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/spinlock.h>
   8
   9 #include <linux/netfilter/x_tables.h>
  10 #include <linux/netfilter/xt_quota.h>
  11
  12 MODULE_LICENSE("GPL");
  13 MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
  14 MODULE_ALIAS("ipt_quota");
  15 MODULE_ALIAS("ip6t_quota");
  16
  17 static DEFINE_SPINLOCK(quota_lock);
  18
  19 static int
  20 match(const struct sk_buff *skb,
  21       const struct net_device *in, const struct net_device *out,
  22       const struct xt_match *match, const void *matchinfo,
  23       int offset, unsigned int protoff, int *hotdrop)
  24 {
  25         struct xt_quota_info *q = ((struct xt_quota_info *)matchinfo)->master;
  26         int ret = q->flags & XT_QUOTA_INVERT ? 1 : 0;
  27
  28         spin_lock_bh(&quota_lock);
  29         if (q->quota >= skb->len) {
  30                 q->quota -= skb->len;
  31                 ret ^= 1;
  32         } else {
  33                 /* we do not allow even small packets from now on */
  34                 q->quota = 0;
  35         }
  36         spin_unlock_bh(&quota_lock);
  37
  38         return ret;
  39 }
  40
  41 static int
  42 checkentry(const char *tablename, const void *entry,
  43            const struct xt_match *match, void *matchinfo,
  44            unsigned int matchsize, unsigned int hook_mask)
  45 {
  46         struct xt_quota_info *q = (struct xt_quota_info *)matchinfo;
  47
  48         if (q->flags & ~XT_QUOTA_MASK)
  49                 return 0;
  50         /* For SMP, we only want to use one set of counters. */
  51         q->master = q;
  52         return 1;
  53 }
  54
  55 static struct xt_match quota_match = {
  56         .name           = "quota",
  57         .family         = AF_INET,
  58         .match          = match,
  59         .matchsize      = sizeof(struct xt_quota_info),
  60         .checkentry     = checkentry,
  61         .me             = THIS_MODULE
  62 };
  63
  64 static struct xt_match quota_match6 = {
  65         .name           = "quota",
  66         .family         = AF_INET6,
  67         .match          = match,
  68         .matchsize      = sizeof(struct xt_quota_info),
  69         .checkentry     = checkentry,
  70         .me             = THIS_MODULE
  71 };
  72
  73 static int __init xt_quota_init(void)
  74 {
  75         int ret;
  76
  77         ret = xt_register_match(&quota_match);
  78         if (ret)
  79                 goto err1;
  80         ret = xt_register_match(&quota_match6);
  81         if (ret)
  82                 goto err2;
  83         return ret;
  84
  85 err2:
  86         xt_unregister_match(&quota_match);
  87 err1:
  88         return ret;
  89 }
  90
  91 static void __exit xt_quota_fini(void)
  92 {
  93         xt_unregister_match(&quota_match6);
  94         xt_unregister_match(&quota_match);
  95 }
  96
  97 module_init(xt_quota_init);
  98 module_exit(xt_quota_fini);