1 files changed, 263 insertions, 22 deletions

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 50d0baa06..4153e8a19 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -30,25 +30,36 @@
 
 #include <drm/drmP.h>
 #include "drm_internal.h"
+#include "drm_legacy.h"
 
 /**
- * drm_getmagic - Get unique magic of a client
- * @dev: DRM device to operate on
- * @data: ioctl data containing the drm_auth object
- * @file_priv: DRM file that performs the operation
+ * DOC: master and authentication
  *
- * This looks up the unique magic of the passed client and returns it. If the
- * client did not have a magic assigned, yet, a new one is registered. The magic
- * is stored in the passed drm_auth object.
+ * struct &drm_master is used to track groups of clients with open
+ * primary/legacy device nodes. For every struct &drm_file which has had at
+ * least once successfully became the device master (either through the
+ * SET_MASTER IOCTL, or implicitly through opening the primary device node when
+ * no one else is the current master that time) there exists one &drm_master.
+ * This is noted in the is_master member of &drm_file. All other clients have
+ * just a pointer to the &drm_master they are associated with.
  *
- * Returns: 0 on success, negative error code on failure.
+ * In addition only one &drm_master can be the current master for a &drm_device.
+ * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
+ * implicitly through closing/openeing the primary device node. See also
+ * drm_is_current_master().
+ *
+ * Clients can authenticate against the current master (if it matches their own)
+ * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
+ * this allows controlled access to the device for an entire group of mutually
+ * trusted clients.
  */
+
 int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 {
 	struct drm_auth *auth = data;
 	int ret = 0;
 
-	mutex_lock(&dev->struct_mutex);
+	mutex_lock(&dev->master_mutex);
 	if (!file_priv->magic) {
 		ret = idr_alloc(&file_priv->master->magic_map, file_priv,
 				1, 0, GFP_KERNEL);
@@ -56,23 +67,13 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
 			file_priv->magic = ret;
 	}
 	auth->magic = file_priv->magic;
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev->master_mutex);
 
 	DRM_DEBUG("%u\n", auth->magic);
 
 	return ret < 0 ? ret : 0;
 }
 
-/**
- * drm_authmagic - Authenticate client with a magic
- * @dev: DRM device to operate on
- * @data: ioctl data containing the drm_auth object
- * @file_priv: DRM file that performs the operation
- *
- * This looks up a DRM client by the passed magic and authenticates it.
- *
- * Returns: 0 on success, negative error code on failure.
- */
 int drm_authmagic(struct drm_device *dev, void *data,
 		  struct drm_file *file_priv)
 {
@@ -81,13 +82,253 @@ int drm_authmagic(struct drm_device *dev, void *data,
 
 	DRM_DEBUG("%u\n", auth->magic);
 
-	mutex_lock(&dev->struct_mutex);
+	mutex_lock(&dev->master_mutex);
 	file = idr_find(&file_priv->master->magic_map, auth->magic);
 	if (file) {
 		file->authenticated = 1;
 		idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
 	}
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev->master_mutex);
 
