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/**
* \file drm_auth.c
* IOCTLs for authentication
*
* \author Rickard E. (Rik) Faith <faith@valinux.com>
* \author Gareth Hughes <gareth@valinux.com>
*/

/*
* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
*
* 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.
*/

#include "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;
struct drm_magic_entry *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, struct drm_magic_entry, hash_item);
retval = pt->priv;
}
mutex_unlock(&dev->struct_mutex);
return retval;
}

/**
* Adds a magic number.
*
* \param dev DRM device.
* \param priv file private data.
* \param magic magic number.
*
* Creates a drm_magic_entry structure and appends to the linked list
* associated the magic number hash key in drm_device::magiclist, while holding
* the drm_device::struct_mutex lock.
*/
static int drm_add_magic(struct drm_device * dev, struct drm_file * priv,
drm_magic_t magic)
{
struct drm_magic_entry *entry;

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

entry = drm_alloc(sizeof(*entry), DRM_MEM_MAGIC);
if (!entry)
return -ENOMEM;
memset(entry, 0, sizeof(*entry));
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;
}

/**
* Remove a magic number.
*
* \param dev DRM device.
* \param magic magic number.
*
* Searches and unlinks the entry in drm_device::magiclist with the magic
* number hash key, while holding the drm_device::struct_mutex lock.
*/
static int drm_remove_magic(struct drm_device * dev, drm_magic_t magic)
{
struct drm_magic_entry *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, struct drm_magic_entry, hash_item);
drm_ht_remove_item(&dev->magiclist, hash);
list_del(&pt->head);
mutex_unlock(&dev->struct_mutex);

drm_free(pt, sizeof(*pt), DRM_MEM_MAGIC);

return 0;
}

/**
* Get a unique magic number (ioctl).
*
* \param inode device inode.
* \param file_priv DRM file private.
* \param cmd command.
* \param arg pointer to a resulting drm_auth structure.
* \return zero on success, or a negative number on failure.
*
* If there is a magic number in drm_file::magic then use it, otherwise
* searches an unique non-zero magic number and add it associating it with \p
* file_priv.
*/
int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
static drm_magic_t sequence = 0;
static DEFINE_SPINLOCK(lock);
struct drm_auth *auth = data;

/* Find unique magic */
if (file_priv->magic) {
auth->magic = file_priv->magic;
} else {
do {
spin_lock(&lock);
if (!sequence)
++sequence; /* reserve 0 */
auth->magic = sequence++;
spin_unlock(&lock);
} while (drm_find_file(dev, auth->magic));
file_priv->magic = auth->magic;
drm_add_magic(dev, file_priv, auth->magic);
}

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

return 0;
}

/**
* Authenticate with a magic.
*
* \param inode device inode.
* \param file_priv DRM file private.
* \param cmd command.
* \param arg pointer to a drm_auth structure.
* \return zero if authentication successed, or a negative number otherwise.
*
* Checks if \p file_priv is associated with the magic number passed in \arg.
*/
int drm_authmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_auth *auth = data;
struct drm_file *file;

DRM_DEBUG("%u\n", auth->magic);
if ((file = drm_find_file(dev, auth->magic))) {
file->authenticated = 1;
drm_remove_magic(dev, auth->magic);
return 0;
}
return -EINVAL;
}
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