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_regs *regs,
  30                              const struct nft_pktinfo *pkt)
  31 {
  32         const struct nft_bitwise *priv = nft_expr_priv(expr);
  33         const u32 *src = &regs->data[priv->sreg];
  34         u32 *dst = &regs->data[priv->dreg];
  35         unsigned int i;
  36
  37         for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
  38                 dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
  39 }
  40
  41 static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
  42         [NFTA_BITWISE_SREG]     = { .type = NLA_U32 },
  43         [NFTA_BITWISE_DREG]     = { .type = NLA_U32 },
  44         [NFTA_BITWISE_LEN]      = { .type = NLA_U32 },
  45         [NFTA_BITWISE_MASK]     = { .type = NLA_NESTED },
  46         [NFTA_BITWISE_XOR]      = { .type = NLA_NESTED },
  47 };
  48
  49 static int nft_bitwise_init(const struct nft_ctx *ctx,
  50                             const struct nft_expr *expr,
  51                             const struct nlattr * const tb[])
  52 {
  53         struct nft_bitwise *priv = nft_expr_priv(expr);
  54         struct nft_data_desc d1, d2;
  55         int err;
  56
  57         if (tb[NFTA_BITWISE_SREG] == NULL ||
  58             tb[NFTA_BITWISE_DREG] == NULL ||
  59             tb[NFTA_BITWISE_LEN] == NULL ||
  60             tb[NFTA_BITWISE_MASK] == NULL ||
  61             tb[NFTA_BITWISE_XOR] == NULL)
  62                 return -EINVAL;
  63
  64         priv->len  = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));
  65         priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
  66         err = nft_validate_register_load(priv->sreg, priv->len);
  67         if (err < 0)
  68                 return err;
  69
  70         priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
  71         err = nft_validate_register_store(ctx, priv->dreg, NULL,
  72                                           NFT_DATA_VALUE, priv->len);
  73         if (err < 0)
  74                 return err;
  75
  76         err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
  77                             tb[NFTA_BITWISE_MASK]);
  78         if (err < 0)
  79                 return err;
  80         if (d1.len != priv->len)
  81                 return -EINVAL;
  82
  83         err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
  84                             tb[NFTA_BITWISE_XOR]);
  85         if (err < 0)
  86                 return err;
  87         if (d2.len != priv->len)
  88                 return -EINVAL;
  89
  90         return 0;
  91 }
  92
  93 static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
  94 {
  95         const struct nft_bitwise *priv = nft_expr_priv(expr);
  96
  97         if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
  98                 goto nla_put_failure;
  99         if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
 100                 goto nla_put_failure;
 101         if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
 102                 goto nla_put_failure;
 103
 104         if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
 105                           NFT_DATA_VALUE, priv->len) < 0)
 106                 goto nla_put_failure;
 107
 108         if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
 109                           NFT_DATA_VALUE, priv->len) < 0)
 110                 goto nla_put_failure;
 111
 112         return 0;
 113
 114 nla_put_failure:
 115         return -1;
 116 }
 117
 118 static struct nft_expr_type nft_bitwise_type;
 119 static const struct nft_expr_ops nft_bitwise_ops = {
 120         .type           = &nft_bitwise_type,
 121         .size           = NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
 122         .eval           = nft_bitwise_eval,
 123         .init           = nft_bitwise_init,
 124         .dump           = nft_bitwise_dump,
 125 };
 126
 127 static struct nft_expr_type nft_bitwise_type __read_mostly = {
 128         .name           = "bitwise",
 129         .ops            = &nft_bitwise_ops,
 130         .policy         = nft_bitwise_policy,
 131         .maxattr        = NFTA_BITWISE_MAX,
 132         .owner          = THIS_MODULE,
 133 };
 134
 135 int __init nft_bitwise_module_init(void)
 136 {
 137         return nft_register_expr(&nft_bitwise_type);
 138 }
 139
 140 void nft_bitwise_module_exit(void)
 141 {
 142         nft_unregister_expr(&nft_bitwise_type);
 143 }