Study the three policy types of SELinux

SELinux (Security-Enhanced Linux) is a security subsystem in the Linux system. It provides an access control security mechanism to restrict programs and users through mandatory access control (MAC). behavior to improve system security. The core of SELinux is a policy-based mechanism, which can control different access permissions through different types of policies.

In SELinux, there are three main policy types, including: role-based access control (RBAC), type-based access control (TE), and attribute-based access control (MLS). These three strategy types will be analyzed below, with corresponding code examples attached.

1. Role-based access control (RBAC):
   Role-based access control is a basic policy type in SELinux, which gives different permissions by defining different roles. Each role can have a series of permissions, and users are granted corresponding permissions based on their roles. Through role-based access control, more fine-grained permission control can be achieved.

Sample code:

# 定义一个名为admin的角色
semanage login -a -s admin admin_user

# 将角色admin授予能够访问某个文件的权限
chcon -R -t admin_t /path/to/file

2. Type-based access control (TE):
   Type-based access control is another policy type in SELinux, which Mainly by defining different object types to control access permissions between different objects. Each object type has its corresponding access rules, and the principals that are allowed to access that object type. Through type-based access control, access control to different objects such as files and processes can be achieved.

Sample code:

# 定义一个名为myapp的类型
semanage fcontext -a -t myapp_exec_t /path/to/myapp

# 将myapp_exec_t类型赋予myapp进程的权限
allow myapp_t myapp_exec_t: file { execute }

3. Attribute-based access control (MLS):
   Attribute-based access control is the most strict and flexible policy in SELinux Type, which mainly controls access permissions by defining the security level attribute of the object. Each object has its corresponding security level label, and only matching principals can access the object. MLS policy types are usually used in scenarios that require strict protection of information, such as military, government and other fields.

Sample code:

# 为文件设置MLS级别属性
chcon unconfined_u:system_r:unconfined_t:s0-s0:c0.c1023 /path/to/file

# 检查MLS级别属性
ls -Z /path/to/file

Through the above code examples, you can better understand the application methods and control principles of different policy types in SELinux. Different policy types can be selected and configured according to actual needs to achieve system security protection and access control. SELinux policy types not only provide comprehensive security protection, but also provide system administrators with more flexibility and customizability, helping them better manage and protect the system.

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