netfilter: nf_tables: add stateful object reference expression

This new expression allows us to refer to existing stateful objects from rules.

Pablo Neira Ayuso committed 9 years ago

Commit c97d22e1 parent 173705d4 files · +133 −0Browse files

Unified · Split

4 files

include/uapi/linux/netfilter/nf_tables.h +14 −0
net/netfilter/Kconfig +6 −0
net/netfilter/Makefile +1 −0
net/netfilter/nft_objref.c +112 −0

include/uapi/linux/netfilter/nf_tables.h+14−0

@@ -1137,6 +1137,20 @@ enum nft_fwd_attributes { · 1136 unmodified lines
1137	};	1137	};
1138	#define NFTA_FWD_MAX (__NFTA_FWD_MAX - 1)	1138	#define NFTA_FWD_MAX (__NFTA_FWD_MAX - 1)
1139		1139
		1140	/**
		1141	* enum nft_objref_attributes - nf_tables stateful object expression netlink attributes
		1142	*
		1143	* @NFTA_OBJREF_IMM_TYPE: object type for immediate reference (NLA_U32: nft_register)
		1144	* @NFTA_OBJREF_IMM_NAME: object name for immediate reference (NLA_STRING)
		1145	*/
		1146	enum nft_objref_attributes {
		1147	NFTA_OBJREF_UNSPEC,
		1148	NFTA_OBJREF_IMM_TYPE,
		1149	NFTA_OBJREF_IMM_NAME,
		1150	__NFTA_OBJREF_MAX
		1151	};
		1152	#define NFTA_OBJREF_MAX (__NFTA_OBJREF_MAX - 1)
		1153
1140	/**	1154	/**
1141	* enum nft_gen_attributes - nf_tables ruleset generation attributes	1155	* enum nft_gen_attributes - nf_tables ruleset generation attributes
1142	*	1156	*

net/netfilter/Kconfig+6−0

 	  This option adds the "nat" expression that you can use to perform
 	  typical Network Address Translation (NAT) packet transformations.
+config NFT_OBJREF
+	tristate "Netfilter nf_tables stateful object reference module"
+	help
+	  This option adds the "objref" expression that allows you to refer to
+	  stateful objects, such as counters and quotas.
 config NFT_QUEUE
 	depends on NETFILTER_NETLINK_QUEUE
 	tristate "Netfilter nf_tables queue module"

net/netfilter/Makefile+1−0

@@ -88,6 +88,7 @@ obj-$(CONFIG_NFT_NUMGEN) += nft_numgen.o · 87 unmodified lines
88	obj-$(CONFIG_NFT_CT) += nft_ct.o	88	obj-$(CONFIG_NFT_CT) += nft_ct.o
89	obj-$(CONFIG_NFT_LIMIT) += nft_limit.o	89	obj-$(CONFIG_NFT_LIMIT) += nft_limit.o
90	obj-$(CONFIG_NFT_NAT) += nft_nat.o	90	obj-$(CONFIG_NFT_NAT) += nft_nat.o
		91	obj-$(CONFIG_NFT_OBJREF) += nft_objref.o
91	obj-$(CONFIG_NFT_QUEUE) += nft_queue.o	92	obj-$(CONFIG_NFT_QUEUE) += nft_queue.o
92	obj-$(CONFIG_NFT_QUOTA) += nft_quota.o	93	obj-$(CONFIG_NFT_QUOTA) += nft_quota.o
93	obj-$(CONFIG_NFT_REJECT) += nft_reject.o	94	obj-$(CONFIG_NFT_REJECT) += nft_reject.o

