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(pkt->net, set, &regs->data[priv->sreg], &ext) ^
  39                 priv->invert;
  40
  41         if (!found) {
  42                 regs->verdict.code = NFT_BREAK;
  43                 return;
  44         }
  45
  46         if (found && set->flags & NFT_SET_MAP)
  47                 nft_data_copy(&regs->data[priv->dreg],
  48                               nft_set_ext_data(ext), set->dlen);
  49
  50 }
  51
  52 static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
  53         [NFTA_LOOKUP_SET]       = { .type = NLA_STRING },
  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 = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET], genmask);
  75         if (IS_ERR(set)) {
  76                 if (tb[NFTA_LOOKUP_SET_ID]) {
  77                         set = nf_tables_set_lookup_byid(ctx->net,
  78                                                         tb[NFTA_LOOKUP_SET_ID],
  79                                                         genmask);
  80                 }
  81                 if (IS_ERR(set))
  82                         return PTR_ERR(set);
  83         }
  84
  85         if (set->flags & NFT_SET_EVAL)
  86                 return -EOPNOTSUPP;
  87
  88         priv->sreg = nft_parse_register(tb[NFTA_LOOKUP_SREG]);
  89         err = nft_validate_register_load(priv->sreg, set->klen);
  90         if (err < 0)
  91                 return err;
  92
  93         if (tb[NFTA_LOOKUP_FLAGS]) {
  94                 flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));
  95
  96                 if (flags & ~NFT_LOOKUP_F_INV)
  97                         return -EINVAL;
  98
  99                 if (flags & NFT_LOOKUP_F_INV) {
 100                         if (set->flags & NFT_SET_MAP)
 101                                 return -EINVAL;
 102                         priv->invert = true;
 103                 }
 104         }
 105
 106         if (tb[NFTA_LOOKUP_DREG] != NULL) {
 107                 if (priv->invert)
 108                         return -EINVAL;
 109                 if (!(set->flags & NFT_SET_MAP))
 110                         return -EINVAL;
 111
 112                 priv->dreg = nft_parse_register(tb[NFTA_LOOKUP_DREG]);
 113                 err = nft_validate_register_store(ctx, priv->dreg, NULL,
 114                                                   set->dtype, set->dlen);
 115                 if (err < 0)
 116                         return err;
 117         } else if (set->flags & NFT_SET_MAP)
 118                 return -EINVAL;
 119
 120         priv->binding.flags = set->flags & NFT_SET_MAP;
 121
 122         err = nf_tables_bind_set(ctx, set, &priv->binding);
 123         if (err < 0)
 124                 return err;
 125
 126         priv->set = set;
 127         return 0;
 128 }
 129
 130 static void nft_lookup_destroy(const struct nft_ctx *ctx,
 131                                const struct nft_expr *expr)
 132 {
 133         struct nft_lookup *priv = nft_expr_priv(expr);
 134
 135         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 136 }
 137
 138 static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
 139 {
 140         const struct nft_lookup *priv = nft_expr_priv(expr);
 141         u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;
 142
 143         if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))
 144                 goto nla_put_failure;
 145         if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))
 146                 goto nla_put_failure;
 147         if (priv->set->flags & NFT_SET_MAP)
 148                 if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))
 149                         goto nla_put_failure;
 150         if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))
 151                 goto nla_put_failure;
 152         return 0;
 153
 154 nla_put_failure:
 155         return -1;
 156 }
 157
 158 static struct nft_expr_type nft_lookup_type;
 159 static const struct nft_expr_ops nft_lookup_ops = {
 160         .type           = &nft_lookup_type,
 161         .size           = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
 162         .eval           = nft_lookup_eval,
 163         .init           = nft_lookup_init,
 164         .destroy        = nft_lookup_destroy,
 165         .dump           = nft_lookup_dump,
 166 };
 167
 168 static struct nft_expr_type nft_lookup_type __read_mostly = {
 169         .name           = "lookup",
 170         .ops            = &nft_lookup_ops,
 171         .policy         = nft_lookup_policy,
 172         .maxattr        = NFTA_LOOKUP_MAX,
 173         .owner          = THIS_MODULE,
 174 };
 175
 176 int __init nft_lookup_module_init(void)
 177 {
 178         return nft_register_expr(&nft_lookup_type);
 179 }
 180
 181 void nft_lookup_module_exit(void)
 182 {
 183         nft_unregister_expr(&nft_lookup_type);
 184 }