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 #include "drm_internal.h"
  38
  39 struct drm_magic_entry {
  40         struct list_head head;
  41         struct drm_hash_item hash_item;
  42         struct drm_file *priv;
  43 };
  44
  45 /**
  46  * Find the file with the given magic number.
  47  *
  48  * \param dev DRM device.
  49  * \param magic magic number.
  50  *
  51  * Searches in drm_device::magiclist within all files with the same hash key
  52  * the one with matching magic number, while holding the drm_device::struct_mutex
  53  * lock.
  54  */
  55 static struct drm_file *drm_find_file(struct drm_master *master, drm_magic_t magic)
  56 {
  57         struct drm_file *retval = NULL;
  58         struct drm_magic_entry *pt;
  59         struct drm_hash_item *hash;
  60         struct drm_device *dev = master->minor->dev;
  61
  62         mutex_lock(&dev->struct_mutex);
  63         if (!drm_ht_find_item(&master->magiclist, (unsigned long)magic, &hash)) {
  64                 pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
  65                 retval = pt->priv;
  66         }
  67         mutex_unlock(&dev->struct_mutex);
  68         return retval;
  69 }
  70
  71 /**
  72  * Adds a magic number.
  73  *
  74  * \param dev DRM device.
  75  * \param priv file private data.
  76  * \param magic magic number.
  77  *
  78  * Creates a drm_magic_entry structure and appends to the linked list
  79  * associated the magic number hash key in drm_device::magiclist, while holding
  80  * the drm_device::struct_mutex lock.
  81  */
  82 static int drm_add_magic(struct drm_master *master, struct drm_file *priv,
  83                          drm_magic_t magic)
  84 {
  85         struct drm_magic_entry *entry;
  86         struct drm_device *dev = master->minor->dev;
  87         DRM_DEBUG("%d\n", magic);
  88
  89         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
  90         if (!entry)
  91                 return -ENOMEM;
  92         entry->priv = priv;
  93         entry->hash_item.key = (unsigned long)magic;
  94         mutex_lock(&dev->struct_mutex);
  95         drm_ht_insert_item(&master->magiclist, &entry->hash_item);
  96         list_add_tail(&entry->head, &master->magicfree);
  97         mutex_unlock(&dev->struct_mutex);
  98
  99         return 0;
 100 }
 101
 102 /**
 103  * Remove a magic number.
 104  *
 105  * \param dev DRM device.
 106  * \param magic magic number.
 107  *
 108  * Searches and unlinks the entry in drm_device::magiclist with the magic
 109  * number hash key, while holding the drm_device::struct_mutex lock.
 110  */
 111 int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
 112 {
 113         struct drm_magic_entry *pt;
 114         struct drm_hash_item *hash;
 115         struct drm_device *dev = master->minor->dev;
 116
 117         DRM_DEBUG("%d\n", magic);
 118
 119         mutex_lock(&dev->struct_mutex);
 120         if (drm_ht_find_item(&master->magiclist, (unsigned long)magic, &hash)) {
 121                 mutex_unlock(&dev->struct_mutex);
 122                 return -EINVAL;
 123         }
 124         pt = drm_hash_entry(hash, struct drm_magic_entry, hash_item);
 125         drm_ht_remove_item(&master->magiclist, hash);
 126         list_del(&pt->head);
 127         mutex_unlock(&dev->struct_mutex);
 128
 129         kfree(pt);
 130
 131         return 0;
 132 }
 133
 134 /**
 135  * Get a unique magic number (ioctl).
 136  *
 137  * \param inode device inode.
 138  * \param file_priv DRM file private.
 139  * \param cmd command.
 140  * \param arg pointer to a resulting drm_auth structure.
 141  * \return zero on success, or a negative number on failure.
 142  *
 143  * If there is a magic number in drm_file::magic then use it, otherwise
 144  * searches an unique non-zero magic number and add it associating it with \p
 145  * file_priv.
 146  * This ioctl needs protection by the drm_global_mutex, which protects
 147  * struct drm_file::magic and struct drm_magic_entry::priv.
 148  */
 149 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 150 {
 151         static drm_magic_t sequence = 0;
 152         static DEFINE_SPINLOCK(lock);
 153         struct drm_auth *auth = data;
 154
 155         /* Find unique magic */
 156         if (file_priv->magic) {
 157                 auth->magic = file_priv->magic;
 158         } else {
 159                 do {
 160                         spin_lock(&lock);
 161                         if (!sequence)
 162                                 ++sequence;     /* reserve 0 */
 163                         auth->magic = sequence++;
 164                         spin_unlock(&lock);
 165                 } while (drm_find_file(file_priv->master, auth->magic));
 166                 file_priv->magic = auth->magic;
 167                 drm_add_magic(file_priv->master, file_priv, auth->magic);
 168         }
 169
 170         DRM_DEBUG("%u\n", auth->magic);
 171
 172         return 0;
 173 }
 174
 175 /**
 176  * Authenticate with a magic.
 177  *
 178  * \param inode device inode.
 179  * \param file_priv DRM file private.
 180  * \param cmd command.
 181  * \param arg pointer to a drm_auth structure.
 182  * \return zero if authentication successed, or a negative number otherwise.
 183  *
 184  * Checks if \p file_priv is associated with the magic number passed in \arg.
 185  * This ioctl needs protection by the drm_global_mutex, which protects
 186  * struct drm_file::magic and struct drm_magic_entry::priv.
 187  */
 188 int drm_authmagic(struct drm_device *dev, void *data,
 189                   struct drm_file *file_priv)
 190 {
 191         struct drm_auth *auth = data;
 192         struct drm_file *file;
 193
 194         DRM_DEBUG("%u\n", auth->magic);
 195         if ((file = drm_find_file(file_priv->master, auth->magic))) {
 196                 file->authenticated = 1;
 197                 drm_remove_magic(file_priv->master, auth->magic);
 198                 return 0;
 199         }
 200         return -EINVAL;
 201 }