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Commit 554ced0a authored by Máté Eckl's avatar Máté Eckl Committed by Pablo Neira Ayuso
Browse files

netfilter: nf_tables: add support for native socket matching 



Now it can only match the transparent flag of an ip/ipv6 socket.

Signed-off-by: default avatarMáté Eckl <ecklm94@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 7849958b

include/uapi/linux/netfilter/nf_tables.h

+25 −0
Original line number Diff line number Diff line
@@ -904,6 +904,31 @@ enum nft_rt_attributes { 
};

#define NFTA_RT_MAX		(__NFTA_RT_MAX - 1)



/**

 * enum nft_socket_attributes - nf_tables socket expression netlink attributes

 *

 * @NFTA_SOCKET_KEY: socket key to match

 * @NFTA_SOCKET_DREG: destination register

 */

enum nft_socket_attributes {

	NFTA_SOCKET_UNSPEC,

	NFTA_SOCKET_KEY,

	NFTA_SOCKET_DREG,

	__NFTA_SOCKET_MAX

};

#define NFTA_SOCKET_MAX		(__NFTA_SOCKET_MAX - 1)



/*

 * enum nft_socket_keys - nf_tables socket expression keys

 *

 * @NFT_SOCKET_TRANSPARENT: Value of the IP(V6)_TRANSPARENT socket option_

 */

enum nft_socket_keys {

	NFT_SOCKET_TRANSPARENT,

	__NFT_SOCKET_MAX

};

#define NFT_SOCKET_MAX	(__NFT_SOCKET_MAX - 1)



/**

 * enum nft_ct_keys - nf_tables ct expression keys

 *

net/netfilter/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -613,6 +613,15 @@ config NFT_FIB_INET 
	  The lookup will be delegated to the IPv4 or IPv6 FIB depending

	  on the protocol of the packet.



config NFT_SOCKET

	tristate "Netfilter nf_tables socket match support"

	depends on IPV6 || IPV6=n

	select NF_SOCKET_IPV4

	select NF_SOCKET_IPV6 if IPV6

	help

	  This option allows matching for the presence or absence of a

	  corresponding socket and its attributes.



if NF_TABLES_NETDEV



config NF_DUP_NETDEV

net/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -102,6 +102,7 @@ obj-$(CONFIG_NFT_FIB) += nft_fib.o 
obj-$(CONFIG_NFT_FIB_INET)	+= nft_fib_inet.o

obj-$(CONFIG_NFT_FIB_NETDEV)	+= nft_fib_netdev.o

obj-$(CONFIG_NF_OSF)		+= nf_osf.o

obj-$(CONFIG_NFT_SOCKET)	+= nft_socket.o



# nf_tables netdev

obj-$(CONFIG_NFT_DUP_NETDEV)	+= nft_dup_netdev.o

net/netfilter/nft_socket.c

0 → 100644
+143 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/module.h>

#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables_core.h>

#include <net/netfilter/nf_socket.h>

#include <net/inet_sock.h>



struct nft_socket {

	enum nft_socket_keys		key:8;

	union {

		enum nft_registers	dreg:8;

	};

};



static void nft_socket_eval(const struct nft_expr *expr,

			    struct nft_regs *regs,

			    const struct nft_pktinfo *pkt)

{

	const struct nft_socket *priv = nft_expr_priv(expr);

	struct sk_buff *skb = pkt->skb;

	struct sock *sk = skb->sk;

	u32 *dest = &regs->data[priv->dreg];



	if (!sk)

		switch(nft_pf(pkt)) {

		case NFPROTO_IPV4:

			sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt));

			break;

#if IS_ENABLED(CONFIG_NF_SOCKET_IPV6)

		case NFPROTO_IPV6:

			sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt));

			break;

#endif

		default:

			WARN_ON_ONCE(1);

			regs->verdict.code = NFT_BREAK;

			return;

		}



	if(!sk) {

		nft_reg_store8(dest, 0);

		return;

	}



	/* So that subsequent socket matching not to require other lookups. */

	skb->sk = sk;



	switch(priv->key) {

	case NFT_SOCKET_TRANSPARENT:

		nft_reg_store8(dest, nf_sk_is_transparent(sk));

		break;

	default:

		WARN_ON(1);

		regs->verdict.code = NFT_BREAK;

	}

}



static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {

	[NFTA_SOCKET_KEY]		= { .type = NLA_U32 },

	[NFTA_SOCKET_DREG]		= { .type = NLA_U32 },

};



static int nft_socket_init(const struct nft_ctx *ctx,

			   const struct nft_expr *expr,

			   const struct nlattr * const tb[])

{

	struct nft_socket *priv = nft_expr_priv(expr);

	unsigned int len;



	if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])

		return -EINVAL;



	switch(ctx->family) {

	case NFPROTO_IPV4:

#if IS_ENABLED(CONFIG_NF_SOCKET_IPV6)

	case NFPROTO_IPV6:

#endif

	case NFPROTO_INET:

		break;

	default:

		return -EOPNOTSUPP;

	}



	priv->key = ntohl(nla_get_u32(tb[NFTA_SOCKET_KEY]));

	switch(priv->key) {

	case NFT_SOCKET_TRANSPARENT:

		len = sizeof(u8);

		break;

	default:

		return -EOPNOTSUPP;

	}



	priv->dreg = nft_parse_register(tb[NFTA_SOCKET_DREG]);

	return nft_validate_register_store(ctx, priv->dreg, NULL,

					   NFT_DATA_VALUE, len);

}



static int nft_socket_dump(struct sk_buff *skb,

			   const struct nft_expr *expr)

{

	const struct nft_socket *priv = nft_expr_priv(expr);



	if (nla_put_u32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))

		return -1;

	if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))

		return -1;

	return 0;

}



static struct nft_expr_type nft_socket_type;

static const struct nft_expr_ops nft_socket_ops = {

	.type		= &nft_socket_type,

	.size		= NFT_EXPR_SIZE(sizeof(struct nft_socket)),

	.eval		= nft_socket_eval,

	.init		= nft_socket_init,

	.dump		= nft_socket_dump,

};



static struct nft_expr_type nft_socket_type __read_mostly = {

	.name		= "socket",

	.ops		= &nft_socket_ops,

	.policy		= nft_socket_policy,

	.maxattr	= NFTA_SOCKET_MAX,

	.owner		= THIS_MODULE,

};



static int __init nft_socket_module_init(void)

{

	return nft_register_expr(&nft_socket_type);

}



static void __exit nft_socket_module_exit(void)

{

	nft_unregister_expr(&nft_socket_type);

}



module_init(nft_socket_module_init);

module_exit(nft_socket_module_exit);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Máté Eckl");

MODULE_DESCRIPTION("nf_tables socket match module");