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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright © 2017 Keith Packard <[email protected]>
4 */
5#include <linux/file.h>
6#include <linux/uaccess.h>
7
8#include <drm/drm_auth.h>
9#include <drm/drm_crtc.h>
10#include <drm/drm_drv.h>
11#include <drm/drm_file.h>
12#include <drm/drm_lease.h>
13#include <drm/drm_print.h>
14
15#include "drm_crtc_internal.h"
16#include "drm_internal.h"
17
18/**
19 * DOC: drm leasing
20 *
21 * DRM leases provide information about whether a DRM master may control a DRM
22 * mode setting object. This enables the creation of multiple DRM masters that
23 * manage subsets of display resources.
24 *
25 * The original DRM master of a device 'owns' the available drm resources. It
26 * may create additional DRM masters and 'lease' resources which it controls
27 * to the new DRM master. This gives the new DRM master control over the
28 * leased resources until the owner revokes the lease, or the new DRM master
29 * is closed. Some helpful terminology:
30 *
31 * - An 'owner' is a &struct drm_master that is not leasing objects from
32 * another &struct drm_master, and hence 'owns' the objects. The owner can be
33 * identified as the &struct drm_master for which &drm_master.lessor is NULL.
34 *
35 * - A 'lessor' is a &struct drm_master which is leasing objects to one or more
36 * other &struct drm_master. Currently, lessees are not allowed to
37 * create sub-leases, hence the lessor is the same as the owner.
38 *
39 * - A 'lessee' is a &struct drm_master which is leasing objects from some
40 * other &struct drm_master. Each lessee only leases resources from a single
41 * lessor recorded in &drm_master.lessor, and holds the set of objects that
42 * it is leasing in &drm_master.leases.
43 *
44 * - A 'lease' is a contract between the lessor and lessee that identifies
45 * which resources may be controlled by the lessee. All of the resources
46 * that are leased must be owned by or leased to the lessor, and lessors are
47 * not permitted to lease the same object to multiple lessees.
48 *
49 * The set of objects any &struct drm_master 'controls' is limited to the set
50 * of objects it leases (for lessees) or all objects (for owners).
51 *
52 * Objects not controlled by a &struct drm_master cannot be modified through
53 * the various state manipulating ioctls, and any state reported back to user
54 * space will be edited to make them appear idle and/or unusable. For
55 * instance, connectors always report 'disconnected', while encoders
56 * report no possible crtcs or clones.
57 *
58 * Since each lessee may lease objects from a single lessor, display resource
59 * leases form a tree of &struct drm_master. As lessees are currently not
60 * allowed to create sub-leases, the tree depth is limited to 1. All of
61 * these get activated simultaneously when the top level device owner changes
62 * through the SETMASTER or DROPMASTER IOCTL, so &drm_device.master points to
63 * the owner at the top of the lease tree (i.e. the &struct drm_master for which
64 * &drm_master.lessor is NULL). The full list of lessees that are leasing
65 * objects from the owner can be searched via the owner's
66 * &drm_master.lessee_idr.
