| /* (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/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_rule.h> |
| #include <net/netfilter/nf_nat_protocol.h> |
| |
| static int |
| 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 int |
| icmp_unique_tuple(struct nf_conntrack_tuple *tuple, |
| const struct nf_nat_range *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.icmp.id) - ntohs(range->min.icmp.id) + 1; |
| /* If no range specified... */ |
| if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) |
| range_size = 0xFFFF; |
| |
| for (i = 0; i < range_size; i++, id++) { |
| tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) + |
| (id % range_size)); |
| if (!nf_nat_used_tuple(tuple, ct)) |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int |
| icmp_manip_pkt(struct sk_buff *skb, |
| unsigned int iphdroff, |
| const struct nf_conntrack_tuple *tuple, |
| enum nf_nat_manip_type maniptype) |
| { |
| struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff); |
| struct icmphdr *hdr; |
| unsigned int hdroff = iphdroff + iph->ihl*4; |
| |
| if (!skb_make_writable(skb, hdroff + sizeof(*hdr))) |
| return 0; |
| |
| hdr = (struct icmphdr *)(skb->data + hdroff); |
| inet_proto_csum_replace2(&hdr->checksum, skb, |
| hdr->un.echo.id, tuple->src.u.icmp.id, 0); |
| hdr->un.echo.id = tuple->src.u.icmp.id; |
| return 1; |
| } |
| |
| struct nf_nat_protocol nf_nat_protocol_icmp = { |
| .name = "ICMP", |
| .protonum = IPPROTO_ICMP, |
| .me = THIS_MODULE, |
| .manip_pkt = icmp_manip_pkt, |
| .in_range = icmp_in_range, |
| .unique_tuple = icmp_unique_tuple, |
| #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) |
| .range_to_nlattr = nf_nat_port_range_to_nlattr, |
| .nlattr_to_range = nf_nat_port_nlattr_to_range, |
| #endif |
| }; |