How to use SELINUX (No I don't mean turn it off)
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Why do we turn off NSA-grade security features? Well early on, SELINUX was complex and confusing. However, the pains of dealing with SELINUX are long gone. In fact, the tools for working with SELINUX have long improved are now so easy, anyone can configure the security layer. Even one bad chmod on a server can leave you vulnerable. However, when SELINUX is running, rogue processes will be prevented from running havoc. You'll learn how easy it is to use SELINUX and how (with little effort) you can configure and troubleshoot this amazing security feature. Stop leaving gaps in your infrastructure and turn it back on.
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How to use SELINUX (No I don't mean turn it off)
- 1. HOWTOUSE SELINUX CHUCK REEVES @MANCHUCK NO I DON'T MEAN TURN IT OFF
- 2. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF ABOUT ▸ Built using Kernel Modules ▸ More permissions than CRUD and Access ▸ Allows Multi-Level Security using BLP and Biba Models ▸ Permissions set on the inode instead of the file ▸ Mandatory Access Control (MAC)
- 3. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 4. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF WHAT YOU NEED TO KNOW ▸ Each iNode is given a single context ▸ Each context identifies a user, role, type and level ▸ SELINUX then allows (or denies) access using the context with a policy ▸ Decision is cached in the Access Vector Cache (AVC) ▸ Decisions is made after the DAC access is checked
- 5. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF WHAT YOU NEED TO KNOW ▸ SELINUX manages: ▸ Users ▸ Sockets ▸ Memory ▸ Directories ▸ TCP/UDP connections
- 6. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF PROCESS TYPES ▸ Confined ▸ Runs in own domain (role) ▸ Resources are limited to the roles and policy ▸ Un-Confined ▸ fallback to the DAC policies
- 7. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF CONTEXTS ▸ Policy checks context of inode for access ▸ "If a process is running with <context_foo> then anything with <context_foo_type> is allowed access" ▸ Four parts: user, role, type and level (optional)
- 8. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF CONTEXTS ▸ Set automatically based on the parent context (mostly) ▸ RPM ▸ Management tools (ansible, chef, puppet) ▸ When a File transitions (moving an uploaded file) ▸ By the sysadmin with chcon, restorecon
- 9. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF FINDING CONTEXT ls -alZ /home
- 10. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF FINDING CONTEXT ps -Z
- 11. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF BOOLEANS ▸ On off settings for policies ▸ Allow HTTPD to make network connections ▸ Allow FTP to access home directories ▸ Overcomes issues with over labeling contexts
- 12. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF TURNING IT BACK ON ▸ TARGETED ▸ PERMISSIVE ▸ DISABLED (You already know this one)
- 13. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF TURNING IT BACK ON <edit> /etc/selinux/config
- 14. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF TURNING IT BACK ON sudo yum install setroubleshoot setroubleshoot-server sudo service auditd restart
- 15. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF TURNING IT BACK ON ls -alZ sudo touch /.autorelabel
- 16. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF TURNING IT BACK ON ls -alZ
- 17. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 18. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 19. ZendCon 2016 TEXT TROUBLESHOOTING EXAMPLE: DATABASE tail -f /var/log/audit/audit.log
- 20. ZendCon 2016 TEXT TROUBLESHOOTING EXAMPLE: DATABASE tail -f /var/log/messages
- 21. ZendCon 2016 TEXT TROUBLESHOOTING EXAMPLE: DATABASE sealert -l <message id>
- 22. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF BOOLEANS setsebool -P httpd_can_network_connect 1
- 23. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF BOOLEANS semanage boolean -l | grep httpd_enable_ftp_server
- 24. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF BOOLEANS getsebool -a getsebool <boolean>
- 25. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF BOOLEANS semanage boolean -l | grep httpd_enable_ftp_server
- 26. ZendCon 2016 TEXT TROUBLESHOOTING EXAMPLE: FILE UPLOAD ls -Z
- 27. ZendCon 2016 TEXT TROUBLESHOOTING EXAMPLE: FILE UPLOAD sealert -l <message id>
- 28. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF SETTING CONTEXT chcon -R -t httpd_sys_content_t web/ ls -Z web
- 29. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF SETTING CONTEXT mkdir web/ touch web/file{1,2,3} ls -Z web
- 30. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 31. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 32. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF
- 33. ZendCon 2016 HOW TO USE SELINUX - NO I DON'T MEAN TURN IT OFF RESOURCES ▸ RedHat Documentation for SELINUX: https://access.redhat.com/ documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Security- Enhanced_Linux/index.html ▸ Servers for Hackers, Batteling SELINUX: https://serversforhackers.com/video/ battling-selinux-cast ▸ SELinux For Mere Mortals: https://www.youtube.com/watch?v=MxjenQ31b70