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
251
252
253
254
255
|
// 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 <linux/random.h>
#include <linux/static_key.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
struct nft_ng_inc {
u8 dreg;
u32 modulus;
atomic_t *counter;
u32 offset;
};
static u32 nft_ng_inc_gen(struct nft_ng_inc *priv)
{
u32 nval, oval;
do {
oval = atomic_read(priv->counter);
nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
} while (atomic_cmpxchg(priv->counter, oval, nval) != oval);
return nval + priv->offset;
}
static void nft_ng_inc_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_ng_inc *priv = nft_expr_priv(expr);
regs->data[priv->dreg] = nft_ng_inc_gen(priv);
}
static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
[NFTA_NG_DREG] = { .type = NLA_U32 },
[NFTA_NG_MODULUS] = { .type = NLA_U32 },
[NFTA_NG_TYPE] = { .type = NLA_U32 },
[NFTA_NG_OFFSET] = { .type = NLA_U32 },
};
static int nft_ng_inc_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_ng_inc *priv = nft_expr_priv(expr);
int err;
if (tb[NFTA_NG_OFFSET])
priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
if (priv->modulus == 0)
return -ERANGE;
if (priv->offset + priv->modulus - 1 < priv->offset)
return -EOVERFLOW;
priv->counter = kmalloc(sizeof(*priv->counter), GFP_KERNEL);
if (!priv->counter)
return -ENOMEM;
atomic_set(priv->counter, priv->modulus - 1);
err = nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
NULL, NFT_DATA_VALUE, sizeof(u32));
if (err < 0)
goto err;
return 0;
err:
kfree(priv->counter);
return err;
}
static bool nft_ng_inc_reduce(struct nft_regs_track *track,
const struct nft_expr *expr)
{
const struct nft_ng_inc *priv = nft_expr_priv(expr);
nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE);
return false;
}
static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
u32 modulus, enum nft_ng_types type, u32 offset)
{
if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_ng_inc *priv = nft_expr_priv(expr);
return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
priv->offset);
}
static void nft_ng_inc_destroy(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
const struct nft_ng_inc *priv = nft_expr_priv(expr);
kfree(priv->counter);
}
struct nft_ng_random {
u8 dreg;
u32 modulus;
u32 offset;
};
static u32 nft_ng_random_gen(const struct nft_ng_random *priv)
{
return reciprocal_scale(get_random_u32(), priv->modulus) + priv->offset;
}
static void nft_ng_random_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_ng_random *priv = nft_expr_priv(expr);
regs->data[priv->dreg] = nft_ng_random_gen(priv);
}
static int nft_ng_random_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_ng_random *priv = nft_expr_priv(expr);
if (tb[NFTA_NG_OFFSET])
priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
if (priv->modulus == 0)
return -ERANGE;
if (priv->offset + priv->modulus - 1 < priv->offset)
return -EOVERFLOW;
return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
NULL, NFT_DATA_VALUE, sizeof(u32));
}
static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_ng_random *priv = nft_expr_priv(expr);
return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
priv->offset);
}
static bool nft_ng_random_reduce(struct nft_regs_track *track,
const struct nft_expr *expr)
{
const struct nft_ng_random *priv = nft_expr_priv(expr);
nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE);
return false;
}
static struct nft_expr_type nft_ng_type;
static const struct nft_expr_ops nft_ng_inc_ops = {
.type = &nft_ng_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
.eval = nft_ng_inc_eval,
.init = nft_ng_inc_init,
.destroy = nft_ng_inc_destroy,
.dump = nft_ng_inc_dump,
.reduce = nft_ng_inc_reduce,
};
static const struct nft_expr_ops nft_ng_random_ops = {
.type = &nft_ng_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
.eval = nft_ng_random_eval,
.init = nft_ng_random_init,
.dump = nft_ng_random_dump,
.reduce = nft_ng_random_reduce,
};
static const struct nft_expr_ops *
nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
{
u32 type;
if (!tb[NFTA_NG_DREG] ||
!tb[NFTA_NG_MODULUS] ||
!tb[NFTA_NG_TYPE])
return ERR_PTR(-EINVAL);
type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
switch (type) {
case NFT_NG_INCREMENTAL:
return &nft_ng_inc_ops;
case NFT_NG_RANDOM:
return &nft_ng_random_ops;
}
return ERR_PTR(-EINVAL);
}
static struct nft_expr_type nft_ng_type __read_mostly = {
.name = "numgen",
.select_ops = nft_ng_select_ops,
.policy = nft_ng_policy,
.maxattr = NFTA_NG_MAX,
.owner = THIS_MODULE,
};
static int __init nft_ng_module_init(void)
{
return nft_register_expr(&nft_ng_type);
}
static void __exit nft_ng_module_exit(void)
{
nft_unregister_expr(&nft_ng_type);
}
module_init(nft_ng_module_init);
module_exit(nft_ng_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
MODULE_ALIAS_NFT_EXPR("numgen");
MODULE_DESCRIPTION("nftables number generator module");
|
