1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * netfilter module to enforce network quotas
 4 *
 5 * Sam Johnston <samj@samj.net>
 6 */
 7#include <linux/skbuff.h>
 8#include <linux/slab.h>
 9#include <linux/spinlock.h>
10
11#include <linux/netfilter/x_tables.h>
12#include <linux/netfilter/xt_quota.h>
13#include <linux/module.h>
14
15struct xt_quota_priv {
16	spinlock_t	lock;
17	uint64_t	quota;
18};
19
20MODULE_LICENSE("GPL");
21MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
22MODULE_DESCRIPTION("Xtables: countdown quota match");
23MODULE_ALIAS("ipt_quota");
24MODULE_ALIAS("ip6t_quota");
25
26static bool
27quota_mt(const struct sk_buff *skb, struct xt_action_param *par)
28{
29	struct xt_quota_info *q = (void *)par->matchinfo;
30	struct xt_quota_priv *priv = q->master;
31	bool ret = q->flags & XT_QUOTA_INVERT;
32
33	spin_lock_bh(&priv->lock);
34	if (priv->quota >= skb->len) {
35		priv->quota -= skb->len;
36		ret = !ret;
37	} else {
38		/* we do not allow even small packets from now on */
39		priv->quota = 0;
40	}
41	spin_unlock_bh(&priv->lock);
42
43	return ret;
44}
45
46static int quota_mt_check(const struct xt_mtchk_param *par)
47{
48	struct xt_quota_info *q = par->matchinfo;
49
50	if (q->flags & ~XT_QUOTA_MASK)
51		return -EINVAL;
52
53	q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
54	if (q->master == NULL)
55		return -ENOMEM;
56
57	spin_lock_init(&q->master->lock);
58	q->master->quota = q->quota;
59	return 0;
60}
61
62static void quota_mt_destroy(const struct xt_mtdtor_param *par)
63{
64	const struct xt_quota_info *q = par->matchinfo;
65
66	kfree(q->master);
67}
68
69static struct xt_match quota_mt_reg __read_mostly = {
70	.name       = "quota",
71	.revision   = 0,
72	.family     = NFPROTO_UNSPEC,
73	.match      = quota_mt,
74	.checkentry = quota_mt_check,
75	.destroy    = quota_mt_destroy,
76	.matchsize  = sizeof(struct xt_quota_info),
77	.usersize   = offsetof(struct xt_quota_info, master),
78	.me         = THIS_MODULE,
79};
80
81static int __init quota_mt_init(void)
82{
83	return xt_register_match(&quota_mt_reg);
84}
85
86static void __exit quota_mt_exit(void)
87{
88	xt_unregister_match(&quota_mt_reg);
89}
90
91module_init(quota_mt_init);
92module_exit(quota_mt_exit);

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * netfilter module to enforce network quotas
 4 *
 5 * Sam Johnston <samj@samj.net>
 6 */
 7#include <linux/skbuff.h>
 8#include <linux/slab.h>
 9#include <linux/spinlock.h>
10
11#include <linux/netfilter/x_tables.h>
12#include <linux/netfilter/xt_quota.h>
13#include <linux/module.h>
14
15struct xt_quota_priv {
16	spinlock_t	lock;
17	uint64_t	quota;
18};
19
20MODULE_LICENSE("GPL");
21MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
22MODULE_DESCRIPTION("Xtables: countdown quota match");
23MODULE_ALIAS("ipt_quota");
24MODULE_ALIAS("ip6t_quota");
25
26static bool
27quota_mt(const struct sk_buff *skb, struct xt_action_param *par)
28{
29	struct xt_quota_info *q = (void *)par->matchinfo;
30	struct xt_quota_priv *priv = q->master;
31	bool ret = q->flags & XT_QUOTA_INVERT;
32
33	spin_lock_bh(&priv->lock);
34	if (priv->quota >= skb->len) {
35		priv->quota -= skb->len;
36		ret = !ret;
37	} else {
38		/* we do not allow even small packets from now on */
39		priv->quota = 0;
40	}
41	spin_unlock_bh(&priv->lock);
42
43	return ret;
44}
45
46static int quota_mt_check(const struct xt_mtchk_param *par)
47{
48	struct xt_quota_info *q = par->matchinfo;
49
50	if (q->flags & ~XT_QUOTA_MASK)
51		return -EINVAL;
52
53	q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
54	if (q->master == NULL)
55		return -ENOMEM;
56
57	spin_lock_init(&q->master->lock);
58	q->master->quota = q->quota;
59	return 0;
60}
61
62static void quota_mt_destroy(const struct xt_mtdtor_param *par)
63{
64	const struct xt_quota_info *q = par->matchinfo;
65
66	kfree(q->master);
67}
68
69static struct xt_match quota_mt_reg __read_mostly = {
70	.name       = "quota",
71	.revision   = 0,
72	.family     = NFPROTO_UNSPEC,
73	.match      = quota_mt,
74	.checkentry = quota_mt_check,
75	.destroy    = quota_mt_destroy,
76	.matchsize  = sizeof(struct xt_quota_info),
77	.usersize   = offsetof(struct xt_quota_info, master),
78	.me         = THIS_MODULE,
79};
80
81static int __init quota_mt_init(void)
82{
83	return xt_register_match(&quota_mt_reg);
84}
85
86static void __exit quota_mt_exit(void)
87{
88	xt_unregister_match(&quota_mt_reg);
89}
90
91module_init(quota_mt_init);
92module_exit(quota_mt_exit);