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Commit c996fd0b authored by Thomas Hellstrom's avatar Thomas Hellstrom
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drm: Protect the master management with a drm_device::master_mutex v3 

The master management was previously protected by the drm_device::struct_mutex.
In order to avoid locking order violations in a reworked dropped master
security check in the vmwgfx driver, break it out into a separate master_mutex.
Locking order is master_mutex -> struct_mutex.

Also remove drm_master::blocked since it's not used.

v2: Add an inline comment about what drm_device::master_mutex is protecting.
v3: Remove unneeded struct_mutex locks. Fix error returns in
    drm_setmaster_ioctl().
Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: default avatarBrian Paul <brianp@vmware.com>
Reviewed-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Acked-by: default avatarDaniel Vetter <daniel@ffwll.ch>
parent a12cd002
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Showing with 64 additions and 47 deletions
drivers/gpu/drm/drm_fops.c
View file @ c996fd0b
......@@ -231,12 +231,11 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
/* if there is no current master make this fd it, but do not create
* any master object for render clients */
mutex_lock(&dev->struct_mutex);
mutex_lock(&dev->master_mutex);
if (drm_is_primary_client(priv) && !priv->minor->master) {
/* create a new master */
priv->minor->master = drm_master_create(priv->minor);
if (!priv->minor->master) {
mutex_unlock(&dev->struct_mutex);
ret = -ENOMEM;
goto out_close;
}
......@@ -244,29 +243,23 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
priv->is_master = 1;
/* take another reference for the copy in the local file priv */
priv->master = drm_master_get(priv->minor->master);
priv->authenticated = 1;
mutex_unlock(&dev->struct_mutex);
if (dev->driver->master_create) {
ret = dev->driver->master_create(dev, priv->master);
if (ret) {
mutex_lock(&dev->struct_mutex);
/* drop both references if this fails */
drm_master_put(&priv->minor->master);
drm_master_put(&priv->master);
mutex_unlock(&dev->struct_mutex);
goto out_close;
}
}
mutex_lock(&dev->struct_mutex);
if (dev->driver->master_set) {
ret = dev->driver->master_set(dev, priv, true);
if (ret) {
/* drop both references if this fails */
drm_master_put(&priv->minor->master);
drm_master_put(&priv->master);
mutex_unlock(&dev->struct_mutex);
goto out_close;
}
}
......@@ -274,7 +267,7 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
/* get a reference to the master */
priv->master = drm_master_get(priv->minor->master);
}
mutex_unlock(&dev->struct_mutex);
mutex_unlock(&dev->master_mutex);
mutex_lock(&dev->struct_mutex);
list_add(&priv->lhead, &dev->filelist);
......@@ -302,6 +295,7 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
return 0;
out_close:
mutex_unlock(&dev->master_mutex);
if (dev->driver->postclose)
dev->driver->postclose(dev, priv);
out_prime_destroy:
......@@ -489,11 +483,13 @@ int drm_release(struct inode *inode, struct file *filp)
}
mutex_unlock(&dev->ctxlist_mutex);
mutex_lock(&dev->struct_mutex);
mutex_lock(&dev->master_mutex);
if (file_priv->is_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))
......@@ -512,6 +508,7 @@ int drm_release(struct inode *inode, struct file *filp)
master->lock.file_priv = NULL;
wake_up_interruptible_all(&master->lock.lock_queue);
}
mutex_unlock(&dev->struct_mutex);
if (file_priv->minor->master == file_priv->master) {
/* drop the reference held my the minor */
......@@ -521,10 +518,13 @@ int drm_release(struct inode *inode, struct file *filp)
}
}
/* drop the reference held my the file priv */
/* drop the master reference held by the file priv */
if (file_priv->master)
drm_master_put(&file_priv->master);
file_priv->is_master = 0;
mutex_unlock(&dev->master_mutex);
mutex_lock(&dev->struct_mutex);
list_del(&file_priv->lhead);
mutex_unlock(&dev->struct_mutex);
......
drivers/gpu/drm/drm_stub.c
View file @ c996fd0b
......@@ -144,6 +144,7 @@ static void drm_master_destroy(struct kref *kref)
struct drm_device *dev = master->minor->dev;
struct drm_map_list *r_list, *list_temp;
mutex_lock(&dev->struct_mutex);
if (dev->driver->master_destroy)
dev->driver->master_destroy(dev, master);
......@@ -171,6 +172,7 @@ static void drm_master_destroy(struct kref *kref)
drm_ht_remove(&master->magiclist);
mutex_unlock(&dev->struct_mutex);
kfree(master);
}
......@@ -186,19 +188,20 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
{
int ret = 0;
mutex_lock(&dev->master_mutex);
