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v6.2
  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 <linux/slab.h>
 32
 33#include <drm/drm_auth.h>
 34#include <drm/drm_drv.h>
 35#include <drm/drm_file.h>
 36#include <drm/drm_lease.h>
 37#include <drm/drm_print.h>
 38
 39#include "drm_internal.h"
 40#include "drm_legacy.h"
 41
 42/**
 43 * DOC: master and authentication
 44 *
 45 * &struct drm_master is used to track groups of clients with open
 46 * primary/legacy device nodes. For every &struct drm_file which has had at
 47 * least once successfully became the device master (either through the
 48 * SET_MASTER IOCTL, or implicitly through opening the primary device node when
 49 * no one else is the current master that time) there exists one &drm_master.
 50 * This is noted in &drm_file.is_master. All other clients have just a pointer
 51 * to the &drm_master they are associated with.
 52 *
 53 * In addition only one &drm_master can be the current master for a &drm_device.
 54 * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
 55 * implicitly through closing/opening the primary device node. See also
 56 * drm_is_current_master().
 57 *
 58 * Clients can authenticate against the current master (if it matches their own)
 59 * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
 60 * this allows controlled access to the device for an entire group of mutually
 61 * trusted clients.
 62 */
 63
 64static bool drm_is_current_master_locked(struct drm_file *fpriv)
 65{
 66	lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) ||
 67			    lockdep_is_held(&fpriv->minor->dev->master_mutex));
 68
 69	return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
 70}
 71
 72/**
 73 * drm_is_current_master - checks whether @priv is the current master
 74 * @fpriv: DRM file private
 75 *
 76 * Checks whether @fpriv is current master on its device. This decides whether a
 77 * client is allowed to run DRM_MASTER IOCTLs.
 78 *
 79 * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
 80 * - the current master is assumed to own the non-shareable display hardware.
 81 */
 82bool drm_is_current_master(struct drm_file *fpriv)
 83{
 84	bool ret;
 85
 86	spin_lock(&fpriv->master_lookup_lock);
 87	ret = drm_is_current_master_locked(fpriv);
 88	spin_unlock(&fpriv->master_lookup_lock);
 89
 90	return ret;
 91}
 92EXPORT_SYMBOL(drm_is_current_master);
 93
 94int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 95{
 96	struct drm_auth *auth = data;
 97	int ret = 0;
 98
 99	mutex_lock(&dev->master_mutex);
100	if (!file_priv->magic) {
101		ret = idr_alloc(&file_priv->master->magic_map, file_priv,
102				1, 0, GFP_KERNEL);
103		if (ret >= 0)
104			file_priv->magic = ret;
105	}
106	auth->magic = file_priv->magic;
107	mutex_unlock(&dev->master_mutex);
108
109	drm_dbg_core(dev, "%u\n", auth->magic);
110
111	return ret < 0 ? ret : 0;
112}
113
114int drm_authmagic(struct drm_device *dev, void *data,
115		  struct drm_file *file_priv)
116{
117	struct drm_auth *auth = data;
118	struct drm_file *file;
119
120	drm_dbg_core(dev, "%u\n", auth->magic);
121
122	mutex_lock(&dev->master_mutex);
123	file = idr_find(&file_priv->master->magic_map, auth->magic);
124	if (file) {
125		file->authenticated = 1;
126		idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
127	}
128	mutex_unlock(&dev->master_mutex);
129
130	return file ? 0 : -EINVAL;
131}
132
133struct drm_master *drm_master_create(struct drm_device *dev)
134{
135	struct drm_master *master;
136
137	master = kzalloc(sizeof(*master), GFP_KERNEL);
138	if (!master)
139		return NULL;
140
141	kref_init(&master->refcount);
142	drm_master_legacy_init(master);
143	idr_init_base(&master->magic_map, 1);
144	master->dev = dev;
145
146	/* initialize the tree of output resource lessees */
147	INIT_LIST_HEAD(&master->lessees);
148	INIT_LIST_HEAD(&master->lessee_list);
149	idr_init(&master->leases);
150	idr_init_base(&master->lessee_idr, 1);
151
152	return master;
153}
154
155static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
156			   bool new_master)
157{
158	dev->master = drm_master_get(fpriv->master);
159	if (dev->driver->master_set)
160		dev->driver->master_set(dev, fpriv, new_master);
161
162	fpriv->was_master = true;
163}
164
165static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
166{
167	struct drm_master *old_master;
168	struct drm_master *new_master;
169
170	lockdep_assert_held_once(&dev->master_mutex);
171
172	WARN_ON(fpriv->is_master);
173	old_master = fpriv->master;
174	new_master = drm_master_create(dev);
175	if (!new_master)
176		return -ENOMEM;
177	spin_lock(&fpriv->master_lookup_lock);
178	fpriv->master = new_master;
179	spin_unlock(&fpriv->master_lookup_lock);
180
181	fpriv->is_master = 1;
182	fpriv->authenticated = 1;
183
184	drm_set_master(dev, fpriv, true);
185
186	if (old_master)
187		drm_master_put(&old_master);
188
189	return 0;
190}
191
192/*
193 * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
194 * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
195 * from becoming master and/or failing to release it.
