Commit 5f776204 authored by Mary Guillemard's avatar Mary Guillemard Committed by Boris Brezillon
Browse files

drm/panthor: Restrict high priorities on group_create 

We were allowing any users to create a high priority group without any
permission checks. As a result, this was allowing possible denial of
service.

We now only allow the DRM master or users with the CAP_SYS_NICE
capability to set higher priorities than PANTHOR_GROUP_PRIORITY_MEDIUM.

As the sole user of that uAPI lives in Mesa and hardcode a value of
MEDIUM [1], this should be safe to do.

Additionally, as those checks are performed at the ioctl level,
panthor_group_create now only check for priority level validity.

[1]https://gitlab.freedesktop.org/mesa/mesa/-/blob/f390835074bdf162a63deb0311d1a6de527f9f89/src/gallium/drivers/panfrost/pan_csf.c#L1038



Signed-off-by: default avatarMary Guillemard <mary.guillemard@collabora.com>
Fixes: de854881 ("drm/panthor: Add the scheduler logical block")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240903144955.144278-2-mary.guillemard@collabora.com
parent 9a71cf8b

drivers/gpu/drm/panthor/panthor_drv.c

+23 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/platform_device.h>

#include <linux/pm_runtime.h>



#include <drm/drm_auth.h>

#include <drm/drm_debugfs.h>

#include <drm/drm_drv.h>

#include <drm/drm_exec.h>
@@ -996,6 +997,24 @@ static int panthor_ioctl_group_destroy(struct drm_device *ddev, void *data, 
	return panthor_group_destroy(pfile, args->group_handle);

}



static int group_priority_permit(struct drm_file *file,

				 u8 priority)

{

	/* Ensure that priority is valid */

	if (priority > PANTHOR_GROUP_PRIORITY_HIGH)

		return -EINVAL;



	/* Medium priority and below are always allowed */

	if (priority <= PANTHOR_GROUP_PRIORITY_MEDIUM)

		return 0;



	/* Higher priorities require CAP_SYS_NICE or DRM_MASTER */

	if (capable(CAP_SYS_NICE) || drm_is_current_master(file))

		return 0;



	return -EACCES;

}



static int panthor_ioctl_group_create(struct drm_device *ddev, void *data,

				      struct drm_file *file)

{
@@ -1011,6 +1030,10 @@ static int panthor_ioctl_group_create(struct drm_device *ddev, void *data, 
	if (ret)

		return ret;



	ret = group_priority_permit(file, args->priority);

	if (ret)

		return ret;



	ret = panthor_group_create(pfile, args, queue_args);

	if (ret >= 0) {

		args->group_handle = ret;

drivers/gpu/drm/panthor/panthor_sched.c

+1 −1
Original line number Diff line number Diff line
@@ -3092,7 +3092,7 @@ int panthor_group_create(struct panthor_file *pfile, 
	if (group_args->pad)

		return -EINVAL;



	if (group_args->priority > PANTHOR_CSG_PRIORITY_HIGH)

	if (group_args->priority >= PANTHOR_CSG_PRIORITY_COUNT)

		return -EINVAL;



	if ((group_args->compute_core_mask & ~ptdev->gpu_info.shader_present) ||

include/uapi/drm/panthor_drm.h

+5 −1
Original line number Diff line number Diff line
@@ -692,7 +692,11 @@ enum drm_panthor_group_priority { 
	/** @PANTHOR_GROUP_PRIORITY_MEDIUM: Medium priority group. */

	PANTHOR_GROUP_PRIORITY_MEDIUM,



	/** @PANTHOR_GROUP_PRIORITY_HIGH: High priority group. */

	/**

	 * @PANTHOR_GROUP_PRIORITY_HIGH: High priority group.

	 *

	 * Requires CAP_SYS_NICE or DRM_MASTER.

	 */

	PANTHOR_GROUP_PRIORITY_HIGH,

};