drm: don't de-authenticate clients on master-close (3cb01a98) · Commits · 戴 / test

If an active DRM-Master closes its device, we deauthenticate all clients on that master. However, if an inactive DRM-Master closes its device, we do nothing. This is quite inconsistent and breaks several scenarios: 1) If this was used as security mechanism, it fails horribly if a master closes a device while VT switched away. Furthermore, none of the few drivers using ->master_*() callbacks seems to require it, anyway. 2) If you spawn weston (or any other non-UMS compositor) in background while another compositor is active, both will get assigned to the same "drm_master" object. If the foreground compositor now exits, all clients of both the foreground AND background compositor will be de-authenticated leading to unexpected behavior. Stop this non-sense and keep clients authenticated. We don't do this when dropping DRM-Master (i.e., switching VTs) so don't do it on active-close either! Reviewed-by:

Alex Deucher <alexander.deucher@amd.com> Reviewed-by:

Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by:

David Herrmann <dh.herrmann@gmail.com>

drivers/gpu/drm/drm_fops.c

+2 −11

Original line number	Diff line number	Diff line
		@@ -199,8 +199,7 @@ static int drm_open_helper(struct file filp, struct drm_minor minor)
		priv->minor = minor;

		/* for compatibility root is always authenticated */
		priv->always_authenticated = capable(CAP_SYS_ADMIN);
		priv->authenticated = priv->always_authenticated;
		priv->authenticated = capable(CAP_SYS_ADMIN);
		priv->lock_count = 0;

		INIT_LIST_HEAD(&priv->lhead);
		@@ -462,20 +461,12 @@ int drm_release(struct inode inode, struct file filp)

		if (drm_is_master(file_priv)) {
		struct drm_master *master = file_priv->master;
		struct drm_file *temp;

		mutex_lock(&dev->struct_mutex);
		list_for_each_entry(temp, &dev->filelist, lhead) {
		if ((temp->master == file_priv->master) &&
		(temp != file_priv))
		temp->authenticated = temp->always_authenticated;
		}

		/**
		* 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;

include/drm/drmP.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -385,7 +385,6 @@ struct drm_prime_file_private {

		/** File private data */
		struct drm_file {
		unsigned always_authenticated :1;
		unsigned authenticated :1;
		/* true when the client has asked us to expose stereo 3D mode flags */
		unsigned stereo_allowed :1;

Admin message