196 *
197 * At the same time, the first client (for a given VT) is _always_ master.
198 * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
199 * application as root or flip the setuid bit.
200 *
201 * If the CAP_SYS_ADMIN was missing, no other client could become master...
202 * EVER :-( Leading to a) the graphics session dying badly or b) a completely
203 * locked session.
204 *
205 *
206 * As some point systemd-logind was introduced to orchestrate and delegate
207 * master as applicable. It does so by opening the fd and passing it to users
208 * while in itself logind a) does the set/drop master per users' request and
209 * b)  * implicitly drops master on VT switch.
210 *
211 * Even though logind looks like the future, there are a few issues:
212 *  - some platforms don't have equivalent (Android, CrOS, some BSDs) so
213 * root is required _solely_ for SET/DROP MASTER.
214 *  - applications may not be updated to use it,
215 *  - any client which fails to drop master* can DoS the application using
216 * logind, to a varying degree.
217 *
218 * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
219 *
220 *
221 * Here we implement the next best thing:
222 *  - ensure the logind style of fd passing works unchanged, and
223 *  - allow a client to drop/set master, iff it is/was master at a given point
224 * in time.
225 *
226 * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
227 *  - DoS/crash the arbitrator - details would be implementation specific
228 *  - open the node, become master implicitly and cause issues
229 *
230 * As a result this fixes the following when using root-less build w/o logind
231 * - startx
232 * - weston
233 * - various compositors based on wlroots
234 */
235static int
236drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
237{
238	if (file_priv->pid == task_pid(current) && file_priv->was_master)
239		return 0;
240
241	if (!capable(CAP_SYS_ADMIN))
242		return -EACCES;
243
244	return 0;
245}
246
247int drm_setmaster_ioctl(struct drm_device *dev, void *data,
248			struct drm_file *file_priv)
249{
250	int ret;
251
252	mutex_lock(&dev->master_mutex);
253
254	ret = drm_master_check_perm(dev, file_priv);
255	if (ret)
256		goto out_unlock;
257
258	if (drm_is_current_master_locked(file_priv))
259		goto out_unlock;
260
261	if (dev->master) {
262		ret = -EBUSY;
263		goto out_unlock;
264	}
265
266	if (!file_priv->master) {
267		ret = -EINVAL;
268		goto out_unlock;
269	}
270
271	if (!file_priv->is_master) {
272		ret = drm_new_set_master(dev, file_priv);
273		goto out_unlock;
274	}
275
276	if (file_priv->master->lessor != NULL) {
277		drm_dbg_lease(dev,
278			      "Attempt to set lessee %d as master\n",
279			      file_priv->master->lessee_id);
280		ret = -EINVAL;
281		goto out_unlock;
282	}
283
284	drm_set_master(dev, file_priv, false);
285out_unlock:
286	mutex_unlock(&dev->master_mutex);
287	return ret;
288}
289
290static void drm_drop_master(struct drm_device *dev,
291			    struct drm_file *fpriv)
292{
293	if (dev->driver->master_drop)
294		dev->driver->master_drop(dev, fpriv);
295	drm_master_put(&dev->master);
296}
297
298int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
299			 struct drm_file *file_priv)
300{
301	int ret;
302
303	mutex_lock(&dev->master_mutex);
304
305	ret = drm_master_check_perm(dev, file_priv);
306	if (ret)
307		goto out_unlock;
308
309	if (!drm_is_current_master_locked(file_priv)) {
310		ret = -EINVAL;
311		goto out_unlock;
312	}
313
314	if (!dev->master) {
315		ret = -EINVAL;
316		goto out_unlock;
317	}
318
319	if (file_priv->master->lessor != NULL) {
320		drm_dbg_lease(dev,
