1/*
2 * Copyright (c) 2008-2009 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_core.h>
18#include <net/netfilter/nf_tables.h>
19
20struct nft_bitwise {
21	enum nft_registers	sreg:8;
22	enum nft_registers	dreg:8;
23	u8			len;
24	struct nft_data		mask;
25	struct nft_data		xor;
26};
27
28static void nft_bitwise_eval(const struct nft_expr *expr,
29			     struct nft_regs *regs,
30			     const struct nft_pktinfo *pkt)
31{
32	const struct nft_bitwise *priv = nft_expr_priv(expr);
33	const u32 *src = &regs->data[priv->sreg];
34	u32 *dst = &regs->data[priv->dreg];
35	unsigned int i;
36
37	for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
38		dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
39}
40
41static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
42	[NFTA_BITWISE_SREG]	= { .type = NLA_U32 },
43	[NFTA_BITWISE_DREG]	= { .type = NLA_U32 },
44	[NFTA_BITWISE_LEN]	= { .type = NLA_U32 },
45	[NFTA_BITWISE_MASK]	= { .type = NLA_NESTED },
46	[NFTA_BITWISE_XOR]	= { .type = NLA_NESTED },
47};
48
49static int nft_bitwise_init(const struct nft_ctx *ctx,
50			    const struct nft_expr *expr,
51			    const struct nlattr * const tb[])
52{
53	struct nft_bitwise *priv = nft_expr_priv(expr);
54	struct nft_data_desc d1, d2;
55	int err;
56
57	if (tb[NFTA_BITWISE_SREG] == NULL ||
58	    tb[NFTA_BITWISE_DREG] == NULL ||
59	    tb[NFTA_BITWISE_LEN] == NULL ||
60	    tb[NFTA_BITWISE_MASK] == NULL ||
61	    tb[NFTA_BITWISE_XOR] == NULL)
62		return -EINVAL;
63
64	priv->len  = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));
65	priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
66	err = nft_validate_register_load(priv->sreg, priv->len);
67	if (err < 0)
68		return err;
69
70	priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
71	err = nft_validate_register_store(ctx, priv->dreg, NULL,
72					  NFT_DATA_VALUE, priv->len);
73	if (err < 0)
74		return err;
75
76	err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &d1,
77			    tb[NFTA_BITWISE_MASK]);
78	if (err < 0)
79		return err;
80	if (d1.len != priv->len)
81		return -EINVAL;
82
83	err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &d2,
84			    tb[NFTA_BITWISE_XOR]);
85	if (err < 0)
86		return err;
87	if (d2.len != priv->len)
88		return -EINVAL;
89
90	return 0;
91}
92
93static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
94{
95	const struct nft_bitwise *priv = nft_expr_priv(expr);
96
97	if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
98		goto nla_put_failure;
99	if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
100		goto nla_put_failure;
101	if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
102		goto nla_put_failure;
103
104	if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
105			  NFT_DATA_VALUE, priv->len) < 0)
106		goto nla_put_failure;
107
108	if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
109			  NFT_DATA_VALUE, priv->len) < 0)
110		goto nla_put_failure;
111
112	return 0;
113
114nla_put_failure:
115	return -1;
116}
117
118static struct nft_expr_type nft_bitwise_type;
119static const struct nft_expr_ops nft_bitwise_ops = {
120	.type		= &nft_bitwise_type,
121	.size		= NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
122	.eval		= nft_bitwise_eval,
123	.init		= nft_bitwise_init,
124	.dump		= nft_bitwise_dump,
125};
126
127static struct nft_expr_type nft_bitwise_type __read_mostly = {
128	.name		= "bitwise",
129	.ops		= &nft_bitwise_ops,
130	.policy		= nft_bitwise_policy,
131	.maxattr	= NFTA_BITWISE_MAX,
132	.owner		= THIS_MODULE,
133};
134
135int __init nft_bitwise_module_init(void)
136{
137	return nft_register_expr(&nft_bitwise_type);
138}
139
140void nft_bitwise_module_exit(void)
141{
142	nft_unregister_expr(&nft_bitwise_type);
143}
144