diff options
author | Patrick McHardy <kaber@trash.net> | 2012-08-26 19:14:06 +0200 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2012-08-30 03:00:14 +0200 |
commit | c7232c9979cba684c50b64c513c4a83c9aa70563 (patch) | |
tree | dbe0fdac62191d85935f5a3dfe815c1b1add60f9 /net/netfilter/nf_nat_proto_tcp.c | |
parent | 051966c0c644a1c96092d4206e00704ade813c9a (diff) |
netfilter: add protocol independent NAT core
Convert the IPv4 NAT implementation to a protocol independent core and
address family specific modules.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/netfilter/nf_nat_proto_tcp.c')
-rw-r--r-- | net/netfilter/nf_nat_proto_tcp.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_proto_tcp.c b/net/netfilter/nf_nat_proto_tcp.c new file mode 100644 index 00000000000..83ec8a6e4c3 --- /dev/null +++ b/net/netfilter/nf_nat_proto_tcp.c @@ -0,0 +1,85 @@ +/* (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/export.h> +#include <linux/tcp.h> + +#include <linux/netfilter.h> +#include <linux/netfilter/nfnetlink_conntrack.h> +#include <net/netfilter/nf_nat.h> +#include <net/netfilter/nf_nat_l3proto.h> +#include <net/netfilter/nf_nat_l4proto.h> +#include <net/netfilter/nf_nat_core.h> + +static u16 tcp_port_rover; + +static void +tcp_unique_tuple(const struct nf_nat_l3proto *l3proto, + struct nf_conntrack_tuple *tuple, + const struct nf_nat_range *range, + enum nf_nat_manip_type maniptype, + const struct nf_conn *ct) +{ + nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct, + &tcp_port_rover); +} + +static bool +tcp_manip_pkt(struct sk_buff *skb, + const struct nf_nat_l3proto *l3proto, + unsigned int iphdroff, unsigned int hdroff, + const struct nf_conntrack_tuple *tuple, + enum nf_nat_manip_type maniptype) +{ + struct tcphdr *hdr; + __be16 *portptr, newport, oldport; + int hdrsize = 8; /* TCP connection tracking guarantees this much */ + + /* this could be a inner header returned in icmp packet; in such + cases we cannot update the checksum field since it is outside of + the 8 bytes of transport layer headers we are guaranteed */ + if (skb->len >= hdroff + sizeof(struct tcphdr)) + hdrsize = sizeof(struct tcphdr); + + if (!skb_make_writable(skb, hdroff + hdrsize)) + return false; + + hdr = (struct tcphdr *)(skb->data + hdroff); + + if (maniptype == NF_NAT_MANIP_SRC) { + /* Get rid of src port */ + newport = tuple->src.u.tcp.port; + portptr = &hdr->source; + } else { + /* Get rid of dst port */ + newport = tuple->dst.u.tcp.port; + portptr = &hdr->dest; + } + + oldport = *portptr; + *portptr = newport; + + if (hdrsize < sizeof(*hdr)) + return true; + + l3proto->csum_update(skb, iphdroff, &hdr->check, tuple, maniptype); + inet_proto_csum_replace2(&hdr->check, skb, oldport, newport, 0); + return true; +} + +const struct nf_nat_l4proto nf_nat_l4proto_tcp = { + .l4proto = IPPROTO_TCP, + .manip_pkt = tcp_manip_pkt, + .in_range = nf_nat_l4proto_in_range, + .unique_tuple = tcp_unique_tuple, +#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) + .nlattr_to_range = nf_nat_l4proto_nlattr_to_range, +#endif +}; |