blob: d8b2e14efddc0d6a0c4ab8bc968ba84b29590fa7 [file] [log] [blame]
/*
* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
* (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.
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/secure_seq.h>
#include <net/checksum.h>
#include <net/route.h>
#include <net/ip.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l3proto.h>
#include <net/netfilter/nf_nat_l4proto.h>
static const struct nf_nat_l3proto nf_nat_l3proto_ipv4;
#ifdef CONFIG_XFRM
static void nf_nat_ipv4_decode_session(struct sk_buff *skb,
const struct nf_conn *ct,
enum ip_conntrack_dir dir,
unsigned long statusbit,
struct flowi *fl)
{
const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
struct flowi4 *fl4 = &fl->u.ip4;
if (ct->status & statusbit) {
fl4->daddr = t->dst.u3.ip;
if (t->dst.protonum == IPPROTO_TCP ||
t->dst.protonum == IPPROTO_UDP ||
t->dst.protonum == IPPROTO_UDPLITE ||
t->dst.protonum == IPPROTO_DCCP ||
t->dst.protonum == IPPROTO_SCTP)
fl4->fl4_dport = t->dst.u.all;
}
statusbit ^= IPS_NAT_MASK;
if (ct->status & statusbit) {
fl4->saddr = t->src.u3.ip;
if (t->dst.protonum == IPPROTO_TCP ||
t->dst.protonum == IPPROTO_UDP ||
t->dst.protonum == IPPROTO_UDPLITE ||
t->dst.protonum == IPPROTO_DCCP ||
t->dst.protonum == IPPROTO_SCTP)
fl4->fl4_sport = t->src.u.all;
}
}
#endif /* CONFIG_XFRM */
static bool nf_nat_ipv4_in_range(const struct nf_conntrack_tuple *t,
const struct nf_nat_range *range)
{
return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
}
static u32 nf_nat_ipv4_secure_port(const struct nf_conntrack_tuple *t,
__be16 dport)
{
return secure_ipv4_port_ephemeral(t->src.u3.ip, t->dst.u3.ip, dport);
}
static bool nf_nat_ipv4_manip_pkt(struct sk_buff *skb,
unsigned int iphdroff,
const struct nf_nat_l4proto *l4proto,
const struct nf_conntrack_tuple *target,
enum nf_nat_manip_type maniptype)
{
struct iphdr *iph;
unsigned int hdroff;
if (!skb_make_writable(skb, iphdroff + sizeof(*iph)))
return false;
iph = (void *)skb->data + iphdroff;
hdroff = iphdroff + iph->ihl * 4;
if (!l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv4, iphdroff, hdroff,
target, maniptype))
return false;
iph = (void *)skb->data + iphdroff;
if (maniptype == NF_NAT_MANIP_SRC) {
csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
iph->saddr = target->src.u3.ip;
} else {
csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
iph->daddr = target->dst.u3.ip;
}
return true;
}
static void nf_nat_ipv4_csum_update(struct sk_buff *skb,
unsigned int iphdroff, __sum16 *check,
const struct nf_conntrack_tuple *t,
enum nf_nat_manip_type maniptype)
{
struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
__be32 oldip, newip;
if (maniptype == NF_NAT_MANIP_SRC) {
oldip = iph->saddr;
newip = t->src.u3.ip;
} else {
oldip = iph->daddr;
newip = t->dst.u3.ip;
}
inet_proto_csum_replace4(check, skb, oldip, newip, 1);
}
static void nf_nat_ipv4_csum_recalc(struct sk_buff *skb,
u8 proto, void *data, __sum16 *check,
int datalen, int oldlen)
{
const struct iphdr *iph = ip_hdr(skb);
struct rtable *rt = skb_rtable(skb);
if (skb->ip_summed != CHECKSUM_PARTIAL) {
if (!(rt->rt_flags & RTCF_LOCAL) &&
(!skb->dev || skb->dev->features & NETIF_F_V4_CSUM)) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_headroom(skb) +
skb_network_offset(skb) +
ip_hdrlen(skb);
skb->csum_offset = (void *)check - data;
*check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, proto, 0);
