net/netfilter/nft_limit.c

   1 /*
   2  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/netlink.h>
  16 #include <linux/netfilter.h>
  17 #include <linux/netfilter/nf_tables.h>
  18 #include <net/netfilter/nf_tables.h>
  19
  20 static DEFINE_SPINLOCK(limit_lock);
  21
  22 struct nft_limit {
  23         u64             tokens;
  24         u64             rate;
  25         u64             unit;
  26         unsigned long   stamp;
  27 };
  28
  29 static void nft_limit_eval(const struct nft_expr *expr,
  30                            struct nft_data data[NFT_REG_MAX + 1],
  31                            const struct nft_pktinfo *pkt)
  32 {
  33         struct nft_limit *priv = nft_expr_priv(expr);
  34
  35         spin_lock_bh(&limit_lock);
  36         if (time_after_eq(jiffies, priv->stamp)) {
  37                 priv->tokens = priv->rate;
  38                 priv->stamp = jiffies + priv->unit * HZ;
  39         }
  40
  41         if (priv->tokens >= 1) {
  42                 priv->tokens--;
  43                 spin_unlock_bh(&limit_lock);
  44                 return;
  45         }
  46         spin_unlock_bh(&limit_lock);
  47
  48         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  49 }
  50
  51 static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
  52         [NFTA_LIMIT_RATE]       = { .type = NLA_U64 },
  53         [NFTA_LIMIT_UNIT]       = { .type = NLA_U64 },
  54 };
  55
  56 static int nft_limit_init(const struct nft_ctx *ctx,
  57                           const struct nft_expr *expr,
  58                           const struct nlattr * const tb[])
  59 {
  60         struct nft_limit *priv = nft_expr_priv(expr);
  61
  62         if (tb[NFTA_LIMIT_RATE] == NULL ||
  63             tb[NFTA_LIMIT_UNIT] == NULL)
  64                 return -EINVAL;
  65
  66         priv->rate   = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
  67         priv->unit   = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
  68         priv->stamp  = jiffies + priv->unit * HZ;
  69         priv->tokens = priv->rate;
  70         return 0;
  71 }
  72
  73 static int nft_limit_dump(struct sk_buff *skb, const struct nft_expr *expr)
  74 {
  75         const struct nft_limit *priv = nft_expr_priv(expr);
  76
  77         if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(priv->rate)))
  78                 goto nla_put_failure;
  79         if (nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(priv->unit)))
  80                 goto nla_put_failure;
  81         return 0;
  82
  83 nla_put_failure:
  84         return -1;
  85 }
  86
  87 static struct nft_expr_type nft_limit_type;
  88 static const struct nft_expr_ops nft_limit_ops = {
  89         .type           = &nft_limit_type,
  90         .size           = NFT_EXPR_SIZE(sizeof(struct nft_limit)),
  91         .eval           = nft_limit_eval,
  92         .init           = nft_limit_init,
  93         .dump           = nft_limit_dump,
  94 };
  95
  96 static struct nft_expr_type nft_limit_type __read_mostly = {
  97         .name           = "limit",
  98         .ops            = &nft_limit_ops,
  99         .policy         = nft_limit_policy,
 100         .maxattr        = NFTA_LIMIT_MAX,
 101         .owner          = THIS_MODULE,
 102 };
 103
 104 static int __init nft_limit_module_init(void)
 105 {
 106         return nft_register_expr(&nft_limit_type);
 107 }
 108
 109 static void __exit nft_limit_module_exit(void)
 110 {
 111         nft_unregister_expr(&nft_limit_type);
 112 }
 113
 114 module_init(nft_limit_module_init);
 115 module_exit(nft_limit_module_exit);
 116
 117 MODULE_LICENSE("GPL");
 118 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 119 MODULE_ALIAS_NFT_EXPR("limit");