drivers/gpu/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 <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 }