1 // SPDX-License-Identifier: GPL-2.0-only
3 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
5 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
6 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
8 #include <linux/module.h>
9 #include <linux/netfilter_ipv4/ip_tables.h>
10 #include <linux/netdevice.h>
11 #include <linux/skbuff.h>
12 #include <linux/slab.h>
14 #include <net/route.h>
18 MODULE_LICENSE("GPL");
19 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
20 MODULE_DESCRIPTION("iptables mangle table");
22 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
23 (1 << NF_INET_LOCAL_IN) | \
24 (1 << NF_INET_FORWARD) | \
25 (1 << NF_INET_LOCAL_OUT) | \
26 (1 << NF_INET_POST_ROUTING))
28 static const struct xt_table packet_mangler = {
30 .valid_hooks = MANGLE_VALID_HOOKS,
33 .priority = NF_IP_PRI_MANGLE,
37 ipt_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
39 unsigned int ret, verdict;
40 const struct iphdr *iph;
46 /* Save things which could affect route */
53 ret = ipt_do_table(priv, skb, state);
54 verdict = ret & NF_VERDICT_MASK;
55 /* Reroute for ANY change. */
56 if (verdict != NF_DROP && verdict != NF_STOLEN) {
59 if (iph->saddr != saddr ||
60 iph->daddr != daddr ||
63 err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
65 ret = NF_DROP_ERR(err);
72 /* The work comes in here from netfilter.c. */
74 iptable_mangle_hook(void *priv,
76 const struct nf_hook_state *state)
78 if (state->hook == NF_INET_LOCAL_OUT)
79 return ipt_mangle_out(priv, skb, state);
80 return ipt_do_table(priv, skb, state);
83 static struct nf_hook_ops *mangle_ops __read_mostly;
84 static int iptable_mangle_table_init(struct net *net)
86 struct ipt_replace *repl;
89 repl = ipt_alloc_initial_table(&packet_mangler);
92 ret = ipt_register_table(net, &packet_mangler, repl, mangle_ops);
97 static void __net_exit iptable_mangle_net_pre_exit(struct net *net)
99 ipt_unregister_table_pre_exit(net, "mangle");
102 static void __net_exit iptable_mangle_net_exit(struct net *net)
104 ipt_unregister_table_exit(net, "mangle");
107 static struct pernet_operations iptable_mangle_net_ops = {
108 .pre_exit = iptable_mangle_net_pre_exit,
109 .exit = iptable_mangle_net_exit,
112 static int __init iptable_mangle_init(void)
114 int ret = xt_register_template(&packet_mangler,
115 iptable_mangle_table_init);
119 mangle_ops = xt_hook_ops_alloc(&packet_mangler, iptable_mangle_hook);
120 if (IS_ERR(mangle_ops)) {
121 xt_unregister_template(&packet_mangler);
122 ret = PTR_ERR(mangle_ops);
126 ret = register_pernet_subsys(&iptable_mangle_net_ops);
128 xt_unregister_template(&packet_mangler);
136 static void __exit iptable_mangle_fini(void)
138 unregister_pernet_subsys(&iptable_mangle_net_ops);
139 xt_unregister_template(&packet_mangler);
143 module_init(iptable_mangle_init);
144 module_exit(iptable_mangle_fini);