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
 21struct nft_exthdr {
 22	u8			type;
 23	u8			offset;
 24	u8			len;
 25	enum nft_registers	dreg:8;
 26};
 27
 28static 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;
 46err:
 47	regs->verdict.code = NFT_BREAK;
 48}
 49
 50static 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
 57static 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;
 63	int err;
 64
 65	if (tb[NFTA_EXTHDR_DREG] == NULL ||
 66	    tb[NFTA_EXTHDR_TYPE] == NULL ||
 67	    tb[NFTA_EXTHDR_OFFSET] == NULL ||
 68	    tb[NFTA_EXTHDR_LEN] == NULL)
 69		return -EINVAL;
 70
 71	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
 72	if (err < 0)
 73		return err;
 74
 75	err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
 76	if (err < 0)
 77		return err;
 78
 79	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
 80	priv->offset = offset;
 81	priv->len    = len;
 82	priv->dreg   = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
 83
 84	return nft_validate_register_store(ctx, priv->dreg, NULL,
 85					   NFT_DATA_VALUE, priv->len);
 86}
 87
 88static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
 89{
 90	const struct nft_exthdr *priv = nft_expr_priv(expr);
 91
 92	if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
 93		goto nla_put_failure;
 94	if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
 95		goto nla_put_failure;
 96	if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
 97		goto nla_put_failure;
 98	if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
 99		goto nla_put_failure;
100	return 0;
101
102nla_put_failure:
103	return -1;
104}
105
106static struct nft_expr_type nft_exthdr_type;
107static const struct nft_expr_ops nft_exthdr_ops = {
108	.type		= &nft_exthdr_type,
109	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
110	.eval		= nft_exthdr_eval,
111	.init		= nft_exthdr_init,
112	.dump		= nft_exthdr_dump,
113};
114
115static struct nft_expr_type nft_exthdr_type __read_mostly = {
116	.name		= "exthdr",
117	.ops		= &nft_exthdr_ops,
118	.policy		= nft_exthdr_policy,
119	.maxattr	= NFTA_EXTHDR_MAX,
120	.owner		= THIS_MODULE,
121};
122
123static int __init nft_exthdr_module_init(void)
124{
125	return nft_register_expr(&nft_exthdr_type);
126}
127
128static void __exit nft_exthdr_module_exit(void)
129{
130	nft_unregister_expr(&nft_exthdr_type);
131}
132
133module_init(nft_exthdr_module_init);
134module_exit(nft_exthdr_module_exit);
135
136MODULE_LICENSE("GPL");
137MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
138MODULE_ALIAS_NFT_EXPR("exthdr");