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10#include <linux/kernel.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/netlink.h>
14#include <linux/netfilter.h>
15#include <linux/netfilter/nf_tables.h>
16#include <linux/static_key.h>
17#include <net/netfilter/nf_tables.h>
18#include <net/netfilter/nf_tables_core.h>
19
20static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state);
21
22struct nft_ng_inc {
23 enum nft_registers dreg:8;
24 u32 modulus;
25 atomic_t counter;
26 u32 offset;
27};
28
29static void nft_ng_inc_eval(const struct nft_expr *expr,
30 struct nft_regs *regs,
31 const struct nft_pktinfo *pkt)
32{
33 struct nft_ng_inc *priv = nft_expr_priv(expr);
34 u32 nval, oval;
35
36 do {
37 oval = atomic_read(&priv->counter);
38 nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
39 } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval);
40
41 regs->data[priv->dreg] = nval + priv->offset;
42}
43
44static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
45 [NFTA_NG_DREG] = { .type = NLA_U32 },
46 [NFTA_NG_MODULUS] = { .type = NLA_U32 },
47 [NFTA_NG_TYPE] = { .type = NLA_U32 },
48 [NFTA_NG_OFFSET] = { .type = NLA_U32 },
49};
50
51static int nft_ng_inc_init(const struct nft_ctx *ctx,
52 const struct nft_expr *expr,
53 const struct nlattr * const tb[])
54{
55 struct nft_ng_inc *priv = nft_expr_priv(expr);
56
57 if (tb[NFTA_NG_OFFSET])
58 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
59
60 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
61 if (priv->modulus == 0)
62 return -ERANGE;
63
64 if (priv->offset + priv->modulus - 1 < priv->offset)
65 return -EOVERFLOW;
66
67 priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);
68 atomic_set(&priv->counter, 0);
69
70 return nft_validate_register_store(ctx, priv->dreg, NULL,
71 NFT_DATA_VALUE, sizeof(u32));
72}
73
74static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
75 u32 modulus, enum nft_ng_types type, u32 offset)
76{
77 if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
78 goto nla_put_failure;
79 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
80 goto nla_put_failure;
81 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
82 goto nla_put_failure;
83 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
84 goto nla_put_failure;
85
86 return 0;
87
88nla_put_failure:
89 return -1;
90}
91
92static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
93{
94 const struct nft_ng_inc *priv = nft_expr_priv(expr);
95
96 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
97 priv->offset);
98}
99
100struct nft_ng_random {
101 enum nft_registers dreg:8;
102 u32 modulus;
103 u32 offset;
104};
105
106static void nft_ng_random_eval(const struct nft_expr *expr,
107 struct nft_regs *regs,
108 const struct nft_pktinfo *pkt)
109{
110 struct nft_ng_random *priv = nft_expr_priv(expr);
111 struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);
112 u32 val;
113
114 val = reciprocal_scale(prandom_u32_state(state), priv->modulus);
115 regs->data[priv->dreg] = val + priv->offset;
116}
117
118static int nft_ng_random_init(const struct nft_ctx *ctx,
119 const struct nft_expr *expr,
120 const struct nlattr * const tb[])
121{
122 struct nft_ng_random *priv = nft_expr_priv(expr);
123
124 if (tb[NFTA_NG_OFFSET])
125 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
126
127 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
128 if (priv->modulus == 0)
129 return -ERANGE;
130
131 if (priv->offset + priv->modulus - 1 < priv->offset)
132 return -EOVERFLOW;
133
134 prandom_init_once(&nft_numgen_prandom_state);
135
136 priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);
137
138 return nft_validate_register_store(ctx, priv->dreg, NULL,
139 NFT_DATA_VALUE, sizeof(u32));
140}
141
142static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
143{
144 const struct nft_ng_random *priv = nft_expr_priv(expr);
145
146 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
147 priv->offset);
148}
149
150static struct nft_expr_type nft_ng_type;
151static const struct nft_expr_ops nft_ng_inc_ops = {
152 .type = &nft_ng_type,
153 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
154 .eval = nft_ng_inc_eval,
155 .init = nft_ng_inc_init,
156 .dump = nft_ng_inc_dump,
157};
158
159static const struct nft_expr_ops nft_ng_random_ops = {
160 .type = &nft_ng_type,
161 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
162 .eval = nft_ng_random_eval,
163 .init = nft_ng_random_init,
164 .dump = nft_ng_random_dump,
165};
166
167static const struct nft_expr_ops *
168nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
169{
170 u32 type;
171
172 if (!tb[NFTA_NG_DREG] ||
173 !tb[NFTA_NG_MODULUS] ||
174 !tb[NFTA_NG_TYPE])
175 return ERR_PTR(-EINVAL);
176
177 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
178
179 switch (type) {
180 case NFT_NG_INCREMENTAL:
181 return &nft_ng_inc_ops;
182 case NFT_NG_RANDOM:
183 return &nft_ng_random_ops;
184 }
185
186 return ERR_PTR(-EINVAL);
187}
188
189static struct nft_expr_type nft_ng_type __read_mostly = {
190 .name = "numgen",
191 .select_ops = &nft_ng_select_ops,
192 .policy = nft_ng_policy,
193 .maxattr = NFTA_NG_MAX,
194 .owner = THIS_MODULE,
195};
196
197static int __init nft_ng_module_init(void)
198{
199 return nft_register_expr(&nft_ng_type);
200}
201
202static void __exit nft_ng_module_exit(void)
203{
204 nft_unregister_expr(&nft_ng_type);
205}
206
207module_init(nft_ng_module_init);
208module_exit(nft_ng_module_exit);
209
210MODULE_LICENSE("GPL");
211MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
212MODULE_ALIAS_NFT_EXPR("numgen");
213