67 */
68
69#define drm_for_each_lessee(lessee, lessor) \
70 list_for_each_entry((lessee), &(lessor)->lessees, lessee_list)
71
72static uint64_t drm_lease_idr_object;
73
74struct drm_master *drm_lease_owner(struct drm_master *master)
75{
76 while (master->lessor != NULL)
77 master = master->lessor;
78 return master;
79}
80
81static struct drm_master*
82_drm_find_lessee(struct drm_master *master, int lessee_id)
83{
84 lockdep_assert_held(&master->dev->mode_config.idr_mutex);
85 return idr_find(&drm_lease_owner(master)->lessee_idr, lessee_id);
86}
87
88static int _drm_lease_held_master(struct drm_master *master, int id)
89{
90 lockdep_assert_held(&master->dev->mode_config.idr_mutex);
91 if (master->lessor)
92 return idr_find(&master->leases, id) != NULL;
93 return true;
94}
95
96/* Checks if the given object has been leased to some lessee of drm_master */
97static bool _drm_has_leased(struct drm_master *master, int id)
98{
99 struct drm_master *lessee;
100
101 lockdep_assert_held(&master->dev->mode_config.idr_mutex);
102 drm_for_each_lessee(lessee, master)
103 if (_drm_lease_held_master(lessee, id))
104 return true;
105 return false;
106}
107
108/* Called with idr_mutex held */
109bool _drm_lease_held(struct drm_file *file_priv, int id)
110{
111 bool ret;
112 struct drm_master *master;
113
114 if (!file_priv)
115 return true;
116
117 master = drm_file_get_master(file_priv);
118 if (!master)
119 return true;
120 ret = _drm_lease_held_master(master, id);
121 drm_master_put(&master);
122
123 return ret;
124}
125
126bool drm_lease_held(struct drm_file *file_priv, int id)
127{
128 struct drm_master *master;
129 bool ret;
130
131 if (!file_priv)
132 return true;
133
134 master = drm_file_get_master(file_priv);
135 if (!master)
136 return true;
137 if (!master->lessor) {
138 ret = true;
139 goto out;
140 }
141 mutex_lock(&master->dev->mode_config.idr_mutex);
142 ret = _drm_lease_held_master(master, id);
143 mutex_unlock(&master->dev->mode_config.idr_mutex);
144
145out:
146 drm_master_put(&master);
147 return ret;
148}
149
150/*
151 * Given a bitmask of crtcs to check, reconstructs a crtc mask based on the
152 * crtcs which are visible through the specified file.
153 */
154uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
155{
156 struct drm_master *master;
157 struct drm_device *dev;
158 struct drm_crtc *crtc;
159 int count_in, count_out;
160 uint32_t crtcs_out = 0;
161
162 if (!file_priv)
163 return crtcs_in;
164
165 master = drm_file_get_master(file_priv);
166 if (!master)
167 return crtcs_in;
168 if (!master->lessor) {
169 crtcs_out = crtcs_in;
170 goto out;
171 }
172 dev = master->dev;
173
174 count_in = count_out = 0;
175 mutex_lock(&master->dev->mode_config.idr_mutex);
176 list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
177 if (_drm_lease_held_master(master, crtc->base.id)) {
178 uint32_t mask_in = 1ul << count_in;
179
180 if ((crtcs_in & mask_in) != 0) {
181 uint32_t mask_out = 1ul << count_out;
182
183 crtcs_out |= mask_out;
184 }
185 count_out++;
186 }
187 count_in++;
188 }
189 mutex_unlock(&master->dev->mode_config.idr_mutex);
190
191out:
192 drm_master_put(&master);
193 return crtcs_out;
194}
195
196/*
197 * Uses drm_master_create to allocate a new drm_master, then checks to
198 * make sure all of the desired objects can be leased, atomically
199 * leasing them to the new drmmaster.
200 *
201 * ERR_PTR(-EACCES) some other master holds the title to any object
202 * ERR_PTR(-ENOENT) some object is not a valid DRM object for this device
203 * ERR_PTR(-EBUSY) some other lessee holds title to this object
204 * ERR_PTR(-EEXIST) same object specified more than once in the provided list
205 * ERR_PTR(-ENOMEM) allocation failed
206 */
207static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr *leases)
208{
209 struct drm_device *dev = lessor->dev;
