Laura Garcia Liebana | 91dbc6b | 2016-08-18 12:13:13 +0200 | [diff] [blame] | 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; |
| 24 | u32 until; |
| 25 | atomic_t counter; |
| 26 | }; |
| 27 | |
| 28 | static void nft_ng_inc_eval(const struct nft_expr *expr, |
| 29 | struct nft_regs *regs, |
| 30 | const struct nft_pktinfo *pkt) |
| 31 | { |
| 32 | struct nft_ng_inc *priv = nft_expr_priv(expr); |
| 33 | u32 nval, oval; |
| 34 | |
| 35 | do { |
| 36 | oval = atomic_read(&priv->counter); |
| 37 | nval = (oval + 1 < priv->until) ? oval + 1 : 0; |
| 38 | } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval); |
| 39 | |
| 40 | memcpy(®s->data[priv->dreg], &priv->counter, sizeof(u32)); |
| 41 | } |
| 42 | |
| 43 | static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { |
| 44 | [NFTA_NG_DREG] = { .type = NLA_U32 }, |
| 45 | [NFTA_NG_UNTIL] = { .type = NLA_U32 }, |
| 46 | [NFTA_NG_TYPE] = { .type = NLA_U32 }, |
| 47 | }; |
| 48 | |
| 49 | static int nft_ng_inc_init(const struct nft_ctx *ctx, |
| 50 | const struct nft_expr *expr, |
| 51 | const struct nlattr * const tb[]) |
| 52 | { |
| 53 | struct nft_ng_inc *priv = nft_expr_priv(expr); |
| 54 | |
| 55 | priv->until = ntohl(nla_get_be32(tb[NFTA_NG_UNTIL])); |
| 56 | if (priv->until == 0) |
| 57 | return -ERANGE; |
| 58 | |
| 59 | priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); |
| 60 | atomic_set(&priv->counter, 0); |
| 61 | |
| 62 | return nft_validate_register_store(ctx, priv->dreg, NULL, |
| 63 | NFT_DATA_VALUE, sizeof(u32)); |
| 64 | } |
| 65 | |
| 66 | static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, |
| 67 | u32 until, enum nft_ng_types type) |
| 68 | { |
| 69 | if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) |
| 70 | goto nla_put_failure; |
Pablo Neira Ayuso | 7073b16 | 2016-08-26 13:42:17 +0200 | [diff] [blame^] | 71 | if (nla_put_be32(skb, NFTA_NG_UNTIL, htonl(until))) |
Laura Garcia Liebana | 91dbc6b | 2016-08-18 12:13:13 +0200 | [diff] [blame] | 72 | goto nla_put_failure; |
Pablo Neira Ayuso | 7073b16 | 2016-08-26 13:42:17 +0200 | [diff] [blame^] | 73 | if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) |
Laura Garcia Liebana | 91dbc6b | 2016-08-18 12:13:13 +0200 | [diff] [blame] | 74 | goto nla_put_failure; |
| 75 | |
| 76 | return 0; |
| 77 | |
| 78 | nla_put_failure: |
| 79 | return -1; |
| 80 | } |
| 81 | |
| 82 | static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr) |
| 83 | { |
| 84 | const struct nft_ng_inc *priv = nft_expr_priv(expr); |
| 85 | |
| 86 | return nft_ng_dump(skb, priv->dreg, priv->until, NFT_NG_INCREMENTAL); |
| 87 | } |
| 88 | |
| 89 | struct nft_ng_random { |
| 90 | enum nft_registers dreg:8; |
| 91 | u32 until; |
| 92 | }; |
| 93 | |
| 94 | static void nft_ng_random_eval(const struct nft_expr *expr, |
| 95 | struct nft_regs *regs, |
| 96 | const struct nft_pktinfo *pkt) |
| 97 | { |
| 98 | struct nft_ng_random *priv = nft_expr_priv(expr); |
| 99 | struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); |
| 100 | |
