On Fri, Jun 19, 2015 at 02:52:28PM +0100, Daniel Thompson wrote:
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.
Signed-off-by: Daniel Thompson daniel.thompson@linaro.org
drivers/gpu/drm/drm_prime.c | 9 +++------ include/uapi/drm/drm.h | 1 + 2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 7fec191b45f7..6d2cf4fb4038 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -331,7 +331,7 @@ 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.
@@ -639,14 +639,11 @@ 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;
I think we should reject DRM_RDWR if there's no mmap implementation in the underlying dma-buf vfunc table. Or in the gem version of those. Otherwise looks ok to me, if we first resolve the dma-buf userspace mmap coherency issue. -Daniel
- /* 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, diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index ff6ef62d084b..092fe3fa8ec0 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -668,6 +668,7 @@ struct drm_set_client_cap { __u64 value; }; +#define DRM_RDWR O_RDWR #define DRM_CLOEXEC O_CLOEXEC struct drm_prime_handle { __u32 handle; -- 2.4.3
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