// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright © 2017 Keith Packard <[email protected]>
*/
#include <linux/file.h>
#include <linux/uaccess.h>
#include <drm/drm_auth.h>
#include <drm/drm_crtc.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
#include <drm/drm_lease.h>
#include <drm/drm_print.h>
#include "drm_crtc_internal.h"
#include "drm_internal.h"
/**
* DOC: drm leasing
*
* DRM leases provide information about whether a DRM master may control a DRM
* mode setting object. This enables the creation of multiple DRM masters that
* manage subsets of display resources.
*
* The original DRM master of a device 'owns' the available drm resources. It
* may create additional DRM masters and 'lease' resources which it controls
* to the new DRM master. This gives the new DRM master control over the
* leased resources until the owner revokes the lease, or the new DRM master
* is closed. Some helpful terminology:
*
* - An 'owner' is a &struct drm_master that is not leasing objects from
* another &struct drm_master, and hence 'owns' the objects. The owner can be
* identified as the &struct drm_master for which &drm_master.lessor is NULL.
*
* - A 'lessor' is a &struct drm_master which is leasing objects to one or more
* other &struct drm_master. Currently, lessees are not allowed to
* create sub-leases, hence the lessor is the same as the owner.
*
* - A 'lessee' is a &struct drm_master which is leasing objects from some
* other &struct drm_master. Each lessee only leases resources from a single
* lessor recorded in &drm_master.lessor, and holds the set of objects that
* it is leasing in &drm_master.leases.
*
* - A 'lease' is a contract between the lessor and lessee that identifies
* which resources may be controlled by the lessee. All of the resources
* that are leased must be owned by or leased to the lessor, and lessors are
* not permitted to lease the same object to multiple lessees.
*
* The set of objects any &struct drm_master 'controls' is limited to the set
* of objects it leases (for lessees) or all objects (for owners).
*
* Objects not controlled by a &struct drm_master cannot be modified through
* the various state manipulating ioctls, and any state reported back to user
* space will be edited to make them appear idle and/or unusable. For
* instance, connectors always report 'disconnected', while encoders
* report no possible crtcs or clones.
*
* Since each lessee may lease objects from a single lessor, display resource
* leases form a tree of &struct drm_master. As lessees are currently not
* allowed to create sub-leases, the tree depth is limited to 1. All of
* these get activated simultaneously when the top level device owner changes
* through the SETMASTER or DROPMASTER IOCTL, so &drm_device.master points to
* the owner at the top of the lease tree (i.e. the &struct drm_master for which
* &drm_master.lessor is NULL). The full list of lessees that are leasing
* objects from the owner can be searched via the owner's
* &drm_master.lessee_idr.
*/
#define drm_for_each_lessee(lessee, lessor) \
list_for_each_entry((lessee), &(lessor)->lessees, lessee_list)
static uint64_t drm_lease_idr_object;
struct drm_master *drm_lease_owner(struct drm_master *master)
{
while (master->lessor != NULL)
master = master->lessor;
return master;
}
static struct drm_master*
_drm_find_lessee(struct drm_master *master, int lessee_id)
{
lockdep_assert_held(&master->dev->mode_config.idr_mutex);
return idr_find(&drm_lease_owner(master)->lessee_idr, lessee_id);
}
static int _drm_lease_held_master(struct drm_master *master, int id)
{
lockdep_assert_held(&master->dev->mode_config.idr_mutex);
if (master->lessor)
return idr_find(&master->leases, id) != NULL;
return true;
}
/* Checks if the given object has been leased to some lessee of drm_master */
static bool _drm_has_leased(struct drm_master *master, int id)
{
struct drm_master *lessee;
lockdep_assert_held(&master->dev->mode_config.idr_mutex);
drm_for_each_lessee(lessee, master)
if (_drm_lease_held_master(lessee, id))
return true;
return false;
}
/* Called with idr_mutex held */
bool _drm_lease_held(struct drm_file *file_priv, int id)
{
bool ret;
struct drm_master *master;
if (!file_priv)
return true;
master = drm_file_get_master(file_priv);
if (!master)
return true;
ret = _drm_lease_held_master(master, id);
drm_master_put(&master);
return ret;
}
bool drm_lease_held(struct drm_file *file_priv, int id)
{
struct drm_master *master;
bool ret;
if (!file_priv)
return true;
master = drm_file_get_master(file_priv);
if (!master)
return true;
if (!master->lessor) {
ret = true;
goto out;
}
mutex_lock(&master->dev->mode_config.idr_mutex);
ret = _drm_lease_held_master(master, id);
mutex_unlock(&master->dev->mode_config.idr_mutex);
out:
drm_master_put(&master);
return ret;
}
/*
* Given a bitmask of crtcs to check, reconstructs a crtc mask based on the
* crtcs which are visible through the specified file.
