net/netfilter/nft_cmp.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_cmp_expr {
  21         struct nft_data         data;
  22         enum nft_registers      sreg:8;
  23         u8                      len;
  24         enum nft_cmp_ops        op:8;
  25 };
  26
  27 static void nft_cmp_eval(const struct nft_expr *expr,
  28                          struct nft_data data[NFT_REG_MAX + 1],
  29                          const struct nft_pktinfo *pkt)
  30 {
  31         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  32         int d;
  33
  34         d = nft_data_cmp(&data[priv->sreg], &priv->data, priv->len);
  35         switch (priv->op) {
  36         case NFT_CMP_EQ:
  37                 if (d != 0)
  38                         goto mismatch;
  39                 break;
  40         case NFT_CMP_NEQ:
  41                 if (d == 0)
  42                         goto mismatch;
  43                 break;
  44         case NFT_CMP_LT:
  45                 if (d == 0)
  46                         goto mismatch;
  47         case NFT_CMP_LTE:
  48                 if (d > 0)
  49                         goto mismatch;
  50                 break;
  51         case NFT_CMP_GT:
  52                 if (d == 0)
  53                         goto mismatch;
  54         case NFT_CMP_GTE:
  55                 if (d < 0)
  56                         goto mismatch;
  57                 break;
  58         }
  59         return;
  60
  61 mismatch:
  62         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  63 }
  64
  65 static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
  66         [NFTA_CMP_SREG]         = { .type = NLA_U32 },
  67         [NFTA_CMP_OP]           = { .type = NLA_U32 },
  68         [NFTA_CMP_DATA]         = { .type = NLA_NESTED },
  69 };
  70
  71 static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  72                         const struct nlattr * const tb[])
  73 {
  74         struct nft_cmp_expr *priv = nft_expr_priv(expr);
  75         struct nft_data_desc desc;
  76         int err;
  77
  78         priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
  79         priv->op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  80
  81         err = nft_data_init(NULL, &priv->data, &desc, tb[NFTA_CMP_DATA]);
  82         BUG_ON(err < 0);
  83
  84         priv->len = desc.len;
  85         return 0;
  86 }
  87
  88 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  89 {
  90         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  91
  92         if (nla_put_be32(skb, NFTA_CMP_SREG, htonl(priv->sreg)))
  93                 goto nla_put_failure;
  94         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
  95                 goto nla_put_failure;
  96
  97         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
  98                           NFT_DATA_VALUE, priv->len) < 0)
  99                 goto nla_put_failure;
 100         return 0;
 101
 102 nla_put_failure:
 103         return -1;
 104 }
 105
 106 static struct nft_expr_type nft_cmp_type;
 107 static const struct nft_expr_ops nft_cmp_ops = {
 108         .type           = &nft_cmp_type,
 109         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 110         .eval           = nft_cmp_eval,
 111         .init           = nft_cmp_init,
 112         .dump           = nft_cmp_dump,
 113 };
 114
 115 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 116                              const struct nft_expr *expr,
 117                              const struct nlattr * const tb[])
 118 {
 119         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 120         struct nft_data_desc desc;
 121         struct nft_data data;
 122         u32 mask;
 123         int err;
 124
 125         priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
 126
 127         err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
 128         BUG_ON(err < 0);
 129         desc.len *= BITS_PER_BYTE;
 130
 131         mask = ~0U >> (sizeof(priv->data) * BITS_PER_BYTE - desc.len);
 132         priv->data = data.data[0] & mask;
 133         priv->len  = desc.len;
 134         return 0;
 135 }
 136
 137 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 138 {
 139         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 140         struct nft_data data;
 141
 142         if (nla_put_be32(skb, NFTA_CMP_SREG, htonl(priv->sreg)))
 143                 goto nla_put_failure;
 144         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 145                 goto nla_put_failure;
 146
 147         data.data[0] = priv->data;
 148         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 149                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 150                 goto nla_put_failure;
 151         return 0;
 152
 153 nla_put_failure:
 154         return -1;
 155 }
 156
 157 const struct nft_expr_ops nft_cmp_fast_ops = {
 158         .type           = &nft_cmp_type,
 159         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 160         .eval           = NULL, /* inlined */
 161         .init           = nft_cmp_fast_init,
 162         .dump           = nft_cmp_fast_dump,
 163 };
 164
 165 static const struct nft_expr_ops *
 166 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 167 {
 168         struct nft_data_desc desc;
 169         struct nft_data data;
 170         enum nft_registers sreg;
 171         enum nft_cmp_ops op;
 172         int err;
 173
 174         if (tb[NFTA_CMP_SREG] == NULL ||
 175             tb[NFTA_CMP_OP] == NULL ||
 176             tb[NFTA_CMP_DATA] == NULL)
 177                 return ERR_PTR(-EINVAL);
 178
 179         sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
 180         err = nft_validate_input_register(sreg);
 181         if (err < 0)
 182                 return ERR_PTR(err);
 183
 184         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 185         switch (op) {
 186         case NFT_CMP_EQ:
 187         case NFT_CMP_NEQ:
 188         case NFT_CMP_LT:
 189         case NFT_CMP_LTE:
 190         case NFT_CMP_GT:
 191         case NFT_CMP_GTE:
 192                 break;
 193         default:
 194                 return ERR_PTR(-EINVAL);
 195         }
 196
 197         err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
 198         if (err < 0)
 199                 return ERR_PTR(err);
 200
 201         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 202                 return &nft_cmp_fast_ops;
 203         else
 204                 return &nft_cmp_ops;
 205 }
 206
 207 static struct nft_expr_type nft_cmp_type __read_mostly = {
 208         .name           = "cmp",
 209         .select_ops     = nft_cmp_select_ops,
 210         .policy         = nft_cmp_policy,
 211         .maxattr        = NFTA_CMP_MAX,
 212         .owner          = THIS_MODULE,
 213 };
 214
 215 int __init nft_cmp_module_init(void)
 216 {
 217         return nft_register_expr(&nft_cmp_type);
 218 }
 219
 220 void nft_cmp_module_exit(void)
 221 {
 222         nft_unregister_expr(&nft_cmp_type);
 223 }