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         if (desc.len > U8_MAX)
  88                 return -ERANGE;
  89
  90         priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  91         priv->len = desc.len;
  92         return 0;
  93 }
  94
  95 static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  96 {
  97         const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  98
  99         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 100                 goto nla_put_failure;
 101         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 102                 goto nla_put_failure;
 103
 104         if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
 105                           NFT_DATA_VALUE, priv->len) < 0)
 106                 goto nla_put_failure;
 107         return 0;
 108
 109 nla_put_failure:
 110         return -1;
 111 }
 112
 113 static struct nft_expr_type nft_cmp_type;
 114 static const struct nft_expr_ops nft_cmp_ops = {
 115         .type           = &nft_cmp_type,
 116         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
 117         .eval           = nft_cmp_eval,
 118         .init           = nft_cmp_init,
 119         .dump           = nft_cmp_dump,
 120 };
 121
 122 static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 123                              const struct nft_expr *expr,
 124                              const struct nlattr * const tb[])
 125 {
 126         struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 127         struct nft_data_desc desc;
 128         struct nft_data data;
 129         u32 mask;
 130         int err;
 131
 132         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 133                             tb[NFTA_CMP_DATA]);
 134         BUG_ON(err < 0);
 135
 136         priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 137         err = nft_validate_register_load(priv->sreg, desc.len);
 138         if (err < 0)
 139                 return err;
 140
 141         desc.len *= BITS_PER_BYTE;
 142         mask = nft_cmp_fast_mask(desc.len);
 143
 144         priv->data = data.data[0] & mask;
 145         priv->len  = desc.len;
 146         return 0;
 147 }
 148
 149 static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
 150 {
 151         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
 152         struct nft_data data;
 153
 154         if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 155                 goto nla_put_failure;
 156         if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
 157                 goto nla_put_failure;
 158
 159         data.data[0] = priv->data;
 160         if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
 161                           NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
 162                 goto nla_put_failure;
 163         return 0;
 164
 165 nla_put_failure:
 166         return -1;
 167 }
 168
 169 const struct nft_expr_ops nft_cmp_fast_ops = {
 170         .type           = &nft_cmp_type,
 171         .size           = NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
 172         .eval           = NULL, /* inlined */
 173         .init           = nft_cmp_fast_init,
 174         .dump           = nft_cmp_fast_dump,
 175 };
 176
 177 static const struct nft_expr_ops *
 178 nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 179 {
 180         struct nft_data_desc desc;
 181         struct nft_data data;
 182         enum nft_cmp_ops op;
 183         int err;
 184
 185         if (tb[NFTA_CMP_SREG] == NULL ||
 186             tb[NFTA_CMP_OP] == NULL ||
 187             tb[NFTA_CMP_DATA] == NULL)
 188                 return ERR_PTR(-EINVAL);
 189
 190         op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 191         switch (op) {
 192         case NFT_CMP_EQ:
 193         case NFT_CMP_NEQ:
 194         case NFT_CMP_LT:
 195         case NFT_CMP_LTE:
 196         case NFT_CMP_GT:
 197         case NFT_CMP_GTE:
 198                 break;
 199         default:
 200                 return ERR_PTR(-EINVAL);
 201         }
 202
 203         err = nft_data_init(NULL, &data, sizeof(data), &desc,
 204                             tb[NFTA_CMP_DATA]);
 205         if (err < 0)
 206                 return ERR_PTR(err);
 207
 208         if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
 209                 return &nft_cmp_fast_ops;
 210         else
 211                 return &nft_cmp_ops;
 212 }
 213
 214 static struct nft_expr_type nft_cmp_type __read_mostly = {
 215         .name           = "cmp",
 216         .select_ops     = nft_cmp_select_ops,
 217         .policy         = nft_cmp_policy,
 218         .maxattr        = NFTA_CMP_MAX,
 219         .owner          = THIS_MODULE,
 220 };
 221
 222 int __init nft_cmp_module_init(void)
 223 {
 224         return nft_register_expr(&nft_cmp_type);
 225 }
 226
 227 void nft_cmp_module_exit(void)
 228 {
 229         nft_unregister_expr(&nft_cmp_type);
 230 }