1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
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>
16 static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state);
25 static u32 nft_ng_inc_gen(struct nft_ng_inc *priv)
30 oval = atomic_read(&priv->counter);
31 nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
32 } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval);
34 return nval + priv->offset;
37 static void nft_ng_inc_eval(const struct nft_expr *expr,
38 struct nft_regs *regs,
39 const struct nft_pktinfo *pkt)
41 struct nft_ng_inc *priv = nft_expr_priv(expr);
43 regs->data[priv->dreg] = nft_ng_inc_gen(priv);
46 static 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 },
53 static int nft_ng_inc_init(const struct nft_ctx *ctx,
54 const struct nft_expr *expr,
55 const struct nlattr * const tb[])
57 struct nft_ng_inc *priv = nft_expr_priv(expr);
59 if (tb[NFTA_NG_OFFSET])
60 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
62 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
63 if (priv->modulus == 0)
66 if (priv->offset + priv->modulus - 1 < priv->offset)
69 atomic_set(&priv->counter, priv->modulus - 1);
71 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
72 NULL, NFT_DATA_VALUE, sizeof(u32));
75 static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
76 u32 modulus, enum nft_ng_types type, u32 offset)
78 if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
80 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
82 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
84 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
93 static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
95 const struct nft_ng_inc *priv = nft_expr_priv(expr);
97 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
101 struct nft_ng_random {
107 static u32 nft_ng_random_gen(struct nft_ng_random *priv)
109 struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);
111 return reciprocal_scale(prandom_u32_state(state), priv->modulus) +
115 static void nft_ng_random_eval(const struct nft_expr *expr,
116 struct nft_regs *regs,
117 const struct nft_pktinfo *pkt)
119 struct nft_ng_random *priv = nft_expr_priv(expr);
121 regs->data[priv->dreg] = nft_ng_random_gen(priv);
124 static int nft_ng_random_init(const struct nft_ctx *ctx,
125 const struct nft_expr *expr,
126 const struct nlattr * const tb[])
128 struct nft_ng_random *priv = nft_expr_priv(expr);
130 if (tb[NFTA_NG_OFFSET])
131 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
133 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
134 if (priv->modulus == 0)
137 if (priv->offset + priv->modulus - 1 < priv->offset)
140 prandom_init_once(&nft_numgen_prandom_state);
142 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
143 NULL, NFT_DATA_VALUE, sizeof(u32));
146 static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
148 const struct nft_ng_random *priv = nft_expr_priv(expr);
150 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
154 static struct nft_expr_type nft_ng_type;
155 static const struct nft_expr_ops nft_ng_inc_ops = {
156 .type = &nft_ng_type,
157 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
158 .eval = nft_ng_inc_eval,
159 .init = nft_ng_inc_init,
160 .dump = nft_ng_inc_dump,
163 static const struct nft_expr_ops nft_ng_random_ops = {
164 .type = &nft_ng_type,
165 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
166 .eval = nft_ng_random_eval,
167 .init = nft_ng_random_init,
168 .dump = nft_ng_random_dump,
171 static const struct nft_expr_ops *
172 nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
176 if (!tb[NFTA_NG_DREG] ||
177 !tb[NFTA_NG_MODULUS] ||
179 return ERR_PTR(-EINVAL);
181 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
184 case NFT_NG_INCREMENTAL:
185 return &nft_ng_inc_ops;
187 return &nft_ng_random_ops;
190 return ERR_PTR(-EINVAL);
193 static struct nft_expr_type nft_ng_type __read_mostly = {
195 .select_ops = nft_ng_select_ops,
196 .policy = nft_ng_policy,
197 .maxattr = NFTA_NG_MAX,
198 .owner = THIS_MODULE,
201 static int __init nft_ng_module_init(void)
203 return nft_register_expr(&nft_ng_type);
206 static void __exit nft_ng_module_exit(void)
208 nft_unregister_expr(&nft_ng_type);
211 module_init(nft_ng_module_init);
212 module_exit(nft_ng_module_exit);
214 MODULE_LICENSE("GPL");
215 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
216 MODULE_ALIAS_NFT_EXPR("numgen");
217 MODULE_DESCRIPTION("nftables number generator module");