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chcon – Modify the security context of an object (file)

The chcon command is used to modify the security context of a file or directory in a Linux system. The security context of a file is a set of metadata that includes the SELinux user, role, type, and level. This metadata is used by SELinux to determine the access control policies for the file. The chcon command can be used to change the SELinux user, role, type, or level of a file, which can be useful in situations where the default security context of a file is not appropriate.

Overview

The syntax for the chcon command is as follows:

chcon [OPTION]... CONTEXT FILE...

Where OPTION is an optional argument that modifies the behavior of the command, CONTEXT is the new SELinux context that you want to set for the file, and FILE is the path to the file or directory that you want to modify.

Here are some examples of how to use the chcon command:

  • To change the SELinux context of a file to httpd_sys_content_t, you can use the following command: 
    chcon -t httpd_sys_content_t /var/www/html/index.html
  • To recursively change the SELinux context of all files and directories under /var/www/html to httpd_sys_content_t, you can use the following command: 
    chcon -R -t httpd_sys_content_t /var/www/html
  • To change the SELinux context of a file to a specific user and role, you can use the following command: 
    chcon -u user_u -r role_r /path/to/file
  • To change the SELinux context of a file to a specific level, you can use the following command: 
    chcon -l s0 /path/to/file

Specific use cases

Here are some specific use cases where the chcon command can be useful:

  • When you need to change the SELinux context of a file to allow it to be accessed by a particular process or service.
  • When you need to change the SELinux context of a file to allow it to be accessed by a user or role that is not allowed by the default context.
  • When you need to change the SELinux context of a file to allow it to be accessed by a different security level.

Options

Here are the available options for the chcon command:

Option Description
-h, --no-dereference Do not follow symbolic links
-r ROLE, --role=ROLE Set the SELinux role
-t TYPE, --type=TYPE Set the SELinux type
-u USER, --user=USER Set the SELinux user
-v, --verbose Verbosely describe the action taken
-R, --recursive Recursively change the SELinux context of files and directories

Troubleshooting tips

Here are some troubleshooting tips for the chcon command:

  • If you get a “Operation not supported” error when trying to change the SELinux context of a file, it may be because SELinux is disabled on your system. You can check if SELinux is enabled by running the sestatus command.
  • If you get a “Permission denied” error when trying to change the SELinux context of a file, it may be because you do not have permission to modify the SELinux context. You can try running the command with sudo or as the root user.

Notes

Here are some additional notes about the chcon command:

  • The chcon command only changes the SELinux context of a file temporarily. If you want to make the change permanent, you need to use the semanage command to modify the SELinux policy.
  • Changing the SELinux context of a file can have unintended consequences and may cause the file to become inaccessible or cause other security issues. It is recommended that you test any changes in a non-production environment before making them in a production environment.

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