[deliverable/linux.git] / net / ipv4 / netfilter / ipt_ECN.c

/* iptables module for the IPv4 and TCP ECN bits, Version 1.5
 *
 * (C) 2002 by Harald Welte <laforge@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.
 *
 * ipt_ECN.c,v 1.5 2002/08/18 19:36:51 laforge Exp
*/

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/checksum.h>

#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ECN.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("iptables ECN modification module");

/* set ECT codepoint from IP header.
 * 	return 0 if there was an error. */
static inline int
set_ect_ip(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
{
	struct iphdr *iph = (*pskb)->nh.iph;
	u_int16_t oldtos;

	if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
		if (!skb_make_writable(pskb, sizeof(struct iphdr)))
			return 0;
		iph = (*pskb)->nh.iph;
		oldtos = iph->tos;
		iph->tos &= ~IPT_ECN_IP_MASK;
		iph->tos |= (einfo->ip_ect & IPT_ECN_IP_MASK);
		iph->check = nf_csum_update(oldtos ^ 0xFFFF, iph->tos,
					    iph->check);
	} 
	return 1;
}

/* Return 0 if there was an error. */
static inline int
set_ect_tcp(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
{
	struct tcphdr _tcph, *tcph;
	u_int16_t oldval;

	/* Not enought header? */
	tcph = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
				  sizeof(_tcph), &_tcph);
	if (!tcph)
		return 0;

	if ((!(einfo->operation & IPT_ECN_OP_SET_ECE) ||
	     tcph->ece == einfo->proto.tcp.ece) &&
	    ((!(einfo->operation & IPT_ECN_OP_SET_CWR) ||
	     tcph->cwr == einfo->proto.tcp.cwr)))
		return 1;

	if (!skb_make_writable(pskb, (*pskb)->nh.iph->ihl*4+sizeof(*tcph)))
		return 0;
	tcph = (void *)(*pskb)->nh.iph + (*pskb)->nh.iph->ihl*4;

	oldval = ((u_int16_t *)tcph)[6];
	if (einfo->operation & IPT_ECN_OP_SET_ECE)
		tcph->ece = einfo->proto.tcp.ece;
	if (einfo->operation & IPT_ECN_OP_SET_CWR)
		tcph->cwr = einfo->proto.tcp.cwr;

	tcph->check = nf_proto_csum_update((*pskb),
					   oldval ^ 0xFFFF,
					   ((u_int16_t *)tcph)[6],
					   tcph->check, 0);
	return 1;
}

static unsigned int
target(struct sk_buff **pskb,
       const struct net_device *in,
       const struct net_device *out,
       unsigned int hooknum,
       const struct xt_target *target,
       const void *targinfo)
{
	const struct ipt_ECN_info *einfo = targinfo;

	if (einfo->operation & IPT_ECN_OP_SET_IP)
		if (!set_ect_ip(pskb, einfo))
			return NF_DROP;

	if (einfo->operation & (IPT_ECN_OP_SET_ECE | IPT_ECN_OP_SET_CWR)
	    && (*pskb)->nh.iph->protocol == IPPROTO_TCP)
		if (!set_ect_tcp(pskb, einfo))
			return NF_DROP;

	return IPT_CONTINUE;
}

static int
checkentry(const char *tablename,
	   const void *e_void,
	   const struct xt_target *target,
           void *targinfo,
           unsigned int targinfosize,
           unsigned int hook_mask)
{
	const struct ipt_ECN_info *einfo = (struct ipt_ECN_info *)targinfo;
	const struct ipt_entry *e = e_void;

	if (einfo->operation & IPT_ECN_OP_MASK) {
		printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
			einfo->operation);
		return 0;
	}
	if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
		printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
			einfo->ip_ect);
		return 0;
	}
	if ((einfo->operation & (IPT_ECN_OP_SET_ECE|IPT_ECN_OP_SET_CWR))
	    && (e->ip.proto != IPPROTO_TCP || (e->ip.invflags & IPT_INV_PROTO))) {
		printk(KERN_WARNING "ECN: cannot use TCP operations on a "
		       "non-tcp rule\n");
		return 0;
	}
	return 1;
}

static struct ipt_target ipt_ecn_reg = {
	.name		= "ECN",
	.target		= target,
	.targetsize	= sizeof(struct ipt_ECN_info),
	.table		= "mangle",
	.checkentry	= checkentry,
	.me		= THIS_MODULE,
};

static int __init ipt_ecn_init(void)
{
	return ipt_register_target(&ipt_ecn_reg);
}