*/
uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
{
struct drm_master *master;
struct drm_device *dev;
struct drm_crtc *crtc;
int count_in, count_out;
uint32_t crtcs_out = 0;
if (!file_priv)
return crtcs_in;
master = drm_file_get_master(file_priv);
if (!master)
return crtcs_in;
if (!master->lessor) {
crtcs_out = crtcs_in;
goto out;
}
dev = master->dev;
count_in = count_out = 0;
mutex_lock(&master->dev->mode_config.idr_mutex);
list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
if (_drm_lease_held_master(master, crtc->base.id)) {
uint32_t mask_in = 1ul << count_in;
if ((crtcs_in & mask_in) != 0) {
uint32_t mask_out = 1ul << count_out;
crtcs_out |= mask_out;
}
count_out++;
}
count_in++;
}
mutex_unlock(&master->dev->mode_config.idr_mutex);
out:
drm_master_put(&master);
return crtcs_out;
}
/*
* Uses drm_master_create to allocate a new drm_master, then checks to
* make sure all of the desired objects can be leased, atomically
* leasing them to the new drmmaster.
*
* ERR_PTR(-EACCES) some other master holds the title to any object
* ERR_PTR(-ENOENT) some object is not a valid DRM object for this device
* ERR_PTR(-EBUSY) some other lessee holds title to this object
* ERR_PTR(-EEXIST) same object specified more than once in the provided list
* ERR_PTR(-ENOMEM) allocation failed
*/
static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr *leases)
{
struct drm_device *dev = lessor->dev;
int error;
struct drm_master *lessee;
int object;
int id;
void *entry;
drm_dbg_lease(dev, "lessor %d\n", lessor->lessee_id);
lessee = drm_master_create(lessor->dev);
if (!lessee) {
drm_dbg_lease(dev, "drm_master_create failed\n");
return ERR_PTR(-ENOMEM);
}
mutex_lock(&dev->mode_config.idr_mutex);
idr_for_each_entry(leases, entry, object) {
error = 0;
if (!idr_find(&dev->mode_config.object_idr, object))
error = -ENOENT;
else if (_drm_has_leased(lessor, object))
error = -EBUSY;
if (error != 0) {
drm_dbg_lease(dev, "object %d failed %d\n", object, error);
goto out_lessee;
}
}
/* Insert the new lessee into the tree */
id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
if (id < 0) {
error = id;
goto out_lessee;
}
lessee->lessee_id = id;
lessee->lessor = drm_master_get(lessor);
list_add_tail(&lessee->lessee_list, &lessor->lessees);
/* Move the leases over */
lessee->leases = *leases;
drm_dbg_lease(dev, "new lessee %d %p, lessor %d %p\n",
lessee->lessee_id, lessee, lessor->lessee_id, lessor);
mutex_unlock(&dev->mode_config.idr_mutex);
return lessee;
out_lessee:
mutex_unlock(&dev->mode_config.idr_mutex);
drm_master_put(&lessee);
return ERR_PTR(error);
}
void drm_lease_destroy(struct drm_master *master)
{
struct drm_device *dev = master->dev;
mutex_lock(&dev->mode_config.idr_mutex);
drm_dbg_lease(dev, "drm_lease_destroy %d\n", master->lessee_id);
/* This master is referenced by all lessees, hence it cannot be destroyed
* until all of them have been
*/
WARN_ON(!list_empty(&master->lessees));
/* Remove this master from the lessee idr in the owner */
if (master->lessee_id != 0) {
drm_dbg_lease(dev, "remove master %d from device list of lessees\n",
master->lessee_id);
idr_remove(&(drm_lease_owner(master)->lessee_idr), master->lessee_id);
}
/* Remove this master from any lessee list it may be on */
list_del(&master->lessee_list);
mutex_unlock(&dev->mode_config.idr_mutex);
if (master->lessor) {
/* Tell the master to check the lessee list */
drm_sysfs_lease_event(dev);