321			      "Attempt to drop lessee %d as master\n",
322			      file_priv->master->lessee_id);
323		ret = -EINVAL;
324		goto out_unlock;
325	}
326
327	drm_drop_master(dev, file_priv);
328out_unlock:
329	mutex_unlock(&dev->master_mutex);
330	return ret;
331}
332
333int drm_master_open(struct drm_file *file_priv)
334{
335	struct drm_device *dev = file_priv->minor->dev;
336	int ret = 0;
337
338	/* if there is no current master make this fd it, but do not create
339	 * any master object for render clients
340	 */
341	mutex_lock(&dev->master_mutex);
342	if (!dev->master) {
343		ret = drm_new_set_master(dev, file_priv);
344	} else {
345		spin_lock(&file_priv->master_lookup_lock);
346		file_priv->master = drm_master_get(dev->master);
347		spin_unlock(&file_priv->master_lookup_lock);
348	}
349	mutex_unlock(&dev->master_mutex);
350
351	return ret;
352}
353
354void drm_master_release(struct drm_file *file_priv)
355{
356	struct drm_device *dev = file_priv->minor->dev;
357	struct drm_master *master;
358
359	mutex_lock(&dev->master_mutex);
360	master = file_priv->master;
361	if (file_priv->magic)
362		idr_remove(&file_priv->master->magic_map, file_priv->magic);
363
364	if (!drm_is_current_master_locked(file_priv))
365		goto out;
366
367	drm_legacy_lock_master_cleanup(dev, master);
368
369	if (dev->master == file_priv->master)
370		drm_drop_master(dev, file_priv);
371out:
372	if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
373		/* Revoke any leases held by this or lessees, but only if
374		 * this is the "real" master
375		 */
376		drm_lease_revoke(master);
377	}
378
379	/* drop the master reference held by the file priv */
380	if (file_priv->master)
381		drm_master_put(&file_priv->master);
382	mutex_unlock(&dev->master_mutex);
383}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
384
385/**
386 * drm_master_get - reference a master pointer
387 * @master: &struct drm_master
388 *
389 * Increments the reference count of @master and returns a pointer to @master.
390 */
391struct drm_master *drm_master_get(struct drm_master *master)
392{
393	kref_get(&master->refcount);
394	return master;
395}
396EXPORT_SYMBOL(drm_master_get);
397
398/**
399 * drm_file_get_master - reference &drm_file.master of @file_priv
400 * @file_priv: DRM file private
401 *
402 * Increments the reference count of @file_priv's &drm_file.master and returns
403 * the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL.
404 *
405 * Master pointers returned from this function should be unreferenced using
406 * drm_master_put().
407 */
408struct drm_master *drm_file_get_master(struct drm_file *file_priv)
409{
410	struct drm_master *master = NULL;
411
412	spin_lock(&file_priv->master_lookup_lock);
413	if (!file_priv->master)
414		goto unlock;
415	master = drm_master_get(file_priv->master);
416
417unlock:
418	spin_unlock(&file_priv->master_lookup_lock);
419	return master;
420}
421EXPORT_SYMBOL(drm_file_get_master);
422
423static void drm_master_destroy(struct kref *kref)
424{
425	struct drm_master *master = container_of(kref, struct drm_master, refcount);
426	struct drm_device *dev = master->dev;
427
428	if (drm_core_check_feature(dev, DRIVER_MODESET))
429		drm_lease_destroy(master);
430
431	drm_legacy_master_rmmaps(dev, master);
432
433	idr_destroy(&master->magic_map);
434	idr_destroy(&master->leases);
435	idr_destroy(&master->lessee_idr);
436
437	kfree(master->unique);
438	kfree(master);
439}
440
441/**
442 * drm_master_put - unreference and clear a master pointer
443 * @master: pointer to a pointer of &struct drm_master
444 *
445 * This decrements the &drm_master behind @master and sets it to NULL.
