SELinux contexts and labels¶
Viewing SELinux Contexts Example of viewing SELinux context for a process using ps command Listing SELinux Types or Domains Explanation of SELinux type security property Example of listing SELinux types associated with MySQL directories and files
SELinux context is like a label that tells the system how to handle files, processes, and other resources. For example, it determines which processes can access certain files and what actions they can perform on them. Understanding SELinux context helps you know how your applications interact with the system and ensures that they have the necessary permissions to function correctly. It’s like giving each item on your computer a tag that says what it is and what it’s allowed to do. So when your application tries to access a file, SELinux checks its context to see if it’s allowed. If the context matches what’s expected, the action is allowed; if not, it’s denied. So knowing the SELinux context is essential for managing security and troubleshooting issues on your system.
Viewing SELinux context for a process using ps command¶
To view the SELinux context for a process using the ps command, you can add the -Z option to display the context information. Here’s how you can do it:
$ ps -eZ | grep <process_name>
Replace <process_name> with the process name you want to check. For example, if you want to see the SELinux context for the MySQL process, you would use:
$ ps -eZ | grep mysqld
The output displays the SELinux context for the specified process and typically consists of four parts: user, role, type (or domain), and sensitivity level.
Expected output
system_u:system_r:mysqld_t:s0 3356 ? 00:00:01 mysqld
system_urepresents the user context.system_rrepresents the role context.mysqld_trepresents the type (or domain) context.s0represents the sensitivity level.
This information helps you understand how SELinux enforces security policies for the specified process.
List SELinux Types or Domains¶
SELinux types or domains categorize different resources on the system, such as files, directories, and processes. Each type or domain has specific permissions and restrictions associated with it, determining how resources interact with each other. To list SELinux types or domains associated with files, you can use the ls command with the -Z option. For example:
$ ls -laZ /var/lib/mysql
Expected output
drwxr-x--x. mysql mysql system_u:object_r:mysqld_db_t:s0 mysql
drwxr-x---. mysql mysql system_u:object_r:mysqld_db_t:s0 mysql-files
drwxr-x---. mysql mysql system_u:object_r:mysqld_db_t:s0 mysql-keyring
This command lists the files and directories under /var/lib/mysql along with their SELinux context, which includes the type or domain associated with each resource. Understanding these types or domains helps manage SELinux policies and ensure proper access control for MySQL-related resources.
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