[linux-2.6-block.git] / security / selinux / netnode.c

/*
 * Network node table
 *
 * SELinux must keep a mapping of network nodes to labels/SIDs.  This
 * mapping is maintained as part of the normal policy but a fast cache is
 * needed to reduce the lookup overhead since most of these queries happen on
 * a per-packet basis.
 *
 * 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., 2007
 *
 * 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 "netnode.h"
#include "objsec.h"

#define SEL_NETNODE_HASH_SIZE       256
#define SEL_NETNODE_HASH_BKT_LIMIT   16

struct sel_netnode_bkt {
	unsigned int size;
	struct list_head list;
};

struct sel_netnode {
	struct netnode_security_struct nsec;

	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_netnode_list);
static DEFINE_SPINLOCK(sel_netnode_lock);
static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];

/**
 * sel_netnode_free - Frees a node 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 node entry can be
 * released safely.
 *
 */
static void sel_netnode_free(struct rcu_head *p)
{
	struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
	kfree(node);
}

/**
 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
 * @addr: IPv4 address
 *
 * Description:
 * This is the IPv4 hashing function for the node interface table, it returns
 * the bucket number for the given IP address.
 *
 */
static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
{
	/* at some point we should determine if the mismatch in byte order
	 * affects the hash function dramatically */
	return (addr & (SEL_NETNODE_HASH_SIZE - 1));
}

/**
 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
 * @addr: IPv6 address
 *
 * Description:
 * This is the IPv6 hashing function for the node interface table, it returns
 * the bucket number for the given IP address.
 *
 */
static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
{
	/* just hash the least significant 32 bits to keep things fast (they
	 * are the most likely to be different anyway), we can revisit this
	 * later if needed */
	return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
}

/**
 * sel_netnode_find - Search for a node record
 * @addr: IP address
 * @family: address family
 *
 * Description:
 * Search the network node table and return the record matching @addr.  If an
 * entry can not be found in the table return NULL.
 *
 */
static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
{
	unsigned int idx;
	struct sel_netnode *node;

	switch (family) {
	case PF_INET:
		idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
		break;
	case PF_INET6:
		idx = sel_netnode_hashfn_ipv6(addr);
		break;
	default:
		BUG();
	}

	list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
		if (node->nsec.family == family)
			switch (family) {
			case PF_INET:
				if (node->nsec.addr.ipv4 == *(__be32 *)addr)
					return node;
				break;
			case PF_INET6:
				if (ipv6_addr_equal(&node->nsec.addr.ipv6,
						    addr))
					return node;
				break;
			}

	return NULL;
}

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

	switch (node->nsec.family) {
	case PF_INET:
		idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
		break;
	case PF_INET6:
		idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
		break;
	default:
		BUG();
	}

	INIT_RCU_HEAD(&node->rcu);

	/* 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 */
	list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
		struct sel_netnode *tail;
		tail = list_entry(
			rcu_dereference(sel_netnode_hash[idx].list.prev),
			struct sel_netnode, list);
		list_del_rcu(&tail->list);
		call_rcu(&tail->rcu, sel_netnode_free);
	} else
		sel_netnode_hash[idx].size++;
}

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

	spin_lock_bh(&sel_netnode_lock);
	node = sel_netnode_find(addr, family);
	if (node != NULL) {
		*sid = node->nsec.sid;
		spin_unlock_bh(&sel_netnode_lock);
		return 0;
	}
	new = kzalloc(sizeof(*new), GFP_ATOMIC);
	if (new == NULL)
		goto out;
	switch (family) {
	case PF_INET:
		ret = security_node_sid(PF_INET,
					addr, sizeof(struct in_addr), sid);
		new->nsec.addr.ipv4 = *(__be32 *)addr;
		break;
	case PF_INET6:
		ret = security_node_sid(PF_INET6,
					addr, sizeof(struct in6_addr), sid);
		ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
		break;
	default:
		BUG();
	}
	if (ret != 0)
		goto out;

	new->nsec.family = family;
	new->nsec.sid = *sid;
	sel_netnode_insert(new);

