drivers/gpu/drm/drm_auth.c

   1 /*
   2  * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
   3  *
   4  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   5  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   6  * All Rights Reserved.
   7  *
   8  * Author Rickard E. (Rik) Faith <faith@valinux.com>
   9  * Author Gareth Hughes <gareth@valinux.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a
  12  * copy of this software and associated documentation files (the "Software"),
  13  * to deal in the Software without restriction, including without limitation
  14  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  15  * and/or sell copies of the Software, and to permit persons to whom the
  16  * Software is furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice (including the next
  19  * paragraph) shall be included in all copies or substantial portions of the
  20  * Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  25  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  26  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  27  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  28  * OTHER DEALINGS IN THE SOFTWARE.
  29  */
  30
  31 #include <drm/drmP.h>
  32 #include "drm_internal.h"
  33 #include "drm_legacy.h"
  34
  35 /**
  36  * DOC: master and authentication
  37  *
  38  * &struct drm_master is used to track groups of clients with open
  39  * primary/legacy device nodes. For every &struct drm_file which has had at
  40  * least once successfully became the device master (either through the
  41  * SET_MASTER IOCTL, or implicitly through opening the primary device node when
  42  * no one else is the current master that time) there exists one &drm_master.
  43  * This is noted in the is_master member of &drm_file. All other clients have
  44  * just a pointer to the &drm_master they are associated with.
  45  *
  46  * In addition only one &drm_master can be the current master for a &drm_device.
  47  * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
  48  * implicitly through closing/openeing the primary device node. See also
  49  * drm_is_current_master().
  50  *
  51  * Clients can authenticate against the current master (if it matches their own)
  52  * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
  53  * this allows controlled access to the device for an entire group of mutually
  54  * trusted clients.
  55  */
  56
  57 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
  58 {
  59         struct drm_auth *auth = data;
  60         int ret = 0;
  61
  62         mutex_lock(&dev->master_mutex);
  63         if (!file_priv->magic) {
  64                 ret = idr_alloc(&file_priv->master->magic_map, file_priv,
  65                                 1, 0, GFP_KERNEL);
  66                 if (ret >= 0)
  67                         file_priv->magic = ret;
  68         }
  69         auth->magic = file_priv->magic;
  70         mutex_unlock(&dev->master_mutex);
  71
  72         DRM_DEBUG("%u\n", auth->magic);
  73
  74         return ret < 0 ? ret : 0;
  75 }
  76
  77 int drm_authmagic(struct drm_device *dev, void *data,
  78                   struct drm_file *file_priv)
  79 {
  80         struct drm_auth *auth = data;
  81         struct drm_file *file;
  82
  83         DRM_DEBUG("%u\n", auth->magic);
  84
  85         mutex_lock(&dev->master_mutex);
  86         file = idr_find(&file_priv->master->magic_map, auth->magic);
  87         if (file) {
  88                 file->authenticated = 1;
  89                 idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
  90         }
  91         mutex_unlock(&dev->master_mutex);
  92
  93         return file ? 0 : -EINVAL;
  94 }
  95
  96 static struct drm_master *drm_master_create(struct drm_device *dev)
  97 {
  98         struct drm_master *master;
  99
 100         master = kzalloc(sizeof(*master), GFP_KERNEL);
 101         if (!master)
 102                 return NULL;
 103
 104         kref_init(&master->refcount);
 105         spin_lock_init(&master->lock.spinlock);
 106         init_waitqueue_head(&master->lock.lock_queue);
 107         idr_init(&master->magic_map);
 108         master->dev = dev;
 109
 110         return master;
 111 }
 112
 113 static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
 114                           bool new_master)
 115 {
 116         int ret = 0;
 117
 118         dev->master = drm_master_get(fpriv->master);
 119         if (dev->driver->master_set) {
 120                 ret = dev->driver->master_set(dev, fpriv, new_master);
 121                 if (unlikely(ret != 0)) {
 122                         drm_master_put(&dev->master);
 123                 }
 124         }
 125
 126         return ret;
 127 }
 128
 129 static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 130 {
 131         struct drm_master *old_master;
 132         int ret;
 133
 134         lockdep_assert_held_once(&dev->master_mutex);
 135
 136         old_master = fpriv->master;
 137         fpriv->master = drm_master_create(dev);
 138         if (!fpriv->master) {
 139                 fpriv->master = old_master;
 140                 return -ENOMEM;
 141         }
 142
 143         if (dev->driver->master_create) {
 144                 ret = dev->driver->master_create(dev, fpriv->master);
 145                 if (ret)
 146                         goto out_err;
 147         }
 148         fpriv->is_master = 1;
 149         fpriv->authenticated = 1;
 150
 151         ret = drm_set_master(dev, fpriv, true);
 152         if (ret)
 153                 goto out_err;
 154
 155         if (old_master)
 156                 drm_master_put(&old_master);
 157
 158         return 0;
 159
 160 out_err:
 161         /* drop references and restore old master on failure */
 162         drm_master_put(&fpriv->master);
