2005-04-17 02:20:36 +04:00
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 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/netfilter.h>
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#include <linux/ip.h>
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#include <linux/icmp.h>
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#include <linux/if.h>
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_core.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/netfilter_ipv4/ip_nat_protocol.h>
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static int
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icmp_in_range(const struct ip_conntrack_tuple *tuple,
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enum ip_nat_manip_type maniptype,
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const union ip_conntrack_manip_proto *min,
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const union ip_conntrack_manip_proto *max)
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{
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return (tuple->src.u.icmp.id >= min->icmp.id
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&& tuple->src.u.icmp.id <= max->icmp.id);
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}
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static int
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icmp_unique_tuple(struct ip_conntrack_tuple *tuple,
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const struct ip_nat_range *range,
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enum ip_nat_manip_type maniptype,
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const struct ip_conntrack *conntrack)
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{
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static u_int16_t id;
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2005-07-22 23:51:38 +04:00
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unsigned int range_size;
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2005-04-17 02:20:36 +04:00
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unsigned int i;
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2005-07-22 23:51:38 +04:00
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range_size = ntohs(range->max.icmp.id) - ntohs(range->min.icmp.id) + 1;
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2005-04-17 02:20:36 +04:00
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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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2005-07-22 23:51:38 +04:00
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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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2005-04-17 02:20:36 +04:00
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if (!ip_nat_used_tuple(tuple, conntrack))
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return 1;
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}
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return 0;
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}
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static int
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icmp_manip_pkt(struct sk_buff **pskb,
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unsigned int iphdroff,
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const struct ip_conntrack_tuple *tuple,
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enum ip_nat_manip_type maniptype)
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{
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struct iphdr *iph = (struct iphdr *)((*pskb)->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_ip_make_writable(pskb, hdroff + sizeof(*hdr)))
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return 0;
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hdr = (struct icmphdr *)((*pskb)->data + hdroff);
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hdr->checksum = ip_nat_cheat_check(hdr->un.echo.id ^ 0xFFFF,
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tuple->src.u.icmp.id,
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hdr->checksum);
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hdr->un.echo.id = tuple->src.u.icmp.id;
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return 1;
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}
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static unsigned int
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icmp_print(char *buffer,
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const struct ip_conntrack_tuple *match,
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const struct ip_conntrack_tuple *mask)
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{
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unsigned int len = 0;
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if (mask->src.u.icmp.id)
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len += sprintf(buffer + len, "id=%u ",
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ntohs(match->src.u.icmp.id));
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if (mask->dst.u.icmp.type)
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len += sprintf(buffer + len, "type=%u ",
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ntohs(match->dst.u.icmp.type));
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if (mask->dst.u.icmp.code)
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len += sprintf(buffer + len, "code=%u ",
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ntohs(match->dst.u.icmp.code));
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return len;
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}
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static unsigned int
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icmp_print_range(char *buffer, const struct ip_nat_range *range)
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{
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if (range->min.icmp.id != 0 || range->max.icmp.id != 0xFFFF)
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return sprintf(buffer, "id %u-%u ",
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ntohs(range->min.icmp.id),
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ntohs(range->max.icmp.id));
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else return 0;
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}
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struct ip_nat_protocol ip_nat_protocol_icmp
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= { "ICMP", IPPROTO_ICMP,
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icmp_manip_pkt,
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icmp_in_range,
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icmp_unique_tuple,
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icmp_print,
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icmp_print_range
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};
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