// SPDX-License-Identifier: GPL-2.0-only

  /*
   * 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@paul-moore.com>

   */
  #include <linux/init.h>
  #include <linux/types.h>

  #include <linux/slab.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

   * @ns: the network namespace

   * @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(const struct net *ns, int ifindex)

  {

  	return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));

  }

  /**
   * sel_netif_find - Search for an interface record

   * @ns: the network namespace

   * @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(const struct net *ns,
  					       int ifindex)

  {

  	int idx = sel_netif_hashfn(ns, ifindex);

  	struct sel_netif *netif;

  	list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)

  		if (net_eq(netif->nsec.ns, ns) &&
  		    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.ns, netif->nsec.ifindex);

  	list_add_rcu(&netif->list, &sel_netif_hash[idx]);
  	sel_netif_total++;

  
  	return 0;

  }

  /**

   * 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--;

  	kfree_rcu(netif, rcu_head);

  }

  /**
   * sel_netif_sid_slow - Lookup the SID of a network interface using the policy

   * @ns: the network namespace

   * @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(struct net *ns, int ifindex, u32 *sid)

  {

  	int ret = 0;

  	struct sel_netif *netif;

  	struct sel_netif *new;

  	struct net_device *dev;

  	/* NOTE: we always use init's network namespace since we don't
  	 * currently support containers */

  	dev = dev_get_by_index(ns, ifindex);

  	if (unlikely(dev == NULL)) {

  		pr_warn("SELinux: failure in %s(), invalid network interface (%d)
  ",
  			__func__, ifindex);

  		return -ENOENT;

  	}

  	spin_lock_bh(&sel_netif_lock);

  	netif = sel_netif_find(ns, ifindex);

  	if (netif != NULL) {
  		*sid = netif->nsec.sid;

  		goto out;
  	}

  
  	ret = security_netif_sid(&selinux_state, dev->name, sid);

  	if (ret != 0)
  		goto out;

  	new = kzalloc(sizeof(*new), GFP_ATOMIC);
  	if (new) {
  		new->nsec.ns = ns;
  		new->nsec.ifindex = ifindex;
  		new->nsec.sid = *sid;
  		if (sel_netif_insert(new))
  			kfree(new);
  	}

  out:

  	spin_unlock_bh(&sel_netif_lock);
  	dev_put(dev);

  	if (unlikely(ret))

  		pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)
  ",
  			__func__, ifindex);

  	return ret;
  }

  /**
   * sel_netif_sid - Lookup the SID of a network interface

   * @ns: the network namespace

   * @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(struct net *ns, int ifindex, u32 *sid)

  {

  	struct sel_netif *netif;
  
  	rcu_read_lock();

  	netif = sel_netif_find(ns, ifindex);

  	if (likely(netif != NULL)) {
  		*sid = netif->nsec.sid;

  		rcu_read_unlock();

  		return 0;

  	}

  	rcu_read_unlock();

  	return sel_netif_sid_slow(ns, ifindex, sid);

  }

  /**
   * sel_netif_kill - Remove an entry from the network interface table

   * @ns: the network namespace

   * @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(const struct net *ns, int ifindex)

  {
  	struct sel_netif *netif;

  	rcu_read_lock();

  	spin_lock_bh(&sel_netif_lock);

  	netif = sel_netif_find(ns, ifindex);

  	if (netif)
  		sel_netif_destroy(netif);
  	spin_unlock_bh(&sel_netif_lock);

  	rcu_read_unlock();

  }

  /**
   * sel_netif_flush - Flush the entire network interface table
   *
   * Description:
   * Remove all entries from the network interface table.
   *
   */

  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_netdev_notifier_handler(struct notifier_block *this,

  					     unsigned long event, void *ptr)

  {

  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  
  	if (event == NETDEV_DOWN)

  		sel_netif_kill(dev_net(dev), 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;

  	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);

  	return 0;

  }
  
  __initcall(sel_netif_init);