Hi Zivi,
On 5/8/26 18:28, Ziyi Guo wrote:
> Userptr BOs wrap pinned user pages in a private dma-buf solely for
> internal use by the NPU driver. Allowing userspace to re-export such a
> BO via DRM_IOCTL_PRIME_HANDLE_TO_FD would expose those pages to other
> drivers through an interface that was never intended to be shared.
>
> Override the driver's prime_handle_to_fd callback to detect dma-bufs
> backed by ivpu_gem_userptr_dmabuf_ops and reject the export with
> -EINVAL.
>
> Signed-off-by: Ziyi Guo <[email protected]>
first of all thanks a lot for pointing that out! The patch which orginally
added that somehow slipped through the cracks.
Then @Karol and @Jacek, using DMA-buf like that is a pretty big NO-GO from the
DMA-buf side!
Using page which you don't own (especially file system backend ones) in a
DMA-buf is absolutely *NOT* something you can do.
I hope that it is not the case here, but if you also allow to mmap() them then
you have create a massive security problem which can lead to random file system
corruptions.
Regards,
Christian.
> ---
> drivers/accel/ivpu/ivpu_drv.c | 1 +
> drivers/accel/ivpu/ivpu_gem.c | 28 +++++++++++++++++++++++++++
> drivers/accel/ivpu/ivpu_gem.h | 3 +++
> drivers/accel/ivpu/ivpu_gem_userptr.c | 5 +++++
> 4 files changed, 37 insertions(+)
>
> diff --git a/drivers/accel/ivpu/ivpu_drv.c b/drivers/accel/ivpu/ivpu_drv.c
> index 2801378e3e19..086d4c769b33 100644
> --- a/drivers/accel/ivpu/ivpu_drv.c
> +++ b/drivers/accel/ivpu/ivpu_drv.c
> @@ -545,6 +545,7 @@ static const struct drm_driver driver = {
>
> .gem_create_object = ivpu_gem_create_object,
> .gem_prime_import = ivpu_gem_prime_import,
> + .prime_handle_to_fd = ivpu_gem_prime_handle_to_fd,
>
> .ioctls = ivpu_drm_ioctls,
> .num_ioctls = ARRAY_SIZE(ivpu_drm_ioctls),
> diff --git a/drivers/accel/ivpu/ivpu_gem.c b/drivers/accel/ivpu/ivpu_gem.c
> index 4f2005a8d496..82079f372b39 100644
> --- a/drivers/accel/ivpu/ivpu_gem.c
> +++ b/drivers/accel/ivpu/ivpu_gem.c
> @@ -12,6 +12,7 @@
> #include <drm/drm_cache.h>
> #include <drm/drm_debugfs.h>
> #include <drm/drm_file.h>
> +#include <drm/drm_prime.h>
> #include <drm/drm_utils.h>
>
> #include "ivpu_drv.h"
> @@ -249,6 +250,33 @@ struct drm_gem_object *ivpu_gem_prime_import(struct
> drm_device *dev,
> return ERR_PTR(ret);
> }
>
> +int ivpu_gem_prime_handle_to_fd(struct drm_device *dev, struct drm_file
> *file_priv,
> + u32 handle, u32 flags, int *prime_fd)
> +{
> + struct ivpu_device *vdev = to_ivpu_device(dev);
> + struct dma_buf *dmabuf;
> + int fd;
> +
> + dmabuf = drm_gem_prime_handle_to_dmabuf(dev, file_priv, handle,
> flags);
> + if (IS_ERR(dmabuf))
> + return PTR_ERR(dmabuf);
> +
> + if (ivpu_gem_is_userptr_dma_buf(dmabuf)) {
> + ivpu_dbg(vdev, IOCTL, "Exporting userptr BO is not
> allowed\n");
> + dma_buf_put(dmabuf);
> + return -EINVAL;
> + }
> +
> + fd = dma_buf_fd(dmabuf, flags);
> + if (fd < 0) {
> + dma_buf_put(dmabuf);
> + return fd;
> + }
> +
> + *prime_fd = fd;
> + return 0;
> +}
> +
> static struct ivpu_bo *ivpu_bo_alloc(struct ivpu_device *vdev, u64 size, u32
> flags)
> {
> struct drm_gem_shmem_object *shmem;
> diff --git a/drivers/accel/ivpu/ivpu_gem.h b/drivers/accel/ivpu/ivpu_gem.h
> index 0c3350f22b55..bfd15ce02354 100644
> --- a/drivers/accel/ivpu/ivpu_gem.h
> +++ b/drivers/accel/ivpu/ivpu_gem.h
> @@ -29,6 +29,9 @@ void ivpu_bo_unbind_all_bos_from_context(struct ivpu_device
> *vdev, struct ivpu_m
>
> struct drm_gem_object *ivpu_gem_create_object(struct drm_device *dev, size_t
> size);
> struct drm_gem_object *ivpu_gem_prime_import(struct drm_device *dev, struct
> dma_buf *dma_buf);
> +int ivpu_gem_prime_handle_to_fd(struct drm_device *dev, struct drm_file
> *file_priv,
> + u32 handle, u32 flags, int *prime_fd);
> +bool ivpu_gem_is_userptr_dma_buf(struct dma_buf *dma_buf);
> struct ivpu_bo *ivpu_bo_create(struct ivpu_device *vdev, struct
> ivpu_mmu_context *ctx,
> struct ivpu_addr_range *range, u64 size, u32
> flags);
> struct ivpu_bo *ivpu_bo_create_runtime(struct ivpu_device *vdev, u64 addr,
> u64 size, u32 flags);
> diff --git a/drivers/accel/ivpu/ivpu_gem_userptr.c
> b/drivers/accel/ivpu/ivpu_gem_userptr.c
> index 7cbf3a4cdc73..45eabea5961e 100644
> --- a/drivers/accel/ivpu/ivpu_gem_userptr.c
> +++ b/drivers/accel/ivpu/ivpu_gem_userptr.c
> @@ -61,6 +61,11 @@ static const struct dma_buf_ops
> ivpu_gem_userptr_dmabuf_ops = {
> .release = ivpu_gem_userptr_dmabuf_release,
> };
>
> +bool ivpu_gem_is_userptr_dma_buf(struct dma_buf *dma_buf)
> +{
> + return dma_buf->ops == &ivpu_gem_userptr_dmabuf_ops;
> +}
> +
> static struct dma_buf *
> ivpu_create_userptr_dmabuf(struct ivpu_device *vdev, void __user *user_ptr,
> size_t size, uint32_t flags)
> --
> 2.34.1
>
