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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * 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>
- */
- #include <linux/module.h>
- #include <linux/netfilter_ipv4/ip_tables.h>
- #include <linux/netdevice.h>
- #include <linux/skbuff.h>
- #include <linux/slab.h>
- #include <net/sock.h>
- #include <net/route.h>
- #include <linux/ip.h>
- #include <net/ip.h>
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
- MODULE_DESCRIPTION("iptables mangle table");
- #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
- (1 << NF_INET_LOCAL_IN) | \
- (1 << NF_INET_FORWARD) | \
- (1 << NF_INET_LOCAL_OUT) | \
- (1 << NF_INET_POST_ROUTING))
- static int __net_init iptable_mangle_table_init(struct net *net);
- static const struct xt_table packet_mangler = {
- .name = "mangle",
- .valid_hooks = MANGLE_VALID_HOOKS,
- .me = THIS_MODULE,
- .af = NFPROTO_IPV4,
- .priority = NF_IP_PRI_MANGLE,
- .table_init = iptable_mangle_table_init,
- };
- static unsigned int
- ipt_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
- {
- unsigned int ret;
- const struct iphdr *iph;
- u_int8_t tos;
- __be32 saddr, daddr;
- u_int32_t mark;
- int err;
- /* Save things which could affect route */
- mark = skb->mark;
- iph = ip_hdr(skb);
- saddr = iph->saddr;
- daddr = iph->daddr;
- tos = iph->tos;
- ret = ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
- /* Reroute for ANY change. */
- if (ret != NF_DROP && ret != NF_STOLEN) {
- iph = ip_hdr(skb);
- if (iph->saddr != saddr ||
- iph->daddr != daddr ||
- skb->mark != mark ||
- iph->tos != tos) {
- err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
- if (err < 0)
- ret = NF_DROP_ERR(err);
- }
- }
- return ret;
- }
- /* The work comes in here from netfilter.c. */
- static unsigned int
- iptable_mangle_hook(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- if (state->hook == NF_INET_LOCAL_OUT)
- return ipt_mangle_out(skb, state);
- return ipt_do_table(skb, state, state->net->ipv4.iptable_mangle);
- }
- static struct nf_hook_ops *mangle_ops __read_mostly;
- static int __net_init iptable_mangle_table_init(struct net *net)
- {
- struct ipt_replace *repl;
- int ret;
- if (net->ipv4.iptable_mangle)
- return 0;
- repl = ipt_alloc_initial_table(&packet_mangler);
- if (repl == NULL)
- return -ENOMEM;
- ret = ipt_register_table(net, &packet_mangler, repl, mangle_ops,
- &net->ipv4.iptable_mangle);
- kfree(repl);
- return ret;
- }
- static void __net_exit iptable_mangle_net_pre_exit(struct net *net)
- {
- if (net->ipv4.iptable_mangle)
- ipt_unregister_table_pre_exit(net, net->ipv4.iptable_mangle,
- mangle_ops);
- }
- static void __net_exit iptable_mangle_net_exit(struct net *net)
- {
- if (!net->ipv4.iptable_mangle)
- return;
- ipt_unregister_table_exit(net, net->ipv4.iptable_mangle);
- net->ipv4.iptable_mangle = NULL;
- }
- static struct pernet_operations iptable_mangle_net_ops = {
- .pre_exit = iptable_mangle_net_pre_exit,
- .exit = iptable_mangle_net_exit,
- };
- static int __init iptable_mangle_init(void)
- {
- int ret;
- mangle_ops = xt_hook_ops_alloc(&packet_mangler, iptable_mangle_hook);
- if (IS_ERR(mangle_ops)) {
- ret = PTR_ERR(mangle_ops);
- return ret;
- }
- ret = register_pernet_subsys(&iptable_mangle_net_ops);
- if (ret < 0) {
- kfree(mangle_ops);
- return ret;
- }
- ret = iptable_mangle_table_init(&init_net);
- if (ret) {
- unregister_pernet_subsys(&iptable_mangle_net_ops);
- kfree(mangle_ops);
- }
- return ret;
- }
- static void __exit iptable_mangle_fini(void)
- {
- unregister_pernet_subsys(&iptable_mangle_net_ops);
- kfree(mangle_ops);
- }
- module_init(iptable_mangle_init);
- module_exit(iptable_mangle_fini);
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