Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 1 | /* (C) 1999-2001 Paul `Rusty' Russell |
| 2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/types.h> |
| 10 | #include <linux/init.h> |
| 11 | #include <linux/ip.h> |
| 12 | #include <linux/tcp.h> |
| 13 | |
| 14 | #include <linux/netfilter.h> |
| 15 | #include <linux/netfilter/nfnetlink_conntrack.h> |
| 16 | #include <net/netfilter/nf_nat.h> |
| 17 | #include <net/netfilter/nf_nat_rule.h> |
| 18 | #include <net/netfilter/nf_nat_protocol.h> |
| 19 | #include <net/netfilter/nf_nat_core.h> |
| 20 | |
Patrick McHardy | 937e0df | 2008-03-20 15:15:47 +0100 | [diff] [blame] | 21 | static u_int16_t tcp_port_rover; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 22 | |
Jan Engelhardt | f2ea825 | 2008-04-14 11:15:53 +0200 | [diff] [blame] | 23 | static bool |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 24 | tcp_unique_tuple(struct nf_conntrack_tuple *tuple, |
| 25 | const struct nf_nat_range *range, |
| 26 | enum nf_nat_manip_type maniptype, |
| 27 | const struct nf_conn *ct) |
| 28 | { |
Patrick McHardy | 937e0df | 2008-03-20 15:15:47 +0100 | [diff] [blame] | 29 | return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct, |
| 30 | &tcp_port_rover); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 31 | } |
| 32 | |
Jan Engelhardt | f2ea825 | 2008-04-14 11:15:53 +0200 | [diff] [blame] | 33 | static bool |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 34 | tcp_manip_pkt(struct sk_buff *skb, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 35 | unsigned int iphdroff, |
| 36 | const struct nf_conntrack_tuple *tuple, |
| 37 | enum nf_nat_manip_type maniptype) |
| 38 | { |
Jan Engelhardt | 82f568f | 2008-01-31 04:52:07 -0800 | [diff] [blame] | 39 | const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 40 | struct tcphdr *hdr; |
| 41 | unsigned int hdroff = iphdroff + iph->ihl*4; |
| 42 | __be32 oldip, newip; |
| 43 | __be16 *portptr, newport, oldport; |
| 44 | int hdrsize = 8; /* TCP connection tracking guarantees this much */ |
| 45 | |
| 46 | /* this could be a inner header returned in icmp packet; in such |
| 47 | cases we cannot update the checksum field since it is outside of |
| 48 | the 8 bytes of transport layer headers we are guaranteed */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 49 | if (skb->len >= hdroff + sizeof(struct tcphdr)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 50 | hdrsize = sizeof(struct tcphdr); |
| 51 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 52 | if (!skb_make_writable(skb, hdroff + hdrsize)) |
Jan Engelhardt | f2ea825 | 2008-04-14 11:15:53 +0200 | [diff] [blame] | 53 | return false; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 54 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 55 | iph = (struct iphdr *)(skb->data + iphdroff); |
| 56 | hdr = (struct tcphdr *)(skb->data + hdroff); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 57 | |
| 58 | if (maniptype == IP_NAT_MANIP_SRC) { |
| 59 | /* Get rid of src ip and src pt */ |
| 60 | oldip = iph->saddr; |
| 61 | newip = tuple->src.u3.ip; |
| 62 | newport = tuple->src.u.tcp.port; |
| 63 | portptr = &hdr->source; |
| 64 | } else { |
| 65 | /* Get rid of dst ip and dst pt */ |
| 66 | oldip = iph->daddr; |
| 67 | newip = tuple->dst.u3.ip; |
| 68 | newport = tuple->dst.u.tcp.port; |
| 69 | portptr = &hdr->dest; |
| 70 | } |
| 71 | |
| 72 | oldport = *portptr; |
| 73 | *portptr = newport; |
| 74 | |
| 75 | if (hdrsize < sizeof(*hdr)) |
Jan Engelhardt | f2ea825 | 2008-04-14 11:15:53 +0200 | [diff] [blame] | 76 | return true; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 77 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 78 | inet_proto_csum_replace4(&hdr->check, skb, oldip, newip, 1); |
| 79 | inet_proto_csum_replace2(&hdr->check, skb, oldport, newport, 0); |
Jan Engelhardt | f2ea825 | 2008-04-14 11:15:53 +0200 | [diff] [blame] | 80 | return true; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 81 | } |
| 82 | |
Patrick McHardy | 2b628a0 | 2007-12-17 22:37:36 -0800 | [diff] [blame] | 83 | const struct nf_nat_protocol nf_nat_protocol_tcp = { |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 84 | .protonum = IPPROTO_TCP, |
| 85 | .me = THIS_MODULE, |
| 86 | .manip_pkt = tcp_manip_pkt, |
Patrick McHardy | 937e0df | 2008-03-20 15:15:47 +0100 | [diff] [blame] | 87 | .in_range = nf_nat_proto_in_range, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 88 | .unique_tuple = tcp_unique_tuple, |
Patrick McHardy | e281db5c | 2007-03-04 15:57:25 -0800 | [diff] [blame] | 89 | #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) |
Patrick McHardy | 535b57c | 2008-04-14 11:15:47 +0200 | [diff] [blame] | 90 | .range_to_nlattr = nf_nat_proto_range_to_nlattr, |
| 91 | .nlattr_to_range = nf_nat_proto_nlattr_to_range, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 92 | #endif |
| 93 | }; |