 163         fpriv->master = old_master;
 164
 165         return ret;
 166 }
 167
 168 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 169                         struct drm_file *file_priv)
 170 {
 171         int ret = 0;
 172
 173         mutex_lock(&dev->master_mutex);
 174         if (drm_is_current_master(file_priv))
 175                 goto out_unlock;
 176
 177         if (dev->master) {
 178                 ret = -EINVAL;
 179                 goto out_unlock;
 180         }
 181
 182         if (!file_priv->master) {
 183                 ret = -EINVAL;
 184                 goto out_unlock;
 185         }
 186
 187         if (!file_priv->is_master) {
 188                 ret = drm_new_set_master(dev, file_priv);
 189                 goto out_unlock;
 190         }
 191
 192         ret = drm_set_master(dev, file_priv, false);
 193 out_unlock:
 194         mutex_unlock(&dev->master_mutex);
 195         return ret;
 196 }
 197
 198 static void drm_drop_master(struct drm_device *dev,
 199                             struct drm_file *fpriv)
 200 {
 201         if (dev->driver->master_drop)
 202                 dev->driver->master_drop(dev, fpriv);
 203         drm_master_put(&dev->master);
 204 }
 205
 206 int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
 207                          struct drm_file *file_priv)
 208 {
 209         int ret = -EINVAL;
 210
 211         mutex_lock(&dev->master_mutex);
 212         if (!drm_is_current_master(file_priv))
 213                 goto out_unlock;
 214
 215         if (!dev->master)
 216                 goto out_unlock;
 217
 218         ret = 0;
 219         drm_drop_master(dev, file_priv);
 220 out_unlock:
 221         mutex_unlock(&dev->master_mutex);
 222         return ret;
 223 }
 224
 225 int drm_master_open(struct drm_file *file_priv)
 226 {
 227         struct drm_device *dev = file_priv->minor->dev;
 228         int ret = 0;
 229
 230         /* if there is no current master make this fd it, but do not create
 231          * any master object for render clients */
 232         mutex_lock(&dev->master_mutex);
 233         if (!dev->master)
 234                 ret = drm_new_set_master(dev, file_priv);
 235         else
 236                 file_priv->master = drm_master_get(dev->master);
 237         mutex_unlock(&dev->master_mutex);
 238
 239         return ret;
 240 }
 241
 242 void drm_master_release(struct drm_file *file_priv)
 243 {
 244         struct drm_device *dev = file_priv->minor->dev;
 245         struct drm_master *master = file_priv->master;
 246
 247         mutex_lock(&dev->master_mutex);
 248         if (file_priv->magic)
 249                 idr_remove(&file_priv->master->magic_map, file_priv->magic);
 250
 251         if (!drm_is_current_master(file_priv))
 252                 goto out;
 253
 254         if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
 255                 /*
 256                  * Since the master is disappearing, so is the
 257                  * possibility to lock.
 258                  */
 259                 mutex_lock(&dev->struct_mutex);
 260                 if (master->lock.hw_lock) {
 261                         if (dev->sigdata.lock == master->lock.hw_lock)
 262                                 dev->sigdata.lock = NULL;
 263                         master->lock.hw_lock = NULL;
 264                         master->lock.file_priv = NULL;
 265                         wake_up_interruptible_all(&master->lock.lock_queue);
 266                 }
 267                 mutex_unlock(&dev->struct_mutex);
 268         }
 269
 270         if (dev->master == file_priv->master)
 271                 drm_drop_master(dev, file_priv);
 272 out:
 273         /* drop the master reference held by the file priv */
 274         if (file_priv->master)
 275                 drm_master_put(&file_priv->master);
 276         mutex_unlock(&dev->master_mutex);
 277 }
 278
 279 /**
 280  * drm_is_current_master - checks whether @priv is the current master
 281  * @fpriv: DRM file private
 282  *
 283  * Checks whether @fpriv is current master on its device. This decides whether a
 284  * client is allowed to run DRM_MASTER IOCTLs.
 285  *
 286  * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
 287  * - the current master is assumed to own the non-shareable display hardware.
 288  */
 289 bool drm_is_current_master(struct drm_file *fpriv)
 290 {
 291         return fpriv->is_master && fpriv->master == fpriv->minor->dev->master;
 292 }
 293 EXPORT_SYMBOL(drm_is_current_master);
 294
 295 /**
 296  * drm_master_get - reference a master pointer
 297  * @master: &struct drm_master
 298  *
 299  * Increments the reference count of @master and returns a pointer to @master.
 300  */
 301 struct drm_master *drm_master_get(struct drm_master *master)
 302 {
 303         kref_get(&master->refcount);
 304         return master;
 305 }
 306 EXPORT_SYMBOL(drm_master_get);
 307
 308 static void drm_master_destroy(struct kref *kref)
 309 {
 310         struct drm_master *master = container_of(kref, struct drm_master, refcount);
 311         struct drm_device *dev = master->dev;
 312
 313         if (dev->driver->master_destroy)
 314                 dev->driver->master_destroy(dev, master);
 315
 316         drm_legacy_master_rmmaps(dev, master);
 317
 318         idr_destroy(&master->magic_map);
 319         kfree(master->unique);
 320         kfree(master);
 321 }
 322
 323 /**
 324  * drm_master_put - unreference and clear a master pointer
 325  * @master: pointer to a pointer of &struct drm_master
 326  *
 327  * This decrements the &drm_master behind @master and sets it to NULL.
 328  */
 329 void drm_master_put(struct drm_master **master)
 330 {
 331         kref_put(&(*master)->refcount, drm_master_destroy);
 332         *master = NULL;
 333 }
 334 EXPORT_SYMBOL(drm_master_put);