446 */
447void drm_master_put(struct drm_master **master)
448{
449	kref_put(&(*master)->refcount, drm_master_destroy);
450	*master = NULL;
451}
452EXPORT_SYMBOL(drm_master_put);
453
454/* Used by drm_client and drm_fb_helper */
455bool drm_master_internal_acquire(struct drm_device *dev)
456{
457	mutex_lock(&dev->master_mutex);
458	if (dev->master) {
459		mutex_unlock(&dev->master_mutex);
460		return false;
461	}
462
463	return true;
464}
465EXPORT_SYMBOL(drm_master_internal_acquire);
466
467/* Used by drm_client and drm_fb_helper */
468void drm_master_internal_release(struct drm_device *dev)
469{
470	mutex_unlock(&dev->master_mutex);
471}
472EXPORT_SYMBOL(drm_master_internal_release);
v5.14.15
  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 <linux/slab.h>
 32
 33#include <drm/drm_auth.h>
 34#include <drm/drm_drv.h>
 35#include <drm/drm_file.h>
 36#include <drm/drm_lease.h>
 37#include <drm/drm_print.h>
 38
 39#include "drm_internal.h"
 40#include "drm_legacy.h"
 41
 42/**
 43 * DOC: master and authentication
 44 *
 45 * &struct drm_master is used to track groups of clients with open
 46 * primary/legacy device nodes. For every &struct drm_file which has had at
 47 * least once successfully became the device master (either through the
 48 * SET_MASTER IOCTL, or implicitly through opening the primary device node when
 49 * no one else is the current master that time) there exists one &drm_master.
 50 * This is noted in &drm_file.is_master. All other clients have just a pointer
 51 * to the &drm_master they are associated with.
 52 *
 53 * In addition only one &drm_master can be the current master for a &drm_device.
 54 * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
 55 * implicitly through closing/openeing the primary device node. See also
 56 * drm_is_current_master().
 57 *
 58 * Clients can authenticate against the current master (if it matches their own)
 59 * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
 60 * this allows controlled access to the device for an entire group of mutually
 61 * trusted clients.
 62 */
 63
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 64int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 65{
 66	struct drm_auth *auth = data;
 67	int ret = 0;
 68
 69	mutex_lock(&dev->master_mutex);
 70	if (!file_priv->magic) {
 71		ret = idr_alloc(&file_priv->master->magic_map, file_priv,
 72				1, 0, GFP_KERNEL);
 73		if (ret >= 0)
 74			file_priv->magic = ret;
 75	}
 76	auth->magic = file_priv->magic;
 77	mutex_unlock(&dev->master_mutex);
 78
 79	DRM_DEBUG("%u\n", auth->magic);
 80
 81	return ret < 0 ? ret : 0;
 82}
 83
 84int drm_authmagic(struct drm_device *dev, void *data,
 85		  struct drm_file *file_priv)
 86{
 87	struct drm_auth *auth = data;
 88	struct drm_file *file;
 89
 90	DRM_DEBUG("%u\n", auth->magic);
 91
 92	mutex_lock(&dev->master_mutex);
 93	file = idr_find(&file_priv->master->magic_map, auth->magic);
 94	if (file) {
 95		file->authenticated = 1;
 96		idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
 97	}
 98	mutex_unlock(&dev->master_mutex);
 99
100	return file ? 0 : -EINVAL;
101}
102
103struct drm_master *drm_master_create(struct drm_device *dev)
104{
105	struct drm_master *master;
106
107	master = kzalloc(sizeof(*master), GFP_KERNEL);
108	if (!master)
109		return NULL;
110
111	kref_init(&master->refcount);
112	drm_master_legacy_init(master);
113	idr_init(&master->magic_map);
114	master->dev = dev;
115
116	/* initialize the tree of output resource lessees */
117	INIT_LIST_HEAD(&master->lessees);
118	INIT_LIST_HEAD(&master->lessee_list);
119	idr_init(&master->leases);
120	idr_init(&master->lessee_idr);
121
122	return master;
123}
124
125static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
126			   bool new_master)
127{
128	dev->master = drm_master_get(fpriv->master);
129	if (dev->driver->master_set)
130		dev->driver->master_set(dev, fpriv, new_master);
131
132	fpriv->was_master = true;
133}
134
135static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
136{
137	struct drm_master *old_master;
138	struct drm_master *new_master;
139
140	lockdep_assert_held_once(&dev->master_mutex);
141
142	WARN_ON(fpriv->is_master);
143	old_master = fpriv->master;
144	new_master = drm_master_create(dev);
145	if (!new_master)
146		return -ENOMEM;
147	spin_lock(&fpriv->master_lookup_lock);
148	fpriv->master = new_master;
149	spin_unlock(&fpriv->master_lookup_lock);
150
151	fpriv->is_master = 1;
152	fpriv->authenticated = 1;
153
154	drm_set_master(dev, fpriv, true);
155
156	if (old_master)
157		drm_master_put(&old_master);
158
159	return 0;
160}
161
162/*
163 * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
164 * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
165 * from becoming master and/or failing to release it.
