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         WARN_ON(fpriv->is_master);
 146         old_master = fpriv->master;
 147         fpriv->master = drm_master_create(dev);
 148         if (!fpriv->master) {
 149                 fpriv->master = old_master;
 150                 return -ENOMEM;
 151         }
 152
 153         if (dev->driver->master_create) {
 154                 ret = dev->driver->master_create(dev, fpriv->master);
 155                 if (ret)
 156                         goto out_err;
 157         }
 158         fpriv->is_master = 1;
 159         fpriv->authenticated = 1;
 160
 161         ret = drm_set_master(dev, fpriv, true);
 162         if (ret)
 163                 goto out_err;
 164
 165         if (old_master)
 166                 drm_master_put(&old_master);
 167
 168         return 0;
 169
 170 out_err:
 171         /* drop references and restore old master on failure */
 172         drm_master_put(&fpriv->master);
 173         fpriv->master = old_master;
 174         fpriv->is_master = 0;
 175
 176         return ret;
 177 }
 178
 179 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 180                         struct drm_file *file_priv)
 181 {
 182         int ret = 0;
 183
 184         mutex_lock(&dev->master_mutex);
 185         if (drm_is_current_master(file_priv))
 186                 goto out_unlock;
 187
 188         if (dev->master) {
 189                 ret = -EINVAL;
 190                 goto out_unlock;
 191         }
 192
 193         if (!file_priv->master) {
 194                 ret = -EINVAL;
 195                 goto out_unlock;
 196         }
 197
 198         if (!file_priv->is_master) {
 199                 ret = drm_new_set_master(dev, file_priv);
 200                 goto out_unlock;
 201         }
 202
 203         if (file_priv->master->lessor != NULL) {
 204                 DRM_DEBUG_LEASE("Attempt to set lessee %d as master\n", file_priv->master->lessee_id);
 205                 ret = -EINVAL;
 206                 goto out_unlock;
 207         }
 208
 209         ret = drm_set_master(dev, file_priv, false);
 210 out_unlock:
 211         mutex_unlock(&dev->master_mutex);
 212         return ret;
 213 }
 214
 215 static void drm_drop_master(struct drm_device *dev,
 216                             struct drm_file *fpriv)
 217 {
 218         if (dev->driver->master_drop)
 219                 dev->driver->master_drop(dev, fpriv);
 220         drm_master_put(&dev->master);
 221 }
 222
 223 int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
 224                          struct drm_file *file_priv)
 225 {
 226         int ret = -EINVAL;
 227
 228         mutex_lock(&dev->master_mutex);
 229         if (!drm_is_current_master(file_priv))
 230                 goto out_unlock;
 231
 232         if (!dev->master)
 233                 goto out_unlock;
 234
 235         if (file_priv->master->lessor != NULL) {
 236                 DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
 237                 ret = -EINVAL;
 238                 goto out_unlock;
 239         }
 240
 241         ret = 0;
 242         drm_drop_master(dev, file_priv);
 243 out_unlock:
 244         mutex_unlock(&dev->master_mutex);
 245         return ret;
 246 }
 247
 248 int drm_master_open(struct drm_file *file_priv)
 249 {
 250         struct drm_device *dev = file_priv->minor->dev;
 251         int ret = 0;
 252
 253         /* if there is no current master make this fd it, but do not create
 254          * any master object for render clients */
 255         mutex_lock(&dev->master_mutex);
 256         if (!dev->master)
 257                 ret = drm_new_set_master(dev, file_priv);
 258         else
 259                 file_priv->master = drm_master_get(dev->master);
 260         mutex_unlock(&dev->master_mutex);
 261
 262         return ret;
 263 }
 264
 265 void drm_master_release(struct drm_file *file_priv)
 266 {
 267         struct drm_device *dev = file_priv->minor->dev;
 268         struct drm_master *master = file_priv->master;
 269
 270         mutex_lock(&dev->master_mutex);
 271         if (file_priv->magic)
 272                 idr_remove(&file_priv->master->magic_map, file_priv->magic);
 273
 274         if (!drm_is_current_master(file_priv))
 275                 goto out;
 276
 277         if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
 278                 /*
 279                  * Since the master is disappearing, so is the
 280                  * possibility to lock.
 281                  */
 282                 mutex_lock(&dev->struct_mutex);
 283                 if (master->lock.hw_lock) {
 284                         if (dev->sigdata.lock == master->lock.hw_lock)
 285                                 dev->sigdata.lock = NULL;
 286                         master->lock.hw_lock = NULL;
 287                         master->lock.file_priv = NULL;
 288                         wake_up_interruptible_all(&master->lock.lock_queue);
 289                 }
 290                 mutex_unlock(&dev->struct_mutex);
 291         }
 292
 293         if (dev->master == file_priv->master)
 294                 drm_drop_master(dev, file_priv);
 295 out:
 296         if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
 297                 /* Revoke any leases held by this or lessees, but only if
 298                  * this is the "real" master
 299                  */
 300                 drm_lease_revoke(master);
 301         }
 302
 303         /* drop the master reference held by the file priv */
 304         if (file_priv->master)
 305                 drm_master_put(&file_priv->master);
 306         mutex_unlock(&dev->master_mutex);
 307 }
 308
 309 /**
 310  * drm_is_current_master - checks whether @priv is the current master
 311  * @fpriv: DRM file private
 312  *
 313  * Checks whether @fpriv is current master on its device. This decides whether a
 314  * client is allowed to run DRM_MASTER IOCTLs.
 315  *
 316  * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
 317  * - the current master is assumed to own the non-shareable display hardware.
 318  */
 319 bool drm_is_current_master(struct drm_file *fpriv)
 320 {
 321         return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
 322 }
 323 EXPORT_SYMBOL(drm_is_current_master);
 324
 325 /**
 326  * drm_master_get - reference a master pointer
 327  * @master: &struct drm_master
 328  *
 329  * Increments the reference count of @master and returns a pointer to @master.
 330  */
 331 struct drm_master *drm_master_get(struct drm_master *master)
 332 {
 333         kref_get(&master->refcount);
 334         return master;
 335 }
 336 EXPORT_SYMBOL(drm_master_get);
 337
 338 static void drm_master_destroy(struct kref *kref)
 339 {
 340         struct drm_master *master = container_of(kref, struct drm_master, refcount);
 341         struct drm_device *dev = master->dev;
 342
 343         if (drm_core_check_feature(dev, DRIVER_MODESET))
 344                 drm_lease_destroy(master);
 345
 346         if (dev->driver->master_destroy)
 347                 dev->driver->master_destroy(dev, master);
 348
 349         drm_legacy_master_rmmaps(dev, master);
 350
 351         idr_destroy(&master->magic_map);
 352         idr_destroy(&master->leases);
 353         idr_destroy(&master->lessee_idr);
 354
 355         kfree(master->unique);
 356         kfree(master);
 357 }
 358
 359 /**
 360  * drm_master_put - unreference and clear a master pointer
 361  * @master: pointer to a pointer of &struct drm_master
 362  *
 363  * This decrements the &drm_master behind @master and sets it to NULL.
 364  */
 365 void drm_master_put(struct drm_master **master)
 366 {
 367         kref_put(&(*master)->refcount, drm_master_destroy);
 368         *master = NULL;
 369 }
 370 EXPORT_SYMBOL(drm_master_put);