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- /*
- * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
- *
- * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
- * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- */
- #include <linux/module.h>
- #include <linux/moduleparam.h>
- #include <linux/netfilter_ipv4/ip_tables.h>
- #include <linux/slab.h>
- #include <net/ip.h>
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
- MODULE_DESCRIPTION("iptables filter table");
- #define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
- (1 << NF_INET_FORWARD) | \
- (1 << NF_INET_LOCAL_OUT))
- static const struct xt_table packet_filter = {
- .name = "filter",
- .valid_hooks = FILTER_VALID_HOOKS,
- .me = THIS_MODULE,
- .af = NFPROTO_IPV4,
- .priority = NF_IP_PRI_FILTER,
- };
- static unsigned int
- iptable_filter_hook(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- if (state->hook == NF_INET_LOCAL_OUT &&
- (skb->len < sizeof(struct iphdr) ||
- ip_hdrlen(skb) < sizeof(struct iphdr)))
- /* root is playing with raw sockets. */
- return NF_ACCEPT;
- return ipt_do_table(skb, state, state->net->ipv4.iptable_filter);
- }
- static struct nf_hook_ops *filter_ops __read_mostly;
- /* Default to forward because I got too much mail already. */
- static bool forward = true;
- module_param(forward, bool, 0000);
- static int __net_init iptable_filter_net_init(struct net *net)
- {
- struct ipt_replace *repl;
- repl = ipt_alloc_initial_table(&packet_filter);
- if (repl == NULL)
- return -ENOMEM;
- /* Entry 1 is the FORWARD hook */
- ((struct ipt_standard *)repl->entries)[1].target.verdict =
- forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
- net->ipv4.iptable_filter =
- ipt_register_table(net, &packet_filter, repl);
- kfree(repl);
- return PTR_ERR_OR_ZERO(net->ipv4.iptable_filter);
- }
- static void __net_exit iptable_filter_net_exit(struct net *net)
- {
- ipt_unregister_table(net, net->ipv4.iptable_filter);
- }
- static struct pernet_operations iptable_filter_net_ops = {
- .init = iptable_filter_net_init,
- .exit = iptable_filter_net_exit,
- };
- static int __init iptable_filter_init(void)
- {
- int ret;
- ret = register_pernet_subsys(&iptable_filter_net_ops);
- if (ret < 0)
- return ret;
- /* Register hooks */
- filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook);
- if (IS_ERR(filter_ops)) {
- ret = PTR_ERR(filter_ops);
- unregister_pernet_subsys(&iptable_filter_net_ops);
- }
- return ret;
- }
- static void __exit iptable_filter_fini(void)
- {
- xt_hook_unlink(&packet_filter, filter_ops);
- unregister_pernet_subsys(&iptable_filter_net_ops);
- }
- module_init(iptable_filter_init);
- module_exit(iptable_filter_fini);
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