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91dbc6be LGL |
1 | /* |
2 | * Copyright (c) 2016 Laura Garcia <nevola@gmail.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | */ | |
9 | ||
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 | ||
20 | static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state); | |
21 | ||
22 | struct nft_ng_inc { | |
23 | enum nft_registers dreg:8; | |
0d9932b2 | 24 | u32 modulus; |
91dbc6be | 25 | atomic_t counter; |
2b03bf73 | 26 | u32 offset; |
91dbc6be LGL |
27 | }; |
28 | ||
29 | static 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); | |
0d9932b2 | 38 | nval = (oval + 1 < priv->modulus) ? oval + 1 : 0; |
91dbc6be LGL |
39 | } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval); |
40 | ||
2b03bf73 | 41 | regs->data[priv->dreg] = nval + priv->offset; |
91dbc6be LGL |
42 | } |
43 | ||
44 | static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { | |
45 | [NFTA_NG_DREG] = { .type = NLA_U32 }, | |
0d9932b2 | 46 | [NFTA_NG_MODULUS] = { .type = NLA_U32 }, |
91dbc6be | 47 | [NFTA_NG_TYPE] = { .type = NLA_U32 }, |
2b03bf73 | 48 | [NFTA_NG_OFFSET] = { .type = NLA_U32 }, |
91dbc6be LGL |
49 | }; |
50 | ||
51 | static 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 | ||
2b03bf73 LGL |
57 | if (tb[NFTA_NG_OFFSET]) |
58 | priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); | |
59 | ||
0d9932b2 LGL |
60 | priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); |
61 | if (priv->modulus == 0) | |
91dbc6be LGL |
62 | return -ERANGE; |
63 | ||
2b03bf73 LGL |
64 | if (priv->offset + priv->modulus - 1 < priv->offset) |
65 | return -EOVERFLOW; | |
66 | ||
91dbc6be | 67 | priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); |
0ecba4d9 | 68 | atomic_set(&priv->counter, priv->modulus - 1); |
91dbc6be LGL |
69 | |
70 | return nft_validate_register_store(ctx, priv->dreg, NULL, | |
71 | NFT_DATA_VALUE, sizeof(u32)); | |
72 | } | |
73 | ||
74 | static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, | |
2b03bf73 | 75 | u32 modulus, enum nft_ng_types type, u32 offset) |
91dbc6be LGL |
76 | { |
77 | if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) | |
78 | goto nla_put_failure; | |
0d9932b2 | 79 | if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus))) |
91dbc6be | 80 | goto nla_put_failure; |
7073b16f | 81 | if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) |
91dbc6be | 82 | goto nla_put_failure; |
2b03bf73 LGL |
83 | if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset))) |
84 | goto nla_put_failure; | |
91dbc6be LGL |
85 | |
86 | return 0; | |
87 | ||
88 | nla_put_failure: | |
89 | return -1; | |
90 | } | |
91 | ||
92 | static 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 | ||
2b03bf73 LGL |
96 | return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL, |
97 | priv->offset); | |
91dbc6be LGL |
98 | } |
99 | ||
100 | struct nft_ng_random { | |
101 | enum nft_registers dreg:8; | |
0d9932b2 | 102 | u32 modulus; |
2b03bf73 | 103 | u32 offset; |
91dbc6be LGL |
104 | }; |
105 | ||
106 | static 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); | |
2b03bf73 | 112 | u32 val; |
91dbc6be | 113 | |
2b03bf73 LGL |
114 | val = reciprocal_scale(prandom_u32_state(state), priv->modulus); |
115 | regs->data[priv->dreg] = val + priv->offset; | |
91dbc6be LGL |
116 | } |
117 | ||
118 | static 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 | ||
2b03bf73 LGL |
124 | if (tb[NFTA_NG_OFFSET]) |
125 | priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); | |
126 | ||
0d9932b2 LGL |
127 | priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); |
128 | if (priv->modulus == 0) | |
91dbc6be LGL |
129 | return -ERANGE; |
130 | ||
2b03bf73 LGL |
131 | if (priv->offset + priv->modulus - 1 < priv->offset) |
132 | return -EOVERFLOW; | |
133 | ||
91dbc6be LGL |
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 | ||
142 | static 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 | ||
2b03bf73 LGL |
146 | return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM, |
147 | priv->offset); | |
91dbc6be LGL |
148 | } |
149 | ||
150 | static struct nft_expr_type nft_ng_type; | |
151 | static 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 | ||
159 | static 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 | ||
167 | static const struct nft_expr_ops * | |
168 | nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[]) | |
169 | { | |
170 | u32 type; | |
171 | ||
0d9932b2 LGL |
172 | if (!tb[NFTA_NG_DREG] || |
173 | !tb[NFTA_NG_MODULUS] || | |
91dbc6be LGL |
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 | ||
189 | static 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 | ||
197 | static int __init nft_ng_module_init(void) | |
198 | { | |
199 | return nft_register_expr(&nft_ng_type); | |
200 | } | |
201 | ||
202 | static void __exit nft_ng_module_exit(void) | |
203 | { | |
204 | nft_unregister_expr(&nft_ng_type); | |
205 | } | |
206 | ||
207 | module_init(nft_ng_module_init); | |
208 | module_exit(nft_ng_module_exit); | |
209 | ||
210 | MODULE_LICENSE("GPL"); | |
211 | MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); | |
212 | MODULE_ALIAS_NFT_EXPR("numgen"); |