netif.c

Linux Kernel 2.6.9 for OMAP1710

/*
 * 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 <[e-mail]>
 *
 * Copyright (C) 2003 Red Hat, Inc., James Morris <[e-mail]>
 *
 * 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 "security.h"
#include "objsec.h"
#include "netif.h"

#define SEL_NETIF_HASH_SIZE	64
#define SEL_NETIF_HASH_MAX	1024

#undef DEBUG

#ifdef DEBUG
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

static u32 sel_netif_total;
static LIST_HEAD(sel_netif_list);
static spinlock_t sel_netif_lock = SPIN_LOCK_UNLOCKED;
static struct sel_netif sel_netif_hash[SEL_NETIF_HASH_SIZE];

static inline u32 sel_netif_hasfn(struct net_device *dev)
{
	return (dev->ifindex & (SEL_NETIF_HASH_SIZE - 1));
}

/*
 * All of the devices should normally fit in the hash, so we optimize
 * for that case.
 */
static struct sel_netif *sel_netif_find(struct net_device *dev)
{
	struct list_head *pos;
	int idx = sel_netif_hasfn(dev);

	__list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
		struct sel_netif *netif = list_entry(pos,
		                                     struct sel_netif, list);
		if (likely(netif->nsec.dev == dev))
			return netif;
	}
	return NULL;
}

static int sel_netif_insert(struct sel_netif *netif)
{
	int idx, ret = 0;
	
	if (sel_netif_total >= SEL_NETIF_HASH_MAX) {
		ret = -ENOSPC;
		goto out;
	}
	
	idx = sel_netif_hasfn(netif->nsec.dev);
	list_add_rcu(&netif->list, &sel_netif_hash[idx].list);
	atomic_set(&netif->users, 1);
	sel_netif_total++;
out:
	return ret;
}

struct sel_netif *sel_netif_lookup(struct net_device *dev)
{
	int ret;
	struct sel_netif *netif, *new;
	struct netif_security_struct *nsec;

	rcu_read_lock();
	netif = sel_netif_find(dev);
	rcu_read_unlock();
	
	if (likely(netif != NULL))
		goto out_hold;
	
	new = kmalloc(sizeof(*new), GFP_ATOMIC);
	if (!new) {
		netif = ERR_PTR(-ENOMEM);
		goto out;
	}
	
	memset(new, 0, sizeof(*new));
	nsec = &new->nsec;

	ret = security_netif_sid(dev->name, &nsec->if_sid, &nsec->msg_sid);
	if (ret < 0) {
		kfree(new);
		netif = ERR_PTR(ret);
		goto out;
	}

	nsec->dev = dev;
	
	spin_lock_bh(&sel_netif_lock);
	
	netif = sel_netif_find(dev);
	if (netif) {
		spin_unlock_bh(&sel_netif_lock);
		kfree(new);
		goto out_hold;
	}
	
	sel_netif_insert(new);
	spin_unlock_bh(&sel_netif_lock);
	
	netif = new;
	
	DEBUGP("new: ifindex=%u name=%s if_sid=%u msg_sid=%u\n", dev->ifindex, dev->name,
	        nsec->if_sid, nsec->msg_sid);
out_hold:
	atomic_inc(&netif->users);
out:
	return netif;
}

static void sel_netif_free(struct rcu_head *p)
{
	struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
	
	DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
	kfree(netif);
}

static void sel_netif_destroy(struct sel_netif *netif)
{
	DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
	
	spin_lock_bh(&sel_netif_lock);
	list_del_rcu(&netif->list);
	sel_netif_total--;
	spin_unlock_bh(&sel_netif_lock);

	call_rcu(&netif->rcu_head, sel_netif_free);
}

void sel_netif_put(struct sel_netif *netif)
{
	if (atomic_dec_and_test(&netif->users))
		sel_netif_destroy(netif);
}

static void sel_netif_kill(struct net_device *dev)
{
	struct sel_netif *netif;
	
	rcu_read_lock();
	netif = sel_netif_find(dev);
	rcu_read_unlock();

	/* Drop internal reference */
	if (netif)
		sel_netif_put(netif);
}

static void sel_netif_flush(void)
{
	int idx;

	for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) {
		struct list_head *pos;
		
		list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
			struct sel_netif *netif;
			
			netif = list_entry(pos, struct sel_netif, list);
			if (netif)
				sel_netif_put(netif);
		}
	}
}

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 (event == NETDEV_DOWN)
		sel_netif_kill(dev);

	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 = 0;
	
	if (!selinux_enabled)
		goto out;

	for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
		INIT_LIST_HEAD(&sel_netif_hash[i].list);

	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);

out:
	return err;
}

__initcall(sel_netif_init);