/*
* Network interface table.
*
* Network interfaces (devices) do not have a security field, so we
* maintain a table associating each interface with a SID.
*
* Author: James Morris <jmorris@redhat.com>
*
* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
* Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
* Paul Moore <paul.moore@hp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2,
* as published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>
#include "security.h"
#include "objsec.h"
#include "netif.h"
#define SEL_NETIF_HASH_SIZE 64
#define SEL_NETIF_HASH_MAX 1024
struct sel_netif
{
struct list_head list;
struct netif_security_struct nsec;
struct rcu_head rcu_head;
};
static u32 sel_netif_total;
static LIST_HEAD(sel_netif_list);
static DEFINE_SPINLOCK(sel_netif_lock);
static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
/**
* sel_netif_hashfn - Hashing function for the interface table
* @ifindex: the network interface
*
* Description:
* This is the hashing function for the network interface table, it returns the
* bucket number for the given interface.
*
*/
static inline u32 sel_netif_hashfn(int ifindex)
{
return (ifindex & (SEL_NETIF_HASH_SIZE - 1));
}
/**
* sel_netif_find - Search for an interface record
* @ifindex: the network interface
*
* Description:
* Search the network interface table and return the record matching @ifindex.
* If an entry can not be found in the table return NULL.
*
*/
static inline struct sel_netif *sel_netif_find(int ifindex)
{
int idx = sel_netif_hashfn(ifindex);
struct sel_netif *netif;
list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
/* all of the devices should normally fit in the hash, so we
* optimize for that case */
if (likely(netif->nsec.ifindex == ifindex))
return netif;
return NULL;
}
/**
* sel_netif_insert - Insert a new interface into the table
* @netif: the new interface record
*
* Description:
* Add a new interface record to the network interface hash table. Returns
* zero on success, negative values on failure.
*
*/
static int sel_netif_insert(struct sel_netif *netif)
{
int idx;
if (sel_netif_total >= SEL_NETIF_HASH_MAX)
return -ENOSPC;
idx = sel_netif_hashfn(netif->nsec.ifindex);
list_add_rcu(&netif->list, &sel_netif_hash[idx]);
sel_netif_total++;
return 0;
}
/**
* sel_netif_free - Frees an interface 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 interface entry can be
* released safely.
*
*/
static void sel_netif_free(struct rcu_head *p)
{
struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
kfree(netif);
}
/**
* sel_netif_destroy - Remove an interface record from the table
* @netif: the existing interface record
*
* Description:
* Remove an existing interface record from the network interface table.
*
*/
static void sel_netif_destroy(struct sel_netif *netif)
{
list_del_rcu(&netif->list);
sel_netif_total--;
call_rcu(&netif->rcu_head, sel_netif_free);
}
/**
* sel_netif_sid_slow - Lookup the SID of a network interface using the policy
* @ifindex: the network interface
* @sid: interface SID
*
* Description:
* This function determines the SID of a network interface by quering the
* security policy. The result is added to the network interface table to
* speedup future queries. Returns zero on success, negative values on
* failure.
*
*/
static int sel_netif_sid_slow(int ifindex, u32 *sid)
{
int ret;
struct sel_netif *netif;
struct sel_netif *new = NULL;
struct net_device *dev;
/* NOTE: we always use init's network namespace since we don't
* currently support containers */
dev = dev_get_by_index(&init_net, ifindex);
if (dev == NULL)
return -ENOENT;
spin_lock_bh(&sel_netif_lock);
netif = sel_netif_find(ifindex);
if (netif != NULL) {
*sid = netif->nsec.sid;
ret = 0;
goto out;
}
new = kzalloc(sizeof(*new), GFP_ATOMIC);
if (new == NULL) {
ret = -ENOMEM;
goto out;
}
ret = security_netif_sid(dev->name, &new->nsec.sid);
if (ret != 0)
goto out;
new->nsec.ifindex = ifindex;
ret = sel_netif_insert(new);
if (ret != 0)
goto out;
*sid = new->nsec.sid;
out:
spin_unlock_bh(&sel_netif_lock);
dev_put(dev);
if (ret != 0)
kfree(new);
return ret;
}
/**
* sel_netif_sid - Lookup the SID of a network interface
* @ifindex: the network interface
* @sid: interface SID
*
* Description:
* This function determines the SID of a network interface using the fastest
* method possible. First the interface 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_netif_sid(int ifindex, u32 *sid)
{
struct sel_netif *netif;
rcu_read_lock();
netif = sel_netif_find(ifindex);
if (likely(netif != NULL)) {
*sid = netif->nsec.sid;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
return sel_netif_sid_slow(ifindex, sid);
}
/**
* sel_netif_kill - Remove an entry from the network interface table
* @ifindex: the network interface
*
* Description:
* This function removes the entry matching @ifindex from the network interface
* table if it exists.
*
*/
static void sel_netif_kill(int ifindex)
{
struct sel_netif *netif;
spin_lock_bh(&sel_netif_lock);
netif = sel_netif_find(ifindex);
if (netif)
sel_netif_destroy(netif);
spin_unlock_bh(&sel_netif_lock);
}
/**
* sel_netif_flush - Flush the entire network interface table
*
* Description:
* Remove all entries from the network interface table.
*
*/
static void sel_netif_flush(void)
{
int idx;
struct sel_netif *netif;
spin_lock_bh(&sel_netif_lock);
for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
list_for_each_entry(netif, &sel_netif_hash[idx], list)
sel_netif_destroy(netif);
spin_unlock_bh(&sel_netif_lock);
}
static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
u16 class, u32 perms, u32 *retained)
{
if (event == AVC_CALLBACK_RESET) {
sel_netif_flush();
synchronize_net();
}
return 0;
}
static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
if (dev->nd_net != &init_net)
return NOTIFY_DONE;
if (event == NETDEV_DOWN)
sel_netif_kill(dev->ifindex);
return NOTIFY_DONE;
}
static struct notifier_block sel_netif_netdev_notifier = {
.notifier_call = sel_netif_netdev_notifier_handler,
};
static __init int sel_netif_init(void)
{
int i, err;
if (!selinux_enabled)
return 0;
for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
INIT_LIST_HEAD(&sel_netif_hash[i]);
register_netdevice_notifier(&sel_netif_netdev_notifier);
err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
if (err)
panic("avc_add_callback() failed, error %d\n", err);
return err;
}
__initcall(sel_netif_init);
