[GitHub/mt8127/android_kernel_alcatel_ttab.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;

	if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
		__u8 oldtos;
		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);
		nf_csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
	} 
	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;
	__be16 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 = ((__be16 *)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;

	nf_proto_csum_replace2(&tcph->check, *pskb,
				oldval, ((__be16 *)tcph)[6], 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 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	30	struct iphdr iph = (pskb)->nh.iph;
1da177e4	31
da878c8e	32	if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
43bc0ca7	33	__u8 oldtos;
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);
43bc0ca7	40	nf_csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
1da177e4 LT	41	}
	42	return 1;
	43	}
	44
	45	/* Return 0 if there was an error. */
	46	static inline int
84fa7933	47	set_ect_tcp(struct sk_buff *pskb, const struct ipt_ECN_info einfo)
1da177e4 LT	48	{
1da177e4 LT	49	struct tcphdr _tcph, *tcph;
6a19d614	50	__be16 oldval;
1da177e4 LT	51
	52	/* Not enought header? */
	53	tcph = skb_header_pointer(pskb, (pskb)->nh.iph->ihl*4,
	54	sizeof(_tcph), &_tcph);
	55	if (!tcph)
	56	return 0;
	57
fd841326 PM	58	if ((!(einfo->operation & IPT_ECN_OP_SET_ECE) \|\|
	59	tcph->ece == einfo->proto.tcp.ece) &&
	60	((!(einfo->operation & IPT_ECN_OP_SET_CWR) \|\|
	61	tcph->cwr == einfo->proto.tcp.cwr)))
1da177e4 LT	62	return 1;
1da177e4 LT	63
089af26c	64	if (!skb_make_writable(pskb, (pskb)->nh.iph->ihl4+sizeof(*tcph)))
1da177e4 LT	65	return 0;
	66	tcph = (void )(pskb)->nh.iph + (pskb)->nh.iph->ihl4;
	67
6a19d614	68	oldval = ((__be16 *)tcph)[6];
1da177e4 LT	69	if (einfo->operation & IPT_ECN_OP_SET_ECE)
	70	tcph->ece = einfo->proto.tcp.ece;
	71	if (einfo->operation & IPT_ECN_OP_SET_CWR)
	72	tcph->cwr = einfo->proto.tcp.cwr;
1da177e4	73
43bc0ca7 AV	74	nf_proto_csum_replace2(&tcph->check, *pskb,
43bc0ca7 AV	75	oldval, ((__be16 *)tcph)[6], 0);
1da177e4 LT	76	return 1;
	77	}
	78
	79	static unsigned int
	80	target(struct sk_buff **pskb,
	81	const struct net_device *in,
	82	const struct net_device *out,
	83	unsigned int hooknum,
c4986734	84	const struct xt_target *target,
fe1cb108	85	const void *targinfo)
1da177e4 LT	86	{
	87	const struct ipt_ECN_info *einfo = targinfo;
	88
	89	if (einfo->operation & IPT_ECN_OP_SET_IP)
	90	if (!set_ect_ip(pskb, einfo))
	91	return NF_DROP;
	92
	93	if (einfo->operation & (IPT_ECN_OP_SET_ECE \| IPT_ECN_OP_SET_CWR)
	94	&& (*pskb)->nh.iph->protocol == IPPROTO_TCP)
84fa7933	95	if (!set_ect_tcp(pskb, einfo))
1da177e4 LT	96	return NF_DROP;
	97
	98	return IPT_CONTINUE;
	99	}
	100
	101	static int
	102	checkentry(const char *tablename,
2e4e6a17	103	const void *e_void,
c4986734	104	const struct xt_target *target,
1da177e4	105	void *targinfo,
1da177e4 LT	106	unsigned int hook_mask)
	107	{
	108	const struct ipt_ECN_info einfo = (struct ipt_ECN_info )targinfo;
2e4e6a17	109	const struct ipt_entry *e = e_void;
1da177e4	110
1da177e4 LT	111	if (einfo->operation & IPT_ECN_OP_MASK) {
	112	printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
	113	einfo->operation);
	114	return 0;
	115	}
	116	if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
	117	printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
	118	einfo->ip_ect);
	119	return 0;
	120	}
1da177e4 LT	121	if ((einfo->operation & (IPT_ECN_OP_SET_ECE\|IPT_ECN_OP_SET_CWR))
	122	&& (e->ip.proto != IPPROTO_TCP \|\| (e->ip.invflags & IPT_INV_PROTO))) {
	123	printk(KERN_WARNING "ECN: cannot use TCP operations on a "
	124	"non-tcp rule\n");
	125	return 0;
	126	}
1da177e4 LT	127	return 1;
	128	}
	129
	130	static struct ipt_target ipt_ecn_reg = {
	131	.name = "ECN",
	132	.target = target,
1d5cd909 PM	133	.targetsize = sizeof(struct ipt_ECN_info),
1d5cd909 PM	134	.table = "mangle",
1da177e4 LT	135	.checkentry = checkentry,
	136	.me = THIS_MODULE,
	137	};
	138
65b4b4e8	139	static int __init ipt_ecn_init(void)
1da177e4 LT	140	{
	141	return ipt_register_target(&ipt_ecn_reg);
	142	}
	143
65b4b4e8	144	static void __exit ipt_ecn_fini(void)
1da177e4 LT	145	{
	146	ipt_unregister_target(&ipt_ecn_reg);
	147	}
	148
65b4b4e8 AM	149	module_init(ipt_ecn_init);
65b4b4e8 AM	150	module_exit(ipt_ecn_fini);