Here is what I found from USCIS.GOV. Seem legal status is requir

A legal immigrant is a foreign national who has been granted the privilege of living and working permanently in the United States. There is a two-step process for your parent to become a legal immigrant. First, the USCIS must approve an immigrant visa petition that you file for your parent. Second, if your parent is outside the United States, your parent will be notified to go to the local U.S. consulate to complete the processing for an immigrant visa. If your parent is legally inside the U.S., he or she may apply to adjust his or her status to that of a lawful permanent resident using the Form I-485.