210 int error;
211 struct drm_master *lessee;
212 int object;
213 int id;
214 void *entry;
215
216 drm_dbg_lease(dev, "lessor %d\n", lessor->lessee_id);
217
218 lessee = drm_master_create(lessor->dev);
219 if (!lessee) {
220 drm_dbg_lease(dev, "drm_master_create failed\n");
221 return ERR_PTR(-ENOMEM);
222 }
223
224 mutex_lock(&dev->mode_config.idr_mutex);
225
226 idr_for_each_entry(leases, entry, object) {
227 error = 0;
228 if (!idr_find(&dev->mode_config.object_idr, object))
229 error = -ENOENT;
230 else if (_drm_has_leased(lessor, object))
231 error = -EBUSY;
232
233 if (error != 0) {
234 drm_dbg_lease(dev, "object %d failed %d\n", object, error);
235 goto out_lessee;
236 }
237 }
238
239 /* Insert the new lessee into the tree */
240 id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
241 if (id < 0) {
242 error = id;
243 goto out_lessee;
244 }
245
246 lessee->lessee_id = id;
247 lessee->lessor = drm_master_get(lessor);
248 list_add_tail(&lessee->lessee_list, &lessor->lessees);
249
250 /* Move the leases over */
251 lessee->leases = *leases;
252 drm_dbg_lease(dev, "new lessee %d %p, lessor %d %p\n",
253 lessee->lessee_id, lessee, lessor->lessee_id, lessor);
254
255 mutex_unlock(&dev->mode_config.idr_mutex);
256 return lessee;
257
258out_lessee:
259 mutex_unlock(&dev->mode_config.idr_mutex);
260
261 drm_master_put(&lessee);
262
263 return ERR_PTR(error);
264}
265
266void drm_lease_destroy(struct drm_master *master)
267{
268 struct drm_device *dev = master->dev;
269
270 mutex_lock(&dev->mode_config.idr_mutex);
271
272 drm_dbg_lease(dev, "drm_lease_destroy %d\n", master->lessee_id);
273
274 /* This master is referenced by all lessees, hence it cannot be destroyed
275 * until all of them have been
276 */
277 WARN_ON(!list_empty(&master->lessees));
278
279 /* Remove this master from the lessee idr in the owner */
280 if (master->lessee_id != 0) {
281 drm_dbg_lease(dev, "remove master %d from device list of lessees\n",
282 master->lessee_id);
283 idr_remove(&(drm_lease_owner(master)->lessee_idr), master->lessee_id);
284 }
285
286 /* Remove this master from any lessee list it may be on */
287 list_del(&master->lessee_list);
288
289 mutex_unlock(&dev->mode_config.idr_mutex);
290
291 if (master->lessor) {
292 /* Tell the master to check the lessee list */
293 drm_sysfs_lease_event(dev);
294 drm_master_put(&master->lessor);
295 }
296
297 drm_dbg_lease(dev, "drm_lease_destroy done %d\n", master->lessee_id);
298}
299
300static void _drm_lease_revoke(struct drm_master *top)
301{
302 int object;
303 void *entry;
304 struct drm_master *master = top;
305
306 lockdep_assert_held(&top->dev->mode_config.idr_mutex);
307
308 /*
309 * Walk the tree starting at 'top' emptying all leases. Because
310 * the tree is fully connected, we can do this without recursing
311 */
312 for (;;) {
313 drm_dbg_lease(master->dev, "revoke leases for %p %d\n",
314 master, master->lessee_id);
315
316 /* Evacuate the lease */
317 idr_for_each_entry(&master->leases, entry, object)
318 idr_remove(&master->leases, object);
319
320 /* Depth-first list walk */
321
322 /* Down */
323 if (!list_empty(&master->lessees)) {
324 master = list_first_entry(&master->lessees, struct drm_master, lessee_list);
325 } else {
326 /* Up */
327 while (master != top && master == list_last_entry(&master->lessor->lessees, struct drm_master, lessee_list))
328 master = master->lessor;
329
330 if (master == top)
331 break;
332
333 /* Over */
334 master = list_next_entry(master, lessee_list);
335 }
336 }
337}
338
339void drm_lease_revoke(struct drm_master *top)
340{
341 mutex_lock(&top->dev->mode_config.idr_mutex);
342 _drm_lease_revoke(top);
343 mutex_unlock(&top->dev->mode_config.idr_mutex);
344}
345
346static int validate_lease(struct drm_device *dev,
347 int object_count,
348 struct drm_mode_object **objects,
