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         int d1, d2;
  32
  33         d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
  34         d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);
  35         switch (priv->op) {
  36         case NFT_RANGE_EQ:
  37                 if (d1 < 0 || d2 > 0)
  38                         regs->verdict.code = NFT_BREAK;
  39                 break;
  40         case NFT_RANGE_NEQ:
  41                 if (d1 >= 0 && d2 <= 0)
  42                         regs->verdict.code = NFT_BREAK;
  43                 break;
  44         }
  45 }
  46
  47 static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {
  48         [NFTA_RANGE_SREG]               = { .type = NLA_U32 },
  49         [NFTA_RANGE_OP]                 = { .type = NLA_U32 },
  50         [NFTA_RANGE_FROM_DATA]          = { .type = NLA_NESTED },
  51         [NFTA_RANGE_TO_DATA]            = { .type = NLA_NESTED },
  52 };
  53
  54 static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  55                         const struct nlattr * const tb[])
  56 {
  57         struct nft_range_expr *priv = nft_expr_priv(expr);
  58         struct nft_data_desc desc_from, desc_to;
  59         int err;
  60         u32 op;
  61
  62         if (!tb[NFTA_RANGE_SREG]      ||
  63             !tb[NFTA_RANGE_OP]        ||
  64             !tb[NFTA_RANGE_FROM_DATA] ||
  65             !tb[NFTA_RANGE_TO_DATA])
  66                 return -EINVAL;
  67
  68         err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),
  69                             &desc_from, tb[NFTA_RANGE_FROM_DATA]);
  70         if (err < 0)
  71                 return err;
  72
  73         err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to),
  74                             &desc_to, tb[NFTA_RANGE_TO_DATA]);
  75         if (err < 0)
  76                 goto err1;
  77
  78         if (desc_from.len != desc_to.len) {
  79                 err = -EINVAL;
  80                 goto err2;
  81         }
  82
  83         priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]);
  84         err = nft_validate_register_load(priv->sreg, desc_from.len);
  85         if (err < 0)
  86                 goto err2;
  87
  88         err = nft_parse_u32_check(tb[NFTA_RANGE_OP], U8_MAX, &op);
  89         if (err < 0)
  90                 goto err2;
  91
  92         switch (op) {
  93         case NFT_RANGE_EQ:
  94         case NFT_RANGE_NEQ:
  95                 break;
  96         default:
  97                 err = -EINVAL;
  98                 goto err2;
  99         }
 100
 101         priv->op  = op;
 102         priv->len = desc_from.len;
 103         return 0;
 104 err2:
 105         nft_data_uninit(&priv->data_to, desc_to.type);
 106 err1:
 107         nft_data_uninit(&priv->data_from, desc_from.type);
 108         return err;
 109 }
 110
 111 static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr)
 112 {
 113         const struct nft_range_expr *priv = nft_expr_priv(expr);
 114
 115         if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg))
 116                 goto nla_put_failure;
 117         if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))
 118                 goto nla_put_failure;
 119
 120         if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,
 121                           NFT_DATA_VALUE, priv->len) < 0 ||
 122             nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,
 123                           NFT_DATA_VALUE, priv->len) < 0)
 124                 goto nla_put_failure;
 125         return 0;
 126
 127 nla_put_failure:
 128         return -1;
 129 }
 130
 131 static struct nft_expr_type nft_range_type;
 132 static const struct nft_expr_ops nft_range_ops = {
 133         .type           = &nft_range_type,
 134         .size           = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),
 135         .eval           = nft_range_eval,
 136         .init           = nft_range_init,
 137         .dump           = nft_range_dump,
 138 };
 139
 140 static struct nft_expr_type nft_range_type __read_mostly = {
 141         .name           = "range",
 142         .ops            = &nft_range_ops,
 143         .policy         = nft_range_policy,
 144         .maxattr        = NFTA_RANGE_MAX,
 145         .owner          = THIS_MODULE,
 146 };
 147
 148 int __init nft_range_module_init(void)
 149 {
 150         return nft_register_expr(&nft_range_type);
 151 }
 152
 153 void nft_range_module_exit(void)
 154 {
 155         nft_unregister_expr(&nft_range_type);
 156 }