[net-next-2.6.git] / net / bridge / netfilter / ebt_limit.c

/*
 *  ebt_limit
 *
 *	Authors:
 *	Tom Marshall <tommy@home.tig-grr.com>
 *
 *	Mostly copied from netfilter's ipt_limit.c, see that file for
 *	more explanation
 *
 *  September, 2003
 *
 */
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/spinlock.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_limit.h>

static DEFINE_SPINLOCK(limit_lock);

#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))

#define _POW2_BELOW2(x) ((x)|((x)>>1))
#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)

#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)

static int ebt_limit_match(const struct sk_buff *skb,
   const struct net_device *in, const struct net_device *out,
   const void *data, unsigned int datalen)
{
	struct ebt_limit_info *info = (struct ebt_limit_info *)data;
	unsigned long now = jiffies;

	spin_lock_bh(&limit_lock);
	info->credit += (now - xchg(&info->prev, now)) * CREDITS_PER_JIFFY;
	if (info->credit > info->credit_cap)
		info->credit = info->credit_cap;

	if (info->credit >= info->cost) {
		/* We're not limited. */
		info->credit -= info->cost;
		spin_unlock_bh(&limit_lock);
		return EBT_MATCH;
	}

	spin_unlock_bh(&limit_lock);
	return EBT_NOMATCH;
}

/* Precision saver. */
static u_int32_t
user2credits(u_int32_t user)
{
	/* If multiplying would overflow... */
	if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
		/* Divide first. */
		return (user / EBT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;

	return (user * HZ * CREDITS_PER_JIFFY) / EBT_LIMIT_SCALE;
}

static int ebt_limit_check(const char *tablename, unsigned int hookmask,
   const struct ebt_entry *e, void *data, unsigned int datalen)
{
	struct ebt_limit_info *info = data;

	/* Check for overflow. */
	if (info->burst == 0 ||
	    user2credits(info->avg * info->burst) < user2credits(info->avg)) {
		printk("Overflow in ebt_limit, try lower: %u/%u\n",
			info->avg, info->burst);
		return -EINVAL;
	}

	/* User avg in seconds * EBT_LIMIT_SCALE: convert to jiffies * 128. */
	info->prev = jiffies;
	info->credit = user2credits(info->avg * info->burst);
	info->credit_cap = user2credits(info->avg * info->burst);
	info->cost = user2credits(info->avg);
	return 0;
}

static struct ebt_match ebt_limit_reg __read_mostly = {
	.name		= EBT_LIMIT_MATCH,
	.match		= ebt_limit_match,
	.check		= ebt_limit_check,
	.matchsize	= XT_ALIGN(sizeof(struct ebt_limit_info)),
	.me		= THIS_MODULE,
};

static int __init ebt_limit_init(void)
{
	return ebt_register_match(&ebt_limit_reg);
}

static void __exit ebt_limit_fini(void)
{
	ebt_unregister_match(&ebt_limit_reg);
}

