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         [NFTA_LOOKUP_SET_ID]    = { .type = NLA_U32 },
  54         [NFTA_LOOKUP_SREG]      = { .type = NLA_U32 },
  55         [NFTA_LOOKUP_DREG]      = { .type = NLA_U32 },
  56         [NFTA_LOOKUP_FLAGS]     = { .type = NLA_U32 },
  57 };
  58
  59 static int nft_lookup_init(const struct nft_ctx *ctx,
  60                            const struct nft_expr *expr,
  61                            const struct nlattr * const tb[])
  62 {
  63         struct nft_lookup *priv = nft_expr_priv(expr);
  64         u8 genmask = nft_genmask_next(ctx->net);
  65         struct nft_set *set;
  66         u32 flags;
  67         int err;
  68
  69         if (tb[NFTA_LOOKUP_SET] == NULL ||
  70             tb[NFTA_LOOKUP_SREG] == NULL)
  71                 return -EINVAL;
  72
  73         set = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET], genmask);
  74         if (IS_ERR(set)) {
  75                 if (tb[NFTA_LOOKUP_SET_ID]) {
  76                         set = nf_tables_set_lookup_byid(ctx->net,
  77                                                         tb[NFTA_LOOKUP_SET_ID],
  78                                                         genmask);
  79                 }
  80                 if (IS_ERR(set))
  81                         return PTR_ERR(set);
  82         }
  83
  84         if (set->flags & NFT_SET_EVAL)
  85                 return -EOPNOTSUPP;
  86
  87         priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
  88         err = nft_validate_register_load(priv->sreg, set->klen);
  89         if (err < 0)
  90                 return err;
  91
  92         if (tb[NFTA_LOOKUP_FLAGS]) {
  93                 flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
  94
  95                 if (flags & ~NFT_LOOKUP_F_INV)
  96                         return -EINVAL;
  97
  98                 if (flags & NFT_LOOKUP_F_INV) {
  99                         if (set->flags & NFT_SET_MAP)
 100                                 return -EINVAL;
 101                         priv->invert = true;
 102                 }
 103         }
 104
 105         if (tb[NFTA_LOOKUP_DREG] != NULL) {
 106                 if (priv->invert)
 107                         return -EINVAL;
 108                 if (!(set->flags & NFT_SET_MAP))
 109                         return -EINVAL;
 110
 111                 priv->dreg = nft_parse_register(tb[NFTA_LOOKUP_DREG]);
 112                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
 113                                                   set->dtype, set->dlen);
 114                 if (err < 0)
 115                         return err;
 116         } else if (set->flags & NFT_SET_MAP)
 117                 return -EINVAL;
 118
 119         priv->binding.flags = set->flags & NFT_SET_MAP;
 120
 121         err = nf_tables_bind_set(ctx, set, &priv->binding);
 122         if (err < 0)
 123                 return err;
 124
 125         priv->set = set;
 126         return 0;
 127 }
 128
 129 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 130                                const struct nft_expr *expr)
 131 {
 132         struct nft_lookup *priv = nft_expr_priv(expr);
 133
 134         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 135 }
 136
 137 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 138 {
 139         const struct nft_lookup *priv = nft_expr_priv(expr);
 140         u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
 141
 142         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 143                 goto nla_put_failure;
 144         if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 145                 goto nla_put_failure;
 146         if (priv->set->flags & NFT_SET_MAP)
 147                 if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 148                         goto nla_put_failure;
 149         if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
 150                 goto nla_put_failure;
 151         return 0;
 152
 153 nla_put_failure:
 154         return -1;
 155 }
 156
 157 static const struct nft_expr_ops nft_lookup_ops = {
 158         .type           = &nft_lookup_type,
 159         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 160         .eval           = nft_lookup_eval,
 161         .init           = nft_lookup_init,
 162         .destroy        = nft_lookup_destroy,
 163         .dump           = nft_lookup_dump,
 164 };
 165
 166 struct nft_expr_type nft_lookup_type __read_mostly = {
 167         .name           = "lookup",
 168         .ops            = &nft_lookup_ops,
 169         .policy         = nft_lookup_policy,
 170         .maxattr        = NFTA_LOOKUP_MAX,
 171         .owner          = THIS_MODULE,
 172 };