Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
4 */
5
6#include <linux/kernel.h>
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/netlink.h>
10#include <linux/netfilter.h>
11#include <linux/netfilter/nf_tables.h>
12#include <linux/random.h>
13#include <linux/static_key.h>
14#include <net/netfilter/nf_tables.h>
15#include <net/netfilter/nf_tables_core.h>
16
17struct nft_ng_inc {
18 u8 dreg;
19 u32 modulus;
20 atomic_t *counter;
21 u32 offset;
22};
23
24static u32 nft_ng_inc_gen(struct nft_ng_inc *priv)
25{
26 u32 nval, oval;
27
28 do {
29 oval = atomic_read(priv->counter);
30 nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
31 } while (atomic_cmpxchg(priv->counter, oval, nval) != oval);
32
33 return nval + priv->offset;
34}
35
36static void nft_ng_inc_eval(const struct nft_expr *expr,
37 struct nft_regs *regs,
38 const struct nft_pktinfo *pkt)
39{
40 struct nft_ng_inc *priv = nft_expr_priv(expr);
41
42 regs->data[priv->dreg] = nft_ng_inc_gen(priv);
43}
44
45static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
46 [NFTA_NG_DREG] = NLA_POLICY_MAX(NLA_BE32, NFT_REG32_MAX),
47 [NFTA_NG_MODULUS] = { .type = NLA_U32 },
48 [NFTA_NG_TYPE] = { .type = NLA_U32 },
49 [NFTA_NG_OFFSET] = { .type = NLA_U32 },
50};
51
52static int nft_ng_inc_init(const struct nft_ctx *ctx,
53 const struct nft_expr *expr,
54 const struct nlattr * const tb[])
55{
56 struct nft_ng_inc *priv = nft_expr_priv(expr);
57 int err;
58
59 if (tb[NFTA_NG_OFFSET])
60 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
61
62 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
63 if (priv->modulus == 0)
64 return -ERANGE;
65
66 if (priv->offset + priv->modulus - 1 < priv->offset)
67 return -EOVERFLOW;
68
69 priv->counter = kmalloc_obj(*priv->counter, GFP_KERNEL_ACCOUNT);
70 if (!priv->counter)
71 return -ENOMEM;
72
73 atomic_set(priv->counter, priv->modulus - 1);
74
75 err = nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
76 NULL, NFT_DATA_VALUE, sizeof(u32));
77 if (err < 0)
78 goto err;
79
80 return 0;
81err:
82 kfree(priv->counter);
83
84 return err;
85}
86
87static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
88 u32 modulus, enum nft_ng_types type, u32 offset)
89{
90 if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
91 goto nla_put_failure;
92 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
93 goto nla_put_failure;
94 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
95 goto nla_put_failure;
96 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
97 goto nla_put_failure;
98
99 return 0;
100
101nla_put_failure:
102 return -1;
103}
104
105static int nft_ng_inc_dump(struct sk_buff *skb,
106 const struct nft_expr *expr, bool reset)
107{
108 const struct nft_ng_inc *priv = nft_expr_priv(expr);
109
110 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
111 priv->offset);
112}
113
114static void nft_ng_inc_destroy(const struct nft_ctx *ctx,
115 const struct nft_expr *expr)
116{
117 const struct nft_ng_inc *priv = nft_expr_priv(expr);
118
119 kfree(priv->counter);
120}
121
122struct nft_ng_random {
123 u8 dreg;
124 u32 modulus;
125 u32 offset;
126};
127
128static u32 nft_ng_random_gen(const struct nft_ng_random *priv)
129{
130 return reciprocal_scale(get_random_u32(), priv->modulus) + priv->offset;
131}
132
133static void nft_ng_random_eval(const struct nft_expr *expr,
134 struct nft_regs *regs,
135 const struct nft_pktinfo *pkt)
136{
137 struct nft_ng_random *priv = nft_expr_priv(expr);
138
139 regs->data[priv->dreg] = nft_ng_random_gen(priv);
140}
141
142static int nft_ng_random_init(const struct nft_ctx *ctx,
143 const struct nft_expr *expr,
144 const struct nlattr * const tb[])
145{
146 struct nft_ng_random *priv = nft_expr_priv(expr);
147
148 if (tb[NFTA_NG_OFFSET])
149 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
150
151 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
152 if (priv->modulus == 0)
153 return -ERANGE;
154
155 if (priv->offset + priv->modulus - 1 < priv->offset)
156 return -EOVERFLOW;
157
158 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
159 NULL, NFT_DATA_VALUE, sizeof(u32));
160}
161
162static int nft_ng_random_dump(struct sk_buff *skb,
163 const struct nft_expr *expr, bool reset)
164{
165 const struct nft_ng_random *priv = nft_expr_priv(expr);
166
167 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
168 priv->offset);
169}
170
171static struct nft_expr_type nft_ng_type;
172static const struct nft_expr_ops nft_ng_inc_ops = {
173 .type = &nft_ng_type,
174 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
175 .eval = nft_ng_inc_eval,
176 .init = nft_ng_inc_init,
177 .destroy = nft_ng_inc_destroy,
178 .dump = nft_ng_inc_dump,
179};
180
181static const struct nft_expr_ops nft_ng_random_ops = {
182 .type = &nft_ng_type,
183 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
184 .eval = nft_ng_random_eval,
185 .init = nft_ng_random_init,
186 .dump = nft_ng_random_dump,
187};
188
189static const struct nft_expr_ops *
190nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
191{
192 u32 type;
193
194 if (!tb[NFTA_NG_DREG] ||
195 !tb[NFTA_NG_MODULUS] ||
196 !tb[NFTA_NG_TYPE])
197 return ERR_PTR(-EINVAL);
198
199 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
200
201 switch (type) {
202 case NFT_NG_INCREMENTAL:
203 return &nft_ng_inc_ops;
204 case NFT_NG_RANDOM:
205 return &nft_ng_random_ops;
206 }
207
208 return ERR_PTR(-EINVAL);
209}
210
211static struct nft_expr_type nft_ng_type __read_mostly = {
212 .name = "numgen",
213 .select_ops = nft_ng_select_ops,
214 .policy = nft_ng_policy,
215 .maxattr = NFTA_NG_MAX,
216 .owner = THIS_MODULE,
217};
218
219static int __init nft_ng_module_init(void)
220{
221 return nft_register_expr(&nft_ng_type);
222}
223
224static void __exit nft_ng_module_exit(void)
225{
226 nft_unregister_expr(&nft_ng_type);
227}
228
229module_init(nft_ng_module_init);
230module_exit(nft_ng_module_exit);
231
232MODULE_LICENSE("GPL");
233MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
234MODULE_ALIAS_NFT_EXPR("numgen");
235MODULE_DESCRIPTION("nftables number generator module");