security/selinux/netport.c - kernel/prism - Git at Google

 /*
  * Network port table
  *
  * SELinux must keep a mapping of network ports to labels/SIDs.  This
  * mapping is maintained as part of the normal policy but a fast cache is
  * needed to reduce the lookup overhead.
  *
  * Author: Paul Moore <paul.moore@hp.com>
  *
  * This code is heavily based on the "netif" concept originally developed by
  * James Morris <jmorris@redhat.com>
  *   (see security/selinux/netif.c for more information)
  *
  */

 /*
  * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of version 2 of the GNU General Public License as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  */

 #include <linux/types.h>
 #include <linux/rcupdate.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <net/ip.h>
 #include <net/ipv6.h>

 #include "netport.h"
 #include "objsec.h"

 #define SEL_NETPORT_HASH_SIZE       256
 #define SEL_NETPORT_HASH_BKT_LIMIT   16

 struct sel_netport_bkt {
 	int size;
 	struct list_head list;
 };

 struct sel_netport {
 	struct netport_security_struct psec;

 	struct list_head list;
 	struct rcu_head rcu;
 };

 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
  * for this is that I suspect most users will not make heavy use of both
  * address families at the same time so one table will usually end up wasted,
  * if this becomes a problem we can always add a hash table for each address
  * family later */

 static LIST_HEAD(sel_netport_list);
 static DEFINE_SPINLOCK(sel_netport_lock);
 static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];

 /**
  * sel_netport_free - Frees a port entry
  * @p: the entry's RCU field
  *
  * Description:
  * This function is designed to be used as a callback to the call_rcu()
  * function so that memory allocated to a hash table port entry can be
  * released safely.
  *
  */
 static void sel_netport_free(struct rcu_head *p)
 {
 	struct sel_netport *port = container_of(p, struct sel_netport, rcu);
 	kfree(port);
 }

 /**
  * sel_netport_hashfn - Hashing function for the port table
  * @pnum: port number
  *
  * Description:
  * This is the hashing function for the port table, it returns the bucket
  * number for the given port.
  *
  */
 static unsigned int sel_netport_hashfn(u16 pnum)
 {
 	return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
 }

 /**
  * sel_netport_find - Search for a port record
  * @protocol: protocol
  * @port: pnum
  *
  * Description:
  * Search the network port table and return the matching record.  If an entry
  * can not be found in the table return NULL.
  *
  */
 static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
 {
 	unsigned int idx;
 	struct sel_netport *port;

 	idx = sel_netport_hashfn(pnum);
 	list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
 		if (port->psec.port == pnum && port->psec.protocol == protocol)
 			return port;

 	return NULL;
 }

 /**
  * sel_netport_insert - Insert a new port into the table
  * @port: the new port record
  *
  * Description:
  * Add a new port record to the network address hash table.
  *
  */
 static void sel_netport_insert(struct sel_netport *port)
 {
 	unsigned int idx;

 	/* we need to impose a limit on the growth of the hash table so check
 	 * this bucket to make sure it is within the specified bounds */
 	idx = sel_netport_hashfn(port->psec.port);
 	list_add_rcu(&port->list, &sel_netport_hash[idx].list);
 	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
 		struct sel_netport *tail;
 		tail = list_entry(
 			rcu_dereference(sel_netport_hash[idx].list.prev),
 			struct sel_netport, list);
 		list_del_rcu(&tail->list);
 		call_rcu(&tail->rcu, sel_netport_free);
 	} else
 		sel_netport_hash[idx].size++;
 }

 /**
  * sel_netport_sid_slow - Lookup the SID of a network address using the policy
  * @protocol: protocol
  * @pnum: port
  * @sid: port SID
  *
  * Description:
  * This function determines the SID of a network port by quering the security
  * policy.  The result is added to the network port table to speedup future
  * queries.  Returns zero on success, negative values on failure.
  *
  */
 static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
 {
 	int ret = -ENOMEM;
 	struct sel_netport *port;
 	struct sel_netport *new = NULL;

 	spin_lock_bh(&sel_netport_lock);
 	port = sel_netport_find(protocol, pnum);
 	if (port != NULL) {
 		*sid = port->psec.sid;
 		spin_unlock_bh(&sel_netport_lock);
 		return 0;
 	}
 	new = kzalloc(sizeof(*new), GFP_ATOMIC);
 	if (new == NULL)
 		goto out;
 	ret = security_port_sid(protocol, pnum, sid);
 	if (ret != 0)
 		goto out;

 	new->psec.port = pnum;
 	new->psec.protocol = protocol;
 	new->psec.sid = *sid;
 	sel_netport_insert(new);

 out:
 	spin_unlock_bh(&sel_netport_lock);
 	if (unlikely(ret)) {
 		printk(KERN_WARNING
 		       "SELinux: failure in sel_netport_sid_slow(),"
 		       " unable to determine network port label\n");
 		kfree(new);
 	}
 	return ret;
 }

