net/netfilter/nft_range.c

   1 /*
   2  * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
   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
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables_core.h>
  16 #include <net/netfilter/nf_tables.h>
  17
  18 struct nft_range_expr {
  19         struct nft_data         data_from;
  20         struct nft_data         data_to;
  21         enum nft_registers      sreg:8;
  22         u8                      len;
  23         enum nft_range_ops      op:8;
  24 };
  25
  26 void nft_range_eval(const struct nft_expr *expr,
  27                     struct nft_regs *regs, const struct nft_pktinfo *pkt)
  28 {
  29         const struct nft_range_expr *priv = nft_expr_priv(expr);
  30         int d1, d2;
  31
  32         d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
  33         d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);
  34         switch (priv->op) {
  35         case NFT_RANGE_EQ:
  36                 if (d1 < 0 || d2 > 0)
  37                         regs->verdict.code = NFT_BREAK;
  38                 break;
  39         case NFT_RANGE_NEQ:
  40                 if (d1 >= 0 && d2 <= 0)
  41                         regs->verdict.code = NFT_BREAK;
  42                 break;
  43         }
  44 }
  45
  46 static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {
  47         [NFTA_RANGE_SREG]               = { .type = NLA_U32 },
  48         [NFTA_RANGE_OP]                 = { .type = NLA_U32 },
  49         [NFTA_RANGE_FROM_DATA]          = { .type = NLA_NESTED },
  50         [NFTA_RANGE_TO_DATA]            = { .type = NLA_NESTED },
  51 };
  52
  53 static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  54                         const struct nlattr * const tb[])
  55 {
  56         struct nft_range_expr *priv = nft_expr_priv(expr);
  57         struct nft_data_desc desc_from, desc_to;
  58         int err;
  59         u32 op;
  60
  61         if (!tb[NFTA_RANGE_SREG]      ||
  62             !tb[NFTA_RANGE_OP]        ||
  63             !tb[NFTA_RANGE_FROM_DATA] ||
  64             !tb[NFTA_RANGE_TO_DATA])
  65                 return -EINVAL;
  66
  67         err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),
  68                             &desc_from, tb[NFTA_RANGE_FROM_DATA]);
  69         if (err < 0)
  70                 return err;
  71
  72         err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to),
  73                             &desc_to, tb[NFTA_RANGE_TO_DATA]);
  74         if (err < 0)
  75                 goto err1;
  76
  77         if (desc_from.len != desc_to.len) {
  78                 err = -EINVAL;
  79                 goto err2;
  80         }
  81
  82         priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]);
  83         err = nft_validate_register_load(priv->sreg, desc_from.len);
  84         if (err < 0)
  85                 goto err2;
  86
  87         err = nft_parse_u32_check(tb[NFTA_RANGE_OP], U8_MAX, &op);
  88         if (err < 0)
  89                 goto err2;
  90
  91         switch (op) {
  92         case NFT_RANGE_EQ:
  93         case NFT_RANGE_NEQ:
  94                 break;
  95         default:
  96                 err = -EINVAL;
  97                 goto err2;
  98         }
  99
 100         priv->op  = op;
 101         priv->len = desc_from.len;
 102         return 0;
 103 err2:
 104         nft_data_release(&priv->data_to, desc_to.type);
 105 err1:
 106         nft_data_release(&priv->data_from, desc_from.type);
 107         return err;
 108 }
 109
 110 static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr)
 111 {
 112         const struct nft_range_expr *priv = nft_expr_priv(expr);
 113
 114         if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg))
 115                 goto nla_put_failure;
 116         if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))
 117                 goto nla_put_failure;
 118
 119         if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,
 120                           NFT_DATA_VALUE, priv->len) < 0 ||
 121             nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,
 122                           NFT_DATA_VALUE, priv->len) < 0)
 123                 goto nla_put_failure;
 124         return 0;
 125
 126 nla_put_failure:
 127         return -1;
 128 }
 129
 130 static const struct nft_expr_ops nft_range_ops = {
 131         .type           = &nft_range_type,
 132         .size           = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),
 133         .eval           = nft_range_eval,
 134         .init           = nft_range_init,
 135         .dump           = nft_range_dump,
 136 };
 137
 138 struct nft_expr_type nft_range_type __read_mostly = {
 139         .name           = "range",
 140         .ops            = &nft_range_ops,
 141         .policy         = nft_range_policy,
 142         .maxattr        = NFTA_RANGE_MAX,
 143         .owner          = THIS_MODULE,
 144 };