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
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	priv->dreg   = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
73
74	return nft_validate_register_store(ctx, priv->dreg, NULL,
75					   NFT_DATA_VALUE, priv->len);
76}
77
78static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
79{
80	const struct nft_exthdr *priv = nft_expr_priv(expr);
81
82	if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
83		goto nla_put_failure;
84	if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
85		goto nla_put_failure;
86	if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
87		goto nla_put_failure;
88	if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
89		goto nla_put_failure;
90	return 0;
91
92nla_put_failure:
93	return -1;
94}
95
96static struct nft_expr_type nft_exthdr_type;
97static const struct nft_expr_ops nft_exthdr_ops = {
98	.type		= &nft_exthdr_type,
99	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
100	.eval		= nft_exthdr_eval,
101	.init		= nft_exthdr_init,
102	.dump		= nft_exthdr_dump,
103};
104
105static struct nft_expr_type nft_exthdr_type __read_mostly = {
106	.name		= "exthdr",
107	.ops		= &nft_exthdr_ops,
108	.policy		= nft_exthdr_policy,
109	.maxattr	= NFTA_EXTHDR_MAX,
110	.owner		= THIS_MODULE,
111};
112
113static int __init nft_exthdr_module_init(void)
114{
115	return nft_register_expr(&nft_exthdr_type);
116}
117
118static void __exit nft_exthdr_module_exit(void)
119{
120	nft_unregister_expr(&nft_exthdr_type);
121}
122
123module_init(nft_exthdr_module_init);
124module_exit(nft_exthdr_module_exit);
125
126MODULE_LICENSE("GPL");
127MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
128MODULE_ALIAS_NFT_EXPR("exthdr");
129