Re: [RFC 1/2] vduse: validate block features only with block devices

[Jason Wang]

On Wed, Apr 19, 2023 at 9:43 PM Maxime Coquelin
<maxime.coquelin@xxxxxxxxxx> wrote:
>
> This patch is preliminary work to enable network device
> type support to VDUSE.
>
> As VIRTIO_BLK_F_CONFIG_WCE shares the same value as
> VIRTIO_NET_F_HOST_TSO4, we need to restrict its check
> to Virtio-blk device type.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@xxxxxxxxxx>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 0c3b48616a9f..6fa598a03d8e 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1416,13 +1416,14 @@ static bool device_is_allowed(u32 device_id)
>         return false;
>  }
>
> -static bool features_is_valid(u64 features)
> +static bool features_is_valid(struct vduse_dev_config *config)
>  {
> -       if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))
> +       if (!(config->features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))
>                 return false;
>
>         /* Now we only support read-only configuration space */
> -       if (features & (1ULL << VIRTIO_BLK_F_CONFIG_WCE))
> +       if ((config->device_id == VIRTIO_ID_BLOCK) &&
> +                       (config->features & (1ULL << VIRTIO_BLK_F_CONFIG_WCE)))

The reason we filter WCE out is to avoid writable config space which
might block the driver with a buggy userspace.

For networking, I guess we should fail if VERSION_1 is not negotiated,
then we can avoid setting mac addresses via the config space.

Thanks

>                 return false;
>
>         return true;
> @@ -1446,7 +1447,7 @@ static bool vduse_validate_config(struct vduse_dev_config *config)
>         if (!device_is_allowed(config->device_id))
>                 return false;
>
> -       if (!features_is_valid(config->features))
> +       if (!features_is_valid(config))
>                 return false;
>
>         return true;
> --
> 2.39.2
>