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Message-ID: <20240903144955.144278-2-mary.guillemard@collabora.com>
Date: Tue, 3 Sep 2024 16:49:55 +0200
From: Mary Guillemard <mary.guillemard@...labora.com>
To: linux-kernel@...r.kernel.org
Cc: kernel@...labora.com,
Mary Guillemard <mary.guillemard@...labora.com>,
stable@...r.kernel.org,
Boris Brezillon <boris.brezillon@...labora.com>,
Steven Price <steven.price@....com>,
Liviu Dudau <liviu.dudau@....com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Heiko Stuebner <heiko@...ech.de>,
dri-devel@...ts.freedesktop.org
Subject: [PATCH] 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: Mary Guillemard <mary.guillemard@...labora.com>
Fixes: de8548813824 ("drm/panthor: Add the scheduler logical block")
Cc: stable@...r.kernel.org
---
drivers/gpu/drm/panthor/panthor_drv.c | 23 +++++++++++++++++++++++
drivers/gpu/drm/panthor/panthor_sched.c | 2 +-
include/uapi/drm/panthor_drm.h | 6 +++++-
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
index b5e7b919f241..34182f67136c 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -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;
diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
index c426a392b081..91a31b70c037 100644
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -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) ||
diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
index 926b1deb1116..e23a7f9b0eac 100644
--- a/include/uapi/drm/panthor_drm.h
+++ b/include/uapi/drm/panthor_drm.h
@@ -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,
};
base-commit: a15710027afb40c7c1e352902fa5b8c949f021de
--
2.46.0
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