net/netfilter/nft_lookup.c

   1 /*
   2  * Copyright (c) 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/list.h>
  14 #include <linux/rbtree.h>
  15 #include <linux/netlink.h>
  16 #include <linux/netfilter.h>
  17 #include <linux/netfilter/nf_tables.h>
  18 #include <net/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_tables_core.h>
  20
  21 struct nft_lookup {
  22         struct nft_set                  *set;
  23         enum nft_registers              sreg:8;
  24         enum nft_registers              dreg:8;
  25         struct nft_set_binding          binding;
  26 };
  27
  28 static void nft_lookup_eval(const struct nft_expr *expr,
  29                             struct nft_data data[NFT_REG_MAX + 1],
  30                             const struct nft_pktinfo *pkt)
  31 {
  32         const struct nft_lookup *priv = nft_expr_priv(expr);
  33         const struct nft_set *set = priv->set;
  34         const struct nft_set_ext *ext;
  35
  36         if (set->ops->lookup(set, &data[priv->sreg], &ext)) {
  37                 if (set->flags & NFT_SET_MAP)
  38                         nft_data_copy(&data[priv->dreg], nft_set_ext_data(ext));
  39                 return;
  40         }
  41         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  42 }
  43
  44 static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
  45         [NFTA_LOOKUP_SET]       = { .type = NLA_STRING },
  46         [NFTA_LOOKUP_SET_ID]    = { .type = NLA_U32 },
  47         [NFTA_LOOKUP_SREG]      = { .type = NLA_U32 },
  48         [NFTA_LOOKUP_DREG]      = { .type = NLA_U32 },
  49 };
  50
  51 static int nft_lookup_init(const struct nft_ctx *ctx,
  52                            const struct nft_expr *expr,
  53                            const struct nlattr * const tb[])
  54 {
  55         struct nft_lookup *priv = nft_expr_priv(expr);
  56         struct nft_set *set;
  57         int err;
  58
  59         if (tb[NFTA_LOOKUP_SET] == NULL ||
  60             tb[NFTA_LOOKUP_SREG] == NULL)
  61                 return -EINVAL;
  62
  63         set = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET]);
  64         if (IS_ERR(set)) {
  65                 if (tb[NFTA_LOOKUP_SET_ID]) {
  66                         set = nf_tables_set_lookup_byid(ctx->net,
  67                                                         tb[NFTA_LOOKUP_SET_ID]);
  68                 }
  69                 if (IS_ERR(set))
  70                         return PTR_ERR(set);
  71         }
  72
  73         priv->sreg = ntohl(nla_get_be32(tb[NFTA_LOOKUP_SREG]));
  74         err = nft_validate_input_register(priv->sreg);
  75         if (err < 0)
  76                 return err;
  77
  78         if (tb[NFTA_LOOKUP_DREG] != NULL) {
  79                 if (!(set->flags & NFT_SET_MAP))
  80                         return -EINVAL;
  81
  82                 priv->dreg = ntohl(nla_get_be32(tb[NFTA_LOOKUP_DREG]));
  83                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
  84                                                   set->dtype, set->dlen);
  85                 if (err < 0)
  86                         return err;
  87         } else if (set->flags & NFT_SET_MAP)
  88                 return -EINVAL;
  89
  90         priv->binding.flags = set->flags & NFT_SET_MAP;
  91
  92         err = nf_tables_bind_set(ctx, set, &priv->binding);
  93         if (err < 0)
  94                 return err;
  95
  96         priv->set = set;
  97         return 0;
  98 }
  99
 100 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 101                                const struct nft_expr *expr)
 102 {
 103         struct nft_lookup *priv = nft_expr_priv(expr);
 104
 105         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 106 }
 107
 108 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 109 {
 110         const struct nft_lookup *priv = nft_expr_priv(expr);
 111
 112         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 113                 goto nla_put_failure;
 114         if (nla_put_be32(skb, NFTA_LOOKUP_SREG, htonl(priv->sreg)))
 115                 goto nla_put_failure;
 116         if (priv->set->flags & NFT_SET_MAP)
 117                 if (nla_put_be32(skb, NFTA_LOOKUP_DREG, htonl(priv->dreg)))
 118                         goto nla_put_failure;
 119         return 0;
 120
 121 nla_put_failure:
 122         return -1;
 123 }
 124
 125 static struct nft_expr_type nft_lookup_type;
 126 static const struct nft_expr_ops nft_lookup_ops = {
 127         .type           = &nft_lookup_type,
 128         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 129         .eval           = nft_lookup_eval,
 130         .init           = nft_lookup_init,
 131         .destroy        = nft_lookup_destroy,
 132         .dump           = nft_lookup_dump,
 133 };
 134
 135 static struct nft_expr_type nft_lookup_type __read_mostly = {
 136         .name           = "lookup",
 137         .ops            = &nft_lookup_ops,
 138         .policy         = nft_lookup_policy,
 139         .maxattr        = NFTA_LOOKUP_MAX,
 140         .owner          = THIS_MODULE,
 141 };
 142
 143 int __init nft_lookup_module_init(void)
 144 {
 145         return nft_register_expr(&nft_lookup_type);
 146 }
 147
 148 void nft_lookup_module_exit(void)
 149 {
 150         nft_unregister_expr(&nft_lookup_type);
 151 }