 	return file ? 0 : -EINVAL;
 }
+
+static struct drm_master *drm_master_create(struct drm_device *dev)
+{
+	struct drm_master *master;
+
+	master = kzalloc(sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return NULL;
+
+	kref_init(&master->refcount);
+	spin_lock_init(&master->lock.spinlock);
+	init_waitqueue_head(&master->lock.lock_queue);
+	idr_init(&master->magic_map);
+	master->dev = dev;
+
+	return master;
+}
+
+static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
+			  bool new_master)
+{
+	int ret = 0;
+
+	dev->master = drm_master_get(fpriv->master);
+	if (dev->driver->master_set) {
+		ret = dev->driver->master_set(dev, fpriv, new_master);
+		if (unlikely(ret != 0)) {
+			drm_master_put(&dev->master);
+		}
+	}
+
+	return ret;
+}
+
+static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
+{
+	struct drm_master *old_master;
+	int ret;
+
+	lockdep_assert_held_once(&dev->master_mutex);
+
+	old_master = fpriv->master;
+	fpriv->master = drm_master_create(dev);
+	if (!fpriv->master) {
+		fpriv->master = old_master;
+		return -ENOMEM;
+	}
+
+	if (dev->driver->master_create) {
+		ret = dev->driver->master_create(dev, fpriv->master);
+		if (ret)
+			goto out_err;
+	}
+	fpriv->is_master = 1;
+	fpriv->authenticated = 1;
+
+	ret = drm_set_master(dev, fpriv, true);
+	if (ret)
+		goto out_err;
+
+	if (old_master)
+		drm_master_put(&old_master);
+
+	return 0;
+
+out_err:
+	/* drop references and restore old master on failure */
+	drm_master_put(&fpriv->master);
+	fpriv->master = old_master;
+
+	return ret;
+}
+
+int drm_setmaster_ioctl(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	int ret = 0;
+
+	mutex_lock(&dev->master_mutex);
+	if (drm_is_current_master(file_priv))
+		goto out_unlock;
+
+	if (dev->master) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!file_priv->master) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!file_priv->is_master) {
+		ret = drm_new_set_master(dev, file_priv);
+		goto out_unlock;
+	}
+
+	ret = drm_set_master(dev, file_priv, false);
+out_unlock:
+	mutex_unlock(&dev->master_mutex);
+	return ret;
+}
+
+static void drm_drop_master(struct drm_device *dev,
+			    struct drm_file *fpriv)
+{
+	if (dev->driver->master_drop)
+		dev->driver->master_drop(dev, fpriv);
+	drm_master_put(&dev->master);
+}
+
+int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
+			 struct drm_file *file_priv)
+{
+	int ret = -EINVAL;
+
+	mutex_lock(&dev->master_mutex);
+	if (!drm_is_current_master(file_priv))
+		goto out_unlock;
+
+	if (!dev->master)
+		goto out_unlock;
+
+	ret = 0;
+	drm_drop_master(dev, file_priv);
+out_unlock:
+	mutex_unlock(&dev->master_mutex);
+	return ret;
+}
+
+int drm_master_open(struct drm_file *file_priv)
+{
+	struct drm_device *dev = file_priv->minor->dev;
+	int ret = 0;
+
+	/* if there is no current master make this fd it, but do not create
+	 * any master object for render clients */
+	mutex_lock(&dev->master_mutex);
+	if (!dev->master)
+		ret = drm_new_set_master(dev, file_priv);
+	else
+		file_priv->master = drm_master_get(dev->master);
+	mutex_unlock(&dev->master_mutex);
+
+	return ret;
+}
+
+void drm_master_release(struct drm_file *file_priv)
+{
+	struct drm_device *dev = file_priv->minor->dev;
+	struct drm_master *master = file_priv->master;
+
+	mutex_lock(&dev->master_mutex);
+	if (file_priv->magic)
+		idr_remove(&file_priv->master->magic_map, file_priv->magic);
+
+	if (!drm_is_current_master(file_priv))
+		goto out;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET)) {
+		/*
+		 * Since the master is disappearing, so is the
+		 * possibility to lock.
+		 */
+		mutex_lock(&dev->struct_mutex);
+		if (master->lock.hw_lock) {
+			if (dev->sigdata.lock == master->lock.hw_lock)
+				dev->sigdata.lock = NULL;
+			master->lock.hw_lock = NULL;
+			master->lock.file_priv = NULL;
+			wake_up_interruptible_all(&master->lock.lock_queue);
+		}
+		mutex_unlock(&dev->struct_mutex);
+	}
+
+	if (dev->master == file_priv->master)
+		drm_drop_master(dev, file_priv);
+out:
+	/* drop the master reference held by the file priv */
+	if (file_priv->master)
+		drm_master_put(&file_priv->master);
+	mutex_unlock(&dev->master_mutex);
+}
+
+/**
+ * drm_is_current_master - checks whether @priv is the current master
+ * @fpriv: DRM file private
+ *
+ * Checks whether @fpriv is current master on its device. This decides whether a
+ * client is allowed to run DRM_MASTER IOCTLs.
+ *
+ * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
+ * - the current master is assumed to own the non-shareable display hardware.
+ */
+bool drm_is_current_master(struct drm_file *fpriv)
+{
+	return fpriv->is_master && fpriv->master == fpriv->minor->dev->master;
+}
+EXPORT_SYMBOL(drm_is_current_master);
+
+/**
+ * drm_master_get - reference a master pointer
+ * @master: struct &drm_master
+ *
+ * Increments the reference count of @master and returns a pointer to @master.
+ */
+struct drm_master *drm_master_get(struct drm_master *master)
+{
+	kref_get(&master->refcount);
+	return master;
+}
+EXPORT_SYMBOL(drm_master_get);
+
+static void drm_master_destroy(struct kref *kref)
+{
+	struct drm_master *master = container_of(kref, struct drm_master, refcount);
+	struct drm_device *dev = master->dev;
+
+	if (dev->driver->master_destroy)
+		dev->driver->master_destroy(dev, master);
+
+	drm_legacy_master_rmmaps(dev, master);
+
+	idr_destroy(&master->magic_map);
+	kfree(master->unique);
+	kfree(master);
+}
+
+/**
+ * drm_master_put - unreference and clear a master pointer
+ * @master: pointer to a pointer of struct &drm_master
+ *
+ * This decrements the &drm_master behind @master and sets it to NULL.
+ */
+void drm_master_put(struct drm_master **master)
+{
+	kref_put(&(*master)->refcount, drm_master_destroy);
+	*master = NULL;
+}
+EXPORT_SYMBOL(drm_master_put);