- 根目录:
- net
- ipv6
- netfilter
- ip6table_nat.c
/*
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* 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.
*
* Based on Rusty Russell's IPv4 NAT code. Development of IPv6 NAT
* funded by Astaro.
*/
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l3proto.h>
static const struct xt_table nf_nat_ipv6_table = {
.name = "nat",
.valid_hooks = (1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_LOCAL_IN),
.me = THIS_MODULE,
.af = NFPROTO_IPV6,
};
static unsigned int alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
{
/* Force range to this IP; let proto decide mapping for
* per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
*/
struct nf_nat_range range;
range.flags = 0;
pr_debug("Allocating NULL binding for %p (%pI6)\n", ct,
HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ?
&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip6 :
&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip6);
return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
}
static unsigned int nf_nat_rule_find(struct sk_buff *skb, unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
struct nf_conn *ct)
{
struct net *net = nf_ct_net(ct);
unsigned int ret;
ret = ip6t_do_table(skb, hooknum, in, out, net->ipv6.ip6table_nat);
if (ret == NF_ACCEPT) {
if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
ret = alloc_null_binding(ct, hooknum);
}
return ret;
}
static unsigned int
nf_nat_ipv6_fn(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
struct nf_conn_nat *nat;
enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);
__be16 frag_off;
int hdrlen;
u8 nexthdr;
ct = nf_ct_get(skb, &ctinfo);
/* Can't track? It's not due to stress, or conntrack would
* have dropped it. Hence it's the user's responsibilty to
* packet filter it out, or implement conntrack/NAT for that
* protocol. 8) --RR
*/
if (!ct)
return NF_ACCEPT;
/* Don't try to NAT if this packet is not conntracked */
if (nf_ct_is_untracked(ct))
return NF_ACCEPT;
nat = nfct_nat(ct);
if (!nat) {
/* NAT module was loaded late. */
if (nf_ct_is_confirmed(ct))
return NF_ACCEPT;
nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
if (nat == NULL) {
pr_debug("failed to add NAT extension\n");
return NF_ACCEPT;
}
}
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED_REPLY:
nexthdr = ipv6_hdr(skb)->nexthdr;
hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
&nexthdr, &frag_off);
if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
hooknum, hdrlen))
return NF_DROP;
else
return NF_ACCEPT;
}
/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
case IP_CT_NEW:
/* Seen it before? This can happen for loopback, retrans,
* or local packets.
*/
if (!nf_nat_initialized(ct, maniptype)) {
unsigned int ret;
ret = nf_nat_rule_find(skb, hooknum, in, out, ct);
if (ret != NF_ACCEPT)
return ret;
} else {
pr_debug("Already setup manip %s for ct %p\n",
maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
ct);
if (nf_nat_oif_changed(hooknum, ctinfo, nat, out))
goto oif_changed;
}
break;
default:
/* ESTABLISHED */
NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
ctinfo == IP_CT_ESTABLISHED_REPLY);
if (nf_nat_oif_changed(hooknum, ctinfo, nat, out))
goto oif_changed;
}
return nf_nat_packet(ct, ctinfo, hooknum, skb);
oif_changed:
nf_ct_kill_acct(ct, ctinfo, skb);
return NF_DROP;
}
static unsigned int
nf_nat_ipv6_in(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
unsigned int ret;
struct in6_addr daddr = ipv6_hdr(skb)->daddr;
ret = nf_nat_ipv6_fn(hooknum, skb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN &&
ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
skb_dst_drop(skb);
return ret;
}
static unsigned int
nf_nat_ipv6_out(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
#ifdef CONFIG_XFRM
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
int err;
#endif
unsigned int ret;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct ipv6hdr))
return NF_ACCEPT;
ret = nf_nat_ipv6_fn(hooknum, skb, in, out, okfn);
#ifdef CONFIG_XFRM
if (ret != NF_DROP && ret != NF_STOLEN &&
!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
&ct->tuplehash[!dir].tuple.dst.u3) ||
(ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
ct->tuplehash[dir].tuple.src.u.all !=
ct->tuplehash[!dir].tuple.dst.u.all)) {
err = nf_xfrm_me_harder(skb, AF_INET6);
if (err < 0)
ret = NF_DROP_ERR(err);
}
}
#endif
return ret;
}
static unsigned int
nf_nat_ipv6_local_fn(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
unsigned int ret;
int err;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct ipv6hdr))
return NF_ACCEPT;
ret = nf_nat_ipv6_fn(hooknum, skb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
&ct->tuplehash[!dir].tuple.src.u3)) {
err = ip6_route_me_harder(skb);
if (err < 0)
ret = NF_DROP_ERR(err);
}
#ifdef CONFIG_XFRM
else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
ct->tuplehash[dir].tuple.dst.u.all !=
ct->tuplehash[!dir].tuple.src.u.all) {
err = nf_xfrm_me_harder(skb, AF_INET6);
if (err < 0)
ret = NF_DROP_ERR(err);
}
#endif
}
return ret;
}
static struct nf_hook_ops nf_nat_ipv6_ops[] __read_mostly = {
/* Before packet filtering, change destination */
{
.hook = nf_nat_ipv6_in,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_PRE_ROUTING,
.priority = NF_IP6_PRI_NAT_DST,
},
/* After packet filtering, change source */
{
.hook = nf_nat_ipv6_out,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP6_PRI_NAT_SRC,
},
/* Before packet filtering, change destination */
{
.hook = nf_nat_ipv6_local_fn,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_LOCAL_OUT,
.priority = NF_IP6_PRI_NAT_DST,
},
/* After packet filtering, change source */
{
.hook = nf_nat_ipv6_fn,
.owner = THIS_MODULE,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_LOCAL_IN,
.priority = NF_IP6_PRI_NAT_SRC,
},
};
static int __net_init ip6table_nat_net_init(struct net *net)
{
struct ip6t_replace *repl;
repl = ip6t_alloc_initial_table(&nf_nat_ipv6_table);
if (repl == NULL)
return -ENOMEM;
net->ipv6.ip6table_nat = ip6t_register_table(net, &nf_nat_ipv6_table, repl);
kfree(repl);
return PTR_RET(net->ipv6.ip6table_nat);
}
static void __net_exit ip6table_nat_net_exit(struct net *net)
{
ip6t_unregister_table(net, net->ipv6.ip6table_nat);
}
static struct pernet_operations ip6table_nat_net_ops = {
.init = ip6table_nat_net_init,
.exit = ip6table_nat_net_exit,
};
static int __init ip6table_nat_init(void)
{
int err;
err = register_pernet_subsys(&ip6table_nat_net_ops);
if (err < 0)
goto err1;
err = nf_register_hooks(nf_nat_ipv6_ops, ARRAY_SIZE(nf_nat_ipv6_ops));
if (err < 0)
goto err2;
return 0;
err2:
unregister_pernet_subsys(&ip6table_nat_net_ops);
err1:
return err;
}
static void __exit ip6table_nat_exit(void)
{
nf_unregister_hooks(nf_nat_ipv6_ops, ARRAY_SIZE(nf_nat_ipv6_ops));
unregister_pernet_subsys(&ip6table_nat_net_ops);
}
module_init(ip6table_nat_init);
module_exit(ip6table_nat_exit);
MODULE_LICENSE("GPL");