Re: [PATCH v3 7/9] vhost: Add new UAPI to support change to task mode
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2024-11-06 07:33:00
Also in:
lkml, virtualization
On Tue, Nov 05, 2024 at 03:25:26PM +0800, Cindy Lu wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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.
quoted hunk ↗ jump to hunk
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