tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * netfilter module to enforce network quotas
3 *
4 * Sam Johnston <samj@samj.net>
5 */
6#include <linux/skbuff.h>
7#include <linux/slab.h>
8#include <linux/spinlock.h>
9
10#include <linux/netfilter/x_tables.h>
11#include <linux/netfilter/xt_quota.h>
12
13struct xt_quota_priv {
14 uint64_t quota;
15};
16
17MODULE_LICENSE("GPL");
18MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
19MODULE_DESCRIPTION("Xtables: countdown quota match");
20MODULE_ALIAS("ipt_quota");
21MODULE_ALIAS("ip6t_quota");
22
23static DEFINE_SPINLOCK(quota_lock);
24
25static bool
26quota_mt(const struct sk_buff *skb, const struct xt_match_param *par)
27{
28 struct xt_quota_info *q = (void *)par->matchinfo;
29 struct xt_quota_priv *priv = q->master;
30 bool ret = q->flags & XT_QUOTA_INVERT;
31
32 spin_lock_bh("a_lock);
33 if (priv->quota >= skb->len) {
34 priv->quota -= skb->len;
35 ret = !ret;
36 } else {
37 /* we do not allow even small packets from now on */
38 priv->quota = 0;
39 }
40 /* Copy quota back to matchinfo so that iptables can display it */
41 q->quota = priv->quota;
42 spin_unlock_bh("a_lock);
43
44 return ret;
45}
46
47static bool quota_mt_check(const struct xt_mtchk_param *par)
48{
49 struct xt_quota_info *q = par->matchinfo;
50
51 if (q->flags & ~XT_QUOTA_MASK)
52 return false;
53
54 q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
55 if (q->master == NULL)
56 return false;
57
58 q->master->quota = q->quota;
59 return true;
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 .me = THIS_MODULE,
78};
79
80static int __init quota_mt_init(void)
81{
82 return xt_register_match("a_mt_reg);
83}
84
85static void __exit quota_mt_exit(void)
86{
87 xt_unregister_match("a_mt_reg);
88}
89
90module_init(quota_mt_init);
91module_exit(quota_mt_exit);