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_cmp_expr {
21	struct nft_data		data;
22	enum nft_registers	sreg:8;
23	u8			len;
24	enum nft_cmp_ops	op:8;
25};
26
27static void nft_cmp_eval(const struct nft_expr *expr,
28			 struct nft_data data[NFT_REG_MAX + 1],
29			 const struct nft_pktinfo *pkt)
30{
31	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
32	int d;
33
34	d = nft_data_cmp(&data[priv->sreg], &priv->data, priv->len);
35	switch (priv->op) {
36	case NFT_CMP_EQ:
37		if (d != 0)
38			goto mismatch;
39		break;
40	case NFT_CMP_NEQ:
41		if (d == 0)
42			goto mismatch;
43		break;
44	case NFT_CMP_LT:
45		if (d == 0)
46			goto mismatch;
47	case NFT_CMP_LTE:
48		if (d > 0)
49			goto mismatch;
50		break;
51	case NFT_CMP_GT:
52		if (d == 0)
53			goto mismatch;
54	case NFT_CMP_GTE:
55		if (d < 0)
56			goto mismatch;
57		break;
58	}
59	return;
60
61mismatch:
62	data[NFT_REG_VERDICT].verdict = NFT_BREAK;
63}
64
65static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
66	[NFTA_CMP_SREG]		= { .type = NLA_U32 },
67	[NFTA_CMP_OP]		= { .type = NLA_U32 },
68	[NFTA_CMP_DATA]		= { .type = NLA_NESTED },
69};
70
71static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
72			const struct nlattr * const tb[])
73{
74	struct nft_cmp_expr *priv = nft_expr_priv(expr);
75	struct nft_data_desc desc;
76	int err;
77
78	priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
79	priv->op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
80
81	err = nft_data_init(NULL, &priv->data, &desc, tb[NFTA_CMP_DATA]);
82	BUG_ON(err < 0);
83
84	priv->len = desc.len;
85	return 0;
86}
87
88static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
89{
90	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
91
92	if (nla_put_be32(skb, NFTA_CMP_SREG, htonl(priv->sreg)))
93		goto nla_put_failure;
94	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
95		goto nla_put_failure;
96
97	if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
98			  NFT_DATA_VALUE, priv->len) < 0)
99		goto nla_put_failure;
100	return 0;
101
102nla_put_failure:
103	return -1;
104}
105
106static struct nft_expr_type nft_cmp_type;
107static const struct nft_expr_ops nft_cmp_ops = {
108	.type		= &nft_cmp_type,
109	.size		= NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
110	.eval		= nft_cmp_eval,
111	.init		= nft_cmp_init,
112	.dump		= nft_cmp_dump,
113};
114
115static int nft_cmp_fast_init(const struct nft_ctx *ctx,
116			     const struct nft_expr *expr,
117			     const struct nlattr * const tb[])
118{
119	struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
120	struct nft_data_desc desc;
121	struct nft_data data;
122	u32 mask;
123	int err;
124
125	priv->sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
126
127	err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
128	BUG_ON(err < 0);
129	desc.len *= BITS_PER_BYTE;
130
131	mask = nft_cmp_fast_mask(desc.len);
132	priv->data = data.data[0] & mask;
133	priv->len  = desc.len;
134	return 0;
135}
136
137static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
138{
139	const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
140	struct nft_data data;
141
142	if (nla_put_be32(skb, NFTA_CMP_SREG, htonl(priv->sreg)))
143		goto nla_put_failure;
144	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
145		goto nla_put_failure;
146
147	data.data[0] = priv->data;
148	if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
149			  NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
150		goto nla_put_failure;
151	return 0;
152
153nla_put_failure:
154	return -1;
155}
156
157const struct nft_expr_ops nft_cmp_fast_ops = {
158	.type		= &nft_cmp_type,
159	.size		= NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
160	.eval		= NULL,	/* inlined */
161	.init		= nft_cmp_fast_init,
162	.dump		= nft_cmp_fast_dump,
163};
164
165static const struct nft_expr_ops *
166nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
167{
168	struct nft_data_desc desc;
169	struct nft_data data;
170	enum nft_registers sreg;
171	enum nft_cmp_ops op;
172	int err;
173
174	if (tb[NFTA_CMP_SREG] == NULL ||
175	    tb[NFTA_CMP_OP] == NULL ||
176	    tb[NFTA_CMP_DATA] == NULL)
177		return ERR_PTR(-EINVAL);
178
179	sreg = ntohl(nla_get_be32(tb[NFTA_CMP_SREG]));
180	err = nft_validate_input_register(sreg);
181	if (err < 0)
182		return ERR_PTR(err);
183
184	op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
185	switch (op) {
186	case NFT_CMP_EQ:
187	case NFT_CMP_NEQ:
188	case NFT_CMP_LT:
189	case NFT_CMP_LTE:
190	case NFT_CMP_GT:
191	case NFT_CMP_GTE:
192		break;
193	default:
194		return ERR_PTR(-EINVAL);
195	}
196
197	err = nft_data_init(NULL, &data, &desc, tb[NFTA_CMP_DATA]);
198	if (err < 0)
199		return ERR_PTR(err);
200
201	if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
202		return &nft_cmp_fast_ops;
203	else
204		return &nft_cmp_ops;
205}
206
207static struct nft_expr_type nft_cmp_type __read_mostly = {
208	.name		= "cmp",
209	.select_ops	= nft_cmp_select_ops,
210	.policy		= nft_cmp_policy,
211	.maxattr	= NFTA_CMP_MAX,
212	.owner		= THIS_MODULE,
213};
214
215int __init nft_cmp_module_init(void)
216{
217	return nft_register_expr(&nft_cmp_type);
218}
219
220void nft_cmp_module_exit(void)
221{
222	nft_unregister_expr(&nft_cmp_type);
223}
224