net/netfilter/nft_quota.c

   1 /*
   2  * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
   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
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/atomic.h>
  13 #include <linux/netlink.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter/nf_tables.h>
  16 #include <net/netfilter/nf_tables.h>
  17
  18 struct nft_quota {
  19         u64             quota;
  20         bool            invert;
  21         atomic64_t      remain;
  22 };
  23
  24 static inline bool nft_overquota(struct nft_quota *priv,
  25                                  const struct nft_pktinfo *pkt)
  26 {
  27         return atomic64_sub_return(pkt->skb->len, &priv->remain) < 0;
  28 }
  29
  30 static void nft_quota_eval(const struct nft_expr *expr,
  31                            struct nft_regs *regs,
  32                            const struct nft_pktinfo *pkt)
  33 {
  34         struct nft_quota *priv = nft_expr_priv(expr);
  35
  36         if (nft_overquota(priv, pkt) ^ priv->invert)
  37                 regs->verdict.code = NFT_BREAK;
  38 }
  39
  40 static const struct nla_policy nft_quota_policy[NFTA_QUOTA_MAX + 1] = {
  41         [NFTA_QUOTA_BYTES]      = { .type = NLA_U64 },
  42         [NFTA_QUOTA_FLAGS]      = { .type = NLA_U32 },
  43 };
  44
  45 static int nft_quota_init(const struct nft_ctx *ctx,
  46                           const struct nft_expr *expr,
  47                           const struct nlattr * const tb[])
  48 {
  49         struct nft_quota *priv = nft_expr_priv(expr);
  50         u32 flags = 0;
  51         u64 quota;
  52
  53         if (!tb[NFTA_QUOTA_BYTES])
  54                 return -EINVAL;
  55
  56         quota = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_BYTES]));
  57         if (quota > S64_MAX)
  58                 return -EOVERFLOW;
  59
  60         if (tb[NFTA_QUOTA_FLAGS]) {
  61                 flags = ntohl(nla_get_be32(tb[NFTA_QUOTA_FLAGS]));
  62                 if (flags & ~NFT_QUOTA_F_INV)
  63                         return -EINVAL;
  64         }
  65
  66         priv->quota = quota;
  67         priv->invert = (flags & NFT_QUOTA_F_INV) ? true : false;
  68         atomic64_set(&priv->remain, quota);
  69
  70         return 0;
  71 }
  72
  73 static int nft_quota_dump(struct sk_buff *skb, const struct nft_expr *expr)
  74 {
  75         const struct nft_quota *priv = nft_expr_priv(expr);
  76         u32 flags = priv->invert ? NFT_QUOTA_F_INV : 0;
  77
  78         if (nla_put_be64(skb, NFTA_QUOTA_BYTES, cpu_to_be64(priv->quota),
  79                          NFTA_QUOTA_PAD) ||
  80             nla_put_be32(skb, NFTA_QUOTA_FLAGS, htonl(flags)))
  81                 goto nla_put_failure;
  82         return 0;
  83
  84 nla_put_failure:
  85         return -1;
  86 }
  87
  88 static struct nft_expr_type nft_quota_type;
  89 static const struct nft_expr_ops nft_quota_ops = {
  90         .type           = &nft_quota_type,
  91         .size           = NFT_EXPR_SIZE(sizeof(struct nft_quota)),
  92         .eval           = nft_quota_eval,
  93         .init           = nft_quota_init,
  94         .dump           = nft_quota_dump,
  95 };
  96
  97 static struct nft_expr_type nft_quota_type __read_mostly = {
  98         .name           = "quota",
  99         .ops            = &nft_quota_ops,
 100         .policy         = nft_quota_policy,
 101         .maxattr        = NFTA_QUOTA_MAX,
 102         .flags          = NFT_EXPR_STATEFUL,
 103         .owner          = THIS_MODULE,
 104 };
 105
 106 static int __init nft_quota_module_init(void)
 107 {
 108         return nft_register_expr(&nft_quota_type);
 109 }
 110
 111 static void __exit nft_quota_module_exit(void)
 112 {
 113         nft_unregister_expr(&nft_quota_type);
 114 }
 115
 116 module_init(nft_quota_module_init);
 117 module_exit(nft_quota_module_exit);
 118
 119 MODULE_LICENSE("GPL");
 120 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 121 MODULE_ALIAS_NFT_EXPR("quota");