static void __exit ipt_ecn_fini(void)
{
	ipt_unregister_target(&ipt_ecn_reg);
}

module_init(ipt_ecn_init);
module_exit(ipt_ecn_fini);
Commit	Line	Data
1da177e4 LT	1	/* iptables module for the IPv4 and TCP ECN bits, Version 1.5
	2	*
	3	* (C) 2002 by Harald Welte <laforge@netfilter.org>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*
	9	* ipt_ECN.c,v 1.5 2002/08/18 19:36:51 laforge Exp
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/ip.h>
	15	#include <linux/tcp.h>
	16	#include <net/checksum.h>
	17
	18	#include <linux/netfilter_ipv4/ip_tables.h>
	19	#include <linux/netfilter_ipv4/ipt_ECN.h>
	20
	21	MODULE_LICENSE("GPL");
	22	MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
	23	MODULE_DESCRIPTION("iptables ECN modification module");
	24
	25	/* set ECT codepoint from IP header.
	26	* return 0 if there was an error. */
	27	static inline int
	28	set_ect_ip(struct sk_buff *pskb, const struct ipt_ECN_info einfo)
	29	{
da878c8e PM	30	struct iphdr iph = (pskb)->nh.iph;
da878c8e PM	31	u_int16_t oldtos;
1da177e4	32
da878c8e	33	if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
089af26c	34	if (!skb_make_writable(pskb, sizeof(struct iphdr)))
1da177e4	35	return 0;
da878c8e PM	36	iph = (*pskb)->nh.iph;
	37	oldtos = iph->tos;
	38	iph->tos &= ~IPT_ECN_IP_MASK;
	39	iph->tos \|= (einfo->ip_ect & IPT_ECN_IP_MASK);
	40	iph->check = nf_csum_update(oldtos ^ 0xFFFF, iph->tos,
	41	iph->check);
1da177e4 LT	42	}
	43	return 1;
	44	}
	45
	46	/* Return 0 if there was an error. */
	47	static inline int
84fa7933	48	set_ect_tcp(struct sk_buff *pskb, const struct ipt_ECN_info einfo)
1da177e4 LT	49	{
1da177e4 LT	50	struct tcphdr _tcph, *tcph;
4cf411de	51	u_int16_t oldval;
1da177e4 LT	52
	53	/* Not enought header? */
	54	tcph = skb_header_pointer(pskb, (pskb)->nh.iph->ihl*4,
	55	sizeof(_tcph), &_tcph);
	56	if (!tcph)
	57	return 0;
	58
fd841326 PM	59	if ((!(einfo->operation & IPT_ECN_OP_SET_ECE) \|\|
	60	tcph->ece == einfo->proto.tcp.ece) &&
	61	((!(einfo->operation & IPT_ECN_OP_SET_CWR) \|\|
	62	tcph->cwr == einfo->proto.tcp.cwr)))
1da177e4 LT	63	return 1;
1da177e4 LT	64
089af26c	65	if (!skb_make_writable(pskb, (pskb)->nh.iph->ihl4+sizeof(*tcph)))
1da177e4 LT	66	return 0;
	67	tcph = (void )(pskb)->nh.iph + (pskb)->nh.iph->ihl4;
	68
4cf411de	69	oldval = ((u_int16_t *)tcph)[6];
1da177e4 LT	70	if (einfo->operation & IPT_ECN_OP_SET_ECE)
	71	tcph->ece = einfo->proto.tcp.ece;
	72	if (einfo->operation & IPT_ECN_OP_SET_CWR)
	73	tcph->cwr = einfo->proto.tcp.cwr;
1da177e4	74
4cf411de PM	75	tcph->check = nf_proto_csum_update((*pskb),
	76	oldval ^ 0xFFFF,
	77	((u_int16_t *)tcph)[6],
	78	tcph->check, 0);
1da177e4 LT	79	return 1;
	80	}
	81
	82	static unsigned int
	83	target(struct sk_buff **pskb,
	84	const struct net_device *in,
	85	const struct net_device *out,
	86	unsigned int hooknum,
c4986734	87	const struct xt_target *target,
fe1cb108	88	const void *targinfo)
1da177e4 LT	89	{
	90	const struct ipt_ECN_info *einfo = targinfo;
	91
	92	if (einfo->operation & IPT_ECN_OP_SET_IP)
	93	if (!set_ect_ip(pskb, einfo))
	94	return NF_DROP;
	95
	96	if (einfo->operation & (IPT_ECN_OP_SET_ECE \| IPT_ECN_OP_SET_CWR)
	97	&& (*pskb)->nh.iph->protocol == IPPROTO_TCP)
84fa7933	98	if (!set_ect_tcp(pskb, einfo))
1da177e4 LT	99	return NF_DROP;
	100
	101	return IPT_CONTINUE;
	102	}
	103
	104	static int
	105	checkentry(const char *tablename,
2e4e6a17	106	const void *e_void,
c4986734	107	const struct xt_target *target,
1da177e4 LT	108	void *targinfo,
	109	unsigned int targinfosize,
	110	unsigned int hook_mask)
	111	{
	112	const struct ipt_ECN_info einfo = (struct ipt_ECN_info )targinfo;
2e4e6a17	113	const struct ipt_entry *e = e_void;
1da177e4	114
1da177e4 LT	115	if (einfo->operation & IPT_ECN_OP_MASK) {
	116	printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
	117	einfo->operation);
	118	return 0;
	119	}
	120	if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
	121	printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
	122	einfo->ip_ect);
	123	return 0;
	124	}
1da177e4 LT	125	if ((einfo->operation & (IPT_ECN_OP_SET_ECE\|IPT_ECN_OP_SET_CWR))
	126	&& (e->ip.proto != IPPROTO_TCP \|\| (e->ip.invflags & IPT_INV_PROTO))) {
	127	printk(KERN_WARNING "ECN: cannot use TCP operations on a "
	128	"non-tcp rule\n");
	129	return 0;
	130	}
1da177e4 LT	131	return 1;
	132	}
	133
	134	static struct ipt_target ipt_ecn_reg = {
	135	.name = "ECN",
	136	.target = target,
1d5cd909 PM	137	.targetsize = sizeof(struct ipt_ECN_info),
1d5cd909 PM	138	.table = "mangle",
1da177e4 LT	139	.checkentry = checkentry,
	140	.me = THIS_MODULE,
	141	};
	142
65b4b4e8	143	static int __init ipt_ecn_init(void)
1da177e4 LT	144	{
	145	return ipt_register_target(&ipt_ecn_reg);
	146	}
	147
65b4b4e8	148	static void __exit ipt_ecn_fini(void)
1da177e4 LT	149	{
	150	ipt_unregister_target(&ipt_ecn_reg);
	151	}
	152
65b4b4e8 AM	153	module_init(ipt_ecn_init);
65b4b4e8 AM	154	module_exit(ipt_ecn_fini);