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_regs *regs,
 29			 const struct nft_pktinfo *pkt)
 30{
 31	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 32	int d;
 33
 34	d = memcmp(&regs->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	regs->verdict.code = 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	err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
 79			    tb[NFTA_CMP_DATA]);
 80	BUG_ON(err < 0);
 81
 82	priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 83	err = nft_validate_register_load(priv->sreg, desc.len);
 84	if (err < 0)
 85		return err;
 86
 87	priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
 88	priv->len = desc.len;
 89	return 0;
 90}
 91
 92static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
 93{
 94	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
 95
 96	if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
 97		goto nla_put_failure;
 98	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
 99		goto nla_put_failure;
100
101	if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
102			  NFT_DATA_VALUE, priv->len) < 0)
103		goto nla_put_failure;
104	return 0;
105
106nla_put_failure:
107	return -1;
108}
109
110static const struct nft_expr_ops nft_cmp_ops = {
111	.type		= &nft_cmp_type,
112	.size		= NFT_EXPR_SIZE(sizeof(struct nft_cmp_expr)),
113	.eval		= nft_cmp_eval,
114	.init		= nft_cmp_init,
115	.dump		= nft_cmp_dump,
116};
117
118static int nft_cmp_fast_init(const struct nft_ctx *ctx,
119			     const struct nft_expr *expr,
120			     const struct nlattr * const tb[])
121{
122	struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
123	struct nft_data_desc desc;
124	struct nft_data data;
125	u32 mask;
126	int err;
127
128	err = nft_data_init(NULL, &data, sizeof(data), &desc,
129			    tb[NFTA_CMP_DATA]);
130	BUG_ON(err < 0);
131
132	priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
133	err = nft_validate_register_load(priv->sreg, desc.len);
134	if (err < 0)
135		return err;
136
137	desc.len *= BITS_PER_BYTE;
138	mask = nft_cmp_fast_mask(desc.len);
139
140	priv->data = data.data[0] & mask;
141	priv->len  = desc.len;
142	return 0;
143}
144
145static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
146{
147	const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
148	struct nft_data data;
149
150	if (nft_dump_register(skb, NFTA_CMP_SREG, priv->sreg))
151		goto nla_put_failure;
152	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(NFT_CMP_EQ)))
153		goto nla_put_failure;
154
155	data.data[0] = priv->data;
156	if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
157			  NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
158		goto nla_put_failure;
159	return 0;
160
161nla_put_failure:
162	return -1;
163}
164
165const struct nft_expr_ops nft_cmp_fast_ops = {
166	.type		= &nft_cmp_type,
167	.size		= NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
168	.eval		= NULL,	/* inlined */
169	.init		= nft_cmp_fast_init,
170	.dump		= nft_cmp_fast_dump,
171};
172
173static const struct nft_expr_ops *
174nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
175{
176	struct nft_data_desc desc;
177	struct nft_data data;
178	enum nft_cmp_ops op;
179	int err;
180
181	if (tb[NFTA_CMP_SREG] == NULL ||
182	    tb[NFTA_CMP_OP] == NULL ||
183	    tb[NFTA_CMP_DATA] == NULL)
184		return ERR_PTR(-EINVAL);
185
186	op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
187	switch (op) {
188	case NFT_CMP_EQ:
189	case NFT_CMP_NEQ:
190	case NFT_CMP_LT:
191	case NFT_CMP_LTE:
192	case NFT_CMP_GT:
193	case NFT_CMP_GTE:
194		break;
195	default:
196		return ERR_PTR(-EINVAL);
197	}
198
199	err = nft_data_init(NULL, &data, sizeof(data), &desc,
200			    tb[NFTA_CMP_DATA]);
201	if (err < 0)
202		return ERR_PTR(err);
203
204	if (desc.len <= sizeof(u32) && op == NFT_CMP_EQ)
205		return &nft_cmp_fast_ops;
206	else
207		return &nft_cmp_ops;
208}
209
210struct nft_expr_type nft_cmp_type __read_mostly = {
211	.name		= "cmp",
212	.select_ops	= nft_cmp_select_ops,
213	.policy		= nft_cmp_policy,
214	.maxattr	= NFTA_CMP_MAX,
215	.owner		= THIS_MODULE,
216};