What is the security of the file, how to achieve the protection of the file, try to enumerate a implementation of the scheme and explain it?

To achieve file sharing, the file system must provide file protection, which provides measures to protect file security. The protection of the file system is mainly to prevent unauthorized users from destroying and attacking the file.

The protection of files can be achieved through user-oriented access control and data-oriented access control.

For example, the user is required to enter the user name and user password at logon to complete authentication of the user identity.

When the user proposes an action on a file, it is necessary to verify that the user has the appropriate permissions for the file, that is, to complete the access control of the file.

What is the security of the file, how to achieve the protection of the file, try to enumerate a implementation of the scheme and explain it?