1 files changed, 263 insertions, 22 deletions

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 50d0baa06db0..4153e8a193af 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);