What is Linux Context?

anonymous·2023년 2월 7일

In the context of Linux systems, a security context refers to a set of security-related attributes that are assigned to a file, process, or other system object. The security context typically includes information about the user and group ownership of the object, as well as the security level or "type" assigned to the object.

SELinuxa Features

Label and categorize system objects
Define policies to dictate allowed operations

In SELinux (Security-Enhanced Linux), which is a popular implementation of mandatory access control (MAC) in the Linux kernel, security contexts are used to enforce security policies that govern the behavior of processes and system objects. SELinux provides a way to label and categorize system objects, and to define policies that dictate which operations are allowed and which are denied for each type of object.

Example file with context

system_u:object_r:postfix_etc_t:s0

system_u : belong to system user
object_r : read permission for the object role
postfix_etc_t : is of type postfix_etc_t
s0 : with a sensitivity level of s0

These labels help to enforce SELinux policies that prevent unauthorized access to sensitive system resources.

In summary, security contexts provide an additional layer of security beyond traditional file and process permissions, helping to enforce more fine-grained and comprehensive security policies on a Linux system.

How do I change Context?

# check context
ls -Z

# change context
sudo chcon -R system_u:object_r:postfix_etc_t:s0 /path/to/ssl

This will set the context of the ssl folder and all its contents to system_u:object_r:postfix_etc_t:s0.
The -R option is used to apply the context change recursively to the entire folder, including any subdirectories and files within it.

Note that the actual context that you should use for the ssl folder may vary depending on the specific requirements of your system, so you should verify that the context specified in the command above is correct for your installation before applying it.

What is the difference between linux context and user ownership and permission?

In Linux, the ownership and permissions of files and directories are determined by the user and group ownership, as well as the file permissions (read, write, and execute) that are set for the user, group, and others.

On the other hand, the security context refers to a set of security-related attributes that are assigned to a file, process, or other system object. In SELinux, the security context is used to enforce security policies that go beyond the traditional file and process permissions, providing an additional layer of security to the system.

So, the difference between the two is that file ownership, group ownership, and file permissions are basic file and process permissions that determine who can access a file or directory and what they can do with it. The security context, on the other hand, is used to enforce more fine-grained and comprehensive security policies in systems that have SELinux enabled.

In short, the security context is used to enforce security policies in addition to traditional file and process permissions, while the user, group, and file permissions are the basic file and process permissions used to control access to files and directories in Linux systems.