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Commit 6c472602 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: nf_tables: add xfrm expression 



supports fetching saddr/daddr of tunnel mode states, request id and spi.
If direction is 'in', use inbound skb secpath, else dst->xfrm.

Joint work with Máté Eckl.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 2953d80f

include/uapi/linux/netfilter/nf_tables.h

+29 −0
Original line number Diff line number Diff line
@@ -1514,6 +1514,35 @@ enum nft_devices_attributes { 
};

#define NFTA_DEVICE_MAX		(__NFTA_DEVICE_MAX - 1)



/*

 * enum nft_xfrm_attributes - nf_tables xfrm expr netlink attributes

 *

 * @NFTA_XFRM_DREG: destination register (NLA_U32)

 * @NFTA_XFRM_KEY: enum nft_xfrm_keys (NLA_U32)

 * @NFTA_XFRM_DIR: direction (NLA_U8)

 * @NFTA_XFRM_SPNUM: index in secpath array (NLA_U32)

 */

enum nft_xfrm_attributes {

	NFTA_XFRM_UNSPEC,

	NFTA_XFRM_DREG,

	NFTA_XFRM_KEY,

	NFTA_XFRM_DIR,

	NFTA_XFRM_SPNUM,

	__NFTA_XFRM_MAX

};

#define NFTA_XFRM_MAX (__NFTA_XFRM_MAX - 1)



enum nft_xfrm_keys {

	NFT_XFRM_KEY_UNSPEC,

	NFT_XFRM_KEY_DADDR_IP4,

	NFT_XFRM_KEY_DADDR_IP6,

	NFT_XFRM_KEY_SADDR_IP4,

	NFT_XFRM_KEY_SADDR_IP6,

	NFT_XFRM_KEY_REQID,

	NFT_XFRM_KEY_SPI,

	__NFT_XFRM_KEY_MAX,

};

#define NFT_XFRM_KEY_MAX (__NFT_XFRM_KEY_MAX - 1)



/**

 * enum nft_trace_attributes - nf_tables trace netlink attributes

net/netfilter/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -625,6 +625,13 @@ config NFT_FIB_INET 
	  The lookup will be delegated to the IPv4 or IPv6 FIB depending

	  on the protocol of the packet.



config NFT_XFRM

	tristate "Netfilter nf_tables xfrm/IPSec security association matching"

	depends on XFRM

	help

	  This option adds an expression that you can use to extract properties

	  of a packets security association.



config NFT_SOCKET

	tristate "Netfilter nf_tables socket match support"

	depends on IPV6 || IPV6=n

net/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ obj-$(CONFIG_NFT_FIB_NETDEV) += nft_fib_netdev.o 
obj-$(CONFIG_NFT_SOCKET)	+= nft_socket.o

obj-$(CONFIG_NFT_OSF)		+= nft_osf.o

obj-$(CONFIG_NFT_TPROXY)	+= nft_tproxy.o

obj-$(CONFIG_NFT_XFRM)		+= nft_xfrm.o



# nf_tables netdev

obj-$(CONFIG_NFT_DUP_NETDEV)	+= nft_dup_netdev.o

net/netfilter/nft_xfrm.c

0 → 100644
+293 −0
Original line number Diff line number Diff line 
/*

 * 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.

 *

 * Generic part shared by ipv4 and ipv6 backends.

 */



#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_core.h>

#include <net/netfilter/nf_tables.h>

#include <linux/in.h>

#include <net/xfrm.h>



static const struct nla_policy nft_xfrm_policy[NFTA_XFRM_MAX + 1] = {

	[NFTA_XFRM_KEY]		= { .type = NLA_U32 },

	[NFTA_XFRM_DIR]		= { .type = NLA_U8 },

	[NFTA_XFRM_SPNUM]	= { .type = NLA_U32 },

	[NFTA_XFRM_DREG]	= { .type = NLA_U32 },

};



struct nft_xfrm {

	enum nft_xfrm_keys	key:8;

	enum nft_registers	dreg:8;

	u8			dir;

	u8			spnum;