| 101 | regs->data[priv->dreg] = reciprocal_scale(prandom_u32_state(state), |
| 102 | priv->until); |
| 103 | } |
| 104 | |
| 105 | static int nft_ng_random_init(const struct nft_ctx *ctx, |
| 106 | const struct nft_expr *expr, |
| 107 | const struct nlattr * const tb[]) |
| 108 | { |
| 109 | struct nft_ng_random *priv = nft_expr_priv(expr); |
| 110 | |
| 111 | priv->until = ntohl(nla_get_be32(tb[NFTA_NG_UNTIL])); |
| 112 | if (priv->until == 0) |
| 113 | return -ERANGE; |
| 114 | |
| 115 | prandom_init_once(&nft_numgen_prandom_state); |
| 116 | |
| 117 | priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); |
| 118 | |
| 119 | return nft_validate_register_store(ctx, priv->dreg, NULL, |
| 120 | NFT_DATA_VALUE, sizeof(u32)); |
| 121 | } |
| 122 | |
| 123 | static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr) |
| 124 | { |
| 125 | const struct nft_ng_random *priv = nft_expr_priv(expr); |
| 126 | |
| 127 | return nft_ng_dump(skb, priv->dreg, priv->until, NFT_NG_RANDOM); |
| 128 | } |
| 129 | |
| 130 | static struct nft_expr_type nft_ng_type; |
| 131 | static const struct nft_expr_ops nft_ng_inc_ops = { |
| 132 | .type = &nft_ng_type, |
| 133 | .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)), |
| 134 | .eval = nft_ng_inc_eval, |
| 135 | .init = nft_ng_inc_init, |
| 136 | .dump = nft_ng_inc_dump, |
| 137 | }; |
| 138 | |
| 139 | static const struct nft_expr_ops nft_ng_random_ops = { |
| 140 | .type = &nft_ng_type, |
| 141 | .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)), |
| 142 | .eval = nft_ng_random_eval, |
| 143 | .init = nft_ng_random_init, |
| 144 | .dump = nft_ng_random_dump, |
| 145 | }; |
| 146 | |
| 147 | static const struct nft_expr_ops * |
| 148 | nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[]) |
| 149 | { |
| 150 | u32 type; |
| 151 | |
| 152 | if (!tb[NFTA_NG_DREG] || |
| 153 | !tb[NFTA_NG_UNTIL] || |
| 154 | !tb[NFTA_NG_TYPE]) |
| 155 | return ERR_PTR(-EINVAL); |
| 156 | |
| 157 | type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE])); |
| 158 | |
| 159 | switch (type) { |
| 160 | case NFT_NG_INCREMENTAL: |
| 161 | return &nft_ng_inc_ops; |
| 162 | case NFT_NG_RANDOM: |
| 163 | return &nft_ng_random_ops; |
| 164 | } |
| 165 | |
| 166 | return ERR_PTR(-EINVAL); |
| 167 | } |
| 168 | |
| 169 | static struct nft_expr_type nft_ng_type __read_mostly = { |
| 170 | .name = "numgen", |
| 171 | .select_ops = &nft_ng_select_ops, |
| 172 | .policy = nft_ng_policy, |
| 173 | .maxattr = NFTA_NG_MAX, |
| 174 | .owner = THIS_MODULE, |
| 175 | }; |
| 176 | |
| 177 | static int __init nft_ng_module_init(void) |
| 178 | { |
| 179 | return nft_register_expr(&nft_ng_type); |
| 180 | } |
| 181 | |
| 182 | static void __exit nft_ng_module_exit(void) |
| 183 | { |
| 184 | nft_unregister_expr(&nft_ng_type); |
| 185 | } |
| 186 | |
| 187 | module_init(nft_ng_module_init); |
| 188 | module_exit(nft_ng_module_exit); |
| 189 | |
| 190 | MODULE_LICENSE("GPL"); |
| 191 | MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); |
| 192 | MODULE_ALIAS_NFT_EXPR("numgen"); |