security/selinux/netnode.c - linux - Git at Google

 /*
  * 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@paul-moore.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_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();
 		return NULL;
 	}

 	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();
 	}

 	/* 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_protected(sel_netnode_hash[idx].list.prev,
 						  lockdep_is_held(&sel_netnode_lock)),
 			struct sel_netnode, list);
 		list_del_rcu(&tail->list);
 		kfree_rcu(tail, rcu);
 	} 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);
 		new->nsec.addr.ipv6 = *(struct in6_addr *)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);
 				kfree_rcu(node, rcu);
 		}
 		sel_netnode_hash[idx].size = 0;
 	}
 	spin_unlock_bh(&sel_netnode_lock);
 }

 static int sel_netnode_avc_callback(u32 event)
 {
 	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);
 	if (ret != 0)
 		panic("avc_add_callback() failed, error %d\n", ret);

 	return ret;
 }

 __initcall(sel_netnode_init);
	/*
	* 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@paul-moore.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_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();
	return NULL;
	}

	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();
	}

	/* 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_protected(sel_netnode_hash[idx].list.prev,
	lockdep_is_held(&sel_netnode_lock)),
	struct sel_netnode, list);
	list_del_rcu(&tail->list);
	kfree_rcu(tail, rcu);
	} 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);
	new->nsec.addr.ipv6 = (struct in6_addr )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);
	kfree_rcu(node, rcu);
	}
	sel_netnode_hash[idx].size = 0;
	}
	spin_unlock_bh(&sel_netnode_lock);
	}

	static int sel_netnode_avc_callback(u32 event)
	{
	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);
	if (ret != 0)
	panic("avc_add_callback() failed, error %d\n", ret);

	return ret;
	}

	__initcall(sel_netnode_init);