};



static int nft_xfrm_get_init(const struct nft_ctx *ctx,

			     const struct nft_expr *expr,

			     const struct nlattr * const tb[])

{

	struct nft_xfrm *priv = nft_expr_priv(expr);

	unsigned int len = 0;

	u32 spnum = 0;

	u8 dir;



	if (!tb[NFTA_XFRM_KEY] || !tb[NFTA_XFRM_DIR] || !tb[NFTA_XFRM_DREG])

		return -EINVAL;



	switch (ctx->family) {

	case NFPROTO_IPV4:

	case NFPROTO_IPV6:

	case NFPROTO_INET:

		break;

	default:

		return -EOPNOTSUPP;

	}



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

	switch (priv->key) {

	case NFT_XFRM_KEY_REQID:

	case NFT_XFRM_KEY_SPI:

		len = sizeof(u32);

		break;

	case NFT_XFRM_KEY_DADDR_IP4:

	case NFT_XFRM_KEY_SADDR_IP4:

		len = sizeof(struct in_addr);

		break;

	case NFT_XFRM_KEY_DADDR_IP6:

	case NFT_XFRM_KEY_SADDR_IP6:

		len = sizeof(struct in6_addr);

		break;

	default:

		return -EINVAL;

	}



	dir = nla_get_u8(tb[NFTA_XFRM_DIR]);

	switch (dir) {

	case XFRM_POLICY_IN:

	case XFRM_POLICY_OUT:

		priv->dir = dir;

		break;

	default:

		return -EINVAL;

	}



	if (tb[NFTA_XFRM_SPNUM])

		spnum = ntohl(nla_get_be32(tb[NFTA_XFRM_SPNUM]));



	if (spnum >= XFRM_MAX_DEPTH)

		return -ERANGE;



	priv->spnum = spnum;



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

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

					   NFT_DATA_VALUE, len);

}



/* Return true if key asks for daddr/saddr and current

 * state does have a valid address (BEET, TUNNEL).

 */

static bool xfrm_state_addr_ok(enum nft_xfrm_keys k, u8 family, u8 mode)

{

	switch (k) {

	case NFT_XFRM_KEY_DADDR_IP4:

	case NFT_XFRM_KEY_SADDR_IP4:

		if (family == NFPROTO_IPV4)

			break;

		return false;

	case NFT_XFRM_KEY_DADDR_IP6:

	case NFT_XFRM_KEY_SADDR_IP6:

		if (family == NFPROTO_IPV6)

			break;

		return false;

	default:

		return true;

	}



	return mode == XFRM_MODE_BEET || mode == XFRM_MODE_TUNNEL;

}



static void nft_xfrm_state_get_key(const struct nft_xfrm *priv,

				   struct nft_regs *regs,

				   const struct xfrm_state *state,

				   u8 family)

{

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



	if (!xfrm_state_addr_ok(priv->key, family, state->props.mode)) {

		regs->verdict.code = NFT_BREAK;

		return;

	}



	switch (priv->key) {

	case NFT_XFRM_KEY_UNSPEC:

	case __NFT_XFRM_KEY_MAX:

		WARN_ON_ONCE(1);

		break;

	case NFT_XFRM_KEY_DADDR_IP4:

		*dest = state->id.daddr.a4;

		return;

	case NFT_XFRM_KEY_DADDR_IP6:

		memcpy(dest, &state->id.daddr.in6, sizeof(struct in6_addr));

		return;

	case NFT_XFRM_KEY_SADDR_IP4:

		*dest = state->props.saddr.a4;

		return;

	case NFT_XFRM_KEY_SADDR_IP6:

		memcpy(dest, &state->props.saddr.in6, sizeof(struct in6_addr));

		return;

	case NFT_XFRM_KEY_REQID:

		*dest = state->props.reqid;

		return;

	case NFT_XFRM_KEY_SPI:

		*dest = state->id.spi;

		return;

	}



	regs->verdict.code = NFT_BREAK;

}



static void nft_xfrm_get_eval_in(const struct nft_xfrm *priv,

				    struct nft_regs *regs,

				    const struct nft_pktinfo *pkt)

