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 static void nft_range_eval(const struct nft_expr *expr,
  27                          struct nft_regs *regs,
  28                          const struct nft_pktinfo *pkt)
  29 {
  30         const struct nft_range_expr *priv = nft_expr_priv(expr);
  31         bool mismatch;
  32         int d1, d2;
  33
  34         d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
  35         d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);
  36         switch (priv->op) {
  37         case NFT_RANGE_EQ:
  38                 mismatch = (d1 < 0 || d2 > 0);
  39                 break;
  40         case NFT_RANGE_NEQ:
  41                 mismatch = (d1 >= 0 && d2 <= 0);
  42                 break;
  43         }
  44
  45         if (mismatch)
  46                 regs->verdict.code = NFT_BREAK;
  47 }
  48
  49 static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {
  50         [NFTA_RANGE_SREG]               = { .type = NLA_U32 },
  51         [NFTA_RANGE_OP]                 = { .type = NLA_U32 },
  52         [NFTA_RANGE_FROM_DATA]          = { .type = NLA_NESTED },
  53         [NFTA_RANGE_TO_DATA]            = { .type = NLA_NESTED },
  54 };
  55
  56 static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  57                         const struct nlattr * const tb[])
  58 {
  59         struct nft_range_expr *priv = nft_expr_priv(expr);
  60         struct nft_data_desc desc_from, desc_to;
  61         int err;
  62
  63         err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),
  64                             &desc_from, tb[NFTA_RANGE_FROM_DATA]);
  65         if (err < 0)
  66                 return err;
  67
  68         err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to),
  69                             &desc_to, tb[NFTA_RANGE_TO_DATA]);
  70         if (err < 0)
  71                 goto err1;
  72
  73         if (desc_from.len != desc_to.len) {
  74                 err = -EINVAL;
  75                 goto err2;
  76         }
  77
  78         priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]);
  79         err = nft_validate_register_load(priv->sreg, desc_from.len);
  80         if (err < 0)
  81                 goto err2;
  82
  83         priv->op  = ntohl(nla_get_be32(tb[NFTA_RANGE_OP]));
  84         priv->len = desc_from.len;
  85         return 0;
  86 err2:
  87         nft_data_uninit(&priv->data_to, desc_to.type);
  88 err1:
  89         nft_data_uninit(&priv->data_from, desc_from.type);
  90         return err;
  91 }
  92
  93 static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr)
  94 {
  95         const struct nft_range_expr *priv = nft_expr_priv(expr);
  96
  97         if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg))
  98                 goto nla_put_failure;
  99         if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))
 100                 goto nla_put_failure;
 101
 102         if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,
 103                           NFT_DATA_VALUE, priv->len) < 0 ||
 104             nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,
 105                           NFT_DATA_VALUE, priv->len) < 0)
 106                 goto nla_put_failure;
 107         return 0;
 108
 109 nla_put_failure:
 110         return -1;
 111 }
 112
 113 static struct nft_expr_type nft_range_type;
 114 static const struct nft_expr_ops nft_range_ops = {
 115         .type           = &nft_range_type,
 116         .size           = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),
 117         .eval           = nft_range_eval,
 118         .init           = nft_range_init,
 119         .dump           = nft_range_dump,
 120 };
 121
 122 static struct nft_expr_type nft_range_type __read_mostly = {
 123         .name           = "range",
 124         .ops            = &nft_range_ops,
 125         .policy         = nft_range_policy,
 126         .maxattr        = NFTA_RANGE_MAX,
 127         .owner          = THIS_MODULE,
 128 };
 129
 130 int __init nft_range_module_init(void)
 131 {
 132         return nft_register_expr(&nft_range_type);
 133 }
 134
 135 void nft_range_module_exit(void)
 136 {
 137         nft_unregister_expr(&nft_range_type);
 138 }