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Commit e7cf05db authored by Harout Hedeshian's avatar Harout Hedeshian
Browse files

netfilter: xt_socket: add XT_SOCKET_RESTORESKMARK flag 



xt_socket is useful for matching sockets with IP_TRANSPARENT and
taking some action on the matching packets. However, it lacks the
ability to match only a small subset of transparent sockets.

Suppose there are 2 applications, each with its own set of transparent
sockets. The first application wants all matching packets dropped,
while the second application wants them forwarded somewhere else.

Add the ability to retore the skb->mark from the sk_mark. The mark
is only restored if a matching socket is found and the transparent /
nowildcard conditions are satisfied.

Now the 2 hypothetical applications can differentiate their sockets
based on a mark value set with SO_MARK.

iptables -t mangle -I PREROUTING -m socket --transparent \
                                           --restore-skmark -j action
iptables -t mangle -A action -m mark --mark 10 -j action2
iptables -t mangle -A action -m mark --mark 11 -j action3

Change-Id: Ica30d9303ac6bb265fce4ef095a952508b4a1f0c
Signed-off-by: default avatarHarout Hedeshian <harouth@codeaurora.org>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Git-commit: 01555e74bde51444c6898ef1800fb2bc697d479e
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
parent f34a3ba0

include/uapi/linux/netfilter/xt_socket.h

+8 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
enum {

	XT_SOCKET_TRANSPARENT = 1 << 0,

	XT_SOCKET_NOWILDCARD = 1 << 1,

	XT_SOCKET_RESTORESKMARK = 1 << 2,

};



struct xt_socket_mtinfo1 {
@@ -18,6 +19,13 @@ struct xt_socket_mtinfo2 { 
};

#define XT_SOCKET_FLAGS_V2 (XT_SOCKET_TRANSPARENT | XT_SOCKET_NOWILDCARD)



struct xt_socket_mtinfo3 {

	__u8 flags;

};

#define XT_SOCKET_FLAGS_V3 (XT_SOCKET_TRANSPARENT \

			   | XT_SOCKET_NOWILDCARD \

			   | XT_SOCKET_RESTORESKMARK)



struct sock *xt_socket_get4_sk(const struct sk_buff *skb,

			       struct xt_action_param *par);

struct sock *xt_socket_get6_sk(const struct sk_buff *skb,

net/netfilter/xt_socket.c

+53 −6
Original line number Diff line number Diff line
@@ -202,6 +202,7 @@ static bool 
socket_match(const struct sk_buff *skb, struct xt_action_param *par,

	     const struct xt_socket_mtinfo1 *info)

{

	struct sk_buff *pskb = (struct sk_buff *)skb;

	struct sock *sk;



	sk = xt_socket_get4_sk(skb, par);
@@ -225,6 +226,10 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, 
				       (sk->sk_state == TCP_TIME_WAIT &&

					inet_twsk(sk)->tw_transparent));



		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&

		    transparent)

			pskb->mark = sk->sk_mark;



		if (sk != skb->sk)

			sock_gen_put(sk);
@@ -246,7 +251,7 @@ socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) 
}



static bool

socket_mt4_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)

socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)

{

	return socket_match(skb, par, par->matchinfo);

}
@@ -376,8 +381,9 @@ xt_socket_get6_sk(const struct sk_buff *skb, struct xt_action_param *par) 
EXPORT_SYMBOL(xt_socket_get6_sk);



static bool

socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)

socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)

{

	struct sk_buff *pskb = (struct sk_buff *)skb;

	struct sock *sk;

	const struct xt_socket_mtinfo1 *info;
@@ -404,6 +410,10 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) 
				       (sk->sk_state == TCP_TIME_WAIT &&

					inet_twsk(sk)->tw_transparent));



		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&

		    transparent)

			pskb->mark = sk->sk_mark;



		if (sk != skb->sk)

			sock_gen_put(sk);
@@ -437,6 +447,19 @@ static int socket_mt_v2_check(const struct xt_mtchk_param *par) 
	return 0;

}



static int socket_mt_v3_check(const struct xt_mtchk_param *par)

{

	const struct xt_socket_mtinfo3 *info =

				     (struct xt_socket_mtinfo3 *)par->matchinfo;



	if (info->flags & ~XT_SOCKET_FLAGS_V3) {

		pr_info("unknown flags 0x%x\n",

			info->flags & ~XT_SOCKET_FLAGS_V3);

		return -EINVAL;

	}

	return 0;

}



static struct xt_match socket_mt_reg[] __read_mostly = {

	{

		.name		= "socket",
@@ -451,7 +474,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { 
		.name		= "socket",

		.revision	= 1,

		.family		= NFPROTO_IPV4,

		.match		= socket_mt4_v1_v2,

		.match		= socket_mt4_v1_v2_v3,

		.checkentry	= socket_mt_v1_check,

		.matchsize	= sizeof(struct xt_socket_mtinfo1),

		.hooks		= (1 << NF_INET_PRE_ROUTING) |
@@ -463,7 +486,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { 
		.name		= "socket",

		.revision	= 1,

		.family		= NFPROTO_IPV6,

		.match		= socket_mt6_v1_v2,

		.match		= socket_mt6_v1_v2_v3,

		.checkentry	= socket_mt_v1_check,

		.matchsize	= sizeof(struct xt_socket_mtinfo1),

		.hooks		= (1 << NF_INET_PRE_ROUTING) |
@@ -475,7 +498,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { 
		.name		= "socket",

		.revision	= 2,

		.family		= NFPROTO_IPV4,

		.match		= socket_mt4_v1_v2,

		.match		= socket_mt4_v1_v2_v3,

		.checkentry	= socket_mt_v2_check,

		.matchsize	= sizeof(struct xt_socket_mtinfo1),

		.hooks		= (1 << NF_INET_PRE_ROUTING) |
@@ -487,13 +510,37 @@ static struct xt_match socket_mt_reg[] __read_mostly = { 
		.name		= "socket",

		.revision	= 2,

		.family		= NFPROTO_IPV6,

		.match		= socket_mt6_v1_v2,

		.match		= socket_mt6_v1_v2_v3,

		.checkentry	= socket_mt_v2_check,

		.matchsize	= sizeof(struct xt_socket_mtinfo1),

		.hooks		= (1 << NF_INET_PRE_ROUTING) |

				  (1 << NF_INET_LOCAL_IN),

		.me		= THIS_MODULE,

	},

#endif

	{

		.name = "socket",

		.revision = 3,

		.family = NFPROTO_IPV4,

		.match = socket_mt4_v1_v2_v3,

		.checkentry = socket_mt_v3_check,

		.matchsize = sizeof(struct xt_socket_mtinfo1),

		.hooks = (1 << NF_INET_PRE_ROUTING) |

			 (1 << NF_INET_LOCAL_IN),

		.me = THIS_MODULE,

	},

#ifdef XT_SOCKET_HAVE_IPV6

	{

		.name = "socket",

		.revision = 3,

		.family = NFPROTO_IPV6,

		.match = socket_mt6_v1_v2_v3,

		.checkentry = socket_mt_v3_check,

		.matchsize = sizeof(struct xt_socket_mtinfo1),

		.hooks = (1 << NF_INET_PRE_ROUTING) |

			 (1 << NF_INET_LOCAL_IN),

		.me = THIS_MODULE,

	},

#endif

};