Staging
v0.5.2
v0.5.2
nf_nat_proto_icmp.c
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
*
* 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/init.h>
#include <linux/export.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netfilter.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l4proto.h>
static bool
icmp_in_range(const struct nf_conntrack_tuple *tuple,
enum nf_nat_manip_type maniptype,
const union nf_conntrack_man_proto *min,
const union nf_conntrack_man_proto *max)
{
return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
}
static void
icmp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
static u_int16_t id;
unsigned int range_size;
unsigned int i;
range_size = ntohs(range->max_proto.icmp.id) -
ntohs(range->min_proto.icmp.id) + 1;
/* If no range specified... */
if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
range_size = 0xFFFF;
for (i = 0; ; ++id) {
tuple->src.u.icmp.id = htons(ntohs(range->min_proto.icmp.id) +
(id % range_size));
if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
return;
}
return;
}
static bool
icmp_manip_pkt(struct sk_buff *skb,
const struct nf_nat_l3proto *l3proto,
unsigned int iphdroff, unsigned int hdroff,
const struct nf_conntrack_tuple *tuple,
enum nf_nat_manip_type maniptype)
{
struct icmphdr *hdr;
if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
return false;
hdr = (struct icmphdr *)(skb->data + hdroff);
inet_proto_csum_replace2(&hdr->checksum, skb,
hdr->un.echo.id, tuple->src.u.icmp.id, false);
hdr->un.echo.id = tuple->src.u.icmp.id;
return true;
}
const struct nf_nat_l4proto nf_nat_l4proto_icmp = {
.l4proto = IPPROTO_ICMP,
.manip_pkt = icmp_manip_pkt,
.in_range = icmp_in_range,
.unique_tuple = icmp_unique_tuple,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
.nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
#endif
};