[net-next-2.6.git] / security / selinux / netport.c

/*
 * 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/slab.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);
Commit	Line	Data
27cc2a6e JM	1	/*
	2	* Network port table
	3	*
	4	* SELinux must keep a mapping of network ports to labels/SIDs. This
	5	* mapping is maintained as part of the normal policy but a fast cache is
	6	* needed to reduce the lookup overhead.
	7	*
	8	* Author: Paul Moore <paul.moore@hp.com>
	9	*
	10	* This code is heavily based on the "netif" concept originally developed by
	11	* James Morris <jmorris@redhat.com>
	12	* (see security/selinux/netif.c for more information)
	13	*
	14	*/
	15
	16	/*
	17	* (c) Copyright Hewlett-Packard Development Company, L.P., 2008
	18	*
	19	* This program is free software: you can redistribute it and/or modify
	20	* it under the terms of version 2 of the GNU General Public License as
	21	* published by the Free Software Foundation.
	22	*
	23	* This program is distributed in the hope that it will be useful,
	24	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	25	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	26	* GNU General Public License for more details.
	27	*
	28	*/
	29
	30	#include <linux/types.h>
	31	#include <linux/rcupdate.h>
	32	#include <linux/list.h>
5a0e3ad6	33	#include <linux/slab.h>
27cc2a6e JM	34	#include <linux/spinlock.h>
	35	#include <linux/in.h>
	36	#include <linux/in6.h>
	37	#include <linux/ip.h>
	38	#include <linux/ipv6.h>
	39	#include <net/ip.h>
	40	#include <net/ipv6.h>
27cc2a6e JM	41
	42	#include "netport.h"
	43	#include "objsec.h"
	44
	45	#define SEL_NETPORT_HASH_SIZE 256
	46	#define SEL_NETPORT_HASH_BKT_LIMIT 16
	47
	48	struct sel_netport_bkt {
	49	int size;
	50	struct list_head list;
	51	};
	52
	53	struct sel_netport {
	54	struct netport_security_struct psec;
	55
	56	struct list_head list;
	57	struct rcu_head rcu;
	58	};
	59
	60	/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
	61	* for this is that I suspect most users will not make heavy use of both
	62	* address families at the same time so one table will usually end up wasted,
	63	* if this becomes a problem we can always add a hash table for each address
	64	* family later */
	65
	66	static LIST_HEAD(sel_netport_list);
	67	static DEFINE_SPINLOCK(sel_netport_lock);
	68	static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
	69
	70	/**
	71	* sel_netport_free - Frees a port entry
	72	* @p: the entry's RCU field
	73	*
	74	* Description:
	75	* This function is designed to be used as a callback to the call_rcu()
	76	* function so that memory allocated to a hash table port entry can be
	77	* released safely.
	78	*
	79	*/
	80	static void sel_netport_free(struct rcu_head *p)
	81	{
	82	struct sel_netport *port = container_of(p, struct sel_netport, rcu);
	83	kfree(port);
	84	}
	85
	86	/**
	87	* sel_netport_hashfn - Hashing function for the port table
	88	* @pnum: port number
	89	*
	90	* Description:
	91	* This is the hashing function for the port table, it returns the bucket
	92	* number for the given port.
	93	*
	94	*/
	95	static unsigned int sel_netport_hashfn(u16 pnum)
	96	{
	97	return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
	98	}
	99
	100	/**
	101	* sel_netport_find - Search for a port record
	102	* @protocol: protocol
	103	* @port: pnum
	104	*
105	* Description:
106	* Search the network port table and return the matching record. If an entry
107	* can not be found in the table return NULL.
108	*
109	*/
110	static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
111	{
112	unsigned int idx;
113	struct sel_netport *port;
114
115	idx = sel_netport_hashfn(pnum);
116	list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
c9b7b979	117	if (port->psec.port == pnum && port->psec.protocol == protocol)
27cc2a6e JM	118	return port;
	119
	120	return NULL;
	121	}
	122
	123	/**
	124	* sel_netport_insert - Insert a new port into the table
	125	* @port: the new port record
	126	*
	127	* Description:
c9b7b979	128	* Add a new port record to the network address hash table.
27cc2a6e JM	129	*
27cc2a6e JM	130	*/
c9b7b979	131	static void sel_netport_insert(struct sel_netport *port)
27cc2a6e JM	132	{
	133	unsigned int idx;
	134
	135	/* we need to impose a limit on the growth of the hash table so check
	136	* this bucket to make sure it is within the specified bounds */
	137	idx = sel_netport_hashfn(port->psec.port);
	138	list_add_rcu(&port->list, &sel_netport_hash[idx].list);
	139	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
	140	struct sel_netport *tail;
c9b7b979 PM	141	tail = list_entry(
	142	rcu_dereference(sel_netport_hash[idx].list.prev),
	143	struct sel_netport, list);
	144	list_del_rcu(&tail->list);
27cc2a6e JM	145	call_rcu(&tail->rcu, sel_netport_free);
	146	} else
	147	sel_netport_hash[idx].size++;
27cc2a6e JM	148	}
	149
	150	/**
	151	* sel_netport_sid_slow - Lookup the SID of a network address using the policy
	152	* @protocol: protocol
	153	* @pnum: port
	154	* @sid: port SID
	155	*
	156	* Description:
	157	* This function determines the SID of a network port by quering the security
	158	* policy. The result is added to the network port table to speedup future
	159	* queries. Returns zero on success, negative values on failure.
