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