if (file_priv->is_master)
return 0;
if (file_priv->minor->master && file_priv->minor->master != file_priv->master)
return -EINVAL;
goto out_unlock;
if (!file_priv->master)
return -EINVAL;
if (file_priv->minor->master) {
ret = -EINVAL;
goto out_unlock;
}
if (file_priv->minor->master)
return -EINVAL;
if (!file_priv->master) {
ret = -EINVAL;
goto out_unlock;
}
mutex_lock(&dev->struct_mutex);
file_priv->minor->master = drm_master_get(file_priv->master);
file_priv->is_master = 1;
if (dev->driver->master_set) {
......@@ -208,27 +211,33 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
drm_master_put(&file_priv->minor->master);
}
}
mutex_unlock(&dev->struct_mutex);
out_unlock:
mutex_unlock(&dev->master_mutex);
return ret;
}
int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
int ret = -EINVAL;
mutex_lock(&dev->master_mutex);
if (!file_priv->is_master)
return -EINVAL;
goto out_unlock;
if (!file_priv->minor->master)
return -EINVAL;
goto out_unlock;
mutex_lock(&dev->struct_mutex);
ret = 0;
if (dev->driver->master_drop)
dev->driver->master_drop(dev, file_priv, false);
drm_master_put(&file_priv->minor->master);
file_priv->is_master = 0;
mutex_unlock(&dev->struct_mutex);
return 0;
out_unlock:
mutex_unlock(&dev->master_mutex);
return ret;
}
/*
......@@ -559,6 +568,7 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
spin_lock_init(&dev->event_lock);
mutex_init(&dev->struct_mutex);
mutex_init(&dev->ctxlist_mutex);
mutex_init(&dev->master_mutex);
dev->anon_inode = drm_fs_inode_new();
if (IS_ERR(dev->anon_inode)) {
......@@ -612,6 +622,7 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
drm_minor_free(dev, DRM_MINOR_CONTROL);
drm_fs_inode_free(dev->anon_inode);
err_free:
mutex_destroy(&dev->master_mutex);
kfree(dev);
return NULL;
}
......@@ -633,6 +644,8 @@ static void drm_dev_release(struct kref *ref)
drm_minor_free(dev, DRM_MINOR_CONTROL);
kfree(dev->devname);
mutex_destroy(&dev->master_mutex);
kfree(dev);
}
......
include/drm/drmP.h
View file @ c996fd0b
......@@ -405,7 +405,8 @@ struct drm_prime_file_private {
struct drm_file {
unsigned always_authenticated :1;
unsigned authenticated :1;
unsigned is_master :1; /* this file private is a master for a minor */
/* Whether we're master for a minor. Protected by master_mutex */
unsigned is_master :1;
/* true when the client has asked us to expose stereo 3D mode flags */
unsigned stereo_allowed :1;
......@@ -684,28 +685,29 @@ struct drm_gem_object {
#include <drm/drm_crtc.h>
/* per-master structure */
/**
* struct drm_master - drm master structure
*
* @refcount: Refcount for this master object.
* @minor: Link back to minor char device we are master for. Immutable.
* @unique: Unique identifier: e.g. busid. Protected by drm_global_mutex.
* @unique_len: Length of unique field. Protected by drm_global_mutex.
* @unique_size: Amount allocated. Protected by drm_global_mutex.
* @magiclist: Hash of used authentication tokens. Protected by struct_mutex.
* @magicfree: List of used authentication tokens. Protected by struct_mutex.
* @lock: DRI lock information.
* @driver_priv: Pointer to driver-private information.
*/
struct drm_master {
struct kref refcount; /* refcount for this master */
struct drm_minor *minor; /**< link back to minor we are a master for */
char *unique; /**< Unique identifier: e.g., busid */
int unique_len; /**< Length of unique field */
int unique_size; /**< amount allocated */
int blocked; /**< Blocked due to VC switch? */
/** \name Authentication */
/*@{ */
struct kref refcount;
struct drm_minor *minor;
char *unique;
int unique_len;
int unique_size;
struct drm_open_hash magiclist;
struct list_head magicfree;
/*@} */
struct drm_lock_data lock; /**< Information on hardware lock */
void *driver_priv; /**< Private structure for driver to use */
struct drm_lock_data lock;
void *driver_priv;
};
/* Size of ringbuffer for vblank timestamps. Just double-buffer
......@@ -1020,7 +1022,8 @@ struct drm_minor {
struct list_head debugfs_list;
struct mutex debugfs_lock; /* Protects debugfs_list. */
struct drm_master *master; /* currently active master for this node */
/* currently active master for this node. Protected by master_mutex */
struct drm_master *master;
struct drm_mode_group mode_group;
};
......@@ -1070,6 +1073,7 @@ struct drm_device {
/*@{ */
spinlock_t count_lock; /**< For inuse, drm_device::open_count, drm_device::buf_use */
struct mutex struct_mutex; /**< For others */
struct mutex master_mutex; /**< For drm_minor::master and drm_file::is_master */
/*@} */
/** \name Usage Counters */
......
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