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