drivers/char/drm/drm_auth.c

   1 /**
   2  * \file drm_auth.c
   3  * IOCTLs for authentication
   4  *
   5  * \author Rickard E. (Rik) Faith <faith@valinux.com>
   6  * \author Gareth Hughes <gareth@valinux.com>
   7  */
   8
   9 /*
  10  * Created: Tue Feb  2 08:37:54 1999 by faith@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 "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_device * dev, drm_magic_t magic)
  49 {
  50         struct drm_file *retval = NULL;
  51         struct drm_magic_entry *pt;
  52         struct drm_hash_item *hash;
  53
  54         mutex_lock(&dev->struct_mutex);
  55         if (!drm_ht_find_item(&dev->magiclist, (unsigned long)magic, &hash)) {
  56                 pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
  57                 retval = pt->priv;
  58         }
  59         mutex_unlock(&dev->struct_mutex);
  60         return retval;
  61 }
  62
  63 /**
  64  * Adds a magic number.
  65  *
  66  * \param dev DRM device.
  67  * \param priv file private data.
  68  * \param magic magic number.
  69  *
  70  * Creates a drm_magic_entry structure and appends to the linked list
  71  * associated the magic number hash key in drm_device::magiclist, while holding
  72  * the drm_device::struct_mutex lock.
  73  */
  74 static int drm_add_magic(struct drm_device * dev, struct drm_file * priv,
  75                          drm_magic_t magic)
  76 {
  77         struct drm_magic_entry *entry;
  78
  79         DRM_DEBUG("%d\n", magic);
  80
  81         entry = drm_alloc(sizeof(*entry), DRM_MEM_MAGIC);
  82         if (!entry)
  83                 return -ENOMEM;
  84         memset(entry, 0, sizeof(*entry));
  85         entry->priv = priv;
  86
  87         entry->hash_item.key = (unsigned long)magic;
  88         mutex_lock(&dev->struct_mutex);
  89         drm_ht_insert_item(&dev->magiclist, &entry->hash_item);
  90         list_add_tail(&entry->head, &dev->magicfree);
  91         mutex_unlock(&dev->struct_mutex);
  92
  93         return 0;
  94 }
  95
  96 /**
  97  * Remove a magic number.
  98  *
  99  * \param dev DRM device.
 100  * \param magic magic number.
 101  *
 102  * Searches and unlinks the entry in drm_device::magiclist with the magic
 103  * number hash key, while holding the drm_device::struct_mutex lock.
 104  */
 105 static int drm_remove_magic(struct drm_device * dev, drm_magic_t magic)
 106 {
 107         struct drm_magic_entry *pt;
 108         struct drm_hash_item *hash;
 109
 110         DRM_DEBUG("%d\n", magic);
 111
 112         mutex_lock(&dev->struct_mutex);
 113         if (drm_ht_find_item(&dev->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(&dev->magiclist, hash);
 119         list_del(&pt->head);
 120         mutex_unlock(&dev->struct_mutex);
 121
 122         drm_free(pt, sizeof(*pt), DRM_MEM_MAGIC);
 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  */
 140 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 141 {
 142         static drm_magic_t sequence = 0;
 143         static DEFINE_SPINLOCK(lock);
 144         struct drm_auth *auth = data;
 145
 146         /* Find unique magic */
 147         if (file_priv->magic) {
 148                 auth->magic = file_priv->magic;
 149         } else {
 150                 do {
 151                         spin_lock(&lock);
 152                         if (!sequence)
 153                                 ++sequence;     /* reserve 0 */
 154                         auth->magic = sequence++;
 155                         spin_unlock(&lock);
 156                 } while (drm_find_file(dev, auth->magic));
 157                 file_priv->magic = auth->magic;
 158                 drm_add_magic(dev, file_priv, auth->magic);
 159         }
 160
 161         DRM_DEBUG("%u\n", auth->magic);
 162
 163         return 0;
 164 }
 165
 166 /**
 167  * Authenticate with a magic.
 168  *
 169  * \param inode device inode.
 170  * \param file_priv DRM file private.
 171  * \param cmd command.
 172  * \param arg pointer to a drm_auth structure.
 173  * \return zero if authentication successed, or a negative number otherwise.
 174  *
 175  * Checks if \p file_priv is associated with the magic number passed in \arg.
 176  */
 177 int drm_authmagic(struct drm_device *dev, void *data,
 178                   struct drm_file *file_priv)
 179 {
 180         struct drm_auth *auth = data;
 181         struct drm_file *file;
 182
 183         DRM_DEBUG("%u\n", auth->magic);
 184         if ((file = drm_find_file(dev, auth->magic))) {
 185                 file->authenticated = 1;
 186                 drm_remove_magic(dev, auth->magic);
 187                 return 0;
 188         }
 189         return -EINVAL;
 190 }