166 *
167 * At the same time, the first client (for a given VT) is _always_ master.
168 * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
169 * application as root or flip the setuid bit.
170 *
171 * If the CAP_SYS_ADMIN was missing, no other client could become master...
172 * EVER :-( Leading to a) the graphics session dying badly or b) a completely
173 * locked session.
174 *
175 *
176 * As some point systemd-logind was introduced to orchestrate and delegate
177 * master as applicable. It does so by opening the fd and passing it to users
178 * while in itself logind a) does the set/drop master per users' request and
179 * b)  * implicitly drops master on VT switch.
180 *
181 * Even though logind looks like the future, there are a few issues:
182 *  - some platforms don't have equivalent (Android, CrOS, some BSDs) so
183 * root is required _solely_ for SET/DROP MASTER.
184 *  - applications may not be updated to use it,
185 *  - any client which fails to drop master* can DoS the application using
186 * logind, to a varying degree.
187 *
188 * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
189 *
190 *
191 * Here we implement the next best thing:
192 *  - ensure the logind style of fd passing works unchanged, and
193 *  - allow a client to drop/set master, iff it is/was master at a given point
194 * in time.
195 *
196 * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
197 *  - DoS/crash the arbitrator - details would be implementation specific
198 *  - open the node, become master implicitly and cause issues
199 *
200 * As a result this fixes the following when using root-less build w/o logind
201 * - startx
202 * - weston
203 * - various compositors based on wlroots
204 */
205static int
206drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
207{
208	if (file_priv->pid == task_pid(current) && file_priv->was_master)
209		return 0;
210
211	if (!capable(CAP_SYS_ADMIN))
212		return -EACCES;
213
214	return 0;
215}
216
217int drm_setmaster_ioctl(struct drm_device *dev, void *data,
218			struct drm_file *file_priv)
219{
220	int ret;
221
222	mutex_lock(&dev->master_mutex);
223
224	ret = drm_master_check_perm(dev, file_priv);
225	if (ret)
226		goto out_unlock;
227
228	if (drm_is_current_master(file_priv))
229		goto out_unlock;
230
231	if (dev->master) {
232		ret = -EBUSY;
233		goto out_unlock;
234	}
235
236	if (!file_priv->master) {
237		ret = -EINVAL;
238		goto out_unlock;
239	}
240
241	if (!file_priv->is_master) {
242		ret = drm_new_set_master(dev, file_priv);
243		goto out_unlock;
244	}
245
246	if (file_priv->master->lessor != NULL) {
247		DRM_DEBUG_LEASE("Attempt to set lessee %d as master\n", file_priv->master->lessee_id);
 
 
248		ret = -EINVAL;
249		goto out_unlock;
250	}
251
252	drm_set_master(dev, file_priv, false);
253out_unlock:
254	mutex_unlock(&dev->master_mutex);
255	return ret;
256}
257
258static void drm_drop_master(struct drm_device *dev,
259			    struct drm_file *fpriv)
260{
261	if (dev->driver->master_drop)
262		dev->driver->master_drop(dev, fpriv);
263	drm_master_put(&dev->master);
264}
265
266int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
267			 struct drm_file *file_priv)
268{
269	int ret;
270
271	mutex_lock(&dev->master_mutex);
272
273	ret = drm_master_check_perm(dev, file_priv);
274	if (ret)
275		goto out_unlock;
276
277	if (!drm_is_current_master(file_priv)) {
278		ret = -EINVAL;
279		goto out_unlock;
280	}
281
282	if (!dev->master) {
283		ret = -EINVAL;
284		goto out_unlock;
285	}
286
287	if (file_priv->master->lessor != NULL) {
288		DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
 
 
289		ret = -EINVAL;
290		goto out_unlock;
291	}
292
293	drm_drop_master(dev, file_priv);
294out_unlock:
295	mutex_unlock(&dev->master_mutex);
296	return ret;
297}
298
299int drm_master_open(struct drm_file *file_priv)
300{
301	struct drm_device *dev = file_priv->minor->dev;
302	int ret = 0;
303
304	/* if there is no current master make this fd it, but do not create
305	 * any master object for render clients
306	 */
307	mutex_lock(&dev->master_mutex);
308	if (!dev->master) {
309		ret = drm_new_set_master(dev, file_priv);
310	} else {
311		spin_lock(&file_priv->master_lookup_lock);