 /**
  * sel_netport_sid - Lookup the SID of a network port
  * @protocol: protocol
  * @pnum: port
  * @sid: port SID
  *
  * Description:
  * This function determines the SID of a network port using the fastest method
  * possible.  First the port table is queried, but if an entry can't be found
  * then the policy is queried and the result is added to the table to speedup
  * future queries.  Returns zero on success, negative values on failure.
  *
  */
 int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
 {
 	struct sel_netport *port;

 	rcu_read_lock();
 	port = sel_netport_find(protocol, pnum);
 	if (port != NULL) {
 		*sid = port->psec.sid;
 		rcu_read_unlock();
 		return 0;
 	}
 	rcu_read_unlock();

 	return sel_netport_sid_slow(protocol, pnum, sid);
 }

 /**
  * sel_netport_flush - Flush the entire network port table
  *
  * Description:
  * Remove all entries from the network address table.
  *
  */
 static void sel_netport_flush(void)
 {
 	unsigned int idx;
 	struct sel_netport *port, *port_tmp;

 	spin_lock_bh(&sel_netport_lock);
 	for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
 		list_for_each_entry_safe(port, port_tmp,
 					 &sel_netport_hash[idx].list, list) {
 			list_del_rcu(&port->list);
 			call_rcu(&port->rcu, sel_netport_free);
 		}
 		sel_netport_hash[idx].size = 0;
 	}
 	spin_unlock_bh(&sel_netport_lock);
 }

 static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
 				    u16 class, u32 perms, u32 *retained)
 {
 	if (event == AVC_CALLBACK_RESET) {
 		sel_netport_flush();
 		synchronize_net();
 	}
 	return 0;
 }

 static __init int sel_netport_init(void)
 {
 	int iter;
 	int ret;

 	if (!selinux_enabled)
 		return 0;

 	for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
 		INIT_LIST_HEAD(&sel_netport_hash[iter].list);
 		sel_netport_hash[iter].size = 0;
 	}

 	ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
 			       SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
 	if (ret != 0)
 		panic("avc_add_callback() failed, error %d\n", ret);

 	return ret;
 }

 __initcall(sel_netport_init);
	/*
	* Network port table
	*
	* SELinux must keep a mapping of network ports to labels/SIDs. This
	* mapping is maintained as part of the normal policy but a fast cache is
	* needed to reduce the lookup overhead.
	*
	* Author: Paul Moore <paul.moore@hp.com>
	*
	* This code is heavily based on the "netif" concept originally developed by
	* James Morris <jmorris@redhat.com>
	* (see security/selinux/netif.c for more information)
	*
	*/

	/*
	* (c) Copyright Hewlett-Packard Development Company, L.P., 2008
	*
	* This program is free software: you can redistribute it and/or modify
	* it under the terms of version 2 of the GNU General Public License as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	*/

	#include <linux/types.h>
	#include <linux/rcupdate.h>
	#include <linux/list.h>
	#include <linux/spinlock.h>
	#include <linux/in.h>
	#include <linux/in6.h>
	#include <linux/ip.h>
	#include <linux/ipv6.h>
	#include <net/ip.h>
	#include <net/ipv6.h>

	#include "netport.h"
	#include "objsec.h"

	#define SEL_NETPORT_HASH_SIZE 256
	#define SEL_NETPORT_HASH_BKT_LIMIT 16

	struct sel_netport_bkt {
	int size;
	struct list_head list;
	};

	struct sel_netport {
	struct netport_security_struct psec;

	struct list_head list;
	struct rcu_head rcu;
	};

	/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
	* for this is that I suspect most users will not make heavy use of both
	* address families at the same time so one table will usually end up wasted,
	* if this becomes a problem we can always add a hash table for each address
	* family later */

	static LIST_HEAD(sel_netport_list);
	static DEFINE_SPINLOCK(sel_netport_lock);
	static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];

	/**
	* sel_netport_free - Frees a port entry
	* @p: the entry's RCU field
	*
	* Description:
	* This function is designed to be used as a callback to the call_rcu()
	* function so that memory allocated to a hash table port entry can be
	* released safely.
	*
	*/
	static void sel_netport_free(struct rcu_head *p)
	{
	struct sel_netport *port = container_of(p, struct sel_netport, rcu);
	kfree(port);
	}

	/**
	* sel_netport_hashfn - Hashing function for the port table
	* @pnum: port number
	*
	* Description:
	* This is the hashing function for the port table, it returns the bucket
	* number for the given port.
	*
	*/
	static unsigned int sel_netport_hashfn(u16 pnum)
	{
	return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
	}

