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Commit 560ee653 authored by James Morris's avatar James Morris Committed by David S. Miller
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netfilter: ip_tables: add iptables security table for mandatory access control rules 



The following patch implements a new "security" table for iptables, so
that MAC (SELinux etc.) networking rules can be managed separately to
standard DAC rules.

This is to help with distro integration of the new secmark-based
network controls, per various previous discussions.

The need for a separate table arises from the fact that existing tools
and usage of iptables will likely clash with centralized MAC policy
management.

The SECMARK and CONNSECMARK targets will still be valid in the mangle
table to prevent breakage of existing users.

Signed-off-by: default avatarJames Morris <jmorris@namei.org>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a258860e

include/linux/netfilter_ipv4.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ enum nf_ip_hook_priorities { 
	NF_IP_PRI_MANGLE = -150,

	NF_IP_PRI_NAT_DST = -100,

	NF_IP_PRI_FILTER = 0,

	NF_IP_PRI_SECURITY = 50,

	NF_IP_PRI_NAT_SRC = 100,

	NF_IP_PRI_SELINUX_LAST = 225,

	NF_IP_PRI_CONNTRACK_CONFIRM = INT_MAX,

include/net/netns/ipv4.h

+1 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ struct netns_ipv4 { 
	struct xt_table		*iptable_mangle;

	struct xt_table		*iptable_raw;

	struct xt_table		*arptable_filter;

	struct xt_table		*iptable_security;

#endif



	int sysctl_icmp_echo_ignore_all;

net/ipv4/netfilter/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -365,6 +365,18 @@ config IP_NF_RAW 
	  If you want to compile it as a module, say M here and read

	  <file:Documentation/kbuild/modules.txt>.  If unsure, say `N'.



# security table for MAC policy

config IP_NF_SECURITY

	tristate "Security table"

	depends on IP_NF_IPTABLES

	depends on SECURITY

	default m if NETFILTER_ADVANCED=n

	help

	  This option adds a `security' table to iptables, for use

	  with Mandatory Access Control (MAC) policy.

	 

	  If unsure, say N.



# ARP tables

config IP_NF_ARPTABLES

	tristate "ARP tables support"

net/ipv4/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ obj-$(CONFIG_IP_NF_FILTER) += iptable_filter.o 
obj-$(CONFIG_IP_NF_MANGLE) += iptable_mangle.o

obj-$(CONFIG_NF_NAT) += iptable_nat.o

obj-$(CONFIG_IP_NF_RAW) += iptable_raw.o

obj-$(CONFIG_IP_NF_SECURITY) += iptable_security.o



# matches

obj-$(CONFIG_IP_NF_MATCH_ADDRTYPE) += ipt_addrtype.o

net/ipv4/netfilter/iptable_security.c

0 → 100644
+180 −0
Original line number Diff line number Diff line 
/*

 * "security" table

 *

 * This is for use by Mandatory Access Control (MAC) security models,

 * which need to be able to manage security policy in separate context

 * to DAC.

 *

 * Based on iptable_mangle.c

 *

 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling

 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam <at> netfilter.org>

 * Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.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/module.h>

#include <linux/netfilter_ipv4/ip_tables.h>

#include <net/ip.h>



MODULE_LICENSE("GPL");

MODULE_AUTHOR("James Morris <jmorris <at> redhat.com>");

MODULE_DESCRIPTION("iptables security table, for MAC rules");



#define SECURITY_VALID_HOOKS	(1 << NF_INET_LOCAL_IN) | \

				(1 << NF_INET_FORWARD) | \

				(1 << NF_INET_LOCAL_OUT)



static struct

{

	struct ipt_replace repl;

	struct ipt_standard entries[3];

	struct ipt_error term;

