Chapter 6. Confining Users

6.1. Linux and SELinux User Mappings
6.2. Confining New Linux Users: useradd
6.3. Confining Existing Linux Users: semanage login
6.4. Changing the Default Mapping
6.5. xguest: Kiosk Mode
6.6. Booleans for Users Executing Applications

A number of confined SELinux users are available in Fedora 12. Each Linux user is mapped to an SELinux user via SELinux policy, allowing Linux users to inherit the restrictions placed on SELinux users, for example (depending on the user), not being able to: run the X Window System; use networking; run setuid applications (unless SELinux policy permits it); or run the su and sudo commands. This helps protect the system from the user. Refer to Section 4.3, “Confined and Unconfined Users” for further information about confined users.

6.1. Linux and SELinux User Mappings

As the Linux root user, run the semanage login -l command to view the mapping between Linux users and SELinux users:

# /usr/sbin/semanage login -l

Login Name                SELinux User              MLS/MCS Range

__default__               unconfined_u              s0-s0:c0.c1023
root                      unconfined_u              s0-s0:c0.c1023
system_u                  system_u                  s0-s0:c0.c1023

In Fedora 12, Linux users are mapped to the SELinux __default__ login by default (which is in turn mapped to the SELinux unconfined_u user). When a Linux user is created with the useradd command, if no options are specified, they are mapped to the SELinux unconfined_u user. The following defines the default-mapping:

__default__               unconfined_u              s0-s0:c0.c1023