312		file_priv->master = drm_master_get(dev->master);
313		spin_unlock(&file_priv->master_lookup_lock);
314	}
315	mutex_unlock(&dev->master_mutex);
316
317	return ret;
318}
319
320void drm_master_release(struct drm_file *file_priv)
321{
322	struct drm_device *dev = file_priv->minor->dev;
323	struct drm_master *master;
324
325	mutex_lock(&dev->master_mutex);
326	master = file_priv->master;
327	if (file_priv->magic)
328		idr_remove(&file_priv->master->magic_map, file_priv->magic);
329
330	if (!drm_is_current_master(file_priv))
331		goto out;
332
333	drm_legacy_lock_master_cleanup(dev, master);
334
335	if (dev->master == file_priv->master)
336		drm_drop_master(dev, file_priv);
337out:
338	if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
339		/* Revoke any leases held by this or lessees, but only if
340		 * this is the "real" master
341		 */
342		drm_lease_revoke(master);
343	}
344
345	/* drop the master reference held by the file priv */
346	if (file_priv->master)
347		drm_master_put(&file_priv->master);
348	mutex_unlock(&dev->master_mutex);
349}
350
351/**
352 * drm_is_current_master - checks whether @priv is the current master
353 * @fpriv: DRM file private
354 *
355 * Checks whether @fpriv is current master on its device. This decides whether a
356 * client is allowed to run DRM_MASTER IOCTLs.
357 *
358 * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
359 * - the current master is assumed to own the non-shareable display hardware.
360 */
361bool drm_is_current_master(struct drm_file *fpriv)
362{
363	return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
364}
365EXPORT_SYMBOL(drm_is_current_master);
366
367/**
368 * drm_master_get - reference a master pointer
369 * @master: &struct drm_master
370 *
371 * Increments the reference count of @master and returns a pointer to @master.
372 */
373struct drm_master *drm_master_get(struct drm_master *master)
374{
375	kref_get(&master->refcount);
376	return master;
377}
378EXPORT_SYMBOL(drm_master_get);
379
380/**
381 * drm_file_get_master - reference &drm_file.master of @file_priv
382 * @file_priv: DRM file private
383 *
384 * Increments the reference count of @file_priv's &drm_file.master and returns
385 * the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL.
386 *
387 * Master pointers returned from this function should be unreferenced using
388 * drm_master_put().
389 */
390struct drm_master *drm_file_get_master(struct drm_file *file_priv)
391{
392	struct drm_master *master = NULL;
393
394	spin_lock(&file_priv->master_lookup_lock);
395	if (!file_priv->master)
396		goto unlock;
397	master = drm_master_get(file_priv->master);
398
399unlock:
400	spin_unlock(&file_priv->master_lookup_lock);
401	return master;
402}
403EXPORT_SYMBOL(drm_file_get_master);
404
405static void drm_master_destroy(struct kref *kref)
406{
407	struct drm_master *master = container_of(kref, struct drm_master, refcount);
408	struct drm_device *dev = master->dev;
409
410	if (drm_core_check_feature(dev, DRIVER_MODESET))
411		drm_lease_destroy(master);
412
413	drm_legacy_master_rmmaps(dev, master);
414
415	idr_destroy(&master->magic_map);
416	idr_destroy(&master->leases);
417	idr_destroy(&master->lessee_idr);
418
419	kfree(master->unique);
420	kfree(master);
421}
422
423/**
424 * drm_master_put - unreference and clear a master pointer
425 * @master: pointer to a pointer of &struct drm_master
426 *
427 * This decrements the &drm_master behind @master and sets it to NULL.
428 */
429void drm_master_put(struct drm_master **master)
430{
431	kref_put(&(*master)->refcount, drm_master_destroy);
432	*master = NULL;
433}
434EXPORT_SYMBOL(drm_master_put);
435
436/* Used by drm_client and drm_fb_helper */
437bool drm_master_internal_acquire(struct drm_device *dev)
438{
439	mutex_lock(&dev->master_mutex);
440	if (dev->master) {
441		mutex_unlock(&dev->master_mutex);
442		return false;
443	}
444
445	return true;
446}
447EXPORT_SYMBOL(drm_master_internal_acquire);
448
449/* Used by drm_client and drm_fb_helper */
450void drm_master_internal_release(struct drm_device *dev)
451{
452	mutex_unlock(&dev->master_mutex);
453}
454EXPORT_SYMBOL(drm_master_internal_release);