} initial_table __initdata = {

	.repl = {

		.name = "security",

		.valid_hooks = SECURITY_VALID_HOOKS,

		.num_entries = 4,

		.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),

		.hook_entry = {

			[NF_INET_LOCAL_IN] 	= 0,

			[NF_INET_FORWARD] 	= sizeof(struct ipt_standard),

			[NF_INET_LOCAL_OUT] 	= sizeof(struct ipt_standard) * 2,

		},

		.underflow = {

			[NF_INET_LOCAL_IN] 	= 0,

			[NF_INET_FORWARD] 	= sizeof(struct ipt_standard),

			[NF_INET_LOCAL_OUT] 	= sizeof(struct ipt_standard) * 2,

		},

	},

	.entries = {

		IPT_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */

		IPT_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */

		IPT_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */

	},

	.term = IPT_ERROR_INIT,			/* ERROR */

};



static struct xt_table security_table = {

	.name		= "security",

	.valid_hooks	= SECURITY_VALID_HOOKS,

	.lock		= __RW_LOCK_UNLOCKED(security_table.lock),

	.me		= THIS_MODULE,

	.af		= AF_INET,

};



static unsigned int

ipt_local_in_hook(unsigned int hook,

		  struct sk_buff *skb,

		  const struct net_device *in,

		  const struct net_device *out,

		  int (*okfn)(struct sk_buff *))

{

	return ipt_do_table(skb, hook, in, out,

			    nf_local_in_net(in, out)->ipv4.iptable_security);

}



static unsigned int

ipt_forward_hook(unsigned int hook,

		 struct sk_buff *skb,

		 const struct net_device *in,

		 const struct net_device *out,

		 int (*okfn)(struct sk_buff *))

{

	return ipt_do_table(skb, hook, in, out,

			    nf_forward_net(in, out)->ipv4.iptable_security);

}



static unsigned int

ipt_local_out_hook(unsigned int hook,

		   struct sk_buff *skb,

		   const struct net_device *in,

		   const struct net_device *out,

		   int (*okfn)(struct sk_buff *))

{

	/* Somebody is playing with raw sockets. */

	if (skb->len < sizeof(struct iphdr)

	    || ip_hdrlen(skb) < sizeof(struct iphdr)) {

		if (net_ratelimit())

			printk(KERN_INFO "iptable_security: ignoring short "

			       "SOCK_RAW packet.\n");

		return NF_ACCEPT;

	}

	return ipt_do_table(skb, hook, in, out,

			    nf_local_out_net(in, out)->ipv4.iptable_security);

}



static struct nf_hook_ops ipt_ops[] __read_mostly = {

	{

		.hook		= ipt_local_in_hook,

		.owner		= THIS_MODULE,

		.pf		= PF_INET,

		.hooknum	= NF_INET_LOCAL_IN,

		.priority	= NF_IP_PRI_SECURITY,

	},

	{

		.hook		= ipt_forward_hook,

		.owner		= THIS_MODULE,

		.pf		= PF_INET,

		.hooknum	= NF_INET_FORWARD,

		.priority	= NF_IP_PRI_SECURITY,

	},

	{

		.hook		= ipt_local_out_hook,

		.owner		= THIS_MODULE,

		.pf		= PF_INET,

		.hooknum	= NF_INET_LOCAL_OUT,

		.priority	= NF_IP_PRI_SECURITY,

	},

};



static int __net_init iptable_security_net_init(struct net *net)

{

	net->ipv4.iptable_security =

		ipt_register_table(net, &security_table, &initial_table.repl);



	if (IS_ERR(net->ipv4.iptable_security))

		return PTR_ERR(net->ipv4.iptable_security);



	return 0;

}



static void __net_exit iptable_security_net_exit(struct net *net)

{

	ipt_unregister_table(net->ipv4.iptable_security);

}



static struct pernet_operations iptable_security_net_ops = {

	.init = iptable_security_net_init,

	.exit = iptable_security_net_exit,

};



static int __init iptable_security_init(void)

{

	int ret;



	ret = register_pernet_subsys(&iptable_security_net_ops);

        if (ret < 0)

		return ret;



	ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));

	if (ret < 0)

		goto cleanup_table;



	return ret;



cleanup_table:

	unregister_pernet_subsys(&iptable_security_net_ops);

	return ret;

}



static void __exit iptable_security_fini(void)

{

	nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));

	unregister_pernet_subsys(&iptable_security_net_ops);

}



module_init(iptable_security_init);

module_exit(iptable_security_fini);