net/netfilter/nft_exthdr.c

   1 /*
   2  * Copyright (c) 2008 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/module.h>
  14 #include <linux/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter/nf_tables.h>
  17 #include <net/netfilter/nf_tables.h>
  18 // FIXME:
  19 #include <net/ipv6.h>
  20
  21 struct nft_exthdr {
  22         u8                      type;
  23         u8                      offset;
  24         u8                      len;
  25         enum nft_registers      dreg:8;
  26 };
  27
  28 static void nft_exthdr_eval(const struct nft_expr *expr,
  29                             struct nft_data data[NFT_REG_MAX + 1],
  30                             const struct nft_pktinfo *pkt)
  31 {
  32         struct nft_exthdr *priv = nft_expr_priv(expr);
  33         struct nft_data *dest = &data[priv->dreg];
  34         unsigned int offset = 0;
  35         int err;
  36
  37         err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
  38         if (err < 0)
  39                 goto err;
  40         offset += priv->offset;
  41
  42         if (skb_copy_bits(pkt->skb, offset, dest->data, priv->len) < 0)
  43                 goto err;
  44         return;
  45 err:
  46         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  47 }
  48
  49 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
  50         [NFTA_EXTHDR_DREG]              = { .type = NLA_U32 },
  51         [NFTA_EXTHDR_TYPE]              = { .type = NLA_U8 },
  52         [NFTA_EXTHDR_OFFSET]            = { .type = NLA_U32 },
  53         [NFTA_EXTHDR_LEN]               = { .type = NLA_U32 },
  54 };
  55
  56 static int nft_exthdr_init(const struct nft_ctx *ctx,
  57                            const struct nft_expr *expr,
  58                            const struct nlattr * const tb[])
  59 {
  60         struct nft_exthdr *priv = nft_expr_priv(expr);
  61         int err;
  62
  63         if (tb[NFTA_EXTHDR_DREG] == NULL ||
  64             tb[NFTA_EXTHDR_TYPE] == NULL ||
  65             tb[NFTA_EXTHDR_OFFSET] == NULL ||
  66             tb[NFTA_EXTHDR_LEN] == NULL)
  67                 return -EINVAL;
  68
  69         priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
  70         priv->offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
  71         priv->len    = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
  72         if (priv->len == 0 ||
  73             priv->len > FIELD_SIZEOF(struct nft_data, data))
  74                 return -EINVAL;
  75
  76         priv->dreg = ntohl(nla_get_be32(tb[NFTA_EXTHDR_DREG]));
  77         err = nft_validate_output_register(priv->dreg);
  78         if (err < 0)
  79                 return err;
  80         return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
  81 }
  82
  83 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
  84 {
  85         const struct nft_exthdr *priv = nft_expr_priv(expr);
  86
  87         if (nla_put_be32(skb, NFTA_EXTHDR_DREG, htonl(priv->dreg)))
  88                 goto nla_put_failure;
  89         if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
  90                 goto nla_put_failure;
  91         if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
  92                 goto nla_put_failure;
  93         if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
  94                 goto nla_put_failure;
  95         return 0;
  96
  97 nla_put_failure:
  98         return -1;
  99 }
 100
 101 static struct nft_expr_type nft_exthdr_type;
 102 static const struct nft_expr_ops nft_exthdr_ops = {
 103         .type           = &nft_exthdr_type,
 104         .size           = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
 105         .eval           = nft_exthdr_eval,
 106         .init           = nft_exthdr_init,
 107         .dump           = nft_exthdr_dump,
 108 };
 109
 110 static struct nft_expr_type nft_exthdr_type __read_mostly = {
 111         .name           = "exthdr",
 112         .ops            = &nft_exthdr_ops,
 113         .policy         = nft_exthdr_policy,
 114         .maxattr        = NFTA_EXTHDR_MAX,
 115         .owner          = THIS_MODULE,
 116 };
 117
 118 static int __init nft_exthdr_module_init(void)
 119 {
 120         return nft_register_expr(&nft_exthdr_type);
 121 }
 122
 123 static void __exit nft_exthdr_module_exit(void)
 124 {
 125         nft_unregister_expr(&nft_exthdr_type);
 126 }
 127
 128 module_init(nft_exthdr_module_init);
 129 module_exit(nft_exthdr_module_exit);
 130
 131 MODULE_LICENSE("GPL");
 132 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 133 MODULE_ALIAS_NFT_EXPR("exthdr");