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