349 bool universal_planes)
350{
351 int o;
352 int has_crtc = -1;
353 int has_connector = -1;
354 int has_plane = -1;
355
356 /* we want to confirm that there is at least one crtc, plane
357 connector object. */
358
359 for (o = 0; o < object_count; o++) {
360 if (objects[o]->type == DRM_MODE_OBJECT_CRTC && has_crtc == -1) {
361 has_crtc = o;
362 }
363 if (objects[o]->type == DRM_MODE_OBJECT_CONNECTOR && has_connector == -1)
364 has_connector = o;
365
366 if (universal_planes) {
367 if (objects[o]->type == DRM_MODE_OBJECT_PLANE && has_plane == -1)
368 has_plane = o;
369 }
370 }
371 if (has_crtc == -1 || has_connector == -1)
372 return -EINVAL;
373 if (universal_planes && has_plane == -1)
374 return -EINVAL;
375 return 0;
376}
377
378static int fill_object_idr(struct drm_device *dev,
379 struct drm_file *lessor_priv,
380 struct idr *leases,
381 int object_count,
382 u32 *object_ids)
383{
384 struct drm_mode_object **objects;
385 u32 o;
386 int ret;
387 bool universal_planes = READ_ONCE(lessor_priv->universal_planes);
388
389 objects = kzalloc_objs(struct drm_mode_object *, object_count);
390 if (!objects)
391 return -ENOMEM;
392
393 /* step one - get references to all the mode objects
394 and check for validity. */
395 for (o = 0; o < object_count; o++) {
396 objects[o] = drm_mode_object_find(dev, lessor_priv,
397 object_ids[o],
398 DRM_MODE_OBJECT_ANY);
399 if (!objects[o]) {
400 ret = -ENOENT;
401 goto out_free_objects;
402 }
403
404 if (!drm_mode_object_lease_required(objects[o]->type)) {
405 DRM_DEBUG_KMS("invalid object for lease\n");
406 ret = -EINVAL;
407 goto out_free_objects;
408 }
409 }
410
411 ret = validate_lease(dev, object_count, objects, universal_planes);
412 if (ret) {
413 drm_dbg_lease(dev, "lease validation failed\n");
414 goto out_free_objects;
415 }
416
417 /* add their IDs to the lease request - taking into account
418 universal planes */
419 for (o = 0; o < object_count; o++) {
420 struct drm_mode_object *obj = objects[o];
421 u32 object_id = objects[o]->id;
422
423 drm_dbg_lease(dev, "Adding object %d to lease\n", object_id);
424
425 /*
426 * We're using an IDR to hold the set of leased
427 * objects, but we don't need to point at the object's
428 * data structure from the lease as the main object_idr
429 * will be used to actually find that. Instead, all we
430 * really want is a 'leased/not-leased' result, for
431 * which any non-NULL pointer will work fine.
432 */
433 ret = idr_alloc(leases, &drm_lease_idr_object , object_id, object_id + 1, GFP_KERNEL);
434 if (ret < 0) {
435 drm_dbg_lease(dev, "Object %d cannot be inserted into leases (%d)\n",
436 object_id, ret);
437 goto out_free_objects;
438 }
439 if (obj->type == DRM_MODE_OBJECT_CRTC && !universal_planes) {
440 struct drm_crtc *crtc = obj_to_crtc(obj);
441
442 ret = idr_alloc(leases, &drm_lease_idr_object, crtc->primary->base.id, crtc->primary->base.id + 1, GFP_KERNEL);
443 if (ret < 0) {
444 drm_dbg_lease(dev, "Object primary plane %d cannot be inserted into leases (%d)\n",
445 object_id, ret);
446 goto out_free_objects;
447 }
448 if (crtc->cursor) {
449 ret = idr_alloc(leases, &drm_lease_idr_object, crtc->cursor->base.id, crtc->cursor->base.id + 1, GFP_KERNEL);
450 if (ret < 0) {
451 drm_dbg_lease(dev, "Object cursor plane %d cannot be inserted into leases (%d)\n",
452 object_id, ret);
453 goto out_free_objects;
454 }
455 }
456 }
457 }
458
459 ret = 0;
460out_free_objects:
461 for (o = 0; o < object_count; o++) {
462 if (objects[o])
463 drm_mode_object_put(objects[o]);
464 }
465 kfree(objects);
466 return ret;
467}
468
469/*
470 * The master associated with the specified file will have a lease
471 * created containing the objects specified in the ioctl structure.
472 * A file descriptor will be allocated for that and returned to the
473 * application.
