net/netfilter/nft_bitwise.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/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter/nf_tables.h>
  17 #include <net/netfilter/nf_tables_core.h>
  18 #include <net/netfilter/nf_tables.h>
  19
  20 struct nft_bitwise {
  21         enum nft_registers      sreg:8;
  22         enum nft_registers      dreg:8;
  23         u8                      len;
  24         struct nft_data         mask;
  25         struct nft_data         xor;
  26 };
  27
  28 static void nft_bitwise_eval(const struct nft_expr *expr,
  29                              struct nft_data data[NFT_REG_MAX + 1],
  30                              const struct nft_pktinfo *pkt)
  31 {
  32         const struct nft_bitwise *priv = nft_expr_priv(expr);
  33         const struct nft_data *src = &data[priv->sreg];
  34         struct nft_data *dst = &data[priv->dreg];
  35         unsigned int i;
  36
  37         for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++) {
  38                 dst->data[i] = (src->data[i] & priv->mask.data[i]) ^
  39                                priv->xor.data[i];
  40         }
  41 }
  42
  43 static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
  44         [NFTA_BITWISE_SREG]     = { .type = NLA_U32 },
  45         [NFTA_BITWISE_DREG]     = { .type = NLA_U32 },
  46         [NFTA_BITWISE_LEN]      = { .type = NLA_U32 },
  47         [NFTA_BITWISE_MASK]     = { .type = NLA_NESTED },
  48         [NFTA_BITWISE_XOR]      = { .type = NLA_NESTED },
  49 };
  50
  51 static int nft_bitwise_init(const struct nft_ctx *ctx,
  52                             const struct nft_expr *expr,
  53                             const struct nlattr * const tb[])
  54 {
  55         struct nft_bitwise *priv = nft_expr_priv(expr);
  56         struct nft_data_desc d1, d2;
  57         int err;
  58
  59         if (tb[NFTA_BITWISE_SREG] == NULL ||
  60             tb[NFTA_BITWISE_DREG] == NULL ||
  61             tb[NFTA_BITWISE_LEN] == NULL ||
  62             tb[NFTA_BITWISE_MASK] == NULL ||
  63             tb[NFTA_BITWISE_XOR] == NULL)
  64                 return -EINVAL;
  65
  66         priv->sreg = ntohl(nla_get_be32(tb[NFTA_BITWISE_SREG]));
  67         err = nft_validate_input_register(priv->sreg);
  68         if (err < 0)
  69                 return err;
  70
  71         priv->dreg = ntohl(nla_get_be32(tb[NFTA_BITWISE_DREG]));
  72         err = nft_validate_output_register(priv->dreg);
  73         if (err < 0)
  74                 return err;
  75         err = nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
  76         if (err < 0)
  77                 return err;
  78
  79         priv->len = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));
  80
  81         err = nft_data_init(NULL, &priv->mask, &d1, tb[NFTA_BITWISE_MASK]);
  82         if (err < 0)
  83                 return err;
  84         if (d1.len != priv->len)
  85                 return -EINVAL;
  86
  87         err = nft_data_init(NULL, &priv->xor, &d2, tb[NFTA_BITWISE_XOR]);
  88         if (err < 0)
  89                 return err;
  90         if (d2.len != priv->len)
  91                 return -EINVAL;
  92
  93         return 0;
  94 }
  95
  96 static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
  97 {
  98         const struct nft_bitwise *priv = nft_expr_priv(expr);
  99
 100         if (nla_put_be32(skb, NFTA_BITWISE_SREG, htonl(priv->sreg)))
 101                 goto nla_put_failure;
 102         if (nla_put_be32(skb, NFTA_BITWISE_DREG, htonl(priv->dreg)))
 103                 goto nla_put_failure;
 104         if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
 105                 goto nla_put_failure;
 106
 107         if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
 108                           NFT_DATA_VALUE, priv->len) < 0)
 109                 goto nla_put_failure;
 110
 111         if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
 112                           NFT_DATA_VALUE, priv->len) < 0)
 113                 goto nla_put_failure;
 114
 115         return 0;
 116
 117 nla_put_failure:
 118         return -1;
 119 }
 120
 121 static struct nft_expr_type nft_bitwise_type;
 122 static const struct nft_expr_ops nft_bitwise_ops = {
 123         .type           = &nft_bitwise_type,
 124         .size           = NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
 125         .eval           = nft_bitwise_eval,
 126         .init           = nft_bitwise_init,
 127         .dump           = nft_bitwise_dump,
 128 };
 129
 130 static struct nft_expr_type nft_bitwise_type __read_mostly = {
 131         .name           = "bitwise",
 132         .ops            = &nft_bitwise_ops,
 133         .policy         = nft_bitwise_policy,
 134         .maxattr        = NFTA_BITWISE_MAX,
 135         .owner          = THIS_MODULE,
 136 };
 137
 138 int __init nft_bitwise_module_init(void)
 139 {
 140         return nft_register_expr(&nft_bitwise_type);
 141 }
 142
 143 void nft_bitwise_module_exit(void)
 144 {
 145         nft_unregister_expr(&nft_bitwise_type);
 146 }