net/netfilter/nft_objref.c+112−0

@@ -0,0 +1,112 @@
	1	/*
	2	* Copyright (c) 2012-2016 Pablo Neira Ayuso <pablo@netfilter.org>
	3	*
	4	* This program is free software; you can redistribute it and/or modify it
	5	* under the terms and conditions of the GNU General Public License,
	6	* version 2, as published by the Free Software Foundation.
	7	*/
	8
	9	#include <linux/init.h>
	10	#include <linux/module.h>
	11	#include <linux/skbuff.h>
	12	#include <linux/netlink.h>
	13	#include <linux/netfilter.h>
	14	#include <linux/netfilter/nf_tables.h>
	15	#include <net/netfilter/nf_tables.h>
	16
	17	#define nft_objref_priv(expr) ((struct nft_object *)nft_expr_priv(expr))
	18
	19	static void nft_objref_eval(const struct nft_expr *expr,
	20	struct nft_regs *regs,
	21	const struct nft_pktinfo *pkt)
	22	{
	23	struct nft_object *obj = nft_objref_priv(expr);
	24
	25	obj->type->eval(obj, regs, pkt);
	26	}
	27
	28	static int nft_objref_init(const struct nft_ctx *ctx,
	29	const struct nft_expr *expr,
	30	const struct nlattr * const tb[])
	31	{
	32	struct nft_object *obj = nft_objref_priv(expr);
	33	u8 genmask = nft_genmask_next(ctx->net);
	34	u32 objtype;
	35
	36	if (!tb[NFTA_OBJREF_IMM_NAME] \|\|
	37	!tb[NFTA_OBJREF_IMM_TYPE])
	38	return -EINVAL;
	39
	40	objtype = ntohl(nla_get_be32(tb[NFTA_OBJREF_IMM_TYPE]));
	41	obj = nf_tables_obj_lookup(ctx->table, tb[NFTA_OBJREF_IMM_NAME], objtype,
	42	genmask);
	43	if (IS_ERR(obj))
	44	return -ENOENT;
	45
	46	nft_objref_priv(expr) = obj;
	47	obj->use++;
	48
	49	return 0;
	50	}
	51
	52	static int nft_objref_dump(struct sk_buff skb, const struct nft_expr expr)
	53	{
	54	const struct nft_object *obj = nft_objref_priv(expr);
	55
	56	if (nla_put_string(skb, NFTA_OBJREF_IMM_NAME, obj->name) \|\|
	57	nla_put_be32(skb, NFTA_OBJREF_IMM_TYPE, htonl(obj->type->type)))
	58	goto nla_put_failure;
	59
	60	return 0;
	61
	62	nla_put_failure:
	63	return -1;
	64	}
	65
	66	static void nft_objref_destroy(const struct nft_ctx *ctx,
	67	const struct nft_expr *expr)
	68	{
	69	struct nft_object *obj = nft_objref_priv(expr);
	70
	71	obj->use--;
	72	}
	73
	74	static struct nft_expr_type nft_objref_type;
	75	static const struct nft_expr_ops nft_objref_ops = {
	76	.type = &nft_objref_type,
	77	.size = NFT_EXPR_SIZE(sizeof(struct nft_object *)),
	78	.eval = nft_objref_eval,
	79	.init = nft_objref_init,
	80	.destroy = nft_objref_destroy,
	81	.dump = nft_objref_dump,
	82	};
	83
	84	static const struct nla_policy nft_objref_policy[NFTA_OBJREF_MAX + 1] = {
	85	[NFTA_OBJREF_IMM_NAME] = { .type = NLA_STRING },
	86	[NFTA_OBJREF_IMM_TYPE] = { .type = NLA_U32 },
	87	};
	88
	89	static struct nft_expr_type nft_objref_type __read_mostly = {
	90	.name = "objref",
	91	.ops = &nft_objref_ops,
	92	.policy = nft_objref_policy,
	93	.maxattr = NFTA_OBJREF_MAX,
	94	.owner = THIS_MODULE,
	95	};
	96
	97	static int __init nft_objref_module_init(void)
	98	{
	99	return nft_register_expr(&nft_objref_type);
	100	}
	101
	102	static void __exit nft_objref_module_exit(void)
	103	{
	104	nft_unregister_expr(&nft_objref_type);
	105	}
	106
	107	module_init(nft_objref_module_init);
	108	module_exit(nft_objref_module_exit);
	109
	110	MODULE_LICENSE("GPL");
	111	MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
	112	MODULE_ALIAS_NFT_EXPR("objref");