[linux-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/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 "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>
5a0e3ad6	34	#include <linux/slab.h>
224dfbd8 PM	35	#include <linux/spinlock.h>
	36	#include <linux/in.h>
	37	#include <linux/in6.h>
	38	#include <linux/ip.h>
	39	#include <linux/ipv6.h>
	40	#include <net/ip.h>
	41	#include <net/ipv6.h>
224dfbd8	42
a639e7ca	43	#include "netnode.h"
224dfbd8 PM	44	#include "objsec.h"
	45
	46	#define SEL_NETNODE_HASH_SIZE 256
	47	#define SEL_NETNODE_HASH_BKT_LIMIT 16
	48
a639e7ca PM	49	struct sel_netnode_bkt {
	50	unsigned int size;
	51	struct list_head list;
	52	};
	53
224dfbd8 PM	54	struct sel_netnode {
	55	struct netnode_security_struct nsec;
	56
	57	struct list_head list;
	58	struct rcu_head rcu;
	59	};
	60
	61	/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
	62	* for this is that I suspect most users will not make heavy use of both
	63	* address families at the same time so one table will usually end up wasted,
	64	* if this becomes a problem we can always add a hash table for each address
	65	* family later */
	66
	67	static LIST_HEAD(sel_netnode_list);
	68	static DEFINE_SPINLOCK(sel_netnode_lock);
a639e7ca	69	static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
224dfbd8 PM	70
	71	/**
	72	* sel_netnode_free - Frees a node entry
	73	* @p: the entry's RCU field
	74	*
	75	* Description:
	76	* This function is designed to be used as a callback to the call_rcu()
	77	* function so that memory allocated to a hash table node entry can be
	78	* released safely.
	79	*
	80	*/
	81	static void sel_netnode_free(struct rcu_head *p)
	82	{
	83	struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
	84	kfree(node);
	85	}
	86
	87	/**
	88	* sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
	89	* @addr: IPv4 address
	90	*
	91	* Description:
	92	* This is the IPv4 hashing function for the node interface table, it returns
	93	* the bucket number for the given IP address.
	94	*
	95	*/
a639e7ca	96	static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
224dfbd8 PM	97	{
	98	/* at some point we should determine if the mismatch in byte order
	99	* affects the hash function dramatically */
	100	return (addr & (SEL_NETNODE_HASH_SIZE - 1));
	101	}
	102
	103	/**
	104	* sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
	105	* @addr: IPv6 address
	106	*
	107	* Description:
	108	* This is the IPv6 hashing function for the node interface table, it returns
	109	* the bucket number for the given IP address.
	110	*
	111	*/
a639e7ca	112	static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
224dfbd8 PM	113	{
	114	/* just hash the least significant 32 bits to keep things fast (they
	115	* are the most likely to be different anyway), we can revisit this
	116	* later if needed */
	117	return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
	118	}
	119
	120	/**
	121	* sel_netnode_find - Search for a node record
	122	* @addr: IP address
	123	* @family: address family
	124	*
	125	* Description:
	126	* Search the network node table and return the record matching @addr. If an
	127	* entry can not be found in the table return NULL.
	128	*
	129	*/
	130	static struct sel_netnode sel_netnode_find(const void addr, u16 family)
	131	{
a639e7ca	132	unsigned int idx;
224dfbd8 PM	133	struct sel_netnode *node;
	134
	135	switch (family) {
	136	case PF_INET:
	137	idx = sel_netnode_hashfn_ipv4((__be32 )addr);
	138	break;
	139	case PF_INET6:
	140	idx = sel_netnode_hashfn_ipv6(addr);
	141	break;
	142	default:
	143	BUG();
	144	}
	145
a639e7ca	146	list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
224dfbd8 PM	147	if (node->nsec.family == family)
	148	switch (family) {
	149	case PF_INET:
	150	if (node->nsec.addr.ipv4 == (__be32 )addr)
	151	return node;
	152	break;
	153	case PF_INET6:
	154	if (ipv6_addr_equal(&node->nsec.addr.ipv6,
	155	addr))
	156	return node;
	157	break;
	158	}
	159
	160	return NULL;
	161	}
	162
	163	/**
	164	* sel_netnode_insert - Insert a new node into the table
	165	* @node: the new node record
	166	*
	167	* Description:
a639e7ca	168	* Add a new node record to the network address hash table.
224dfbd8 PM	169	*
224dfbd8 PM	170	*/
a639e7ca	171	static void sel_netnode_insert(struct sel_netnode *node)
224dfbd8	172	{
a639e7ca	173	unsigned int idx;
224dfbd8 PM	174
	175	switch (node->nsec.family) {
	176	case PF_INET:
	177	idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
	178	break;
	179	case PF_INET6:
	180	idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
	181	break;
	182	default:
	183	BUG();
	184	}
a639e7ca PM	185
a639e7ca PM	186	INIT_RCU_HEAD(&node->rcu);
224dfbd8 PM	187
	188	/* we need to impose a limit on the growth of the hash table so check
	189	* this bucket to make sure it is within the specified bounds */
a639e7ca PM	190	list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
	191	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
	192	struct sel_netnode *tail;
	193	tail = list_entry(
	194	rcu_dereference(sel_netnode_hash[idx].list.prev),
	195	struct sel_netnode, list);
	196	list_del_rcu(&tail->list);
	197	call_rcu(&tail->rcu, sel_netnode_free);
	198	} else
	199	sel_netnode_hash[idx].size++;
224dfbd8 PM	200	}
	201
	202	/**
	203	* sel_netnode_sid_slow - Lookup the SID of a network address using the policy
	204	* @addr: the IP address
	205	* @family: the address family
	206	* @sid: node SID
	207	*
	208	* Description:
	209	* This function determines the SID of a network address by quering the
	210	* security policy. The result is added to the network address table to
	211	* speedup future queries. Returns zero on success, negative values on
	212	* failure.