	160	*
	161	*/
	162	static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
	163	{
c9b7b979	164	int ret = -ENOMEM;
27cc2a6e JM	165	struct sel_netport *port;
	166	struct sel_netport *new = NULL;
	167
	168	spin_lock_bh(&sel_netport_lock);
	169	port = sel_netport_find(protocol, pnum);
	170	if (port != NULL) {
	171	*sid = port->psec.sid;
c9b7b979 PM	172	spin_unlock_bh(&sel_netport_lock);
c9b7b979 PM	173	return 0;
27cc2a6e JM	174	}
27cc2a6e JM	175	new = kzalloc(sizeof(*new), GFP_ATOMIC);
c9b7b979	176	if (new == NULL)
27cc2a6e	177	goto out;
c9b7b979	178	ret = security_port_sid(protocol, pnum, sid);
27cc2a6e JM	179	if (ret != 0)
27cc2a6e JM	180	goto out;
c9b7b979	181
27cc2a6e JM	182	new->psec.port = pnum;
27cc2a6e JM	183	new->psec.protocol = protocol;
c9b7b979 PM	184	new->psec.sid = *sid;
c9b7b979 PM	185	sel_netport_insert(new);
27cc2a6e JM	186
	187	out:
	188	spin_unlock_bh(&sel_netport_lock);
	189	if (unlikely(ret)) {
	190	printk(KERN_WARNING
	191	"SELinux: failure in sel_netport_sid_slow(),"
	192	" unable to determine network port label\n");
	193	kfree(new);
	194	}
	195	return ret;
	196	}
	197
	198	/**
	199	* sel_netport_sid - Lookup the SID of a network port
	200	* @protocol: protocol
	201	* @pnum: port
	202	* @sid: port SID
	203	*
	204	* Description:
	205	* This function determines the SID of a network port using the fastest method
	206	* possible. First the port table is queried, but if an entry can't be found
	207	* then the policy is queried and the result is added to the table to speedup
	208	* future queries. Returns zero on success, negative values on failure.
	209	*
	210	*/
	211	int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
	212	{
	213	struct sel_netport *port;
	214
	215	rcu_read_lock();
	216	port = sel_netport_find(protocol, pnum);
	217	if (port != NULL) {
	218	*sid = port->psec.sid;
	219	rcu_read_unlock();
	220	return 0;
	221	}
	222	rcu_read_unlock();
	223
	224	return sel_netport_sid_slow(protocol, pnum, sid);
	225	}
	226
	227	/**
	228	* sel_netport_flush - Flush the entire network port table
	229	*
	230	* Description:
	231	* Remove all entries from the network address table.
	232	*
	233	*/
	234	static void sel_netport_flush(void)
	235	{
	236	unsigned int idx;
c9b7b979	237	struct sel_netport port, port_tmp;
27cc2a6e JM	238
	239	spin_lock_bh(&sel_netport_lock);
	240	for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
c9b7b979 PM	241	list_for_each_entry_safe(port, port_tmp,
c9b7b979 PM	242	&sel_netport_hash[idx].list, list) {
27cc2a6e JM	243	list_del_rcu(&port->list);
	244	call_rcu(&port->rcu, sel_netport_free);
	245	}
	246	sel_netport_hash[idx].size = 0;
	247	}
	248	spin_unlock_bh(&sel_netport_lock);
	249	}
	250
	251	static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
	252	u16 class, u32 perms, u32 *retained)
	253	{
	254	if (event == AVC_CALLBACK_RESET) {
	255	sel_netport_flush();
	256	synchronize_net();
	257	}
	258	return 0;
	259	}
	260
	261	static __init int sel_netport_init(void)
	262	{
	263	int iter;
	264	int ret;
	265
	266	if (!selinux_enabled)
	267	return 0;
	268
	269	for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
	270	INIT_LIST_HEAD(&sel_netport_hash[iter].list);
	271	sel_netport_hash[iter].size = 0;
	272	}
	273
	274	ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
f5269710	275	SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
27cc2a6e JM	276	if (ret != 0)
	277	panic("avc_add_callback() failed, error %d\n", ret);
	278
	279	return ret;
	280	}
	281
	282	__initcall(sel_netport_init);