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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/static_key.h>
13#include <net/netfilter/nf_tables.h>
14#include <net/netfilter/nf_tables_core.h>
15
16static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state);
17
18struct nft_ng_inc {
19 u8 dreg;
20 u32 modulus;
21 atomic_t *counter;
22 u32 offset;
23};
24
25static u32 nft_ng_inc_gen(struct nft_ng_inc *priv)
26{
27 u32 nval, oval;
28
29 do {
30 oval = atomic_read(priv->counter);
31 nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
32 } while (atomic_cmpxchg(priv->counter, oval, nval) != oval);
33
34 return nval + priv->offset;
35}
36
37static void nft_ng_inc_eval(const struct nft_expr *expr,
38 struct nft_regs *regs,
39 const struct nft_pktinfo *pkt)
40{
41 struct nft_ng_inc *priv = nft_expr_priv(expr);
42
43 regs->data[priv->dreg] = nft_ng_inc_gen(priv);
44}
45
46static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
47 [NFTA_NG_DREG] = { .type = NLA_U32 },
48 [NFTA_NG_MODULUS] = { .type = NLA_U32 },
49 [NFTA_NG_TYPE] = { .type = NLA_U32 },
50 [NFTA_NG_OFFSET] = { .type = NLA_U32 },
51};
52
53static int nft_ng_inc_init(const struct nft_ctx *ctx,
54 const struct nft_expr *expr,
55 const struct nlattr * const tb[])
56{
57 struct nft_ng_inc *priv = nft_expr_priv(expr);
58 int err;
59
60 if (tb[NFTA_NG_OFFSET])
61 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
62
63 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
64 if (priv->modulus == 0)
65 return -ERANGE;
66
67 if (priv->offset + priv->modulus - 1 < priv->offset)
68 return -EOVERFLOW;
69
70 priv->counter = kmalloc(sizeof(*priv->counter), GFP_KERNEL);
71 if (!priv->counter)
72 return -ENOMEM;
73
74 atomic_set(priv->counter, priv->modulus - 1);
75
76 err = nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
77 NULL, NFT_DATA_VALUE, sizeof(u32));
78 if (err < 0)
79 goto err;
80
81 return 0;
82err:
83 kfree(priv->counter);
84
85 return err;
86}
87
88static bool nft_ng_inc_reduce(struct nft_regs_track *track,
89 const struct nft_expr *expr)
90{
91 const struct nft_ng_inc *priv = nft_expr_priv(expr);
92
93 nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE);
94
95 return false;
96}
97
98static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
99 u32 modulus, enum nft_ng_types type, u32 offset)
100{
101 if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
102 goto nla_put_failure;
103 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
104 goto nla_put_failure;
105 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
106 goto nla_put_failure;
107 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
108 goto nla_put_failure;
109
110 return 0;
111
112nla_put_failure:
113 return -1;
114}
115
116static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
117{
118 const struct nft_ng_inc *priv = nft_expr_priv(expr);
119
120 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
121 priv->offset);
122}
123
124static void nft_ng_inc_destroy(const struct nft_ctx *ctx,
125 const struct nft_expr *expr)
126{
127 const struct nft_ng_inc *priv = nft_expr_priv(expr);
128
129 kfree(priv->counter);
130}
131
132struct nft_ng_random {
133 u8 dreg;
134 u32 modulus;
135 u32 offset;
136};
137
138static u32 nft_ng_random_gen(struct nft_ng_random *priv)
139{
140 struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);
141
142 return reciprocal_scale(prandom_u32_state(state), priv->modulus) +
143 priv->offset;
144}
145
146static void nft_ng_random_eval(const struct nft_expr *expr,
147 struct nft_regs *regs,
148 const struct nft_pktinfo *pkt)
149{
150 struct nft_ng_random *priv = nft_expr_priv(expr);
151
152 regs->data[priv->dreg] = nft_ng_random_gen(priv);
153}
154
155static int nft_ng_random_init(const struct nft_ctx *ctx,
156 const struct nft_expr *expr,
157 const struct nlattr * const tb[])
158{
159 struct nft_ng_random *priv = nft_expr_priv(expr);
160
161 if (tb[NFTA_NG_OFFSET])
162 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
163
164 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
165 if (priv->modulus == 0)
166 return -ERANGE;
167
168 if (priv->offset + priv->modulus - 1 < priv->offset)
169 return -EOVERFLOW;
170
171 prandom_init_once(&nft_numgen_prandom_state);
172
173 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
174 NULL, NFT_DATA_VALUE, sizeof(u32));
175}
176
177static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
178{
179 const struct nft_ng_random *priv = nft_expr_priv(expr);
180
181 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
182 priv->offset);
183}
184
185static bool nft_ng_random_reduce(struct nft_regs_track *track,
186 const struct nft_expr *expr)
187{
188 const struct nft_ng_random *priv = nft_expr_priv(expr);
189
190 nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE);
191
192 return false;
193}
194
195static struct nft_expr_type nft_ng_type;
196static const struct nft_expr_ops nft_ng_inc_ops = {
197 .type = &nft_ng_type,
198 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
199 .eval = nft_ng_inc_eval,
200 .init = nft_ng_inc_init,
201 .destroy = nft_ng_inc_destroy,
202 .dump = nft_ng_inc_dump,
203 .reduce = nft_ng_inc_reduce,
204};
205
206static const struct nft_expr_ops nft_ng_random_ops = {
207 .type = &nft_ng_type,
208 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
209 .eval = nft_ng_random_eval,
210 .init = nft_ng_random_init,
211 .dump = nft_ng_random_dump,
212 .reduce = nft_ng_random_reduce,
213};
214
215static const struct nft_expr_ops *
216nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
217{
218 u32 type;
219
220 if (!tb[NFTA_NG_DREG] ||
221 !tb[NFTA_NG_MODULUS] ||
222 !tb[NFTA_NG_TYPE])
223 return ERR_PTR(-EINVAL);
224
225 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
226
227 switch (type) {
228 case NFT_NG_INCREMENTAL:
229 return &nft_ng_inc_ops;
230 case NFT_NG_RANDOM:
231 return &nft_ng_random_ops;
232 }
233
234 return ERR_PTR(-EINVAL);
235}
236
237static struct nft_expr_type nft_ng_type __read_mostly = {
238 .name = "numgen",
239 .select_ops = nft_ng_select_ops,
240 .policy = nft_ng_policy,
241 .maxattr = NFTA_NG_MAX,
242 .owner = THIS_MODULE,
243};
244
245static int __init nft_ng_module_init(void)
246{
247 return nft_register_expr(&nft_ng_type);
248}
249
250static void __exit nft_ng_module_exit(void)
251{
252 nft_unregister_expr(&nft_ng_type);
253}
254
255module_init(nft_ng_module_init);
256module_exit(nft_ng_module_exit);
257
258MODULE_LICENSE("GPL");
259MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
260MODULE_ALIAS_NFT_EXPR("numgen");
261MODULE_DESCRIPTION("nftables number generator module");
262
