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_regs *regs,
  29                          const struct nft_pktinfo *pkt)
  30 {
  31         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  32         int d;
  33
  34         d = memcmp(&regs->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         regs->verdict.code = 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         err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
  79                             tb[NFTA_CMP_DATA]);
  80         BUG_ON(err < 0);
  81
  82         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
  83         err = nft_validate_register_load(priv->sreg, desc.len);
  84         if (err < 0)
  85                 return err;
  86
  87         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  88         priv->len = desc.len;
  89         return 0;
  90 }
  91
  92 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  93 {
  94         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  95
  96         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
  97                 goto nla_put_failure;
  98         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
  99                 goto nla_put_failure;
 100
 101         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 102                           NFT_DATA_VALUE, priv->len) < 0)
 103                 goto nla_put_failure;
 104         return 0;
 105
 106 nla_put_failure:
 107         return -1;
 108 }
 109
 110 static struct nft_expr_type nft_cmp_type;
 111 static const struct nft_expr_ops nft_cmp_ops = {
 112         .type           = &nft_cmp_type,
 113         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 114         .eval           = nft_cmp_eval,
 115         .init           = nft_cmp_init,
 116         .dump           = nft_cmp_dump,
 117 };
 118
 119 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 120                              const struct nft_expr *expr,
 121                              const struct nlattr * const tb[])
 122 {
 123         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 124         struct nft_data_desc desc;
 125         struct nft_data data;
 126         u32 mask;
 127         int err;
 128
 129         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 130                             tb[NFTA_CMP_DATA]);
 131         BUG_ON(err < 0);
 132
 133         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 134         err = nft_validate_register_load(priv->sreg, desc.len);
 135         if (err < 0)
 136                 return err;
 137
 138         desc.len *= BITS_PER_BYTE;
 139         mask = nft_cmp_fast_mask(desc.len);
 140
 141         priv->data = data.data[0] & mask;
 142         priv->len  = desc.len;
 143         return 0;
 144 }
 145
 146 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 147 {
 148         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 149         struct nft_data data;
 150
 151         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 152                 goto nla_put_failure;
 153         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 154                 goto nla_put_failure;
 155
 156         data.data[0] = priv->data;
 157         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 158                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 159                 goto nla_put_failure;
 160         return 0;
 161
 162 nla_put_failure:
 163         return -1;
 164 }
 165
 166 const struct nft_expr_ops nft_cmp_fast_ops = {
 167         .type           = &nft_cmp_type,
 168         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 169         .eval           = NULL, /* inlined */
 170         .init           = nft_cmp_fast_init,
 171         .dump           = nft_cmp_fast_dump,
 172 };
 173
 174 static const struct nft_expr_ops *
 175 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 176 {
 177         struct nft_data_desc desc;
 178         struct nft_data data;
 179         enum nft_cmp_ops op;
 180         int err;
 181
 182         if (tb[NFTA_CMP_SREG] == NULL ||
 183             tb[NFTA_CMP_OP] == NULL ||
 184             tb[NFTA_CMP_DATA] == NULL)
 185                 return ERR_PTR(-EINVAL);
 186
 187         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 188         switch (op) {
 189         case NFT_CMP_EQ:
 190         case NFT_CMP_NEQ:
 191         case NFT_CMP_LT:
 192         case NFT_CMP_LTE:
 193         case NFT_CMP_GT:
 194         case NFT_CMP_GTE:
 195                 break;
 196         default:
 197                 return ERR_PTR(-EINVAL);
 198         }
 199
 200         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 201                             tb[NFTA_CMP_DATA]);
 202         if (err < 0)
 203                 return ERR_PTR(err);
 204
 205         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 206                 return &nft_cmp_fast_ops;
 207         else
 208                 return &nft_cmp_ops;
 209 }
 210
 211 static struct nft_expr_type nft_cmp_type __read_mostly = {
 212         .name           = "cmp",
 213         .select_ops     = nft_cmp_select_ops,
 214         .policy         = nft_cmp_policy,
 215         .maxattr        = NFTA_CMP_MAX,
 216         .owner          = THIS_MODULE,
 217 };
 218
 219 int __init nft_cmp_module_init(void)
 220 {
 221         return nft_register_expr(&nft_cmp_type);
 222 }
 223
 224 void nft_cmp_module_exit(void)
 225 {
 226         nft_unregister_expr(&nft_cmp_type);
 227 }