474 */
475int drm_mode_create_lease_ioctl(struct drm_device *dev,
476 void *data, struct drm_file *lessor_priv)
477{
478 struct drm_mode_create_lease *cl = data;
479 size_t object_count;
480 int ret = 0;
481 struct idr leases;
482 struct drm_master *lessor;
483 struct drm_master *lessee = NULL;
484 struct file *lessee_file = NULL;
485 struct file *lessor_file = lessor_priv->filp;
486 struct drm_file *lessee_priv;
487 int fd = -1;
488 uint32_t *object_ids;
489
490 /* Can't lease without MODESET */
491 if (!drm_core_check_feature(dev, DRIVER_MODESET))
492 return -EOPNOTSUPP;
493
494 if (cl->flags && (cl->flags & ~(O_CLOEXEC | O_NONBLOCK))) {
495 drm_dbg_lease(dev, "invalid flags\n");
496 return -EINVAL;
497 }
498
499 lessor = drm_file_get_master(lessor_priv);
500 /* Do not allow sub-leases */
501 if (lessor->lessor) {
502 drm_dbg_lease(dev, "recursive leasing not allowed\n");
503 ret = -EINVAL;
504 goto out_lessor;
505 }
506
507 object_count = cl->object_count;
508
509 /* Handle leased objects, if any */
510 idr_init(&leases);
511 if (object_count != 0) {
512 object_ids = memdup_array_user(u64_to_user_ptr(cl->object_ids),
513 object_count, sizeof(__u32));
514 if (IS_ERR(object_ids)) {
515 ret = PTR_ERR(object_ids);
516 idr_destroy(&leases);
517 goto out_lessor;
518 }
519
520 /* fill and validate the object idr */
521 ret = fill_object_idr(dev, lessor_priv, &leases,
522 object_count, object_ids);
523 kfree(object_ids);
524 if (ret) {
525 drm_dbg_lease(dev, "lease object lookup failed: %i\n", ret);
526 idr_destroy(&leases);
527 goto out_lessor;
528 }
529 }
530
531 /* Allocate a file descriptor for the lease */
532 fd = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
533 if (fd < 0) {
534 idr_destroy(&leases);
535 ret = fd;
536 goto out_lessor;
537 }
538
539 drm_dbg_lease(dev, "Creating lease\n");
540 /* lessee will take the ownership of leases */
541 lessee = drm_lease_create(lessor, &leases);
542
543 if (IS_ERR(lessee)) {
544 ret = PTR_ERR(lessee);
545 idr_destroy(&leases);
546 goto out_leases;
547 }
548
549 /* Clone the lessor file to create a new file for us */
550 drm_dbg_lease(dev, "Allocating lease file\n");
551 lessee_file = file_clone_open(lessor_file);
552 if (IS_ERR(lessee_file)) {
553 ret = PTR_ERR(lessee_file);
554 goto out_lessee;
555 }
556
557 lessee_priv = lessee_file->private_data;
558 /* Change the file to a master one */
559 drm_master_put(&lessee_priv->master);
560 lessee_priv->master = lessee;
561 lessee_priv->is_master = 1;
562 lessee_priv->authenticated = 1;
563
564 /* Pass fd back to userspace */
565 drm_dbg_lease(dev, "Returning fd %d id %d\n", fd, lessee->lessee_id);
566 cl->fd = fd;
567 cl->lessee_id = lessee->lessee_id;
568
569 /* Hook up the fd */
570 fd_install(fd, lessee_file);
571
572 drm_master_put(&lessor);
573 drm_dbg_lease(dev, "drm_mode_create_lease_ioctl succeeded\n");
574 return 0;
575
576out_lessee:
577 drm_master_put(&lessee);
578
579out_leases:
580 put_unused_fd(fd);
581
582out_lessor:
583 drm_master_put(&lessor);
584 drm_dbg_lease(dev, "drm_mode_create_lease_ioctl failed: %d\n", ret);
585 return ret;
586}
587
588int drm_mode_list_lessees_ioctl(struct drm_device *dev,
589 void *data, struct drm_file *lessor_priv)
590{
591 struct drm_mode_list_lessees *arg = data;
592 __u32 __user *lessee_ids = (__u32 __user *) (uintptr_t) (arg->lessees_ptr);
593 __u32 count_lessees = arg->count_lessees;
594 struct drm_master *lessor, *lessee;
595 int count;
596 int ret = 0;
597
598 if (arg->pad)
