On Tue, Nov 05, 2024 at 03:25:26PM +0800, Cindy Lu wrote:
> Add a new UAPI to enable setting the vhost device to task mode.
> The userspace application can use VHOST_SET_INHERIT_FROM_OWNER
> to configure the mode if necessary.
> This setting must be applied before VHOST_SET_OWNER, as the worker
> will be created in the VHOST_SET_OWNER function
>
> Signed-off-by: Cindy Lu <l...@redhat.com>
> ---
> drivers/vhost/vhost.c | 15 ++++++++++++++-
> include/uapi/linux/vhost.h | 2 ++
> 2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index c17dc01febcc..70c793b63905 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -2274,8 +2274,9 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int
> ioctl, void __user *argp)
> {
> struct eventfd_ctx *ctx;
> u64 p;
> - long r;
> + long r = 0;
> int i, fd;
> + bool inherit_owner;
>
> /* If you are not the owner, you can become one */
> if (ioctl == VHOST_SET_OWNER) {
> @@ -2332,6 +2333,18 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int
> ioctl, void __user *argp)
> if (ctx)
> eventfd_ctx_put(ctx);
> break;
> + case VHOST_SET_INHERIT_FROM_OWNER:
> + /*inherit_owner can only be modified before owner is set*/
bad coding style
> + if (vhost_dev_has_owner(d))
> + break;
is this silently failing? should return EBUSY or something like this.
> +
> + if (copy_from_user(&inherit_owner, argp,
> + sizeof(inherit_owner))) {
not good,
> + r = -EFAULT;
> + break;
> + }
> + d->inherit_owner = inherit_owner;
> + break;
> default:
> r = -ENOIOCTLCMD;
> break;
This means any task can break out of jail
and steal root group system time by setting inherit_owner to 0
even if system is configured to inherit by default.
we need a modparam to block this.
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index b95dd84eef2d..1e192038633d 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -235,4 +235,6 @@
> */
> #define VHOST_VDPA_GET_VRING_SIZE _IOWR(VHOST_VIRTIO, 0x82, \
> struct vhost_vring_state)
> +
> +#define VHOST_SET_INHERIT_FROM_OWNER _IOW(VHOST_VIRTIO, 0x83, bool)
do not put bool in interfaces. something like u8 and validate it is 0 or
1.
> #endif
> --
> 2.45.0
