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// SPDX-License-Identifier: GPL-2.0-only
/*
* IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6
*
* Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
*/
#include <linux/module.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/slab.h>
#include <net/ipv6.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("ip6tables 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 const struct xt_table packet_mangler = {
.name = "mangle",
.valid_hooks = MANGLE_VALID_HOOKS,
.me = THIS_MODULE,
.af = NFPROTO_IPV6,
.priority = NF_IP6_PRI_MANGLE,
};
static unsigned int
ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
{
struct in6_addr saddr, daddr;
unsigned int ret, verdict;
u32 flowlabel, mark;
u8 hop_limit;
int err;
/* save source/dest address, mark, hoplimit, flowlabel, priority, */
memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
mark = skb->mark;
hop_limit = ipv6_hdr(skb)->hop_limit;
/* flowlabel and prio (includes version, which shouldn't change either */
flowlabel = *((u_int32_t *)ipv6_hdr(skb));
ret = ip6t_do_table(priv, skb, state);
verdict = ret & NF_VERDICT_MASK;
if (verdict != NF_DROP && verdict != NF_STOLEN &&
(!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
!ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
skb->mark != mark ||
ipv6_hdr(skb)->hop_limit != hop_limit ||
flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
err = ip6_route_me_harder(state->net, state->sk, skb);
if (err < 0)
ret = NF_DROP_ERR(err);
}
return ret;
}
/* The work comes in here from netfilter.c. */
static unsigned int
ip6table_mangle_hook(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
{
if (state->hook == NF_INET_LOCAL_OUT)
return ip6t_mangle_out(priv, skb, state);
return ip6t_do_table(priv, skb, state);
}
static struct nf_hook_ops *mangle_ops __read_mostly;
static int ip6table_mangle_table_init(struct net *net)
{
struct ip6t_replace *repl;
int ret;
repl = ip6t_alloc_initial_table(&packet_mangler);
if (repl == NULL)
return -ENOMEM;
ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops);
kfree(repl);
return ret;
}
static void __net_exit ip6table_mangle_net_pre_exit(struct net *net)
{
ip6t_unregister_table_pre_exit(net, "mangle");
}
static void __net_exit ip6table_mangle_net_exit(struct net *net)
{
ip6t_unregister_table_exit(net, "mangle");
}
static struct pernet_operations ip6table_mangle_net_ops = {
.pre_exit = ip6table_mangle_net_pre_exit,
.exit = ip6table_mangle_net_exit,
};
static int __init ip6table_mangle_init(void)
{
int ret = xt_register_template(&packet_mangler,
ip6table_mangle_table_init);
if (ret < 0)
return ret;
mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
if (IS_ERR(mangle_ops)) {
xt_unregister_template(&packet_mangler);
return PTR_ERR(mangle_ops);
}
ret = register_pernet_subsys(&ip6table_mangle_net_ops);
if (ret < 0) {
xt_unregister_template(&packet_mangler);
kfree(mangle_ops);
return ret;
}
return ret;
}
static void __exit ip6table_mangle_fini(void)
{
unregister_pernet_subsys(&ip6table_mangle_net_ops);
xt_unregister_template(&packet_mangler);
kfree(mangle_ops);
}
module_init(ip6table_mangle_init);
module_exit(ip6table_mangle_fini);