In a nested VM environment, we have to refuse to assign to a nested guest the same CID assigned to our guest->host transport. In this way, the user can use the local CID for loopback. Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> --- drivers/vhost/vsock.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index fdda9ec625ad..dde392b91bb3 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -718,6 +718,12 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid) if (guest_cid > U32_MAX) return -EINVAL; + /* Refuse if CID is assigned to the guest->host transport (i.e. nested + * VM), to make the loopback work. + */ + if (vsock_find_cid(guest_cid)) + return -EADDRINUSE; + /* Refuse if CID is already in use */ mutex_lock(&vhost_vsock_mutex); other = vhost_vsock_get(guest_cid); -- 2.21.0
