/*-
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Rickard E. (Rik) Faith <faith@valinux.com>
 *    Gareth Hughes <gareth@valinux.com>
 *
 * $FreeBSD: src/sys/dev/drm2/drm_auth.c,v 1.1 2012/05/22 11:07:44 kib Exp $
 */

/** @file drm_auth.c
 * Implementation of the get/authmagic ioctls implementing the authentication
 * scheme between the master and clients.
 */

#include <drm/drmP.h>

/**
 * Find the file with the given magic number.
 *
 * \param dev DRM device.
 * \param magic magic number.
 *
 * Searches in drm_device::magiclist within all files with the same hash key
 * the one with matching magic number, while holding the drm_device::struct_mutex
 * lock.
 */
static struct drm_file *drm_find_file(struct drm_device *dev, drm_magic_t magic)
{
	struct drm_file *retval = NULL;
	drm_magic_entry_t *pt;
	struct drm_hash_item *hash;

	mutex_lock(&dev->struct_mutex);
	if (!drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
		pt = drm_hash_entry(hash, drm_magic_entry_t, hash_item);
		retval = pt->priv;
	}
	mutex_unlock(&dev->struct_mutex);
	return retval;
}

/**
 * Inserts the given magic number into the hash table of used magic number
 * lists.
 */
static int drm_add_magic(struct drm_device *dev, struct drm_file *priv,
			 drm_magic_t magic)
{
	drm_magic_entry_t *entry;

	DRM_DEBUG("%d\n", magic);

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
		return -ENOMEM;
	entry->priv = priv;
	entry->hash_item.key = (unsigned long)magic;
	mutex_lock(&dev->struct_mutex);
	drm_ht_insert_item(&dev->magiclist, &entry->hash_item);
	list_add_tail(&entry->head, &dev->magicfree);
	mutex_unlock(&dev->struct_mutex);

	return 0;
}

/**
 * Removes the given magic number from the hash table of used magic number
 * lists.
 */
static int drm_remove_magic(struct drm_device *dev, drm_magic_t magic)
{
	drm_magic_entry_t *pt;
	struct drm_hash_item *hash;

	DRM_DEBUG("%d\n", magic);

	mutex_lock(&dev->struct_mutex);
	if (drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
		mutex_unlock(&dev->struct_mutex);
		return -EINVAL;
	}
	pt = drm_hash_entry(hash, drm_magic_entry_t, hash_item);
	drm_ht_remove_item(&dev->magiclist, hash);
	list_del(&pt->head);
	mutex_unlock(&dev->struct_mutex);

	kfree(pt);

	return 0;
}

/**
 * Called by the client, this returns a unique magic number to be authorized
 * by the master.
 *
 * The master may use its own knowledge of the client (such as the X
 * connection that the magic is passed over) to determine if the magic number
 * should be authenticated.
 */
int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
	static drm_magic_t sequence = 0;
	struct drm_auth *auth = data;

	/* Find unique magic */
	if (file_priv->magic) {
		auth->magic = file_priv->magic;
	} else {
		DRM_LOCK(dev);
		do {
			int old = sequence;

			auth->magic = old+1;

			if (!atomic_cmpset_int(&sequence, old, auth->magic))
				continue;
		} while (drm_find_file(dev, auth->magic));
		file_priv->magic = auth->magic;
		drm_add_magic(dev, file_priv, auth->magic);
		DRM_UNLOCK(dev);
	}

	DRM_DEBUG("%u\n", auth->magic);

	return 0;
}

/**
 * Marks the client associated with the given magic number as authenticated.
 */
int drm_authmagic(struct drm_device *dev, void *data,
		  struct drm_file *file_priv)
{
	struct drm_auth *auth = data;
	struct drm_file *priv;

	DRM_DEBUG("%u\n", auth->magic);

	DRM_LOCK(dev);
	priv = drm_find_file(dev, auth->magic);
	if (priv != NULL) {
		priv->authenticated = 1;
		drm_remove_magic(dev, auth->magic);
		DRM_UNLOCK(dev);
		return 0;
	} else {
		DRM_UNLOCK(dev);
		return EINVAL;
	}
}