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Commit 3cb01a98 authored by David Herrmann's avatar David Herrmann
Browse files

drm: don't de-authenticate clients on master-close 



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: default avatarAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
parent 48ba8137

drivers/gpu/drm/drm_fops.c

+2 −11
Original line number Original line Diff line number Diff line
@@ -199,8 +199,7 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor) 
	priv->minor = minor;

	priv->minor = minor;





	/* for compatibility root is always authenticated */

	/* for compatibility root is always authenticated */

	priv->always_authenticated = capable(CAP_SYS_ADMIN);

	priv->authenticated = capable(CAP_SYS_ADMIN);

	priv->authenticated = priv->always_authenticated;

	priv->lock_count = 0;

	priv->lock_count = 0;





	INIT_LIST_HEAD(&priv->lhead);

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




	if (drm_is_master(file_priv)) {

	if (drm_is_master(file_priv)) {

		struct drm_master *master = file_priv->master;

		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

		 * Since the master is disappearing, so is the

		 * possibility to lock.

		 * possibility to lock.

		 */

		 */



		mutex_lock(&dev->struct_mutex);

		if (master->lock.hw_lock) {

		if (master->lock.hw_lock) {

			if (dev->sigdata.lock == master->lock.hw_lock)

			if (dev->sigdata.lock == master->lock.hw_lock)

				dev->sigdata.lock = NULL;

				dev->sigdata.lock = NULL;

include/drm/drmP.h

+0 −1
Original line number Original line Diff line number Diff line
@@ -385,7 +385,6 @@ struct drm_prime_file_private { 




/** File private data */

/** File private data */

struct drm_file {

struct drm_file {

	unsigned always_authenticated :1;

	unsigned authenticated :1;

	unsigned authenticated :1;

	/* true when the client has asked us to expose stereo 3D mode flags */

	/* true when the client has asked us to expose stereo 3D mode flags */

	unsigned stereo_allowed :1;

	unsigned stereo_allowed :1;