Mastering Linux Kernel Development

Access control lists (ACLs)

The default file and directory access permissions that specify access rights for the owner, the group to which owner belongs, and others users does not offer fine-grained control required in some situations. ACLs are a feature that enable an extended mechanism to specify file access permissions for various processes and users. This feature considers all files and directories as objects, and allows system administrators to define a list of access permissions for each. ACLs include operations valid on an object with access privileges, and restrictions for each user and system process on a specified object.