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net/netfilter/nft_numgen.c
5.56 KB
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/* * Copyright (c) 2016 Laura Garcia <nevola@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #include <linux/kernel.h> #include <linux/init.h> #include <linux/module.h> #include <linux/netlink.h> #include <linux/netfilter.h> #include <linux/netfilter/nf_tables.h> #include <linux/static_key.h> #include <net/netfilter/nf_tables.h> #include <net/netfilter/nf_tables_core.h> static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state); struct nft_ng_inc { enum nft_registers dreg:8; |
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u32 modulus; |
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atomic_t counter; |
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u32 offset; |
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}; |
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static u32 nft_ng_inc_gen(struct nft_ng_inc *priv) |
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{ |
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u32 nval, oval; do { oval = atomic_read(&priv->counter); |
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nval = (oval + 1 < priv->modulus) ? oval + 1 : 0; |
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} while (atomic_cmpxchg(&priv->counter, oval, nval) != oval); |
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return nval + priv->offset; } static void nft_ng_inc_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) { struct nft_ng_inc *priv = nft_expr_priv(expr); regs->data[priv->dreg] = nft_ng_inc_gen(priv); } |
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static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { [NFTA_NG_DREG] = { .type = NLA_U32 }, |
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[NFTA_NG_MODULUS] = { .type = NLA_U32 }, |
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[NFTA_NG_TYPE] = { .type = NLA_U32 }, |
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[NFTA_NG_OFFSET] = { .type = NLA_U32 }, |
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}; static int nft_ng_inc_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) { struct nft_ng_inc *priv = nft_expr_priv(expr); |
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if (tb[NFTA_NG_OFFSET]) priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); |
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priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); if (priv->modulus == 0) |
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return -ERANGE; |
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if (priv->offset + priv->modulus - 1 < priv->offset) return -EOVERFLOW; |
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priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); |
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atomic_set(&priv->counter, priv->modulus - 1); |
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return nft_validate_register_store(ctx, priv->dreg, NULL, NFT_DATA_VALUE, sizeof(u32)); } static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, |
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u32 modulus, enum nft_ng_types type, u32 offset) |
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{ if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) goto nla_put_failure; |
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if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus))) |
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goto nla_put_failure; |
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if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) |
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goto nla_put_failure; |
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if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset))) goto nla_put_failure; |
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return 0; nla_put_failure: return -1; } static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr) { const struct nft_ng_inc *priv = nft_expr_priv(expr); |
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return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL, priv->offset); |
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} struct nft_ng_random { enum nft_registers dreg:8; |
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u32 modulus; |
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u32 offset; |
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}; |
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static u32 nft_ng_random_gen(struct nft_ng_random *priv) { struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); return reciprocal_scale(prandom_u32_state(state), priv->modulus) + priv->offset; } |
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static void nft_ng_random_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) { struct nft_ng_random *priv = nft_expr_priv(expr); |
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|
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regs->data[priv->dreg] = nft_ng_random_gen(priv); } |
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static int nft_ng_random_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) { struct nft_ng_random *priv = nft_expr_priv(expr); |
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if (tb[NFTA_NG_OFFSET]) priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); |
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priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); if (priv->modulus == 0) |
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return -ERANGE; |
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if (priv->offset + priv->modulus - 1 < priv->offset) return -EOVERFLOW; |
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prandom_init_once(&nft_numgen_prandom_state); priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); return nft_validate_register_store(ctx, priv->dreg, NULL, NFT_DATA_VALUE, sizeof(u32)); } static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr) { const struct nft_ng_random *priv = nft_expr_priv(expr); |
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return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM, priv->offset); |
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} static struct nft_expr_type nft_ng_type; static const struct nft_expr_ops nft_ng_inc_ops = { .type = &nft_ng_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)), .eval = nft_ng_inc_eval, .init = nft_ng_inc_init, .dump = nft_ng_inc_dump, }; static const struct nft_expr_ops nft_ng_random_ops = { .type = &nft_ng_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)), .eval = nft_ng_random_eval, .init = nft_ng_random_init, .dump = nft_ng_random_dump, }; static const struct nft_expr_ops * nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[]) { u32 type; |
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if (!tb[NFTA_NG_DREG] || !tb[NFTA_NG_MODULUS] || |
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!tb[NFTA_NG_TYPE]) return ERR_PTR(-EINVAL); type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE])); switch (type) { case NFT_NG_INCREMENTAL: return &nft_ng_inc_ops; case NFT_NG_RANDOM: return &nft_ng_random_ops; } return ERR_PTR(-EINVAL); } static struct nft_expr_type nft_ng_type __read_mostly = { .name = "numgen", |
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.select_ops = nft_ng_select_ops, |
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.policy = nft_ng_policy, .maxattr = NFTA_NG_MAX, .owner = THIS_MODULE, }; static int __init nft_ng_module_init(void) { return nft_register_expr(&nft_ng_type); } static void __exit nft_ng_module_exit(void) { nft_unregister_expr(&nft_ng_type); } module_init(nft_ng_module_init); module_exit(nft_ng_module_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); MODULE_ALIAS_NFT_EXPR("numgen"); |