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

/**
 * sel_netnode_sid - Lookup the SID of a network address
 * @addr: the IP address
 * @family: the address family
 * @sid: node SID
 *
 * Description:
 * This function determines the SID of a network address using the fastest
 * method possible.  First the address 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_netnode_sid(void *addr, u16 family, u32 *sid)
{
	struct sel_netnode *node;

	rcu_read_lock();
	node = sel_netnode_find(addr, family);
	if (node != NULL) {
		*sid = node->nsec.sid;
		rcu_read_unlock();
		return 0;
	}
	rcu_read_unlock();

	return sel_netnode_sid_slow(addr, family, sid);
}

/**
 * sel_netnode_flush - Flush the entire network address table
 *
 * Description:
 * Remove all entries from the network address table.
 *
 */
static void sel_netnode_flush(void)
{
	unsigned int idx;
	struct sel_netnode *node, *node_tmp;

	spin_lock_bh(&sel_netnode_lock);
	for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
		list_for_each_entry_safe(node, node_tmp,
					 &sel_netnode_hash[idx].list, list) {
				list_del_rcu(&node->list);
				call_rcu(&node->rcu, sel_netnode_free);
		}
		sel_netnode_hash[idx].size = 0;
	}
	spin_unlock_bh(&sel_netnode_lock);
}

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

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

	if (!selinux_enabled)
		return 0;

