From 01573e231f18eb2d99162747186f59511f56b64d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 08 Dec 2023 10:40:48 +0000
Subject: [PATCH] 移去rt
---
kernel/drivers/gpu/drm/drm_auth.c | 166 ++++++++++++++++++++++++++++++++++++-------------------
1 files changed, 109 insertions(+), 57 deletions(-)
diff --git a/kernel/drivers/gpu/drm/drm_auth.c b/kernel/drivers/gpu/drm/drm_auth.c
index ce098eb..232abbb 100644
--- a/kernel/drivers/gpu/drm/drm_auth.c
+++ b/kernel/drivers/gpu/drm/drm_auth.c
@@ -28,10 +28,16 @@
* OTHER DEALINGS IN THE SOFTWARE.
*/
-#include <drm/drmP.h>
+#include <linux/slab.h>
+
+#include <drm/drm_auth.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_lease.h>
+#include <drm/drm_print.h>
+
#include "drm_internal.h"
#include "drm_legacy.h"
-#include <drm/drm_lease.h>
/**
* DOC: master and authentication
@@ -103,14 +109,11 @@
return NULL;
kref_init(&master->refcount);
- spin_lock_init(&master->lock.spinlock);
- init_waitqueue_head(&master->lock.lock_queue);
+ drm_master_legacy_init(master);
idr_init(&master->magic_map);
master->dev = dev;
/* initialize the tree of output resource lessees */
- master->lessor = NULL;
- master->lessee_id = 0;
INIT_LIST_HEAD(&master->lessees);
INIT_LIST_HEAD(&master->lessee_list);
idr_init(&master->leases);
@@ -119,26 +122,19 @@
return master;
}
-static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
- bool new_master)
+static void 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);
- }
- }
+ if (dev->driver->master_set)
+ dev->driver->master_set(dev, fpriv, new_master);
- return ret;
+ fpriv->was_master = true;
}
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);
@@ -150,43 +146,88 @@
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;
+ drm_set_master(dev, fpriv, true);
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;
- fpriv->is_master = 0;
+/*
+ * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
+ * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
+ * from becoming master and/or failing to release it.
+ *
+ * At the same time, the first client (for a given VT) is _always_ master.
+ * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
+ * application as root or flip the setuid bit.
+ *
+ * If the CAP_SYS_ADMIN was missing, no other client could become master...
+ * EVER :-( Leading to a) the graphics session dying badly or b) a completely
+ * locked session.
+ *
+ *
+ * As some point systemd-logind was introduced to orchestrate and delegate
+ * master as applicable. It does so by opening the fd and passing it to users
+ * while in itself logind a) does the set/drop master per users' request and
+ * b) * implicitly drops master on VT switch.
+ *
+ * Even though logind looks like the future, there are a few issues:
+ * - some platforms don't have equivalent (Android, CrOS, some BSDs) so
+ * root is required _solely_ for SET/DROP MASTER.
+ * - applications may not be updated to use it,
+ * - any client which fails to drop master* can DoS the application using
+ * logind, to a varying degree.
+ *
+ * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
+ *
+ *
+ * Here we implement the next best thing:
+ * - ensure the logind style of fd passing works unchanged, and
+ * - allow a client to drop/set master, iff it is/was master at a given point
+ * in time.
+ *
+ * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
+ * - DoS/crash the arbitrator - details would be implementation specific
+ * - open the node, become master implicitly and cause issues
+ *
+ * As a result this fixes the following when using root-less build w/o logind
+ * - startx
+ * - weston
+ * - various compositors based on wlroots
+ */
+static int
+drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
+{
+ if (file_priv->pid == task_pid(current) && file_priv->was_master)
+ return 0;
- return ret;
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ return 0;
}
int drm_setmaster_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
- int ret = 0;
+ int ret;
mutex_lock(&dev->master_mutex);
+
+ ret = drm_master_check_perm(dev, file_priv);
+ if (ret)
+ goto out_unlock;
+
if (drm_is_current_master(file_priv))
goto out_unlock;
if (dev->master) {
- ret = -EINVAL;
+ ret = -EBUSY;
goto out_unlock;
}
@@ -206,7 +247,7 @@
goto out_unlock;
}
- ret = drm_set_master(dev, file_priv, false);
+ drm_set_master(dev, file_priv, false);
out_unlock:
mutex_unlock(&dev->master_mutex);
return ret;
@@ -223,14 +264,23 @@
int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
- int ret = -EINVAL;
+ int ret;
mutex_lock(&dev->master_mutex);
- if (!drm_is_current_master(file_priv))
+
+ ret = drm_master_check_perm(dev, file_priv);
+ if (ret)
goto out_unlock;
- if (!dev->master)
+ if (!drm_is_current_master(file_priv)) {
+ ret = -EINVAL;
goto out_unlock;
+ }
+
+ if (!dev->master) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
if (file_priv->master->lessor != NULL) {
DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
@@ -238,7 +288,6 @@
goto out_unlock;
}
- ret = 0;
drm_drop_master(dev, file_priv);
out_unlock:
mutex_unlock(&dev->master_mutex);
@@ -275,21 +324,7 @@
if (!drm_is_current_master(file_priv))
goto out;
- if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
- /*
- * 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);
- }
+ drm_legacy_lock_master_cleanup(dev, master);
if (dev->master == file_priv->master)
drm_drop_master(dev, file_priv);
@@ -344,9 +379,6 @@
if (drm_core_check_feature(dev, DRIVER_MODESET))
drm_lease_destroy(master);
- if (dev->driver->master_destroy)
- dev->driver->master_destroy(dev, master);
-
drm_legacy_master_rmmaps(dev, master);
idr_destroy(&master->magic_map);
@@ -369,3 +401,23 @@
*master = NULL;
}
EXPORT_SYMBOL(drm_master_put);
+
+/* Used by drm_client and drm_fb_helper */
+bool drm_master_internal_acquire(struct drm_device *dev)
+{
+ mutex_lock(&dev->master_mutex);
+ if (dev->master) {
+ mutex_unlock(&dev->master_mutex);
+ return false;
+ }
+
+ return true;
+}
+EXPORT_SYMBOL(drm_master_internal_acquire);
+
+/* Used by drm_client and drm_fb_helper */
+void drm_master_internal_release(struct drm_device *dev)
+{
+ mutex_unlock(&dev->master_mutex);
+}
+EXPORT_SYMBOL(drm_master_internal_release);
--
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