netfilter: nf_tables: add hash expression
Subsystems (2)
PATCH v3 1/1 netfilter: nf_tables: add hash expression
This patch adds a new hash expression, this provides jhash support but this can be extended to support for other hash functions.
The modulus and seed already comes embedded into this new expression.
Use case example:
meta mark set hash ip saddr mod 10
Signed-off-by Laura Garcia Liebana <[email protected]>
---
Changes in V3:
- Add null checks in init()
- Include registers load validation
include/uapi/linux/netfilter/nf_tables.h | 20 +++++ net/netfilter/Kconfig | 6 ++ net/netfilter/Makefile | 1 + net/netfilter/nft_hash.c | 141 +++++++++++++++++++++++++++++++ 4 files changed, 168 insertions(+) create mode 100644 net/netfilter/nft_hash.c
include/uapi/linux/netfilter/nf_tables.h +20 -0
@@ -724,6 +724,26 @@ enum nft_meta_keys { };/** +* enum nft_hash_attributes - nf_tables hash expression netlink attributes +* +* @NFTA_HASH_SREG: source register (NLA_U32) +* @NFTA_HASH_DREG: destination register (NLA_U32) +* @NFTA_HASH_LEN: source data length (NLA_U32) +* @NFTA_HASH_MODULUS: modulus value (NLA_U32) +* @NFTA_HASH_SEED: seed value (NLA_U32) +*/ +enum nft_hash_attributes { +NFTA_HASH_UNSPEC , +NFTA_HASH_SREG , +NFTA_HASH_DREG , +NFTA_HASH_LEN , +NFTA_HASH_MODULUS , +NFTA_HASH_SEED , + __NFTA_HASH_MAX, +}; +#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1) + +/** * enum nft_meta_attributes - nf_tables meta expression netlink attributes * * @NFTA_META_DREG: destination register (NLA_U32)
net/netfilter/Kconfig +6 -0
@@ -569,6 +569,12 @@ config NFT_COMPAT x_tables match/target extensions over the nf_tables framework. +config NFT_HASH + tristate "Netfilter nf_tables hash module" + help + This option adds the "hash" expression that you can use to perform + a hash operation on registers. + if NF_TABLES_NETDEV config NF_DUP_NETDEV
net/netfilter/Makefile +1 -0
@@ -93,6 +93,7 @@ obj-$(CONFIG_NFT_COUNTER) += nft_counter.o obj-$(CONFIG_NFT_LOG) += nft_log.o obj-$(CONFIG_NFT_MASQ) += nft_masq.o obj-$(CONFIG_NFT_REDIR) += nft_redir.o +obj-$(CONFIG_NFT_HASH) += nft_hash.o # nf_tables netdev obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o
net/netfilter/nft_hash.c new file +141 -0
141 lines not on this page · raw message
Signature · 1 line
2.8.1
Pablo Neira Ayuso
maintainerQuoted 64 lines · Laura Garcia Liebana
net/netfilter/nft_hash.c new file +58
-0@@ -0,0 +1,141 @@ +/* +* Copyright (c) 2016 Laura Garcia <[email protected]> +* +* 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]; +u32 h; + + h =reciprocal_scale (jhash (data, priv->len, priv->seed), priv->modulus); + + regs->data[priv->dreg] = h; +} + +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; +u32 seed =0 ; + + if (!tb[NFTA_HASH_SREG] || + !tb[NFTA_HASH_DREG] ||
net/netfilter/nft_hash.c line 68
Quoted 10 lines
net/netfilter/nft_hash.c new file +10
-0+ !tb[NFTA_HASH_LEN ] || + !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 -EINVAL ;
Use return -ERANGE here so we get in sync with lib/nlattr.c policy validation, that returns this error for values out of range.
net/netfilter/nft_hash.c line 74
Quoted 6 lines
net/netfilter/nft_hash.c new file +6
-0+ + priv->len = len; + + priv->modulus =ntohl (nla_get_be32 (tb[NFTA_HASH_MODULUS ])); +if (priv->modulus <=1 ) +return -EINVAL ;
Use return -ERANGE instead.
net/netfilter/nft_hash.c line 76
Quoted 2 lines
net/netfilter/nft_hash.c new file +2
-0+ +if (tb[NFTA_HASH_LEN ])
typo here, this should be NFTA_HASH_SEED.
net/netfilter/nft_hash.c line 77
Quoted 1 line
net/netfilter/nft_hash.c new file +1
-0+ seed =ntohl (nla_get_be32 (tb[NFTA_HASH_SEED ]));
I don't see any benefit from making this optional, worst case userspace can pass zero to us, right?
net/netfilter/nft_hash.c line 81
Quoted 4 lines
net/netfilter/nft_hash.c new file +4
-0+ + priv->seed = seed; + + return nft_validate_register_store(ctx, priv->sreg, NULL,
This should be a validate_register_load instead.
net/netfilter/nft_hash.c line 83
Quoted 2 lines
net/netfilter/nft_hash.c new file +2
-0+ NFT_DATA_VALUE, len) && + nft_validate_register_store(ctx, priv->dreg, NULL,
^
Comestic: If you do this, you have to get this aligned with the line above tabs and then spaces, ie.
return nft_validate_register_store(ctx, priv->sreg, NULL, NFT_DATA_VALUE, len) && nft_validate_register_store(ctx, priv->dreg, NULL,
Anyway, the code above needs a respin.
net/netfilter/nft_hash.c line 85
Quoted 2 lines
net/netfilter/nft_hash.c new file +2
-0+ NFT_DATA_VALUE, sizeof(u32)); +}
Thanks.