drm_master_put(&master->lessor);
}
drm_dbg_lease(dev, "drm_lease_destroy done %d\n", master->lessee_id);
}
static void _drm_lease_revoke(struct drm_master *top)
{
int object;
void *entry;
struct drm_master *master = top;
lockdep_assert_held(&top->dev->mode_config.idr_mutex);
/*
* Walk the tree starting at 'top' emptying all leases. Because
* the tree is fully connected, we can do this without recursing
*/
for (;;) {
drm_dbg_lease(master->dev, "revoke leases for %p %d\n",
master, master->lessee_id);
/* Evacuate the lease */
idr_for_each_entry(&master->leases, entry, object)
idr_remove(&master->leases, object);
/* Depth-first list walk */
/* Down */
if (!list_empty(&master->lessees)) {
master = list_first_entry(&master->lessees, struct drm_master, lessee_list);
} else {
/* Up */
while (master != top && master == list_last_entry(&master->lessor->lessees, struct drm_master, lessee_list))
master = master->lessor;
if (master == top)
break;
/* Over */
master = list_next_entry(master, lessee_list);
}
}
}
void drm_lease_revoke(struct drm_master *top)
{
mutex_lock(&top->dev->mode_config.idr_mutex);
_drm_lease_revoke(top);
mutex_unlock(&top->dev->mode_config.idr_mutex);
}
static int validate_lease(struct drm_device *dev,
int object_count,
struct drm_mode_object **objects,
bool universal_planes)
{
int o;
int has_crtc = -1;
int has_connector = -1;
int has_plane = -1;
/* we want to confirm that there is at least one crtc, plane
connector object. */
for (o = 0; o < object_count; o++) {
if (objects[o]->type == DRM_MODE_OBJECT_CRTC && has_crtc == -1) {
has_crtc = o;
}
if (objects[o]->type == DRM_MODE_OBJECT_CONNECTOR && has_connector == -1)
has_connector = o;
if (universal_planes) {
if (objects[o]->type == DRM_MODE_OBJECT_PLANE && has_plane == -1)
has_plane = o;
}
}
if (has_crtc == -1 || has_connector == -1)
return -EINVAL;
if (universal_planes && has_plane == -1)
return -EINVAL;
return 0;
}
static int fill_object_idr(struct drm_device *dev,
struct drm_file *lessor_priv,
struct idr *leases,
int object_count,
u32 *object_ids)
{
struct drm_mode_object **objects;
u32 o;
int ret;
bool universal_planes = READ_ONCE(lessor_priv->universal_planes);
objects = kcalloc(object_count, sizeof(struct drm_mode_object *),
GFP_KERNEL);
if (!objects)
return -ENOMEM;
/* step one - get references to all the mode objects
and check for validity. */
for (o = 0; o < object_count; o++) {
objects[o] = drm_mode_object_find(dev, lessor_priv,
object_ids[o],
DRM_MODE_OBJECT_ANY);
if (!objects[o]) {
ret = -ENOENT;
goto out_free_objects;
}
if (!drm_mode_object_lease_required(objects[o]->type)) {
DRM_DEBUG_KMS("invalid object for lease\n");
ret = -EINVAL;
goto out_free_objects;
}
}
ret = validate_lease(dev, object_count, objects, universal_planes);
if (ret) {
drm_dbg_lease(dev, "lease validation failed\n");
goto out_free_objects;
}
/* add their IDs to the lease request - taking into account
universal planes */
for (o = 0; o < object_count; o++) {
struct drm_mode_object *obj = objects[o];
u32 object_id = objects[o]->id;
drm_dbg_lease(dev, "Adding object %d to lease\n", object_id);
/*
* We're using an IDR to hold the set of leased
* objects, but we don't need to point at the object's
* data structure from the lease as the main object_idr
* will be used to actually find that. Instead, all we
* really want is a 'leased/not-leased' result, for
* which any non-NULL pointer will work fine.
