summaryrefslogtreecommitdiff
path: root/net/netfilter/nft_hash.c
blob: f829f5289e162358faf9e15d2de1aa1ae6fd0a0e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <linux/jhash.h>

struct nft_jhash {
	u8			sreg;
	u8			dreg;
	u8			len;
	bool			autogen_seed:1;
	u32			modulus;
	u32			seed;
	u32			offset;
};

static void nft_jhash_eval(const struct nft_expr *expr,
			   struct nft_regs *regs,
			   const struct nft_pktinfo *pkt)
{
	struct nft_jhash *priv = nft_expr_priv(expr);
	const void *data = &regs->data[priv->sreg];
	u32 h;

	h = reciprocal_scale(jhash(data, priv->len, priv->seed),
			     priv->modulus);

	regs->data[priv->dreg] = h + priv->offset;
}

struct nft_symhash {
	u8			dreg;
	u32			modulus;
	u32			offset;
};

static void nft_symhash_eval(const struct nft_expr *expr,
			     struct nft_regs *regs,
			     const struct nft_pktinfo *pkt)
{
	struct nft_symhash *priv = nft_expr_priv(expr);
	struct sk_buff *skb = pkt->skb;
	u32 h;

	h = reciprocal_scale(__skb_get_hash_symmetric(skb), priv->modulus);

	regs->data[priv->dreg] = h + priv->offset;
}

static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
	[NFTA_HASH_SREG]	= { .type = NLA_U32 },
	[NFTA_HASH_DREG]	= { .type = NLA_U32 },
	[NFTA_HASH_LEN]		= { .type = NLA_U32 },
	[NFTA_HASH_MODULUS]	= { .type = NLA_U32 },
	[NFTA_HASH_SEED]	= { .type = NLA_U32 },
	[NFTA_HASH_OFFSET]	= { .type = NLA_U32 },
	[NFTA_HASH_TYPE]	= { .type = NLA_U32 },
};

static int nft_jhash_init(const struct nft_ctx *ctx,
			  const struct nft_expr *expr,
			  const struct nlattr * const tb[])
{
	struct nft_jhash *priv = nft_expr_priv(expr);
	u32 len;
	int err;

	if (!tb[NFTA_HASH_SREG] ||
	    !tb[NFTA_HASH_DREG] ||
	    !tb[NFTA_HASH_LEN]  ||
	    !tb[NFTA_HASH_MODULUS])
		return -EINVAL;

	if (tb[NFTA_HASH_OFFSET])
		priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));

	err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
	if (err < 0)
		return err;
	if (len == 0)
		return -ERANGE;

	priv->len = len;

	err = nft_parse_register_load(tb[NFTA_HASH_SREG], &priv->sreg, len);
	if (err < 0)
		return err;

	priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
	if (priv->modulus < 1)
		return -ERANGE;

	if (priv->offset + priv->modulus - 1 < priv->offset)
		return -EOVERFLOW;

	if (tb[NFTA_HASH_SEED]) {
		priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
	} else {
		priv->autogen_seed = true;
		get_random_bytes(&priv->seed, sizeof(priv->seed));
	}

	return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], &priv->dreg,
					NULL, NFT_DATA_VALUE, sizeof(u32));
}

static int nft_symhash_init(const struct nft_ctx *ctx,
			    const struct nft_expr *expr,
			    const struct nlattr * const tb[])
{
	struct nft_symhash *priv = nft_expr_priv(expr);

	if (!tb[NFTA_HASH_DREG]    ||
	    !tb[NFTA_HASH_MODULUS])
		return -EINVAL;

	if (tb[NFTA_HASH_OFFSET])
		priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));

	priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
	if (priv->modulus < 1)
		return -ERANGE;

	if (priv->offset + priv->modulus - 1 < priv->offset)
		return -EOVERFLOW;

	return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG],
					&priv->dreg, NULL, NFT_DATA_VALUE,
					sizeof(u32));
}

static int nft_jhash_dump(struct sk_buff *skb,
			  const struct nft_expr *expr)
{
	const struct nft_jhash *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
		goto nla_put_failure;
	if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
		goto nla_put_failure;
	if (!priv->autogen_seed &&
	    nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
		goto nla_put_failure;
	if (priv->offset != 0)
		if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
			goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static int nft_symhash_dump(struct sk_buff *skb,
			    const struct nft_expr *expr)
{
	const struct nft_symhash *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
		goto nla_put_failure;
	if (priv->offset != 0)
		if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
			goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static struct nft_expr_type nft_hash_type;
static const struct nft_expr_ops nft_jhash_ops = {
	.type		= &nft_hash_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
	.eval		= nft_jhash_eval,
	.init		= nft_jhash_init,
	.dump		= nft_jhash_dump,
};

static const struct nft_expr_ops nft_symhash_ops = {
	.type		= &nft_hash_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
	.eval		= nft_symhash_eval,
	.init		= nft_symhash_init,
	.dump		= nft_symhash_dump,
};

static const struct nft_expr_ops *
nft_hash_select_ops(const struct nft_ctx *ctx,
		    const struct nlattr * const tb[])
{
	u32 type;

	if (!tb[NFTA_HASH_TYPE])
		return &nft_jhash_ops;

	type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
	switch (type) {
	case NFT_HASH_SYM:
		return &nft_symhash_ops;
	case NFT_HASH_JENKINS:
		return &nft_jhash_ops;
	default:
		break;
	}
	return ERR_PTR(-EOPNOTSUPP);
}

static struct nft_expr_type nft_hash_type __read_mostly = {
	.name		= "hash",
	.select_ops	= nft_hash_select_ops,
	.policy		= nft_hash_policy,
	.maxattr	= NFTA_HASH_MAX,
	.owner		= THIS_MODULE,
};

static int __init nft_hash_module_init(void)
{
	return nft_register_expr(&nft_hash_type);
}

static void __exit nft_hash_module_exit(void)
{
	nft_unregister_expr(&nft_hash_type);
}

module_init(nft_hash_module_init);
module_exit(nft_hash_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
MODULE_ALIAS_NFT_EXPR("hash");
MODULE_DESCRIPTION("Netfilter nftables hash module");