{

	const struct sec_path *sp = pkt->skb->sp;

	const struct xfrm_state *state;



	if (sp == NULL || sp->len <= priv->spnum) {

		regs->verdict.code = NFT_BREAK;

		return;

	}



	state = sp->xvec[priv->spnum];

	nft_xfrm_state_get_key(priv, regs, state, nft_pf(pkt));

}



static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv,

				  struct nft_regs *regs,

				  const struct nft_pktinfo *pkt)

{

	const struct dst_entry *dst = skb_dst(pkt->skb);

	int i;



	for (i = 0; dst && dst->xfrm;

	     dst = ((const struct xfrm_dst *)dst)->child, i++) {

		if (i < priv->spnum)

			continue;



		nft_xfrm_state_get_key(priv, regs, dst->xfrm, nft_pf(pkt));

		return;

	}



	regs->verdict.code = NFT_BREAK;

}



static void nft_xfrm_get_eval(const struct nft_expr *expr,

			      struct nft_regs *regs,

			      const struct nft_pktinfo *pkt)

{

	const struct nft_xfrm *priv = nft_expr_priv(expr);



	switch (priv->dir) {

	case XFRM_POLICY_IN:

		nft_xfrm_get_eval_in(priv, regs, pkt);

		break;

	case XFRM_POLICY_OUT:

		nft_xfrm_get_eval_out(priv, regs, pkt);

		break;

	default:

		WARN_ON_ONCE(1);

		regs->verdict.code = NFT_BREAK;

		break;

	}

}



static int nft_xfrm_get_dump(struct sk_buff *skb,

			     const struct nft_expr *expr)

{

	const struct nft_xfrm *priv = nft_expr_priv(expr);



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

		return -1;



	if (nla_put_be32(skb, NFTA_XFRM_KEY, htonl(priv->key)))

		return -1;

	if (nla_put_u8(skb, NFTA_XFRM_DIR, priv->dir))

		return -1;

	if (nla_put_be32(skb, NFTA_XFRM_SPNUM, htonl(priv->spnum)))

		return -1;



	return 0;

}



static int nft_xfrm_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,

			     const struct nft_data **data)

{

	const struct nft_xfrm *priv = nft_expr_priv(expr);

	unsigned int hooks;



	switch (priv->dir) {

	case XFRM_POLICY_IN:

		hooks = (1 << NF_INET_FORWARD) |

			(1 << NF_INET_LOCAL_IN) |

			(1 << NF_INET_PRE_ROUTING);

		break;

	case XFRM_POLICY_OUT:

		hooks = (1 << NF_INET_FORWARD) |

			(1 << NF_INET_LOCAL_OUT) |

			(1 << NF_INET_POST_ROUTING);

		break;

	default:

		WARN_ON_ONCE(1);

		return -EINVAL;

	}



	return nft_chain_validate_hooks(ctx->chain, hooks);

}





static struct nft_expr_type nft_xfrm_type;

static const struct nft_expr_ops nft_xfrm_get_ops = {

	.type		= &nft_xfrm_type,

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

	.eval		= nft_xfrm_get_eval,

	.init		= nft_xfrm_get_init,

	.dump		= nft_xfrm_get_dump,

	.validate	= nft_xfrm_validate,

};



static struct nft_expr_type nft_xfrm_type __read_mostly = {

	.name		= "xfrm",

	.ops		= &nft_xfrm_get_ops,

	.policy		= nft_xfrm_policy,

	.maxattr	= NFTA_XFRM_MAX,

	.owner		= THIS_MODULE,

};



static int __init nft_xfrm_module_init(void)

{

	return nft_register_expr(&nft_xfrm_type);

}



static void __exit nft_xfrm_module_exit(void)

{

	nft_unregister_expr(&nft_xfrm_type);

}



module_init(nft_xfrm_module_init);

module_exit(nft_xfrm_module_exit);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("nf_tables: xfrm/IPSec matching");

MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");

MODULE_AUTHOR("Máté Eckl <ecklm94@gmail.com>");

MODULE_ALIAS_NFT_EXPR("xfrm");