net/netfilter/xt_quota.c

   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
  13 struct xt_quota_priv {
  14         spinlock_t      lock;
  15         uint64_t        quota;
  16 };
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
  20 MODULE_DESCRIPTION("Xtables: countdown quota match");
  21 MODULE_ALIAS("ipt_quota");
  22 MODULE_ALIAS("ip6t_quota");
  23
  24 static bool
  25 quota_mt(const struct sk_buff *skb, struct xt_action_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(&priv->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         spin_unlock_bh(&priv->lock);
  40
  41         return ret;
  42 }
  43
  44 static int quota_mt_check(const struct xt_mtchk_param *par)
  45 {
  46         struct xt_quota_info *q = par->matchinfo;
  47
  48         if (q->flags & ~XT_QUOTA_MASK)
  49                 return -EINVAL;
  50
  51         q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
  52         if (q->master == NULL)
  53                 return -ENOMEM;
  54
  55         spin_lock_init(&q->master->lock);
  56         q->master->quota = q->quota;
  57         return 0;
  58 }
  59
  60 static void quota_mt_destroy(const struct xt_mtdtor_param *par)
  61 {
  62         const struct xt_quota_info *q = par->matchinfo;
  63
  64         kfree(q->master);
  65 }
  66
  67 static struct xt_match quota_mt_reg __read_mostly = {
  68         .name       = "quota",
  69         .revision   = 0,
  70         .family     = NFPROTO_UNSPEC,
  71         .match      = quota_mt,
  72         .checkentry = quota_mt_check,
  73         .destroy    = quota_mt_destroy,
  74         .matchsize  = sizeof(struct xt_quota_info),
  75         .me         = THIS_MODULE,
  76 };
  77
  78 static int __init quota_mt_init(void)
  79 {
  80         return xt_register_match(&quota_mt_reg);
  81 }
  82
  83 static void __exit quota_mt_exit(void)
  84 {
  85         xt_unregister_match(&quota_mt_reg);
  86 }
  87
  88 module_init(quota_mt_init);
  89 module_exit(quota_mt_exit);