*/
ret = idr_alloc(leases, &drm_lease_idr_object , object_id, object_id + 1, GFP_KERNEL);
if (ret < 0) {
drm_dbg_lease(dev, "Object %d cannot be inserted into leases (%d)\n",
object_id, ret);
goto out_free_objects;
}
if (obj->type == DRM_MODE_OBJECT_CRTC && !universal_planes) {
struct drm_crtc *crtc = obj_to_crtc(obj);
ret = idr_alloc(leases, &drm_lease_idr_object, crtc->primary->base.id, crtc->primary->base.id + 1, GFP_KERNEL);
if (ret < 0) {
drm_dbg_lease(dev, "Object primary plane %d cannot be inserted into leases (%d)\n",
object_id, ret);
goto out_free_objects;
}
if (crtc->cursor) {
ret = idr_alloc(leases, &drm_lease_idr_object, crtc->cursor->base.id, crtc->cursor->base.id + 1, GFP_KERNEL);
if (ret < 0) {
drm_dbg_lease(dev, "Object cursor plane %d cannot be inserted into leases (%d)\n",
object_id, ret);
goto out_free_objects;
}
}
}
}
ret = 0;
out_free_objects:
for (o = 0; o < object_count; o++) {
if (objects[o])
drm_mode_object_put(objects[o]);
}
kfree(objects);
return ret;
}
/*
* The master associated with the specified file will have a lease
* created containing the objects specified in the ioctl structure.
* A file descriptor will be allocated for that and returned to the
* application.
*/
int drm_mode_create_lease_ioctl(struct drm_device *dev,
void *data, struct drm_file *lessor_priv)
{
struct drm_mode_create_lease *cl = data;
size_t object_count;
int ret = 0;
struct idr leases;
struct drm_master *lessor;
struct drm_master *lessee = NULL;
struct file *lessee_file = NULL;
struct file *lessor_file = lessor_priv->filp;
struct drm_file *lessee_priv;
int fd = -1;
uint32_t *object_ids;
/* Can't lease without MODESET */
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
if (cl->flags && (cl->flags & ~(O_CLOEXEC | O_NONBLOCK))) {
drm_dbg_lease(dev, "invalid flags\n");
return -EINVAL;
}
lessor = drm_file_get_master(lessor_priv);
/* Do not allow sub-leases */
if (lessor->lessor) {
drm_dbg_lease(dev, "recursive leasing not allowed\n");
ret = -EINVAL;
goto out_lessor;
}
object_count = cl->object_count;
/* Handle leased objects, if any */
idr_init(&leases);
if (object_count != 0) {
object_ids = memdup_array_user(u64_to_user_ptr(cl->object_ids),
object_count, sizeof(__u32));
if (IS_ERR(object_ids)) {
ret = PTR_ERR(object_ids);
idr_destroy(&leases);
goto out_lessor;
}
/* fill and validate the object idr */
ret = fill_object_idr(dev, lessor_priv, &leases,
object_count, object_ids);
kfree(object_ids);
if (ret) {
drm_dbg_lease(dev, "lease object lookup failed: %i\n", ret);
idr_destroy(&leases);
goto out_lessor;
}
}
/* Allocate a file descriptor for the lease */
fd = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
if (fd < 0) {
idr_destroy(&leases);
ret = fd;
goto out_lessor;
}
drm_dbg_lease(dev, "Creating lease\n");
/* lessee will take the ownership of leases */
lessee = drm_lease_create(lessor, &leases);
if (IS_ERR(lessee)) {
ret = PTR_ERR(lessee);
idr_destroy(&leases);
goto out_leases;
}
/* Clone the lessor file to create a new file for us */
drm_dbg_lease(dev, "Allocating lease file\n");
lessee_file = file_clone_open(lessor_file);
if (IS_ERR(lessee_file)) {
ret = PTR_ERR(lessee_file);
goto out_lessee;
}
lessee_priv = lessee_file->private_data;
/* Change the file to a master one */
drm_master_put(&lessee_priv->master);
lessee_priv->master = lessee;
lessee_priv->is_master = 1;
lessee_priv->authenticated = 1;
/* Pass fd back to userspace */
drm_dbg_lease(dev, "Returning fd %d id %d\n", fd, lessee->lessee_id);
cl->fd = fd;
cl->lessee_id = lessee->lessee_id;
/* Hook up the fd */
fd_install(fd, lessee_file);
