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/*
* netfilter module to enforce network quotas
*
* Sam Johnston <samj@samj.net>
*/
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_quota.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
MODULE_DESCRIPTION("Xtables: countdown quota match");
MODULE_ALIAS("ipt_quota");
MODULE_ALIAS("ip6t_quota");
static DEFINE_SPINLOCK(quota_lock);
static bool
quota_mt(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct xt_match *match,
const void *matchinfo, int offset, unsigned int protoff,
bool *hotdrop)
{
struct xt_quota_info *q =
((const struct xt_quota_info *)matchinfo)->master;
bool ret = q->flags & XT_QUOTA_INVERT;
spin_lock_bh("a_lock);
if (q->quota >= skb->len) {
q->quota -= skb->len;
ret = !ret;
} else {
/* we do not allow even small packets from now on */
q->quota = 0;
}
spin_unlock_bh("a_lock);
return ret;
}
static bool
quota_mt_check(const char *tablename, const void *entry,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
struct xt_quota_info *q = matchinfo;
if (q->flags & ~XT_QUOTA_MASK)
return false;
/* For SMP, we only want to use one set of counters. */
q->master = q;
return true;
}
static struct xt_match quota_mt_reg __read_mostly = {
.name = "quota",
.revision = 0,
.family = NFPROTO_UNSPEC,
.match = quota_mt,
.checkentry = quota_mt_check,
.matchsize = sizeof(struct xt_quota_info),
.me = THIS_MODULE,
};
static int __init quota_mt_init(void)
{
return xt_register_match("a_mt_reg);
}
static void __exit quota_mt_exit(void)
{
xt_unregister_match("a_mt_reg);
}
module_init(quota_mt_init);
module_exit(quota_mt_exit);
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