Ansible - Working with immutable files

You could harden / obfuscate your system by making important files immutable such as the '/etc/sssd/sssd.conf' or '/etc/selinux/config' to prevent automatic changes to these files. I'll template these using ansible to have a deployment workflow so that all my systems are equal and I can make changes in a deployment fashion.

Here are some tasks to give you a basic idea:

 - name: selinux conig immutable block  
   block:          
     - name: configure selinux config  
       template:      
         src: templates/etc/selinux/config.j2  
         dest: /etc/selinux/config  
         owner: root    
         group: root    
         mode: '0644'    
       tags:        
         - selinux_config     
     - name: set immutable attribute  
       file:        
         path: /etc/selinux/config  
         attr: '+i'     
   rescue:         
     - name: unset immutable attribute  
       file:        
         path: /etc/selinux/config  
         attr: '-i'     
     - name: configure selinux config  
       template:      
         src: templates/etc/selinux/config.j2  
         dest: /etc/selinux/config  
         owner: root    
         group: root    
         mode: '0644'    
       tags:        
         - selinux_config     
     - name: set immutable attribute  
       file:        
         path: /etc/selinux/config  
         attr: '+i'

Another example templating '/etc/sssd/sssd.conf':

 - name: sssd config immutable block  
   block:         
     - name: configure sssd properly  
       template:     
         src: roles/base/templates/etc/sssd/sssd.conf.j2  
         dest: /etc/sssd/sssd.conf  
         owner: root   
         group: root   
         mode: '0600'   
       notify: restart sssd.service  
     - name: set immutable attribute  
       file:       
         path: /etc/sssd/sssd.conf  
         attr: '+i'    
   rescue:        
     - name: unset immutable attribute  
       file:       
         path: /etc/sssd/sssd.conf  
         attr: '-i'    
     - name: configure sssd properly  
       template:     
         src: roles/base/templates/etc/sssd/sssd.conf.j2  
         dest: /etc/sssd/sssd.conf  
         owner: root   
         group: root   
         mode: '0600'   
       notify: restart sssd.service  
     - name: set immutable attribute  
       file:       
         path: /etc/sssd/sssd.conf  
         attr: '+i'

This will try to template the file and return 'OK' if everything is as it's declared. If that's not the case, however, it will return a failed and jump to the block's rescue which

unsets the immutable bit
templates the file and notifies the handler if defined
sets the immutable bit

At this point, this is more of an 'extra-mile' approach and might not be useful in every deployment.

Feel free to comment and / or suggest a topic.

Comments

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