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 #include <drm/drm_lease.h>
  35
  36 /**
  37  * DOC: master and authentication
  38  *
  39  * &struct drm_master is used to track groups of clients with open
  40  * primary/legacy device nodes. For every &struct drm_file which has had at
  41  * least once successfully became the device master (either through the
  42  * SET_MASTER IOCTL, or implicitly through opening the primary device node when
  43  * no one else is the current master that time) there exists one &drm_master.
  44  * This is noted in &drm_file.is_master. All other clients have just a pointer
  45  * to the &drm_master they are associated with.
  46  *
  47  * In addition only one &drm_master can be the current master for a &drm_device.
  48  * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
  49  * implicitly through closing/openeing the primary device node. See also
  50  * drm_is_current_master().
  51  *
  52  * Clients can authenticate against the current master (if it matches their own)
  53  * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
  54  * this allows controlled access to the device for an entire group of mutually
  55  * trusted clients.
  56  */
  57
  58 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
  59 {
  60         struct drm_auth *auth = data;
  61         int ret = 0;
  62
  63         mutex_lock(&dev->master_mutex);
  64         if (!file_priv->magic) {
  65                 ret = idr_alloc(&file_priv->master->magic_map, file_priv,
  66                                 1, 0, GFP_KERNEL);
  67                 if (ret >= 0)
  68                         file_priv->magic = ret;
  69         }
  70         auth->magic = file_priv->magic;
  71         mutex_unlock(&dev->master_mutex);
  72
  73         DRM_DEBUG("%u\n", auth->magic);
  74
  75         return ret < 0 ? ret : 0;
  76 }
  77
  78 int drm_authmagic(struct drm_device *dev, void *data,
  79                   struct drm_file *file_priv)
  80 {
  81         struct drm_auth *auth = data;
  82         struct drm_file *file;
  83
  84         DRM_DEBUG("%u\n", auth->magic);
  85
  86         mutex_lock(&dev->master_mutex);
  87         file = idr_find(&file_priv->master->magic_map, auth->magic);
  88         if (file) {
  89                 file->authenticated = 1;
  90                 idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
  91         }
  92         mutex_unlock(&dev->master_mutex);
  93
  94         return file ? 0 : -EINVAL;
  95 }
  96
  97 struct drm_master *drm_master_create(struct drm_device *dev)
  98 {
  99         struct drm_master *master;
 100
 101         master = kzalloc(sizeof(*master), GFP_KERNEL);
 102         if (!master)
 103                 return NULL;
 104
 105         kref_init(&master->refcount);
 106         spin_lock_init(&master->lock.spinlock);
 107         init_waitqueue_head(&master->lock.lock_queue);
 108         idr_init(&master->magic_map);
 109         master->dev = dev;
 110
 111         /* initialize the tree of output resource lessees */
 112         master->lessor = NULL;
 113         master->lessee_id = 0;
 114         INIT_LIST_HEAD(&master->lessees);
 115         INIT_LIST_HEAD(&master->lessee_list);
 116         idr_init(&master->leases);
 117         idr_init(&master->lessee_idr);
 118
 119         return master;
 120 }
 121
 122 static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
 123                           bool new_master)
 124 {
 125         int ret = 0;
 126
 127         dev->master = drm_master_get(fpriv->master);
 128         if (dev->driver->master_set) {
 129                 ret = dev->driver->master_set(dev, fpriv, new_master);
 130                 if (unlikely(ret != 0)) {
 131                         drm_master_put(&dev->master);
 132                 }
 133         }
 134
 135         return ret;
 136 }
 137
 138 static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 139 {
 140         struct drm_master *old_master;
 141         int ret;
 142
 143         lockdep_assert_held_once(&dev->master_mutex);
 144
 145         old_master = fpriv->master;
 146         fpriv->master = drm_master_create(dev);
 147         if (!fpriv->master) {
 148                 fpriv->master = old_master;
 149                 return -ENOMEM;
 150         }
 151
 152         if (dev->driver->master_create) {
 153                 ret = dev->driver->master_create(dev, fpriv->master);
 154                 if (ret)
 155                         goto out_err;
 156         }
 157         fpriv->is_master = 1;
 158         fpriv->authenticated = 1;
 159
 160         ret = drm_set_master(dev, fpriv, true);
 161         if (ret)
 162                 goto out_err;
 163
 164         if (old_master)
 165                 drm_master_put(&old_master);
 166
 167         return 0;
 168
 169 out_err:
 170         /* drop references and restore old master on failure */
 171         drm_master_put(&fpriv->master);
 172         fpriv->master = old_master;
 173
 174         return ret;
 175 }
 176
 177 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 178                         struct drm_file *file_priv)
 179 {
 180         int ret = 0;
 181
 182         mutex_lock(&dev->master_mutex);
 183         if (drm_is_current_master(file_priv))
 184                 goto out_unlock;
 185
 186         if (dev->master) {
 187                 ret = -EINVAL;
 188                 goto out_unlock;
 189         }
 190
 191         if (!file_priv->master) {
 192                 ret = -EINVAL;
 193                 goto out_unlock;
 194         }
 195
 196         if (!file_priv->is_master) {
 197                 ret = drm_new_set_master(dev, file_priv);
 198                 goto out_unlock;
 199         }
 200
 201         if (file_priv->master->lessor != NULL) {
 202                 DRM_DEBUG_LEASE("Attempt to set lessee %d as master\n", file_priv->master->lessee_id);
