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drm_auth.c revision 1.1
      1 /**
      2  * \file drm_auth.c
      3  * IOCTLs for authentication
      4  *
      5  * \author Rickard E. (Rik) Faith <faith (at) valinux.com>
      6  * \author Gareth Hughes <gareth (at) valinux.com>
      7  */
      8 
      9 /*
     10  * Created: Tue Feb  2 08:37:54 1999 by faith (at) valinux.com
     11  *
     12  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
     13  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
     14  * All Rights Reserved.
     15  *
     16  * Permission is hereby granted, free of charge, to any person obtaining a
     17  * copy of this software and associated documentation files (the "Software"),
     18  * to deal in the Software without restriction, including without limitation
     19  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     20  * and/or sell copies of the Software, and to permit persons to whom the
     21  * Software is furnished to do so, subject to the following conditions:
     22  *
     23  * The above copyright notice and this permission notice (including the next
     24  * paragraph) shall be included in all copies or substantial portions of the
     25  * Software.
     26  *
     27  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     28  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     29  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     30  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
     31  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
     32  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     33  * OTHER DEALINGS IN THE SOFTWARE.
     34  */
     35 
     36 #include <drm/drmP.h>
     37 
     38 /**
     39  * Find the file with the given magic number.
     40  *
     41  * \param dev DRM device.
     42  * \param magic magic number.
     43  *
     44  * Searches in drm_device::magiclist within all files with the same hash key
     45  * the one with matching magic number, while holding the drm_device::struct_mutex
     46  * lock.
     47  */
     48 static struct drm_file *drm_find_file(struct drm_master *master, drm_magic_t magic)
     49 {
     50 	struct drm_file *retval = NULL;
     51 	struct drm_magic_entry *pt;
     52 	struct drm_hash_item *hash;
     53 	struct drm_device *dev = master->minor->dev;
     54 
     55 	mutex_lock(&dev->struct_mutex);
     56 	if (!drm_ht_find_item(&master->magiclist, (unsigned long)magic, &hash)) {
     57 		pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
     58 		retval = pt->priv;
     59 	}
     60 	mutex_unlock(&dev->struct_mutex);
     61 	return retval;
     62 }
     63 
     64 /**
     65  * Adds a magic number.
     66  *
     67  * \param dev DRM device.
     68  * \param priv file private data.
     69  * \param magic magic number.
     70  *
     71  * Creates a drm_magic_entry structure and appends to the linked list
     72  * associated the magic number hash key in drm_device::magiclist, while holding
     73  * the drm_device::struct_mutex lock.
     74  */
     75 static int drm_add_magic(struct drm_master *master, struct drm_file *priv,
     76 			 drm_magic_t magic)
     77 {
     78 	struct drm_magic_entry *entry;
     79 	struct drm_device *dev = master->minor->dev;
     80 	DRM_DEBUG("%d\n", magic);
     81 
     82 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
     83 	if (!entry)
     84 		return -ENOMEM;
     85 	entry->priv = priv;
     86 	entry->hash_item.key = (unsigned long)magic;
     87 	mutex_lock(&dev->struct_mutex);
     88 	drm_ht_insert_item(&master->magiclist, &entry->hash_item);
     89 	list_add_tail(&entry->head, &master->magicfree);
     90 	mutex_unlock(&dev->struct_mutex);
     91 
     92 	return 0;
     93 }
     94 
     95 /**
     96  * Remove a magic number.
     97  *
     98  * \param dev DRM device.
     99  * \param magic magic number.
    100  *
    101  * Searches and unlinks the entry in drm_device::magiclist with the magic
    102  * number hash key, while holding the drm_device::struct_mutex lock.
    103  */
    104 int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
    105 {
    106 	struct drm_magic_entry *pt;
    107 	struct drm_hash_item *hash;
    108 	struct drm_device *dev = master->minor->dev;
    109 
    110 	DRM_DEBUG("%d\n", magic);
    111 
    112 	mutex_lock(&dev->struct_mutex);
    113 	if (drm_ht_find_item(&master->magiclist, (unsigned long)magic, &hash)) {
    114 		mutex_unlock(&dev->struct_mutex);
    115 		return -EINVAL;
    116 	}
    117 	pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
    118 	drm_ht_remove_item(&master->magiclist, hash);
    119 	list_del(&pt->head);
    120 	mutex_unlock(&dev->struct_mutex);
    121 
    122 	kfree(pt);
    123 
    124 	return 0;
    125 }
    126 
    127 /**
    128  * Get a unique magic number (ioctl).
    129  *
    130  * \param inode device inode.
    131  * \param file_priv DRM file private.
    132  * \param cmd command.
    133  * \param arg pointer to a resulting drm_auth structure.
    134  * \return zero on success, or a negative number on failure.
    135  *
    136  * If there is a magic number in drm_file::magic then use it, otherwise
    137  * searches an unique non-zero magic number and add it associating it with \p
    138  * file_priv.
    139  * This ioctl needs protection by the drm_global_mutex, which protects
    140  * struct drm_file::magic and struct drm_magic_entry::priv.
    141  */
    142 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
    143 {
    144 	static drm_magic_t sequence = 0;
    145 	static DEFINE_SPINLOCK(lock);
    146 	struct drm_auth *auth = data;
    147 
    148 	/* Find unique magic */
    149 	if (file_priv->magic) {
    150 		auth->magic = file_priv->magic;
    151 	} else {
    152 		do {
    153 			spin_lock(&lock);
    154 			if (!sequence)
    155 				++sequence;	/* reserve 0 */
    156 			auth->magic = sequence++;
    157 			spin_unlock(&lock);
    158 		} while (drm_find_file(file_priv->master, auth->magic));
    159 		file_priv->magic = auth->magic;
    160 		drm_add_magic(file_priv->master, file_priv, auth->magic);
    161 	}
    162 
    163 	DRM_DEBUG("%u\n", auth->magic);
    164 
    165 	return 0;
    166 }
    167 
    168 /**
    169  * Authenticate with a magic.
    170  *
    171  * \param inode device inode.
    172  * \param file_priv DRM file private.
    173  * \param cmd command.
    174  * \param arg pointer to a drm_auth structure.
    175  * \return zero if authentication successed, or a negative number otherwise.
    176  *
    177  * Checks if \p file_priv is associated with the magic number passed in \arg.
    178  * This ioctl needs protection by the drm_global_mutex, which protects
    179  * struct drm_file::magic and struct drm_magic_entry::priv.
    180  */
    181 int drm_authmagic(struct drm_device *dev, void *data,
    182 		  struct drm_file *file_priv)
    183 {
    184 	struct drm_auth *auth = data;
    185 	struct drm_file *file;
    186 
    187 	DRM_DEBUG("%u\n", auth->magic);
    188 	if ((file = drm_find_file(file_priv->master, auth->magic))) {
    189 		file->authenticated = 1;
    190 		drm_remove_magic(file_priv->master, auth->magic);
    191 		return 0;
    192 	}
    193 	return -EINVAL;
    194 }
    195