[mirror_ubuntu-bionic-kernel.git] / net / netfilter / nft_hash.c

/*
 * 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;
	u32			offset;
};

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 = &regs->data[priv->sreg];
	u32 h;

	h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
	regs->data[priv->dreg] = h + priv->offset;
}

static 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 },
	[NFTA_HASH_OFFSET]	= { .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;

	if (tb[NFTA_HASH_OFFSET])
		priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));

	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;

	if (priv->offset + priv->modulus - 1 < priv->offset)
		return -EOVERFLOW;

	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 (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
		goto nla_put_failure;
	if (priv->offset != 0)
		if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
			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");
Commit	Line	Data
cb1b69b0 LGL	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 <net/netfilter/nf_tables.h>
	17	#include <net/netfilter/nf_tables_core.h>
	18	#include <linux/jhash.h>
	19
	20	struct nft_hash {
	21	enum nft_registers sreg:8;
	22	enum nft_registers dreg:8;
	23	u8 len;
	24	u32 modulus;
	25	u32 seed;
70ca767e	26	u32 offset;
cb1b69b0 LGL	27	};
	28
	29	static void nft_hash_eval(const struct nft_expr *expr,
	30	struct nft_regs *regs,
	31	const struct nft_pktinfo *pkt)
	32	{
	33	struct nft_hash *priv = nft_expr_priv(expr);
	34	const void *data = &regs->data[priv->sreg];
70ca767e	35	u32 h;
cb1b69b0	36
70ca767e LGL	37	h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
70ca767e LGL	38	regs->data[priv->dreg] = h + priv->offset;
cb1b69b0 LGL	39	}
cb1b69b0 LGL	40
a5e57336	41	static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
cb1b69b0 LGL	42	[NFTA_HASH_SREG] = { .type = NLA_U32 },
	43	[NFTA_HASH_DREG] = { .type = NLA_U32 },
	44	[NFTA_HASH_LEN] = { .type = NLA_U32 },
	45	[NFTA_HASH_MODULUS] = { .type = NLA_U32 },
	46	[NFTA_HASH_SEED] = { .type = NLA_U32 },
5751e175	47	[NFTA_HASH_OFFSET] = { .type = NLA_U32 },
cb1b69b0 LGL	48	};
	49
	50	static int nft_hash_init(const struct nft_ctx *ctx,
	51	const struct nft_expr *expr,
	52	const struct nlattr * const tb[])
	53	{
	54	struct nft_hash *priv = nft_expr_priv(expr);
	55	u32 len;
	56
	57	if (!tb[NFTA_HASH_SREG] \|\|
	58	!tb[NFTA_HASH_DREG] \|\|
	59	!tb[NFTA_HASH_LEN] \|\|
	60	!tb[NFTA_HASH_SEED] \|\|
	61	!tb[NFTA_HASH_MODULUS])
	62	return -EINVAL;
	63
70ca767e LGL	64	if (tb[NFTA_HASH_OFFSET])
	65	priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
	66
cb1b69b0 LGL	67	priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
	68	priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
	69
	70	len = ntohl(nla_get_be32(tb[NFTA_HASH_LEN]));
	71	if (len == 0 \|\| len > U8_MAX)
	72	return -ERANGE;
	73
	74	priv->len = len;
	75
	76	priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
	77	if (priv->modulus <= 1)
	78	return -ERANGE;
	79
14e2dee0	80	if (priv->offset + priv->modulus - 1 < priv->offset)
70ca767e LGL	81	return -EOVERFLOW;
70ca767e LGL	82
cb1b69b0 LGL	83	priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
	84
	85	return nft_validate_register_load(priv->sreg, len) &&
	86	nft_validate_register_store(ctx, priv->dreg, NULL,
	87	NFT_DATA_VALUE, sizeof(u32));
	88	}
	89
	90	static int nft_hash_dump(struct sk_buff *skb,
	91	const struct nft_expr *expr)
	92	{
	93	const struct nft_hash *priv = nft_expr_priv(expr);
	94
	95	if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
	96	goto nla_put_failure;
	97	if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
	98	goto nla_put_failure;
7073b16f	99	if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
cb1b69b0	100	goto nla_put_failure;
7073b16f	101	if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
cb1b69b0	102	goto nla_put_failure;
7073b16f	103	if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
cb1b69b0	104	goto nla_put_failure;
70ca767e LGL	105	if (priv->offset != 0)
	106	if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
	107	goto nla_put_failure;
cb1b69b0 LGL	108	return 0;
	109
	110	nla_put_failure:
	111	return -1;
	112	}
	113
	114	static struct nft_expr_type nft_hash_type;
	115	static const struct nft_expr_ops nft_hash_ops = {
	116	.type = &nft_hash_type,
	117	.size = NFT_EXPR_SIZE(sizeof(struct nft_hash)),
	118	.eval = nft_hash_eval,
	119	.init = nft_hash_init,
	120	.dump = nft_hash_dump,
	121	};
	122
	123	static struct nft_expr_type nft_hash_type __read_mostly = {
	124	.name = "hash",
	125	.ops = &nft_hash_ops,
	126	.policy = nft_hash_policy,
	127	.maxattr = NFTA_HASH_MAX,
	128	.owner = THIS_MODULE,
	129	};
	130
	131	static int __init nft_hash_module_init(void)
	132	{
	133	return nft_register_expr(&nft_hash_type);
	134	}
	135
	136	static void __exit nft_hash_module_exit(void)
	137	{
	138	nft_unregister_expr(&nft_hash_type);
	139	}
	140
	141	module_init(nft_hash_module_init);
	142	module_exit(nft_hash_module_exit);
	143
	144	MODULE_LICENSE("GPL");
	145	MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
	146	MODULE_ALIAS_NFT_EXPR("hash");