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         bool                            invert;
  26         struct nft_set_binding          binding;
  27 };
  28
  29 static void nft_lookup_eval(const struct nft_expr *expr,
  30                             struct nft_regs *regs,
  31                             const struct nft_pktinfo *pkt)
  32 {
  33         const struct nft_lookup *priv = nft_expr_priv(expr);
  34         const struct nft_set *set = priv->set;
  35         const struct nft_set_ext *ext;
  36         bool found;
  37
  38         found = set->ops->lookup(nft_net(pkt), set, &regs->data[priv->sreg],
  39                                  &ext) ^ priv->invert;
  40         if (!found) {
  41                 regs->verdict.code = NFT_BREAK;
  42                 return;
  43         }
  44
  45         if (set->flags & NFT_SET_MAP)
  46                 nft_data_copy(&regs->data[priv->dreg],
  47                               nft_set_ext_data(ext), set->dlen);
  48
  49 }
  50
  51 static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
  52         [NFTA_LOOKUP_SET]       = { .type = NLA_STRING,
  53                                     .len = NFT_SET_MAXNAMELEN - 1 },
  54         [NFTA_LOOKUP_SET_ID]    = { .type = NLA_U32 },
  55         [NFTA_LOOKUP_SREG]      = { .type = NLA_U32 },
  56         [NFTA_LOOKUP_DREG]      = { .type = NLA_U32 },
  57         [NFTA_LOOKUP_FLAGS]     = { .type = NLA_U32 },
  58 };
  59
  60 static int nft_lookup_init(const struct nft_ctx *ctx,
  61                            const struct nft_expr *expr,
  62                            const struct nlattr * const tb[])
  63 {
  64         struct nft_lookup *priv = nft_expr_priv(expr);
  65         u8 genmask = nft_genmask_next(ctx->net);
  66         struct nft_set *set;
  67         u32 flags;
  68         int err;
  69
  70         if (tb[NFTA_LOOKUP_SET] == NULL ||
  71             tb[NFTA_LOOKUP_SREG] == NULL)
  72                 return -EINVAL;
  73
  74         set = nft_set_lookup(ctx->net, ctx->table, tb[NFTA_LOOKUP_SET],
  75                              tb[NFTA_LOOKUP_SET_ID], genmask);
  76         if (IS_ERR(set))
  77                 return PTR_ERR(set);
  78
  79         priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
  80         err = nft_validate_register_load(priv->sreg, set->klen);
  81         if (err < 0)
  82                 return err;
  83
  84         if (tb[NFTA_LOOKUP_FLAGS]) {
  85                 flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
  86
  87                 if (flags & ~NFT_LOOKUP_F_INV)
  88                         return -EINVAL;
  89
  90                 if (flags & NFT_LOOKUP_F_INV) {
  91                         if (set->flags & NFT_SET_MAP)
  92                                 return -EINVAL;
  93                         priv->invert = true;
  94                 }
  95         }
  96
  97         if (tb[NFTA_LOOKUP_DREG] != NULL) {
  98                 if (priv->invert)
  99                         return -EINVAL;
 100                 if (!(set->flags & NFT_SET_MAP))
 101                         return -EINVAL;
 102
 103                 priv->dreg = nft_parse_register(tb[NFTA_LOOKUP_DREG]);
 104                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
 105                                                   set->dtype, set->dlen);
 106                 if (err < 0)
 107                         return err;
 108         } else if (set->flags & NFT_SET_MAP)
 109                 return -EINVAL;
 110
 111         priv->binding.flags = set->flags & NFT_SET_MAP;
 112
 113         err = nf_tables_bind_set(ctx, set, &priv->binding);
 114         if (err < 0)
 115                 return err;
 116
 117         priv->set = set;
 118         return 0;
 119 }
 120
 121 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 122                                const struct nft_expr *expr)
 123 {
 124         struct nft_lookup *priv = nft_expr_priv(expr);
 125
 126         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 127 }
 128
 129 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 130 {
 131         const struct nft_lookup *priv = nft_expr_priv(expr);
 132         u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
 133
 134         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 135                 goto nla_put_failure;
 136         if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 137                 goto nla_put_failure;
 138         if (priv->set->flags & NFT_SET_MAP)
 139                 if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 140                         goto nla_put_failure;
 141         if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
 142                 goto nla_put_failure;
 143         return 0;
 144
 145 nla_put_failure:
 146         return -1;
 147 }
 148
 149 static const struct nft_expr_ops nft_lookup_ops = {
 150         .type           = &nft_lookup_type,
 151         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 152         .eval           = nft_lookup_eval,
 153         .init           = nft_lookup_init,
 154         .destroy        = nft_lookup_destroy,
 155         .dump           = nft_lookup_dump,
 156 };
 157
 158 struct nft_expr_type nft_lookup_type __read_mostly = {
 159         .name           = "lookup",
 160         .ops            = &nft_lookup_ops,
 161         .policy         = nft_lookup_policy,
 162         .maxattr        = NFTA_LOOKUP_MAX,
 163         .owner          = THIS_MODULE,
 164 };