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

	ret = avc_add_callback(sel_netnode_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_netnode_init);
Commit	Line	Data
224dfbd8 PM	1	/*
	2	* Network node table
	3	*
	4	* SELinux must keep a mapping of network nodes 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 since most of these queries happen on
	7	* a per-packet basis.
	8	*
	9	* Author: Paul Moore <paul.moore@hp.com>
	10	*
	11	* This code is heavily based on the "netif" concept originally developed by
	12	* James Morris <jmorris@redhat.com>
	13	* (see security/selinux/netif.c for more information)
	14	*
	15	*/
	16
	17	/*
	18	* (c) Copyright Hewlett-Packard Development Company, L.P., 2007
	19	*
	20	* This program is free software: you can redistribute it and/or modify
	21	* it under the terms of version 2 of the GNU General Public License as
	22	* published by the Free Software Foundation.
	23	*
	24	* This program is distributed in the hope that it will be useful,
	25	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	26	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	27	* GNU General Public License for more details.
	28	*
	29	*/
	30
	31	#include <linux/types.h>
	32	#include <linux/rcupdate.h>
	33	#include <linux/list.h>
	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>
224dfbd8	41
a639e7ca	42	#include "netnode.h"
224dfbd8 PM	43	#include "objsec.h"
	44
	45	#define SEL_NETNODE_HASH_SIZE 256
	46	#define SEL_NETNODE_HASH_BKT_LIMIT 16
	47
a639e7ca PM	48	struct sel_netnode_bkt {
	49	unsigned int size;
	50	struct list_head list;
	51	};
	52
224dfbd8 PM	53	struct sel_netnode {
	54	struct netnode_security_struct nsec;
	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_netnode_list);
	67	static DEFINE_SPINLOCK(sel_netnode_lock);
a639e7ca	68	static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
224dfbd8 PM	69
	70	/**
	71	* sel_netnode_free - Frees a node 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 node entry can be
	77	* released safely.
	78	*
	79	*/
	80	static void sel_netnode_free(struct rcu_head *p)
	81	{
	82	struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
	83	kfree(node);
	84	}
	85
	86	/**
	87	* sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
	88	* @addr: IPv4 address
	89	*
	90	* Description:
	91	* This is the IPv4 hashing function for the node interface table, it returns
	92	* the bucket number for the given IP address.
	93	*
	94	*/
a639e7ca	95	static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
224dfbd8 PM	96	{
	97	/* at some point we should determine if the mismatch in byte order
	98	* affects the hash function dramatically */
	99	return (addr & (SEL_NETNODE_HASH_SIZE - 1));
	100	}
	101
	102	/**
	103	* sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
	104	* @addr: IPv6 address
	105	*
	106	* Description:
	107	* This is the IPv6 hashing function for the node interface table, it returns
	108	* the bucket number for the given IP address.
	109	*
	110	*/
a639e7ca	111	static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
224dfbd8 PM	112	{
	113	/* just hash the least significant 32 bits to keep things fast (they
	114	* are the most likely to be different anyway), we can revisit this
	115	* later if needed */
	116	return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
	117	}
	118
	119	/**
	120	* sel_netnode_find - Search for a node record
	121	* @addr: IP address
	122	* @family: address family
	123	*
	124	* Description:
	125	* Search the network node table and return the record matching @addr. If an
	126	* entry can not be found in the table return NULL.
	127	*
	128	*/
	129	static struct sel_netnode sel_netnode_find(const void addr, u16 family)
	130	{
a639e7ca	131	unsigned int idx;
224dfbd8 PM	132	struct sel_netnode *node;
	133
	134	switch (family) {
	135	case PF_INET:
	136	idx = sel_netnode_hashfn_ipv4((__be32 )addr);
	137	break;
	138	case PF_INET6:
	139	idx = sel_netnode_hashfn_ipv6(addr);
	140	break;
	141	default:
	142	BUG();
	143	}
	144
a639e7ca	145	list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
224dfbd8 PM	146	if (node->nsec.family == family)
	147	switch (family) {
	148	case PF_INET:
	149	if (node->nsec.addr.ipv4 == (__be32 )addr)
	150	return node;
	151	break;
	152	case PF_INET6:
	153	if (ipv6_addr_equal(&node->nsec.addr.ipv6,
	154	addr))
	155	return node;
	156	break;
	157	}
	158
	159	return NULL;
	160	}
	161
	162	/**
	163	* sel_netnode_insert - Insert a new node into the table
	164	* @node: the new node record
	165	*
	166	* Description:
a639e7ca	167	* Add a new node record to the network address hash table.
224dfbd8 PM	168	*
224dfbd8 PM	169	*/
a639e7ca	170	static void sel_netnode_insert(struct sel_netnode *node)
224dfbd8	171	{
a639e7ca	172	unsigned int idx;
224dfbd8 PM	173
	174	switch (node->nsec.family) {
	175	case PF_INET:
	176	idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
	177	break;
	178	case PF_INET6:
	179	idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
	180	break;
	181	default:
	182	BUG();
	183	}