} else {
*check = 0;
*check = csum_tcpudp_magic(iph->saddr, iph->daddr,
datalen, proto,
csum_partial(data, datalen,
0));
if (proto == IPPROTO_UDP && !*check)
*check = CSUM_MANGLED_0;
}
} else
inet_proto_csum_replace2(check, skb,
htons(oldlen), htons(datalen), 1);
}
static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
struct nf_nat_range *range)
{
if (tb[CTA_NAT_V4_MINIP]) {
range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
range->flags |= NF_NAT_RANGE_MAP_IPS;
}
if (tb[CTA_NAT_V4_MAXIP])
range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
else
range->max_addr.ip = range->min_addr.ip;
return 0;
}
static const struct nf_nat_l3proto nf_nat_l3proto_ipv4 = {
.l3proto = NFPROTO_IPV4,
.in_range = nf_nat_ipv4_in_range,
.secure_port = nf_nat_ipv4_secure_port,
.manip_pkt = nf_nat_ipv4_manip_pkt,
.csum_update = nf_nat_ipv4_csum_update,
.csum_recalc = nf_nat_ipv4_csum_recalc,
.nlattr_to_range = nf_nat_ipv4_nlattr_to_range,
#ifdef CONFIG_XFRM
.decode_session = nf_nat_ipv4_decode_session,
#endif
};
int nf_nat_icmp_reply_translation(struct sk_buff *skb,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
unsigned int hooknum)
{
struct {
struct icmphdr icmp;
struct iphdr ip;
} *inside;
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
unsigned int hdrlen = ip_hdrlen(skb);
const struct nf_nat_l4proto *l4proto;
struct nf_conntrack_tuple target;
unsigned long statusbit;
NF_CT_ASSERT(ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY);
if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
return 0;
if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
return 0;
inside = (void *)skb->data + hdrlen;
if (inside->icmp.type == ICMP_REDIRECT) {
if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
return 0;
if (ct->status & IPS_NAT_MASK)
return 0;
}
if (manip == NF_NAT_MANIP_SRC)
statusbit = IPS_SRC_NAT;
else
statusbit = IPS_DST_NAT;
/* Invert if this is reply direction */
if (dir == IP_CT_DIR_REPLY)
statusbit ^= IPS_NAT_MASK;
if (!(ct->status & statusbit))
return 1;
l4proto = __nf_nat_l4proto_find(NFPROTO_IPV4, inside->ip.protocol);
if (!nf_nat_ipv4_manip_pkt(skb, hdrlen + sizeof(inside->icmp),
l4proto, &ct->tuplehash[!dir].tuple, !manip))
return 0;
if (skb->ip_summed != CHECKSUM_PARTIAL) {
/* Reloading "inside" here since manip_pkt may reallocate */
inside = (void *)skb->data + hdrlen;
inside->icmp.checksum = 0;
inside->icmp.checksum =
csum_fold(skb_checksum(skb, hdrlen,
skb->len - hdrlen, 0));
}
/* Change outer to look like the reply to an incoming packet */
nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
l4proto = __nf_nat_l4proto_find(NFPROTO_IPV4, 0);
if (!nf_nat_ipv4_manip_pkt(skb, 0, l4proto, &target, manip))
return 0;
return 1;
}
EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
static int __init nf_nat_l3proto_ipv4_init(void)
{
int err;
err = nf_nat_l4proto_register(NFPROTO_IPV4, &nf_nat_l4proto_icmp);
if (err < 0)
goto err1;
err = nf_nat_l3proto_register(&nf_nat_l3proto_ipv4);
if (err < 0)
goto err2;
return err;
err2:
nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_icmp);
err1:
return err;
}
static void __exit nf_nat_l3proto_ipv4_exit(void)
{
nf_nat_l3proto_unregister(&nf_nat_l3proto_ipv4);
nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_icmp);
}
MODULE_LICENSE("GPL");
MODULE_ALIAS("nf-nat-" __stringify(AF_INET));
module_init(nf_nat_l3proto_ipv4_init);
module_exit(nf_nat_l3proto_ipv4_exit);