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);
60 if (tb[NFTA_NG_OFFSET])
61 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
63 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
64 if (priv->modulus == 0)
67 if (priv->offset + priv->modulus - 1 < priv->offset)
70 priv->counter = kmalloc(sizeof(*priv->counter), GFP_KERNEL);
74 atomic_set(priv->counter, priv->modulus - 1);
76 err = nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
77 NULL, NFT_DATA_VALUE, sizeof(u32));
88 static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
89 u32 modulus, enum nft_ng_types type, u32 offset)
91 if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
93 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus)))
95 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))
97 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))
106 static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
108 const struct nft_ng_inc *priv = nft_expr_priv(expr);
110 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,
114 static void nft_ng_inc_destroy(const struct nft_ctx *ctx,
115 const struct nft_expr *expr)
117 const struct nft_ng_inc *priv = nft_expr_priv(expr);
119 kfree(priv->counter);
122 struct nft_ng_random {
128 static u32 nft_ng_random_gen(struct nft_ng_random *priv)
130 struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);
132 return reciprocal_scale(prandom_u32_state(state), priv->modulus) +
136 static void nft_ng_random_eval(const struct nft_expr *expr,
137 struct nft_regs *regs,
138 const struct nft_pktinfo *pkt)
140 struct nft_ng_random *priv = nft_expr_priv(expr);
142 regs->data[priv->dreg] = nft_ng_random_gen(priv);
145 static int nft_ng_random_init(const struct nft_ctx *ctx,
146 const struct nft_expr *expr,
147 const struct nlattr * const tb[])
149 struct nft_ng_random *priv = nft_expr_priv(expr);
151 if (tb[NFTA_NG_OFFSET])
152 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));
154 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));
155 if (priv->modulus == 0)
158 if (priv->offset + priv->modulus - 1 < priv->offset)
161 prandom_init_once(&nft_numgen_prandom_state);
163 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg,
164 NULL, NFT_DATA_VALUE, sizeof(u32));
167 static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
169 const struct nft_ng_random *priv = nft_expr_priv(expr);
171 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,
175 static struct nft_expr_type nft_ng_type;
176 static const struct nft_expr_ops nft_ng_inc_ops = {
177 .type = &nft_ng_type,
178 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
179 .eval = nft_ng_inc_eval,
180 .init = nft_ng_inc_init,
181 .destroy = nft_ng_inc_destroy,
182 .dump = nft_ng_inc_dump,
185 static const struct nft_expr_ops nft_ng_random_ops = {
186 .type = &nft_ng_type,
187 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
188 .eval = nft_ng_random_eval,
189 .init = nft_ng_random_init,
190 .dump = nft_ng_random_dump,
193 static const struct nft_expr_ops *
194 nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
198 if (!tb[NFTA_NG_DREG] ||
199 !tb[NFTA_NG_MODULUS] ||
201 return ERR_PTR(-EINVAL);
203 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
206 case NFT_NG_INCREMENTAL:
207 return &nft_ng_inc_ops;
209 return &nft_ng_random_ops;
212 return ERR_PTR(-EINVAL);
215 static struct nft_expr_type nft_ng_type __read_mostly = {
217 .select_ops = nft_ng_select_ops,
218 .policy = nft_ng_policy,
219 .maxattr = NFTA_NG_MAX,
220 .owner = THIS_MODULE,
223 static int __init nft_ng_module_init(void)
225 return nft_register_expr(&nft_ng_type);
228 static void __exit nft_ng_module_exit(void)
230 nft_unregister_expr(&nft_ng_type);
233 module_init(nft_ng_module_init);
234 module_exit(nft_ng_module_exit);
236 MODULE_LICENSE("GPL");
237 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
238 MODULE_ALIAS_NFT_EXPR("numgen");
239 MODULE_DESCRIPTION("nftables number generator module");