a639e7ca PM	184
a639e7ca PM	185	INIT_RCU_HEAD(&node->rcu);
224dfbd8 PM	186
	187	/* we need to impose a limit on the growth of the hash table so check
	188	* this bucket to make sure it is within the specified bounds */
a639e7ca PM	189	list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
	190	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
	191	struct sel_netnode *tail;
	192	tail = list_entry(
	193	rcu_dereference(sel_netnode_hash[idx].list.prev),
	194	struct sel_netnode, list);
	195	list_del_rcu(&tail->list);
	196	call_rcu(&tail->rcu, sel_netnode_free);
	197	} else
	198	sel_netnode_hash[idx].size++;
224dfbd8 PM	199	}
	200
	201	/**
	202	* sel_netnode_sid_slow - Lookup the SID of a network address using the policy
	203	* @addr: the IP address
	204	* @family: the address family
	205	* @sid: node SID
	206	*
	207	* Description:
	208	* This function determines the SID of a network address by quering the
	209	* security policy. The result is added to the network address table to
	210	* speedup future queries. Returns zero on success, negative values on
	211	* failure.
	212	*
	213	*/
	214	static int sel_netnode_sid_slow(void addr, u16 family, u32 sid)
	215	{
a639e7ca	216	int ret = -ENOMEM;
224dfbd8 PM	217	struct sel_netnode *node;
	218	struct sel_netnode *new = NULL;
	219
	220	spin_lock_bh(&sel_netnode_lock);
	221	node = sel_netnode_find(addr, family);
	222	if (node != NULL) {
	223	*sid = node->nsec.sid;
a639e7ca PM	224	spin_unlock_bh(&sel_netnode_lock);
a639e7ca PM	225	return 0;
224dfbd8 PM	226	}
224dfbd8 PM	227	new = kzalloc(sizeof(*new), GFP_ATOMIC);
a639e7ca	228	if (new == NULL)
224dfbd8	229	goto out;
224dfbd8 PM	230	switch (family) {
	231	case PF_INET:
	232	ret = security_node_sid(PF_INET,
a639e7ca	233	addr, sizeof(struct in_addr), sid);
224dfbd8 PM	234	new->nsec.addr.ipv4 = (__be32 )addr;
	235	break;
	236	case PF_INET6:
	237	ret = security_node_sid(PF_INET6,
a639e7ca	238	addr, sizeof(struct in6_addr), sid);
224dfbd8 PM	239	ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
	240	break;
	241	default:
	242	BUG();
	243	}
	244	if (ret != 0)
	245	goto out;
a639e7ca	246
224dfbd8	247	new->nsec.family = family;
a639e7ca PM	248	new->nsec.sid = *sid;
a639e7ca PM	249	sel_netnode_insert(new);
224dfbd8 PM	250
	251	out:
	252	spin_unlock_bh(&sel_netnode_lock);
71f1cb05 PM	253	if (unlikely(ret)) {
	254	printk(KERN_WARNING
	255	"SELinux: failure in sel_netnode_sid_slow(),"
	256	" unable to determine network node label\n");
224dfbd8	257	kfree(new);
71f1cb05	258	}
224dfbd8 PM	259	return ret;
	260	}
	261
	262	/**
	263	* sel_netnode_sid - Lookup the SID of a network address
	264	* @addr: the IP address
	265	* @family: the address family
	266	* @sid: node SID
	267	*
	268	* Description:
	269	* This function determines the SID of a network address using the fastest
	270	* method possible. First the address table is queried, but if an entry
	271	* can't be found then the policy is queried and the result is added to the
	272	* table to speedup future queries. Returns zero on success, negative values
	273	* on failure.
	274	*
	275	*/
	276	int sel_netnode_sid(void addr, u16 family, u32 sid)
	277	{
	278	struct sel_netnode *node;
	279
	280	rcu_read_lock();
	281	node = sel_netnode_find(addr, family);
	282	if (node != NULL) {
	283	*sid = node->nsec.sid;
	284	rcu_read_unlock();
	285	return 0;
	286	}
	287	rcu_read_unlock();
	288
	289	return sel_netnode_sid_slow(addr, family, sid);
	290	}
	291
	292	/**
	293	* sel_netnode_flush - Flush the entire network address table
	294	*
	295	* Description:
	296	* Remove all entries from the network address table.
	297	*
	298	*/
	299	static void sel_netnode_flush(void)
	300	{
a639e7ca PM	301	unsigned int idx;
a639e7ca PM	302	struct sel_netnode node, node_tmp;
224dfbd8 PM	303
224dfbd8 PM	304	spin_lock_bh(&sel_netnode_lock);
a639e7ca PM	305	for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
	306	list_for_each_entry_safe(node, node_tmp,
	307	&sel_netnode_hash[idx].list, list) {
	308	list_del_rcu(&node->list);
	309	call_rcu(&node->rcu, sel_netnode_free);
	310	}
	311	sel_netnode_hash[idx].size = 0;
	312	}
224dfbd8 PM	313	spin_unlock_bh(&sel_netnode_lock);
	314	}
	315
	316	static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
	317	u16 class, u32 perms, u32 *retained)
	318	{
	319	if (event == AVC_CALLBACK_RESET) {
	320	sel_netnode_flush();
	321	synchronize_net();
	322	}
	323	return 0;
	324	}
	325
	326	static __init int sel_netnode_init(void)
	327	{
	328	int iter;
	329	int ret;
	330
	331	if (!selinux_enabled)
	332	return 0;
	333
a639e7ca PM	334	for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
	335	INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
	336	sel_netnode_hash[iter].size = 0;
	337	}
224dfbd8 PM	338
224dfbd8 PM	339	ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
7b6b239c	340	SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
224dfbd8 PM	341	if (ret != 0)
	342	panic("avc_add_callback() failed, error %d\n", ret);
	343
	344	return ret;
	345	}
	346
	347	__initcall(sel_netnode_init);