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                 /* fall through */
  48         case NFT_CMP_LTE:
  49                 if (d > 0)
  50                         goto mismatch;
  51                 break;
  52         case NFT_CMP_GT:
  53                 if (d == 0)
  54                         goto mismatch;
  55                 /* fall through */
  56         case NFT_CMP_GTE:
  57                 if (d < 0)
  58                         goto mismatch;
  59                 break;
  60         }
  61         return;
  62
  63 mismatch:
  64         regs->verdict.code = NFT_BREAK;
  65 }
  66
  67 static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
  68         [NFTA_CMP_SREG]         = { .type = NLA_U32 },
  69         [NFTA_CMP_OP]           = { .type = NLA_U32 },
  70         [NFTA_CMP_DATA]         = { .type = NLA_NESTED },
  71 };
  72
  73 static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  74                         const struct nlattr * const tb[])
  75 {
  76         struct nft_cmp_expr *priv = nft_expr_priv(expr);
  77         struct nft_data_desc desc;
  78         int err;
  79
  80         err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
  81                             tb[NFTA_CMP_DATA]);
  82         if (err < 0)
  83                 return err;
  84
  85         if (desc.type != NFT_DATA_VALUE) {
  86                 err = -EINVAL;
  87                 nft_data_release(&priv->data, desc.type);
  88                 return err;
  89         }
  90
  91         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
  92         err = nft_validate_register_load(priv->sreg, desc.len);
  93         if (err < 0)
  94                 return err;
  95
  96         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  97         priv->len = desc.len;
  98         return 0;
  99 }
 100
 101 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
 102 {
 103         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 104
 105         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 106                 goto nla_put_failure;
 107         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 108                 goto nla_put_failure;
 109
 110         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 111                           NFT_DATA_VALUE, priv->len) < 0)
 112                 goto nla_put_failure;
 113         return 0;
 114
 115 nla_put_failure:
 116         return -1;
 117 }
 118
 119 static const struct nft_expr_ops nft_cmp_ops = {
 120         .type           = &nft_cmp_type,
 121         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 122         .eval           = nft_cmp_eval,
 123         .init           = nft_cmp_init,
 124         .dump           = nft_cmp_dump,
 125 };
 126
 127 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 128                              const struct nft_expr *expr,
 129                              const struct nlattr * const tb[])
 130 {
 131         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 132         struct nft_data_desc desc;
 133         struct nft_data data;
 134         u32 mask;
 135         int err;
 136
 137         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 138                             tb[NFTA_CMP_DATA]);
 139         if (err < 0)
 140                 return err;
 141
 142         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 143         err = nft_validate_register_load(priv->sreg, desc.len);
 144         if (err < 0)
 145                 return err;
 146
 147         desc.len *= BITS_PER_BYTE;
 148         mask = nft_cmp_fast_mask(desc.len);
 149
 150         priv->data = data.data[0] & mask;
 151         priv->len  = desc.len;
 152         return 0;
 153 }
 154
 155 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 156 {
 157         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 158         struct nft_data data;
 159
 160         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 161                 goto nla_put_failure;
 162         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 163                 goto nla_put_failure;
 164
 165         data.data[0] = priv->data;
 166         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 167                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 168                 goto nla_put_failure;
 169         return 0;
 170
 171 nla_put_failure:
 172         return -1;
 173 }
 174
 175 const struct nft_expr_ops nft_cmp_fast_ops = {
 176         .type           = &nft_cmp_type,
 177         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 178         .eval           = NULL, /* inlined */
 179         .init           = nft_cmp_fast_init,
 180         .dump           = nft_cmp_fast_dump,
 181 };
 182
 183 static const struct nft_expr_ops *
 184 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 185 {
 186         struct nft_data_desc desc;
 187         struct nft_data data;
 188         enum nft_cmp_ops op;
 189         int err;
 190
 191         if (tb[NFTA_CMP_SREG] == NULL ||
 192             tb[NFTA_CMP_OP] == NULL ||
 193             tb[NFTA_CMP_DATA] == NULL)
 194                 return ERR_PTR(-EINVAL);
 195
 196         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 197         switch (op) {
 198         case NFT_CMP_EQ:
 199         case NFT_CMP_NEQ:
 200         case NFT_CMP_LT:
 201         case NFT_CMP_LTE:
 202         case NFT_CMP_GT:
 203         case NFT_CMP_GTE:
 204                 break;
 205         default:
 206                 return ERR_PTR(-EINVAL);
 207         }
 208
 209         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 210                             tb[NFTA_CMP_DATA]);
 211         if (err < 0)
 212                 return ERR_PTR(err);
 213
 214         if (desc.type != NFT_DATA_VALUE) {
 215                 err = -EINVAL;
 216                 goto err1;
 217         }
 218
 219         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 220                 return &nft_cmp_fast_ops;
 221
 222         return &nft_cmp_ops;
 223 err1:
 224         nft_data_release(&data, desc.type);
 225         return ERR_PTR(-EINVAL);
 226 }
 227
 228 struct nft_expr_type nft_cmp_type __read_mostly = {
 229         .name           = "cmp",
 230         .select_ops     = nft_cmp_select_ops,
 231         .policy         = nft_cmp_policy,
 232         .maxattr        = NFTA_CMP_MAX,
 233         .owner          = THIS_MODULE,
 234 };