1/*
2 * netfilter module to enforce network quotas
3 *
4 * Sam Johnston <samj@samj.net>
5 */
6#include <linux/skbuff.h>
7#include <linux/spinlock.h>
8
9#include <linux/netfilter/x_tables.h>
10#include <linux/netfilter/xt_quota.h>
11
12MODULE_LICENSE("GPL");
13MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
14MODULE_ALIAS("ipt_quota");
15MODULE_ALIAS("ip6t_quota");
16
17static DEFINE_SPINLOCK(quota_lock);
18
19static int
20match(const struct sk_buff *skb,
21      const struct net_device *in, const struct net_device *out,
22      const struct xt_match *match, const void *matchinfo,
23      int offset, unsigned int protoff, int *hotdrop)
24{
25	struct xt_quota_info *q = ((struct xt_quota_info *)matchinfo)->master;
26	int ret = q->flags & XT_QUOTA_INVERT ? 1 : 0;
27
28	spin_lock_bh(&quota_lock);
29	if (q->quota >= skb->len) {
30		q->quota -= skb->len;
31		ret ^= 1;
32	} else {
33		/* we do not allow even small packets from now on */
34		q->quota = 0;
35	}
36	spin_unlock_bh(&quota_lock);
37
38	return ret;
39}
40
41static int
42checkentry(const char *tablename, const void *entry,
43	   const struct xt_match *match, void *matchinfo,
44	   unsigned int hook_mask)
45{
46	struct xt_quota_info *q = (struct xt_quota_info *)matchinfo;
47
48	if (q->flags & ~XT_QUOTA_MASK)
49		return 0;
50	/* For SMP, we only want to use one set of counters. */
51	q->master = q;
52	return 1;
53}
54
55static struct xt_match xt_quota_match[] = {
56	{
57		.name		= "quota",
58		.family		= AF_INET,
59		.checkentry	= checkentry,
60		.match		= match,
61		.matchsize	= sizeof(struct xt_quota_info),
62		.me		= THIS_MODULE
63	},
64	{
65		.name		= "quota",
66		.family		= AF_INET6,
67		.checkentry	= checkentry,
68		.match		= match,
69		.matchsize	= sizeof(struct xt_quota_info),
70		.me		= THIS_MODULE
71	},
72};
73
74static int __init xt_quota_init(void)
75{
76	return xt_register_matches(xt_quota_match, ARRAY_SIZE(xt_quota_match));
77}
78
79static void __exit xt_quota_fini(void)
80{
81	xt_unregister_matches(xt_quota_match, ARRAY_SIZE(xt_quota_match));
82}
83
84module_init(xt_quota_init);
85module_exit(xt_quota_fini);
86