Skip to content

Commit

Permalink
drm/panthor: Restrict high priorities on group_create
Browse files Browse the repository at this point in the history
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: Mary Guillemard <[email protected]>
Fixes: de85488 ("drm/panthor: Add the scheduler logical block")
Cc: [email protected]
Reviewed-by: Boris Brezillon <[email protected]>
Signed-off-by: Boris Brezillon <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
  • Loading branch information
marysaka authored and igorpecovnik committed Oct 9, 2024
1 parent 8a730fd commit cbd34d0
Show file tree
Hide file tree
Showing 3 changed files with 29 additions and 2 deletions.
23 changes: 23 additions & 0 deletions drivers/gpu/drm/panthor/panthor_drv.c
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>

#include <drm/drm_auth.h>
#include <drm/drm_drv.h>
#include <drm/drm_exec.h>
#include <drm/drm_ioctl.h>
Expand Down Expand Up @@ -995,6 +996,24 @@ 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)
{
Expand All @@ -1010,6 +1029,10 @@ 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;
Expand Down
2 changes: 1 addition & 1 deletion drivers/gpu/drm/panthor/panthor_sched.c
Original file line number Diff line number Diff line change
Expand Up @@ -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) ||
Expand Down
6 changes: 5 additions & 1 deletion include/uapi/drm/panthor_drm.h
Original file line number Diff line number Diff line change
Expand Up @@ -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,
};

Expand Down

0 comments on commit cbd34d0

Please sign in to comment.