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_regs *regs,
  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, &regs->data[priv->sreg], &ext)) {
  37                 if (set->flags & NFT_SET_MAP)
  38                         nft_data_copy(&regs->data[priv->dreg],
  39                                       nft_set_ext_data(ext), set->dlen);
  40                 return;
  41         }
  42         regs->verdict.code = NFT_BREAK;
  43 }
  44
  45 static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
  46         [NFTA_LOOKUP_SET]       = { .type = NLA_STRING },
  47         [NFTA_LOOKUP_SET_ID]    = { .type = NLA_U32 },
  48         [NFTA_LOOKUP_SREG]      = { .type = NLA_U32 },
  49         [NFTA_LOOKUP_DREG]      = { .type = NLA_U32 },
  50 };
  51
  52 static int nft_lookup_init(const struct nft_ctx *ctx,
  53                            const struct nft_expr *expr,
  54                            const struct nlattr * const tb[])
  55 {
  56         struct nft_lookup *priv = nft_expr_priv(expr);
  57         struct nft_set *set;
  58         int err;
  59
  60         if (tb[NFTA_LOOKUP_SET] == NULL ||
  61             tb[NFTA_LOOKUP_SREG] == NULL)
  62                 return -EINVAL;
  63
  64         set = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET]);
  65         if (IS_ERR(set)) {
  66                 if (tb[NFTA_LOOKUP_SET_ID]) {
  67                         set = nf_tables_set_lookup_byid(ctx->net,
  68                                                         tb[NFTA_LOOKUP_SET_ID]);
  69                 }
  70                 if (IS_ERR(set))
  71                         return PTR_ERR(set);
  72         }
  73
  74         if (set->flags & NFT_SET_EVAL)
  75                 return -EOPNOTSUPP;
  76
  77         priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
  78         err = nft_validate_register_load(priv->sreg, set->klen);
  79         if (err < 0)
  80                 return err;
  81
  82         if (tb[NFTA_LOOKUP_DREG] != NULL) {
  83                 if (!(set->flags & NFT_SET_MAP))
  84                         return -EINVAL;
  85
  86                 priv->dreg = nft_parse_register(tb[NFTA_LOOKUP_DREG]);
  87                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
  88                                                   set->dtype, set->dlen);
  89                 if (err < 0)
  90                         return err;
  91         } else if (set->flags & NFT_SET_MAP)
  92                 return -EINVAL;
  93
  94         priv->binding.flags = set->flags & NFT_SET_MAP;
  95
  96         err = nf_tables_bind_set(ctx, set, &priv->binding);
  97         if (err < 0)
  98                 return err;
  99
 100         priv->set = set;
 101         return 0;
 102 }
 103
 104 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 105                                const struct nft_expr *expr)
 106 {
 107         struct nft_lookup *priv = nft_expr_priv(expr);
 108
 109         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 110 }
 111
 112 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 113 {
 114         const struct nft_lookup *priv = nft_expr_priv(expr);
 115
 116         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 117                 goto nla_put_failure;
 118         if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 119                 goto nla_put_failure;
 120         if (priv->set->flags & NFT_SET_MAP)
 121                 if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 122                         goto nla_put_failure;
 123         return 0;
 124
 125 nla_put_failure:
 126         return -1;
 127 }
 128
 129 static struct nft_expr_type nft_lookup_type;
 130 static const struct nft_expr_ops nft_lookup_ops = {
 131         .type           = &nft_lookup_type,
 132         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 133         .eval           = nft_lookup_eval,
 134         .init           = nft_lookup_init,
 135         .destroy        = nft_lookup_destroy,
 136         .dump           = nft_lookup_dump,
 137 };
 138
 139 static struct nft_expr_type nft_lookup_type __read_mostly = {
 140         .name           = "lookup",
 141         .ops            = &nft_lookup_ops,
 142         .policy         = nft_lookup_policy,
 143         .maxattr        = NFTA_LOOKUP_MAX,
 144         .owner          = THIS_MODULE,
 145 };
 146
 147 int __init nft_lookup_module_init(void)
 148 {
 149         return nft_register_expr(&nft_lookup_type);
 150 }
 151
 152 void nft_lookup_module_exit(void)
 153 {
 154         nft_unregister_expr(&nft_lookup_type);
 155 }