	213	*
	214	*/
	215	static int sel_netnode_sid_slow(void addr, u16 family, u32 sid)
	216	{
a639e7ca	217	int ret = -ENOMEM;
224dfbd8 PM	218	struct sel_netnode *node;
	219	struct sel_netnode *new = NULL;
	220
	221	spin_lock_bh(&sel_netnode_lock);
	222	node = sel_netnode_find(addr, family);
	223	if (node != NULL) {
	224	*sid = node->nsec.sid;
a639e7ca PM	225	spin_unlock_bh(&sel_netnode_lock);
a639e7ca PM	226	return 0;
224dfbd8 PM	227	}
224dfbd8 PM	228	new = kzalloc(sizeof(*new), GFP_ATOMIC);
a639e7ca	229	if (new == NULL)
224dfbd8	230	goto out;
224dfbd8 PM	231	switch (family) {
	232	case PF_INET:
	233	ret = security_node_sid(PF_INET,
a639e7ca	234	addr, sizeof(struct in_addr), sid);
224dfbd8 PM	235	new->nsec.addr.ipv4 = (__be32 )addr;
	236	break;
	237	case PF_INET6:
	238	ret = security_node_sid(PF_INET6,
a639e7ca	239	addr, sizeof(struct in6_addr), sid);
224dfbd8 PM	240	ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
	241	break;
	242	default:
	243	BUG();
	244	}
	245	if (ret != 0)
	246	goto out;
a639e7ca	247
224dfbd8	248	new->nsec.family = family;
a639e7ca PM	249	new->nsec.sid = *sid;
a639e7ca PM	250	sel_netnode_insert(new);
224dfbd8 PM	251
	252	out:
	253	spin_unlock_bh(&sel_netnode_lock);
71f1cb05 PM	254	if (unlikely(ret)) {
	255	printk(KERN_WARNING
	256	"SELinux: failure in sel_netnode_sid_slow(),"
	257	" unable to determine network node label\n");
224dfbd8	258	kfree(new);
71f1cb05	259	}
224dfbd8 PM	260	return ret;
	261	}
	262
	263	/**
	264	* sel_netnode_sid - Lookup the SID of a network address
	265	* @addr: the IP address
	266	* @family: the address family
	267	* @sid: node SID
	268	*
	269	* Description:
	270	* This function determines the SID of a network address using the fastest
	271	* method possible. First the address table is queried, but if an entry
	272	* can't be found then the policy is queried and the result is added to the
	273	* table to speedup future queries. Returns zero on success, negative values
	274	* on failure.
	275	*
	276	*/
	277	int sel_netnode_sid(void addr, u16 family, u32 sid)
	278	{
	279	struct sel_netnode *node;
	280
	281	rcu_read_lock();
	282	node = sel_netnode_find(addr, family);
	283	if (node != NULL) {
	284	*sid = node->nsec.sid;
	285	rcu_read_unlock();
	286	return 0;
	287	}
	288	rcu_read_unlock();
	289
	290	return sel_netnode_sid_slow(addr, family, sid);
	291	}
	292
	293	/**
	294	* sel_netnode_flush - Flush the entire network address table
	295	*
	296	* Description:
	297	* Remove all entries from the network address table.
	298	*
	299	*/
	300	static void sel_netnode_flush(void)
	301	{
a639e7ca PM	302	unsigned int idx;
a639e7ca PM	303	struct sel_netnode node, node_tmp;
224dfbd8 PM	304
224dfbd8 PM	305	spin_lock_bh(&sel_netnode_lock);
a639e7ca PM	306	for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
	307	list_for_each_entry_safe(node, node_tmp,
	308	&sel_netnode_hash[idx].list, list) {
	309	list_del_rcu(&node->list);
	310	call_rcu(&node->rcu, sel_netnode_free);
	311	}
	312	sel_netnode_hash[idx].size = 0;
	313	}
224dfbd8 PM	314	spin_unlock_bh(&sel_netnode_lock);
	315	}
	316
	317	static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
	318	u16 class, u32 perms, u32 *retained)
	319	{
	320	if (event == AVC_CALLBACK_RESET) {
	321	sel_netnode_flush();
	322	synchronize_net();
	323	}
	324	return 0;
	325	}
	326
	327	static __init int sel_netnode_init(void)
	328	{
	329	int iter;
	330	int ret;
	331
	332	if (!selinux_enabled)
	333	return 0;
	334
a639e7ca PM	335	for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
	336	INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
	337	sel_netnode_hash[iter].size = 0;
	338	}
224dfbd8 PM	339
224dfbd8 PM	340	ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
7b6b239c	341	SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
224dfbd8 PM	342	if (ret != 0)
	343	panic("avc_add_callback() failed, error %d\n", ret);
	344
	345	return ret;
	346	}
	347
	348	__initcall(sel_netnode_init);