599 return -EINVAL;
600
601 /* Can't lease without MODESET */
602 if (!drm_core_check_feature(dev, DRIVER_MODESET))
603 return -EOPNOTSUPP;
604
605 lessor = drm_file_get_master(lessor_priv);
606 drm_dbg_lease(dev, "List lessees for %d\n", lessor->lessee_id);
607
608 mutex_lock(&dev->mode_config.idr_mutex);
609
610 count = 0;
611 drm_for_each_lessee(lessee, lessor) {
612 /* Only list un-revoked leases */
613 if (!idr_is_empty(&lessee->leases)) {
614 if (count_lessees > count) {
615 drm_dbg_lease(dev, "Add lessee %d\n",
616 lessee->lessee_id);
617 ret = put_user(lessee->lessee_id, lessee_ids + count);
618 if (ret)
619 break;
620 }
621 count++;
622 }
623 }
624
625 drm_dbg_lease(dev, "Lessor leases to %d\n", count);
626 if (ret == 0)
627 arg->count_lessees = count;
628
629 mutex_unlock(&dev->mode_config.idr_mutex);
630 drm_master_put(&lessor);
631
632 return ret;
633}
634
635/* Return the list of leased objects for the specified lessee */
636int drm_mode_get_lease_ioctl(struct drm_device *dev,
637 void *data, struct drm_file *lessee_priv)
638{
639 struct drm_mode_get_lease *arg = data;
640 __u32 __user *object_ids = (__u32 __user *) (uintptr_t) (arg->objects_ptr);
641 __u32 count_objects = arg->count_objects;
642 struct drm_master *lessee;
643 struct idr *object_idr;
644 int count;
645 void *entry;
646 int object;
647 int ret = 0;
648
649 if (arg->pad)
650 return -EINVAL;
651
652 /* Can't lease without MODESET */
653 if (!drm_core_check_feature(dev, DRIVER_MODESET))
654 return -EOPNOTSUPP;
655
656 lessee = drm_file_get_master(lessee_priv);
657 drm_dbg_lease(dev, "get lease for %d\n", lessee->lessee_id);
658
659 mutex_lock(&dev->mode_config.idr_mutex);
660
661 if (lessee->lessor == NULL)
662 /* owner can use all objects */
663 object_idr = &lessee->dev->mode_config.object_idr;
664 else
665 /* lessee can only use allowed object */
666 object_idr = &lessee->leases;
667
668 count = 0;
669 idr_for_each_entry(object_idr, entry, object) {
670 if (count_objects > count) {
671 drm_dbg_lease(dev, "adding object %d\n", object);
672 ret = put_user(object, object_ids + count);
673 if (ret)
674 break;
675 }
676 count++;
677 }
678
679 DRM_DEBUG("lease holds %d objects\n", count);
680 if (ret == 0)
681 arg->count_objects = count;
682
683 mutex_unlock(&dev->mode_config.idr_mutex);
684 drm_master_put(&lessee);
685
686 return ret;
687}
688
689/*
690 * This removes all of the objects from the lease without
691 * actually getting rid of the lease itself; that way all
692 * references to it still work correctly
693 */
694int drm_mode_revoke_lease_ioctl(struct drm_device *dev,
695 void *data, struct drm_file *lessor_priv)
696{
697 struct drm_mode_revoke_lease *arg = data;
698 struct drm_master *lessor;
699 struct drm_master *lessee;
700 int ret = 0;
701
702 drm_dbg_lease(dev, "revoke lease for %d\n", arg->lessee_id);
703
704 /* Can't lease without MODESET */
705 if (!drm_core_check_feature(dev, DRIVER_MODESET))
706 return -EOPNOTSUPP;
707
708 lessor = drm_file_get_master(lessor_priv);
709 mutex_lock(&dev->mode_config.idr_mutex);
710
711 lessee = _drm_find_lessee(lessor, arg->lessee_id);
712
713 /* No such lessee */
714 if (!lessee) {
715 ret = -ENOENT;
716 goto fail;
717 }
718
719 /* Lease is not held by lessor */
720 if (lessee->lessor != lessor) {
721 ret = -EACCES;
722 goto fail;
723 }
724
725 _drm_lease_revoke(lessee);
726
727fail:
728 mutex_unlock(&dev->mode_config.idr_mutex);
729 drm_master_put(&lessor);
730
731 return ret;
732}