2 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
4 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
5 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/module.h>
12 #include <linux/netfilter_ipv4/ip_tables.h>
13 #include <linux/netdevice.h>
14 #include <linux/skbuff.h>
15 #include <linux/slab.h>
17 #include <net/route.h>
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
23 MODULE_DESCRIPTION("iptables mangle table");
25 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
26 (1 << NF_INET_LOCAL_IN) | \
27 (1 << NF_INET_FORWARD) | \
28 (1 << NF_INET_LOCAL_OUT) | \
29 (1 << NF_INET_POST_ROUTING))
31 static const struct xt_table packet_mangler = {
33 .valid_hooks = MANGLE_VALID_HOOKS,
36 .priority = NF_IP_PRI_MANGLE,
40 ipt_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
43 const struct iphdr *iph;
49 /* root is playing with raw sockets. */
50 if (skb->len < sizeof(struct iphdr) ||
51 ip_hdrlen(skb) < sizeof(struct iphdr))
54 /* Save things which could affect route */
61 ret = ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
62 /* Reroute for ANY change. */
63 if (ret != NF_DROP && ret != NF_STOLEN) {
66 if (iph->saddr != saddr ||
67 iph->daddr != daddr ||
70 err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
72 ret = NF_DROP_ERR(err);
79 /* The work comes in here from netfilter.c. */
81 iptable_mangle_hook(void *priv,
83 const struct nf_hook_state *state)
85 if (state->hook == NF_INET_LOCAL_OUT)
86 return ipt_mangle_out(skb, state);
87 if (state->hook == NF_INET_POST_ROUTING)
88 return ipt_do_table(skb, state,
89 state->net->ipv4.iptable_mangle);
90 /* PREROUTING/INPUT/FORWARD: */
91 return ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
94 static struct nf_hook_ops *mangle_ops __read_mostly;
96 static int __net_init iptable_mangle_net_init(struct net *net)
98 struct ipt_replace *repl;
100 repl = ipt_alloc_initial_table(&packet_mangler);
103 net->ipv4.iptable_mangle =
104 ipt_register_table(net, &packet_mangler, repl);
106 return PTR_ERR_OR_ZERO(net->ipv4.iptable_mangle);
109 static void __net_exit iptable_mangle_net_exit(struct net *net)
111 ipt_unregister_table(net, net->ipv4.iptable_mangle);
114 static struct pernet_operations iptable_mangle_net_ops = {
115 .init = iptable_mangle_net_init,
116 .exit = iptable_mangle_net_exit,
119 static int __init iptable_mangle_init(void)
123 ret = register_pernet_subsys(&iptable_mangle_net_ops);
128 mangle_ops = xt_hook_link(&packet_mangler, iptable_mangle_hook);
129 if (IS_ERR(mangle_ops)) {
130 ret = PTR_ERR(mangle_ops);
131 unregister_pernet_subsys(&iptable_mangle_net_ops);
137 static void __exit iptable_mangle_fini(void)
139 xt_hook_unlink(&packet_mangler, mangle_ops);
140 unregister_pernet_subsys(&iptable_mangle_net_ops);
143 module_init(iptable_mangle_init);
144 module_exit(iptable_mangle_fini);