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].data[0];
  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, priv->len) < 0)
  43                 goto err;
  44         return;
  45 err:
  46         regs->verdict.code = 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
  62         if (tb[NFTA_EXTHDR_DREG] == NULL ||
  63             tb[NFTA_EXTHDR_TYPE] == NULL ||
  64             tb[NFTA_EXTHDR_OFFSET] == NULL ||
  65             tb[NFTA_EXTHDR_LEN] == NULL)
  66                 return -EINVAL;
  67
  68         priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
  69         priv->offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
  70         priv->len    = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
  71         priv->dreg   = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
  72
  73         return nft_validate_register_store(ctx, priv->dreg, NULL,
  74                                            NFT_DATA_VALUE, priv->len);
  75 }
  76
  77 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
  78 {
  79         const struct nft_exthdr *priv = nft_expr_priv(expr);
  80
  81         if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
  82                 goto nla_put_failure;
  83         if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
  84                 goto nla_put_failure;
  85         if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
  86                 goto nla_put_failure;
  87         if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
  88                 goto nla_put_failure;
  89         return 0;
  90
  91 nla_put_failure:
  92         return -1;
  93 }
  94
  95 static struct nft_expr_type nft_exthdr_type;
  96 static const struct nft_expr_ops nft_exthdr_ops = {
  97         .type           = &nft_exthdr_type,
  98         .size           = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
  99         .eval           = nft_exthdr_eval,
 100         .init           = nft_exthdr_init,
 101         .dump           = nft_exthdr_dump,
 102 };
 103
 104 static struct nft_expr_type nft_exthdr_type __read_mostly = {
 105         .name           = "exthdr",
 106         .ops            = &nft_exthdr_ops,
 107         .policy         = nft_exthdr_policy,
 108         .maxattr        = NFTA_EXTHDR_MAX,
 109         .owner          = THIS_MODULE,
 110 };
 111
 112 static int __init nft_exthdr_module_init(void)
 113 {
 114         return nft_register_expr(&nft_exthdr_type);
 115 }
 116
 117 static void __exit nft_exthdr_module_exit(void)
 118 {
 119         nft_unregister_expr(&nft_exthdr_type);
 120 }
 121
 122 module_init(nft_exthdr_module_init);
 123 module_exit(nft_exthdr_module_exit);
 124
 125 MODULE_LICENSE("GPL");
 126 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 127 MODULE_ALIAS_NFT_EXPR("exthdr");