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/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_DESCRIPTION("Xtables: countdown quota match");
15MODULE_ALIAS("ipt_quota");
16MODULE_ALIAS("ip6t_quota");
17
18static DEFINE_SPINLOCK(quota_lock);
19
20static bool
21quota_mt(const struct sk_buff *skb, const struct net_device *in,
22 const struct net_device *out, const struct xt_match *match,
23 const void *matchinfo, int offset, unsigned int protoff,
24 bool *hotdrop)
25{
26 struct xt_quota_info *q =
27 ((const struct xt_quota_info *)matchinfo)->master;
28 bool ret = q->flags & XT_QUOTA_INVERT;
29
30 spin_lock_bh("a_lock);
31 if (q->quota >= skb->len) {
32 q->quota -= skb->len;
33 ret = !ret;
34 } else {
35 /* we do not allow even small packets from now on */
36 q->quota = 0;
37 }
38 spin_unlock_bh("a_lock);
39
40 return ret;
41}
42
43static bool
44quota_mt_check(const char *tablename, const void *entry,
45 const struct xt_match *match, void *matchinfo,
46 unsigned int hook_mask)
47{
48 struct xt_quota_info *q = matchinfo;
49
50 if (q->flags & ~XT_QUOTA_MASK)
51 return false;
52 /* For SMP, we only want to use one set of counters. */
53 q->master = q;
54 return true;
55}
56
57static struct xt_match quota_mt_reg[] __read_mostly = {
58 {
59 .name = "quota",
60 .family = AF_INET,
61 .checkentry = quota_mt_check,
62 .match = quota_mt,
63 .matchsize = sizeof(struct xt_quota_info),
64 .me = THIS_MODULE
65 },
66 {
67 .name = "quota",
68 .family = AF_INET6,
69 .checkentry = quota_mt_check,
70 .match = quota_mt,
71 .matchsize = sizeof(struct xt_quota_info),
72 .me = THIS_MODULE
73 },
74};
75
76static int __init quota_mt_init(void)
77{
78 return xt_register_matches(quota_mt_reg, ARRAY_SIZE(quota_mt_reg));
79}
80
81static void __exit quota_mt_exit(void)
82{
83 xt_unregister_matches(quota_mt_reg, ARRAY_SIZE(quota_mt_reg));
84}
85
86module_init(quota_mt_init);
87module_exit(quota_mt_exit);