[GitHub/exynos8895/android_kernel_samsung_universal8895.git] / net / ipv6 / netfilter / ip6t_HL.c

/*
 * Hop Limit modification target for ip6tables
 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
 * Based on HW's TTL module
 *
 * This software is distributed under the terms of GNU GPL
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6t_HL.h>

MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
MODULE_DESCRIPTION("IP6 tables Hop Limit modification module");
MODULE_LICENSE("GPL");

static unsigned int ip6t_hl_target(struct sk_buff *skb,
				   const struct net_device *in,
				   const struct net_device *out,
				   unsigned int hooknum,
				   const struct xt_target *target,
				   const void *targinfo)
{
	struct ipv6hdr *ip6h;
	const struct ip6t_HL_info *info = targinfo;
	int new_hl;

	if (!skb_make_writable(skb, skb->len))
		return NF_DROP;

	ip6h = ipv6_hdr(skb);

	switch (info->mode) {
		case IP6T_HL_SET:
			new_hl = info->hop_limit;
			break;
		case IP6T_HL_INC:
			new_hl = ip6h->hop_limit + info->hop_limit;
			if (new_hl > 255)
				new_hl = 255;
			break;
		case IP6T_HL_DEC:
			new_hl = ip6h->hop_limit - info->hop_limit;
			if (new_hl < 0)
				new_hl = 0;
			break;
		default:
			new_hl = ip6h->hop_limit;
			break;
	}

	ip6h->hop_limit = new_hl;

	return XT_CONTINUE;
}

static bool ip6t_hl_checkentry(const char *tablename,
		const void *entry,
		const struct xt_target *target,
		void *targinfo,
		unsigned int hook_mask)
{
	const struct ip6t_HL_info *info = targinfo;

	if (info->mode > IP6T_HL_MAXMODE) {
		printk(KERN_WARNING "ip6t_HL: invalid or unknown Mode %u\n",
			info->mode);
		return false;
	}
	if (info->mode != IP6T_HL_SET && info->hop_limit == 0) {
		printk(KERN_WARNING "ip6t_HL: increment/decrement doesn't "
			"make sense with value 0\n");
		return false;
	}
	return true;
}

static struct xt_target ip6t_HL __read_mostly = {
	.name 		= "HL",
	.family		= AF_INET6,
	.target		= ip6t_hl_target,
	.targetsize	= sizeof(struct ip6t_HL_info),
	.table		= "mangle",
	.checkentry	= ip6t_hl_checkentry,
	.me		= THIS_MODULE
};

static int __init ip6t_hl_init(void)
{
	return xt_register_target(&ip6t_HL);
}

static void __exit ip6t_hl_fini(void)
{
	xt_unregister_target(&ip6t_HL);
}

module_init(ip6t_hl_init);
module_exit(ip6t_hl_fini);
Commit	Line	Data
1ab1457c	1	/*
0ac4f893 HW	2	* Hop Limit modification target for ip6tables
	3	* Maciej Soltysiak <solt@dns.toxicfilms.tv>
	4	* Based on HW's TTL module
	5	*
	6	* This software is distributed under the terms of GNU GPL
	7	*/
	8
	9	#include <linux/module.h>
	10	#include <linux/skbuff.h>
	11	#include <linux/ip.h>
6709dbbb	12	#include <linux/ipv6.h>
0ac4f893	13
6709dbbb	14	#include <linux/netfilter/x_tables.h>
0ac4f893 HW	15	#include <linux/netfilter_ipv6/ip6t_HL.h>
	16
	17	MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
6709dbbb	18	MODULE_DESCRIPTION("IP6 tables Hop Limit modification module");
0ac4f893 HW	19	MODULE_LICENSE("GPL");
0ac4f893 HW	20
3db05fea	21	static unsigned int ip6t_hl_target(struct sk_buff *skb,
0ac4f893 HW	22	const struct net_device *in,
	23	const struct net_device *out,
	24	unsigned int hooknum,
c4986734	25	const struct xt_target *target,
fe1cb108	26	const void *targinfo)
0ac4f893 HW	27	{
	28	struct ipv6hdr *ip6h;
	29	const struct ip6t_HL_info *info = targinfo;
0ac4f893 HW	30	int new_hl;
0ac4f893 HW	31
3db05fea	32	if (!skb_make_writable(skb, skb->len))
0ac4f893 HW	33	return NF_DROP;
0ac4f893 HW	34
3db05fea	35	ip6h = ipv6_hdr(skb);
0ac4f893 HW	36
	37	switch (info->mode) {
	38	case IP6T_HL_SET:
	39	new_hl = info->hop_limit;
	40	break;
	41	case IP6T_HL_INC:
	42	new_hl = ip6h->hop_limit + info->hop_limit;
	43	if (new_hl > 255)
	44	new_hl = 255;
	45	break;
	46	case IP6T_HL_DEC:
	47	new_hl = ip6h->hop_limit - info->hop_limit;
	48	if (new_hl < 0)
	49	new_hl = 0;
	50	break;
	51	default:
	52	new_hl = ip6h->hop_limit;
	53	break;
	54	}
	55
2822b0d9	56	ip6h->hop_limit = new_hl;
0ac4f893	57
6709dbbb	58	return XT_CONTINUE;
0ac4f893 HW	59	}
0ac4f893 HW	60
e1931b78	61	static bool ip6t_hl_checkentry(const char *tablename,
2e4e6a17	62	const void *entry,
c4986734	63	const struct xt_target *target,
0ac4f893	64	void *targinfo,
0ac4f893 HW	65	unsigned int hook_mask)
0ac4f893 HW	66	{
a47362a2	67	const struct ip6t_HL_info *info = targinfo;
0ac4f893	68
0ac4f893	69	if (info->mode > IP6T_HL_MAXMODE) {
1ab1457c	70	printk(KERN_WARNING "ip6t_HL: invalid or unknown Mode %u\n",
0ac4f893	71	info->mode);
e1931b78	72	return false;
0ac4f893	73	}
7c4e36bc	74	if (info->mode != IP6T_HL_SET && info->hop_limit == 0) {
0ac4f893 HW	75	printk(KERN_WARNING "ip6t_HL: increment/decrement doesn't "
0ac4f893 HW	76	"make sense with value 0\n");
e1931b78	77	return false;
0ac4f893	78	}
e1931b78	79	return true;
0ac4f893 HW	80	}
0ac4f893 HW	81
9f15c530	82	static struct xt_target ip6t_HL __read_mostly = {
1ab1457c	83	.name = "HL",
6709dbbb	84	.family = AF_INET6,
1ab1457c	85	.target = ip6t_hl_target,
7f939713 PM	86	.targetsize = sizeof(struct ip6t_HL_info),
7f939713 PM	87	.table = "mangle",
1ab1457c	88	.checkentry = ip6t_hl_checkentry,
0ac4f893 HW	89	.me = THIS_MODULE
	90	};
	91
65b4b4e8	92	static int __init ip6t_hl_init(void)
0ac4f893	93	{
6709dbbb	94	return xt_register_target(&ip6t_HL);
0ac4f893 HW	95	}
0ac4f893 HW	96
65b4b4e8	97	static void __exit ip6t_hl_fini(void)
0ac4f893	98	{
6709dbbb	99	xt_unregister_target(&ip6t_HL);
0ac4f893 HW	100	}
0ac4f893 HW	101
65b4b4e8 AM	102	module_init(ip6t_hl_init);
65b4b4e8 AM	103	module_exit(ip6t_hl_fini);