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![Jan Engelhardt](/assets/img/avatar_default.png)
Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
84 lines
2.4 KiB
C
84 lines
2.4 KiB
C
/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/ip.h>
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#include <linux/icmp.h>
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#include <linux/netfilter.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_core.h>
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#include <net/netfilter/nf_nat_rule.h>
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#include <net/netfilter/nf_nat_protocol.h>
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static bool
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icmp_in_range(const struct nf_conntrack_tuple *tuple,
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enum nf_nat_manip_type maniptype,
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const union nf_conntrack_man_proto *min,
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const union nf_conntrack_man_proto *max)
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{
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return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
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ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
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}
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static bool
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icmp_unique_tuple(struct nf_conntrack_tuple *tuple,
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const struct nf_nat_range *range,
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enum nf_nat_manip_type maniptype,
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const struct nf_conn *ct)
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{
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static u_int16_t id;
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unsigned int range_size;
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unsigned int i;
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range_size = ntohs(range->max.icmp.id) - ntohs(range->min.icmp.id) + 1;
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/* If no range specified... */
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if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
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range_size = 0xFFFF;
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for (i = 0; i < range_size; i++, id++) {
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tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) +
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(id % range_size));
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if (!nf_nat_used_tuple(tuple, ct))
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return true;
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}
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return false;
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}
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static bool
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icmp_manip_pkt(struct sk_buff *skb,
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unsigned int iphdroff,
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const struct nf_conntrack_tuple *tuple,
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enum nf_nat_manip_type maniptype)
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{
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const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
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struct icmphdr *hdr;
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unsigned int hdroff = iphdroff + iph->ihl*4;
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if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
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return false;
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hdr = (struct icmphdr *)(skb->data + hdroff);
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inet_proto_csum_replace2(&hdr->checksum, skb,
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hdr->un.echo.id, tuple->src.u.icmp.id, 0);
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hdr->un.echo.id = tuple->src.u.icmp.id;
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return true;
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}
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const struct nf_nat_protocol nf_nat_protocol_icmp = {
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.protonum = IPPROTO_ICMP,
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.me = THIS_MODULE,
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.manip_pkt = icmp_manip_pkt,
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.in_range = icmp_in_range,
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.unique_tuple = icmp_unique_tuple,
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#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
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.range_to_nlattr = nf_nat_proto_range_to_nlattr,
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.nlattr_to_range = nf_nat_proto_nlattr_to_range,
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#endif
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};
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