 203                 ret = -EINVAL;
 204                 goto out_unlock;
 205         }
 206
 207         ret = drm_set_master(dev, file_priv, false);
 208 out_unlock:
 209         mutex_unlock(&dev->master_mutex);
 210         return ret;
 211 }
 212
 213 static void drm_drop_master(struct drm_device *dev,
 214                             struct drm_file *fpriv)
 215 {
 216         if (dev->driver->master_drop)
 217                 dev->driver->master_drop(dev, fpriv);
 218         drm_master_put(&dev->master);
 219 }
 220
 221 int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
 222                          struct drm_file *file_priv)
 223 {
 224         int ret = -EINVAL;
 225
 226         mutex_lock(&dev->master_mutex);
 227         if (!drm_is_current_master(file_priv))
 228                 goto out_unlock;
 229
 230         if (!dev->master)
 231                 goto out_unlock;
 232
 233         if (file_priv->master->lessor != NULL) {
 234                 DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
 235                 ret = -EINVAL;
 236                 goto out_unlock;
 237         }
 238
 239         ret = 0;
 240         drm_drop_master(dev, file_priv);
 241 out_unlock:
 242         mutex_unlock(&dev->master_mutex);
 243         return ret;
 244 }
 245
 246 int drm_master_open(struct drm_file *file_priv)
 247 {
 248         struct drm_device *dev = file_priv->minor->dev;
 249         int ret = 0;
 250
 251         /* if there is no current master make this fd it, but do not create
 252          * any master object for render clients */
 253         mutex_lock(&dev->master_mutex);
 254         if (!dev->master)
 255                 ret = drm_new_set_master(dev, file_priv);
 256         else
 257                 file_priv->master = drm_master_get(dev->master);
 258         mutex_unlock(&dev->master_mutex);
 259
 260         return ret;
 261 }
 262
 263 void drm_master_release(struct drm_file *file_priv)
 264 {
 265         struct drm_device *dev = file_priv->minor->dev;
 266         struct drm_master *master = file_priv->master;
 267
 268         mutex_lock(&dev->master_mutex);
 269         if (file_priv->magic)
 270                 idr_remove(&file_priv->master->magic_map, file_priv->magic);
 271
 272         if (!drm_is_current_master(file_priv))
 273                 goto out;
 274
 275         if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
 276                 /*
 277                  * Since the master is disappearing, so is the
 278                  * possibility to lock.
 279                  */
 280                 mutex_lock(&dev->struct_mutex);
 281                 if (master->lock.hw_lock) {
 282                         if (dev->sigdata.lock == master->lock.hw_lock)
 283                                 dev->sigdata.lock = NULL;
 284                         master->lock.hw_lock = NULL;
 285                         master->lock.file_priv = NULL;
 286                         wake_up_interruptible_all(&master->lock.lock_queue);
 287                 }
 288                 mutex_unlock(&dev->struct_mutex);
 289         }
 290
 291         if (dev->master == file_priv->master)
 292                 drm_drop_master(dev, file_priv);
 293 out:
 294         if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
 295                 /* Revoke any leases held by this or lessees, but only if
 296                  * this is the "real" master
 297                  */
 298                 drm_lease_revoke(master);
 299         }
 300
 301         /* drop the master reference held by the file priv */
 302         if (file_priv->master)
 303                 drm_master_put(&file_priv->master);
 304         mutex_unlock(&dev->master_mutex);
 305 }
 306
 307 /**
 308  * drm_is_current_master - checks whether @priv is the current master
 309  * @fpriv: DRM file private
 310  *
 311  * Checks whether @fpriv is current master on its device. This decides whether a
 312  * client is allowed to run DRM_MASTER IOCTLs.
 313  *
 314  * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
 315  * - the current master is assumed to own the non-shareable display hardware.
 316  */
 317 bool drm_is_current_master(struct drm_file *fpriv)
 318 {
 319         return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
 320 }
 321 EXPORT_SYMBOL(drm_is_current_master);
 322
 323 /**
 324  * drm_master_get - reference a master pointer
 325  * @master: &struct drm_master
 326  *
 327  * Increments the reference count of @master and returns a pointer to @master.
 328  */
 329 struct drm_master *drm_master_get(struct drm_master *master)
 330 {
 331         kref_get(&master->refcount);
 332         return master;
 333 }
 334 EXPORT_SYMBOL(drm_master_get);
 335
 336 static void drm_master_destroy(struct kref *kref)
 337 {
 338         struct drm_master *master = container_of(kref, struct drm_master, refcount);
 339         struct drm_device *dev = master->dev;
 340
 341         if (drm_core_check_feature(dev, DRIVER_MODESET))
 342                 drm_lease_destroy(master);
 343
 344         if (dev->driver->master_destroy)
 345                 dev->driver->master_destroy(dev, master);
 346
 347         drm_legacy_master_rmmaps(dev, master);
 348
 349         idr_destroy(&master->magic_map);
 350         idr_destroy(&master->leases);
 351         idr_destroy(&master->lessee_idr);
 352
 353         kfree(master->unique);
 354         kfree(master);
 355 }
 356
 357 /**
 358  * drm_master_put - unreference and clear a master pointer
 359  * @master: pointer to a pointer of &struct drm_master
 360  *
 361  * This decrements the &drm_master behind @master and sets it to NULL.
 362  */
 363 void drm_master_put(struct drm_master **master)
 364 {
 365         kref_put(&(*master)->refcount, drm_master_destroy);
 366         *master = NULL;
 367 }
 368 EXPORT_SYMBOL(drm_master_put);