/*
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License as
   *  published by the Free Software Foundation, version 2 of the
   *  License.
   */
  
  #include <linux/module.h>

  #include <linux/nsproxy.h>

  #include <linux/slab.h>

  #include <linux/user_namespace.h>

  #include <linux/cred.h>

  /*

   * Create a new user namespace, deriving the creator from the user in the
   * passed credentials, and replacing that user with the new root user for the
   * new namespace.
   *
   * This is called by copy_creds(), which will finish setting the target task's
   * credentials.

   */

  int create_user_ns(struct cred *new)

  {
  	struct user_namespace *ns;

  	struct user_struct *root_user;

  	int n;
  
  	ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
  	if (!ns)

  		return -ENOMEM;

  
  	kref_init(&ns->kref);
  
  	for (n = 0; n < UIDHASH_SZ; ++n)

  		INIT_HLIST_HEAD(ns->uidhash_table + n);

  	/* Alloc new root user.  */
  	root_user = alloc_uid(ns, 0);
  	if (!root_user) {

  		kfree(ns);

  		return -ENOMEM;

  	}

  	/* set the new root user in the credentials under preparation */
  	ns->creator = new->user;
  	new->user = root_user;
  	new->uid = new->euid = new->suid = new->fsuid = 0;
  	new->gid = new->egid = new->sgid = new->fsgid = 0;
  	put_group_info(new->group_info);
  	new->group_info = get_group_info(&init_groups);
  #ifdef CONFIG_KEYS
  	key_put(new->request_key_auth);
  	new->request_key_auth = NULL;
  #endif
  	/* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */

  	/* alloc_uid() incremented the userns refcount.  Just set it to 1 */
  	kref_set(&ns->kref, 1);

  	return 0;

  }
  
  void free_user_ns(struct kref *kref)
  {
  	struct user_namespace *ns;
  
  	ns = container_of(kref, struct user_namespace, kref);

  	free_uid(ns->creator);

  	kfree(ns);
  }

  EXPORT_SYMBOL(free_user_ns);