There are many embedded solution for guaranteeing Access Control (Mandatory or Role-Based) in Linux:

1. TOMOYO Linux: initially developed by NTT Data. Inside Kenel from 2.6.30
2. SELinux
3. AppArmor: initially developed by Novell. Indice SuSe Linux
4. LIDS
5. grSecurity

• WHO:  from the perspective of subjects (processes)
• WHERE: in the kernel, in order to not be bypassed by errors and improper configurations

1. Kernel functions