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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>
108 lines
2.8 KiB
C
108 lines
2.8 KiB
C
/*
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* DCCP NAT protocol helper
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*
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* Copyright (c) 2005, 2006. 2008 Patrick McHardy <kaber@trash.net>
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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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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/ip.h>
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#include <linux/dccp.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_protocol.h>
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static u_int16_t dccp_port_rover;
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static bool
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dccp_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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return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
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&dccp_port_rover);
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}
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static bool
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dccp_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 = (const void *)(skb->data + iphdroff);
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struct dccp_hdr *hdr;
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unsigned int hdroff = iphdroff + iph->ihl * 4;
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__be32 oldip, newip;
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__be16 *portptr, oldport, newport;
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int hdrsize = 8; /* DCCP connection tracking guarantees this much */
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if (skb->len >= hdroff + sizeof(struct dccp_hdr))
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hdrsize = sizeof(struct dccp_hdr);
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if (!skb_make_writable(skb, hdroff + hdrsize))
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return false;
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iph = (struct iphdr *)(skb->data + iphdroff);
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hdr = (struct dccp_hdr *)(skb->data + hdroff);
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if (maniptype == IP_NAT_MANIP_SRC) {
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oldip = iph->saddr;
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newip = tuple->src.u3.ip;
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newport = tuple->src.u.dccp.port;
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portptr = &hdr->dccph_sport;
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} else {
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oldip = iph->daddr;
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newip = tuple->dst.u3.ip;
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newport = tuple->dst.u.dccp.port;
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portptr = &hdr->dccph_dport;
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}
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oldport = *portptr;
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*portptr = newport;
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if (hdrsize < sizeof(*hdr))
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return true;
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inet_proto_csum_replace4(&hdr->dccph_checksum, skb, oldip, newip, 1);
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inet_proto_csum_replace2(&hdr->dccph_checksum, skb, oldport, newport,
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0);
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return true;
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}
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static const struct nf_nat_protocol nf_nat_protocol_dccp = {
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.protonum = IPPROTO_DCCP,
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.me = THIS_MODULE,
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.manip_pkt = dccp_manip_pkt,
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.in_range = nf_nat_proto_in_range,
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.unique_tuple = dccp_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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static int __init nf_nat_proto_dccp_init(void)
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{
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return nf_nat_protocol_register(&nf_nat_protocol_dccp);
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}
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static void __exit nf_nat_proto_dccp_fini(void)
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{
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nf_nat_protocol_unregister(&nf_nat_protocol_dccp);
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}
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module_init(nf_nat_proto_dccp_init);
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module_exit(nf_nat_proto_dccp_fini);
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("DCCP NAT protocol helper");
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MODULE_LICENSE("GPL");
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