Uniting and Strengthening American Liberty Act of 2017 or the USA Liberty Act of 2017 This bill amends the Foreign Intelligence Surveillance Act of 1978 to allow the contents of communications by persons outside of the United States to be accessed if the Department of Justice (DOJ) determines there is probable cause to believe that those contents may provide evidence of a crime. Noncontent communication information may be accessed only if DOJ determines that the noncontent information is relevant to an authorized investigation or assessment. DOJ must establish specific procedures when unmasking information is requested. (Unmasking means providing the identity of a U.S. person mentioned in an intelligence report that contains a reference to the person but does not identify the person.) The National Security Act of 1947 is amended to prevent federal employees from taking any personnel action against a contractor employee who has made a lawful disclosure of information that the contractor employee believes provides evidence of a violation of federal law or mismanagement, a gross waste of funds, an abuse of authority, or a substantial and specific danger to public health or safety. The bill extends to September 30, 2023, the authorization of title VII of the Foreign Intelligence Surveillance Act (FISA), which allows DOJ and the Office of the Director of National Intelligence to jointly authorize the electronic surveillance of non-U.S. persons who are outside the United States. The bill increases the criminal penalty (from one to up to five years imprisonment) for knowingly removing classified information without authority and with intent to retain such information at an unauthorized location and imposes a criminal penalty of up to one year imprisonment for negligently removing such information. The bill directs the Government Accountability Office to study the unauthorized disclosure of classified information and the U.S. classification system.