/* user_defined.c: user defined key type
   *
   * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * 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; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/slab.h>
  #include <linux/seq_file.h>
  #include <linux/err.h>

  #include <keys/user-type.h>

  #include <asm/uaccess.h>
  #include "internal.h"

  /*
   * user defined keys take an arbitrary string as the description and an
   * arbitrary blob of data as the payload
   */
  struct key_type key_type_user = {
  	.name		= "user",
  	.instantiate	= user_instantiate,

  	.update		= user_update,
  	.match		= user_match,

  	.revoke		= user_revoke,

  	.destroy	= user_destroy,
  	.describe	= user_describe,
  	.read		= user_read,
  };

  EXPORT_SYMBOL_GPL(key_type_user);

  /*
   * instantiate a user defined key
   */

  int user_instantiate(struct key *key, const void *data, size_t datalen)

  {

  	struct user_key_payload *upayload;

  	int ret;
  
  	ret = -EINVAL;
  	if (datalen <= 0 || datalen > 32767 || !data)
  		goto error;
  
  	ret = key_payload_reserve(key, datalen);
  	if (ret < 0)
  		goto error;

  	ret = -ENOMEM;

  	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
  	if (!upayload)

  		goto error;

  	/* attach the data */
  	upayload->datalen = datalen;
  	memcpy(upayload->data, data, datalen);
  	rcu_assign_pointer(key->payload.data, upayload);

  	ret = 0;

  error:

  	return ret;

  }

  EXPORT_SYMBOL_GPL(user_instantiate);

  /*

   * update a user defined key

   * - the key's semaphore is write-locked

   */

  int user_update(struct key *key, const void *data, size_t datalen)

  {

  	struct user_key_payload *upayload, *zap;

  	int ret;
  
  	ret = -EINVAL;
  	if (datalen <= 0 || datalen > 32767 || !data)
  		goto error;

  	/* construct a replacement payload */

  	ret = -ENOMEM;

  	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
  	if (!upayload)

  		goto error;

  	upayload->datalen = datalen;
  	memcpy(upayload->data, data, datalen);

  
  	/* check the quota and attach the new data */

  	zap = upayload;

  
  	ret = key_payload_reserve(key, datalen);
  
  	if (ret == 0) {
  		/* attach the new data, displacing the old */
  		zap = key->payload.data;

  		rcu_assign_pointer(key->payload.data, upayload);

  		key->expiry = 0;
  	}

  	if (zap)
  		kfree_rcu(zap, rcu);

  error:

  	return ret;

  }

  EXPORT_SYMBOL_GPL(user_update);

  /*
   * match users on their name
   */

  int user_match(const struct key *key, const void *description)

  {
  	return strcmp(key->description, description) == 0;

  }

  EXPORT_SYMBOL_GPL(user_match);

  /*

   * dispose of the links from a revoked keyring
   * - called with the key sem write-locked
   */
  void user_revoke(struct key *key)
  {
  	struct user_key_payload *upayload = key->payload.data;
  
  	/* clear the quota */
  	key_payload_reserve(key, 0);
  
  	if (upayload) {
  		rcu_assign_pointer(key->payload.data, NULL);

  		kfree_rcu(upayload, rcu);

  	}

  }

  
  EXPORT_SYMBOL(user_revoke);

  /*
   * dispose of the data dangling from the corpse of a user key

   */

  void user_destroy(struct key *key)

  {

  	struct user_key_payload *upayload = key->payload.data;
  
  	kfree(upayload);

  }

  EXPORT_SYMBOL_GPL(user_destroy);

  /*

   * describe the user key

   */

  void user_describe(const struct key *key, struct seq_file *m)

  {
  	seq_puts(m, key->description);

  	if (key_is_instantiated(key))
  		seq_printf(m, ": %u", key->datalen);

  }

  EXPORT_SYMBOL_GPL(user_describe);

  /*
   * read the key data

   * - the key's semaphore is read-locked

   */

  long user_read(const struct key *key, char __user *buffer, size_t buflen)

  {

  	struct user_key_payload *upayload;
  	long ret;

  	upayload = rcu_dereference_key(key);

  	ret = upayload->datalen;

  
  	/* we can return the data as is */
  	if (buffer && buflen > 0) {

  		if (buflen > upayload->datalen)
  			buflen = upayload->datalen;

  		if (copy_to_user(buffer, upayload->data, buflen) != 0)

  			ret = -EFAULT;
  	}
  
  	return ret;

  }

  
  EXPORT_SYMBOL_GPL(user_read);