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_regs *regs,
  30                             const struct nft_pktinfo *pkt)
  31 {
  32         struct nft_exthdr *priv = nft_expr_priv(expr);
  33         u32 *dest = &regs->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         dest[priv->len / NFT_REG32_SIZE] = 0;
  43         if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
  44                 goto err;
  45         return;
  46 err:
  47         regs->verdict.code = NFT_BREAK;
  48 }
  49
  50 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
  51         [NFTA_EXTHDR_DREG]              = { .type = NLA_U32 },
  52         [NFTA_EXTHDR_TYPE]              = { .type = NLA_U8 },
  53         [NFTA_EXTHDR_OFFSET]            = { .type = NLA_U32 },
  54         [NFTA_EXTHDR_LEN]               = { .type = NLA_U32 },
  55 };
  56
  57 static int nft_exthdr_init(const struct nft_ctx *ctx,
  58                            const struct nft_expr *expr,
  59                            const struct nlattr * const tb[])
  60 {
  61         struct nft_exthdr *priv = nft_expr_priv(expr);
  62         u32 offset, len, err;
  63
  64         if (tb[NFTA_EXTHDR_DREG] == NULL ||
  65             tb[NFTA_EXTHDR_TYPE] == NULL ||
  66             tb[NFTA_EXTHDR_OFFSET] == NULL ||
  67             tb[NFTA_EXTHDR_LEN] == NULL)
  68                 return -EINVAL;
  69
  70         err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
  71         if (err < 0)
  72                 return err;
  73
  74         err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
  75         if (err < 0)
  76                 return err;
  77
  78         priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
  79         priv->offset = offset;
  80         priv->len    = len;
  81         priv->dreg   = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
  82
  83         return nft_validate_register_store(ctx, priv->dreg, NULL,
  84                                            NFT_DATA_VALUE, priv->len);
  85 }
  86
  87 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
  88 {
  89         const struct nft_exthdr *priv = nft_expr_priv(expr);
  90
  91         if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
  92                 goto nla_put_failure;
  93         if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
  94                 goto nla_put_failure;
  95         if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
  96                 goto nla_put_failure;
  97         if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
  98                 goto nla_put_failure;
  99         return 0;
 100
 101 nla_put_failure:
 102         return -1;
 103 }
 104
 105 static struct nft_expr_type nft_exthdr_type;
 106 static const struct nft_expr_ops nft_exthdr_ops = {
 107         .type           = &nft_exthdr_type,
 108         .size           = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
 109         .eval           = nft_exthdr_eval,
 110         .init           = nft_exthdr_init,
 111         .dump           = nft_exthdr_dump,
 112 };
 113
 114 static struct nft_expr_type nft_exthdr_type __read_mostly = {
 115         .name           = "exthdr",
 116         .ops            = &nft_exthdr_ops,
 117         .policy         = nft_exthdr_policy,
 118         .maxattr        = NFTA_EXTHDR_MAX,
 119         .owner          = THIS_MODULE,
 120 };
 121
 122 static int __init nft_exthdr_module_init(void)
 123 {
 124         return nft_register_expr(&nft_exthdr_type);
 125 }
 126
 127 static void __exit nft_exthdr_module_exit(void)
 128 {
 129         nft_unregister_expr(&nft_exthdr_type);
 130 }
 131
 132 module_init(nft_exthdr_module_init);
 133 module_exit(nft_exthdr_module_exit);
 134
 135 MODULE_LICENSE("GPL");
 136 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 137 MODULE_ALIAS_NFT_EXPR("exthdr");