module_init(ebt_limit_init);
module_exit(ebt_limit_fini);
MODULE_DESCRIPTION("Ebtables: Rate-limit match");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* ebt_limit
	3	*
	4	* Authors:
	5	* Tom Marshall <tommy@home.tig-grr.com>
	6	*
	7	* Mostly copied from netfilter's ipt_limit.c, see that file for
	8	* more explanation
	9	*
	10	* September, 2003
	11	*
	12	*/
1da177e4	13	#include <linux/module.h>
1da177e4 LT	14	#include <linux/netdevice.h>
1da177e4 LT	15	#include <linux/spinlock.h>
18219d3f JE	16	#include <linux/netfilter/x_tables.h>
	17	#include <linux/netfilter_bridge/ebtables.h>
	18	#include <linux/netfilter_bridge/ebt_limit.h>
1da177e4 LT	19
	20	static DEFINE_SPINLOCK(limit_lock);
	21
	22	#define MAX_CPJ (0xFFFFFFFF / (HZ6060*24))
	23
	24	#define _POW2_BELOW2(x) ((x)\|((x)>>1))
	25	#define _POW2_BELOW4(x) (_POW2_BELOW2(x)\|_POW2_BELOW2((x)>>2))
	26	#define _POW2_BELOW8(x) (_POW2_BELOW4(x)\|_POW2_BELOW4((x)>>4))
	27	#define _POW2_BELOW16(x) (_POW2_BELOW8(x)\|_POW2_BELOW8((x)>>8))
	28	#define _POW2_BELOW32(x) (_POW2_BELOW16(x)\|_POW2_BELOW16((x)>>16))
	29	#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
	30
	31	#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
	32
	33	static int ebt_limit_match(const struct sk_buff *skb,
	34	const struct net_device in, const struct net_device out,
	35	const void *data, unsigned int datalen)
	36	{
	37	struct ebt_limit_info info = (struct ebt_limit_info )data;
	38	unsigned long now = jiffies;
	39
	40	spin_lock_bh(&limit_lock);
	41	info->credit += (now - xchg(&info->prev, now)) * CREDITS_PER_JIFFY;
	42	if (info->credit > info->credit_cap)
	43	info->credit = info->credit_cap;
	44
	45	if (info->credit >= info->cost) {
	46	/* We're not limited. */
	47	info->credit -= info->cost;
	48	spin_unlock_bh(&limit_lock);
	49	return EBT_MATCH;
	50	}
	51
	52	spin_unlock_bh(&limit_lock);
	53	return EBT_NOMATCH;
	54	}
	55
	56	/* Precision saver. */
	57	static u_int32_t
	58	user2credits(u_int32_t user)
	59	{
	60	/* If multiplying would overflow... */
	61	if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
	62	/* Divide first. */
	63	return (user / EBT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
	64
	65	return (user * HZ * CREDITS_PER_JIFFY) / EBT_LIMIT_SCALE;
	66	}
	67
	68	static int ebt_limit_check(const char *tablename, unsigned int hookmask,
	69	const struct ebt_entry e, void data, unsigned int datalen)
	70	{
abfdf1c4	71	struct ebt_limit_info *info = data;
1da177e4	72
1da177e4 LT	73	/* Check for overflow. */
	74	if (info->burst == 0 \|\|
	75	user2credits(info->avg * info->burst) < user2credits(info->avg)) {
	76	printk("Overflow in ebt_limit, try lower: %u/%u\n",
	77	info->avg, info->burst);
	78	return -EINVAL;
	79	}
	80
	81	/* User avg in seconds * EBT_LIMIT_SCALE: convert to jiffies * 128. */
	82	info->prev = jiffies;
	83	info->credit = user2credits(info->avg * info->burst);
	84	info->credit_cap = user2credits(info->avg * info->burst);
	85	info->cost = user2credits(info->avg);
	86	return 0;
	87	}
	88
30083c95	89	static struct ebt_match ebt_limit_reg __read_mostly = {
1da177e4 LT	90	.name = EBT_LIMIT_MATCH,
	91	.match = ebt_limit_match,
	92	.check = ebt_limit_check,
18219d3f	93	.matchsize = XT_ALIGN(sizeof(struct ebt_limit_info)),
1da177e4 LT	94	.me = THIS_MODULE,
	95	};
	96
65b4b4e8	97	static int __init ebt_limit_init(void)
1da177e4 LT	98	{
	99	return ebt_register_match(&ebt_limit_reg);
	100	}
	101
65b4b4e8	102	static void __exit ebt_limit_fini(void)
1da177e4 LT	103	{
	104	ebt_unregister_match(&ebt_limit_reg);
	105	}
	106
65b4b4e8 AM	107	module_init(ebt_limit_init);
65b4b4e8 AM	108	module_exit(ebt_limit_fini);
f776c4cd	109	MODULE_DESCRIPTION("Ebtables: Rate-limit match");
1da177e4	110	MODULE_LICENSE("GPL");