drm_master_put(&lessor);
drm_dbg_lease(dev, "drm_mode_create_lease_ioctl succeeded\n");
return 0;
out_lessee:
drm_master_put(&lessee);
out_leases:
put_unused_fd(fd);
out_lessor:
drm_master_put(&lessor);
drm_dbg_lease(dev, "drm_mode_create_lease_ioctl failed: %d\n", ret);
return ret;
}
int drm_mode_list_lessees_ioctl(struct drm_device *dev,
void *data, struct drm_file *lessor_priv)
{
struct drm_mode_list_lessees *arg = data;
__u32 __user *lessee_ids = (__u32 __user *) (uintptr_t) (arg->lessees_ptr);
__u32 count_lessees = arg->count_lessees;
struct drm_master *lessor, *lessee;
int count;
int ret = 0;
if (arg->pad)
return -EINVAL;
/* Can't lease without MODESET */
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
lessor = drm_file_get_master(lessor_priv);
drm_dbg_lease(dev, "List lessees for %d\n", lessor->lessee_id);
mutex_lock(&dev->mode_config.idr_mutex);
count = 0;
drm_for_each_lessee(lessee, lessor) {
/* Only list un-revoked leases */
if (!idr_is_empty(&lessee->leases)) {
if (count_lessees > count) {
drm_dbg_lease(dev, "Add lessee %d\n",
lessee->lessee_id);
ret = put_user(lessee->lessee_id, lessee_ids + count);
if (ret)
break;
}
count++;
}
}
drm_dbg_lease(dev, "Lessor leases to %d\n", count);
if (ret == 0)
arg->count_lessees = count;
mutex_unlock(&dev->mode_config.idr_mutex);
drm_master_put(&lessor);
return ret;
}
/* Return the list of leased objects for the specified lessee */
int drm_mode_get_lease_ioctl(struct drm_device *dev,
void *data, struct drm_file *lessee_priv)
{
struct drm_mode_get_lease *arg = data;
__u32 __user *object_ids = (__u32 __user *) (uintptr_t) (arg->objects_ptr);
__u32 count_objects = arg->count_objects;
struct drm_master *lessee;
struct idr *object_idr;
int count;
void *entry;
int object;
int ret = 0;
if (arg->pad)
return -EINVAL;
/* Can't lease without MODESET */
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
lessee = drm_file_get_master(lessee_priv);
drm_dbg_lease(dev, "get lease for %d\n", lessee->lessee_id);
mutex_lock(&dev->mode_config.idr_mutex);
if (lessee->lessor == NULL)
/* owner can use all objects */
object_idr = &lessee->dev->mode_config.object_idr;
else
/* lessee can only use allowed object */
object_idr = &lessee->leases;
count = 0;
idr_for_each_entry(object_idr, entry, object) {
if (count_objects > count) {
drm_dbg_lease(dev, "adding object %d\n", object);
ret = put_user(object, object_ids + count);
if (ret)
break;
}
count++;
}
DRM_DEBUG("lease holds %d objects\n", count);
if (ret == 0)
arg->count_objects = count;
mutex_unlock(&dev->mode_config.idr_mutex);
drm_master_put(&lessee);
return ret;
}
/*
* This removes all of the objects from the lease without
* actually getting rid of the lease itself; that way all
* references to it still work correctly
*/
int drm_mode_revoke_lease_ioctl(struct drm_device *dev,
void *data, struct drm_file *lessor_priv)
{
struct drm_mode_revoke_lease *arg = data;
struct drm_master *lessor;
struct drm_master *lessee;
int ret = 0;
drm_dbg_lease(dev, "revoke lease for %d\n", arg->lessee_id);
/* Can't lease without MODESET */
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
lessor = drm_file_get_master(lessor_priv);
mutex_lock(&dev->mode_config.idr_mutex);
lessee = _drm_find_lessee(lessor, arg->lessee_id);
/* No such lessee */
if (!lessee) {
ret = -ENOENT;
goto fail;
}
/* Lease is not held by lessor */
if (lessee->lessor != lessor) {
ret = -EACCES;
goto fail;
}
_drm_lease_revoke(lessee);
fail:
mutex_unlock(&dev->mode_config.idr_mutex);
drm_master_put(&lessor);
return ret;
}
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