LXR linux/net/netfilter/xt

   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
  12struct xt_quota_priv {
  13        uint64_t quota;
  14};
  15
  16MODULE_LICENSE("GPL");
  17MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
  18MODULE_DESCRIPTION("Xtables: countdown quota match");
  19MODULE_ALIAS("ipt_quota");
  20MODULE_ALIAS("ip6t_quota");
  21
  22static DEFINE_SPINLOCK(quota_lock);
  23
  24static bool
  25quota_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  26{
  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;
  30
  31        spin_lock_bh(&quota_lock);
  32        if (priv->quota >= skb->len) {
  33                priv->quota -= skb->len;
  34                ret = !ret;
  35        } else {
  36                /* we do not allow even small packets from now on */
  37                priv->quota = 0;
  38        }
  39        /* Copy quota back to matchinfo so that iptables can display it */
  40        q->quota = priv->quota;
  41        spin_unlock_bh(&quota_lock);
  42
  43        return ret;
  44}
  45
  46static bool 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 false;
  52
  53        q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
  54        if (q->master == NULL)
  55                return false;
  56
  57        q->master->quota = q->quota;
  58        return true;
  59}
  60
  61static void quota_mt_destroy(const struct xt_mtdtor_param *par)
  62{
  63        const struct xt_quota_info *q = par->matchinfo;
  64
  65        kfree(q->master);
  66}
  67
  68static struct xt_match quota_mt_reg __read_mostly = {
  69        .name       = "quota",
  70        .revision   = 0,
  71        .family     = NFPROTO_UNSPEC,
  72        .match      = quota_mt,
  73        .checkentry = quota_mt_check,
  74        .destroy    = quota_mt_destroy,
  75        .matchsize  = sizeof(struct xt_quota_info),
  76        .me         = THIS_MODULE,
  77};
  78
  79static int __init quota_mt_init(void)
  80{
  81        return xt_register_match(&quota_mt_reg);
  82}
  83
  84static void __exit quota_mt_exit(void)
  85{
  86        xt_unregister_match(&quota_mt_reg);
  87}
  88
  89module_init(quota_mt_init);
  90module_exit(quota_mt_exit);
  91