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drm: prime: Honour O_RDWR during prime-handle-to-fd 

Currently DRM_IOCTL_PRIME_HANDLE_TO_FD rejects all flags except
(DRM|O)_CLOEXEC making it difficult (maybe impossible) for userspace
to mmap() the resulting dma-buf even when this is supported by the
DRM driver.

It is trivial to relax the restriction and permit read/write access.
This is safe because the flags are seldom touched by drm; mostly they
are passed verbatim to dma_buf calls.

v3 (Tiago): removed unused flags variable from drm_prime_handle_to_fd_ioctl.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1450820214-12509-2-git-send-email-tiago.vignatti@intel.com
This commit is contained in:
Daniel Thompson 2015-12-22 19:36:44 -02:00 committed by Daniel Vetter
parent 10c1b6183a
commit bfe981a095
2 changed files with 4 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/gpu/drm/drm_prime.c
View File

@ -329,7 +329,7 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
* drm_gem_prime_export - helper library implementation of the export callback
* @dev: drm_device to export from
* @obj: GEM object to export
* @flags: flags like DRM_CLOEXEC
* @flags: flags like DRM_CLOEXEC and DRM_RDWR
*
* This is the implementation of the gem_prime_export functions for GEM drivers
* using the PRIME helpers.
@ -628,7 +628,6 @@ int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_prime_handle *args = data;
uint32_t flags;
if (!drm_core_check_feature(dev, DRIVER_PRIME))
return -EINVAL;
@ -637,14 +636,11 @@ int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
return -ENOSYS;
/* check flags are valid */
if (args->flags & ~DRM_CLOEXEC)
if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
return -EINVAL;
/* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
flags = args->flags & DRM_CLOEXEC;
return dev->driver->prime_handle_to_fd(dev, file_priv,
args->handle, flags, &args->fd);
args->handle, args->flags, &args->fd);
}
int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,

1
include/uapi/drm/drm.h
View File

@ -669,6 +669,7 @@ struct drm_set_client_cap {
__u64 value;
};
#define DRM_RDWR O_RDWR
#define DRM_CLOEXEC O_CLOEXEC
struct drm_prime_handle {
__u32 handle;