diff options
Diffstat (limited to 'net/netfilter/nft_numgen.c')
| -rw-r--r-- | net/netfilter/nft_numgen.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/net/netfilter/nft_numgen.c b/net/netfilter/nft_numgen.c new file mode 100644 index 000000000000..55bc5ab78d4a --- /dev/null +++ b/net/netfilter/nft_numgen.c @@ -0,0 +1,212 @@ +/* + * 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; + u32 modulus; + atomic_t counter; + u32 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); + u32 nval, oval; + + do { + oval = atomic_read(&priv->counter); + nval = (oval + 1 < priv->modulus) ? oval + 1 : 0; + } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval); + + regs->data[priv->dreg] = nval + priv->offset; +} + +static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { + [NFTA_NG_DREG] = { .type = NLA_U32 }, + [NFTA_NG_MODULUS] = { .type = NLA_U32 }, + [NFTA_NG_TYPE] = { .type = NLA_U32 }, + [NFTA_NG_OFFSET] = { .type = NLA_U32 }, +}; + +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); + + if (tb[NFTA_NG_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); + + priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); + if (priv->modulus == 0) + return -ERANGE; + + if (priv->offset + priv->modulus - 1 < priv->offset) + return -EOVERFLOW; + + priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); + atomic_set(&priv->counter, 0); + + 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, + u32 modulus, enum nft_ng_types type, u32 offset) +{ + if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset))) + goto nla_put_failure; + + 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); + + return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL, + priv->offset); +} + +struct nft_ng_random { + enum nft_registers dreg:8; + u32 modulus; + u32 offset; +}; + +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); + struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); + u32 val; + + val = reciprocal_scale(prandom_u32_state(state), priv->modulus); + regs->data[priv->dreg] = val + priv->offset; +} + +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); + + if (tb[NFTA_NG_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); + + priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); + if (priv->modulus == 0) + return -ERANGE; + + if (priv->offset + priv->modulus - 1 < priv->offset) + return -EOVERFLOW; + + 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); + + return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM, + priv->offset); +} + +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; + + if (!tb[NFTA_NG_DREG] || + !tb[NFTA_NG_MODULUS] || + !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", + .select_ops = &nft_ng_select_ops, + .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"); |