[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / ipv4 / netfilter / ip_nat_proto_tcp.c

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 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/netfilter.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/if.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>

static int
tcp_in_range(const struct ip_conntrack_tuple *tuple,
	     enum ip_nat_manip_type maniptype,
	     const union ip_conntrack_manip_proto *min,
	     const union ip_conntrack_manip_proto *max)
{
	u_int16_t port;

	if (maniptype == IP_NAT_MANIP_SRC)
		port = tuple->src.u.tcp.port;
	else
		port = tuple->dst.u.tcp.port;

	return ntohs(port) >= ntohs(min->tcp.port)
		&& ntohs(port) <= ntohs(max->tcp.port);
}

static int
tcp_unique_tuple(struct ip_conntrack_tuple *tuple,
		 const struct ip_nat_range *range,
		 enum ip_nat_manip_type maniptype,
		 const struct ip_conntrack *conntrack)
{
	static u_int16_t port;
	u_int16_t *portptr;
	unsigned int range_size, min, i;

	if (maniptype == IP_NAT_MANIP_SRC)
		portptr = &tuple->src.u.tcp.port;
	else
		portptr = &tuple->dst.u.tcp.port;

	/* If no range specified... */
	if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
		/* If it's dst rewrite, can't change port */
		if (maniptype == IP_NAT_MANIP_DST)
			return 0;

		/* Map privileged onto privileged. */
		if (ntohs(*portptr) < 1024) {
			/* Loose convention: >> 512 is credential passing */
			if (ntohs(*portptr)<512) {
				min = 1;
				range_size = 511 - min + 1;
			} else {
				min = 600;
				range_size = 1023 - min + 1;
			}
		} else {
			min = 1024;
			range_size = 65535 - 1024 + 1;
		}
	} else {
		min = ntohs(range->min.tcp.port);
		range_size = ntohs(range->max.tcp.port) - min + 1;
	}

	for (i = 0; i < range_size; i++, port++) {
		*portptr = htons(min + port % range_size);
		if (!ip_nat_used_tuple(tuple, conntrack)) {
			return 1;
		}
	}
	return 0;
}

static int
tcp_manip_pkt(struct sk_buff **pskb,
	      unsigned int iphdroff,
	      const struct ip_conntrack_tuple *tuple,
	      enum ip_nat_manip_type maniptype)
{
	struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff);
	struct tcphdr *hdr;
	unsigned int hdroff = iphdroff + iph->ihl*4;
	u32 oldip, newip;
	u16 *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 ((*pskb)->len >= hdroff + sizeof(struct tcphdr))
		hdrsize = sizeof(struct tcphdr);

	if (!skb_make_writable(pskb, hdroff + hdrsize))
		return 0;

	iph = (struct iphdr *)((*pskb)->data + iphdroff);
	hdr = (struct tcphdr *)((*pskb)->data + hdroff);

	if (maniptype == IP_NAT_MANIP_SRC) {
		/* Get rid of src ip and src pt */
		oldip = iph->saddr;
		newip = tuple->src.ip;
		newport = tuple->src.u.tcp.port;
		portptr = &hdr->source;
	} else {
		/* Get rid of dst ip and dst pt */
		oldip = iph->daddr;
		newip = tuple->dst.ip;
		newport = tuple->dst.u.tcp.port;
		portptr = &hdr->dest;
	}

	oldport = *portptr;
	*portptr = newport;

	if (hdrsize < sizeof(*hdr))
		return 1;

	hdr->check = ip_nat_cheat_check(~oldip, newip,
					ip_nat_cheat_check(oldport ^ 0xFFFF,
							   newport,
							   hdr->check));
	return 1;
}

