2 * netfilter module to enforce network quotas
4 * Sam Johnston <samj@samj.net>
6 #include <linux/skbuff.h>
7 #include <linux/spinlock.h>
9 #include <linux/netfilter/x_tables.h>
10 #include <linux/netfilter/xt_quota.h>
12 struct xt_quota_priv {
16 MODULE_LICENSE("GPL");
17 MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
18 MODULE_DESCRIPTION("Xtables: countdown quota match");
19 MODULE_ALIAS("ipt_quota");
20 MODULE_ALIAS("ip6t_quota");
22 static DEFINE_SPINLOCK(quota_lock);
25 quota_mt(const struct sk_buff *skb, const struct xt_match_param *par)
27 struct xt_quota_info *q = (void *)par->matchinfo;
28 struct xt_quota_priv *priv = q->master;
29 bool ret = q->flags & XT_QUOTA_INVERT;
31 spin_lock_bh("a_lock);
32 if (priv->quota >= skb->len) {
33 priv->quota -= skb->len;
36 /* we do not allow even small packets from now on */
39 /* Copy quota back to matchinfo so that iptables can display it */
40 q->quota = priv->quota;
41 spin_unlock_bh("a_lock);
46 static bool quota_mt_check(const struct xt_mtchk_param *par)
48 struct xt_quota_info *q = par->matchinfo;
50 if (q->flags & ~XT_QUOTA_MASK)
53 q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
54 if (q->master == NULL)
57 q->master->quota = q->quota;
61 static void quota_mt_destroy(const struct xt_mtdtor_param *par)
63 const struct xt_quota_info *q = par->matchinfo;
68 static struct xt_match quota_mt_reg __read_mostly = {
71 .family = NFPROTO_UNSPEC,
73 .checkentry = quota_mt_check,
74 .destroy = quota_mt_destroy,
75 .matchsize = sizeof(struct xt_quota_info),
79 static int __init quota_mt_init(void)
81 return xt_register_match("a_mt_reg);
84 static void __exit quota_mt_exit(void)
86 xt_unregister_match("a_mt_reg);
89 module_init(quota_mt_init);
90 module_exit(quota_mt_exit);