*okfn)(struct sk_buff *))
{
	return arpt_do_table(pskb, hook, in, out, &packet_filter, NULL);
}

static struct nf_hook_ops arpt_ops[] = {
	{
		.hook		= arpt_hook,
		.owner		= THIS_MODULE,
		.pf		= NF_ARP,
		.hooknum	= NF_ARP_IN,
	},
	{
		.hook		= arpt_hook,
		.owner		= THIS_MODULE,
		.pf		= NF_ARP,
		.hooknum	= NF_ARP_OUT,
	},
	{
		.hook		= arpt_hook,
		.owner		= THIS_MODULE,
		.pf		= NF_ARP,
		.hooknum	= NF_ARP_FORWARD,
	},
};

static int __init init(void)
{
	int ret, i;

	/* Register table */
	ret = arpt_register_table(&packet_filter, &initial_table.repl);
	if (ret < 0)
		return ret;

	for (i = 0; i < ARRAY_SIZE(arpt_ops); i++)
		if ((ret = nf_register_hook(&arpt_ops[i])) < 0)
			goto cleanup_hooks;
	return ret;

cleanup_hooks:
	while (--i >= 0)
		nf_unregister_hook(&arpt_ops[i]);

	arpt_unregister_table(&packet_filter);
	return ret;
}

static void __exit fini(void)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(arpt_ops); i++)
		nf_unregister_hook(&arpt_ops[i]);

	arpt_unregister_table(&packet_filter);
}

module_init(init);
module_exit(fini);