diff options
Diffstat (limited to 'net/netfilter/nft_hash.c')
| -rw-r--r-- | net/netfilter/nft_hash.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c new file mode 100644 index 000000000000..b82ff29b3f5f --- /dev/null +++ b/net/netfilter/nft_hash.c @@ -0,0 +1,136 @@ +/* + * 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 <net/netfilter/nf_tables.h> +#include <net/netfilter/nf_tables_core.h> +#include <linux/jhash.h> + +struct nft_hash { + enum nft_registers sreg:8; + enum nft_registers dreg:8; + u8 len; + u32 modulus; + u32 seed; +}; + +static void nft_hash_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct nft_hash *priv = nft_expr_priv(expr); + const void *data = ®s->data[priv->sreg]; + + regs->data[priv->dreg] = + reciprocal_scale(jhash(data, priv->len, priv->seed), + priv->modulus); +} + +const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { + [NFTA_HASH_SREG] = { .type = NLA_U32 }, + [NFTA_HASH_DREG] = { .type = NLA_U32 }, + [NFTA_HASH_LEN] = { .type = NLA_U32 }, + [NFTA_HASH_MODULUS] = { .type = NLA_U32 }, + [NFTA_HASH_SEED] = { .type = NLA_U32 }, +}; + +static int nft_hash_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_hash *priv = nft_expr_priv(expr); + u32 len; + + if (!tb[NFTA_HASH_SREG] || + !tb[NFTA_HASH_DREG] || + !tb[NFTA_HASH_LEN] || + !tb[NFTA_HASH_SEED] || + !tb[NFTA_HASH_MODULUS]) + return -EINVAL; + + priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]); + priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); + + len = ntohl(nla_get_be32(tb[NFTA_HASH_LEN])); + if (len == 0 || len > U8_MAX) + return -ERANGE; + + priv->len = len; + + priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); + if (priv->modulus <= 1) + return -ERANGE; + + priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED])); + + return nft_validate_register_load(priv->sreg, len) && + nft_validate_register_store(ctx, priv->dreg, NULL, + NFT_DATA_VALUE, sizeof(u32)); +} + +static int nft_hash_dump(struct sk_buff *skb, + const struct nft_expr *expr) +{ + const struct nft_hash *priv = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg)) + goto nla_put_failure; + if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) + goto nla_put_failure; + if (nft_dump_register(skb, NFTA_HASH_LEN, priv->len)) + goto nla_put_failure; + if (nft_dump_register(skb, NFTA_HASH_MODULUS, priv->modulus)) + goto nla_put_failure; + if (nft_dump_register(skb, NFTA_HASH_SEED, priv->seed)) + goto nla_put_failure; + + return 0; + +nla_put_failure: + return -1; +} + +static struct nft_expr_type nft_hash_type; +static const struct nft_expr_ops nft_hash_ops = { + .type = &nft_hash_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_hash)), + .eval = nft_hash_eval, + .init = nft_hash_init, + .dump = nft_hash_dump, +}; + +static struct nft_expr_type nft_hash_type __read_mostly = { + .name = "hash", + .ops = &nft_hash_ops, + .policy = nft_hash_policy, + .maxattr = NFTA_HASH_MAX, + .owner = THIS_MODULE, +}; + +static int __init nft_hash_module_init(void) +{ + return nft_register_expr(&nft_hash_type); +} + +static void __exit nft_hash_module_exit(void) +{ + nft_unregister_expr(&nft_hash_type); +} + +module_init(nft_hash_module_init); +module_exit(nft_hash_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); +MODULE_ALIAS_NFT_EXPR("hash"); |