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         if (set->flags & NFT_SET_EVAL)
  80                 return -EOPNOTSUPP;
  81
  82         priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
  83         err = nft_validate_register_load(priv->sreg, set->klen);
  84         if (err < 0)
  85                 return err;
  86
  87         if (tb[NFTA_LOOKUP_FLAGS]) {
  88                 flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
  89
  90                 if (flags & ~NFT_LOOKUP_F_INV)
  91                         return -EINVAL;
  92
  93                 if (flags & NFT_LOOKUP_F_INV) {
  94                         if (set->flags & NFT_SET_MAP)
  95                                 return -EINVAL;
  96                         priv->invert = true;
  97                 }
  98         }
  99
 100         if (tb[NFTA_LOOKUP_DREG] != NULL) {
 101                 if (priv->invert)
 102                         return -EINVAL;
 103                 if (!(set->flags & NFT_SET_MAP))
 104                         return -EINVAL;
 105
 106                 priv->dreg = nft_parse_register(tb[NFTA_LOOKUP_DREG]);
 107                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
 108                                                   set->dtype, set->dlen);
 109                 if (err < 0)
 110                         return err;
 111         } else if (set->flags & NFT_SET_MAP)
 112                 return -EINVAL;
 113
 114         priv->binding.flags = set->flags & NFT_SET_MAP;
 115
 116         err = nf_tables_bind_set(ctx, set, &priv->binding);
 117         if (err < 0)
 118                 return err;
 119
 120         priv->set = set;
 121         return 0;
 122 }
 123
 124 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 125                                const struct nft_expr *expr)
 126 {
 127         struct nft_lookup *priv = nft_expr_priv(expr);
 128
 129         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 130 }
 131
 132 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 133 {
 134         const struct nft_lookup *priv = nft_expr_priv(expr);
 135         u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
 136
 137         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 138                 goto nla_put_failure;
 139         if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 140                 goto nla_put_failure;
 141         if (priv->set->flags & NFT_SET_MAP)
 142                 if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 143                         goto nla_put_failure;
 144         if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
 145                 goto nla_put_failure;
 146         return 0;
 147
 148 nla_put_failure:
 149         return -1;
 150 }
 151
 152 static const struct nft_expr_ops nft_lookup_ops = {
 153         .type           = &nft_lookup_type,
 154         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 155         .eval           = nft_lookup_eval,
 156         .init           = nft_lookup_init,
 157         .destroy        = nft_lookup_destroy,
 158         .dump           = nft_lookup_dump,
 159 };
 160
 161 struct nft_expr_type nft_lookup_type __read_mostly = {
 162         .name           = "lookup",
 163         .ops            = &nft_lookup_ops,
 164         .policy         = nft_lookup_policy,
 165         .maxattr        = NFTA_LOOKUP_MAX,
 166         .owner          = THIS_MODULE,
 167 };