	/**
	* sel_netport_find - Search for a port record
	* @protocol: protocol
	* @port: pnum
	*
	* Description:
	* Search the network port table and return the matching record. If an entry
	* can not be found in the table return NULL.
	*
	*/
	static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
	{
	unsigned int idx;
	struct sel_netport *port;

	idx = sel_netport_hashfn(pnum);
	list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
	if (port->psec.port == pnum && port->psec.protocol == protocol)
	return port;

	return NULL;
	}

	/**
	* sel_netport_insert - Insert a new port into the table
	* @port: the new port record
	*
	* Description:
	* Add a new port record to the network address hash table.
	*
	*/
	static void sel_netport_insert(struct sel_netport *port)
	{
	unsigned int idx;

	/* we need to impose a limit on the growth of the hash table so check
	* this bucket to make sure it is within the specified bounds */
	idx = sel_netport_hashfn(port->psec.port);
	list_add_rcu(&port->list, &sel_netport_hash[idx].list);
	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
	struct sel_netport *tail;
	tail = list_entry(
	rcu_dereference(sel_netport_hash[idx].list.prev),
	struct sel_netport, list);
	list_del_rcu(&tail->list);
	call_rcu(&tail->rcu, sel_netport_free);
	} else
	sel_netport_hash[idx].size++;
	}

	/**
	* sel_netport_sid_slow - Lookup the SID of a network address using the policy
	* @protocol: protocol
	* @pnum: port
	* @sid: port SID
	*
	* Description:
	* This function determines the SID of a network port by quering the security
	* policy. The result is added to the network port table to speedup future
	* queries. Returns zero on success, negative values on failure.
	*
	*/
	static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
	{
	int ret = -ENOMEM;
	struct sel_netport *port;
	struct sel_netport *new = NULL;

	spin_lock_bh(&sel_netport_lock);
	port = sel_netport_find(protocol, pnum);
	if (port != NULL) {
	*sid = port->psec.sid;
	spin_unlock_bh(&sel_netport_lock);
	return 0;
	}
	new = kzalloc(sizeof(*new), GFP_ATOMIC);
	if (new == NULL)
	goto out;
	ret = security_port_sid(protocol, pnum, sid);
	if (ret != 0)
	goto out;

	new->psec.port = pnum;
	new->psec.protocol = protocol;
	new->psec.sid = *sid;
	sel_netport_insert(new);

	out:
	spin_unlock_bh(&sel_netport_lock);
	if (unlikely(ret)) {
	printk(KERN_WARNING
	"SELinux: failure in sel_netport_sid_slow(),"
	" unable to determine network port label\n");
	kfree(new);
	}
	return ret;
	}

	/**
	* sel_netport_sid - Lookup the SID of a network port
	* @protocol: protocol
	* @pnum: port
	* @sid: port SID
	*
	* Description:
	* This function determines the SID of a network port using the fastest method
	* possible. First the port table is queried, but if an entry can't be found
	* then the policy is queried and the result is added to the table to speedup
	* future queries. Returns zero on success, negative values on failure.
	*
	*/
	int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
	{
	struct sel_netport *port;

	rcu_read_lock();
	port = sel_netport_find(protocol, pnum);
	if (port != NULL) {
	*sid = port->psec.sid;
	rcu_read_unlock();
	return 0;
	}
	rcu_read_unlock();

	return sel_netport_sid_slow(protocol, pnum, sid);
	}

	/**
	* sel_netport_flush - Flush the entire network port table
	*
	* Description:
	* Remove all entries from the network address table.
	*
	*/
	static void sel_netport_flush(void)
	{
	unsigned int idx;
	struct sel_netport port, port_tmp;

	spin_lock_bh(&sel_netport_lock);
	for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
	list_for_each_entry_safe(port, port_tmp,
	&sel_netport_hash[idx].list, list) {
	list_del_rcu(&port->list);
	call_rcu(&port->rcu, sel_netport_free);
	}
	sel_netport_hash[idx].size = 0;
	}
	spin_unlock_bh(&sel_netport_lock);
	}

	static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
	u16 class, u32 perms, u32 *retained)
	{
	if (event == AVC_CALLBACK_RESET) {
	sel_netport_flush();
	synchronize_net();
	}
	return 0;
	}

	static __init int sel_netport_init(void)
	{
	int iter;
	int ret;

	if (!selinux_enabled)
	return 0;

	for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
	INIT_LIST_HEAD(&sel_netport_hash[iter].list);
	sel_netport_hash[iter].size = 0;
	}

	ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
	SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
	if (ret != 0)
	panic("avc_add_callback() failed, error %d\n", ret);

	return ret;
	}

	__initcall(sel_netport_init);