What are the differences between Windows and Linux access control lists?

Answer 1

In Windows, files have an owner (usually the creator), but not a group, to which they 'belong'. - and the owner isn't really important in determining access rights. Files either have an explicit list of people and groups or inherit it from a parent directory. These lists specify individual users and groups (in a list) who have access to the directory/file/subdirectories, and the specific rights granted to each item.

In Unix/Linux, each file and directory belongs to a specific user AND group - for example, configuration files may belong to user root and a group set up for administrators (typically called 'wheel'). Instead of having a list of people who can/cannot access the file, you simply specify read, write and execute privileges for the owner and group the file belongs to, and then anyone else.

In Windows, if you have a configuration file, the owner doesn't matter. Instead you set the ACL to include any Administrators you want to access the file, as well as any other users that may need to read it, including the program it configures.

In Linux, you'd perhaps set the same configuration file to belong to the root user, and the group to which the configured program runs in, and everyone to no rights at all - so only root and the program can read it. Or you could set the owner to the user the program runs under and the group that the Administrators belong to, so the program can read it and so that Administrators et.al. can change the file, but keep everyone set to no rights to keep the configuration secure.

They are two different ways of accomplishing security, each with their own configuration peculiarities and performance issues.

Answer 2

As far as I know, there is no difference. File permissions in filesystems are determined by the filesystem, not the operating system. File permissions and properties are stored as filesystem metadata, not as information in the file itself. This includes most security features such as access control lists and mandatory access control labels.

Linux, however, migh "map" the permissions NTFS describes for a file into the standard owner/group/other read/write/execute permission model as an absctraction, but no one in their right mind would cause NTFS's metadata format to change and expect Windows to be able to read the filesystem afterward, so likely this view of the permissions in Linux doesn't really resemble the way the permissions are stored in filesystem metadata.