Re: [PATCH] drm/ioctl: Add a ioctl to label GEM objects

On 9/16/19 12:35 PM, Rohan Garg wrote:

DRM_IOCTL_BO_SET_LABEL lets you label GEM objects, making it easier to debug issues in userspace applications.

Signed-off-by: Rohan Garg rohan.garg@collabora.com

drivers/gpu/drm/drm_gem.c | 51 ++++++++++++++++++++++++++++++++++ drivers/gpu/drm/drm_internal.h | 2 ++ drivers/gpu/drm/drm_ioctl.c | 1 + include/drm/drm_gem.h | 7 +++++ include/uapi/drm/drm.h | 18 ++++++++++++ 5 files changed, 79 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 6854f5867d51..c116b242d679 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -941,6 +941,52 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private) idr_destroy(&file_private->object_idr); }

+/**

• • drm_gem_label - label a given GEM object
• • @dev: drm_device which is being closed by userspace

We're not closing a device, are we?

• • @data: drm_label_bo struct with a label, label length and any relevant flags
• • @file_private: drm file-private structure to clean up
• */

+int drm_gem_label(struct drm_device *dev, void *data,

•        struct drm_file *file_priv)
  

+{

• struct drm_label_object *args = data;
• struct drm_gem_object *gem_obj;
• int err = 0;
• if (!args->len || !args->name)

• return -EINVAL;
  

• gem_obj = drm_gem_object_lookup(file_priv, args->handle);
• if (!gem_obj) {

• DRM_ERROR("Failed to look up GEM BO %d\n", args->handle);
  

• err = -ENOENT;
  

• goto err;
  

• }
• if ((args->len == 0 && args->name == NULL) || gem_obj->label) {

• kfree(gem_obj->label);
  

• gem_obj->label = NULL;
  

• }
• gem_obj->label = strndup_user(u64_to_user_ptr(args->name), args->len);

Do we have a mechanism in place to stop a malicious unprivileged app from allocating all kernel memory to gem labels?

• drm_gem_object_put_unlocked(gem_obj);
• if (IS_ERR(gem_obj->label)) {

• err = PTR_ERR(gem_obj->label);
  

• goto err;
  

• }

+err:

• if (err != 0)

• args->flags = err;
  

• return err;

+}

• /**
  • drm_gem_object_release - release GEM buffer object resources
  • @obj: GEM buffer object

@@ -958,6 +1004,11 @@ drm_gem_object_release(struct drm_gem_object *obj)

dma_resv_fini(&obj->_resv); drm_gem_free_mmap_offset(obj);

• if (obj->label) {

• kfree(obj->label);
  

• obj->label = NULL;
  

• } } EXPORT_SYMBOL(drm_gem_object_release);

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index 51a2055c8f18..c9854b237fb6 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -137,6 +137,8 @@ int drm_gem_pin(struct drm_gem_object *obj); void drm_gem_unpin(struct drm_gem_object *obj); void *drm_gem_vmap(struct drm_gem_object *obj); void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr); +int drm_gem_label(struct drm_device *dev, void *data,

•        struct drm_file *file_priv);
  
  

  /* drm_debugfs.c drm_debugfs_crc.c */ #if defined(CONFIG_DEBUG_FS)

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index f675a3bb2c88..7b6f4b7dadb9 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -709,6 +709,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = { DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER), DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER), DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER),

• DRM_IOCTL_DEF(DRM_IOCTL_BO_SET_LABEL, drm_gem_label, DRM_RENDER_ALLOW),

Not all drivers use GEM. Could we have a struct drm_driver entry for this?

Thanks,

Thomas

};

#define DRM_CORE_IOCTL_COUNT ARRAY_SIZE( drm_ioctls ) diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 6aaba14f5972..f801c054e972 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -237,6 +237,13 @@ struct drm_gem_object { */ int name;

• /**

• * @label:
  

• *
  

• * Label for this object, should be a human readable string.
  

• */
  

• char *label;
• /**
  • @dma_buf:

diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 8a5b2f8f8eb9..286167f880de 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -626,6 +626,23 @@ struct drm_gem_open { __u64 size; };

+/** struct drm_label_object - ioctl argument for labelling BOs.

• • This label's a BO with a userspace label
• */

+struct drm_label_object {

• /** Handle for the object being labelled. */
• __u32 handle;
• /** Label and label length. */
• __u32 len;
• __u64 name;
• /** Flags */
• int flags;

+};

• #define DRM_CAP_DUMB_BUFFER 0x1 #define DRM_CAP_VBLANK_HIGH_CRTC 0x2 #define DRM_CAP_DUMB_PREFERRED_DEPTH 0x3

@@ -946,6 +963,7 @@ extern "C" { #define DRM_IOCTL_SYNCOBJ_QUERY DRM_IOWR(0xCB, struct drm_syncobj_timeline_array) #define DRM_IOCTL_SYNCOBJ_TRANSFER DRM_IOWR(0xCC, struct drm_syncobj_transfer) #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD, struct drm_syncobj_timeline_array) +#define DRM_IOCTL_BO_SET_LABEL DRM_IOWR(0xCE, struct drm_label_object)

/**

• Device specific ioctls should only be in their respective headers