struct ip_nat_protocol ip_nat_protocol_tcp = {
	.name			= "TCP",
	.protonum		= IPPROTO_TCP,
	.me			= THIS_MODULE,
	.manip_pkt		= tcp_manip_pkt,
	.in_range		= tcp_in_range,
	.unique_tuple		= tcp_unique_tuple,
#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
    defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
	.range_to_nfattr	= ip_nat_port_range_to_nfattr,
	.nfattr_to_range	= ip_nat_port_nfattr_to_range,
#endif
};
Commit	Line	Data
1da177e4 LT	1	/* (C) 1999-2001 Paul `Rusty' Russell
	2	* (C) 2002-2004 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/netfilter.h>
	12	#include <linux/ip.h>
	13	#include <linux/tcp.h>
	14	#include <linux/if.h>
080774a2	15	#include <linux/netfilter/nfnetlink_conntrack.h>
1da177e4 LT	16	#include <linux/netfilter_ipv4/ip_nat.h>
	17	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	18	#include <linux/netfilter_ipv4/ip_nat_protocol.h>
	19	#include <linux/netfilter_ipv4/ip_nat_core.h>
	20
	21	static int
	22	tcp_in_range(const struct ip_conntrack_tuple *tuple,
	23	enum ip_nat_manip_type maniptype,
	24	const union ip_conntrack_manip_proto *min,
	25	const union ip_conntrack_manip_proto *max)
	26	{
	27	u_int16_t port;
	28
	29	if (maniptype == IP_NAT_MANIP_SRC)
	30	port = tuple->src.u.tcp.port;
	31	else
	32	port = tuple->dst.u.tcp.port;
	33
	34	return ntohs(port) >= ntohs(min->tcp.port)
	35	&& ntohs(port) <= ntohs(max->tcp.port);
	36	}
	37
	38	static int
	39	tcp_unique_tuple(struct ip_conntrack_tuple *tuple,
	40	const struct ip_nat_range *range,
	41	enum ip_nat_manip_type maniptype,
	42	const struct ip_conntrack *conntrack)
	43	{
d04b4f8c PM	44	static u_int16_t port;
d04b4f8c PM	45	u_int16_t *portptr;
1da177e4 LT	46	unsigned int range_size, min, i;
	47
	48	if (maniptype == IP_NAT_MANIP_SRC)
	49	portptr = &tuple->src.u.tcp.port;
	50	else
	51	portptr = &tuple->dst.u.tcp.port;
	52
	53	/* If no range specified... */
	54	if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
	55	/* If it's dst rewrite, can't change port */
	56	if (maniptype == IP_NAT_MANIP_DST)
	57	return 0;
	58
	59	/* Map privileged onto privileged. */
	60	if (ntohs(*portptr) < 1024) {
	61	/* Loose convention: >> 512 is credential passing */
	62	if (ntohs(*portptr)<512) {
	63	min = 1;
	64	range_size = 511 - min + 1;
	65	} else {
	66	min = 600;
	67	range_size = 1023 - min + 1;
	68	}
	69	} else {
	70	min = 1024;
	71	range_size = 65535 - 1024 + 1;
	72	}
	73	} else {
	74	min = ntohs(range->min.tcp.port);
	75	range_size = ntohs(range->max.tcp.port) - min + 1;
	76	}
	77
	78	for (i = 0; i < range_size; i++, port++) {
	79	*portptr = htons(min + port % range_size);
	80	if (!ip_nat_used_tuple(tuple, conntrack)) {
	81	return 1;
	82	}
	83	}
	84	return 0;
	85	}
	86
	87	static int
	88	tcp_manip_pkt(struct sk_buff **pskb,
	89	unsigned int iphdroff,
	90	const struct ip_conntrack_tuple *tuple,
	91	enum ip_nat_manip_type maniptype)
	92	{
	93	struct iphdr iph = (struct iphdr )((*pskb)->data + iphdroff);
	94	struct tcphdr *hdr;
	95	unsigned int hdroff = iphdroff + iph->ihl*4;
	96	u32 oldip, newip;
	97	u16 *portptr, newport, oldport;
	98	int hdrsize = 8; /* TCP connection tracking guarantees this much */
	99
	100	/* this could be a inner header returned in icmp packet; in such
	101	cases we cannot update the checksum field since it is outside of
	102	the 8 bytes of transport layer headers we are guaranteed */
	103	if ((*pskb)->len >= hdroff + sizeof(struct tcphdr))
	104	hdrsize = sizeof(struct tcphdr);
	105
089af26c	106	if (!skb_make_writable(pskb, hdroff + hdrsize))
1da177e4 LT	107	return 0;
	108
	109	iph = (struct iphdr )((pskb)->data + iphdroff);
	110	hdr = (struct tcphdr )((pskb)->data + hdroff);
	111
	112	if (maniptype == IP_NAT_MANIP_SRC) {
	113	/* Get rid of src ip and src pt */
	114	oldip = iph->saddr;
	115	newip = tuple->src.ip;
	116	newport = tuple->src.u.tcp.port;
	117	portptr = &hdr->source;
	118	} else {
	119	/* Get rid of dst ip and dst pt */
	120	oldip = iph->daddr;
	121	newip = tuple->dst.ip;
	122	newport = tuple->dst.u.tcp.port;
	123	portptr = &hdr->dest;
	124	}
	125
	126	oldport = *portptr;
	127	*portptr = newport;
	128
	129	if (hdrsize < sizeof(*hdr))
	130	return 1;
	131
	132	hdr->check = ip_nat_cheat_check(~oldip, newip,
	133	ip_nat_cheat_check(oldport ^ 0xFFFF,
	134	newport,
	135	hdr->check));
	136	return 1;
	137	}
	138
373ac735 PM	139	struct ip_nat_protocol ip_nat_protocol_tcp = {
	140	.name = "TCP",
	141	.protonum = IPPROTO_TCP,
	142	.me = THIS_MODULE,
	143	.manip_pkt = tcp_manip_pkt,
	144	.in_range = tcp_in_range,
	145	.unique_tuple = tcp_unique_tuple,
080774a2 HW	146	#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) \|\| \
080774a2 HW	147	defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
373ac735 PM	148	.range_to_nfattr = ip_nat_port_range_to_nfattr,
373ac735 PM	149	.nfattr_to_range = ip_nat_port_nfattr_to_range,
080774a2	150	#endif
1da177e4	151	};